Abstract Soil organic carbon (SOC) storage represents one of the most critical ecosystem services provided by soils, yet scientific assessments frequently focus on surface layers, overlooking deeper horizons. In this study, we investigated SOC stocks and spatial patterns of soil δ 13 C across three contrasting land use and land cover (LULC) types in southeastern Brazil: a deforested area (DA), a densely wooded savanna (DWS), and a semideciduous seasonal forest (SSF). Soil samples were collected at five depths along a 1‐m profile across 30 sampling sites. Carbon, nitrogen, and their isotopes ( 13 C and 15 N) were determined using an elemental analyzer, and bulk density was estimated via a pedotransfer function. Restricting SOC evaluation to standard metrics (0–30 cm) captured approximately one‐third of the carbon stored within the first meter, while 62%–67% of SOC occurred below 20 cm across all LULC types. Bulk density uncertainty introduced a variation of ±0.4–2.1 Mg C ha −1 . No significant differences in SOC stocks were observed between DA and DWS at intermediate depths; however, DA stocks remained substantially lower than SSF across the full profile, and the dominance of exotic Urochloa decumbens precludes interpretation of these similarities as ecosystem recovery. Soil δ 13 C signatures indicated depth‐dependent isotopic shifts consistent with C 4 vegetation legacy effects, though microbial fractionation represents a competing mechanism that cannot be fully excluded. These findings demonstrate that integrating deep soil sampling with isotopic and spatial analyses provides a robust framework for identifying LULC legacies and improving SOC assessments in tropical landscapes.
Alexandre et al. (Mon,) studied this question.