Carbon allocation in grassland communities under drought stress followed by 14C pulse labeling |
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| Institution: | 1. UPMC, CNRS, BIOEMCO, (UMR CNRS-INRA-UPMC-UPEC-IRD-ENS-AgroParisTech), Thiverval-Grignon, France;2. ISES, University of Agriculture, Faisalabad, Pakistan;3. URP3F, INRA Poitou-Charentes, Lusignan, France;4. Department of Agroecosystem Research, University of Bayreuth, Germany;1. Tiantong National Field Observation Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200062, China;2. School of Life Sciences, Anhui Agricultural University, Hefei, Anhui Province, 230036, China;3. Center for Global Change and Ecological Forecasting, East China Normal University, Shanghai 200062, China;4. Coastal Ecosystems Research Station of Yangtze River Estuary, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, The Institute of Biodiversity Science, Fudan University, 220 Handan Road, Shanghai 200433, China;5. The Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration (SHUES), East China Normal University, Shanghai 2000241, China;1. Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen, Germany;2. Institute of Forestry, Tribhuwan University, Hetauda, Makwanpur, Nepal;3. Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan;4. Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany;1. Center for Ecosystem Science and Society (Ecoss), Northern Arizona University, Flagstaff, AZ 86011, USA;2. Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA;3. Canadian Rivers Institute, University of New Brunswick, Fredericton, NB E3 B 5A3, Canada;4. South Central Climate Science Center, Texas Tech University, Lubbock, TX 79409, USA;1. Department of Agroecology, Faculty of Science and Technology, Aarhus University, Post Box 50, 8830 Tjele, Denmark;2. Dept. of Soil Science of Temperate Ecosystems, University of Göttingen, Germany;3. Dept. of Agricultural Soil Science, University of Göttingen, Germany;1. Land and Environment College, Shenyang Agricultural University, Shenyang 110866, China;2. Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN, 37996, USA;1. College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, PR China;2. Faculty of Natural Resource Management, Lakehead University, 955 Oliver Road, Thunder Bay, ON P78 5E1, Canada |
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| Abstract: | Although extreme climatic events such as drought have important consequences for belowground carbon (C) cycling, their impact on the plant-soil system of mixed plant communities is poorly understood. Our objective was to study the effect of drought on C allocation and rhizosphere-mediated CO2 fluxes under three plant species: Lolium perenne, Festuca arundinacea and Medicago sativa grown in monocultures or mixture. The conceptual approach included 14CO2 pulse labeling of plants grown under drought and optimum water conditions in order to be able to follow above- and belowground C allocation. After 14C pulse labeling, we traced 14C allocation to shoots and roots, soil and rhizospheric CO2, dissolved organic carbon (DOC) and microbial biomass.Drought and plant community composition significantly affected assimilate allocation in the plant-soil system. Drought conditions changed the source sink relationship of monocultures, which transferred a relatively larger portion of assimilates to their roots compared to water sufficient plants. In contrast, plant mixture showed an increase in 14C allocation to shoots when exposed to drought.Under drought stress, root respiration was reduced for all monocultures except under the legume species. Microbial respiration remained similar in all cases showing that microbial activity was less affected by drought than root activity. This may be explained by strongly increased assimilate allocation to easily available exudates or rhizodeposits under drought. In conclusion, plant community composition may modify the impact of climatic changes on carbon allocation and belowground carbon fluxes. The presence of legume species attenuates drought effects on rhizosphere processes. |
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