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Final Report: Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
EPA Grant Number: R825433C032Subproject: this is subproject number 032 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
Investigators: Rizzo, David
Institution: University of California - Davis
EPA Project Officer: Levinson, Barbara
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992)
Research Category: Center for Ecological Health Research , Targeted Research
Description:
Objective:In the first part of our research project, we studied dwarf mistletoe in two different areas (with different management histories) and two different Arceuthobium species over three study sites. The objectives of this research project were to: (1) determine the relationships of dwarf mistletoe with host variables, bark beetles, and mortality; (2) assess the spatial pattern of Arceuthobium on white fir in two different mixed-conifer locations in the Sierra Nevada; and (3) determine whether different species of Arceuthobium on their respective conifer hosts have similar spatial distributions within a 1-ha area. We looked at the distribution of an introduced pathogen, white pine blister rust (WPBR). This is an exotic pathogen that infects and kills five-needle pine species.
Summary/Accomplishments (Outputs/Outcomes):Many pathogens and insects are considered to be major pests of forest ecosystems and, therefore, detrimental to management goals. The fact that many of these organisms, however, are native to these sites indicates that they also may play key roles in ecosystem functions (e.g., directing succession, maintaining biodiversity, decomposition, or providing food for wildlife). Although the importance of pathogens and insects in natural forests has been acknowledged by ecologists, relatively few studies have directly assessed their role in the dynamics of these ecosystems. To remedy this lack of knowledge, we identified major pest complexes (pathogens and insects) associated with overstory and understory mortality and reduced vigor in the forests of the Sierra Nevada Mountains and the Sierra San Pedro Martir (SSPM) of Northern Baja, Mexico. The combination of data from all of our study sites has contributed to current models that relate to ecosystem health and offer practical information for restoration efforts.
In the SSPM, we determined the prevalence of pathogens and insects across mixed-conifer stands to assess the role of pests in a pristine forest ecosystem. We also determined the spatial distribution of the white fir's two most common pests, Phoradendron pauciflorum (a parasitic plant that is bird dispersed) and Scolytus ventralis (a bark beetle), across a 25-ha grid to assess the spread and relationship of pest and host variables.
The presence of root disease in conifers will play a significant role in determining the direction of vegetation management in the Sierra Nevada's Yosemite National Park. Thus, we documented and mapped 68 discrete canopy gaps associated with the fungal pathogen, Heterobasidion annosum, and followed the progression of the disease over the past 30 years in the Yosemite Valley.
Finally, we participated in the Teakettle Ecosystem Experiment, which aims to test management protocols (e.g., prescribed fire, thinning) recommended for the restoration of coniferous forests via a large-scale, replicated study. The project involves 15 scientists from 6 institutions, covering topics ranging from soils and microclimate to the distribution of invertebrates and vertebrates. All trees over a 72-ha area have been mapped and divided into 18 4-ha plots; these plots will be treated with various combinations of burning and thinning. The experiment has allowed for 2 years of data collection before the treatments. It is clear from the initial data collection from all scientists that patch dynamics are one of the driving forces behind ecosystem function in these forests. Our study interfaces with the other studies by determining the causes of these patches.
The following activities were accomplished:
• We have shown that the relative impacts of fire and biotic agents have changed over the past 150 years in Sierra Nevada forests. The importance of fire and biotic organisms appears to differ between the SSPM and the mixed-conifer forests of the Sierra Nevada. Although fire is responsible for subcanopy mortality in SSPM, pests are important to overstory mortality in the Sierra Nevada. Mortality rates generally are constant and deviate because of spatially restricted episodes of bark beetle mediated mortality. In contrast, stand thinning in mixed-conifer Sierra Nevada forests takes place at a much later point in time in stand development (i.e., when trees are larger than 20 cm dbh). In these fire-suppressed Sierra Nevada forests, insects and diseases in association with periodic drought events now largely have replaced fire as the main stand-thinning agents, but insects, diseases, and fire maintain tree diversity and evenness in the SSPM. Sierra Nevada forest managers should consider this information carefully.
• We determined that ecosystems under traditional ecosystem patterns are more resistant to pathogens and insects during stress periods such as drought. Although similar droughts struck both the Sierra Nevada and the SSPM during the early 1990s, the stand structure of the SSPM allowed these forests to escape the drought without landscape-level mortality because of bark beetles. This has implications for the development of restoration guidelines and stand manipulations.
• Our results suggest that WPBR incidence in mixed-conifer forests is largely dependent on topographic features that favor environmental conditions suitable for rust infection. In the Lake Tahoe Basin, three species that are affected by this disease: sugar pine (Pinus lambertiana), western white pine (Pinus monticola), and whitebark pine (Pinus albicaulis). Western white pine grows in the transition zone between upper montane and the subalpine zone, whereas whitebark pine exists only in the subalpine zones. These two species are important components of these subalpine habitats, and are valued for their roles in watershed protection and wildlife food at these higher elevations. The loss of these species from the subalpine landscape would have major ecological consequences. Thus, forest management agencies will find our results useful in protecting these valuable species.
• We contributed to the large-scale Teakettle Ecosystem Experiment—a project that tests management protocols recommended for coniferous forest restoration—by determining the causes of patch dynamics because of thinning and burning practices. Our baseline data will be invaluable for assessing the efficacy of various stand treatments during future drought years and periodic outbreaks of bark beetles and defoliators.
• We developed guidelines for root disease prevention in Yosemite Valley conifer forests. Since the flood of 1997, the Yosemite Valley has undergone significant restoration of campgrounds to natural conditions, the establishment of new campgrounds, and the building of numerous hotel and employee buildings. Park mangers have recognized that root disease can significantly influence all of these objectives. We have assisted the park by mapping all infection centers in the developed areas of the Yosemite Valley and have recommended placement of buildings to minimize impacts on the forest. In addition, we have written a set of guidelines for park personnel to follow during construction activities. Hazardous trees in canopy gaps have been felled by the park service since the 1970s, but the option of tree removal in developed areas must be continually evaluated in relation to the often competing requirements for public safety, aesthetics, and ecosystem function.
Supplemental Keywords:ecosystem, ecosystem protection, environmental exposure and risk, geographic area, international cooperation, water, terrestrial ecosystems, aquatic ecosystem, aquatic ecosystem restoration, aquatic ecosystems and estuarine research, biochemistry, ecological effects, ecological indicators, ecological monitoring, ecology and ecosystems, environmental chemistry, restoration, state, water and watershed, watershed, watershed development, watershed land use, watershed management, watershed modeling, watershed restoration, watershed sustainability, agricultural watershed, exploratory research environmental biology, California, CA, Clear Lake, Lake Tahoe, anthropogenic effects, aquatic habitat, biogeochemical cycling, ecological assessment, ecology assessment models, ecosystem monitoring, ecosystem response, ecosystem stress, environmental stress, environmental stress indicators, fish habitat, hydrologic modeling, hydrology, integrated watershed model, lake ecosystems, lakes, land use, nutrient dynamics, nutrient flux, water management options, water quality, wetlands. , Ecosystem Protection/Environmental Exposure & Risk, ENVIRONMENTAL MANAGEMENT, Water, INTERNATIONAL COOPERATION, Scientific Discipline, RFA, ECOSYSTEMS, Ecosystem/Assessment/Indicators, Water & Watershed, exploratory research environmental biology, Restoration, Aquatic Ecosystem Restoration, Aquatic Ecosystems & Estuarine Research, Terrestrial Ecosystems, Ecological Monitoring, Aquatic Ecosystem, Ecological Indicators, Biochemistry, Environmental Microbiology, Ecological Effects - Human Health, Watersheds, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Monitoring/Modeling, Resources Management, water quality, ecological impact, lake ecosystem, forest tenure, watershed management, watershed restoration, ecosystem modeling, ecological restoration, deforestation, ecological research, aquatic habitat protection , pest complexes, ecosystem restoration, wetland restoration, forested basins, wetland plant species, conservation, GIS, forest ecosystems, aquatic ecosystems, ecosystem assessment, environmental stress, pathogens, vegetation , lake ecosysyems, biotic stress, deterministic linkages, ecological assessment, forest conservation, forests, restoration strategies, ecosystem stress, watershed assessment, ecological models, watershed forests, Sierra National Forest, biodiversity, ecological effects, restoration planning
Relevant Websites:
Progress and Final Reports:
1999 Progress Report
2000 Progress Report
Original Abstract
Main Center Abstract and Reports:
R825433 EERC - Center for Ecological Health Research (Cal Davis)
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
R825433C002 Sacramento River Watershed
R825433C003 Endocrine Disruption in Fish and Birds
R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
R825433C005 Fish Developmental Toxicity/Recruitment
R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
R825433C009 Modeling Ecosystems Under Combined Stress
R825433C010 Mercury Uptake by Fish
R825433C011 Clear Lake Watershed
R825433C012 The Role of Fishes as Transporters of Mercury
R825433C013 Wetlands Restoration
R825433C014 Wildlife Bioaccumulation and Effects
R825433C015 Microbiology of Mercury Methylation in Sediments
R825433C016 Hg and Fe Biogeochemistry
R825433C017 Water Motions and Material Transport
R825433C018 Economic Impacts of Multiple Stresses
R825433C019 The History of Anthropogenic Effects
R825433C020 Wetland Restoration
R825433C021 Sierra Nevada Watershed Project
R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
R825433C025 Regional Movement of Toxics
R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
R825433C031 Pre-contact Forest Structure
R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
R825433C035 Border Rivers Watershed
R825433C036 Toxicity Studies
R825433C037 Watershed Assessment
R825433C038 Microbiological Processes in Sediments
R825433C039 Analytical and Biomarkers Core
R825433C040 Organic Analysis
R825433C041 Inorganic Analysis
R825433C042 Immunoassay and Serum Markers
R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
R825433C045 Microbial Community Assays
R825433C046 Cumulative and Integrative Biochemical Indicators
R825433C047 Mercury and Iron Biogeochemistry
R825433C048 Transport and Fate Core
R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
R825433C053 Currents in Clear Lake
R825433C054 Data Integration and Decision Support Core
R825433C055 Spatial Patterns and Biodiversity
R825433C056 Modeling Transport in Aquatic Systems
R825433C057 Spatial and Temporal Trends in Water Quality
R825433C058 Time Series Analysis and Modeling Ecological Risk
R825433C059 WWW/Outreach
R825433C060 Economic Effects of Multiple Stresses
R825433C061 Effects of Nutrients on Algal Growth
R825433C062 Nutrient Loading
R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
R825433C064 Chlorinated Hydrocarbons
R825433C065 Sierra Ozone Studies
R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
R825433C067 Terrestrial - Agriculture
R825433C069 Molecular Epidemiology Core
R825433C070 Serum Markers of Environmental Stress
R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
R825433C072 Molecular Monitoring of Microbial Populations
R825433C073 Aquatic - Rivers and Estuaries
R825433C074 Border Rivers - Toxicity Studies