Differences in vegetation types over a landscape can influence the structural behaviour and organic carbon storage of soils thereby determining site specific management decisions for soils.This study aimed at establishing the differences in structural indices and organic carbon distribution across soils under secondary rainforest vegetation cover. Nine replicates of auger and core soil samples were collected from the site in a simple random sampling method at 0 – 20cm depth, and each sampling point was georeferenced. Soil samples were prepared and analysed at the Soil science laboratory of the National Root Crops Research institute, Umudike. Data obtained were subjected to geospatial analysis using a Geographical Information System (GIS) software package. Results showed that there were changes in soil structural properties and organic carbon storage across the studied area. Changes in organic carbon storage ranged from 40 – 48 ton / ha, BD ranged from 1.39 – 1.42 mg / m 3 , clay flocculation index ranged from 50 –68 %, aggregated silt + clay ranged from 9 – 12 %, clay dispersion index ranged from 32 – 42 %, dispersion ratio ranged from 26 – 32 % and mean weight diameter ranged from 0.75 – 1.05 mm. regions of increased soil micro aggregate dispersion dominated the land while there was increased dominance of regions with greater stability of soil macro aggregates. Also, regions with greater soil bulk density dominated the land while regions of greater soil organic carbon storage occupied about half portion of the land. Consequently, management of the soil for improved productivity and soil quality requires that conservation tillage be practiced in regions with weak aggregates stability while organic matter input be increased at regions with least organic carbon storage through application of organic manure or increased plant density for biomass return to the soil..

Keywords: Tropical rainforest, Bulk density, Aggregate stability, Organic carbon