Impacts of Forest Fire on Soil Physico-chemical Properties and Nutrient Storages in Dry Dipterocarp Forest, In Takin. Silvicultural Research Station, Chiang Mai Province

Abstract

Impacts of forest fire on changes of soil physico-chemical properties and nutrient storages in dry dipterocarp forest (DDF) were studied at In Takin Silvicultural Research Station, Chiang Mai Province by comparing two sites, DDF with and without fire for at least 10 years. Soil study was taken in the two sites by making two soil pits (150 cm. width x 200 cm. depth) in each site. Soil samples were collected along the profiles, and later analyzed for physical and chemical properties. It is found that surface soil in DDF with fire had loamy sand whereas non-fire site was sandy loam. Other soil parameters in the surface soils of DDF with and without fire had some differences; bulk density: 1.26, 1.11 Mg m^-3, pH: 5.1, 5.5 (strongly acid), contents of organic matter: 25.0, 32.1 g kg^-1, carbon: 14.5, 18.6 g kg^-1, nitrogen: 0.8, 1.2 g kg^-1, available P: 13.6, 34.9 mg kg^-1, extractable K: 282.8, 359.8 mg kg^-1, Ca: 385.2, 621.9 mg kg^-1, Mg: 154.7, 271.5 mg kg^-1 and Na: 10.6, 18.9 mg kg^-1 ,respectively. Average amounts of organic matter, carbon and nitrogen within 200 cm depth soil of fire site were 124, 72 and 7.9 Mg ha^-1 , respectively while the higher amounts of 212, 123 and 8.0 Mg ha^-1were for non-fire site. Extractable P, K, Ca, Mg and Na amounts of fire site were in the order of 50; 6,421; 3,827; 2,902 and 493 kg ha^-1 while those of non-fire site were 156; 6,227; 4,287; 3,921 and 412 kg ha^-1, respectively.