不同光照条件下华北落叶松更新木的光响应曲线

以华北落叶松为研究对象,在林隙和林缘两种光照条件下设置标准地,利用LI-6400便携式光合测定系统对不同年龄更新木进行光响应曲线参数测定和分析,建立了更新木的直角双曲线光响应曲线模型,并分析了光补偿点(LCP)、暗呼吸速率(Rd)、初始斜率(α)和最大净光合速率(Pmax)等参数。结果表明:林隙光照下三个年龄阶段更新苗的α、LCP、Rd值表现一致,均是幼树中等幼苗小幼苗,而Pmax值是幼树小幼苗中等幼苗;林缘光照下三个年龄阶段的α、LCP、Rd也一致表现为中等幼苗幼树小幼苗,而Pmax值是中等幼苗小幼苗幼树;同一年龄阶段的更新木α值表现为林隙大于林缘。而LCP值则为林缘高于林隙。Rd值则表现较为复杂,小幼苗和中等幼苗是林隙小于林缘,而幼树则相反。Pmax值在不同年龄阶段的更新木间也表现不一致,小幼苗和幼树是林隙大于林缘,而中等幼苗却相反。该研究揭示了不同光照条件下不同年龄阶段的华北落叶松更新木间光能利用特点差异的生理学基础,将为华北落叶松林分的可持续经营提供理论依据。

Light Response Curves of Larix Principis-rupprechtii Seedlings in Different Light Environments

The authors studied the light response characteristics of naturally regenerated Larix Principis-rupprechtii seedlings and saplings growing in forest gaps and forest edges by measuring and analyzing the light response curves with a Li-6400 portable CO2 analyzer.A rectangle hyperbole model of photosynthesis was established to calculate the light compensation point,respiration rate,the initial slope of light response curve and the maximum net photosynthetic rate with measurements.The results showed that the light compensation point,respiration rate and initial slope of light response curve were highest in saplings followed by medium and small seedlings in forest gap and were highest in medium seedlings followed by saplings and small seedlings in forest edge.The maximum net photosynthetic rates of the seedlings and saplings under both light environments did not show consistent patterns.This study laid a foundation for reviewing the regeneration mechanisms of conifer forest in the cold-temperate climate zones,and provided the theoretical support for the sustainable management of Larix Principis-rupprechtii stands,especially from natural regeneration origin.