Journal Article
Beyond bulk: Density fractions explain heterogeneity in global soil carbon abundance and persistence
Katherine Heckman; Caitlin E. Hicks Pries; Corey R. Lawrence; Craig Rasmussen; Susan E. Crow; Alison M. Hoyt; Sophie F. von Fromm; Zheng Shi; Shane Stoner; Casey McGrath; Jeffrey Beem‐Miller; Asmeret Asefaw Berhe; Joseph C. Blankinship; Marco Keiluweit; Erika Marín‐Spiotta; J. Grey Monroe; Alain F. Plante; Joshua Schimel; Carlos A. Sierra; Aaron Thompson; Rota Wagai
Global Change Biology · Vol. 28, Issue 3 · pp. 1178-1196 · 2022
Abstract
Understanding the controls on the amount and persistence of soil organic carbon (C) is essential for predicting its sensitivity to global change. The response may depend on whether C is unprotected, isolated within aggregates, or protected from decomposition by mineral associations. Here, we present a global synthesis of the relative influence of environmental factors on soil organic C partitioning among pools, abundance in each pool (mg C g −1 soil), and persistence (as approximated by radiocarbon abundance) in relatively unprotected particulate and protected mineral‐bound pools. We show that C within particulate and mineral‐associated pools consistently differed from one another in degree of persistence and relationship to environmental factors. Soil depth was the best predictor of C abundance and persistence, though it accounted for more variance in persistence. Persistence of all C pools decreased with increasing mean annual temperature (MAT) throughout the soil profile, whereas persistence increased with increasing wetness index (MAP/PET) in subsurface soils (30–176 cm). The relationship of C abundance (mg C g −1 soil) to climate varied among pools and with depth. Mineral‐associated C in surface soils (