Detrital Decomposition As a Measure of Ecosystem Function in Created Wetlands

ABSTRACT

Mitigation wetland performance is typically assessed with indicators of ecosystem structure and organization, such as plant community composition. While structural indicators can confirm the establishment of a wetland, the degree to which they measure system function is debatable. We evaluated the potential of coarse particulate litter decomposition as a measure of ecosystem function in three created wetlands of different hydrologic regimes and different ages—4, 12, and 155 years. We evaluated litter decomposition rates among the three wetlands relative to site-specific characteristics of vegetation, substrate conditions, and hydrologic regime. Decomposition rates differed among these wetlands, and age effects were strongly influenced by site conditions and environmental factors. Hydrologic regime was the most significant interaction factor with decomposition and likely was a confounding factor for an age-based trajectory of detrital dynamics. These results suggest that decomposition dynamics can be a useful indicator of developing ecosystem function but only in carefully selected wetlands of similar hydrologic regime.