Heterogeneity of forest landscapes and the distribution and abundance of the southern pine beetle

A fundamental and unanswered research question in landscape ecology centers on how the spatial arrangement of ecosystems influences the distribution a nd abundance of organisms across complex landscape mosaics. In this study o ur god was to examine how the southern pine beetle (SPB) perceives and resp onds to heterogeneity in forest landscape mosaics. The study was based on t he use of extant knowledge of SPB's natural history and a spatially referen ced database that included explicit information on landscape structure as w ell as distribution and abundance of the insect. Both the content and conte xt of the spatial elements forming the forest landscape were considered, as human-caused fragmentation and natural disturbances create mosaic patterns where the specific arrangement of components can enhance or inhibit herbiv ory by the SPB. To examine how heterogeneity influences epidemiology of the SPB, we identified the elements of landscape structure that serve as targe ts for SPB. The principal targets include three types or arrangements of ho st trees: acceptable species, susceptible habitat patches, and lightning-st ruck hosts. Using a spatial database and a statistical approach we evaluate d the number and arrangement of these targets in the context of existing po pulation centers. The product was a functional heterogeneity map that portr ayed how the spatial arrangement of landscape elements (habitat targets) in fluences the distribution and abundance of the SPB across complex mosaics o f ecosystems. (C) 1999 Elsevier Science B.V. All rights reserved.