Vegetation cover and rain timing co-regulate the responses of soil CO2 efflux to rain increase in an arid desert ecosystem |
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| Institution: | 1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China;2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China;3. Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China;4. Ministry of Education Key Laboratory for Earth System Modeling and Center for Earth System Science, Tsinghua University, Beijing 100084, China;1. Kyushu Research Center, Forestry and Forest Products Research Institute (FFPRI), 4-11-16 Kurokami, Chuo-ku, Kumamoto 860-0862, Japan;2. Department of Forest Soils, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan;3. Fukushima Prefectural Forestry Research Center, 1 Nishi-jimasaka, Narita, Asaka, Koriyama, Fukushima 963-0112, Japan;4. Shikoku Research Center, FFPRI, 2-915 Asakura-Nishimachi, Kochi 780-8077, Japan;1. State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi, Xinjiang 830011, China;2. Department of Agronomy, University of Almeria, Carretera de Sacramento s/n, 04120 La Cañada de San Urbano, Almería, Spain;1. State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China;2. CSIRO Sustainable Agriculture Flagship, Glen Osmond, SA 5064, Australia;3. University of Chinese Academy of Sciences, Beijing 100049, China;1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China;2. Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resource, Yangling 712100, China;3. College of Resources and Environment, Northwest A&F University, Yangling 712100, China;1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. Inner Mongolia Prataculture Research Center, Chinese Academy of Science, Hohhot 010031, China;4. Institute of Agricultural Resources and Regional Planning, CAAS, Beijing 100081, China;5. Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China;6. School of Environment, Tsinghua University, Beijing 100084, China;1. College of Life Sciences, Nankai University, Tianjin 300071, People’s Republic of China;2. Netherlands Institute of Ecology (NIOO-KNAW), Department of Terrestrial Ecology, P.O. Box 50, 6700 AB, Wageningen, The Netherlands;3. Department of Statistics, The University of Chicago, Chicago, IL 60637, USA;4. College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, People’s Republic of China |
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| Abstract: | Climate models often predict that more extreme precipitation events will occur in arid and semiarid regions, where C cycling is particularly sensitive to the amount and seasonal distribution of precipitation. Although the effects of precipitation change on soil carbon processes in desert have been studied intensively, how vegetation cover and rain timing co-regulate the responses of soil CO2 efflux to precipitation change is still not well understood. In this study, a field manipulative experiment was conducted with five simulated rain addition treatments (natural rains plus 0%, 25%, 50%, 75%, 100% of local annual mean precipitation) in a desert ecosystem in Northwest China. The rain addition treatments were applied with 16 field rain enrichment systems on the 10th day of each month from May to September, 2009. Soil water content, soil temperature and soil CO2 efflux rates were measured in both bare and vegetated soils before and after the rain addition during a 3-week period for each rain treatment. The response magnitude and duration of soil CO2 efflux to rain addition depended not only on the rain amount but also on the type of vegetation covers and the timing of rain addition treatments. Soil water content responded quickly to the rain addition regardless of rain amount and timing, but soil CO2 efflux increased to rain addition only in May–July but not in late growing season (September). In addition, soil CO2 efflux from the bare and vegetated soils showed similar increase to rain additions in May–July, but they demonstrated distinct responses to rain addition in September. The differences in the responses of soil CO2 efflux to rain addition between the bare and vegetated soils could be explained by the root activities stimulated by added rain water, while the difference in soil CO2 efflux response to rain addition among treatment times could be attributed to soil water condition prior to rain addition and/or soil temperature drop following rain addition. Thus, both vegetation cover and rain timing can co-regulate responses of soil CO2 efflux to future precipitation change in arid desert ecosystems, which should be considered when predicting future carbon balance of desert ecosystems in arid and semiarid regions. |
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