Kan pramoen kha thang setthakit khong sapphayakon pamai nai phun thi khong sathani wichai singwaetlom Sakaerat, Amphoe Pak Thong Chai, Changwat Nakhon Ratchasima.

Economic assessment of forest resources was conducted in the Sakaerat Environmental Research Station (SERS) which is located in Amphoe Pak Thong Chai, Changwat Nakon Ratchasima, in the Northeastern region of Thailand. The period of this investigation was from 1978 to 1979. The designated objective of this project were: a) to assess the economic values of the productivities of the native dry -evergreen forest (DEF) and the dry - dipterocarp forest (DDF) and compare these to the productivities of the two agricultural lands (formerly, the DEF and the DDF) which are adjacent to the SERS, and b) to evaluate the succession and natural evolution of vegetation in the agricultural lands which are still in man - activity and in abandoned fields of different ages after the last cropping. The results show that total biomass production of all tree species is 394.05 tons/hectare, of which 261.23 tons is stem biomass, 124.58 tons branch biomass and 8.24 tons leaf biomass. Hopea ferrea Pierre is the highest biomass contributor per hectare which has 312.21 t/ha of total biomass. The total annual biomass increment of all tree species is 7.7401 t/ha, of which 4.9497 tons is contributed by stem, 2.6637 tons by branch and 0.1267 ton by leaves. H. ferrea is still the highest biomass contributor per hectare which was 6.8153 t/ha of total annual biomass increment. The results from the computation show that total biomass production of all tree species is 183.61 t/ha, of which 130.40 tons is stem biomass, 48.35 tons branch biomass and 4.86 tons leaf biomass. Shorea talura Roxb. is the highest biomass contributor per hectare which has 70.97 t/ha of total biomass. The total annual biomass increment of all tree species is 2.21 t/ha of which 1.51 tons is contributed by stem, 0.66 ton by branch and 0.04 ton by leaves. Pentacme suavis A.DC. and S. talura are the high biomass contributors per hectare which have 1.34 and 9.84 t/ha, respectively. Cited after Drew et al. (1978), in a series of abandoned fields from 1 to 20 + years which were in the dry -evergreen forest, the above ground biomass varies with the age of fields. In 20 + year plot, it is found a few valuable timber species which is the member of the mature dry - evergreen forest. This indicates the biological loss which is considered to be important one. Natural succession of the abandoned fields to attain a comparable stage of development found in the dry evergreen forest, requires a very long period of time.