FORUM: THE ARBOREAL SUPERHIGHWAY: ARTHROPODS AND LANDSCAPE DYNAMICS

Species richness of arthropods in northern temperate coastal rain forests far exceeds previous estimates, and the functional significance that these species play in ecosytem processes remains largely unknown. Examination of several species, many of which are not yet described, indicates that these intact ancient rain forests are structurally complex and act as reservoirs for biological diversity. Forest harvesting and resulting fragmentation affects arthropod diversity by altering key patterns of natural processes which are inseparably linked to habitat diversity. Consequences for arthropods may vary but those species which are endemic or inseparably linked to habitat features found only in these forests are particularly vulnerable to fragmentation-induced changes. Several important questions arise. What are the implications of forest fragmentation on ecological processes? What role does dispersal play in arthropod population viability? Given the immense biodiversity of arthropods, what are the functional roles that the species play in these forests and how are these changed when forests are harvested? The lack of empirical evidence makes it difficult to answer these questions and to quantify the functional roles of arthropods in these ecosystems.To address these questions, I suggest that studies should not rely on single-species approaches and the measurement of diversity (i.e. species richness and abundance) but should focus on addressing the functional roles of forest arthropods. To move beyond the basic description of pattern I suggest that studies concentrate on describing species assemblages while including dynamic processes such as dispersal into the framework of how we think about arthropods in ancient forests. The use of feeding guilds in the development of predictive models may give us an understanding of these factors and provide information that could be used to examine functional patterns in community structure.