2. STUDY AREA
The study area is in the Northeast of Thailand, covers an area of about 170,000
sq.km. and lies between the latitudes of 14° to 18° N and the longitudes of 101° E
to 106° E. The most extensive areas are restricted to paddy fields, crop fields, a
small portion is forested. The topography is characterized by small hills and gentle
undulating terrain with sparse vegetation cover. The remaining forests are isolated
patches of remnant forest. The area is underlain by a thick sequence of Mesozoic
rock, mainly Maha Sarakam Formations which consist of sandstone, siltstone and
interbedded rock salts. The soils are inherently low in fertility and have sandy
textures. The study area is shown in figure 1.