Species Diversity, Aboveground Biomass, and Carbon Storage of Watershed Forest in Phayao Province, Thailand

Restoration of watershed forest ecosystems can perform different disturbance regimes over remnant forests, which can ultimately affect plant diversity, soil formation, and carbon storage. To address an issue, this study assessed tree species diversity, aboveground biomass (AGB), and aboveground carbon (AGC) storage of the watershed forest in Phayao Province, Thailand. Data collection was conducted in 18 plots along nine watersheds along the topographic gradients. Tree height and diameter at breast height (DBH) were collected. AGB of vegetation was estimated by using the allometric equation. Likewise, AGC storage was evaluated from half of AGB. A total of 133 species belonging to 105 genera and 39 families were recorded from the watershed forests (1.8 ha). Mixed deciduous forest (MDF) and dry evergreen forest (DEF) exhibited high density and high diversity index, respectively. The highest value of total AGC storage was found in the MDF with 91.2 ton C/ha, following by DEF (78.3 ton C/ha) and dry dipterocarp forest (DDF) (60.5 ton C/ha). Detrended correspondence analysis (DCA) revealed that the occurrences of Albizia saman, Hopea odorata, Lagerstroemia calyculata, and Acrocarpus fraxinifolius related to AGB, AGC, slope, and tree canopy in the DEF. Intensity of slope influenced tree species occurrence in the watershed forest of Phayao.