Litter Decomposition Stage Exerted a Stronger Influence on Soil Organic Carbon Fractions Than Forest Litter Type

Abstract

Litter decomposition is a fundamental driver of carbon sequestration in forest ecosystems, influenced by tree species composition and associated litter quality. However, how different forest litter types affect decomposition dynamics, soil biochemistry, and organic carbon (SOC) sequestration remains unclear. We conducted a 210‐days in situ litterbag experiment comparing leaf litter from Pinus tabulaeformis (PTF), Quercus acutissima (QAF), and a mixed forest (MF) of both species. Our results demonstrate that PTF litter had the slowest decomposition rate, retaining the highest remaining ratios of carbon, phosphorus, cellulose, and lignin, followed by MF and QAF. In contrast, soil nitrogen, phosphorus, and ammonium levels showed minimal variation among forest types, with only minor shifts in microbial community structure. Notably, QAF litter promoted the highest particulate organic carbon (POC) content and POC/SOC ratio, whereas MF litter enhanced mineral‐associated organic carbon (MAOC) accumulation. Decomposition stage was the primary driver of SOC and POC dynamics, while MAOC was more strongly influenced by litter type. These findings indicate that mixed forests may enhance SOC sequestration compared to pure stands, though long‐term stability requires further investigation.