金沙江干热河谷局部小气候对苏门答腊金合欢、新银合欢自然更新的影响

Regeneration of Acacia glauca and Leucaena leucocephala Plantations in Jingsha Dry and Hot Valley

通过样地调查,比较了苏门答腊金合欢和新银合欢纯林在金沙江干热河谷不同地段林分结实量、种子散布格局、种子密度及幼苗、幼树数量,并对影响天然更新的因素进行了分析;同时,使用灰色关联度法对2个树种在不同地段、同一地段的天然更新进行了综合评价.结果表明:随着距母树距离的增加,苏门答腊金合欢林地种子密度减少的幅度较新银合欢小,新银合欢种子的传播距离为80～90 m、苏门答腊金合欢为100～110 m.新银合欢在金沙江干热河谷上段(鹤庆)、中段(元谋)、下段(东川)关联系数为0.333 3、0.744 9、0.957 7;苏门答腊金合欢为0.555 6、0.884 3、0.459 0;同一试验点新银合欢的关联系数比苏门答腊金合欢高0.222 2、0.444 5、0.444 5.新银合欢在金沙江干热河谷下段(东川)的天然更新状况最好,在上段(鹤庆)表现最差;苏门答腊金合欢在金沙江干热河谷中段(元谋)的天然更新状况最好,在下段(东川)表现最差;而在整个金沙江干热河谷流域,新银合欢的天然更新情况好于苏门答腊金合欢.

Sample plot investigation revealed the seed yield,seed dispersal pattern,seed density and quantity of seedlings of Acacia glauca and Leucaena leucocephala plantations in Jingsha dry and hot valley and factors affecting the natural regeneration in different plots were analyzed.A comprehensive evaluation by gray correlational analysis of the two species regarding their natural regeneration at different reaches or at the same reaches of the valley was made.The result showed that with the distance to mother tree increased the seed density of A.glauca declined but less than L.leucocephala did.The seed dispersal distance of L.leucocephala was 80~90 m while that of A.glauca was up to 100~110 m.The gray correlational coefficients of L.leucocephala forest in Heqing,Yuanmao,Dongchuan in Jingsha hot-dry river valley were 0.333 3,0.744 9 and 0.957 7 respectively,and those for A.glauca were 0.555 6,0.884 3 and 0.459 0 respectively.The figure of gray correlational coefficient indicates the situation of natural regeneration of plant,the higher the better.Thus L.leucocephala performed best in regeneration in the lower part(Dongchuan) and the worst in the upper part,whereas A.glauca performed best in regeneration in the middle part(Yuanmao) and poorest in the lower part(Dongchuan).In general,L.leucocephala plantation had a better regeneration than A.glauca in jingsha hot-dry river valley.