SOIL ATTRIBUTES AND ITS RELATION TO SOIL ORGANIC MATTER IN ATLANTIC FOREST REMNANTS UNDER DIFFERENT SUCCESSIONAL TRAJECTORIES

Soils under tropical forests represent an important carbon sink, primarily through the accumulation of organic matter. Soil organic matter (SOM) plays a crucial role in several soil functions, including cation exchange capacity, soil structure stabilization, and the provision of resources for soil microbiota. In Brazil, Seasonal Semideciduous Forests are among the most threatened ecosystems within the Atlantic Forest biome due to deforestation and fragmentation. Therefore, soil monitoring is essential for understanding carbon storage patterns and for supporting ecosystem services. In this study, we evaluated physicochemical soil attributes and enzyme activities in samples collected from Seasonal Semideciduous Forests across three successional trajectories: (a) Old-growth forests, with no recorded disturbances for at least the last century; (b) Logged forests, subjected to selective timber extraction until the 1970s; and (c) Secondary forests, resulting from natural succession following pasture abandonment in the 1980s. Principal Factor Analysis identified two main groups of variables. The first group was strongly associated with soil pH, Ca, Mg, and K contents, as well as arylsulfatase activity. The second group was strongly linked to SOM, clay content, nitrogen, phosphorus, sulfur, and micronutrients, which were also reflected in β-glucosidase activity. Correlation analysis showed that soil carbon storage was strongly associated with clay content, highlighting the influence of soil texture on carbon stabilization in tropical forest soils.