内蒙古罕山次生林区木质残体基础特征

为探讨内蒙古罕山次生林区木质残体(WD)基础特征的地域差异性,文中以研究区年平均降水量由低到高的分布梯度,以赛罕乌拉、罕山、青山为实验地开展WD的基础特征研究。结果表明:罕山次生林区WD平均分布密度为(1336±53)株·hm^-2,主要以干基折断倒木或枯立木形式存在;径级结构总体以中小径级(2.5cm-10cm)为主,分布规律呈倒"J"字型;密度和径级特征均随降水梯度的增加逐渐下降,赛罕乌拉主要以中大径级(>10cm)为主;分解等级除赛罕乌拉以Ⅲ、Ⅳ级为主外,总体处于Ⅱ、Ⅲ级,占同径级WD总数的82.15%-95.06%。WD的积累与森林大面积非正常死亡密切相关,在关注研究区WD对森林生态系统积极作用的同时,还应对火灾防控、病虫害防治、森林健康等经营管理方面的负面影响引起重视。

Basic characteristics of woody debris in secondary forests of Hanshan,Inner Mongolia

To explore the regional differences in the basic characteristics of woody debris(WD) in the secondary forest area of Hanshan in Inner Mongolia, three sites of Saihanwula, Hanshan, and Qingshan, which are located on the gradient of the average annual precipitation from low to high, were taken as experimental sites to probe the basic characteristics of WD. The results show that the average distribution density of WD in secondary forest area of Hanshan is(1336±53) plants·hm^-2, mainly in the form of broken and fallen trees or dead standing trees on the dry foundation. The overall diameter class structure is mainly medium and small diameter class(2.5 cm-10 cm), and the distribution law is in the inverted "J" shape. Both the density and diameter class characteristics gradually decrease with the increase of the precipitation gradient. WD in Saihanwula is mainly composed of medium and large diameter(>10 cm). The decomposition grade of WD is mainly in grade II and III, accounting for 82.15%-95.06% of the total WD of the same diameter class, except that of Saihanura which is mainly of grade III and IV. The accumulation of WD is closely related to the abnormal death of large area of forest. While paying attention to the positive effect of WD on forest ecosystem, we should also pay attention to the negative effects of fire prevention and control, pest control and forest health.