Diversity and assembly of forest bird communities across a rainfall gradient in Central Africa

了解群落结构的基本模式及其与环境和人类因素的关系是生物多样性理论和保护实践的关键。西非和中非的生物群落研究尤其不足，考虑到非洲森林和大草原独特的古地理历史以及当前气候和土地利用变化的威胁，这尤其令人遗憾。本文建议以森林鸟类群落为指标，从系统发育和功能角度对中非几内亚-刚果森林和苏丹大草原生物群落的区域生物多样性梯度进行评估。我们的目标是描述迄今为止未知但基本的鸟类群落模式，如分类、功能和系统发育多样性和结构，利用自己收集的数据，从喀麦隆的六个低地站点跨越沿海常绿，潮湿的半落叶林到林地和苏丹草原的开阔地区。这些地点基本上代表了一个降雨梯度，随着地点的生物和非生物因素的不同，植被复杂性也不同。我们希望提供基线数据，以了解组装过程背后的机制，如最终的环境（生物过滤）以及生态相互作用（如竞争排斥）。我们还希望解决最终的历史因素，如灭绝、物种形成或扩散限制。这项研究是几内亚-刚果领域在这种规模上的首次此类研究，特别是对于我们所处理的多种生物多样性维度。

An understanding of basic patterns of community structure and how these relate to environment and human factors is key both for biodiversity theory and conservation practice. Biotic communities of West and Central Africa are particularly understudied which is especially unfortunate given the unique paleogeographic history of African forests and savannahs and the current threats from climate and land use change. We here propose to assess a regional biodiversity gradient across Guinea-Congolian Forests and Sudano Savannah biomes in Central Africa using forest bird communities as indicators, addressing diversity from a phylogenetic and functional viewpoint. We aim at describing hitherto unknown but basic bird community patterns such as taxonomic, functional and phylogenetic diversity and structure, using own collected data from six lowland sites in Cameroon spanning from coastal evergreen, over moist semi-deciduous forests into the woodlands and open areas of the Sudano savanna. These sites essentially represent a rainfall gradient, varying in vegetational complexity with sites differing in biotic and abiotic factors. We wish to provide baseline data to understand the mechanisms behind the assembly process, such as eventual environmental (biotic filtering) as well as ecological interactions (such as competitive exclusion). We also wish to address eventual historical factors such as extinction, speciation or dispersal limitation. The study is the first of its kind in the Guineo-Congolian realm at this scale, especially for the multiple biodiversity dimensions we address.