Ecological Assessment of Aspen Communities in the Klamath Network: A Problem Analysis

Sarr, Daniel

As part of the National Park Service (NPS) Inventory and Monitoring Vital Signs process, aspen were identified as keystone ecosystems in forest ecosystems of several of the parks of the Klamath Network. Aspen stands provide an important source of understory plant diversity in the conifer dominated forests of Lassen Volcanic National Park (LAVO) and may be considered a keystone species. However, studies indicate aspen are declining in the region (Di Orio et al. 2005) and throughout the West (Bartos and Campbell 1998). Preliminary results from an aspen inventory and assessment of LAVO indicate a similar trend. Many stands are small in size, heavily browsed by deer, and experiencing competition from lodgepole pine (Pinus contorta ssp. murrayana Grev. and Balf.) and white fir (Abies concolor Gordon and Glend.). This observed pattern has raised the concern that as aspen stands decline in area, the understory plant diversity harbored beneath them and other ecological values will be lost. The Klamath Network and the parks required baseline data to inform the development of long-term monitoring protocols and to provide information about the current condition of the park stands. The objectives of this project were to: 1. Collect baseline data about the ecological values of aspen communities within the parks to assess whether they function as a keystone species; and 2. To assess current condition and environmental trends in park aspen stands, by measuring changes in the total area covered by aspen over the last 50 years, and by measuring browse and conifer encroachment in the stands. To accomplish these objectives, this study quantified the amount and rate of conifer encroachment in 29 aspen stands at LAVO over the past 50 years. Current aspen stand condition along a gradient of percent conifer canopy cover was measured and the associations between conifer presence and variables representing the ecological values of aspen stands were evaluated. This approach provides managers with information needed to identify management needs and analyze restoration and protection options.

Ecological Assessment of Aspen Communities in the Klamath Network: A Problem Analysis

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