红松和紫椴叶片暗呼吸及其光抑制性在幼、成树间的差异

叶片暗呼吸是森林碳循环的重要组分,深入分析幼、成树的叶片暗呼吸及其光抑制性的差异,对生态系统总生产力(GPP)的准确估算具有重要意义.本研究以长白山阔叶红松林主要树种(红松和紫椴)的幼树和成树为研究对象,分别测算不同光照下叶片暗呼吸与无光暗呼吸,比较叶片暗呼吸及其光抑制性在幼、成树间的差异,结合幼、成树叶片生理生态参数的对比,对幼、成树叶片暗呼吸及其光抑制性差异的原因进行探讨.结果表明: 两个树种幼树叶片光下暗呼吸的值高于成树,在生长季(6—9月),幼树的值比成树高6.8%～39.6%;两个树种幼树叶片暗呼吸光抑制程度低于成树,幼树叶片暗呼吸光抑制性的值比成树低2.5%～14.1%;红松幼、成树间叶片暗呼吸光抑制性的差异总体高于紫椴幼、成树间叶片暗呼吸光抑制性的差异,差值最高可达18.6%;幼树中较高的光下暗呼吸值和较低的光抑制程度可能与最大净光合速率、比叶面积、气孔导度的变化有关,与叶片氮含量的变化无关.

Differences of leaf dark respiration and light inhibition between saplings and mature trees of Pinus koraiensis and Tilia amurensis.

Leaf dark respiration is an important component of carbon cycle. Understanding the differences of leaf dark respiration and light inhibition between saplings and mature trees is important for accurate estimation of ecosystem gross primary productivity (GPP). We meansured leaf dark respiration of saplings and mature trees of two dominant species (Pinus koraiensis and Tilia amurensis) in light and in darkness in the broadleaved-Korean pine mixed forest on Changbai Mountain. Differences of leaf dark respiration, light inhibition and leaf physiological and ecological parameters between saplings and mature trees were analyzed. The reason of differences on leaf dark respiration and the light inhibition were explored. The results showed that leaf dark respiration of saplings of two species under light was 6.8%-39.6% higher than that of mature trees in growing season. Light inhibition of leaf dark respiration in saplings was 2.5%-14.1% lower than in mature trees. The difference of light inhibition of leaf dark respiration between saplings and mature trees of P. koraiensis was higher than that of T. amurensis, with a maximum difference of 18.6%. The higher leaf dark respiration and lower light inhibition degree in saplings might result from the changes of max net photosynthesis rate, specific leaf area, and stomatal conductance, instead of leaf nitrogen content.