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

Teakettle Ecosystem Study: Fire and thinning effects on mixed conifer ecosystem structure and function

Study Plan
Research Project Summary

The Research

Teakettle cabinAfter a century of fire suppression, thinning and prescribed fire are widely used to restore Sierran forests. Managers, however, have little information about the comparative effects of these treatments and their combination on ecosystem response or forest health. Does mechanical timber harvesting mimic the ecological effects of the natural fire disturbance regime, and if it does not, what ecosystem functions and processes are being altered and what are the consequences of these changes? Using 18 replicated four ha plots, two level of burning (no burn and prescribed fire) and three levels of thinning (no thin, understory thinning, overstory thinning) will be applied in a full factorial design. Pre-treatment data has been collected for 2-3 years. Fire and thinning treatments were completed in November of 2001. For 3 years post-treatment ecosystem response was assessed with 17 concurrent studies, many of which have coordinating sampling and data collection protocol to facilitate interdisciplinary analysis.


Teakettle plot after burn and cut treatment
blue arrrowTo assess how widely used restoration methods, prescribed fire and thinning, affect ecosystem structure, composition and function.
blue arrrowTo understand disturbance and successional dynamics in Sierra forests.
blue arrrowTo assess how energy, nutrient, water flows and trophic structure are affected by treatments.
blue arrrowTo evaluate mixed-conifer 'health' following 6 restoration treatments.

Methods and Design

The design is a full factorial crossing that combined burn/no burn with three levels of thinning (none, understory and overstory). Each of the six treatments (including the control) was replicated 3 times on 18 four ha plots. All plots were carefully selected to have no significant difference in forest structure or soil conditions before treatments. In each plot, a sample grid was mapped and permanently marked so that all studies would have common sample points to facilitate cross discipline data analysis and study integration. In 6 of the plots, one of each treatment, grip pointswere established on a 25 by 25 m spacing (n=49) to facilitate more intensive, spatial analysis. In 12 of the plots, grid points were established on a 50 by 50 m spacing for a total gridpoint network of 402 sample points. All studies sampled conditions for their study (ex. understory plants, soil respiration, nutrients, etc.) for 2-3 years before treatments and for 3 years after treatments.

Application of Research Results

Results should have direct relevance to forest management in the Sierra Nevada following a century of fire suppression. Forest health has been set as a goal for restoration treatments. Although the term may be vague, a better understanding of ecosystem structure, composition and functional response to restoration treatments would certainly help assess forest response. Beside the publications listed below, a film and interactive DVD is being produced to communicate results with forest managers, students and the public.

photo of Teakettle plot map

map of the Sierra Nevada Ecoregion


Old growth mixed-conifer forests of the Teakettle Experimental Forest, 80 km east of Fresno at 2200 m elevation.

Lead Scientists/Collaborators

1) North, M. 26 collaborators from 12 institutions.

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

Publications and Reports

Izzo, A., M. Meyer, J. 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(3).

Marra, J. and R. Edmonds. 2005. Soil Arthropod Responses to Different Patch Types in a Mixed Conifer Forest of the Sierra Nevada. Forest Science 51(3).

Schowalter, T. and Y. Zhang. 2005. Canopy arthropod assemblages in four overstory and three understory plant species in mixed-conifer old-growth forest in California. Forest Science 51(3).

Erickson, H., P. Soto, D. Johnson, B. Roath, and C. Hunsaker. 2005. Effects of Vegetation Patches on Soil Nutrient Pools and Fluxes within a Mixed-Conifer Forest. Forest Science 51(3).

A. Gray, H. Zald, R. Kern, and M. North. 2005. Stand conditions associated with tree regeneration in Sierran mixed-conifer forests. Forest Science 51(3).

Ma, S., J. Chen, J. Butnor, M. North, E. Euskirchen, B. Oakley. 2005. Biophysical Controls on Soil Respiration in the Dominant Patch Types of an Old-Growth, Mixed-Conifer Forest. Forest Science 51(3).

Smith, T., D. Rizzo and M. North. 2005. Patterns of Mortality in an Old-Growth Mixed-Conifer Forest of the Southern Sierra Nevada, California. Forest Science 51(3).

North, M., M. Hurteau, R. Fiegener, and M. Barbour. 2005. Influence of fire and El Nino on tree recruitment varies by species in Sierran mixed conifer. Forest Science 51(3).

Meyer, M., D. Kelt, and M. North. In press. Nest trees of northern flying squirrels in the Sierra Nevada. Canadian Journal of Mammalogy.

Meyer, M., M. North and D. Kelt. In press. Short-term effects of fire and forest thinning on truffle abundance and consumption in the southern Sierra Nevada of California. C.J.F.R.

Izzo, A., J. Agbowo, T. Bruns. 2005. Detection of plot-level changes in ectomycorrhizal communities across years in an old-growth mixed-conifer forest. New Phytol.

Concilio, A., S. Ma, Q. Li, J. LeMoine, J. Chen, M. North, D. Moorhead, and R. Jensen. In press. Soil respiration response to prescribed burning and thinning in mixed conifer and hardwood forests. C.J.F.R.

North, M., B. Oakley, R. Fiegener, A. Gray and M. Barbour. In press. Influence of light and soil moisture on Sierran mixed-conifer understory communities. Plant Ecology.

Oakley, B., M. North, J. Franklin, B. Hedlund, and J. Staley. 2004. Diversity and distribution of Frankia strains symbiotic with Ceanothus in California. Applied and Environmental Microbiology 70: 6444-6452.

North, M., J. Chen, B. Oakley, B. Song, M. Rudnicki, and A. Gray. 2004. Forest stand structure and pattern of old-growth western hemlock/Douglas-fir and mixed-conifer forest. Forest Science 50 (3):299-311.

Ma, S., J. Chen, M. North, H. Erickson, M. Bresee, and J. Le Moine. 2004. Short-term effects of experimental treatments on soil respiration in an old-growth, mixed-conifer forest. Env. Man. 33(1): 148-159.

Maloney, P. E., and D. M Rizzo. 2002. Dwarf mistletoe-host interactions in mixed-conifer forests in the Sierra Nevada. Phytopathology 92:597-602.

Oakley B, North M, Franklin J. 2003 The effects of fire on soil nitrogen associated with patches of the actinorhizal shrub Ceanothus cordulatus. Plant and Soil 254:35-46.

North, Malcolm P. 2002. The Teakettle Experiment. pp 47-54 in Jared Verner (tech. editor). Proceedings of a Symposium on the Kings River Sustainable Forest Ecosystems Project: Progress and Current Status. USDA Forest Service, Pacific Southwest Research Station Gen. Tech. Rep. PSW-GTR-183.

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

Last Modified: Jun 13, 2016 04:03:25 PM