Fig. 4: A conceptual framework illustrating temporal changes in soil organic carbon fractions across various land types globally, influenced by climate change and human activities over decadal timescales.
From: Unprotected carbon dominates decadal soil carbon increase
Temporal variations in soil organic carbon (SOC) fractions and the particulate organic carbon to mineral-associated organic carbon (POC/MAOC) ratio differed significantly across land types, with management practices and the intensity of human activities playing key roles. Compared to undisturbed natural ecosystems, POC declines to varying degrees in planted forests, grazed grasslands, and croplands under management practices such as heavy grazing and conventional tillage. White arrows indicate an increase (upward) or decrease (downward) in the POC/MAOC ratio from 2000 to 2022, while white circles represent no significant change in the ratio (P > 0.05).
