Decomposition and Nutrient Release into Water from Litter Mixtures of Coastal Wetland Species.

Coastal wetlands are among the most carbon-rich ecosystems in the world. Litter decomposition is a major process controlling soil carbon input. Non-additive effect of litter mixture on decomposition has been observed in many terrestrial plants but rarely tested in coastal species. We selected three common mangrove species and one saltmarsh species co-occurring in subtropical coasts to test whether the non-additive effect occurs when their litters mixed together, and how the nutrients release into water are impacted consequently. A litter-bag experiment was carried out in a glasshouse with single and mixed leaf litters. Non-additive effects were observed in the litter mixtures of mangrove species Aegiceras corniculatum vs. Kandelia obovata (antagonistic) and A. corniculatum vs. Avicennia marina (synergistic), but not in the litter mixtures of A. corniculatum (mangrove species) vs. Spartina alterniflora (saltmarsh species). The strength of the non-additive effect was unrelated to the initial trait dissimilarity of litters. Instead, the decomposition rate and mass remaining of litter mixtures were strongly related to the carbon concentrations in litter mixtures. Nutrient content in waters was dependent on the decomposition rate of litter mixtures but not on the initial nutrient concentrations in litters. Despite the behind mechanisms were not yet revealed by the current study, our findings have improved the understanding of the litter decomposition of coastal species and the consequent nutrient release. [ABSTRACT FROM AUTHOR]