![[logo] US EPA](https://webarchive.library.unt.edu/eot2008/20081105211921im_/http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Final Report: Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
EPA Grant Number: R825433C033Subproject: this is subproject number 033 , 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: Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
Investigators: Rejmankova, Eliska
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:The objectives of this research project were to conduct site-specific studies on wetland processes in the Sierra Nevada and the Lake Tahoe Basin to characterize the role of wetlands in watershed dynamics. Because of their position in the landscape at the interface of aquatic and terrestrial ecosystems, wetlands play an integral role in watershed dynamics. Rather than being simple ecotones existing solely as a gradation between upland and lake, wetlands are distinct ecosystems with unique biological, geochemical, and hydrological properties and processes. These properties, which are important at the landscape scale in nutrient dynamics, sediment movement, and biodiversity, serve to buffer the effects of terrestrial disturbances on the lake community. There is a strong need for site-specific studies on wetland processes in the Sierra Nevada and the Lake Tahoe Basin to characterize the role of wetlands in watershed dynamics.
Summary/Accomplishments (Outputs/Outcomes):Subalpine marshes of the Sierra Nevada are connected strongly to watershed properties in that they are almost wholly dependent on surface and groundwater runoff from the watershed. Because of this connection between wetland and terrestrial ecosystems, important aspects of species biodiversity and biogeochemistry in these marshes are strongly tied to properties of the surrounding watershed such as vegetation, soils, disturbance (fire, erosion), land use (timber, grazing), management (wilderness areas), and population.
Our research in subalpine wetlands of the Lake Tahoe Basin addressed wetland ecology at a range of spatial and temporal scales, from the landscape to the individual marsh. By examining: (1) how multiple stresses directly affect the wetland ecosystem (e.g., disturbance, hydrological alteration); (2) how indirect factors at the landscape level affect the wetland ecosystem (e.g., watershed size, vegetation, land uses); and (3) how wetlands modify the biogeochemical processes that contribute to the Lake Tahoe dynamics, we took an approach that mirrors the interconnections of wetlands with aquatic and terrestrial systems. Long-term research by the Tahoe Research Group has documented an important change in limiting resources in Lake Tahoe; specifically, the switch from a nitrogen (N)-limited ecosystem to a phosphorus (P)-limited ecosystem. Because resource availability not only is of crucial importance for the Lake Tahoe ecosystem, but also is a driving force in structuring plant communities, we asked the following questions: (1) Have changes in nutrient limitation observed at the lake level impacted plant communities in the transitional zones (e.g., wetlands)? (2) What community-level and, consequently, ecosystem-level changes can we expect following human alteration of nutrient cycling in the Lake Tahoe watershed? (3) What are the best ecological/ecophysiological indicators of changes in nutrient resources?
With an understanding of wetland dynamics and their relationship to landscape processes, subalpine wetlands in the Sierra Nevada can be better managed for protection of their beneficial uses.
The following activities were accomplished:
• We found that dominant marsh species can be differentiated by remote sensing. Remote sensing techniques enable rapid surveys and repeated monitoring of marshes and, thus, detection of potential changes of marsh ecosystems. Leaf reflectance spectra were different in shape and magnitude across the spectrum, with canopy architecture and cover having marked effects on albedo and wavelength-dependent variance among samples. Plants with horizontal canopy showed the least difference between canopy and leaf reflectance, those with vertical canopy had the strongest effect on reflectance, and the effect of spherical canopy was intermediate.
• Historical changes in marsh communities can be inferred from sediment cores. Pollen composition and physical and chemical characteristics of sediment cores showed the environmental changes in marshes caused by human activities around Lake Tahoe. Road construction and maintenance activities were well recorded in the cores by an increased sedimentation rate and cation concentration. The plant community of Pope Marsh has been affected by the water level change in Lake Tahoe and the maintenance of the Tahoe Keys. Also, the increase in motor vehicles affected the lead level in the marshes near roads.
• We determined that dominant plant species differ in their nutrient resorption efficiency and, consequently, in their sediment building and P removal efficiency. Information on nutrient uptake and nutrient resorption efficiency by dominant wetland macrophyte species resulted in delineation of several simple indicators (e.g., leaf tissue N, P, and N/P) of current and (recent) past conditions of sediments in particular marshes. This, in turn, provided information on N and P input from the watersheds draining into these wetlands and potential output of nutrients into the lake. This information can be used by other investigators studying Lake Tahoe's nutrient budget.
• We assessed the potential of Lake Tahoe Basin Wetlands for P removal. An important question for reducing the P input into Lake Tahoe is: How much P from stream loading and direct runoff potentially may be reduced by wetlands? Based on our data obtained during the course of this research project, we came up with the following estimates: assuming the wetland area is about 75 ha and the annual accumulation rate is 0.22 g m-1, a total of 165 g P per year is retained. This corresponds to slightly more than 0.5 percent of annual P input into the lake. Thus, wetlands do not retain most of the P entering the lake and, therefore, are not a solution to the P problem in the Tahoe Basin.
• We showed that sedimentation rate and sediment components in a wetland were changed according to human activities around the wetland. Road construction and maintenance were statistically responsible for the change in sedimentation rate. This analysis suggests that almost all of the wetlands studied still retain their pristine condition. This analysis, however, also shows that a slight increase in human activities has the possibility of degrading this condition. These results should be considered by urban development planners and resource managers in the Tahoe area.
• Our results showed that there is a correlation between tissue nutrient concentration (particularly P) and sediment nutrient content, and that rhizome nutrient content may be a better predictor of sediment nutrients than leaf nutrient content. Clearly, nutrient uptake and resorption processes by individual wetland dominants are of great importance for the performance of the whole wetland system, and should be considered carefully by other investigators researching wetland dynamics.
• We tested the possibility of using enzyme activities in soil and litter as another indicator of long-term decomposition. Because enzymes ultimately are responsible for the decomposition of organic material, this would be a clear indicator of decomposition; a useful tool for investigators studying this phenomenon.
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, Water, INTERNATIONAL COOPERATION, Geographic Area, Scientific Discipline, RFA, ECOSYSTEMS, Ecosystem/Assessment/Indicators, Water & Watershed, Restoration, Aquatic Ecosystem Restoration, Aquatic Ecosystems & Estuarine Research, Terrestrial Ecosystems, Ecological Monitoring, Aquatic Ecosystem, Ecological Indicators, Biochemistry, Watersheds, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Monitoring/Modeling, Environmental Monitoring, State, lakes, water quality, California (CA), wildlife habitat, watershed modeling, watershed land use, watershed, watershed management, watershed restoration, hydrologic modeling, ecology assessment models, environmental stress indicators, anthropogenic effects, fish habitat, land use, wetlands, watershed development, Lake Tahoe, aquatic habitat, marsh plants, agricultural watershed, aquatic ecosystems, environmental stress, lake ecosysyems, watershed sustainablility, biogeochemcial cycling, ecological assessment, hydrology, water management options, ecosystem stress, ecosystem response, ecosystem monitoring, biodiversity, nutrient dynamics, integrated watershed model
Relevant Websites:
Progress and Final Reports:
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