Derivation of species interactions strength in a plant community with game theory

Derivation of species interactions function in a plant community and the quantified analysis of the effects of multi-species interactions poses a challenge because of the large number of interactions in a community. However, through the interaction with the local environment and resources as well as the adjustment of species richness and distribution frequency, the community will eventually reach the highest resources utilization efficiency to attain the status of an ecologically stable community. We developed the species-interaction function based on above characteristic of stable community and the evolutionarily stable strategies theory of game theory, the conditions of coexistence, and the maximization of the utilization efficiency of minimal restriction resources. We discovered that once the ability of different species to occupy an unoccupied or vacant place in a plant community (the competitive ability of species) has been realized to the maximum extent, the product of the community richness and the harmonic mean of the fitness of all species is equal to the product of the total amount of minimal restriction resources and the resources utilization efficiency of the community. The species-interaction strength further proves that the interspecific and intraspecific interactions strengths are unified in the process of competing for resources. Through validation with published species diversity data covering fifteen years of a grassland community, it is proved that our species interaction model was able to explain the changes of plant diversity in the communities with the minimum limitation resource changes with the impact of global climate changes.