Influence on a North‐Eastern Sandy Highveld sward of winter utilization by sheep

Rethman, N.F.G.; Beukes, B.H.; Malherbe, C. E.

doi:10.1080/00725560.1971.9648636

Cited by 7 publications

(5 citation statements)

References 2 publications

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“…These findings coincide with the results of Rethman, Beukes & Malherbe (1971) with Digitaria tricholaenoides. According to their results a significant decrease in basal cover occurred when plots were grazed during the early summer and winter, and were cleaned off (mown) afterwards.…”

Section: Resultssupporting

confidence: 95%

Grazing ofcymbopogon‐themedaveld in the dormant period

G¹

1975

Proceedings of the Annual Congresses of the Grassland Society o

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The influence on summer-rested veld of grazing during autumn, winter, and early summer was studied in Cymbopogon-Themeda Veld at Potchefstroom. Continuous grazing throughout the winter period, and even during early summer, severely damaged species such as Themeda triandra, Eragrostis curvula and Digitaria eriantha although it did not affect total herbage yields. Early summer grazing stimulated undesirable species such as Elyonorus argenteus. A sound system of rotational grazing could, however, avoid damgae of desirable grass species, while keeping unwanted species in check. UITTREKSEL Die invloed van beweiding gedurende die herfs, winter en vroeë somer is opCymbopogonThemeda-veld te Potchefstroom bepaal Die algemene praktyk om veld aanhoudend gedurende die hele winter en selfs vroeë somer te bewei het skade aan soorte soos Themeda triandra, Eragrostis curvula en Digitaria eriantha veroorsaak, alhoewel dit nie die totale opbrengs beïnvloed het nie. Vroeë somerbeweiding kan ongewenste soorte soos Elyonurus argenteus stimuleer. 'n Goeie wisselweidingstelsel kan egter skade aan goeie grassoorte voorkom en tog ongewenste soorte in bedwang hou.

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Section: Resultssupporting

confidence: 95%

Grazing ofcymbopogon‐themedaveld in the dormant period

G¹

1975

Proceedings of the Annual Congresses of the Grassland Society o

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“…(1991, p. 63, 70, 1994, p. 358), however, suggest that for semi‐arid Kalahari savanna conditions species such as Eragrostis lehmanniana Nees and Chloris virgata Sw., which are commonly viewed as pioneers or Increasers and thus as indicators of degradation in the moist eastern savanna areas of southern Africa (cf. Rethman et al ., 1971, p. 60), should not be viewed as such in environments characterized by greater aridity (also see Bosch & Janse Van Rensburg, 1987, pp. 143, 146–147).…”

Section: Species Compositionmentioning

confidence: 99%

“…The so‐called South African ‘lovegrasses’ or Eragrostis spp., for example, are known to be persistent under a range of drought conditions (Cox, 1984, p. 160) and might be considered desirable species in arid areas. Even in relatively moist areas species normally classified as unpalatable may be consumed by livestock ‘with relish’ during particular times of the year, as noted for E. plana Ness in the high altitude ‘sourveld’ of north‐eastern Transvaal during winter grazing by sheep (Rethman et al ., 1971, p. 57; also see Parsons et al ., 1997, pp. 325–326).…”

Section: Species Compositionmentioning

confidence: 99%

“…They concluded that ‘[e]ven though the communal area has twenty times more stock than the commercial farms, soil quality is similar’ (Ward et al ., 1998, p. 369; also see Perkins & Thomas, 1993, p. 188). Rethman et al . (1971, p. 57) even suggest that an increase in soil fertility due to manuring by grazing may enhance the nutritional value of herbaceous species.…”

Section: Soil Erosionmentioning

confidence: 99%

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On non‐equilibrium in arid and semi‐arid grazing systems

Sullivan¹,

Rohde²

2002

Journal of Biogeography

200

148

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A critical comment on A. Illius and T. G. O'Connor (1999) On the relevance of non-equilibrium concepts to arid and semi-arid grazing systems. Ecological Applications, 9, 798-813.A debate in ecology rages over the sources and types of dynamic behaviour driving ecological systems. Drylands have become a particular focus of this debate. In these environments extreme and unpredictable variability in rainfall are considered to confer non-equilibrium dynamics by continually disrupting the tight consumer-resource relations otherwise considered to pull a system towards equilibrium. This implies that livestock grazing in drylands, widely thought to cause degradation and ÔdesertificationÕ through bad management practices leading to overstocking, might not be causing irreversible ecological change through over-use of vegetation. An article recently published in Ecological Applications (Illius & O'Connor, 1999), however, argues that variability in arid and semi-arid grazing systems is not the outcome of qualitatively different dynamical behaviour, and that livestock do cause negative change through ÔnormalÕ density-dependent relations. The authors maintain that these operate primarily in key resource areas and during drought periods.We contest these arguments on several grounds: that key terms are poorly applied in ways which suggest inconsistencies in the internal logic of the arguments; that the paper is unjustifiably selective in the choice and interpretation of ÔevidenceÕ on which it builds; and that the authors do not engage critically with the crucial policy implications of the debate, particularly as they relate to pastoral landuse by African herders in areas under communal tenure and management. We do not suggest that degradation never occurs in arid and semi-arid rangelands, but that Illius and O'Connor's analysis of the mechanisms via which this might take place is misleading and at times, we feel, theoretically bizarre. In particular, we suggest that drought periods may be the times when density-dependent mechanisms are least likely to occur and that key resource areas exist because of ungrazeable reserves which effectively cannot be degraded, although subject to heavy grazing. We also attempt to draw out the theoretical implications of attributing change caused by biotic-abiotic effects to biotic-biotic interactions. We contend that non-equilibrium concepts remain crucial for both natural and social science approaches to understanding dryland environments and their multiple, dynamic uses by pastoralists.Illius and O'Connor's critique of non-equilibrium concepts as a means for understanding ecosystem behaviour in African drylands seeks to address a deepening conceptual fault line separating factions of the rangeland science and livestock development community. Epitomizing one side of this divide are understandings of semi-arid and arid environments in terms of relationships between their biotic components, emphasizing the potential for grazing by domestic livestock to perturb the ÔsystemÕ from a knowable and desi...

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“…The value of empirical experiments in terms of information of practical value is, for example, wellillustrated by the investigations reported by Jones (1967) and Jones and Cross (1971), in which study was made of the effects of differential clipping treatments and nitrogenous fertilisation on the control of the weed Eragrosiis plana in sown pastures. Likewise, the investigations reported by du Toit and Ingpen (1970), Kirkby (1971), and Rethman, Beukes and Malherbe (1971), relating to the effects of various methods of utilisation of veld in the winter, provide a valuable practical guide.…”

Section: The Effect Of Soil Typementioning

confidence: 95%

Defoliation effects on perennial grasses — continuing confusion

Barnes¹

1972

Proceedings of the Annual Congresses of the Grassland Society o

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Although an adequate knowledge of growth patterns and defoliation effects in perennial grasses is a prerequisite for the rational use of veld and pastures for animal production, our knowledge of this subject is far from adequate. The results of various physiological and clipping studies on tropical and subtropical grasses are appraised and their weaknesses in providing information applicable in practical management are indicated. It is suggested that there is a need for increased emphasis on studies of growth patterns and defoliation effects giving priority to (a) defining and evaluating the extrinsic and intrinsic factors affecting differential response to similar defoliation treatments in different circumstances, (b) applying defoliation treatments with a practical bias, and (c) determining actual defoliation patterns under grazing. UITTREKSEL 'n Voldoende kennis van groeipatrone en onthlaringseffekte by meerjarige grassoorte word beskou as 'n noodsaaklike voorvereiste vir die rasionele gebruik van veld en aangeplame weidings vir veeproduksie.Ons kennis van hierdie onderwerp is egter onvoldoende. Die resultate van verskeie fisiologiese en snystudies op tropiese en subtropiese grassoorte word hier evalueer en die tekortkominge by die praktiese toepassing daarvan in veldbeheer, word aangedui. Dit word voorgestel dat groter nadruk op studies van groei patrone en ontblaringseffekte geplaas moet word, met voorkeur aun (a) bepaling en evaluering van die eksterne en interne, faktore wat die differensiële respons op soorlgelyke ontblaringsbehandelings onder verskillende toestande beïnvloed, (b) toepassing van ontblaringsbehandelings met 'n praktiese nadruk en (c) bepaling van werklike ontblaringspalrone onder weitoestande.

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Influence on a North‐Eastern Sandy Highveld sward of winter utilization by sheep

Cited by 7 publications

References 2 publications

Grazing ofcymbopogon‐themedaveld in the dormant period

Grazing ofcymbopogon‐themedaveld in the dormant period

On non‐equilibrium in arid and semi‐arid grazing systems

Defoliation effects on perennial grasses — continuing confusion

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