Forest Resources and Wildlife Management Publications

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Forest Resources and Wildlife Management Publications

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    Functional and species composition of understory plants varies with mistletoe-infection on Vachellia karroo trees in a semi-arid African savanna
    (Elsevier, 2021-10-27) Maponga, T.S.; Ndagurwa, H.G.T.; Witkowski, E.T.
    In savanna ecosystems, tree canopy patches differ in plant species composition compared to adjacent intercanopy spaces due to different levels of resource availabilities. Mistletoes further augment nutrients underneath tree canopies whilst reducing their hosts’ competitive edge, thus providing more resources and creating patches that support higher understory species richness. However, little is known on how understory species and functional trait assemblages, in both canopy and intercanopy spaces, are affected by varying overstory mistletoe infection intensities. This study investigated how functional and species diversity/composition varied within and between canopy patches and intercanopy spaces of high- and low mistletoe-infected Vachellia karroo trees. The affinity of individual species to the different canopy patches and intercanopy spaces was also assessed. Microhabitats had significantly different species compositions. A higher proportion of species (34%) showed a strong positive affinity towards canopy patches whilst intercanopy spaces were strongly associated with only 9% of recorded species, indicating greater dominance of some species there. Generally, subcanopy patches had significantly higher species richness and diversity, and functional diversity, compared to adjacent intercanopy spaces. These variables increased with increasing mistletoe infection, thus grass, forb and tree species diversity were 17–43% higher, and functional diversity indices were 0.5–28% greater in high- compared to low mistletoe-infection canopy patches. Furthermore, species richness and diversity of C3, C4, annual and perennial plants were 1.27–3.13-fold higher within canopy patches compared to intercanopy spaces and 1.28–1.74-fold greater within high- compared to low mistletoe-infection microhabitats. Consequently, high mistletoe-infection canopy patches had between 1.08 and 3.76-fold greater species richness and diversity of C3, C4, annual and perennial plants compared to the other three microhabitats. Our findings suggest that by enhancing spatial heterogeneity, variations in mistletoe infection facilitate biodiversity and to a lesser extent vegetation structural diversity in these semi-arid savannas.
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    An assessment of the impact of the 2014 US elephant trophy importation ban on the hunting patterns in Matetsi Hunting Complex, north-west Zimbabwe
    (Elsevier, 2021-08-16) Nyamayedenga, S.; Mashapa, C.; Chateya, R.J.; Gandiwa, E.
    This study assessed the influence of a 2014 United States of America (USA) imposed ban on the importation of elephant (Loxodonta africana) hunted trophies from Zimbabwe on the hunting patterns (i.e., elephant quota allocation, utilisation and hunter’s or client country of origin dynamics) in Matetsi Hunting Complex. The study was divided into two period, i.e., pre- ban (2008–2013) and post-ban (2014–2017). Although the study results showed a non-significant quota allocation variation difference between the pre-ban and post-ban periods, there was however, a significant decline in quota utilisation in post-ban period compared to the pre-ban period. Accordingly, a significant decline in US hunters or clients was recorded in the post-ban period. It is concluded that trophy hunting and trade bans by some global north countries without an alternative global conservation framework that provides conservation incentives will likely reverse the gains in wildlife conservation and rural development in some global south countries where sustainable utilisation is an integral part of the wildlife conservation practice.
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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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    Within-plant variation in defences in response to simulated herbivory in a semi-arid southern African savannah
    (John Wiley & Sons Ltd, 2015) Sebata, A.; Ndlovu, L.R.
    Within-plant spatial variation in herbivore pressure can induce localized antiherbivory defence responses. We tested this hypothesis by studying branch-specific responses of Acacia robusta, Dichrostachys cinerea and Ziziphus mucronata to simulated mammalian herbivory. Herbivory was simulated by clipping the terminal shoots (3 cm from tip) of tree branchlets, allowing them one year of regrowth and then comparing their spine length and density and condensed tannins with those of adjacent unclipped branchlets. Condensed tannins concentrations were higher in clipped branchlets than in unclipped branchlets in all three woody species (P < 0.05). Spine length was higher in clipped branchlets than in unclipped branchlets in A. robusta (P < 0.05) but was similar in both D. cinerea and Z. mucronata (P > 0.05). Spine density was double in clipped branchlets as compared to the unclipped branchlets in Z. mucronata (P < 0.05) but was similar in both A. robusta and D. cinerea (P > 0.05). We found evidence of within-plant variation in condensed tannins concentration and spine length and density in response to simulated herbivory in the three woody species.
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    Effect of leaf size, thorn density and leaf accessibility on instantaneous intake rates of five woody species browsed by Matebele goats (Capra hircus L) in a semi-arid savanna, Zimbabwe
    (Elsevier, 2010) Sebata, A.; Ndlovu, L.R.
    Browse instantaneous intake rate (IIR) is a product of bite size and bite rate which are constrained by plant morphology. We studied the effects of leaf size, thorn density and leaf accessibility on the IIRs of five browse species in semi-arid savanna over three leaf phenophases using cafeteria-style trials. Bite size was influenced by leaf size and bite rate by leaf accessibility, while thorn density had an impact on both bite size and bite rate. The lowest IIRs were recorded on the small leafed Acacia tortilis which also had the highest thorn density. Dichrostachys cinerea had the highest IIRs due to the large bite sizes. Although Terminalia prunioides and Commiphora pyracanthoides had small leaves, their arrangements in clusters allowed for higher IIRs, which were comparable to those of the large leafed D. cinerea. Instantaneous intake rate showed no clear trend in relation to leaf phenophase, although at early leaf the goats cropped smaller bites because of the small size of the newly sprouting leaves. We conclude that leaf size influenced IIRs through bite size, leaf accessibility through bite rate and thorn density through both bite size and bite rate.