The Dynamic Of Biodiversity And Stoichiometry Along The Succession Of Alpine Meadow

Community succession is a dynamic procedure. Some species were replaced byothers, and one plant community took the place of another along communitysuccession. The sduties on dynamics of community succession went on more than onecentury. Some ecologists have posed a lot of theories and mechanisms concerningvariation of plant community, relationships between plant community and habitatfactor along the succession and climax community.But there have been a unifiedtheory which can be applicable to all ecosystems, habitat and even the different stagesin the same succession series. Ecological stoichiometry was knowledge about theelement balance between plant and the habitat. It could provide an equilibrium systemfor studies on succession, and the theoretical foundation for studies on therelationships between plant and their habitat factor. Metabolic theory predicts howmetabolic rate, by setting the rates of resource uptake fromg the environmet andresource allocation to survial, growth, and reproduction, controls ecological processesat all levels of organization from individuals to the biosphere. Therefore, it provid ameans to reveal the changes of community along succession series from body sizeviews.In this paper, we tried to summarize a model about variation of body size andbiodiversity by ecological stoichiometry and metabolic theory of ecology which couldbe applicable to all ecosystems, take a secondary succession series of alpinemeadow communities as an example. The conclusions were given as follows:1. The numbers of species in community and their effection could be changedalong successional gradients. For feverfew, Ajania tenuifolium Tzvel dominated inearly successional community, Leontopodium leontopodiaoides Beauv. dominated inmid-successional community, and Artemisia tangutica Pamp dominated in latesuccessional community. The results shown that Ajania tenuifolium Tzvel was used tothe harsh natural environment in early successional stage, and the important effect offeverfew on plant community successiom. Diversity of plant life-forms in communitywas increased along the successional series.Important value of annual herbs slowlydescenden, important value of perennial herbs and shrub slowly increased with the succession stages. It shown that stabilization of community structure and ecologicalfunction of community were strengthend.2. In all successional field, Shannon-Weiner indices was remarkably positivelyrelated to soil available N, available P, and organic matter.It explained that soilavailable N, P and organic matter observably promoted the restoration of speciesrichness along succession series. The Simpson indices were positively related to soilphysico-chemical properties. It shown that soil physico-chemical properties influncedstructure of community, reduced numbers of dominant species in community, reducedimportant value of dominat species, and weaken effection of dominat species oncommunity structure and ecological function.3. According to RDA, the relationships between soil available N and P and plantstoichiometry was revealed. Soil available P was not related to plant stoichiometryand soil available N was postively related to plant stoichiometry in early successionstages. Plant stoichiometry was influnced more heavly by soil available N than soilavailable P in mid-succession stages. But the complexion was reversed in latesuccession stages. The relationships between soil available P and N and plantstoichiometry were more and more significant along succession stages as a result ofmore variances explained by all canonical axis.4. Based on metabolic theory of ecology and energy equilibium rules, therelationships between body size and succession time were displayed asfollows: ln((?)_t)=ln((?)₀)-4/3(ln(R₀)/t_B)t. This equation explained that average bodysize of the population declined with the community succession. As average body sizeof the population reached the critical average body size, individual could notreproduce and the population would be removed from the community succession.5. For organisms were four-dimensional fractal geometry objects, therelationship between body size and leaf area was displayed asfollows: A_i∝m_i^3/4 .Further, apparent leaf area index was derived based on last equation:LAI=σ₀(?)(m_i)^3/4/A=(ρ₀J)/A〈M^3/4〉_J=ρ₀ρ₀ was density, and a constantacross all species. To sum up the above arguments, we reached an equation about therelationships between species richness and aboundance and succession time:ln S_t2=ln S_t1+ln(ln R₀/t_Bm)t,ln J_t2=ln J_t1-ln(ln R₀)/t_Bm)t.