Department of Biology, North Carolina State University, Raleigh, North Carolina, United States of America.
PLoS One. 2010 Mar 10;5(3):e9534. doi: 10.1371/journal.pone.0009534.
Habitat fragmentation is a major driver of biodiversity loss. Yet, the overall effects of fragmentation on biodiversity may be obscured by differences in responses among species. These opposing responses to fragmentation may be manifest in higher variability in species richness and abundance (termed hyperdynamism), and in predictable changes in community composition. We tested whether forest fragmentation causes long-term hyperdynamism in butterfly communities, a taxon that naturally displays large variations in species richness and community composition. Using a dataset from an experimentally fragmented landscape in the central Amazon that spanned 11 years, we evaluated the effect of fragmentation on changes in species richness and community composition through time. Overall, adjusted species richness (adjusted for survey duration) did not differ between fragmented forest and intact forest. However, spatial and temporal variation of adjusted species richness was significantly higher in fragmented forests relative to intact forest. This variation was associated with changes in butterfly community composition, specifically lower proportions of understory shade species and higher proportions of edge species in fragmented forest. Analysis of rarefied species richness, estimated using indices of butterfly abundance, showed no differences between fragmented and intact forest plots in spatial or temporal variation. These results do not contradict the results from adjusted species richness, but rather suggest that higher variability in butterfly adjusted species richness may be explained by changes in butterfly abundance. Combined, these results indicate that butterfly communities in fragmented tropical forests are more variable than in intact forest, and that the natural variability of butterflies was not a buffer against the effects of fragmentation on community dynamics.
生境破碎化是生物多样性丧失的主要驱动因素。然而，破碎化对生物多样性的总体影响可能因物种间的反应差异而被掩盖。这些对破碎化的相反反应可能表现为物种丰富度和丰度的更高变异性（称为超动态），以及群落组成的可预测变化。我们测试了森林破碎化是否会导致蝴蝶群落的长期超动态，蝴蝶类群的物种丰富度和群落组成自然存在很大变化。利用亚马逊中部一个实验性破碎景观的 11 年数据集，我们通过时间评估了破碎化对物种丰富度和群落组成变化的影响。总体而言，调整后的物种丰富度（根据调查持续时间进行调整）在破碎森林和完整森林之间没有差异。然而，破碎森林中调整后的物种丰富度的空间和时间变化明显高于完整森林。这种变化与蝴蝶群落组成的变化有关，具体表现为破碎森林中林下阴凉物种的比例较低，边缘物种的比例较高。使用蝴蝶丰度指数估算的稀有物种丰富度的分析表明，在空间或时间变化方面，破碎和完整森林斑块之间没有差异。这些结果与调整后的物种丰富度结果并不矛盾，而是表明蝴蝶调整后的物种丰富度的更高变异性可能是由蝴蝶丰度的变化引起的。综合来看，这些结果表明，破碎热带森林中的蝴蝶群落比完整森林更具变异性，而蝴蝶的自然变异性并不是对群落动态破碎化影响的缓冲。
