Timber potential value in the eastern-arc mountains, Tanzania: Nyanganje Forest Reserve

Abstract

The study was conducted to determine the quantity of timber and extent of illegal timber harvesting in Eastern Arc Mountains. Data were collected using three techniques: desktop review which was used to collect information on timber stocks from two studies in EAMs while socio-economic and ecological surveys were employed to collect information on timber disturbances and timber stocks harvested illegally in NFR. Data analysis involved use of Microsoft excel and Statistical Package for Social Sciences (SPSS). A t-test analysis showed that, the EAMs have high potential in terms of timber tree stocks (p (t) = 0.047 d.f = 39) for stems per ha and (p (t) = 0.001 d.f = 39) for volume per ha). Also linear regression analysis showed that, extraction of timber trees in NFR mostly occurs illegally at the roadside (R2 = 0.19, p = 0.015). A total of 135 600 000 stems and 74 400 000 m3 (an equivalent of 0.6 m3 per tree) composed of 180 different timber species were identified in EAMs. The major timber species contributed 47 000 000 m3 (63%) of total wood volume. Taking the royalty and volume of each timber classes for indigenous and exotic species, the value of timber in EAMs was USD 5576 million. The harvestable timber was about USD 4461 million for trees sizes of greater than 40 cm DBH. The mean annual quantity of wood harvested illegally was estimated to be 6.2 m3 per ha, of which 2.7 m3 per ha was due to timber harvesting. If extraction is done in every hectare in NFR, each year the government could lose USD 0.36 million. Though the EAMs have high potential of timber species, this potentiality will be depleted if effective measures are not taken due to the fact that currently these forests are under pressure for timber extraction. The timber trees species thus need to be well managed and conserved, to ensure sustainability.