达维台风对海南尖峰岭热带山地雨林群落的影响

 海南岛地处我国台风的频发地带, 台风是影响海南岛热带雨林的一个重要的自然干扰因子。该文对2005年达维台风前后海南尖峰岭热带山地雨林天然次生林2 600 m²固定样地的物种组成、胸高断面积、植株数目、风倒木的影响因子、物种多样性、生物量变化及碳储量归还进行比较分析。结果显示, 台风后森林内产生大量的风倒木、断枝和落叶, 导致群落郁闭度减少、透光性增强, 并产生大量的林窗。台风后群落的组成结构发生显著变化, 受损株数达514株(占总株数26.1%); 其中风倒木比例较大, 达206株(占总株数10.5%)。方差分析结果显示, 受台风影响产生的风倒木与未明显受损树木的胸径面积、树高和木材密度均无显著差异; 但与树种组成有较紧密的关联, 对乔木层、幼树层和下木层造成的损害存在种类上的明显差异。台风产生的损害可以分为直接性损害和间接性损害两种: 1)直接性损害主要作用于乔木层, 造成大径级植株严重受损; 部分树种重要值降低, 变成伴生种, 或者次优势种和原有优势种成为共同优势种; 2)间接性损害主要通过风倒木作用于幼树层和下木层, 产生的倒木、断枝和落叶压倒其它植株, 表现为小面积范围内的个体死亡, 甚至有种类消失; 部分优势种的个体数减少较多, 但占该种群所有个体数目的比例较小。乔木层的Shannon-Wiener和Simpson多样性指数均略有下降, 而幼树层和下木层均略有上升, 但3个林层均表现为不同程度的种类消失和一些种类的个体数目减少。此次台风还造成该样地至少占台风前总生物量10.42%的生物量归还给林地, 并对森林生态系统碳循环产生重大影响。

INFLUENCE OF TYPHOON DAMREY ON THE TROPICAL MONTANE RAIN FOREST COMMUNITY IN JIANFENGLING,HAINAN ISLAND,CHINA

Aims My objective was to determine the impact of a strong typhoon on the tropical montane rain forest community in Hainan Island. Methods A 2 600 m² permanent plot in Jianfengling, Hainan Island was surveyed in June 2005 before Typhoon Damrey and in October 2005 after the typhoon. All individuals with diameter at breast height >1.0 cm were recorded and classified into four injury types. I analyzed changes in species composition, basal area, number of individuals, influence of wind-blown trees, biological diversity, biomass change and carbon return. Important findings Many wind-blown trees, broken branches and fallen leaves appeared after Typhoon Damrey and this decreased crown density, increased penetrating light and produced many canopy gaps. Community composition and structure changed significantly, with 514 individuals (26.1%) damaged totally. Wind-blown individuals accounted for a large proportion, with 206 individuals (10.5%). ANOVA analysis showed that wind-blown and the normal trees did not differ in basal area, tree height and wood density. However, damage in the tree, sapling and understory layers was significantly different. Damages included direct and indirect damage. Direct damage mainly influenced the tree layer, where large-diameter individuals were damaged severely. The relative Importance Values of some species decreased; some became associate species and some sub-dominant species became co-dominant with formerly dominant species. Indirect damage mainly influenced the sapling and understory layers with wind-blown trees, broken branches and fallen leaves affecting other individuals. Individuals died in small areas, and some species disappeared from these layers. Individuals of some dominant species decreased, but accounted for only a small part of their populations. Shannon-Wiener and Simpson diversity indices decreased slightly in the tree layer, in contrast to the sapling and understory layer. However, a few species disappeared and the number of individuals of some species decreased in all layers. At least 10.42% of the forest biomass was lost after Typhoon Damrey, which greatly influenced the carbon cycle of the forest ecosystem.