Effect of ecological factors on plant communities of the Cele River Basin on the north slope of the middle Kunlun mountains

This research explored the relationships between environmental factors and vegetation patterns in the arid mountain ranges.The Cele River Basin on the north slope of the middle Kunlun mountains was selected as the study area to set up 63 plots at altitudes ranging from 1 960 to 4 100 m.Eighteen variables were used as indicators of spatial position,soil characteristics,and topography.The types of plant community in this region were investigated in relation to environmental factors using TWINSPAN,DCA and DCCA.In order to eliminate redundant environmental variables,the environmental factors which significantly influence plant community composition were chosen by forward selection and Monte Carlo tests.1) The plant communities in this region could be divided into 4 types by TWINSPAN.2) The results of DCA ordination indicated that the main factor restricting the distribution of communities was altitude.The number of species increased with increasing altitude.A comparison of the ordination of species with that of quadrats showed that the ordination plot of the dominant species in plant communities was similar to that of the plant community type.To some extent,the distribution of the former determined that of the latter.3) Six environmental variables (e.g.altitude) were used in the species-environment correlation analysis.The ordination result of DCCA indicated that altitude was more important than other environmental factors because the change of altitude gradient would lead to changes in both temperature and humidity gradients.The first axis indicated the gradient of altitude between communities,while the second axis was the pH gradient between communities.Compared with other areas,the scarcity of plant species and the differentiation of plant communities were obvious in the arid mountain range.The altitude was an important factor that influenced the plant species and vegetation patterns.Using methods of Quantitative Ecology better result of ecological relationships between vegetation and environment can be obtained.