Structure and Function of Ephemeral Streams in the Arid and Semiarid Southwest: Implications for Conservation and Management
RC-1726
Objective
Ephemeral and intermittent streams and their associated riparian biota are an important but little studied resource in the southwestern United States. Many agents of change affect these ecosystems, from local factors such as freshwater withdrawal to regional factors including climate change. However, the impacts of abiotic controls on ecosystem end points such as biodiversity are not well understood.
The objective of this project is to increase understanding of the hydroclimatic processes that influence ephemeral and intermittent stream ecosystems. Specific objectives are to (1) quantify the responses to and dependence on groundwater by riparian biota; (2) quantify biotic responses to seasonal water pulses and document spatio-temporal patterns of variation; (3) assess how stream and riparian attributes are influenced by catchment size and position within a stream network; and (4) provide an integrated assessment of regional variability of ephemeral and intermittent stream ecosystems and of the processes that influence their structure and function.
Technical Approach
To address effects of climate variability and change, ephemeral and intermittent stream study sites will be selected on and near Department of Defense (DoD) lands in three areas of Arizona that differ in duration, intensity, and frequency of seasonal precipitation events. To evaluate impacts of freshwater withdrawals, sites will be selected that have different water table depths. To assess the influence of spatio-temporal variability, data will be collected over a 3-year period. To determine how position within a stream network affects ephemeral and intermittent stream attributes, sites will be selected on streams with and without perennial headwaters that drain catchments of differing size. Physical variables to be measured include soil and groundwater moisture status, surface water, infiltration, recharge fluxes, and nutrient levels and biogeochemical fluxes. These measurements will be supplemented with hydrologic models. Biotic variables include biomass, composition, diversity, and productivity of plant communities (inclusive of seed banks) and productivity, composition, and diversity of ground-dwelling arthropods. A key component is measurement of secondary production of arthropods, thereby providing a bridge between plant productivity and productivity of higher trophic levels.
Benefits
Results of this project will inform decision making regarding land and water use by increasing understanding of how human actions affect ephemeral and intermittent streams. The results will also aid DoD land managers in prioritizing locations for stream restoration and protection. In terms of broader scientific impact, the research will increase understanding of abiotic and biotic system linkages in a little studied ecosystem. Of particular significance for dryland regions, the research will increase understanding of linkages between climate, hydrology, nutrients, and diversity, composition and productivity of riparian vegetation and soil arthropods. (Anticipated Project Completion - 2014)
Symposium & Workshop
FY 2013 New Start Project Selections
Points of Contact
Principal Investigator
Dr. Juliet Stromberg
Arizona State University
Phone: 602-276-2635
Program Manager
Resource Conservation and Climate Change
SERDP and ESTCP
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.