title: Influences of nitrogen, phosphorus and silicon addition on plant productivity and species richness in an alpine meadow.
abstract: Fertilization, especially with nitrogen (N), increases aboveground primary productivity (APP), but reduces plant species richness at some level. Silicon (Si) fertilization alone, or with addition of N or phosphorus (P), has multiple direct and indirect beneficial effects on plant growth and development, both for individuals and the whole community. This study aimed to examine the effects of Si, N, P, NSi and PSi combinations on APP and species richness of the community and of four functional groups in an alpine meadow. The results showed that plots fertilized with Si in combination with either N or P had higher APP than when fertilized with N or P alone. Addition of N or P increased APP, and the higher APP occurred when the highest level of N was added, indicating co-limitation of N and P, with N being most limiting. Silicon fertilization alone or with addition of N increased the APP of grasses and forbs. Nitrogen addition decreased the community species richness; Si with addition of N alleviated the loss of species richness of the whole community and the forbs group. For the four functional groups, N or P addition increased the species richness of grasses and decreased that of forbs. Our findings highlight the importance of Si in improving APP and alleviating N fertilization-induced biodiversity loss in grasslands, and will help improve our ability to predict community composition and biomass dynamics in alpine meadow ecosystems subject to changing nutrient availability.
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems/School of Life Science, Lanzhou University, No. 222, South Tianshui Road, Lanzhou, Gansu 730000, China dhxu@lzu.edu.cn.
authors.forename: Danghui
authors.initials: D
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems/School of Life Science, Lanzhou University, No. 222, South Tianshui Road, Lanzhou, Gansu 730000, China.
authors.forename: Xiangwen
authors.initials: X
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems/School of Life Science, Lanzhou University, No. 222, South Tianshui Road, Lanzhou, Gansu 730000, China.
authors.forename: Renyi
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Centre of Urban Ecology and Environmental Biotechnology, Lanzhou City University, Lanzhou 730070, China.
authors.forename: Tianpeng
authors.initials: T
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems/School of Life Science, Lanzhou University, No. 222, South Tianshui Road, Lanzhou, Gansu 730000, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Bu
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems/School of Life Science, Lanzhou University, No. 222, South Tianshui Road, Lanzhou, Gansu 730000, China.
authors.forename: Guozhen
authors.initials: G
authors.lastname: Du
keywords: Aboveground primary productivity (APP); community composition; nitrogen enrichment; plant functional group; silicon nutrient; species richness