Patterns of β-diversity can provide insight into forces shaping community assembly. We analyzed species-rich insect assemblages in two reserve fragments that had once been part of one contiguous Mediterranean coastal pine forest. Local environments are still similar across both fragments, but their landscape context differs strongly, with one surrounded by intense agricultural land, while the other neighbors the urbanized area of Ravenna. Using 23,870 light-trap records of 392 moth species, and multiple local and landscape metrics, we compared the relative importance of habitat- versus landscape-scale environmental factors for shaping small-scale variation in differentiation and proportional insect β-diversity across 30 sites per reserve. Moth assemblage composition differed substantially between fragments, most likely due to ecological drift and landscape-scale variation. For proportional β-diversity, especially local forest structure was important. At well-developed forest sites, additive homogenization could be observed, whereas the lack of typical forest species at dry, dense, and younger forest sites increased species turnover (subtractive heterogenization). For differentiation β-diversity, local and landscape-scale factors were equally important in both reserves. At the landscape-scale (500 m radius around light-trapping sites) the proximity to urban areas and the fraction of human-altered land were most important. At the habitat scale, gradients in soil humidity, nutrient levels and forest structure mattered most, whereas plant diversity had very little explanatory power. Overall, landscape-scale anthropogenic alterations had major effects on moth communities inside the two conservation areas. Yet, even for these parts of one formerly contiguous forest trajectories in community change were remarkably idiosyncratic.

β-多样性的模式可以提供对塑造群落组装的力量的洞察。我们分析了两个保护区碎片中物种丰富的昆虫组合，这些碎片曾经是一片毗邻的地中海沿岸松树林的一部分。两个片段的当地环境仍然相似，但它们的景观背景差异很大，一个被密集的农田包围，而另一个毗邻拉文纳的城市化地区。使用 392 种蛾类的 23,870 条光阱记录以及多个当地和景观指标，我们比较了栖息地与景观尺度环境因素的相对重要性，以在每个 30 个地点形成分化的小尺度变化和成比例的昆虫 β-多样性。预订。飞蛾组合组成在碎片之间有很大差异，很可能是由于生态漂移和景观尺度变化。对于成比例的β-多样性，特别是当地的森林结构很重要。在发达的森林地点，可以观察到加性同质化，而在干燥、茂密和较年轻的森林地点缺乏典型的森林物种会增加物种周转率（减法异质化）。对于分化β-多样性，地方和景观尺度因素在两个保护区中同样重要。在景观尺度上（采光点周围半径 500 米），靠近城市地区和人类改造土地的比例是最重要的。在栖息地尺度上，土壤湿度、养分水平和森林结构的梯度最为重要，而植物多样性几乎没有解释力。全面的，景观尺度的人为改变对两个保护区内的飞蛾群落产生了重大影响。然而，即使对于以前连续森林的这些部分，社区变化的轨迹也非常特殊。