Influence of 90 Years of Protection From Grazing on Plant and Soil Processes in the Subalpine of the Wasatch Plateau,USA |
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| Institution: | 1. School of Environmental and Rural Science, University of New England (UNE), Armidale, NSW 2351, Australia;2. Rural Climate Solutions, UNE/NSW Department of Primary Industries, Armidale, NSW 2351, Australia;3. NSW Office of Environment and Heritage, PO Box U221, Armidale, NSW 2351, Australia;4. NSW Department of Primary Industries, Tamworth, NSW 2340, Australia;5. NSW Department of Primary Industries, Orange Agricultural Institute, Orange, NSW 2800, Australia;6. CSIRO Land and Water/Sustainable Agriculture Flagship, Glen Osmond, SA 5064, Australia;1. NSW Department of Primary Industries, Orange Agricultural Institute, 1447 Forest Road, Orange, NSW 2800, Australia;2. NSW Office of Environment and Heritage, PO Box 445, Cowra, NSW 2794, Australia;3. Charles Sturt University Orange, Leeds Pde Orange, NSW 2800, Australia;4. School of Environmental and Rural Sciences, University of New England, Armidale 2351, Australia;1. Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country, UPV/EHU, E-48940 Leioa, Basque Country, Spain;2. Department of Ecology and Natural Resources, Basque Institute for Agricultural Research and Development, NEIKER-Tecnalia, c/Berreaga 1, E-48160 Derio, Basque Country, Spain;1. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;2. Joint Center for Global Change Studies, Beijing 100875, China;3. University of Chinese Academy of Science, Beijing 100049, China;1. Institute of Wetland Research, Chinese Academy of Forestry, Beijing 100091, PR China;2. Sichuan Academy of Forestry, Chengdu 610081, PR China;3. Sustainable Resource Management, Grenfell Campus, Memorial University of Newfoundland, Corner Brook, NL A2H 6P9, Canada;4. College of Resources and Environment, Sichuan Agricultural University, Chengdu 611130, PR China |
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| Abstract: | Human communities in the Intermountain West depend heavily on subalpine rangelands because of their importance in providing water for irrigation and forage for wildlife and livestock. In addition, many constituencies are looking to managed ecosystems to sequester carbon in plant biomass and soil C to reduce the impact of anthropogenic CO2 on climate. This work builds on a 90-year-old grazing experiment in mountain meadows on the Wasatch Plateau in central Utah. The purpose of this study was to evaluate the influence of 90 years of protection from grazing on processes controlling the input, output, and storage of C in subalpine rangelands. Long-term grazing significantly reduced maximum biomass in all years compared with plots within grazing exclosures. For grazed plots, interannual variability in aboveground biomass was correlated with July precipitation and temperature (R2 = 0.51), while there was a weak correlation between July precipitation and biomass in ungrazed plots (R2 = 0.24). Livestock grazing had no statistically significant impacts on total soil C or particulate organic matter (POM), although grazing did increase active soil C and decrease soil moisture. Grazing significantly increased the proportion of total soil C pools that were potentially mineralizable in the laboratory, with soils from grazed plots evolving 4.6% of total soil C in 1 year while ungrazed plots lost 3.3% of total soil C. Volumetric soil moisture was consistently higher in ungrazed plots than grazed plots. The changes in soil C chemistry may have implications for how these ecosystems will respond to forecast climate change. Because grazing has resulted in an accumulation of easily decomposable organic material, if temperatures warm and summer precipitation increases as is anticipated, these soils may become net sources of CO2 to the atmosphere creating a positive feedback between climate change and atmospheric CO2. |
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