Studying Mechanisms Underlying Species Abundance Distribution Under Nitrogen Addition Using Species Coexistence Theory

Species abundance distribution is one of the important patterns of biodiversity in nature.Studying the mechanism that determines the species abundance distribution is of great significance for understanding the structure,dynamics and construction of natural communities.This paper uses the modern coexistence theory to fit the LotkaVolterra competition model and quantify the intrinsic growth,niche difference and fitness difference of species based on the relevant data of three nitrogen addition experimental platforms(Nitrogen Addition Experiment in Haibei,Park Grass Experiment and Global Nutrient Network Experiment)spanning different temporal and spatial scales,so as to reveal how these parameters that determine species coexistence affect species abundance distribution and its change mechanism under nitrogen addition.The results showed that: 1)Under the control in Haibei nitrogen addition experiment,the control and nitrogen addition treatment in Park Grass experiment and nutrient network experiment,the log normal model fitting effect was better The log series model fitting was better under nitrogen addition treatment in the Haibei nitrogen addition experiment.2)In the Haibei nitrogen addition experiment,the intrinsic growth rate,niche difference,and fitness difference were significantly positively correlated with species abundance;in the Park Grass experiment,the intrinsic growth rate was significantly negatively correlated with species abundance,and the intraspecific competition coefficient and the interspecific competition coefficient was significantly negatively correlated with species abundance;in nutrient network experiment,the intrinsic growth rate,intraspecific competition coefficient,and interspecific competition coefficient were significantly negatively correlated with species abundance,and the niche difference and fitness difference were significantly positively correlated with species abundance.3)The change of interspecific competition coefficient in Haibei nitrogen addition experiment significantly affected the change of species abundance;the change of intrinsic growth rate,intraspecific competition coefficient and interspecific competition coefficient in Park Grass experiment significantly affected the change of species abundance;in nutrient network experiment the variation of fitness difference,intraspecific competition coefficient and interspecific competition coefficient significantly affected the change of species abundance.Overall,the results of these different experiments suggest that species coexistence mechanisms determine species abundance distributions and their changes under nitrogen addition.To sum up,this paper preliminarily reveals the intrinsic link between species coexistence mechanism and species abundance distribution,which deepens our understanding of species abundance distribution mechanism in grassland plant communities,and provides a basis for studying species abundance distribution patterns.new ideas...