Organic carbon release from litter decomposition of woody and herbaceous plants in the Dongting Lake wetlands: A comparative study

Plant litter decomposition is a major source of soil organic carbon (OC); however, the quantitative differences in litter decomposition and carbon (C) release between herbaceous and woody plants are not well understood. In this study, we investigated the litter decomposition processes of the leaves of Carex brevicuspis (herbaceous plant) and the leaves and branches of Salix triandroides (woody plant) at soil depths of 0 and 5 cm from March–November in Dongting Lake. The litter of C. brevicuspis had a lower C concentration and C to nitrogen (N) ratio compared to that of S. triandroides. The decomposition and C release rates were higher in the litter of C. brevicuspis than those in the litter of S. triandroides. The higher release rate of OC from the decomposition of the litter of C. brevicuspis compared to that of S. triandroides contributed to the higher soil concentration of OC in the C. brevicuspis community compared to that of S. triandroides. Litter decomposition and release rates of OC changed over time and were higher during the non-flood period than during the flood period. Additionally, the rate of OC release from litter decomposition in the two investigated plants was correlated with the richness of Firmicutes, Bacteroidetes, Cyanobacteria, and Verrucomicrobia. Our results reveal that the differences in OC released during the decomposition of herbaceous and woody litters are related to the litter properties, nutrient concentrations in soil, flood period, and specific bacterial communities. This study reveals that the herbaceous plant C. brevicuspis has a stronger ability to improve soil OC than the woody plant S. triandroides.