Bibliography: Land Degradation in South Africa project

survey per experimental camp were classified into perennial grass and shrubs.

The increase and decrease in these components over the years are shown in figure

1 A to F. The rainfall for the periods September to February (favouring grass)

and March to August (favouring shrubs) were calculated . The accumulative

departure, from the long term averages of these seasonal rainfalls were plotted

as shown in figure 1,G. These graphs showed that the "grass rains" became more

favourable from 1950 and remained favourable until 1959. From 1960 to 1965 this

seasonal rainfall was of a sporadic nature. In contrast, the "shrub rains"

became less favourable from 1949 and remained unfavourable until 1960 after

which it became more favourable. From the graphs the close relationship between

the seasonal rainfall and its effect on the two main components, grass and

shrubs, can be clearly seen. It can also be seen that irrespective of the

treatment applied the vegetation components show similar trends. These

fluctuations in the vegetation, as brought about by the fluctuations in the

seasonal rainfall are regarded to be one of the main causes of the instability

and dynamic nature of the vegetation of the Eastern Mixed Karoo.

Ref ID : 2254

1697. Roux, P.W. Principles of veld management in the Karoo and the adjacent dry

sweet-grass veld. In: The small stock industry in South Africa, edited by Hugo,

W.J.Pretoria:Government Printer, 1968,p. 318-340.

Reprint : Not in File,

Keywords : VELD MANAGEMENT

Ref ID : 206

1698. Roux, P.W. Vegetation change in the Karoo region. Karoo Agric 1(5):15-16,

1980.

Reprint : In File,

Keywords : VEGETATION CHANGE; KAROO DESERTIFICATION; GRAZING EFFECTS;

ENVIRONMENTAL HISTORY

Notes : The author has come to the conclusion that desert encroachment, as a

natural propcess, cannot be regarded as an important ecological factor operating

in the Karoo region. In spite of the relative paucity of data on vegetational

change and related aspects, it appears that vegatational change in the Karoo

Region took place in three broad overlapping, but recognizable serial phases of

desertification. This paper describes these phases, and suggests a fourth phase

of progression, characterised by the present.

Ref ID : 343

1699. Roux, P.W. Interaction between climate, vegetation and runoff in the

Karoo. Maaren, H. Department of Water Affairs:Pretoria. TR113:90-101, 1981.

Reprint : In File,

Keywords : SOIL EROSION; HYDROMETEOROLOGY; VELD CONDITION; CLIMATE; RUNOFF; LAND

USE; EROSION

Notes : The author concludes that, from the notes it should be clear that land

use, especially that of the extensive grazing lands and their utilization by

domestic stock, has the most far-reaching effect on run-off and erosion. It

should ever be borne in mind that the manipulation of the grazing animal in veld

utilization strategies has by far the greatest effect on vegetation and run-off

and erosion than any other environmental factor.

Ref ID : 865

1700. Roux, P.W. The general condition of the veld in the Republic of South

Africa. In: Save our soil. Proceedings of the Veld Trust Conference on the

conservation status of agricultural resources in the RSA, Pretoria, edited by

National Veld Trust, 1990,

Reprint : In File,

Keywords : VELD CONDITION

Ref ID : 1883

1701. Roux, P.W. The general condition of the veld in the Republic of South

Africa. Veld Trust Conference on the conservation status of agricultural

resources in the RSA. De Preez, J.F.Anonymous Pretoria:Unisa. , 1990.

Reprint : In File,

Keywords : VELD CONDITION; RAINFALL; CONSERVATION

Notes : Veld, and its condition, in the context of this paper, refers to natural

vegetation on which the livestock farming industry is economically dependent.

Veld condition is a deceptive phenomenon; it is difficult to define, changes

over time, and not easy to assess accurately and objectively. It is also, to a

considerable extent, a matter of perception. It could thus have a different

meaning to different people. The condition of the veld has a great deal to do

with the very fabric of the natural resources, especially in respect of soil - a

non-renewable resource - and water resources. The author concludes that,

considering present trends, attitudes and economic pressure, the main trend in

veld condition will be one of continued deterioration with major and minor

fluctuations in veld condition occurring as dictated primarily by seasonal rends

in rainfall and/or the amount of rainfall.

Ref ID : 344

1702. Roux, P.W. and Opperman, D.P.J. Soil erosion. In: The Karoo biome: a

preliminary synthesis, Part 1 - Physical environment, edited by Cowling, R.M.,

Roux, P.W., and Pieterse, A.J.H. 1986,p. 92-111.

Reprint : In File,

Keywords : SOIL EROSION; NAMA KAROO; SUCCULENT KAROO; EROSION; DROUGHT; FAUNA;

WIND EROSION

Notes : This chapter provides a background to soil erosion in the Karoo. It

then delineates the causes of soil erosion, including overgrazing by farm

animals; the physical impact of the grazing animal; drought; and the Fencing Act

of 1912. The authors then describe the influence of indigenous fauna, including

the springbok; the rock rabbit (dassie); other animals; and insects. They note

erosion processes, including wind erosion; wind erosion and seasons; and water

erosion. This is followed by an account of landscape in the Karoo biome and

erosion, including the Great Escarpment; Namaqualand; the Great Karoo; the Upper

Karoo; and the Fish River Basin. An account of erosion and vegetation is then

provided, including vegetation structure and erosion; sheet erosion under grass

and bushes; erosion on slopes under grass; and erosion of the Orthic-A horizon.

Finally, the results of erosion are discussed, including surface erosion and

seedling establishment; deposition of silt and sediment; zones of deposition;

salination of soil; brack bare patches; tunnel formation; control of erosion;

and research into soil erosion.

Ref ID : 1046

1703. Roux, P.W. and Vorster, M. Development of veld management research in the

Karoo region. Proceedings of the Grassland Society of southern Africa 18:30-34,

1983.

Reprint : In File,

Keywords : VELD MANAGEMENT; KAROO DESERTIFICATION; ENVIRONMENTAL HISTORY

Abstract : The development of veld research in the semi-arid Karoo areas since

1934 is outlined. It entailed key experiments on different types of veld, and

the synthesis of grazing systems and their testing in experimental camps and co-

operatively on a practical farming scale. The experiments were primarily

conducted with Merino sheep but Angora goats, Boer goats, cattle and Persian

sheep were also employed. A large number of rotational grazing systems, special

treatments and methods have been set out for the entire Karoo Region. The group

camp approach serves as a basis for complete veld management planning in the

Karoo Region. Supporting research covered plant physiological, phenological and

ecological studies; the determination of selective grazing habits of livestock;

production of karoo bushes; and the development of research techniques

especially in connection with quantitative and qualitative vegetation surveys.

Ref ID : 210

1704. Roux, P.W. and Vorster, M. Vegetation change in the Karoo. Proceedings of

the Grassland Society of southern Africa 18:25-29, 1983.

Reprint : In File,

Keywords : VEGETATION CHANGE; NAMA KAROO; KAROO DESERTIFICATION; ENVIRONMENTAL

HISTORY; VELD CONDITION

Abstract : Large scale and often radical change has taken place in Karoo

vegetation over the past three centuries. This change can be equated with

desertification and desertization processes. Change largely embodies the

thinning out of the vegetation, decrease or destruction of perennial grass, and

an increase and spreading of undesirable karoo bush and woody species. In many

instances veld types have changed and the drier types extended into the moister

types. The overall vegetation change has been ordinated into five broadly

overlapping phases. These are primary degradation, denudation, revegetation,

secondary degradation and a desertified phase.

The main factor causing change is over-exploitation by sheep. Seasonal

fluctuations in climate enhance the instability of the vegetation.

Ref ID : 970

1705. Roux, P.W., Vorster, M., Zeeman, P.J.L., and Wentzel, D. Stock production

in the karoo region. Proceedings of the Grassland Society of southern Africa

16:29-35, 1981.

Reprint : In File,

Keywords : LIVESTOCK PRODUCTION; NAMA KAROO; STATISTICS; VELD MANAGEMENT;

DROUGHT

Abstract : The Karoo Region, an arid to semi-arid extensive small stock grazing

area, is described. The main factors concerning stock production are covered.

These are elucidated and supported by research data and references. Management

aspects and situations generally hampering stock production are degradation of

the vegetation, overgrazing, drought, economic vicissitudes, fluctuating forage

and nutritional supply, stock diseases, insect pests and detrimental management

practices. Measures to promote stock production are discussed. These are sound

veld and stock management practices, which include stock reduction, rotational

systems, diversification of stock, control of diseases and parasites,

reproduction, breeding and supplementary feeding, and proper physical

facilities. The future of stock production in the Karoo Region is summarised.

Ref ID : 2074

1706. Rowntree, K. An assessment of the potential impact of alien invasive

vegetation on the geomorphology of river channels in South Africa. South African

Journal of Aquatic Sciences 17:28-43, 1991.

Reprint : Not in File,

Keywords : GEOMORPHOLOGY

Ref ID : 346

1707. Rowntree, K.M. Equilibrium concepts, vegetation change and soil erosion in

semi-arid areas: Some considerations for the Karoo. In: Geomorphological studies

in southern Africa, edited by Dardis, G.F. and Moon, B.P.Rotterdam:Balkema,

1988,p. 175-185.

Reprint : In File,

Keywords : SOIL EROSION; VEGETATION CHANGE; NAMA KAROO; KAROO DESERTIFICATION;

EROSION

Notes : This paper examines the relationship between vegetation cover and

hydrogeomorphic processes with particular reference to soil erosion in the semi-

arid Karoo of SA. The discussion focuses on the processes of gully erosion

because it is seen as an expression of geomorphological instability which has

direct implications for ecosystem equlibrium. The paper is divided into three

parts. The first reviews factors associated with rejuvenation of drainage

systems responsible for the initiation of gully erosion and examines the

evidence for the Karoo itself. The second outlines established relationships

between vegetation cover and sediment processes within the context of gully

erosion. Finally the paper brings together concepts of geomorphological

stability and ecosystem stabilily in order to explore the interrelationships

between them. The paper concludes that in semi-arid areas such as the Karoo,

erosion may not necessarily represent degradation because cycles of erosion and

deposition must be part of the dynamic equilibrium of semi-arid ecosystems. The

need for further research into the relationship between plant community dynamics

and sediment processes is emphasised.

Ref ID : 866

1708. Rowntree, K.M. and Dollar, E.S.J. Hydroclimatic trends, sediment sources

and geomorphic response in the Bell river catchment, Eastern Cape Drakensberg,

South Africa. South African Geographical Journal 77:21-32, 1995.

Reprint : In File,

Keywords : HYDROMETEOROLOGY; SEDIMENTATION; GEOMORPHOLOGY; EASTERN CAPE; SOIL

EROSION; RAINFALL; FLOODS; DROUGHT; EROSION

Abstract : The Bell River in the Eastern Cape Drakensberg of SA has shown recent

signs of channel instability as evidenced by avulsion, sinuosity reductions,

gradient steepening and general channel instability. Analysis of rainfall data

did not provide evidence for progressive long term change in rainfall pattern

for the catchment. However, annual and seasonal rainfall cycles with variance

peaks every 16-19 years were found, from which it can be inferred that flood

events following years of below average rainfall may cross the threshold limit

for channel stability. Channel instability is often followed by a major flood

event after sustained low rainfall periods, a sequence referred to as the Flood

and Drought Dominated Regimes by Warners. Evidence presented also indicates an

increase in catchment erosion in the past centrury with attendant sediment

production increases to the channel. This may be due to catchment land use and

management practices (following settlement by commercial farmers) superimposed

on long term climatic changes. The conclusions are that catchment and channel

processes are inseparable, and that disequilibrium in the catchment will be

transferred to the channel.

Ref ID : 867

1709. Rowntree, K.M. and Dollar, E.S.J. Controls on channel form and channel

change in the Bell river, Eastern Cape, South Africa. South African Geographical

Journal 78:20-28, 1996.

Reprint : In File,

Keywords : EASTERN CAPE; SOIL EROSION; GEOMORPHOLOGY

Abstract : Channel instability has occurred in the Bell River in the form of

meander cutoffs, incipient meander cutoffs, and general channel instability.

This paper examines the incidence of channel instability in relation to the

spatial variability of factors controlling channel form. The locations of

channel change were mapped from aerial photographs for a 40 year period.

Channel form characteristics were measured over a 17 km stretch of channel.

Data collected from this stretch included pattern, width, depth, form ratio,

channel gradient, particle-size distribution of bed and bank materials and

riparian vegetation. Results indicate that the two primary spatial controls on

channel form and pattern are riparian vegetation and bed-material size.

Evidence indicates that narrow stable stretches are associated with finer bed-

material and relatively high levels of riparian vegetation. Riparian vegetation

increases bank stability and reduced channel cross-section, thereby inducing

stabilty at flows less than bankfull. However, at flows greater than bankfull,

reduced channel capacity results in more frequent flooding which may ultimately

lead to channel avulsion. Wider, unstable channels are associated with larger

calibre bed material and relatively less riparian vegetation. Predicted

threshold slopes for braiding have indicated that most reaches in the Bell river

are close to or above the threshold slope for braiding. Since riparian

vegetation serves to increase bank stability, steeper threshold slopes are

required for braiding in channels with high vegetation density. Recent

incidences of channel instability have been identified as occurring in the

transitional zone between the upper, coarser reach and lower, finer channel

reach.

Ref ID : 1743

1710. Rubin, F. The physical environment and major plant communities of the

Tankwa-Karoo National Park. Koedoe 41(2):61-94, 1998.

Reprint : Not in File,

Keywords : EROSION; NATURE RESERVES; BOTANICAL SURVEY; MONITORING;

GEOMORPHOLOGY; SEDIMENTATION; RAINFALL

Abstract : Apart from Acocks (1988) there are no published descriptions of the

vegetation of the greater Tanqua and Doring River drainage basin. A botanical

and physical description of the Tankwa-Karoo National Park (TKRNP) which occurs

in Veldtype 31b is provided. The three dominant geological formations, older

glacigenic deposits of the Dwyka Group, followed by the succession of

siliciclastic sediments of the Permian Ecca Group, with flat dolerite sills and

dykes, underlie eight distinct plant communities. The plant communities can be

divided into large open plains dominated by Galenia africana and tripteris sp.

in the erosion rills, Malephora luteola and Augea capensis common in the low

lying areas and Zygophyllum microcarpum, Brownanthus ciliatus and Galenia

crystallina common on the more shaly concave plains and low shale hills.

Slightly elevated rocky areas are dominated by Ruschia cf. robusta, Ruschia

spinosa communities, while crusts of stemless mesembs such as Rhinephyllum

macradenium, Hereroa fimbriata and Cheiridopsis acuminata are found on the

desert paved areas. Annual Asteraceae covers all the denuded and sparsely

vegetated areas after good winter rains while annual mesembs colonise on the

more sodic sites. A total of 259 plant species were collected sporadically over

a period of eight years, this includes 65 succulents and seven species endemic

to the Tanqua Karoo and immediate adjacent area of the Roggeveld Mountain Range

and Sutherland. Four Tanqua Karoo endemic species were found in the park.

Ref ID : 1951

1711. Russow, F. and Garland, G. The siltation of Hazelmere Dam, KwaZulu

Natal.Anonymous , 1998.

Reprint : Not in File,

Keywords : KWAZULU; KWAZULU NATAL

Notes : Paper presented to the biennial conference of the Southern African

Association of Goemorphologists, Rhodes University, Grahamstown.

Ref ID : 2229

1712. Rutherford, M.C. Biomes. In: Vegetation of southern Africa, edited by

Cowling, R.M., Richardson, D.M., and Pierce, S.M.Cambridge:Cambridge University

Press, 1997,p. 91-98.

Reprint : In File,

Keywords : SOUTHERN AFRICA

Ref ID : 2322

1713. Rutherford, M.C. and De W Bosenberg, J. Some responses of indigenous

western Cape vegetation to the Australian invasive, Acacia Cyclops. Proceedings

of the 5th International conference on Mediterranean ecosystems (MEDECOS V) held

in Montpellier, France, July 15 - 21, 1987. Di Castri, F., Floret, C., Rambal,

S., and Roy, J.Anonymous Paris, France:International Union of Biological

Sciences. :631-635, 1988.

Reprint : In File,

Keywords : WESTERN CAPE

Notes : The following conclusions were made by the authors: 1. the negative to

positive response of indigenous species to A. cyclops invasion is strongly

species specific; 2. decreased water availability results in A. cyclops-induced

water stress in indigenous plant species which is independent of their strength

of association with the alien invasive; and 3. the effects of the non-thermal

components of attenuated radiation are probably critical to survival, and

require further research.

Ref ID : 1242

1714. Rwelamira, J.K. and Kleynhans, T.E. SADC agricultural potential

assessment: country profiles.Anonymous Anonymous Development Bank of Southern

Africa. (124):1-25, 1996.

Reprint : In File,

Keywords : AGRICULTURAL PRODUCTION; POLICY

Notes : Chapter 8 provides a profile of South Africa. The reader is provided

with an introduction, whereafter the following topics are dealt with: the

economic performance and economic growth strategy of SA; socio-demography and

human development in SA; natural and agricultural resources of SA; key

environmental issues related to agriculture; dualism and structural diversity in

agricultural production; land policy and tenure in SA and their implications for

agriculture; and agricultural production in SA.

Ref ID : 393

1715. Rwelamira, J.K. and Kleynhans, T.E. SADC Agricultural Potential

Assessment: Country Profiles, Johannesburg:Development Bank of Southern Africa,

1996.pp. i-12-24.

Reprint : In File,

Keywords : PRODUCTION POTENTIAL; AGRICULTURAL DEVELOPMENT; AGRICULTURAL

PRODUCTION; POLICY

Notes : The agricultural potential assessment of SADC countries study consists

of two parts. Part I consists of the SADC country profiles (see ID no. 1242 for

the profile on SA) . Part II concentrates on developing an integrated

Agricultural Information System (AIS) to support rational resource use in the

SADC region. The objective of the research is to study the agricultural

potential of the SADC region generally and each country specifically, in terms

of its physical potential, technological development, infrastructure and

potential to produce specific categories of products under different assumptions

of institutions. This report is descriptive and draws on various studies,

reports and books relating to the SADC region, Sub-Saharan Africa and the world

at large, that were available to the reserachers.

Ref ID : 1718

1716. Rwelamira, J.K. and Kleynhans, T.E. SADC Agricultural Potential

Assessment: Country Profiles, Johannesburg:Development Bank of Southern Africa,

1996.pp. i-12-24.

Reprint : In File,

Keywords : PRODUCTION POTENTIAL; AGRICULTURAL DEVELOPMENT; AGRICULTURAL

PRODUCTION; POLICY; ECONOMIC ASPECTS; ENVIRONMENTAL POLICY; ENVIRONMENTAL

HISTORY; LAND TENURE

Notes : In chapter 8 various issues relating to South Africa are discussed. The

authors provide an introduction whereafter the following matters are discussed:

the economic performance and economic growth strategy of SA; socio-demography

and human development in SA; natural and agricultural resources of SA; key

environmental issues related to agriculture; dualism and structural diversity in

agricultural production; land policy and tenure in SA and their implications for

agriculture; and agricultural production in SA.

Ref ID : 906

1717. Rycroft, H.B. Saving our flora. The Journal of the Botanical Society of

South Africa XLI/XLII:13-15, 1955.

Reprint : In File,

Keywords : CONSERVATION

Notes : The speaker and author of this article stresses that the starting point

to life in all forms is conservation of vegetation. An historical account is

presented and the question is explored to what extent vegetation has changed in

those areas which are not actually built upon or cultivated. Ways are also

discussed in which vegetation may be nurtured, grown and sustained not only

nationally, but internationally.

Ref ID : 2214

1718. Sami, K. and Murray, E.C. Guidelines for the evaluation of water resources

for rural development with an emphasis on groundwater.Anonymous Water Research