Great Basin Ecosystem Management Project

Individual Studies

GBEM-Team Leader

   -Jeanne Chambers

EPR-Project Leader

   -Robin Tausch

The Book

   -Great Basin Riparian Ecosystems

GBEM-Field Tour

Employment

GWERD Riparian Restoration

GWERD in the Great Basin

Climate and Vegetation History of Central Great Basin Watersheds during the Holocene

Robin J. Tausch

This work has provided a summary of the climate and vegetation changes that occurred in the Great Basin during the Holocene based on existing paleoecological records, and is examining the specific changes that occurred in the riparian corridors of Central Great Basin Watersheds using packrat midden data.

Geomorphic Responses of Central Great Basin Watersheds, Riparian Corridors, and Stream Reaches to Natural and Anthropogenic Disturbance during the mid- to late Holocene

Jerry R. Miller, Dru Germanoski

This research has reconstructed the geomorphic history of the watersheds over the past 5,000 years using detailed geomorphic mapping and carbon dating, and has determined the influence of changes in climate on hillslope and fluvial processes. It has shown that a major drought occurred 2500-1900 years ago.  Hillslopes were stripped of available sediments. Tributary-junction alluvial fans in sediments were deposited in the valley bottoms. The alluvial fan building that occurred 2,000 years ago is still influencing the geomorphic processes and vegetation patterning in these systems. The systems are currently sediment-limited and exhibit a natural tendency to incise. Current research in this area is examining the factors controlling sensitivity to disturbance at the watershed, riparian corridor, and stream reach scales.

Groundwater Sources and Flow Patterns in Streams and Meadow Ecosystems

David G. Jewett, Mark Lord

Groundwater sources are being determined by examining differences in the isotopes of hydrogen, oxygen, and carbon, and flow patterns are being evaluated from detailed piezometric groundwater monitoring. The relative influence of alluvial fans vs. bedrock on locally elevated water tables and meadow ecosystems is being evaluated through particle size analysis and seismic work. Initial results indicate that runoff is more important than groundwater in maintaining the riparian ecosystems. Also, bedrock currently has a greater influence on maintaining elevated water tables than the relatively coarse-textured alluvial fans.

Water Quality and Water/Soil Nutrient Dynamics in Central Great Basin Stream Systems

Michael Amacher

A water quality survey of streams in the Toiyabe, Toquima and Monitor ranges was conducted in spring 1994, and detailed water quality monitoring was conducted in several perennial stream systems in the Toiyabe mountain range from 1994-1999. Results indicate that water quality is generally good with low levels of dissolved N and P in the streams, although high levels of sediment may be a significant source of nonpoint pollutants. In addition, phosphorus chemistry has been examined in detail in these stream systems.

Relationships among Geomorphic Process, Hydrologic Regimes and Vegetation Dynamics within Riparian Corridors and Stream Reaches

Jeanne C. Chambers, Jerry R. Miller, Dru Germanoski, Robin J. Tausch

Several interrelated studies are examining the relationships among geomorphic processes, hydrologic regimes, and vegetation dynamics in the study systems. (1) The relationships between geomorphic features of the valley bottoms and stream reaches and vegetation patterns are being examined from a GIS based on high resolution, low-altitude video imagery. (2) The geomorphic response of the stream reaches to disturbance is being examined as a function of position relative to alluvial fans, channel characteristics, flow competence, and vegetation characteristics of the reaches. (3) The influence of geomorphic features on water table depth, soil water availability, and riparian vegetation is being examined at the scale of the stream reach.

Restoration of Riparian Corridors and Key Meadow Ecosystems

Jeanne C. Chambers

One focus of this research has examined the plant physiological and community responses of mesic meadows degraded by livestock grazing following several potential restoration treatments, including soil aeration, nitrogen additions and revegetation. Results indicate that both nitrogen addition and soil aeration can improve growth, rooting characteristics and water relations of key riparian species. A second focus has been on using threshold and alternative state concepts to examine the restoration potential of dry meadow ecosystems that have been converted to basin big sagebrush. It is finding that the threshold between the dry meadow and sagebrush state can be defined based upon depth to water table and its influences on abiotic characteristics, such as soil water availability, and biotic characteristics, such as species composition of the understory vegetation.

Analytic and predictive modeling of species distributions

Erica Fleishman

The objectives of this comprehensive program of research are to increase ecological understanding of species distributions and to implement that knowledge in a predictive context. Butterflies and birds are being used as initial focal groups. Hypotheses about biotic and abiotic predictors of species distributions are tested using clearly defined criteria and Bayesian-based methods, which facilitate more detailed and practical evaluation and improvement of predictions than conventional approaches. The project also quantifies variation in species distributions in space and time, underlying mechanisms for those changes, and how variation in species distributions affects the extent to which predictive models are applicable.

Classification and Monitoring of Central Great Basin Riparian Areas

Dave Weixelman, Desi Zamudio, and Karen Zamudio

This effort has developed a classification and monitoring scheme for riparian ecosystem types in central Nevada based on sampling on Forest Service lands in the Shoshone, Toiyabe, Toquima, and Monitor mountain ranges from 1990-1993. The original sample plots have been used to establish a long-term monitoring scheme for evaluating riparian ecosystem change within these mountain ranges.

Great Basin Riparian Ecosystems, edited by Jeanne C. Chambers and Jerry R. Miller.

Presents the approach used by the researchers to study and understand riparian areas in the Great Basin region.