title: Response of alpine grassland to elevated nitrogen deposition and water supply in China.
abstract: Species composition and productivity are influenced by water and N availability in semi-arid grasslands. To assess the effects of increased N deposition and water supply on plant species composition and productivity, two field experiments with four N addition treatments, and three N and water combination treatments were conducted in alpine grassland in the mid Tianshan mountains, northwest China. When considering N addition alone, aboveground biomass (AGB) of forbs (F(AGB)) responded less to N addition than AGB of grasses (G(AGB)). G(AGB) increased as an effect of N combined with water addition but F(AGB) did not show such an effect, reflecting a stronger response of grasses to the interaction of water availability and N than forbs. Under all treatments, N allocation to the aboveground tissue did not change for either forbs or grasses. N deposition and water addition did not alter species richness in the present study. These results suggest that N addition generally promoted AGB but had little effect on species richness in wet years. Snowfall in winter combined with rainfall in the early growing season likely plays a critical role in regulating plant growth of the subsequent year in the alpine grassland.
authors.affiliation: Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China.
authors.forename: Kaihui
authors.initials: K
authors.lastname: Li
authors.forename: Xuejun
authors.initials: X
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Song
authors.forename: Yanming
authors.initials: Y
authors.lastname: Gong
authors.forename: Chunfang
authors.initials: C
authors.lastname: Lu
authors.forename: Ping
authors.initials: P
authors.lastname: Yue
authors.forename: Changyan
authors.initials: C
authors.lastname: Tian
authors.forename: Fusuo
authors.initials: F
authors.lastname: Zhang
mesh_terms: D000397:Air Pollution; D018533:Biomass; D002681:China; D002980:Climate; D004463:Ecology; D065948:Grassland; D009584:Nitrogen / Q000378:metabolism*; D063245:Plant Development; D010944:Plants / Q000378:metabolism; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism; D013045:Species Specificity; D014867:Water / Q000378:metabolism*; D014881:Water Supply
chemical_list: D014867:Water; D009584:Nitrogen