Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress

EPA Grant Number: R825433C033
Subproject: 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: Packard, Benjamin H
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research


This project seeks to relate variations in marsh plant species assemblages and nutrient dynamics to watershed properties to study the relationship between landscapes and wetland ecosystems.


A common but frequently ignored problem faced in wetland research is that many wetlands are connected by hydrologic mechanisms to a terrestrial watershed whose characteristics influence wetland structure and function. Subalpine marshes of the Sierra Nevada are strongly connected to watershed properties in that they are almost wholly dependent on surface and groundwater runoff from the watershed. During the active summer growing season the precipitation in the Sierra Nevada is extremely low accounting for less than 5 percent of the annual total. The watershed landscape strongly influences the chemical qualities and hydroperiod of the snowmelt-dominated runoff through contact with vegetation, soils and geological substrate. 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 (e.g., fire, erosion), land use (e.g., timber, grazing), management (e.g., wilderness areas) and population.

The investigators' research in subalpine wetlands of the Lake Tahoe Basin addresses 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 are taking an approach that mirrors the interconnections of wetlands with aquatic and terrestrial systems. 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.

While considerable research has gone into elucidating the effects of freshwater wetlands on watershed processes (e.g., water quality downstream, groundwater recharge), much less has been done to address the effects of the watershed on wetlands. This research attempts to address this knowledge gap, searching for patterns in the linkages between the wetland and watershed ecosystems that will provide the framework for generating mechanistic hypotheses for experimental research. Because the research is interdisciplinary (e.g., hydrogeology, soil science, plant ecology), many questions are simultaneously being addressed with the data collection.

Work has already been completed which establishes the ability to monitor the distribution and abundance of the dominant marsh species using remote sensing. Subalpine marshes in approximately thirty different watersheds in an area of the northern Sierra Nevada extending in a ca. 50 mile radius from Lake Tahoe have been botanically surveyed. A GIS database of subalpine marshes in the Lake Tahoe Basin was constructed, describing geographic location, size, elevation and potential levels of disturbance. Watersheds that provide water to these marshes were then quantitatively characterized in additional GIS layers, by combining existing data layers and new layers created for this project. Relationships among plant community species compositions and watershed properties are currently being analyzed.

To reveal the historical change of watershed and wetland plant communities and condition, sediment cores of subalpine marshes in and around the Lake Tahoe basin, where an extensive record of human activities is available, were collected covering a range of sites of different levels of human impact. Pollen composition and physical and chemical characteristics of sediment cores showed the environmental changes according to human activities around Tahoe. Road construction and maintenance activities were well recorded in the core but an increased sedimentation rate and cation concentration. The plant community of Pope Marsh has been affected by water level change in Lake Tahoe and maintenance of Tahoe Keys. Also, the increase in motor vehicles affected the lead level in the marshes near roads.

To determine factors affecting sedimentation rate, sediment cores were collected in 11 marshes that have diverse environmental settings and sedimentation rates were determined by lead 210 dating method. Generally, sedimentation rates were related to human activities in the watershed or around the wetland but it was impossible to relate sedimentation rate to combined anthropogenic impact level. The sedimentation rate and sediment components in a wetland were changed according to human activities around the wetland. Road construction and maintenance was statistically responsible for the change in sedimentation rate. This analysis suggested that almost all of the wetlands studied still retain their pristine condition. However, it also showed that a slight increase in human activities has the possibility of degrading this condition.

Expected Results:

It is anticipated that correlations among plant community compositions and watershed properties will provide information on the ecological connections between these ecosystems, and will generate mechanistic hypotheses on the nature of these connections.

In addition, it this research hopes to elucidate the potential impact of changes in nutrient limitation on wetland community and ecosystem properties. Finally, it is also hope that this research will yield insights into nutrient budgets in subalpine wetlands and a new test of enzyme activities in soil and litter as an early indicator of ecosystem stress.

Supplemental Keywords:

Watershed, ecosystem restoration, ecosystem indicator, marsh plants, vegetation, biogeochemistry, groundwater, runoff, Lake Tahoe, wetlands, nutrient dynamics, land use., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Geographic Area, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Restoration, State, Aquatic Ecosystem, Monitoring/Modeling, Ecological Effects - Environmental Exposure & Risk, Biochemistry, Environmental Monitoring, Terrestrial Ecosystems, Ecological Monitoring, Aquatic Ecosystem Restoration, Watersheds, Ecological Indicators, nutrient dynamics, watershed development, wetlands, ecosystem monitoring, watershed management, fish habitat, marsh plants, watershed, biodiversity, anthropogenic effects, agricultural watershed, nutrient flux, biogeochemcial cycling, aquatic habitat, watershed land use, watershed modeling, ecological assessment, hydrology, integrated watershed model, lakes, aquatic ecosystems, environmental stress, lake ecosysyems, water quality, watershed sustainablility, ecosystem stress, hydrologic modeling, Lake Tahoe, California (CA), ecology assessment models, environmental stress indicators, water management options, wildlife habitat, ecosystem response, land use

Progress and Final Reports:

  • 1997
  • 1998
  • 1999
  • Final Report

  • 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