Effect of Fire on Vegetation in the Dry Deciduous Dipterocarp Forest at Huai Kha Khaeng Wildlife Sanctuary, Uthai Thani Province

Abstract

Effect of fire on vegetation in the dry deciduous dipterocarp forest at Huai Kha Khaeng Wildlife Sanctuary was observed from twelve plots of 30 m x 30 mm size locating by completely randomized design sampling. Three plots were monthly burned startly from January to April in 2003. The effect of fire on growth and mortality data of vegetation were determined before, immediately after and one, three, six, nine and twelve months after burning. The data were compared between pre-burn and post-burn and among the four months of burning. The results revealed that the fire had a little effect on growth and mortality of trees. On the other hand, it affected to both growth and mortality of saplings and seedlings. Mean of the height and diameter at breast height of saplings of immediately killing by fire were 4.20 m and 5.14 cm, respectively. While the seedlings with diameter at ground level less than 0.50 cm were over 50 percent killed. The tallest seedling was immediately killed after burning was 1.24 m, while the largest diameter at ground level was 2.55 cm. The mortality dramatically increased one month after burning and was then, it quite consistent in latter measurements. Most of the survival seedlings could recover through sprouting in the rainy season. Low fire intensity in this study benefited to those plant communities only in terms of height increment of saplings, but it adversely affected diameter growth at ground level and the density of seedlings. Although fire is the factor the dry deciduous dipterocarp forest, if severe fire or fire was occurred every year, the high mortality of seedlings and saplings could limit their development to big trees with no reproduction to replace the dead ones. As a result, the forest would be gradually decreased and eventually disappeared.

Keywords: Fire effect, Vegetation, Dry deciduous dipterocarp forest, Huai Kha Khaeng Wildlife Sanctuary