Does grazing management matter for soil carbon sequestration in shortgrass steppe?

Authors: Derner, Justin; Augustine, David; FRANK, DOUGLAS - Syracuse University

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/3/2017
Publication Date: 2/9/2018
Citation: Derner, J.D., Augustine, D.J., Frank, D.A. 2018. Does grazing management matter for soil carbon sequestration in shortgrass steppe?. Society for Range Management Meeting Abstracts. Abstract Proceedings of the 71st Society for Range Management, Technical Training, and Trade Show. Jan 28 - Feb 2, 2018, Sparks, NV.

Interpretive Summary:

Technical Abstract: Considerable uncertainty remains regarding the potential of grazing management on semiarid rangelands to sequester soil carbon. Short-term (less than 1 decade) studies have determined that grazing management potentially influences fluxes of carbon, but such studies are strongly influenced by prevailing weather/climatic conditions, with carbon gains occurring during wet periods and losses during dry/drought conditions. A few decadal studies have evaluated influences of grazing management on changes in pools of soil carbon, but again these demonstrate interactions of grazing management and climate; in addition, these studies have limitations with quantifying the relatively small changes associated with grazing management relative to the inherently large soil carbon pool. To address this limitation, we sampled soils (0-20 cm) in 2011 from 26 long-term grazing exclosures and paired moderately grazed sites in the shortgrass steppe of northeastern Colorado. Exclosures were established in 1937 across a soil texture gradient. The use of 14C radiocarbon provided the opportunity to determine turnover of the stable C pool over a seven-decade period in the presence versus absence of grazing. The effects of long-term moderate grazing or removal from grazing did not interact with soil texture to influence total soil nitrogen, total soil carbon, soil organic carbon or turnover of the soil carbon. Soil texture did influence total soil nitrogen, total soil carbon and nitrogen, but not turnover of carbon. In contrast, grazing management did not influence any of the soil properties evaluated, even though grazing strongly influenced plant community composition and altered the relative abundance of C3 versus C4 grasses. These results provide evidence that long-term moderately grazed and ungrazed sites, though different in plant community characteristics, do not differ with respect to long-term soil carbon sequestration.