Stoichiometric characteristics of vegetation successional stages in karst area of northwest Guangxi

ObjectiveEcological stoichiometry of karst communities at different vegetation successional stages in north west Guangxi were explored to provide references for further understanding nutrient change regulation and nutrient limitation during vegetation succession and system stability of karst ecosystems in the vegetation succession process.MethodThrough establishing plots,sampling and laboratory analysis,the carbon(C),nitrogen(N)and phospuros(P) contents and stoichiometric ratio in plant,litter and soil of four successional stages(grass,shrub,secondary forest and primary forest)were analyzed.Variance analysis and correlation analysis were used to analyze their differences and corre-lations.ResultAlong the succession series,the contents of C,N and P in plant showed upward trend.C,N and P con-tents of litter were lower than those in plants.The performance of plant N and P reabsorption rate was as follows:primary forest>shrub>secondary forest>grass.The highest C and N contcent at 0-10 cm soil layer appeared in secondary forest. The highest P concent lied in shurb.C∶N,C∶P and N∶P ratios showed the rule of litter>plant>soil.Grass displayed the highest plant C∶N,plant C∶P and litter C∶N,and the lowest plant N∶P and litter N∶P.Primary forest showed the highest litter C∶P and litter N∶P.The highest plant N∶P ratio appeared in the secondary forest.C∶P and N∶P ratios in soil rose along the successional stage.There were significant correlations between C,N and P and their ratios in plants,litter and soil(P<0.05).ConclusionSoil nutrients have no direct impact on plant nutrients,but play an important role in plant growth.However,plant leaf N∶P ratios are mainly influenced by soil N and P.Plant growth is vulnerable to nutrient limi-tation in the early vegetation successional stages.