Aboveground Biomass Estimation of &i&Avicennia marina&/i& (Forssk) Vierh. and &i&Rhizophora mucronata&/i& Lam. in the Mangoky Delta, SW Madagascar

摘要

Forty-three trees (23 Rhizophora mucronata and 20 Avicennia marina ) were studied for the establishment of allometric relationships between the aboveground biomass “y” and the following dendrometric variables “x”: diameter at breast height DBH, (DBH)2 product Ht (where Ht is the total height), and the basal circumference Cb of the trees. The Log y = A Log [(DBH)2·Ht] + B equation gives a fairly satisfactory regression coefficient (R2 > 0.9) for the woody compartments. For A. marina , it is the equation Log y = A Log Cb + B that is the best correlated for the estimation of less woody compartments (R2 = 0.826 to 0.847). As for R. mucronata , these are much more related to DBH. For trees of 8 - 10 m height, the aboveground biomass of the delta is higher (171 t·ha-1 for R. mucronata ) than that of Puerto Rico, but quite comparable to that of Australia (110 t·ha-1 for A. marina ). The first tools for estimating aboveground biomass are given for these two characteristic species of the Indo-Pacific Region and East Africa. Because of the low values of the regression coefficients for some allometric relationships obtained, precautions should be taken in case of extrapolation.