Litter percolate nitrogen promotes saprophytic and mycorrhizal fungi to contribute more soil carbon in mixed Masson pine plantations.

The carbon contribution of soil fungi in mixed forests is considerably influenced by variations in litter nutrients, but the comprehension of this impact is fraught with discrepancies and ambiguities. Furthermore, litter percolate, a vital way in which litter nutrients impact soil, has gotten less attention. These considerably limit our understanding of fungi's roles in carbon storage in mixed forests. In this study, ingrowth cores were buried, and litter percolate collection buckets were placed in pure and mixed plantations. To determine how introducing tree species changed litter percolate and how litter percolate affected the carbon accumulation in various types of fungi, we measured and examined soil and litter percolate samples. The results showed that in the mixed Masson pine plantation mixed with Cercidiphyllum japonicum Sieb. et Zucc (PM + CJ), litter percolate nitrogen was 0.99 mg/L higher than in the pure Masson pine plantation (PM). In the mixed Masson pine plantation mixed with Manglietia chingii Dandy (PM + MC), litter percolate nitrogen was 1.78 mg/L higher than that in PM. Saprophytic and mycorrhizal fungi contributed substantially more soil organic carbon (SOC) in mixed plantations than in PM. In addition, both mycorrhizal and saprophytic fungi increased the soil carbon pool management index (CPMI) of mixed plantations. Litter percolate ammonium nitrogen contributed 40.76 % to the increase of SOC by mycorrhizal fungi, and together with litter percolate nitrogen contributed 40.13 % to the increase of SOC by saprophytic fungi. Mycorrhizal fungi's carbon contribution is influenced by both litter percolate and soil nitrogen content. It is recommended that the selection of mixed tree species that can increase nitrogen levels in litter percolate and soil be prioritized in order to enhance the accumulation and stability of SOC in Masson pine plantations.