Analyzing CO2 concentrations with an infrared gas analyzer (IRGA)
Hoof punching and exposed peat in Aster Fen
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Abstract: Peatlands serve as significant carbon storage reservoirs relative to their abundance on the landscape yet impacts to these important ecosystems are numerous. Studies on the effects of cattle grazing on these systems are few. We measured water table dynamics, vegetation composition, CO2 fluxes, and impacts due to cattle hoof punching at four fens in the northern Sierra Nevada of California to understand the natural functioning of these peatlands and the effects of cattle grazing on the ecosystem. We compared areas with and without cattle hoof punching and contrasted impacts from cattle to the effects of erosion gully-induced water table drawdown on the potential for CO2 sequestration. We found that areas without hoof punching are generally carbon accumulating while cattle hoof punching had a negative effect on potential carbon sequestration. Areas with high amounts of hoof punching indicated carbon loss. Areas hoof punched by cattle had 10% the potential for carbon storage as areas without hoof punching in the Oreostemma alpigenum vegetation type (p < 0.0001) and 20% the potential for carbon storage in Sphagnum subsecundum (p = 0.0009). While intact fens demonstrate carbon storage potential, our analysis indicates that even small amounts of cattle hoof punching negatively affects this process and greater disturbance results in greater potential for carbon losses. Soil temperature in hoof punched areas was not significantly different than temperatures in areas without hoof punching and CO2 emissions did not depend on variations in the water table. Results suggest that cattle hoof punching has a greater negative effect on carbon sequestration than water table drawdown resulting from gully incision in these fens.
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Study sites are located in the Mount Pleasant Research Natural Area in the Bucks Lake Wilderness, Plumas National Forest, California. Sites are named Quaking, Aster, Bucks, and Rocky Knoll. Left photo inset is of Quaking Fen.
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Linear regression of cattle hoof punching and NEP. Percent hoof punching ranged from 0-100%. Increased hoof punching is linearly correlated to greater potential for carbon loss. In areas with high amounts of hoof punching NEP is positive, indicating carbon loss.
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