Use of Gap Analysis Data to Establish Goals and Priorities for Individual Land Management Units - National Wildlife Refuges in Washington State

With demands on natural resources increasing, land managers need to adopt a landscape approach in developing management goals and priorities (Fig. 1). Whereas efforts in the past have focused on individual management units in isolation, Gap Analysis data provide a landscape context for land management units, irrespective of land ownership. In this paper, we describe the results of a preliminary analysis of the contributions of three National Wildlife Refuges (NWRs) to the conservation of biodiversity in the ecoregions in which they are located. This project, which will include all of the NWRs in the state when completed, is a cooperative effort between the Washington Gap Analysis Project, the U.S. Fish and Wildlife Service (FWS) Region 1-Refuges and Wildlife, and the FWS's field office in Vancouver, Washington. Our preliminary analyses include the Nisqually NWR in the Puget Trough ecoregion on the west side of the Cascade mountains, and the Turnbull and Little Pend Oreille NWRs in the ecoregion referred to as the Northeast Corner (ecoregional boundaries correspond to those described by Bailey [1980] as refined by the USFS and WAGAP). For each ecoregion, we identified the proportion of land in each vegetation zone, the actual land cover within each zone, and the proportion of each zone in each of five conservation status categories. The latter correspond to the National GAP guidelines, except that for this analysis we divided lands not managed for native species into public, e.g., DOD and tribal lands (conservation status 4) and private lands (status 5). We then identified those vertebrate species predicted to occur within the ecoregions and each of the refuges. Vertebrate distributions were based on each species' association with actual land cover. This allowed us to calculate the proportion of each species' predicted distribution on "reserves" (conservation status codes 1 and 2; lands managed for biodiversity) and to develop a "report card" describing the contribution of each NWR to the conservation of vertebrate biodiversity in their respective ecoregions. And finally, based on ecoregional context, we made recommendations as to the management goals and priorities for each NWR, both within and outside their boundaries.

Nisqually NWR

The Nisqually NWR, like most of the refuges in the Puget Trough ecoregion, is small and not connected to other areas managed for biodiversity. However, the refuge contains examples of most of the major habitat types within the Puget Trough ecoregion. This habitat diversity accounts for the high proportion of Trough vertebrates predicted to be present (see report card), but surrounding development threatens to reduce adjacent habitat patches to where they may not support viable populations of some species. Lowland forest (<2% in reserves) is particularly threatened within the Puget Trough ecoregion, and forested areas on the refuge are in danger of becoming isolated.

Based on modeled distributions, 45 of the ecoregion's native mammals are predicted to occur on the refuge, including 7 of 9 species listed as threatened or endangered by the state or federal government; 90 of the ecoregion's 144 native breeding birds, including 10 listed species; and 13 of the region's 22 native reptiles and amphibians.

The Nisqually River is the refuge's primary link to larger undeveloped areas. Compared to other large rivers within the Puget Trough ecoregion, the Nisqually has the least surrounding developed and agricultural land. Maintenance of this corridor to other protected areas in the watershed via land acquisition or land-use planning appears to be critical for ensuring the continued contribution of the refuge to the protection of biodiversity in this ecoregion.

Turnbull and Little Pend Oreille NWRs

The conservation status of vegetation zones varies considerably within the Northeast Corner ecoregion (see table below). Statewide, 49 percent of the Ponderosa Pine zone is privately owned. Three percent of this zone is managed for biodiversity in the Northeast Corner ecoregion, compared to 12 percent statewide. The Western Redcedar/Western Hemlock zone also has only 3 percent of its area managed for biodiversity in this ecoregion, but 70 percent of its total area is publically owned. In contrast, 44 percent of the Subalpine Fir zone occurs within "reserves," and only 3 percent of its total area in this ecoregion is privately owned.

Turnbull NWR is almost entirely within the Ponderosa Pine zone. One of its major assets is its status as one of the few conservation areas with this forest type. The refuge is, however, on a "peninsula" of Ponderosa Pine forest among agricultural lands and steppe, and development around Spokane threatens to isolate the refuge from other forests. Fifteen of the ecoregion's 16 reptiles and amphibians are predicted to occur on Turnbull NWR, as are 46 of 64 native mammals, and 105 of 160 species of breeding birds (see report card). Ten listed species of mammals and birds are predicted to occur on the refuge. Management recommendations from this preliminary analysis include maintaining existing grasslands and open canopy Ponderosa Pine woodland on the refuge and, if possible, preventing isolation from other forests to the north.

Little Pend Oreille NWR contains all of the major forest zones and forested habitats within the ecoregion. Not only is it the largest refuge in the state, it is bordered by national forest to the north and south. Because of its size and location, it has greater potential than smaller refuges to support large animals or those with large home ranges. Probably the refuge's greatest deficiency is its lack of connection to habitats along the Colville or Little Pend Oreille Rivers. Most of the reptile, amphibian, and mammal species in the ecoregion and 94 species of breeding birds are predicted to occur in the Little Pend Oreille NWR. Our preliminary analysis indicates that maintenance of a corridor to adjacent river valleys would help maximize the contribution of the refuge to biodiversity protection.

Overall, the three refuges are predicted to provide some habitat for 38 percent of the state's listed species and 80 percent of the remainder. We note that predicted presence does not necessarily mean that the species are confirmed as present or that the habitat on the refuge has been confirmed as suitable. More detailed field-level sampling is needed for the next stage of conservation planning. This analysis is an example of how to begin the planning at the ecoregion and landscape levels.

We believe our analysis, when completed, will serve as a model for the application of GAP data to the development of management goals and priorities within the National Wildlife Refuge System. Similar analyses for Fort Lewis and Camp Bonneville (both belonging to the U.S. Department of Defense) have been well received. The latter was recently considered for addition to the National Refuge System.

Literature Cited

Bailey, R.G. 1980. Description of the ecoregions of the United States. USDA Forest Service, Miscellaneous Publication No. 1391. 77 pp.

Christian Grue, Kelly Cassidy, Michael Smith, Karen Dvornich, Jane Cassady, and Susan Fregien
Washington Cooperative Fish and Wildlife Research Unit
University of Washington, Seattle