长白山自然保护区蒙古栎幼树生理生长特性随海拔梯度的变化

Physiological and growth variations of Quercus mongolica saplings along an elevational gradient in Changbai Mountain Nature Reserve,northeastern China

【目的】揭示长白山自然保护区蒙古栎幼树生理生长特征对海拔梯度的响应,以预测环境变化对该地区蒙古栎幼树生长的潜在影响。【方法】以长白山自然保护区不同海拔的林下蒙古栎幼树为材料,研究其叶片生理学、叶片形态学特性和植株生长特性对海拔梯度的响应。【结果】(1)蒙古栎叶片的比叶重和叶片干物质含量没有显著的海拔差异(P>0.05),而叶片的表观量子效率、光饱和点、光饱和速率、水分利用效率和表观CO2利用效率随海拔高度的增加呈下降趋势,即蒙古栎叶片的对弱光的利用能力、对强光的适应能力和最大光合潜力随海拔高度的增加而下降,生成单位有机物所需消耗的水分和胞间CO2随海拔高度的增加而增加;(2)蒙古栎植株的叶生物量、新生枝条生物量、一年生枝条生物量、叶生物量比重、新生枝条生物量比重和一年生枝条生物量比重随海拔高度的增加分别下降了64%、59%、60%、53%、45%和47%,即蒙古栎幼树的年生长量随海拔高度的增加而下降;(3)本研究中选择的叶片因子共解释了蒙古栎总生长变异的12.03%,选择的环境因子共解释了总生长变异的19.31%。【结论】蒙古栎幼树叶片生理性状和整株生长性状对海拔梯度的响应反映了该物种在异质生境中具有较强的叶片生理和整株形态可塑性。蒙古栎幼树的叶片的比叶重和干物质含量随海拔梯度没有显著变化,但其光合速率以及年生长量随海拔高度的增加而下降,即环境变化可能会通过影响蒙古栎幼树叶片的光合特征而非叶片的形态学特征进而影响蒙古栎幼树的生长。本文对预测蒙古栎在未来气候变化下的生理生态响应及演化方向具有一定意义。

[Objective]This paper aims to reveal the inner mechanisms of vegetation growth to elevational gradient and provide scientific basis for predicting the impact of climate change on vegetation growth of Quercus mongolica in Changbai Mountain Nature Reserve,northeastern China.[Method]We used the Quercus mongolica saplings under the canopy to evaluate leaf physiological characteristics,leaf morphological characteristics and plant growth characteristics of Quercus mongolica at different elevations.[Result]The results were as follows:(1)there were no significant differences(P>0.05)between the average needle leaf mass per area(LMA)and leaf dry mass content(LDMC)from various elevations.The apparent quantum yield,the saturation light intensity,the light saturated net photosynthesis,the water use efficiency and apparent CO2 use efficiency were negatively correlated with elevation,i.e.the ability to utilize low light,the ability to adapt to strong light and the maximum photosynthetic potential decreased with elevation,while the consumption of water and intercellular CO2 required for the production of organic matter increased with elevation.(2)Leaf biomass,new branch biomass,one year old branch biomass,leaf biomass proportion,new branch biomass proportion and one year old branch biomass proportion were also negatively correlated with elevation,i.e.the annual growth of Quercus mongolica saplings decresed with elevation.(3)All leaf factors in this study explained 12.03%of total growth variation,while all environmental factors in this study explained 19.31%of total growth variation of Quercus mongolica saplings.[Conclusion]The elevational responses of leaf physiological characters and whole plant growth characters of Quercus mongolica reflect that this species has strong plasticity in heterogeneous habitats.There is no significant difference in leaf mass per area and leaf dry mass content of Quercus mongolica from different elevations,but the photosynthetic rate and annual growth decrease with elevation,namely environmental variations may affect the growth of saplings by affecting the photosynthetic characteristics rather than the morphological characteristics of the leaves,in turn,affect the growth of Quercus mongolica saplings.This paper is of certain significance to predict the physiological and ecological response of Quercus mongolica under the future climate change.