Dynamics of Fungal and Bacterial Biomass Carbon in Natural Ecosystems: Site?Level Applications of the CLM?Microbe Model

Author(s): He, L; Lipson, DA; Mazza Rodrigues, JL; Mayes, M; Bjork, RG; Glaser, B; Thornton, P; Xu, X | Abstract: Explicitly representing microbial processes has been recognized as a key improvement to Earth system models for the realistic projections of soil carbon (C) and climate dynamics. The CLM-Microbe model builds upon CLM4.5 explicitly represents two major groups, fungi bacteria. Based on compiled time-series data fungal (FBC) bacterial (BBC) biomass C from nine biomes, we parameterized validated model, further conducted sensitivity uncertainty analysis simulating cycling. performance was evaluated with mean absolute error (MAE), root square (RMSE), coefficient determination (R2) relative change in FBC BBC. is able reasonably capture seasonal dynamics BBC across particularly tropical/subtropical forest, temperate broadleaf grassland, MAE l0.49 l0.36 RMSE l0.52 l0.39 BBC, while R2 values are relatively smaller some biomes (e.g., shrub) due small sample sizes. We found good consistencies between simulated observed (R2n=n0.70, Pnln0.001) (R2n=n0.26, Pnln0.05) average but not fully large variation Sensitivity shows that most critical parameters turnover rate carbon-to-nitrogen ratio bacteria assimilation efficiency. This study confirms explicit representation mechanisms enhances variables such heterotrophic respiration organic density. application would deepen our understanding contributions global cycle.