Browsing by Author "Henry, Matieu"

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Allometric models for estimating tree volume and aboveground biomass in lowland forests of Tanzania
(International Journal of Forestry Research, 2016) Mugasha, Wilson Ancelm; Mwakalukwa, Ezekiel Edward; Luoga, Emannuel; Malimbwi, Rogers Ernest; Zahabu, Eliakimu; Silayo, Dos Santos; Sola, Gael; Crete, Philippe; Henry, Matieu; Kashindye, Almas
Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sample of 60 trees which were destructively harvested from both dry and wet lowland forests of Dindili in Morogoro Region (30 trees) and Rondo in Lindi Region (30 trees), respectively, this study developed site specific and general models for estimating total tree volume and aboveground biomass. Specifically the study developed (i) height-diameter (ht-dbh) models for trees found in the two sites, (ii) total, merchantable, and branches volume models, and (iii) total and sectional aboveground biomass models of trees found in the two study sites. The findings show that site specific ht-dbh model appears to be suitable in estimating tree height since the tree allometry was found to differ significantly between studied forests. The developed general volume models yielded unbiased mean prediction error and hence can adequately be applied to estimate tree volume in dry and wet lowland forests in Tanzania. General aboveground biomass model appears to yield biased estimates; hence, it is not suitable when accurate results are required. In this case, site specific biomass allometric models are recommended. Biomass allometric models which include basic wood density are highly recommended for improved estimates accuracy when such information is available.
NAFORMA: National forest resources monitoring and assessment of Tanzania Mainland
(FAO, 2022) Rajala, Tuomas; Heikkinen, Juha; Gogo, Sophia; Ahimbisibwe, Joyce; Bakanga, Geofrey; Chamuya, Nurdin; Perez, Javier Garcia; Kilawe, Edward; Kiluvia, Shani; Morales, David; Nzunda, Emmanuel; Otieno, Jared; Sawaya, Jonathan; Vesa, Lauri; Zahabu, Eliakimu; Henry, Matieu
hree options for the sampling design of the field plot clusters of NAFORMA II biophysical survey are compared in this report. Option 1 consists of re-measuring all NAFORMA I field sample plots (3 205 clusters) and Option 2 of re-measuring only those that were established as permanent (848 clusters). The recommended Option 3 is a compromise between these two “extreme” options: Re-measure a subset (1 405 clusters) of NAFORMA I field sample plots including (almost) all permanent clusters and a carefully selected set of other NAFORMA I field plot clusters to obtain a uniform sample within each TFS zone. Design Option 3 has the following features: • • • • Sampling intensity is uniform within each TFS zone. This makes it simple to use the data. For example, mean volumes can be estimated by averages over the plots. The selected clusters are well-spread over the target population. The anticipated precision of land-class area and mean wood volume relative to sample size is nearly as good as that of NAFORMA I. All proposed clusters were measured in NAFORMA I, which enables precise estimation of change based on repeated measurements. The costs and precision were anticipated by utilizing NAFORMA I field data, information about subsequent improvements in the road network, and changes in land-use using satellite imaging derived land-class maps.