USDA Forest Service

Pacific Southwest Research Station
Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Research Topics Ecosystem Processes

Sierra Nevada Ecosystems

Small mammal and truffle response to burning in mixed-conifer forest

Study Plan
Research Project Summary

The Research

There is little information to the effects of fuel reduction treatments on wildlife and their food webs. In previous research we found the abundance and diversity of truffles, a key food source in forest food webs, decreased as the intensity of fuel treatment increased. This short-term (≤ 2 years) response, however, may change as truffles, small mammal populations, and forest habitat rebound from prescribed fire and thinning treatments. Using a field experiment with fuel treatments completed in 2001, we are examining whether the intensity of fuel reduction influences this food web by measuring small mammal and truffle abundance, truffle consumption, and habitat variables in replicate plots 5-7 years following burning and thinning treatments. We are comparing the response of the northern flying squirrel (Glaucomys sabrinus; a truffle specialist) and the lodgepole chipmunk (Neotamias speciosus; a dietary generalist) to assess how these ecologically distinct species respond to six different levels of fuel treatment. Changes in the abundances of these two species may significantly influence predators that rely on them, such as the California spotted owl, northern goshawk, and Pacific fisher. Forest managers working with the Teakettle Experiment have urged this study of forest food webs to understand the potential impact of fuel reduction treatments on sensitive species in California’s Sierra Nevada.


Our research objective is to test whether the effect of fuel treatments on forest food webs is dependent on treatment intensity, such that high-intensity treatments (overstory thin, combined thin and burn) generally have a negative impact and low-intensity treatments (burn only, understory thin only) have a positive or neutral effect. Specifically, we predict the following mid-term responses:
blue arrrow truffle abundance and northern flying squirrel capture rates, habitat use, and truffle consumption decline with increasing disturbance intensity;
blue arrrowcapture rates of lodgepole chipmunks, availability of non-truffle foods (e.g., seeds, fruits), and consumption of non-truffle foods by chipmunks increase with disturbance intensity;
blue arrrowthe burn-only treatment has a negative short-term but no lasting impact on all food web variables;
blue arrrow thin-only treatments will have a lasting negative impact on all food web variables, primarily due to slower recovery of flying squirrel and truffle-related stand variables.

Methods and Design

In 1997, the USDA Forest Service Pacific Southwest Research Station and the Sierra National Forest initiated an Administrative Study called the Teakettle Ecosystem Experiment. Eighteen 4-ha replicate plots were established in Teakettle, a 1300 hectare, mixed-conifer forest in the southern Sierra Nevada. Treatments were allocated in a full factorial design and include mechanical thinning (two levels of intensity), prescribed burning, and no treatment (controls).

Small mammal capture rates (flying squirrels and lodgepole chipmunks) in each treatment plot were estimated using mark-recapture of live-trapped animals (9 live trap stations per plot on a 50 by 50 m grid). Truffles were sampled in eight 4m 2 placed 10 m apart along a randomly located transect in each plot. We collected samples in the spring and late-summer (2000-2003) to estimate frequency, biomass, and species richness of truffles. We anticipate collecting more samples in spring and late-summer of 2006-2007. We measured forest stand variables at all live-trap grid points. Truffle consumption by small mammals was determined by microhistological analysis.

A parallel study of the effect of prescribed burning on truffle biodiversity is being initiated in Yosemite National Park for 2006-2007. This study will focus on mid-term (5-12 years) effects of burning on truffle abundance and diversity in Yosemite’s mixed-conifer forests. Another study examining northern flying squirrel nest use in Yosemite National Park was completed in 2005.

Application of Research Results

Managing fuels treatments is an immediate focus of many forestry practices, but the public is often very concerned about potential impacts on wildlife habitat and forest health. Very little information is available about how different fuel treatment prescriptions affect forest food webs and how these changes impact wildlife abundance and habitat use. Much of the controversy over fuels treatments has focused on the perceived negative effects of fire and thinning disturbances on wildlife, despite the fact that these forests had a historic disturbance regime of frequent, low-intensity fire. Immediate effects of fuel treatments are likely to reduce wildlife abundance as animals adjust to new forest conditions. This immediate response may reinforce perceptions that fuel treatments are disruptive of a delicate balance supporting wildlife and their habitat. A longer, intermediate-term response, however, may provide important information regarding the resiliency of forest food webs to different treatments that approximate or depart from historic disturbances to which wildlife are adapted.

Science and management information from this project has and will continue to be presented to the general public, and education and management organizations. This research will benefit USDA Forest Service fire and land management personnel through presentations and reports as well as researchers at the Pacific Southwest Research Station, University of California Davis , and other academic and research institutions.

map of the Sierra Nevada Ecoregion


Our primary study is located at the Teakettle Experimental Forest in the southern Sierra Nevada (Sierra National Forest; 1800-2400 m elev., 36°58’ N latitude and 119°2’ W longitude). Other research (e.g., fire effects on truffle biodiversity) is located various areas of Yosemite National Park .

Lead Scientists/Collaborators

1) Meyer, M.; 1.)North, M.; 2.)Kelt, D.

1) USDA Forest Service, PSW Research Station
Sierra Nevada Research Center
Department of Environmental Horticulture
One Shields Ave.
University of California
Davis, CA 95528
ph: (530) 754-7398
fax: (530) 752-1819

2) Department of Wildlife, Fish, and Conservation Biology,
University of California-Davis

Publications and Reports

Meyer, M. D., D. A. Kelt, and M. North. Microhabitat associations of northern flying squirrels in burned and thinned forest stands of the Sierra Nevada. Accepted pending minor revision in American Midland Naturalist.

Meyer, M. D., M. P. North, and D. A. Kelt. Nest trees of northern flying squirrels in Yosemite National Park. In press in The Southwestern Naturalist.

Meyer, M. D., M. North, and D. A. Kelt. 2005. Short-term effects of fire and forest thinning on truffle abundance and consumption in the southern Sierra Nevada of California. Canadian Journal of Forest Research 35:1061-1070.

Meyer, M. D., D. A. Kelt, and M. North. 2005. Fungi in the diets of northern flying squirrels and lodgepole chipmunks in the Sierra Nevada. Canadian Journal of Zoology 83:1581-1589.

Meyer, M. D., D. A. Kelt, and M. North. 2005. Nest tree ecology of northern flying squirrels in the southern Sierra Nevada. Journal of Mammalogy 86:275-280.

Meyer, M. D., and M. North. 2005. Truffle abundance in riparian and upland forests of California’s southern Sierra Nevada. Canadian Journal of Botany 83:1015-1020.

Izzo, A. D., M. D. Meyer, J. M. Trappe, M. North, and T. Bruns. 2005. Hypogeous ectomycorrhizal fungal species on roots and in small mammal diet in a mixed-conifer forest. Forest Science 51:243-254.

North, M., B. Oakley, J. Chen, H. Erickson, A. Gray, A. Izzo, D. Johnson, S. Ma, J. Marra, M. D. Meyer, K. Purcell, T. Rambo, D. Rizzo, B. Roath, and T. Schowalter. 2002. Vegetation and ecological characteristics of mixed conifer and red fir forests at Teakettle Experimental Forest. U. S. Forest Service PSW-General Technical Report PSW-GTR-186.

Meyer, M. D., D. A. Kelt, and M. North. Short-term effects of burning and thinning on the abundance of lodgepole chipmunks (Neotamias speciosus) in the Sierra Nevada of California. In prep.

Last Modified: Aug 29, 2016 10:57:28 AM