Abstract
Contemporary land-use change during the past century in Northeast Thailand was analyzed at four socio-ecological scales: region, community, landscape and field plot. The main objectives were to elucidate factors influencing the change and identify effects of the change on the present land conditions. At all scales the land was transformed from forest to cultivated fields by pioneering farmers but such land transformation did not lead to rapid forest loss in the earlier subsistence economy period. Rapid forest loss only occurred after the economy became more commercialized with the expansion of cash crop cultivation in the early 1950s. Land transformation began in the lowland (prime areas for paddy fields) and expanded upward to the uplands. Population growth was the major factor for land-use change in the earlier stage while subsequently the growing commercialization of agriculture was the main factor. Changes in land use have resulted in degradation of land in the upland fields but not in the paddy fields. The upland fields have higher soil erosion and lower soil organic matter pools than the natural forest. The paddy fields, however, do not show indications of being degraded, probably because of their inherent soil properties and their location in the low-lying areas where they receive continuing in-flows of nutrients eroded from higher parts of the landscape. A number of measures to counter the land degradation are suggested including adopting of a more polycultural form of agriculture by integrating trees into agroecosystems at all scales. Such polycultural systems mimic the natural forest ecosystem which is more sustainable ecologically than monocultural systems. In addition, farmers in the Northeast should readopt some degree of subsistence-orientation which would increase the economic and social sustainability of Northeastern agriculture.
