Sierra Nevada Science Symposium 2002: Science for Management and Conservation

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POSTER SESSION: Fire/Physical Processes
Abstracts for each of the posters can be viewed below by clicking on the title of the poster.




Measuring the Effectiveness of Fuel Treatments in Changing Fire Behavior and Effects During Wildfires
Jo Ann Fites-Kaufman
, USDA Forest Service, Adaptive Management Services Enterprise Team, Tahoe National Forest, 631 Coyote Street, Nevada City, CA 95959; email: jfites@fs.fed.us. Dave Sapsis, California Department of Fire and Forestry. Sue Husari, National Park Service. Larry Hood, Lassen National Forest. Bernie Bahro and Christie Neill, USDA Forest Service Pacific Southwest Region. Danny C. Lee, USDA Forest Service Pacific Southwest Research Station. Bret Butler, USDA Forest Service Rocky Mountain Research Station.


Direct observation and measurement of fire behavior as it passes through fuel treatment areas is the most direct way to evaluate the effectiveness of fuel treatments. Concordant measurement of fuel conditions before the fire and fire behavior during the fire provide a direct means of evaluating which fuel metrics best relate to wildland fire behavior and improve fire behavior predictions. We have a rapid response team to measure fuel conditions pre- and post-fire, and fire behavior during wildland fire in areas with various fuel treatments and other past land-use management activities. During the fire season of 2002 we are prototyping techniques for such research. For each fire event, we: 1) rapidly obtain vegetation management history information; 2) obtain pre-fire aerial photography; 3) collect pre-fire fuels condition data ahead of the fire; 4) measure fire behavior through sites where we have measured fuels; and 5) measure some immediate post-fire effects and indirect measures of fire behavior. We capture and record all weather, fire behavior, topography, fuels, fire suppression actions and other pertinent information providing an overall context for the pattern of the fire. We will present preliminary results from 1 to 3 fires collected in 2002.




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Ecological Impacts of Season of Prescribed Fire in a Sierran Mixed Conifer Forest
Eric E. Knapp*, Jon E. Keeley, and Nathan L. Stephenson, US Geological Survey, Sequoia and Kings Canyon Field Station, 47050 Generals Highway, Three Rivers, CA 93271; ph: (559) 565-3175, *email: eknapp@usgs.gov.


Prescribed fire is an important tool for reducing fuels and restoring structure and function to forested ecosystems of the Sierra Nevada. Unfortunately, only a fraction of the acreage necessary for maintaining a natural fire return interval typically gets burned each year, due air quality concerns in adjacent populated areas, and the limited time before winter snows. Most prescribed burning is currently conducted in the fall to coincide with the normal historical fire period. This is also the time of year with the poorest air quality. Expanding the prescribed fire window to include early season burns might reduce air quality conflicts and allow more acres to be treated. However, the impact of early season burning on many important ecosystem components is poorly understood. Nine 15 ha plots were established in Sequoia National Park in 2001. Three plots were burned in the fall of 2001, three plots were burned in June 2002, and three remained unburned (controls). Data on fuels, overstory tree density and composition, understory vegetation, small mammal and bird populations, bark beetles, root pathogens, and soil nutrient cycling were collected by USGS researchers and other collaborators prior to the prescribed burns and are being collected post burn. Initial data indicate a great deal of heterogeneity in fire intensity and subsequent tree mortality within both the early season and late season burn units. Multiple regression analysis showed that the proportion of the tree basal area composed of pines, together with the total basal area of all trees explained 26% of the variation in crown scorch height in the late season burn plots. Areas with high abundance of pines and more trees burned with the greatest intensity, while areas dominated by fir trees and having fewer trees burned with lower intensity. Data on tree mortality, fire damage, and area burned are presently being collected in the early season burn plots. These numbers, and comparisons between the early and late season burn treatments will be reported. Preliminary data indicate that early season burns resulted in less fuel reduction and left more of the area unburned. These islands of unburned habitat may be important for recolonization by some plant and animal species post fire.




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Preliminary Results from Hazardous Fuel Reduction at Yosemite National Park, California
Kara J. Paintner* and Monica Buhler, Yosemite National Park, Fire Management Office, PO Box 577, Yosemite, CA 95389; ph: (209) 379-1115 or 375-9596; *email: kara_paintner@nps.gov.


Monitoring mechanical fuel reduction paired with prescribed fires began at Yosemite NP in 1996. Resource objectives include targets for total fuel loads and tree density. Ten plots have been installed using the NPS Fire Monitoring Handbook. A two-phase treatment starts with mechanical removal and piling of all ponderosa pine, incense cedar, and white fir smaller than 6 inches dbh and burning of the piles. Then the area is burned within two years. Seven plots have been thinned and piles burned, and two plots have burned. One and ten hour fuels increased after thinning and pile burning. Total fuel load was reduced, but is still well above target levels. Two burned plots show significant fuel load reduction. Changes in fire behavior and tree mortality were modeled at the high end of prescription before and after thinning using Crown MassTM. Before thinning a stand could have surface and active crown fire and after thinning fire behavior changed to surface fire alone. Canopy to base height increased with thinning, while scorch height and larger tree mortality decreased. The information helping to refine project prescriptions, target conditions and field evaluations for future work.




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Spatial considerations in fire management: the importance of heterogeneity for maintaining diversity in a mixed-conifer forest
Monique E. Rocca, Duke University Program in Ecology, Nicholas School of the Environment and Earth Sciences, Box 90328, Durham, NC 27708; ph: (919) 613-8124; email: mer3@duke.edu. Dean L. Urban, Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708. Jon E. Keeley, USGS Biological Resources Division, Western Ecological Research Center, Sequoia-Kings Canyon Field Station, 47050 Generals Highway, Three Rivers, CA 93271.


This study examines the factors controlling fine-scale distributions of herbs, shrubs, and tree seedlings in the Sierra Nevada mixed-conifer forest. The goals of this project are 1) to determine the importance of within-fire heterogeneity in fire effects to maintaining plant diversity, and 2) to compare alternative fire restoration strategies - spring prescribed fire, fall prescribed fire, and prescribed natural fire (PNF) - in terms their ability to create a heterogeneous environment that allows diverse suites of species to coexist. We have collected high-resolution (1 meter) botanical and environmental data along 256-meter transects in the Fire/Fire Surrogates plots and recent PNFs at Sequoia National Park. We introduce a novel spatial statistical approach, wavelet analysis, to identify relationships between species and their environment while accounting for the fact that different environmental variables exert their influence on plants at different spatial scales. Preliminary results show that, in the absence of fire, understory species distributions are controlled by local variability in topography and soil moisture at scales greater than 64 meters. We are in the process of testing whether variability in fire effects leads to finer scale patterning of species distributions after fire. Once identified, the types and scales of fire-generated environmental variability that matter to plants can be incorporated into fire restoration plans.




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Response to Management Strategies in Young-Growth Giant Sequoia Stands at Mountain Home State Forest
Gary Roller, 1330 Southwood Dr. #1, San Luis Obispo, CA 93401; ph: (805) 544-7433; email: groller@calpoly.edu. Douglas D. Piirto, PhD., Natural Resources Management, College of Agriculture, Cal Poly State University, San Luis Obispo, CA 93407; ph: (805) 756-2968.


Young-growth giant sequoia stands at Mountain Home State Forest have been re-measured in 2001 to evaluate growth response to three silvicultural treatments: thinning, thinning followed by an underburn, and control. This is the third measurement of a continuing study, which started in 1989. The California Department of Forestry and Fire Protection is providing funding for this Cal Poly study.

The current study is specifically evaluating: 1.) overall growth performance of treated giant sequoia stands; 2.) understory plant response to the silvicultural treatments; and 3.) fuel accumulation over the last twelve years following treatment. Additionally, all plots were precisely mapped using GPS technology and photographs were taken from identified photo points during this third re-measurement effort.

Preliminary findings of this current Cal Poly study are presented here. This study is unique because very little research has been done to comparatively track the overstory and understory growth response of giant sequoia, and associated flora, following mechanical treatment and prescribed burning. The data and the conclusions that will be drawn from this study are invaluable given the current political climate and interest in giant sequoia trees.




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Thermally-Driven Wind Systems and Boundary-Layer Structure in Yosemite National Park
Craig B. Clements, Atmospheric Science Programme, University of British Columbia, 1984 West Mall Vancouver, B.C. V6T 1Z2; ph: (604) 738-0552; email: cbclemen@geog.ubc.ca.


Thermally-driven wind systems are a common phenomenon found in mountainous regions throughout the world and are important in the transport of pollutants within the mountain boundary layer. As population increases are expected in California's Central Valley, there is a need for a better understanding of the boundary layer structure in the Sierra Nevada. This will have important practical implications and provide improved forecasting of air pollution episodes that may lead to adverse health and visibility degradation in the region's national parks.

Observations of the wind and temperature structure made in two major valleys of Yosemite National Park are presented. Measurements were made during multiple campaigns from 1994 to 1998 using standard meteorological towers, an atmospheric profiling system, and pilot balloons. Results have shown that the atmospheric structure in the Yosemite region is very complex and is rarely decoupled from the prevailing synoptic-scale flows. Vertical profiles of temperature in Yosemite Valley showed a strong and shallow inversion developing in the lowest 40 m by morning. Above this layer the valley atmosphere was nearly isothermal up to ~700 m AGL. Winds within the inversion were extremely weak, but down-valley flows (~ 4-6 m s-1) persisted through the entire valley depth suggesting that pollutants are easily transported from outside the region into the valley.




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Fire and Invasive Plants in the Mixed Coniferous Forest
Jon E. Keeley, U.S. Geological Survey, Sequoia-Kings Canyon Field Station, Three Rivers, CA 93271; ph: (559) 565-3170; email: jon_keeley@usgs.gov.


In the coniferous forests of Sequoia and Kings Canyon national parks, species diversity is a function of fire severity and time since fire. High intensity fires create gaps that decrease canopy coverage and increase light levels and nutrients for an ephemeral successional flora. Few species have persistent seed banks so time since fire is an important determinant of colonization success. Complicating the picture of postfire response is the fact that there was a highly significant interaction between fire severity and time since fire for understory cover, species richness and alien richness and cover. Time was consistently a significant factor for these parameters, whereas fire severity was a significant factor only for species richness parameters. In general, understory was sparse the first year after fire, particularly in low severity burns and increased substantially several years after fire, particularly on high severity burns. Both fire severity and time since fire affected alien species richness and dominance. Coniferous forests had about a third as many alien species as the foothill oak savannas and fewer than half of the species were shared between these communities. Some sites were largely free of alien species whereas others had a significant alien presence that presents a challenge for fire restoration of these forests.




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Pre-Fire Fuel Manipulation Impacts on Alien Plant Invasion of Wildlands
Jon E. Keeley* and Kyle Merriam, U.S. Geological Survey, Sequoia-Kings Canyon Field Station, Three Rivers, CA 93271; ph: (559) 565-3170, *email: jon_keeley@usgs.gov.


This project addresses the impacts of fuel breaks or defensible fuel reduction zones on invasion of alien plant species into wildland areas representing diverse fuel types, including shrublands, woodlands and conifer forests. We are investigating this potential impact on Federal (BLM, NPS, and USFS), state (CDF) and local jurisdictions throughout California with multi-agency cooperation and support. There are three objectives: 1) To inventory current floristic composition of fuel breaks in southern California, the central coast, the north coast and the Sierra Nevada and relate patterns of alien plant distribution to fuel break parameters, including construction age, past maintenance, vegetation modification treatment, proximity to roads, and other environmental variables. 2) Intensively sample belt transects perpendicular from fuel breaks into surrounding vegetation to determine the extent to which fuel breaks may act as source populations for the invasion of wildland areas. This sampling focuses on areas that have experienced fires within the last decade, as this is the time ecosystems are most vulnerable to invasion. 3) To educate resource managers on the potential problems of invasive plants, both in terms of displacing native vegetation and altering fire regimes, and on how fuel manipulations may be planned to minimize these impacts on natural landscapes.




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Avian Response to Prescribed Burning in the Spring
Karen Bagne, Dept. of Biology, University of California, Riverside, CA, 92521; USDA Forest Service, Sierra Nevada Research Center, Fresno, CA; Pacific Southwest Research Center, 2081 E. Sierra Ave, Fresno, CA 93710; ph: (559) 841-6318; email: Kbagne2@aol.com. John Rotenberry, Dept. of Biology, University of California, Riverside, CA. Kathryn Purcell, USDA Forest Service, Sierra Nevada Research Center, Fresno, CA.


Fire is an important abiotic component in maintaining a diverse landscape in many regions including the Sierra Nevada of California. Suppression of fire during the last century has altered natural systems, but in the past two decades fire has been reintroduced through prescribed burning. While prescribed fire returns an important natural process to the landscape, under human control fire can have features that are not consistent with fire regimes of the past. In particular, prescribed fires are often initiated during moist periods such as spring when many bird species are initiating breeding activities. This represents preliminary findings from 2 years of data collected in Sierra National Forest, California. Fires were set in early April and burned patchily on three of nine study sites. Territories of Hutton's Vireo were mapped and their breeding attempts monitored in addition to other target species. Tentative findings suggest that response to burning is similar to inclement weather events that can occur in the spring and unburned patches within treated areas support habitat features required by specific species that could be otherwise be negatively affected. Other habitat features such as snags were monitored for changes in distribution and abundance resulting from prescribed fire in addition to use by cavity nesting species.




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Improving Fire Hazard Assessment at the Urban Wildland Interface: Case Study in South Lake Tahoe, CA
Lisa de Jong, Ph. D., USDA Forest Service, Center for Urban Forest Research, c/o Environmental Horticulture Room 1103, Davis, CA 95616; ph: (530) 754-8908; email: ldejong@ucdavis.edu.


A fire hazard assessment was conducted on private, developed lots in South Lake Tahoe, a high fire hazard UWI community in Northern California. Fire hazard was assessed in terms of the minimum standards in the National Fire Protection Association's (NFPA) Standard 299 and homeowner choices involving compliance with the fire safety laws, construction of the home, and irrigation practices. In addition, researchers assessed the influence of non-compliant neighbors on a parcel's fire hazard.

Results indicate that the overall fire hazard rating for the city is relatively low because of its good infrastructure: good roads, water, signage, and level of service. However, the citywide non-compliance rate for maintenance is 66%, the citywide non-compliance rate for defensible space is 86% when adjusted for small parcel size, and 57% of the parcels are non-compliant for both defensible space and maintenance.

The results of this study clearly indicate that homeowners in South Lake Tahoe rarely choose for fire safety even though the city's infrastructure is good. Furthermore, individual fire hazard will be underestimated if small lot size and homeowner actions are not taken into account. Analysis of compliance rates and homeowner choices will provide a more accurate estimate of individual fire hazard.




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Landscape Patterns of Pre - 20th Century Fire in the Kaweah Watershed, Sequoia and Kings Canyon National Parks
Anthony C. Caprio, Sequoia and Kings Canyon National Parks, 47050 Generals Highway, Three Rivers, CA 93271, USA; ph: (559) 565-3126; email: tony_caprio@nps.gov.


Knowledge of the spatial and temporal attributes of pre-Euroamerican fire, including fire size, is important in understanding ecosystem processes and in developing ecologically sound fire management objectives. Over the last decade dendrochronologically reconstructed fire histories have been developed from a network of sites in the Kaweah watershed on the west slope of the Sierra Nevada. These are providing a better understanding of fire across large spatial scales prior to Euroamerican settlement (1700-1900) within a complex landscape. Sites extend from low elevation conifer patches embedded in chaparral vegetation to high elevation subalpine conifer forest. Striking differences in the fire regime between north and south aspects have been found, particularly at low-to-mid-elevation conifer sites. Fire frequency on north aspects was less than half that observed on south aspects with occurrence strongly linked to climate on north aspects. Reconstructions of fire size also show considerable variability. Some burns extended over much of the drainage and into adjacent watersheds. Fire size was also related to climatic variability with large fires, particularly on north aspects, occurring during dry years. Such differences must have had significant influences on the biotic components and the past dynamics of these landscapes. This baseline information is being utilized in monitoring restoration of fire as an ecosystem process.




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Restoring Mixed-Conifer Forests with Prescribed Fire: Monitoring to Assess Fuel Reduction and Stand Structure Objectives
MaryBeth Keifer*, Ecologist, Jeff Manley, Natural Resource Management Specialist, and Karen Webster, Biological Science Technician, Sequoia and Kings Canyon National Parks, 47050 Generals Highway, Three Rivers, CA 93271; ph: (559) 565-3128; *email: marybeth_keifer@nps.gov.


Similar to many wildlands throughout the Sierra Nevada, Sequoia and Kings Canyon National Parks experienced a disruption of the fire regime over the last century that altered forest conditions. Heavy surface fuels accumulated, stand density increased, and species composition shifted as a result of fire exclusion in forests where frequent fires had historically burned. Over the last 35 years, park managers and scientists have attempted to restore fuel and forest conditions using prescribed fire. A long-term fire effects monitoring program has documented changes in fuel load, stand structure and composition, and shrub and herbaceous vegetation composition before and following prescribed fire treatment. Fuel reduction objectives for initial prescribed fire treatment are met in all mixed-conifer forest types. In the giant sequoia-mixed conifer forest, stand structure restoration objectives are met within 5 years after initial treatment; however, other mixed-conifer forest types may need a second treatment with prescribed fire before restoration objectives are achieved. Once structural restoration objectives are met, process related objectives for maintaining the natural fire regime become the standard for determining long-term prescribed fire program success.




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Forest Litter Densities Under Different Dominant Tree Species: A Factor Affecting Ground Fire Spread
Kurt M. Menning* and John J. Battles, Division of Ecosystem Sciences, Dept. of Environmental Science, Policy and Management, University of California, Berkeley, 151 Hilgard Hall #3110, Berkeley, CA 94720; *email: kmenning@nature.berkeley.edu. Tracy L. Benning, Department of Environmental Science, Harney Science Center, 2130 Fulton Street, University of San Francisco, San Francisco, CA 94117. Nathan L. Stephenson, Biological Resources Division, United States Geological Survey, Sequoia & Kings Canyon Field Station, Research Office, Sequoia & Kings Canyon National Parks, Three Rivers, CA 93271.

Long-lived conifers and several hardwoods dominate the mixed conifer forest in the southern Sierra Nevada. Historically, this forest experienced frequent, low-severity fires. The link between canopy species variability and fire behavior in a mixed forest has not been well understood, however. We sampled forest litter across 10,000 ha in the Mineral King watershed to determine how dominant species would affect litter density and fire behavior.

Samples were sorted by canopy dominance. Litter under red fir (Abies magnifica) was the densest at 95 kg/m3, followed by pine (Pinus ponderosa, P. jeffreyi, P. monticola, P. contorta: 76 kg/m3), white fir (A. concolor: 72 kg/m3), and least dense, sequoia and cedar (Sequoiadendron giganteum and Calocedrus decurrens: 67 kg/m3). Density differences observed between red fir and both white fir and sequoia/cedar are significant.

Fire spread rates and intensity have been calculated for the different litter densities given standard conditions. For example, white fir fire spread rates (0.23 m/min) are more than double that of red fir (0.09 m/min). Intensity in white fir litter (38 J/m2min) is more than seven times that in red fir (5.3 J/m2min). Our conclusion: dominant canopy species may dramatically affect fire behavior in the mixed conifer forest.




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Fire History of the Chaparral Zone in the Southern Sierra Nevada
Jon E. Keeley* and Anne Pfaff, U.S. Geological Survey, Sequoia-Kings, Canyon Field Station, Three Rivers, CA 93271; ph: (559) 565-3170, *email: jon_keeley@usgs.gov. Pat Lineback, Sequoia-Kings Canyon National Parks, Three Rivers, CA 93271.

Chaparral dominates a significant portion of the southern Sierra Nevada foothills, yet relatively little attention has been given to historical patterns of burning in these shrublands. Using a historical database on fire history for the national parks, national forests, BLM, CDF and other jurisdictions in the foothills we have evaluated burning patterns for the 20th century. Roughly half of the chaparral area has not recorded a fire during this time period whereas some areas have had repeated fires. Spatial and temporal patterns of burning are presented. From these and other studies there is reason to believe that unlike southern California chaparral, these ecosystems may be at risk from fire exclusion.




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