Soil Characteristics under Various Types of Forest in Sakaerat Environmental Research Station

Abstract

A study on soil characteristics under different types of forest in Sakaerat Environmental Research Station Nakhon Ratchasima province was carried out on eight representative soils including an area of secondary mixed deciduous forest (Skr 1), two sites of dry dipterocarp forest (Skr-2, 3), an ecotone zone (Skr-4), three restoration dry evergreen forest (Skr-5, 6, 7) and an undisturbed dry evergreen forest (Skr-8). All soils located at upper part of middle footslope to upper part of lower footslope which were derived from colluvium over residuum of sandstone. Results revealed that soils under different forest covers are moderately shallow to very deep, which the one under dry dipterocarp forest (Skr-3) is the shallowest. Their texture ranges from sandy loam to clay loam except for a dry evergreen forest area (Skr-8) where the soil has finer texture than do the soils in other types of forest. Other properties of soils under different types of forest are quite similar especially in subsoils horizon. They are very strongly to slightly acid (pH 4.5-6.3). Organic matter contents range between moderately high to very low (3.44-32.16 g kg-1) and decreasing with depth, which correspond to the amount of total nitrogen (0.21-1.75 g kg-1). Available phosphorus content is very low with the value of 0.006-0.17 mg kg-1. Cation exchange capacity and extractable acidity values are low (4.5-16.3 and 1-23 cmolc kg-1, respectively) except for the topsoils in some areas. The soil under dry evergreen forest (Skr-7), which was undergone reforestation, has high base saturation percentage throughout the soil profile (48-81%).