Land Use Dynamics and Land Cover Structure Change in Thailand (As Exemplified by Mountainous Nan Province

Changes in the land use pattern and in the land cover structure for the time interval 1995-2012 in Thailand are considered by using, as an example, Nan Province located in the northern mountainous part of the country. Interpretation of satellite images and vector data that were provided by the Land Development Department (Thailand) revealed the main directions of change in the region's land use: deforestation, expansion of areas under crops, transition from slash and burn cultivation to permanent cultivation, and intensive utilization of agrochemicals. In spite of a decrease in the deforestation rate across Thailand in general, it is shown that for the period under review the proportion of natural forests in Nan Province decreased by nearly one half. On the other hand, the agricultural lands increased for the same period by more than 50%. The highest deforestation rates were recorded during 2009-2012. It was found that the changes in the land use pattern disturbed the existing centuries-old balance of man-natural environment interaction within the framework of the traditional system of slash and burn agriculture which is well adapted to local conditions. The study revealed the chief causes for such changes: an ineffective monitoring of forests; an unclear character of the boundaries separating lands of rural communities and protected territories, and possibilities for sales of commercial products (maize, cassava, etc.) cultivated in illegal fields. It is shown that rapid changes in land cover due to deforestation and plowing of mountainous areas for cultivation of commercial crops led to an intensification of slope processes (landslides and solifluction), an increase in overland runoff, and to an enhanced hazard of heavy floods during the monsoon season. To keep track of deforestation and deal with nature management conflicts requires a continuous monitoring of the land cover dynamics.