African
Journals Online
African Journal of Range & Forage Science
VOLUME 20 ISSUE 1 (2003)
ABSTRACTS
African Journal of Range &
Forage Science 2003, 20: 1–10
©2003 NISC Pty Ltd, www.nisc.co.za
Medium-term changes in grass composition and
diversity of Highland Sourveld grassland in the southern Drakensberg in
response to fire and grazing management
AD Short1, TG
O’Connor1, 2* and CR Hurt3
1 Tim O’Connor and Associates
CC, PO Box 379, Hilton 3245, South Africa
2 Centre for African Ecology,
School of APES, University of the Witwatersrand, Private Bag 3, PO WITS 2050,
Johannesburg, South Africa
3 ARC–Range and Forage
Institute, PO Box 1190, Hilton 3245, South Africa
* Corresponding author, e-mail:
[email protected]
Received 23 September 2002,
accepted 2 December 2002
This study examined the
compositional stability of Highland Sourveld in response to fire and grazing by
wildlife (Coleford Nature Reserve) and by cattle on three properties over 20–25
years. A limited amount of compositional change took place except on a property
stocked 1.5 times as heavily as the others, but no species were lost. In
general, Decreaser species decreased and Increaser 2 species increased,
although individual species of a group did not show a consistent pattern of
change in abundance. Consistent heavy grazing favoured mtshiki species (Sporobolus
africanus, Eragrostis plana), stoloniferous species (Paspalum notatum)
and Alloteropsis semialata. The extent of compositional change was least
at an intermediate (0.4 versus 0.1–0.75AU ha-1) stocking density.
Clovelly soils were prone to twice as much change as Hutton or Mispah soils. On
lands abandoned for >50 years, the dominant E. curvula declined by
two thirds and small amounts of characteristic Highland Sourveld species
established. Infrequent burning (every six years) resulted in twice as much
compositional change as annual burning. Ordination techniques revealed three
main groups of species, in terms of their amount and direction of change,
identifiable with the Increaser-Decreaser classification. Important
contradictions were, however, evident, such as a similar response for the
Decreaser Themeda triandra and the Increaser 2 Diheteropogon
filifolius, indicating review of this classification is warranted for the
Highland Sourveld. Changes in composition reflected changes in grass diversity
(evenness, species richness, Shannon-Weaver diversity). Heavy grazing increased
evenness, hence Shannon-Weaver diversity, through reducing the mono-dominance
of T. triandra. Grazing-induced changes in grassland composition may
therefore reflect the conservation status of grasslands
Keywords: Coleford Nature Reserve,
diversity, monitoring, montane
African Journal of Range &
Forage Science 2003, 20: 11–19
©2003 NISC Pty Ltd, www.nisc.co.za
Soil and vegetation changes across a Succulent
Karoo grazing gradient
PC Beukes1* and F
Ellis2
1 Department of Nature
Conservation and Oceanography, Cape Technikon, PO Box 652, Cape Town 8000,
South Africa
2 Department of Soil Science,
University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
* Corresponding author,
address: Dexcel Ltd, Private Bag 3221, Hamilton, New Zealand, e-mail:
[email protected]
Received 10 July 2002, accepted
22 November 2002
This study describes soil and
vegetation changes radiating out from a central watering point on a livestock
farm in the Succulent Ceres Karoo (Tanqua). The aim was to identify possible
relationships between long-term grazing pressure, and soil and vegetation
properties. There are indications that continuous high-intensity defoliation of
Succulent Karoo vegetation leads to a decline in species richness and perennial
plant cover with a consequent loss of fertile topsoil. Over-grazed areas close
to the watering point had shallow soils with a greater potential for crusting
and therefore poorer water capacity. Mainly short-lived succulents
(Mesembryanthemaceae) were recorded here, while under-utilised veld far from
the watering point was identified by plant groupings dominated by Antimima
hantamensis and Ruschia spinosa. Malephora crassa and Rhinephyllum
macradenium are two key species which could be useful in veld condition
assessment since they showed strong relationships with distance from the
watering point. The results also have implications for restoration of degraded
veld. Soils from degraded areas have been altered almost permanently and simply
resting from livestock grazing may not achieve the desired vegetation recovery.
Keywords: biodiversity, indicator
species, piosphere, restoration, veld condition
African Journal of Range & Forage
Science 2003, 20: 21–27
©2003 NISC Pty Ltd, www.nisc.co.za
The coppicing ability of Acacia erubescens
and Combretum apiculatum subsp. apiculatum in response to cutting
GN Smit
Department of Animal, Wildlife
and Grassland Sciences, University of the Free State, PO Box 339, Bloemfontein
9300, South Africa
e-mail: [email protected]
Received 12 April 2001,
accepted 21 November 2002
The investigation was conducted
in the Limpopo Province of South Africa. Twenty single stemmed trees of both Acacia
erubescens and Combretum apiculatum subsp. apiculatum were
randomly selected and five trees of each species were cut at heights of 5cm,
15cm, 30cm and 45cm above ground level. At the end of the following five
growing seasons leaf dry mass estimates were calculated using the BECVOL-model.
Both species coppiced vigorously, but C. apiculatum achieved a higher
leaf dry mass production (mean of 875g tree-1) in comparison to A.
erubescens (mean of 608g tree-1). In the case of A. erubescens
the leaf dry mass production at the end of the 5-year trial period varied from
a minimum of 460g tree-1 at a cutting height of 5cm to a maximum of
768g tree-1 at a cutting height of 15cm. In the case of C. apiculatum it
varied from a minimum of 668g tree-1 at a cutting height of 15cm to
a maximum of 1 074g tree-1 at a cutting height of 30cm. The effect
of the cutting height on the subsequent height of the coppice growth differed
between the two species. In the case of A. erubescens the total height
of the coppice growth differed significantly between plants that were cut at
different heights, but not in the case of C. apiculatum. The cutting
height had no significant effect on the leaf dry mass production of both
species. Despite the lack of statistically significant differences, the leaf
dry mass production tended to be higher with an increase in cutting height.
Depending on the cutting height, the A. erubescens trees will regrow to their
original leaf biomass (average of 1 429.7g tree-1) within 5.9 to 9.4
years (seasons) and the C. apiculatum trees (average of 1 748.9g tree-1)
within 7.1 to 15.8 years (seasons).
Keywords: browsers, bush encroachment,
leaf dry mass production, savanna, tree thinning
African Journal of Range &
Forage Science 2003, 20: 29–39
©2003 NISC Pty Ltd, www.nisc.co.za
Fire and the dynamics of semi-arid grassland:
influence on plant survival, productivity and water-use efficiency
HA Snyman
Department of Animal, Wildlife
and Grassland Sciences, University of the Free State, PO Box 339, Bloemfontein
9300, South Africa
e-mail: [email protected]
Received 15 April 2002,
accepted 30 November 2002
There is a lack of knowledge
concerning the effect of fire behaviour on the vegetation dynamics of semi-arid
climates. Arising from this, an investigation was initiated to characterise the
behaviour of fires burning with the wind (head fire) and against the wind (back
fire). The behaviour of these fires was related to the response of the
vegetation by monitoring the recovery and productivity of the grass sward after
only one burn over a two year period (2000/01 to 2001/02 seasons). The results
showed that head fires had significantly greater flame height and rate of
spread than back fires. However, at ground level back fires were more intense
and had a negative effect on recovery of the grasses, resulting in lower
litter, yield and water-use efficiency (aboveground phytomass or crude protein
produced per unit of evapotranspiration). Fire had a significant effect on
plant density and cover, with basal cover 68% lower than that of unburnt
grassland two months after the fire. Cymbopogon plurinodis with large
tufts had the most die-back of all the species. With the exception of plant
cover and density, which takes longer to recover, it takes approximately two
complete growing seasons to recover from most of the detrimental effects of
fire. The initial increased crude protein content of the plant material caused
by fire did not off set the approximately 50% reduction in plant production the
first growing season after the fire. Fire significantly decreased WUE
(water-use efficiency), with an average over the two growing seasons of 3.06kg
ha-1 mm-1 and 2.45kg ha-1 mm-1 for unburnt and
burnt grassland respectively. In various semi-arid grassland areas, the use of
fire as a management tool is questionable if there is no specific purpose for
it.
Keywords: back and head fires, basal
cover, crude protein content, grass sward recovery, tuft mortality
African Journal of Range &
Forage Science 2003, 20: 41–45
©2003 NISC Pty Ltd, www.nisc.co.za
Impact of water stress on growth reserves and
re-growth of Themeda triandra (Forssk) following defoliation
IB Oosthuizen* and HA Snyman
Department of Animal, Wildlife
and Grassland Sciences, University of the Free State, PO Box 339, Bloemfontein
9300, South Africa
* Corresponding author, e-mail:
[email protected]
Received 22 January 2002,
accepted 20 October 2002
The influence of water stress
and defoliation on the concentration of total non-structural carbohydrates
(TNCC) and water-soluble protein (WSPC) as growth reserves after defoliation
were determined in the indigenous C4 semi-arid grass species Themeda
triandra during three growth stages (vegetative, piping and reproductive)
and in three plant parts (roots, stubble and leaves). Four water stress
treatments (T1 = 0–25%, T2 = 25–50%, T3 = 50–75% and T4 = 75–100% depletion of
plant available water) were applied to the plants in pots in a glasshouse. The
TNCC declined drastically after severe defoliation over all the water
treatments (P < 0.05), in all the plant parts (P < 0.05) and for all the
growth stages (P < 0.05), while the TNCC did not recover (P < 0.05) (to
the TNCC values as before defoliation) within 6 days after defoliation. The
WSPC in the leaves increased from after defoliation, up to day 6 over all the
water treatments (P < 0.05) and for all the growth stages (P < 0.05).
Non-structural carbohydrates serve as the most important growth reserve and are
utilised for re-growth after severe defoliation. Water-soluble protein can also
be utilised as growth reserve, but only as an emergency measure for up to two
days after defoliation. These results could make a meaningful contribution to
ensure sustainable utilisation of the grassland ecosystem in semi-arid areas.
Keywords: growth reserve, growth stages,
translocation, water-soluble protein, water stress
African Journal of Range &
Forage Science 2003, 20: 47–51
©2003 NISC Pty Ltd, www.nisc.co.za
Composition of colostrum and milk of South
African indigenous Nguni goats grazing natural pasture and supplemented
with concentrate
AA Akingbade1*, IV
Nsahlai2 and CD Morris3
1 Department of Animal
Production & Health, Ladoke Akintola University of Technology, Ogbomoso,
Oyo State, Nigeria
2 Discipline of Animal and
Poultry Science, University of Natal, Scottsville 3209, South Africa
3 Range and Forage Institute,
Agricultural Research Council, Scottsville 3209, South Africa
* Corresponding author, e-mail: [email protected]
Received 10 June 2002, accepted
21 November 2002
Samples of colostrum, early and
late lactation milk from thirteen South African indigenous Nguni goats
(SAING) were analysed for contents of total solids (TS), solids-not-fat (SNF),
fat, protein, lactose, ash and energy. Relationships between colostrum or milk
and some parameters such as litter size (LS), milk yield (MY) and does kidding
weight (DKW) were determined. Fat, protein and lactose contents of colostrum
were poorly correlated (P > 0.05) with LS. Of relationships between early
lactation parameters considered, only the coefficient between MY and DKW was
significant (r = 0.72, P < 0.001). Correlations between protein and lactose
contents of late lactation milk and LS were not significant (P > 0.05).
However, the milk fat content of late lactation milk was significantly
correlated with LS (r = 0.23, P = 0.041). Means of TS, SNF, fat and energy
contents decreased with increased lactation period while ash content increased
as lactation advanced. Protein and lactose contents were at maximum in
colostrum and early lactation milk, respectively. Fat and TS contents of
colostrum, early and late lactation milk samples were positively and
significantly (P < 0.05) correlated. Fat content of colostrum and milk of
SAING can be used to predict the dry matter (total solids) constituent of the
goats’ colostrum and milk.
Keywords: Nguni goats, colostrum,
milk, composition, natural pasture
African Journal of Range &
Forage Science 2003, 20: 53–57
©2003 NISC Pty Ltd, www.nisc.co.za
Effects of sowing rate on growth and protein
contents of wall barley (Hordeum murinum L.) grown under Mediterranean
conditions
MKJ El-Shatnawi1*, M
Turk2 and HM Saoub3
1 Natural Resources and the
Environment Department, Faculty of Agriculture, Jordan University of Science
and Technology, PO Box 3030, Irbid, Jordan
2 Plant Production Department,
Faculty of Agriculture, Jordan University of Science and Technology, PO Box
3030, Irbid, Jordan
3 Faculty of Agriculture,
University of Jordan, Amman 11942, Jordan
* Corresponding author, e-mail:
[email protected]
Received 9 December 2001,
accepted 18 December 2002
Accurate control of the seeding rate
favours the establishment of a high-quality stand. Improper seeding rates waste
seed and reduce potential yield. Our objective for this research is to
determine the proper sowing rate for wall barley (Hordeum murinum L.) to
obtain optimum and sustainable forage and seed yield in the northeastern
depleted rangelands of Jordan. Wall barley seeding rates of 10kg ha-1,
20kg ha-1, 30kg ha-1 and 40kg ha-1 were
evaluated in field studies that were conducted for two years at Ramtha
Agricultural Research Station (32°33’N 36°0’E) located 22km to the east of
Irbid. Measurements recorded each year included plant height, number of tillers
per plant, oven-dry forage weight, seed yield and protein content. Forage and
seed production increased in response to increasing sowing rate, and was
highest at a sowing rate of 30kg ha-1. Tiller numbers showed a
negative response to increasing sowing rate. Plant height and crude protein
content did not respond to seeding rate, but they varied with years (P £ 0.05). Protein content did not respond to seeding rates. The
highest forage and seed yield of wall barley was obtained at 30kg ha-1
seeding rate.
Keywords: annual grasses, forage
production, plant height, tiller number, seed yield
African Journal of Range &
Forage Science 2003, 20: 59–62
©2003 NISC Pty Ltd, www.nisc.co.za
Effect of Acacia tortilis pods on intake,
digestibility and nutritive quality of goat diets in southwestern Eritrea
Mengistu R Araya1, Robinson K
Ngugi2, Nashon KR Musimba2 and Dickson M Nyariki2
1 Ministry of Agriculture,
Research and Extension Department, PO Box 4627, Asmara, Eritrea
2 University of Nairobi,
Department of Range Management, PO Box 29053, Nairobi, Kenya
Received 13 May 2002, accepted
8 January 2003
Fresh Acacia tortilis
pods were mixed with low quality native grass hay to form the following five
rations: 100% hay (T1), 25% pods and 75% hay (T2), 50%
pods and 50% hay (T3), 75% pods and 25% hay (T4) and
100% pods (T5) on ‘as fed’ weight basis. Fifteen male Barka
goats, approximately one year old and 10–15kg body weight, were randomly
assigned to the five rations and fed in individual pens. Chemical composition,
dry matter intake (DMI), in vitro dry and organic matter digestibility
and body weight changes of the animals were evaluated. The average crude
protein content of the pods was about 47% higher than the 7% minimum required
for normal rumen function, while that of the hay was about 13% below. Percent
ash, neutral detergent fibre (NDF), acid detergent fibre (ADF), hemi-cellulose
(HC), cellulose (CL) and acid detergent lignin (ADL) contents were higher in
the hay than in the pods. The pods were, however, generally higher in Ca, P, Mg
and Na than the hay. Average DMI (g d-1 and g kg-1 LBW),
percent in vitro dry and organic matter digestibility and body weight gains
(total kg and gd-1) increased with an increase in A. tortilis
pods, up to 75% level and then begun to decline. However, despite the decrease,
T5 still had significantly (P < 0.05) higher feed digestibility
and body weight gains than T2 and T3. Thus, supplementing
low quality range herbage with Acacia pods can considerably improve the
nutritive value of range livestock diets, particularly during the dry season
when other types of fodder are of extremely low quality.
Keywords: Acacia pods, Barka
goat diet, range forage, pastoralists, semi-arid Eritrea
African Journal of Range &
Forage Science 2003, 20: 63–68
©2003 NISC Pty Ltd, www.nisc.co.za
Country Perspective
Status of range and forage research in
Mozambique
Inácio C Maposse*, James P Muir
and Albertina A Alage
Universidade Eduardo Mondlane,
Faculdade de Agronomia e Engenharia Florestal, CP 257, Maputo, Mozambique
* Corresponding author, e-mail:
[email protected]
Received 14 August 2002,
accepted 24 January 2003
Domestic ruminant production in
Mozambique is limited by a long dry season and lack of a well-defined breeding
season to match forage supply. To date, research on pasture and forages has
concentrated mainly on range vegetation mapping, forage adaptation and
production from small plots. Little research has been conducted on animal
production per se, despite numerous projects focusing on animal health. A key
to sustainable use of forage resources will require, among other aspects, the
determination of pasture productivity and long-term carrying capacity using
animal output and land conservation parameters, maximum use of local resources
including local seed production, improved use of crop residues and the
integrated use of native flora and fauna.
Keywords: range, forage, pasture,
Mozambique
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