agricultural production guidelines
m
Veld in KwaZulu-Natal
Co-ordinated Extension KwaZulu-Natal Veld 4.10 1999
BIORESOURCE GROUPS 21, 22 AND 23: VALLEY BUSHVELD, LOWVELD AND SANDY BUSHVELD
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
These regions have traditionally been used as winter grazing areas, particularly for beef and, increasingly, for game. In recent times, however, intensification has seen the production of sisal, pineapples and cotton under dryland conditions, and cotton, together with citrus and forage crops, under irrigation.
The Valley Bushveld is found in the hot valleys of the major rivers of the Province. These are the Mtamvuna, in the extreme south, the Mzimkulu, Mkhomazi, Mlazi, Mgeni, Mvoti, Thukela and the Mhlatuze rivers. The topography of this BRG is mainly steep and rugged with the occasional flat to gently sloping valley bottom.Valley Bushveld (BRG 21)
Lowveld (BRG 22)
The Lowveld has a more tropical character than the Valley Bushveld and generally has a less rugged terrain. It lies mainly north of the White Mfolozi River, with small areas to the south of the river, and extends to KwaZulu-Natal's border with Swaziland and Mozambique. The topography is mainly flat to undulating with the occasional hill. However, this BRG also extends up both the eastern and western slopes of the Ubombo mountain range and on the steep slopes in an area west of the Hluhluwe-Mkuzi road. The boundary between the Lowveld and the Dry Zululand Thornveld (BRG 20) is not clear. In the area of Magudu the break in terrain from undulating hills to the steeply rising hills west of Magudu has been taken as the border between the two BRG’s. Here the presence of Acacia sieberana indicates the change to Dry Zululand Thornveld.Sandy Bushveld (BRG 23)
Sandy Bushveld is found on the Maputoland plain and stretches from the Mozambique border in the north, and to the western shores of False Bay in the south. The Lowveld (BRG 22) lies to the west and the Dry and Moist Coast (BRG’s 1 & 2) lie to the east. This BRG falls in a single area and no sub-groups exist. Elevation ranges from 0 m (shores of False Bay) to 152 m.
VEGETATION STRUCTURE AND COMPOSITION
The vegetation of these areas is mainly a savanna of varying tree and bush density.
The vegetation is characterized by an open to dense scrub forest containing many species of Euphorbia.Valley Bushveld (BRG 21)
Semi-deciduous bush is found in the dry, hot areas of the valleys. The vegetation in most of these areas has been altered by severe disturbance (overgrazing and cultivation) and this has caused a break down in the natural resources. Pioneer species dominate and erosion is severe with extensive areas eroded to the parent material.
Many species are deciduous during the winter but species like Boscia albitrunca, Euclea crispa, E. schimperi and Olea europaea subsp. africana remain evergreen. Acacia species such as Acacia robusta, A. karroo, A. nilotica, A. tortilis, A. gerrardii and A. ataxacantha are common. A major contributor to the problem of bush encroachment is Acacia tortilis, and this species forms dense thickets, particularly on abandoned lands at lower elevations.
The climax grasses are Themeda triandra var. trachyspathea, Heteropogon contortus, Bothriochloa insculpta, Setaria incrassata (the latter two on black clays) and Cymbopogon plurinodis. In the shade the dominant grasses are Panicum maximum and P. deustum. Subclimax grasses include Eragrostis curvula, E. chloromelas, and Digitaria spp. Species found in the severely overgrazed areas are Aristida congesta, A. diffusa, Chloris virgata, Melinis repens, Tragus beteronianus and Urochloa mosambicensis.
Mixed succulent scrub is found on dry, north-facing aspects on shallow soils. These areas have a low rainfall and are relatively free of frost. A Euphorbia tirucalli community grows on arid, alkaline soils. Thickets occur, often on old lands, from which other species are excluded. Euphorbia triangularis frequently grows in association with Euphorbia tirucalli on dry, north facing aspects and tends to grow in a belt across the slope. Basal cover is very poor and Panicum maximum and P. deustum provide sparse cover. Euphorbia ingens grows on frost free slopes and on the floors of the lower valleys where frost does not occur.
Combretum apiculatum Tree veld grows on shallow, rocky soils on dry north-facing aspects. It is typically an open woodland but overgrazing has resulted in an invasion by species such as Euphorbia tirucalli, E. grandicornis, E. pseudocactus and Acacia species.
Sclerocarya-Acacia Tree Veld grows at elevations below 600 m in an area of light frosts, with moderately severe frosts occurring occasionally. Soils are generally deep. The dominant tree is Sclerocarya birrea while Acacia sieberana is found at the upper elevational range. Disturbance has resulted in an increase in Acacia nilotica, A. tortilis and Dichrostachys cinerea.
The grass layer is dominated by secondary species due to disturbance and the commonest grasses are Aristida congesta var. barbicollis, Bothriochloa insculpta, Chloris gayana, C. pycnothrix, C. virgata, Cymbopogon plurinodis, Cynodon dactylon, Eragrostis chloromelas, E. racemosa, E. superba, Heteropogon contortus, Melinis repens, Melinis nerviglumis, Panicum maximum, Perotis patens, Setaria incrassata, Setaria sphacelata, Sporobolus fimbriatus, Sporobolus pyramidalis, Themeda triandra var. trachyspathea, Tragus berteronianus, Trichoneura grandiglumis and Urochloa mosambicensis.
Spirostachys Woodland occurs mainly on hot, dry north-facing aspects and is particularly extensive in the Mvoti and Mgeni River valleys. Erosion is severe, mainly on colluvial and alluvial soils which are neutral to alkaline. The vegetation is severely disturbed and the woodland has been generally replaced by secondary vegetation with relic trees remaining.
The dominant grasses indicate the severe disturbance. They include Aristida barbicollis, Bothriochloa insculpta, Cynodon dactylon, Eragrostis superba, Melinis repens, Melinis nerviglumis, Tragus beteronianus and Urochloa mosambicensis. The climax grasses are presented by Cymbopogon plurinodis, Heteropogon contortus and Themeda triandra var. trachyspathea.
Lowveld (BRG 22)
The characteristic vegetation of the Lowveld is an Acacia
nigrescens-Sclerocarya-Themeda Savanna. The dominant, emergent trees which
characterise the Lowveld are Acacia nigrescens, A. tortilis, Schotia
brachypetala, Spirostachys africana, Sclerocarya birrea and Acacia burkei.
The vegetation pattern varies from open Combretum apiculatum-Acacia
nigrescens woodland to bushland thickets, the latter being particularly
dense along water courses. These thickets can include, or are often dominated by
species such as Dichrostachys cinerea, Maytenus senegalensis, Acacia nilotica,
A. karroo, A. senegal, Spirostachys africana, Euclea crispa and E.
divinorum.
On heavy clay soils the dominant grass species of the sweetveld are the tall form of Themeda triandra, Aristida bipartita, Bothriochloa insculpta, Cymbopogon excavatus, Digitaria spp., Diplachne eleusine, Eragrostis superba, Setaria incrassata and Sporobolus fimbriatus. Panicum maximum and Panicum deustum grow in the shade of trees.
Themeda triandra is less common on sandy soils where Aristida diffusa, Brachiaria nigropedata, Cymbopogon excavatus, C. plurinodis, Elionurus muticus, Eragrostis curvula, E. superba, Eustachys paspaloides, Heteropogon contortus, Hyparrhenia hirta, Panicum coloratum, Pogonarthria squarrosa and Sporobolus fimbriatus are among the common grass species.
Sandy Bushveld (BRG 23)
The vegetation patterns of this BRG vary considerably.
In the western portion patches of Sand Forest are found in a matrix of bushland
thicket, while areas of bushland and bushed grassland are found. Closer to the
coast, the vegetation changes to Palm Veld with pockets of bushland thicket,
bushland and bushed grassland. The Sand Forest has an upper canopy about 20 m
high with an average height of about 10 m.
Terminalia sericea, Combretum molle, Acacia burkei, Strychnos spp., and Albizia versicolor grow in the woodland areas. Grass cover is sparse and the species reflect the sandy nature of the soil including Hyperthelia dissoluta, Pogonarthria squarrosa and Perotis patens. Other grasses found are Aristida spp., Themeda triandra, Urochloa mosambicensis, Digitaria spp., and Aristida spp.
The Palm Veld, which lies to the east of the Sand Forest zone, also has a patchy appearance. The palms consist of Hyphaene natalensis and Phoenix reclinata in a bush clump grassland which includes Themeda triandra, Perotis patens, Eragrostis spp. and Aristida spp. amongst others. The trees, Mimusops caffra, Syzygium cordatum, Albizia adianthifolia, Acacia robusta, Spirostachys africana and Schotia brachypetala grow on drained raised ground. In the moist depressions grass-sedge com-munities are found.
Benchmark sites for the Valley Bushveld (BRG 21) and the Lowveld (BRG 22) are presented in Tables 1 and 2 respectively. Due to the considerable influence of landscape position on species composition in the Lowveld, benchmarks for upland, midslope and bottomland areas are presented in Table 2 for the Lowveld vegetation type. No benchmark has been described for the Sandy Bushveld (BRG 23). Tables 1 and 2 also present 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 Bioresource Groups 21 and 22 are presented together with their weightings in Table 3. 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 0.6kg/day through the year. Weaners of 240 to 260kg 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 21, 22 & 23: VALLEY BUSHVELD, LOWVELD AND SANDY BUSHVELD
|
BRG 21 |
BRG 22 |
BRG 23 |
||
|
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%) |
500 383 3.5 5.4 365 84 28 56 89 3 500
42 28 14 |
880 674 3.5 5.0 365 84 28 56 96 3 500
39 26 13 |
444 355 3.5 5.4 365 84 28 56 89 3 500
42 28 14 |
|
|
Rested area |
Each camp should be rested once every three to four years |
|||
|
Winter grazing |
Licks are not necessarily required when grazing rested veld |
|||
|
Animal types |
Cattle and Goats (high potential); Sheep (low potential) |
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|
Burning |
Burn to remove moribund and excess herbage, and to control the 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 practised.
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 Valley Bushveld (BRG 21).
|
Scientific name |
Common name |
Relative abundance (%) |
|
BRG 20 |
||
|
INCREASER Ib Hyperthelia dissoluta |
Yellow thatchgrass |
|
|
INCREASER Ia Cymbopogon plurinodis |
Bushveld turpentine grass |
2 |
|
DECREASER Digitaria eriantha Diheteropogon amplectens Eustachys paspaloides Panicum maximum Setaria incrassata Themeda triandra |
Finger grass Broadleaved bluestem Fan grass Guinea grass Vlei bristlegrass Redgrass, rooigras |
3
2 2
80 |
|
INCREASER IIa Chloris gayana Eragrostis capensis Eragrostis racemosa Heteropogon contortus |
Rhodes grass Heartseed lovegrass Narrow-heart lovegrass Speargrass |
2 |
|
INCREASER IIb Bothriochloa insculpta Eragrostis chloromelas Eragrostis curvula Eragrostis superba Hyparrhenia hirta Setaria sphacelata Sporobolus fimbriatus Sporobolus pyramidalis |
Pinhole grass Weeping lovegrass
Sawtooth lovegrass Common thatchgrass Golden setaria Bushveld dropseed Catstail dropseed |
1 2 2
1
1 1 |
|
INCREASER IIc Aristida congesta subsp. barbicollis Cynodon dactylon Forbs Sedges |
Spreading bristlegrass Couch grass
|
1 |
|
INCREASER III Elionurus muticus |
Wire lemongrass |
Table 2. Benchmark species abundances and species not occurring in the benchmark for grassland in Lowveld (BRG 22), in upland, midslope and bottomland sites.
|
Scientific name |
Common name |
Relative abundance (%) |
||
|
Upland |
Midslope |
Bottomland |
||
|
INCREASER Ib Hyperthelia dissoluta |
Yellow thatchgrass |
|||
|
INCREASER Ia Cymbopogon plurinodis |
Bushveld turpentine grass |
|||
|
DECREASER Cenchrus ciliaris Chloris mosambicensis Digitaria eriantha Diheteropogon amplectens Eustachys paspaloides Panicum coloratum Panicum maximum Sehima galpinii Setaria incrassata Themeda triandra |
Blue buffalo grass Perennial spiderweb grass Finger grass Broadleaved bluestem Fan grass White buffalo grass Guinea grass Yellow turfgrass Vlei bristlegrass Redgrass, rooigras |
3
2 7 9
1 70 |
1
1
4 5 12 2 3 60 |
2 2
5 12 3 8 48 |
|
INCREASER IIa Chloris gayana Eragrostis capensis Eragrostis racemosa Heteropogon contortus |
Rhodes grass Heartseed lovegrass Narrow-heart lovegrass Speargrass |
2 |
2 |
4 |
|
INCREASER IIb Bothriochloa insculpta Diplachne eleusine Eragrostis chloromelas Eragrostis curvula Eragrostis superba Hyparrhenia hirta Setaria sphacelata Sporobolus fimbriatus Sporobolus pyramidalis |
Pinhole grass Large scale grass
Weeping lovegrass Sawtooth lovegrass Common thatchgrass Golden setaria Bushveld dropseed Catstail dropseed |
1
1 1 2
1
|
1 3
1 2 1
2 |
1
1
3 |
|
INCREASER IIc Aristida congesta subsp. barbicollis Cynodon dactylon Sporobolus nitens Urochloa mosambicensis Forbs Sedges |
Spreading bristlegrass Couch grass Curly-leaved dropseed Bushveld signal grass
|
1
1 1 5 3 |
||
|
INCREASER III Elionurus muticus |
Wire lemongrass |
|||
Table 3. Proposed key grass species and species weightings for grassland in Valley Bushveld and Lowveld (BRG’s 21 & 22).
|
Scientific name |
Common name |
Species weighting |
|
Sporobolus nitens Sporobolus iocladus Urochloa mosambicensis Hyparrhenia hirta Eragrostis curvula Heteropogon contortus Themeda triandra Tristachya leucothrix |
Curly-leaved dropseed Pan dropseed Bushveld signal grass Common thatchgrass Weeping lovegrass Speargrass Redgrass, rooigras Tridentgrass |
1 1 2 3 4 6 9 10 |