Mopane Research Articles

A lepidopteran (Imbrasia belina) might influence tree-grass balance of Colophospermum mopane savanna

Traditional explanations of tree-grass coexistence in African savannas are based on competition between these growth forms or demographic bottlenecks of trees maintained by fire or mammalian browsers. Perturbation of their “balance” may result in an alternate system state of woody encroachment. Invertebrate herbivory has never been offered as an explanation. We developed a consumer-resource model which illustrated that annual irruptions of a lepidopteran (Imbrasia belina), known as mopane worm, can determine the tree-grass balance of semi-arid Colophospermum mopane savanna in southern Africa. Model performance was sensitive to the abundance, hence mortality, of mopane worms, owing to their complete defoliation of tree leaf biomass resulting in altered competitive relations between trees and grasses. Invertebrate herbivores have been recognized in other systems as agents for effecting a state change of host tree populations; this modeling study offers a first indication of such a role for the well-researched tree-grass relations of African savannas.

English

Patch dieback of Colophospermum mopane (Kirk ex Benth.) Kirk ex J. Leonard, which was attributed to drought, soil surface condition and soil chemistry has been reported in South Africa. In Botswana, dieback of C. mopane and other species were noticed in 2012 in the North east part of the country (North West of Francistown). The causes of the noticed dieback were not known. The objective of this study was to determine the status and causes of that dieback. The study was based on field survey to determine species with dieback, the percentage number of dieback affected individual plants of each species and the areas affected. A questionnaire was also administered to get views from people living in the study area on what they thought caused the dieback. Rainfall and temperature data were obtained from Department of Meteorological Services. It was found that it was not only C. mopane that was affected but even other species such as Dichrostachys cinerea, Combretum hereroense and Terminalia prunioides. It appears that low temperatures combined with soils type are the major causes of the dieback. Dieback was mostly on tree individuals on heavy clay soils than those on loamy soils. Key words: Francistown, plant dieback, vertisols, loamy soils, temperature, rainfall.

Strong competitive effects of African savanna C4 grasses on tree seedlings do not support rooting differentiation

Abstract:Rooting differentiation between established trees and grasses has been well documented in savannas, but it remains unclear to what extent tree-grass rooting differences affect competition between newly established seedlings and grasses. To examine this question, a greenhouse experiment was conducted at the University of Missouri, USA. Twenty 3-mo-old seedlings each of two African savanna tree species (Acacia nigrescens and Colophospermum mopane) were grown for 8 mo with two crossed factors: grass competition and irrigation depth. Strong negative effects of grass competition on final seedling biomass and leaf photosynthetic and stomatal conductance occurred in both tree species, but no effects of irrigation depth were detected. There was a clear tree species by grass competition interaction, suggesting interspecific variation in competitive response. The results emphasize the importance of below-ground competition with grasses for physiological and morphological responses of tree seedlings, while minimizing the importance of tree-grass rooting depth differences as a factor in modulating the competitive response of trees to grasses at the seedling stage.

Characterization of the Primary Metabolome of Brachystegia boehmii and Colophospermum mopane under Different Fire Regimes in Miombo and Mopane African Woodlands.

Miombo and Mopane are ecological and economic important woodlands from Africa, highly affected by a combination of climate change factors, and anthropogenic fires. Although most species of these ecosystems are fire tolerant, the mechanisms that lead to adaptive responses (metabolic reconfiguration) are unknown. In this context, the aim of this study was to characterize the primary metabolite composition of typical legume trees from these ecosystems, namely, Brachystegia boehmii (Miombo) and Colophospermum mopane (Mopane) subjected to different fire regimes. Fresh leaves from each species were collected in management units and landscapes across varied fire frequencies in the Niassa National Reserve (NNR) and Limpopo National Park (LNP) in Mozambique. Primary metabolites were extracted and analyzed with a well-established gas chromatography time-of-flight mass spectrometry metabolomics platform (GC-TOF-MS). In B. boehmii, 39 primary metabolites were identified from which seven amino acids, two organic acids and two sugars increased significantly, whereas in C. mopane, 41 primary metabolites were identified from which eight amino acids, one sugar and two organic acids significantly increased with increasing fire frequency. The observed changes in the pool of metabolites of C. mopane might be related to high glycolytic and tricarboxylic acid (TCA) rate, which provided increased levels of amino acids and energy yield. In B. boehmii, the high levels of amino acids might be due to inhibition of protein biosynthesis. The osmoprotectant and reactive oxygen species (ROS) scavenging properties of accumulated metabolites in parallel with a high-energy yield might support plants survival under fire stress.

Adaptation of Colophospermum mopane to extra-seasonal drought conditions: site-vegetation relations in dry-deciduous forests of Zambezi region (Namibia)

BackgroundThe drought-tolerant tree species Colophospermum mopane is focussed at for an assessment of the impact of water stress, as well as for the specific adaptation potential of the species. Three differing sites (‘Forest’, ‘Shrubs’ and ‘Swamp’) under three different seasonal situations (advanced dry season, drought and early rain season), in the mopane woodland of north-eastern Namibia were studied.MethodsPlant water potentials were measured using a pressure chamber in the field. Pre-dawn water potentials were assessed to reflect the soil water potential of the rhizosphere. Midday water potentials were measured to assess the strongest negative water potential by the sample trees.ResultsThe study reveals significant differences of the water potentials indicated by C. mopane. The different site-vegetation relations specify the impacts of seasonal conditions and site conditions (soil parameters and soil water availability) on the selected species.ConclusionsThe investigation reveals a specific adaptation potential of C. mopane in relation to different soil parameter under seasonal conditions. The impact of the different seasons on the pre-dawn plant water potential (indicating actual soil water availability) was assessed independently of other parameters. The adaptation range of C. mopane is obviously reflected by its ability to cope with water stress situations by midday samples. An advantage of using plant-physiological characteristics as monitoring parameters is the circumstance that these reflect the plant-internal ‘digestibility’ of the evaluated conditions directly on the natural stand. In this consideration, the evaluation of specific site conditions referring to the plant-effective water deficiency and the plant-internal, physiological ability of adaptation towards these, are recommended as key-parameters, for, e.g., investigations of site-species matching for afforestation or reforestation management.

Effect of Lopping and Root Barrier on Pasture Production in Colophospermum mopane Based Silvipastoral System in Western Rajasthan

Effect of Lopping and Root Barrier on Pasture Production in Colophospermum mopane Based Silvipastoral System in Western Rajasthan

Exploring survival strategies of African Savanna trees by partial ordering techniques

The resilience of savanna ecosystems to climate and land-use changes is an important ecological and management question. The term ‘resilience’ is used to refer to the ability of a tree species to survive in a specific location, even under changing environmental conditions. In this study, vectors of functional traits of selected savanna tree species are studied by applying partial order algorithms to them. Some ecological interpretations are obtained and are compared to published research. One finding is the high rates of nitrogen fixation for the leaves of Acacia nigrescens. In opposition to this well-known fact, we discovered that Sclerocarya birrea has a bigger average leaf area than the other four tree species. Additionally, we found high carbonate values within the leaf from Colophospermum mopane, Combretum apiculatum, and Terminalis sericea. These results correspond to different ecological strategies for the tree species in question. It became obvious that geometric structures gained from partial ordering show a very good correspondence to ecological strategies of these tree species. Concepts of partial order theory may therefore be helpful in ecosystem research.

Temporal determinants of human–elephant conflict in Victoria Falls

This study established the temporal determinants of human-elephant conflict in Victoria Falls town, Hwange West communal area and the resettlement areas of Don Rovin, Mubiya and Kalala. Interviews were the main instruments adopted for the study. Results indicate that, elephants which cause conflict in Hwange communal areas come from the Fuller forest concession area. During the cropping season elephants come to this area to raid food crops. The elephants stay in the Fuller forest during the day. As night falls elephants wait until it gets dark, then enter human settlements where they cause different human-elephant conflict manifestations. During the day, elephants seek refuge in the protected areas where they avoid contact with people. People in the area sleep in fields guarding crops to prevent elephants raids. During the dry season elephants come to drink water from the perrenial streams in the Hwange communal area. The riparian vegatation and fruits in the perrernial streams also attract elephants to the communal areas. Elephants are attracted to these areas during the dry season by the availability food and water. The perrenials streams sustain fruits such as savanna dwala berry, monkey finger and wild medra. Mopane and acacia vegetation which is elephants's favourite also attract elephants to this area during the dry season. The bark of mopane trees is eaten by elephants during the dry season. Elephants opportunistically raid crops from fields at the fringes of rivers when they enter the settlements. Some elephants also hide in the forest remnants and attack people during the night. It is therefore recommended that there is need for participation of all stakeholders such as scientists, elephant managers, policy makers and local communities in addressing the issues of human-elephant conflict effectively.

Population genomics and the evolution of virulence in the fungal pathogen Cryptococcus neoformans.

Cryptococcus neoformans is an opportunistic fungal pathogen that causes approximately 625,000 deaths per year from nervous system infections. Here, we leveraged a unique, genetically diverse population of C. neoformans from sub-Saharan Africa, commonly isolated from mopane trees, to determine how selective pressures in the environment coincidentally adapted C. neoformans for human virulence. Genome sequencing and phylogenetic analysis of 387 isolates, representing the global VNI and African VNB lineages, highlighted a deep, nonrecombining split in VNB (herein, VNBI and VNBII). VNBII was enriched for clinical samples relative to VNBI, while phenotypic profiling of 183 isolates demonstrated that VNBI isolates were significantly more resistant to oxidative stress and more heavily melanized than VNBII isolates. Lack of melanization in both lineages was associated with loss-of-function mutations in the BZP4 transcription factor. A genome-wide association study across all VNB isolates revealed sequence differences between clinical and environmental isolates in virulence factors and stress response genes. Inositol transporters and catabolism genes, which process sugars present in plants and the human nervous system, were identified as targets of selection in all three lineages. Further phylogenetic and population genomic analyses revealed extensive loss of genetic diversity in VNBI, suggestive of a history of population bottlenecks, along with unique evolutionary trajectories for mating type loci. These data highlight the complex evolutionary interplay between adaptation to natural environments and opportunistic infections, and that selection on specific pathways may predispose isolates to human virulence.

Effects of pruning on the concentration of trace elements in Colophospermum mopane leaves

AbstractDespite the nutritional value of Colophospermum mopane to browser's diets, there is still insufficient knowledge on the effect of browsers on concentrations of these trace elements. A field experiment was conducted in Musina Nature Reserve, Limpopo Province, South Africa, to determine the effect of pruning on the concentration of trace elements in mopane leaves. Samples were analysed for iron (Fe), manganese (Mn), boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), cobalt (Co), fluoride (F) and selenium (Se) using the inductively coupled plasma atomic emission spectrometry technique. The effect of pruning was tested using the two‐tailed t‐test: two‐sample assuming equal variance and two‐tailed Mann–Whitney U‐test. Results showed that the concentration of trace elements in the control and pruned trees varies slightly through the year. Fe, Mn, Mo, Cu, Zn and Se are higher during leaf flush, but declined as the leaves matured and aged. This study concluded that simulated browsing had no significant effect on the concentration of trace elements in the mopane leaves. Seasonal variation in the amount of trace elements has implications on the distribution of browsers in the mopane woodland.

Field efficacy of hermetic and other maize grain storage options under smallholder farmer management

Household grain storage continues to be of paramount importance in improving food security in sub-Saharan Africa (SSA) where maize post-harvest losses of 10–20% are reported. On-farm trials to compare alternative solutions for reducing household maize storage losses were conducted in the 2014/15 and 2015/16 storage seasons in two contrasting agro-ecological zones in the Hwedza district of Zimbabwe. A wide range of treatments including a commercial synthetic pesticide composed of fenitrothion 1% and deltamethrin 0.13%, unregistered but commonly used botanical pesticides (Aloe ash, Colophospermum mopane leaves, Eleusine coracana (rapoko) chaff, and Ocimum gratissimum), hermetic storage facilities (metal silos, GrainPro Super Grain Bags (SGB) IVR™, Purdue Improved Crop Storage (PICS) bags), and storage bags with deltamethrin incorporated into their fabric, were evaluated. The results demonstrated the superiority of hermetic storage facilities (PICS bags, SGBs, and metal silos) in suppressing insect pest build-up, insect grain damage and weight loss in stored maize grain. A newly introduced synthetic pesticide on the Zimbabwean market which has pirimiphos-methyl 1.6% and thiamethoxam 0.36% was also evaluated in the 2015/16 season and was found to be highly effective. The following grain storage technologies: hermetic metal silos, SGB bags, PICS bags, and the pesticide pirimiphos-methyl 1.6% and thiamethoxam 0.36% are therefore recommended for smallholder farmer use to reduce stored grain losses due to insect pests.

Plants promote mating and dispersal of the human pathogenic fungus Cryptococcus.

Infections due to Cryptococcus are a leading cause of fungal infections worldwide and are acquired as a result of environmental exposure to desiccated yeast or spores. The ability of Cryptococcus to grow, mate, and produce infectious propagules in association with plants is important for the maintenance of the genetic diversity and virulence factors important for infection of animals and humans. In the Western United States and Canada, Cryptococcus has been associated with conifers and tree species other than Eucalyptus; however, to date Cryptococcus has only been studied on live Arabidopsis thaliana, Eucalyptus sp., and Terminalia catappa (almond) seedlings. Previous research has demonstrated the ability of Cryptococcus to colonize live plants, leaves, and vasculature. We investigated the ability of Cryptococcus to grow on live seedlings of the angiosperms, A. thaliana, Eucalyptus camaldulensis, Colophospermum mopane, and the gymnosperms, Pseudotsuga menziesii (Douglas fir), and Tsuga heterophylla (Western hemlock). We observed a broad-range ability of Cryptococcus to colonize both traditional infection models as well as newly tested conifer species. Furthermore, C. neoformans, C. deneoformans, C. gattii (VGI), C. deuterogattii (VGII) and C. bacillisporus (VGIII) were able to colonize live plant leaves and needles but also undergo filamentation and mating on agar seeded with plant materials or in saprobic association with dead plant materials. The ability of Cryptococcus to grow and undergo filamentation and reproduction in saprobic association with both angiosperms and gymnosperms highlights an important role of plant debris in the sexual cycle and exposure to infectious propagules. This study highlights the broad importance of plants (and plant debris) as the ecological niche and reservoirs of infectious propagules of Cryptococcus in the environment.

English

Plants with diverse therapeutic properties are indigenous to Namibia. Concoctions of Colophospermum mopane and Acrotome inflata are widely used traditionally in the management of respiratory, gastrointestinal and wound infections. Limited studies have validated these traditional uses particularly against resistant bacteria strains such as Pseudomonas spp. This study aimed to determine the antimicrobial activity and phytochemistry of extracts of C. mopane and A. inflata, medicinal plants indigenous to Namibia. Phytochemical analysis and antimicrobial testing were done on leaves and barks of C. mopane and A. inflata whole plant. Voucher specimens were collected from Omugulugoonime village, Oshikoto region and validated at the National Botanical Research institute, Windhoek. Crude extraction of dried plants was done by maceration with ethanolic and aqueous solvents. Phytochemical screening was done using methods described by Harborne (1998) and/or Tiwari et al (2011). The antimicrobial activity against wild types of Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtillis and Candida albicans was done using the disc-agar-diffusion method. The mean diameters of the zones of inhibition (mm) for each extract were determined against each test organism. The antimicrobial activity (zones of inhibition) of ethanolic extracts (5 mg/ml) of C. mopane bark (10±0.6 mm) and leaves (10±1.2 mm) and A. inflata (8.7±0.6 mm) against P. aeruginosa is comparable to that of penicillin G (14±1.4 mm). Aqueous extracts leaves and bark of C. mopane showed activity against P. aeruginosa and S. aureus. The activity of the ethanolic extracts against B subtillis was: C. mopane leaves (7.3±0.6 mm), C. mopane bark (8.7±0.6 mm) and A. inflata (11.3±3.21 mm) and Penicillin G (26±1.4 mm). Both ethanolic and aqueous extracts did not have activity on C. albicans. Aqeous extracts of A. inflata had no activity on Pseudomonas and B. subtillis. Organic extracts of Colophospermum mopane and A. inflata exhibit antimicrobial potential against Pseudomonas and Bacillus species.  The alkaloids, flavonoids and tannins should be further purified and characterized for antipseudomonal activity. Key words: Antipseudomonal, Namibia, Colophospermum mopane, Acrotome inflate.

Antibacterial activity of aqueous and methanol extracts of selected species used in livestock health management

Context: Salvadora persica L. (Salvadoraceae), Colophospermum mopane (J.Kirk ex Benth.) J. Léonard (Leguminosae) and Dichrostachys cinerea (L.) Wight & Arn. (Leguminosae) crude extracts are used by local farmers against many livestock infections with little or no side effects usually associated with synthetic antimicrobials. However, their efficacy has rarely been tested.Objective: These plants were tested for potential antibacterial activity against clinical isolates of Staphylococcus aureus ATCC33862 and Escherichia coli ATCC25922. Minimal inhibitory concentrations (MIC) of the crude plant extracts were determined.Materials and methods: Aqueous and methanol extraction of 100 g each of the bark of C. mopane, roots of D. cinerea and leaves of S. persica was done by placing the samples in 250 mL of either water or methanol. Nutrient broth was used as growth medium for the bacteria, and McFarland standard for bacterial standardization. 2,3,5-Triphenyltetrazoliumchloride (TTC) was the indicator salt. Each of the aqueous and methanol extracts (100 μL) was tested. Gentamycin and ampicillin were the controls.Results: MIC of aqueous extracts ranged from 1.03–14.6 mg/mL against S. aureus, and from 12.1–34.3 mg/mL against E. coli. Methanol extracts ranged between 5.31 and 9.64 mg/mL against S. aureus, and between 7.86 and 13.6 mg/mL against E. coli. Aqueous and methanol extracts of S. persica were significantly higher (p < 0.05) than C. mopane and D. cinerea.Discussion and conclusion: Colophospermum mopane, S. persica and D. cinerea exhibited antibacterial activity, with methanol extracts performing better than aqueous extracts, justifying use as ethnoveterinary medicine. Further study to isolate the active components should be pursued.

Influence of Soil Drainage and Elephant (Loxodonta africana) Damage on Abundance and Structure of Colophospermum mopane in Central Mana Pools National Park Zimbabwe

A study on the influence of soil drainage and elephant damage on the abundance and structure of Colophospermum mopane was carried out in Central Mana Pools National Park (MPNP) Zimbabwe. Data were collected in April- May 2013. The stratified random sampling method was employed. The study area was stratified according to soil drainage. Three strata were established namely; well drained, moderately drained and poorly drained soils. Ten plots were sampled in each strata and a total of 30 plots were sampled to determine the abundance and structure of C. mopane in Central MPNP. Results from One way ANOVA showed significant differences in tree height, basal area, tree canopy volume, shrub canopy volume, sapling density, tree density, number of stems per tree and damaged trees density (PA‹Â‚0.05). There was no significant difference in the number of dead trees across the three strata (PA‹Âƒ0.05). Moderately drained soil had the highest number of undamaged trees (n=91; 42%), saplings and stems per tree. Well drained soils had the highest number of damaged live trees (n=112; 51%) and poorly drained soils had the highest number of dead trees (n=60; 51%). There were significant differences in damage (PA‹Â‚0.001). Regression analysis showed a negative relationship between elephant density and damaged trees density (R2=0.03; PA‹Âƒ0.05), however, there was a positive relationship between elephant density and dead trees (R2=0.3865; PA‹Â‚0.05). Results from this study suggest that soil properties as well as elephant damage have an influence on the abundance and structure of C. mopane, therefore the need for constant monitoring of this tree species.

Demography of woody species in a semi-arid African savanna reserve following the re-introduction of elephants

The hypothesis that African elephants may cause the local extirpation of selected woody species was evaluated in a medium-sized, semi-arid reserve following their reintroduction at low density. Mortality, state-change, and regeneration of 25 tree and 17 shrub species were studied between 1997 and 2010. Annual mortality of shrub species ranged from 0.2 to 8.0%, with six species experiencing 6–8%. Eight shrub species lost more than half their adult population (range 10–94%). Annual tree mortality ranged from 0.2 to 10.5%. The two dominant dryland tree species experienced <1% annual mortality, 18 species lost more than half their tree population, and one was eliminated. Elephants accounted for >63% and stress-related agents >20% of tree deaths. The manner in which elephants induced tree death depended on species. The proportion of individuals of a species killed by pollarding or uprooting ranged from 0 to 74%, and by debarking from 0 to 100%. Complete uprooting was a common cause of death for three shrub species. Regeneration ranged from zero for six tree and one shrub species to a seedling every 7 m2 for Colophospermum mopane and 23 m2 for Dichrostachys cinerea in riparian habitat. Three shrub and eight tree species were identified as vulnerable to local extirpation owing to a combination of high mortality and poor regeneration that is likely to result in a considerably simplified system. Reintroduction of elephants into medium-sized reserves without regulation of their numbers may not be a desirable action.

Enhancing forage production through a silvi-pastoral system in an arid environment

A study was undertaken at Jodhpur during the years 2001–2011 to assess the production potential of Cenchrus ciliaris L., Lasiurus sindicus Henr. and Vigna unguiculata L. (cowpea) sown in strips with Colophospermum mopane Kirk ex Benth. and Hardwickia binata Roxb. tree stands without and with fertilizer application. Results indicated that the plant growth and survival percentage of C. mopane was higher than that of H. binata. Growth of C. mopane plants was affected by different cropping systems and fertilizer treatments during the initial phase but later on the effect was not significant. Green and dry forage yields were influenced by the cropping systems, i.e., 2.09 t ha−1 with L. sindicus followed by 1.9 t ha−1 dry forage yield in a sole strip of C. ciliaris, which was significantly higher than the strip cropping of cowpea with respective grasses. However, the sustainable yield index was higher with C. ciliaris (0.52) followed by L. sindicus (0.38). The average data revealed that the protein yield was higher in L. sindicus + cowpea and C. ciliaris + cowpea inter-cropping as compared to the respective sole strip of Cenchrus ciliaris and L. sindicus. Application of 40 kg N ha−1 increased dry fodder yields by 15 % over the control, and crude protein also increased by 22.37 %. Water use efficiency of grasses increased with nitrogen application. Maximum water use efficiency (9.8 kg dry matter ha−1 mm−1) was recorded in L. sindicus with 40 kg N ha−1 mm−1 application followed by C. ciliaris (8.8 kg dry matter ha−1 mm−1). The system productivity varied with different tree species and inter-cropping. Among tree species, the system productivity was higher with H. binata than with C. mopane. Leaves of H. binata were more palatable and preferred by goats than C. mopane. For obtaining higher productivity of quality fodder, inter-cropping of grasses with legumes in association with H. binata appears to be a highly suitable proposition for a silvi-pastoral system in an arid environment.

Comparative performance of four survey methods for assessing Lilian’s Lovebird abundance in Liwonde National Park, Malawi

Monitoring abundance of threatened species is important for conservation planning. Lilian’s Lovebird Agapornis lilianae is a near-threatened small parrot found in mopane Colophospermum mopane woodland. Its population has not been investigated in any part of its range. We investigated the abundance and density of the Lilian’s Lovebird in Liwonde National Park, Malawi. Both distance sampling (line and point transects) methods and total counts (waterhole and flyway counts) were applied. The point count method gave very low numbers and was discontinued after the first year. Line transects conducted during the wet season had the highest density estimates of 17 ± 4.8 lovebirds km−2 of mopane woodland. However, number of observations per transect in each year were low. Waterhole counts had the lowest density estimates (10 ± 3.5 lovebirds km−2). Flyway counts gave an intermediate estimate (13 ± 3.0 lovebirds km−2). The total population of Lilian’s Lovebirds in Liwonde National Park is therefore estimated to be about 4 000 individuals. The use of line transect counts at the end of the rainy season is recommended for continued monitoring of Lilian’s Lovebirds abundance in Liwonde National Park.

Tragelaphus strepsiceros Browse During the Wet Season in the Mopani Veld of Limpopo Province, South Africa

Tragelaphus strepsiceros (greater kudu) has adapted to the harsh conditions of southern Africa’s mopani woodland. However, there is still limited information on the diet composition and selection of browse by greater kudu, particularly during the wet season. This poses a challenge to manage these ungulates effectively within their habitat. The study used rumen content to quantify the diet composition of greater kudu during the wet season. The study was conducted at the Sandown Game Farm, Limpopo Province, South Africa. Rumen samples were collected from four adult female and four adult male greater kudu culled in March 2015 and statistically analyzed using the t-test: paired two sample for means and Pearson’s correlation coefficient analysis. Findings show that Combretum apiculatum contributed most (43%) to the diet of greater kudu during the wet season. Other browse plant species were Sclerocarya birrea (24%), Colophospermum mopane (12%), and Acacia nigrescens (8%), with the contribution of the remaining species to the diet being insignificant. Leaves were the plant parts browsed most often and contributed 81% to the diet during this season. The remaining 19% of the diet consisted mainly of S. birrea fruit. Gender differences in diet selection were observed. The diet of female greater kudu consisted mainly of C. apiculatum (44%) and C. mopane (20%), while the diet of male greater kudu mostly contained S. birrea (38%) and C. apiculatum (34%). Implications for the management and conservation of greater kudu in mopani veld are discussed.

Savanna Tree Seedlings are Physiologically Tolerant to Nighttime Freeze Events.

Freeze events can be important disturbances in savanna ecosystems, yet the interactive effect of freezing with other environmental drivers on plant functioning is unknown. Here, we investigated physiological responses of South African tree seedlings to interactions of water availability and freezing temperatures. We grew widely distributed South African tree species (Colophospermum mopane, Combretum apiculatum, Acacia nigrescens, and Cassia abbreviata) under well-watered and water-limited conditions and exposed individuals to nighttime freeze events. Of the four species studied here, C. mopane was the most tolerant of lower water availability. However, all species were similarly tolerant to nighttime freezing and recovered within one week following the last freezing event. We also show that water limitation somewhat increased freezing tolerance in one of the species (C. mopane). Therefore, water limitation, but not freezing temperatures, may restrict the distribution of these species, although the interactions of these stressors may have species-specific impacts on plant physiology. Ultimately, we show that unique physiologies can exist among dominant species within communities and that combined stresses may play a currently unidentified role in driving the function of certain species within southern Africa.