Changes in bee (Hymenoptera: Anthophila) diversity during forest stand succession after final felling

Due to the loss and degradation of natural and semi-natural grasslands, many grassland specialist insect species are forced to inhabit roadsides, quarries and other anthropogenic sites. Amongst such substitute habitats, clear-cuts have been shown to provide a habitat for a variety of insect species found in grasslands and other open biotopes. However, it is not entirely clear how bee communities change over time as these sites undergo rapid early succession after final felling. In this study, we focused on how bee diversity changes in clear-cuts during succession (1–30 years), and which patch (forest stand age and area) and vegetation descriptors best explain these changes. Using coloured pan traps and generalised mixed effects modelling, we found that bee diversity was highest in younger forest stands and decreased until 10 years of age, after which it remained consistently low. Higher bee diversity was found in forest stands with a larger area and a higher diversity of flowering plant genera, while flower cover and specific plant genera abundance were not significant. The results show that clear-cuts are exploited by bees and can support their populations. However, it is important to consider the conflict of conservation targets between locally hosting temporal bee populations and negatively influencing numerous forest specialist species.