title: Response of aboveground biomass and diversity to nitrogen addition along a degradation gradient in the Inner Mongolian steppe, China.
abstract: Although nitrogen addition and recovery from degradation can both promote production of grassland biomass, these two factors have rarely been investigated in combination. In this study, we established a field experiment with six N-treatment (CK, 10, 20, 30, 40, 50 g N m(-2) yr(-1)) on five fields with different degradation levels in the Inner Mongolian steppe of China from 2011-2013. Our observations showed that while the external nitrogen increased the aboveground biomass in all five grasslands, the magnitude of the effects differed with the severity of degradation. Fields with a higher level of degradation tended to have a higher saturation value (20 g N m(-2) yr(-1)) than those with a lower degradation level ( < 10 g N m(-2) yr(-1)). After three years of experimentation, species richness showed little change across degradation levels. Among the four functional groups of grasses, sedges, forbs and legumes, grasses shared the most similar response patterns with those of the whole community, demonstrating the predominant role that they play in the restoration of grassland under a stimulus of nitrogen addition.
authors.affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.
authors.forename: Xiaotian
authors.initials: X
authors.lastname: Xu
authors.affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Environment and Resources, Zhejiang Agricultural and Forestry University, Lin'an, Zhejiang 311300, China.
authors.forename: Zhaoliang
authors.initials: Z
authors.lastname: Song
authors.affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.
authors.forename: Guozheng
authors.initials: G
authors.lastname: Hu
authors.affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.
authors.forename: Zhaohuan
authors.initials: Z
authors.lastname: Qi
mesh_terms: D044822:Biodiversity; D018533:Biomass; D002681:China; D065948:Grassland; D009584:Nitrogen / Q000494:pharmacology*; D013045:Species Specificity
chemical_list: D009584:Nitrogen