Tin mining has been carried out in Thailand for more than five hundred years. The lands abandoned after mining account for a total area of over 70,000 ha, mostly in the South. The study sites of this investigation were located in the Takuapa district of Phangnga province. The original vegetation type consisted of tropical rainforest with an annual rainfall of 3,615mm and 200 rainy days a year. The soil texture was characterized by sandy loam with a pH of 4.7 and 1.52% soil organic matter. Such biophysical characteristics as vegetation, soil, and water associated with the duration of the period after mining were analyzed.
The results showed that plant succession, soil properties, and water quality varied with the years after the land had been abandoned. There were 55 families of 99 species which naturally regenerated on the 1-20 years old mine-spoiled lands originally occupied by moist evergreen forest. Grasses were found to be pioneer species followed by shrubs and trees.
Maximum above-ground biomass was recorded in the 20-year-old site (38 ton/ha), while such production was too low to be traced in the first year plot. Both the physical and chemical soil properties were affected by mining, especially the availability of macronutrients due to the sandy soil texture together with the low pH and CEC values. Heavy metal concentration in the water collected from mining ponds with different age classes was also affected·by mining, and it tended to decrease with the increase of the age of the mining-ponds. With the exception of Cd and Pb, the concentrations of Cu, Hg, and Zn did not exceed the drinking-water standards set by the MOPH and WHO. However, the consumption of water collected from mining ponds younger than three years old should be avoided. Information gained from these findings is useful for mine land reclamation and utilization, especially from the reforestation point of view.