Global Ecology and Conservation (Jan 2022)
Fragmentation of forest-steppe predicts functional community composition of wild bee and wasp communities
Abstract
Increased habitat fragmentation in natural areas is one of the causes of declining insect diversity and biomass globally. Wild bees and wasps and their ecosystem functions are not exceptions of the trend. To stop this trend, we need to increase our understanding of interactions between functional traits and the environment for better informing conservation and restoration. Therefore, we studied how habitat fragmentation (i.e., connectivity, fragment size) and flower availability (abundance and species richness) affect functional traits of wild bees and wasps. Forest‐steppe is a complex ecosystem ranging from far East of Asia to Eastern Central Europe, consisting of a mosaic of woody and herbaceous vegetation patches. We selected 30 natural forest-steppe fragments along a connectivity gradient in the Hungarian Great Plain region. The size of the selected fragments ranged between 0.16 and 6.88 ha. We collected wild bees and wasps with yellow pan traps. We selected four functional traits: social habit, body size, feeding preference, and nesting location and investigated them in relation to habitat connectivity, patch size, flower abundance and richness. We used RLQ ordination to analyse the pollinators' functional community composition. We found that habitat connectivity supported larger, eusocial and ground nesting wild bees. Fragment size was closely related to larvae feeding preference in both studied groups by positively affecting oligolectic bees and carnivore wasps. Additionally, higher abundance and species richness of flowers maintained polygolectic bees and solitary, ground-nesting wasps. In our study, we described for the first time the relationship between the functional traits and habitat fragmentation of wild bee and wasp communities in a natural forest-steppe habitat. Our findings suggest that improved knowledge about the response of functional traits of wild bee and wasp communities to habitat fragmentation will allow a better understanding and prediction of subsequent effects on ecosystem functioning. We conclude that a combination of large, high-quality and well-connected patches maintains specialist wild bee and wasp communities.
