Morante-Filho José Carlos, Faria Deborah, Mariano-Neto Eduardo, Rhodes Jonathan
Applied Conservation Ecology Lab, Programa de Pós-graduação Ecologia e Conservação da Biodiversidade, Universidade Estadual de Santa Cruz, Rodovia Ilhéus-Itabuna, km16 /Salobrinho, Ilhéus, Bahia, Brazil.
Instituto de Biologia, Universidade Federal da Bahia, R. Barão Jeremoabo, Ondina, Salvador, Bahia, Brazil.
PLoS One. 2015 Jun 17;10(6):e0128923. doi: 10.1371/journal.pone.0128923. eCollection 2015.
Habitat loss is the dominant threat to biodiversity and ecosystem functioning in terrestrial environments. In this study, we used an a priori classification of bird species based on their dependence on native forest habitats (forest-specialist and habitat generalists) and specific food resources (frugivores and insectivores) to evaluate their responses to forest cover reduction in landscapes in the Brazilian Atlantic Forest. From the patch-landscapes approach, we delimited 40 forest sites, and quantified the percentage of native forest within a 2 km radius around the center of each site (from 6 - 85%). At each site, we sampled birds using the point-count method. We used a null model, a generalized linear model and a four-parameter logistic model to evaluate the relationship between richness and abundance of the bird groups and the native forest amount. A piecewise model was then used to determine the threshold value for bird groups that showed nonlinear responses. The richness and abundance of the bird community as a whole were not affected by changes in forest cover in this region. However, a decrease in forest cover had a negative effect on diversity of forest-specialist, frugivorous and insectivorous birds, and a positive effect on generalist birds. The species richness and abundance of all ecological groups were nonlinearly related to forest reduction and showed similar threshold values, i.e., there were abrupt changes in individuals and species numbers when forest amount was less than approximately 50%. Forest sites within landscapes with forest cover that was less than 50% contained a different bird species composition than more extensively forested sites and had fewer forest-specialist species and higher beta-diversity. Our study demonstrated the pervasive effect of forest reduction on bird communities in one of the most important hotspots for bird conservation and shows that many vulnerable species require extensive forest cover to persist.
栖息地丧失是陆地环境中生物多样性和生态系统功能面临的主要威胁。在本研究中，我们根据鸟类对原生森林栖息地的依赖程度（森林 specialists 和栖息地 generalists）以及特定食物资源（食果动物和食虫动物）对鸟类物种进行了先验分类，以评估它们对巴西大西洋森林景观中森林覆盖减少的反应。从斑块景观方法出发，我们划定了40个森林地点，并量化了每个地点中心周围2公里半径内原生森林的百分比（从6% - 85%）。在每个地点，我们使用点计数法对鸟类进行采样。我们使用零模型、广义线性模型和四参数逻辑模型来评估鸟类群体的丰富度和丰度与原生森林数量之间的关系。然后使用分段模型来确定表现出非线性反应的鸟类群体的阈值。该地区鸟类群落的整体丰富度和丰度不受森林覆盖变化的影响。然而，森林覆盖的减少对森林 specialists、食果和食虫鸟类的多样性有负面影响，对 generalist 鸟类有正面影响。所有生态群体的物种丰富度和丰度与森林减少呈非线性相关，并显示出相似的阈值，即当森林面积小于约50%时，个体和物种数量会发生突然变化。森林覆盖小于50%的景观中的森林地点与森林覆盖更广泛的地点包含不同的鸟类物种组成，森林 specialists 物种较少，β多样性较高。我们的研究证明了森林减少对鸟类保护最重要的热点地区之一的鸟类群落具有普遍影响，并表明许多脆弱物种需要广泛的森林覆盖才能生存。
