PNNL

Abstract

Soil respiration is a major component of global carbon cycling, but the long-term response of this flux to altered precipitation regimes remains uncertain. This uncertainty is in large part due to differential responses of soil respiration in distinct ecosystems with varying degrees of water-limitation. We conducted a meta-analysis to determine the role of soil characteristics (organic carbon stock and clay content), study duration, and ecosystem type (e.g., forest, grassland, etc) in modifying the response of soil respiration to precipitation change. In general, increased precipitation increased soil respiration rates, and decreased precipitation decreased this flux. However, the long-term response of ecosystems varied, with ecosystem types that are less constrained by water-availability showing acclimation to altered precipitation. Soil characteristics strongly modified the response of soil respiration to decreased precipitation, but only weakly modified the response to increased precipitation. Our results indicate that ecosystems with limited soil water-holding capacity and strong inherent water-limitation will show long-term dynamic change in soil respiration regardless of direction of precipitation change.