Impact of litter quality on the stability and storage of soil carbon in flooded wetlands

Abstract

Context High inputs of plant litters and slow decomposition of soil organic carbon (SOC) influence the biogeochemical cycling of soil carbon in flooded wetlands. Aims To investigate the effects of different quality litter inputs on SOC stability and storage in flooded wetlands. Methods A 180-day microcosmic experiment to investigated the decomposition of litters of two dominant plants (Carex cinerascens Kukenth., CC; Cyperaceae family) and Triarrhena lutarioriparia L. Liu, TL; Poaceae family), in Poyang Lake Wetlands. Key results CC litters (high-quality, low lignin/N mass ratio) reduced gross content of SOC, but increased labile carbon and labile index (LI) of soils. In contrast, inputs of TL litters (low-quality, high lignin/N mass ratio) increased SOC gross content and recalcitrant carbon fractions of soils, but reduced soil labile carbons and LI. Significant effects of litters on SOC were not observed until ∼30 days indicating that the effects of litter inputs on soil carbon pools in flooded wetlands need time to be activated. CC and TL litters both increased the soil microbial biomass carbon (MBC) content. Soil MBC in CC treatments was significantly affected by the litter ash-free dry mass, while that in TL treatments was significantly affected by mass loss. Conclusions Litter quality may regulate the growth of soil MBC via different microbial growth strategies. Implications Our results suggest that inputs of high-quality litters can yield a high amount of labile carbon through stimulated microbial decomposition, leading to an overall loss of carbon. In contrast, inputs of low-quality litters can promote the microbial production of more recalcitrant carbons and increase soil carbon stability and carbon sequestration.