阔叶红松林主要树种光合与光谱反射特性及初级生产力研究

【目的】从生理角度探究阔叶红松林不同演替阶段的5个主要树种对光胁迫的适应性差异;揭示不同高度和不同冠层方向是否对叶片的光合特性、光谱反射特性以及相关生理功能性状产生影响;对各树种的有机物积累速率进行评估,为东北地区阔叶红松林初级生产力的研究提供参考。【方法】选取了阔叶红松林林冠层的5个乔木树种(春榆、紫椴、胡桃楸、蒙古栎和红松)进行研究,测定不同取样位置的叶片光合参数、光谱反射参数、比叶面积、元素含量等生理指标,进行方差分析与均值多重比较,建立各生理参数之间的相关关系,利用异速生长方程估算样地春榆、紫椴、胡桃楸、蒙古栎和红松种群的初级生产速率。【结果】(1)光合特性、光谱反射特性、比叶面积、叶片厚度和叶片元素含量等生理特征的种间差异显著(P<0.05)。红松的表观量子效率最低,暗呼吸速率和光补偿点均比其他树种高,比叶面积最小,叶片厚度最大,氮元素含量和钾元素含量最低;(2)各树种的光合特性、光谱反射特性、比叶面积、叶片厚度和叶片元素含量等生理特征在不同取样位置无显著差异(P>0.05);(3)阔叶树种的暗呼吸速率和光补偿点分别与光化学反射指数存在显著的种间负相关(P<0.05),线性拟合结果表明R^2分别高达0.96和0.94;(4)春榆、紫椴、胡桃楸、蒙古栎和红松种群的最大初级生产速率分别为4.806、1.637、1.981、0.350、0.106 kg/s。【结论】不同树种对光胁迫的适应性差异在光合特性和光谱反射特性上都有所表现,叶片光合特性与群落树种的更替密切相关,群落演替后期处于林冠层的植物对光环境的适应性决定了该群落的冠层物种构成;植物在15 m以下的不同高度和冠层方向的差异不足以引起叶片的光合生理特征产生适应性改变;春榆对群落生产力的贡献的最大,红松最小。

Photosynthetic,spectral reflectance characteristics and primary productivity of main tree species in broadleaved Korean pine forest

Objective  This paper aims to explore the adaptability of five main tree species in different succession stages of mixed broadleaved Korean pine forests (MBKPFs) to light stress from the physiological perspective; to reveal whether different heights and canopy direction have influences on photosynthetic characteristics, spectral reflectance characteristics and related physiological functions of leaves; to evaluate the organic matter accumulation rate of various tree species in order to provide reference for the study of primary productivity of MBKPFs in northeastern China. Method  Five species of arbor plants in the canopy of MBKPFs, Ulmus davidiana, Tilia amurensis, Juglans mandshurica, Quercus mongolica and Pinus koraiensis, were selected to determine the physiological index of photosynthetic characteristics, spectral reflectance characteristics and functional traits at different sample positions, conducting ANOVA and LSD test and establishing correlation between various physiological parameters, so as to estimate the primary productivity of each tree species with reference to the allometric biomass equation established by previous studies. Result  (1) There were significant differences in the photosynthetic characteristics, spectral reflectance characteristics, specific leaf area, blade thickness and leaf nitrogen content and potassium content among varied species (P < 0.05). The lowest apparent quantum efficiency, specific leaf area, nitrogen content and potassium content were found in P. koraiensis, with higher dark respiration rate, light compensation point and blade thickness. (2) There were no significant differences in the photosynthetic characteristics, spectral reflectance characteristics, specific leaf area, leaf thickness, leaf nitrogen content and potassium content among different sampling positions within species (P > 0.05). (3) Among species, dark respiration rate and light compensation point were significantly negatively correlated with PRI with R2 up to 0.96 and 0.94, respectively (P < 0.05), indicating that the adaptation of plants to light environment was reflected in both photosynthetic and spectral characteristics. (4) The maximum primary production rates of population were estimated with U. pumila of 4.806 kg/s, T. amurensis of 1.637 kg/s, J. mandshurica of 1.981 kg/s, Q. mongolica of 0.350 kg/s and P. koraiensis of 0.106 kg/s. Conclusion  The adaptability differences of tree species to light stress are reflected both in photosynthetic characteristics and spectral reflectance characteristics, and the photosynthetic characteristics of leaves are closely related to the community succession, in the later stage of which the adaptability of plants in the canopy layer to the light environment determines the canopy species composition of the community; the difference of plant height below 15 m and canopy direction is not enough to cause adaptive changes in photosynthetic physiological characteristics of leaves; U. pumila contributes the most to the community productivity while P. koraiensis contributes the least.