Refinement of a model for upscaling of soil respiration in Japan

Yamanuki, Hina*; Ichii, Kazuhito*; Yamamoto, Yuhei*; Kotsuki, Shunji*; Sun, L.*; Liang, N.*; Teramoto, Munemasa*; Nagano, Hirohiko*; Hirano, Takashi*; Takagi, Kentaro*; Ishida, Sachinobu*; Takagi, Masahiro*; Kondo, Toshiaki*; Koarashi, Jun   ; Atarashi-Andoh, Mariko  ; Takahashi, Yoshiyuki*

Soil respiration (SR) is one of the most essential components of soil carbon cycles. However, large uncertainties remain in its temporal and spatial variations. In this study, we refined our model to estimate SR across Japan with observation data (eight sites across Japan), remote sensing data (MODIS land products), and random forest regression. We newly added soil temperature and moisture by a process-based model, the Simple Biosphere model including Urban Canopy (SiBUC). Our estimation shows a reasonable performance with R=0.72 for the in-situ model and R=0.73 for remote sensing and in-situ combined model on average. Based on the established model, we produced upscaled estimations of SR across Japan with a spatial resolution of 4 km from 2000 to 2020.