毛竹林叶片碳氮磷化学计量特征的海拔梯度效应

The Response of Stoichiometry of Leaf Carbon,Nitrogen and Phosphorus of Phyllostachys edulis Forests to Altitude

毛竹是中国重要的经济竹种,区域上具有明显的垂直分布特点。为揭示毛竹林叶片碳氮磷化学计量特征的海拔梯度效应,为毛竹林科学的林分管理与土壤养分补充提供理论依据,测定了3个海拔梯度毛竹林叶片碳(C)、氮(N)、磷(P)含量,分析了其化学计量特征和异速增长关系。结果表明:随着立竹年龄的增大,毛竹林立竹叶片碳、氮、磷含量及N∶P均总体上呈降低趋势,而C∶N、C∶P则总体上呈升高趋势,1度立竹叶片碳、氮、磷含量均显著高于2度、3度立竹,且后2者间碳、氮、磷含量及其化学计量比均无显著差异。随海拔梯度的升高,毛竹林叶片碳含量略有降低,而氮、磷含量呈降低趋势,其中,中、低海拔叶片氮、磷含量显著高于高海拔,且前2者氮含量无显著差异,而磷含量差异显著;叶片C∶N、C∶P、N∶P均呈上升趋势,其中,中、低海拔叶片C∶N显著低于高海拔,中、高海拔叶片N∶P显著高于低海拔,叶片C∶P海拔梯度间差异显著,其他均无显著差异;不同海拔梯度毛竹林叶片碳、氮、磷间呈显著的正异速增长关系,随海拔梯度的升高,C-N、C-P异速增长指数显著下降,而N-P异速增长指数显著提高。研究表明,随海拔梯度的升高,毛竹林叶片氮、磷含量降低,利用率提高,P素限制性作用增强,建议在高海拔毛竹林经营中宜适当增加磷素的补充。

Phyllostachys edulis is the most important economic bamboo species,and distributes vertically along altitudes. The stoichiometry of leaf carbon,nitrogen and phosphorus of Phyllostachys edulis forests at various altitude was studied,so as to guide the management and fertilization of Ph. edulis forests. The concentrations of leaf carbon,nitrogen and phosphorus of Ph. edulis forests at three different altitudes were determined,and stoichiometry and allometry were analyzed. The results showed that the concentration of leaf carbon,nitrogen and phosphorus and N∶P ratios decreased,while ratios of C∶N and C∶P increased with bamboo age increasing. Furthermore,the concentration of leaf carbon,nitrogen and phosphorus of the 1 st age class bamboos were all higher than that of the 2 nd and 3 rd age class bamboos., There were no difference in the concentration and its stoichiometry of leaf carbon,nitrogen and phosphorus between the 2 nd and 3 rd age class bamboos. With the altitude increasing,leaf carbon deceased slightly,while leaf nitrogen and phosphorus decreased greatly,. Of which,leaf nitrogen and phosphorus of Ph. edulis from low and medium altitude were all higher obviously than that of high altitude. No significant difference in leaf nitrogen of between low and medium altitude was observed,but the difference in leaf phosphorus between them was significant. With the altitude increasing,leaf C∶N,C∶P,N∶P ratios increased dramatically. Leaf C∶N of low and medium altitude were greatly higher than that of high altitude,and leaf N∶P of medium and high altitude were obviously higher than that of low altitude. There were significant differences of C∶P among the three altitudes. With the altitude increasing,leaf C∶N,C∶P,N∶P ratios increased. Leaf C∶N of low and medium altitude were greatly higher than that of high altitude,and leaf N∶P of medium and high altitude were obviously higher than that of low altitude. There were significant differences of C∶P among the three altitudes. There were significant positive allometric growth among leaf carbon,nitrogen and phosphorus. With the altitudes increasing,allometric exponent between leaf carbon-nitrogen,and carbon-phosphorus decreased obviously,and that of N-P increased dramatically. Thus,with the attitude increasing,the leaf nitrogen and phosphorus decreased,and their use efficiency increased greatly,yet,phosphorus limitation to Phyllostachys edulis growth enhanced. So more phosphorus should be added at high altitude during the bamboo management.