Chapter 9: Identification and Mapping of Habitat Cores


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BOOK EXCERPT: Conservation planning requires good spatial data and a basic understanding of what type of habitat is required to support a given species, ensemble, or community. Thus, a critical step in conservation planning is often the development of a map of suitable habitat across a target landscape (see Dickson et al., chapter 7). The next key step is using this map of suitable habitat to identify and map the core habitat required to meet conservation objectives or to be used as an input to subsequent analysis, like population modeling and corridor planning...In most conservation planning, then, “core” has been used to reflect a sense of intact habitat that is unaffected by human disturbance or other neighboring habitat. Thus, this chapter will examine the approaches that can be used to identify and map core habitat based upon a broad definition of core as “an area or patch of relatively intact habitat that is sufficiently large to support more than one individual of a species.” Identification and mapping of the core is a critical prelude to identification of important buffer areas and connectivity issues...The term “relatively intact” is context- and scale-related. At a very broad scale, even a highway through hundreds of acres of habitat may leave it relatively intact. Thus, Yellowstone Park is generally considered core habitat on a regional scale for many species, even though it is intertwined with busy highways and lesser roads. At the scale of the park itself, though, individual cores for different species may be defined in areas remote from the highways. The definition above also lacks a sense of time. In many cases, the conservation goal may be to support or maintain a family unit of a given species throughout their lives or throughout seasons of the year (including migratory routes). At broader scales, a core might maintain an entire population of that species for many generations.Decisions about how many animals are desired to persist for how long into the future need to be made on a case-by-case basis. Determining a core that can support a viable population is discussed by Stanton and Akçakaya (chapter 11); for many species this requires a regional scale of analysis. In many cases however, defining a core for a smaller number of animals persisting for shorter time frames can be an effective conservation goal at a subpopulation level, or even a smaller group at a local level of analysis. Core habitat at these scales can contribute to supporting a viable population at a broader scale...Planning for the protection of natural landscapes in the face of human encroachment, increasing fragmentation, and climate change means that greater efforts will need to be made in modeling habitat and the impacts of change. Better-integrated methods are needed to support planning for the protection of focal species. For example, it is realistic to expect that modeling tools integrated with GIS will form the backbone of future work. As such tools evolve, tools such as Maximum Scatter and RSLM Heuristic will become readily available as an add-on to GIS software. Just as FRAGSTATS can be used to measure many different metrics associated with habitat, core, and fragmentation, better tools and models for modeling and delineating core habitat will be integrated into decision-making aids (e.g. Marxan; Ball et al. 2009). It is also reasonable to expect that one will be able to move across scales using such tools as population viability analysis, habitat models, corridor location, reserve design models, and climate models.


Dr. Richard L. Church
Department of Geography
University of California at Santa Barbara
Santa Barbara, CA 93106-4060





Powerpoint/Teaching Resources: Core, the whole core - BBAR 2010 presentation Tools & MAPS of Habitats (click on thumbnail to pan & zoom, 'view larger' to open window)


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Critical Habitats Mapper (view application ) The Critical Habitat portal is an online service for information regarding Threatened and Endangered Species final Critical Habitat designation across the United States. Not all of the critical habitat data designated by the U.S. Fish & Wildlife Service (USFWS) is available from this portal.



Critical habitats by Ecoregion: Areas considered critical to the survival of a particular species, as determined by USFWS. Ecoregions are areas of similar biota and climate, as determined by the EPA. This map was created by calculating the percent of each ecoregion that is considered critical habitat, regardless of species. The Critical Habitat by Ecoregion map was derived by calculating the percentage of each Ecoregion that is occupied by pixels representing Critical Habitat (of any species). 

3-Scale & Time
4-Land Cover
5-Land Use
6-Focal Species
7-Habitats: Terrestrial
8-Habitats: Marine/Aq
9-Habitat Cores
11-Viability Analysis
13-Climate Change
14-Processes & Tools

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