Harvested and standing wood stocks in protected and communal miombo woodlands of eastern Tanzania

Abstract

Miombo ( Zambezian savanna) woodlands in protected and public (communal) lands of eastern Tanzania were examined to compare standing and harvested wood stocks and investigate different human disturbance gradients between the two utilization/management regimes. The standing volume in the forest reserve was 47±3.38 ( S.E.) m 3 ha −1 and the total removal volume (calculated from stumps) was 7.1±1.18 m 3 ha −1 . In the public lands, the standing volume was only 16.7±2.26 m 3 ha −1 and the total removal volume was 19.62±2.58 m 3 ha −1 . Harvesting intensity decreased with increasing distance from village settlements and reserve boundaries but the pattern had no significant overall impact on standing stocks of wood. The Dar-es-Salaam–Morogoro highway, which bisects the study area is the major axis of disturbance. Multivariate analysis indicated that the linear combinations of physiographic variables significantly influence the pattern of tree harvesting. Commercial harvesting for charcoal overrides patterns from other harvesting purposes because of economic incentive and the wide range of species and size classes harvested. The estimated annual wood removal for all uses of 6.38±2.39 m 3 ha −1 in public lands exceeds the reported mean annual increment (MAI) in the study area of 4.35 m 3 ha −1 yr −1. Thus present patterns of harvesting are changing the structure and composition of the vegetation, especially in the communal areas and are not sustainable. This will increase pressure for harvesting in reserves.