Divergent controls on carbon concentration and persistence between forests and grasslands of the conterminous US

• DOI: 10.1007/s10533-020-00725-z
• Publication Date: 2020-11-23T11:03:35Z
• Authors: K. A. Heckman; L. E. Nave; M. Bowman; A. Gallo; J. A. Hatten; L. M. Matosziuk; A. R. Possinger; M. SanClements; B. D. Strahm; T. L. Weiglein; C. Rasmussen; C. W. Swanston
• Keywords: Persistence (discontinuity); Soil carbon

Abstract Variation in soil organic C (%OC) concentration has been associated with the of reactive Fe- and Al-oxyhydroxide phases exchangeable Ca, relative importance these two stabilizing components shifting as pH moves from acid to alkaline. However, it is currently unknown if this pattern similar or different regard measures persistence. We sampled soils 3 horizons (uppermost A, uppermost B, lowest B horizons) across a gradient 11 grass-dominated 13 deciduous/mixed forest-dominated NEON sites examine similarities differences drivers concentrations all could be linked abundances Fe, Al but were not significantly variation Though was related Δ 14 OC, higher persistence more alkaline values. In forested soils, depth explained 75% OC ( p < 0.0001), no significant additional correlations extractable metal phases. grasslands, Ca concentrations, instead by inorganic (R 2 = 0.76, implying stabilization through association carbonate precipitation. substrate quality suggested greater also advanced degree decomposition. Results suggest that explanatory variables differ those persistence, may present high enough most offer any protective capacity. These results have implications for our understanding how model cycle previously unrecognized mechanisms carbonates forms Si.