Cumulative effects on wetland landscapes: Links to wetland restoration in the United States and Southern Canada

Abstract

The cumulative effects of human actions on wetland ecosystems motivate current efforts at wetland restoration. They also have created in part the context within which restorations are undertaken. Using modern hydrogeological understanding of wetland-landscape linkages, I argue that restorations should begin with a cumulative impact analysis for the entire region in which the restoration is proposed. The analysis, however, should not focus merely on number of hectares of wetlands lost or degraded. It should be based on the concept of templates for wetland development. These templates are the diversity of settings created in specific landscapes by the complex interactions of hydrogeologic factors and climate. They control key hydrologic variables and hydrologically influenced chemical variables that cause specific wetland types to form and to be maintained through time. They also determine in large part the biogeochemical cycling characteristics specific to different types of wetlands. They thus account for both the biological and functional diversity of wetlands. A cumulative impact assessment for restoration purposes should identify the kinds, numbers, relative abundances, and spatial distribution of wetland templates in a region-both past and present. These past and present profiles of the wetland landscape can be used to make decisions regarding the type and location of restorations. Matching type and location to the appropriate hydrogeologic setting will maximize the probability of success for individual projects. Regional wetland diversity can be restored if individual restoration decisions about wetland type and location are made in light of the diversity of templates in past and present regional profiles.