Resolving a heated debate: The utility of prescribed burning as a management tool for biodiversity on lowland heath

Abstract

Lowland heath is a priority habitat for conservation, nowadays largely managed for biodiversity. Historically, prescribed burning has been the principal management tool, but there are increasing calls to substitute burning with cutting to improve biodiversity outcomes. However, poor understanding of potential impacts compromises decision making. Our study was carried out in the New Forest National Park, the largest area of lowland heath in Europe. Using a multi-trophic approach, we compared the ecological impact of prescribed burning with two types of vegetation cutting (swiping and baling) as management tools for biodiversity outcomes for up to 20 years after management. Indicators included: common standards monitoring (CSM) assessment; vegetation species assemblage; below- and above-ground invertebrate biodiversity; and available food resources for two characteristic heathland birds—the Dartford Warbler Sylvia undata and the Nightjar Caprimulgus europaeus. When compared with swiped sites, areas managed by prescribed burning resulted in: better habitat condition (assessed by CSM); higher cover of heathers; lower bracken cover; more areas of bare ground. We found no evidence that burning is detrimental for the investigated components of biodiversity. Cutting by swiping did not replicate the benefits of burning. Swiping supported grassland conditions that suit non-heathland species. Baling resulted in habitat condition similar to prescribed burning but restricted replication of baled sites limited our conclusions. However, swiped sites supported high invertebrate abundance and diversity, including food resources for Dartford Warbler and Nightjar. Synthesis and applications. Removing burning from the management programme is likely to reduce heathland condition. Biodiversity is encouraged by a mosaic of management and more mobile species, such as birds, will exploit the resources provided by several management techniques. Including some cutting in a rotational regime is likely to be beneficial although prescribed burning should form the majority of the management programme, Lowland heathland differs fundamentally from upland heathland/moorland and it is not easy to transfer the results. Current heathland CSM does not adequately assess wider biodiversity on protected areas but is effectively an assessment of vegetation feature condition. Including invertebrates in surveys provides a more nuanced assessment of heathland condition.