Restoring habitat for the northern Idaho ground squirrel (Urocitellus brunneus brunneus): Effects of prescribed burning on dwindling habitat

摘要

Land use and fire exclusion have contributed to an increase in ponderosa pine (Pinus ponderosa) forest extent and density in west-central Idaho. Open areas within ponderosa pine forests are decreasing, thus reducing habitat for the endemic northern Idaho ground squirrel (NIDGS; Urocitellus brunneus brunneus). In 2000, the NIDGS was listed on the Endangered Species Act as threatened in part due to habitat loss. Therefore, recovery plans encourage the use of burning to expand meadows and open corridors. We gathered data on habitat attributes altered by prescribed fall burning at three sites selected for habitat restoration. Each site was divided into two units: a CONTROL unit occupied by the NIDGS and a BURN unit not occupied by the NIDGS. We sought to assess whether the prescribed fall burning fulfilled management goals and generated habitat features similar to CONTROL conditions that are suitable for the NIDGS. Data were collected before the fall prescribed burn and one and two years post-burn. Before the prescribed burn, BURN units had higher tree densities and canopy cover than CONTROL units; however, the prescribed fall burn did not reduce tree density or canopy cover one year later. Understory height in the BURN unit decreased slightly post-burn, approaching CONTROL conditions. Majority of understory characteristics were similar between CONTROL and BURN units before, one, and two years after the burn, but understory community structure remained strongly dissimilar. This study preliminarily examines NIDGS habitat and is the first paper to evaluate the effects of prescribed burning as restoration practices to create NIDGS habitat. Key habitat attributes associated with NIDGS presence include tree canopy cover, understory height and community structure, and litter depth. Management goals were not attained within the stated timeline, one year post-burn, or even two years after prescribed burn was implemented. Based on our results, managers should consider extending the timeframe for restoration goal achievement and perhaps modifying goals to include changes in tree canopy cover, understory height and community structure, and litter depth. Future efforts should monitor beyond two years post-fire, focus on long-term effects of prescribed burning, and examine how repeat burns may help attain habitat restoration goals. (C) 2013 Elsevier B.V. All rights reserved.