Plant Species Diversity and Carbon Stocks in Dry Dipterocarp Forest with and without Fire at Intakin Silvicultural Research Station, Chiang Mai Province

Abstract

            The objectives of this study were to assess plant species diversity and carbon biomass stocks in ecosystems of dry dipterocarp forest (DDF) with annual fire and without fire for at least 10 years at Intakin Silvicultural Research Station, Chiang Mai province. Plant communities were assessed using frequency, density, dominance and important value index and species diversity index was measured using the Shannon-Wiener function (Krebs, 1985).  Aboveground biomass was analyzed using Ogino et al. (1967), biomass of roots using Ogawa et al. (1965), and carbon stocks using Tsutsumi et al. (1983). In total, 42 tree species in 36 genera and 22 families were observed in DDF with annual fire. The most dominant tree species was Dipterocarpus tuberculatus, followed by Shorea obtusa, Gluta usitata, D. obtusifolius, Aporusa villosa and Canarium subulatum, respectively.  The Shannon-Wiener index of species diversity in DDF with annual fire was 3.24. In DDF without fire, 46 species (38 genera and 25 families) were recorded. D. tuberculatus had the highest importance, followed by S. obtusa, G. usitata, A. villosa and C. subulatum, respectively. The Shannon-Wiener index of species diversity was 3.20. The total biomass of  DDF with annual fire was 106.6 Mg ha^-1, separated into stem, branch, leaf and root biomass of 68.6, 22.9, 1.9 and 13.1 Mg ha^-1, respectively. The total carbon biomass was 52.6 Mg ha^-1 composed of stem, branch, leaf and root biomass of 34.3, 11.1, 0.9 and 6.3 Mg ha^-1, respectively.  The total biomass in DDF without fire was 128.3 Mg ha^-1, composed of stem, branch, leaf, and root biomass of 82.1, 29.3, 2.0 and 15.0 Mg ha^-1, respectively. The total carbon biomass was 63.4 Mg ha^-1 which accumulated in the stem, branch, leaf, and root biomass at 41.0, 14.2, 1.0 and 7.2 Mg ha^-1, respectively.  Plant growth was interrupted by forest fire, so more big trees (girth > 100 cm) were found in DDF without fire than in DDF with annual fire.  As a result, biomass and carbon storage in DDF without fire were higher than in DDF with annual fire. Thus, forest fire control could be a tool to increase carbon stocks in DDF.

Keywords:  dry dipterocarp forest, forest fire, plant species diversity, carbon stocks