Linking landscapes to wetland condition: A case study of eight headwater complexes in Pennsylvania

A major focus of wetland management is on documenting condition, identifying stressors, and determining the relationship between the two. One challenge of this work is to relate and understand the pathways between stressors that are being controlled at the landscape scale to microbially mediated ecosystem -processes (e.g., nitrification, denitrification, decomposition, methanogenesis) -happening at much smaller spatial extents. In this chapter, we use a preexisting multiple-stress function (alternately termed an anthropogenic or human disturbance indicator) to select study sites for comparison of condition metrics. More specifically, this is a case study of eight headwater complexes, four reference standard sites, and four stressed sites, where landscape and site level structural components are compared and contrasted. The site level components that were selected for this analysis were those known to influence microbially mediated ecosystem processes. We reveal many significant differences in these groups for both landscape parameters across space and time, and in site level components. In addition to collecting process-based data, we suggest that connecting structural baseline data such as those parameters described herein with process-based models, as a way to begin to hypothesize what the collective effects of wetland components are on microbially mediated ecosystem processes, as well as to understand which components are most influential. With this understanding it becomes easier to link processes to landscape-driven stressors, through preexisting knowledge about the links between stressors and wetland structure. We also suggest shifting some attention to spatiotemporal dynamics of the stressor(s), in order to determine the feasibility in managing, restoring, and/or protecting wetland ecosystems.