昆嵛山天然林13年演替动态--生物多样性变化、物种周转与食叶害虫的短期干扰

13-years succession dynamic of Kunyushan natural forest:change of diversity,species turnover and herbivorous insect's short-term disturbance

依托昆嵛山森林生态定位观察站所设立的40块永久性样地,比较了群落自然演替13 a的林内灌草多样性指数、物种周转率以及食叶害虫昆嵛山腮扁叶蜂的危害程度,评判食叶害虫对林分结构变化的短期潜在功能作用。结果表明:赤松纯林内灌草Shannon多样性指数和均匀度指数分别为2.50和0.79,分别低于1996年的2.69和0.85;黑松混交林内灌草Shannon多样性指数和均匀度指数分别为2.27和0.79,分别高于1996年的1.85和0.77。赤松和黑松混交林下的灌草种类13 a的整体物种周转率达到125.9%;昆嵛山腮扁叶蜂发生严重林分(虫口密度>25头.株-1)的树木死亡率(平均13.35%)极显著高于腮扁叶蜂发生较轻的林分(P=0.003 8),树木死亡率与腮扁叶蜂虫口密度呈显著的正相关,并与林分郁闭度显著相关,但与林分密度不相关;腮扁叶蜂发生严重林分的树木胸径平均增长量略高于发生较轻的林分,但两者之间差异不显著。从本研究结果看,在昆嵛山,与未发生腮扁叶蜂的林分相比,腮扁叶蜂危害导致树木死亡率升高有可能加速林分密度的调整。

The objective of this study was to evaluate potential impact of biotic disturbance on the change of Pinus densiflora population quantitative characteristics over 13-years growth in Kunyushan Forest Farm.Investigations and assessments of Shannon diversity index（H） and evenness index（JS） of shrub and herbage plant communities,species turnover rate and web-spinning sawfly severity were conducted in 40 permanent plots.Shannon diversity index and evenness index of shrub and herbage plant communities under P.densiflora pure forest was 2.50 and 0.79 in 2008,lower than（H） 2.69 and（JS） 0.85 in 1996,respectively.In P.thunbergii mixed forest,Shannon diversity index and evenness index of shrub and herbage plant communities was 2.27 and 0.79 in 2008,higher than（H） 1.85 and（JS） 0.77 in 1996,respectively.Species turnover rate was 125.9%,which implied the change of species over 13 years in Kunyushan forest communities.It was found that there was a significant higher mortality rate（average 13.35%） in severely infested stands whose sawfly（Cephalcia kunyushanica） larval density was 25 larvae/tree,than that in slightly infested stands（p=0.003）.Meanwhile,a positive correlation was found between tree＇s mortality and sawfly larval density and canopy cover.Growth of diameter at breast height（DBH） of severely infested stands was slightly higher than that of slightly infested stands while there was no significant difference between them.This indicates that higher tree mortality caused by sawfly attack could accelerate adjustment of stand density in severely infested stands compared to the same course by population self-thinning in slightly infested stands,however,the attack of sawfly did not inhibited tree growth promisingly.