热带山地雨林不同结构与功能幼树的叶片特征比较

Comparison of Leaf Traits of the Saplings of Different Structural and Functional Species in Tropical Montane Rain Forest

植物的生理生态特征决定了植物在生态系统中的分布模式和物种的丰度。在样地调查的基础上,应用Li-6400光合测定系统,研究了海南热带山地雨林3个层次的6个优势种与10个伴生种的光合作用参数,并测定了相应叶片的比叶面积。结果表明:16个树种的比叶面积为71.16~139.90 cm2·g^(-1)、单位面积最大光合速率(A-area)为2.95~13.27μmol·m^(-2)·s^(-1)、单位干质量最大光合速率(A-mass)为22.7~126.5μmol·kg^(-1)·s^(-1),单位面积暗呼吸速率(Rd-area)为0.02~1.15μmol·m^(-2)·s^(-1)、单位干质量暗呼吸速率(Rd-mass)为0.19~12.61μmol·kg^(-1)·s^(-1),光补偿点(LCP)为2.5~32.2μmol·m^(-2)·s^(-1),表观量子效率(Ф)为0.006 6~0.042 8μmol·μmol^(-1)。幼树的比叶面积随物种成树所在层次降低而减少(上层种>中层种>下层种),与单位干质量最大光合速率的次序一致,而与光补偿点的次序相反,但差异均不显著(P>0.05)。中层种的幼树具有较高的暗呼吸速率和表观量子效率。优势种的单位面积最大光合速率显著大于伴生种(P<0.05);优势种的单位质量最大光合速率、暗呼吸速率(Rd)和表观量子效率也大于伴生种,但差异不显著(P>0.05);优势种的比叶面积和光补偿点低于伴生种,但差异不显著(P>0.05)。优势种的暗呼吸速率和比叶面积显著正相关(P<0.05);伴生种的暗呼吸速率和比叶面积不相关(P>0.05)。不同类型幼树的叶片结构与功能的生态位分化,从功能性状的角度,为热带雨林维持高生物多样性以及保持物种长期共存提供了一个可能的解释。

We studied the differences of leaf traits between dominant species and companion species, and differences among three different layers. Based on sample-plot survey, leaf traits of six dominant species and ten companion species from three different layers of tropical montane rain forest were measured in Hainan Island, by using a Li-6400 portable photosynthesis system. Leaves were sampled to measure its specific leaf area （SLA）. SLA and A of saplings decreased with their ma- ture tree height reducing, and had the descending order of upper layer species, middle layer species and lower layer spe- cies, while the order of LCP was opposite, but there were no significant differences among three groups （P〉0.05）. Middle layer species had a higher Rd and Ф than those of the other. A-area of dominant species was significantly higher than that of companion species （P〈0.05）. Their -massm Rd and Ф were also higher than those of companion species, while their SLA and LCP were lower than those the latter, but there was no significant difference here （P〉0.05）. Rd of dominant species was positively correlated with SLA （P〈0.05）, but for companion species there was no correlation between Rd and SLA （P〉 0.05）. The ecological niche differentiation of leaf structure and function of different type saplings provides a potential expla- nation for the high diversity of tropical rainforest.