Browsing by Author "Malimbwi, Rogers E"

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Biomass and volume models based on stump diameter for assessing degradation of miombo woodlands in Tanzania
(Hindawi, 2018-12-27) Manyanda, Bernardol J; Mugasha, Wilson A; Nzunda, Emannuel F.; Malimbwi, Rogers E
Models to estimate forest degradation in terms of removed volume and biomass from the extraction of wood fuel and logging using stump diameter (SD) are lacking. The common method of estimating removals is through estimating diameter at breast height (D) by applying equations relating measured D and SD. The estimated D is then used to estimate biomass and volume by means of allometric equations, which utilize D. Through this sequence of procedures, it is apparent that there is an accumulation of errors. This study developed equations for estimating volume, aboveground biomass (ABG), and belowground biomass (BGB) using SD in miombo woodlands of mainland Tanzania. Volume models were developed from 114 sample trees while AGB and BGB models were developed from 127 and 57 sample trees, respectively. Both site specific and regional models were developed. Over 70% of the variations in BGB, AGB, and volume were explained by SD. It was apparent that SD is inferior compared to measured D in explaining variation in volume and BGB but not AGB. However, the accuracy of BGB and volume estimates emanating directly from SD were far better than those obtained indirectly, i.e., volume or BGB estimates obtained from estimated D from SD, since the latter is affected by accumulation of regression equation errors. For improved accuracy of ABG, BGB, and volume estimates, we recommend the use of site specific models. However, for areas with no site specific models, application of regional models is recommended. The developed models will facilitate the addition of forest degradation as a REDD+ activity into the forthcoming FREL.
Woodlands and the charcoal trade: the case of Dar es Salaam City
(2008) Malimbwi, Rogers E; Zahabu, Eliakimu M
Tanzania has a total area of about 94.5 million ha out of which 88.6 million ha is covered by land- mass and the rest is inland water. Forests and woodlands in Tanzania cover about 34 million hec- tares making about 40% of land. Gazetted forestland is about 13 million hectares, predominantly managed by the Central Government. Only 600 000 hectares of the gazetted forest land are under the ownership and management of Local Governments. Game reserves and national parks consti- tute about 2 000 000 ha. Non gazetted forests in public lands cover about 19 million hectares and this is where forests are facing serious conversion to competing land uses. Non gazetted forests are also known as general land forests which are essentially open access. Deforestation in Tanza- nia, which is estimated at between 130 000 to 500 000 hectares per annum occurs mostly in the general land forests as well as degradation (loss of biomass) over much of the total forest area. Establishment of village forest reserves under Participatory Forest Management (PFM) which started in 1990s was found to retard deforestation in unreserved forestland. To date more than 3 million ha are under PFM (MNRT 2006) which is about 11% of total forest area. This reduces the open access forest area in the general land from 19 million ha to about 16 million, which is 47% of the entire forested land (Table 1).