Historical dynamics of terrestrial carbon during 1901–2016 as simulated by the CLM-Microbe model

Abstract. The CLM-Microbe model was able to reproduce the variations of gross (GPP) and net (NPP) primary productivity, heterotrophic (HR), and soil (SR) respiration, microbial (MBC) biomass C in fungi (FBC) and bacteria (BBC) in the top 30 cm and 1 m, dissolved (DOC) and soil organic C (SOC) in the top 30 cm and 1 m during 2901–2016. During the study period, simulated C variables increased by approximately 30 PgC yr⁻¹ for GPP, 13 PgC yr⁻¹ for NPP, 12 PgC yr⁻¹ for HR, 25 PgC yr⁻¹ for SR, 1.0 PgC for FBC and 0.4 PgC for BBC in 0–30 cm, 1.2 PgC for FBC, 0.7 PgC for BBC, 2.4 PgC for DOC, 34 PgC for SOC, and 4 PgC for litter C in 0–1 m, and 37 PgC for vegetation C. Increases in C fluxes and pools were larger at northern high latitudes and in equatorial regions than at other latitudes; the largest absolute increases of C fluxes and pools were in Asia and South America, particularly in eastern Asia and central and northern South America. However, the largest relative increases of GPP, NPP, HR, and SR in Asia and Europe, FBC (0–30 cm and 0–1 m) in South America, BBC (0–30 cm and 0–1 m) in Europe, DOC (0–1 m) in South America and Europe, SOC (0–1 m) in Africa, and vegetation C and litter C (0–1 m) in Europe. Vegetation productivity was primarily controlled by warming and precipitation, while microbial and soil C was jointly governed by vegetation C input and soil temperature and moisture. This study enhances our understanding of soil microbial roles in the global terrestrial C cycle.