title: Leaf P increase outpaces leaf N in an Inner Mongolia grassland over 27 years.
abstract: The dynamics of leaf nitrogen (N) and phosphorus (P) have been intensively explored in short-term experiments, but rarely at longer timescales. Here, we investigated leaf N : P stoichiometry over a 27-year interval in an Inner Mongolia grassland by comparing leaf N : P concentration of 2006 with that of 1979. Across 80 species, both leaf N and P increased, but the increase in leaf N lagged behind that of leaf P, leading to a significant decrease in the N : P ratio. These changes in leaf N : P stoichiometry varied among functional groups. For leaf N, grasses increased, woody species tended to increase, whereas forbs showed no change. Unlike leaf N, leaf P of grasses and forbs increased, whereas woody species showed no change. Such changes may reflect N deposition and P release induced by soil acidification over the past decades. The interannual effect of precipitation may somewhat have reduced the soil available N, leading to the more modest increase of leaf N than of leaf P. Thus, leaf N : P stoichiometry significantly responded to long-term environmental changes in this temperate steppe, but different functional groups responded differently. Our results indicate that conclusions of plant stoichiometry under short-term N fertilization should be treated with caution when extrapolating to longer timescales.
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Road, Xining 810008, People's Republic of China University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, People's Republic of China.
authors.forename: Zhaorong
authors.initials: Z
authors.lastname: Mi
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 Road, Beijing 100871, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Huang
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 Road, Beijing 100871, People's Republic of China.
authors.forename: Huijie
authors.initials: H
authors.lastname: Gan
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 Road, Beijing 100871, People's Republic of China.
authors.forename: Wenjia
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Road, Xining 810008, People's Republic of China The Arnold Arboretum of Harvard University, 1300 Centre St., Boston, MA 02131, USA.
authors.forename: Dan F B
authors.initials: DF
authors.lastname: Flynn
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Road, Xining 810008, People's Republic of China 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 Road, Beijing 100871, People's Republic of China jshe@pku.edu.cn.
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: He
mesh_terms: D002681:China; D065948:Grassland; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D010944:Plants / Q000737:chemistry; D006109:Poaceae / Q000737:chemistry; D011891:Rain; D012987:Soil / Q000737:chemistry
chemical_list: D012987:Soil; D010758:Phosphorus; D009584:Nitrogen
keywords: Chinese grassland; N : P stoichiometry; N deposition; soil acidification