USDA Forest Service

Pacific Southwest Research Station


Pacific Southwest Research Station
800 Buchanan Street
West Annex Building
Albany, CA 94710-0011

(510) 559-6300

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.

Programs and Projects


Ecology and Management of Western Forests Influenced by Mediterranean Climate

Photo of Eric Knapp

Eric E Knapp
Research Ecologist
Employee E-mail Address Image
Phone: (530) 226-2555

USDA, Forest Service
Pacific Southwest Research Station

3644 Avtech Parkway
Redding, CA 96002
Ph: (530) 226-2530
Fx: (530) 226-5091

B.A. Biology, U.C. Santa Barbara (1985)
M.S. Agronomy, U.C. Davis (1988)
Ph.D. Genetics (emphasis: population genetics, plant ecology, plant population biology), U.C. Davis (1992)

Research Interests/Duties

My current research is focused on forest ecology in relation to disturbance, particularly fire. I am interested in understanding changes that have occurred in the absence of fire and as forests have recovered from past logging disturbance, and the effect of these changes on forest resilience to fire, climate change, and other disturbances. I use historical information from photographs, old vegetation plots, and fire scars as a means of understanding the extent, severity, and frequency of past disturbance, as well as studies of areas with intact or near-intact fire regimes. Both can provide important lessons for the management of our forests today.

Other interests include understanding the ecological effects and fire behavior implications of different forest and fuel management practices, the ability of fuel treatments (mechanical and prescribed fire) to emulate natural disturbance, the effect of fire on the habitat of plant and animal species, and the effect of prescribed fire season.

Additional duties:

  • Manager, 1700 acre Stanislaus-Tuolumne Experimental Forest on the Stanislaus National Forest.
  • Member, Dry Forest Workgroup for the northern spotted owl recovery plan.

Current Emphases, Studies, Projects
  • Long-term forest change with recovery from logging in absence of fire, Stanislaus-Tuolumne Experimental Forest. We are investigating changes to the overstory, understory, and stand spatial structure that have occurred since prior to logging in three recently rediscovered plots from a "Methods of Cutting" study established in 1929. By reconstructing what forests used to look like, we hope to shed light on how historical structure affected biodiversity and resilience to fire. For more information: Viewing forests through a historical lens: past records on fire resilient, biodiverse stands could offer models for the future. Science Perspectives, Fall 2009.
  • Variable Density Thinning study, Stanislaus-Tuolumne Experimental Forest. We are evaluating the influence of stand spatial structure and prescribed fire on small mammals, birds, tree regeneration, tree growth, and understory diversity. This study will compare a new thinning prescription designed to produce a highly diverse structure with a prescription where trees are thinned more evenly. The ultimate goal is to investigate new means of achieving multiple forest management objectives, from fuel reduction to habitat creation for multiple species.
  • Large tree health following thinning and prescribed fire, Stanislaus-Tuolumne Experimental Forest. Long-term exclusion of fire threatens the long-term health of large pines by allowing new trees to establish that compete with the larger trees for water. The build-up of fuels at the base of these large trees also means that mortality after a prescribed fire may now be substantial. We will be investigating different strategies for reintroducing fire after thinning competing young trees, on the survival and vigor of large legacy pines.
  • Fire severity patterns in the Klamath Mountains. We are investigating the relative contribution of various topographic, weather, and fuel variables on patterns of fire severity using satellite remote sensing data and statistical models. Our goal is to be able to predict effects to the landscape and habitat to key species, such as the northern spotted owl, of fire burning under different conditions.
  • Variable Retention Salvage study, Blacks Mountain Experimental Forest. We are studying how the volume of removal (amount of salvage or disturbance) after a stand replacing fire affects native and exotic species cover and diversity. Treatments being compared range from 100% of the stand basal salvaged to no salvage, in 25% increments.
  • Fire and Fire Surrogate study – Southern Cascades site, Goosenest Adaptive Management Area, Klamath National Forest. Ecological effects of mechanical thinning with and without prescribed fire are being compared to unthinned plots and plots where fire was introduced without prior mechanical treatment, to determine the extent to which mechanical disturbance can emulate fire.
  • Balancing fuel reduction, soil exposure, and potential for erosion, Lake Tahoe Basin. Pattern of soil exposure is being evaluated for different mastication and prescribed fire treatments under different soil moisture conditions, and the effect of pattern of soil exposure on soil erosion is being tested with erosion simulators. Outside partners: Drs. Andrew Stubblefield and J. Morgan Varner, Humboldt State University.
  • Effect of fire on a rare orchid, Modoc National Forest. Whether Cypripedium montanum can be maintained when fire is reintroduced after a long period of exclusion, and mechanisms by which this and other species survived and/or benefited from fire historically, are being studied using demographic surveys in plots either subject to a prescribed burn or not.
  • Fire behavior, fire effects, and vegetation recovery after mechanical mastication treatments. Ladder fuels (shrubs and small trees) without commercial value or at the wildland urban interface (WUI) are increasingly being managed by mastication (chipping, with chips dispersed on the forest floor). We evaluated fuel characteristics at ten sites and conducted prescribed burns at two (and in the laboratory) in order to better understand fire behavior, soil heating, and fire effects. Partners: Outside partner: Dr. J. Morgan Varner, Humboldt State University. Masticated Fuels Research web page

Selected Publications

Kane, J., J.M. Varner, and E.E. Knapp, and R.F. Powers.  2010. Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest. Applied Vegetation Science 13:207-220.

Matt D. Busse, Carol J. Shestak, Ken R. Hubbert, and Eric E. Knapp. 2010. Soil Physical Properties Regulate Lethal Heating during Burning of Woody Residues. Soil Sci Soc Am J 2010 74: 947-955.

Knapp, E.E., B.L. Estes, and C.N. Skinner. 2009. Ecological effects of prescribed fire season: a literature review and synthesis for managers. Gen. Tech. Rep. PSW-GTR-224. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 80 p.

Kane, J., J.M. Varner, and E.E. Knapp. 2009. Novel fuelbed characteristics associated with mechanical mastication treatments in northern California and southwestern Oregon. International J. Wildland Fire 18:686-697.

Schwilk, D.W., J.E Keeley, E.E. Knapp, J. McIver, J.D. Bailey, C.J. Fettig, C.E. Fiedler, R.J. Harrod, J.J. Moghaddas, K.W. Outcalt, C.N. Skinner, S.L. Stephens, T.A. Waldrop, D.A. Yaussy, and A. Youngblood. 2009. The national Fire and Fire Surrogate study: effects of fuel reduction methods on forest vegetation structure and fuels. Ecological Applications 19:285-304.

S.L. Stephens, J.J. Moghaddas, C. Edminster, C.E. Fiedler, S. Haase, M. Harrington, J.E. Keeley, E.E. Knapp, J.D. McIver, K. Metlen, C.N. Skinner, and A. Youngblood. 2009. Fire treatment effects on vegetation structure, fuels, and potential fire severity in western U.S. forests. Ecological Applications 19:305-320.

Miller, J.D., E.E. Knapp, C.H. Key, C.N. Skinner, C. Isbell, M. Creasy, and J. Sherlock. 2009. Calibration and validation of the relative differenced Normalized Burn Ratio (RdNBR) to three measures of fire severity in the Sierra Nevada and Klamath Mountains, California, USA. Remote Sensing of Environment 113:645-656.

Rabin, L.A.; W.W. Oliver, R.F. Powers, M.W. Ritchie, M.D. Busse, and E.E. Knapp. 2009. Historical growth plots in the Pacific Southwest. Gen. Tech. Rep. PSW-GTR-213. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 83 p.

E.E. Knapp, and K.J. Rice. 2009. Effects of competition and temporal variation on the evolutionary potential of two native bunchgrass species . Restoration Ecology, Early View (Article online in advance of print), published Online: July 1, 2009. doi: 10.1111/j.1526-100X.2009.00552.x

Rice, K.J., and E.E. Knapp. 2008. Effects of competition and life history stage on the expression of local adaptation in two native bunchgrasses. Restoration Ecology 16(1):12-23.

Hamman, S.T., I.C. Burke, and E.E. Knapp. 2008. Soil nutrients and microbial activity after early and late season prescribed burns in a Sierra Nevada mixed conifer forest. Forest Ecology and Management 256:367-374.

Knapp, E.E. D.W. Schwilk, J.M. Kane, and J.E. Keeley. 2007. Role of burning season on initial understory vegetation response to prescribed fire in a mixed conifer forest. Can. J. For. Res. 37: 11-22 (2007).

Youngblood, Andrew; Bigler-Cole, Heidi; Fettig, Christopher J.; Fiedler, Carl; Knapp, Eric E.; Lehmkuhl, John F.; Outcalt, Kenneth W.; Skinner, Carl N.; Stephens, Scott L.; Waldrop, Thomas A. 2007. Making fire and fire surrogate science available: a summary of regional workshops with clients. Gen. Tech. Rep. PNW-GTR-727. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 59 p.

Busse, M., C. Shestak, E. Knapp, G. Fiddler, and K. Hubbert. 2006. Lethal soil heating during burning of masticated fuels: effects of soil moisture and texture. Proceedings of the Third International Fire Ecology and Management Congress, Nov. 13-17, San Diego , CA.

Ferrenberg S. M. , D.W. Schwilk, E.E. Knapp, E. Groth, and J.E. Keeley. 2006. Fire decreases arthropod abundance but increases diversity: early and late seasson prescribed fire effects in a Sierra Nevada mixed-conifer forest. Fire Ecology 2 (2): 79-101.

Kane, J. M., E.E. Knapp, and J. M. Varner. 2006. Variability in loading of mechanically masticated fuel beds in northern California and southwestern Oregon. In Andrews, P.L., and Butler , B.W., comps., Fuel Management-How to Measure Success: Conference Proceedings, March 28-30, 2006 , Portland OR . U.S.D.A. Forest Service, Proceedings RMRS-P-41, pages 341-350.

Kane, J., J.M. Varner, and E. Knapp. 2006. Initial Understory Vegetation Response to Mechanical Mastication Fuel Treatments: Balancing Biodiversity and Fire Hazard Reduction. Proceedings of the Third International Fire Ecology and Management Congress, Nov. 13-17, San Diego, CA.

Knapp, E., M.Busse, J. Morgan Varner III, C. Skinner, and R. Powers. 2006. Behavior and short-term effects of fire in masticated fuel beds. Proceedings of the Third International Fire Ecology and Management Congress, Nov. 13-17, San Diego, CA.

Knapp, E. E.,and J. E. Keeley. 2006. Heterogeneity in fire severity with early season and late season prescribed burns in a mixed conifer forest. International Journal of Wildland Fire.15:37-45.

Schwilk, D.W., E. E. Knapp, S.M. Ferrenberg, J.E. Keeley, and A.C. Caprio. 2006. Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed conifer forest. Forest Ecology and Management 232: 36-45

Knapp, E. E., J.E. Keeley, E. A. Ballenger, and T. J. Brennan. 2005. Fuel reduction and coarse woody debris dynamics with early season and late season prescribed fires in a Sierra Nevada mixed conifer forest. Forest Ecology and Management 208:383-397.

Youngblood, A., K. L. Metlen, E. E. Knapp, K. W. Outcalt, S. L. Stephens, T. A. Waldrop, and D. Yaussy. Implementation of the Fire and Fire Surrogate Study-A national research effort to evaluate the consequences of fuel reduction treatments. In: C. E. Peterson, and D. A. Maguire, eds., Balancing Ecosystem Values: Innovative Experiments for Sustainable Forestry, Proceedings of the International Union of Forest Research Organizations workshop. General Technical Report PNW-GTR-635. Pgs. 315-321.

Knapp, E. E., S. L. Stephens, J. D. McIver, J. J. Moghaddas, and J. E. Keeley. 2004. The Fire and Fire Surrogate study in the Sierra Nevada: Evaluating restoration treatments at Blodgett Experimental Forest and Sequoia National Park. In Proceedings of the Sierra Science Symposium, Oct. 8-10, 2002, Kings Beach, CA (eds. D.D. Murphy and P.A. Stine), pp. 79-86. General Technical Report PSW-GTR-193. USDA Forest Service, Pacific Southwest Research Station, Albany CA.

Other Publications by Eric Knapp*

Knapp, E. E., M. A. Goedde, and K. J. Rice. 2001. Pollen limited reproduction in blue oak: implications for wind-pollination in fragmented landscapes. Oecologia 128:48-55.

Rice, K. J., and E. E. Knapp. 2000. Evolutionary factors affecting the probability of local adaptation or should we expect to see ecotypes behind every rock? In J. E. Keeley, M. Baer-Keeley, and C. J. Fotheringham (eds.) 2 nd interface between ecology and land development in California. U.S. Geological Survey Open-File Report 00-62.

Knapp, E. E., and P. G. Connors. 1999. Genetic consequences of a single-founder population bottleneck in Trifolium amoenum (Fabaceae). American Journal of Botany 86: 124-130.

Knapp, E. E. and K. J. Rice. 1998. Comparison of isozymes and quantitative traits for evaluating patterns of genetic variation in purple needlegrass (Nassella pulchra). Conservation Biology 12:1031-1041.

Knapp, E. E. and A. R. Dyer. 1997. When do genetic considerations require special approaches to ecological restoration? Pages 345-363 in P. L. Fiedler, and P. Kareiva (eds.) Conservation Biology for the Coming Decade, 2nd edition. Chapman and Hall, New York, New York.

Knapp, E. E. and K. J. Rice. 1996. Genetic structure and gene flow in Elymus glaucus: implications for native grassland restoration. Restoration Ecology 4:1-10.

Knapp, E. E. and K. J. Rice. 1994. Starting from seed: Genetic issues in using native grasses for restoration. Restoration and Management Notes 12(1):40-45.

*Due to policy or copyright restrictions, we are unable to provide full-text versions of these publications. Please check with your local library or contact Eric Knapp to inquire about reprints.

Last Modified: Feb 1, 2010 01:49:52 PM