Self-thinning is a ubiquitous phenomenon that observed in plant and animal populations.The quantitative description of self-thinning process has a high value for ecological theory and applications,and is considered as one of the few laws in ecology.However,empirical studies found that the self-thinning trajectory is variable and the justifiable value of self-thinning exponent is still under debate.Although different factors such as different modes of competition(symmetric versus asymmetric),abiotic stress,initial density and initial spatial pattern were suggested to affect self-thinning process,the effects of different modes of facilitation on self-thinning has not been studied which has been proved to affect plant population dynamics.