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1 THE GROWING DILEMMA OF TIMBER HARVESTING IN BRAZIL NUT RICH, COMMUNITY FORESTS IN NORTHERN BOLIVIA: EFFECTS ON NATURAL REGENERATION AND FOREST DISTURBANCE By MARLENE SORIANO 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 2010
2 2010 Marlene Soriano
3 To Cor nelia, to whom I owe what I am Este logro es tambin tuyo Madre
4 ACKNOWLEDGMENTS I am very grateful to my mentor and committee chair Karen Kainer, for the trust and guidance she provided me along this journey. The expertise of my committee members, Christine Staudhammer and Jack Putz, greatly helped me to keep in the right track. I really appreciate their openness to directly learn from them throughout the development of this thesis. I am infinite ly grateful to the Amazon Conservation Leadership Initiative (ACLI) Program and the School of Forest Resources and Conservation, who provided me financial support. In particular, this thesis would have not been possible without ACLI funding. My sincere gra titude goes to the Instituto Boliviano de Investigacin Forestal (IBIF) and the Centro de Investigacin y Preservacin de la Amazonia (CIPA) for their encouragement and logistical support to carry out this research. Along the way towards pursuing my maste rs, there were many people who were keen to help in ways possible for them. First, I am greatly thankful to my colleagues and friends, Marielos Pea Claros, Bonifacio Mostacedo, and Eben Broadbent for writing letters of recommendation on my behalf, which a llowed me to embark on a masters program at the University of Florida (UF). Bonifacio and Eben were continuously motivating me to get this experience. I also want to thank them for their valuable feedback on earlier drafts of the main chapter of this thes is. I would also like to thank Martijn Slot, who indirectly motivated me to apply to UF to do my masters, and who was an excellent support during a good part of this experience. I want to thank Bonifacio Mostacedo and Zulma Villegas for their support as fr iends and as heads of my host institution, IBIF. I am very grateful to my colleagues Juan Carlos, Alfredo and Tita for facilitating information about Pando and field methods. Along the way to the fieldwork, there were key people who facilitated my stay in Pando. I want to express my gratitude to Marco Antonio Albornoz, Julio Rojas, and Wilder Suarez. The
5 support and interest expressed by the people from the communities were crucial for the successful completion of data collection and this material. I am esp ecially thankful to those who adopted the research goals as theirs. Thanks to the community representatives and landholders of the sites where this research took placeDon Pedro Paz, Don Donato Guarena, Don William Pedraza, Don Jesus Salvatierra, Don Oscar Capiona, and Don Juan Cuajerawhose willingness and interest in the potential outcome of this research were key to successfully completing the fieldwork. Two key players were very important to achieve the overall goals during fieldwork. I am deeply indebt ed to my brother Eduardo, who is also a forester and whose interest and enthusiasm on the research and the Amazon were motivating and contagious. His support greatly helped the fieldwork to go smoothly, and his presence made me feel safe at all times. I feel very lucky for having encountered so many knowledgeable and enthusiastic people throughout the fieldwork season, I was very fortunate for having encountered Jesus Aguilera Tingo in the first place, for whom, being young was not synonymous of inexperie nce in the forest; he was always keen to share his knowledge and learn new forest insights. Eduardo and Tingo were key people to advance with data collection at a steady pace while building capacity among other community landholders. Despite distance, the continuous support and love of my family: my parents Cornelia and Walter, my siblings Celia, Eduardo, and Carmencita, my nephew Wayan and niece Paola, and my sister in l aw Arminda, were essential for me to get through these years in a foreign country Spe cial thanks go to my friends in Bolivia, Eva Maria, Janeth, Daniel, Ang y Jackmina, Geovanna, and Kathelyn, who were always sending me good vibes and encouraging words. Despite my short stay in Pando, I greatly enjoyed the hospitality and friendship of Jac keline, Gonzalo, Marcelo, Harrison, Kevin, Guido, Gladys, Canela, Frank, Toyama, Mauricio, Cecilia,
6 Severo, and Lucas. I feel fortunate to have been given the opportunity to meet wonderful and experienced people at UF. I want to express special thanks to L aurita, Joysee, Carolina, Lauralu, Ana Alice, Sheryl, Mira, Joe, Wes, Pedro, Eric, Leo, Ane, Ana Carolina, Pepe, Walid, Linda, Tatiana, and to my lab friends (Marina, Jennifer, Joanna, Amy, Tita, Vivian, Shoana, and Christie), whose support and cheering, especially in difficult times, has been very important to get through the process of being a graduate student and simultaneously enjoy life. Finally, I want to thank the Tropical Conservation and Development program, an incredible community of faculty, staf f, and students who greatly enriched my education.
7 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................. 8 LIST OF FIGURES ........................................................................................................... 9 ABSTRACT ............................................................................................................................. 10 CHAPTER 1 INTRODUCTION ..................................................................................................... 12 2 THE GROW ING DILEMMA OF TIMBER HARVESTING IN BRAZIL NUT RICH, COMMUNITY FORESTS IN NORTHERN BOLIVIA: EFFECTS ON NATURAL REGENERATION AND FOREST DISTURBANCE ................................................... 15 Introduction .............................................................................................................. 15 Study Area ................................................................................................................ 18 Methods ................................................................................................................... 19 Field Data Collection ........................................................................................... 19 Data Analysis ..................................................................................................... 22 Results ..................................................................................................................... 24 Disturbance Responses to Formal and Informal Logging ......................................... 24 Explaining Brazil nut Regeneration ....................................................................... 25 Explaining Regeneration of Other Economically Important Species ......................... 25 Discussion ................................................................................................................ 27 The Brazil nut Case ............................................................................................. 27 The Case of Timber Species ................................................................................. 28 Disturbance Created by Formal and Informal Logging ............................................ 29 In the Shoes of Community Based Landholders ..................................................... 29 Is Multiple Use Forest Management Viable in Northern Bolivias Communities? ...... 31 3 CONCLUSIONS ....................................................................................................... 46 LIST OF REFERENCES .................................................................................................. 49 BIOGRAPHICAL SKETCH ............................................................................................. 53
8 LIST OF TABLES Table page 21 Key variables that differentiate formal from informal logging in community based landholdings in Northern Bolivia. ........................................................................... 33 22 Stand characteristics of fo rmal and informal logging sites ......................................... 34 23 Best models to explain density of individuals B. excelsa ..................... 35 24 Best models to explain density of individuals H. brasiliensis and seven timber species .............................................................................................. 36
9 LIST OF FIGURES Figure page 21 Geographic location of research sites in the department of Pando in the Bolivian Amazon ............................................................................................................... 37 22 Sampling design within each logged site. ................................................................. 38 23 Percent disturbed area created by formal (filled circles) and informal logging (empty circles) as a function of logging intensity expressed as: A. trees ha1, and B. m3 ha1. .... 39 24 Proportion of individuals logging disturbance by species ........................................................................................... 40 25 Density of individuals ormally logged sites by species ........................................................................................... 41 26 Density of individuals isturbance types and by species ............ 42 27 Density of individuals microsite : plot core vs edge of disturbance. ...... 43 28 Significant effects (p of individuals .......................... 44 29 Proportion of conspecific individuals and informal logging sites. ..................................................................................... 45
10 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 THE GROWING DILEMMA OF TIMBER HARVESTING IN BRAZIL NUT RICH, COMMUNITY FORESTS IN NORTHERN BOLIVIA: EFFECTS ON NATURAL REGENERATION AND FOREST DISTURBANCE By Marlene Soriano August 2010 Chair: Karen A. Kainer Major: Forest R esources and Conservation Desire for economic returns is stimulating increased logging in communally owned Brazil nut ( Bertholletia excelsa ) rich forests in Northern Bolivia. Building on previous research showing low logging damage to mature B. excelsa trees, we compared the effects of forma l and informal logging (with and without management plans, respectively) on natural regeneration (individuals timber species, B. excelsa and Hevea brasiliensis, and 10 timber species. Logging intensity was no different between forma l and informal logging (0.28 vs 0.24 trees ha1; p = 0.378). Contrary to our expectations and reported industrial scale findings, formal logging in these communities resulted in a larger percentage of disturbed area than informal logging (10.6% 0.65 SE v s 6.9% 1.26 SE; p = 0.012). This may be attributed to the fewer trees extracted in informal logging, and to the often ignored planning community landholders conduct with informal loggers prior to timber extraction. Regeneration densities of B. excelsa di d not differ between unlogged or formally or informally logged sites measured 25 years after logging. B. excelsa densities were, however, greater in larger logging disturbances (i.e. log landings vs. skid trails), corroborating our model in which canopy openness explained regeneration densities (p = 0.001). Regeneration responses of timber species varied by logging
11 treatment and type of disturbance, but all species demonstrated higher densities in the core zone (versus edge zone) of disturbed areas. Regeneration of two of the most commercially important timber species ( Swietenia macrophylla and Amburana cearensis ) rarely occurred, and only where conspecific trees were felled, implying that population recovery of select species may only occur with silvicul tural interventions. Findings that neither formal nor informal logging affected regeneration densities of B. excelsa within co mmunally logged forests suggest that multiple use Brazil nut timber may be viable under certain circums tances. Timber harvesting at low intensities as in our study sites (0.130.31 trees ha1 ) and integrating local knowledge and practices, such as opening short paths to reach target trees as practiced by community landholders, are two observed management features that may facilitate more sustainable multiple forest use. Integrating and adapting these and other practices, policies and support mechanisms that promote small versus large scale logging activities among communities could help bring traditional forest users into the lega l framework while also conserving biodiversity and reducing deforestation and forest degradation.
12 CHAPTER 1 INTRODUCTION The creation of both the land reform and the forestry laws in the late 1990s resulted in substantial changes in Bolivias rural social context and forestry system (Benneker, 2006). Most notably, it granted legal rights to forest dependent communities and included informal loggers into the legal framework. Although secure land tenure itself has the potential to encourage sustainable community forest management (Benneker, 2006; GarcaFernndez et al., 2008 ), whether these policies facilitate long term sustainability of community forests remain unknown. Meanwhile, informal logging is spreading at the same pace as timber market diversification, and so are the ways in which informal logging occurs. Despite the struggles of implementing the forestry law and dealing with increased ille gal logging in communally owned lands the combined area managed by indigenous and smallholders has risen to almost equal that of medium and large scale landowners (1.25 and 1.52 millions of hectares, respectively) (Superintendencia Forestal, 2007). Most of these managed areas have had external support and/or assistance from local governmental institutions or national and international nongovernmental organizations (NGOs). Still, support has not reached the majority of communities, particularly the smalle st ones, which usually have to rely on thirdparties to carry out most logging activities taking place in their forests. Although these third party loggers often comply with the basic rules of the forestry law within community lands, they rarely apply RIL techniques to prevent unnecessary damage and/or improve natural regeneration of commercially important species. Third parties perceive community owned forests as providers of immediate economic benefits; therefore, they tend to ignore the importance of th e forest for its long term productivity, provision of ecosystem services and biodiversity value. Despite the socioeconomic losses illegal logging represents to governments (Kaimowitz, 2007), informal logging can be up
13 to five times more profitable than for mal logging (Rice et al., 1997); thus, the ability to control forest activities weakens as illegal logging becomes increasingly widespread (Kaimowitz, 2007) and economically more interesting than formal logging (Rice et al., 1997). To guarantee long term timber yield, Bolivias forestry law largely relies upon generalized simulations on species growth and recovery rates (Dauber et al., 2005). In a wide range study of distribution patterns of tree species along Bolivian lowland forest s, Toledo (2010) has shown, however, that natural regeneration of each individual species responds uniquely to logging. Therefore, species specific forest management recommendations would enhance current generalized management guidelines. Another important measure to consider is t he extent of disturbance caused by logging, which range s between 5 and 50% of the logged area in tropical forests varying with harvest intensity, yarding method, and the care logging operators take to reduce logging impacts (Putz et al., 2001). For example increased logging intensity may cause significant mortality of advanced regeneration (Gerwing, 2002). Furthermore, logging high volumes of conspecific species would typically compromise re generation of young individuals, because most tropical tree species are found in low densities (Gerwing, 2002). However, f elling gaps from logging may have positive implications for natural regeneration, especially in the establishment of high value species (Gullison and Hardner, 1993; Jhons, 1996). Despite significant gains in our understanding of logging effects in tropical forests (Jhons, 1996; Pinard and Putz, 1996; Sist et al., 1998; Pereira et al., 2002; Pea Claros et al., 2008; Rockwell et al., 2007), the effects of logging at the communi ty and/or smallholder scale has been little studied. Furthermore, research about the effects of logging on natural regeneration for multipleuse forest management (i.e., non timber forest products timber) is minimal. More specifically, no published studies have looked at the effects of current logging practices formal and informalon natural
14 regeneration and extent of disturbance in community forests rich in Brazil nut ( Bertholletia excelsa) I investigated natural regeneration (individuals res ponses of 10 logged timber species, and 2 economically important non timber species (Brazil nut; and rubber, Hevea brasiliensis) to unlogged forest, formal, and informal logging. I characterized regeneration densities of examined species by type of disturb ance (i.e. skid trails, access roads felling gaps, and log landings), and location of individual plant s within disturbed areas (edge and core zone). Additionally, the extent of disturbance caused by formal and informal logging was estimated to compare di fferences in extent of logged area, number of logged species, logging intensi ty and percent of disturbed area between logging types (formal and informal). This thesis has a main chapter (Chapter 2) and two additional chapters (Chapters 1 and 3). Whil e Chapter 2 is a single, independent chapter prepared for submission to a peer reviewed journal, Chapters 1 and 3 provide a general contextual introduction and conclusions of the main themes of this paper, respectively.
15 CHAPTER 2 THE GROWING DILEMMA OF TIM BER HARVESTING IN BR AZIL NUT RICH, COMMUNITY FORESTS IN NORTHERN BOLIVIA: EF FECTS ON NATURAL REGENERATION AND FOR EST DISTURBANCE Introduction Interest in multiple use forest management (MFM) that integrates management for diverse products such as timber, n on timber forest products (NTFPs), and environmental services has increased globally in recent years ( Garca Fernndez et al., 2008 ). This holds particularly true in tropical regions where high biodiversity and carbon sequestration intersect with rural com munities dependent on these forest resources and the ecosystem services they provide (Smith and Scherr, 2003). MFM has been practiced for centuries by rural Amazonian inhabitants with the non timber sector historically driving regional economies. In recen t years, Brazil nut ( Bertholletia excelsa : Lecythidaceae family) has emerged as a key economic species for rural communities, particularly in Northern Bolivia where it not only provides cash and subsistence income, but also temporary nut collection and fac tory based processing jobs during the harvest season (Guariguata et al., 2008). As of 2006, Bolivia exported products of 66 forest species: 61 timber, and 5 nontimber species. Brazil nut was the single most economically important forest export species, co nstituting 39% (US$ 73 of $ 187 million) of the forest based national economy (Cmara Forestal de Bolivia, 2007). Furthermore, both Brazil nut and timber exports are steadily rising (Cmara Forestal de Bolivia, 2007), parallel to increased logging pressure on these Brazil nut rich forests (Cronkleton et al., 2009), often held on communally titled lands. The department of Pando serves as a nexus for these Brazil nut timber interactions where 245 peasant and 5 indigenous communities have legal title to 2 and 1.4 million ha of forest, respectively (Pacheco et al., 2009).
16 Prior to Bolivias 1996 forestry law (Ley 1700), forest dependent communities had no legal rights over the timber growing on the forests they inhabited. Timber rights were solely granted to large scale timber enterprises (Pacheco, 1998). The new legislation recognized the legitimacy of traditional communities, as well as a broad range of forest stakeholders, to timber harvest rights. These rights came with the legal responsibilities of developi ng a government approved General Forest Management Plan (GFMP) and Annual Operational Logging Plans (AOLPs). Within this legal framework, a 2025year harvest rotation is required, except in forest areas < 200 ha, in which case, a 5 year minimum harvest ro tation is recommended, but not required. They must also follow a series of logging restrictions and forest management guidelines known as Reduced Impact Logging (RIL), developed to enhance the likelihood that timber yields and forest integrity are sustain ed over the long term (Putz et al., 2000; Fredericksen and Putz, 2003; Zarin et al., 2007). AOLPs must be submitted each harvest year to obtain permits for timber extraction from a particular compartment area corresponding to a specific year stated in the GFMP. Logging is considered legal upon formal approval of these plans. Few communities, however, posses the capacity and capital to comply with the requirements of the forestry law by themselves (Martnez Montao, 2008). Thus, instead of solely conducti ng formal logging, many communities also engage in informal logging, commonly described as illegal logging. In contrast to the planning and harvest restrictions that characterize formal (legally approved) logging, informal logging is mainly based on extrac ting a few high value tree species (Table 2 1) such as mahogany ( Swietenia macrophylla), cedar ( Cedrela odorata), amburana ( Amburana cearensis ), and marfil ( Aspidosperma macrocarpon). In this system, landholders dispense with a formal inventory and road planning, opting instead to open short paths to target
17 trees they intend to sell to loggers (Table 2 1). These paths are often then used by loggers to extract the timber, either in th e form of cuartones (trunk sliced into sections), or as logs disguised with legal documentation from a separately approved AOLP submitted with overestimated volumes (Superintendencia Forestal, 2007; Martnez Montao, 2008). At the time of our fieldwork in 2009, though not comfortable with, nor perhaps even aware of breaking the law, most community based landholders were engaged in informal logging activities. Their reasoning was that over the long term, formal logging could not guarantee a steady provision of economic benefits. They also noted that revenues from informal logging were immediately available in difficult times such as illness or needed land or house improvements, whereas benefits from formal logging were often delayed. To what extent are these growing logging activities affecting the Brazil nut populations that serve as the economic mainstay of Pandos forest based communities? In this study, we address a set of questions to exam ine the effects of logging on new recruits and survivors post loggi ng densities of Brazil nut ( B. excelsa ), rubber ( Hevea brasiliensis ), and 10 timber species in two formally and four informally logged sites. Based on previous studies of secondary forests (Cotta et al., 2008) and gaps (Myers et al., 2000; Zuidema and Boot, 2002) that highlight a favorable response by B. excelsa to disturbance, we hypothesized that formal and informal logging would enhance B. excelsa re generation densities compared to those encountered in unlogged forest. Different types of logging disturbances ( i.e., skid trails, access roads, felling gaps, and log landings) in both formal and informal logging sites were also differentiated. To further explain mechanisms behind B. excelsa re generation we quantified the following variables within each disturbance type: core and edge zones of disturbed areas (hereafter referred as microsite zone ), distance to nearest conspecific
1 8 potential mother tree, and canopy openness. Similar questions were also address ed for H. brasiliensis, and 10 commercially important timber species. To better understand differences between formal and informal logging, we compared the extent of logged area, number of logged species, logging intensity, and percent of disturbed area. S ome studies have demonstrated that RIL such as required under formal logging in Bolivia, can reduce residual damage up to 50% compared to conventional informal (or illegal) logging (Pinard and Putz, 1996; Johns, 1996; Sist et al., 1998). Thus, we hypothes ized that informal logging will cause greater disturbance than formal logging. Study Area This study was implemented in six community landholdings in the p rovince of Filadelfia, western of the d epartment of Pando, Bolivia (Figure 2 1). Pando receives average annual rainfall of 1700 to 2000 mm, has a mean temperature of 26C, and a three month dry season (Mostacedo et al., 2006). Soils are classified as ferrasols (oxisols), with low fertility and high aluminum concentration. The diversity of tree species 0 cm dbh ranges between 52 and 122 species ha1, and average tree abundance ranges between 544 and 627 trees ha1The province of Filadelfia, Pando (our study site), is a hot spot for informal logging. A good proportion of informally extracted logs are confounded with legally extracted timber to fulfill the authorized timb er volumes from a managed area, and are then destined to carpentries installed in nearby cities or used in local building construction (Pacheco et al., 2009). (Mostacedo et al., 2006). Deforestation in Pando remains low compared to neighboring states in Brazil and Peru (Pacheco, 1998; Duchelle, 2009) attributed to its almost complete isolation from the rest of the country and to its long history of NTFP extractivism. Of the entire Bolivian Amazon, 50% is under collective ownership, and over 257 communities have been granted ~500 ha per family of Braz il nut rich forests (Guariguata et al. 2008).
19 Methods Field Data Collection Fieldwork was conducted in six forest sites logged between 2004 an d 2007, 2 to 5 years prior to data collection; two sites were formally logged and four were informally logged. Each logged site was spatially independent from the others, except for one site on which both formal and informal logging overlapped, but effects of each logging type could be evaluated independently. Within each logged site, all types of logging disturbances were easily distinguished and mapped using a Venture HC Garmin GPS; length of access roads and skid trails were calculated using Garmin MapS ource software. Formal logging sites had a preharvest defined area as a prerequisite to meet forest management criteria in Bolivias 1996 forestry law. In contrast, informal logging areas were not defined as in a formal management plan. To delineate these illdefined areas we used terrain observations and satellite imagery maps (i.e. Google EARTH PRO) to first identify the extent and location of logging induced disturbances such as skid trails, access roads, felling gaps, and log landings. Second, using b oth maps and ground inspection, we identified natural features such as wetlands, rivers, and/or slopes that often define borders of logged sites. We then integrated logging induced disturbance information with that provided by natural features to define ap proximate borders for informally logged sites. To test the veracity of this border delineation method, we followed the same procedure on our formally logged areas, and found that the resulting area using this method differed from the original, predetermined area listed on the formal management plan by less than 1%. This confirmed that our border delineation method was realistic and trustworthy for application in determining extent of disturbance on a per hectare basis.
20 To compare differences in regeneration densities between unlogged, formally logged, and informally logged sites, we established 7 to 10 plots in each disturbance type (skid trails, access roads, felling gaps, and log landings) within each logged site; and 9 to 10 plots within unlogged areas at each logged site (Figure 2 2). In total, we established 203 plots allocated as follows in each disturbance type (and formal and informal logging sites): 40 on skid trails (10 formal, 30 informal), 39 on access roads (19 formal, 20 informal), 57 in felling gaps (21 formal and 36 informal), 10 in log landin gs (6 formal, 4 informal), and 57 plots in unlogged areas (20 formal, 37 informal). The 7 to 10 felling gaps were randomly selected after identifying all felling gaps in each site; plot size in these gaps varied by extent of the disturbance caused by the felling tree. Plots in skid trails and access roads were systematically established every 25 m along the course of these disturbance types; plots were 25 m long, and plot width was determined by the disturb ance itself. Plots were installed in all log landings, with plot size varying according to the extent of the landing. The 9 to 10 plots in unlogged forests were located at a random direction typically from each sampled felling gap. Unlogged plots were 25 x 25 m, and were always located at least 50 m from any logging disturbance. To measure the extent of each disturbed plot, we extended a metric tape through the middle of the longest axis of each disturbance type, marking every 5 m along that axis (Figure 2 2). Then, we measured the perpendicular distance from each of these marked points, placing a flag at the edge of the disturbance limit (Contreras et al., 2001). The total area of each disturbance type included not only the core disturbed area but also an e dge zone that extended 2 (skid trails and access roads) to 3 m (felling gaps and log landings) into the forest (Figure 22). The core zone was defined by the edge of open overhead canopy, and the edge zone was defined as the area beyond that, where some in direct sunlight penetrated into the forest edge due to logging
21 disturbance. Edge zones were also distinguishable from undisturbed forest by the presence of coarse woody debris either caused by the felling of the logged tree or by the maneuvering of logging machinery. To calculate the total area (core + edge zone ) of each felling gap and log landing, we followed the method used by Contreras et al. (2001), dividing the whole area into two sub areas at each side of the middle axis: A1 = d [((dleft 1 + dleft n) / 2) + dleft 2 + dleft 3 + + dleft n 1A2 = d [((d )] (Equation 21) right 1 + dright n) / 2) + dright 2 + dright 3 + + dright n 1Where: )] (Equation 22) d = distance interval along the largest middle axis between two perpendicular distances dleft 1 + .. + dleft nd = distances from the middle axis to the left side of the plot right 1 + .. + dright nSubsequently, we measured canopy cover of the core disturbed area with a concave sph erical densiometer held at 1m height (Lemon, 1957). The exact location of the measurements varied according to disturbance type. For example, in tree fall gaps, measurements were taken at the stump, trunk, and crown zone of the felled tree, and were averag ed to obtain mean percent canopy openness by plot. On skid trails and access roads, measurements were taken at 5 and 20 m along the 25 m length of the middle axis. On log landings, we took one measurement in the center of the middle axis. The formula used to calculate percentage of canopy cover was as follows: = distances from the middle axis to the right side of the plot Canopy Cover % = 100% (# of empty squares x 4.17) (Equation 23) We obtained percent canopy openness by subtract ing the percent canopy cover from 100%. In each plot, we carefully searched and coun ted all regeneration (new recruits and survivors post logging 10 cm dbh ) of 2 non timber, and 10 timber species. We recorded height and stem diameter at the base if plant height was 1.5 m; otherwise, we measured dbh. We also recorded microsite zone (co re and edge) within the plot of each measured plant in each
22 disturbance type. However, when the number of individuals of any given species was > 50, we measured diameter, height, and microsite on only the first 50. To assess whether distance to potential m other tree affects regeneration densities, potential mother trees were searched up to 50 m starting from the border of the plot. This distance was originally selected for B. excelsa based on Cotta et al.s (2008) method regarding maximum seed dispersal a nd was standardized and used for all species. For B. excelsa potential mother trees were considered to be 40 cm dbh (K.A. Kainer, personal communication). Distance to, and dbh of the nearest potential mother tree were recorded in all 203 plots regardles s of whether regeneration of this species was encountered in the plot or not. Distance to, and dbh of, the nearest potential nearest mother trees of all other species were only recorded when individuals of that given species were found in the plot. For the se species, potential mother trees were considered to be those 20 cm dbh, applying a standardized diameter that approximates when most Amazonian tree species start producing fruits (Van Rheenen, 2005). In these cases, the influence of mother tree then responded to the question: Given the presence of regeneration of a given species, are densities explained by distance to the nearest potential mother tree? Data Analysis All statistical analyses were performed using SAS software (Version 9.2), and difference s were considered statistically significant at p values differences on extent of disturbance between logging treatments (2 formal and 4 informal) were small, the two sample non parametric test (PROC NPAR1WAY WI LCOXON) was performed to test differences between logged areas, number of logged species, logging intensities (trees ha1 and m3 ha1), and percent disturbed area. For this, t he continuity correction factor assumed in the computation of the standardized Z test statistics was removed using the correct = no statement in the SAS procedure.
23 A Generalized Linear Mixed Modeling procedure PROC GLIMMIX was used to predict regeneration densities by species as a function of logging type, distance to nearest potenti al mother tree, disturbance type, and microsite. However, due to low abundance of some species, the usage of this model was restricted to only 9 of the 12 examined species, 2 non timber and 7 timber species. The response variable (number of recruits and su rvivors post logging = regeneration density) was characterized as a Poisson distribution, using natural logarithm of plot area as an offset to properly reflect differences in plot sizes. To avoid statistical issues associated with overdispersion due to masting events of some species, regeneration density per sample unit included in the analysis was cut off at 1000 individuals, affecting only two species: H. brasiliensis and Astronium lecontei each masting event occurring in a different sample unit. Least squares means were al so generated, and adjusted using Scheffes method to account for multiple comparisons between logging types, disturbance types, microsite zones and distance classes to nearest potential mother tree. Three models were explored to explain B. excelsa regener ation density. Model 1 tested whether the three logging treatments (unlogged, formal, and informal logging), canopy openness, and/or distance to nearest potential mother tree explained regeneration densities (N = 196). For purposes of analysis, distances t o nearest potential mother trees were classified in seven classes: A first class was set for trees encountered within the plot, five represented sequential 10 m intervals, and a sixth for distances > 50 m from the border of each plot. Model 2 explored the effects of type of logging disturbance (felling gap, skid trail, access road, and log landing), and therefore excluded plots in unlogged sites (thus, N = 143) from Model 1. Finally, Model 3 only used those plots where B. excelsa individuals were present (N = 49), to explore whether microsite zone helped explain densities (Table 2 3).
24 Similar methods and logic used for B. excelsa were followed to model regeneration densities of all other species. Because distance to nearest potential mother tree for all other species was only recorded when individuals of that particular species was encountered in a particular plot, a most basic model (Model 0) was run. Thus, Model 0 only accounted for two explanatory variables, logging treatments and canopy openness, to obtai n differences between logging treatments based on a larger sample size (195 196 plots). Models 1 and 3, which used potential mother tree as an explanatory variable, considered the logged species as a potential mother tree for individuals encountered within examined felling gaps. For some of these species ( H. brasiliensis, C. odorata, Hymenaea parvilofia, and Mezilaurus itauba), Model 3 showed slightly high chisquare statistics, indicating poor model fit. However, alternative models to Model 3 did not impro ve the chi square statistic, and although residuals indicated no heteroscedasticity, results should be viewed conservatively. The effects of formal and informal logging on regeneration density of three conspecific logged species, as well as the proportion that each species represented by the twelve examined species found in the 203 plots, were compared using descriptive statistics in Microsoft Office Excel 2007. Results Disturbance Responses to Formal and Informal Logging Although logging intensity did no t differ between formal and informal logging (0.28 vs 0.24 trees ha1, p = 0.184; 1.8 vs 1.6 m3 ha1, p = 0.486), formal logging resulted in more species logged in a given logging site (61 3.0 SE vs. 23 8.4 SE; p = 0.047) and a larger portion of distur bed area (10.6% 0.6 SE vs. 6.9% 1.26 SE; p = 0.047) than informal logging (Table 22). Despite no differences between formal and informal logging intensities, formal logging sites had the greatest percent of disturbed area (Figure 2 3).
25 Explaining Braz il nut Re generation Relative regeneration abundance (individuals B. excelsa was very low proportional to a pool of twelve species (0.67% of 100%) (Figure 24). Regeneration densities did not differ between logging types (3.9 1.3 ind. ha1 in unlogged, 7.6 1.7 ind. ha1 in formally and 5.8 1.2 ind. ha1 in informally logged sites, respectively; p = 0.315) (Figure 25; Table 2 3) nor with distance to potential mother trees (p = 0.477) (Table 2 3). Differences were, however, observed be tween disturbance types (p = 0.0272) (Table 23). Specifically, regeneration in log landings (15.1 7.2 ind. ha1) was significantly higher than in skid trails (2.9 1.2 ind. ha1) (Figure 2 6). Interestingly, differences between microsites (core versus edge of disturbed area) were observed for all species other than B. excelsa (14.6 3.0 vs 17.1 3.4 ind. ha1Explaining Re generation of Other Economically Important Species ; p = 0.444) (Figure 27; Table 2 3). Regeneration of A stronium lecontei, C. odorata, H. brasiliensis and M. itauba were four of the most abundant species found within all plots (unlogged, formally and informally logged) and across all types of disturbances (Figure 2 4). In contrast, individuals of A. cearensis and S. macrophylla were rare, representing only 0.04 % and 0.21% of the 12 studied species respectively and these species were only found in felling gaps where conspecific trees were felled (Figure 24). When comparing regeneration densities between logging treatments, only densities of three species varied between unlogged and formally logged sites; C. odorata (8.6 2.9 vs 39.8 9.3 ind. ha1; p = 0.001) and Dipteryx odorata (3.0 1.4 vs 14.1 4.4 ind. ha1; p = 0.030) had higher densities in formally logged sites, wher eas M. itauba had higher densities in unlogged sites (114.0 18.5 vs 60.4 9.5 ind. ha1; p = 0.017) (Figure 25; Table 2 4). In all three cases, densities did not differ between formally or informally logged sites (Figure 25).
26 Some species demonstrated differences in regeneration densities between types of logging disturbances. Aspidosperma vargasii presented lower densities on skid trails (31.1 8.4 ind. ha1) and access roads (15.7 4.3 ind. ha1) than in felling gaps (84.2 16.6 ind. ha1) (p = <.0001). D. odorata had higher densities in log landings (198.1 136.7 ind. ha1) than on skid trails (7.0 3.1 ind. ha1), access roads (10.4 3.9 ind. ha1), and felling gaps (17.1 5.1 ind. ha1) (p = 0.002). Higher regenerati on densities of Hymenaea parvifolia were observed in felling gaps (24.2 6.7 ind. ha1) and log landings (103.7 70.7 ind. ha1) than on skid trails (2.7 1.2 ind. ha1) and access roads (2.9 1.3 ind. ha1) (p = <.0001). Similarly, M. itauba also had higher densities in felling gaps (173.2 23.2 ind. ha1) and log landings (227.8 78.1 ha1) than on skid trails (36.2 6.9 ind. ha1) and access roads (40.2 7.2 ind. ha1Regarding regeneration microsite prefere nces, all species had higher densities at the core than the edge of disturbed areas (p 7; Table 2 4). Recruitment densities of A. vargasii (p = 0.024 ), A. lecontei (p = 0.001), C. odorata (p = 0.003), D. odorata (p = 0.014), H. parvifolia ( p <0.0001), and T. impetiginosa (p = 0.001) differed with distance to nearest potential mother tree (Table 2 4). Greater densities were observed at shorter distances, and then gradually decreased at further distances (Figure 2 8). ) (p = <.0001) (Figure 26; Table 24). Individuals from the th ree most dominant species were identified within felling gaps, to specifically determine whether the species logged affected regeneration of a particular species. Regeneration of two species, M. itauba and A. vargasii were always among the three most abundant species (reaching up to 70 and 47% of all species), regardless of the species logged. R egeneration from C. odorata, D. odorata, and H. parvifolia were consistently among the three most abundant in conspecific felling gaps where these species were logg ed, 41%, 34% and 43%,
27 respectively, indicating a high degree of conspecificity in regeneration establishment. Only three species were logged in both formal and informal logging sites ( A. cearensis, C. odorata, and D. odorata). Of these, only C. odorata sho wed differences a higher proportion of regeneration in formally logged than in informally logged sites (Figure 29). Discussion The Brazil n ut Case Despite being considered a gap dependent species (Myers et al. 2000; Zuidema and Boot 2002), and demonstrati ng comparatively higher regeneration densities (individuals in abandoned agricultural fallows than in mature forests (Cotta et al., 2008), we found no differences in B. excelsa regeneration densities between unlogged and logged (neither formal nor informal) sites. However, higher densities were observed in larger logging disturbances (i.e. log landings vs skid trails) (Figure 2 6). Still, no differences were found in B. excelsa preferences regarding microsite zone ; the higher incidence of light in the core of disturbed plots did not translate into higher regeneration densities than within edge zones. This finding may be a reflection of the habitat preferences of seed dispersers (Chen et al. 1999). The logging debris usually encountered on the ed ges of logging induced disturbances provides a measure of safety to seed dispersers such as agouti ( Dasyprocta spp. ) while they eat and bury B. excelsa seeds. Individuals of this species are often found within accumulated debris or behind a tree stem (Peres and Baider, 1997; personal observation, M. Soriano). The lack of relationship between regeneration density and distance to nearest potential mother trees contrasts with findings of Cott a et al. (2008), who found a positive correlation between proximity to mother trees and B. excelsa regeneration densities. Lack of effects could be explained by the high density of adult trees in our sites, and/or that seed reburial at long distances by ag outis played an important role in seed dispersal (Tuck Haugaasen et al., 2010) and thus on its establishment. Our overall finding
28 that low logging intensity did not negatively affect regeneration of this keystone species complements Guariguata et al.s (20 09) results of minimal logging damage to B. excelsa trees 10 cm dbh in certified forest concessions in which RIL guidelines were followed. The Case of Timber Species Logging under the conditions of our study sites resulted in greater regeneration of two important species; both, D. odorata and C. odorata had higher densities in logged areas than in unlogged forest. In addition, regeneration densities of all timber species tended to be higher on log landings and in felling gaps than on skid trails and acces s roads. This finding is consistent with others that demonstrated that many commercial timber species respond favorable to higher light environments (Licona Vasquez et al., 2007; PeaClaros et al., 2008). We also found that, with the exception of A. lecon tei canopy openness positively affected regeneration densities of all timber species examined, as well as H. brasiliensis These species also had higher densities in the higher light microsites (core vs edge of disturbed areas). Some species (e.g., A. ce arensis, C. odorata, and D. odorata) showed high regeneration densities of conspecific logged species, probably because seedfall of these species coincided with logging season in Northern Bolivia. This suggests that the time of year when species are logged (mid to end of the dry season) can be planned to stimulate regeneration establishment (Mostacedo and Pinard, 2001; Soriano Candia, 2005). The fact that individuals of two of the most important timber species, A. cearensis and S. macrophylla, were rarely e ncountered in the study plots (each representing less than 1% of total counted individuals from all species) is attributed to historical logging intensity of these high value species (Putz et al., 2001) that has depleted them over time. Regeneration of bo th species only occurred in felling gaps where these species were logged, implying that population recovery may only occur once selective logging of
29 these species is halted followed by intervention with silvicultural treatments (Fredericksen and Pariona, 2 002). Disturbance Created by Formal and Informal Logging Our hypothesis was not supported on that the extent of logging disturbance would be greater in informally (illegally) logged sites than in those with approved management plans (formally logged) as documented in multiple studies (Johns, 1996; Pinard and Putz, 1996; Sist et al., 1998; Pereira et al., 2002). Contrary to expectations, we found that formally logged sites incurred a greater percentage of disturbed area than informally logged sites. While p revious studies were carried out within large (industrial) scale logging operations, logging activities in our communally owned sites were relatively small scale. The observed comparatively lower extent of disturbance in our informally logged sites may be attributed to two reasons; first, the opening of short paths to reach target trees tended to reduce felling of non target trees. A study of smallscale RIL logging within communities in Acre, Brazil also attributed their finding of no effects from marking future crop trees to the fact that landholders marked paths to guide skidding activities (Rockwell et al., 2007). Secondly, logging intensities, and number of trees logged, were lower in informal than in formal logging areas In the Shoes of Community B as ed Landholders Undoubtedly, formal logging has the potential to return significant economic benefits to forest dependent communities (Benneker, 2006); however, under the circumstances of the community landholdings we examined, this was not entirely evident First, formal logging resulted in a greater relative disturbed area than informal logging, and a greater number of trees logged, perhaps more than was necessary to maintain a familys livelihood at a given year. Indeed, formal logging (versus informal lo gging) often results in extraction of greater timber volumes; according to the current forestry law up to 80% of all trees above the minimum
30 diameter cutting can be removed from a managed forest Formal logging may also threaten the long term economic sus tainability of a familys forest. A familys entire productive forest is usually around 200 ha; therefore, formal timber harvesting is often carried out in a single year, extracting most commercial stems, to cover the greater planning requirements and related costs dictated by formal logging. (Cronkleton et al., 2009). A lack of sufficient areas to harvest in subsequent years could increase pressure over the originally logged area to harvest seed trees (C. Borobobo, personal communication), although new sp ecies, for which there was no market demand during the first logging, may also be tapped in subsequent years. Finally, in practice, not all felled trees that are formally logged in any given year make it to the market. This translates into substantial economic loses for smallholders, because third parties do not pay for those logs that remain in landholders forest to rot (Benneker, 2006; P. Paz and C. Borobobo, personal communication). Thus, Martnez Montao (2008) reports that community people conclude th at formal logging can be worse than informally selling smaller quantities of high value, illegally logged timber species Indeed, formal logging may also affect smallholder livelihoods negatively by: (1) indirectly prohibiting small scale timber production; (2) requiring complex paperwork that forest people are uneasy to complete by themselves, (3) prohibiting traditional activities such as hunting, although we certainly acknowledge that not all game harvests are sustainable in managed forests for timber, and, (4) advocating that creation of no take zones within communities is the best alternative for forest conservation. From the community standpoint, it has become nearly impossible to comply with GFMP requirements without technical assistance and economic support of external institutions (Benneker, 2006; Martnez Montao, 2008; Cronkleton et al., 2009).
31 Furthermore, roads built under formal logging regimes are often used as a conduit for informal loggers and wildlife poachers to access remote areas that were otherwise inaccessible. In reality, some formally managed forests are being degraded by informal loggers, leading indirectly to deforestation (Asner et al., 2006; personal observation, M. Soriano). In view of these constraints, informal logging may also be comparatively more compatible with community based landholders forest management and conservation objectives than formal logging as carried out under the current forestry regime. Is M ultiple U se Forest Management Viable in Northern Bolivias Communiti es? Findings that neither formal nor informal logging affected regeneration densities of B. excelsa within communally logged forests suggests that multiple use, Brazil nut timber forest management may be viable under certain circumstances. First, and perh aps most importantly, all our study sites were harvested at low intensities (0.13 0.31 trees ha1), falling within the lowest range of logging intensities found in the literature (Jhons, 1996; Sist et al., 1998; Rockwell et al., 2007; Guariguata et al., 2009). Secondly, the extensive forest based knowledge and the earlier described unforeseen management practices (i.e., guiding skid trails for informal loggers) carried out by community based landholders could smooth the road towards sustainable management i n practice. In our efforts to understand the dilemma on whether timber harvesting could be compatible with sustaining the keystone non timber species B. excelsa results suggest that both B. excelsa and most examined timber species regenerate successfully. Unexpectedly, neither formal nor informal logging proved totally incompatible with Brazil nut harvests. Nonetheless, despite low observed disturbance effects of informal logging (Rice et al., 1997), a sole focus on harvesting high value species which disr egards its reproductive ecology, has been detrimental for the long term population viability of those species (Figure 24).
32 We believe that governmental and nongovernmental regulations, policies and support mechanisms should promote small scale rather than large scale logg ing activities among community based landholdings Integrating traditional knowledge, and developing simplified and integral legal procedures and guidelines to improve the current forestry system (Martnez Montao, 2008) would not only bri ng traditional forest users into the legal framework, but would also reduce deforestation and forest degradation and have positive implications for biodiversity conservation.
33 Table 2 1. Key variables that differentiate formal from informal logging in community based landholdings in Northern Bolivia. Few exceptions may exist to given logged areas on the current table. Issue Formal logging Informal logging Timing of harvest Every 20 25 years Varies according to cash needs Target species Commercial species High value species only (1 5) Remnant seed trees 20% of harvestable trees Unknown Inventory Tree census Exploratory Basis for road planning Maps, tree census Seek shortest distance between trees Capital needs High Low Logging entity/loggers Timber companies, sawmills Experienced and inexperienced sawyers, landholders, sawmills, timber companies Logged area* > 200 ha < 200 ha
34 Table 2 2. Stand characteristics of formal and informal logging sites. Values with an asterisk indicate significant differences at onesided p for the two sample Wilcoxon test. Logging type Logging site Year of logging Logging equipment Logged area ha (SE) #logged species (SE) Log ging intensity (SE) % disturbed area (SE) trees ha 1 m 3 ha 1 Formal JS 2007 Skidder 225.6 7 0.28 1.6 11.2 PP 2004 Caterpillar 203.8 10 0.28 1.9 9.9 Mean 2 214.7 (10.9) 8.5 (1.5) 0.28 (0.0) 1.8 (0.15) 10.6 (0.65) Informal JS 2007 4 wheeled drive truck 271.0 4 0.13 1.3 5.3 WT 2005 Skidder 153.6 5 0.25 1.2 7.2 DG 2007 Skidder 25.6 1 0.27 1.4 6.1 OC 2006 Skidder 32.0 3 0.31 2.5 9.1 Mean 4 120.5 (58.15) 3.3 (0.85) 0.24 (0.04) 1.6 (0.30) 6.9 (1.26) Pr(<0.05) 1 sided 0.1879 0.0468* 0.1845 0.4857 0.0468* Pr(<0.05) 2 sided 0.3757 0.0937 0.3691 0.3757 0.0937
35 Table 2 3. Best models to explain density of individuals 10 cm dbh of B. excelsa Different models were used to maximize the number of observations under the sampling scheme employed. Model 1 tested whether logging treatments (unlogged, formal and informal logging) and distance to nearest potential mother trees affected regeneration densities. Models 2 and 3 excluded unlogged plots to tes t whether densities differed between d isturbance types ( skid trails, access roads, felling gaps, and log landings) and microsite zones (core and edge of disturbances). Significant differences at p 0.05 are marked with an asterisk. Model # plots Log likelihood Chi square Fixed effects canopy openness logging treatment disturbance type microsite distance mother 1 196 762.69 0.69 0.0009* 0.3146 0.4768 2 143 544.88 0.71 0.0911 0.5536 0.0272* 3 49 319.46 1.25 0.1430 0.8210 0.7832 0.4443 0.1672
36 Table 2 4. Best models to explain density of individuals H. brasiliensis and seven timber species. Different models were used to maximize the number of observations under the sampling scheme employed. Models 0 and 1 tested whether regeneration densities differed between logging treatments (unlogged, formal and informal logging ), and distance to nearest potential mother trees respectively. Models 2 and 3 excluded data from unlogged plots to test whether densities differed between disturbance types (skid trails, access roads, felling gaps, and log landings) and microsite zones (c ore and edge of disturbances). Significant differences at p are marked with an asterisk. Species Model # plots Log likelihood Chi squar e Fixed effects canopy openness logging treatment disturbance type Microsite distance mother Hevea brasiliensis 0 195 982.60 0.61 0.4872 0.0945 1 36 119.99 1.00 0.1398 0.4072 0.0901 2 142 703.07 0.61 0.4883 0.0386* 0.5769 3 29 379.21 5.89 0.4424 0.5714 0.5713 <.0001* 0.4100 Timber species Aspidosper ma vargasii 0 196 724.65 0.99 0.0038* 0.4257 1 153 481.60 0.95 0.0926 0.9817 0.0238* 2 143 525.89 0.95 0.2545 0.4685 <.0001* 3 109 874.89 2.02 0.0843 0.6277 0.362 <.0001* 0.0630 Astronium lecontei 0 195 790.85 0.89 0.4892 0.0448* 1 100 300.02 0.90 0.2990 0.0277* 0.0013* 2 142 581.40 0.92 0.6629 0.2927 0.1930 3 80 599.28 1.69 0.8357 0.1360 0.8307 <.0001* 0.0070* Cedrela odorata 0 195 791.56 0.87 <.0001* 0.0014* 1 114 368.50 0.93 <.0001* 0.1886 0.0033* 2 142 560.42 0.94 <.0001* 0.1363 0.3227 3 102 1009.87 2.95 0.0083* 0.7126 0.6921 <.0001* 0.3043 Dipteryx odorata 0 196 888.19 0.74 <.0001* 0.0302* 1 66 202.05 0.91 0.0004* 0.0129* 0.0144* 2 143 621.01 0.83 0.0141* 0.7204 0.0016* 3 59 469.59 1.87 0.0437* 0.0143* 0.0548 <.0001* 0.3641 Hymenaea parvifolia 0 196 858.95 0.80 0.9772 0.7283 1 80 238.44 0.80 0.2780 0.2582 <.0001* 2 143 618.66 0.74 0.0020* 0.5707 <.0001* 3 57 604.26 2.80 0.2467 0.4041 0.3151 <.0001* 0.3672 Mezilaurus itauba 0 196 616.92 1.03 <.0001* 0.0169* 2 143 425.53 1.00 0.9570 0.0013* <.0001* 3 125 924.71 2.19 0.0016* 0.0076* <.0001* <.0001* 0.7997 Tabebuia impetiginos a 0 196 906.66 0.49 0.0488* 0.0311* 1 34 82.18 0.76 0.4015 0.9708 0.0009* 2 143 667.52 0.49 0.5008 0.0063* 0.0399* 3 28 218.55 1.74 0.6567 0.4835 0.0689 <.0001* 0.0006*
37 Figure 21. Geographic locati on of research sites in the d epartment of Pando in the Bolivian Amazon.
38 Figure 22. Sampling design within each logged site.
39 A B Figure 23. Percent disturbed area created by formal (filled circles) and informal logging (empty circles) as a function of logging intensity expressed as: A. trees ha1, and B. m3 ha1.
40 Figure 24. Proportion of individuals disturbance by spe cies. Timber species are represented by filled bars, and nontimber forest products ( NTFPs ) species are represented by light colored bars.
41 Figure 25. Density of individuals ogged sites by species. Different letters represent statistical differences at p
42 Figure 26. Density of individuals d ifferences at p
43 Figure 27. Density of individuals microsite : plot core vs edge of disturbance. Different letters represent statistical differences at p ificant differences.
44 Figure 28. Significant effects (p individuals
45 Figure 29. Proportion of conspecific individuals cm dbh for species logged in both formal and informal logging sites.
46 CHAPTER 3 CONCLUSIONS Multiple use forest management (MFM) is a new concept that is becoming prominent worldwide ( Garca Fernndez et al., 2008) Since timber exploitation started to take place in Northern Bolivia, unmanaged mixed forest use has simultaneously been occurring to the harvesting of nontimber forest products (NTFPs) MFM has been perceived as being especially important and relevant t o the sustainability of these forests because B. excelsa has grown into a worldwide consumed tropical nut solely harvested from the wild. Some certification efforts to counteract potential effects of logging to B. excels as population and /or nut production have taken place in this region. For example, certified landholdings are prohibited to harvest timber in either formal or informal ways (Duc helle, 2009). Brazil nut is particularly abundant in Northern Bolivia where hundreds of communiti es rely on its nuts, which are considered the most important source of cash income for the entire region and have converted Bolivia into the largest exporter of B. excelsa in the world. The extent of dependency on B. excelsa nuts has proven to be high est in this region, followed by revenues from timber. A study of fourteen forest dependent community and social organizations assisted by an NGO for timber harvesting under management in lowland Bolivia indicated that 12% of family income in this region relies on nontimber forest products (mostly due to B. excelsa nuts) compared to only 02% in other forest dependent regions (Aguilar, 2008). Therefore the income dependency by nonassisted communities o n this species might be greater than those assisted commun ities. Furthermore, intensive cattle ranching and selective logging are acquiring growing interest in this region (Pacheco et al., 2009); as a result, pressu re for non sustainable usage of Brazil nut rich forests is also meant to increase. If not appropriately tackled, current trends may have immeasurable consequences for these forests and peoples livelihoods.
47 In this research we evaluated three different logging treatments (unlogged, formal and informal logging) and the extent these logging treatments ar e affecting natural regeneration (individuals timber and timber species. We concluded that logging intensities are not different between unlogged, formal and informal logging, but that informal logging, as pract iced by community based landholders, causes less forest disturbance than formal logging. While B. excelsa regeneration was unaffected by logging treatment or its location within a microsite zone (core or edge of disturbed areas), larger logging caused dist urbances (log landings vs skid trails) presented higher densities of this species. Regeneration densities from about half of examined species differed between logging treatments (N = 3 out of 8), logging disturbance (N = 4 out of 8), and all species prefer red the core over the edge of disturbed areas. Somewhat worrisome is the low abundance of two of the most economically important timber species, S. macrophylla and A. cearensis For these species, our analysis could not be properly run due to lack of occur rence in most sampled plots, an indication that these species urgently require silvicultural intervention to enhance their regeneration. Based on our results, it is clear that species specific management planning will be necessary to prevent lack of forest productivity of valuable species such as C. odorata, T. impetiginosa, and D. odorata over time. Although B. excelsa was the third species with the lowest abundance compared to the other examined species, the majority of B. excelsa regeneration has higher chances to survive over the long term (97% in fallows, and 100% in mature forests; Cotta et al., 2008). R estricting forest use by establishing no take areas within community lands might not be the only way for long term conservatio n of these forests R esults suggest that more sustainable efforts may be made to halt informal logging occurrence in these forests: by (1) encouraging low
48 intensity logging, (2) implementing combined traditional and scientific knowledge based management ac tivities, and (3) making incentives available to promote the utilization of silvicultural treatments among smallholders.
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53 BIOGRAPHICAL SKETCH Marlene Soriano was born in 1980, in Omereque, Campero province, Cochabamba, Bolivia. She grew up in the Valles Cruceos region in Santa Cruz. She received a Bachelor of Science degree in Forestry from Universidad Autnoma Gabriel Ren Moreno, Santa Cruz, Bolivia in 2006. She carried out her bachelors thesis with the Bolivian Institute for Forestry Research ; and since then, she has assisted and carried out research through various research projects along the different f orest types in lowland Bolivia. Her research experience ranges from evaluating forest dynamics in mature forests, logged forests, and seco ndary forests, to estimating carbon for Reducing Emissions from Deforestation and Degradation (REDD) projects She has collaborated with various types of local institutions, from researchers at Stanford University to forest dependent communities. In 2008, she enrolled in a graduate program at University of Florida in the School of Forest Resources and Conservation with a concentration in Tropical Conservation and Development. He r m aster thesis was conducted in collaboration with forest communities in Northe rn Bolivia where she previously worked and which greatly influenced her decision to pursue a graduate program. Her future plans are related to linking community conservation efforts to REDD programs by building capacity through participatory research.