Current Research

• 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.
• 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. A new thinning prescription designed to produce a highly diverse structure is being compared 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 are investigating how different strategies for reintroducing fire after thinning affects 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.

Research Interests

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.

Past Research

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. Outside partner: Dr. J. Morgan Varner, Humboldt State University. Masticated Fuels Research web page

Education

• University of California, Ph.D. Genetics, emphasis population genetics, plant ecology, plant population biology 1992
• University of California, M.S. Agronomy 1988
• University of California, B.A. Biology 1985

Publications

• Ziegler, Justin P.; Hoffman, Chad M.; Collins, Brandon M.; Knapp, Eric E.; Mell, William (Ruddy). 2021. Pyric tree spatial patterning interactions in historical and contemporary mixed conifer forests, California, USA.
• Knapp, Eric E.; Bernal, Alexis A.; Kane, Jeffrey M.; Fettig, Christopher J.; North, Malcolm P. 2021. Variable thinning and prescribed fire influence tree mortality and growth during and after a severe drought.
• Reed, Warren P.; Varner, J. Morgan; Knapp, Eric E.; Kreye, Jesse K. 2020. Long-term changes in masticated woody fuelbeds in northern California and southern Oregon, USA.
• Knapp, Eric E.; Carlson, Robert L.; North, Malcolm P.; Lydersen, Jamie L.; Collins, Brandon M. 2020. Restoring forest heterogeneity with thinning and prescribed fire: Initial results from the central Sierra Nevada, California.
• Collins, Brandon M.; Miller, Jay D.; Knapp, Eric E.; Sapsis, David B. 2019. A quantitative comparison of forest fires in central and northern California under early (1911 1924) and contemporary (2002 2015) fire suppression.
• Zhang, Jianwei ; Finley, Kaelyn A.; Knapp, Eric E. 2019. Resilience of a ponderosa pine plantation to a backfiring operation during a mid-summer wildfire.
• Pawlikowski, Natalie C.; Coppoletta, Michelle ; Knapp, Eric ; Taylor, Alan H. 2019. Spatial dynamics of tree group and gap structure in an old-growth ponderosa pine-California black oak forest burned by repeated wildfires.
• North, Malcolm P.; Stevens, Jens T.; Greene, David F.; Coppoletta, Michelle ; Knapp, Eric E.; Latimer, Andrew M.; Restaino, Christina M.; Tompkins, Ryan E.; Welch, Kevin R.; York, Rob A.; Young, Derek J.N.; Axelson, Jodi N.; Buckley, Tom N.; Estes, Becky L.; Hager, Rachel N.; Long, Jonathan W.; Meyer, Marc D.; Ostoja, Steven M.; Safford, Hugh D.; Shive, Kristen L.; Tubbesing, Carmen L.; Vice, Heather ; Walsh, Dana ; Werner, Chhaya M.; Wyrsch, Peter . 2019. Tamm Review: Reforestation for resilience in dry western U.S. forests.
• Stephens, Scott L; Collins, Brandon M; Fettig, Christopher J; Finney, Mark A; Hoffman, Chad M; Knapp, Eric E; North, Malcolm P; Safford, Hugh; Wayman, Rebecca B. 2018. Drought, tree mortality, and wildfire in forests adapted to frequent fire.
• Slack, Andrew; Kane, Jeffrey; Knapp, Eric; Sherriff, Rosemary. 2017. Contrasting impacts of climate and competition on large sugar pine growth and defense in a fire-excluded forest of the Central Sierra Nevada.
• Knapp, Eric E.; Lydersen, Jamie M.; North, Malcolm P.; Collins, Brandon M. 2017. Efficacy of variable density thinning and prescribed fire for restoring forest heterogeneity to mixed-conifer forest in the central Sierra Nevada, CA.
• Estes, Becky L.; Knapp, Eric E.; Skinner, Carl N.; Miller, Jay D.; Preisler, Haiganoush K. 2017. Factors influencing fire severity under moderate burning conditions in the Klamath Mountains, northern California, USA.
• Stevens, Jens T.; Safford, Hugh D.; North, Malcolm P.; Fried, Jeremy S.; Gray, Andrew N.; Brown, Peter M.; Dolanc, Christopher R.; Dobrowski, Solomon Z.; Falk, Donald A.; Farris, Calvin A.; Franklin, Jerry F.; Fulé, Peter Z.; Hagmann, R. Keala; Knapp, Eric E.; Miller, Jay D.; Smith, Douglas F.; Swetnam, Thomas W.; Taylor, Alan H.; Jones, Julia A. 2016. Average stand age from forest inventory plots does not describe historical fire regimes in ponderosa pine and mixed-conifer forests of western North America.
• Harrison, Nicolas M.; Stubblefield, Andrew P.; Varner, J. Morgan; Knapp, Eric E. 2016. Finding balance between fire hazard reduction and erosion control in the Lake Tahoe Basin, California Nevada.
• Sollmann, R.; White, Angela; Tarbill, Gina; Manley, Patricia; Knapp, Eric E. 2016. Landscape heterogeneity compensates for fuel reduction treatment effects on Northern flying squirrel populations.
• Knapp, Eric E.; Ritchie, Martin W. 2016. Response of understory vegetation to salvage logging following a high-severity wildfire.
• Kreye, Jesse K.; Varner, J. Morgan; Kane, Jeffrey M.; Knapp, Eric E.; Reed, Warren P. 2016. The impact of aging on laboratory fire behaviour in masticated shrub fuelbeds of California and Oregon, USA.
• Knapp, Eric E. 2015. Long-term dead wood changes in a Sierra Nevada mixed conifer forest: habitat and fire hazard implications.
• Lydersen, Jamie M.; Collins, Brandon M.; Knapp, Eric E.; Roller, Gary B.; Stephens, Scott. 2015. Relating fuel loads to overstorey structure and composition in a fire-excluded Sierra Nevada mixed conifer forest.
• Ritchie, Martin W.; Knapp, Eric E. 2014. Establishment of a long-term fire salvage study in an interior ponderosa pine forest.
• Cocking, Matthew I.; Varner, J. Morgan; Knapp, Eric E. 2014. Long-term effects of fire severity on oak conifer dynamics in the southern Cascades.
• van Mantgem, Phillip J.; Nesmith, Jonathan C.B.; Keifer, MaryBeth; Knapp, Eric E.; Flint, Alan; Flint, Lorriane. 2013. Climatic stress increases forest fire severity across the western United States.
• Knapp, Eric E.; Skinner, Carl N.; North, Malcolm P.; Estes, Becky L. 2013. Long-term overstory and understory change following logging and fire exclusion in a Sierra Nevada mixed-conifer forest.
• Ryan, Kevin C.; Knapp, Eric E.; Varner, J. Morgan. 2013. Prescribed fire in North American forests and woodlands: history, current practice, and challenges.
• Lydersen, Jamie M.; North, Malcolm P.; Knapp, Eric E.; Collins, Brandon M. 2013. Quantifying spatial patterns of tree groups and gaps in mixed-conifer forests: reference conditions and long-term changes following fire suppression and logging.
• Ritchie, Martin W.; Knapp, Eric E.; Skinner, Carl N. 2013. Snag longevity and surface fuel accumulation following post-fire logging in a ponderosa pine dominated forest.
• Knapp, E.; North, M.; Benech, M.; Estes, B. 2012. Chapter 12: The variable-density thinning study at Stanislaus-Tuolumne Experimental Forest.
• McIver, James D.; Stephens, Scott L.; Agee, James K.; Barbour, Jamie; Boerner, Ralph E. J.; Edminster, Carl B.; Erickson, Karen L.; Farris, Kerry L.; Fettig, Christopher J.; Fiedler, Carl E.; Haase, Sally; Hart, Stephen C.; Keeley, Jon E.; Knapp, Eric E.; Lehmkuhl, John F.; Moghaddas, Jason J.; Otrosina, William; Outcalt, Kenneth W.; Schwilk, Dylan W.; Skinner, Carl N.; Waldrop, Thomas A.; Weatherspoon, C. Phillip; Yaussy, Daniel A.; Youngblood, Andrew; Zack, Steve. 2012. Ecological effects of alternative fuel-reduction treatments: highlights of the National Fire and Fire Surrogate study (FFS).
• Stephens, Scott L.; Boerner, Ralph E. J.; Moghaddas, Jason J.; Moghaddas, Emily E. Y.; Collins, Brandon M.; Dow, Christopher B.; Edminster, Carl; Fiedler, Carl E.; Fry, Danny L.; Hartsough, Bruce R.; Keeley, Jon E.; Knapp, Eric E.; McIver, James D.; Skinner, Carl N.; Youngblood, Andrew. 2012. Fuel treatment impacts on estimated wildfire carbon loss from forests in Montana, Oregon, California, and Arizona.
• Kreye, Jesse K.; Varner, J.Morgan; Knapp, Eric E. 2012. Moisture desorption in mechanically masticated fuels: effects of particle fracturing and fuelbed compaction.
• Miller, Jay D.; Skinner, Carl N.; Safford, Hugh D.; Knapp, Eric E.; Ramirez, Carlos M. 2012. Northwest California National Forests fire severity monitoring 1987-2008.
• Estes, Becky L.; Knapp, Eric E.; Skinner, Carl N.; Uzoh, Fabian C. C. 2012. Seasonal variation in surface fuel moisture between unthinned and thinned mixed conifer forest, northern California, USA.
• Knapp, Eric E.; Weatherspoon, Phillip C.; Skinner, Carl N. 2012. Shrub seed banks in mixed conifer forests of northern California and the role of fire in regulating abundance.
• Miller, J. D.; Skinner, Carl; Safford, H. D.; Knapp, Eric E.; Ramirez, C. M. 2012. Trends and causes of severity, size, and number of fires in northwestern California, USA.
• Knapp, Eric; Varner, J. Morgan; Busse, Matt; Skinner, Carl; Shestak, Carol. 2011. Behaviour and effects of prescribed fire in masticated fuelbeds.
• Kreye, Jesse K.; Varner, J. Morgan; Knapp, Eric E. 2011. Effects of particle fracturing and moisture content on fire behaviour in masticated fuelbeds burned in a laboratory.
• Van Mantgem, Phillip J.; Stephenson, Nathan L.; Knapp, Eric; Barrles, John; Keeley, Jon E. 2011. Long-term effects of prescribed fire on mixed conifer forest structure in the Sierra Nevada, California.
• Busse, Matt; Shestak, Carol; Hubbert, Ken; Knapp, Eric. 2010. Soil physical properties regulate lethal heating during burning of woody residues.
• Spies, Thomas A.; Miller, Jay D.; Buchanan, Joseph B.; Lehmkuhl, John F.; Franklin, Jerry F.; Healey, Sean P.; Hessburg, Paul F.; Safford, Hugh D.; Cohen, Warren B.; Kennedy, Rebecca S.H.; Knapp, Eric E.; Agee, James K.; Moeur, Melinda. 2010. Underestimating risks to the northern spotted owl in fire-prone forests: response to Hanson et al.
• Kane, Jeffrey M.; Varner, J. Morgan; Knapp, Eric E. 2010. Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest.
• Miller, Jay D.; Knapp, Eric E.; Key, Carl H.; Skinner, Carl N.; Isbell, Clint J.; Creasy, R. Max; Sherlock, Joseph W. 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.
• Knapp, Eric E.; Estes, Becky L.; Skinner, Carl N. 2009. Ecological effects of prescribed fire season: a literature review and synthesis for managers.
• Stephens, Scott L.; Moghaddas, Jason J.; Edminster, Carl; Fiedler, Carl E.; Haase, Sally; Harrington, Michael; Keeley, Jon E.; Knapp, Eric E.; McIver, James D.; Metlen, Kerry; Skinner, Carl N.; Youngblood, Andrew. 2009. Fire treatment effects on vegetation structure, fuels, and potential fire severity in western U.S. forests.
• Rabin, Lawrence A.; Oliver, William W.; Powers, Robert F.; Ritchie, Martin W.; Busse, Matt D.; Knapp, Eric E. 2009. Historical growth plots in the Pacific Southwest.
• Kane, Jeffrey M.; Varner, J. Morgan; Knapp, Eric E. 2009. Novel fuelbed characteristics associated with mechanical mastication treatments in northern California and south-western Oregon, USA.
• Schwilk, Dylan W.; Keeley, Jon E.; Knapp, Eric E.; Mciver, James; Bailey, John D.; Fettig, Christopher J.; Fiedler, Carl E.; Harrod, Richy J.; Moghaddas, Jason J.; Outcalt, Kenneth W.; Skinner, Carl N.; Stephens, Scott L.; Waldrop, Thomas A.; Yaussy, Daniel A.; Youngblood, Andrew. 2009. The national Fire and Fire Surrogate study: effects of fuel reduction methods on forest vegetation structure and fuels.
• Parks, Noreen; Knapp, Eric. 2009. Viewing forests through a historical lens.
• Kevin J. , Rice; Eric E., Knapp. 2008. Effects of competition and life history stage on the expression of local adaptation in two native bunchgrasses.
• Hamman, Sarah T.; Burke, Ingrid C.; Knapp, Eric E. 2008. Soil nutrients and microbial activity after early and late season prescribed burns in a Sierra Nevada mixed conifer forest.
• 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.
• Knapp, Eric E.; Schwilk, Dylan W.; Kane, Jeffrey M.; Keeley, Jon E. 2007. Role of burning season on initial understory vegetation response to prescribed fire in a mixed conifer forest.
• Ferrenberg, Scott M.; Schwilk, Dylan W.; Knapp, Eric E.; Groth, Eric; Keeley, Jon E. 2006. Fire decreases arthropod abundance but increases diversity: early and late season prescribed fire effects in a Sierra Nevada mixed-conifer forest.
• Knapp, Eric E.; Keeley, Jon E. 2006. Heterogeneity in fire severity with early season and late season prescribed burns in a mixed conifer forest.
• Schwilk, Dylan W.; Knapp, Eric E.; Ferrenberg, Scott M.; Keeley, Jon E.; Caprio, Anthony. 2006. Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed conifer forest.
• Kane, Jeffrey M.; Knapp, Eric E.; Varner, J. Morgan. 2006. Variability in Loading of Mechanically Masticated Fuel Beds in Northern California and Southwestern Oregon.
• Knapp, Eric E.; Keeley, Jon E.; Ballenger, Elizabeth A.; Brennan, Teresa J. 2005. Fuel reduction and coarse woody debris dynamics with early season and late season prescribed fires in a Sierra Nevada mixed conifer forest.
• Youngblood, Andrew; Metlen, Kerry L.; Knapp, Eric E.; Outcalt, Kenneth W.; Stephens, Scott L.; Waldrop, Thomas A.; Yaussy, Daniel. 2005. Implementation of the fire and fire surrogate study a national research effort to evaluate the consequences of fuel reduction treatments.
• Knapp, Eric E.; Stephens, Scott L.; McIver, James D.; Moghaddas, Jason J.; Keeley, Jon E. 2004. Fire and fire surrogate study in the Sierra Nevada: evaluating restoration treatments at Blodgett Forest and Sequoia National Park.

Research Highlights

Highlight	Title	Year
PSW-2011-12	How well will mastication reduce fire hazard Mechanical mastication of standing shrubs and small trees is widely used as a method to reduce fire hazard. The resulting fuelbeds are poorly r ...	2011
PSW-2017-173	New study finds post-wildfire recovery of understory vegetation is little affected by salvage logging After the 2002 Cone Fire burned into the Blacks Mountain Experimental Forest on the Lassen National Forest in northeastern California, scientist ...	2017
PSW-2012-22	Wildfire Can Benefit Landscapes and Reduce Threats to Local Communities Scientists determine that managing wildfire across large portions of Sierra Nevada forests may alleviate the current hazardous fuels problem tha ...	2012