苦竹叶片碳氮磷化学计量特征的海拔梯度效应

Concentration and its stoichiometrics of leaf carbon, nitrogen and phosphorus of Pleioblastus amarus forest from different altitudinal gradients

关键词:  苦竹, 海拔, 主要养分, 生态化学计量, 异速增长

Key words:  Pleioblastus amarus, altitude, main nutrient, ecological stoichiometry, allometric growth

摘要:

为揭示海拔梯度对苦竹林立竹叶片碳(C)、氮(N)、磷(P)化学计量特征的影响,该文以3个海拔梯度 [低海拔,(200±10)m; 中海拔,(400±10)m; 高海拔,(800±10)m]苦竹林为研究对象,测定1至3年生立竹叶片C、N、P含量,分析其化学计量特征和异速增长关系。结果表明:(1)立竹年龄对苦竹叶片C、N、P含量及其化学计量特征影响明显,随立竹年龄的增大,苦竹叶片C、N、P含量和N:P总体上均呈降低趋势,而C:N、C:P总体上呈升高趋势。(2)海拔对苦竹叶片C、N、P含量及其化学计量特征有重要影响,随海拔梯度升高,不同年龄立竹叶片C含量呈先升高后下降变化趋势,N、P含量总体上呈降低趋势,而C:N、C:P和N:P均呈升高趋势。(3)不同海拔梯度苦竹林立竹叶片C、N、P含量和C:N、C:P差异显著,中、高海拔苦竹林立竹叶片N:P无显著差异,均显著高于低海拔苦竹林; 不同海拔梯度苦竹林立竹叶片C、N、P间呈显著的正异速增长关系,随海拔梯度的升高,C-N、C-P异速增长指数显著升高,而N-P异速增长指数显著下降。综上结果表明,高海拔苦竹林虽然N、P利用效率提高,但立竹叶片C含量较低,P限制性作用增强; 中海拔苦竹林不但具有较高的N、P利用效率,而且立竹叶片C含量高,说明中海拔是苦竹林丰产培育的适宜海拔。

Abstract:

To reveal the influence of altitude on stoichiometrics of leaf carbon(C), nitrogen(N)and phosphorus(P)of Pleioblastus amarus, we determined the contents of leaf C, N and P for 1-3-year-old bamboo from stand at three different altitudinal gradients [low altitude,(200±10)m; middle altitude(400±10)m; high altitude,(800±10)m], and analyzed their stoichiometries and allometric growth. The results were as follows:(1)Bamboo age had great influences on the contents of leaf C, N and P and its stoichiometrics. With the increasing of bamboo age, the contents of leaf C, N, P and N:P ratios decreased overall, while ratios of C:N and C:P increased.(2)Altitude had significant effects on the contents of leaf C, N and P and its stoichiometrics. With the increase of altitudinal gradient, leaf carbon increased remarkably and then deceased sharply, while leaf N and P decreased overall, and leaf C:N, C:P and N:P increased generally.(3)There were significant differences existing in the contents of leaf C, N, P, C:N and C:P at different altitudinal gradients. Leaf N:P ratios of stands from the middle and high altitudes were higher than those of the low altitude. There was significantly positive allometric growth between leaf C, N and P. With the increase of altitudinal gradient, allometric exponent for leaf C-N and C-P increased remarkably, but that for N-P decreased dramatically. The results indicate that the P. amarus stand at the high altitude had the highest utilization efficiency of N and P, but its carbon content was lower and P limitation increased. While the P. amarus stand at the middle altitude had higher utilization efficiencies of N, P and the highest C content, therefore, it is the preferred altitude of high-yield cultivation for P. amarus forest.