Conservation of birds in fragmented landscapes requires protected areas

For successful conservation of biodiversity, it is vital to know whether protected areas in increasingly fragmented landscapes effectively conserve species. However, how large habitat fragments must be and what level of protection is required to sustain species, remains poorly known. We compiled a global dataset on almost 2000 bird species in 741 forest fragments varying in size and protection status, and show that protection is associated with higher bird occurrence, especially for threatened species. Protection becomes increasingly important with increasing size of forest fragments. For forest fragments >50 ha our results show that strict protection (IUCN cat. I-IV) is strongly associated with higher bird occurrences, whereas fragments should be at least 175 ha to observe a positive effect of moderate protection (cat. V-VI). This meta-analysis quantifies the importance of fragment size, protection status, and their interaction for the conservation of bird species communities, and stresses that protection should not be limited to large pristine areas.若要成功开展生物多样性保护，明晰日益破碎化景观中的保护区能否切实发挥物种保护效能，至关重要。然而，当前学界对于维持物种存续所需的最小生境破碎斑块面积，以及对应的保护等级标准，仍知之甚少。本研究整合了一套全球数据集，涵盖741块面积与保护等级各异的森林生境破碎斑块中的近2000种鸟类，研究结果表明，保护措施与更高的鸟类出现率显著相关，这一现象在受威胁鸟类物种中尤为突出。保护措施的重要性会随森林生境破碎斑块面积的增大而愈发凸显。针对面积超过50公顷的森林破碎斑块，本研究结果显示，严格保护（IUCN 类别I-IV）与更高的鸟类出现率存在强相关性；而若要体现中度保护（IUCN 类别V-VI）的积极效应，森林破碎斑块的面积至少需达到175公顷。本项荟萃分析量化了破碎斑块面积、保护等级及其交互作用对鸟类群落保护的关键作用，并强调保护举措不应仅局限于大型原始未受干扰的区域。