Soil carbon dioxide effluxes from different vegetation environments in semi-arid Eastern Cape,South Africa

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 emissions (averaging 2 µmol m^?2 s^?1) from all covers. Although semi-arid ecosystems are limited by low moisture and sandy soils, they contribute to CO₂ emissions under high moisture and increasing temperature. Keywords: Eastern Cape, grassland, soil carbon dioxide effluxes, soil organic carbon, thicket     

Observations of microtrash ingestion in Cape Vultures in the Eastern Cape,South Africa

Ingestion of man-made items by birds can reduce stomach volume and block the digestive track. In southern Africa, microtrash within the regurgitation of Cape Vulture nestlings was last documented in 1983. We present evidence of nestling microtrash ingestion after a 30-year gap. Vulture nestlings were captured at a breeding colony in the Eastern Cape, South Africa. One nestling regurgitated three microtrash fragments. Two pieces of microtrash were collected from the nest of another nestling. Neither nestling appeared to have skeletal deformities or feather stress bars. Our results highlight the persistence of microtrash ingestion by Cape Vulture nestlings, which could impact the species negatively.     

Feeding ecology of four livestock species under different management in a semi-arid pastoral system in South Africa

The Leliefontein communal area in Namaqualand is grazed by mixed species herds that have multiple benefits for pastoralists. This study assessed how the management (herding and free-ranging) of different livestock herds affects their feeding ecology during the wet and dry seasons in a semi-arid shrubland. By using direct observations of livestock grazing in the field, we established their habitat preferences, diet selection and resources overlap. Results indicate that all free-ranging livestock can be considered grazers with cattle being selective. When sheep are herded, they tend to be more generalist feeders and herded goats are browsers. Livestock diet selection and forage preferences are largely linked to the habitats in which they graze and browse. Dietary overlap is highest between free-ranging livestock irrespective of season, whereas herded livestock are able to consume a food source with little potential competition from other livestock. Although the wet-season annual forage resources are able to sustain the livestock population in Leliefontein, this study concludes that the overdependence on annual vegetation would make livestock vulnerable during drought periods when forage production is low.     

Spatial patterns of encroaching shrub species under different grazing regimes in a semi-arid savanna,eastern Karoo,South Africa

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 in most of the grazing plots. These findings indicate that (1) at a fine spatial scale, grazing in the wet season promotes shrub encroachment, and (2) there is a tendency to aggregation among encroaching shrub species in the grazing plots.     

Evaluation of shrub species for sheep grazing in the Strandveld of the Cape West Coast of South Africa

The production of three exotic shrub species, Atriplex nummularia (old man saltbush), A. canescens (four‐winged salt‐bush) and Medicago arborea (tree lucerne) and one indigenous evergreen shrub, Chrysanthemoides monilifera subsp. pisifera (west coast bitou), was evaluated in the Strandveld of the Cape West Coast in terms of grazing capacity (ssu ha^?1) and average daily gain (ADG) (g ssu^?1 day^?1) using mature Dorper sheep. Medicago arborea died out during the first season. The other three shrubs, however, survived and over a seven‐year period mean grazing capacities of 1.7, 1.6 and 1.0 ssu ha^?1 were obtained, respectively, for C. monilifera, A. nummularia and A. canescens, which is in excess of the area norm of 5 ha ssu^?1 for natural veld. Positive ADGs of 80 and 30 g ssu^?1 day^?1 were obtained on A. nummularia and A. canescens, respectively, but not on C. monilifera (‐180 g ssu^?1 day^?1).     

Impact of Prosopis (mesquite) invasion and clearing on vegetation species composition and diversity in semi-arid Nama-Karoo rangeland,South Africa

The Nama-Karoo biome occupies 28% of South Africa’s land area. Alien leguminous trees of the genus Prosopis have invaded large tracts of Nama-Karoo rangeland. We evaluated the impact of Prosopis invasion and clearing on vegetation species composition and diversity (alien and indigenous species richness and cover) in Nama-Karoo rangeland on two sheep farms in the Beaufort West district of the Western Cape province of South Africa. Our results suggest that Prosopis invasion and clearing can significantly change Nama-Karoo rangeland species composition. Invasion and clearing appear to have no effect on alien species richness. Invasion, however, increases alien species cover, while clearing restores it to pre-invasion levels. In contrast, invasion reduces indigenous species richness while clearing restores it to pre-invasion levels. Invasion appears to have no effect on indigenous species cover. This lack of effect appears to be the serendipitous result of a site-specific trade-off between a decline in cover of grasses that are negatively affected by Prosopis invasion and a concomitant increase in the cover of positively affected grasses. Clearing increases indigenous species cover to above pre-invasion levels. The higher than usual indigenous species cover after clearing could be a transient legacy of Prosopis soil nutrient enrichment.     

Livestock grazing has minimal effect on the species richness and diversity of semi-arid shrubland in the Western Little Karoo,South Africa

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. pallens, especially on the plains and bottomlands, rendering them insensitive to grazing. The current condition of the northern slopes should be maintained and managed such that palatable species can spread to more degraded areas of the landscape.     

Ixodid ticks on dogs in the eastern region of the Eastern Cape Province, South Africa

The objective of this study was to determine the species composition and geographic distribution of ixodid ticks infesting domestic dogs in the eastern region of the Eastern Cape Province. Seventy-two communal cattle dip-tanks within this region were randomly selected as survey localities and their geographic coordinates recorded. In addition to ticks that were collected from five cattle and five goats at each of the dip-tanks, ticks were also collected from five dogs whenever possible. No dogs were available at 19 dip-tanks and no ticks were collected from dogs at 13 dip-tanks, while ticks were collected from 132 of 200 dogs at 40 dip-tanks. Eight ixodid tick species were collected from these dogs, and Haemaphysalis leachi followed by Rhipicephalus appendiculatus and Rhipicephalus simus were present on dogs at the largest number of dip-tanks. Seven dogs were simultaneously infested with three tick species and one with four species. The geographic distributions of Amblyomma hebraeum, H. leachi, R. appendiculatus and R. simus recovered from the dogs lay within the ranges previously reported for these ticks.     

Temporal and spatial dynamics of mineral levels of forage,soil and cattle blood serum in two semi-arid savannas of South Africa

In this study, we examined temporal and spatial dynamics of minerals of forage, soil and cattle serum in two savannas (valley and plain) of South Africa. The aims were to explore the relationships between ecosystem components, and plan communal grazing and fodder flow for sustainable livestock production. In each area, grazing sites near, at intermediate distance from (middle) and far from homesteads were selected. In the valley land, site interacted with season to influence local variations (P<0.05) of soil calcium and microelements. In the plain lands, local variations occurred for soil phosphorus and magnesium. At the large scale, most macro-minerals showed differences between the valley and plain lands. In the valley areas, forage calcium differed (P<0.05) locally in the dry season, whereas in the plain areas, potassium and phosphorus showed local variations (P<0.05) in the wet season. Seasonal variations of most forage elements were significant within each local site of both study areas. All forages were deficient in phosphorus and copper. Cattle serum from the valley area had low iron concentrations. The study concluded that biotic and abiotic factors may influence the distribution of soil and forage elements, but their effects may vary between the two areas. Rangeland improvement and supplementation strategies are suggested to sustain animal production.     

Tick control methods used by resource-limited farmers and the effect of ticks on cattle in rural areas of the Eastern Cape Province,South Africa

A survey to document tick control methods used by resource-limited farmers in the control of cattle ticks in the Eastern Cape Province of South Africa was conducted by interviewing 59 cattle farmers using structured questionnaires and general conversation. Information collected was on external parasites of cattle, their effects and their control methods. Ticks were reported to be a major problem causing diseases like anaplasmosis (89.8%), babesiosis (55.9%) and ehrlichiosis (16.9%), as well as wounds that predispose to screwworm infestation, tick worry and teat damage to cows troubling farmers in their farming enterprises. The main tick control methods were; acaricides provided by government, however 94.9% of the farmers interviewed were of the opinion that the dip wash is not effective in killing the ticks. As a result, farmers complement the government dipping service with their own initiatives like spraying with conventional acaricides (22%), household disinfectants such as Jeyes fluid (18.6%), used engine oil (10.2%), chickens (5.1%), manual removal (5.1%), and pouricides (1.7%). In addition, some farmers also use plants (6.8%), mainly the leaf of Aloe ferox and the bark of Ptaeroxylon obliquum. The study revealed ticks to be a major problem in the study area.     

Marine connectivity and fish length frequencies of selected species in two adjacent temporarily open/closed estuaries in the Eastern Cape Province,South Africa

The effects of timing, frequency and duration of mouth opening and marine overwash events on fish assemblages in two, adjacent temporarily open/closed estuaries were investigated. Sampling was conducted biannually over two years during summer and winter, using selective sampling gear to target estuarine-associated marine species. During this period the East Kleinemonde Estuary opened more frequently than the West Kleinemonde Estuary and it also experienced a greater number of bar overwash events when larval recruitment can occur. The timing of mouth opening and the frequency of marine overwash events did not influence species richness of marine-spawning species but had a pronounced effect on abundances (catch-per-unit-effort) of species. The species composition of both estuaries was similar, but the catch-per-unit-effort in the East Kleinemonde Estuary was more than three times greater than that of the West Kleinemonde Estuary. The East Kleinemonde also supported a greater proportion of immature individuals of Rhabdosargus holubi and Monodactylus falciformis, and the length frequency distributions of both these species differed significantly between the two estuaries. The larger fish sizes in the West Kleinemonde Estuary were attributed to the prolonged mouth closure that resulted in the trapping of larger juveniles and mature fish within the estuary.     

Introduction,establishment and spread of the Southern mouthbrooder Pseudocrenilabrus philander in the Baakens River,Eastern Cape,South Africa

This paper provides evidence for the extralimital establishment and spread of Pseudocrenilabrus philander in the Baakens River, Eastern Cape, South Africa. Since the first occurrence record at a single locality in 1994 this species has now spread throughout the river and the population contains both reproductive adults and juveniles. Gut content analysis demonstrated potential dietary overlap with native fishes and predation on fish larvae. Pseudocrenilabrus philander in the Baakens River therefore satisfies all criteria for an invasive species in this river and was categorised as invasive using a unified framework for biological invasions.     

Effect of Prosopis (mesquite) invasion and clearing on vegetation cover in semi-arid Nama Karoo rangeland,South Africa

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 reduce rangeland erosion potential at low cover and increase it after they exceed critical threshold cover. Information about thresholds of Prosopis impact can be used to direct clearing efforts for maximum benefit when resources are limited.     

Traditional remedies used for the treatment of cattle wounds and myiasis in Amatola Basin, Eastern Cape Province, South Africa

A questionnaire survey was carried out to document traditional remedies used in the treatment of cattle wounds and myiasis in Amatola Basin. Eighty-three cattle farmers from nine villages were interviewed. The majority of respondents (67.9%) use traditional remedies for treatment of these conditions. However, 25.9% of them use a combination of traditional remedies with conventional medicines. The survey revealed that 13 medicinal plants belonging to 11 families were used. Aloe ferox, Prunus persica and Phytolacca heptandra were, however, the most commonly used. Leaves are the most frequently used plant part, often prepared as an infusion. Other non-plant remedies used include disinfectants, antiseptics as well as diesel and petrol. Manual removal of maggots from wounds was also practise and treatment is usually continued until the wound heals.     

微量元素钼在畜禽生产中的应用

本文从分布、代谢、营养、缺乏及过量方面阐述了钼的特点及在畜禽生产中的应用并指出钼研究领域存在的问题和研究方向。     

Use of herbal remedies by small-scale farmers to treat livestock diseases in Central Eastern Cape Province, South Africa

The use of herbal remedies by African farmers in the treatment of livestock diseases was investigated using a range of methods, including group interviews, structured interviews, semi-structured interviews and participant observation. The study was concerned mainly with the 'why' and 'how' of herbal remedy use among African livestock holders farming on communally-owned land in central Eastern Cape Province. We found that the use of herbal remedies was still widespread because these remedies were cheap, locally available and convenient to administer. Farmers also used herbal remedies because they did not have knowledge of conventional remedies or found these too expensive and therefore used herbal remedies as a last resort. Most of the farmers interviewed (73%) had used some form of herbal remedy. A small number of farmers did not use herbal remedies at all. They rejected them because they had bad experiences in the past or because they considered the practice outdated and socially inferior. Often farmers used herbal remedies in combination with conventional ones, but a substantial number relied on herbal remedies only. Farmers obtained herbal remedies principally by preparing their own or by purchasing from herbalists. Different plant parts were used to prepare herbal remedies in the form of infusions, decoctions, powders, pastes, and juices from fresh plant material. Preparations were made from a single plant or from a range of plants. Application of a remedy was by different routes and methods, depending on the perceived cause of the disease condition. Topical applications were used for skin conditions, powders were rubbed into incisions, drenches were common in the treatment of systemic conditions, and drops to treat ears and eyes. We identified several aspects of herbal remedy utilisation that could be subject to improvement, which included the absence of standard dose regimes, the potential toxicity of certain compounds present in plants used, over-exploitation of the plant resource and a lack of interest by the youth to learn the art.     

Milk production and calf rearing practices in the smallholder areas in the Eastern Cape Province of South Africa

Farmer perceptions on milk production and calf rearing practices on communal rangelands in the smallholder areas of the Eastern Cape Province, South Africa were evaluated on a total of 218 cattle farmers using structured questionnaires, semi-structured interviews with key informants and personal observations. Nearly 70% of the households in the small-scale areas milked twice a day compared to 60% in the communal areas. About 62% of the interviewees weaned calves between 6 and 12 months of age. Milk yield/cow/day (7.5 ± 0.5 litres), fresh milk consumption/household/day (3.2 ± 0.5 litres) and sales/household/day (3.1 ± 1.1 litres) were highest in the sour-veld, small-scale farms (P < 0.05). Sour milk consumption/household/day (2.6 ± 0.2 litres) and sales/household/day (0.8 ± 0.2 litres) were significantly high in communal farms with a sour-veld. It was concluded that, calf rearing practices were poor and milk yield, consumption and sales were generally low and varied with production system and rangeland type. Further research is required to improve calf management practices, cow nutrition, milk yield and quality and how milk production can be used as a toll for rural development in the smallholder areas of South Africa.     

The impacts of season and livestock management strategy on the quality of diets selected by goats and sheep in the semi-arid rangelands of Namaqualand,South Africa

Access to good-quality forages is one of the major limitations to livestock production in semi-arid pastoral systems. This study aimed to determine whether there are differences in the nutritional quality of diets selected by herded and free-ranging goat and sheep flocks utilising Namaqualand Granite Renosterveld vegetation during the wet and dry seasons. Plant samples collected along the grazing routes of livestock were dried and analysed for their fibre, condensed tannin, total phenolic and mineral nutrient contents. The study showed that a large variety of forages were on offer and livestock groups selected different diets of which some were different to the total diet on offer. In general, significant deficiencies in phosphate, protein and energy in the diets selected by herded and free-ranging goats and sheep were observed in both wet and dry season. The quality of the diets selected by herded and free-ranging livestock was also found to be different from each other, with herded livestock generally selecting more nutrient-dense diets. Herding, therefore, allows livestock to access better-quality forage in the Namaqualand Granite Renosterveld rangeland, where it is generally poor.     

有机微量元素对生长猪生长性能及微量元素排出量的影响

选用96头平均体重为（19.13±1.18）kg生长猪,分为处理1组（高剂量无机微量元素组）、处理2组（高剂量有机元素组）、处理3组（低剂量无机元素组）、处理4组（高剂量有机元素组）,每个处理3个重复,每个重复8头仔猪,试验期50 d,研究有机微量元素对生长猪生长性能及微量元素排出量的影响力。结果表明：处理1、2、4组的日增重分别比处理3组提高5.83%、7.03%、7.70%,均显著高于处理3组（P＜0.05）,其他处理组之间的日增重差异不显著。处理1、2、4组的料重比分别比处理3组降低5.28%、6.79%、7.92%,均达差异显著（P＜0.05）,处理1、2、4组之间的料重比差异不显著,处理4组的料重比最低。处理1组和处理2组粪中铜、铁、锌、锰的排泄量差异均不显著,处理3组和处理4组粪中铜、铁、锌、锰的排泄量差异均不显著,处理3组和处理4组粪中铜、铁、锌、锰的排泄量比处理1组和处理2组显著降低（P＜0.05）。