APPLICATION OF GIS IN ANALYSIS OF OFREST AREA CHANGES BEFORE AND AFTER LOGGING BAN : A CASE STUDY IN EASTERN THAILAND

Abstract

Analysis of forest area changes before and after logging ban in eastern Thailand using vectorbased GIS, Pc ARC / INFO, was divided into 3 periods: period I (1973 - 1982), Period II (1982 - 1989) and period III (1989 - 1991). It was found that the forest areas decreased at the average rates of 5.6, 1.8 and 2.8 % per annum during Period I, II and III respectively. These indicated clearly that the ban on logging operations in January 1989 did not decrease the rate of deforestation and did not stop the rural people from encroaching the forest lands. Moreover, the rate of deforestation increased in Period III. By consideration with physical factors of the study area, it was found that the locations of invasion were mainly on flat and low slope lands, not so far from roads. Consideration with other factors such as slope and transportation routes revealed that the forest area decreased during each period mainly occurred on 0 - 8 % slope areas. Locations and directions of the deforestation were related to transportation routes. Wherever the transportation routes passed, the forest areas were destroyed on a large scale.