Modeled ecosystem responses to intra-annual redistribution and levels of precipitation in a prairie grassland

Abstract

Global models projected that, precipitation in Great Plains of the United States will decrease in summer and increase in spring and winter. However, few studies had carefully examined ecosystem responses to this intra-annual redistribution of precipitation. Here we used a process-based model, Terrestrial ECOsystem (TECO) Model, to evaluate responses of ecosystem carbon processes (including net primary production (NPP), heterotrophic respiration (Rh), and net ecosystem production (NEP)) and hydrological cycles (including evapotranspiration, and runoff) to precipitation redistribution at three levels (−50%, ambient, and +50% precipitation) in five soil textures (sand, sandy loam, loam, silt loam, and clay loam). Redistribution was designed by subtracting 40% summer precipitation and adding to spring and fall. Results showed that precipitation redistribution decreased NPP, Rh, and NEP at all three precipitation levels. Responses of NPP, Rh, and NEP differed in five soil textures. Redistribution slightly increased runoff and decreased evapotranspiration. Runoff was higher in coarse textured soils and lower in fine textured soils. Responses of evapotranspiration were contrary to runoff. Precipitation levels and redistribution had little effect on mean annual soil water content (SWC), especially in coarse textured soils. Our results indicated that, besides amount and timing of precipitation, the intra-annual redistribution could also affect ecosystem carbon and water processes. Moreover, the extent to which the ecosystem responses to redistribution of precipitation is largely controlled by soil texture.