滇中高原森林凋落物不同分解阶段C、N、P的化学计量特征及种间差异

【目的】为了解滇中高原磨盘山典型森林凋落物在不同分解阶段的化学计量特征,揭示滇中高原森林不同分解阶段凋落物的质量特征,为更好地促进滇中高原森林生态系统的凋落物分解进程和养分循环提供理论依据。【方法】以滇中高原的华山松Pinus armandii林、云南松Pinus yunnanensis林、高山栎Quercus semecarpifolia林、滇油杉Keteleeria evelyniana林、常绿阔叶林5种林地为试验区,人为地将自然状态下的森林凋落物分为未分解层、半分解层、已分解层,用以模拟凋落物的不同分解阶段,对不同分解层凋落物的碳氮磷(C、N、P)含量、化学计量比及元素释放率进行分析。【结果】1)随着凋落物分解程度的加剧,5种森林凋落物的C含量不断减少,P、N含量大体呈增加趋势,其中云南松林及华山松林的N含量呈先增加后减少的趋势,常绿阔叶林P含量为先减少后增加,且C、N、P含量在同一分解层中不同森林之间差异显著;2)5种森林凋落物的C∶N、C∶P随着凋落物分解程度的不断降低,云南松林的二者比值最高,N∶P在云南松林、华山松林和常绿阔叶林中先升高后降低,在高山栎林中先降低后升高,在滇油杉林中逐渐降低,且滇中高原森林凋落物C∶P和N∶P均显著小于全球平均水平;3)森林凋落物中C、N、P的总释放率均为滇油杉林>华山松林>高山栎林>云南松林>常绿阔叶林,常绿阔叶林前期元素释放效率快,后期减弱,华山松林和云南松林则相反,滇中磨盘山5种森林凋落物的化学元素易富集难释放。【结论】根据碳、氮、磷的化学计量特征表明,森林种间差异及不同的分解阶段会显著影响凋落物分解过程中的碳氮磷含量、化学计量比及其释放效率。

C,N and P stoichiometry at different stages of litter decomposition and interspecies comparison in central Yunnan plateau

【Objective】In order to study the stoichiometry of litter in central Yunnan plateau,and reveal the element metrological characteristics of litter in different decomposing stages of forest in the central Yunnan plateau,these results provided a comprehensive understanding of the litter.【Method】The Pinus armandii forest,Pinus yunnanensis forest,Quercus semecarpifolia forest,Keteleeria evelyniana forest and evergreen broad-leaved forest were taken as test areas,and the method of artificially dividing three litter layers including Un-decomposed layer(U),Semi-decomposed layer(S)and Decomposed layer(D)under natural conditions were used to simulate different litter stages,then analyzed the Carbon(C),nitrogen(N)and phosphorus(P)contents,its stoichiometric ratio and release proportion of three litter layers.【Result】The results showed that:1)When litter decomposition intensifies,for all the forest litter,the C content of decreased continuously and the P and N contents generally increased.The N content of the Pinus yunnanensis forest and the Pinus armandii forest increased first and then decreased,the N content of evergreen broad-leaved forest decrease first and then increase,and there were significant differences in the C,N,P content between different forests in different litter levels.2)When litter decomposition intensifies,the C∶N and C∶P of for all the forest litter decreased,and the C∶N and C∶P of Yunnan pine was the highest.The N∶P of the Pinus yunnanensis forest,the Pinus armandii forest and evergreen broad-leaved forest increased first and then decreased,the N∶P of Quercus semecarpifolia forest first decreased and then increased,the N∶P of Keteleeria evelyniana forest gradually decreased.Overall,litter C∶P and N∶P of forest in central Yunnan plateau were significantly lower than the global average.3)The C,N,and P release proportion of forest litter:Keteleeria evelyniana forest>Pinus armandii forest>Quercus semecarpifolia forest>Pinus yunnanensis forest>evergreen broad-leaved forest,the nutrient content rapid release of evergreen broad-leaved forest in the early stage and weakened in the later stage,the Pinus armandii forest and the Pinus yunnanensis forest are the opposite.Then,the nutrient content of forest litter in central Yunnan plateau is easy to enrich and difficult to release.【Conclusion】According to the C,N and P Stoichiometry,it’s shown that the forest interspecies comparison and different stages of litter decomposition significantly affected C,N,P contents and its stoichiometric ratio and release proportion in the process of litter decomposition.