桂西北喀斯特地区植被不同演替阶段生态化学计量特征（英文）

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

【目的】探讨桂西北喀斯特地区植被不同演替阶段生态化学计量特征,为进一步了解植被演替过程中的养分循环和喀斯特生态系统的稳定性提供参考。【方法】通过野外样地设置、取样及室内试验,采用方差分析和相关性分析等经典统计方法对桂西北喀斯特地区四个演替阶段(草丛、灌丛、次生林和原生林)植物、凋落物和土壤的碳(C)、氮(N)和磷(P)含量、化学计量比及其相关性进行分析。【结果】植物C、N和P含量随植被正向演替呈增长趋势,凋落物的养分含量均低于植物。植物N和P再吸收率表现为原生林>灌丛>次生林>草丛。次生林中0~10 cm土壤以C和N含量最高,但灌丛以P含量最高。养分化学计量比C∶N、C∶P和N∶P在各层次中表现出一定的规律:凋落物>植被>土壤。在草丛中,植物C∶N、C∶P和凋落物C∶N最高,植物和凋落物的N∶P最低;凋落物C∶P、N∶P和植物N∶P分别出现在原生林和次生林;土壤C∶P、N∶P沿植被正向演替而增加。植物、凋落物和土壤中C、N和P含量及其化学计量比间存在显著相关(P<0.05)。【结论】土壤养分对植物养分含量影响不明显,但在植物生长过程中发挥重要作用;植物叶片N∶P受土壤N和P含量的影响;植物生长在演替阶段早期易受土壤养分限制。

【Objective】Ecological 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.【Method】Through 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 correlations.【Result】Along the succession series,the contents of C,N and P in plant showed upward trend.C,N and P contents 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).【Conclusion】Soil 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 limitation in the early vegetation successional stages.