Data from: Compensatory dynamics maintain bird phylogenetic diversity in fragmented tropical landscapes

1.Tropical forest loss can drive the extinction of forest-dependent species. Yet, non-forest species can proliferate in deforested landscapes, thus enabling community-level attributes (e.g., total abundance and richness) to be maintained in the remaining forest patches. Such compensatory dynamics have been, however, poorly investigated regarding the phylogenetic dimension of species diversity. Here, we assessed whether compensatory dynamics can stabilize the phylogenetic richness, divergence and structure of bird communities in response to forest loss in two regions in the Brazilian Atlantic forest, each under with different levels of land use intensification.

2.We surveyed birds in 40 forest sites, and assessed the response of five phylogenetic metrics to forest cover measured in local (600-m radius) landscapes. We separately assessed the entire community, forest-dependent and non-forest-dependent species and used information-theoretic criteria to assess the effect of forest cover on each response variable. In particular, we evaluated the plausibility of four models: a null model (no effect of forest cover), a linear model, a power law model (nonlinear effect), and an analysis of covariance model (to assess whether the effect of forest cover differed between regions).

3.Forest cover varied from 7% to 98%, and was positively related to the phylogenetic richness of forest-dependent species, but negatively related to the phylogenetic richness and divergence of non-forest birds, particularly in the more disturbed region. As consequence, the phylogenetic richness and divergence of the entire community were weakly related to forest cover.

4.Forest birds were less phylogenetically clustered in sites surrounded by lower forest cover, but the phylogenetic structure of non-forest birds was independent of forest cover.

5.Synthesis and applications. The phylogenetic impoverishment of forest-dependent birds is offset by the phylogenetic enrichment and divergence of non-forest-dependent birds in severely tropical deforested landscapes. These compensatory dynamics suggest that both bird groups are important for safeguarding bird evolutionary diversity in human-modified landscapes. Although deforested landscapes are reservoirs of bird phylogenetic diversity, suggesting that ecosystem functioning may be maintained in these sites, preventing further deforestation is urgently needed to preserve forest birds and their key ecological roles in the ecosystem.

1. 热带森林丧失可引发依赖森林物种（forest-dependent species）的灭绝。然而，非森林物种（non-forest species）可在已砍伐的森林景观中增殖，从而使剩余森林斑块的群落水平特征（community-level attributes，如总多度与物种丰富度）得以维持。不过，针对物种多样性的系统发育维度（phylogenetic dimension）开展的补偿动态研究仍较为匮乏。本研究针对巴西大西洋森林（Brazilian Atlantic forest）的两个区域（两地土地利用强度水平各异），评估了补偿动态能否稳定鸟类群落的系统发育丰富度、分化程度与结构，以响应森林丧失的影响。
2. 研究人员对40处森林样地开展了鸟类调查，并评估了5个系统发育指标（phylogenetic metrics）对局部（半径600米）景观中森林覆盖率（forest cover）的响应。我们分别针对完整群落、依赖森林物种与非依赖森林物种进行分析，并采用信息论准则（information-theoretic criteria）检验森林覆盖率对各响应变量的影响。具体而言，我们评估了四类模型的合理性：零模型（null model，无森林覆盖率效应）、线性模型（linear model）、幂律模型（power law model，非线性效应）以及协方差分析模型（analysis of covariance model，用于检验森林覆盖率的效应在两个区域间是否存在差异）。
3. 森林覆盖率介于7%至98%之间，且与依赖森林物种的系统发育丰富度呈正相关，却与非森林鸟类的系统发育丰富度及分化程度呈负相关，这一现象在受干扰程度更高的区域尤为显著。受此影响，完整群落的系统发育丰富度与分化程度与森林覆盖率的相关性较弱。
4. 当样地周边森林覆盖率较低时，森林鸟类的系统发育聚集程度更低，但非森林鸟类的系统发育结构与森林覆盖率无关。
5. 综合与应用。在受严重破坏的热带森林砍伐景观中，依赖森林鸟类的系统发育匮乏现象可被非依赖森林鸟类的系统发育富集与分化所抵消。这类补偿动态表明，两类鸟类群体均对保护人类改造景观中的鸟类进化多样性具有重要意义。尽管森林砍伐景观是鸟类系统发育多样性的储存库，这提示这些样地的生态系统功能或可得以维持，但仍亟需通过阻止进一步的森林砍伐来保护森林鸟类及其在生态系统中的关键生态作用。