Volume Models for Single Trees in Tropical Rainforests in Tanzania

Abstract

The present study was the first to develop total tree, stem and branches volume models for rainforests in south-eastern Africa based on destructive sampling. The number of sample trees was 60 and diameter at breast height (dbh) and total tree height (h) ranged from 6 to 117 cm and from 6.4 m to 50 m, respectively. Large parts of the total volume and stem volume variations were explained by the models (Pseudo-R2 ranged from 0.85 to 0.93) and they performed relatively well over different size classes. When considering the challenges in height measurements in rainforests, we in general recommend applying model 3 with dbh only as independent variable. For large trees we recommend model 2 (dbh and h as independent variables) because of the moderating effect h has on volume predictions. If accurate stem volumes are needed for forestry licensing or for calculating compensation of timber loss, we also recommend model 2. As long as the allometry of the trees obviously is not different from that of our study site, the developed models may also be applied for rainforests elsewhere in Tanzania, but further testing of the models is also recommended.