Modeling the dynamics of wildlife habitats and populations at the landscape scale

A forest dynamics model (FORCLIM) was linked to a spatial wildlife population model (PATCH) to assess the effects of habitat change in a landscape on selected wildlife species.  The habitat changes included forest responses to harvesting, development, and climate change on a western Oregon landscape.  Two regionally common and well-studied bird species with contrasting habitat requirements were selected for analysis.  Winter wrens, typical of mature conifer forests, and song sparrows, typical of shrub-dominated areas, were modeled in the upper South Santiam Watershed of the Oregon Cascade Range.  Three levels of land use change (1990-2050) were considered: 1) a conservation trend, 2) a plan trend, and 3) a development trend.  In addition, three levels of climate change were considered for the same period: 1) no change, 2) somewhat warmer and slightly drier, 3) much warmer and wetter.  Using FORCLIM, these conditions were combined to create landscape maps of nine possible scenarios at seven time steps.  In turn, a set of landscape suitability maps was created for each bird species and used in PATCH.  From 1990 to 2050, winter wren populations were projected to decline steadily in the face of development.  Song sparrow populations declined, but then recovered under the plan trend and the development trend.  In the case of these two species under these particular conditions, land use change had greater habitat-mediated effects than did climate change.