Prevalence and standing volume of Dalbergia Melanoxylon in Coastal and Inland sites of Southern Tanzania

Abstract

In order to determine the prevalence and standing volume of Dalbergia melanoxylon( mpingo), 120 sample plots were laid out in each of two districts, Kilwa and Nachingwea, representing coastal and inland woodlands in Lindi Region, southern Tanzania. Using data from felled trees, volume equations for various utilisation classes were constructed. Also estimated were the basic density of mpingo, the percentage content Of heartwood, sapwood, and heartrot, and the thickness of bark and sapwood.The basic density values for mpingo were 1.14,0.76 and 1.06 g cm' for heartwood, sapwood, and both heartwood and sapwood. These are multiplier factors to obtain biomass values from volume. The heartwood content of mpingo is 83% of the total volume and the rest (17%) is sapwood and bark. Based on a few logs observed 13% of the total volume may be expected to have heartrot. The sapwood thickness is 1.1 cm with little variation irrespective of log diameter. The bark is thin (3.7 mm) and soft making the tree susceptible to damage by bruising and fire.The inland forests have twice as much overbark volume of mpingo as the coastal forests with 10 and 5 m3 ha"1 respectively. The merchantable volume to 20 cm top diameter overbark is 4.4 and 1.7 m3 ha"1 accounting for only 43 and 33% of the total volume per hectare respectively. Since regeneration of mpingo is easy, there is no immediate need to classify mpingo as an endangered species provided fire control is enhanced as an important conservation measure. It is, however, appropriate to regard the species as threatened.