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利用Li-6400光合测定系统,研究了长白山阔叶红松林4个不同尺度林窗内光照强度的异质性,分析红松幼树在林窗内9个方位的光合作用日变化特征.结果表明:林窗内9个方位出现光合有效辐射(PAR)峰值顺序为:西实际林窗、北扩展林窗、林窗中心>南实际林窗、南扩展林窗、东扩展林窗、东实际林窗>西扩展林窗、北实际林窗,光照呈东-西、南-北不对称分布,光照梯度在西、北方向变化较大,但各方向距中心不同距离的日均PAR无显著差异.林窗Ⅰ~Ⅳ日均PAR分别为21.85、45.57、66.02和23.48μmol.m-2.s-1,相互之间均达显著差异水平(P<0.05).PAR与净光合速率(Pn)呈显著正相关,且相关系数随PAR增大而增大.随林窗面积的增大,PAR和Pn均先增大后减小;当林窗面积为267 m2时,二者同时达到最大值.
Li-6400 photosynthesis system was used to study the heterogeneity of light intensity in four different size gaps of broad-leaved Korean pine forest in Changbai Mountains. The diurnal variation of photosynthesis of young Korean pine trees in nine directions was analyzed. The results showed that : The order of peak PAR of photosynthetic active radiation (PAR) appeared in 9 directions in the canopy was: West Actual Gap, North Extended Gap, Gap Center> South Real Gap, South Gap, East Gap, East Gap Window> west expansion gap window, north actual gap window, the illumination is east-west, south-north asymmetric distribution, the illumination gradient changes greatly in the west and north directions, but there is no significant difference in average daily PAR at different distances from the center (P <0.05) .PAR and net photosynthetic rate (Pn) were significantly higher than those in control group (P <0.05) (P <0.05), while PAR and Pn increased at first and then decreased with the increase of PAR.When the area of GAP was 267 m2, the two reached the maximum at the same time .