agricultural production guidelines
m
Veld in KwaZulu-Natal
Co-ordinated Extension KwaZulu-Natal Veld 4.9 1999
BIORESOURCE GROUPS 19 AND 20: MOIST AND DRY ZULULAND THORNVELD
C R Hurt
ARC - Range and Forage Institute, Cedara
K G T Camp
KwaZulu-Natal Department of Agriculture
Vegetation
Structure and Compositions
Veld Benchmark
Animal Production
INTRODUCTION
Bioresource Groups 19 and 20 have traditionally been used as winter grazing areas, particularly for beef and, increasingly, for game.
The Moist Zululand Thornveld (refer to Figure 1 in Production Guideline 4.1 in this series) lies mainly on the coastal belt below an elevation of 450 m. In its northern extremity, north of the Hluhluwe Game Reserve, it rises to an elevation of approximately 560m. The main areas of the BRG lie in the Heatonville area west of Empangeni and in a large body west of Mtubatuba. These two areas have the Moist Coast BRG lying to the south-east and the Dry Zululand Thornveld (BRG 20) or Lowveld (BRG 22) lying on their western and north-western borders. Additional areas are found on the hills in the Hluhluwe Game Reserve and extend to the north of the Reserve.Moist Zululand Thornveld (BRG 19)
Dry Zululand Thornveld (BRG 20)
In the north of the Province, the Dry Zululand Thornveld (refer to Figure 1 in Production Guideline B1.1 in this series) lies on the escarpment above 450 m and to the west of the Lowveld (BRG 22). This area includes the Pongola River valley to the west of the town of Pongola and the tops of hills rising out of the Lowveld to the East and south-east of the town of Magudu. Magudu lies on the crest of a hill in the Dry Zululand Thornveld. The Swart Mfolozi area and hilltops in the Hluhluwe-Umfolosi Game Reserve are found within this BRG, while the southern limit is an extensive area in the vicinity of Heatonville.
VEGETATION STRUCTURE AND COMPOSITION
The vegetation of these BRG’s is mainly a savanna with varying tree/bush density.
The vegetation pattern varies considerably from an open grassland with patches of scrub forest to bushed grassland and bushland thicket. Riverine bushland thickets occur along most drainage lines. The grassland is a transition from sour to mixed veld. Forbs are common in the grass layer. The dominant grass species include Themeda triandra, Eragrostis capensis, E. racemosa, Tristachya leucothrix, Heteropogon contortus, Trachypogon spicatus and Schizachyrium sanguineum. Panicum maximum is the dominant grass under trees. When overgrazed, the grassveld reverts initially to species of Eragrostis (mainly E. curvula) and Sporobolus (S. pyramidalis. Where severe grazing is prolonged, spreading bristlegrass (Aristida congesta subsp. barbicollis) may eventually predominate. In contrast to what happens in the more arid bushveld areas, recovery of degraded veld in this region is relatively slow.Moist Zululand Thornveld
Acacia species, including Acacia karroo, A. nilotica, Acacia caffra, A. tortilis and A. sieberana, have increased, in some areas to thicket proportions, where grazing and fire management has not been effectively controlled. Scrub forest has increased in extent for similar reasons mainly on south-facing aspects.
Dry Zululand Thornveld (BRG 20)
The vegetation of the Dry Zululand Thornveld varies
from bushland thicket at lower elevations and, in the river valleys, to bushed
grassland at the highest elevations. The grassland is a mixed veld at the
highest elevations and is mixed to sweet at the lowest elevations, particularly
in the valley bottoms where it is transitional to Lowveld. An exception is the
sour veld found on quartzitic soils. Many of the typical Lowveld tree species,
such as Sclerocarya birrea, Acacia burkei and Phoenix reclinata
are found in these situations. The grassland in good condition is dominated by Themeda
triandra while Panicum maximum is dominant under trees. Bothriochloa
insculpta is found mainly on black clays, while Hyperthelia dissoluta
grows on well-drained sands and soils of granitic origin. Sporobolus
pyramidalis and Eragrostis curvula are dominant on overgrazed areas.
Common trees of this BRG include Acacia karroo, A. nilotica and Acacia tortilis. Acacia sieberana, often growing in woodlands, is an important indicator species of this BRG. Other trees include Acacia burkei, A. robusta, Combretum molle, Schotia brachypetala, Sclerocarya birrea, Euphorbia ingens and Spirostachys africana. Dichrostachys cinerea is a problem species, forming dense thickets in areas where the veld is in poor condition.
No benchmarks have been described for grassveld of these BRG’s. This is, no doubt, partly due to the considerable influence that landscape position (and therefore soil type) has on the nature of the grassveld. However, veld in good condition could broadly be expected to consist of the benchmark species abundances presented in Table 1 (bearing in mind that these proportions are estimated, and will vary widely according to landscape position). Table 1 also presents other grass species which occur in these Bioresource Groups, but are not necessarily found in the benchmark. The species groupings (i.e. Increaser and Decreaser species), and concepts related to this classification, are explained in detail in Production Guidelines 6.1 to 6.3 in this series.
Veld that consists predominantly of redgrass, with Panicum maximum (Guinea grass, ubabe) under the trees, is considered to be in excellent condition. Indicator species for the Zululand Thornveld vegetation type are presented together with their weightings in Table 2. These weightings can be used in the Weighted
Key Species method for assessing veld condition (refer to Production Guideline 6.2 in this series for a description of this method).
Neither sheep nor dairy cattle are suited to these warm areas. Sheep suffer from a variety of diseases, while the high temperatures and the extensive nature of farming do not suit dairy production. Beef and game farming are, however, well suited to the region. Because the veld is sweet, grazing is provided for the beef breeding herd throughout the year, without the need for supplementation. Livemass gains in steers will, where sufficient grazing is available, average as much as 0.6 kg/day through the year. Weaners of 240 to 260 kg can be produced at 8 to 9 months of age.
Goat farming is not popular in this region, but the potential for goats is relatively high where good browse is available. Goats will need to be provided with good sweetveld grazing in winter in those areas in which the majority of browse-producing plants are deciduous (i.e. lose their leaves in winter). Goats in these regions have two major advantages. Firstly, a browsing system is usually superimposed on a grazing system, and therefore major reductions in grazer stocking rates are unnecessary. This effectively increases the red meat production per unit area. Secondly, goats are able to control bush efficiently, and this reduces the management costs (e.g. bush control costs such as herbicides, fire, mechanical clearing - refer to Production Guideline 7.7 in this series).
The bushveld areas of KwaZulu-Natal therefore have much potential for extensive animal production. Due to the nature of the vegetation, however, maximal animal production can be achieved only in conjunction with good veld management.
VELD MANAGEMENT NORMS AND GENERAL INFORMATION FOR BRG’s 19 & 20: MOIST AND DRY ZULULAND THORNVELD
|
BRG 19 |
BRG 20 |
||
|
Total area (1 000 ha) Area of veld (1 000 ha) Potential grazing capacity (ha/AU) Current grazing capacity (ha/AU) Grazing season (days) Grazing cycle (days) Period of stay (days) Period of absence (days) AU grazing days per hectare Expected intake (kg/AU/annum) Livestock production potential (kg livemass per ha/annum) Excellent condition veld (90%) Moderate condition veld (60%) Poor condition veld (30%) |
74 52 1.9 2.7 300 63 21 42 148 3 000
55 37 18 |
301 216 2.3 4 300 63 21 42 101 3 000
50 33 17 |
|
|
Rested area |
Each camp should be rested once every four to six years |
||
|
Winter grazing |
Licks are required when grazing rested veld in winter |
||
|
Animal types |
Cattle (high potential); Sheep (low potential) Goats (moderate potential) |
||
|
Burning |
Burn to remove moribund and excess herbage and to control bush canopy |
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1 In areas where stocking rates are higher than those given for potential grazing capacity, the livestock production potential will not be achieved. This is particularly so where continuous grazing is practiced.
2 Current grazing capacity is based on the average condition of veld in the BRG as estimated in 1997.
3 Animal Unit (AU) grazing days per hectare are based on the estimated average CGC of the BRG.
4 Livestock production potential refers to the expected amount of live mass (kg) gain per hectare using a beef weaner production system (see the example of such a system in Production Guideline 2.6).
Table 1. Benchmark species abundances and species not occurring in the benchmark for grassland in Moist (BRG 19) and Dry (BRG 20) Zululand Thornveld.
|
Scientific name |
Common name |
Relative abundance (%) |
|
|
BRG 19 |
BRG 20 |
||
|
Increaser Ib Hyperthelia dissoluta |
Yellow thatchgrass |
|
|
|
Increaser Ia Cymbopogon excavatus Cymbopogon plurinodis Trachypogon spicatus Tristachya leucothrix |
Common turpentine grass Bushveld turpentine grass Giant speargrass Tridentgrass |
1 1 1 13 |
1 2 0 5 |
|
Decreaser Bracharia serrata Digitaria eriantha Diheteropogon amplectens Eustachys paspaloides Panicum maximum Setaria incrassata Themeda triandra |
Velvet signalgrass Finger grass Broadleaved bluestem Fan grass Guinea grass Vlei bristlegrass Redgrass, rooigras |
1 1
1 9
44 |
2
2 14 2 48 |
|
Increaser IIa Chloris gayana Eragrostis capensis Heteropogon contortus |
Rhodes grass Heartseed lovegrass Speargrass |
2 |
4 |
|
Increaser IIb Bothriochloa insculpta Eragrostis curvula Eragrostis racemosa Eragrostis superba Hyparrhenia hirta Setaria sphacelata Sporobolus pyramidalis Sporobolus fimbriatus |
Pinhole grass Weeping lovegrass Narrow-heart lovegrass Sawtooth lovegrass Common thatchgrass Golden setaria Catstail dropseed Bushveld dropseed |
2 4 2 4 5 1
|
1 3 4 5
1 1 |
|
Increaser IIc Aristida congesta subsp. barbicollis Cynodon dactylon Forbs Sedges |
Spreading bristlegrass Couch grass
|
1
4 2 |
3 1 |
|
Increaser III Aristida junciformis Elionurus muticus |
Ngongoni Wire lemongrass |
1 |
1 |
Table 2. Proposed key grass species and species weightings for grassland in Zululand Thornveld (BRG’s 19 & 20).
|
Scientific name |
Common name |
Species weighting |
|
Cynodon dactylon Hyparrhenia hirta Sporobolus pyramidalis Eragrostis curvula Heteropogon contortus Themeda triandra Tristachya leucothrix |
Couch grass Common thatchgrass Catstail dropseed Weeping lovegrass Speargrass Redgrass, rooigras Tridentgrass |
1 2 3 4 6 9 10 |