Soil warming effect on the heterotrophic respiration rate during a decadal experiment in a cool-temperate forested peatland

冷温帯泥炭林における土壌温暖化の微生物呼吸への影響

高木 健太郎*; Liang, N.*; Aguilos, M.*; Rythi, K.*; 寺本 宗正*; 小林 真*; Sun, L.*; 近藤 俊明*; 小嵐 淳   ; 安藤 麻里子  

Takagi, Kentaro*; Liang, N.*; Aguilos, M.*; Rythi, K.*; Teramoto, Munemasa*; Kobayashi, Makoto*; Sun, L.*; Kondo, Toshiaki*; Koarashi, Jun; Atarashi-Andoh, Mariko

We conducted a soil warming experiment in a cool-temperate forested peatland in northern Japan during snow-free seasons of 2007-2017, to determine the soil warming effect on the heterotrophic respiration rate. Soil CO efflux was measured with a 15-channel automated chamber system, which was divided into three groups each with five replications for the control (unwarmed-not trenched), unwarmed-trenched, and warmed-trenched treatments. Soil warming increased the heterotrophic respiration rate having a increasing trend in the annual mean enhancement ratio. These annul mean enhancement ratio was linearly correlated with the current year's litterfall supply, which shows that the litterfall is quickly decomposed as the labile substrate for respiration and the amount becomes a limiting factor for the enhancement. The warming also sustained enhancement of the temperature sensitivity, Q, and the basal respiration at 10C, R, during the decadal experiment. Accordingly, warming enhanced not only the heterotrophic respiration rate itself but also its Q and R in forests with high substrate availability in the soil, without acclimation by continuous warming.