Comparison of individual tree aboveground biomass estimation in community forests using allometric equation and expansion factor in Magetan, East Java, Indonesia

Setiahadi R. 2021. Comparison of individual tree aboveground biomass estimation in community forests using allometric equation and expansion factor in Magetan, East Java, Indonesia. Biodiversitas 22: 3899-3909. The use of allometric equation and biomass expansion factor can facilitate more efficient tree biomass estimation. This study evaluates the accuracy of the allometric equation and expansion factor for quantifying the individual tree aboveground biomass in community forest tree species. Destructive sampling n on 120 trees from four different species: Falcataria moluccana, Melia azedarach, Swietenia macrophylla, and Tectona grandis. For each tree sample, aboveground biomass measured at every tree component, i.e., stem, branches, and leaves. The allometric equation developed using regression analysis with several predictor variables, such as diameter at breast height (D), squared diameter at breast height combined with tree height (D2H), and D and H separately. On another side, the biomass expansion factor was calculated based on the total aboveground biomass and stem biomass ratio. The results found the highest mean aboveground biomass for all species are M. azedarach (326.36±88.40 kg tree-1), S. macrophylla (244.47±98.73 kg tree-1), T. grandis (173.31±80.97 kg tree-1), and F. moluccana (56.56±23.10 kg tree-1). The most significant average biomass expansion factor observed in M. azedarach (1.78±0.03), adhered by T. grandis (1.66±0.09), S. macrophylla (1.61±0.04), and F. moluccana (1.59±0.06). The equation ln? = lna + b x ln (D) was best for estimating aboveground biomass in each tree component and a total of four species with an accuracy of more than 90%.

Contribution of some Savannah tree species in carbon sequestration

Improvements in above ground biomass estimation can help account for changes in carbon stock in forest areas that may potentially participate in the clean development mechanism. The main objective of this study was to assess potential of some selected forest variables for modeling carbon sequestration for Combretum hartmannianum, Terminalia brownii, and Lanea fruitcosa. A total of 10 sample trees for Lanea fruitcosa and 8 sample trees for each of the other two species were selected for biomass and carbon determination were selected from El Nour Natural Forest Reserve of the Blue Nile State, Sudan. Data of diameter at breast height, total tree height, tree crown diameter, crown height, and upper stem diameters were measured. Then sample trees were felled and sectioned to their components and weighed. Subsamples were selected from each component for oven drying at 105 ˚C. Finally, allometric models were developed and the aboveground dry weight (dwt) and carbon sequestered per hector were calculated. The results presented biomass equations, biomass expansion factor and wood density that developed for the trees. In case of inventoried wood volume, corrections for biomass expansion factor and wood density value were done, and new values are suggested for use to convert wood volume to biomass estimates. The results also, indicate that diameter at breast height, crown diameter and tree height are good predictors for estimation of tree dwt and carbon stock. The developed allometric equations in this study gave better estimation of dwt than default value. The average carbon stock was found to be 22.57 t/ha.

Assessment of Biomass Expansion Factor (BEF) and Root-to-shoot Ratio (R) for some Tree Species of Uttarakhand, India

The present study was conducted in Shorea robusta (sal), Pinus roxburghii (Chir pine), Tectona grandis (Teak) and Ailanthus excelsa (Ardu) plantations of different ages at different sites in Uttarakhand. Biomass was calculated on the basis of complete tree harvesting method (stratified mean tree technique method). Biomass Expansion Factor (BEF) and root-to-shoot ratio (R) of all these 4 tree species have been calculated and presented in this paper. Sample trees of S. robusta were of 45, 53 and 60 years of age. BEF for all these 3 age series were assessed as 1.3 at 45 years, 1.4 at 53 years and 1.2 at 60 years of age. Similarly, R values were assessed as 0.27, 0.28 and 0.26, respectively, in these 3 age series. BEF and R values assessed for T. grandis (28 years age) as 1.46 and 0.21; and for A. excelsa (39 years age) as 1.23 and 0.23, respectively. BEF for P. roxburghii trees calculated as 2.3 for 13 years age, 1.75 for 20 years, 1.71 for 22 years, 1.5 for 33 years and 1.46 for trees of 45 years of age. Similarly, R values were 0.2 for 13 years, 0.21 for 20 years, 0.12 for 22 years, 0.13 for 33 years and 0.15 for 45 years of age. P. roxburghii sample trees have shown decreasing order of BEF with increasing age, whereas S. robusta has not shown such trend along the chronosequence.