CONCLUTION
The forest soil in the northern part of Thailand, with the organic content of 1.33
percent, achieved the hydrogen buffering capacity at 1 meq/lOOgmsoil with out pH
change. As the soil contained high aluminum and iron, the experiment illustrated that
a1ulllinu.m was leached to the acid rain leachate although there was no significant change
of pH in the soil. Simulated acid rain caused the reduction of bacteria actiuornyces and
aml~lotlifyitlgb acteria in-the upy er part of the soil. These could lead,t o low nutrient cycliig
rate in the ecosystem as these microorganism play the siguificant role on decomposition.
Although forest can served as the buffering source of acid depositioil within certain limit,
sollle cheinical and biological change could occur before the tllresllold vl~cll i~lflrle~lce
directly and indirectly to the soil ecosystem.
REFERENCES
1. World Bank and National Energy Policy Office . Thailand Coal Development aud
Utilization Study. A Joint Report 1989.
2. P. Wibulawas and S. Towprayoon "Sulhr dioxide Emission fiom Po~ver Station and
Oil Refineries iu Thailand" in Proceeding of the 1993 hternational Collferences on
Regional Emission and Climate Change in East Asia; Taipei, Taiwau ROC 1993
3. P. Kritiporn, " Acid Raiu Control Strategies for Thailand" in the Proceeding; of the 1990
Secolld Aunual Workshop on Acid Rain and Emission in Asia. Bangkok Thailand 1990 pp
193-214
4. A.L. Page Method of Soil Aualvsis Part 2, 2nd ed., Madison, America11 Society of
Agronomy, pp. 781- 1079.
5. A. Lett1 " Xufluence of Industrial Sulfbr dioxide hmission on Microorganisms of
Forest Soils" Ekoloaia-Cssr, Vol9 No3, pp 3 15-330