Measuring success: performance standards and trajectories of ecosystem development

Evaluating success of wetland restoration projects requires measurements of community structure and ecosystem processes that are compared with prerestoration measurements or more commonly, with measurements in one or more high-quality, natural reference wetlands of the same geomorphic and vegetation type and in the same watershed. Measured attributes are referred to as performance standards and are chosen to document and track physical (hydrology), chemical (water quality, soils), and biological (vegetation, fauna, microorganisms) characteristics of the site over time based on preestablished goals. Vegetation is frequently used to gauge health of existing wetlands and success of restored sites using assessment methods such as rapid assessment methods, floristic quality index, and the hydrogeomorphic approach to assess wetland functions. Attributes of structure and function often progress along pathways or trajectories that describe ecosystem development over time. Trajectories may be linear or curvilinear, and some standards take longer to develop than others. Performance standards should be chosen to reflect the goals of a particular restoration project, be it improvement in water quality or enhancement of biodiversity.