Ecological Stoichiometric Characteristics Of Carbon, Nitrogen And Phosphorus Of Plants, Soil And Microorganisms In Succession Of Evergreen Broad-Leaved Forest In Tiantong

Forest succession affects ecological processes such as plant carbon(C)nitrogen(N)and phosphorus(P)distribution,soil C,N,and P transformation,and microbial nutrient metabolism.Clarifying the C,N,and P ecological stoichiometry characteristics and coupling relationships of different components of the ecosystem(plants,soil,and microorganisms)during forest succession can improve the theoretical framework of forest succession and provide scientific support for natural restoration and conservation of forests.At present,there are few systematic studies on the effects of subtropical evergreen broad-leaved forest succession on the ecological stoichiometry and coupling relationship of plant,soil and microbial C,N,P,especially the C,N,P limitation of microorganisms and the C,N,P homeostasis of plants and microorganisms under the succession of evergreen broad-leaved forest.In view of the above research deficiencies,this paper relies on the sample plots of the early,middle and late succession stages of the evergreen broad-leaved forest in Tiantong,Zhejiang Province.By measuring the C,N and P contents of dominant plant leaves,branches and roots at different succession stages,and the C,N and P contents and enzyme activities of soil and microorganisms at different depths,this paper analyzes the changes of C,N and P ecological stoichiometry characteristics of plants,soil and microorganisms with forest succession,analyzes the correlation between C,N and P ecological stoichiometry characteristics of plants,soil and microorganisms,and quantifies and compares the C,N and P homeostasis of different organs and microorganisms of plants.The main results are as follows :(1)The succession of evergreen broad-leaved forest significantly affected the ecological stoichiometric characteristics of C,N and P in plant,soil and microorganism.The effects of forest succession on the ecological stoichiometry of C,N and P in leaves and roots were significant,and the trend was consistent.The effects of forest succession on the ecological stoichiometry of C,N and P in branches were small.With forest succession,the content of C in leaves changed little,ranging from 458.2to 481.7 g / kg.The content of N in leaves decreased first and then increased,while the content of P in leaves was the highest in the late succession stage.The C : N and C : P in leaves increased significantly first and then decreased significantly,and the N : P in leaves decreased in the late succession stage.With the succession of forest,the relative stoichiometric values of C,N and P among plant organs were basically stable,showing leaf > branch > root.The effects of forest succession on the stoichiometry of C,N and P in topsoil were significant.With the forest succession,the content of TP in 0-20 cm soil depth decreased significantly.The contents of C,N and P in forest soil at different succession stages decreased with the increase of soil depth.At each forest succession stage,soil microorganisms were limited by phosphorus,and with forest succession,microbial carbon and phosphorus limitations gradually increased.(2)There was a coupling relationship between plant,microorganism and soil carbon,nitrogen and phosphorus ecological stoichiometry in the succession of evergreen broad-leaved forest.Soil C and microbial biomass C,leaf N,leaf C : N,soil P and leaf N : P,soil C : N and leaf P,leaf C : P,leaf N : P,soil C : P and leaf C : N had significant correlation.With forest succession,the internal stability of leaf N,P,C : N,C : P and N : P,branch C and root N : P increased.The internal stability of N and C : N in branches was higher than that in leaves and roots at different succession stages.The stability of leaf C in forest succession plants was higher than that of microorganisms,but the stability of plant N : P was lower than that of microorganisms.This study found that the succession of evergreen broad-leaved forest can obviously affect the carbon and phosphorus limitation intensity of microorganisms,and change the internal stability of carbon,nitrogen and phosphorus of plants and microorganisms,which is related to the distribution strategy of carbon,nitrogen and phosphorus of plants and the change of microbial nutrient metabolism after forest succession.This study deepens the understanding of forest succession on the ecological stoichiometry of plant,soil and microbial carbon,nitrogen and phosphorus and their coupling relationship,and further illustrates the necessity of understanding forest succession process from the perspective of plant and microbial ecological stoichiometry,which is helpful to improve the theoretical framework of evergreen broad-leaved forest succession.