Landuse changes at Surat Thani, Southern Thailand from 1973 to 1993
The results showed that the areas of existing forest and mangrove forest have been decreased by 1.30 and 4.68 percent respectively in 1973, to 0.89 and 2.54 percent respectively in 1984, and to 0.63 and 2.16 percent respectively in 1993. Over the same period, the agricultural land areas such as orchard, rubber and oil palm plantations were expanded from 32.38 percent in 1973 to 33.32 percent in 1984, but diminished to 30.53 percent in 1993, after the destruction of Typhoon Gay in November 1989. Paddy fields have been expanded from 20.90 percent in 1973 to 22.96 percent in 1984, and decreased after the same natural disaster, to 13.03 percent in 1993. Shrimp pond areas have been increased from 2.01 percent in 1984 to 5.98 percent in 1993. Also, urban areas have been expanded from 0.54 percent in 1973, to 0.64 percent in 1984, and to 1.77 percent in 1993. From the survey statistics of the data from the total area of Surat Thani Province, the areas of existing tropical forest from 1961 to 1991 have been diminished from 63.56 percent of the total land area, to 25.47 or 1.269 percent (158.42 square km) per year. The areas of mangrove forest from 1975 to 1992 have also decreased from 0.29 to 0.19 percent, or 0.0055 percent (0.67 square km) per year. The population of Surat Thani has increased by 425,103 per 31 years, or 13.713 per year. Areas for shrimp ponds have increased from 3,430 rai in 1975, to 59,256 rai in 1991 (1 rai=1,600 square m) or 3,283.88 rai per year, on average. Catches of freshwater animals have increased from 103.67 tons in 1975 to 18,747.65 tons in 1991, or 1,096.70 tons per year. Graphs of the area of existing forest and population in Surat Thani showed a high inverse correlation. This inverse relationship was also observed in the correlation of areas of mangrove forest with areas of shrimp ponds and freshwater animal catch. This means that deforestation and socio-economical problems are the main cause of landuse changes in Surat Thani.