Volume And Biomass Estimation Models For Tectona Grandis Grown At Longuza Forest Plantation, Tanzania

ABSTRACT

Quantifying tree volume, biomass and Carbon (C) stocks potential of tree crops by using allometric models is vital for understanding the contribution of forests on climate change mitigation effort. The existing allometric models for accurate estimations of total tree volume and total tree biomass for Teak (Tectona grandis) has limitation of application such as models being developed from few sample trees for model development and covered narrow range of diameters and excluded trees with small and large diameters. This study was carried out to fill these gaps by developing biomass and volume estimation models for Teak that cover a wide range of diameter. A total of 51 sample trees of diameter at breast height (Dbh) between 1.00 - 83.40 cm from seven compartments with ages of 2, 5, 16, 19, 21, 34 and 42 years were used for volume and biomass model development and evaluation. The sample trees were measured for Dbh and total height then felled down through excavation and cross cut into manageable billets which measured, measured for fresh weight, mid diameter and length. The twigs and leaves of each tree were tied into bundles and weighed. A total of 16 samples per tree from stem, branches, twigs and leaves, root crown, main roots and side roots were measured for fresh weight and taken to the laboratory for dry weight determination. Different types of models for biomass (total tree biomass, total above-ground and total below-ground) and volume were developed in this study. The selection of the best model was based on high R2, lower MSE and e%. The Akaike Information Criteria (AIC) was used as final criteria for selection of the best model in which the model with lower AIC was selected. The developed total tree biomass model for Teak was 0.7136×Dbh2.0282 (R2 = 98%, e% = 0.38 and AIC = 697) and the total volume equation up to cut off point of 2 cm was V=0.00120×Dbh1.9912 (R2 = 99%, e% = 2.2 and AIC =16).