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Livestock impacts on soil organic carbon storage in Great Basin ecosystems.
Ogle, Stephen*,1, Ojima, Dennis1, Clausnitzer, Dave2, Sanford, Robert3, 1 Colorado State University, Fort Collins, CO2 USGS, Forest & Rangeland Ecosystem Science Center, Corvallis, OR3 University of Denver, Denver, CO
ABSTRACT- Livestock production has been shown to have dramatic impacts on Great Basin ecosystems. Our objective was to evaluate the impact of livestock use on soil organic carbon (SOC) storage using a combination of field sampling and computer modeling. To quantify livestock impacts, we sampled plots at 75 and 2640 m from 4 watering holes in Oregon and Utah, representing high- and low-use by livestock. Plots near watering holes had significantly more soil organic carbon for 3 of the 4 sites, with high-use plots having 406 to 510 gC m-2 more SOC than low-use plots. Consistent with SOC, high-use plots had significantly more root biomass, ranging from 19 to 21 g m-2. Modeling the increase in root biomass accounted for 25% of the enhancement in SOC storage near water holes. In addition, livestock have redistributed carbon to the high-use areas, estimated at 0.1 to 1 gC m-2 month-1, and modeling this effect accounted for an additional 30% of the increase in carbon storage near the water holes. This research suggest that SOC storage increases in areas surrounding water holes across Great Basin ecosystems over time frames ranging from 20 to 50 years, and both redistribution of carbon by livestock and shifts in plant carbon allocation favoring root growth in those locales have contributed to this landscape pattern.
Key words: livestock, arid lands, soil organic carbon, Great Basin