Abstract: Australian acacias have spread to many parts of the world. In South Africa, species such as A. mearnsii and dealbata are invasive. Consequently, more effort has focused on their clearing. In a context of increasing clearing costs, it is crucial to develop innovative ways of managing invasions. Our aim was to understand the biophysical properties of A. mearnsii in grasslands as they relate to grass production and to explore management implications. Aboveground biomass (AGB) of A. mearnsii was determined using a published allometric equation in invaded grasslands of the northern Eastern Cape, South Africa. The relationships among the A. mearnsii leaf area index (LAI), normalised difference vegetation index (NDVI) and AGB were investigated. The influence of A. mearnsii LAI and terrain slope on grass cover was also investigated. Strong linear relationships between NDVI, LAI and AGB were developed. Acacia mearnsii canopy adversely impacted grass production more than terrain slope (p < 0.05) and when LAI approa...

Abstract: The objective of this study was to examine the factors influencing smallholder producers’ potential to sell cattle and identify marketing opportunities for sustainable beef production in South Africa. A total of 95 structured questionnaires was administered to the Ncorha and Gxwalibomvu communities in the Eastern Cape province of South Africa. Average cattle herd size per household was higher (P 5%) were mentioned as potential strategies for improving commercial marketing of cattle in the studied areas. Most producers (70%) indicated their potential and willingness to participate in develop...

Abstract: (2016). Carbon Accounting and Savanna Fire Management. African Journal of Range & Forage Science: Vol. 33, No. 3, pp. 215-216.

Abstract: The Nama-Karoo is the largest of the three biomes that comprise the semi-arid Karoo-Namib ecoregion of southern Africa. Large tracts of Nama-Karoo rangeland have been invaded by alien leguminous trees of the genus Prosopis. We assessed the impact of Prosopis invasion and clearing on vegetation cover in heavily grazed Nama-Karoo rangeland on two sheep farms in the Beaufort West district of the Western Cape province of South Africa. Our results suggest that, below critical threshold cover levels, Prosopis trees do not affect indigenous vegetation and add to overall rangeland vegetation cover. However, once Prosopis cover exceeds critical thresholds, the trees begin to negatively impact on indigenous vegetation (especially grasses) and overall vegetation cover. In addition, our data suggest that vegetation cover recovers after Prosopis clearing, being temporarily higher than pre-invasion levels possibly as a result of enhanced post-invasion soil fertility. Lastly, our results suggest that Prosopis trees redu...

Abstract: Fire products have been widely identified as germination cues for a number of species from both fire-prone and fire-free ecosystems. However, there is uncertainty about the effects of fire products on seed germination of semi-arid rangeland species. We examined the germination of seven dominant species from Central Zagros rangelands in the semi-arid region of Iran under various heat shock (60, 80 and 120 °C), aerosol smoke, ash and control treatments. Our findings showed that fire products could enhance, inhibit or not affect the seed germination of rangeland species in this area. The germination percentage of Astragalus adscendens increased following 60 °C heat treatment in comparison with the control. The germination of Astragalus verus, Bromus tectorum, B. tomentellus and Phlomis olivieri were increased significantly using smoke treatment (P < 0.0001). The seed germination of B. tomentellus and B. tectorum was promoted by ash treatment, whereas the other species exhibited no response or were inhibited by fire products. In addition, smoke treatment shortened the overall germination time of B. tectorum. These findings suggest that fire products affect the germination of several species and can serve as potential tools for understanding the vegetation dynamics and restoration of disturbed semi-arid rangelands.Keywords: aerosol smoke, fire products, restoration, seed dormancy, vegetation dynamics

Abstract: Among a vast number of forage trees, Vachellia karroo (Acacia karroo) remains one of the most widely distributed indigenous plant legumes in Southern Africa. The plant possesses some striking attributes, such as rapid growth rate, drought tolerance, adaptation to alkaline and acidic sterile soils, and resistance to a variety of edaphic and temperature changes. In past years V. karroo was recognised to be a major threat to rangeland productivity owing to its invasive nature. Research interest has shifted from its eradication as an unwanted plant to its utilisation as a feed resource for livestock. Extensive utilisation of V. karroo is mainly hindered by the presence of tannins and spines. Prospects to lessen the adverse effects of the anti-nutritional influences are now recognised. Vachellia karroo possesses desirable fatty acid profiles, and high protein and mineral contents that can improve animal performance. Presently, the use of V. karroo for goat production in communal areas is restricted owing to li...

Abstract: Book Title: Fynbos Ecology and Management Book Authors: Karen J Esler, Shirley M Pierce and Charl de Villiers (Eds.) 2014, Briza Publications, 121 Soutpansberg Road, Pretoria, South Africa. 262 pages, softcover. ISBN 978-1-920217-37-2. Price R250

Abstract: Woody plant encroachment is increasing in arid and semi-arid regions of the world. We investigated the structure and fine-scale spatial pattern of encroaching species and how these patterns vary with different grazing regimes in semi-arid regions. In this study, we investigated how four encroaching shrub species (Searsia erosa, S. burchellii, Diospyros lycioides and Eriocephalus ericoides) in Middelburg (Eastern Cape, South Africa) coexist and partition space under different grazing regimes (viz. continuous rest, and continuous, summer and winter grazing). We used point-pattern analysis to assess the spatial ecology of these species. We also used an index of integration (mingling index), where low values indicate that they are surrounded by conspecifics and high values indicate that they are surrounded by heterospecifics. The three shrub species were highly mingled except in the winter-grazing plot, where S. burchellii and D. lycioides clustered. We found that the shrub species were generally aggregated i...

Abstract: Beef traders’ and consumers’ perceptions on the development of a natural pasture-fed beef (NPB) brand by smallholder cattle producers were investigated. In total, 18 meat traders (five abattoirs and 13 beef retailers) and 155 beef consumers were interviewed using structured questionnaires. All meat traders had the potential but were not willing to support the development of a NPB brand citing smallholder farmers’ limited ability to supply sufficient volumes of high-quality cattle. Consumers (81%) were prepared to purchase NPB upon availability on the market but were not willing (80%) to pay a brand premium. Logistic regression model results showed that consumers’ willingness to buy NPB and pay a premium were influenced (P < 0.05) by gender, household size, income source, meat preference, meat consumption frequency, money spent on beef, frequency of beef purchases and consumption. Overall, beef traders and consumers held positive impressions regarding the development of a NPB brand by smallholder cattle pr...

Abstract: Following a field campaign to determine the species composition, canopy cover, aboveground annual production and leaf area index (LAI) of the semi-arid savanna of north-western Namibia, we present a production model that can be used by graziers to determine the livestock carrying capacity The model predicts the annual aboveground net primary production (ANPP) from regression equations of canopy cover by annual production fraction for plant functional classes We tested the output of the model against another fully independent net primary production (NPP) model, namely the MODIS NPP product The mean MODIS NPP for the 29 sites was 343 ± 22 kg dry matter (DM) ha−1 y−1 as opposed to 285 ± 142 kg DM ha−1 y−1 for the fAP model that used the regression method (p < 001) As a proof of concept, these landscape-scale ANPP values are used to calculate a recommended livestock carrying capacity for the Ehirovipuka Communal Conservancy, a 1 980 km2 communal area with both wildlife and livestock populations In addit

Abstract: The effect of replacing commercial supplements with isoenergetic and isonitrogenous velvet bean-, cowpeaand lablab-based supplements on milk yield, milk quality and economic returns in smallholder crossbred dairy cows was investigated in the 2013 and 2014 dry seasons. Using 3 × 3 Latin square designs, nine multiparous Red Dane, Guernsey and Holstein-Friesian crosses in mid-lactation (130 ± 19 d) were offered forage legume-based supplements for 63 d at 0.5 kg per litre of milk produced. Milk quantity and quality were significantly (P < 0.05) different among supplements in both seasons. Cows fed commercial supplements had higher milk yield than cows fed forage legume supplements. Milk fat content was significantly (p < 0.05) higher in cows fed lablab-based supplements than cows fed other supplements. Milk protein, total solids and lactose content of cows fed commercial supplements was significantly (p < 0.05) higher than those fed forage legume-based supplements, although protein content was similar to cows...

Abstract: There is a dearth of knowledge on the effects of annual burning of fire-breaks on species composition, plant diversity and soil properties. Whittaker’s plant diversity technique was used to gather data on species composition and diversity in four grassland communities on the Loskop Dam Nature Reserve (LDNR). The study demonstrated that fire-beaks did not have a negative effect on plant diversity and an increase was even noted in various diversity parameters in the grassland on abandoned cropland. Fire-breaks were changing the species composition, as three of the four communities illustrated a clear separation in species composition between fire-break and unburnt plots. There was not a strong association between specific species and the fire-break or unburnt plots, except for Themeda triandra and Tristachya leucothrix, known for their association with and without fire, respectively. The change in species composition was not negatively affecting range condition. Carbon and nitrogen concentrations were slightly lower in the fire-break than unburnt soils, but the reduced concentrations were unlikely to cause severe soil degradation in fire-break zones. From a management perspective, fire-breaks appear to be a sustainable management tool as they are not adversely affecting plant diversity or range condition in the grassland association on LDNR.Keywords: abandoned cultivated land, annual burning, range condition, species richness, succession

Abstract: The Succulent Karoo, one of two arid biodiversity hotspots in the world, is known for its high plant species richness, but little is known about the influence of topography and how it mediates the potentially deleterious effects of grazing. Changes in vegetation species composition, cover and species diversity were examined along piosphere gradients on northerly slopes, bottomlands and low-lying plains on 45 farms. Landscapes differed in the plant speciesand life-form composition, species richness and cover, with the more species-rich, heterogeneous grassy northerly slopes distinct from the plains and bottomlands, which were dominated by Pteronia pallens, Psilocaulon junceum and Drosanthenum spp. with more annual and ephemeral species. Overall, species richness declined linearly with decreasing rangeland condition. A weak grazing effect was detected only on the north-facing slopes, where shrubs and grass decreased with intense grazing. Years of overgrazing have resulted in the widespread dominance of P. p...

Abstract: The economic and performance effect of supplementing smallholder cattle by substituting commercial feed with iso-nitrogenous and iso-energetic diets based on alternative protein sources was investigated in two trials. In trial 1, three diets (commercial concentrate, commercial concentrate partially substituted with mucuna, and commercial concentrate partially substituted with lablab–cowpea) compared with veld grass were allocated to 12 cattle in a complete randomised block design. In trial 2, a double complete randomised block design with 40 cattle assigned to four forage legume-based diets, a poultry-based diet and a commercial beef concentrate was carried out. Diets were offered at 1.5% of body weight daily over 56 d. Average daily weight gain (ADWG) was measured weekly in trial 1 and fortnightly in trial 2. In trial 1, ADWG was significantly (p < 0.05) higher for animals on supplements compared with non-supplemented cattle. In trial 2, ADWG was significantly highest on the groundnut stover-based diet a...

Abstract: Book Title: Grasses and Grazers of Botswana and the Surrounding Savanna Book Author: Veronica Roodt 2015, Struik Publishers, PO Box 1144, Cape Town 8001, South Africa. 344 pages, softcover. ISBN 978-1-775-84115-9. Price R290.00

Abstract: This study examined the effects of adding forage legumes as protein supplements to poor-quality natural pasture (veld) hay offered to goats on microbial protein yield and nitrogen metabolism. Four indigenous Nguni-type goats were used in a 4×4 Latin cross-over design experiment. Goats were randomly allocated to four dietary treatments comprising commercial goat feed (GF), veld hay supplemented with cowpea (CW), velvetbean (VB) or silverleaf desmodium (SD). Microbial protein yields were determined using the purine derivatives technique and nitrogen retention was calculated from the digestible organic matter intake. Total nitrogen intake was significantly higher in the GF followed by CW, SD and VB, respectively. Microbial protein supply, calculated microbial true protein and digestible microbial true protein were affected (P<0.05) by legume supplementation. Animals on poor-quality forages had the most efficient microbial protein synthesis. However, supplementation of hay failed to meet the maintenance requi...

Abstract: Book Title: The New Game Rancher Book Authors: Pamela & Peter Oberem (compiling editors) 2016, Briza Publications, P.O. Box 11050, Queenswood 0121, South Africa 373 pages, hardcover ISBN 978-1-920217-62-4. Price R450.00

Abstract: Pseudo-galls of three East African acacia (Vachellia) species were compared to determine the correlates of gall colour and their potential defensive functions. Although all three species produce white thorns, the pseudo-galls of V. gerrardii and V. drepanolobium are dark coloured. In contrast, pseudo-galls of V. seyal var. fistula are white. Associated with this, they are thin-walled and poorly used by aggressive mutualistic ants. We suggest that this weak functionality is compensated for by the highly visible white colour. This aposematism may also involve mimicry as only the fistula variety of V. seyal has galls and only this variety co-occurs with other Vachellia species that have functional galls. Vachellia seyal seyal does not have pseudo-galls and this variety does not occur with other Vachellia species that have pseudo-galls.

Abstract: Livestock excreta is one of the major nutrient sources in natural grasslands. Understanding how livestock diet and season affects the decomposition dynamics is critical to nutrient cycling models. We hypothesised that livestock diet and season of the year affect dung decomposition. This study evaluated the decomposition and release of N, P, K, Ca, Mg, and Na from faeces of cattle collected in dry and wet seasons. Treatments were signalgrass (Brachiaria decumbens Stapf) in monoculture or mixed with sabia (Mimosa caesalpiniifolia Benth.) or gliricidia (Gliricidia sepium (Jacq.) Kunth ex Walp.). Excreta samples were incubated in nylon bags for 0, 2, 4, 8, 16, 32, 64, 128 and 256 d. The single negative exponential mathematical model was adequate (P < 0.0001) to explain the decomposition. The relative rate of dung decomposition (k) was greater for samples that originated from cattle grazed on signalgrass (k = 0.00284 g g−1 d−1), followed by sabia (k = 0.00233 g g−1 d−1), and gliricidia (k = 0.00200 g g−1 d−1) ...

Abstract: can impact on the substrate (vegetation and soils), resulting in multiple states, representing the different levels of ecosystem structure. These structural states vary according to the density of elephants, as well as the intensity of the inter-annual variation in climatic drivers. Finally, there are a group of responders to these states, including other large mammals and birds. The book is structured to present each component of the model.

Abstract: Important drivers of woody cover in African savannas are rainfall, soil and nutrients, and disturbance factors, such as fire and herbivory. However, very little is known about how these drivers influence woody cover at specific height classes. The main aim of this study was to identify which of these drivers are the best predictors of woody cover at three height classes: shrub (0.75–2.5 m), brush (2.5–5.5 m) and tree (>5.5 m). Percent woody cover estimates were collected using a rapid monitoring technique over 1 700 sites in Kruger National Park, South Africa. Geology (basalt and granite), mean annual rainfall, fire frequency and elephant density were analysed as potential drivers of woody cover. Results indicate that mean annual rainfall was negatively associated with shrub cover, fire frequency was negatively associated with brush cover, and elephant density was negatively associated with tree cover. Patterns of woody cover show that while geology influences the spatial distribution of horizontal woody ...

Abstract: Disturbance by fire in the Succulent Karoo is rare but fire events could increase as a result of an increase in grassiness (alien and indigenous species). This study assessed the effects of fire eight years after an experimentally induced burn in Succulent Karoo vegetation. Post-fire monitoring was conducted using the line intercept method and species counts per plot (1 m2) for each of three fire disturbance treatments: control/unburnt, high and low fuel load. Vegetation cover and abundance were compared across treatments and growth forms. Vegetation cover and abundance on fire-disturbed plots had not returned to pre-fire levels after eight years. Resprouters exhibited a rapid recovery and early dominance on burnt plots. Succulent seedlings established slower, but after eight years occurred at higher densities on the burnt than control plots. Recovery after disturbance of density and cover of long-lived, woody non-resprouter non-succulents was slow relative to resprouting non-succulents and reseeding succ...

Abstract: Though important, CO2 effluxes from non-agricultural ecosystems are poorly characterised. Given that thicket vegetation is prevalent in Eastern Cape, South Africa, we monitored soil CO2 effluxes from an intact thicket, degraded thicket (DT) and grassland (G) over 10 months, as affected by temperature, moisture and penetration resistance (PR). High soil moisture (16%) reduced PR (4 kg cm−2), which raised winter effluxes (1.2 µmol m−2 s−1), while low moisture (2%) resulted in hard dry soil (14 kg cm−2) that suppressed spring effluxes (0.2 µmol m−2 s−1). There was good interaction between PR and moisture (r = −0.53), with seasonal effluxes increasing with increasing moisture (r = 0.9, p = 0.0001) and decreasing PR (r = −0.66, p = 0.02). Temperature effects were significant under unlimited moisture supply. Thus high summer temperature (40 °C) gave lower effluxes in DT and G (<1 µmol m−2 s−1) due to limited moisture (<10%), whereas high autumn temperature (48 °C) and good moisture (16%) accelerated CO2 emissio...

Abstract: The major challenge to adoption of improved forage technologies in the smallholder farming sector is poor accessibility to seed of improved cultivars. Since 2012, the Zimbabwe Crop Livestock Integration for Improved Food Security (ZimCLIFS) project set out to address such challenges through research-for-development initiatives. The main objective was to demonstrate the potential viability of a pasture seed business using a lead farmer approach, farmer-to-farmer technology dissemination, innovation platforms and field demonstrations. Snapshot surveys were used to map forage seed distribution pathways within and outside project areas. Total land area planted to forages from the 2012/13 to 2014/15 seasons increased by 147% from 14.6 ha. In 2013, Mucuna pruriens (mucuna), Lablab purpureus (lablab) and Vigna unguiculata (cowpea) seed produced was 2 250 kg, 120 kg and 4 450 kg, respectively, and by the third season, total yield increased by 163%. Seed diffusion was within and beyond project boundaries, with muc...

Abstract: In rangelands, grazing management is a main driver of rangeland condition. Due to masking effects of seasonal climate fluctuations, little is known about (dis)similarity of management effects on rangeland condition and forage provision across major dryland biomes. Taking a macro-ecological perspective, we analysed if management effects differed between South Africa’s central grassland and Kalahari savanna biomes. We recorded proxies of forage provision (phytomass, vegetation cover and their ratio) over five seasons, annual rainfall to account for seasonal climate fluctuations, and rangeland condition (through relative abundances of increaser and decreaser species). Regarding forage provision, we found effects of management for the savanna, where, irrespective of rainfall, rotational grazing management resulted in higher phytomass and phytomass–cover ratios than management with continuous grazing. In the grassland, however, this difference was only discernible for phytomass–cover ratio in two years with ab...

Abstract: The objective of this on-farm study was to develop an effective and labour-extensive method to cure forage Lablab purpureus ‘Highworth’ for resource-constrained smallholder farmers in the Goromonzi district, Zimbabwe in 2014. In a completely randomised factorial design, the drying rate of forage subjected to three conditioning treatments, viz. pressing with a plain water-filled 200 L steel drum, pressing with a water-filled 200 L steel drum covered with 14-gauge wire mesh, and chopping to 5 cm length with a machete, was compared with that of unconditioned forage. The conditioning treatments were subjected to three natural aeration methods, viz. Aframe, raised platform, and dry ground. Replicated four times, conditioned forage was cured at a swath density of 25 kg m−2 to cover 3 m2 per treatment over 28 d. Conditioning of forage had a significant (p 0.05) effect on crude protein content. Aeration treatments did not have a ...

Abstract: This study evaluated whether the FieldScout CM 1000 NDVI and Yara N–Tester models can produce accurate and reliable estimates of nitrogen (N), buffer-soluble nitrogen (BSN), buffer-insoluble nitrogen (BISN), non-protein nitrogen (NPN) and in vitro ruminal nitrogen degradability after 3, 12 and 24 h incubation (ND3, ND12 and ND24) in three tropical grasses: Brachiaria hybrid, Megathyrsus maximus and Paspalum atratum. Correlation between the Yara N-Tester and N, BISN and in vitro ruminal N degradability of the Brachiaria hybrid and M. maximus were high (r 0.67–0.83). The Yara N-Tester accounted for 81% and 86% (p 0.000) of N variability in the Brachiaria hybrid and M. maximus, respectively. The Yara N-Tester prediction models explained 72% and 70% (p 0.000) BISN variability in the Brachiaria hybrid and M. maximus, respectively. In vitro ND24 of the Brachiaria hybrid (R 2 0.75) and M. maximus (R 2 0.75) was also best predicted with the Yara N-Tester. Model validation showed generally low (≤0.90) concordance ...