Soil Color Indicators of Biogeochemical Changes Under Land Use Intensification in Tropical Climosequences

Abstract

Land use intensification is transforming the structure and function of tropical soils, with significant impacts on biogeochemical cycling, organic matter dynamics, and ecosystem productivity. Among the most visible consequences of such changes is the alteration of soil color—an integrative indicator of soil health that reflects key physical, chemical, and biological processes. This review explores the scientific nexus between land use intensification, soil color variability, and biogeochemical feedbacks across tropical climosequences. Drawing from recent empirical studies and long-term landscape assessments, it synthesizes how shifts from forest to agriculture, agroforestry, and urban systems influence soil color attributes such as hue, value, and chroma. These color changes are further contextualized with respect to alterations in soil organic carbon, iron oxide transformations, redoximorphic features, and nutrient cycling under variable climatic regimes—ranging from humid tropics to sub-humid and dry tropics. We critically compare field-based Munsell assessments, digital imaging, and spectral reflectance techniques used to quantify soil color and relate it to land use gradients. The review also discusses how color signatures can serve as proxy indicators for soil degradation, fertility loss, and hydrological imbalance, especially in low-resource settings. Finally, it outlines research priorities for improving the integration of soil color into land evaluation frameworks, digital soil mapping, and environmental policy across climatically diverse tropical zones. The paper emphasizes the utility of soil color as both a diagnostic and planning tool for sustainable land management under intensifying anthropogenic pressures.