云南片断化热带雨林生物多样性变化研究

Biodiversity Changes of the Fragmented Tropical Rain Forest in Yunnan

  • 摘要: 鉴于目前热带地区生境破碎化和热带森林片断化已不可避免,基于以往的各种研究,总结了热带季节性雨林片段化后对生态和生物多样性等的影响。结果表明:片断化后,一些植物分类群(种、属、科)的优势度明显改变,单位面积上物种数减少了,并且干扰越严重且片断的面积越小,物种减少越明显;在生活型构成上,藤本植物和小高位芽植物相对增加,而附生植物,大、中高位芽植物和地上芽植物相对减少,同时发现具有较小种群的树种在片断雨林中会首先消失。在片断化的热带季节性雨林里,不同生态种组的物种发生了显著变化,阳性和先锋植物种类增加,耐阴和阴生植物种类减少;随着热带季节性雨林的片断化,其组成物种也发生了系统发育结构的改变:系统发育关系由聚集变为离散。热带季节性雨林片断化后,林缘产生了明显的“边缘效应”,森林边缘单位面积植物种数和个体数明显多于森林内部,并以藤本植物的增加最为显著;干扰越大的片断热带雨林,林缘和林内阳性植物的比例越大,差值越小;林缘优势植物科的数量相对增加了,即林缘种类主要集中在一些含先锋树种较多的科中,而林内的少种科的比例较高。热带季节性雨林主要通过林下存在的幼苗、幼树库来更新,林下种植会破坏热带雨林更新所依赖的幼苗、幼树库, 使热带雨林丧失更新能力。热带雨林变为橡胶林后,原来的物种极端丰富的乔木层变为仅由单一树种橡胶组成的乔木层,物种多样性大量丧失。

     

    Abstract: Tropical habitats and tropical forests have been fragmented, the effects of fragmentation of tropical seasonal rain forests on ecology and biodiversity were summarized with previous studies. The findings indicated that with fragmentation of the forest, species diversity is usually reduced, and the smaller of the fragment and the greater of the disturbance, the greater of the species diversity reduction. In life form composition, the liana and microphanerophyte species increased in the fragmented forests, but epiphyte, megaphanerophyte, mesophanerophyte and chamaephyte species decreased. Tree species with small populations are lost first in the process of fragmentation. The species of different ecological species groups changed greatly, heliophilous or pioneer tree species increased, and shade-tolerant species were reduced. Phylogenetic structure changed distinctly from clustering to dispersion with fragmentation of the forest. In addition, in fragmented habitats, the edge-related changes in environment and plant diversity, that is edge effects, arose on the margin of forest. The plant species and individual numbers are higher in the forest edge than in the interior, and especially lianas increase conspicuously in the edge. The greater of the disturbance to the forest, the more light-demanding species appear both in the edge and the interior. The number of families with abundant species increased in the edge, while the families with less species abundance were more in the interior. Tropical seasonal rain forests are mainly regenerated through understory seedlings and sapling, the damage of it caused by understory crop planting, which suppresses the regeneration of tropical rain forests. The decrease in area and the consequent fragmentation of the seasonal rain forest mainly due to the expansion of rubber have been obviously the principal factors leading to loss of biodiversity.

     

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