Carbon sequestration and rangelands: A synthesis of land management and precipitation effects

Management of rangelands can aid in the mitigation of rising atmospheric carbon dioxide concentrations via carbon storage in biomass and soil organic matter, a process termed carbon sequestration. Here we provide a review of current knowledge on the effects of land management practices (grazing, nitrogen inputs, and restoration) and precipitation on carbon sequestration in rangelands. Although there was no statistical relationship between change in soil carbon with longevity of the grazing management practice in Dative rangelands of the North American Great Plains, the general trend seems to suggest a decrease in carbon sequestration with longevity of the grazing management practice across stocking rates. The relationship of carbon sequestration to mean annual precipitation is negative for both the 0 to 10 cm (0 to 3.9 in) and 0 to 30 cm (0 to 11.8 in) soil depths across stocking rates. The threshold from positive to negative carbon change occurs at approximately 440 mm (17.3 in) of precipitation for the 0 to 10 cm soil depth and at 600 mm (23.6 in) for the 0 to 30 cm soil depth. We acknowledge that largely unexplored is the arena of nianagement-environment interactions needed to increase our understanding of cliniate-plaiit-soil-microbial interactions as factors affecting nutrient cycling. Continued refinement of estimates of terrestrial carbon storage in rangelands will assist in the development of greenhouse gas emissions and carbon credit marketing policies, as well as potentially modifying government natural resource conservation programs to emphasize land management practices that increase carbon sequestration.