Enhanced precipitation promotes decomposition and soil C stabilization in semiarid ecosystems, but seasonal timing of wetting matters
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Changing precipitation regimes in semiarid ecosystems will affect the balance of soil carbon (C) input and release, but the net effect on soil C storage is unclear. We asked how changes in the amount and timing of precipitation affect litter decomposition, and soil C stabilization in semiarid ecosystems.
The study took place at a long-term (18 years) ecohydrology experiment located in Idaho. Precipitation treatments consisted of a doubling of annual precipitation (+200 mm) added either in the cold-dormant season or in the growing season. Experimental plots were planted with big sagebrush (Artemisia tridentata), or with crested wheatgrass (Agropyron cristatum). We quantified decomposition of sagebrush leaf litter, and we assessed organic soil C (SOC) in aggregates, and silt and clay fractions.
We found that: (1) increased precipitation applied in the growing season consistently enhanced decomposition rates relative to the ambient treatment, and (2) precipitation applied in the dormant season enhanced soil C stabilization.
These data indicate that prolonged increases in precipitation can promote soil C storage in semiarid ecosystems, but only if these increases happen at times of the year when conditions allow for precipitation to promote plant C inputs rates to soil.
KeywordsPrecipitation change Soil carbon sequestration Litter decomposition Semiarid ecosystem
soil organic carbon
We thank Amanda Sills, Jessica Vanderveen, Jaron Adkins, Michael Anderson, Hasini Delvinne, Janina Dierks, Shay Gillette, Aislinn Johns, Jamie (Hicks) Kezar, Peggy Martinez, Leslie Nichols, and Arianne Shannon for assisting with the field and laboratory work. Many thanks to Keith Reinhardt for helping managing the field site, the Idaho National Laboratory for providing the field site and Stoller Corporation for logistical support. This work was supported by the NSF Idaho EPSCoR Program under award number EPS-0814387. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the US Government.
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