摘要
设置6块样地对河北省张北地区杨树林分枯稍的原因进行了调查，结果表明：样地Ⅱ和样地Ⅳ内，枯稍程度与树高的相关性在0.05的水平上均达到了显著相关，而枯稍与胸径的相关性在样地Ⅱ内达到了显著相关，在样地Ⅳ内相关性不显著；被调查的6块样地有5块样地土壤剖面中存在钙积层，它阻碍了根系向下生长，杨树在该土壤条件下不能继续正常生长，是杨树枯稍的一个重要原因；杨树林龄过大，树势较弱，地下水紧缺以及虫害危害对枯稍也有影响。我们认为，在更新整地时，挖穿钙积层更有利于林分生长；选择造林树种时，尝试用采伐周期更长、适生性更好的樟子松和榆树造林，或可取得更佳的生态效益；该地区应做好森林防虫工作，并严格控制农业生产用水。
Abstract
To understand the reasons for poplar degeneration with different degrees in Zhangbei,we inves-tigated the poplar forest stands.Results suggest that in plotⅡand plotⅣ,the top dry degree had signifi-cant correlation with tree height in a certain level.But when the top dry degree and the diameter at breast height had significant correlation in plot Ⅱ,there was no significant correlation in plot Ⅳ.In all the 6 plots investigated,5 had tepetate in their soil profiles.The tepetate kept root system from growing in soil, it was a main top dry factor.As the forest age was too old and underground water was decreasing sharply, the trees were really weak,which were easily attacked by insects.
NETL
NSTL
维普
万方数据