Impact of experimental warming on soil temperature and moisture of the shallow active layer of wet meadows on the Qinghai-Tibet Plateau |
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| Affiliation: | 1. Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China;2. Zoige Peatland and Global Change Research Station, Chinese Academy of Sciences, Hongyuan 624400, China;3. University of Chinese Academy of sciences, Beijing 100049, China;4. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China;1. State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, 4, 320 West Donggang Road, Lanzhou 730000, China;2. School of Civil Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China;3. Key Laboratory of Western China''s Environmental Systems (Ministry of Education),College of Earth and Environmental Sciences, Lanzhou University, 222 South Tianshui Road, Lanzhou 730000, China;4. Institute of Arctic and Alpine Research, University of Colorado at Boulder, Boulder, CO 80309-0545, USA;1. State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, Qinghai 810016, China;2. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai 810008, China;3. Harvard University Herbaria, Cambridge, MA 02138, USA;4. Department of Ecosystem Science and Sustainability and Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80525, USA;5. Key Laboratory of Restoration Ecology for Cold Regions Laboratory in Qinghai, Xining, Qinghai 810008, China;6. Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, College of Environment and Planning, Henan University, Kaifeng, Henan 475004, China |
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| Abstract: | Climate change is now increasingly evident on the Qinghai–Tibet Plateau and has a strong impact on both the abiotic and biotic components of ecosystems, particularly on permafrost, active layer thickness, vegetation, and soil properties. Permafrost ecosystems are recognized to be sensitive to the influences of the changing climate, which may disturb the permafrost soil carbon (C) pool and lead to huge C emissions. To facilitate the assessment of warming effects on the temperature and moisture patterns in the shallow soil of the active layer of the wet meadows on the Qinghai–Tibet Plateau, near-surface air temperature was passively increased by using open-top chambers (OTCs) with two different temperature increments. Soil temperature and moisture were continuously monitored at depths of 5, 20, and 40 cm at hourly intervals in a wet meadow in the Beiluhe region on the Qinghai–Tibet Plateau from October 1, 2007 to June 24, 2009. When near-surface air temperature increased by 5.29 °C and 1.84 °C in the OTC2 and OTC1 plots, respectively, relative to the control plots, soil temperatures at depths of 5, 20, and 40 cm were seen to increase by 3.84°C, 2.23°C, and 1.42 °C, respectively, in the OTC2 plots and by 0.94°C, 0.27°C, and 0.25 °C, respectively, in the OTC1 plots. Soil moisture content at depths of 5, 20, and 40 cm declined by 8.04%, 1.79%, and 1.52%, respectively, in the OTC2 plots and by 5.33%, 0.69%, and 0.09%, respectively, in the OTC1 plots. Near-surface warming was found to extend the continuous thawing time of the shallow soil, delay the occurrence of the autumnal freezing process, and shorten the duration of continuous freezing. It was also seen to increase both the temperature of the shallow soil and the accumulated temperatures at different depths. Near-surface warming could be one of the main factors leading to the degradation of vegetation, thus threatening the stability of the soil C pool and the ecological safety of the Qinghai–Tibet Plateau. |
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