Browsing by Author "Ndagurwa, H.G."

Now showing 1 - 7 of 7
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    Changes in miombo woody assemblage along a disturbance gradient in a smallholder tobacco production communal land, northeast Zimbabwe
    (Elsevier, 2021-09-19) Zinyowera, N.I.; Ndagurwa, H.G.; Muvengwi, J.
    Harvesting of large, hard timber trees for tobacco curing and barn construction affects the integrity of miombo woodlands, yet impacts have been quantified in a few studies despite the recent increase in tobacco farming in rural Zimbabwe. Therefore, we examined nature of disturbances, vegetation structure, and woody assemblage of miombo woodland in five plots (20 m × 20 m) each established within 1 km, 2.5 km, and 4 km from the boundary of a smallholder tobacco production communal land in northeast Zimbabwe. Fire, livestock grazing, firewood and pole collection, and land clearing were the major anthropogenic disturbances, being more prevalent closer to the communal area. Consequently, these disturbances declined with increasing distance from the communal area. Although the majority of the species were associated with the more disturbed sites in the communal area, species diversity did not differ between the sampling categories. Tree height, diameter, and basal area increased but sapling density declined with distance from the communal area. Seedlings were larger and denser within the communal area boundary while mature trees were denser, dominant, and species-rich further away from the communal area. In all sampling categories, the diameter size-class distribution followed an inverse J-shape dominated by young trees indicating a stable, regenerating population. Together, our results show that, in response to disturbance, miombo woodland structure changes into a shrub-rich plant community, but species composition is unaffected due to resprouting and coppicing from stumps remaining on the site. Although the inverse J-shape observed in all sampled sites indicate a potentially resilient and persistent population, monitoring over longer periods is recommended to ensure sustainable use and better inform policy on woodland management in agriculture-dominated areas.
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    Comparability of radar and optical methods in identifying surface water in a semi-arid protected area
    (African Journal of Ecology, 2024-05-22) Dzinotizei, Z.; Ndagurwa, H.G.; Ndaimani, H.; Chichinye, A.,
    Surface water assumes a pivotal role in sustaining a wide range of wildlife species in semi‐arid protected areas. However, differences in surface water body typology, underlying soil type, wildlife activity, the presence of phytoplankton amongst other factors, result in high variability of surface water spectral reflectance and detection accuracy. In this study, the performance of radar and optical methods was evaluated in detecting surface water of variable spectral reflectance in Hwange National Park, Zimbabwe using Sentinel‐1 radar and Sentinel‐2 optical images for the period 2016–2023. Results demonstrated that radar methods had low surface water detection accuracy which was highly variable as shown by overall accuracy and kappa statistic measures which continuously changed over time compared with optical methods. The overall best‐performing method was the optical AWEInsh (sharpened) which showed high surface water detection accuracy and consistency (OA: 94%–100%) and (κ: 0.88–1.00) from 2016 to 2023. Therefore, optical methods present a stable and robust way for surface water monitoring in heterogeneous semi‐arid protected areas. However, radar‐based methods should be continually explored where optical‐based technologies are impeded as a result of vegetation cover and cloud conditions.
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    Ethnobotanical knowledge and use-value of Harpagophytum (Devil’s claw) in Matabeleland, Zimbabwe
    (Elsevier, 2021-09-17) Ncube, S.F.; Ndagurwa, H.G.; Mundy, P.J.; Sibanda, S.; Dlodlo, M.
    Quantitative ethnobotanical knowledge is important in guiding sustainable resource use, yet for many medicinal plants such as Harpagophytum (Devil's claw), this information is scanty. Thus, we documented the ethnobotanical knowledge of Devil's claw in Hwange, Gwanda, Matobo, and Tsholotsho, western Zimbabwe, in relation to a person's age, gender, level of education, and locality. Using a semi-structured questionnaire, we interviewed 205 respondents on their knowledge of the physical features, distribution, uses and use-values, part used, and the method of preparation of Devil's claw. Physical identification was assessed based on the frequency of knowledge of plant parts. Binomial General Linear Models were used to test the effect of age, education, gender, and locality on the respondent's knowledge. Relationships of age, gender, level of education, and locality to ethnoecological perceptions were assessed using Pearson's Chi-square test. Use values were assessed based on Plant Part Value (PPV), Use Value category (UVk), and Overall Use Value (OUV). Ethnobotanical knowledge varied with locality and age, with better physical description in most adults and senior respondents in Hwange and Tsholotsho. Respondent's perceptions showed that Devil's claw was more abundant in Hwange and Tsholotsho relative to Matobo and Gwanda. Tubers (53%) were most valued in all localities followed by leaves (29%), and fruits (18%). Of the five identified categories of use, medicinal (UVk of 0.38) was the most important while ethnoveterinary, rituals, personal care, and food were least important (all UVks ≤0.02). OUVs were dependent on locality, significantly higher in Hwange and Tsholotsho (0.64 and 0.58, respectively) as compared to Gwanda (0.1) and Matobo (0.28). This study provides a wealth of knowledge that contributes to the preservation of indigenous knowledge of Devil's claw, sustainable management of the plant as well as further contribute to pharmacological interventions.
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    In vitro antioxidant activity of crude extracts of Harpagophytum zeyheri and their anti-inflammatory and cytotoxicity activity compared with diclofenac
    (BMC Complementary Medicine and Therapies, 2021-09-23) Ncube, S.F.; McGaw, L.J.; Njoya, E.M.; Ndagurwa, H.G.; Mundy, P.J.; Sibanda, S.
    Background This study evaluated the in vitro antioxidant activity and comparison of anti-inflammatory and cytotoxic activity of Harpagopytum zeyheri with diclofenac. Methods In vitro assays were conducted using water, ethanol, and ethyl acetate extracts of H.zeyheri. The antioxidant activity was evaluated using the 2,2′-diphenyl-1-picrylhydrazy (DPPH) and 2,2′- azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The anti-inflammatory activity was determined by measuring the inhibition of nitric oxide (NO) on lipopolysaccharide (LPS)-induced RAW 264.7 mouse macrophages as well as cytokine (TNF-α and IL-10) expression on LPS-induced U937 human macrophages. For cytotoxicity, cell viability was determined using the 3-(4, 5-dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Results The ethyl acetate extract had the lowest IC50 values in the DPPH (5.91 μg/ml) and ABTS (20.5 μg/ml) assay compared to other extracts. Furthermore, the ethyl acetate extracts effectively inhibited NO and TNF-α and proved to be comparable to diclofenac at some concentrations. All extracts of H. zeyheri displayed dose-dependent activity and were associated with low levels of human-IL-10 expression compared to quercetin. Furthermore, all extracts displayed low toxicity relative to diclofenac. Conclusions These findings show that H. zeyheri has significant antioxidant activity. Additionally, similarities exist in the inflammatory activity of H. zeyheri to diclofenac at some concentrations as well as low toxicity in comparison to diclofenac.
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    Land use effects on phylogenetic and functional diversity of birds: Significance of urban green spaces
    (Elsevier, 2022-05-07) Muvengwi, J.; Fritz, H.; Mbiba, M.; Ndagurwa, H.G.
    Although research has been done in order to understand the impact of urban development on avian diversity, it mainly focused on taxonomic diversity. Here we aimed to assess biodiversity targeting beyond species richness since this has the potential to inform the conservation of healthy functioning ecosystem. We explored how functional and phylogenetic diversity vary between a protected area and urban green spaces. We collected avian data at Lake Chivero Park and six green spaces in the city of Harare, Zimbabwe. The avian point count method at 30 sites for each location (Harare and Lake Chivero Park) was conducted. Alpha diversity indices were compared between Harare and Lake Chivero Park using independent t-test. One-way analysis of variance was applied to test for variation in functional and phylogenetic beta-diversity metrics together with the respective standardized effect size. Urban green spaces had higher species richness, abundance, phylogenetic and functional diversity than Lake Chivero Park. Beta diversity between the two sites was much higher than within sites diversity. The two sites did not differ in terms of beta diversity. Our study shows that urban development that incorporates green spaces maybe critical in the conservation of functional and phylogenetic diversity of avifauna. We suggest that urban landscapes be considered in national and regional conservation plans since they can act as conduits between protected areas, especially for avifauna.
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    The coupling effects of pyrodiversity and land use on termite assemblages in semi-arid savanna
    (Elsevier, 2021-05-18) Ngwenya, B.T.; Ndagurwa, H.G.; Huruba, R.; Mlambo, D.; Mawanza, M.; Muvengwi, J.; MacFadyen, D.N.; Chirima, A
    Despite the importance of termites in the structure and function of savanna ecosystems, long-term studies that examine the effects of several disturbance factors on termite communities are limited constraining our understanding of determinants of termite assemblages in savanna. We determined termite assemblages in six random plots (100 m × 2 m) each established on no fire, low fire, and moderate fire frequency sites in a communal area and a commercial cattle-wildlife ranch in a semi-arid savanna, southwest Zimbabwe. Environmental variables i.e., soil and plant variables were also determined in the termite sampling sites. Relationships of land use, fire, and their interaction to (i) termite assemblage and (ii) soil and plant variables were tested using a general linear model (GLM). Relationships between termite assemblages and soil and plant variables were explored using canonical correspondence analysis (CCA). Nineteen termite species from three sub-families were present, dominated by Macrotermitinae. Termite species richness and abundance were greater by a factor of up to 2.8 in the ranch than in the communal area. Termite abundance and species richness only differed with fire frequency in the ranch, being greater at low fire frequency than at moderate fire frequency or no fire. Although some relationships were observed between the environmental variables and the composition of termite assemblages, the lack of differences in environmental variables between land uses and fire frequencies suggested that other factors may better explain the patterns in termite assemblages in this savanna.
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    The influence of African elephants on litter and soil nitrogen attributes in mopane woodland in Hwange National Park, northwest Zimbabwe
    (Elsevier, 2022-05-17) Maponga, T.S.; Ndagurwa, H.G.; Muvengwi, J.; Sebele, L.; Nzuma, T.M.
    Little is known about modification of nutrient fluxes through elephant-induced woodland change. We assessed litter quality, soil N attributes, and N transformations in five 20 × 20 m plots each established on sites of low, medium, and high elephant utilization categorized using dung-count surveys in three mopane woodland patches in Hwange National Park, Zimbabwe. Litter standing crop significantly declined but litter N, lignin, lignin:N, condensed tannins, and total phenols increased with increasing elephant utilization, peaking at intermediate levels of elephant utilization. Medium elephant utilization sites had more than twice the nitrate pools in low and high elephant utilization sites (p < 0.001). Ammonium concentration at low elephant utilization was lower by 65% and 92% than at high and medium elephant utilization, respectively. Soil moisture, infiltration rates, N mineralization, and nitrification decreased with increasing elephant utilization. Nitrogen mineralization and nitrification were up to four times greater in low than in medium and high elephant utilization sites. Ammonium, N mineralization, and nitrification were positively correlated to litter N but negatively correlated to condensed tannins. These results indicate that elephant-induced woodland change plays an important role in carbon and nutrient fluxes potentially increasing resources heterogeneity and reinforcing the patch dynamics of savanna.