哈尔滨实验林场主要林分类型叶面积指数(LAI)的测定

Determination of LAI of Major Stand Types in Harbin Experimental Forest Farm

以哈尔滨实验林场为研究区,利用可以测量枝叶聚集程度的植物冠层分析仪作为叶面积指数(LAI)测量仪器,分别收集研究区水曲柳人工林和落叶松人工林的夏季LAI数据和冬季的木质部面积指数(WAI)数据,从植被面积指数(PAI)中移除木质材料的信息,获得叶子信息,修正了TRAC测量中所需参数——木质部占总植被面积的比率α,计算了哈尔滨实验林场的水曲柳林和落叶松林的叶面积指数。结果表明:研究区水曲柳林的LAI平均值为4.099,落叶松林的LAI平均值为5.176;水曲柳林的LAI与有效植被面积指数(PAI e)的平均值差别不大,这是由于水曲柳林的木质部分对叶面积指数的贡献与其叶片的聚集度效应基本相当,落叶松林的PAI e与LAI相差达到27%之多,针簇内部尺度的聚集度指数是造成这种差距的主要原因,所以对于针叶林的LAI测量必须要考虑叶子的聚集度效应;哈尔滨地区的水曲柳林TRAC改正参数α的参考值为0.24,哈尔滨地区的落叶松林TRAC改正参数α的参考值为0.30。

Taking the experimental forest farm of Harbin in Heilongjiang Province of Northeast China as study site,this paper measured the forest canopy LAI by TRAC （Tracing Radiation and Architecture of Canopies） which can measure foliage clumping index,in order to collect respectively LAI of Manchurian Ash and Larix in the summer and wood area index （WAI）of them in the winter.α （woody-to-total area ratio）required as one of the parameters in processing LAI with TRAC was corrected by the removement of woodiness material information （WAI） form vegetation area index （PAI）.Finally the LAI of the stand of Manchurian Ash and Larix was calculated.The results showed that at the study site,the average LAI of the stand of Manchurian Ash was 4.099 and the average LAI of the stand of Larix was 5.176.The LAI of the stand of Manchurian Ash was close to the LAI,which was due to that the contribution rate of the woody part of Manchurian Ash was nearly equal to that of the foliage clumping for LAI,but the LAI of the stand of Larix was 27％ larger than the PAIe,mainly because of the needle-to-shoot area ratio quantifying the effect of foliage clumping within a shoot,so the effect of foliage clumping must be considered for coniferous forest.The reference value of α was determined to 0.24 for the stand of Manchurian Ash,and the reference value of α was determined to 0.30 for the stand of Larix around Harbin.