Chin J Plan Ecolo ›› 2016, Vol. 40 ›› Issue (2): 165-.DOI: 10.17521/cjpe.2015.0210

• Research Articles • Previous Articles     Next Articles

Responses of growth of four desert species to different N addition levels

Ju-Ying HUANG1,*(), Hai-Long YU2   

  1. 1Center of New Technology Application and Research, Ningxia University, Yinchuan 750021, China

    2College of Resources and Environment, Ningxia University, Yinchuan 750021, China
  • Online:2016-02-10 Published:2016-03-08
  • Contact: Ju-Ying HUANG

Abstract:

Aims The increase in atmospheric N deposition has accelerated N cycling of ecosystems, thus altering the structure and function of ecosystems, especially in those limited by N availability. Studies on the response of plant growth to artificial N addition could provide basic data for a better understanding of how the structure of grasslands in northern China responds to increasing N deposition. Methods We investigated the seasonal dynamics of plant growth of four species after 2-year multi-level N addition in a field experiment conducted in a desert steppe of Ningxia in 2011. Plant biomass and the relative growth rate (RGR) of the studied species were measured and their relationships with C:N:P ratios of plants (community and leaf levels) and soils were analyzed. Important findings Results in 2012 showed that 2-year N addition promoted the growth of the four species and the effects were different among growth forms and were species-specific. In general, the plant biomass of the studied species was significantly correlated with leaf N concentration, leaf N:P ratio, community N pool, soil total N content and soil N:P ratio, while only weak relationships were observed between plant biomass and C:N and C:P ratios of plants and soils. In contrast, there was a significant linear relationship between RGR and N:P ratios both of plants and soils.Our results suggest that short-term N addition promoted the accumulation of plant biomass, and the species-specific responses to stimulated N addition can directly affect the structure of the desert steppe ecosystem. Plant N:P ratio and soil N:P ratio could indicate nutrient limitation of plant growth to a certain extent: N addition increased soil N content and N:P ratio, and thus relieved N limitation gradually. Once more N is available to plants, the growth of plants and the accumulation of community N was stimulated in turn.

Key words: C:N:P ecological stoichiometry, desert steppe, relative growth rate, increase in atmospheric N deposition, population biomass