Butterfly metapopulations in dynamic habitats

• Main Author: Hodgson, Jenny
• Published: University of York 2007
• Subjects: 591.7
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485097

Many species require habitats that are naturally patchily-distributed and ephemeral, but human activities fundamentally alter the rate and scale of habitat change. This thesis describes the development of a new metapopulation simulation model applicable to a broad range of species that depend on dynamic habitat. I apply the model to two' case studies, both involving butterfly species that use early-successional habitats and that are UK BiodiversIty Action Plan priority species. I describe. two methods for parameterising the model for a particular metapopulation in a particular landscape. One method uses parallel disturbance ar:d population presence data for a few consecutive years; the other derives population parameters and landscape parameters from separate data sources. In the first case study, I found that the BAP target for Heath Fritillary (Melitaea athalia) populations in the Blean Woods, Kent, could either be met by approximately doubling the coppicing effort, or by concentrating the existing effort into one of the larger woodland blocks. In the second case study, I found that the rate of heathland burning in the South Stack area of Angl~seywas not enough by itself to sustain the metapopulation of Silver-studded Blues (Plebejus argus). However, the metapopulation is probably saved from extinction by the existence of permanently-suitable habitat close to the coast. I have also elucidated an important phenomenon in metapopulations with dynamic habitat: the relationship between patch occupancy and patch connectivity can be obscured by the temporal changes in habitat. This has important implications for the debate about whether many real populations actually fit the metapopulation paradigm because the existence of metapopulation dynamics is often determined by testing the connectivity-occupancy relationship. The simulation model, 'MANAGE', is an important new tool for integrating landscape-scale information, and answering conservation questions, in a field which is relatively new and unexplored.