Effects of Soil Physico-Chemical Properties on Plant Species Composition and Diversity Along an Elevation Gradient Over Alpine Grassland on the Qinghai-Tibetan Plateau, China

Abstract

Background and aims Alpine grassland on the Qinghai-Tibetan Plateau (QTP) is sensitive and fragile, and it is subject to serious degradation. It is essential to determine the effects of soil parameters on plant species to explain grassland degradation. Methods We classified plant communities into six types based on hierarchical clustering. Then we analyzed the effects of soil physico-chemical properties on plant species composition and diversity by canonical ordination and spatial regression from an elevation perspective. Results Elevation class had significant effects on soil moisture content, soil pH, and soil available nitrogen content. The primary soil parameter affecting plant species composition and diversity in alpine grassland was soil available nitrogen content. The effect of soil available nitrogen content on plant species richness varied at different elevations. For Gramineae plants (G), plant species richness declined with the increase in soil available nitrogen content at low elevation, but rose at middle elevation. Soil available nitrogen content had a more significant limiting effect on species richness at high elevation. Conclusion Analyzing the relationship between plant species and soil physico-chemical properties increases our understanding of grassland degradation, and will improve grassland restoration programs and responses to climate change.