Litter quality-dependent dynamics of bacteria communities in litter and soil layers during litter decomposition

While many studies have investigated the influence of litter quality on microbial communities in litter or soil layer, the response of microbial communities to litter quality with decomposition time in both layers remains unclear. Our specific objectives were to explore how litter quality over decomposition time affects bacterial communities in both litter and soil layers.

A 673-day in-situ decomposition experiment was conducted using freshly fallen leaves from six species, categorized into low- and high-quality litters according to decomposition rates. Litter and soil bacterial communities were investigated after 136, 232, 309, 536, and 673 days.

Litter quality predictors included water-soluble carbohydrates (WSC), N and lignin, but not P. Litter quality significantly affected bacterial diversity in soil at later stage, but not in litter. Litter quality altered bacterial community composition in litter throughout decomposition period and in soil at later stage. At the phylum level, litter quality affected the relative abundance of Actinobacteria in litter and Actinobacteria, Proteobacteria, Acidobacteriota and Chloroflexi in soil. At the genus level, litter quality induced significant variation in relative abundance of both enriched and depleted genera and number of these genera increased over decomposition time in litter, and high-quality litters had a greater number of both enriched and depleted genera than low-quality litters in soil.

Litter and soil bacterial communities respond differently to litter quality with decomposition time. It is essential to integrally consider both litter and soil layers for a comprehensive understanding of microbial dynamics in litter decomposition.