Conservation Assessment and Prioritization System (CAPS) Highlands Communities Initiative PHASE 1
Total Page：16
File Type：pdf, Size：1020Kb
Conservation Assessment and Prioritization System (CAPS) Highlands Communities Initiative PHASE 1 Final Report June 9, 2005 Landscape Ecology Program, Department of Natural Resources Conservation, University of Massachusetts, Amherst. Kevin McGarigal, Associate Professor, Department of Natural Resources Conservation. University of Massachusetts, Amherst, MA 01003. Phone: (413) 577-0655; email: [email protected] Bradley W. Compton, Research Associate, Department of Natural Resources Conservation. University of Massachusetts, Amherst, MA 01003. Phone: (413) 577-2179; email: [email protected] Scott D. Jackson, Program Director, UMass Extension Natural Resources and Environmental Conservation Program. University of Massachusetts, Amherst, MA 01003. Phone: (413) 545-4743; email: [email protected] Kasey Rolih, Research Associate, Department of Natural Resources Conservation. University of Massachusetts, Amherst, MA 01003. Phone: (413) 577-2179; email: [email protected] Eduard Ene, Research Associate, Department of Natural Resources Conservation. University of Massachusetts, Amherst, MA 01003. Phone: (413) 577-2179; email: [email protected] Introduction Planners and conservationists have long sought better ways to proactively conserve the most significant natural areas before they are lost or irreversibly fragmented, but it is difficult to identify which areas are in the greatest need of protection, or which ones provide the greatest ecological value for the cost of protection. Analyzing a landscape’s ecological/biodiversity value requires integrating vast amounts of site-specific information over varying spatial scales. Municipalities and other participants in the decision-making process simply have not had access to the databases and technical tools that these complex analyses require. Furthermore, they have been hindered by a partial or complete lack of information of what—in terms of biodiversity—is present in the landscape, let alone the distribution and inherent value of each natural community unit or the role of each unit in sustaining a fully functioning landscape. Nevertheless, state agencies, conservation organizations and communities across the Commonwealth are spending millions of dollars on land acquisition each year to protect natural areas. During the past several years, we have pioneered the development of a method for quantitatively evaluating the ecological integrity of a landscape and its biodiversity* value at any scale--state, region, watershed, town, etc. The Conservation Assessment and Prioritization System (CAPS) is a community-based, coarse-filter approach for assessing the ecological integrity of lands and waters and subsequently identifying and prioritizing land for biodiversity conservation. We define ecological integrity as the ability of an area to support biodiversity, and the ecosystem processes necessary to sustain biodiversity, over the long term. Our approach assumes that by conserving intact, ecologically-defined communities of high integrity, we can conserve most species and ecological processes. Moreover, by identifying the lands most worthy and in need of protection, towns, land trusts and others can target their limited dollars strategically; in short, they can get the most out of every conservation dollar. Our coarse filter is a first step in the process of targeting land for conservation. Field work will be required to verify predictions made by our broad-scale model, and a further, fine-filter approach will be necessary to include habitat for species of concern that slip through the cracks—this includes many threatened and endangered species. Overview of CAPS CAPS is a computer modeling approach to prioritizing land for conservation based on the assessment of ecological integrity for various natural communities (e.g., deciduous forest, grassland, shrub swamp, first-order stream) within an area. Beginning with a GIS base map depicting various classes of developed and undeveloped land, we evaluate a variety of landscape- based metrics (or indices) to calculate ecological integrity for every point in the landscape. Each landscape metric evaluates a different aspect of the underlying natural community map. A metric may, for example, take into account the size of a natural community patch, its proximity to streams and rivers, the diversity of soil types in the patch, or the intensity of roads in the vicinity. For each natural community, several metrics are applied to the landscape and then integrated in a weighted linear combination. Weights are supplied by expert teams to reflect the relative importance of each metric for each community. This process results in a final “index of ecological integrity” for each point in the landscape. Intermediate results are saved to facilitate analysis—thus one can examine not only a map of the final indices of ecological integrity, but maps of road intensity, natural community patch area, soil series diversity within forested areas, and so on. Hierarchical Community Levels – Within CAPS, ecological integrity may be assessed at three hierarchical community levels. At the lowest level are primary communities, such as shrub swamp, or cultural grassland. These communities are aggregated into secondary communities, such as palustrine or grasslands based on wildlife habitat use. Finally, secondary communities are aggregated into three tertiary communities: Forests, Nonforested Uplands, and Wetlands and *For our purposes, we define biodiversity as the diversity of life at all levels of organization from the gene to the landscape and all the ecological and evolutionary processes and interconnections that support life across levels of organization. In its broadest sense, biodiversity is the variety of life forms and environments that support that life. Here, we adopt a more pragmatic focus on the maintenance of viable populations of all native species (from carnivores to soil bacteria) and ecological communities (hereafter simply referred to as “communities”) found in their natural places, distributed and functioning within their natural range of variability. 2 Aquatic Communities. Thus, each point on the landscape is a member of a primary community, a secondary community, and a tertiary community. Analysis may be done at any of these three levels alone or in combination, and the results can be interpreted independently at each level or they can be combined into a single, multi-level assessment. Metrics do not apply to developed land—all cells corresponding to developed land cover types are given an ecological integrity index of zero, even though we recognize that even developed land may contribute to the conservation of biodiversity. Landscape Metric Groups – Landscape metrics are organized into five groups, and these metrics may be computed at any of the hierarchical community levels: • Composition metrics evaluate the rarity, richness, or evenness of communities or abiotic values in the focal patch, without regard to the spatial context of the patch. • Spatial character metrics evaluate the shape or configuration of a patch, without regard to its composition or spatial context. • Context metrics evaluate the composition and configuration of the neighborhood (i.e., ecological context) surrounding each point in a community. • Condition metrics evaluate negative effects (usually anthropogenic disturbance) on the ecological integrity of each point in a community, based on the composition and configuration of the neighborhood. • Aquatic (watershed) metrics evaluate the condition of aquatic communities based on the watershed above each point, rather than its surroundings in all directions. These metrics follow flow upstream and uphill to define an influence zone for each point, based on the modeled rate of flow across different land cover types and slopes. Watershed metrics are weighted by this influence zone, so that, for instance, a potential pollution source near a stream would have a stronger influence than one far upstream, or a distance away from the stream. Combining Metric Results – Results from the landscape metrics are rescaled, weighted, and then combined into an overall index of ecological integrity. First, the results of each metric are rescaled by percentiles for each community so that, for instance, the best 10% of marshes have values ≥ 0.90, and the best 25% have values ≥ 0.75. This is done to adjust for differences in units of measurement among metrics and to account for differences in the range of metric values for each community. The rescaling by community is done to facilitate identifying the “best” of each community, as opposed to the best overall – which is strongly biased towards the dominant, matrix-forming communities. Next, the rescaled values are weighted (weights assigned by the user), to reflect the relative importance of each metric for each community (Appendix C), and then added together to compute an overall index of ecological integrity. The weighted linear combinations are nested. First, all metrics are combined within each metric group (composition, spatial character, context, condition and watershed). Then, these five groups are combined to represent the index of ecological integrity at the current community level. Thus, the final index 3 of ecological integrity for each cell is a weighted combination of the metric outputs for that cell, based on the community the cell falls in. Identifying and Prioritizing Land for Conservation – Among its many uses, the index of ecological integrity can