ESRI Conservation Program: GIS Stories from the field

American Wildlands


[IMAGE]American Wildlands envisions a Northern Rockies Lifescape wherein a vital, interconnected matrix of protected wildlands, with a full complement of thriving native species, co-exists with equally vital human communities and activities; the health and success of all being guided by conservation biology principles and cooperative decision-making. A Lifescape is more than a landscape: it is a living landscape, the land and its abiotic components together with the life forms or biotic components that exist there. Humans are a part of a Lifescape . A healthy Lifescape in our present era consists of a balanced, interconnected, matrix of protected wild lands and human communities and developments, where human beings co-exist, and thrive, along with viable populations of all native species.

CORRIDOR ANALYSIS: The basic framework of corridor analysis consists of identifying areas of habitat which are suitable for the wildlife species in question. Habitat suitability depends upon the needs of a given species. It can be approximated by overlaying layers such as current vegetation, topography (aspect, slope, elevation), distance to water, and perhaps climatic variables such as average temperature and precipitation. Because different wildlife species vary in their sensitivity to human disturbance, habitat suitability is constrained by disturbance variables such as distance to roads, distance to towns, traffic volumes, hunting status, etc. Generally, a coverage of known distribution of a species (sightings, radio-telemetry locations, hunter-kill and road-kill sites) is also developed. ...A probability contour is finally developed from the convergence of these coverages to indicate the likelihood of a given area being suitable for a given species. Where this probable habitat connects areas of known population centers, it is often termed a corridor.

Corridors and Reserve Design: ...The immediate challenge is to design reserves for wildlife that can sustain wildlife populations as human populations continue to increase outside the reserves. The basic design consists of a core reserve where human activities are limited and the maintenance of wildlife habitat and biodiversity are the primary goals. Dr. Reed Noss, with the Wildlands Project, has refined this concept. ...In designing reserves, we are trying to conserve as much of the natural connectivity as possible in the face of human population growth and human developments. A basic assumption of this project is that an interconnected network of reserves will be more effective in maintaining populations of carnivores than would smaller, more isolated reserves. A second assumption of this project is that a reserve design that maintains large carnivores will also maintain prey populations, smaller carnivores, and the majority of native plants and animals. This is known as the umbrella species concept.

Yellowstone Grizzly Bear Management: One of our project areas, in cooperation with the Greater Yellowstone Coalition, A Naturalist's World, and other concerned groups, involves mapping Threats to the Greater Yellowstone Ecosystem . One of the key indicator species of these threats is grizzly bears. To address threats to grizzlies, and other components of the ecosystem, we are developing a GIS database covering the ecosystem. We have prepared maps of individual Bear Management Units (BMUs) which we will make available to individuals and groups. ...An overall map of the BMUs is depicted here. We have prepared larger hard copy maps of each of the BMUs. Our hope is that people will return these maps with information on actual and proposed development projects, open roads, bear attractants, unsanitary sites, dangerous road crossings for wildlife, and any other recent changes in the plant and animal communities that are due to human activities.

Grizzly Bear & Mountain Lion Corridors: This map identifies probable wildlife corridor routes from the north end of the Absaroka Range and the north end of the Gallatin Range across Interstate 90 to the Bridger Range. Habitat suitability for grizzly bear and mountain lion was modeled using Montana Gap Analysis coverages for vegetation type and weighted index for road density (developed by Rich Walker) that was derived as a cell-based integration of TIGER road data. Corridor routes were located using a Least-Cost-Path Analysis algorithm that is standard in ArcGRID....This analysis used a 1-square-kilometer grid size. The routes outlined are only approximate (within a kilometer or two) but are a first approximation of the best habitat available for wildlife movement in this area. The next stage of analysis will more closely identify these general routes.

Cutthroat Trout: Today, according to the most recent scientific data, current distribution and abundance of the westslope cutthroat trout is severely restricted compared with historical conditions, and populations continue to decline at an alarming rate. Pure westslope cutthroat trout (WCT) are extinct throughout most of their historic range, and existing populations are in imminent danger from land-use activities and hybridization. Reasons for the critical condition of the WCT include habitat destruction from logging, roadbuilding, grazing, mining, urban development, agriculture and dams, introduction of artificial hatchery strains, competition and hybridization from introduced non-native fish species, and overfishing.

...In the process of creating WCT distribution maps, a seemingly straightforward task, several cartographic challenges emerged. (In fact, when posed with the same task, the Montana Department of Fish, Wildlife and Parks could not agree on an appropriate means of mapping this very same species.) The most daunting problem was the difficulty of creating maps which adequately reflected the severity of the situation for WCT. Most attempts to render the decline of the WCT made the situation appear much less alarming than the known facts. Several factors contributed to this problem. ...The main hurdles to rendering an accurate map related to the trout being an aquatic animal. Most species range maps depict "areas" a given species (usually an upland animal) inhabits. Fish, however, are confined to aquatic habitats -- thus a depiction of streams with fish populations seems more appropriate. But when showing discrete small streams inhabited by a fish species over a large area (i.e. western Montana and central and northern Idaho) it appeared nearly ubiquitous. This belied the underlying reality of the many small stream reaches in the very same localities where the species has been extirpated.


Text and graphics: American Wildlands
January 2, 1997. 40 East Main Street, Suite #2, Bozeman, MT 59715, Phone: (406) 586-8175 Fax: (406) 586-8242, Email: webmail@wildlands.org

Web layout & design: ESRI Conservation Program, January 2, 1996

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