Untitled DocumentHydrologic thresholds for biodiversity in semiarid riparian ecosystems: Importance of climate change and variability
Macro Theme Area:
River Systems [Project ID: R40]
PI:
Tom Meixner
CO-PI(s):
James Hogan, Julie Stromberg
Basin focus:
San Pedro
Specific area in
basin /
field sites:
N/A
Summary/Goals: Riparian ecosystems of the arid and semiarid Southwest are linear corridors of high productivity and diversity. These ecosystems are sensitive to even small changes in the riparian water balance, with sharp changes in vegetation as streams become intermittent and as groundwater declines below survivorship thresholds. As a result, riparian vegetation has declined on many rivers due to water abstraction or has been altered due to the hydrologic impacts of climate variability. Despite much disciplinary work on individual rivers, a regionally comprehensive and integrated understanding of how aquatic-terrestrial ecotones respond to hydrologic change, including those imposed by climate change, awaits development.
Activities and outcomes during past year:
Initial sampling has begin on the Bill Williams and Hassayampa. Infrequent flooding on the Bill Williams appears to make it an end member system on cottonwood willow forests. The initial Hassayampa data is still being analyzed but shows very little variation over time. Ajami and Simpson have both commenced on coupling groundwater and surface water models in San Pedro. Ajami has started working on the technical and philosophical approaches to seasonalizing recharge.
Plans for the upcoming year:
We will determine region-wide sensitivity of riparian vegetation to climate change by 1) isotopically quanitifying riparian aquifer recharge along a regional precipitation gradient; 2) evaluating established connections between vegetation condition and hydrologic conditions of flood flows, groundwater depth, and stream flow permancne; and 3) developing alternative scenarios of climate change and using a scenario-driven model to estimate climate impacts on vegetation along the San Pedro River.
