Carbon Stocks in Deciduous Forest with Different Burning Frequencies at Huai Kha Khaeng Wildlife Sanctuary, Uthai Thani Province

Abstract

A study on carbon stock in deciduous forest with different burning frequencies. aims at determining plant species composition and structure and estimating the aboveground biomass and carbon stock in each plot. Plant species composition and structure (trees and saplings) were investigated in five 90 x 90 m plots of different burning frequencies: annual burning (M2), 1-year fire free interval (M5), 2-year fire free interval (M9), 4-year free interval (M1), and control unburned (M10) The main plot was divided into 81 subplot (10 x 10 m) for tree measurement and other 81 subplot (4 x 4 m) were established within 10 x 10 m subplot for sapling  measurement. Vegetations were identified and the measurement of their diameter at breast height (DBH) and height were undertaken. Importance value index (IVI) was analyzed to describe and compare species composition and community. Aboveground biomass of both trees and saplings were estimated using allometric equations and then convert to the carbon stock.

The results showed that there were 74 tree species found from all five plots. Schleichera oleosa (Lour.) Oken was the most dominant tree species in all plot examined except in the 2-year fire free interval plot where Shorea obtusa Wall. ex Blume; a deciduous dipterocarp species, had the greatest IVI. However, all of the top five IVI tree species are commonly found in mixed deciduous forest i.e. Xylia xylocarpa (Roxb.) Taub. var kerrii (Craib & Hutch.) I.C.Nielsen, Lannea coromandelica (Houtt.) Merr., and Croton roxburghii N.P. Balakr. There were 61 sapling species of which the top five IVI were C. roxburghii N.P. Balakr. Sterculia guttata Roxb. Grewia eriocapa Juss. Bauhinia sp.and Lagerstroemia ovalifolia Teijsm. & Binn., respectively. Aboveground tree biomass and aboveground carbon stock in 4-year free interval were significantly highest among all plot (191.431 and 91.887 ton/ha respectively) (p-value<0.05), probably because of the highest mean DBH and height. Expectedly, the greatest aboveground sapling biomass and carbon storage was found in control unburned plot (1.687 and 0.810 tonne/ha respectively) (p-value<0.05) despite less sapling density. This could probably be due to the largest DBH and height of these saplings. The findings suggest that the lesser the fire frequency the greater aboveground biomass and carbon stock observed in sapling, This may attribute to the growth and development of saplings after burning. However, a study on the biomass and carbon stock change is, therefore, recommended to underline the influence of fire frequency to biomass and carbon stock in this forest.

Keywords: fire frequencies, plant community, biomass, carbon stock, deciduous forest