Microbial survivability during repeated extreme dry-wet cycles determines CO emissions after rewetting of dried soils in humid temperate forests

Nakayama, Masataka*; Suzuki, Yuri; Abe, Yukiko; Taniguchi, Takeshi*; Atarashi-Andoh, Mariko  ; Koarashi, Jun   ; Nagano, Hirohiko*

Rewetting of dried soil provokes pulse carbon dioxide (CO) emissions from soils. In this study, we aimed to reveal the effects of repeated soil dry-wet cycle (DWC) on soil CO emissions, and the factors affecting emissions after rewetting in humid temperate forests. Experimentation included incubation of soils under five sequential DWCs. Rewetting of dried soil significantly increased CO emissions. Soil rewetting decreased soil microbial biomass carbon and increased extractable organic carbon (EOC), and the EOC concentration decreased during each subsequent wet period. Based on path analysis, MBC after rewetting was strongly and positively correlated with CO emissions in the following days. The results suggest that microbial survivability to soil DWCs, rather than sudden labile carbon supply, determines the response of pulse CO emissions from soils after rewetting during repeated soil DWCs.