Comparison of abiotic and structurally defined patch patterns in a hypothetical forest landscape

An understanding of landscape patterns is now considered essential information in developing programs for biological conservation. We examined the adequacy of conventional approaches to landscape-pattern characterization by evaluating the spatial patterns in environmental conditions and their ecological implications at the landscape level. Six factors were varied in a hypothetical, managed, old-growth Douglas-fir (Pseudotsuga menziesii [Mirb.] Franko) landscape of 3000 ha in the Pacific Northwest: two variables were associated with biotic processes and four with abiotic processes. The two biotic variables represented the distribution of habitat for edge and interior forest species. The abiotic variables included air temperature at dawn and noon, wind speed, and direct solar radiation. The area of edge influence between forest patches and the clearcut matrix was simulated as a unique landscape element in the spatial analysis. The structurally defined landscape pattern (based on vegetation or soil type) differed clearly from the patterns associated with the six variables, which also differed among themselves. Spatial patterns changed at various temporal scales, substantiating the notion that landscape patterns of abiotic variables are very dynamic. Area of edge influence played an important role in configuring spatial patterns of a landscape, occupied much area in the landscape, and significantly influenced ecosystem structure and function. Simulation results showed that landscape patterns based solely on traditional structural parameters are limited in their usefulness because the ecological landscape is the integration of all variables and the associated movement of energy, materials, and species. This information about landscape patterns delincated by various biotic and abiotic variables is critical in reserve design and monitoring and in managing habitats for target species across landscapes. Efforts to describe the ecological function of an area will have to consider not only structurally-defined patches but also patterns in abiotic variables that are typically not congruent with structural patches and showing daily and seasonal change.