At the moderate selection stand, the surface soil is protected from water erosion by crowns of trees above and fallen leaves, hence, it contains many relatively greater soil aggregates (3mm<) rich in finer particles.
At the over cut stand in selection method and the clear cut stand, the surface soil is exposed to water erosion, and such aggregates as mentioned above bacome smaller (3~0.25mm) by the decomposition or lost of fine particles. These smaller aggregates seem rather stable.