Chin J Plant Ecol ›› 2019, Vol. 43 ›› Issue (5): 427-436.DOI: 10.17521/cjpe.2019.0046

• Research Articles • Previous Articles     Next Articles

Effects of nitrogen addition on plant community composition and microbial biomass ecological stoichiometry in a desert steppe in China

WANG Pan1,ZHU Wan-Wan1,NIU Yu-Bin1,FAN Jin1,YU Hai-Long1,LAI Jiang-Shan2,HUANG Ju-Ying3,*()   

  1. 1. College of Resources and Environment, Ningxia University, Yinchuan 750021, China
    2. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    3. Institute of Environmental Engineering, Ningxia University, Yinchuan 750021, China
  • Received:2019-03-05 Accepted:2019-04-23 Online:2019-05-20 Published:2019-10-18
  • Contact: HUANG Ju-Ying
  • Supported by:
    Supported by the High School Scientific Research Foundation of Ningxia, China(NGY2017003);The National Natural Science Foundation of China(31760144);The Natural Science Foundation of Ningxia, China(NZ17015)

Abstract: Aims Increasing atmospheric nitrogen (N) deposition accelerates soil N cycling, potentially resulting in decoupling of microbial biomass carbon (C):N:phosphorus (P), loss of plant species, and reductions of provision of ecosystem service. Studies on how the changes of elemental balance in microbes affect plant community composition, could provide a new insight for making clear the mechanism of N-induced loss of plant species. Methods We conducted a manipulative N addition experiment in a desert steppe in Ningxia, northwestern China to quantify the changes in plant biomass and species composition over two years. We analyzed the individual effects of microbial biomass C:N:P ecological stoichiometry and the joint effects with other key soil factors on plant community composition. Important findings The responses of plants to N addition appeared species-specific. The biomass of Salsola collina increased substantially; the biomass of Lespedeza potaninii decreased gradually. Other species showed slightly decreasing in biomass although statistically insignificant (p > 0.05). Along the N addition gradient, Shannon-Wiener diversity index, Simpson dominance index, and Patrick richness index of the plant community increased initially but decreased over time later. With increase in N addition level, the N content and N:P ratio of the microbial community increased, but the C:N ratio decreased. Plant community composition showed stronger correlations with microbial biomass N content, microbial biomass C:N ratio, microbial biomass N:P, soil NO3 --N concentration, soil NH4 +-N concentration, and the total P content of the soils. Microbial biomass C:N:P ecological stoichiometry explained <3% of the variation in aboveground plant biomass and community diversity index. Surprisingly, the joint influences from microbial biomass C:N:P ecological stoichiometry and other soil properties explained 51% of the variation in plant biomass and 26% of the change in plant community diversity. These results indicate that the effect of microbial biomass C:N:P ecological stoichiometry on plant community was highly related to the effects of other soil properties under N addition.

Key words: atmospheric nitrogen deposition, ecological stoichiometry, species diversity, degraded ecosystem