Warming-induced enhancement of soil heterotrophic respiration is linearly increased by the current year's litterfall supply in a cool-temperate forested peatland

冷温帯森林泥炭土壌における土壌微生物呼吸の温暖化による増加は、年間リターフォール量に依存する

高木 健太郎*; Liang, N.*; Aguilos, M.*; 寺本 宗正*; 近藤 俊明*; 小嵐 淳   ; 安藤 麻里子  

Takagi, Kentaro*; Liang, N.*; Aguilos, M.*; Teramoto, Munemasa*; 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.