Bertellotti Franklin, Sommer Nathalie R, Schmitz Oswald J, McCary Matthew A
School of the Environment Yale University New Haven Connecticut USA.
Department of Biosciences Rice University Houston Texas USA.
Ecol Evol. 2023 Nov 7;13(11):e10686. doi: 10.1002/ece3.10686. eCollection 2023 Nov.
Metacommunity theory has advanced scientific understanding of how species interactions and spatial processes influence patterns of biodiversity and community structure across landscapes. While the central tenets of metacommunity theory have been promoted as pivotal considerations for conservation management, few field experiments have tested the validity of metacommunity predictions. Here, we tested one key prediction of metacommunity theory-that decreasing habitat connectivity should erode metacommunity structure by hindering species movement between patches. For 2 years, we manipulated an experimental old-field grassland ecosystem via mowing to represent four levels of habitat connectivity: (1) open control, (2) full connectivity, (3) partial connectivity, and (4) no connectivity. Within each treatment plot (10 × 10 m, = 4 replicates), we measured the abundance and diversity (i.e., alpha and beta) of both flying and ground arthropods using sticky and pitfall traps, respectively. We found that the abundance and diversity of highly mobile flying arthropods were unaffected by habitat connectivity, whereas less mobile ground arthropods were highly impacted. The mean total abundance of ground arthropods was 2.5× and 2× higher in the control and partially connected plots compared to isolated patches, respectively. We also reveal that habitat connectivity affected the trophic interactions of ground arthropods, with predators (e.g., wolf spiders, ground spiders) being highly positively correlated with micro-detritivores (springtails, mites) but not macro-detritivores (millipedes, isopods) as habitat connectivity increased. Together these findings indicate that changes in habitat connectivity can alter the metacommunity structure for less mobile organisms such as ground arthropods. Because of their essential roles in terrestrial ecosystem functioning and services, we recommend that conservationists, restoration practitioners, and land managers include principles of habitat connectivity for ground arthropods when designing biodiversity management programs.
集合群落理论推动了人们对于物种相互作用和空间过程如何影响景观尺度上生物多样性模式和群落结构的科学理解。虽然集合群落理论的核心原则已被视为保护管理的关键考量因素，但很少有野外实验检验过集合群落预测的有效性。在此，我们检验了集合群落理论的一项关键预测，即栖息地连通性降低会阻碍物种在斑块间移动，进而破坏集合群落结构。在两年时间里，我们通过割草对一个实验性的旧耕地草原生态系统进行了操控，以呈现四种栖息地连通性水平：（1）开放对照，（2）完全连通，（3）部分连通，以及（4）无连通。在每个处理样地（10×10米，n = 4个重复）内，我们分别使用粘性陷阱和陷阱捕捉器测量了飞行节肢动物和地面节肢动物的丰度和多样性（即阿尔法多样性和贝塔多样性）。我们发现，高移动性的飞行节肢动物的丰度和多样性不受栖息地连通性的影响，而移动性较差的地面节肢动物则受到了很大影响。与隔离斑块相比，对照样地和部分连通样地中地面节肢动物的平均总丰度分别高出2.5倍和2倍。我们还发现，栖息地连通性影响了地面节肢动物的营养相互作用，随着栖息地连通性的增加，捕食者（如狼蛛、地蜘蛛）与微型碎屑食性动物（跳虫、螨虫）高度正相关，但与大型碎屑食性动物（千足虫、等足类动物）无此相关性。这些研究结果共同表明，栖息地连通性的变化会改变地面节肢动物等移动性较差生物的集合群落结构。鉴于它们在陆地生态系统功能和服务中的重要作用，我们建议保护主义者、恢复实践者和土地管理者在设计生物多样性管理计划时纳入地面节肢动物栖息地连通性原则。
