Study On Impact Factors On Species Diversity And Productivity Of Alpine Grassland Communities On The Qinghai-Tibet Plateau

Understanding Species richness could know the species distribution and adapt to growing conditions.Biomass is the carrier to reflect the material cycle and energy flow of grassland ecosystem,and evaluate the change of the functional value,growth status and morphological characteristics.They are two important characteristic value of plant communities.In this paper,we investigated 105 alpine grassland communities in the Qinghai-Tibet plateau and analyzed the responses of different grassland types,different functional groups,species diversity(abundance)and community productivity(biomass)to geographical factors and climatic factors.At the same time,the effects of various functional groups on the formation of grassland community structure were studied.The results show:(1)The species richness of meadow decreases with altitude,but the species richness of steppe increases with altitude.The relationship between the species richness of the sedges at altitude was independent of the grassland type.In addition,in the functional groups of the meadow,the sedges species richness increased significantly with the altitude,while the other functional groups decreased significantly.With the increase of annual average temperature,meadow species richness was significantly increased,while steppe species richness significantly decreased,and the sedges showed the same phenomenon.The graminoids species richness increased significantly with the increase of annual precipitation,and the forbs species richness increased significantly with the increase of sunshine hours,but they were also independent of grassland types.(2)The biomass of meadows decreased significantly with the increase of longitude,and all geographical factors had no significant effect on steppes biomass.The graminoids biomass was related to altitude,but it was not related to grassland type,and the relative interpretation of altitude in geographical factors was the highest,and both had a significant negative correlation.Annual precipitation and sunshine hours have significant effects on the biomass of the meadow.The meadow biomass significantly increased with annual precipitation,while decreased with increase sunshine hours,but the climatic factors had no significant effect on steppe biomass.The relationship between the biomass of the graminoids and the annual average temperature was not related to the type of grassland,and its biomass increased significantly with the increase of annual mean temperature.The climatic factors that have a significant impact on sedges are different.Meadow sedges were annual precipitation,and steppe sedges were annual average temperatures.(3)The meadow community productivity increased with the increase of forbs community productivity,while the steppe community productivity significantly increased with the increase of graminoids and forbs community productivity.The decisive factor of species diversity in meadows and steppe was weeds species diversity,and significantly increased with the weed species abundance.(4)The relationship between species richness and biomass of meadow functional groups was consistent with meadows,and had a significant positive correlation.In addition,the relationship between species richness and biomass of sedges was irrelevant to grassland type,and also both had a significant positive correlation.