Impact of Varying Storm Intensity and Consecutive Dry Days on Grassland Soil Moisture

Intra-annual precipitation patterns are expected to shift toward more intense storms and longer dry periods because of changes in climate within future decades. Using satellite-derived estimates of plant growth combined with in situ measurements of precipitation and soil moisture between 1999 and 2013, this study quantifiedthe 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, 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 hydroclimatic conditions will result in more efficient resource management and better-informed policy decisions.

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