Forests, Trees and Livelihoods Vol. 21, No. 2, June 2012, 97–113Impacts of decentralised forest management on forest resource changes were assessed. Six contrasting forest reserves regarding management regimes, that is, Joint Forest Management (JFM; in National Forest Reserves, owned by the State), Community Based Forest Management (CBFM; in village lands or general lands), and ordinary centralized state management, were selected. The forest resources were assessed by means of systematic sample plot inventories. Number of stems, basal area, volume, biomass, and carbon ha21 were compared with results from previous studies in the same reserves. Harvesting activities were also assessed as part of the sample plot inventories. In general, the results were somewhat ambiguous regarding the impacts of different management regimes. There was, however, some empirical evidence indicating that JFM and CBFM performed better than the ordinary state management, although uncontrolled exploitation of the forest has continued under decentralised forest management in the studied forests. The two regimes are promising forest decentralisation models for Tanzania, but more research is needed to understand the functions of different governance structures and how they may facilitate sustainability in both forest use and livelihoods.