The relationships between plant diversity, plant cover, plant biomass and soil fertility vary with grassland type on Qinghai-Tibetan Plateau

Biodiversity studies of grassland communities on Qinghai-Tibetan Plateau (QTP) produced dynamic results due mainly to environmental factors and anthropogenic activities. This study was designed to compare the plant diversity, plant biomass, plant tottal cover across different types of grasslands on the QTP. The various relationships between plant diversity indices such as Shannon-Weiner, Simpson, Evenness, and plant biomass, plant cover and soil elements were examined through correlation analysis. Further investigation was performed to examine the plant soil fertility-plant biomass and plant cover-plant biomass relationship using simple linear regression. We found a weak positive relationship between Evennes index and plant biomass, while a positive relationship was detected between plant cover and plant biomass. We suggested that grassland types and grazing affected the plant diversity-biomass-cover relationships on the QTP. Soil nitrogen (N), carbon (C), phosphorus (P) and Magnesium (Mg) were positively correlated with plant biomass, suggesting that soil nutrients rather than plant diversity played critical roles in regulating plant biomass accumulation in alpine grasslands. For a comprehensive understanding of the interconnections between plant diversity, plant cover, soil fertility and plant biomass, more studies should be done to probe into these relations and hence make a decision along this path.