Subsistence use of wood products and shifting cultivation within a miombo woodland of eastern Tanzania, with some notes on commercial uses

This study categorizes different subsistence and commercial uses of resourc es and quantifies the amount of wood used for firewood and building poles w ithin an eastern Tanzanian miombo woodland site. Data from questionnaire su rveys were collected from 80 households sampled from two villages. Firewood was used solely at the subsistence level by 96% of the population, with a per capita consumption of 1.5 +/- 0.17 (SE) m(3) year(-1), whereas building poles were not only used at subsistence level but were partly commercialis ed in the informal market. Per capita consumption of wood for building pole s was 0.138 +/- 0.01 m(3) year(-1), based on an average house life-span of eight years. Timber and charcoal production were the most commercialised re sources. Shifting cultivation, which is undertaken in the majority of the a reas cleared for charcoal, is practiced by 68% of the population while perm anent cropping is practiced by 32% of the population. Both farming systems predominantly comprise mono-cropping and mixed-cropping of cereals with bea n crops. Shifting cultivation changes vegetation structure from woodlands t o bushlands because of a short fallow period of only four years after conti nuous farming for about six years. Current levels of subsistence use of fir ewood and poles appear to be sustainable, but levels of shifting cultivatio n are not. However, selection of favoured species for building poles often leads to over-exploitation, especially when these species are inherently sc arce.