agricultural production guidelines
m
Veld in KwaZulu-Natal
Co-ordinated Extension KwaZulu-Natal Veld 4.4 1999
BIORESOURCE GROUPS 5, 6 & 7: MOIST AND DRY MIDLANDS MISTBELT AND NORTHERN MISTBELT
N M Tainton
Professor Emeritus, University of Natal
K G T Camp
KwaZulu-Natal Department of Agriculture
Vegetation
Structure and Composition
Veld Benchmark
Animal Production
INTRODUCTION
Bioresource Groups 5 and 6 cover a region of broken topography which occurs in an interrupted belt along the Hilton escarpment from Eshowe in the north to the Transkei border in the south (refer to Figure 1 in Production Guideline 4.1 in this series). The area has undergone a great deal of intensification, particularly into pastures and timber. Such intensification is likely to continue because of the favourable conditions for plant growth during summer, and the poor nature of the natural veld. Only the generally broken topography is likely to set a limit to the extent to which this area will be intensified.
The Northern Mistbelt (BRG 7) occurs in three separate areas. The northern-most area straddles the Vryheid-Pongola road and includes the town of Louwsburg. To the south is a more extensive area lying on top of the Ngome mountains with a small separate area to the west of this range.
VEGETATION STRUCTURE AND COMPOSITION
Most of the area has the potential to develop into evergreen forest because of the favourable moisture conditions experienced during the summer months. Today, such forest is largely restricted to the cool damp southern slopes and fire refuge sites. A number of moderately large forests occur in this region, including the Qudeni, Nkandla, Karkloof and Weza forests, together with numerous, small, scattered patches. Where these forests have not been cut-over for timber, Podocarpus species (yellowwoods) are common, together with a number of other forest emergents. Indeed, these forests are extremely rich in species. Included are a number of undergrowth forest grasses which, while remaining nutritious and palatable during the winter, provide relatively little grazing due to their sparse growth habit.
Much of this region is now occupied by open grassland. This grassland owes its very existence to the regular fires which have apparently occurred here for many years. It seems that it is defoliation by fire, rather than by grazing, which has maintained these grasslands. In a pristine state these grasslands are dominated by Themeda triandra (redgrass), but are extremely sensitive to even a moderate grazing pressure.
This veld is sour. It will support animal growth only during the summer months, after which it loses quality and its acceptability to grazing animals. Today very little veld in this region remains in good condition. In BRG’s 5 and 6 grazing, to which the grassveld is clearly not adapted, has converted much of the veld into a degenerate, Aristida junciformis ngongoni dominated community. In this state, its productive capacity is extremely low. Animals must search between the ngongoni tufts for acceptable forage from such species as Eragrostis curvula (weeping lovegrass), Sporobolus africanus (mtshiki) and Hyparrhenia hirta (common thatchgrass), none of which are particularly useful forage species, except in spring.
With poor grazing management veld in BRG 7 is not invaded with ngongoni but rather becomes dominated by the "mtshiki" species (i.e. Eragrostis curvula, E. plana, Sporobolus africanus and Sporobolus pyramidalis)and Hyparrhenia hirta. In this state the veld has a higher grazing capacity than degraded veld in BRG’s 5 and 6.
Where veld, in either benchmark or degenerate condition, remains undefoliated for any length of time, tall forest margin grasses such as Cymbopogon validus (turpentine grass), Miscanthus capensis (East-coast broomgrass) and tall species of Hyparrhenia invade, together with forest precursor shrubs such as Leucosidea sericea (ouhout), Buddleja salviifolia (sagewood) and others, and autumn forbs (Berkeya species and others). Such communities produce little useful forage, but they do provide the useful functions of protecting the fringes of the forests from fires, and providing useful refuge sites for game.
Benchmark species abundances are included in Table 1 (note that while the benchmark species composition for BRG 5 is relatively well understood the benchmarks provided for BRG’s 6 and 7 are based on experience and must therefore be regarded as best approximations until research provides more information on the vegetation of these BRG’s). In addition, Table 1 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.
Key grass species (which are used for monitoring veld condition) have not been objectively determined for the grasslands in these BRG’s. However, experience and research suggest that the species and weightings presented in Table 2 can be used in the Weighted Key Species method for determining veld condition (refer to Production Guideline 6.2 in this series for a description of this method).
Livestock production off veld is restricted largely to beef, although some sheep are farmed on the veld in these Bioresource Groups. Where veld is in good condition it is relatively productive through summer, but in winter it is both unpalatable and indigestible, and provides no useful forage.
As indicated previously, the veld in BRG’s 5 and 6 is prone to invasion by ngongoni. As it invades, grazing pressure on the palatable grasses increases. This process eventually kills the palatable grasses and provides a competition-free environment for the continued invasion of ngongoni. The sward which eventually results is virtually ungrazeable, except for a short period in the spring after burning. For much of the season, therefore, the animals must survive on what palatable species have been able to persist between the ngongoni tufts, and thus the productivity of such communities is extremely low.
It seems clear that the veld in these Bioresource Groups is never likely to play an important role in animal production except on rocky or steep terrain where intensification is not practical. Much of the area is destined for intensification or improvement in the years ahead.
VELD MANAGEMENT NORMS AND GENERAL INFORMATION FOR BRG’s 5, 6 & 7: MOIST AND DRY MIDLANDS MISTBELT AND NORTHERN MISTBELT
BRG 5
BRG 6
BRG 7
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%)
520
58
1.5
2.5
250
30
10
20
134
2 500
87
58
29
48
5
1.7
2.8
250
30
10
20
119
2 500
64
43
21
31
4
1.5
2.2
250
30
10
20
151
2 500
87
58
29
Rested area
Each camp should be rested once every four years
Winter grazing
Licks are required when grazing rested veld in winter
Animal types
Cattle (high potential); Sheep (moderate potential); Goats (low potential)
Burning Burn to remove moribund and excess herbage 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 the Moist (BRG 5) and Dry (BRG 6) Midlands Mistbelt, and the Northern Mistbelt (BRG 7).
Scientific name
Common name
Relative abundance (%)
BRG 5
BRG 6
BRG 7
Increaser Ib
Hyparrhenia dregeana
Miscanthus capensis
Blue thatchgrass
East-coast broomgrass
Increaser Ia
Alloteropsis semialata
Cymbopogon excavatus
Digitaria diagonalis
Digitaria natalensis
Digitaria tricholaenoides
Eulalia villosa
Setaria nigrirostris
Trachypogon spicatus
Tristachya leucothrix
Blackseed grass
Common turpentine grass
Brownseed finger grass
Coast finger grass
Purple finger grass
Golden velvetgrass
Large seed setaria
Giant speargrass
Tridentgrass
2
1
1
1
2
18
1
1
1
1
16
2
1
3
20
Decreaser
Andropogon schirensis
Bracharia serrata
Diheteropogon amplectens
Monocymbium ceresiiforme
Themeda triandra
Velvet signalgrass
Broadleaved bluestem
Wild oatgrass
Redgrass, rooigras
1
2
2
45
1
1
48
1
1
5
35
Increaser IIa
Eragrostis capensis
Harpochloa falx
Heteropogon contortus
Heartseed lovegrass
Catterpillar grass
Speargrass
2
2
3
4
5
2
2
4
Increaser IIb
Eragrostis curvula
Eragrostis plana
Eragrostis racemosa
Hyparrhenia hirta
Loudetia simplex
Setaria sphacelata
Sporobolus africanus
Weeping lovegrass
Fan lovegrass
Narrow-heart lovegrass
Common thatchgrass
Russet grass
Golden setaria
Ratstail dropseed
1
1
1
1
1
1
1
2
4
1
1
1
1
1
1
1
Increaser IIc
Microchloa caffra
Paspalum scrobiculatum
Forbs
Sedges
Pincushion grass
Veld paspalum
1
1
5
2
2
1
3
2
1
3
5
2
Increaser III
Aristida junciformis
Diheteropogon filifolius
Elionurus muticus
Rendlia altera
Ngongoni
Wire bluestem
Wire lemongrass
Toothbrush grass
2
1
1
2
1
1
1
1
3
2
Table 2. Proposed key grass species and species weightings for grassland in the Moist (BRG 5) and Dry (BRG 6) Midlands Mistbelt and Northern Mistbelt (BRG 7).
Scientific name
Common name
Species weighting
Aristida junciformis
Paspalum scrobiculatum
Sporobolus africanus
Eragrostis curvula
Eragrostis plana
Heteropogon contortus
Themeda triandra
Tristachya leucothrix
Ngongoni
Veld paspalum
Ratstail dropseed
Weeping lovegrass
Fan lovegrass
Speargrass
Redgrass, rooigras
Tridentgrass
1
1
2
3
3
4
9
10