Allometric equation based on DBH for predicting tree and shrub stands biomass in the sudano-guinea savannahs of Ngaoundere, Cameroon

The sustainable management of savannahs for their contribution to the reduction of greenhouse effects inevitably requires knowledge of their carbon stock. Thus, a study on the establishment of multi-species allometric equations for estimating woody biomass from 3 standard physical variables used in forestry (DBH, wood height and density) was conducted in the Sudano-guinea savannahs of Ngaoundere Cameroon. A sample of one hundred and fifty (150) individuals belonging to 16 species was carried out in the savannahs and distributed over all the classes of diameter, ranged from 10 to 60 cm. The diameter at breast height of these individuals and their height were measured. After felling, the woody plant was divided into branches, stems, and leaves including the twigs, and their biomass was determined after drying and weighing. Different allometric equations between biomass and these three tree parameters were tested. The analysis of the selection criteria of the best models (Adjusted determination coefficients (R²aj), the residual standard error (RSE) and the Akaike information criterion (AIC)) made possible to select the best following equations: Ln(B) = -1.61+0.32Ln(D)+0.36Ln (DH*p), with R²aj = -0.477 and AIC = 275.22 for leaves; Ln(B)= -1.78+1.07in(D) + 0.35Ln(DH*p), with R²aj = 0.688 and AIC = 280.79 for the branches, Ln(B) -1.54 +0 .64Ln(D) +0.38Ln(D'H*p), with R²aj = 0.640 and AIC= -184.78 for the stems and Ln(B)= -0.10 + 0.72Ln(D) + 0.33Ln(D'H*p), with R²aj = 0.736 and AIC=180.24 for the total biomass. These equations provide a contribution to the reliable and rapid estimation of the carbon stock of the Ngaoundere savannah in the context of evaluating the contribution of the Sudano-guinea savannahs to climate change mitigation.