Plant Diversity And Its Relationship With Productivity Of Typical Steppe In Xilin River Basin

The relationship between biodiversity and ecosystem functions is one of core issues in ecology.A total of 143 representative samples in the typical Steppe of Xilin River Basin,Inner Mongolia,were chosen in this study to reveal main environmental factors affecting productivity were determined and key factors influencing the relationship between biodiversity and productivity.Through field observations about vegetation,plant functional traits and soil,we acquired species diversity(SD),function diversity(FD),productivity,and soil nutrient data(total nitrogen,TN;total phosphorus,TP;available nitrogen,AN;available phosphorus,AP).By combining with environmental factors,including mean annual precipitation(MAP),mean annual temperature(MAT),aridity index(AI),grazing intensity(sheep density data,D)and soil nutrients,this study analyzed characteristics of SD and FD of three formations of typical Steppe and the relationship among these diversity indices with productivity.The main conclusions are as follows:1.The study divided typical Steppe in Xilin River Basin into three formations:Leymus chinensis,Stipa grandis and Stipa krylovii.2.Regarding SD,L.chinesis formation's SD was higher;as for community-weighted mean trait(CWM),the CWMLw showed L.chinensis formation>S.grandis formation>S.krylovii formation,and these three emerged significant difference.The CWMSLA of L.chinensis formation was significantly smaller than that of S.grandis and S.krylovii formation;The CWMH of S.grandis formation was significantly higher than L.chinensis and S.krylovii;regarding multidimensional function diversity index,S.grandis formation's functional diversity index was higher than the others,whose functional richness and S.krylovii formation's,functional specialization index and L.chinensis formation's,Rao quadratic entropy index and L.chinensis formation's and S.krylovii formation's had significant difference.3.In terms of different formations,the relationship between SD and productivity was weaker,while the relationship between FD and productivity was stronger,which is characterized by three formations' CWMH and productivity were significant positive correlated,the CWMLA and productivity in L.chinensis formation and S.krylovii formation were very significant positive correlated,CWMLW in L.chinensis formation and productivity significantly were positively correlated;in terms of multidimensional function diversity index,functional richness,functional specialization index and Rao quadratic entropy index was significantly positive related to productivity in L.chinensis and S.krylovii formation.4.There were significantly negative correlations between Shannon-Weaver index and productivity for the whole typical Steppe in Xilin River Basin.CWMLA,CWMH were an extremely significantly positive correlation with productivity;and functional richness index was significantly positive related to productivity;Rao quadratic entropy index and functional specialization index were very significantly positive correlations with productivity.5.The content of soil TN,TP and AN on the whole typical Steppe and its formations had a greater influence on productivity,AI,AMT and AMP was just in the whole typical Steppe and S.krylovii formation closely related to community productivity.6.In the whole typical Steppe and its formations,CWMH had the highest explanation power for productivity variation,which illustrated the selection effect was the dominant mechanism to maintain the relationship of FD and productivity in typical Steppe of Xilin River Basin.On the other hand,there was the significantly positive correlation between Rao quadratic entropy index and community productivity,which indicated that complementary effect also played a major role to maintain the relationship between FD and productivity.