Abstract:
The objectives of this study were to examine carbon stocks in soil of mixed deciduous
forest and teak plantation of 6, 15 and 24 years of age, as well as determining, the relationship
between soil organic carbon and the properties of soil, namely, bulk density, available water
content in various depths and finally, to examine the spatial distribution and variability of soil
organic carbon in teak plantations of 6, 15 and 24 years of age. Pearson correlation and Multiple
regression were used for the statistical analysis. Geographic Information System (GIS) ARCVIEW
was also used to prepare soil organic carbon map. The study was conducted in 2 areas; mixed
deciduous forest at Huay Kha Khaeng Wildlife Sanctuary, teak plantation of Thai Plywood Co.,
Ltd. in Lansak District, Uthaithani Province. The soil samples were collected in September 2003.
Results revealed that soil organic carbon from all sites decreased generally with the
increasing depth. From the surface soil down to the level of 100 cm. The highest carbon stocks in
soil were recorded at the 6-year-old teak plantation, followed by the 24 and 15-year-old teak
plantations and mixed deciduous forest 157.03, 105.67, 78.78 and 70.96 tC/ha respectively.
As for the relationship between soil organic carbon and properties of soil, the results
showed that soil organic carbon in mixed deciduous forests and teak plantations at any given age
were significantly higher where bulk density and depth were decreased, and the available water
content was also higher. The results from the spatial distribution and variability of soil organic
carbon in teak plantation of 6, 15 and 24 years of age, indicated that these were significantly
different from one another. The 6-year-old teak plantation had more spatial distribution of soil
organic carbon than the 24 and the 15-year-old teak plantation. Soil variability in 6,15 and 24 -
year-old teak plantations were 0.59, 0.67 and 0.56, respectively. The dissimilarity of spatial
distribution of soil organic carbon may be due to forest fire, forest management and topography