Standing Litter Decomposition and the Role of Dew and Solar Radiation in a Freshwater Wetland

Standing litter decomposition generally plays important roles in biogeochemical cycling in wetlands. By contrast with dew, the role of solar radiation receives less attention in humid ecosystems. Here, we determined aerial decomposition dynamics of five litters in a freshwater wetland in the Yangtze-Huaihe basin. Moreover, we analyzed the role of dew and sunlight in the decomposition of Phragmites australis culm and leaf based on a simulation experiment. After 360 days of field decomposition, the mass loss ranged from 31.1% to 80.7%, significantly relating to litter nutrient, cellulose, and lignin concentrations. In the simulation experiment, the sunlight treatment rather than the dew treatment facilitated mass loss of culm, and the mass loss in the dew + sunlight treatment was greater than the sunlight treatment. For the leaf, both sunlight and dew treatments increased mass loss, and the mass loss in the dew + sunlight treatment was greater relative to that in the dew and the sunlight treatments. In addition, the mass loss was not significantly different between the sterilization and the control treatments, irrespective of tissue. However, the sterilization + sunlight treatment increased the mass loss of culm, despite no significant effects on the leaf. These findings confirm the importance of standing litter in biogeochemical cycling of freshwater wetlands in the Yangtze-Huaihe basin. Moreover, this study highlights the important role of sunlight and its combined action with dew in regulating litter decomposition in humid ecosystems, where the specific role varies with litter quality.