Browsing by Author "Eid, Tron"

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Above- and belowground tree biomass models for three mangrove species in Tanzania: a nonlinear mixed effects modelling approach
(Springer, 2015-10) Njana, Marco Andrew; Bollandsås, Ole Martin; Eid, Tron; Malimbwi, Rogers Ernest; Zahabu, Eliakimu
& Key message Tested on data from Tanzania, both existing species-specific and common biomass models developed elsewhere revealed statistically significant large prediction errors. Species-specific and common above- and below- ground biomass models for three mangrove species were therefore developed. The species-specific models fitted bet- ter to data than the common models. The former models are recommended for accurate estimation of biomass stored in mangrove forests of Tanzania. & Context Mangroves are essential for climate change mitiga- tion through carbon storage and sequestration. Biomass models are important tools for quantifying biomass and car- bon stock. While numerous aboveground biomass models exist, very few studies have focused on belowground biomass, and among these, mangroves of Africa are hardly or not represented.
Forestland tenure systems in Tanzania: an overview of policy changes in relation to forest management
(Department of Ecology and Natural Resource Management Norwegian University of Life Sciences, 2009) Zahabu, Eliakimu; Eid, Tron; Kajembe, George; Mbwambo, L.; Mongo, Cellina; Sangeda, Anthony; Malimbwi, Rogers; Katan, Josiah; Kashaigili, Japhet; Luoga, Emmanuel
ummary Zahabu, E., Eid, T., Kajembe, G. C., Mbwambo, L., Mongo, C., Sangeda, A.Z., Malimbwi, R. E., Katani, J.Z., Kashaigili, J.J. and Luoga, E.J. 2009. Forestland tenure systems in Tanzania: an overview of policy changes in relation to forest management [Eiendomsforholdene for skogarealer i Tanzania: en oversikt over policyendringer i skogforvaltningen]. INA-fagrapport no. 14, 24 pp. A review of the role of forestland tenure systems in Tanzania, and how different forestland tenure approaches and reforms have influenced forest management is presented. The complexity of land reforms and processes that have taken place in Tanzania during the pre-colonial, colonial and post-independence periods is discussed. The pre-colonial period, though not much is written, was characterised by forest management through traditional institutions, low population and low forest resources exploitation. Colonial governments undermined the role of local traditions in managing the forests related to for example burial areas and springs. They also established forest reserves and in some areas cleared indigenous forests to establish tea, coffee and exotic fruit and timber plantations. Different land reforms that were geared towards sustainable development occurred after independence, forests depletion continued, however. Currently, it is observed that there coexists state, village, private and collective rights on forests without clear ownership. This is greatly linked to the ongoing deforestation and forest degradation in the country. In this situation, sustainable forestland use may be attained through establishing an enabling environment that allows effective local communities’ participation in forest management. Sustainable management, however, always presupposes effective control of harvesting and other activities to secure the carrying capacity of forests and woodlands, whether it is undertaken by central authorities or local people. Studies on forestland tenures and rights, and the impact of changes in tenures and rights on forest resources and rural livelihoods are therefore important. Such studies are required for the provision of facts for the establishment of proper future policy means that aim at reducing forest degradation and improving livelihoods in Tanzania.
Forestland tenure systems in Tanzania: an overview of policy changes in relation to forest management
(INA fagrapport, 2009) Zahabu, Eliakimu; Eid, Tron; Kajembe, George; Mbwambo, Lawrence; Mongo, Cellina; Sangeda, Anthony; Malimbwi, Rogers; Katani, Josiah; Kashaigili, Japhet; Luoga, Emmanuel
A review of the role of forestland tenure systems in Tanzania, and how different forestland tenure approaches and reforms have influenced forest management is presented. The complexity of land reforms and processes that have taken place in Tanzania during the pre-colonial, colonial and post-independence periods is discussed. The pre-colonial period, though not much is written, was characterised by forest management through traditional institutions, low population and low forest resources exploitation. Colonial governments undermined the role of local traditions in managing the forests related to for example burial areas and springs. They also established forest reserves and in some areas cleared indigenous forests to establish tea, coffee and exotic fruit and timber plantations. Different land reforms that were geared towards sustainable development occurred after independence, forests depletion continued, however. Currently, it is observed that there coexists state, village, private and collective rights on forests without clear ownership. This is greatly linked to the ongoing deforestation and forest degradation in the country. In this situation, sustainable forestland use may be attained through establishing an enabling environment that allows effective local communities’ participation in forest management. Sustainable management, however, always presupposes effective control of harvesting and other activities to secure the carrying capacity of forests and woodlands, whether it is undertaken by central authorities or local people. Studies on forestland tenures and rights, and the impact of changes in tenures and rights on forest resources and rural livelihoods are therefore important. Such studies are required for the provision of facts for the establishment of proper future policy means that aim at reducing forest degradation and improving livelihoods in Tanzania.
Impact of forstland tenure changes on forest cover, stocking and three species diversity in Amani natural reserve, Tanzania
(Academic Publishers, 2011) Mpanda, Mathew M; Luoga, Emmanuel J; Kajembe, George C; Eid, Tron
The aim of the present study was to evaluate the impact of changes from private to state tenure on forest resources for three blocks in Amani Nature Reserve. The resource changes were determined in terms of forest cover, forest stocking and tree species diversity over a period of six to eight years. When considering the three blocks as one entity one may in general maintain that there have been positive changes regarding forest cover. There were differences between the blocks, however. The proportions of dense and semi-closed forest increased by around 14% in the former tea company block, remained unchanged in the former farmland and decreased by around 12% in the former sisal company block. The changes in stocking parameters and tree species diversity were mainly positive, but none were statistically significant. Although the results were somewhat ambiguous evidence of positive impacts as a result of the tenure changes was identified. This is in line with the main aim of establishing nature reserves focusing on conservation values. More research, however, is required regarding impacts of tenure changes on livelihood for those living adjacent to the nature reserve.
Models for estimation of tree volume in the miombo woodlands of Tanzania
(Southern Forests: a Journal of Forest Science, 2014) Mauya, Ernest W.; Mugasha, Wilson A.; Zahabu, Eliakimu; Bollandsås, Ole M.; Eid, Tron
Volume of trees is an important parameter in forest management, but only volume models with limited geographical and tree size coverage have previously been developed for Tanzanian miombo woodlands. This study developed models for estimating total, merchantable stem and branches volume applicable for the entire miombo woodlands of Tanzania. We used data from 158 destructively sampled trees, including 55 tree species collected from wide geographical and biophysical ranges. We developed general and site-specific models with diameter at breast height only as the independent variable, together with models with both diameter at breast height and tree height. Leave-one-out cross-validation was used to evaluate the models. The total tree volume models that included diameter at breast height and tree height had appropriate predictive capabilities with relative root mean square errors (RMSEr) ranging from 30.5% to 47.6%. The RMSEr for total tree volume models with diameter at breast height only ranged from 39.9% to 48.0%. The site-specific models had slightly lower RMSEr values relative to the general models. The relative mean prediction error of the general total tree volume model with diameter at breast height and tree height was lower (0.6%) than those of the previously developed models (−30.7% to 31.2%). Based on the evaluations, we recommend the general total tree models to be applied over a wide range of geographical and biophysical conditions in Tanzania.
mpact of forestland tenure changes on forest cover, stocking and tree species diversity in Amani nature reserve, Tanzania
(Taylor & Francis, 2016) Mpanda, Mathew M.; Luoga, Emmanuel J.; Kajembe, George C.; Eid, Tron
The aim of the present study was to evaluate the impact of changes from private to state tenure on forest resources for three blocks in Amani Nature Reserve. The resource changes were determined in terms of forest cover, forest stocking and tree species diversity over a period of six to eight years. When considering the three blocks as one entity one may in general maintain that there have been positive changes regarding forest cover. There were differences between the blocks, however. The proportions of dense and semi-closed forest increased by around 14% in the former tea company block, remained unchanged in the former farmland and decreased by around 12% in the former sisal company block. The changes in stocking parameters and tree species diversity were mainly positive, but none were statistically significant. Although the results were somewhat ambiguous evidence of positive impacts as a result of the tenure changes was identified. This is in line with the main aim of establishing nature reserves focusing on conservation values. More research, however, is required regarding impacts of tenure changes on livelihood for those living adjacent to the nature reserve.
Procedures for quantification of belowground biomass of three mangrove tree species
(Springer Science, 2015-02) Njana, Marco Andrew; Eid, Tron; Zahabu, Eliakimu; Malimbwi, Rogers
A review of studies on belowground biomass (BGB) of mangroves revealed that proce- dures for excavation and determination of dry weight are insufficiently documented. The main objective of this study was therefore to describe procedures for quantification of tree BGB for Avicennia marina (Forssk.), Sonneratia alba J. Smith and Rhizophora mucronata Lam. The study covered four sites in Tanzania where 30 trees were sampled (10 for each species). A new root sampling procedure applied for A. marina and S. alba seemed to work adequately. Dry to fresh weight ratios (DF-ratios) varied between tree species, between tree sizes and between root compo- nents. Therefore, for each tree species, tree- and root component-specific DF-ratios were applied for dry weight determination. For A. marina and S. alba trees, a significant proportion of total tree BGB is stored in the root crown (34 and 10 % respectively). Future studies should therefore ensure inclusion of root crown when accounting for total tree BGB.