• Version
• Download 8
• File Size 828.85 KB
• Create Date 1 January 1999
• Download

We studied riparian habitat use by a high density brown bear (Ursus arctos) population on the Tongass National Forest (Tongass) where spawning salmon (Oncorhyncus spp.) provide an important seasonal food resource. The Tongass contains large tracts of pristine old-growth coniferous forest and some of these tracts are within riparian zones that are subject to timber harvest and various timber management guidelines. Determining the size of protective riparian no-cut buffers to conserve fish and wildlife habitat and water quality was a major component of a revision of the U.S. Department of Agriculture (USDA) Forest Service's Tongass Land Management Plan (TLMP; U.S. Forest Service 1997). We radiocollared 111 brown bears on a 1,119 km2 portion of Chichagof Island to evaluate bear use of riparian habitats and to determine how proposed buffers might be used by brown bears. Our study area was managed for timber harvest and had>25 salmon spawning streams and associated riparian habitats with various riparian-zone management opportunities. Sixty-three percent of 2,069 aerial radiotelemetry locations were in riparian habitats during August and 61% of all August locations were <1,000 m from a salmon-spawning stream. The new Tongass forest plan has 2 types of administrative buffers on salmon streams: (1) a riparian standard and guideline, which is a variable-width buffer and usually incorporates <150 m of protection, and was established primarily to protect salmon habitat and water quality, and (2) a 153-m no-cut buffer established to protect foraging areas for brown bears. Twenty-four percent of the August locations were within the riparian standard and guideline buffer, and 39% fell within the brown bear buffer, assuming it was applied across all salmon spawning streams used by bears. These results were useful in revising the Tongass forest plan and in assisting decision-makers with the necessary information to change historic land allocations and provide more habitat conservation for brown bears. A panel of brown bear scientists recommended that a 153-m no-cut forest buffer be placed on all salmon spawning streams that are used by brown bears. The final forest plan weakened this recommendation, and its implementation will be subject to future interpretation. However, compared with previous forest planning efforts that had little protection of riparian habitats and none specifically for brown bears, this conclusion was an important measure for brown bear conservation.