Changing importance of habitat structure across multiple spatial scales for three species of insects


M. A. Krawchuk and P. D. Taylor, Atlantic Co-operative Wildlife Research Network, Biology Dept, Acadia Univ., Wolfville, Nova Scotia, Canada B0P 1X0. Present address for MAK: Dept of Renewable Resources, Univ. of Alberta, 7-51 General Services Building, Edmonton, Alberta, Canada T6G 2H1 (


Considerable scientific effort has gone into examining how the spatial structure of habitat influences organism distribution and abundance in both theoretical and applied contexts. An emerging conclusion from these works is that the overall amount of habitat in the landscape matters most for species persistence and that more local attributes of habitat structure such as the size and arrangement of patches is of secondary importance. In this study, we quantify how and when the effects of habitat configuration (patch size and isolation) influence the density of three species of insects (Order: Diptera; Wyeomyia smithii, Metriocnemus knabi, Fletcherimyia fletcheri) whose larvae are found exclusively in identical habitats (the water-filled leaves of pitcher plants –Sarracenia purpurea) in a system that is naturally patchy at multiple spatial scales. We illustrate that relationships with configuration exist regardless of the overall amount of habitat in the broader landscape, and that there are distinct changes in the relationship between insect density and habitat configuration across multiple spatial scales. In general, patch size is more important within the movement range of the individual and isolation is important at larger, aggregation scales. Thus we demonstrate that a) both the amount and configuration of habitat are important attributes of species distribution; b) responses to measures of configuration can be scaled to processes such as movement and c) that hierarchical frameworks extending across very broad scales are essential for understanding how species respond to habitat structure and their role in ecosystem function.