Loss of specialized arthropods and community turnover caused by planting non-native trees in Temperate forests

This is the authors' abstract. We don't add key points for this paper.

Planting non-native tree species is widely discussed as a strategy to mitigate the productivity-related risks that climate change poses to European forestry. At the same time, conservation scientists broadly agree that non-native monocultures can harm biodiversity. However, the responses of individual species and communities to non-native trees are not uniform and remain poorly understood, especially in mixed forests. Here, we examine canopy-associated arthropod communities on 13 native and non-native broadleaved and coniferous tree species in temperate mixed forests in southwest Germany using an environmental DNA metabarcoding approach with canopy leaves as substrate. At the level of entire arthropod communities, we found that non-native coniferous trees were associated with significant losses of α-diversity. This effect of non-native trees was not observed in broadleaved species. In contrast, we found significant declines in specialist arthropod species richness in both broadleaved and coniferous trees. While β-diversity analyses showed strong effects of tree species identity on community composition, no signal of biotic homogenization was found in non-native trees. However, the strong tree specific effects on community composition suggest that the planting of non-native trees will result in a pronounced turnover of the resident canopy arthropod community. This is assumed because each tree species supports a distinct arthropod community. Overall, our findings support that widespread use of non-native trees in climate-adaptive forestry may come with considerable effects on arthropod diversity.