Effects Of Fertilization And Clipping On Species Diversity, Productivity, Community Structure And Their Relationship In Subalpine Meadow

The objective of this study was to determine whether fertilization and clipping would affect species diversity, productivity, community structure, species composition and the relationship between species diversity and productivity in a subalpine meadow of China. In other words, to explore how the interaction effects on the interaction between species diversity and productivity. To explore ecological mechanisms of the relationship between plant community productivity and species diversity. The experiment was set up as a randomized block design consisting of three levels of fertilization and three intensities of clipping with eight replications, using quadrat size of0.5×0.5m2. The aboveground biomass and species diversity were measesured within each quadrat. The relationship between species diversity and productivity were tested by plotting aboveground biomass against species diversity based on linear and non-linear regressions by treatments. The main results are as follows:1). Fertilization and clipping had significant effects on aboveground biomass, species diversity, total plants number, Simpson index and Shannon-Wiener index during2008-2013(p<0.05), but fertilization and clipping had not identical influence in each year.2). Fertilization and clipping had significant effects on aboveground biomass (p<0.05); community biomass increased with the level of fertilization but decreased with the clipping intensity. Both fertilization and clipping had no apparent effects on species diversity.3). Through the analysis of plant community functional group changes and four typical species important value display response to fertilization and mowing:Fertilization increased the important value of Elymus nutans Griseb., decreasing the important value of Agropyron cristatum (L.) Gaertn., but no consistent effect of Picirs hieracioides L.subsp. and Gueldenstaedtia Verna (Georgi) Boiss. The proportion of Poaceae decrease with clipping, the proporition of Asteraceae and weeds increase with clipping times.4). The relationships between year and aboveground biomass, between year and species diversity are significant positive correlation (p<0.05). However, analysis each year interrelation, only2009present Negative linear and quadratic relationship, other years non-correlated. 5). The relationships between aboveground biomass and species diversity occurred as monotonic, quadratic, or non-correlated depending on fertilization and clipping treatments in each year from2008to2013.The results show that the relationship between species diversity and productivity is not always isotropic and changes with conditions of fertility and level of biomass removal in the community. Thus, productivity is unlikely related to species diversity under conditions of varying fertilization regimes and clipping treatments.