Impact of woodland agri-environment management on woodland structure and target bird species

Abstract

Agri-environment incentives form a central mechanism supporting changes to land management to provide public benefits. This study assesses the medium-term effects of woodland management on 13 target, specialist woodland bird species, as well as other woodland birds in a single region of the UK. The abundance of breeding birds (using two methods: point counts and territory mapping) and metrics of woodland structure were recorded on sites with Woodland Improvement Grants (improvement sites) and nearby comparison sites (control sites). Initial measurements were made prior to management and repeated 7-9 years later. A separate comparison of changes in bird abundance was made between the managed woodland sites and woodland from similar landscapes surveyed as part of the national Breeding Bird Survey (BBS). There was an increase in abundance of target species on improvement sites compared to a decrease on both control sites and BBS sites, although this was only evident from point count data. The effects on target species were stronger than for other woodland specialists and there was no apparent effect on woodland generalists, suggesting that the management interventions were appropriate for the target species. Changes in woodland structure were generally consistent with the expected effect of management, with lower tree density and greater Bramble (Rubus sp.) cover. However, contrary to the aim of increasing understorey cover, a reduction was recorded within the 2-10 m height category in improvement sites. This contrast is due to the removal of young trees during thinning affecting this height band and the short time period since management to allow regrowth. Our findings show that bespoke management supported through government agri-environment incentives can have a positive impact on target woodland birds. For managed forests, identifying species requirements and how management can be adapted to improve their habitats can be an effective way of delivering biodiversity gains when financial incentives are provided to achieve policy goals.

Keywords: Agri-environment; Public funding; Targeted woodland management; Woodland birds; Woodland structure.