Assessing habitat disturbance using an historical perspective: The case of Salisbury Plain military training area

Chalk grasslands are a habitat with high European importance for both flora and fauna. The largest known expanse of unimproved chalk grassland in north-west Europe lies within the Salisbury Plain training area (SPTA) in SW England, where sole use of the land for military training since the end of the nineteenth century has limited the ecologically damaging impacts of modern intensive agriculture. Organisational changes in the British Army may now paradoxically be threatening this unique ecological resource. In this study, historical aerial photograph analysis was carried out for SPTA using images from the 1940s through to the mid 1990s. Image analysis software enabled the creation of a model that analysed the extent and pattern of high intensity military disturbance on SPTA at a local landscape scale. Although trends in disturbance vary across SPTA for the time period under investigation, the average annual increase in bare ground since WWII has been in the region of 25·5 ha. These trends indicate that disturbance is occurring at a greater rate than natural regeneration, representing a significant threat to the chalk grassland through habitat loss and fragmentation.