Forest Resources and Wildlife Management Publications Newsletters

Permanent URI for this collection

http://196.220.97.103:4000/handle/123456789/168

Browse

Now showing 1 - 9 of 9

An overview of the Dept. of Forest Resources and Wildlife Management - National University of Science and Technology, Bulawayo, Zimbabwe
(SAWMA, 2009) Mundy, Peter J.
Effects of conspecifics and rocks on seedling recruitment of Brachystegia spiciformis Benth.in a dry miombo woodland in southern Africa
(Elsevier, 2021) Mlambo, D.; Chiparange, F.T.
Natural objects that buffer climate extremes and potentially function as regeneration niches are ubiquitous in dry miombo woodlands, yet few studies have explored their effects on early stages of plant recruitment. We used Brachystegia spiciformis to investigate the influence of conspecifics and rocks on early seedling recruitment in Cecil Kop Nature Reserve in Zimbabwe. B. spiciformis-dominated woodland was stratified into canopy and gap sites which were further divided into rock and rock-free microsites. In each microsite, we laid 3 blocks of 100 × 100 m and sow seeds of B. spiciformis in five 1 m2 plots close to rocks under canopies (CR), close to rocks in gaps (GR), rock-free in gaps (GF) and rock-free under canopies (CF), making a total of 60 plots. We laid additional 1 m2 plots to quantify the presence of naturally occurring seedlings at 1–12 m distances from boles of 15 trees in four cardinal directions. We found that photosynthetic photon flux density (PPFD), soil and air temperatures were significantly lower in CR, CF and GR than in GF while soil moisture displayed a reverse trend. Although seedling emergence was above 65% in all microsites, more than 60% of the seedlings died because of droughtrelated mortality which was increased in GF compared with other microsites. Survival probabilty of seedlings was highest in CF and CR, intermediate in GR and lowest in GF. Seedling biomass was increased in GR than under canopies despite higher concentrations of soil organic C, N and P in the latter. The density of naturally occurring seedlings was highest at the parent location than away from it, contradicting the Janzen-Connell recruitment pattern. We conclude that in dry miombo, conservation efforts may be well-served by focusing on the role of nurse objects in the plant recruitment process.
Disturbance impacts on the persistence niche of key species in the Baikiaea–Guibourtia–Pterocarpus woodlands of north-western Zimbabwe
(Taylor and Francis, 2021) Chichinye, A.; Geldenhuys, C.J.; Chirwa, P.W.
The persistence niche (studied through different modes of regeneration) of three key species (Baikiaea plurijuga (Harms), Guibourtia coleosperma (Benth.) J. Leonard, and Pterocarpus angolensis) (DC) under five different disturbance regimes (eight years after cessation of disturbance) was studied in the Baikiaea-Guibourtia-Pterocarpus woodlands of north-western Zimbabwe. The disturbance regimes were: protected area (no disturbance); timber concession area (timber harvesting); pole and firewood harvesting sites; abandoned crop fields (after clearing for agriculture); and burnt sites (fire disturbance). Influence of stump diameter and height on regeneration factors was investigated. For each disturbance regime, six main plots (100 m × 100 m) each were systematically laid out (20 m apart) to assess regeneration. In each main plot, 10 m wide transects (5 m apart) were surveyed for seedlings and saplings of the target species (at least 100 plants of each species), resulting in 7 transects per main plot, 42 transects in each study site and 210 transects in total. Number of seedlings with or without a rootstock (i.e., just grown from seed) was recorded. Diameter of stumps was measured at the cut surface. Shoot height was measured from their origin. Each target species was associated with mode of regeneration (χ² = 27 642, p < 0.001). Most plants regenerated from root suckers. Regeneration mode is dependent on disturbance regime (B. plurijuga χ² = 225.66, p < 0.001; G. coleosperma χ² = 158.62, p < 0.001; and P. angolensis χ² = 144.01, p < 0.001). Stump diameter negatively influenced number of sprouts for B. plurijuga and P. angolensis, but positively influenced sprout height for all species. Stump height positively influenced sprout height for G. coleosperma and P. angolensis. The study therefore concludes that disturbances are necessary in facilitating sprouting and growth of suppressed shoots. Stump height and diameter influence the ability of stumps to regrow vegetatively through sprouting. Weak relationships between stump diameter/height and coppice density and shoot height suggest that there are other factors that affect vegetative regrowth through coppicing.
Short duration overnight cattle kraaling in natural rangelands: Implications for grass composition, quality, above ground biomass, species diversity and basal cover
(Elsevier, 2021-02-01) Huruba, R.; Mlambo, T.; Mundy, P.J.; Sebata, A.; MacFadyen, D.N.
Short duration overnight cattle kraaling in natural rangelands is an innovative management practice aimed at improving grazing availability. We tested the ability of this practice to alter grass composition in favour of palatable species, increase aboveground grass biomass, species diversity and basal cover using a chronosequence consisting of sites kraaled 6, 12, 24 and 36 months prior to the study and compared them to the surrounding vegetation. We also determined grass quality in terms of fibre content, digestibility and nutrient content [nitrogen (N), phosphorus (P), calcium (Ca), potassium (K) and magnesium (Mg)] 12, 16 and 20 months after kraal use and in surrounding vegetation. Previously kraaled sites had higher proportions of palatable grass species, diversity, N, P, K and Mg than surrounding vegetation. Aboveground grass biomass and basal cover were lower in previously kraaled sites than surrounding vegetation, while grass fibre, digestibility and Ca content did not change with kraaling. These results demonstrate that establishing short duration overnight cattle kraals in natural rangelands improve grazing quality in terms of abundance of palatable grass species and grass nutrient content. However, improved grass quality attracted grazers such as warthogs (Phacochoerus aethiopicus), which reduced grass biomass and basal cover.
Diet and Life-History Traits of Savannah Dwelling Waterbirds in Southern Africa: Implications for Their Conservation Status
(Birds, 2021-04-20) Tarakini, T.; Mabika, I.; Mwedzi, T.; Mundy, P.; Fritz, H.
This study evaluates the relative contribution of reproduction-based life history traits and diet to the population trends in waterbirds from southern Africa. Life history traits (clutch size, incubation period, fledging time, body mass and generation length), diet (prey weight, body lengths and number of taxa represented in its diet (NTD)) and conservation status (declining/not declining) of 163 waterbird species were reviewed. An index of diet generalism was created based on NTD. Cluster analysis was applied on life history traits to define groups of waterbirds. Binomial regressions were used to test if population trends were different across cluster groups and diet variables. Four clusters of waterbirds were defined, with most waterfowl clustering together. Species that feed on small and large prey had higher probabilities of declining (0.17 and 0.26, respectively) compared to those feeding on medium-sized prey (0.08). Amphibians, coleopterans, crustacea, molluscs and tunicates were used by species in all clusters, and the risk of waterbird populations declining further are high given the current dwindling of the prey base. The large proportions of declining species (61%) in waterbirds, which have constrained habitats, calls for continued efforts to mitigate disturbances to wetlands.
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.
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.
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.
Mistletoe-infected trees facilitate invasion of the alien shrub Lantana camara in a semi-arid African savanna
(Elsevier, 2024-07-18) Mlambo, D.; Mundava, J.
The co-occurrence of mistletoes and Lantana camara (hereafter, lantana) is common in southern Africa, yet little is known about how they interact. To fill this gap, we investigated whether mistletoe-infected trees facilitate lantana invasion in a semi-arid southern African savanna. We compared invasibility, native woody plant diversity and soil parameters beneath mistletoe-infected and non-infected trees. We trapped bird droppings beneath mistletoe-infected and non-infected trees and conducted germination experiments to check if they contained viable lantana seeds. Regardless of whether trees were legumes or non-legumes, the subcanopy environments of mistletoe-infected trees had significantly higher invasibility than non-infected trees. The probability of lantana invasion beneath trees increased with mistletoe-infection levels. Soil nutrient concentrations were higher beneath mistletoe-infected trees than non-infected trees. Subcanopy invasibility was positively correlated with soil nutrient concentrations and negatively with native woody plant diversity. We found viable lantana seeds in bird droppings beneath mistletoe-infected trees. Put together, our findings indicate that mistletoes indirectly facilitate lantana invasion by enriching soil nutrients and attracting lantana seed dispersers. Our work provides a rationale for the necessity to simultaneously manage mistletoes and lantana where they cooccur to reduce invasion of the latter.

Browse

Browsing Forest Resources and Wildlife Management Publications Newsletters by Issue Date

Results Per Page

Sort Options