Edge effects on components of diversity and above-ground biomass in a tropical rainforest

1. Edge effects are among the most significant consequences of forest fragmentation. Therefore, understanding the impacts of edge creation on biodiversity is crucial for forest management and biological conservation. 2. In this study, we used trait-based and phylogenetic approaches to examine the effects of fragmentation on components of diversity and above-ground biomass of rainforest tree communities in Madagascar in forest edge vs. interior habitats. 3. Tree communities in forest edges showed lower phylogenetic diversity relative to those in interior habitats, suggesting that some clades may be more vulnerable to environmental filtering than others. Functional diversity was also significantly lower on the edge for productivity traits, but not for dispersal traits. Tree communities in the forest edge showed higher divergence of dispersal traits and lower divergence in productivity traits than expected by chance, while functional diversity in interior forest did not differ from random expectations. This suggests separate mechanisms affect productivity traits vs. dispersal traits in edge habitat. 4. There was no significant difference in above-ground biomass between edge and interior habitats, suggesting that edge effects have not yet negatively influenced the forest’s potential for carbon storage. However, these changes may not have occurred yet, given the slow turnover of tree communities. 5. Synthesis and applications: Our results highlight the role of edge effects in the erosion of functional and phylogenetic diversity of highly diverse tree communities. While above-ground biomass did not appear to be affected by forest edge in our study, we suggest long-term monitoring of forests for potential changes in ecosystem functioning. Given the prevalence of forest fragmentation globally, these findings indicate the need for more holistic biodiversity studies to better understand local consequences of forest fragmentation.11-Jul-2017

1. 边缘效应是森林破碎化最显著的后果之一。因此，明晰生境边缘形成对生物多样性的影响，对于森林经营与生物保护工作至关重要。
2. 本研究基于功能性状与系统发育分析方法，对比分析了马达加斯加雨林乔木群落的多样性组分与地上生物量，探究森林破碎化对林缘与林内生境的影响。
3. 相较于林内生境的乔木群落，林缘乔木群落的系统发育多样性更低，这表明部分演化支相较于其他类群更易受环境过滤作用的影响。就生产力相关功能性状而言，林缘生境的功能多样性同样显著更低，但扩散相关功能性状的功能多样性并无此差异。林缘乔木群落的扩散功能性状分化程度高于随机预期，而生产力相关功能性状的分化程度则低于随机预期；但林内生境的功能多样性与随机预期无显著差异。这意味着林缘生境中，作用于生产力相关功能性状与扩散相关功能性状的生态过程存在差异。
4. 林缘与林内生境的地上生物量并无显著差异，表明边缘效应尚未对森林的碳储存潜力造成负面影响。不过考虑到乔木群落的周转速率较慢，这些变化可能尚未显现。
5. 总结与应用：本研究结果凸显了边缘效应在高多样性乔木群落的功能与系统发育多样性丧失过程中的作用。尽管本研究中地上生物量未受林缘生境的显著影响，但我们建议对森林开展长期监测，以追踪生态系统功能的潜在变化。鉴于全球范围内森林破碎化现象普遍存在，本研究结果表明，需开展更具整体性的生物多样性研究，以更深入地理解森林破碎化带来的局地生态后果。
2017年7月11日