• Topics: Agronomy  |  Fox, Alison Mary  |  Dusky, Joan A  |  Stocker, Randall K  |  Natural Area Weeds  |  Langeland, Kenneth 

IFAS Assessment of Non-native Plants in Florida's Natural Areas: Status Assessment¹

This publication is available in its entirety in PDF format only.

Click here to print or view the entire publication. Current results of the IFAS Assessment and a summary of its conclusions are available on the Center for Aquatic and Invasive Plants Web site at: (http://plants.ifas.ufl.edu/assessment).

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 assessment is intended to be useful in developing priorities for research and management efforts, and it can be adapted for use in other states.

The IFAS Assessment has three components: the status assessment (this document), the predictive tool, and the infraspecific taxon protocol. All three components and a more detailed description of how the IFAS Assessment was developed are available at: http://plants.ifas.ufl.edu/assessment/.

The status assessment is intended only 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. Species present in the state but not invasive in Florida''s natural areas, which are either recent arrivals to Florida or are known to cause problems in areas with similar habitats and climate to Florida, are directed by the status assessment to the predictive tool. The Australian Weed Risk Assessment system (Pheloung et al., 1999) has been adapted for use in Florida (Gordon et al., 2008) as the predictive tool for the IFAS Assessment complete the assessment of such species (http://plants.ifas.ufl.edu/assessment/pdfs/predictive_tool.pdf).

In all likelihood, fewer than 1% of all non-native plant species in the state will be identified as having ecological impacts in natural areas (for definitions of terms as used in this document see Glossary, pages 4-5). The status assessment is designed to identify non-native species that are invasive in areas of Florida with designated management objectives that include the conservation of native biodiversity. While a range of activities may be conducted in these areas, those activities are designed to be compatible with the conservation objective. State and local governments and some private landowners, for example, manage natural areas for recreation, grazing, forestry or other harvest values as well as for conservation values. These areas would be included in the assessment of invasion, with clearly identifiable edges disregarded. Species that invade only adjacent to roads, trails, fire lanes, recent dredge spoil, expanses of bare soil, etc. should not be identified as invaders with impacts in natural areas because their persistence and spread is only in these anthropogenically disturbed zones in the natural area. Species that spread along these artificially disturbed zones but disperse over 10 yards into more intact natural areas would need to be evaluated by this assessment.

Some anthropogenically disturbed areas can provide habitat for species of special concern. . Thus, in considering broad conservation objectives, it may still be necessary to review non-native species that have not been identified in this Assessment as invading natural areas. For example, where threatened or Endangered species are now predominantly found and eaintained in anthropogenically disturbed areas, it is possible that these could be impacted by non-native species that are described by this assessment as "Not considered a problem species at this time". Such cases should be referred to the Florida Endangered Plant Advisory Council (Secretary: Danny Phelps, FL Department of Agriculture and Consumer Services, Division of Plant Industry, Tel: 352-372-3505).

Implementation of the Status Assessment

Relevant ecological, management and economic value information on species are summarized within the status assessment by latitudinal zone in Florida. This approach provides substantially more information than would be indicated by simple presence or absence on an invasive species list. The information is summarized by four indices: Ecological Impacts, Potential for Expansion, Difficulty of Management, and Economic Value. Whenever possible, predictive questions have been avoided, and are relegated to the predictive tool. Most questions have been reduced to simple two-choice answers. The status assessment does not address economic impacts other than management costs and economic value. Such 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.

Conclusions by latitudinal zone, drawn from the four combined scores of the four indices, result in specific recommendations that can be made about the species by IFAS personnel. The conclusions include a period after which the species must be assessed (either 2 or 10 years). However, any species may be reassessed whenever additional relevant information is obtained that change the results of the assessment. Thus, conclusions might change at any time. The 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 (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; though they are derived differently, the conclusions for these infraspecific taxa are reported with those for all species evaluated using any component of the IFAS Assessment.

Use of the Assessment within IFAS

Species will be assessed by trained personnel under the supervision of the IFAS Invasive Plants Working Group. The results of each assessment will be 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.

The status assessment will place non-native plant species in categories (called Index Categories) which describe varying degrees of "Ecological Impacts", "Potential for Expansion", "Management Difficulty", and "Economic Value". Any IFAS Extension publications or newsletters 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) must include a reference to this assessment if the species has a "caution" or "not recommended" conclusion., and use the terms and conclusions from the assessment when describing the characteristics of these plants. For example, "...shows high ecological impacts such as causing long-term alterations in ecosystem processes" or "...this species is considered invasive and not recommended by IFAS faculty (IFAS Invasive Plant Working Group, 2008. Additional guidelines about how to cite information from the IFAS Assessment (specific language to address the conclusions within printed materials) is provided at http://plants.ifas.ufl.edu/assessment/pdfs/citations_examples.pdf).

The status assessment uses the index categories to define the conclusions of the assessed species, including "Invasive and not recommended by IFAS faculty". Faculty making planting recommendations may choose to include plants that are not recommended by IFAS in their publications if the conclusions from the assessment are clearly presented. In some situations, it may provide better public education to include a plant that isn't recommended with the reasons it should be avoided, instead of leaving the species out of the publication entirely.

The status assessment will be revised periodically and content and conclusions may change substantially as more is learned about the species. IFAS Extension publications 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 that publication is revised. The IFAS Invasive Plants Working Group 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 assessment is divided into five main sections, one for determining where the plant is invading and the others corresponding to four indices 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.). Separate questions within a box have their own number which is in either Arabic numerals, for questions that influence the order of progression through the 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 assessment.

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Species that are listed as prohibited species by federal and/or state laws will not be recommended by IFAS faculty. If such species are discussed, their prohibited status should be stated. 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

• Florida Department of Agricultural and Consumer Services - Noxious weed list:

• • http://www.doacs.state.fl.us/pi/enpp/botany/images/noxiousweedtable1.pdf

• Florida Department of Environmental Protection - Prohibited plant list:

• http://www.dep.state.fl. us/lands/invaspec/2ndlevpgs/perrules.htm#62C-52.011%20Prohibited%20Aquatic%20Plants

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 or 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, 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 where the canopy of the non-native species intercepts the 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 and which 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 pg. 6). . 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 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.

Federal- or 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://myfwc.com/imperiledspecies/.

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.

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 recreation, grazing, forestry or other harvest values and for conservation values. These areas would be included in the assessment of invasion, with clearly identifiable edges disregarded. Species that invade only adjacent to roads, trails, fire lanes, recent dredge spoil, formerly cultivated areas, expanses of bare soil, etc. should 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. Populations of species that spread along these disturbed zones but disperse over 10 yards into more intact natural areas 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, under-story shrubs).

References

Gordon, D.R. 1998. Effects of invasive, non-indigenous plant species on ecosystem processes: lessons from Florida. Ecological Applications 8: 975-989.

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: 178-195.

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: 239-251.

Vitousek, P., L. Loope, C. D''Antonio and S.J. Hassol. 1995. Biological invasions as global change. pp. 213-336 In: S.J. Hassol and J. Katzenberger (eds) Elements of change 1994. Aspen Global Change Institute, Aspen, CO.

Other Resources

Floras, databases, herbaria, etc.

• Search FL Department of Environmental Protection / FLEPPC Exotic plant database -

• • http://www.fleppc.org/EDDMaps/

• 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 Botanic Garden

• • http://www.virtualherbarium.org (Information and instructions for using search engine). To search Fairchild 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/natsci/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://www.fngla.org/locator/searchPlants.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 Web site

• • Search for wholesale commercial availability of a species in Florida at: http://www.plantfinder.com/availability/plantavailability1.asp

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. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

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. Larry Arrington, Dean.

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