Remeš Vladimír, Remešová Eva, Friedman Nicholas R, Matysioková Beata, Rubáčová Lucia
Department of Zoology and Laboratory of Ornithology Faculty of Science Palacky University Olomouc Czech Republic.
Department of Ecology Faculty of Science Charles University Prague Czech Republic.
Ecol Evol. 2021 Jul 27;11(17):11839-11851. doi: 10.1002/ece3.7952. eCollection 2021 Sep.
Vegetation complexity is an important predictor of animal species diversity. Specifically, taller vegetation should provide more potential ecological niches and thus harbor communities with higher species richness and functional diversity (FD). Resource use behavior is an especially important functional trait because it links species to their resource base with direct relevance to niche partitioning. However, it is unclear how exactly the diversity of resource use behavior changes with vegetation complexity. To address this question, we studied avian FD in relation to vegetation complexity along a continental-scale vegetation gradient. We quantified foraging behavior of passerine birds in terms of foraging method and substrate use at 21 sites (63 transects) spanning 3,000 km of woodlands and forests in Australia. We also quantified vegetation structure on 630 sampling points at the same sites. Additionally, we measured morphological traits for all 111 observed species in museum collections. We calculated individual-based, abundance-weighted FD in morphology and foraging behavior and related it to species richness and vegetation complexity (indexed by canopy height) using structural equation modeling, rarefaction analyses, and distance-based metrics. FD of morphology and foraging methods was best predicted by species richness. However, FD of substrate use was best predicted by canopy height (ranging 10-30 m), but only when substrates were categorized with fine resolution (17 categories), not when categorized coarsely (8 categories). These results suggest that, first, FD might increase with vegetation complexity independently of species richness, but whether it does so depends on the studied functional trait. Second, patterns found might be shaped by how finely we categorize functional traits. More complex vegetation provided larger "ecological space" with more resources, allowing the coexistence of more species with disproportionately more diverse foraging substrate use. We suggest that the latter pattern was driven by nonrandom accumulation of functionally distinct species with increasing canopy height.
植被复杂性是动物物种多样性的重要预测指标。具体而言，更高的植被应提供更多潜在的生态位，从而容纳具有更高物种丰富度和功能多样性（FD）的群落。资源利用行为是一个特别重要的功能性状，因为它将物种与其资源基础联系起来，与生态位划分直接相关。然而，资源利用行为的多样性究竟如何随植被复杂性而变化尚不清楚。为了解决这个问题，我们沿着大陆尺度的植被梯度研究了鸟类功能多样性与植被复杂性的关系。我们在澳大利亚绵延3000公里的林地和森林中的21个地点（63个样带），根据觅食方法和底物利用情况对雀形目鸟类的觅食行为进行了量化。我们还对相同地点内630个采样点的植被结构进行了量化。此外，我们测量了博物馆馆藏中所有111个观察物种的形态特征。我们使用结构方程模型、稀疏分析和基于距离的指标，计算了基于个体的、丰度加权的形态和觅食行为功能多样性，并将其与物种丰富度和植被复杂性（以冠层高度为指标）相关联。形态和觅食方法的功能多样性最好由物种丰富度预测。然而，底物利用的功能多样性最好由冠层高度（范围为10 - 30米）预测，但只有当底物以精细分辨率分类（17类）时才成立，粗分类（8类）时则不然。这些结果表明，首先，功能多样性可能会随着植被复杂性的增加而独立于物种丰富度增加，但情况是否如此取决于所研究的功能性状。其次，发现的模式可能受到我们对功能性状分类精细程度的影响。更复杂的植被提供了更大的“生态空间”和更多资源，使得更多具有不成比例的更多样化觅食底物利用方式的物种能够共存。我们认为后一种模式是由功能不同的物种随着冠层高度增加的非随机积累驱动的。
