塞罕坝华北落叶松针叶光响应指标变化规律及其影响因素

以河北省塞罕坝机械林场华北落叶松人工林为研究对象,比较潜在最大光能利用效率(LUE_max)、潜在最有效光照强度(PAR_e)、光补偿点(LCP)和光饱和点(LSP)在树冠不同垂直位置和不同物候期的差异,并分析其主要影响因素。结果表明: LUE_max在树冠垂直方向随着冠层深度的增加而增大,PAR_e、LCP和LSP则随冠层深度的增加而减小,表明上层针叶对强光具有更高的利用效率而下层针叶能更高效地适应弱光环境。LUE_max在生长季内随着叶片发育呈现出逐渐增加的趋势,但在7月有所下降;其余指标均呈现出“单峰”的变化趋势。环境因子与光响应指标显著相关,主要原因是叶片气孔对周边环境的应激反应。了解光响应指标的垂直及物候期变化规律对制定科学的经营措施、优化林分结构、改善局部微环境、最大限度提高森林生产力有重要意义。

Changes of light response indicators and its impact factors of Larix principis-rupprechtii on Saihanba Forest Farm,China.

We examined the differences of maximum light use efficiency (LUE_max), most effective light intensity (PAR_e), light compensation point (LCP) and light saturation point (LSP) in diffe-rent vertical positions and different phenological periods of tree crown in Larix principis-rupprechtii plantation in Saihanba Mechanical Forest Farm of Hebei Province. We analyzed the main influencing factors for all the variables. The results showed that LUE_max increased with the increasing crown depth, and that PAR_e, LCP and LSP decreased with the increasing crown depth. Such a result indicated that upper crown had higher utilization efficiency to strong light and that the lower crown was more efficient to adapt to weak light environment. During the leaf development in the growth period, the LUE_max approximately increased except in July, while the changes of other photosynthe-tic-light factors showed a tendency of unimodal curve. Environmental factors were significantly correlated with the indices of light response, mainly due to the stress reaction of leaf stomata to surrounding environment. Understanding the spatial and seasonal changes of the photosynthetic-light indicators was important for formulating scientific management measures, optimizing stand structure, improving local microenvironment and maximizing forest productivity.