Dissolved organic carbon dynamics in a cool temperate forest soil; Clues from C and C signatures

Nakanishi, Takahiro   ; Koarashi, Jun   ; Atarashi-Andoh, Mariko  ; Hirai, Keizo*

Dissolved organic carbon (DOC) is an important constituent in forest soils, because it affects soil formation and transport of heavy metals, is a source of C for microbes, and contributes to soil organic carbon (SOC) accumulation. In this study, we measured C and C in water extractable organic carbon (WEOC) to investigate the dynamics of DOC at Appi, a cool temperate deciduous forest in Japan. The C values of WEOC were slightly higher than those of SOC. Such enrichment in C indicated that WEOC production, which was coupled with the microbial activity, mainly used a C-enriched SOC fraction (including sugars, amino acids, etc.) of the total SOC. Indeed, hydrophilic fractions were enriched in C compared to the total WEOC. Hydrophilic fractions are considered more biologically available for decomposition. The result of C indicated that WEOC consists mainly of C-enriched, labile, hydrophilic organic materials with faster turnover times (several decades).