The impacts of geographic, soil and climatic factors on plant diversity, biomass and their relationships of the alpine dry ecosystems: Cases from the Aerjin Mountain Nature Reserve, China

Abstract Spatial patterns of plant species diversity, functional diversity, and aboveground plant biomass, and their relationships with environmental factors in the Aerjin Mountain Nature Reserve (AMNR) on the Qinghai-Tibetan Plateau, China were examined in this study. The transect-quadrat sampling method was applied to sample the plant species and functional diversity and the aboveground plant biomass. Statistical package F-diversity v. 2011 was used to calculate the functional diversity index. OriginPro 9.0 drawing software was used to diagram 3-dimensional (longitudinal, latitudinal, and altitudinal) distribution patterns of plant diversity, plant biomass and environmental factors. Correlations among plant biomass, species diversity, functional diversity, and environmental factors were analyzed by using SPSS16.0. The results indicated that alpine steppe was the major vegetation type in high-altitude areas of the southwestern region of the AMNR, alpine wet meadow and alpine steppe were the major vegetation types in low altitude areas of the northeastern region of the AMNR. The vegetation types in mid-altitude areas of the northwestern region and low altitude areas of the southeastern region of the AMNR were primarily alpine desert. Plant species diversity and biomass did not vary significantly along latitudinal, longitudinal, and altitudinal gradients. Plant species diversity was positively correlated with soil total nitrogen, total carbon, organic carbon, and moisture. The functional diversity of the plant community was positively correlated with precipitation and soil moisture. Vegetation biomass was positively correlated with soil total nitrogen, organic carbon, and soil moisture, whereas it was negatively correlated with soil bulk density. Plant species diversity was positively correlated with the functional diversity of the plant community. The integrated effects of geographic factors, soil factors, and meteorological conditions contributed to the spatial heterogeneity of species biodiversity and vegetation biomass of the plant communities in the AMNR, whereas the effects of soil and climatic factors were much stronger than those of geographical factors.