Bees use anthropogenic habitats despite strong natural habitat preferences

Aim: Habitat loss and alteration are widely considered one of the main drivers of current pollinator diversity loss. Yet little is known about habitat importance and preferences for major groups of pollinators, although this information is crucial to anticipate and mitigate the current decline of their populations. We aim to rank and assess the importance of different habitats for bees, to determine the preference for and avoidance of particular habitat types by different bees, and to quantify the diversity of bees within and among habitats. Location: Northeastern US. Time period: The sampling was done over 15 years (2001-2015). Major taxa studied: Apoidea Methods: We used an unprecedented extensive dataset of >15,000 bee specimens, comprising more than 400 species collected across northeast USA. We extracted habitat information from the points and used network analyses, null models comparisons and beta-diversity analysis to assess habitat importance, habitat preference, use and diversity. Results: We found that natural habitats sustain higher bee diversity and a different set of species than agricultural and urban areas. Although many bee species can use human-altered habitats, most species exhibited strong preferences for forested habitats and only a few preferred altered habitats over more natural habitats. In contrast to previous studies, landscape composition only had moderate buffer effects on diversity loss. The loss of biodiversity in human-altered environments could have been higher had not been partially compensated by the presence of human commensals and exotic species. Main conclusions: Although human-altered environments may harbor a substantial number of species, our work reveals that preserving natural areas is still essential to guarantee the conservation of bee biodiversity.

研究目的：栖息地丧失与改造被公认为当前传粉昆虫（pollinator）多样性丧失的核心驱动因素之一。尽管此类信息对预判并缓解传粉昆虫种群衰退至关重要，但学界对主要传粉昆虫类群的栖息地重要性与栖息偏好的认知仍较为匮乏。本研究旨在对不同栖息地在蜂类保育中的重要性开展排序与评估，明确不同蜂类类群对特定栖息地类型的偏好与规避行为，并量化各栖息地内部及栖息地间的蜂类多样性。
研究区域：美国东北部。
时间跨度：采样工作历时15年（2001—2015年）。
研究类群：蜜蜂总科（Apoidea）。
研究方法：本研究采用一套前所未有的大规模数据集，包含在美国东北部采集的逾15000号蜂类标本，涵盖400余个蜂类物种。研究人员从采样点位提取栖息地相关信息，并通过网络分析、零模型对比及β多样性分析，对栖息地重要性、栖息偏好、利用模式及物种多样性进行量化评估。
研究结果：相较于农业与城市生境，自然栖息地能够维持更高的蜂类多样性，并支撑独特的物种群落。尽管诸多蜂类可利用人为改造后的栖息地，但多数蜂类对森林生境表现出强烈偏好，仅有少数物种相较于自然生境更偏好受干扰生境。与既往研究结论不同的是，景观组成对多样性丧失仅存在中等程度的缓冲效应。若无人为共生种与外来物种的部分补偿，人为干扰环境中的生物多样性损失本可能更为显著。
主要结论：尽管人为改造的栖息地可容纳相当数量的物种，但本研究证实，保护自然区域仍是保障蜂类生物多样性保育的核心前提。