Taxonomic and community composition of epigeal arthropods in monoculture and mixed tree species plantations in a deciduous forest of Ghana

Tropical forests provide several ecosystem services and functions and support approximately two-thirds of the world's biodiversity but are seriously threatened by deforestation. Approaches to counteract this menace have revolved around afforestation with several or a single tree species. We thus investigated how plantation forests with either a single or several tree species influenced arthropod taxonomic and community composition using pitfall traps to sample selected groups of epigeal arthropods (Araneae, Coleoptera, Orthoptera and Hymenoptera) and with environmental variables assessed simultaneously. Our results revealed 54 taxonomic groups with significantly higher taxonomic richness, activity density, and diversity in the mixed stands than in the monoculture stands. The significant differences in community composition were mainly driven by families including Lycosidae, Formicidae, Staphylinidae, Scotylidae, Hydrophilidae, Gryllidae and Scarabaeidae and were explained by distinct habitat characteristics (canopy openness, litter depth, deadwood volume, and tree height). While the diverse tree communities and heterogeneous vegetation structure offered food and habitat resources for diverse arthropod groups, the allelopathic nature coupled with homogenous stand characteristics of the Tectona grandis stands in the monoculture suppressed the growth of understorey vegetation that could otherwise serve as food and habitat resources for arthropods, which might have led to limited activities and diversity of arthropods in the monoculture plantation stands. The findings thus highlight the need to promote mixed tree plantations in degraded tropical areas, especially when restoring biodiversity is the prime management focus.

Automated summary

Plantation forests with mixed tree species have higher taxonomic richness, activity density, and diversity of arthropods compared to monoculture stands. The differences in community composition are mainly driven by distinct habitat characteristics. Monoculture stands suppress understorey vegetation growth, limiting food and habitat resources for arthropods.