Bigger, better hedgerows - assessing hedge structure and landscape context for pollinating insects

Biodiversity is in decline, including key insect taxa such as butterflies and other pollinators. Hedgerows are important semi-natural habitats in agricultural landscapes, providing resources and refuges for animals and plants, and supporting ecosystem services including pollination. The role of hedges in enhancing biodiversity is recognised in the 25-year Environment Plan. A substantial increase in hedgerow extent has been proposed by government, to mitigate biodiversity loss and increase carbon sequestration but we do not know the best places to plant these hedgerows to maximise the benefits they can deliver.

In addition, hedgerow condition is important for many taxa, including butterflies and other pollinators. Less than 50% of hedges are in good condition in terms of their size and gappiness8, suggesting a potential missed opportunity for current hedges to effectively support biodiversity.

This project will address the challenge of understanding the relative importance of location, habitat quality, extent and age of hedgerows for pollinators and butterflies, to inform management and policy for improving the UK hedgerow network and delivery of biodiversity benefits.

Research objectives:
1) Using national Citizen Science datasets, measure how pollinating insects including butterflies respond to hedgerow size and extent, and how this is modified by surrounding landscape context.
2) Collect new field data to test whether local habitat quality (hedgerow structural condition, woody species composition) is more important than hedgerow extent in the surrounding landscape for pollinating insects.
3) Assess how hedgerow age affects their utilisation by mobile insects, and how long after planting hedges become a useful biodiversity habitat.