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Forest-Use History and the Soils and Vegetation of a Lowland Forest in Bolivia


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FOREST-USE HISTORY AND THE SOIL S AND VEGETATION OF A LOWLAND FOREST IN BOLIVIA By CLEA LUCRECIA PAZ RIVERA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2003

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Copyright 2003 by Clea Lucrecia Paz Rivera

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To the memory of my grandfather Carlos Alfredo Rivera, whose love and inspiration have accompanied me through the years.

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ACKNOWLEDGMENTS Numerous individuals and institutions deserve acknowledgment for their contributions to this thesis. First, I am indebted to my advisor Francis E. Jack Putz, for his mentorship, persistence, enthusiasm, and interest in Bolivia. Also at the University of Florida, I would like to thank my other committee members Kaoru Kitajima and Nigel Smith for their advice. I also wish to thank Nick Comerford for his guidance on soil analysis, Mary Mcleod, Jennie del Marco for helping me in the laboratory. The Latin American Scholarship Program of American Universities (LASPAU/Fulbright), Proyecto de Manejo Forestal Sostenible (BOLFOR), the School of Natural Resources and Environment, the Department of Botany, and the Tropical Conservation and Development Program at the University of Florida, all provided generous financial and logistical support for my graduate studies. My excellent field guide, Jos Chuvia, deserves praise for his boundless energy and rich knowledge of the forest. I also thank Marielos Pea-Claros, Joaqun Justiniano, and Todd Fredericksen at BOLFOR; Narel Paniagua at the Herbario Nacional de Bolivia; and Sergio Calla (for his archaeological work). The BOLFOR project staff gave me technical and logistic support in Santa Cruz. I thank my labmates at the University of Florida (Bonifacio Mostacedo Geoffrey Blate, and William Grauel) who were always available for grammatical consultations, statistical guidance, editing, and comic relief. Amy Miller helped me in many ways, from editing, to sharing the challenges of thesis writing, to being a dear iv

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friend. Catherine Cardels and Eddie Watkins provided both friendship and draft reviews. I especially thank my parents and siblings for their inspiration and support; and for taking care of my son while I was in the field. My son Santiago shared with me his beauty and companionship, and I thank him for his forgiveness when I could not give him the time and attention he deserved. Last but not least, I could not have completed this work without the constant love, care, support, and warm meals from my husband Stephen. v

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TABLE OF CONTENTS Page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES...........................................................................................................viii LIST OF FIGURES...........................................................................................................ix ABSTRACT.......................................................................................................................xi CHAPTER 1 ANTHROPOGENIC SOILS OF A FORESTRY CONCESSION IN LOWLAND BOLIVIA......................................................................................................................1 Introduction...................................................................................................................1 History of Study Area...................................................................................................4 Spaniards...............................................................................................................5 Missionary Activity...............................................................................................6 Population Density................................................................................................7 Land and Resource Use.........................................................................................8 Methods......................................................................................................................11 Study Site.............................................................................................................11 Soil Sampling and Analysis.................................................................................12 Results.........................................................................................................................13 Area, Shape, and Location of Anthropogenic Soil Patches.................................13 Soil Chemistry.....................................................................................................15 Discussion...................................................................................................................16 Area, Shape, and Location of Anthropogenic Soil Patches.................................16 Soil Chemistry.....................................................................................................18 Implications of Anthropogenic Influences on La Chonta Forest........................20 2 DISTRIBUTION OF USEFUL TREE SPECIES IN RELATION TO HISTORICAL HUMAN INFLUENCES ON THE FOREST OF A TIMBER CONCESSION IN LOWLAND BOLIVIA...............................................................................................28 Introduction.................................................................................................................28 Methods......................................................................................................................31 Study Site.............................................................................................................31 Species Selection.................................................................................................32 vi

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Species Sampling.................................................................................................33 Data Analysis.......................................................................................................34 Results.........................................................................................................................34 Discussion...................................................................................................................36 REFERENCES..................................................................................................................47 BIOGRAPHICAL SKETCH.............................................................................................56 vii

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LIST OF TABLES Table page 1-1. Distribution of tierra negra (TN) sites in a 216 ha sample area...............................22 1-2. Mean values ( one SE) of tierra negra, tierra morena, and non-tierrra negra soil properties at two depths (0-10 and 40-50 cm) with sites as replicates.....................22 1-3. Statistical contrast of the three soil types at two depths............................................23 2-1. Characteristics of tree species that are used by humans and selected for study in La Chonta......................................................................................................................41 2-2. Maximum diameters, mean growth rates for trees > 10 cm DBH and mean annual diameter increment (MAI based on 3 years of data) of the selected tree species in La Chonta.................................................................................................................43 viii

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LIST OF FIGURES Figure page 1-1. Location of the study site in lowland Bolivia............................................................24 1-2. Location and size of the TN sites in La Chonta........................................................25 1-3. Spatial distribution of tierra negra (TN) in relation to tierra morena (MO) and non-tierra negra (NTN)...........................................................................................26 1-4. Mean values (+ 1 SE) for tierra negra (TN, N = 10), tierra morena (MO, N = 3,), and non-tierra negra (NTN, N = 6) at two different depths for a) pH, b) organic matter content, c) extractable phosphorous, d) extractable calcium, and e) extractable potassium...............................................................................................27 2-1. Relative abundances ( 1 SE) of the selected useful tree species among the three different soil types....................................................................................................46 ix

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science FOREST-USE HISTORY AND THE SOILS AND VEGETATION OF A LOWLAND FOREST IN BOLIVIA By Clea Lucrecia Paz Rivera December 2003 Chair: Francis E. Putz Major Department: Natural Resources and Environment Land-use practices can dramatically affect soils and vegetation, even centuries after they cease. In Amazonia, soils enriched by nutrient and charcoal additions are indicators of ancient village sites and old agricultural plots. To ascertain whether past land-use practices also result in local enrichment with useful plants, I studied the anthropogenic soils and associated vegetation of a forestry concession in the Department of Santa Cruz, Bolivia. I compared the chemical properties of anthropogenic soils with surrounding soils and then compared the concentration of useful tree species on and off of anthropogenic soil areas. Two types of anthropogenic soils were identified in the research area: tierra negra (TN) darkened with charcoal fragments and with abundant buried pottery shards; and tierra morena (MO), somewhat darkened but with little or no pottery. In an area of 216ha, nine TN soil patches (0.3 to 10 ha) and three MO soil patches were identified and compared with six nearby non-anthropogenic soils (inceptisols), which are referred to as xi

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non-tierra negra (NTN). The abundance of seventeen useful tree species was measured in plots on the three soil types (TN, MO, and NTN). Results of this study demonstrate that La Chontas soils retain strong effects of past human activities that ceased 300 to 400 years ago, when the area was abandoned. The TN soils cover approximately 20% of La Chonta and are chemically different from the MO and NTN soils but all were circum neutral in pH, high in Ca content, and similar in total P. The TN soils had significantly higher contents of organic matter, extractable P, and extractable Ca than did NTN soils; and higher pH and extractable P than did MO soils. The MO soils had organic matter and Ca content similar to that of NTN soils and significantly less extractable K. Overall, TN soils had higher nutrient content than surrounding soils, both at the surface (0-10 cm) and deeper in the soil (40-50 cm). Of the seventeen useful tree species studied, none were concentrated in TN areas. This unexpected result may be due to interactions between local dispersal agents and natural disturbances that masked historical patterns. Alternatively, past inhabitants of La Chonta may have managed or cultivated their useful tree species beyond anthropogenic soil areas. In any case, the influence of past land-use practices on plant species composition is not apparent in La Chonta. xii

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CHAPTER 1 ANTHROPOGENIC SOILS OF A FORESTRY CONCESSION IN LOWLAND BOLIVIA Introduction Land-use history has played important roles in shaping modern landscapes and ecosystems. This study examines the history of the currently uninhabited timber concession of La Chonta, in the Guarayos Province of lowland Bolivia, and the effects of past land-use practices on its soil properties. Humans are now recognized as having dramatically influenced Amazon Basin forests (Roosevelt et al. 1991, Denevan 1992b, Bale 1994, Smith 1999). Forests once considered pristine or virgin are increasingly viewed as resulting from regeneration after the cessation of human activities (Lentz 2000b). Human influences are to be expected, given that archeological studies reveal that humans were present in Amazonia at least 12,000 years ago (Roosevelt et al. 1991). Although hotly debated, estimates of pre-Columbian population density in Amazonia are all high. For example, Dobyns (1966) estimated 6 million for all of tropical South America, whereas Denevan (1992a) estimated a population of 8.6 million in lowland South America alone, a number that declined by 90% within 100 years after European contact. pre-Columbian societies in the Amazon have affected the region at all scales up to the landscape level, through constructing raised fields, earthen causeways, and hydraulic earthworks (Denevan 1966, 2001, Lippi 1988, Erickson 2000, Roosevelt 2000) as well as through use of more subtle forest-management practices (Posey 1985, Bale 1994, Denevan 1998, Peters 2000). 1

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2 Past human disturbances may have influenced several attributes of present-day Neotropical landscapes (Bale 1994, Lentz 2000a). For example, Peters (2000) and Erickson (2000) working in Central American forests and Amazonian savannas respectively, showed that modern vegetation in their study sites was greatly altered by direct and indirect enrichment by pre-Columbian societies. Direct enrichment of useful plant species occurred through manipulations such as planting or thinning, while indirect enrichment was the creation or alteration of habitats such as those conducive to colonization by early successional species. Despite the extent of landscape alterations by pre-Columbian societies, land-use history in dynamic tropical ecosystems can be difficult to unravel because ecological processes such as bioturbation, heavy rainfall, and rapid plant growth can obscure evidence of earlier human activities (Stahl 1995). Nevertheless, soils generally reflect human-induced alterations for long periods of time and therefore can serve as useful indicators of past land-use practices (Glaser 2002). In Amazonia, dark anthropogenic soils (referred to as tierra negra in Bolivia, and terra preta and terra preta do Indio in Brazil) occur in patches from 0.5 to 300 ha, typically embedded in a matrix of infertile soils (mainly oxisols and ultisols). Terra preta are defined by a distinctive anthropogenic epipedon with intermixed potsherds and celts (Sombroek 1966, Smith 1980, Woods et al. 2000, Glaser et al. 2001). High organic matter and elevated nutrient contents (especially phosphorous, calcium, potassium, and sodium) distinguish the Amazonian anthropogenic soils from those in their surroundings (Smith 1980, Woods et al. 2000, Glaser et al. 2001, McCann et al. 2001).

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3 Although the origin, distribution, and use of Amazonian anthropogenic soils are still unclear, it seems that fire was the most important factor in their formation (Woods et al. 2000). Apparently incorporation of charcoal (black carbon) and wood ash increases nutrient retention capacity, cation exchange capacity (CEC), and soil pH (Woods et al. 2000); ant it stabilizes soil organic matter (SOM) while reduces nutrient leaching from soils (Glaser et al. 2000 and 2001). Charcoal is also extremely resistant to weathering and can persist in soil for millennia (Rainho Texeira et al. 2002), thereby contributing to the maintenance of anthropogenic soil properties through time. The second factor related to the formation of these soils was the incorporation of household waste, such us food remains, shells, bones, feces, blood, and urine, all of which increased soil nutrient content (Smith 1980, McCann et al. 2001). Initially, anthropogenic soils were reported on floodplains, especially on river bluffs along the main Amazon river (Sombroek 1966, Smith 1980). More recently, large areas of terra preta have been reported in terra firme, or upland forests (Heckenberger et al. 1999), and in floodplains along tributaries of the Amazon river (McCann et al. 2001). In any case, most of the reported occurrences of anthropogenic soils in South America to date are near permanent sources of water. Two kinds of anthropogenic soils, terra preta and terra mulata, have been described as being clearly distinguishable in Brazil (Sombroek et al. 2002). Terra preta appears in former human settlements and, besides being enriched in nutrients and charcoal, is always associated with pottery and cultural debris (Smith 1980, Heckenberger et al. 1999). Terra mulata is thought to have developed in permanent agricultural fields, enriched by long-term soil-management practices such as mulching

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4 and infield burning (Denevan 1996, Woods et al. 2000, McCann et al. 2001). Despite some recent advances in our understanding, the nature and characteristics of pre Columbian agriculture that originated terra mulata still remain little known. High nutrient levels of anthropogenic soils and the different ways vegetation was managed in and surrounding these areas are expected to influence the vegetation that either persists or colonizes the sites after their abandonment. In any event, it is obvious that the original vegetation in these areas was substantially modified by humans, and that certain species were either favored or introduced from other areas, perhaps permanently altering local species composition. This study has two objectives. The first is to reconstruct the history of the Guarayos area through review of bibliographic sources. The second is to describe the anthropogenic soils of La Chonta and compare soil properties between anthropogenic and surrounding soils. History of Study Area Unraveling the history of human activities can help us understand the soils, vegetation, landscape, and successional patterns in modern ecosystems (Glenn 1999). Given that there are few published historical accounts of Guarayos, colonial archives and historical reports from nearby regions were used to reconstruct its probable land-use patterns and settlement history (Orbigny 1835, Cards 1886). Guarayos is a biological and cultural transitional region with influences from the humid forests of Amazonia to the north, the drier forests of Chiquitos (Chiquitania) and Chaco to the southeast, and the savannas of Mojos (Moxos) to the west (Figure 1-1). Both Mojos and Chiquitos were explored and settled by Europeans earlier than Guarayos

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5 and as a result there is relatively more historical information about them, but the histories of the three regions are intertwined. Although the Swedish anthropologist Erland Nordenskild excavated in Guarayos in the early twentieth century (Nordenskild 1930), the secondary urn burials (urns containing fleshless bones) he unearthed have apparently not been dated. I am aware of no other pre-contact archeological data. Early reports from European explorers and missionaries provide the only descriptions of cultural and ecological conditions following European contact. The Guarayos region is believed to have been inhabited by the Guarayo Indians, who likely migrated from Paraguay and inhabited the Guarayos region since at least 1400 (Orbigny 1835, Cards 1886). The Guarayo language is of the Tupi-Guaran family and is closely related to Guaran (Cards 1886), spoken by the Guaran Indians who historically inhabited the Chaco region of southeastern Bolivia and northern Argentina and Paraguay. Despite their common language, the Guarayo and Guaran have marked cultural and physical differences, suggesting that if the two groups were once more closely related, their separation took place long before European contact (Finot 1939). Spaniards The region now referred to as Guarayos and inhabited primarily by the Guarayo was probably first encountered by Europeans during a Spanish expedition that set out from Asuncin, Paraguay in the 1540s. The objective of this and numerous similar explorations was to find the tierra ricas of indigenous legends that described the treasures and gold of El Dorado, El Gran Paititi, or El Gran Mojos, this last believed at one time to be located north of Chiquitos (Finot 1939).

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6 Apparently the first expedition to pass through the Guarayos region was led by the Spanish captain uflo de Chvez, who left Asuncin in 1558 with 150 Spanish soldiers and 1500 Guaran Indians. His mission was to establish a new town in the Xarayes marshes (located in Mato Grosso, Brazil, and southeastern Bolivia) but upon arrival, he found the area unsuitable for settlement and decided to continue the expedition, traveling west and northwest in search of El Dorado. Although maps that reconstruct uflo de Chvezs expeditions show the route passing through Guarayos region, there is no direct mention of Guarayo people in the chronicles of the trip, contrasting with the extensive description of surrounding indigenous groups such as Chiquito, Chiriguano, Mojo, and others (Levillier 1976). According to the interpretation of Levillier (1976), Chvez encountered the Guarayo indians north of latitude 16 South when he was attacked by an unidentified indigenous group living at a heavily fortified settlement. Chvez, uncertain of victory, turned away from the settlement and returned to Chiquitos. In the late 17th century the Spaniards approach to conquest shifted from one of broad exploration to a more systematic effort at populating areas where they had been able to establish a presence. Because of its distance from Santa Cruz de al Sierra, the Guarayos region was not colonized and there is little mention of the area until the 18th century. Missionary Activity Religious missionaries entered South America with objectives quite different from those of the explorersin place of gold they sought the souls of indigenous infieles. Unlike the explorers, who in most cases passed quickly over through the landscape, missionaries had sustained contact with local people. Jesuit missionaries arrived on the

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7 continent in the late 1500s and in the Bolivian lowlands the first reducciones (Jesuit and Franciscan missions) were established roughly a century later. In Mojos, the first mission (Loreto) was established in 1682; San Francisco Javier in Chiquitos was established in 1691. Between 1700 and 1845, there were five attempts, first by Jesuits and later by Franciscans, to establish reducciones among the Guarayo. The first four failed at retaining significant numbers of people. It was only later (1845) that thousands of Guarayo were concentrated in several towns in the region, including the present-day capital, Ascencin, founded by Franciscans in 1826. Population Density There are apparently no published estimates of population density in Guarayos before the missionary period. Nevertheless, as mentioned above, several lines of evidence indicate that the native population was high in pre-Columbian times. For example, near Guarayos in the savannas of Mojos, Jesuit missionaries reported 37 related yet distinct indigenous groups in 1696 (Chvez 1986). Denevan estimated a native population of 350,000 in the same region and calculated that that number decreased to 100,000 by the 1690s as a consequence of epidemic diseases (Denevan 1992a). Spanish chronicles of expeditions from Paraguay to Santa Cruz and Mojos in the late 1500s and early 1600s reported encounters with hundreds of indigenous groups. Reports from this time stated that the Guaran and Guaran-related groups, including Chiriguano, Sirion, and Itantines, tended to be the more populous and bellicose (Finot 1939, Pinckert-Justiniano 1991). After Gregorio Salvatierra, a Franciscan missionary, visited four mission towns in 1794 (Asencin, Yaguar, Yota and Urubich), he estimated a population between 3000

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8 and 4000 in the region (Cards 1886). DOrbingy, who visited Asencin de Guarayos in 1831, estimated 1,000 Guarayo Indians in the area (Orbigny 1835). During the mission period, the Jesuits concentrated hundreds of families in towns, but they repeatedly reported the existence of many wild Guarayo living in the forest who maintained only sporadic contact with people living in towns. The Jesuits carried out several recruitment expeditions into forested areas and reported dispersed families along their route and returned with groups of varied sizes, the last (1825) returning with 200 Guarayo (Cards 1886). The population estimates of DOrbigny and Salvatierra were likely gross underestimates because they were based only on the established mission settlements, and did not include people dispersed through the forest. It also seems relevant to note that these censuses were carried out more than 200 years after the arrival of Europeans to the region, when populations were probably greatly diminished by introduced diseases such as smallpox and the flu. The impact diseases brought by Europeans was reported in Chiquitos by DOrbigny who noted that half of the Chiquitano residing in San Javier died from smallpox in 1825. Similarly Cards mentioned that a malignous fever attacked and killed hundreds of Guarayo in 1845. Land and Resource Use Archaeologists and ecologists are currently trying to understand land-use practices prior to European contact. Descriptions by Jesuits and Franciscans, admittedly biased by their belief that indigenous peoples were ignorant savages, and reports by DOrbingy, provide the earliest reports of the land-use practices and customs. Unfortunately, the land-use practices they described already reflected European influences, the most important of these being the introduction of metal tools. Metal tools are several times

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9 more efficient for cutting trees than stone tools (the ratio varies from 10 to 1 to 23 to 1, Denevan 1992c), allowing faster forest clearing, and the development of long fallow shifting cultivation. Due to the inefficiency of stone axes, some authors claim that pre-Columbian agriculture was based in home gardens and permanent crop fields instead of modern shifting cultivation with short cropping periods followed by long forest fallows, which would be too labor intensive to be a common agricultural practice (Denevan 1998). DOrbigny, who visited Asencin de Guarayos in 1823, provides the first description of anthropogenic soils, reporting black fields ready to be planted. After his arrival he described the Guarayo living in mission towns with the Franciscans as having maintained more of their customs and otherwise were less influenced by Europeans than the Chiquitano. DOrbigny asserts that agriculture was their main food producing activity, and that hunting was more of a past time than an essential activity (this contradicts the missionaries descriptions, who assert the Guarayo were mainly hunters). DOrbignys claims, however, are corroborated by the great number of religious ceremonies devoted to Tamoi (grandfather), the most important god of the Guarayo, who was believed to have taught them agriculture. When DOrbigny arrived in the region, the Guarayo had a well-developed shifting cultivation system centered on squash, corn, yucca, papaya, pineapples, and sugar cane (an old world crop introduced by the Jesuits in the early 1800s) using metal axes. Agricultural fields were managed by the whole community while they lived divided in small families in octagonal-shaped cabaas roofed with palm leaves, similar to those used by the Caribe of Central America. They reportedly planted near the houses a sacred tree called turienda (apparently Ceiba pentandra), which they claimed was used by their gods to come down and take them

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10 when they died. They wore clothes made of the bibosi tree bark (Ficus spp.) and painted their bodies with achiote (Bixa orellana; Orbigny 1835). Cards, a Franciscan missionary who visited the area between 1883 and 1884, provides a similar description of the Guarayo agricultural system (Cards 1886). He described low, forested, rolling hills intermixed with forested wetlands to the south, extensive, flat, lowland forests to the north, and to the west, beyond several leguas (leagues, approximately four to seven kilometers) of forest, began the huge savannas of Mojos region. He also observed that the Ro Blanco (Figure 1-1), was navigable to Carmen del Mojos whereas today, the river is navigable only seasonally, and then by small canoe. Cards described the Guarayo as primarily hunters and fishers, with their principal crops being corn, yucca, plantain (an old world crop), beans, peanuts, and squash. Spider monkey was their preferred meat and chicha, a fermented beverage made of corn or yucca, was their most common beverage. The different views on human cultures and ecology in the Guarayos region provided by early explorers, missionaries, and scientists, offer an opportunity to consider the dramatic changes that took place over the previous centuries. Although Guarayos was at first a region on the periphery of European activities in Bolivia, it was still affected, finally to a large degree, by the arrival of explorers and missionaries. Unfortunately, the accounts of DOrbigny, Cards, and others begin at least two centuries after the arrival of Europeans to the region, sufficient time for forests to regenerate on abandoned sites following the massive indigenous population declines that occurred throughout the Americas (Denevan 1992a, Block 1994). This lapse in time prevents us from understanding pre-colonial landscapes that may have been quite different from

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11 those DOrbigny, Cards, and others observed. For instance, if native populations were large before contact, the landscape was likely much less forested than it was more than a century after the population crash. Study of the anthropogenic soils of La Chonta affords an opportunity to piece together the past at a much different level of detail than that made possible by historical and religious records. It allows us to estimate the area of long-abandoned settlements or cultivated plots, and the effects of human induced soil alterations on soil chemistry and plant species composition. Methods Study Site This study was conducted in La Chonta, a lowland tropical forest in Guarayos Province, Department of Santa Cruz, Bolivia (15'S, 62'W, Figure 1-1). A 100,000 ha private timber concession since 1974, the area was selectively logged for mahogany (Swietenia macrophylla) and tropical cedar (Cedrela odorata) for the first decade after its establishment. When mahogany was depleted, the focus shifted to other species and today loggers extract up to a dozen species. La Chonta was certified by the Forest Stewardship Council as well managed in 1998. A long-term silvicultural research project was started in La Chonta in 2000 as part of the BOLFOR Sustainable Forest Management Project (Putz et al. in press). The vegetation of La Chonta is classified as subtropical humid forest (Holdridge 1971), with mean annual temperature of 24.5C and mean annual rainfall of ca. 1500 mm. The canopy is semideciduous and fairly open, with heights of mature forests of 20 to 25 m. Common canopy tree species are characteristic of humid forests and include Hura crepitans and Pseudolmedia laevis (Navarro and Maldonado 2002). Lianas are

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12 abundant and dominate disturbed areas (Alvira et al. 2003). The area has a long history of both human-induced and natural fires, but there were no signs of recent fires in my study area. The region has numerous ephemeral streams, and the rivers Blanco and Negro border the peripheries of the concession (Figure 1-1). Soil Sampling and Analysis An area of 216 ha was surveyed for anthropogenic soils by sampling at 200 m intervals along walking trails separated by 150 m. The trails delimit research plots in La Chonta and are kept clear of vegetation; changes in soil color and type were easily recognized. Surface soil was cursorily examined and soil color was recorded using a Munsell Soil Color Chart. When soil color darkened markedly, sampling intervals were reduced to 100 m and examined more thoroughly for charcoal and pottery. Soils were classified as tierra negra (TN) when extremely dark in color (7.5 YR 3/1 and 2.5/1; dark brown and very dark brown) and both charcoal and pottery sherds were present. Soils that were somewhat darkened (7.5 YR 4/3 3/2, brown to dark brown) but with little or no pottery were classified as tierra morena (MO). Soils with no apparent indicators of anthropogenic influences were classified as non-tierra negra (NTN), and are tentatively classified as inceptisols (Navarro 2002). When TN soils were encountered, their area was estimated by sampling in the four cardinal directions every 20 m with a soil auger until the patch limits were identified. Patch locations were recorded with a handheld Garmin GPS. Soil samples were taken from each of the TN and MO patches, and the surrounding NTN soils. From the approximate center of each patch, soil samples were taken at two depths (0-10 and 40-50 cm) at the corners of a 10x10 m square. Samples from each of the

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13 depths were mixed together and 200 g of each was air dried in the field and stored for laboratory analysis. As a preliminary archaeological assessment of the area, one test pit (1x1m3) was excavated in the central area of each TN site to quantify the abundance of pottery sherds and to determine the depth of the TN soils. During the early phase of this study, two large charcoal fragments that were found intermixed with abundant pottery sherds at 10 and 20 cm depths in an anthropogenic soil patch (tierra negra 3 Table 1-1) were submitted to Beta Analytic Laboratory for accelerator mass spectrometry (AMS) radio-carbon dating. In the laboratory, soil organic matter was estimated using the weight loss on ignition method (Nelson 1996). Total phosphorous (P) was measured colorimetrically after sulfuric acid digestion (Olsen and Sommers 1982). Extractable phosphorous was measured colorimetrically after a Mehlich double-acid solution (Olsen and Sommers 1982). Finally, extractable calcium (Ca), magnesium (Mg), and potassium (K) were assayed using atomic absorption (AA) following extraction in a Mehlic double-acid solution (Thomas 1982). To compare soil types, the chemical data were analyzed with a two-way ANOVA model using soil type (TN, MO and NTN) and depth as factors and sites as replicates. Results Area, Shape, and Location of Anthropogenic Soil Patches In an area of 216 ha, nine patches of tierra negra (TN, Table 1-1, Figure 1-2), three patches of tierra morena (MO), and six nearby (within 1 km) areas of non-tierra negra (NTN) soil were identified. The TN patches were commonly located on flat terraces within 200 m of streams that at least flow during the rainy season (Figure 1-3). TN patch sizes varied in La Chonta and were grouped in two categories: small circular patches

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14 (0.3-2.5 ha), and larger, irregular patches (5-10 ha). Mapping of the larger areas was not completed because they extended past the perimeters of the research plots. Within TN sites, I found areas with higher concentration of charcoal and pottery sherds, probably corresponding to kitchen middens (S. Palma, unpublished data). The cumulative area of the most prominently affected anthropogenic soils (TN) accounts for approximately 20% of the study area (Table 1-1, Figure 1-2). The patches of MO were 0.3-1.0 ha and tended to surround the TN sites (Figure 1-3). I did not quantitatively measure areas of MO but estimate them to cover an additional 5% of the area. The preliminary archaeological investigations carried out in TN soil pits revealed distinguishable layers, defined by abundant pottery sherds and charcoal, which differed between the small and large patches. In both patches sizes the surface 10 cm were dark in color but usually contained no pottery and charcoal, with the exception of areas disturbed by animals or roads. The small patches (0.3-1 ha) in general had one continuous stratum of dark soil from 10 to 30-45 cm depth with intermixed charcoal and pottery whereas the larger patches generally had two separated layers with anthropogenic traces, one at 10-40 cm depth and other at 45-75 cm depth. The 5 cm separation between the two anthropogenic layers in the large patches consisted of a layer of sandy-loam soil with large quartz crystals. The density of buried pottery sherds in the intensively inventoried soil pits varied from 19 to 187 pieces per m3. I also found solid pieces of macroscopic black carbon (between 1 and 5 cm size) from 10 to 75 cm soil depth in both the small and large patches. The two charcoal fragments found mixed with pottery in tierra negra site 3 at 10

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15 and 20 cm below the surface were AMS dated from 330 80 to 420 60 years BP respectively. Soil Chemistry The pH of soils in La Chonta were all high, averaging 7.2 in the TN soils, 6.4 in the MO soils and 7.2 in the NTN (Table 1-2); pH was significantly higher in TN and NTN soils than in the MO soils (P < 0.006, Figure 1-4a). Organic matter content at 10 and 50 cm depth averaged 5.7% and 2.6% in TN soils, 4.8% and 2.1% in MO soils, and 4.7% and 2.1% in NTN soils, being significantly higher in the TN soils than the NTN soils (P < 0.039, Figure 1-4b). Total phosphorous was relatively high in all three soil types while extractable phosphorous was relatively low. Total P was not significantly different among the three soil types and averaged 155-358 (Table 1-2) Extractable P content averaged 49.65 and 35.92 mg/kg (at 10 and 50 cm respectively) in TN soils, being significantly higher than MO soils at both depths and significantly higher than NTN at 50 cm (P < 0.015, Figure 1-4c). Extractable Ca was extremely high in all La Chonta soils, averaging (at 10 and 50 cm depths, respectively) 3179 and 1428 mg/kg in TN soils, 1975 and 587 mg/kg in MO soils and 2435 and 805 in NTN soils, being significantly higher in TN soils than NTN and MO soils (P < 0.002 Figure 1-4d). Extractable K was significantly higher in NTN soils and TN soils when compared to MO soils (P < 0.015, Figure 1-4e), averaging 94.36 and 62.54 mg/kg in TN soils, 57 and 28.39 mg/kg in MO soils, and 91.82 and 55.24 mg/kg in NTN soils (at 10 and 50 cm, respectively). All of the soil properties tested, with the exception of pH and total P, were significantly higher at 10 cm than at 50 cm depth (Table 1-3). Organic matter content,

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16 extractable P and extractable Ca were significantly higher in TN than MO and NTN at 50 cm depth (P < 0.015, P < 0.001, and P < 0.0001 respectively, Figure 1-4b, c, and d). Overall, the transitional MO soils had lower nutrient concentrations than NTN soils. Discussion Area, Shape, and Location of Anthropogenic Soil Patches In contrast with the majority of anthropogenic soil areas in the Amazon Basin (Sombroek 1966, Smith 1980, Heckenberger et al. 1999, Woods et al. 2000, McCann et al. 2001), the anthropogenic soils of La Chonta are located in an area lacking big rivers or wetlands. In fact, researchers and logging crews currently working in the area are faced with the hardship of bringing barrels of water long distances to their camps. The closest rivers, Ro Negro and Ro Blanco, are 14-30 km from the TN areas I mapped (Figure 1-1) and the water flow in La Chonta streams has ceased completely during the latter portions of the dry seasons (between May and October). Ancient village sites in the Brazilian Amazon described to date are mostly associated with large rivers (Roosevelt 1989, Smith 1980, McCann et al. 2001). However, a large terra preta site (200 ha) relatively far away from rivers (15 kilometers from the Amazon River floodplain) was reported in Comunidade Terra Preta, at km 55 of the Juriti-Tabatinga road in Par, Brazil (Smith 1999, p. 25). Further detailed analyses of the archaeology, pollen, and phytoliths in La Chonta are needed to determine if the water regime was the same when the area was last inhabited, and how the former inhabitants managed to provide themselves enough water to survive, given that I found no evidence of prehistoric wells or dams. The processes of settlement, abandonment, and reoccupation of the large patches of TN may help explain the great differences in patch size. Apparently the larger patches (5-10 ha) were occupied more than once (S. Palma, unpublished data), which makes the size

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17 of the patches an inaccurate indicator of village size, as suggested by Meggers (1995) for TN areas in the Brazilian Amazon. Alternatively, the larger patches could represent old agricultural plots in which forms of indigenous agriculture not currently used may have been practiced. Denevan (1992c), for example, suggests that management of house gardens and permanent plots of mixed annuals and perennials were common indigenous pre-Columbian agricultural practices. Nevertheless, more archaeological research is needed to determine precisely the land-use practices carried in the large areas of TN and MO. The two C-14 dates for charcoal that was mixed with pottery at 10 and 20 cm depth suggest tierra negra site 3 was inhabited between 300 and 400 years B.P, but do not indicate the prior duration of settlement. However, charcoal and pottery were present at deeper in the soil (to 75 cm) in other TN sites, consequently, a series of soil charcoal C-14 dates along several soil excavation units replicated in different archaeological sites in the area will be necessary to establish more precisely the sequence of human occupation of La Chonta. In this study, charcoal was found at greater depths than those Glaser et al. (2000) reported in Brazil (30-40 cm depth). However, charcoal, presumably from wild fires, is commonly reported to one meter depth in neotropical forests soils (Saldarriaga et al. 1988, Horn 1992). The presence of charcoal and pottery sherds buried deep in the soil could also result from bioturbation, a process that is particularly strong in the tropics. In addition, repeated periods of afforestation and deforestation result in the burial of charcoal and pottery (Glaser et al. 2000).

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18 Finally, terra mulata in Brazil have been described as large areas in which terra preta were embedded (Sombroek et al. 2002), but in La Chonta, MO areas appear to be smaller and only as a ring surrounding the TN areas. Further detailed mapping of MO areas in La Chonta are necessary to compare them with terra mulata, which is apparently the same sort of soil in Brazil. Soil Chemistry Perhaps the main difference between the tierra negra of La Chonta and terra preta soils reported in other parts of the Amazon Basin is the type of soils from which the soils are derived. All La Chonta soils have neutral pH contrasting with the typically acidic Amazonian soils (oxisols and ultisols). Therefore, even though reported pH values in Brazilian anthrosols (averaging 4.8-5.5; Smith 1980, Glaser et al. 2000, Sombroek et al. 2002) are higher than their surrounding oxisols, ultisols or inceptisols (< 4.8), they are much more acidic than the TN of La Chonta. The pH of TN of La Chonta was not significantly different from the NTN, which was also reported by Eden et al. (1984) for much more acidic terra preta and their surrounding inceptisols in Caquet, Colombia (pH 4.3-4.8 for terra preta and 4.0-4.5 for inceptisols). In La Chonta, soil organic matter (SOM) was significantly higher in TN soils than NTN soils, corresponding with the results of several other researchers working in the Brazilian Amazon (Smith 1980, Glaser et al. 2000, Sombroek et al. 2002). However, in La Chonta SOM did not differ between MO and NTN, contrasting with Brazilian terra mulata, which has higher SOM content, sometimes even higher that terra preta (Woods and McCann 1999, McCann et al. 2001, Sombroek et al. 2002). Although total P is considered a good indicators of former human occupations (Eidt 1977), total P did not differ between TN, MO, and NTN in La Chonta. However,

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19 McGrath et al. (2001) had similar results, reporting no differences among Amazonian soils under different land-use practices (primary forest, secondary forest, and pasture; with values of total P ranging between 180 41 to 231 26 mg/kg). In contrast with the results for total P, extractable P differed among the three soil types, being higher in TN than NTN and MO of La Chonta. The amounts of extractable P in TN (49.6 and 35.92 mg/kg at 10 cm and 50 cm respectively) were not as high as reported for terra preta in Brazil (358.1 and 619.2 mg/kg at 30 cm, Heckenberger et al. 1999; 175 mg/kg at 20 cm, Smith 1980; and 600 mg/kg, Woods and McCann 1999). While P is limiting in most tropical soils, occurring typically at less than 6 mg/kg (Kellman and Tackaberry 1997, McGrath et al. 2001, Fardeau and Zapata 2002), its presence at higher concentrations in TN, particularly deeper in the soil, positively influences soil fertility in TN. Not surprisingly, in present-day Brazil terra preta soils are valued as agricultural sites for both indigenous people and mestizos, and are sold in urban areas for spreading on yards to promote plant growth (Smith 1980). Terra mulata has been reported as having slightly higher extractable P content than the surrounding non-anthropogenic soils in Brazil (McCann et al. 2001, Sombroek et al. 2002 ), but in La Chonta, MO soils had the same (at 50 cm) and less (at 10 cm) extractable P than NTN soils. One possible explanation for the relative lack of nutrients (particularly P and Ca) in MO soils may be that former inhabitants of La Chonta removed plant material and therefore nutrients from MO areas. Plant material may have been removed from the MO areas and incorporated into TN soils as green manure or through infield burning of vegetation. Certainly, the removal of plant material can locally

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20 diminish nutrients. However more studies in MO soils in La Chonta are necessary to test this hypothesis. The high levels of Ca in the TN soils of La Chonta, coincide with those found by Heckenberger et al. (1999) (from 2626 to 3212 ppm at 20-50 cm depth) near the Negro and Xingu rivers in the Brazilian Amazon, and can be explained by additions of bones, shells, and the influence of ash deposition (Smith 1980, McCann et al. 2001). However, although significantly lower than in TN, extractable Ca was still very high for MO and NTN in La Chonta. These results can be explained by the nature of the parent material, in addition to the anthropogenic influences that might have affected MO and NTN areas, and require further study. Implications of Anthropogenic Influences on La Chonta Forest The large extent of anthropogenic soils in La Chonta should be taken into account by forest managers and researchers. The presence and extent of anthropogenic soils demonstrates that, in the past, the landscape of the region was dramatically different from what is found today and that the present forest developed in the wake of earlier human activities. This study, while not conclusive, shows that human settlements in La Chonta were quite large and of considerable duration. These settlements altered soil chemistry and their effects persist today. Higher nutrient content deep in the anthropogenic soils of La Chonta are expected to strongly influence plant communities. The higher levels of extractable P in TN sites when compared with surrounding soils at 50 cm might be particularly influential. This difference is likely to be influencing present day plant species composition and growth. In the future, careful studies of the larger TN areas, including comprehensive identification of concentrations of archaeological material, will be necessary to

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21 understand the ecological history of La Chonta at the landscape level. The present study concentrated on history and soil chemistry, which, integrated with additional archaeological studies, could contribute to a historical reconstruction of the area and a better understanding of current human-influenced landscapes. In La Chonta, loggers should avoid disturbing archaeological sites until additional investigations are carried out. In addition, researchers should replicate experiments in areas with TN and NTN soils to understand the interactions between land-use history and the variables under examination. Interactions between TN soils and plant communities are still poorly understood and, considering the length of time needed for the formation of anthropogenic soils (1 cm/10 years, Smith 1980), silvicultural and research treatments that disturb TN soils should be minimized.

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Table 1-1. Distribution of tierra negra (TN) sites in a 216 ha sample area Site Area Geographic coordinates (UTM, zone 20) Tierra negra 1 2.4 ha N 8266140 E 526015 Tierra negra 2 0.3 ha N 8265393 E 525920 Tierra negra 3 1 ha N 8265166 E 525950 Tierra negra 4 0.5 ha N 8264084 E 521534 Tierra negra 5 10 ha Not registered Tierra negra 6 10 ha N 8267455 E 521670 Tierra negra 7 5 ha N 8270277 E 520462 Tierra negra 8 1 ha N 8269390 E 520130 Tierra negra 9 Undetermined N 8263147 E524504 Table 1-2. Mean values ( one SE) of tierra negra, tierra morena, and non-tierrra negra soil properties at two depths (0-10 and 40-50 cm) with sites as replicates. Total P was measured colorimetrically after sulfuric acid digestion. Extractable P was measured colorimetrically, and Ca, Mg and K were measured and using atomic absorption (AA) after a Mehlich double-acid extraction 22 Soil property Tierra negra (n = 10) Tierra morena (n = 3) Nontierra negra (n = 6) 0-10 cm 40-50 cm 0-10 cm 40-50 cm 0-10 cm 40-50 cm pH (in water) 7.3 0.10 7.2 0.10 6.6 0.30 6.3 0.30 7.3 0.30 7.0 0.20 % Organic matter 5.7 0.40 2.6 0.20 4.8 0.80 2.1 0.30 4.7 0.30 2.1 0.20 C/N ratio 10.77 0.55 12.00 0.64 10.23 0.26 11.85 0.07 10.13 0.19 12.07 0.32 Total P (g/g) 203.17 33.78 322.15 41.33 170.62 29.68 165.63 53.74 155.31 22.31 357.84 88.12 Extractable P (mg/kg) 49.65 16.36 35.92 17.69 6.66 1.44 2.84 0.82 26.04 9.82 4.34 1.07 Extractable K (mg/kg) 94.36 8.17 62.54 7.92 57.00 9.64 28.39 6.42 91.82 12.96 55.24 8.86 Extractable Ca (mg/kg) 3179.75 288.50 1428.95 115.24 1975.96 328.71 586.77 161.63 2434.71 333.62 805.14 143.87 Extractable Mg (mg/kg) 87.00 14.64 35.53 3.75 58.18 1.44 40.77 7.17 60.12 3.69 31.62 5.77

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Table 1-3. Statistical contrast of the three soil types at two depths Soil property Soils (tierra negra, tierra morena, and non-tierra negra) Depth (0-10 cm and 40-50 cm) Soils x Depth df F P-value df F P-value df F P-value pH (in water) 2 6.03 0.006 1 1.30 0.263 2 0.23 0.795 % Organic matter 2 3.60 0.039 1 72.91 < 0.0001 2 0.37 0.695 C/N ratio 2 0.21 0.812 1 8.63 0.006 2 0.24 0.791 Total P (ug/g) 2 1.55 0.230 1 5.81 0.022 2 1.53 0.234 Extractable P (mg/kg) 2 5.81 0.007 1 6.73 0.015 2 0.79 0.462 Extractable K (mg/kg) 2 4.83 0.015 1 12.64 0.001 2 0.06 0.942 Extractable Ca (mg/kg) 2 7.71 0.002 1 45.10 < 0.0001 2 0.18 0.834 Extractable Mg (mg/kg) 2 1.41 0.259 1 11.35 0.002 2 1.30 0.287 23

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24 Figure 1-1. Location of the study site in lowland Bolivia

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25 Figure 1-2. Location and size of the TN sites in La Chonta

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26 Intermittent, seasonal stream Intermittent, seasonal stream 0 100 m 0 100 m Figure 1-3. Spatial distribution of tierra negra (TN) in relation to tierra morena (MO) and non-tierra negra (NTN)

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27 Soil type NTNMOTNExtractable P (mg/kg) 01020304050 ABCDE Soil type NTNMOTNExtractable K (mg/kg) 020406080100120 soil type: P < 0.015depth: P < 0.001 Soil type NTNMOTNExtractable Ca (mg/kg) 01000200030004000 soil type: P < 0.002depth: P < 0.0001 Soil type NTNMOTN% Organic matter 01234567 soil type: P < 0.0022depth: P < 0.0001 Soil type NTNMOTNpH 0246810 soil type: P < 0.006depth: NS 0 -10 cm 40 50 cm aabbaabababbabaab Figure 1-4. Mean values (+ 1 SE) for tierra negra (TN, N = 10), tierra morena (MO, N = 3,), and non-tierra negra (NTN, N = 6) at two different depths. A) pH. B) Organic matter content. C) Extractable phosphorous. D) Extractable calcium. E) extractable potassium. Different letters indicate overall significant differences among means of the three soil types.

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CHAPTER 2 DISTRIBUTION OF USEFUL TREE SPECIES IN RELATION TO HISTORICAL HUMAN INFLUENCES ON THE FOREST OF A TIMBER CONCESSION IN LOWLAND BOLIVIA Introduction Enrichment of native plant communities with species used by humans (hereafter useful species) near settlements likely occurred prior to as well as after the advent of agriculture, when hunters and gatherers selected and favored certain plant species both purposefully by planting or inadvertently by consuming fruits and disposing of seeds in or near their settlements (Smith 1995, Peters 2000). Tropical fruits were harvested by humans and their seeds transported at least as long ago as 10,500 years B.P. (Roosevelt et al. 1996). These activities may have altered the distribution and enlarged the populations of selected plant species (Lentz 2000a) and are part of the process that transforms plants from wild to domesticated (Clement 1999). The alteration of forests and landscapes was even more dramatic after development of intensive agricultural systems, such as maize cultivation, which developed in the tropical lowlands of the Americas 6,000 7,000 years B.P. (Bush et al. 1989, Pearsall 1992, Piperno and Pearsall 1998). Historical and archaeological records of pre-contact agriculture are scarce because of the severe depopulation and rapid reforestation that took place soon after European colonization of the Americas (Denevan 1992b, Block 1994). Using colonial documents and ethnographies of modern indigenous people to extrapolate pre-historic land-use practices can be inaccurate due to the effects of acculturation coupled with rapid environmental and demographic changes (Denevan 1992a, Lentz 2000b). During the last 28

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29 several decades, archaeological, ecological, paleobotanical, and geographical research carried out in the lowland tropics have revealed pre-Columbian agriculture of scales and intensities previously not considered (Denevan 1966, 1998, Roosevelt 2000). This study examines the influence of past land-use by native human populations on forest composition in the La Chonta timber concession in lowland Bolivia. In modern times, as in the past, people increase the concentration of semi-domesticated and domesticated plants near their settlements by transplanting, planting, tending, and, in general, managing landscapes in favor of useful species (Posey 1985, Bale 1994, Dalle et al. 2002, Smith 2002). Moreover, a positive relationship between biodiversity and management of useful plants has been reported in certain tropical areas (Salick et al. 1999). Accompanying the management of useful species, soils of ancient indigenous villages and their agricultural lands in tropical lowlands were dramatically changed through the addition of plant and animal refuse, charcoal and ash, and mulching, which resulted in darkened anthropogenic soils (referred as to terra preta in Brazil and tierra negra in Bolivia, black soil, and dark earth, Chapter 1). Anthropogenic soils persist for centuries after abandonment, acting as indicators of former villages (Smith 1980, Eden et al.1984, Denevan 1998, Heckenberger et al. 1999). Anthropogenic dark soils usually have higher organic matter and nutrient content than the surrounding soils even several centuries after abandonment (see Chapter 1). The influence of historical land-uses on modern vegetation has been studied in several temperate forests (e.g., Peterken and Game 1984, Foster 1988, 1992, Zbigniew and Loster 1997, Motzkin et al. 1999) but there are few such studies in tropical forests

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30 (e.g., Foster et al. 1998, Dalle et al. 2002). Detecting changes in the distribution of species managed by humans in the past is particularly challenging in tropical regions because the vegetation and species are not well known, there is high diversity, dating tree age is difficult (but see Chambers et al. 1998, Martnez-Ramos and Alvarez-Buylla 1998), and many plant distributions are substantially influenced by stochastic forces (Hubbell and Foster 1986). Furthermore, animals other than humans disperse the seeds of the plants humans find useful (Andresen 1999, Galetti et al. 2001, Quiroga-Castro and Roldn 2001, Zuidema and Boot 2002). Nevertheless, soils and land-use history have been shown to play important roles in the distribution of tropical forests trees (Moran 1993, Clark et al. 1995, Clark et al. 1999, Lentz 2000b). As in other Bolivian forests, many of the most important timber tree species are poorly represented among the smaller trees and regenerate poorly in the forest after logging in La Chonta (Mostacedo and Fredericksen 1999). In contrast, these same species seem to regenerate well in heavily disturbed areas such as along logging roads and in large logging gaps, especially where surface soils have been disturbed by harvesting equipment (Fredericksen and Mostacedo 2000, Fredericksen and Pariona 2002) or following large-scale natural disturbances (Gould et al. 2002). Past land-use practices by indigenous people in La Chonta including large-scale clearing and frequent burning (Chapter 1) may also have provided suitable habitats for colonization and recruitment by these poorly regenerating species. Several of these species may also have been cultivated in the past by indigenous people in the Amazon region such as Bactris gasipaes (Clement 1986, Mora-Urp et al. 1997) and Spondias mombin (Smith et al. 1992, Smith 1995). Did individuals of these useful species or their parents regenerate in

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31 abandoned clearings and/or are they relicts of former indigenous cultivation? By investigating the relationship between these species and anthropogenic soils we can start to answer these questions. In this study I compared the concentration of useful tree species in areas with anthropogenic and non-anthropogenic soils. I predicted that domesticated and semi-domesticated plant species are more abundant in areas with tierra negra than in the surrounding forest. I studied an array of purportedly domesticated and useful wild species including long-lived canopy tree species with dense wood (e.g., Pouteria spp.), pioneer species (e.g., Pourouma cecropiaefolia), and palms (e.g., Attalea phalerata). Methods Study Site The study was carried out in La Chonta, a lowland tropical forest located in the Guarayos Province, Department of Santa Cruz, Bolivia (15'S, 62'W). The annual mean precipitation is ca. 1,500 mm with a severe dry season between May to October and the mean annual temperature of 24.3 C. The vegetation of La Chonta is classified as subtropical humid forest (Holdridge 1971); common tree species include Pseudolmedia laevis, Ocotea guianensis, Clarisia racemosa, Terminalia oblonga, and Hura crepitans (Pizarro-Romero 2001, Fredericksen and Pariona 2002). Lianas are remarkably abundant in the forest (Alvira et al. 2003). The area has a history of human-induced disturbances indicated by the presence of extensive areas of anthropogenic soils (Chapter 1) but the sites examined have apparently not been inhabited for at least 300 years. Uncontrolled selective logging for mahogany (Swietenia macrophylla) and tropical cedar (Cedrela odorata) was carried out until 1996 when

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32 management plans were written and followed and current extraction of 18 species has occurred in the area since the 1970s. La Chonta was formerly inhabited by Guarayo Indians (see Chapter 1), and is characterized by three different soils that they helped create: Tierra negra (TN) dark anthropogenic soils present in patches of 0.3->10 ha, surrounded by tierra morena (MO) a transitional anthropogenic soil that occurs adjacent to TN; and a matrix of non-anthropogenic soils (NTN), tentatively classified as inceptisols. The TN areas are likely former village sites or agricultural fields but the MO areas past land-use is unclear. The chemical properties differ between these soils; TN soils have higher organic matter content, extractable phosphorous (P), and extractable calcium (Ca), than NTN soils and higher pH and extractable P than MO soils. MO and NTN soils had similar organic matter and Ca content, and MO had significantly less extractable K than TN and NTN soils (see Chapter 1). Species Selection Based on a preliminary floristic inventory of the area coupled with literature search, seventeen tree species reportedly used by humans were selected for study (Table 2-1). These species are described as semi-domesticated or domesticated (mostly for their fruits or seeds) by tropical South American indigenous groups (Clement 1986, Smith et al. 1992, Bale 1994, Henderson 1995, Clement 1999) or are presently used by indigenous peoples in lowland Bolivia (Centurin and Krajlevic 1996, Vsquez and Coimbra 1996, DeWalt et al. 1999, Mostacedo and Uslar 1999, Paz et al. 2001). Information about uses and regeneration status was gathered for each species based on field observations, interviews with local foresters, and available literature (Table 2-1). Geographical distributions are based on the Missouri and New York Botanical Garden databases

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33 (Solomon 2002, New York Botanical Garden 2003). Maximum stem diameters and growth rates are derived from unpublished BOLFOR databases (Table 2-2). Maximum age was calculated by dividing maximum DBH by the mean annual growth increment (MAI). The criteria for classifying species as domesticated or semi-domesticated were from Clement (1999) who defines them as follows: Domesticated species are those whose ecological adaptability has been reduced to a point that they can only survive in human-created environments, and if human interventions ceases, the population dies out in short order. Semi-domesticated species are those significantly modified by human selection and intervention, but that retain enough ecological adaptability to survive in the wild without human intervention. Because edible plants are often dispersed to and planted in or near dwellings, ten of the seventeen useful plant species belong to this category. Camps, trails, and settlements were enriched with fruit and nut trees; a process that still takes place in Amazonian backyards and homegardens (Bale 1994, Smith 1995, Lamont et al. 1999). Five species are palms that are used in many ways and found in many present-day indigenous villages and abandoned village sites (Brcher 1989, Clark et al. 1995, Henderson 1995, Moraes-Ramirez 1996, Morcote-Rios and Bernal 2001). Most of the studied palm species regenerate at least sparsely in the forest, with the exception of Bactris gasipaes, which has not been observed as seedlings in La Chonta (T.S. Fredericksen 2002, pers. comm.) and is cultivated through tropical Latin America (Killeen et al. 1993, Postma and Verheij 1994, Clement 1999, Morcote-Rios and Bernal 2001). Species Sampling The total abundance of each selected species was recorded in 50 x 20 m plots in each soil type (TN, MO, and NTN) studied in Chapter 1. Plots were established in 14 NTN sites, 10 MO sites, and 14 TN sites. The area of each of the soil type site varies

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34 between 0.3 ha and >10 ha for TN sites, surrounded by MO sites of approximately 0.5 1 ha, all embedded in a matrix of NTN soils (Chapter 1). The number of plots per site (TN, MO, or NTN site) varied from one to five according the size of the site and the condition of vegetation (whether or not the area had been logged). One to three plots were established in 0.1-0.5 ha sites and five plots were established in sites >0.5 ha. Data Analysis The mean abundance of useful species in each site was calculated by averaging sample plot abundance data scaled up to 1 ha. To test whether species densities differed among soil types, Kruskal-Wallis tests were performed, using a probability of significance of 0.05 with a sequential Bonferroni correction for the error probability (Rice, 1989). Results The tree species I studied all occurred at low densities, but total abundance among the species also varied considerably. Bactris gasipaes (chonta de castilla, peach palm), Astrocaryum aculeatum (chonta de anillo), Ceiba pentandra (hoja de yuca), Pourouma cecropiaefolia (uvilla) and Eugenia sp. (arrayn) were all very scarce, with overall mean abundances between 0.02 to 0.09 individuals/ha. Talisia sculenta (pitn), Spondias mombin (ocorocillo, yellow mombim), Batocarpus amazonicus (murur), Syagrus sancona (sumuqu), Attalea phalerata (motac), Inga spp. (pacay), Myrcia sp. (sawinto), Sapindus saponaria (isotouvo), and Astrocaryum murumuru (chonta) were more common with overall mean abundances between 0.2 to 0.9 individuals/ha. Pouteria nemorosa (coquino), Pouteria macrophylla (lcma) and Ampelocera ruizii (blanquillo) were the most abundant species, with 1.1-3.5 individuals/ha (Table 2-2).

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35 The species vary in geographical distributions and growth characteristics. Pourouma cecropiaefolia is a geographically widespread, fast-growing tree, typical of pioneer species. Spondias mombin, Inga spp., Ceiba pentandra, and Ampelocera ruizii are widespread canopy trees with intermediate growth rates. Their sizes vary between 73 to 200 cm DBH and their maximum ages are estimated between 180 to 227 years. Finally, Eugenia sp., Talisia sculenta, Batocarpus amazonicus, Myrcia sp., Sapindus saponaria, Pouteria nemorosa, and Pouteria macrophylla are relatively slow-growing trees with widespread geographical distribution, except Pouteria nemorosa which is found only in Bolivia and Ecuador. Their sizes range between 51 and 150 cm DBH and their estimated maximum ages (249-468) are negatively correlated with their growth rates (Table 2-2). The distribution of the palms ranges from extremely widespread (Bactris gasipaes) to widespread (Astrocaryum murumuru, Astrocaryum aculeatum, found throughout the Amazon) to restricted (Syagrus sancona, Attalea phalerata, found in southwestern Amazon) (Table 2-2). Contrary to my expectations, the densities of the seventeen species studied did not differ significantly among the three soil types (Figure 2-1) but they were trends that might indicate soil preferences or historical effects. Six species (Inga spp., Spondias mombin, Astrocaryum aculeatum, Bactris gasipaes, Ceiba pentandra, and Pouteria nemorosa) appear to be most abundant in MO areas, and Pouteria macrophylla, appears to be more abundant in NTN soils when compared to MO and TN soils, but the differences were not statistically significant due to high variances When analyzing the differences between anthropogenic (TN and MO pooled together) and non-anthropogenic soils (NTN), the only species showing significant

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36 differences was Pouteria macrophylla, which was more abundant in NTN soils than in anthropogenic soils (MO and TN soils together, Mann-Whitney U = 254, P = 0.009, df = 1, Figure 2-1 O). Although not statistically significan t probably due to small sample sizes, two species, Astrocaryum aculeatum and Ceiba pentandra, were only recorded in TN and MO soils and were not present in NTN soils (Figure 2-1 B and 2-1 G). Discussion Contrary to my expectations, the results showed few differences in the abundances of the 17 useful tree species studied between anthropogenic (TN and MO) and non-anthropogenic soils (NTN) in La Chonta, contradicting the original hypothesis (a concentration of useful species in anthropogenic soils). This unexpected result may be due to a misunderstanding of past land-use practices, but contemporary disturbances cannot be disregarded. It seems most likely that past inhabitants of La Chonta altered the forest beyond the TN areas, influencing both MO and NTN areas. This would be the case if TN areas were villages and surrounding areas (MO and NTN areas) were managed forest or agricultural plots. Alternatively, a former concentration of useful tree species in TN and MO areas may have been masked by modern disturbances, natural dispersal and other factors. The overall low densities and high variability in the distributions of the species studied are consistent with other studies that report canopy species in tropical forests as rare, with densities of tress 10 cm DBH of < 1 individual/ha of (Hubbell 1979, Hubbell and Foster 1986, Clark and Clark 1992). Nevertheless, the six species that appear to be more abundant on MO soils than TN and NTN soils may have been concentrated there if the TN areas were indeed village sites that were mostly devoid of vegetation, and the MO sites were the surrounding agricultural plots.

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37 Four of the six species that appear to be more abundant in MO areas (Spondias mombin, Astrocaryum aculeatum, Bactris gasipaes, and Ceiba pentandra) are present at overall low densities (0.21, 0.04, 0.02, and 0.05 trees/ha respectively), are widely distributed long-lived species, and regenerate poorly in La Chonta (Table 2-1, Table 2-2). In addition, they are all known to be cultivated near human settlements elsewhere in the tropics (particularly Bactris gasipaes, Brcher 1989, Smith et al. 1992, and Clement 1999). It is possible, therefore, were planted by the people who lived in La Chonta 300-400 years ago, but further studies at a bigger scale will be necessary to test this hypothesis. While palms are influenced by several disturbance regimes (Anderson et al. 1991, McPherson and Williams 1998) they are commonly associated with human settlements (Clement 1999, Morcote-Rios and Bernal 2001). There are several reasons to expect that the B. gasipaes population of La Chonta is a relict of ancient cultivation. Despite maximum age estimations of 50-100 years for each mature stem (Brcher 1989, Smith et al. 1992, Mora-Urp et al. 1997), the clone from which new stems emerge could be centuries old, perhaps planted by former inhabitants. In addition, it is the only species I studied that is considered fully domesticated (Clement 1999) and does not regenerate naturally in La Chonta. However, several authors (Clement 1986, 1999, Mora-Urp et al. 1997) recognize that there are different varieties of Bactris gasipaes, comprising a continuum between domesticated and semi-domesticated varieties. In La Chonta, further studies of seed/fruit ratios will determine where Bactris falls in this continuum. Similar to Bactris, the small population of the semi-domesticated palm, Astrocaryum aculeatum (Clements 1999), may also be a relict from earlier plantings given that it is generally

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38 associated with human settlements (Wessels Boer 1965) and regenerates poorly in La Chonta (Table 2-1). The fact that Bactris gasipaes and Astrocaryum aculeatum are not significantly concentrated in the anthropogenic soils suggests in the past their management was not restricted to TN and MO sites. Existing short-lived species (less than 100 years old) could not have been planted by former inhabitants of La Chonta because the area was abandoned more than 300 years ago. For example, the maximum age of Inga spp. in La Chonta is estimated to be 117 years, while in Brazil Laurence (unpublished data) estimated the age of three species of Inga to be between 50 to 160 years. While several species of Inga are considered semi-domesticated, in particular Inga edulis, (Clements 1999), they are also dispersed by monkeys (Andresen 1999) and regenerate well in La Chonta (Table 2-1). Consequently, the apparent concentration of Inga spp. on MO soils (Figure 2-1 H) may be the product of a secondary ecological adaptation rather than the result of enrichment by past inhabitants of La Chonta. The species with abundant regeneration, overall high densities, and no apparent pattern of concentration according to soil type, such as Ampelocera ruizii and Sapindus saponaria, may be wild species that are used by people, but past uses apparently have not altered their present distribution in La Chonta. Ampelocera ruizii is not reported as domesticated or semi-domesticated in the literature and has a fairly narrow distribution, growing only in Brazil and the Bolivian lowlands (Table 2-1). In contrast, Sapindus saponaria is extremely widespread, and is reported to be used by several indigenous groups (Brchner 1989). If the range Sapindus saponaria was expanded by humans, its

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39 regeneration status and distribution (Table 2-1) suggest that it has become wild in La Chonta. The lack of apparent differences in the abundances of most of the species I studied on the different soil types may be explained by numerous interacting factors that are know to determine forest composition (topography, physiography, land use history, etc.) as well as stochastic forces (Hubbell and Foster 1986). Certainly, edaphic and historic factors alone are not enough to explain forest composition in La Chonta, but their interactions with several other factors might do so. Clark et al. (1999) for example, determined that the distributions of only 30% of the species they studied in a lowland forest in Costa Rica were correlated with edaphic conditions, and concluded that only mesoscale vegetation and soil sampling will estimate the true degree of edaphically influenced distributions. A larger scale study in La Chonta and its surroundings, integrating other environmental variables to the analysis may allow us to do the same. One of the main factors influencing the results of this study might be the extended period post-abandonment forest dynamics in the area. The two C-14 dates of charcoal buried among pottery sherds in tierra negra site 3 (Chapter 1) suggest that the site was probably inhabited most recently 380 and 430 years BP. This extended time since abandonment might be sufficient to mask the effects of humans enrichment with useful species in the anthropogenic soil areas. In this time period, two or three generations of the short-lived trees can have developed and biotic and abiotic seed dispersal processes may have extended the species distribution range beyond the TN patches, if they were indeed initially concentrated there. In addition, disturbances such as fires and tree falls may have played a role in the distribution of useful species.

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40 It is also possible that TN areas were maintained as permanently cleared areas in villages as they are and were in Amazonian Brazil (Heckenberger et al. 1999). If village sites were maintained clear of vegetation with a large central plaza and compacted soils (Heckenberger et al. 1999, Woods et al. 2000), it is likely that the perimeter of these areas (MO and NTN areas) represent the agricultural zone that was enriched with useful species. If this is true in La Chonta, the soils surrounding TN sites are those more affected by past agricultural practices and are areas where useful species would have been managed or cultivated. Consequently, NTN areas adjacent to TN areas might not constitute a good control for testing the influence of past land-use practices on species composition. A better control area would be a similar forest without a history of human disturbances, which will be difficult to find. The results of this study suggest that short-lived species with good regeneration and no pattern of concentration in anthropogenic soils, while perhaps used by former inhabitants, are now wild species that do not reflect the influence of past human use. In contrast, large individuals of long-lived species with poor regeneration may in fact be remnants of former cultivation. The lack of significant concentrations of useful species in TN and MO soils suggests that species may have been cultivated or managed in adjacent NTN areas and that plant communities on all sites were influenced by human activities.

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Table 2-1. Characteristics of tree species that are used by humans and selected for study in La Chonta. 41 Family Scientificname Commonname Use Growthform Geographical distribution Regeneration statusa Anacardiaceae Spondias mombin* Ocorocillo Multiuse (edible fruit, roots and medicinal bark); cultivated. Emergent Mexico to Bolivia. Poor Arecaceae Astrocaryum aculeatum* Chonta de anillo Multi-use (edible fruits and seeds, oil, construction). Subcanopy Amazonia, fromColombia to Bolivia Poor Arecaceae Astrocaryum murumuru Chonta Multi-use (ediblefruits and seeds, oil, construction) Canopy Amazonia, fromColombia to Bolivia Medium Arecaceae Attalea phalerata Motac Multi-use (ediblefruits and seeds, medicine, construction) Canopy South and West Amazonia, Peru, Brazil and Bolivia. Good Arecaceae Bactris gasipaes** Chonta de castilla Multi-use (edible fruit, medicine, bows, construction); cultivated. Canopy Central America to Bolivia. Poor Arecaceae Syagrus sancona Sumuqu Multi-use(construction, fruits and seeds used to attract game); cultivated. Emergent SouthwesternAmazon and Eastern Andes, from Colombia to Bolivia. Medium Bombacaceae Ceiba pentandra Hoja de yuca Multi-use (religious, fiber, oil from seeds); cultivated. Emergent Pantropical. Poor Leguminosae (Mimosoideae) Inga spp.* Pacay Edible fruit; Inga edulis cultivated Subcanopy, pioneer Genus is widespread in tropics and subtropics. Good

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42 Table 2-1, Continued Moraceae Batocarpus amazonicus Murur Multi-use (ediblefruit, dye, latex) Canopy Panama to Bolivia Poor Moraceae Pourouma cecropiaefolia Uvilla Edible fruit,medicinal; cultivated. Canopy, pioneer Costa Rica to Bolivia. Good Myrtaceae Eugenia sp.* Arrayn Edible fruit Subcanopy Pantropical Good Myrtaceae Myrcia sp. Sawinto Edible fruit Canopy Amazonia, Bolivia and Brazil Poor Sapindaceae Sapindus saponaria Isotouvo Soap from fruit, medicinal Subcanopy Arizona to Bolivia Good Sapindaceae Talisia sculenta Pitn Edible fruit;cultivated. Subcanopy Amazonia, fromColombia to Bolivia. Poor Sapotaceae Pouteria macrophylla* Lcma Edible fruit Canopy Bolivia, Brazil and Peru Good Sapotaceae Pouteria nemorosa Coquino Edible fruit Canopy Disjunct, only in Ecuador and Bolivia Good Ulmaceae Ampelocera ruizii Blanquillo Edible fruit Canopy Bolivia, Brazil and Peru Good aGood = seedlings, saplings (<1.50 m), juveniles (>1.50 m) and adults present in the forest; Medium = juveniles and adults present, regeneration scarce; Poor = only adults present, regeneration scarce. This classification is valid only for La Chonta. = Semi-domesticated; ** = Domesticated, according to (Clement 1999).

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Table 2-2. Maximum diameters, mean growth rates for trees > 10 cm DBH and mean annual diameter increment (MAI based on 3 years of data) of the selected tree species in La Chonta, based on unpublished data from permanent sample plots of BOLFOR Project. Estimated maximum age was calculated by dividing maximum DBH by MAI. Scientific name Maximum DBH (cm) Mean annual diameter increment (MAI, cm) N (for MAI) Estimated maximum age (years) Overall mean abundance / ha ( one SE) Spondias mombin 121 0.43 61 180 0.21 ( 0.04) Astrocaryum murumuru 40 ---0.91 ( 0.12) Astrocaryum aculeatum 16 ---0.04 ( 0.03) Attalea phalerata 48 ---0.41 ( 0.07) Bactris gasipaes 18 ---0.02 ( 0.01) Syagrus sancona 26 ---0.37 ( 0.07) Ceiba pentandra 200 0.88 15 227 0.05 ( 0.02) Inga spp. 73 0.62 55 117 0.49 ( 0.12) Batocarpus amazonicus 85 0.27 62 316 0.33 ( 0.08) Pourouma cecropiaefolia 74 2.23 16 33 0.06 ( 0.03) Eugenia sp. 37 0. 29 12 128 0.09 ( 0.03) Myrcia sp. 83 0.30 209 276 0.60 ( 0.21) Sapindus saponaria 51 0.12 166 427 0.83 ( 0.13) Talisia sculenta 52 0.21 31 250 0.17 ( 0.05) Pouteria macrophylla 99 0.26 100 382 1.49 ( 0.24 Pouteria nemorosa 150 0.32 219 469 1.12 ( 0.15) Ampelocera ruizii 110 0. 61 410 180 3.51 ( 0.38) 43

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44 Spondias mombinSoil type NTNMOTNMean abundance / ha 0.00.10.20.30.40.5 Astrocaryum murumuruSoil type NTNMOTN 012 Astrocaryum aculeatumSoil type NTNMOTN 0.000.020.040.060.080.100.120.140.160.18 Attalea phalerataSoil type NTNMOTN 012 Bactris gasipaesSoil type NTNMOTNMean abundance / ha 0.000.020.040.060.080.10 Mean abundance / ha Syagrus sanconaSoil type NTNMOTN 0.00.10.20.30.40.50.6 A B C D E F Figure 2-1. Comparisons of the relative abundances ( 1 SE) of the selected useful tree species among the three different soil types: non-tierra negra (NTN, N = 14), tierra morena (MO, N = 10), and tierra negra (TN, N = 14).

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45 Myrcia sp.Soil type NTNMOTN 012 Eugenia sp.Soil type NTNMOTN 0.000.050.100.150.200.25 Ceiba pentandra Soil type NTNMOTN Mean abundance / ha 0.000.020.040.060.080.100.120.14 Pourouma cecropiifoliaSoil type NTNMOTNMean abundance / ha 0.000.020.040.060.080.100.120.140.160.180.20 Inga spp.Soil type NTNMOTN 012 Batocarpus amazonicusSoil type NTNMOTN 0.00.10.20.30.40.50.6 Mean abundance / ha G H I J L K Figure 2-1. Continued

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46 Sapindus saponariaSoil type NTNMOTN 012 Talisia sculentaSoil type NTNMOTN 0.00.10.20.30.40.5 Mean abundance / haP < 0.027 Pouteria macrophyllaSoil type NTNMOTNMean abundance / ha 0123 Pouteria nemorosaSoil type NTNMOTN 0123 Ampelocera ruiziiSoil type NTNMOTNMean abundance / ha 012345 MPNOQ Figure 2-1. Continued

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56 BIOGRAPHICAL SKETCH Clea Lucrecia Paz Rivera was born in La P az, Bolivia. As a child, she lived in Per, Mexico, and Colombia, while her mother, a sociologist, was in pol itical exile. While living in these countries she developed a love and curiosity for the natural and cultural diversity of Latin America. As an undergraduate she studied biological sciences at the Universidad Mayor de San Andrs in La Paz. Her undergraduate thes is focused on the effects of cattle grazing on floristic diversity in the savannas of Beni, Bolivia. She graduated with her Licenciatura in 1998. She the worked as an associat e researcher at the Herbario Nacional de Bolivia, conducting floristic inventories in secondary forests in the Chapare region. She also collaborated in the initial phase of the Catalog of Vascular Plants of Bolivia. In 2000, the Herbarium nominated her for a LASP AU/Fulbright fellowship. The fellowship was granted and she began her graduate work in the University of Florida's Interdisciplinary Ecology Program in Spri ng 2001, hosted by the Department of Botany. Upon completing her masters degree, Clea will return to her country with her husband and son. She intends to resume work at the Herbario Nacional de Bolivia and explore dissertation topics.


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FOREST-USE HISTORY AND THE SOILS AND VEGETATION OF A LOWLAND
FOREST IN BOLIVIA
















By

CLEA LUCRECIA PAZ RIVERA


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA


2003

































Copyright 2003

by

Clea Lucrecia Paz Rivera

































To the memory of my grandfather Carlos Alfredo Rivera, whose love and inspiration
have accompanied me through the years.















ACKNOWLEDGMENTS

Numerous individuals and institutions deserve acknowledgment for their

contributions to this thesis. First, I am indebted to my advisor Francis E. "Jack" Putz, for

his mentorship, persistence, enthusiasm, and interest in Bolivia. Also at the University of

Florida, I would like to thank my other committee members Kaoru Kitajima and Nigel

Smith for their advice. I also wish to thank Nick Comerford for his guidance on soil

analysis, Mary Mcleod, Jennie del Marco for helping me in the laboratory.

The Latin American Scholarship Program of American Universities

(LASPAU/Fulbright), Proyecto de Manejo Forestal Sostenible (BOLFOR), the School of

Natural Resources and Environment, the Department of Botany, and the Tropical

Conservation and Development Program at the University of Florida, all provided

generous financial and logistical support for my graduate studies. My excellent field

guide, Jose Chuvifia, deserves praise for his boundless energy and rich knowledge of the

forest. I also thank Marielos Pefia-Claros, Joaquin Justiniano, and Todd Fredericksen at

BOLFOR; Narel Paniagua at the Herbario Nacional de Bolivia; and Sergio Calla (for his

archaeological work). The BOLFOR project staff gave me technical and logistic support

in Santa Cruz. I thank my labmates at the University of Florida (Bonifacio Mostacedo

Geoffrey Blate, and William Grauel) who were always available for grammatical

consultations, statistical guidance, editing, and comic relief. Amy Miller helped me in

many ways, from editing, to sharing the challenges of thesis writing, to being a dear









friend. Catherine Cardelus and Eddie Watkins provided both friendship and draft

reviews.

I especially thank my parents and siblings for their inspiration and support; and for

taking care of my son while I was in the field. My son Santiago shared with me his

beauty and companionship, and I thank him for his forgiveness when I could not give him

the time and attention he deserved. Last but not least, I could not have completed this

work without the constant love, care, support, and warm meals from my husband

Stephen.
















TABLE OF CONTENTS
Page

A C K N O W L E D G M E N T S ................................................................................................. iv

LIST OF TABLES .................................................... ........ .. .............. viii

LIST OF FIGURES ......... ......................... ...... ........ ............ ix

ABSTRACT .............. ................. .......... .............. xi

CHAPTER

1 ANTHROPOGENIC SOILS OF A FORESTRY CONCESSION IN LOWLAND
B O L IV IA ................................................................ .. ........ ...............1

Introduction .........................................................................................................
History of Study Area ............... ................. ....................... ...... ... 4
Sp aniard s ................................................................... 5
M issionary A activity ........................................... .. ........ ................ .6
Population D ensity ...................................... .......................... .7
L and and R source U se ........................................................... ............... 8
M e th o d s ................................................................ ......................................1 1
Study Site...................................... ............ 11
Soil Sam pling and A nalysis........................................... .......................... 12
Results ................. ............... .................. .. ............................... 13
Area, Shape, and Location of Anthropogenic Soil Patches.............................. 13
Soil Chemistry .................................... .......................... .... ........ .15
D discussion ................................................................ ......... ........... 16
Area, Shape, and Location of Anthropogenic Soil Patches.............................. 16
Soil Chemistry ................ ................................. ......... .....................18
Implications of Anthropogenic Influences on La Chonta Forest ......................20

2 DISTRIBUTION OF USEFUL TREE SPECIES IN RELATION TO HISTORICAL
HUMAN INFLUENCES ON THE FOREST OF A TIMBER CONCESSION IN
L O W L A N D B O L IV IA .................................................................... .....................28

Introduction..................................... .................................. .......... 28
M e th o d s ................................................................... 3 1
Study Site.............................................. 31
Species Selection ................................. ........................... ... .......32










Species Sampling.................. .. ............................. 33
D ata A n a ly sis .................................................................................................. 3 4
R e su lts ...........................................................................................3 4
D isc u ssio n .............................................................................................................. 3 6

R E F E R E N C E S ................................................................47

B IO G R A PH IC A L SK E T C H ........................................................................................ 56
















LIST OF TABLES


Table pge

1-1. Distribution of tierra negra (TN) sites in a 216 ha sample area ............................22

1-2. Mean values (+ one SE) of tierra negra, tierra morena, and non-tierrra negra soil
properties at two depths (0-10 and 40-50 cm) with sites as replicates...................22

1-3. Statistical contrast of the three soil types at two depths................. .... ........... 23

2-1. Characteristics of tree species that are used by humans and selected for study in La
C h o n ta ........................................................... ................ 4 1

2-2. Maximum diameters, mean growth rates for trees > 10 cm DBH and mean annual
diameter increment (MAI, based on 3 years of data) of the selected tree species in
L a C h o n ta ........... ......... ...... ......... ...... .......... .....................................4 3















LIST OF FIGURES


Figure pge

1-1. Location of the study site in lowland Bolivia ........ ...........................................24

1-2. Location and size of the TN sites in La Chonta. ....................................... .......... 25

1-3. Spatial distribution of tierra negra (TN) in relation to tierra morena (MO) and
non-tierra negra (N TN ). ............................................... ............................... 26

1-4. Mean values (+ 1 SE) for tierra negra (TN, N = 10), tierra morena (MO, N = 3,),
and non-tierra negra (NTN, N = 6) at two different depths for a) pH, b) organic
matter content, c) extractable phosphorous, d) extractable calcium, and e)
extractable potassium ....................... .. ...... .................. .. .. ....... ........... 27

2-1. Relative abundances ( 1 SE) of the selected useful tree species among the three
different soil types ............. ................... ... ......... ........ .. .. .. ........ .... 46
















Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

FOREST-USE HISTORY AND THE SOILS AND VEGETATION OF A LOWLAND
FOREST IN BOLIVIA

By

Clea Lucrecia Paz Rivera

December 2003

Chair: Francis E. Putz
Major Department: Natural Resources and Environment

Land-use practices can dramatically affect soils and vegetation, even centuries after

they cease. In Amazonia, soils enriched by nutrient and charcoal additions are indicators

of ancient village sites and old agricultural plots. To ascertain whether past land-use

practices also result in local enrichment with useful plants, I studied the anthropogenic

soils and associated vegetation of a forestry concession in the Department of Santa Cruz,

Bolivia. I compared the chemical properties of anthropogenic soils with surrounding soils

and then compared the concentration of useful tree species on and off of anthropogenic

soil areas.

Two types of anthropogenic soils were identified in the research area: tierra negra

(TN) darkened with charcoal fragments and with abundant buried pottery shards; and

tierra morena (MO), somewhat darkened but with little or no pottery. In an area of

216ha, nine TN soil patches (0.3 to 10 ha) and three MO soil patches were identified and

compared with six nearby non-anthropogenic soils (inceptisols), which are referred to as









non-tierra negra (NTN). The abundance of seventeen useful tree species was measured

in plots on the three soil types (TN, MO, and NTN).

Results of this study demonstrate that La Chonta's soils retain strong effects of past

human activities that ceased 300 to 400 years ago, when the area was abandoned. The TN

soils cover approximately 20% of La Chonta and are chemically different from the MO

and NTN soils but all were circum neutral in pH, high in Ca content, and similar in total

P. The TN soils had significantly higher contents of organic matter, extractable P, and

extractable Ca than did NTN soils; and higher pH and extractable P than did MO soils.

The MO soils had organic matter and Ca content similar to that of NTN soils and

significantly less extractable K. Overall, TN soils had higher nutrient content than

surrounding soils, both at the surface (0-10 cm) and deeper in the soil (40-50 cm).

Of the seventeen useful tree species studied, none were concentrated in TN areas.

This unexpected result may be due to interactions between local dispersal agents and

natural disturbances that masked historical patterns. Alternatively, past inhabitants of La

Chonta may have managed or cultivated their useful tree species beyond anthropogenic

soil areas. In any case, the influence of past land-use practices on plant species

composition is not apparent in La Chonta.














CHAPTER 1
ANTHROPOGENIC SOILS OF A FORESTRY CONCESSION IN LOWLAND
BOLIVIA

Introduction

Land-use history has played important roles in shaping modern landscapes and

ecosystems. This study examines the history of the currently uninhabited timber

concession of La Chonta, in the Guarayos Province of lowland Bolivia, and the effects of

past land-use practices on its soil properties.

Humans are now recognized as having dramatically influenced Amazon Basin

forests (Roosevelt et al. 1991, Denevan 1992b, Balee 1994, Smith 1999). Forests once

considered pristine or virgin are increasingly viewed as resulting from regeneration after

the cessation of human activities (Lentz 2000b). Human influences are to be expected,

given that archeological studies reveal that humans were present in Amazonia at least

12,000 years ago (Roosevelt et al. 1991). Although hotly debated, estimates of pre-

Columbian population density in Amazonia are all high. For example, Dobyns (1966)

estimated 6 million for all of tropical South America, whereas Denevan (1992a)

estimated a population of 8.6 million in lowland South America alone, a number that

declined by 90% within 100 years after European contact. pre-Columbian societies in the

Amazon have affected the region at all scales up to the landscape level, through

constructing raised fields, earthen causeways, and hydraulic earthworks (Denevan 1966,

2001, Lippi 1988, Erickson 2000, Roosevelt 2000) as well as through use of more subtle

forest-management practices (Posey 1985, Balee 1994, Denevan 1998, Peters 2000).









Past human disturbances may have influenced several attributes of present-day

Neotropical landscapes (Balee 1994, Lentz 2000a). For example, Peters (2000) and

Erickson (2000) working in Central American forests and Amazonian savannas

respectively, showed that modem vegetation in their study sites was greatly altered by

direct and indirect enrichment by pre-Columbian societies. Direct enrichment of useful

plant species occurred through manipulations such as planting or thinning, while indirect

enrichment was the creation or alteration of habitats such as those conducive to

colonization by early successional species.

Despite the extent of landscape alterations by pre-Columbian societies, land-use

history in dynamic tropical ecosystems can be difficult to unravel because ecological

processes such as bioturbation, heavy rainfall, and rapid plant growth can obscure

evidence of earlier human activities (Stahl 1995). Nevertheless, soils generally reflect

human-induced alterations for long periods of time and therefore can serve as useful

indicators of past land-use practices (Glaser 2002).

In Amazonia, dark anthropogenic soils (referred to as tierra negra in Bolivia, and

terra preta and terra preta do Indio in Brazil) occur in patches from 0.5 to 300 ha,

typically embedded in a matrix of infertile soils (mainly oxisols and ultisols). Terrapreta

are defined by a distinctive anthropogenic epipedon with intermixed potsherds and celts

(Sombroek 1966, Smith 1980, Woods et al. 2000, Glaser et al. 2001). High organic

matter and elevated nutrient contents (especially phosphorous, calcium, potassium, and

sodium) distinguish the Amazonian anthropogenic soils from those in their surroundings

(Smith 1980, Woods et al. 2000, Glaser et al. 2001, McCann et al. 2001).









Although the origin, distribution, and use of Amazonian anthropogenic soils are

still unclear, it seems that fire was the most important factor in their formation (Woods et

al. 2000). Apparently incorporation of charcoal (black carbon) and wood ash increases

nutrient retention capacity, cation exchange capacity (CEC), and soil pH (Woods et al.

2000); ant it stabilizes soil organic matter (SOM) while reduces nutrient leaching from

soils (Glaser et al. 2000 and 2001). Charcoal is also extremely resistant to weathering and

can persist in soil for millennia (Rainho Texeira et al. 2002), thereby contributing to the

maintenance of anthropogenic soil properties through time. The second factor related to

the formation of these soils was the incorporation of household waste, such us food

remains, shells, bones, feces, blood, and urine, all of which increased soil nutrient content

(Smith 1980, McCann et al. 2001).

Initially, anthropogenic soils were reported on floodplains, especially on river

bluffs along the main Amazon river (Sombroek 1966, Smith 1980). More recently, large

areas of terrapreta have been reported in terrafirme, or upland forests (Heckenberger et

al. 1999), and in floodplains along tributaries of the Amazon river (McCann et al. 2001).

In any case, most of the reported occurrences of anthropogenic soils in South America to

date are near permanent sources of water.

Two kinds of anthropogenic soils, terrapreta and terra mulata, have been

described as being clearly distinguishable in Brazil (Sombroek et al. 2002). Terrapreta

appears in former human settlements and, besides being enriched in nutrients and

charcoal, is always associated with pottery and cultural debris (Smith 1980,

Heckenberger et al. 1999). Terra mulata is thought to have developed in permanent

agricultural fields, enriched by long-term soil-management practices such as mulching









and infield burning (Denevan 1996, Woods et al. 2000, McCann et al. 2001). Despite

some recent advances in our understanding, the nature and characteristics of pre

Columbian agriculture that originated terra mulata still remain little known.

High nutrient levels of anthropogenic soils and the different ways vegetation was

managed in and surrounding these areas are expected to influence the vegetation that

either persists or colonizes the sites after their abandonment. In any event, it is obvious

that the original vegetation in these areas was substantially modified by humans, and that

certain species were either favored or introduced from other areas, perhaps permanently

altering local species composition.

This study has two objectives. The first is to reconstruct the history of the

Guarayos area through review of bibliographic sources. The second is to describe the

anthropogenic soils of La Chonta and compare soil properties between anthropogenic and

surrounding soils.

History of Study Area

Unraveling the history of human activities can help us understand the soils,

vegetation, landscape, and successional patterns in modern ecosystems (Glenn 1999).

Given that there are few published historical accounts of Guarayos, colonial archives and

historical reports from nearby regions were used to reconstruct its probable land-use

patterns and settlement history (Orbigny 1835, Cardus 1886).

Guarayos is a biological and cultural transitional region with influences from the

humid forests of Amazonia to the north, the drier forests of Chiquitos (Chiquitania) and

Chaco to the southeast, and the savannas ofMojos (Moxos) to the west (Figure 1-1).

Both Mojos and Chiquitos were explored and settled by Europeans earlier than Guarayos









and as a result there is relatively more historical information about them, but the histories

of the three regions are intertwined.

Although the Swedish anthropologist Erland Nordenskiold excavated in Guarayos

in the early twentieth century (Nordenskiold 1930), the secondary urn burials (urns

containing fleshless bones) he unearthed have apparently not been dated. I am aware of

no other pre-contact archeological data. Early reports from European explorers and

missionaries provide the only descriptions of cultural and ecological conditions following

European contact.

The Guarayos region is believed to have been inhabited by the Guarayo Indians,

who likely migrated from Paraguay and inhabited the Guarayos region since at least 1400

(Orbigny 1835, Cardus 1886). The Guarayo language is of the Tupi-Guarani family and

is closely related to Guarani (Cardus 1886), spoken by the Guarani Indians who

historically inhabited the Chaco region of southeastern Bolivia and northern Argentina

and Paraguay. Despite their common language, the Guarayo and Guarani have marked

cultural and physical differences, suggesting that if the two groups were once more

closely related, their separation took place long before European contact (Finot 1939).

Spaniards

The region now referred to as Guarayos and inhabited primarily by the Guarayo

was probably first encountered by Europeans during a Spanish expedition that set out

from Asuncion, Paraguay in the 1540s. The objective of this and numerous similar

explorations was to find the tierra ricas of indigenous legends that described the

treasures and gold of El Dorado, El Gran Paititi, or El Gran Mojos, this last believed at

one time to be located north of Chiquitos (Finot 1939).









Apparently the first expedition to pass through the Guarayos region was led by the

Spanish captain Nuflo de Chavez, who left Asunci6n in 1558 with 150 Spanish soldiers

and 1500 Guarani Indians. His mission was to establish a new town in the Xarayes

marshes (located in Mato Grosso, Brazil, and southeastern Bolivia) but upon arrival, he

found the area unsuitable for settlement and decided to continue the expedition, traveling

west and northwest in search of ElDorado. Although maps that reconstruct Nuflo de

Chavez's expeditions show the route passing through Guarayos region, there is no direct

mention of Guarayo people in the chronicles of the trip, contrasting with the extensive

description of surrounding indigenous groups such as Chiquito, Chiriguano, Mojo, and

others (Levillier 1976).

According to the interpretation of Levillier (1976), Chavez encountered the

Guarayo indians north of latitude 160 South when he was attacked by an unidentified

indigenous group living at a heavily fortified settlement. Chavez, uncertain of victory,

turned away from the settlement and returned to Chiquitos.

In the late 17th century the Spaniards approach to conquest shifted from one of

broad exploration to a more systematic effort at populating areas where they had been

able to establish a presence. Because of its distance from Santa Cruz de al Sierra, the

Guarayos region was not colonized and there is little mention of the area until the 18th

century.

Missionary Activity

Religious missionaries entered South America with objectives quite different from

those of the explorers-in place of gold they sought the souls of indigenous infieles.

Unlike the explorers, who in most cases passed quickly over through the landscape,

missionaries had sustained contact with local people. Jesuit missionaries arrived on the









continent in the late 1500s and in the Bolivian lowlands the first reducciones (Jesuit and

Franciscan missions) were established roughly a century later. In Mojos, the first mission

(Loreto) was established in 1682; San Francisco Javier in Chiquitos was established in

1691.

Between 1700 and 1845, there were five attempts, first by Jesuits and later by

Franciscans, to establish reducciones among the Guarayo. The first four failed at

retaining significant numbers of people. It was only later (1845) that thousands of

Guarayo were concentrated in several towns in the region, including the present-day

capital, Ascenci6n, founded by Franciscans in 1826.

Population Density

There are apparently no published estimates of population density in Guarayos

before the missionary period. Nevertheless, as mentioned above, several lines of evidence

indicate that the native population was high in pre-Columbian times. For example, near

Guarayos in the savannas of Mojos, Jesuit missionaries reported 37 related yet distinct

indigenous groups in 1696 (Chavez 1986). Denevan estimated a native population of

350,000 in the same region and calculated that that number decreased to 100,000 by the

1690s as a consequence of epidemic diseases (Denevan 1992a).

Spanish chronicles of expeditions from Paraguay to Santa Cruz and Mojos in the

late 1500s and early 1600s reported encounters with hundreds of indigenous groups.

Reports from this time stated that the Guarani and Guarani-related groups, including

Chiriguano, Sirion6, and Itantines, tended to be the more populous and bellicose (Finot

1939, Pinckert-Justiniano 1991).

After Gregorio Salvatierra, a Franciscan missionary, visited four mission towns in

1794 (Asenci6n, Yaguaru, Yotau and Urubicha), he estimated a population between 3000









and 4000 in the region (Cardus 1886). D'Orbingy, who visited Asenci6n de Guarayos in

1831, estimated 1,000 Guarayo Indians in the area (Orbigny 1835). During the mission

period, the Jesuits concentrated hundreds of families in towns, but they repeatedly

reported the existence of many "wild" Guarayo living in the forest who maintained only

sporadic contact with people living in towns. The Jesuits carried out several recruitment

expeditions into forested areas and reported dispersed families along their route and

returned with groups of varied sizes, the last (1825) returning with 200 Guarayo (Cardus

1886).

The population estimates of D'Orbigny and Salvatierra were likely gross

underestimates because they were based only on the established mission settlements, and

did not include people dispersed through the forest. It also seems relevant to note that

these censuses were carried out more than 200 years after the arrival of Europeans to the

region, when populations were probably greatly diminished by introduced diseases such

as smallpox and the flu. The impact diseases brought by Europeans was reported in

Chiquitos by D'Orbigny who noted that half of the Chiquitano residing in San Javier died

from smallpox in 1825. Similarly Cardus mentioned that a "malignous fever" attacked

and killed hundreds of Guarayo in 1845.

Land and Resource Use

Archaeologists and ecologists are currently trying to understand land-use practices

prior to European contact. Descriptions by Jesuits and Franciscans, admittedly biased by

their belief that indigenous peoples were ignorant savages, and reports by D'Orbingy,

provide the earliest reports of the land-use practices and customs. Unfortunately, the

land-use practices they described already reflected European influences, the most

important of these being the introduction of metal tools. Metal tools are several times









more efficient for cutting trees than stone tools (the ratio varies from 10 to 1 to 23 to 1,

Denevan 1992c), allowing faster forest clearing, and the development of long fallow

shifting cultivation. Due to the inefficiency of stone axes, some authors claim that pre-

Columbian agriculture was based in home gardens and permanent crop fields instead of

modern shifting cultivation with short cropping periods followed by long forest fallows,

which would be too labor intensive to be a common agricultural practice (Denevan 1998).

D'Orbigny, who visited Asenci6n de Guarayos in 1823, provides the first

description of anthropogenic soils, reporting "black fields ready to be planted". After his

arrival he described the Guarayo living in mission towns with the Franciscans as having

maintained more of their customs and otherwise were less influenced by Europeans than

the Chiquitano. D'Orbigny asserts that agriculture was their main food producing

activity, and that hunting was more of a past time than an essential activity (this

contradicts the missionaries descriptions, who assert the Guarayo were mainly hunters).

D'Orbigny's claims, however, are corroborated by the great number of religious

ceremonies devoted to Tamoi (grandfather), the most important god of the Guarayo, who

was believed to have taught them agriculture. When D'Orbigny arrived in the region, the

Guarayo had a well-developed shifting cultivation system centered on squash, corn,

yucca, papaya, pineapples, and sugar cane (an old world crop introduced by the Jesuits in

the early 1800s) using metal axes. Agricultural fields were managed by the whole

community while they lived divided in small families in octagonal-shaped cabafias roofed

with palm leaves, similar to those used by the Caribe of Central America. They

reportedly planted near the houses a sacred tree called turienda (apparently Ceiba

pentandra), which they claimed was used by their gods to come down and take them









when they died. They wore clothes made of the bibosi tree bark (Ficus spp.) and painted

their bodies with achiote (Bixa orellana; Orbigny 1835).

Cards, a Franciscan missionary who visited the area between 1883 and 1884,

provides a similar description of the Guarayo agricultural system (Cardus 1886). He

described low, forested, rolling hills intermixed with forested wetlands to the south,

extensive, flat, lowland forests to the north, and to the west, beyond several leguas

(leagues, approximately four to seven kilometers) of forest, began the huge savannas of

Mojos region. He also observed that the Rio Blanco (Figure 1-1), was navigable to

Carmen del Mojos whereas today, the river is navigable only seasonally, and then by

small canoe. Cards described the Guarayo as primarily hunters and fishers, with their

principal crops being corn, yucca, plantain (an old world crop), beans, peanuts, and

squash. Spider monkey was their preferred meat and chicha, a fermented beverage made

of corn or yucca, was their most common beverage.

The different views on human cultures and ecology in the Guarayos region

provided by early explorers, missionaries, and scientists, offer an opportunity to consider

the dramatic changes that took place over the previous centuries. Although Guarayos

was at first a region on the periphery of European activities in Bolivia, it was still

affected, finally to a large degree, by the arrival of explorers and missionaries.

Unfortunately, the accounts of D'Orbigny, Cardus, and others begin at least two centuries

after the arrival of Europeans to the region, sufficient time for forests to regenerate on

abandoned sites following the massive indigenous population declines that occurred

throughout the Americas (Denevan 1992a, Block 1994). This lapse in time prevents us

from understanding pre-colonial landscapes that may have been quite different from









those D'Orbigny, Cardus, and others observed. For instance, if native populations were

large before contact, the landscape was likely much less forested than it was more than a

century after the population crash.

Study of the anthropogenic soils of La Chonta affords an opportunity to piece

together the past at a much different level of detail than that made possible by historical

and religious records. It allows us to estimate the area of long-abandoned settlements or

cultivated plots, and the effects of human induced soil alterations on soil chemistry and

plant species composition.

Methods

Study Site

This study was conducted in La Chonta, a lowland tropical forest in Guarayos

Province, Department of Santa Cruz, Bolivia (15047'S, 62055'W, Figure 1-1). A

100,000 ha private timber concession since 1974, the area was selectively logged for

mahogany (Swietenia macrophylla) and tropical cedar (Cedrela odorata) for the first

decade after its establishment. When mahogany was depleted, the focus shifted to other

species and today loggers extract up to a dozen species. La Chonta was certified by the

Forest Stewardship Council as well managed in 1998. A long-term silvicultural research

project was started in La Chonta in 2000 as part of the BOLFOR Sustainable Forest

Management Project (Putz et al. in press).

The vegetation of La Chonta is classified as subtropical humid forest (Holdridge

1971), with mean annual temperature of 24.50C and mean annual rainfall of ca. 1500

mm. The canopy is semideciduous and fairly open, with heights of mature forests of 20

to 25 m. Common canopy tree species are characteristic of humid forests and include

Hura crepitans and Pseudolmedia laevis (Navarro and Maldonado 2002). Lianas are









abundant and dominate disturbed areas (Alvira et al. 2003). The area has a long history of

both human-induced and 'natural' fires, but there were no signs of recent fires in my

study area. The region has numerous ephemeral streams, and the rivers Blanco and Negro

border the peripheries of the concession (Figure 1-1).

Soil Sampling and Analysis

An area of 216 ha was surveyed for anthropogenic soils by sampling at 200 m

intervals along walking trails separated by 150 m. The trails delimit research plots in La

Chonta and are kept clear of vegetation; changes in soil color and type were easily

recognized. Surface soil was cursorily examined and soil color was recorded using a

Munsell Soil Color Chart. When soil color darkened markedly, sampling intervals were

reduced to 100 m and examined more thoroughly for charcoal and pottery.

Soils were classified as tierra negra (TN) when extremely dark in color (7.5 YR

3/1 and 2.5/1; dark brown and very dark brown) and both charcoal and pottery sherds

were present. Soils that were somewhat darkened (7.5 YR 4/3 3/2, brown to dark

brown) but with little or no pottery were classified as tierra morena (MO). Soils with no

apparent indicators of anthropogenic influences were classified as non-tierra negra

(NTN), and are tentatively classified as inceptisols (Navarro 2002). When TN soils were

encountered, their area was estimated by sampling in the four cardinal directions every

20 m with a soil auger until the patch limits were identified. Patch locations were

recorded with a handheld Garmin GPS.

Soil samples were taken from each of the TN and MO patches, and the surrounding

NTN soils. From the approximate center of each patch, soil samples were taken at two

depths (0-10 and 40-50 cm) at the corners of a 10x10 m square. Samples from each of the









depths were mixed together and 200 g of each was air dried in the field and stored for

laboratory analysis.

As a preliminary archaeological assessment of the area, one test pit (lxlm3) was

excavated in the central area of each TN site to quantify the abundance of pottery sherds

and to determine the depth of the TN soils. During the early phase of this study, two large

charcoal fragments that were found intermixed with abundant pottery sherds at 10 and 20

cm depths in an anthropogenic soil patch (tierra negra 3 Table 1-1) were submitted to

Beta Analytic Laboratory for accelerator mass spectrometry (AMS) radio-carbon dating.

In the laboratory, soil organic matter was estimated using the weight loss on

ignition method (Nelson 1996). Total phosphorous (P) was measured colorimetrically

after sulfuric acid digestion (Olsen and Sommers 1982). Extractable phosphorous was

measured colorimetrically after a Mehlich double-acid solution (Olsen and Sommers

1982). Finally, extractable calcium (Ca), magnesium (Mg), and potassium (K) were

assayed using atomic absorption (AA) following extraction in a Mehlic double-acid

solution (Thomas 1982). To compare soil types, the chemical data were analyzed with a

two-way ANOVA model using soil type (TN, MO and NTN) and depth as factors and

sites as replicates.

Results

Area, Shape, and Location of Anthropogenic Soil Patches

In an area of 216 ha, nine patches of tierra negra (TN, Table 1-1, Figure 1-2), three

patches of tierra morena (MO), and six nearby (within 1 km) areas of non-tierra negra

(NTN) soil were identified. The TN patches were commonly located on flat terraces

within 200 m of streams that at least flow during the rainy season (Figure 1-3). TN patch

sizes varied in La Chonta and were grouped in two categories: small circular patches









(0.3-2.5 ha), and larger, irregular patches (5-10 ha). Mapping of the larger areas was not

completed because they extended past the perimeters of the research plots. Within TN

sites, I found areas with higher concentration of charcoal and pottery sherds, probably

corresponding to kitchen middens (S. Palma, unpublished data). The cumulative area of

the most prominently affected anthropogenic soils (TN) accounts for approximately 20%

of the study area (Table 1-1, Figure 1-2). The patches of MO were 0.3-1.0 ha and tended

to surround the TN sites (Figure 1-3). I did not quantitatively measure areas of MO but

estimate them to cover an additional 5% of the area.

The preliminary archaeological investigations carried out in TN soil pits revealed

distinguishable layers, defined by abundant pottery sherds and charcoal, which differed

between the small and large patches. In both patches sizes the surface 10 cm were dark in

color but usually contained no pottery and charcoal, with the exception of areas disturbed

by animals or roads. The small patches (0.3-1 ha) in general had one continuous stratum

of dark soil from 10 to 30-45 cm depth with intermixed charcoal and pottery whereas the

larger patches generally had two separated layers with anthropogenic traces, one at 10-40

cm depth and other at 45-75 cm depth. The 5 cm separation between the two

anthropogenic layers in the large patches consisted of a layer of sandy-loam soil with

large quartz crystals.

The density of buried pottery sherds in the intensively inventoried soil pits varied

from 19 to 187 pieces per m3. I also found solid pieces of macroscopic black carbon

(between 1 and 5 cm size) from 10 to 75 cm soil depth in both the small and large

patches. The two charcoal fragments found mixed with pottery in tierra negra site 3 at 10









and 20 cm below the surface were AMS dated from 330 + 80 to 420 60 years BP

respectively.

Soil Chemistry

The pH of soils in La Chonta were all high, averaging 7.2 in the TN soils, 6.4 in the

MO soils and 7.2 in the NTN (Table 1-2); pH was significantly higher in TN and NTN

soils than in the MO soils (P < 0.006, Figure 1-4a). Organic matter content at 10 and 50

cm depth averaged 5.7% and 2.6% in TN soils, 4.8% and 2.1% in MO soils, and 4.7%

and 2.1% in NTN soils, being significantly higher in the TN soils than the NTN soils (P <

0.039, Figure 1-4b).

Total phosphorous was relatively high in all three soil types while extractable

phosphorous was relatively low. Total P was not significantly different among the three

soil types and averaged 15522-358+8 (Table 1-2) Extractable P content averaged 49.65

and 35.92 mg/kg (at 10 and 50 cm respectively) in TN soils, being significantly higher

than MO soils at both depths and significantly higher than NTN at 50 cm (P < 0.015,

Figure 1-4c).

Extractable Ca was extremely high in all La Chonta soils, averaging (at 10 and 50

cm depths, respectively) 3179 and 1428 mg/kg in TN soils, 1975 and 587 mg/kg in MO

soils and 2435 and 805 in NTN soils, being significantly higher in TN soils than NTN

and MO soils (P < 0.002 Figure 1-4d). Extractable K was significantly higher in NTN

soils and TN soils when compared to MO soils (P < 0.015, Figure 1-4e), averaging 94.36

and 62.54 mg/kg in TN soils, 57 and 28.39 mg/kg in MO soils, and 91.82 and 55.24

mg/kg in NTN soils (at 10 and 50 cm, respectively).

All of the soil properties tested, with the exception of pH and total P, were

significantly higher at 10 cm than at 50 cm depth (Table 1-3). Organic matter content,









extractable P and extractable Ca were significantly higher in TN than MO and NTN at 50

cm depth (P < 0.015, P < 0.001, and P < 0.0001 respectively, Figure 1-4b, c, and d).

Overall, the transitional MO soils had lower nutrient concentrations than NTN soils.

Discussion

Area, Shape, and Location of Anthropogenic Soil Patches

In contrast with the majority of anthropogenic soil areas in the Amazon Basin

(Sombroek 1966, Smith 1980, Heckenberger et al. 1999, Woods et al. 2000, McCann et

al. 2001), the anthropogenic soils of La Chonta are located in an area lacking big rivers or

wetlands. In fact, researchers and logging crews currently working in the area are faced

with the hardship of bringing barrels of water long distances to their camps. The closest

rivers, Rio Negro and Rio Blanco, are 14-30 km from the TN areas I mapped (Figure 1-1)

and the water flow in La Chonta streams has ceased completely during the latter portions

of the dry seasons (between May and October). Ancient village sites in the Brazilian

Amazon described to date are mostly associated with large rivers (Roosevelt 1989, Smith

1980, McCann et al. 2001). However, a large terrapreta site (200 ha) relatively far away

from rivers (15 kilometers from the Amazon River floodplain) was reported in

Comunidade Terra Preta, at km 55 of the Juriti-Tabatinga road in Para, Brazil (Smith

1999, p. 25). Further detailed analyses of the archaeology, pollen, and phytoliths in La

Chonta are needed to determine if the water regime was the same when the area was last

inhabited, and how the former inhabitants managed to provide themselves enough water

to survive, given that I found no evidence of prehistoric wells or dams.

The processes of settlement, abandonment, and reoccupation of the large patches of

TN may help explain the great differences in patch size. Apparently the larger patches (5-

10 ha) were occupied more than once (S. Palma, unpublished data), which makes the size









of the patches an inaccurate indicator of village size, as suggested by Meggers (1995) for

TN areas in the Brazilian Amazon. Alternatively, the larger patches could represent old

agricultural plots in which forms of indigenous agriculture not currently used may have

been practiced. Denevan (1992c), for example, suggests that management of house

gardens and permanent plots of mixed annuals and perennials were common indigenous

pre-Columbian agricultural practices. Nevertheless, more archaeological research is

needed to determine precisely the land-use practices carried in the large areas of TN and

MO.

The two C-14 dates for charcoal that was mixed with pottery at 10 and 20 cm depth

suggest tierra negra site 3 was inhabited between 300 and 400 years B.P, but do not

indicate the prior duration of settlement. However, charcoal and pottery were present at

deeper in the soil (to 75 cm) in other TN sites, consequently, a series of soil charcoal C-

14 dates along several soil excavation units replicated in different archaeological sites in

the area will be necessary to establish more precisely the sequence of human occupation

of La Chonta.

In this study, charcoal was found at greater depths than those Glaser et al. (2000)

reported in Brazil (30-40 cm depth). However, charcoal, presumably from wild fires, is

commonly reported to one meter depth in neotropical forests soils (Saldarriaga et al.

1988, Horn 1992). The presence of charcoal and pottery sherds buried deep in the soil

could also result from bioturbation, a process that is particularly strong in the tropics. In

addition, repeated periods of afforestation and deforestation result in the burial of

charcoal and pottery (Glaser et al. 2000).









Finally, terra mulata in Brazil have been described as large areas in which terra

preta were embedded (Sombroek et al. 2002), but in La Chonta, MO areas appear to be

smaller and only as a ring surrounding the TN areas. Further detailed mapping of MO

areas in La Chonta are necessary to compare them with terra mulata, which is apparently

the same sort of soil in Brazil.

Soil Chemistry

Perhaps the main difference between the tierra negra of La Chonta and terrapreta

soils reported in other parts of the Amazon Basin is the type of soils from which the soils

are derived. All La Chonta soils have neutral pH contrasting with the typically acidic

Amazonian soils (oxisols and ultisols). Therefore, even though reported pH values in

Brazilian anthrosols (averaging 4.8-5.5; Smith 1980, Glaser et al. 2000, Sombroek et al.

2002) are higher than their surrounding oxisols, ultisols or inceptisols (< 4.8), they are

much more acidic than the TN of La Chonta. The pH of TN of La Chonta was not

significantly different from the NTN, which was also reported by Eden et al. (1984) for

much more acidic terrapreta and their surrounding inceptisols in Caqueta, Colombia (pH

4.3-4.8 for terrapreta and 4.0-4.5 for inceptisols).

In La Chonta, soil organic matter (SOM) was significantly higher in TN soils than

NTN soils, corresponding with the results of several other researchers working in the

Brazilian Amazon (Smith 1980, Glaser et al. 2000, Sombroek et al. 2002). However, in

La Chonta SOM did not differ between MO and NTN, contrasting with Brazilian terra

mulata, which has higher SOM content, sometimes even higher that terrapreta (Woods

and McCann 1999, McCann et al. 2001, Sombroek et al. 2002).

Although total P is considered a good indicators of former human occupations (Eidt

1977), total P did not differ between TN, MO, and NTN in La Chonta. However,









McGrath et al. (2001) had similar results, reporting no differences among Amazonian

soils under different land-use practices (primary forest, secondary forest, and pasture;

with values of total P ranging between 180 41 to 231 + 26 mg/kg).

In contrast with the results for total P, extractable P differed among the three soil

types, being higher in TN than NTN and MO of La Chonta. The amounts of extractable P

in TN (49.6 and 35.92 mg/kg at 10 cm and 50 cm respectively) were not as high as

reported for terrapreta in Brazil (358.1 and 619.2 mg/kg at 30 cm, Heckenberger et al.

1999; 175 mg/kg at 20 cm, Smith 1980; and 600 mg/kg, Woods and McCann 1999).

While P is limiting in most tropical soils, occurring typically at less than 6 mg/kg

(Kellman and Tackaberry 1997, McGrath et al. 2001, Fardeau and Zapata 2002), its

presence at higher concentrations in TN, particularly deeper in the soil, positively

influences soil fertility in TN. Not surprisingly, in present-day Brazil terrapreta soils are

valued as agricultural sites for both indigenous people and mestizos, and are sold in urban

areas for spreading on yards to promote plant growth (Smith 1980).

Terra mulata has been reported as having slightly higher extractable P content than

the surrounding non-anthropogenic soils in Brazil (McCann et al. 2001, Sombroek et al.

2002 ), but in La Chonta, MO soils had the same (at 50 cm) and less (at 10 cm)

extractable P than NTN soils. One possible explanation for the relative lack of nutrients

(particularly P and Ca) in MO soils may be that former inhabitants of La Chonta removed

plant material and therefore nutrients from MO areas. Plant material may have been

removed from the MO areas and incorporated into TN soils as green manure or through

infield burning of vegetation. Certainly, the removal of plant material can locally









diminish nutrients. However more studies in MO soils in La Chonta are necessary to test

this hypothesis.

The high levels of Ca in the TN soils of La Chonta, coincide with those found by

Heckenberger et al. (1999) (from 2626 to 3212 ppm at 20-50 cm depth) near the Negro

and Xingu rivers in the Brazilian Amazon, and can be explained by additions of bones,

shells, and the influence of ash deposition (Smith 1980, McCann et al. 2001). However,

although significantly lower than in TN, extractable Ca was still very high for MO and

NTN in La Chonta. These results can be explained by the nature of the parent material, in

addition to the anthropogenic influences that might have affected MO and NTN areas,

and require further study.

Implications of Anthropogenic Influences on La Chonta Forest

The large extent of anthropogenic soils in La Chonta should be taken into account

by forest managers and researchers. The presence and extent of anthropogenic soils

demonstrates that, in the past, the landscape of the region was dramatically different from

what is found today and that the present forest developed in the wake of earlier human

activities. This study, while not conclusive, shows that human settlements in La Chonta

were quite large and of considerable duration. These settlements altered soil chemistry

and their effects persist today.

Higher nutrient content deep in the anthropogenic soils of La Chonta are expected

to strongly influence plant communities. The higher levels of extractable P in TN sites

when compared with surrounding soils at 50 cm might be particularly influential. This

difference is likely to be influencing present day plant species composition and growth.

In the future, careful studies of the larger TN areas, including comprehensive

identification of concentrations of archaeological material, will be necessary to









understand the ecological history of La Chonta at the landscape level. The present study

concentrated on history and soil chemistry, which, integrated with additional

archaeological studies, could contribute to a historical reconstruction of the area and a

better understanding of current human-influenced landscapes.

In La Chonta, loggers should avoid disturbing archaeological sites until additional

investigations are carried out. In addition, researchers should replicate experiments in

areas with TN and NTN soils to understand the interactions between land-use history and

the variables under examination. Interactions between TN soils and plant communities

are still poorly understood and, considering the length of time needed for the formation of

anthropogenic soils (1 cm/10 years, Smith 1980), silvicultural and research treatments

that disturb TN soils should be minimized.














Table 1-1. Distribution of tierra negra (TN) sites in a 216 ha sample area
Site Area Geographic coordinates (UTM,
zone 20)
Tierra negra 1 2.4 ha N 8266140 E 526015
Tierra negra 2 0.3 ha N 8265393 E 525920
Tierra negra 3 1 ha N 8265166 E 525950
Tierra negra 4 0.5 ha N 8264084 E 521534
Tierra negra 5 10 ha Not registered
Tierra negra 6 10 ha N 8267455 E 521670
Tierra negra 7 5 ha N 8270277 E 520462
Tierra negra 8 1 ha N 8269390 E 520130
Tierra negra 9 Undetermined N 8263147 E524504


Table 1-2. Mean values ( one SE) of tierra negra, tierra morena, and non-tierrra negra soil properties at two depths (0-10 and 40-
50 cm) with sites as replicates. Total P was measured colorimetrically after sulfuric acid digestion. Extractable P was
measured colorimetrically, and Ca, Mg and K were measured and using atomic absorption (AA) after a Mehlich double-


acid extraction
Soil property Tierra negra
(n 10)
0-10 cm


pH (in water)
% Organic matter
C/N ratio
Total P (pg/g)
Extractable P (mg/kg)
Extractable K (mg/kg)
Extractable Ca (mg/kg)
Extractable Mg (mg/kg)


7.3 + 0.10
5.7 + 0.40
10.77 + 0.55
203.17 + 33.78
49.65 + 16.36
94.36 + 8.17
3179.75 + 288.50
87.00 14.64


40-50 cm


7.2 0.10
2.6 + 0.20
12.00 + 0.64
322.15 + 41.33
35.92 + 17.69
62.54 + 7.92
1428.95 + 115.24
35.53 + 3.75


Tierra morena
(n = 3)
0-10 cm
6.6 0.30
4.8 + 0.80
10.23 0.26
170.62 + 29.68
6.66 + 1.44
57.00 + 9.64
1975.96 + 328.71
58.18 1.44


40-50 cm


6.3 + 0.30
2.1 + 0.30
11.85 + 0.07
165.63 + 53.74
2.84 + 0.82
28.39 + 6.42
586.77 161.63
40.77 + 7.17


Non- tierra negra
(n = 6)
0-10 cm
7.3 + 0.30
4.7 0.30
10.13 0.19
155.31 + 22.31
26.04 + 9.82
91.82 12.96
2434.71 + 333.62
60.12 + 3.69


40-50 cm


7.0 + 0.20
2.1 + 0.20
12.07 + 0.32
357.84 + 88.12
4.34 + 1.07
55.24 + 8.86
805.14 143.87
31.62 + 5.77


CJ


-














Table 1-3. Statistical contrast of the three soil types at two depths


Soil property


pH (in water)
% Organic matter
C/N ratio
Total P (ug/g)
Extractable P (mg/kg)
Extractable K (mg/kg)
Extractable Ca (mg/kg)
Extractable Mg (mg/kg)


Soils (tierra negra, tierra morena,
and non-tierra negra)
df F P-value
2 6.03 0.006
2 3.60 0.039
2 0.21 0.812
2 1.55 0.230
2 5.81 0.007
2 4.83 0.015
2 7.71 0.002


2 1.41


0.259


Depth (0-10 cm and 40-50 cm)


df F
1 1.30
1 72.91
1 8.63
1 5.81
1 6.73
1 12.64
1 45.10
1 11.35


P-value
0.263
<0.0001
0.006
0.022
0.015
0.001
< 0.0001
0.002


Soils x Depth


df F
2 0.23
2 0.37
2 0.24
2 1.53
2 0.79
2 0.06
2 0.18
2 1.30


P-value
0.795
0.695
0.791
0.234
0.462
0.942
0.834
0.287








South America



N La Chonta
I


Santa Cruz


Scale 1: 7.000,000


Figure 1-1. Location of the study site in lowland Bolivia













520000


TN sites
0-1 ha
S1 2 ha
2-3ha
i 3-5 ha
6- 10ha
La Chonta sawmill
roads
Rivers
| Research blocks


Scale 1:200000
Projection UTM
WGS 84 Zone 20S


Figure 1-2. Location and size of the TN sites in La Chonta


510000


515000


525000


530000


535000



































Figure 1-3. Spatial distribution of tierra negra (TN) in relation to tierra morena (MO)
and non-tierra negra (NTN)



















10 -10cm
I 40- 50 cm

8- a


soil type P < 0 006
depth NS


NTN MO
A Soil type


4000


30

ab
20n


10



NTN MO TN

C Soil type


soil type P < 00022
depth P < 0 0001

m a


NTN MO
B Soil type


soil type P < 0 002
depth P<00001


3000

E

2000



1000


NTN MO

Soil type


a




b









NTN MO

Soil type


soiltype P<0015
depth P <0 001

a












TN


Figure 1-4. Mean values (+ 1 SE) for tierra negra (TN, N = 10), tierra morena (MO, N -

3,), and non-tierra negra (NTN, N = 6) at two different depths. A) pH. B)

Organic matter content. C) Extractable phosphorous. D) Extractable calcium.

E) extractable potassium. Different letters indicate overall significant

differences among means of the three soil types.


80


60


40


20


0

E














CHAPTER 2
DISTRIBUTION OF USEFUL TREE SPECIES IN RELATION TO HISTORICAL
HUMAN INFLUENCES ON THE FOREST OF A TIMBER CONCESSION IN
LOWLAND BOLIVIA

Introduction

Enrichment of native plant communities with species used by humans (hereafter

useful species) near settlements likely occurred prior to as well as after the advent of

agriculture, when hunters and gatherers selected and favored certain plant species both

purposefully by planting or inadvertently by consuming fruits and disposing of seeds in

or near their settlements (Smith 1995, Peters 2000). Tropical fruits were harvested by

humans and their seeds transported at least as long ago as 10,500 years B.P. (Roosevelt et

al. 1996). These activities may have altered the distribution and enlarged the populations

of selected plant species (Lentz 2000a) and are part of the process that transforms plants

from wild to domesticated (Clement 1999). The alteration of forests and landscapes was

even more dramatic after development of intensive agricultural systems, such as maize

cultivation, which developed in the tropical lowlands of the Americas 6,000 7,000 years

B.P. (Bush et al. 1989, Pearsall 1992, Piperno and Pearsall 1998).

Historical and archaeological records of pre-contact agriculture are scarce because

of the severe depopulation and rapid reforestation that took place soon after European

colonization of the Americas (Denevan 1992b, Block 1994). Using colonial documents

and ethnographies of modern indigenous people to extrapolate pre-historic land-use

practices can be inaccurate due to the effects of acculturation coupled with rapid

environmental and demographic changes (Denevan 1992a, Lentz 2000b). During the last









several decades, archaeological, ecological, paleobotanical, and geographical research

carried out in the lowland tropics have revealed pre-Columbian agriculture of scales and

intensities previously not considered (Denevan 1966, 1998, Roosevelt 2000). This study

examines the influence of past land-use by native human populations on forest

composition in the La Chonta timber concession in lowland Bolivia.

In modern times, as in the past, people increase the concentration of semi-

domesticated and domesticated plants near their settlements by transplanting, planting,

tending, and, in general, managing landscapes in favor of useful species (Posey 1985,

Balee 1994, Dalle et al. 2002, Smith 2002). Moreover, a positive relationship between

biodiversity and management of useful plants has been reported in certain tropical areas

(Salick et al. 1999).

Accompanying the management of useful species, soils of ancient indigenous

villages and their agricultural lands in tropical lowlands were dramatically changed

through the addition of plant and animal refuse, charcoal and ash, and mulching, which

resulted in darkened anthropogenic soils (referred as to terrapreta in Brazil and tierra

negra in Bolivia, black soil, and dark earth, Chapter 1). Anthropogenic soils persist for

centuries after abandonment, acting as indicators of former villages (Smith 1980, Eden et

al.1984, Denevan 1998, Heckenberger et al. 1999). Anthropogenic dark soils usually

have higher organic matter and nutrient content than the surrounding soils even several

centuries after abandonment (see Chapter 1).

The influence of historical land-uses on modern vegetation has been studied in

several temperate forests (e.g., Peterken and Game 1984, Foster 1988, 1992, Zbigniew

and Loster 1997, Motzkin et al. 1999) but there are few such studies in tropical forests









(e.g., Foster et al. 1998, Dalle et al. 2002). Detecting changes in the distribution of

species managed by humans in the past is particularly challenging in tropical regions

because the vegetation and species are not well known, there is high diversity, dating tree

age is difficult (but see Chambers et al. 1998, Martinez-Ramos and Alvarez-Buylla

1998), and many plant distributions are substantially influenced by stochastic forces

(Hubbell and Foster 1986). Furthermore, animals other than humans disperse the seeds of

the plants humans find useful (Andresen 1999, Galetti et al. 2001, Quiroga-Castro and

Roldan 2001, Zuidema and Boot 2002). Nevertheless, soils and land-use history have

been shown to play important roles in the distribution of tropical forests trees (Moran

1993, Clark et al. 1995, Clark et al. 1999, Lentz 2000b).

As in other Bolivian forests, many of the most important timber tree species are

poorly represented among the smaller trees and regenerate poorly in the forest after

logging in La Chonta (Mostacedo and Fredericksen 1999). In contrast, these same

species seem to regenerate well in heavily disturbed areas such as along logging roads

and in large logging gaps, especially where surface soils have been disturbed by

harvesting equipment (Fredericksen and Mostacedo 2000, Fredericksen and Pariona

2002) or following large-scale natural disturbances (Gould et al. 2002). Past land-use

practices by indigenous people in La Chonta including large-scale clearing and frequent

burning (Chapter 1) may also have provided suitable habitats for colonization and

recruitment by these poorly regenerating species. Several of these species may also have

been cultivated in the past by indigenous people in the Amazon region such as Bactris

gasipaes (Clement 1986, Mora-Urpi et al. 1997) and Spondias mombin (Smith et al.

1992, Smith 1995). Did individuals of these useful species or their parents regenerate in









abandoned clearings and/or are they relicts of former indigenous cultivation? By

investigating the relationship between these species and anthropogenic soils we can start

to answer these questions.

In this study I compared the concentration of useful tree species in areas with

anthropogenic and non-anthropogenic soils. I predicted that domesticated and semi-

domesticated plant species are more abundant in areas with tierra negra than in the

surrounding forest. I studied an array of purportedly domesticated and useful wild species

including long-lived canopy tree species with dense wood (e.g., Pouteria spp.), pioneer

species (e.g., Pourouma cecropiaefolia), and palms (e.g., Attaleaphalerata).

Methods

Study Site

The study was carried out in La Chonta, a lowland tropical forest located in the

Guarayos Province, Department of Santa Cruz, Bolivia (15047'S, 62055'W). The annual

mean precipitation is ca. 1,500 mm with a severe dry season between May to October and

the mean annual temperature of 24.3 C.

The vegetation of La Chonta is classified as subtropical humid forest (Holdridge

1971); common tree species include Pseudolmedia laevis, Ocotea guianensis, Clarisia

racemosa, Terminalia oblonga, and Hura crepitans (Pizarro-Romero 2001, Fredericksen

and Pariona 2002). Lianas are remarkably abundant in the forest (Alvira et al. 2003). The

area has a history of human-induced disturbances indicated by the presence of extensive

areas of anthropogenic soils (Chapter 1) but the sites examined have apparently not been

inhabited for at least 300 years. Uncontrolled selective logging for mahogany (Swietenia

macrophylla) and tropical cedar (Cedrela odorata) was carried out until 1996 when









management plans were written and followed and current extraction of 18 species has

occurred in the area since the 1970s.

La Chonta was formerly inhabited by Guarayo Indians (see Chapter 1), and is

characterized by three different soils that they helped create: Tierra negra (TN) dark

anthropogenic soils present in patches of 0.3->10 ha, surrounded by tierra morena (MO)

a transitional anthropogenic soil that occurs adjacent to TN; and a matrix of non-

anthropogenic soils (NTN), tentatively classified as inceptisols. The TN areas are likely

former village sites or agricultural fields but the MO area's past land-use is unclear. The

chemical properties differ between these soils; TN soils have higher organic matter

content, extractable phosphorous (P), and extractable calcium (Ca), than NTN soils and

higher pH and extractable P than MO soils. MO and NTN soils had similar organic

matter and Ca content, and MO had significantly less extractable K than TN and NTN

soils (see Chapter 1).

Species Selection

Based on a preliminary floristic inventory of the area coupled with literature search,

seventeen tree species reportedly used by humans were selected for study (Table 2-1).

These species are described as semi-domesticated or domesticated (mostly for their fruits

or seeds) by tropical South American indigenous groups (Clement 1986, Smith et al.

1992, Balee 1994, Henderson 1995, Clement 1999) or are presently used by indigenous

peoples in lowland Bolivia (Centuri6n and Krajlevic 1996, Vasquez and Coimbra 1996,

DeWalt et al. 1999, Mostacedo and Uslar 1999, Paz et al. 2001). Information about uses

and regeneration status was gathered for each species based on field observations,

interviews with local foresters, and available literature (Table 2-1). Geographical

distributions are based on the Missouri and New York Botanical Garden databases









(Solomon 2002, New York Botanical Garden 2003). Maximum stem diameters and

growth rates are derived from unpublished BOLFOR databases (Table 2-2). Maximum

age was calculated by dividing maximum DBH by the mean annual growth increment

(MAI). The criteria for classifying species as domesticated or semi-domesticated were

from Clement (1999) who defines them as follows:

Domesticated species are those whose ecological adaptability has been reduced to a
point that they can only survive in human-created environments, and if human
interventions ceases, the population dies out in short order. Semi-domesticated
species are those significantly modified by human selection and intervention, but
that retain enough ecological adaptability to survive in the wild without human
intervention.

Because edible plants are often dispersed to and planted in or near dwellings, ten of

the seventeen useful plant species belong to this category. Camps, trails, and settlements

were enriched with fruit and nut trees; a process that still takes place in Amazonian

backyards and homegardens (Balee 1994, Smith 1995, Lamont et al. 1999). Five species

are palms that are used in many ways and found in many present-day indigenous villages

and abandoned village sites (Brticher 1989, Clark et al. 1995, Henderson 1995, Moraes-

Ramirez 1996, Morcote-Rios and Bemal 2001). Most of the studied palm species

regenerate at least sparsely in the forest, with the exception ofBactris gasipaes, which

has not been observed as seedlings in La Chonta (T.S. Fredericksen 2002, pers. comm.)

and is cultivated through tropical Latin America (Killeen et al. 1993, Postma and Verheij

1994, Clement 1999, Morcote-Rios and Bemal 2001).

Species Sampling

The total abundance of each selected species was recorded in 50 x 20 m plots in

each soil type (TN, MO, and NTN) studied in Chapter 1. Plots were established in 14

NTN sites, 10 MO sites, and 14 TN sites. The area of each of the soil type site varies









between 0.3 ha and >10 ha for TN sites, surrounded by MO sites of approximately 0.5 -

1 ha, all embedded in a matrix of NTN soils (Chapter 1). The number of plots per site

(TN, MO, or NTN site) varied from one to five according the size of the site and the

condition of vegetation (whether or not the area had been logged). One to three plots

were established in 0.1-0.5 ha sites and five plots were established in sites >0.5 ha.

Data Analysis

The mean abundance of useful species in each site was calculated by averaging

sample plot abundance data scaled up to 1 ha. To test whether species densities differed

among soil types, Kruskal-Wallis tests were performed, using a probability of

significance of 0.05 with a sequential Bonferroni correction for the error probability

(Rice, 1989).

Results

The tree species I studied all occurred at low densities, but total abundance among

the species also varied considerably. Bactris gasipaes (chonta de castilla, peach palm),

Astrocaryum aculeatum (chonta de anillo), Ceibapentandra (hoja de yuca), Pourouma

cecropiaefolia (uvilla) and Eugenia sp. (arrayan) were all very scarce, with overall mean

abundances between 0.02 to 0.09 individuals/ha. Talisia sculenta (pit6n), Spondias

mombin (ocorocillo, yellow mombim), Batocarpus amazonicus (murure), Syagrus

sancona (sumuque), Attaleaphalerata (motacu), Inga spp. (pacay), Myrcia sp. (sawinto),

Sapindus saponaria (isotouvo), and Astrocaryum murumuru (chonta) were more common

with overall mean abundances between 0.2 to 0.9 individuals/ha. Pouteria nemorosa

(coquino), Pouteria macrophylla (lucma) and Ampelocera ruizii blanquilloo) were the

most abundant species, with 1.1-3.5 individuals/ha (Table 2-2).









The species vary in geographical distributions and growth characteristics.

Pourouma cecropiaefolia is a geographically widespread, fast-growing tree, typical of

pioneer species. Spondias mombin, Inga spp., Ceiba pentandra, and Ampelocera ruizii

are widespread canopy trees with intermediate growth rates. Their sizes vary between 73

to 200 cm DBH and their maximum ages are estimated between 180 to 227 years.

Finally, Eugenia sp., Talisia sculenta, Batocarpus amazonicus, Myrcia sp., Sapindus

saponaria, Pouteria nemorosa, and Pouteria macrophylla are relatively slow-growing

trees with widespread geographical distribution, except Pouteria nemorosa which is

found only in Bolivia and Ecuador. Their sizes range between 51 and 150 cm DBH and

their estimated maximum ages (249-468) are negatively correlated with their growth rates

(Table 2-2). The distribution of the palms ranges from extremely widespread (Bactris

gasipaes) to widespread (Astrocaryum murumuru, Astrocaryum aculeatum, found

throughout the Amazon) to restricted (Syagrus sancona, Attaleaphalerata, found in

southwestern Amazon) (Table 2-2).

Contrary to my expectations, the densities of the seventeen species studied did not

differ significantly among the three soil types (Figure 2-1) but they were trends that

might indicate soil preferences or historical effects. Six species (Inga spp., Spondias

mombin, Astrocaryum aculeatum, Bactris gasipaes, Ceiba pentandra, and Pouteria

nemorosa) appear to be most abundant in MO areas, and Pouteria macrophylla, appears

to be more abundant in NTN soils when compared to MO and TN soils, but the

differences were not statistically significant due to high variances

When analyzing the differences between anthropogenic (TN and MO pooled

together) and non-anthropogenic soils (NTN), the only species showing significant









differences was Pouteria macrophylla, which was more abundant in NTN soils than in

anthropogenic soils (MO and TN soils together, Mann-Whitney U = 254, P = 0.009,

df= 1, Figure 2-1 O). Although not statistically significant probably due to small sample

sizes, two species, Astrocaryum aculeatum and Ceibapentandra, were only recorded in

TN and MO soils and were not present in NTN soils (Figure 2-1 B and 2-1 G).

Discussion

Contrary to my expectations, the results showed few differences in the abundances

of the 17 useful tree species studied between anthropogenic (TN and MO) and non-

anthropogenic soils (NTN) in La Chonta, contradicting the original hypothesis (a

concentration of useful species in anthropogenic soils). This unexpected result may be

due to a misunderstanding of past land-use practices, but contemporary disturbances

cannot be disregarded. It seems most likely that past inhabitants of La Chonta altered the

forest beyond the TN areas, influencing both MO and NTN areas. This would be the case

if TN areas were villages and surrounding areas (MO and NTN areas) were managed

forest or agricultural plots. Alternatively, a former concentration of useful tree species in

TN and MO areas may have been masked by modern disturbances, natural dispersal and

other factors.

The overall low densities and high variability in the distributions of the species

studied are consistent with other studies that report canopy species in tropical forests as

rare, with densities of tress > 10 cm DBH of < 1 individual/ha of (Hubbell 1979, Hubbell

and Foster 1986, Clark and Clark 1992). Nevertheless, the six species that appear to be

more abundant on MO soils than TN and NTN soils may have been concentrated there if

the TN areas were indeed village sites that were mostly devoid of vegetation, and the MO

sites were the surrounding agricultural plots.









Four of the six species that appear to be more abundant in MO areas (Spondias

mombin, Astrocaryum aculeatum, Bactris gasipaes, and Ceiba pentandra) are present at

overall low densities (0.21, 0.04, 0.02, and 0.05 trees/ha respectively), are widely

distributed long-lived species, and regenerate poorly in La Chonta (Table 2-1, Table 2-2).

In addition, they are all known to be cultivated near human settlements elsewhere in the

tropics (particularly Bactris gasipaes, Brucher 1989, Smith et al. 1992, and Clement

1999). It is possible, therefore, were planted by the people who lived in La Chonta 300-

400 years ago, but further studies at a bigger scale will be necessary to test this

hypothesis.

While palms are influenced by several disturbance regimes (Anderson et al. 1991,

McPherson and Williams 1998) they are commonly associated with human settlements

(Clement 1999, Morcote-Rios and Bernal 2001). There are several reasons to expect that

the B. gasipaes population of La Chonta is a relict of ancient cultivation. Despite

maximum age estimations of 50-100 years for each mature stem (Brucher 1989, Smith et

al. 1992, Mora-Urpi et al. 1997), the clone from which new stems emerge could be

centuries old, perhaps planted by former inhabitants. In addition, it is the only species I

studied that is considered fully domesticated (Clement 1999) and does not regenerate

naturally in La Chonta. However, several authors (Clement 1986, 1999, Mora-Urpi et al.

1997) recognize that there are different varieties of Bactris gasipaes, comprising a

continuum between domesticated and semi-domesticated varieties. In La Chonta, further

studies of seed/fruit ratios will determine where Bactris falls in this continuum. Similar to

Bactris, the small population of the semi-domesticated palm, Astrocaryum aculeatum

(Clements 1999), may also be a relict from earlier plantings given that it is generally









associated with human settlements (Wessels Boer 1965) and regenerates poorly in La

Chonta (Table 2-1). The fact that Bactris gasipaes and Astrocaryum aculeatum are not

significantly concentrated in the anthropogenic soils suggests in the past their

management was not restricted to TN and MO sites.

Existing short-lived species (less than 100 years old) could not have been planted

by former inhabitants of La Chonta because the area was abandoned more than 300 years

ago. For example, the maximum age of Inga spp. in La Chonta is estimated to be 117

years, while in Brazil Laurence (unpublished data) estimated the age of three species of

Inga to be between 50 to 160 years. While several species oflnga are considered semi-

domesticated, in particular Inga edulis, (Clements 1999), they are also dispersed by

monkeys (Andresen 1999) and regenerate well in La Chonta (Table 2-1). Consequently,

the apparent concentration oflnga spp. on MO soils (Figure 2-1 H) may be the product of a

secondary ecological adaptation rather than the result of enrichment by past inhabitants of

La Chonta.

The species with abundant regeneration, overall high densities, and no apparent

pattern of concentration according to soil type, such as Ampelocera ruizii and Sapindus

saponaria, may be wild species that are used by people, but past uses apparently have not

altered their present distribution in La Chonta. Ampelocera ruizii is not reported as

domesticated or semi-domesticated in the literature and has a fairly narrow distribution,

growing only in Brazil and the Bolivian lowlands (Table 2-1). In contrast, Sapindus

saponaria is extremely widespread, and is reported to be used by several indigenous

groups (Bruchner 1989). If the range Sapindus saponaria was expanded by humans, its









regeneration status and distribution (Table 2-1) suggest that it has become wild in La

Chonta.

The lack of apparent differences in the abundances of most of the species I studied

on the different soil types may be explained by numerous interacting factors that are

know to determine forest composition (topography, physiography, land use history, etc.)

as well as stochastic forces (Hubbell and Foster 1986). Certainly, edaphic and historic

factors alone are not enough to explain forest composition in La Chonta, but their

interactions with several other factors might do so. Clark et al. (1999) for example,

determined that the distributions of only 30% of the species they studied in a lowland

forest in Costa Rica were correlated with edaphic conditions, and concluded that only

mesoscale vegetation and soil sampling will estimate the true degree of edaphically

influenced distributions. A larger scale study in La Chonta and its surroundings,

integrating other environmental variables to the analysis may allow us to do the same.

One of the main factors influencing the results of this study might be the extended

period post-abandonment forest dynamics in the area. The two C-14 dates of charcoal

buried among pottery sherds in tierra negra site 3 (Chapter 1) suggest that the site was

probably inhabited most recently 380 and 430 years BP. This extended time since

abandonment might be sufficient to mask the effects of humans' enrichment with useful

species in the anthropogenic soil areas. In this time period, two or three generations of the

short-lived trees can have developed and biotic and abiotic seed dispersal processes may

have extended the species' distribution range beyond the TN patches, if they were indeed

initially concentrated there. In addition, disturbances such as fires and tree falls may

have played a role in the distribution of useful species.









It is also possible that TN areas were maintained as permanently cleared areas in

villages as they are and were in Amazonian Brazil (Heckenberger et al. 1999). If village

sites were maintained clear of vegetation with a large central plaza and compacted soils

(Heckenberger et al. 1999, Woods et al. 2000), it is likely that the perimeter of these areas

(MO and NTN areas) represent the agricultural zone that was enriched with useful

species. If this is true in La Chonta, the soils surrounding TN sites are those more

affected by past agricultural practices and are areas where useful species would have

been managed or cultivated. Consequently, NTN areas adjacent to TN areas might not

constitute a good control for testing the influence of past land-use practices on species

composition. A better control area would be a similar forest without a history of human

disturbances, which will be difficult to find.

The results of this study suggest that short-lived species with good regeneration and

no pattern of concentration in anthropogenic soils, while perhaps used by former

inhabitants, are now wild species that do not reflect the influence of past human use. In

contrast, large individuals of long-lived species with poor regeneration may in fact be

remnants of former cultivation. The lack of significant concentrations of useful species

in TN and MO soils suggests that species may have been cultivated or managed in

adjacent NTN areas and that plant communities on all sites were influenced by human

activities.













Table 2-1. Characteristics of tree species that are used by humans and selected for study in La Chonta.


Family

Anacardiaceae


Arecaceae


Arecaceae


Arecaceae



Arecaceae



Arecaceae




Bombacaceae


Leguminosae
(Mimosoideae)


Scientific name

Spondias mombin*


Astrocaryum aculeatum*


Astrocaryum murumuru


Attalea phalerata



Bactris gasipaes**



Syagrus sancona




Ceiba pentandra


Inga spp.*


Common Use
name
Ocorocillo Multiuse (edible fruit,
roots and medicinal
bark); cultivated.
Chonta de Multi-use (edible
anillo fruits and seeds, oil,
construction).
Chonta Multi-use (edible
fruits and seeds, oil,
construction)
Motaci Multi-use (edible
fruits and seeds,
medicine,
construction)
Chonta de Multi-use (edible
castilla fruit, medicine, bows,
construction);
cultivated.
Sumuque Multi-use
(construction, fruits
and seeds used to
attract game);
cultivated.
Hoja de Multi-use (religious,
yuca fiber, oil from seeds);
cultivated.
Pacay Edible fruit; Inga
edulis cultivated


Growth
form
Emergent


Geographical
distribution
Mexico to Bolivia.


Subcanopy Amazonia, from
Colombia to Bolivia


Canopy


Canopy



Canopy


Amazonia, from
Colombia to Bolivia

South and West
Amazonia, Peru,
Brazil and Bolivia.

Central America to
Bolivia.


Emergent Southwestern
Amazon and Eastern
Andes, from
Colombia to Bolivia.

Emergent Pantropical.


Subcanopy,
pioneer


Regeneration
statusa
Poor


Poor


Medium


Good



Poor



Medium




Poor


Genus is widespread Good
in tropics and
subtropics.













Table 2-1, Continued
Moraceae Batocarpus amazonicus Mururd Multi-use (edible Canopy Panama to Bolivia Poor
fruit, dye, latex)
Moraceae Pourouma cecropiaefolia Uvilla Edible fruit, Canopy, Costa Rica to Bolivia. Good
medicinal; cultivated, pioneer
Myrtaceae Eugenia sp. Arrayan Edible fruit Subcanopy Pantropical Good
Myrtaceae Myrcia sp. Sawinto Edible fruit Canopy Amazonia, Bolivia Poor
and Brazil
Sapindaceae Sapindus saponaria Isotouvo Soap from fruit, Subcanopy Arizona to Bolivia Good
medicinal
Sapindaceae Talisia sculenta Pit6n Edible fruit; Subcanopy Amazonia, from Poor
cultivated. Colombia to Bolivia.
Sapotaceae Pouteria macrophylla* Lucma Edible fruit Canopy Bolivia, Brazil and Good
Peru
Sapotaceae Pouteria nemorosa Coquino Edible fruit Canopy Disjunct, only in Good
Ecuador and Bolivia
Ulmaceae Ampelocera ruizii Blanquillo Edible fruit Canopy Bolivia, Brazil and Good
Peru

"Good = seedlings, saplings (<1.50 m), juveniles (>1.50 m) and adults present in the forest; Medium = juveniles and adults present, regeneration
scarce; Poor = only adults present, regeneration scarce. This classification is valid only for La Chonta.
* = Semi-domesticated; ** = Domesticated, according to (Clement 1999).













Table 2-2. Maximum diameters, mean growth rates for trees > 10 cm DBH, and mean annual diameter increment (MAI, based on 3
years of data) of the selected tree species in La Chonta, based on unpublished data from permanent sample plots of
BOLFOR Project. Estimated maximum age was calculated by dividing maximum DBH by MAI.


Scientific name


Spondias mombin
Astrocaryum murumuru
Astrocaryum aculeatum
Attalea phalerata
Bactris gasipaes
Syagrus sancona
Ceiba pentandra
Inga spp.
Batocarpus amazonicus
Pourouma cecropiaefolia
Eugenia sp.
Myrcia sp.
Sapindus saponaria
Talisia sculenta
Pouteria macrophylla
Pouteria nemorosa
Ampelocera ruizii


Maximum DBH
(cm)

121
40
16
48
18
26
200
73
85
74
37
83
51
52
99
150
110


Mean annual
diameter increment
(MAI, cm)
0.43






0.88
0.62
0.27
2.23
0.29
0.30
0.12
0.21
0.26
0.32
0.61


N
(for MAI)

61






15
55
62
16
12
209
166
31
100
219
410


Estimated maximum
age (years)

180


Overall mean abundance / ha
( one SE)
0.21 (+ 0.04)
0.91 (+ 0.12)
0.04 (+ 0.03)
0.41 (+ 0.07)
0.02 (+ 0.01)
0.37 (+ 0.07)
0.05 (+ 0.02)
0.49 (+ 0.12)
0.33 (+ 0.08)
0.06 (+ 0.03)
0.09 (+ 0.03)
0.60 (+ 0.21)
0.83 (+ 0.13)
0.17 (+ 0.05)
1.49 (+ 0.24
1.12 (+ 0.15)
3.51 (+ 0.38)













Astrocaryum aculeatum


016


NTN


NTN MO TN

Soil type
Astrocaryum murumuru


MO TN

Soil type


Attalea phalerata


NTN MO TN

Soil type D


Bactris gasipaes


06


05


NTN MO TN

Soil type


00

F


NTN MO

Soil type


Figure 2-1. Comparisons of the relative abundances (+ 1 SE) of the selected useful tree

species among the three different soil types: non-tierra negra (NTN, N = 14),

tierra morena (MO, N = 10), and tierra negra (TN, N = 14).


C


NTN MO TN

Soil type


Syagrus sancona


o 006


S004


0 02


0 00

E


Spondias mombin














Ceiba pentandra


Inga spp.


0


TN MO

Soil type

Batocarpus amazonicus


NTN

I


020

018

016
014

012

010
008

006

004

002

0 00
NTN MO TN NTN
Soil type
Soll type


Eugenia sp.


G


06


05


04


a 03


S02


01


00

I



025


S020

c
ao o
S015


5 010


005


000


K


MO TN

Soil type

'ourouma cecropiifolia


MO TN

Soil type


Myrcia sp.


NTN MO

Soil type


Figure 2-1. Continued


010


N


kU0-
NTN MO TN

Soil type


TN


N


I
















Sapindus saponaria


04


a)





M
1















3





2











0




5



4



a 3
o3
-o







o --


NTN MO

Soil type

Ampelocera ruizii




i


- 00

N





3


















P


NTN MO

Soil type


Pouteria nemorosa


NIN MU

Soil type


u --------- ^~ ~ ^
NTN MO

Q Soil type



Figure 2-1. Continued


NTN MO IN

Soil type


Pouteria macrophylla


Talisia sculenta















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BIOGRAPHICAL SKETCH

Clea Lucrecia Paz Rivera was born in La Paz, Bolivia. As a child, she lived in Peru,

Mexico, and Colombia, while her mother, a sociologist, was in political exile. While

living in these countries she developed a love and curiosity for the natural and cultural

diversity of Latin America.

As an undergraduate she studied biological sciences at the Universidad Mayor de

San Andres in La Paz. Her undergraduate thesis focused on the effects of cattle grazing

on floristic diversity in the savannas of Beni, Bolivia. She graduated with her

Licenciatura in 1998. She the worked as an associate researcher at the Herbario Nacional

de Bolivia, conducting floristic inventories in secondary forests in the Chapare region.

She also collaborated in the initial phase of the Catalog of Vascular Plants of Bolivia. In

2000, the Herbarium nominated her for a LASPAU/Fulbright fellowship. The fellowship

was granted and she began her graduate work in the University of Florida's

Interdisciplinary Ecology Program in Spring 2001, hosted by the Department of Botany.

Upon completing her master's degree, Clea will return to her country with her

husband and son. She intends to resume work at the Herbario Nacional de Bolivia and

explore dissertation topics.