Stability and vulnerability of organic carbon stored in Japanese forest soils

Koarashi, Jun   ; Atarashi-Andoh, Mariko  ; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro   

Accelerated release of carbon (C) previously stored in soils is considered one of the most important positive feedbacks from terrestrial ecosystems to the atmosphere in a future warmer world. We used 14C analysis following chemical fractionation to quantify the sizes and turnover times of C pools of Japanese forest soils. The C-based approach revealed higher variations of the family of MRTs soil by soil. The size of C pools that cycle slowly on timescales of 100-1000 years strongly correlated with the content of pyrophosphate-extractable Al. In contrast, faster-cycling C pools that turn over within decades showed a negative correlation with mean annual temperature at the sites. Our results suggest that C dynamics in the isolated SOC pools may be regulated by different mechanisms: temperature control on decadal cycling C versus mineralogy control on slower-cycling C, and clearly demonstrate that the forest soils will respond very differently to climate change over the next century.