1989 年 33 巻 1 号 p. 17-29
In the tropics, "waste lands" resulted from various man-made impacts have been expanding at a remarkable rate, with a further demand for economical development to sustain increasing population. Above all, forest destruction is a serious problem brought about by shifting cultivation, over-cutting for fuel wood, forest fire, over-grazing, mining, and so on. Thus, reforestation is an urgent demand. For the purpose of improving the biological productivity or these tropical waste lands in Thailand, four experimental sites were selected : 1). Takua Pa tin mining area, 2). Ratchaburi over-cutting area, 3). Somdet lowland shifting cultivation area, and 4). Huey Tung Jaw highland shifting cultivation area. Compared with the soils under original vegetation, it can be concluded or suggested that soils from the cultivated area had following specific problems such as; 1). lack of clayey materials for optimum water and nutrient retention, 2). physical hazard for root growth caused by the hardening of soft plinthite, 3). nutrient deficiency in the original materials and subsequent deprivation by intensive cultivation, and 4). dense coverage of weeds which suppressed the growth of planted trees.
