Plant decomposition and litter accumulation in depressional wetlands: Functional performance of two wetland age classes that were created via excavation

Plant decomposition and litter accumulation are important components of wetland functions, yet they have rarely been evaluated in created wetlands. In this study, eleven 20-yr and six 2-yr-old depressional wetlands, the most common type of created wetlands, were investigated. We measured plant decomposition as mass loss over 507 days for both age classes and litter accumulation as litter (detritus) mass present in the 20-yr-old wetlands. The wetlands were all created via excavation and contained shallow facultative wetland and deeper obligate wetland plant communities that were often dominated by Scirpus cyperinus and Typha latifolia, respectively. In the decomposition study, stems and leaves from each species were harvested from an adjacent 20-yr-old wetland site and placed in separate plastic mesh bags. Bags were deployed in March 1994 and were recovered after 2, 161, 258, 364, and 507 days. In the litter accumulation study, plant litter that accumulated on top of alluvium was harvested in 0.25...