闽北天然阔叶林林层特征研究

闽北天然阔叶林乔木层垂直层次明显，一般可分２～３林层；全林树高变动大，其变动系数随主林层平均年龄增大而增大；各林层树高变动系数总体变化趋势是：第Ⅰ层＞第Ⅱ层＞第Ⅲ层（最高层），第Ⅲ林层树高变动系数随主林层平均年龄增大而减小，第Ⅰ及第Ⅱ林层树高变动系数随主林层平均年龄增大而增大；各林层株数组成总体变化趋势是：第Ⅰ层＞第Ⅱ层＞第Ⅲ层，各林层蓄积组成总体变化趋势正相反；第Ⅱ及第Ⅲ林层株数组成占全林的３１～３６％，蓄积组成却占９２～９４％．

Vertical Struture of Natural Broad-leaved Forest in North Fujian

The tree layer of matural broad-leaved forest in North Fujian is divided into three sublayers based on tree beight.The coefficient of height variation for the whole stand increased with average age of the overstory trees.In order of coefficients of height variation,sublayer Ⅰ>sublayer Ⅱ>sublayer Ⅲ.The coeffiment of height variation for sublayer Ⅲ decreased with average age of the overstory trees,but reverse for sublayers Ⅱ,Ⅲ.SublayerⅠ>sublayer Ⅱ>sublaper Ⅲ in order of stem density,but reverse in order of stand volume.The standing stems of sublayer Ⅱ and sublayer Ⅲ altogether account for between 31 percent and 36 percent of the total stems,but between 92 percent and 94 percent of the total stand volumes.