Browsing by Author "Muvengwi, J."

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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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    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.