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 a g e s 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.

Decomposition Trends of Five Plant Litter Types in Mitigated and Reference Wetlands in West Virginia, USA

“…wetlands than in natural sites. Spieles and Mora (2007) studied decomposition rates at three created wetlands of different ages (4, 12 and 155 years) in Ohio and found that decomposition rates were highest in the 4-year-old wetland, lowest in the 12-year-old wetland, and intermediate in the 155-year-old wetland. Álvares and Bécares (2006) found Typha latifolia decomposition rates in a created wetland in Spain were similar to rates reported in the literature.…”

“…It is directly and indirectly linked to many other wetland processes. This makes it an effective tool for assessing the development of ecosystem function in created systems (Spieles and Mora 2007). Decomposition is important as a driving force in nutrient cycling and supports major flows of nutrients along detrital pathways in ecosystems (Brinson et al 1981;Webster and Benfield 1986;Berg and Laskowski 2005).…”

Litter decomposition in created and reference wetlands in West Virginia, USA

“…Similar results were noted in this study, with the second oldest wetland (27 year) having the lowest decomposition rate constant. Though age was not correlated with decomposition rate, Spieles and Mora (2007) found that wetland hydrology (mean water depth and exposure frequency) was significantly correlated and concluded that site conditions explained decomposition rate better than wetland age. We suspect that this was likely the case at the wetlands in this study.…”

“…Spieles and Mora (2007) compared decomposition rates in a 4, 12, and 155-year-old wetland and found that the 4-year-old wetland had the greatest decomposition rate while the 12-year-old wetland had the lowest rate. Similar results were noted in this study, with the second oldest wetland (27 year) having the lowest decomposition rate constant.…”

“…Decomposition is linked to wetland services such as invertebrate and wildlife habitat through primary production and detritus availability (Burdett and Watts 2009;Taylor and Batzer 2010), to carbon storage through organic matter accumulation (Bridgham et al 2006), to sediment and mineral retention through primary productivity and organic matter accumulation (Braskerud 2000, Rooth et al 2003 and to stream nutrient availability through nutrient cycling (Richardson 1994;Mitsch and Gosselink 2007). It is this web of interactions that allows decomposition rate to influence a wetland's functions and services and which makes it a potential tool for assessing the evolution of overall ecosystem function (Spieles and Mora 2007).…”