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Research Project: Ecohydrological Processes, Scale, Climate Variability, and Watershed Management

Location: Southwest Watershed Research Center

Title: Impact of varying storm intensity and consecutive dry days on grassland soil moisture

Author
item HOTTENSTEIN, J.D. - University Of Arizona
item PONCE-CAMPOS, G.E. - University Of Arizona
item YANES, J.M. - University Of Mexico
item Moran, Mary

Submitted to: Journal of Hydrometeorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2014
Publication Date: 2/1/2015
Citation: Hottenstein, J., Ponce-Campos, G., Yanes, J., Moran, M.S. 2015. Impact of varying storm intensity and consecutive dry days on grassland soil moisture. Journal of Hydrometeorology. 16:106-117. https://doi.org/10.1175/JHM-D-14-0057.1.
DOI: https://doi.org/10.1175/JHM-D-14-0057.1

Interpretive Summary: Climates across the world are undergoing unprecedented changes. In the early 21st century, grassland regions of the United States have experienced prolonged warm drought and a shift to larger, more infrequent storms. This has raised the question: How will these new storm patterns affect our grasslands? For nine grassland sites across the southern United States, we found a fundamental difference in Desert and Plains grasslands. Soil moisture in the wetter Plains grasslands decreased with an increase of high-intensity storms. The drier Desert grasslands were not responsive to storm size, but instead, soil moisture decreased as storms became more infrequent. This improved ability to predict soil moisture and plant growth with changing hydro-climatic conditions will result in more efficient resource management and better informed policy decisions.

Technical Abstract: Intra-annual precipitation patterns are expected to shift toward more intense storms and longer dry periods due to changes in climate within the next decades. Using satellite-derived estimates of plant growth data from 2000-2012, this study quantified the relationship between intra-annual precipitation patterns, annual average soil moisture (at 5-cm depth) and plant growth at nine grassland sites across the southern United States. Results showed a fundamental difference in the response to varying precipitation patterns between mesic and semiarid grasslands. Surface soil moisture in mesic grasslands decreased with an increase of high-intensity storms; whereas in semiarid grasslands, soil moisture decreased with longer dry periods. For these sites, we established that annual average soil moisture was a better indicator of grassland production than total annual precipitation. This improved ability to predict variability in soil moisture and plant growth with changing hydro-climatic conditions will result in more efficient resource management and better informed policy decisions.