生态疏伐对华北落叶松林分结构和生物多样性的影响

The effect of ecological thinning on the stand structure and biodiversity of Larix principis-rupprechtii Mayr

森林抚育对调整林分结构、促进林木生长都具有极大作用。为了解抚育对华北落叶松林分结构和林下物种多样性的影响,以承德市第三乡林场华北落叶松—白桦混交林为研究对象,采用对比分析的方法,对生态疏伐前后的林分结构、径阶分布和生物多样性进行了探讨。结果表明:生态疏伐后林分平均胸径增加2.1cm,平均树高稍有变化,林分密度从疏伐前的1 365株/hm^2下降到900株/hm^2;生态疏伐前,直径分布曲线呈左偏,6~16径阶林木数量占总数的42.6%;疏伐后,6~16径阶林木株数占总株数的21.3%,直径分布稍向右偏,更趋于正态分布;疏伐后,林下物种的Simpson和Shannon-Wiener指数均有所增加,Pielou均匀度指数在1号、4号、5号样方内有所下降,2号、3号样方内呈增加趋势,且3号样方的Simpson、Shannon-Wiener和Pielou均匀度指数涨幅均最大,分别比抚育前增加了0.373、0.834和0.203。

Forest tending has significant benefit for adjusting stand structure and promoting tree growth. For understanding the effect of forest tending of Larix principis-rupprechtii Mayr forest on stand structure and forest species diversity, the larch-betula platyphylla mixed forest in The Third Forest Farm of Chengde city was used as research object in this experiment, and the method of comparative analysis was to used study the effect of ecological thinning on stand structure, diameter class distribution and biodiversity. The results showed that after thinning, the average diameter grade increased 2.1 cm, and the average tree height was slightly changed. The stand density decreased from 1 365/hm2 before thinning to 900 / hm2 now. Before the ecological thinning, the diameter distribution curve was left-skewed, and the tree amount of 6--16 diameter class accounted for 42.6%. After thinning, 6--16 diameter trees accounted for 21. tion was slightly right-skewed, 3% of the total number of trees, and the diameter distribu- tending to be more normal distribution. After thinning, the Simpson and Shannon Wiener index of understory species were increased. The Pielou uni- formity index in the 1st , 4th , and 5th quadrats declined, while in the 2nd and 3rd plots it showed the increasing trend. The Simpson index, Shannon-Wiener index and Pielou even- ness index in the 3rd plot increased the most, for increasing 0. 373, 0. 843 and 0. 203 respec- tively compared with the before-tending trees.