近天然落叶松-云冷杉林树种竞争关系的变化

Tree competitive states and trends in semi-natural mixed forest of Larch-Spruce

以4块落叶松-云冷杉间伐实验样地为对象,采用6个与距离无关的竞争指标,研究林木竞争状态在20年间(1986～2006年)的变化及间伐的影响。结果表明,落叶松为主要树种,竞争能力最强,其竞争压力主要来自种内,红松和其他阔叶树的竞争能力有逐渐增强的趋势,因此,随着林分生长,落叶松的竞争主体地位受到了来自其他针叶树云冷杉、红松及阔叶树种的威胁。该林分竞争关系近期相对稳定,但有从落叶松-云冷杉林向阔叶树及红松林发展的趋势。间伐影响种间竞争关系和林分平均竞争水平,影响程度与间伐对象的选择与间伐强度有关。林分竞争水平随间伐强度的增加而降低,但会逐渐恢复。

The tree competition states and changes were examined in the four plots（0.25 hm2 for each） of semi-natural mixed forest of larch-spruce-fir in Jingouling forest farm,Wangqing forestry bureau,Jilin Province.The plots with thinning intensity by 20%,30% and 40% were observed from 1986 to 2006.Six distance-independent competition indices were introduced to show the competition states and the influences of thinning on the the states.The results indicated that larch was the main and the most powerful species in competition in the stands and rarely affected by other species.The competitiveness of Korean pine and several broad-leaved species were increased with the growth of the forest stands,which would threaten the dominance of larch.The competition structure of this forest was relatively stable recently,but it tended to be the broad-leaved or the Korean pine forest in the future.Thinning played great roles in the intrerspecific competition and the average competition level of the forest stands,and the effects thinning were associated with the species selected for thinning and the thinning intensities.The average competition level of the forest stands was declined with the increase of thinning intensities but the competition level could be recovered in one or two decades.