Assessing habitat disturbance using an historical perspective: The case ofSalisbury 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 nort h-west Europe lies within the Salisbury Plain training area (SPTA) in SW En gland, where sole use of the land for military training since the end of th e nineteenth century has limited the ecologically damaging impacts of moder n intensive agriculture. Organisational changes in the British Army may now paradoxically be threatening this unique ecological resource. In this stud y, historical aerial photograph analysis was carried out for SPTA using ima ges from the 1940s through to the mid 1990s. Image analysis software enable d the creation of a model that analysed the extent and pattern of high inte nsity military disturbance on SPTA at a local landscape scale. Although tre nds in disturbance vary across SPTA for the time period under investigation , the average annual increase in bare ground since WWII has been in the reg ion of 25.5ha. These trends indicate that disturbance is occurring at a gre ater rate than natural regeneration, representing a significant threat to t he chalk grassland through habitat loss and fragmentation. (C) 2000 Academi c Press.