Study On The Relationship Between Species Richness And Biomass Stability Of Experimental Plant Communities

The object of the experiment is to reveal whether there is a definite relationship between species richness and biomass stability in experimental community of subalpine meadow.We conducted a pot experiment with different species richness,species combinations,seeding densities and sowing ratio of three plant species?Festuca sinensis Keng.,Elymus nutans Griseb.,Roegneria nutans Keng.?under three levels of fertilization.We studied the effects of species richness,species composition,seeding densities,sowing ratio and fertilization levels on stability of plant community biomass,respectively.Data of the experiment showed that seeding density and sowing ratio had no significant effect on community biomass stability;Fertilization had significant effect on community biomass stability,while species richness and species composition had significant effects on community biomass stability under fertilization levels.The main results are as follows:?1?Fertilization significantly increased community biomass stability.Fertilization increased community biomass stability by increasing the mean of community biomass relative to community biomass standard deviation?S=?/??.Among them,the effect of low fertilization level?F₁?on community biomass stability is stronger than that of high fertilization level?F₂?.It may be for that fertilization is no longer a limiting factor to community biomass under high-level fertilization condition.?2?The effect of species composition on community biomass stability is higher than species richness and is affected by fertilization.Under the same conditions,the biomass of a particular composition is more stable.In the monoculture community,the biomass stability of Elymus nutans Griseb.(P₃₀)is higher;In the polyculture community,the biomass stability of combination of Festuca sinensis Keng.and Elymus nutans Griseb.(P₁₀E₁₀,P₁₀E₂₀,P₂₀E₁₀),or three species(Z₁₀P₁₀E₁₀)are higher.Species composition had no significant effect on community biomass stability without fertilization.Under the condition of fertilization,the asynchrony of species in a specific species composition community increased significantly,which significantly affected the stability of community biomass.?3?Fertilization affects the competition among species in the community,which in turn increases the asynchrony of species in the community.Under the fertilization conditions,the relative competitiveness of species in different combinations of species changed.On the other hand,the competition between species increases the asynchrony of species in the community.?4?There may be no direct correlation between species richness and community biomass stability.Under fertilization conditions,the positive linear regressive relationship between species richness and community biomass stability is only a representation.This representation is produced by that fertilization increase species asynchrony in a particular species composition community.