Research Repository :: Browsing by Author "Mligo, Cosmas"

Browsing by Author "Mligo, Cosmas"

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Comparing Flow Regime, Channel Hydraulics and Biological Communities to Infer Flow-Ecology Relationships in the Mara River of Kenya and Tanzania
(2014) McClain, Michael E.; Subalusky, Amanda L.; Anderson, E.; Dessu, Shimelis B.; Melesse, Assefa M.; Ndomba, Preksedis M.; Mtamba, Joseph O. D.; Tamatamah, Rashid A.; Mligo, Cosmas
Equatorial rivers of East Africa exhibit unusually complex seasonal and inter-annual flow regimes, and aquatic and adjacent terrestrial organisms have adapted to cope with this flow variability. This study examined the annual flow regime over the past 40 years for three gauging stations on the Mara River in Kenya and Tanzania, which is of international importance because it is the only perennial river traversing the MaraSerengeti ecoregion. Select environmental flow components were quantified and converted to ecologically relevant hydraulic variables. Vegetation, macroinvertebrates, and fish were collected and identified at target study sites during low and high flows. The results were compared with available knowledge of the life histories and flow sensitivities of the riverine communities to infer flow–ecology relationships. Management implications are discussed, including the need to preserve a dynamic environmental flow regime to protect ecosystems in the region. The results for the Mara may serve as a useful model for river basins of the wider equatorial East Africa region.
Conservation of Plant Biodiversity of Namatimbili Forest in the Southern Coastal Forests of Tanzania
(2015) Mligo, Cosmas
The aim of this study was to determine the ecological characteristic of Namatimbili Forest in terms of plant species composition, stem size class structure, stand biomass, diversity, and distribution and identify endemic and threatened plant species that are found within the forest. Data were sampled by using transect method that were established in various habitats within the forest. A total of 312 plant species were found in 62 families, where Fabaceae (51 species) was the highly represented of all families. Of all plant species recorded, 26 are cited under IUCN red list and 36 are endemic species of East African Coastal Forests.The woodlands were more diverse with a Shannon’s index of 2.72 ± 0.21 followed by the riverine forest (1.64 ± 0.19), coral rags (2.28 ± 0.32) and closed canopy evergreen forest (2.32± 0.17) and this pattern was also applied to the species evenness and the difference among vegetation types was significant. The DCA ordination revealed a major variation at DCA-Axis1 where samples from riverine forest separated quite clearly and positioned on the right side of the ordination space. The coral rag habitat extended widely overlapping with other habitats because of high similarity in plant species composition. The woodland habitats separated from the evergreen forest habitat at DCA Axis 3 because of plant species composition differences between them, such that closed canopy trees and the understorey species characterized the evergreen habitats. The riverine forest had a density of 136 stems/ha with the DBH sizes between 41 and 292.99 cm and the stand biomass ranged from 0.1 to 876.06 m3/ha. However, high density of trees with DBH sizes beyond 90 cm was observed in the riverine forest, regardless of all the vegetation typeshaving individual stems beyond this size class. The coral rag vegetation had 42 stems/ha, with diameter at breast height (DBH) sizes ranging from 41 to 95.5 cm and stand biomass in a range from 0.1 to 59 m3/ha. The woodlands had 28 stems/ha with the DBH sizes between 41 and 77.38 cm with denser stems at the size class of 10-14 cm DBH and stand biomass in a range from 0.06 to 127.4 m3/ha. There were 31 stems/ha in the evergreen forest with the DBH sizes from 41.40 to 108.28 cm and stand biomass between 0.06 and 64.42 m3/ha. A significant difference exists in stand biomass, basal area, but no difference in crown cover among vegetation types. It can be concluded that, the heterogeneous habitat characteristics in Namatimbili Forest favour the performance of diverse plant species and determine their natural distribution patterns. Large proportion of plant species found in the forest is endemic to the East African Coastal Forests and some of these have been cited under various IUCN threat categories. However, exploitation of timber trees, fire, and clearance for cultivation negatively affected the plant species diversity, distribution and vegetation community structure in this forest. Based on the ecological importance of Namatimbili Forest, the forest need to be considered for gazetting for protection from habitat degradation caused by anthropogenic activities and it should be included in the natural resource management plans of the southern coastal forests of Tanzania.
Determination of the Soil Organic Carbon, Nitrogen, Available Phosphorus and the Combined Aboveground Plant Materials in the Semi‐Arid Mbulu District, Tanzania
(2009) Mligo, Cosmas
Soil of the semi-arid Mbulu District is part of the tropical soils, covered with sparse trees, shrubs or grasses in which domestic grazing animals have prevented the wide spread of vegetation cover. The study aimed at determining soil organic carbon (OC), total nitrogen (N), available phosphorus (P) and the combined aboveground plant materials. Six study sites were established in which soil samples were collected at the depths of 0–5, 6–10 and 11–20 cm. Soil samples were analysed for OC, N and P as well as the levels of N and P in the combined aboveground materials of Panicum coloratum and Hyparrhenia filipendula. The percentage concentrations of OC, N and P were high in the top soil than in the deeper soil horizons. However, analysis of variance showed significant differences of OC in some sites whereas no difference for N and P between soil depth classes. OC was highly related with N and P along soil depth classes. It was concluded that the availability of N and P was because of the decomposition of organic matter in the soil. Soil N and P were highly related with the same in the combined aboveground plant materials. It was concluded that the increased concentration of N and P in the soil resulted into availability of the same in P. coloratum and H. filipendula. There was a very high variation in N and P among sites with different levels of intensity of grazing. It was concluded that grazing animals contributes to the redistribution of soil elements in the rangelands because they graze upon plant parts but the excreta are dropped away from the grazed spot.
Diversity and Distribution Pattern of Riparian Plant Species in the Wami River System, Tanzania
(2016) Mligo, Cosmas
Aims The Wami River system is among the most important rivers for riparian plant biodiversity conservation but it is potentially threatened by anthropogenic activities. This study was aimed to determine riparian plant species diversity and distribution patterns in relation to the anthropogenic disturbances. Methods The transect method was used to collect vegetation data. Transects were established perpendicular to the river at intervals of 50 m downstream and five plots were systematically established, separated by 5-m distance along each transect. Results A total of 261 plant species in 68 families were recorded in the Wami River system with a Shannon diversity index in the range of 1.63 to 2.94 and a significantly decreasing trend downstream. Using the Two Way Indicator Species Analysis (TWINSPAN), three plant communities (A, B and C) emerged based on variations in riparian plant species composition among sites. Canonical correspondence analysis (CCA) indicated that the spatial pattern of riparian plant species was significantly influenced by environmental variables. This implies that the plant species composition gradients and spatial assemblages of vegetation communities are a result of human disturbances. Because of the fragile nature of the riparian system, some species are more vulnerable than others and hence there is an urgent need for better land use planning to conserve riparian plant biodiversity in the sub-Basin of Wami River.
The Effect of Anthropogenic Disturbances on Population Structure and Regeneration of Scorodophloeus Fischeri and Manilkara Sulcata in Coastal Forests of Tanzania
(2011) Mligo, Cosmas; Lyaruu, H. M. V.; Ndangalasi, Henry J.
Scorodophloeus fischeri (Fabaceae, subfamily Caesalpinoideae) and Manilkara sulcata (Sapotaceae) are examples of tropical African hardwood species and are endemic to East African coastal forests. These plant species are threatened by human activities beyond natural recovery in some forests. This study aimed to assess the effects of anthropogenic disturbance on the natural regeneration potential of S. fischeri and M. sulcata in the selected coastal forests of Tanzania. Transects were established in various vegetation communities and a nested quadrat technique was used to assess the natural regeneration. Scorodophloeus fischeri regenerates best in Zaraninge forest with high density of trees with diameter at breast height (DBH) between 10–50 cm and a higher seedling density than in other forests. Similarly, M. sulcata regenerates best in Pande forest, although many trees had a DBH of 10–30 cm, implying that the trees with size classes above these are missing. It was concluded that the minimum level of human disturbances in Zaraninge favoured high potentials of natural regeneration of S. fischeri. Disturbances through human activities contributed to the variation in the natural regeneration potentials for S. fischeri and M. sulcata in these forests. Conservation attention is likely to improve population structure and natural regeneration patterns of S. fischeri and M. sulcata in East African coastal forests.
The Effect of Anthropogenic Disturbances on Population Structure and Regeneration of Scorodophloeus Fischeri And Manilkara Sulcata In Coastal Forests Of Tanzania
(Taylor & Francis, 2011-07) Mligo, Cosmas; Lyaruu, Hvm; Ndangalasi, Henry J.
Scorodophloeus fischeri (Fabaceae, subfamily Caesalpinoideae) and Manilkara sulcata (Sapotaceae) are examples of tropical African hardwood species and are endemic to East African coastal forests. These plant species are threatened by human activities beyond natural recovery in some forests. This study aimed to assess the effects of anthropogenic disturbance on the natural regeneration potential of S. fischeri and M. sulcata in the selected coastal forests of Tanzania. Transects were established in various vegetation communities and a nested quadrat technique was used to assess the natural regeneration. Scorodophloeus fischeri regenerates best in Zaraninge forest with high density of trees with diameter at breast height (DBH) between 10–50 cm and a higher seedling density than in other forests. Similarly, M. sulcata regenerates best in Pande forest, although many trees had a DBH of 10–30 cm, implying that the trees with size classes above these are missing. It was concluded that the minimum level of human disturbances in Zaraninge favoured high potentials of natural regeneration of S. fischeri. Disturbances through human activities contributed to the variation in the natural regeneration potentials for S. fischeri and M. sulcata in these forests. Conservation attention is likely to improve population structure and natural regeneration patterns of S. fischeri and M. sulcata in East African coastal forests.
The Impact of Grazing on Plant Natural Regeneration in Northern Slopes of Mount Kilimanjaro, Tanzania
(Scientific Research, 2015) Kikoti, Imani A.; Mligo, Cosmas; Kilemo, Dominico B.
Livestock grazing is considered to be of great ecological importance in terrestrial ecosystems if sustained at acceptable levels. Overgrazing has ecological ramifications which lead to degradation of the ecosystem. This has become a problem in many parts of Tanzania. A study was conducted in Northen Slopes of Mount Kilimajaro in order to examine the impact of grazing on natural regeneration of the grazed vegetation. This paper is guided by the hypothesis that the species richness, species diversity and density of regenerants vary across grazing intensities. The study area was divided into four zones as per grazing intensity namely heavily grazed areas, moderately grazed, least grazed and ungrazed areas. Ten rectangular quadrats of 20 m × 25 m were established in each zone, making a total of 40 quadrats in the entire study area. A stratified random sampling procedure was used in locating quadrats in each zone of grazing intensity whereby two subquadrats of 2 m × 5 m were nested in bigger quadrats. Natural regeneration was assessed in terms of species diversity and density of seedlings, saplings and poles. Results indicate that species regeneration varied among areas with different grazing intensity. The variations of seedlings and saplings density among areas with different grazing intensity were statistically significant. The species diversity of regenerants differed significantly among areas with different grazing intensity. Keeping the grazing intensity at low and moderate levels will stimulate more plant growth and diversity as opposed to heavy grazing which will lead to vegetation retrogression.
The Impact of Livestock Grazing on Soil Characteristics in Mount Kilimanjaro, Tanzania
(Scientific Research, 2015) Mligo, Cosmas
Livestock grazing is an anthropogenic disturbance on the soil properties in montane forests of the northern slopes of Mount Kilimanjaro. It was determined the effect of livestock grazing on SOC, N, CEC, SAS, SFD and P in the montane forest. Forty plots were randomly established for collection of soil samples. Data showed livestock grazing decreased the accumulation of SOC and consequently negatively affected the natural pattern of N, P, SFD, CEC and SAS. An opposing pattern of available soil phosphorus was interpreted that the nutrient pool retained in plant tissues particularly in the long-lived trees, which were absent in heavily grazed area. The observed positive correlation between SOC with TN and CEC implies the livestock grazing impacts on the former negatively affected the later soil parameters. Low fungal density in degraded parts of the montane forest indicates that they are sensitive to the current land use change. Based on the observation from this study, it can be regarded that excessive livestock grazing has a long-term negative ramification for soil conservation in montane forest. An important decision has to be sought off with regard to the conservation management of soil characteristics of the montane forest in Kilimanjaro Mountain.
Impacts of Livestock Grazing on Plant Species Composition in Montane Forests on the Northern Slope of Mount Kilimanjaro, Tanzania
(Taylor and Francis, 2015) Kikoti, Imani A.; Mligo, Cosmas
The montane forests on Mount Kilimanjaro are part of the ecologically protected area and provide ecosystem services to the local communities on the lower slopes. Despite their ecological value, the montane forests on the northern slope of Mount Kilimanjaro have been affected by increased livestock grazing pressure due to prolonged drought and expansion of agricultural land. We examined the impacts of livestock grazing on plant species composition in the montane forests on the northern slope of Mount Kilimanjaro. The study area was sub-divided into heavily grazed, moderately grazed, lightly grazed and ungrazed sites. A quadrat method was used for field data collection. A total of 115 plant species distributed within 93 genera and 39 families were identified. Moderately grazed and lightly grazed areas had higher plant species diversities than heavily and ungrazed areas. This observation concurs with the intermediate disturbance hypothesis. However, plant species that contributed to high species richness and diversity in grazed areas were mainly grasses, shrubs and herbs. It was concluded that livestock grazing in montane forests on the northern slope of Mount Kilimanjaro has serious impacts on vegetation community composition. Conservation of montane forest habitat and improvement of rangelands on communal land are necessary.
Plant Species Composition and Distribution in Relation to Land Use Patterns in Serengeti Ecosystem Tanzania
(Scientific Research, 2015) Mligo, Cosmas
Serengeti is the largest ecosystem in Tanzania endowed with high level of biodiversity in protected and unprotected areas. Serengeti National Park is the only protected area in a matrix of unprotected areas characterized with a wide range of human activities which threaten biodiversity conservation. It was assessed plant species composition, diversity, distribution and vegetation structure in both the protected and unprotected areas of the ecosystem. Two transects with twenty plots each were established in each vegetation type in which data was collected. A significantly higher species composition (262) and diversity (2.39 ± 0.03) was observed in unprotected areas than in the protected area (163 and 2.06 ± 0.04 respectively). The DCA ordination of the species data from the two management regimes formed four clusters based on similarity in plant species composition, where three clusters were from unprotected areas and one from protected area. The variations in plant species composition ranged from 35.69% to 65.92% for the first four DCA axes. There was no significant difference in stem density between protected and unprotected areas of the ecosystem. Although high density of trees at 10 - 14 cm DBH sizes was observed in both sides of the conservation management regimes, individuals with DBH above 65 cm existed in the protected area but were absent in unprotected areas. It can be concluded that the decrease of plant species diversity and density in unprotected area is because of habitat degradation associated with exploitation pressure, livestock grazing and other forms of disturbance related with anthropogenic activities. Because of high demand for plant resources, the local community needs to establish woodlots to cater for wood resource needs outside the protected areas of Serengeti. Also, pastoralists need to diversify livestock keeping systems compatible with limited grazing land in unprotected area of the Serengeti ecosystem.
Regeneration Pattern and Size-Class Distribution of Native Tree Species in Exotic Plantation in Pugu Forest Reserve, Tanzania.
(2012) Rocky, J.; Mligo, Cosmas
Pugu Forest Reserve is among coastal forests in Tanzania which is highly degraded through exploitation. To conserve the forest, part of natural forest was cleared and established exotic plantation to provide forest resource needs for the nearby residents. However, the regeneration pattern of indigenous trees in the exotic plantation was not monitored. It was aimed at assessing diversity, population structure, size class distribution and natural regeneration pattern of indigenous trees in exotic tree plantation. Vegetation data was collected using nested plots established along transects on both exotic tree plantation and the natural forest. The diameter size classes for most trees were less than 25 cm with poor recruitment at lower size classes implying an unstable plant population structure. Significant difference existed on the abundance of indigenous plant species between those in exotic tree plantation and the natural forest. However, the indigenous plant species regenerated successfully in exotic tree plantation as it occurred in the natural forest. Conclusively, establishing exotic plantation through clearing natural forests required monitoring as a management strategy because indigenous woody plants recovered through natural regeneration and outcompeted exotic trees in the plantation.
Two ‘Extinct’ Trees Rediscovered Near Kilwa, Tanzania
(2011) Clarke, Philip G.; Burgess, Neil D.; Mbago, Frank M.; Mligo, Cosmas; Mackinder, Barbara; Gereau, Roy E.
Preliminary botanical explorations in the little-known Namatimbili-Ngarama forest block located some 35 km inland of Kilwa in south-east Tanzania have rediscovered and further confirmed the presence of two tree species, Erythrina schliebenii Harms and Karomia gigas (Faden) Verde., that were previously thought to have become extinct. Both trees are endemic to the Coastal Forests of Eastern Africa hotspot and to the Swahilian Regional Centre of Endemism.
Vegetation Community Structure, Composition and Distribution Pattern in the Zaraninge Forest, Bagamoyo District, Tanzania
(2009) Mligo, Cosmas; Lyaruu, Herbet; Ndangalasi, Henry J.; Marchant, Rob A.
Zaraninge Forest, part of the Coastal Forest Biodiversity Hotspot of Tanzania, is threatened by human activities. The effect of such activities on the ecology of the forest is less known. Nested quadrat sampling technique was used along preestablished transect lines. Trees had a stem density of 521 ha-1, the majority falling in Diameter at Breast Height (DBH) size classes 9.5 to 44.9 cm. There was no significant difference in species diversity between sampling areas, which had a Shannon's diversity index ranging from 1.64 to 2.63. PCA identified two vegetation sample groups with Baphia kirkii, Cynometra webberi, C. brachyrachis, Scorodophloeus fischeri and Tessmannia burttii being abundant in both groups. TWINSPAN revealed three vegetation communities: Community A was fragmented woodlands characterized by the effects of fire and exploitation and having few remaining individuals of the valuable timber trees Afzelia quanzensis and Pterocarpus angolensis; community B was growing in a moist ecologically rich habitat and included rare species (Inhambanella henriquesii), endemic species (T. burttii, C. brachyrachis and S. fischeri); and community C had dry habitats dominated by C. webberi and C. brachyrachis. We conclude that habitat characteristics, fire, past and the present exploitation clearly influence the species diversity, distribution and variation in vegetation communities. The results are discussed in context of current and future management plans for this ecologically important forest.

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