title: Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau.
abstract: Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland.
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 100871, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 100871, Beijing, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Environmental Futures Research Institute, Griffith School of Environment, Griffith University, 4111, Nathan, Queensland, Australia.
authors.forename: Chengrong
authors.initials: C
authors.lastname: Chen
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., 810008 Xining, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China.
authors.forename: Qi-Bing
authors.initials: QB
authors.lastname: Wang
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 100871, Beijing, China.|Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., 810008 Xining, China.
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: He
mesh_terms: D018533:Biomass; D057231:Climate Change; D017753:Ecosystem; D065948:Grassland; D064307:Microbiota / Q000187:drug effects / Q000528:radiation effects; D009584:Nitrogen / Q000032:analysis*; D058458:Nitrogen Cycle; D011891:Rain; D012987:Soil / Q000737:chemistry*; D013696:Temperature; D018609:Tibet
chemical_list: D012987:Soil; D009584:Nitrogen