Skip to main content
ARS Home » Plains Area » Las Cruces, New Mexico » Range Management Research » Research » Publications at this Location » Publication #319463
Title: Enhanced precipitation variability effects on water losses and ecosystem

Author
item SALA, OSVALDO - Arizona State University
item GHERARDI, LAUREANO - Arizona State University
item Peters, Debra

Submitted to: Climatic Change
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: Climate change will result in increased precipitation variability with more extreme events reflected in more frequent droughts as well as more frequent extremely wet conditions. We used a process-based ecosystem model to simulate water losses and soil-water availability at 35 grassland locations in the central US under 4 levels of precipitation variability (control, +25, +50 +75%) and six temporal scales ranging from intra- to multi-annual variability. We found that inter- and multi-annual variability had much larger effects on soil water than intra-annual variability in precipitation. Further, the effect of precipitation variability was modulated by mean annual precipitation. Arid-semiarid locations receiving less than about 380 mm yr-1 mean annual precipitation showed increases in water availability at deeper depths that may promote shifts in species dominance in the future to more deeper-rooted woody plants.

Technical Abstract: Climate change will result in increased precipitation variability with more extreme events reflected in more frequent droughts as well as more frequent extremely wet conditions. The increase in precipitation variability will occur at different temporal scales from intra to inter-annual and even longer scales. We used a process-based ecosystem model to simulate water losses and soil-water availability at 35 grassland locations in the central US under 4 levels of precipitation variability (control, +25, +50 +75%) and six temporal scales ranging from intra- to multi-annual variability. We show that the scale of temporal variability had a larger effect on soil-water availability than the magnitude of variability, and that inter- and multi-annual variability had much larger effects than intraannual variability. Further, the effect of precipitation variability was modulated by mean annual precipitation. Arid-semiarid locations receiving less than about 380 mm yr-1 mean annual precipitation showed increases in water availability as a result of enhanced precipitation variability while more mesic locations (>380mm yr-1) showed a decrease in soil water availability. The beneficial effects of enhanced variability in arid-semiarid regions resulted from a deepening of the soil-water availability profile and a reduction in bare soil evaporation. The deepening of the soil-water availability profile resulting from increase precipitation variability may promote future shifts in species composition and dominance to deeper-rooted woody plants for ecosystems that are susceptible to state changes. The break point, which has a mean of 380-mm with a range between 440 and 350 mm, is remarkably similar to the 370-mm threshold of the inverse texture hypothesis, below which coarse-texture soils had higher productivity than fine-textured soils.