Complex Response of Grassland Soil Moisture to Extreme Precipitation Patterns

Intra-annual precipitation patterns are expected to shift towards more intense storms and longer dry periods due to changes in climate within the next decades. Using rainfall, soil moisture and satellite-derived plant growth data from 2000-2012, this study was able to quantify the relationship between extreme precipitation patterns, annual soil moisture, and plant growth at six grassland sites across the United States. Results showed a fundamental difference in the response to altered precipitation patterns between mesic and semi arid grasslands. Soil moisture in mesic grasslands decreased with an increase of high-intensity storms, and semi-arid grassland soil moisture decreased with longer dry periods. Using satellite-derived estimates of plant growth, we established a positive correlation between increases in soil moisture and plant production. Further, we concluded that growing season soil moisture is a better indicator of grassland production than precipitation. This improved ability to predict soil moisture and plant growth due to changing hydro-climatic conditions will result in more efficiently managed resources and better informed policy decisions.