BEETLE SPECIES RESPONSES TO TROPICAL FOREST FRAGMENTATION
BEETLE SPECIES RESPONSES TO TROPICAL FOREST FRAGMENTATION
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甲虫物种对热带森林破碎化的反应
DOI：
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发表时间：
1998
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通讯作者：
N. Stork
中科院分区：
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作者：
R. Didham;P. Hammond;J. Lawton;P. Eggleton;N. Stork
在亚马逊河流域中部的一个实验片段化的热带森林景观中，研究了森林片段化对甲虫物种组成的影响。叶凋落物甲虫采样在7个距离森林边缘（0-420米）沿着森林边缘到内部横断面在两个100公顷的森林片段和两个连续的森林边缘，并在一系列相同的距离沿着两个深连续的森林横断面。在两个10公顷森林片段和两个1公顷片段的中心采集了额外的样本。这种取样制度允许区分边缘和碎片面积效应。甲虫种类组成的变化显着，并独立地减少距离林缘和减少碎片面积。边缘对物种组成的影响由6个重要的环境变量介导：气温，冠层高度，树枝的地面覆盖百分比，凋落物生物量，凋落物含水量，和气温×距离边缘的相互作用效应，由于不同的边缘植被密度的温度廓线不同。
种群密度的32个最丰富的甲虫物种测试（47%）的15个显着影响森林片断化。根据经验将物种响应分为四个主要类别：（A）边缘敏感，区域不敏感;（B）区域敏感，边缘不敏感;（C）边缘和区域敏感;以及（D）边缘和区域不敏感。在这些类别中，密度趋势要么是正的（深林物种），要么是负的（受干扰地区物种），物种对破碎化的反应是全方位的。绝大多数物种都受到了不利影响。估计物种损失率从森林片段：49.8%的常见物种从1公顷片段，29.8%从10公顷片段，13.8%从100公顷片段。下降的密度是一个显着的前兆物种损失的森林片段，但其他物种没有表现出显着的人口密度响应片段化也没有从一些片段，大概是偶然的。
从森林片段的物种损失的概率是不相关的身体大小或营养组的32个常见的物种，虽然整个甲虫组合（993种）的比例在不同的营养组的物种的变化显着与碎片。稀有性和种群变异性（在未受干扰的森林）是重要的预测破碎化的敏感性。然而，令人惊讶的是，普通物种比稀有物种更有可能在小范围内灭绝。这为多物种共存模型提供了经验支持，该模型表明竞争优势但分散性差的物种是由于栖息地破坏而首先灭绝的物种。因此，稀有物种被预测为更好的扩散和更好地坚持。
The effects of forest fragmentation on beetle species composition were investigated in an experimentally fragmented tropical forest landscape in Central Amazonia. Leaf-litter beetles were sampled at seven distances from the forest edge (0–420 m) along forest edge-to-interior transects in two 100-ha forest fragments and two continuous forest edges, and at an identical series of distances along two deep continuous forest transects. Additional samples were taken at the centers of two 10-ha forest fragments and two 1-ha fragments. This sampling regime allowed discrimination between edge and fragment area effects. Beetle species composition changed significantly and independently with both decreasing distance from forest edge and decreasing fragment area. Edge effects on species composition were mediated by six important environmental variables: air temperature, canopy height, percent ground cover of twigs, litter biomass, litter moisture content, and an air temperature × distance from edge interaction effect, due to the different temperature profiles of edges with differing edge vegetation density.
Population densities of 15 of the 32 most abundant beetle species tested (47%) were significantly affected by forest fragmentation. Species responses were classified empirically into four major categories: (A) edge sensitive, area insensitive; (B) area sensitive, edge insensitive; (C) edge and area sensitive; and (D) edge and area insensitive. Within these categories, trends in density were either positive (deep-forest species), or negative (disturbed-area species), with species showing the full spectrum of responses to fragmentation. The vast majority of species were adversely affected. Estimated species loss rates from forest fragments were: 49.8% of common species from 1-ha fragments, 29.8% from 10-ha fragments, and 13.8% from 100-ha fragments. Declining density was a significant precursor of species loss from forest fragments, but other species that did not show significant population density responses to fragmentation were also absent from some fragments, presumably by chance.
The probability of species loss from forest fragments was not correlated with body size or trophic group for the 32 common species, although for the entire beetle assemblage (993 species) proportions of species in different trophic groups changed significantly with fragmentation. Rarity and population variability (in undisturbed forest) were significant predictors of susceptibility to fragmentation. Surprisingly, though, common species were significantly more likely to become locally extinct in small fragments than rarer species. This lends empirical support to models of multispecies coexistence under disturbance that suggest competitively dominant but poorly dispersing species are the first to become extinct due to habitat destruction. Thus, rarer species are predicted to be better dispersers and better at persisting.