An analysis of management for late-seral-stage (older) forests and riparian areas is underway on the Tahoe National Forest. Wildlife and fish biologists have reviewed related scientific literature and have developed recommendations and desired future conditions for managing older forests and riparian habitats to maintain viable and well-distributed populations of associated fish and wildlife species. These recommendations represent the wildlife and fish desired future conditions for riparian and older forests and will next undergo interdisciplinary review and analysis. The Tahoe National Forest will consider these recommendations and other resource values and develop a proposal for managing older forests and riparian areas. This will lead to an Environmental Impact Statement which will study the biological, physical, social, and economic effects and may lead to an amendment of the Forest Plan.

These recommendations offer a generalized ecosystem framework for establishing management programs for older forests and riparian areas in order to maintain high quality habitat that would support the full assemblage of associated vertebrate species. The framework provides an overview of desired future conditions for landscapes and stands, thus allowing local planning groups to determine specific project-level details and appropriate activities that fit on-site conditions.

The proposed landscape design consists of some large blocks of mature forest and a riparian/older forest network. The goal for the large blocks is to conserve viable sub-populations of wildlife that are associated with the interior zones of older forest habitats. The recommended riparian/older forest network provides a continuously connected system of older forest centered on watercourses and has three components: 1) riparian zone; 2) older forest zone; and 3) connectors.

The riparian zone includes the stream channel, floodplain, and upland areas that directly influence the stream environment. The objectives for the riparian zone are to provide a high quality stream environment and those key attributes that are important for fish and wildlife. The two key riparian attributes identified in the literature review are: 1) the composition and arrangement of riparian and adjacent upland forest canopy and understory vegetation; and 2) uninterrupted surface and subsurface water flows. When the following components are maintained in a natural condition, high quality stream environments can be maintained over time: 1) stream temperature; 2) arrangement and recruitment of large woody debris; 3) sediment conditions; and 4) watershed connectivity and fish passage.

The older forest zone includes, but also extends beyond, the upland area in the riparian zone. Depending on the size of the stream, the objective for this zone is to provide travelways and year-long or seasonal habitat for associated species. Headwater areas would be managed primarily to provide critical habitat for small mammals and amphibians. As stream size increases downstream, an increasingly larger old forest zone (up to 1650 feet) would be managed to provide sufficient habitat for travel and year-long or seasonal use for larger species.

Connectors are included in the network to link older forest habitats into a completely connected system and are intended to provide travelways for wildlife. Connectors are arranged over ridges so that older forest habitat in each planning watershed is linked with habitat in adjacent watersheds.

Where the objective is to provide high quality older forest habitat (the large blocks, the older forest zone, and the connectors), management should concentrate on providing key older forest habitat components over time. The key components identified are: 1) large-diameter overstory trees; 2) large-diameter snags; 3) large-diameter logs; and 4) vertical diversity (multi-layer canopies).

The recommended program for managing older forest and riparian habitats outlines above is viewed as a set of working hypotheses that integrate current science into a comprehensive proposal for forest management. Analytical tools, such as GIS are recommended for evaluating the effectiveness and impacts of the proposed program. These recommendations should be adapted to accommodate evaluations and any new scientific information, as it becomes available. Summary documents of the literature review are available.

Ann and Diana can be reached at (916) 265-4531.