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. Th...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.展开更多
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 characteri...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.展开更多
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...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.展开更多
Aims The Wami River system is among the most important rivers for ripar-ian plant biodiversity conservation but it is potentially threatened by anthropogenic activities.This study was aimed to determine riparian plant...Aims The Wami River system is among the most important rivers for ripar-ian 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,sepa-rated by 5-m distance along each transect.Important Findings 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 1.63-2.94 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.展开更多
文摘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.
文摘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.
文摘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.
文摘Aims The Wami River system is among the most important rivers for ripar-ian 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,sepa-rated by 5-m distance along each transect.Important Findings 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 1.63-2.94 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.
