title: Increasing temperature reduces the coupling between available nitrogen and phosphorus in soils of Chinese grasslands.
abstract: Changes in climatic conditions along geographical gradients greatly affect soil nutrient cycling processes. Yet how climate regimes such as changes in temperature influence soil nitrogen (N) and phosphorus (P) concentrations and their stoichiometry is not well understood. This study investigated the spatial pattern and variability of soil N and P availability as well as their coupling relationships at two soil layers (0-10 and 10-20 cm) along a 4000-km climate transect in two grassland biomes of China, the Inner Mongolian temperate grasslands and the Tibetan alpine grasslands. Our results found that in both grasslands, from cold to warm sites the amounts of soil total N, total P and available P all decreased. By contrast, the amount of available N was positively related to mean annual temperature in the Tibetan grasslands. Meanwhile, with increasing temperature ratio of available N to P significantly increased but the linear relationship between them was considerably reduced. Thus, increasing temperature may not only induce a stoichiometric shift but also loose the coupling between available N and P. This N-P decoupling under warmer conditions was more evident in the Tibetan alpine grasslands where P limitation might become more widespread relative to N as temperatures continue to rise.
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, 5 Yiheyuan Rd., Beijing 100871, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Department of Geoscience, Soil Science and Geomorphology, University of Tuebingen, Ruemelinstrasse 19-23, 72070 Tuebingen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Baumann
authors.affiliation: Odum School of Ecology, University of Georgia, 140 E Green St, Athens, GA 30602, USA.
authors.forename: Chao
authors.initials: C
authors.lastname: Song
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining 810008, China.
authors.forename: Mi
authors.initials: M
authors.lastname: Zhang
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, 5 Yiheyuan Rd., Beijing 100871, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining 810008, China.
authors.forename: Peter
authors.initials: P
authors.lastname: Kühn
authors.affiliation: Department of Geoscience, Soil Science and Geomorphology, University of Tuebingen, Ruemelinstrasse 19-23, 72070 Tuebingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Scholten
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, 5 Yiheyuan Rd., Beijing 100871, China.|Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining 810008, China.
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: He