Soil Organic Carbon Across Forest–Agriculture–Oil Palm Land-Use Trajectories in Ucayali, Peru

Abanto-Rodríguez C.; Blas J.C.G.; Torres D.D.C.; Ramírez-Flores N.; Soria D.G.G.; Nieto J.A.B.; Panduro-Tenazoa N.M.; Neto J.L.L.M.; Murga-Orrillo H.; Cano D.; Guerra-Blas D.P. · International Journal of Forestry Research (2026) · DOI: 10.1155/ijfr/1628905

Resumen

Deforestation and agricultural expansion in the Peruvian Amazon are reshaping soil functioning and carbon storage, yet the factors influencing soil organic carbon (SOC) remain poorly understood. This study assessed SOC variability across contrasting land-use systems in Ucayali, Peru, including old-growth forest remnants and secondary forests, cocoa agroforestry, Brachiaria pastures, and oil palm plantations of different ages—by integrating 54 composite topsoil sampling units, aggregated into 37 spatially independent analytical locations (0–15 cm, in 2024) with Sentinel-2 spectral variables and land-use history derived from MapBiomas Peru (1985–2024). SOC stocks varied across sites but did not differ significantly among present-day land-use classes, indicating that current land cover alone can be a poor predictor of SOC in this highly heterogeneous Amazonian landscape. In contrast, SOC exhibited negative but nonsignificant associations with land-use history variables: more recent forest conversions retained higher SOC, and lower SOC values tended to occur along land-use intensification pathways. Exploratory analyses of Sentinel-2 variables revealed statistically significant but moderate associations with SOC. However, strong collinearity among predictors and relatively low correlation strength suggest that spectral variables capture broad environmental gradients rather than independent drivers of SOC variability. Although exploratory, these patterns are broadly consistent with the concept of soil carbon debt; however, further studies are needed to understand the underlying mechanisms. Integrating field observations with long-term land-use trajectories provides a more robust methodology for assessing soil degradation in rapidly transforming tropical landscapes. Copyright

Instituciones: Universidad de Huánuco; Universidad Nacional Autónoma de Alto Amazonas; Universidad Nacional Intercultural de la Amazonia