Browsing by Author "Manoko, Mkabwa L.K.M."

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    Distribution patterns of plant species around North Mara Gold Mine in Tanzania
    (International Academic Journals, 2012-03) Mganga, Nyatwere; Manoko, Mkabwa L.K.M.; Rulangaranga, Zachariah K.R.
    Elevated heavy metals are toxic to many plants. There are many known edaphic factors affecting alteration of vegetation patterns. This study aimed to determine the relationship between bioavailable heavy metals and distribution patterns of plant species. Three parallel line transects of 3500 m long and 100 m apart were established opposite the mine wastes. Sampling was done at every 100 m up to 700 m and from the last 500 m. Numbers of plant species were systematically recorded using nested quadrats per transect and soil samples were collected at each point. The soil samples were analyzed for evidence of bioavailable heavy metals (copper, lead, chromium, zinc, cadmium and nickel) using an Atomic Absorption Spectrophotometer. Canonical Correspondence Analysis showed that levels of lead, chromium, cadmium and nickel negatively influenced distribution patterns of the plants. However, the Monte Carlo Permutation test showed that the measured metals did not have a significant influence on distribution patterns of the plants. It is likely that distribution patterns of the plants were also influenced by some other factors that were not currently investigated in this research. In terms of conservation as the main priority, waiting for evidence of the influence of heavy metals to have an obvious and significant effect on plant patterns may mean that an ecosystem has already undergone serious damage.
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    Variations in floristic diversity with distance around North Mara gold mine in Tanzania
    (2012-05) Mganga, Nyatwere D.; Manoko, Mkabwa L.K.M.; Rulangaranga, Zachariah K.
    Plant-heavy metal interactions and resultant variations in plant diversity are widely documented. However, such information was scanty at the study area. Three parallel line transects, each of 3500 m, 100 m apart were established opposite the mine wastes. Data were collected at Kwinyunyi (within 1 km from mine wastes) and at Masangora (within 3 km from mine wastes). Abundance of plant species was systematically recorded using nested quadrats; also, soils were sampled at each point. Soils were analyzed for bioavailable heavy metals by Atomic Absorption Spectrophotometer and for pH. The highest diversity index, richness and evenness were recorded within 1 km from mine wastes, while, the lowest diversity index and richness of plant species were recorded within 3 km from the waste. The lowest evenness of plant species was recorded within 1 km from mine wastes. T-test showed that the diversity, richness and evenness of plant species were not significantly different between Kwinyunyi and Masangora (p > 0.05). The levels of bioavailable chromium, cadmium, lead and nickel were above the internationally permissible ones. This study probably confirms that the ecosystem is robust and resilient in that plant communities sometimes adapt to conditions despite of alarmingly high levels of heavy metals.