Ecologic and precursor success criteria for south Florida ecosystem restoration

A Science Sub-Group Report to the Working Group of the South Florida Ecosystem Restoration Task Force

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CHAPTER 7: LANDSCAPE ECOLOGICAL INDICES

IntroductionVegetation Change Index
Nutrient Tolerant Vegetation IndexExotic Species Change Index
Spatial Extent IndexNatural Area and Buffer Area Change Index
Corridor IndexReferences

I. INTRODUCTION

A. Team:

Tom Armentano, Tom Bancroft, Sarah Bellmund, Laura Brandt, Joan Browder, Paul Carlson, Dan Childers, Doug DeVries, Amy Fereter, Ron Hofstetter, Su Jewell, David Jones, Wiley Kitchens, Francois LaRoche, Frank Mazzotti, Christopher McVoy, Leonard Pearlstine, Dianne Petitjean, Bill Robertson, Mike Ross, Ken Rutchy, John Stenberg, Tom Smith, Jim Snyder, Dan Thayer, Joel VanArman, Mike Zimmerman. Authors: Sarah Bellmund, Wiley Kitchens

B. General Background

The intent of landscape analysis is to examine the loss of habitat, shifts in habitat patterns, and shifts in composition of habitat in a quantifiable manner in conjunction with the restoration of south Florida. To develop a quantitative approach to restoration efforts, the Science Subgroup originally identified two types of indices that could be used to measure system condition and response. Precursor success indices (PSI) measure forcing factors in the system that form a basis for ecological restoration. Ecological success indicators (ESI) provide measures of the end-point success of ecological restoration of the system.

The Landscape ecological index is comprised of the precursor success index (PSI) of Spatial Extent and the Ecological Success Index (ESI) of Landscape Pattern. These indices were created by combining several old categories from earlier Science Sub-Group documents. The Landscape pattern index includes a vegetation change index, a nutrient tolerant vegetation change index, and an exotic species change index. The Spatial Extent index is comprised of a buffer index and a corridor and connectivity index.

Taken together these composite indices define an overall landscape ecological approach to quantifying existing conditions and evaluating changes that occur within the region affected by the Central and South Florida Project (C&SF) as it returns to healthy vegetative landscapes. A geographical information systems (GIS) approach is ideally suited for the requisite analyses to generate these indices, given the complexity of the system and the areal extent of land under evaluation. The intent of the landscape ecological criteria and its indices is to define the current system, quantify the changes presently occurring in the system, and quantify the changes in the system as it returns to healthy vegetative landscapes. The indices are designed to principally use ongoing programs, existing projects, and modeling efforts. They are designed to evaluate data generated by existing programs and identify information that is needed to understand the system.

The landscape criteria are based upon a description of patterns and the subsequent change in patterns throughout the South Florida system as measured at various scales. The intent of this process, as comprised by the landscape success criteria, is to examine the loss of habitat as well as shifts in pattern and composition of habitat in a quantifiable manner in conjunction with the restoration of the study area (Figure 1).

C. Definitions

The application of landscape ecological principles to this evaluation requires the definition of terms to provide a common language and reduce semantic confusion. The definition of many of these terms depends on the scale at which they are applied.

1. Scale Definitions

Scale is defined based on a description of patterns and the subsequent change in patterns throughout the south Florida system. Although, the global scale will not be used directly, it is included for context and completeness of the definition of scales relative to each other in the larger context. The appropriate scales for the south Florida restorations effort are macro, meso, micro, and nano, which are defined as follows:

Global Scale: The global scale is used to represent how the distribution of dominant ecosystems south Florida ecosystems (e.g. freshwater wetlands, mangroves, coral reefs, subtropical forests, etc.) relate to their counterparts in other parts of the world. This scale can be assessed using satellite imagery and broad scale mapping techniques. These major ecological systems that have a spatial extent represented by hundreds to thousands of kilometers.
Macro Scale: Macro scale features are represented in south Florida by large landscape phenomena and are composed of perhaps 20-25 categories of cover classes that can readily be discerned. This scale can be assessed using high resolution satellite imagery. These are principally watershed units and major physiographic features that have a spatial extent of 1 km-100 km.
Meso Scale: This scale represents features that are smaller and more regional; that can be assessed by a combination of high resolution, low altitude imagery in conjunction with field sampling; and that may be represented by 80 to >100 categories. These features are principally composed of a mixture of landscape elements within a particular landscape. Each element may have a spatial extent of 10 - 1000 m.
Micro Scale: This scale is representative of sub-regional features that are best assessed by field sampling on the plot size level and reviewed in conjunction with broader scale (meso or macro) phenomena. Typically this scale represents plots within a single landscape element that have a spatial extent of 1 -10 m.
Nano Scale: The nano-scale represents organisms and processes taking place in the finest reasonable resolution. This scale would include individual microbial processes and microflora/microfauna changes with a spatial extent of 0.1 -1.0 m. Conditions at this scale can be assess by field sampling in conjunction with laboratory analyses.

Most of the success criteria will be assessed at the macro and meso scales. The micro and nano scales may be used in individual situations as informational needs of the system become more clearly defined. These finer scales may be more appropriate for answering detailed questions, particularly about the relationship between scales and to define connections between components of the landscapes.

2. Concept Definitions

Region is an "area, usually containing a number of landscapes that is determined by a complex of climatic, physiographic, biological, economic, social and cultural characteristics" (Forman and Godron, 1986).

Landscape is defined as "a heterogeneous land area composed of a cluster of interacting ecosystems [or elements] that are repeated in similar form throughout." and down in size to a few kilometers in area (modified from Forman and Godron, 1986). Organism perspective defines landscape size depending on what constitutes habitat mosaics or resource patches meaningful to that organism and is described based upon the chosen scale of investigation (McGarigal and Marks, 1994).

Landscape element is a unit of organization, which is the basic relatively homogeneous ecological unit found within the boundaries of the landscape (this can be of natural or anthropogenic origin). (Forman and Godron, 1986)

Mosaic is comprised of patches within a matrix and are patches comprised of similar aggregated objects or a pattern of patches and corridors within a matrix (Forman, 1996).

Matrix is the most extensive and connected landscape element type present and plays the dominant role in landscape functioning (also a landscape element surrounding a patch) (Forman and Godron, 1986). The matrix element type is defined as that which is the most extensive and connected and thus the greatest in areal extent (McGarigal and Marks, 1994). The background land-use type in a mosaic, which is characterized by high connectivity and is the extensive cover (Forman, 1996).

Patch is a "non-linear surface area differing in appearance from its surroundings" (Forman and Godron, 1986), typically as an aggregate within a matrix.

Configuration is defined as "the location and juxtaposition of the landscape elements" (Forman and Godron, 1986). This refers to "the physical distribution or spatial character of patches within the landscape" (McGarigal and Marks, 1994).

Composition is the features associated with the presence and amount of each patch type within the landscape, the variety and abundance of patch types within a landscape but not their placement or location (McGarigal and Marks, 1994).

Grain is defined as the smallest scale at which an organism perceives and responds to a patch structure, the size of individual units of operation (McGarigal and Marks, 1994).

Spatial Element is represented by "each of the relatively homogeneous units recognized in a mosaic at any scale" (Forman, 1996).

II. GENERAL RATIONALE

Landscape-level habitat loss and fragmentation have degraded the south Florida ecosystem since the 1880's (Beard, 1938; Loveless, 1959). As part of this degradation,the major canals were in place by 1930 and the majority of all currently existing canals were constructed by 1965 (SFWMD, 1992). Severe fires in the 1940's and 1950's caused extensive damage throughout the system, reflecting the efficiency of drainage canals on the Everglades (Loveless, 1959). The vegetative landscape, which is crucial to the support of the native fauna, has declined dramatically as a result of drainage related impacts throughout the twentieth century. Currently, habitat loss has been accelerated by development, agricultural runoff, and further over drainage.

Landscape mosaics resulting from patterns of occurrence of Everglades plant communities provide the habitat for native south Florida fauna. As the loss of habitat has continued, the number of threatened and endangered species has risen within the historic Everglades system. There has also been a general decrease in fauna and flora that can be attributed to a change in function of the system, loss of habitat, hydrologic shifts, and impacts due to the proximity of urban and agricultural development. The landscape ecological indices have been created as a means to evaluate the vegetation changes in the system and proposed reappearance of habitats resulting from the Central and South Florida restoration effort. They are intended to quantify these changes across scales and for landscape habitats found in the study area and identify relative trends of changes within the system.

Ongoing development for urban growth and agriculture has steadily decreased the natural system throughout the twentieth century. Removing the natural structure and function of the system as it existed has compromised the ability of the ecosystem to sustain itself. As components of the system have been removed, it is important to understand what their functions were, how they originally operated, and what components are necessary to restore these functions. Since the historic (pre- 1880) natural vegetation patterns are known anecdotally at best, it is necessary to begin this work with the system and information that exists today and to measure changes through time. The assumption of this approach is that restoration will result in change reflective of what we assume the historic system to have been.

Evaluating how restoration affects landscapes within the south Florida ecosystem will involve measuring composition and configuration on a temporal and spatial basis using change detection methodology. This can be done in conjunction with the ongoing landscape modeling efforts of the Across Trophic Level System Simulation (ATLSS) program of the Biological Resources Division (BRD) of the U. S. Geological Survey (USGS) and the South Florida Water Management District's (SFWMD) Everglades Landscape Modeling (ELM) process. Whereas these ongoing modeling efforts are focused on predictive methods, the success indicators are designed to use these and other existing programs to describe actual changes. The restoration of the system must take into account the loss of natural communities now covered by urban and agricultural areas. Therefore, a reasonable asses nent of the system can be made by examining future change against a more recent baseline assessment.

The general approach planned for these landscape ecological indices is to use data from existing programs to evaluate the study region. This approach will also be dichotomous, evaluating public and private lands separately. This process will better identify which components of the restoration are successful and where further changes are needed.


Ecological Success Index (ESI)

I. VEGETATION CHANGE INDEX

II. RATIONALE

There are two components of this process, measuring changes in landscape diversity and measuring the reappearance of missing landscape elements. These indices will evaluate the vegetative changes that have occurred on both public and privately owned land using a geographical information systems (GIS) approach by sub-regions (Figure 2). The first component of this analysis requires GIS techniques to describe and quantify changes within the sub-regions. This will be done for each sub-region by the sub-regional landscape elements to quantify the vegetation information and complete Table 1. Table 1 shows the sub-regional landscapes and their elements. It is comprised of the Nature Conservancy coverage as applied by the GAP program at the University of Florida and how it is related to the cover categories for the freshwater and coastal system as described by Browder and Ogden (in press).

Quantifying change within the system requires answers to several questions. Is the natural system getting smaller or larger, and what are the concomitant changes working with this shift? Is the existing system getting more or less fragmented? Is there a vegetation shift and if so is it occurring in a natural way? Is a vegetation shift caused by natural processes such as sea level rise (Maul, 1993) or climate change? Can the result of changes due to natural processes measured in a quantifiable way?

The success criteria include analyses of the system to quantify changes in landscape diversity based upon composition and configuration descriptions of the landscapes. These analyses provide a basis for understanding the elements that compose each unit, and how they interrelate in their physical location. These relationships may vary depending upon the scale used, which will be based on informational needs. This work will show the presence and relative size of given habitats, provide an indication of fragmentation, and may begin to define landscape scale and the processes acting upon the area.

The second portion of the vegetation change index involves quantifying the reappearance of landscape elements defined in the process as missing. Landscape elements were known to occur under natural conditions include pond apple (Annona glabra) sloughs, sawgrass (Cladium jamaicense) plains, cypress (Taxodium spp.) strands, transverse glades, short hydroperiod wetlands, and seagrass communities. Other vegetative categories identified include coastal and inland scrub communities. These communities have been identified as either severely impacted, lost to the current system, or in danger of being lost.

[ Figure 2: Ecosystem Restoration Sub-Regions ] [ Table 1: Sub-Regional Landscapes and Their Elements ]

III. RECOMMENDED SPECIFIC SUCCESS CRITERIA

A. Statement of Success Criteria

The proposed initial measures evaluate changes in landscape diversity and the reappearance of missing landscape elements in the natural system as well as in the urban and agricultural areas. A combination of imagery, zoning information, and permitting data will be used to quantify, on a system-wide basis (natural, protected, agriculture and urban), the available area of the system and changes resulting from restoration efforts.

B. Reference Baseline

Potential sources:
  1. Use the most accurate existing imagery that has already been ground truthed available for the period 1993-current. Subsequent new imagery will be classified and ground truthed for comparative analysis and re-scored when this is accomplished;
  2. G.A.P. coverage for vegetation and related digital imagery;
  3. SFWMD wetland maps of the WCAs, and Holy Land Wildlife Management Area;
  4. National Wetlands Inventory (N.W.I.) maps for south Florida;
  5. Existing hard copy and electronic permit data to most accurately define loss in extent and type of wetlands in areas outside of the National Parks, protected areas, and the Conservation Areas;
  6. Alexander plots for 1974 in combination with McPhearson, 1972 data;
  7. Vegetation mapping project on both the macro and meso scales by U. S. Park Service South Florida Natural Resource Center (ENP-SFNRC), south Florida vegetation map and data base of ENP, Big Cypress National Preserve (BCNP), Biscayne National Park (BNP) and the Panther National Wildlife Refuge (PNWR).
  8. Florida Department of Environmental Protection-Florida Marine Research Institute (FDEP-FMRI), SFWMD, Environmental Protection Agency (EPA), Metro Dade County Department of Environmental Protection (DERM) coverage and information for seagrass distribution and density.

C. Historic condition

A pre-project initial baseline can be constructed from a combination of soils data from Jones (1948), early Soil Conservation Service (SCS) maps, soils data from Davis (1946) and the vegetation map from Davis (1943a). A modified version of the vegetation map from Davis (1943 a) is available from Florida Department of Environmental Protection (FDEP) Florida Marine Research Institute (FMRI) and can be used for a baseline comparison. This data layer can be compared by aggregating current classifications of modern maps. An initial attempt at defining the relationships between historic classifications and modern landscapes by Browder and Ogden (in prep.) shows the agreed upon baseline from a combination of historic vegetation, and has been modified to create Table 1 to conform to an aggregated version of the current GAP project.

D. Expectation from restoration

It is expected that the extent of the natural system will continue to decrease until restoration begins to improve and restore historic areas. As restoration improves the system, specific patch cover types will increase in area. At some future time, wetland losses to development will be equalled by wetlands restoration or acquisition. A further expectation from restoration is that missing landscape elements will reappear and increase.

E. Scores and scoring methodology

1. Regional Definition

The appropriate landscape elements will be identified for each of the listed regions (Figure 2). The area of each element will be determined, or some selected sub-plot within each region will be monitored. This acreage will be compared using trend analyses for each year of available data. The boundaries of the study area must be specified geographically using global positioning system points. The total value of all landscape areas or the sub-plots within each region will sum to 100% of the region or area under study. The landscape units by region will therefore sum across regions to 100% of the study site. In addition, all elements will have some total area for the whole system and by region.

Results of the detailed meso scale analyses of the ENP, Big Cypress National Park (BCNP), Biscayne National Park (BNP), and the Panther National Wildlife Refuge (PNWR) vegetation complex will be integrated and analyzed using standard change analysis methodology. This DOI mapping project uses 1 km x 7 km areas of low level color photography of vegetation plots as sub-samples of the macro-scale vegetation mapping which will result in a finer resolution of 1:6000 scale for these sub-units. The macro scale mapping effort is on a 1:24,000 scale.

2. Proposed Methods
Table 1 will be created and quantified for each of the following regions: Specified Regions as defined by the Science Sub-group report
  1. Kissimmee River Basin
  2. Lake Okeechobee and Fisheating Creek
  3. Upper East Coast, St. Lucie River
  4. Everglades Agricultural Area
  5. Water Conservation Areas
  6. Big Cypress Basin
  7. Mainland Portion of Everglades National Park
  8. Florida Bay/Florida Keys/Biscayne Bay and Adjacent Coastal Waters
  9. Lower East Coast Urban Area (Metropolitan Ridge)
  10. Caloosahatchee River Basin/Southwest Florida

Landscapes elements described in Table 1 will be evaluated using compositional and configurational analyses and evaluation of relative trends. Temporal changes will be described using standard change detection techniques based on available classified imagery by region. Vegetation mosaics within the landscapes will be described and quantified using the following metrics.

Composition:
  1. Patch density- a frequency distribution of area by patch type (class) where division by total area gives this normalized index.
  2. Frequency distribution of patch size by patch type.
  3. Total acreage by cover type.
  4. Trend analysis using Coastal-Change Analysis Program (C-CAP) detection change technique to evaluate multispectral imagery for the time period of interest .
Configuration:
  1. Alignment
  2. Contiguity
  3. Nearest neighbor
  4. Fractal dimension as a measure of shape complexity
  5. Core area

Trend analysis will entail plotting the total area of each vegetation mosaic against time, while cumulatively summing these areas to represent their respective contributions to the total area of the system at any time. Cumulative area of the entire system is plotted along the y axis as a function of the sum of the area of each individual mosaic type.

IV. SUPPORTING INFORMATION NEEDED

Supporting information necessary for this index includes ground truthed imagery, electronic information on wetlands permitting and mitigation, and zoning coverage by county. In addition, nearest-neighbor considerations are important when analyzing the significance of changes within the system. It is important to understand the 'openness' of the landscape with respect to the phenomena of interest. A landscape whose extent is smaller than the home range of the organism or the scale of the ecological process of interest constitutes an open system (McGarigal and Marks, 1994). This may impose boundary effects, which can be dealt with by increasing the landscape size relative to the scale of the phenomena.

V. OTHER POTENTIAL SUCCESS CRITERIA

Continue to evaluate the types and forms of information that can be processed and included using this type of data. Further usage includes creating a cross-scale native vegetative landscape pattern description, with proportions similar in structure and function to the pre-drainage and re-development system, using a re-assessed reconstruction of that system as a benchmark. This will facilitate moving the system toward a "historic vegetation" condition where possible. The most useful thing about a description of native vegetative habitat would be beginning to understand the habitats which result from various processes. Since the effects on the system of substantially altering large scale ecological processes are largely unknown, it is important to quantify the results of any changes in the system as they occur. This must be done in a way which will facilitate understanding which processes to alter and which way to alter them to achieve the desired results. Alterations may result in both positive and negative indices since various patterns will change in both directions.

VI. SCIENTIFIC SUPPORT NEEDED

A. Prepare, improve, and test recommended success criteria

Field Sampling:
Revisit field sampling plots for historic and current studies as a means to verify images and to examine pattern changes.

More detailed work would increase the field truthing necessary due to fine scale of measurement and an increased interim between assessments (>3-5 yrs). Additional research may stem from these information needs as well as determining connections between scales, what processes act on each scale, and how to relate the scales to each other.

B. Interpret results.

Modeling and special studies will be examined as a feedback component to adaptive management of the system. This information will be examined in relation to ATLSS and ELM output.

C. Develop potential success criteria.

Other success criteria may be developed as information becomes available from this analysis and from the large ecological models of ATLSS and ELM.


Ecological Success Index (ESI)

I. NUTRIENT TOLERANT VEGETATION CHANGE INDEX

II. GENERAL RATIONALE

Shifts in nutrient balance and availability within the Everglades ecosystem have caused various imbalances in oligotrophic plant communities (Scheidt, 1988; Swift, 1984; Jones and Amador, 1992; SFWMD, 1992; Davis, 1994). The principal expressions of these nutrient changes have been an increase in the aerial extent of cattails (Typha spp.), and shifts in the composition of periphyton communities (Davis, 1994; Browder et al., 1994). Both nitrogen and phosphorus availability and concentrations have changed within the system (Amador et al., 1992; Scheidt, 1988). Although nitrogen is found to be the limiting nutrient in many ecosystems, phosphorus has been demonstrated to be limiting within south Florida's ecosystems (Powell et al., 1989; Fourqurean et al., 1993; Amador and Jones, 1993). Nutrient-induced shifts within the vegetation communities of the Everglades are best documented for periphyton communities (Browder et al., 1994) and the sawgrass (Cladium jamaicense) marsh, where cattails (Typha spp.), normally a minor component of the system, have expanded in response to increased phosphorus availability (Grace, 1988; Scheidt, 1988; Davis, 1991). In addition, Amador and Jones (1993; 1995) have shown changes in microbial community components of Everglades soils in response to phosphorus changes and effects on peat deposition processes.

Changes resulting from increased phosphorus levels within the normally oligotrophic Everglades communities are first demonstrated in soils, as increases in total phosphorus concentrations (Amador et al., 1992). Changes in soil total phosphorus concentrations affect microbial processes such as respiration and carbon mineralization, as well as shifts in C:N and C:P ratios in soils (Amador and Jones, 1993,1995; Amador et al., 1992; Jones and Amador, 1992). Changes in soil total phosphorus concentration and soil microbial communities are expressed in shifts in periphyton communities (Swift, 1984; Browder et al., 1994). Ultimately these changes are then expressed in macrophyte communities such as the sawgrass (C. jamaicense) marshes, where this oligotrophic species is out competed by the faster-growing, more nutrient-tolerant cattail species (Typha spp.) (Scheidt, 1988; Davis, 1991; Davis 1994; Grace, 1988).

Success criteria for changes in nutrient-tolerant vegetation will utilize ongoing work to document shifts in plant species of the sawgrass marsh due to nutrient enrichment. The initial phase of this work will be focused on the Cladium-Typha shift. Recommended research is to document nutrient-related shifts in other plant communities, and evaluate remote sensing means of measuring nutrient changes prior to their expression in plant community shifts. Currently there is an ongoing process to document plant community shifts in the sawgrass marshes of the Water Conservation Areas by the staff of the South Florida Water Management District (SFWMD). In addition there is ongoing research by the Department of the Interior on threshold impact studies (conducted by Florida International University) and studies sponsored by the sugar industry and Duke University to examine the Cladium-Typha shift.

III. RECOMMENDED SUCCESS CRITERIA

A. Statement of Success Criteria

The initial criterion of success is that nutrient-tolerant plant species expansion will stabilize and cease throughout the system. Reduction in phosphorus loading will decrease the expansion of cattails and shifts in periphyton communities. Other potential vegetation shifts that may be related to nutrient loading of either phosphorus or nitrogen, or a synergistic effect of both nitrogen and phosphorus will eventually be measured.

B. Reference Baseline

Reference baseline is the existing system as determined by a combination of 1) the 1993-94 imagery from GAP/C-CAP projects, 2) the detailed vegetation map created by Rutchy and Vilchek (1994) and currently in process at the SFWMD, 3) the WCA 1,2a, 2b, 3a, and 3b, the Holy Land Wildlife Management Area, and 4) the US Park Service vegetation mapping project on both the macro and meso scales for ENP, BCNP, BNP, and the Panther National Wildlife Refuge (PNWR).

C. Historic Condition

Historic condition of the system shows the existence of Typha spp. communities, principally around alligator holes and other sources of nutrients such as bird rookeries (Craighead, 1968; Frederick and Powell, 1994). Historic extent and relationship of Typha spp. communities may be able to be estimated from Davis (1943a) where there are areas without extensive areas of this species, since it is not expected that nutrient enrichment had a significant effect until after this map was produced.

D. Expectation from restoration

Restoration is expected to decrease the areal extent of Typha spp. community coverage within the system, particularly in those areas affected by agricultural and urban runoff. The initial expectation is for areal expansion to cease, and after a lag phase, for the community to shift back to oligotrophic species in their natural densities.

E. Scores and scoring methodology

The current mapping effort by the SFWMD used SPOT (HRV2) 20m multispectral digital satellite imagery from August 1991. After a combination unsupervised/supervised classification, a final number of 30 clusters was evaluated by field reconnaissance. Each cluster was located using GPS and field verified (Rutchy and Vilchek, 1994). Final groupings resulting from evaluation and field verification are from the categories listed in Rutchy and Vilchek (1994).

Standard change detection will be done using imagery available for the WCAs as an initial demonstration and verification of this technique and its application to detecting shifts in Typha communities. This analysis will be done utilizing methodology from the NMFS coastal change and analysis program (CCAP) and Jensen (1986). As imagery is available and verified for other regions within the study area (including south Florida National Parks' meso scale vegetation mapping) it will be examined utilizing this technique.

IV. SUPPORTING INFORMATION NEEDED

Extensive field verification of vegetation is necessary.

V. OTHER POTENTIAL SUCCESS CRITERIA

Micro and nano scales should be examined using criteria outlined in Pomeroy et al. (1995) (Appendix 1). Researchers working on plant response to phosphorus thresholds should develop a common set of reference sites in each Everglades habitat type. The number of sites should be large enough to span possible site variability and any nutrient gradient across the spatial extent of the Everglades Protection Area (EPA). Reference sites would then be able to show species variation, such as sawgrass morphometric changes, due to nutrient condition. Sawgrass under low nutrient conditions is less than a meter tall but under higher nutrient conditions it can grow to a height of up to a meter (Armentano unpublished data; Newman et al., 1996). Other benthic macrophyte species should be examined to determine whether they exhibit similar phenomena. These reference sites should also represent the diversity of periphyton communities.

VI. SCIENTIFIC SUPPORT REQUIRED

A. Prepare, improve and test recommended success criteria.

Further information in relation to the effects of water depth, hydroperiod, fire regime and their interactions of shifts of Cladium to Typha (Newman et al., 1996).

B. Interpret results.

It is documented that in the southern Everglades region that Typha replaces Cladium after a fire and can occur in larger patches of unknown duration as a natural feature (Wade et al. 1980). It is also featured by stabilized deeper water in addition to nutrients which must be considered when evaluating Typha spread (Newman et al, 1996). It is important to determine the differences between observed effects due to nutrient elevation verses confounding effects of fire, hydropattern and hydroperiod. This must be evaluated when interpreting all results. This may involve additional field research to determine the mechanism of observed interactions.

C. Develop potential success criteria.

Potential additional criteria may be derived from future research or as a component of the SFWMD's Stormwater treatment research.


Ecological Success Index (ESI)

I. EXOTIC SPECIES CHANGE INDEX

II. GENERAL RATIONALE FOR EXOTIC PLANT SPECIES BASED SUCCESS CRITERIA

Currently in south Florida the Exotic Pest Plant Council's list of "Florida's most Invasive Species" records 126 exotic plants as posing a serious threat to the native plant communities. Of the existing established exotic species, 60 have become serious threats to the ecosystems of south Florida, and their removal from the system or control must be incorporated into restoration plans. The five species identified as primary threats are melaleuca (Melaleuca quinquenervia), Brazilian pepper (Schinus terebinthifolius), Australian pine (Casuarina sp.), latherleaf (Colubrina asiatica), and the old world climbing fern (Lygodium microphyllum). These plants are causing widespread changes and damage to native plant communities within the Everglades system.

To address these problems, a combination of methods are being implemented throughout south Florida. Herbicidal, mechanical, physical and biological control programs are being implemented by a multi-agency group coordinated through the Exotic Pest Plant Council. The South Florida Water Management District administers the overall program covering the boundaries of the District, but principally concentrates on canal banks, District lands, Lake Okeechobee, and the Water Conservation Areas (WCA's). National Park staff administers the area covered by Everglades National Park, Biscayne National Park Big Cypress National Preserve, and other Department of Interior lands as requested. It is necessary both to classify and identify the potential threats of exotic plants to the natural system, and to measure the success of programs to halt the spread and damage by these exotic species.

The status of the four major exotics identified can serve as a guide to the success of efforts to remove exotics and restore the natural ecosystem. In 1993, aerial surveys were implemented by the SFWMD and the US Forest Service Southeastern Experiment Station. This project was designed to implement the reproducible survey method to measure non-cryptic exotic plant species.

III. RECOMMENDED SPECIFIC SUCCESS CRITERIA

A. Statement of success criteria

Success criteria include a measure of the amount of information known about potential exotic plant invaders, the area of invasion by the critical species, how well these species are being controlled and the quantification of the areal extent of invasion by the identified species. Success is defined as a decrease in the number of potential new exotic plant threats to the system, a decrease in the area of invasion by the four critical species, and an increase in the state of control of these plants.

B. Reference Baseline

Reference baseline will be the 1994 exotic surveys by the SFWMD and the U. S. Forest Service, as well as the baseline knowledge of exotics for that year.

C. Historic Condition

This project's historic condition is the pristine condition of the original system.

D. Expectation from restoration

The expected trend from restoration will be a decrease in the number of potential new exotic threats to the system, and a decrease in the areal extent covered by the identified four critical plant species. An effective methodology to combat new exotic plant invasions will be developed.

E. Scores and scoring methodology

Methodology will be broken into evaluating the information and data available for both the known threats and potential new threats to natural systems, and assessing the existing or known threats. The first component of this process is a survey of the system to identify information needs and the potential for new exotic plant threats. This is to be accomplished using rankings based on the plant survey on Table 2. The second component of this scoring methodology is a survey of the system for the extent of the four identified critical exotic plant species by the SFWMD and the US Forest Service Southeastern Experiment Station (USFSSES). This project was implemented in 1993 as aerial surveys designed to implement a reproducible survey method to measure non cryptic exotic plant species. Information must be summarized by number and extent of patches, as well as by percent of area invaded.

IV. SUPPORTING INFORMATION NEEDED

Supporting information will be needed as identified under the plant survey of information in Table 2. On-going areal and ground surveys of the system are needed by the SFWMD and USFSSES for the critical plant species and on-going assessments to determine potential new plant threats. On-going coordination from the Exotic Pest Plant Council for Florida is necessary to continue to exotic restoration efforts and implement new strategies as they are identified.

V. OTHER POTENTIAL SUCCESS CRITERIA

Other potential success criteria include plant responses to individual treatment methods. Are certain treatments more cost effective than others? It may be possible to determine the most effective treatment methods depending on the type of habitat where the plant is the worst problem. Methods to determine the most cost effective means of treatment and which method is the most effective for treating large areas could be used as other potential success criteria. Methodology may also be utilized after Hiebert and Stubbendieck (1993) to evaluate new exotic plant threats and develop strategy for controlling them.

VI. SCIENTIFIC SUPPORT REQUIRED

A. Prepare, improve and test recommended success criteria.

Modeling of exotic plant community changes may be implemented at a future date, if identified as important. In addition it may be added as a vegetation component of the Across Trophic Level System Simulation (ATLSS) if identified as important.

B. Interpret results.

Modeling monitoring and special studies will be examined as a feedback component to adaptive management of the system.

C. Develop potential success criteria.

Other success criteria may developed as future data becomes available.

Table Two: Exotic Plant Index: Indentification of new and existing exotic threats, ranking by plant species

Precursor Success Index (PSI)

I. SPATIAL EXTENT INDEX

II. GENERAL RATIONALE FOR SUCCESS CRITERIA

A. Introduction

These criteria are intended to measure the effectiveness of restoration for supporting the viability of natural flora and fauna through direct habitat enhancement and hydrologic enhancement in the protected areas. They are designed to evaluate the success of hydrologic restoration in conjunction with buffering wildlife habitat from the effects of development and habitat fragmentation. In addition to this primary goal of hydrologic restoration, buffer areas serve to increase the effective areas of existing habitats while decreasing the effects of edges on core areas. Major values of buffer areas are their ability to provide undisturbed core habitat for a broad variety of interior species, with short hydroperiod marshes, pinelands, cypress domes, and hammocks in their wetland mosaics. The buffer areas are intended to provide hydrologic restoration of the protected system, buffer habitat between existing conservation areas and urban and agricultural development, connect sensitive habitats in a biologically viable way, utilize existing anthropogenic areas or features for buffers or corridors, and when possible provide for the sensitive construction of facilities for human recreational use.

Both buffers and corridors are discussed under the criteria of protection of conservation lands, although they are separate entities. These criteria allow for evaluation of land protection, measurement of the increase in functional connectivity of protected areas, preservation of existing easement areas, and coordination with planned recreational use areas. These criteria are divided into buffers, ecologically viable corridors, existing anthropogenic features, and wildlife-sensitive construction of new features. Each category will be assessed separately using similar methods.

B. Specific definitions:

wildlife habitat - natural flyways, flowways, and uplands; artificial wildlife habitats (e.g., greenways, blueways and corridors)

greenways and blueways - linear habitats.that are created or restored along existing features (e.g. railroad beds, canals, streams).

corridor - natural or artificial habitat that connects larger patches of habitat

connectivity - when ecological processes can occur between habitats (e.g. exchange of individuals, gene pools, nutrients, energy)

open land - land which is not build upon or developed, but includes environmentally protected lands, open lands, parks, agricultural lands and silvicultural lands.


Precursor Success Index (PSI)

I. NATURAL AREA AND BUFFER AREA CHANGE INDEX

II. RATIONALE FOR SUCCESS CRITERIA FOR BUFFER AREA CHANGE INDEX

The primary areas originally designated as buffer areas were initially designed in the restoration process as hydrologic breaks between developed areas in the east and natural features found to the west in the Water Conservation Areas and Everglades National Park. In this capacity the existing vegetative community was less important than the ability to serve the hydrologic function of providing a location for water storage and a "stepped" water table gradient between the natural and developed systems. These hydrologic buffers function to decrease human impacts on protected or sensitive areas by providing hydrologic restoration, an ecosystem gradient and decreasing edge effects or impacts.

Functions of general buffer areas are as wildlife protection areas, as habitat themselves, and as a means to decrease edge effects on protected areas. Some additional functions commonly associated with buffer areas include:

Increasing buffer area around protected areas will provide a gradient between development and core habitat. It also represents a change that may help to restore natural gradients lost from south Florida. Buffers, serving as hydrologic breaks, have been defined by the restoration process but additional buffer areas can be used as a means to improve habitat quality for targeted species or restore lost habitats. Buffer areas should thus be defined in terms of their potential to provide some of the listed functions.

To be effective, buffer areas must be located adjacent to natural features they are designed to protect. For the C&SF project area, buffers must be contiguous areas located in the corridor between the levee system defining ENP and the WCA's and the urban east coast, and possibly areas to the west, between the main wildlife areas and the Gulf of Mexico. These areas should have the same physical structure and function as natural communities and systems, but may have degraded plant communities that can subsequently be restored. They serve the function of protecting the remaining natural areas from further harm and environmental impacts, while providing some of the functions of the missing short-hydroperiod wetlands and forest communities. These buffers are intended to protect preservation areas from hydrologic impacts, wildlife disturbance due to the proximity of developed areas, anthropogenic chemical impacts, or any other degradation.

III. RECOMMENDED SPECIFIC SUCCESS CRITERIA

A. Statement of success criteria

This criterion is comprised of three indices, based upon the acquisition of open land: the ratio of the amount of land acquired to the open land available during an index year, the ratio of the amount of available land developed to that available from the index year, and the ratio of acquired land to protected land. For the first index, the more land acquired as measured against the open land available in the index year 1991, the higher the score. The second, a negative index, is calculated as the area identified in the index year that has since been developed. The third index is a measure of the relationship of buffer area to existing protected healthy system; it is the amount of buffer land divided by the area of existing protected land in index year 1991 and measured against the total available protected lands.

B. Reference baseline

The reference baseline to compile the buffer acquisition criteria was chosen to be 1991, a year for which information is available and these numbers can be defined.

C. Historic condition

The historic amount of adjacent short-hydroperiod wetlands has not been quantified. The buffer lands under consideration along the water conservation areas may be expected to replace the short-hydroperiod wetlands as well as other functional components of the historic natural system and their concomitant functions.

D. Expectation from restoration

It is expected that, as buffer lands are acquired, the positive index will increase.

E. Scores and scoring methodology

1. Measure:

Methodology A: Selecting 1991 as the index year, compile the number of acres in this year defined as non-residentially developed land. The land categories would include open land, park land, environmentally sensitive land, un-zoned land, agricultural land, pasture, improved pasture, and other 'non-urban' land. A maximum value would be calculated, and an index value of from zero to one determined by dividing the amount of land acquired by the maximum value. The second, negative index is calculated as land that has since been developed (and therefore not available) divided by the total acres of land available as identified in 1991. It is important that this area be contiguous and that it include a N-S and at least one E-W corridor of upland habitat. The buffer area index is the area of land acquired additional to the existing protected area, divided by the actual acreage of healthy protected area. This would provide a quantifiable measure of relative increase or decrease of area with respect to protected healthy areas as of the 1991 index year.

Methodology B: Define the currently protected areas of interest and the core area or nature reserve area. Determine the area around or on the edge of this core area as a potential buffer area. The potential buffer area is determined by the amount of area needed by the preserve to protect the core area and its functions.

Definitions:

This area is defined as B(A)
where B(A) =the width of the buffer zone needed to protect a reserve or core area of size A.
S = The total amount of land available for purchase for inclusion as the buffer zone.
A = area of the core habitat, park area, or preserve.

dS/dt = rate at which the available land around the reserve is shrinking,and
= F(Lp, Ld, U)
where: Lp = land price
Ld = land desirability
U = unknown factors

This rate can be compared to the amount of time needed to determine the area necessary to preserve the identified functions of the core area. This information can be used to predict, roughly, how soon it will be too late to buy the amount of land identified as B(A). The rate at which available land is being lost, dS/dt, can be determined from the rate of permit issuance by county for the area of interest.

2. Discussion:

To some extent, the area for buffers will be determined by the need to hydrologically step the water table down from the conservation areas and the Park into the developed areas. The water levels will be determined by the water levels that will be held west of the levee. Underlying this concept of hydrologic buffer is the need to preserve, restore or recreate specific portions of the system. The importance of these areas can be defined under the "missing vegetation" portion of this document. The functions of these areas depend upon the total area of a given vegetation or habitat type remaining within the protected areas. The function of hydrologic buffer requires contiguous land that can be flooded. The concept of biologic buffer may be able to incorporate less intensive land uses such as different types of agriculture. It may also be that a biologic buffer may be enhanced further by additional stepped land use, such as agriculture, as the next level of buffer. This may aid species requiring extensive home ranges without human presence (or with minimal human presence).

IV. SUPPORTING INFORMATION NEEDED

Information necessary for this work includes; hydrologic effects of buffers on surrounding developed areas, actual storage capacity, detailed evapotranspiration rates for existing and proposed vegetation.

V. OTHER POTENTIAL SUCCESS CRITERIA

Other potential success criteria may be identified as part of the ATLSS or ELM modeling process. These criteria would potentially depend upon the identified needs of various functional groups for habitat or for forage areas that exist outside of the existing protected areas.

VI. SCIENTIFIC SUPPORT REQUIRED

A. Prepare, improve and test recommended success criteria.

It is important to document the use and relative success of buffers. Hydrologic buffers designated as components of the hydrologic restoration of the Everglades must be evaluated for other functions, particularly for wildlife and vegetation restoration.

B. Interpret results.

Result must be interpreted in the context of habitat requirements of faunal components of the system and in terms of the impacts of the removal of buffer lands on the protected areas.

Develop potential success criteria.

Success criteria may be derived from faunal habitat improvements. This may be measured in terms of improvement in wildlife biomass or in improvement in areal extent of wildlife habitat.

Precursor Success Index (PSI)

I. CORRIDOR INDEX

II. GENERAL RATIONALE

Measures of corridors and greenways divide these components into two categories: those primarily designed as habitat or as movement corridors and those that are primarily anthropogenic (such as utility easements, bike paths, and canals) but may aid wildlife movement and habitat protection in an ancillary manner. Corridors can be defined "... as the structural framework for the movement and migration of organisms." (Gulinck et al., 1991). Simberloffet al. (1992) defined six types of corridors from the conservation literature, which they divided into the following categories:

  1. corridors that are actually habitats, where their utility for habitat can be defined separately from that as a movement corridor,
  2. greenbelts and buffers when described as corridors,
  3. biogeographic land bridges, geo-structural features such land bridges,
  4. a series of discrete refuges for migratory birds
  5. underpasses and tunnels used to facilitate movement under highways
  6. strips of land intended to facilitate movement between larger habitats.

This assessment defines the categories as

  1. Buffer to existing protected area.
  2. Habitat-scale land feature (or mosaic), which coincidentally connects two or more larger pieces of habitat (already protected habitat).
  3. Land whose specific function is to connect existing pieces of protected area.
  4. Land whose function is anthropogenically based, but is compatible with wildlife use.
  5. The connection of habitat found on either side of an existing anthropogenic faunal break feature (e.g. highways).

Each of these categories represents different perspectives on use and habitat for target species. These different mosaics are defined by scale, edge shape, and edge-to-area ratio.

The success of these structures for wildlife use depends on their being defined from the point of view of the user (Soule and Gilpin, 1991). Each structure suffers from edge effects, where many factors come into play. For example, as width increases both edge and mortality decrease (Soule and Gilpin, 1991). The creation of dramatic edge effects along contiguous highly contrasting plant communities such clear-cut and old growth forest results in intrusion and increase of edge species and a decrease in rare or sensitive interior species (Harris and Scheck, 1991; Simberloff et al., 1992; Soule and Gilpin, 1991).

III. RECOMMENDED SPECIFIC SUCCESS CRITERIA

A. Statement of Success Criteria

This success criteria seeks to identify and preserve natural and anthropogenic habitats based on the needs and spatial extent of wildlife for each sub-region. Areas where corridors are necessary will be identified, and quantified according to the type and extent of area required for movement of target animals. Utility and other anthropogenic structures will be identified and preserved as an existing means of movement for wildlife within each sub-region.

B. Reference Baseline

Validate reference maps to:

  1. Look at original spatial extent of wildlife habitats and
  2. Measure degree of fragmentation (i.e. patch size compared with spatial extent).
  3. Use baseline materials designated under general vegetation index
  4. Identify and quantify existing and proposed SFWMD and other utility easements and conveyances.

C. Historic Condition.

Under historic conditions the system was not subdivided and compartmentalized. Improvements to the system using corridors should decompartmentalize the system as well as approximate the natural habitat relationships and interactions.

D. Expectation from Restoration.

Expectation is that, as natural corridors are defined and preserved, target animals (particularly interior species) will form sustainable populations within the regions where they are currently missing or depleted.

E. Scores and Scoring Methodology

  1. Increase in spatial extent, and decrease in numbers of patches with a corresponding increase in patch size.
  2. Minimum width of corridors is 100m for small mammals and lkm for large mammals (e.g. bears and panthers).
  3. Decrease in number of roadkills of bears and panthers (such as through the use of underpasses). Also, decrease in number of patches while increasing patch size.
  4. Total area of South Florida Water Management Districts rights of way available for all components of the system, measured against the index year 1991. A decrease is a negative index.


IV. References

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Alexander, T. R. and A. G. Crook. 1973. Recent and Long Term Vegetation Changes and Patterns in south Florida, Part I, Preliminary Report, South Florida Ecological Study, Appendix G. University of Miami, Coral Gables Florida.

Amador, J. A., G. H. Richany, and R.D Jones. 1992. Factors affecting phosphate uptake by peat soils of the Florida Everglades. Soil Science. Vol. 153, No. 6. pp.463 470.

Amador, J. A. and R.D Jones. 1993. Nutrient limitations on microbial respiration in peat soils with different total phosphorus content. Soil Biol. Biochem. Vol. 25, No. 6, pp. 793-801.

Amador, J. A. and R.D Jones. 1995. Carbon mineralization in pristine and phosphorous enriched peat soils of the Florida Everglades. Soil Science. Vol. 159, No. 2, pp.129-141.

Armentano, T.A. 1997. Unpublished data on Cladium jamaicense in Shark Slough and other locations within Everglades National Park Florida. Everglades National Park-SFNRC, 40001 S.R. 9336, Homestead, FL 33034.

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Browder, J. A., P. J. Gleason, and D.R. Swift. 1994. Periphyton in the Everglades: Spatial variation, environmental correlates, and ecological implications. pp. 379 418. In: Everglades: The Ecosystem and Its Restoration, S. M. Davis and J.C. Ogden (Eds.), St. Lucie Press, Delray Beach, FL, 826 pages.

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Craighead, F. C. 1968. The role of the alligator in shaping plant communities and maintaining wildlife of the southern Everglades. Florida Naturalist. Vol. 41 :2-7 and 69-74 (April 1968).

Davis, J. H. Jr. 1943 a. The natural features of southern Florida, especially the vegetation, and the Everglades. Bulletin No. 25, Florida Geological Survey, Tallahassee Florida. 331 pp.

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Davis, J. H. Jr. 1946. The peat deposits of Florida - their occurrence, development, and uses. Bulletin 30: 1-247. Florida Geological Survey, Tallahassee, Florida. 247 pp.

Davis, S. M. 1991. Growth, decomposition, and nutrient retention of Cladium jamaicense Crants and Typha domingensis Pers. in the Florida Everglades, Aquat. Bot., 40:203-224.

Davis S. M. 1994. Phosphorus inputs and vegetation sensitivity in the Everglade, pp. 357-378. in: Everglades: The Ecosystem and Its Restoration, S. M. Davis and J.C. Ogden (Eds.), St. Lucie Press, Delray Beach, FL, 826 pages.

Forman, R.T.T and M Godron. 1986. Landscape Ecology. John Wiley and Sons, Inc. N.Y., N.Y. 619 pp.

Forman, R.T.T. 1996. Land Mosaics: The Ecology of Landscapes and Regions. Cambridge University Press. Cambridge, Mass. 623 pp.

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Fourqurean, J. W., R. D. Jones, and J. C. Zieman. 1993. Processes influencing water column nutrient characteristics and phosphorus limitation of phytoplankton biomass in Florida Bay, FL, USA: inferences from spatial distributions Estuarine, Coastal, and Shelf Science. vol. 36. pp. 295-314.

Frederick P.C. and G.V.N. Powell. 1994. Nutrient transport by wading birds in the Everglades. pp. 571-584. In: Everglades: The Ecosystem and Its Restoration, S. M. Davis and J.C. Ogden (Eds.), St. Lucie Press, Delray Beach, FL, 826 pages.

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Jones, L. A. 1948. Soils, Geology, and Water Control in the Everglades Region. Bull. 442. University of Florida Agricultural Experiment Station, Gainesville Florida.

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