Monoculture and mixture-planting of non-native Douglas fir alters species composition, but promotes the diversity of ground beetles in a temperate forest system

Abstract Planting non-native tree species, like Douglas fir in temperate European forest systems, is encouraged to mitigate effects of climate change. However, monocultures often revealed negative on biota, while mixtures with native species ecosystems are less well understood. We investigated three (Douglas fir, Norway spruce, beech), ground beetles forests Germany. Beetles were sampled each and broadleaf-conifer pitfall traps, environmental variables assessed around trap. used linear mixed models a two-step procedure disentangle environment identity beetle abundance, richness, functional diversity assemblage structure. Contradictory our expectations, abundance was highest pure stands, showed intermediate values between coniferous beech stands. The main drivers these patterns only partially dependent identity, which highlights the importance structural features study distinct shifts structure eased through mixture planting. Our findings suggest that planting trees associated biodiversity can be actively modified by promoting beneficial structures. Nevertheless, integrating even trees, will invariably alter structures compromise conservation efforts targeted at typical composition.