Natural areas are important for wild bees in human-dominated landscapes as they provide permanent feeding and nesting resources. Understanding how bee communities vary with the amount of natural areas is thus key to guide conservation measures. This information, however, is largely lacking in montane tropical ecosystems. Here we explore to what extent the amount of forest area or forest edge (as landscape variables) influence the species richness and abundance of forest-edge associated bees in the Colombian Andes. In addition, we assess the effects of flower species richness and abundance (as local variables) to better understand the individual and interactive effects of forest conservation. Bees were surveyed along 20 forest edges differing in forest proportion and forest edge length within four spatial scales (250, 500, 1000 and 1500 m radii). We conducted trait-specific analyses as bees with different traits associated to body size, sociality and nesting behavior might differ in their response to local and landscape variables. We found that overall bee species richness and abundance increased with an increasing proportion of forest within 1000 m radius, but also with flower abundance. Similarly, the species richness and abundance of social, large and above-ground nesting bees increased with an increasing proportion of forest area, mainly within 500 and 1000 m radii. However, only the abundance (not the species richness) of solitary and small bees were positively related to the proportion of forest within 1000 m. Below-ground nesters did not respond to the individual effect of forest area at any spatial scale. Interactive effects between local and landscape variables were mainly found between flower richness and the proportion of forest. Forest edge length influenced only the abundance of solitary bees. These findings highlight the importance of conserving and/or restoring forest areas – at meaningful spatial scales – to promote diverse bee communities in montane tropical regions.

中文翻译：

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森林边缘相关蜜蜂受益于热带森林的比例，无论其边缘长度如何

自然区域对于人类主导的景观中的野生蜜蜂非常重要，因为它们提供永久的觅食和筑巢资源。因此，了解蜜蜂群落如何随自然区域的数量变化是指导保护措施的关键。然而，山地热带生态系统很大程度上缺乏这些信息。在这里，我们探讨了森林面积或森林边缘的数量（作为景观变量）在多大程度上影响哥伦比亚安第斯山脉森林边缘相关蜜蜂的物种丰富度和丰度。此外，我们还评估花卉物种丰富度和丰度（作为局部变量）的影响，以更好地了解森林保护的个体和互动效应。在四个空间尺度（250、500、1000 和 1500 m 半径）内，沿着 20 个森林比例和森林边缘长度不同的森林边缘对蜜蜂进行了调查。我们进行了特定性状分析，因为具有与体型、社交性和筑巢行为相关的不同特征的蜜蜂对当地和景观变量的反应可能不同。我们发现，随着 1000 米半径内森林比例的增加，蜜蜂物种的整体丰富度和丰富度也随之增加，而且花朵的丰富度也随之增加。同样，社会性、大型和地上筑巢蜜蜂的物种丰富度和丰度随着森林面积比例的增加而增加，主要在 500 和 1000 m 半径范围内。然而，只有独居和小型蜜蜂的丰度（而不是物种丰富度）与1000 m以内的森林比例呈正相关。地下筑巢者在任何空间尺度上都对森林面积的个体效应没有反应。局部变量和景观变量之间的交互作用主要体现在花卉丰富度和森林比例之间。森林边缘长度仅影响独居蜜蜂的数量。这些发现强调了在有意义的空间尺度上保护和/或恢复森林地区对于促进山地热带地区蜜蜂群落多样化的重要性。