IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment

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IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment
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Fox, Alison M.
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
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SS-AGR-225 IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment1 Alison M. Fox, Doria R. Gordon, Joan A. Dusky, Linda Tyson, Randall K. Stocker, Kenneth A. Langeland, and Aimee L. Cooper2 1. This document is SS-AGR-225, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised publication date: April 2009. In IFAS Extension publications this document should be cited as: Fox, A.M., D.R. Gordon, J.A. Dusky, L. Tyson, R.K. Stocker, K.A. Langeland, and A.L. Cooper (2009) IFAS Assessment of Non-Native Plants in Florida's Natural Areas: Status Assessment. Cited from the Internet December 2009, http://plants.ifas.ufl.edu/assessment/pdfs/status_assessment.pdf 2. Alison M. Fox, emeritus associate professor, Agronomy Department, University of Florida, Gainesville, FL; Doria R. Gordon, Director of Conservation Science, The Nature Conservancy and Courtesy Professor, Department of Biology, University of Florida, Gainesville, FL; Joan A. Dusky, professor and associate dean for Extension, University of Florida, Gainesville, FL; Linda Tyson, professor, Santa Fe Community College, Gainesville, FL; Randall K. Stocker, emeritus professor, Agronomy Department, University of Florida, Gainesville, FL; K. A. Langeland, professor, Agronomy Department and Center for Aquatic and Invasive Plants, University of Florida, Gainesville, FL; and Aimee L. Cooper, biological scientist, Agronomy Department and Center for Aquatic and Invasive Plants, University of Florida, Gainesville, FL. The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean Purpose The purpose of the IFAS Assessment of Non-Native Plants in Florida's Natural Areas (IFAS Assessment) is to provide a well-defined system for distinguishing invasive, non-native plant species from those that are not invasive in Florida's natural areas. The IFAS Assessment conclusions allow consistent description and categorization of non-native plants in all IFAS Extension publications. The conclusions are intended to prevent invasion or reduce the likelihood of continued invasion of non-native species in Florida's natural systems. Development of a common basis for decisions will increase consistency and understanding of recommendations made by IFAS personnel about these species. The IFAS Assessment has specific requirements for documentation to support all relevant evidence, which reinforces the transparency and credibility of the process. The IFAS Assessment is intended to be useful in developing priorities for research and management efforts, and can be adapted for use in other states. (For definitions of terms as used in this document see Glossary, at the end). The IFAS Assessment has three components: the Status Assessment (this document), the Predictive Tool, and the Infraspecific Taxon Protocol. All three components along with a more detailed description of how the IFAS Assessment was developed are available at http://plants.ifas.ufl.edu/assessment/. The Status Assessment is only intended for plants that currently occur within Florida. It is not intended to provide evaluations of species that have not yet been introduced to the state. Those species would be


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 2 assessed using the Predictive Tool, which uses the Australian Weed Risk Assessment (Pheloung et al. 1999) system adapted for use in Florida (Gordon et al. 2008) ( http://plants.ifas.ufl.edu/assessment/pdfs/ predictive_tool.pdf). Additionally, the Status Assessment directs use of the Predictive Tool for: 1) species that have not escaped into Florida's natural areas but are either recent arrivals to the state or are known to cause problems in areas with habitats and climate similar to Florida's habitats and climate; or 2) species for which there are proposed new uses that would result in higher propagule pressure2 in Florida (see question I-a-1, below). In all likelihood, the Status Assessment will identify fewer than 1 percent of all non-native plant species in the state as showing ecological impacts in natural areas. The Status Assessment is designed to identify those non-native plant species that are invasive in areas of Florida where designated management objectives include the conservation of native biodiversity. A range of activities may be conducted in such areas, but those activities should be compatible with the conservation objective of the natural areas. State and local governments and some private landowners, for example, manage natural areas both for economic values (recreation, grazing, forestry or other harvest values) and for conservation values. These areas with multiple uses would be designated as natural areas in the IFAS Assessment, with clearly identifiable "non-natural" edges disregarded. Species that invade only the identified edgesareas next to roads, trails, fire lanes, recent dredge spoil, expanses of bare soil, etc.will not be identified as invaders with impacts in natural areas because their persistence and spread is limited to those anthropogenically disturbed zones in the natural area. The Status Assessment does require the evaluation of species that not only spread along these artificially disturbed zones but disperse over 10 yards into more intact natural areas, however. Furthermore, in a few cases, consideration for broad conservation objectives sometimes makes it advisable to designate certain anthropogenically disturbed areas as "natural" for the purposes of assessment. This is because anthropogenically disturbed areas can provide habitat for species of special concern (Threatened or Endangered species). Non-native species that have not been identified in this Assessment as invading natural areas because their spread is limited to anthropogenically disturbed areas may in fact be causing damaging impacts when Threatened or Endangered species are found and maintained in areas the non-natives have become established. In other words, species currently described by this Assessment as "Not considered a problem species at this time" could in fact be causing problems. Such cases should be referred to the Florida Endangered Plant Advisory Council (Secretary: Tyson Emery, FL Department of Agriculture and Consumer Services, Division of Plant Industry, Tel: (352) 372-3505 Ext. 162.) Objective The objective of the Status Assessment is to summarize relevant ecological, management and economic value information on species by latitudinal zones in Florida. This approach provides substantially more information than would be indicated by simple presence or absence of an "Invasive Species List." This information is summarized by four indices, Ecological Impacts, Potential for Expansion, Difficulty of Management and Economic Value. Wherever possible, predictive items have been avoided, and are directed to the Predictive Tool. Most questions have been reduced to simple, two-choice answers. The Status Assessment does not address economic impacts other than cost of control in natural areas and economic value (in this instance, economic value is described as value for forage, biomass, or remediation purposes only). Other economic data (lost revenue, management costs other than control in natural areas, etc.) should be included in any detailed risk-benefit analyses of the current, or future, infestations of a species. tConclusions by latitudinal zone, drawn from the combined scores of the four indices, result in


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 3 specific recommendations that can be made about the species by IFAS personnel. The conclusions include a period after which the species must be reassessed (either 2 or 10 years). However, any species may be reassessed whenever additional relevant information becomes available that might change the result of the Assessment. Thus, conclusions might change at any time. tThe Status Assessment is generally applied at the species level. It is only applied independently to infraspecific taxa (e.g., cultivars, varieties, or sub-species) if these taxa can be clearly distinguished in the field and are not likely to revert to traits of the parent plants (throughout the Status Assessment, reference to the species under consideration could also refer to such distinct infraspecific taxa). Other infraspecific taxa may be proposed for assessment using the Infraspecific Taxon Protocol http://plants.ifas.ufl.edu/assessment/ infraspecific_taxon_protocol.html. This protocol uses the same conclusions as the Status Assessment. Although they are derived differently, the conclusions for these infraspecific taxa are reported along with conclusions for all species evaluated using any component of the IFAS Assessment. Use of the Assessment within IFAS Species are assessed by trained personnel under the supervision of the IFAS Invasive Plants Working Group (IPWG). The results of each assessment are made available to all IFAS state and county Extension faculty (hereafter "IFAS faculty") through a website based at the Center for Aquatic and Invasive Plants http://plants.ifas.ufl.edu/assessment with links to IFAS Extension websites. IFAS faculty dealing with non-native plant species in Florida are expected to be familiar with this assessment. tThe Status Assessment places non-native plant species in categories (called "index categories"). These categories describe varying degrees of "Ecological Impacts," "Potential for Expansion," "Management Difficulty," and "Economic Value." Any IFAS Extension publications or newsletters, including those developed by county faculty, that refer to specific non-native plants in relation to the topics covered by this assessment (e.g., invasiveness, ecology, distribution, management, use, recommendations, and value) are required to include a reference to this assessment, and to use the terms and conclusions from the assessment when describing features of these plants. For example, "This species shows high ecological impacts such as causing long-term alterations in ecosystem processes," and, "This species is considered invasive and not recommended by IFAS faculty (IFAS Invasive Plant Working Group, 2008)." Additional information about how to cite the IFAS Assessment, its components, conclusions, and results can be found at: http://plants.ifas.ufl.edu/assessment/pdfs/ citations_examples.pdf tThe Status Assessment uses the index categories to define "conclusions" about the assessed species, including conclusions such as "Invasive and not recommended by IFAS faculty." Faculty making planting recommendations may choose to include "not recommended" plants in their publications if the conclusions from the assessment are clearly presented. In some situations, it is better public education to include a "not recommended" plant with the reasons it should be avoided than to leave the species out of the publication entirely. tt tThe Status Assessment will be revised periodically, and content and conclusions may change substantially. Every IFAS Extension publication must conform to the assessment protocol in place at the time of that publication's final drafting and must be made to conform to the current assessment protocol when it is revised. The IPWG will continue to review all Extension pre-publications related to invasive plants, and will determine if the direction and intent of these provisions are being followed. Further details concerning the use of the IFAS Assessment system by IFAS faculty are provided at: http://plants.ifas.ufl.edu/assessment/pdfs/ useassess.pdf Structure of the Status Assessment The Status Assessment is divided into five main sections, one for determining where the plant is invading and the others corresponding to four indices


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 4 of Ecological Impacts, Potential for Expansion, Difficulty of Management, and Economic Value. These sections are designated by Roman Numerals (I V). Assessment questions within these sections are located in shadowed boxes which have sub-section letters (I-a, I-b, etc.). Each separate question within a box has its own number which is in either Arabic numerals, for questions that influence the order of progression through the Status Assessment (e.g., I-a 1., I-a 2.), or diminutive Roman numerals, for statements to which scores are assigned (e.g., II-a i, II-a ii). Three further sections that directly lead to conclusions have letters A C and are found at the end of the Status Assessment. Certain species currently existing in Florida or not yet known here are prohibited by federal or state laws. IFAS faculty will not recommend such species and should note their prohibited status when discussing them. Relevant lists of such species can be found at: USDA / APHIS Federal noxious weed list http://www.aphis.usda.gov/plant_health/ plant_pest_info/weeds/downloads/weedlist2006.pdf Dept. Agric. and Consumer Services Noxious weed list https://www.flrules.org/gateway/ readFile.asp?sid=0&tid=3023798&type=1&File=5B57.007.htm Florida Fish and Wildlife Conservation CommissionProhibited plant list http://www.myfwc.com/WILDLIFEHABITATS/ InvasivePlants_AquaticPlantPermitRules.htm#62C52.011%20Prohibited%20Aquatic%20Plants. Section I Invasion Status The purpose of this section is to separate species that do not appear to invade natural habitats from those that do. For this assessment, a species is defined as invading if it forms self-sustaining and expanding populations within a natural plant community with which it had not previously been associated (cf. "invasive" in Vitousek et al. 1995). This definition does not specify that the species must cause some defined impact (as is required by some definitions) because this will be addressed separately. I-b Invasion Status in Three Zones of Florida Some species may be invading all parts of the state, while others can invade one zone (e.g., sub-tropical south Florida) but may not be able to invade or survive in other zones. A few species may be found currently in only one zone but have the potential to continue to spread to others. Having determined the invasion status of the species on a state-wide basis in Section I-a, determine indices for Ecological Impacts (Section II) and Potential for Expansion (Section III) separately for each of three latitudinal zones so that conclusions can be proposed that account for varying latitudinal and environmental patterns of invasion. In zones where a species is not currently invading, only Potential for Expansion will be evaluated (Section III).


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 5 The state of Florida has been divided into three phytogeographic regions based on an estimated chill accumulation chart. We have modified that map to separate zones at the northern borders of counties that lie along the 420 chill unit accumulation (north) and and the southern borders of counties along the 110 chill unit accumulation (south). These zones are similar to those defined by USDA Hardiness Zones 8, 9 and 10/11 (http://www.usna.usda.gov/Hardzone/index.html). While no areas of Florida are wholly undisturbed by human activity (e.g., air pollution, trails, fragmentation), this assessment is confined to species that invade natural areas in which that anthropogenic disturbance is minimal, or species that may persist in natural communities once anthropogenic disturbances have been largely removed. Natural systems are dynamic because of a number of natural disturbances on various scales (e.g., gopher mounds, treefalls, fire, tides, flooding, hurricanes, etc.). Altering the frequency and scales of those natural disturbances may allow establishment of new species; it presents as much of a perturbation to the system as does introducing a completely new anthropogenic disturbance (e.g., trampling, grazing animals, soil movement, drainage, pollution, etc.). If a species invades only when disturbance regimes other than those under which the community evolved occur, and if that species is not known to persist when the natural regime is reestablished, the species will not have critical impacts in natural areas being managed to restore or maintain natural processes. For example, skunk vine (Paederia foetida) can invade sandhills that have been fire suppressed, but it is quickly killed and is maintained at low levels when fire is restored to that system. (Note: skunk vine can also invade undisturbed areas and non fire-adapted habitats, so it would still be categorized as invading in Section I-b.) A species that can establish and persist when natural disturbance regimes exist may pose a serious threat to natural systems. Non-native species that do not require an anthropogenic or other novel disturbance for establishment are pre-adapted to Florida's natural systems and may out-compete native species also adapted to those systems. Section II Ecological Impacts of Invasion The purpose of this section is to evaluate the severity of ecological impacts caused by an invasion. This evaluation is made without regard to the actual size or age of an invasion and is independent of any assessment of value or cost of the species. Because we are defining invasion without a requirement for impact (see Section I), it is possible in this assessment for a species to have been identified as


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 6 invading natural habitats but to score low or zero on the Ecological Impact scale (e.g. remains at a low density in an existing stratum of vegetation). Other species may show multiple impacts, which will result in a high score. In the first part of this section, the worst known impacts of a species are assessed regardless of whether these worst impacts are widespread. II-b Range of Communities in Which Species is Invading Species that are capable of invading a wide range of communities are likely to have wide environmental tolerances and broader impacts than those species that are limited to a narrow range of communities. The following lists of community groups have been adapted from the Natural Community Groups defined by the Florida Natural Areas Inventory (FNAI and FDNR 1990). These groups are described at: http://www.fnai.org/PDF/ Natural_Communities_Guide.pdf Terrestrial List Xeric uplandstSandhill, scrub, xeric hammocktttt Coastal uplandstBeach dune, coastal berm, coastal grassland, coastal rock barren coastal strand, maritime hammock, shell moundtttt Mesic uplandstBluff, slope forest, upland glade, upland hardwood forest, upland mixed forest, upland pine forest RocklandstPine rockland, rockland hammock, sinkhole Mesic flatlandstDry prairie, mesic flatwoods, prairie hammock, scrubby flatwoods Palustrine (wetland) / Aquatic List Wet flatlandstHydric hammock, marl prairie, wet flatwoods, wet prairie Seepage wetlands Bay gall, seepage slope Floodplain wetlands Bottomland forest, floodplain floodplain forest, floodplain marsh, floodplain swamp, freshwater tidal swamp, slough, strand swamp, swale Basin wetlandstBasin marsh, basin swamp, bog, coastal interdunal swale, depression marsh, dome swamp Lakes and riverstAll types of freshwater lakes, rivers and streams Tidal wetlandstMarine and estuarine tidal marshes and swamps


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 7 II-c Proportion of Invaded Sites with Significant Impacts This section is intended to separate those species that do not cause serious impacts everywhere they occur but only in very specific regions or environments. Such species may be acceptable for use in areas that are sufficiently distant from the specific communities they impact (Section B, page 23). It is important to estimate the proportion of sites where worst-case impacts have been recorded, relative to all sites within the zone where the plant has been invading. Section III Potential for Expansion. The purpose of this section is to provide a crude evaluation of whether there is high or low potential for this species to expand much further within Florida. This assessment is made independently for zones where the plant has invaded, and zones where it has not invaded. The assessment is made without regard to absolute areas of invasion or potential habitats. A high potential for expansion is indicated if there is a significant rate of spread of the species. This section is important for species that may have only recently invaded and for which little evidence of impacts may be available. It is also important for assessing the species' potential for expansion and causing impacts in zones which it is not currently invading. Question III-a ONLY for Zones Where Plant Has Invaded. III-a Known Rate of Invasion. Doubling times and absolute areas can be difficult to quantify, so this section uses the concept of "discrete populations" to indicate the rate of habitat invasion. Discrete populations (populations separated by at least 1 mile see glossary) are intended to be units that are easy to quantify and that probably indicate invading plant populations that arose by long-distance dispersal mechanisms. The rate at which new populations for a species are reported may be as much influenced by increased search effort as by actual expansion of plant coverage. However, this parameter is included because such change in reporting is typical of recently identified species, which are also most likely to have the greatest potential to expand beyond their current distribution. Question III-b ONLY for Zones Where Plant Has NOT Invaded. III-b Potential for Invading Non-invaded Zones If a species is capable of surviving, reproducing, and dispersing in a zone, then it is likely that its current absence from that zone is a function of its rate of expansion from the place where it was introduced to the state. Its potential for expansion if it reaches a suitable new zone is likely to be high if its potential in currently invaded zones is high. Question III-c ONLY for Zones Where Plant Has NOT Invaded but Has the Potential To Invade. III-c Potential for Causing Ecological Impacts in Non-invaded Zones The purpose of this section is to identify the likelihood of future ecological impacts in a zone that


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 8 has not yet been invaded but that has the potential to be. If there is no reason to believe that the ecological impacts observed elsewhere in the state could not occur in this zone, then it is reasonable to adjust the ecological impact score to match that of an adjacent invaded zone, which will lead to similar conclusions for the two zones. Section IV Difficulty of Management Management Index It seems unlikely that management difficulty will vary significantly by zones so this section is assessed on the state-wide distribution of the species, not by zones. The intention of this section is to distinguish species for which management is especially difficult. For most statements, no particular methods of control are specified but responses should relate to the methods that are most likely to be used. Most of these statements relate to the availability of control methods, factors that influence the cost of control (over multiple generations, if relevant), or factors that indicate the increasing likelihood of unavoidable non-target damage. Management of species that become reproductive in a short period of time, or that produce many, long-lived and/or widely dispersed reproductive propagules, is more difficult because they will require more frequent, longer-lasting, and/or more widely ranging re-surveys and re-treatments. tBiological control can greatly reduce management costs, and several effective programs for biological control of non-native plants have been implemented in Florida. Because target plant species for biological control programs have, to date, been on Florida's Prohibited Aquatic Plants List (maintained by Florida Department of Environmental Protection) or Noxious Weeds List (maintained by Florida Department of Agriculture and Consumer Services), and because listed prohibited plants are automatically exempted from the assessment (page 6), neither the use nor the results of biological control are specifically addressed in this section. Note: This section is assessed on the state-wide distribution of the species, NOT by zones. Section V Economic Value Value Index The intention of this section is not to identify attributes that must apply to every high-value species but to find parameters that indicate the species is of some significant value. Few data are available at the species level on plant production and sales in Florida so it is difficult to develop simple questions for which appropriate information can be found. Sales from chain retail stores may only relate to a few growers but it is likely that these will be high-income species because the chain stores will only select species that they are confident will be popular and sell quickly (especially department and grocery stores). Note: this section is assessed on the state-wide distribution of the species, NOT by zones. Conversion of Index Scores to Index Categories The actual scores for each index will be important if species are to be compared with each other or over time. For the purposes of reporting the status of a species for each index and for determining the appropriate conclusion, the index scores are converted to index categories. For Potential for Expansion, Management Difficulty, and Economic


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 9 Value there are only two categories (Low or High). For Ecological Impacts there are four categories (Low, Medium, High and Very High). The criteria for the Impact score cut-offs for each category are based on the combinations of statements that are scored in Section II-a on pages 10 11. Low impacts include only one mid-scoring statement (8 points) or one to three low-scoring statements (1 or 4 points), usually without a wide habitat range. Medium impacts have at least one high-scoring statement (12 or 15 points), a midand low-scoring statement, multiple low-scoring statements, or a wide habitat range. Most High impacts include an ecosystem effect and/or wide habitat range, plus at least one of the other high-scoring statements or several other low-scoring statements. Very High impacts must show ecosystem effects and either all other impacts or a wide habitat range, or must have all impacts other than ecosystem and must have a wide habitat range. NOTE: The following conclusions would be subject to any local laws, rules, or ordinances that prohibit the sale, transportation, or use of particular species. This may apply to species that are highly problematic in some zone(s), but that have caused minimal impact and have low potential for spread into another zone. Conclusions For Zones where conclusions were NOT already developed in Section D Conclusions are derived separately for each zone from the combined index categories using the table on page 21. Whenever new information becomes available about the invasive status of a species (e.g., new populations, new data on ecological impacts) that species should be reviewed and if necessary reassessed. The following text corresponds to the abbreviations in the table on page 21 (text in bold is


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 10 approved language for IFAS documents, text in parentheses provides additional instructions to IFAS faculty and for reassessment): OK = t Not considered a problem species at this time (may be recommended by IFAS faculty and reassess in 10 years). Caution = t Caution manage to prevent escape (may be recommended by IFAS faculty and reassess in 2 years). No unless specified use approved = In the zones to which this conclusion applies, a species may be eligible for a proposal for specified and limited use, as detailed in Section D. If a proposal for specified and limited use has not been approved by the IFAS Invasive Plants Working Group (IPWG) the conclusion is: Invasive and not recommended by IFAS faculty (reassess in 10 yearsa proposal for specified and limited use may be submitted to the IPWG at any time). In IFAS publications, reference can be made to the website http://plants.ifas.ufl.edu/assessment to determine if any specified and limited uses have been approved since the time of publication. If a proposal for specified and limited use has been approved by the IPWG the conclusion is:tt Invasive and not recommended by IFAS faculty except for the "specified and limited" use that has been approved by the IFAS Invasive Plants Working Group (reassess in 10 years or 2 years if specified use) OR Predicted to be invasive*: Recommended only under specific management practices agreed upon by the IFAS Invasive Plant Working Group (reassess in 2 years). In IFAS publications the term "specified and limited" would be replaced by a summary of the specific use that has been approved (e.g., indoor foliage). Details of approved specified and limited uses are to be kept with other assessment documentation. No = Invasive and not recommended by IFAS faculty (reassess in 10 years). *Reported invasiveness in environments similar to but outside of Florida is one basis for this conclusion Section A (from Section I-a page 7 or Section I-b page 9) The purpose of this section is to identify species that pose a threat of genetic invasion of Federalor Florida-listed plants or economically important species, and to identify for further assessment species that have either been introduced recently or that may have the potential to cause problems based on experiences in similar regions of the world. Plants that do not fall into any of these categories are not


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 11 considered invasive at this time but should be reassessed every 10 years or if invasion into natural areas is recorded. Section B (from Section II-c page 12) The purpose of this section is to determine whether the locations in which impacts of the invading species are high can be clearly defined. If impacts are restricted to an identifiable habitat or community, the species may not be recommended for use near those areas. Dispersal characteristics are evaluated to determine how far away a no-plant zone would have to extend to reasonably ensure that propagules would not reach a site that is susceptible to damaging invasion. Section C (from Footnote 2 on page 21) For a zone that is invaded and has Impact = Low but where the adjacent zone has Impact = High or Very High, this section addresses the concern that some of these species have just arrived in a zone and so have not yet become severe enough to be causing ecological impacts in that zone. If the same species had NOT yet been detected in this zone, but were considered likely to survive and cause impacts there, the conclusion would match that for the nearest invaded zone (via Section III-c). For example, in 2001, Paederia foetida in the south zone fit this category as a single, new population was first recorded in 2000. All else being equal, then, in zones next to highly impacted areas, invasive species that are near the zone but not yet in it give that zone a higher impact rating than invasive species that have actually arrived in the zone, albeit very recently. This not only seems inconsistent but risks underestimating the threat posed by a species at the earliest stage of invasion, when the most effective control action might be taken. On the other hand, if a species has been known in a zone for a long time but it still causes minimal ecological impacts (e.g., Lantana camara in the north zone) a Cautionmanage to prevent escape OR Not considered a problem species at this time conclusion would be appropriate. Section D (from Section A1, Section B, or Footnote 1 on page 21) This section provides the possibility of a specified exemption to certain Invasive and not recommended by IFAS faculty conclusions (listed above), based on a reasonable certainty that plants grown in the specified conditions will not be able to escape into natural habitats or into the well-defined habitats in which limited impacts occur. Anyone using this assessment tool should recognize that the proposed conclusions have been developed under the assumption that growers, retailers, and consumers will follow any use specifications made.


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 12 Glossary for this Assessment Anthropogenic disturbance. Recurring anthropogenic source of soil exposure (e.g., roads, trails, plow lines) and/or vegetation structure change (e.g., mowing) that is not the result of a natural process or that does not mimic a natural process and that causes partial or total destruction of vegetative biomass. Also includes human-induced changes in natural disturbance regime (e.g., changing the severity of fires; fire suppression in fire-adapted communities or fire in communities not adapted to fire; or grazing cattle above the density of native herbivores). In this context, disturbance is likely to facilitate the invasion of rapidly colonizing and persistent species. Coverage. Visual or quantitative estimate of the relative amount of area in a stratum in which the canopy of the non-native species intercepts light that would otherwise be available for other species in or below that stratum. Estimated cover may be dispersed or continuous in a site. Cover is usually measured when foliage is fully expanded. In the case of species that form a dense, continuous mat of rhizomes or stolons, the percent of the soil surface or upper level occupied by that root mat can be estimated as soil, rather than canopy, cover. Disturbance. Natural mechanisms that limit biomass by causing its partial or total destruction (e.g., fires caused by lightning; herbivory; flooding; hurricanes). Discrete populations. A population is a group of individuals of the same species living in the same place that are much more likely to reproduce with one another than with individuals from another population. For the purposes of this assessment, discrete populations must be at least 1 mile apart. They likely arose by separate, long-distance dispersal events. Distributional evidence. Search floras, databases, herbaria, etc. (for examples see "Floras, etc." in Other Resources on page 28). For each relevant record, document: the source (e.g., database, herbarium); the date; the site; the collector; and any other relevant information. If formal documentation is not available, obtain such information (confirmed in writing) from at least two people who have the expertise to identify the particular species. Documentation of evidence. One publication including relevant, original research will suffice if data are specific to the taxon and zone(s) under evaluation. If such documentation is not available or needs to be updated, at least three individuals who have expertise on the particular species and zone in question must be identified. If more than three experts have been identified, use the responses that are most precautionary (i.e., worst assessment of impacts or greatest management needs reported), as consistent with the intent of the assessment. Relevant information (confirmed in writing) must be provided by at least two of the three experts to justify a "yes" response to a question, or to support a score-accruing statement. For example, in Sections II-a and IV, scores are summed for all statements that have each been confirmed either in the literature or by at least two experts. In statement II-a i), if two experts indicate that there have been ecosystem changes, 15


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 13 points are assigned for this item even if the experts are reporting different types of ecosystem changes. If data in the literature show that a species causes a particular ecological impact but not in the zone under consideration, expert opinion is still needed. However, an expert could give the opinion that this impact is also likely to occur in the zone, and that could be one of the three expert opinions needed. Records should be kept of all the experts who were contacted for each species and zone, regardless of whether they provided input. Federalor Florida -listed. Species that are listed by Federal laws or Florida statutes or rules as Threatened, Endangered or Species of Special Concern within the state of Florida. The list of endangered and threatened species of plants is available at: http://www.doacs.state.fl.us/pi/enpp/botany/images/ Notes2003.pdf Also species and habitats of special concern that are regulated by Florida Statute include: mangroves (FL statute 403.9321), sea oats and sea grape (FL statute 370.041), cypress trees (FL statute 590.02). Other types of imperiled species are listed at: http://www.myfwc.com/WILDLIFEHABITATS/ imperiledSpp_index.htm Invading. A species that forms self-sustaining and expanding populations within a natural plant community with which it had not previously been associated (cf. "invasive" in Vitousek et al. 1995). Invasive. Invading species that cause documented ecological impacts higher than Low (pages 19 21). Long-term alterations in ecosystem processes. Examples of ecosystem processes that could be altered: erosion and sedimentation rates; land elevation; water channels; water-holding capacity; water-table depth; surface flow patterns; rates of nutrient mineralization or immobilization; soil or water chemistry; and type, frequency, intensity, or duration of disturbance. For further explanation see Gordon (1998). Native. Species within its natural range or natural zone of dispersal (i.e., within the range it could have, or would have, occupied without direct or indirect introduction and/or care by humans. Excludes species descended from domesticated ancestors) (Vitousek et al. 1995). Natural areas. Areas of Florida (public or private) with designated management objectives that include the conservation of native biodiversity. While a range of activities may be conducted on these areas (e.g., prescribed fire, low intensity grazing), those activities are designed to be compatible with the conservation objective. State and local governments and some private landowners, for example, manage natural areas both for economic value (recreation, grazing, forestry or other harvest values) and for conservation values. These areas with multiple uses would be designated as natural areas in the Status Assessment, with clearly identifiable "non-natural" edges disregarded. Species that invade only the identified edgesareas next to to roads, trails, fire lanes, recent dredge spoil, formerly cultivated areas, expanses of bare soil, etc.will not be identified as invaders with impacts in natural areas because their persistence and spread is only in these clearly anthropogenically disturbed zones in the natural area. The Status Assessment does require the evaluation of populations of species that not only spread along these disturbed zones but disperse over 10 yards into more intact natural areas: these would be included as invading. Ecological impacts would be assessed only where the population has spread into the intact natural areas and not within the source population in the disturbed or formerly cultivated area. Pollen or genetic invasion. When a native species is displaced by a non-native species through hybridization. Sites. Locations that can be distinctly described by name (e.g., named State Park or lake) and may be subdivided into distinct habitats and/or communities (e.g., mesic uplands in Acme Park and rocklands in Acme Park). A site may contain more than one discrete population of a species provided that the populations are at least 1 mile apart. Stratum. A distinct layer in the architecture of vegetation (e.g., tree canopy, understory shrubs).


IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment 14 References Gordon, D.R. 1998. Effects of invasive, non-indigenous plant species on ecosystem processes: lessons from Florida. Ecological Applications 8: 975. Gordon, D.R., D.A. Onderdonk, A.M. Fox, R.K. Stocker, and C. Gantz. 2008. Predicting Invasive Plants in Florida Using the Australian Weed Risk Assessment. Invasive Plant Science and Management 1: 178 Lockwood, J.L., P. Cassey, and T. Blackburn (2005) The role of propagule pressure in explaining species invasions. Trends Ecol Evol 20: 223. Mack, R.N. (2008) Evaluating the credits and debits of a proposed biofuel species: giant reed (Arundo donax). Weed Sci 56: In press Pheloung, P.C, P.A. Williams, and S.R. Halloy. 1999. A weed risk assessment model for use as a biosecurity tool evaluating plant introductions. Journal of Environmental 57: 239. Reaser, J.K., L.A. Meyerson, and B. von Holle (2008) Saving camels from straws: how propagule pressure-based prevention policies can reduce the risk of biological invasion. Biol Invasions 10: 1085. Vitousek, P., L. Loope, C. D'Antonio and S.J. Hassol. 1995. Biological invasions as global change. pp. 213 In: S.J. Hassol and J. Katzenberger (eds) Elements of change 1994. Aspen Global Change Institute, Aspen, CO.t Other Resources Floras, databases, herbaria, etc. APIRS Online Bibliographic database of aquatic, wetland & invasive plants http://plants.ifas.ufl.edu/ t Search FL Department of Environmental Protection / FLEPPC Exotic plant database http://www.eddmaps.org/florida/ Atlas of Florida Vascular Plants Institute for Systematic Botany, University of South Florida. http://www.plantatlas.usf.edu/ use scientific name search. Virtual herbarium Fairchild Tropical Gardens http://www.virtualherbarium.org/ (Information and instructions for using search engine). To search FTG herbarium directly http://www.virtualherbarium.org/vh/db/main.htm Floristic Inventory of South Florida Institute for Regional Conservation http://www.regionalconservation.org Information may also be obtained by visiting the University of Florida (FLAS) Herbarium Details regarding herbarium visits may be obtained at: http://www.flmnh.ufl.edu/herbarium/flasvasc.htm Some FLAS herbarium records are available on-line and can be linked through the homepage. Plant locators Florida Nursery, Growers and Landscape Association http://www.fngla.org/ Search for wholesale commercial availability of a species at: http://dev.fngla.org/search/searching/index.asp Tampa Bay Wholesale Growers Association Search for wholesale commercial availability of a species (86 nurseries) at: http://www.tbwg.org/PAL.htm PLANTFINDER Betrock's Hortworld website Search for wholesale commercial availability of a species in Florida at: http://www.plantfinder.com/availability/ plantavailability1.asp