Effects of forest diversification on floral reward production for pollinators

The herb layer in forests has a large potential to provide nectar and pollen for pollinators, but forest management practices such as planting tree species mixtures vs monocultures can affect floral reward production by the herb layer via changes in understorey environment. This project will explore the effects of tree species diversity and composition on quantity and quality of the nectar and pollen produced by the herb layer, the underlying mechanisms of the above effects, and the consequences of variation in floral reward production for pollinator visitation and plant fitness. The project will use the Satakunta forest diversity experiment in Finland (https://www.sataforestdiversity.org/) which consists of plots planted with monocultures and species mixtures of different broadleaves and conifers. Quantity and chemistry of nectar and pollen produced by different understorey plant species will be compared between tree monocultures and species mixtures. To explore the underlying mechanisms of forest diversity effects, microclimatic conditions of understorey and flowering phenology of herb species in tree monocultures and mixtures will be compared. To explore the consequences of variation in floral reward production, frequency and duration of visits by different pollinator species in monocultures and mixtures and herb plant fitness will be studied. The results of the project will contribute to development of pollinator-friendly forms of forest management.