Forest Resources and Wildlife Management Publications Newsletters
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- ItemComparability 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.
- ItemMistletoe-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.
- ItemShort 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.
- ItemIn 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.
- ItemEffects 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.