The influence of hydrologic regime, vegetation, and land use on carbon fluxes of northern Sierra Nevada fens
Date
2018
Authors
Flett, Dana Anne, author
Cooper, David J., advisor
von Fischer, Joe, committee member
Chimner, Rodney A., committee member
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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. I 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. I 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. I 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, my 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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Subject
cattle
fluxes
peatland
fen
carbon dioxide
grazing