The high diversity of insects has limited the volume of long-term community data with a high taxonomic resolution and considerable geographic replications, especially in forests. Therefore, trends and causes of changes are poorly understood. Here we analyse trends in species richness, abundance and biomass of nocturnal macro moths in three quantitative data sets collected over four decades in forests in southern Germany. Two local data sets, one from coppiced oak forests and one from high oak forests included 125K and 48K specimens from 559 and 532 species, respectively. A third regional data set, representing all forest types in the temperate zone of central Europe comprised 735K specimens from 848 species. Generalized additive mixed models revealed temporal declines in species richness (−38%), abundance (−53%) and biomass (−57%) at the regional scale. These were more pronounced in plant host specialists and in dark coloured species. In contrast, the local coppiced oak forests showed an increase, in species richness (+62%), while the high oak forests showed no clear trends. Left and right censoring as well as cross validation confirmed the robustness of the analyses, which led to four conclusions. First, the decline in insects appears in hyper diverse insect groups in forests and affects species richness, abundance and biomass. Second, the pronounced decline in host specialists suggests habitat loss as an important driver of the observed decline. Third, the more severe decline in dark species might be an indication of global warming as a potential driver. Fourth, the trends in coppiced oak forests indicate that maintaining complex and diverse forest ecosystems through active management may be a promising conservation strategy in order to counteract negative trends in biodiversity, alongside rewilding approaches.

中文翻译：

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寄主特异性和物种着色介导中欧森林夜蛾的区域衰退

昆虫的高度多样性限制了具有高分类分辨率和大量地理复制的长期群落数据量，尤其是在森林中。因此，人们对变化的趋势和原因知之甚少。在这里，我们在德国南部森林中收集了 4 年的三个定量数据集中分析了夜间大型蛾类的物种丰富度、丰度和生物量的趋势。两个本地数据集，一个来自矮化橡树林，另一个来自高橡树林，分别包括来自 559 和 532 个物种的 125K 和 48K 标本。第三个区域数据集代表中欧温带地区的所有森林类型，包含来自 848 个物种的 735K 标本。广义加性混合模型显示物种丰富度随时间下降（-38%），区域尺度的丰度 (-53%) 和生物量 (-57%)。这些在植物宿主专家和深色物种中更为明显。相比之下，当地矮化橡树林的物种丰富度有所增加（+ 62％），而高橡树林则没有明显的趋势。左右审查以及交叉验证证实了分析的稳健性，从而得出四个结论。首先，昆虫的减少出现在森林中高度多样化的昆虫群中，并影响物种丰富度、丰度和生物量。其次，宿主专家的显着下降表明栖息地丧失是观察到的下降的重要驱动因素。第三，黑暗物种更严重的减少可能表明全球变暖是一个潜在的驱动因素。第四，