海南中部山区天然林群落结构与多样性变化

Changes of community structure and diversity of natural forests in mountainous areas of central Hainan Island

为了解海南中部山区天然林群落结构与多样性变化规律,对五指山山地雨林原始林、尖峰岭低地雨林、吊罗山山地雨林、霸王岭云雾林次生林内建成的各1600 m2样地进行常年监测,基于2012—2020年监测数据,从群落结构、树木生长、树木死亡、物种多样性等方面分析群落近8年动态特征。结果表明:2012—2020年,(1)五指山山地雨林、尖峰岭低地雨林的径级结构与树高结构均呈倒“J”型,吊罗山山地雨林、霸王岭云雾林的径级结构呈倒“J”型,树高结构呈近“L”型;随着时间的推移,群落结构更加复杂。(2)小径级个体树高生长速率较快,随胸径增加树高生长速率降低,胸径生长速率升高;死亡个体数量随胸径的增加而减少,表现出小径级个体对阳光等资源的强烈竞争。(3)翻白叶(Pterospermum heterophyllum)、岭南山竹子(Garcinia oblongifolia)、四蕊三角瓣花(Prismatomeris tetrandra)、海南山矾(Symplocos hainanensis)种群变化率分别为-6.07%、+7.10%、+12.52%、+14.29%,种群变化率均大于5%,属于快速变动种群,表现出喜阳先锋种逐渐被耐阴演替过渡种取代。(4)五指山山地雨林α物种多样性的平均变化率为+1.48%,尖峰岭低地雨林为+1.59%,吊罗山山地雨林为+4.19%,霸王岭云雾林为+12.26%;进入和退出树种多为偶见种,是引起物种多样性变化的主要原因。对于海南中部山区受破坏的生态系统,通过有效的封山育林,群落演替均能得到较好的恢复,结构复杂性、物种多样性和群落稳定性得到有效提高。

To understand the changes of community structure and diversity of natural forests in mountainous areas of central Hainan Island, two surveys were conducted in the montane rain forest in Wuzhishan, the lowland rain forest in Jianfengling, the montane rain forest in Diaoluoshan and the cloud forest in Bawangling from 2012 to 2020. A plot with a size of 1600 m~2 was set up for each forest type. The temporal variations of community structure, tree growth, tree mortality and species diversity in eight years were analyzed. The results showed that from 2012 to 2020:(1) DBH size-class and tree height class of the montane rain forest in Wuzhishan and the lowland rain forest in Jianfengling showed an inverted “J” shape. DBH size-class of the montane rain forest in Diaoluoshan and the cloud forest in Bawangling showed an inverted “J” shape, while tree height class showed a near “L” shape. The community structure became more complex over time.(2) Height growth rate of young trees was faster. With the increase of DBH, growth rate of tree height decreased and growth rate of DBH increased. The number of dead indivi-duals decreased with the increase of DBH. Young trees had a strong competition for resources, such as sunlight.(3) The change rates of population size of Pterospermum heterophyllum, Garcinia oblongifolia, Prismatomeris tetrandra and Symplocos hainanensis were higher than 5%, indicating rapidly changing populations. Pioneer species were gradually replaced by transitional species.(4) The average change rate of species diversity was +1.48%, +1.59%, +4.19%, and +12.26% in the montane rain forest in Wuzhishan, the lowland rain forest in Jianfengling, the montane rain forest in Diaoluoshan and the cloud forest in Bawangling, respectively. Most of the immigrating and exiting species were occasional species, which accounted for the changes of species diversity. Community succession of the damaged forests in the mountainous areas of central Hainan Island can be well restored, the structure complexity, species diversity and community stability of which can be effectively improved by effective enclosure.