Browsing by Author "Ndangalasi, Henry Joseph"
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Item Implications of utilization of non-timber forest products in mountain ecosystems(University of Dar es Salaam, 2004) Ndangalasi, Henry JosephControl of Tanzanian protected forests is so far by use of regulatoiy policy instruments. The strategy does not adequately identify nor protect Non-Timber Forest Products (NTFPs) that are used by the local communities living close to the forests. Consequently, the local communities continue to use protected forests ‘illegally’. Examination of different NTFPs extracted by the local communities from montane forests and their effects on species diversity, composition and forest structure was carried out through interviews and observations. Uzungwa Scarp and Njerera Forest Reserves served as a case study. The study used 100-0. lha plots placed in the proximal (disturbed) and distal (undisturbed) forest sites in equal numbers. A total of 236 species represented by 7994 individual trees in 56 families, were recorded. Species diversity (H’) ranged from 2.139 to 3.609 in the proximal sites and from 2.462 to 3.045 in the distal sites. Except for Mbawi and Uhafiwa areas, proximal sites recorded significantly higher species diversity than distal sites (t-test, p<0.05). Also proximal sites consistently recorded lower total basal area (Mean 21.70±19.39 m ha'1) than the distal sites (Mean 40.84±17.87m ha'1). In addition, a significant difference in DBH size-class distribution was observed between the two contrasting sites (t-test, p<0.05); larger DBH size classes being confined to distal sites. Colonizing species such as Macaranga kilimandscharica dominated proximal sites, an indication that extraction of NTFPs favour their establishment. Classification of vegetation using TWINSPAN and Clustering methods resulted into four groups, a reflection of the topographical and geographical differences inherent of the area. Diameter at Breast Height size-class distribution of some canopy trees did not produce the expected reversed J-shaped curve even for trees recorded from distal sites, perhaps factors other than human disturbance are in operation, hence a need for further research. Eight types of NTFPs were identified: building poles, fiielwood, medicinal plants, etc, most of the products being extracted from protected forests. The density of commonly extracted species was approximately three times higher in the distal than proximal sites. The northern USFR is richer in NTFPs than the southern part. Use of NTFPs extracted from the protected forests by the local communities as revealed by this study show failure of the regulatory policy instruments in protecting forest reserves. The extraction of NTFPs threaten the stability of biodiversity. Intervention on current debarking of medicinal trees is necessary because targeted trees are killed in the process. The local communities should be assisted in establishing woodlots for both exotic and indigenous trees to satisfy their needs. There is also a need to involve the local communities in managing the forests and sharing the benefits. Simultaneously, a balance should be maintained between the local communities interests in these forests and the government’s interest in protecting biodiversity and water catchment areas.Item Studies on canopy gap characteristics and regenerating species composition in Pugu forest reserve, Tanzania(University of Dar es Salaam, 1997) Ndangalasi, Henry JosephCanopy gaps were studied in Pugu Forest Reserve, Tanzania in order to determine the causes of their formation, their size and regenerating species composition and diversity. The results show that canopy gaps were caused by both natural processes and anthropogenic activities such as felling trees for charcoal burning and building poles. Charcoal gaps ranged in area between 35m2 and 1462.5m2 with a mean area ± SD of 325.9m2±309.3. the northern part of the forest, with 92% of all the charcoal gaps recorded, was the most affected area when compared to the southern part. Estimates show that 7.65% of the total forest area was charcoal gaps. Panicum trichocladum and Trema orientalis (with a relative density of 22.2% and 15.3% respectively) were the most frequent colonizing species in these gaps. Manilkara sulcata, Scorodophloeus fischeri, Diospyros verrucosa, Vitex zanzibarensis and Haplocoelopsis Africana were the species most preferred for making charcoal. Natural canopy gaps ranged in size between 36m2 and 147m2 with a mean±SD of 88m2±29.6. Estimates show that 16.49% of the total Pugu forest Reserve was natural canopy gaps. The main cause of natural gaps were trecfalls, snapped-off branches and dead-standing trees, each of which accounted for 48.3% 31.0% amd 26.7% of all natural gaps respectively. In total 108, 227 and 207 species were recorded from the charcoal gaps, natural gaps and the undisturbed forest sites respectively. Natural gaps recorded the highest mean species diversity (Shannon’s Diversity Index) ±SD 2.4581 ±0.4875, followed by the undisturbed forest 2.3350±0.1252. charcoal gaps recorded the lowest species diversity at 2.2844±0.4613. Similarity in floristic composition between the charcoal gaps and adjacent undisturbed forest sites was low, with 86.5% of all the compared sites registering similarity indices of between 20% and 40%. On the contrary natural canopy gaps showed relatively higher similarity with 65.5% of all the compared sites recording similarity indices of greater than 40% with the adjacent undisturbed forest. There were no significant differences (t-test, p˃0.05) in the number of seedlings, saplings, poles and trees of 19 most frequent species occurring between the natural gaps and the undisturbed forest sites except for the saplings of Brachylaena huillensis (p=0.01) and poles of Rinorea angustifolia (p=0.047). the first two recorded more saplings in the canopy gaps than in the undisturbed forest sites, whereas the latter recorded more poles in the undisturbed forest sites than in the canopy gaps. Dominance-diversity profiles for 21 most frequently occurring species for seedlings, saplings, poles and trees from the canopy gaps and undisturbed forest sites indicated that only few species dominated each size class. Rinorea angustifolia was overwhelmingly dominant in the first three size class strata both in the bcanopy gaps and the undisturbed forest sites. Diameter size class distributions for the most frequently occurring tree species indicated that some species had negatively skewed distributions, while others had positively skewed distributions. However, in the case of Dialium holtzii and Newtonia paucijuga the majority of their members were in the above 35cm dbh size class. Poor representation of these species in the lower size classes probably indicates that recruitment of new members of these two species is currently not taking place.