Soil water retention after natural and simulated rainfall on a temperate grassland

Summary Recent climate change scenarios resulting from elevated trace gasses may alter environmental temperature and moisture. The ecological consequences, however, are uncertain requiring an understanding of how soil-plant systems will respond to different conditions. This study examines the temporal characteristics of soil water retention in a temperate grassland following natural and simulated summer showers. We have used weighting lysimeters located in grassland stands of 360 m², 2.25 m² and lone lysimeters measuring 0.07 m². Water deposited from natural summer rainfall on these grasslands is likely to be lost in less than two days because 92% of the rainshowers are < 10 mm having residence times of less than two days. Showers > 10 mm did, however, consistently remain in the soil-plant system for periods longer than light showers. When the largest plots (360 m²) were wetted by small (< 3 mm) natural rainfall events covering a portion of the entire valley (30–70 km²), soil water depletion rates were not significantly different than if just the 360 m² plots were wetted by irrigations of the same size. If anthopogenetic changes occur in the rainfall amounts of summer showers in the Northern Great Plains, our results support the contention that soil water retention and associated ecosystem processes may be significantly altered inAgropyron smithii (Rybd.) grasslands.With 1 Figure