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 African Journal of Range & Forage Science

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VOLUME 19 ISSUE 1 (2002)

African Journal of Range & Forage Science 2002, 19: 1—11

©2001 NISC Pty Ltd, www.nisc.co.za

Diet selection of goats in the communally grazed Richtersveld National Park

HH Hendricks1*, PA Novellie2, WJ Bond3 and JJ Midgley3

1 South African National Parks, PO Box 110040, Hadison Park 8306, South Africa

2 South African National Parks, PO Box 787, Pretoria 0001, South Africa

3 Botany Department, University of Cape Town, Private Bag, Rondebosch 7701, South Africa

* Corresponding author, e-mail: [email protected] 

Received 8 August 2001, accepted 20 February 2002

The study provided an account of the diet selection of goats within the Richtersveld National Park and focused on (a) diet composition, (b) plant growth-forms, (c) principal and preferred food plants. The conservation status of these food plants was also assessed. The diet of goats included a wide variety of plant species. A total of 87 species were recorded to be eaten by goats during winter within the National Park while 39 species were completely ignored. In this study, goats preferred herbaceous food plants. The foliage of woody browse and leaf-succulent plants became important in sites where forbs were limited. A total of 13 plant species in the diet of goats were considered to be principal food plants. Of the 32 species that were preferred, 19 species were intermediate whilst 13 species were highly preferred. The majority of plant species in the diet of goats are considered to be of low conservation priority.

Keywords: foraging, principal foods, dietary preferred plants, growth-form, Succulent Karoo

African Journal of Range & Forage Science 2002, 19: 13—20

©2001 NISC Pty Ltd, www.nisc.co.za

Dietary overlap between Boer goats and indigenous browsers in a South African savanna

L Breebaart1†*, R Bhikraj1 and TG O’Connor2

1 Range & Forage Resources, School of Applied Environmental Sciences, and 2 Centre for Sustainable Savannas, University of Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa

† Present address: National Botanical Institute, Private Bag X7, Claremont 7735, South Africa

* Corresponding author, e-mail: [email protected] 

Received 26 October 2001, accepted 19 January 2002

The winter diet of free ranging Boer goats in Valley Bushveld, KwaZulu-Natal, was determined by direct observations and compared with the diet of indigenous browsers (kudu, eland, giraffe, black rhinoceros) in order to determine which browsers are most compatible with goats for ensuring more efficient use of savanna vegetation. Goats were predominantly browsers during winter, spending 73% of their time eating woody plant forage. Principal woody plant species in the diet included Rhus pentheri, Acacia nilotica, Acacia karroo, Euclea crispa and Ziziphus mucronata. Succulents (Aloe ferox and Aloe maculata) were also readily eaten. Highly preferred species were Capparis sepiaria, Phyllanthus verrucosus and Scolopia zeyheri, while Rhoicissus tridentata, Calpurnia aurea, Acacia ataxacantha, Euclea natalensis, Clerodendrum glabrum, Zanthoxylum capense and Hippobromus paucifolia were strongly avoided. Goats fed between ground level and 1m, with an average feeding height of 0.67m. The diet and feeding height of kudu and goats and of black rhinoceros and goats overlapped to a large extent suggesting that they are potential competitors for food resources. Similarly, overlap in diet between giraffe and goats was extensive, but overlap in feeding height was small. The potential for competition appeared to be the least between goats and eland because, despite feeding at similar heights, they generally consumed different species. A mixed farming system which includes goats, eland and giraffe is proposed as a useful management tool for using savanna vegetation more efficiently.

Keywords: animal production, bush encroachment, competition

African Journal of Range & Forage Science 2002, 19: 21—28

©2001 NISC Pty Ltd, www.nisc.co.za

Predicting the extent of succulent thicket under current and future climate scenarios

MP Robertson1 and AR Palmer2*

1 Department of Zoology and Entomology, Rhodes University, Grahamstown 6140, South Africa

2 Agricultural Research Council — Range and Forage Institute (ARC—RFI), PO Box 101, Grahamstown 6140, South Africa

* Corresponding author e-mail: [email protected] 

Received 30 December 2001, accepted 25 March 2002

Using data from the distribution records of the facultative CAM succulent shrub Portulacaria afra, and high resolution climate response surfaces, we developed a spatially explicit model of the potential distribution of the species in the Thicket Biome of the eastern and southern Cape, South Africa. The resultant map shows a close relationship with the expected distribution of P. afra prior to the advent of intensive ranching by goats in the region. In field situations where P. afra is known to have been cleared by agricultural activities, the map showed the potential of the site for this species. It also demonstrated the absence of the species in areas where it does not occur e.g. fynbos, grasslands, forest and Nama-karoo. A weakness of the model is the lack of a measure of the density of P. afra. Under the CSM (coupled ocean-atmosphere model) climatic change scenario, 80.3% of the grid-cells would remain suitable and 19.7% would become unsuitable.

Keywords: potential distribution model, CSM, coupled ocean-atmosphere model, climate change, CAM, Crassulacean acid metabolism, thicket, Portulacaria afra

African Journal of Range & Forage Science 2002, 19: 29—44

©2001 NISC Pty Ltd, www.nisc.co.za

Estimated spatial requirements of the medium- to large-sized mammals, according to broad habitat units, in the Cape Floristic Region, South Africa

AF Boshoff1*, GIH Kerley1 and RM Cowling2

Terrestrial Ecology Research Unit, Departments of Zoology1 and Botany2, University of Port Elizabeth, PO Box 1600, Port Elizabeth 6000, South Africa

* Corresponding author, e-mail: [email protected] 

Received 17 September 2001, accepted 18 January 2002

Conservation planning in the Cape Floristic Region (CFR) of South Africa, a recognised world plant diversity hotspot, required information on the estimated spatial requirements of selected medium- to large-sized mammals within each of 102 Broad Habitat Units (BHUs) delineated according to key biophysical parameters. Spatial requirement estimates were derived for 19 omnivore and carnivore species, following a review and extrapolation of extant information. The estimates for 23 herbivore species were derived from a simple spreadsheet model based on forage availability estimates and the metabolic requirements of the species in question; this analysis incorporated adaptations of the agriculture-based Large Stock Unit (LSU) or Animal Unit approach. The LSU approach has various shortcomings but given the virtual absence of information on forage availability (quantity, quality and seasonality) for indigenous herbivores in the CFR, it provides the only extant measure of the influence of key biophysical factors on this parameter, especially at a regional scale. The outcomes of the exercise, viz. densities (hectares/animal), are presented here; these should be considered as testable hypotheses and a cautious ‘management by hypothesis’ approach should be adopted in their use. This information can be used to guide both conservation planning activities and practical conservation management decisions.

Keywords: forage production, species assemblages, herbivore densities, conservation planning, conservation management

African Journal of Range & Forage Science 2002, 19: 45—53

©2001 NISC Pty Ltd, www.nisc.co.za

Spatial and temporal variation in a mesic savanna fire regime: responses to variation in annual rainfall

DA Balfour* and OE Howison

KwaZulu-Natal Nature Conservation Service1, Hluhluwe-Umfolozi Park, PO Box 25, Mtubatuba 3935, South Africa

* Corresponding author, e-mail: [email protected] 

Received 15 November 2001, accepted 22 January 2002

This paper analyses the fire regime over 41 years (1956 to 1996) in Hluhluwe-Umfolozi Park, a mesic savanna area in South Africa. The study focuses at the landscape scale of tens of kilometres and at the medium term temporal scale of decades. Variation in fire regime was analysed in relation to variation in annual rainfall and the influence of management. The average annual area of the park that burnt was 26% and the average area of individual fires was 9.1km2. Statistics relating to the percentage of area burnt annually, the average size of an individual burn, the mean and median fire return periods and the influence of management philosophy relative to the spatial and temporal variation in rainfall conditions are presented. Sources of ignition and implications for management are discussed.

Keywords: fire history, fire management, fire return period, Hluhluwe-Umfolozi Park

African Journal of Range & Forage Science 2002, 19: 55—62

©2001 NISC Pty Ltd, www.nisc.co.za

The influence of various types and frequencies of rest on the production and condition of sourveld grazed by sheep or cattle. 1. Proportional species composition

KP Kirkman

Grassland Science, School of Applied Environmental Sciences, University of Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa 

e-mail: [email protected] 

Received 3 September 2001, 9 October 2001

Data collected between 1992/93 and 1996/97 from a long-term grazing trial were used to investigate the interaction between grazing animals and veld grass. Comparisons were made, firstly between the impacts of sheep and cattle grazing, and secondly between various types and frequencies of rest, on veld vigour and condition. Treatments involved applying a full growing season rest in alternate years, half a growing season rest (late season) in alternate years and no rest to veld grazed by sheep or cattle at similar stocking rates. Changes in proportional species composition were determined using a nearest plant point technique. Species composition of veld grazed by sheep deteriorated over the trial period in contrast to the veld grazed by cattle, which improved in species composition. Grazing management recommendations for sourveld should include a bias towards cattle and include resting for enhancing vigour of the palatable grasses.

Keywords: grazing management, livestock type, livestock movement

African Journal of Range & Forage Science 2002, 19: 63—69

©2001 NISC Pty Ltd, www.nisc.co.za

Preliminary results of a stocking rate trial in Lesotho

LM Mpiti-Shakhane1*, GY Kanyama-Phiri2, WO Odenya1 and JW Banda2

1 National University of Lesotho, Department of Animal Science, PO Roma 180, Lesotho

2 Bunda College of Agriculture, PO Box 219, Lilongwe, Malawi

* Corresponding author, e-mail: [email protected] 

Received 10 March 2001, accepted 22 January 2002

Forage responses to stocking rates and seasons were determined over a one-year period. The experimental design consisted of three stocking rates namely, light (2.0ha LSU-1), moderate (1.25ha LSU-1) and heavy (0.5ha LSU-1) and four seasons (autumn, winter, spring and summer) combined factorially in a Randomised Complete Block Design with three replicates per treatment. Data collected included aboveground available phytomass production, botanical composition and crude protein content.

Total aboveground available phytomass production of forages at the end of the study period was significantly (P<0.05) lower in the heavy stocking rate than in the moderate and light stocking rates. Season significantly (P<0.05) reduced crude protein (CP) from 5.6% CP in summer and 7.8% CP in autumn to 4.2% CP in winter and 4.3% CP in spring. It is concluded that season exerted greater impact on sward productivity than stocking rate.

Keywords: aboveground available phytomass, crude protein, seasonal variation, species composition

Abbreviation: LSU = Large Stock Unit

African Journal of Range & Forage Science 2002, 19: 71—75

©2001 NISC Pty Ltd, www.nisc.co.za

Merino sheep responses to different stocking rates and seasonal variation under rangeland conditions of Lesotho

LM Mpiti-Shakhane1*, GY Kanyama-Phiri2, WO Odenya1 and JW Banda2

1 National University of Lesotho, Department of Animal Science, PO Roma 180, Lesotho

2 Bunda College of Agriculture, PO Box 219, Lilongwe, Malawi

* Corresponding author, e-mail: [email protected] 

Received 10 March 2001, 22 January 2002

Merino sheep responses to stocking rates were determined over a one-year period. The experimental design consisted of three stocking rates; light (2.0ha LSU-1), moderate (1.25ha LSU-1) and heavy (0.5ha LSU-1) in a Randomised Complete Block Design with three replicates per treatment. Data collected were live weight, grease fleece weight, staple length, fibre diameter and crimp frequency from ewes, and birth weight, growth rate, weaning weight and percent mortality from lambs. Ewes in the heavy stocking rate had significantly (P<0.05) lower final weight, grease fleece weight and fleece length than those in moderate and light stocking rates. Lambs in the heavy stocking rate had significantly (P<0.05) lower birth weight and weaning weight, but higher mortality than those in moderate and light stocking rates. It is concluded that heavy stocking rate significantly reduced ewe and lamb performances.

Keywords: mortality, weight gains, wool production, wool quality

African Journal of Range & Forage Science 2002, 19: 77—78

©2001 NISC Pty Ltd, www.nisc.co.za

Impact of goat browsing on Aloe ferox in a South African savanna

L Breebaart1†*, R Bhikraj1 and TG O’Connor2

1 Range & Forage Resources, School of Applied Environmental Sciences and 2 Centre for Sustainable Savannas, University of Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa

† Present address: National Botanical Institute, Private Bag X7, Claremont 7735, South Africa

* Corresponding author, e-mail: [email protected] 

Received 26 October 2001, accepted 30 January 2002

The extent and impact of the utilisation of Aloe ferox by Boer goats during winter in a South African savanna was determined using a plant-based approach. All Aloe plants rooted within the transects were eaten by goats, with small plants utilised more frequently than tall plants. The density of dying and dead Aloe plants was significantly greater than live plants. Mortality of Aloe ferox was a result of extensive browsing by Boer goats. The future survival of Aloe ferox in this savanna system is highly unlikely.

Keywords: browsers, succulents, survival