Bibliography: Land Degradation in South Africa project

Notes : The author concludes as follows. This study of the structure and

functional dynamics of the Natal bushveld has yielded many results in common

with those of Archer and his co-workers (op.cit.) for a relatively similar

situation in the savannas of southeastern Texas. However, there are some

differences which can be attributed to the topological complexity of the Natal

bushveld sites and to the wider range of land use histories w hich they have

experienced. Below, the author states what he believes the major conclusions

are of this work and wherever possible, he points out the similarities and

differences with the savannas of North America. First, cluster species richness

can be used as an index of cluster developmental stage. This is particularly

important where a variety of different land use histories must be considered.

Heavily used rangelands often have fewer bush clusters per unit area and they

are smaller, whereas relatively unutilised areas have a higher density of bush

clusters and a greater range of bush cluster sizes. As a result of the

differential effects of immigration to and extinction within bush clumps,

cluster species richness is a better estimate of successional stages in areas

with different land use histories. This effect was not a problem at the La

Copita site in the savanna of southeastern Texas which was subjected to only one

pattern of land use history. Second, cluster growth is dependant on the rate at

which different clusters can coalesce, and not concentric expansion of

individual cluster perimeter. This, in turn, is depedent on the rate of cluster

formation and survival. A similar result was obtained in Texas. In both

studies, cluster formation and survival were greatest during wet periods with

severe mortality of small bush clusters occurring during periods of long-term

drought. Larger bush clusters continued to increase in size in both studies

during drought periods and were difficult to identify individually in the

sequence of aerial photographs used. The latter observation suggests that the

estimates of the rate of closure of the bush cluster phase are lower than they

actually are. Third, most of the species that occur in the Natal bushveld seem

to be dependent on the clustered structure of woody vegetation for establishment

and survival. Very few of the species found in the interstices of bush cluster

phase are present within the bush clusters. Those species that are present in

both situations are primarily members of the genus, Acacia, or are understory

shrubs which rarely reach tree size. A similar result was reached in the Texas

study where Prosopis glandulosa is the dominant woody species found in the open

grassland stage. It also serves as foci for the establishment of other woody

species, which are rarely found in the open, under their canopies. As a

consequnce, the cluster phase in Natal bushveld vegetation is important for the

maintenance of species diversity and ecosystem resilience at the landscape

scale. The bush cluster phase is particularly important where different types of

land use are employed on the landscape. The effects of these land-use practices

can (i) result in local extinction of species and loss of ecosystem resilience

and (ii) retard the development of closed-canopy woodland. Fourth, a

'successional gradient', which is likely the result of biotic interaction among

individual plants over a 'successional time scale' can be used to explain the

pattern of species distribution in a Natal bushveld community to a large degree.

As a consequence, species reponses to such a 'successional gradient' can be used

to describe the temporal range of individual species, and to group these species

into functional classes. In this study, as in the La Copita study, the early

successional species are aggressive invaders of the grassland phase and are not

easily removed once established. These species are primarily responsible for

our 'bush encroachment' problems in southern Africa and in many other parts of

the world. In all cases, the propagules of these early successional species are

dispersed into grasslands by large vertebrates. The propagules of later

successional species are dispersed by birds, monkeys and, rarely, wind. These

species are generally broad-leafed and appear to be dependent on bush clusters

to facilitate their successful establishment. Next, models based upon the above

methods and results can be constructed which describe species turn-over in

bushveld communities along a continuum of 'successional' development. Such a

model can be used to classify different communities or sites on the basis of

their species composition according to their previous land-use history and their

successional status. Such a model would be a potentially useful management and

planning tool. Finally, the phenomenon of 'bush encroachment' in southern Africa

is the result of natural events in which man has interceeded. Unless a clear

understanding is obtained of the dynamics underlying the ecological processes

and the environmental forces involved in causing the transition from one state

of vegetation to another within these rangelands, no attempts to manage this

vegetation to a desired endpoint will be successful in the long term. At

present, bush clusters in Natal bushveld continue to grow and coalesce in

moderately disturbed veld, slowly reverting to closed-canopy woodland. The

future of Natal bushveld under higher levels of disturbance is still an

unanswered question.

Ref ID : 648

1269. Le Roux, J.S. Spatial variations in the rate of fluvial erosion (sediment

production) over South Africa. Water SA 16(3):185-194, 1990.

Reprint : In File,

Keywords : SOIL EROSION; SEDIMENTATION

Abstract : The rate of denudation of the past ten to fifty years was calculated

from sediment accumulated in man-made reservoirs. The rate of surface lowering

generally increases from west to east over the subcontinent. This increase more

or less coincides with both an increase in annual precipitation and an increase

in the number of storms of high intensity. On the whole there is an increase in

relief from west to east, but relief seems to be only a secondary factor in the

explanation of denudation rate. No conclusive evidence could be found (from

reservoir sedimentation rates) that denudation rates have either decreased or

increased over the last ten to fifty years.

Ref ID : 312

1270. Le Roux, J.S. and Roos, Z.N. Rate of erosion in the catchment of the

Bulbergfontein dam near Reddersburg in the Orange Free State. J.Limnol Soc.S.A.

5(2):89-93, 1979.

Reprint : In File,

Keywords : SOIL EROSION; FREE STATE; SEDIMENTATION; CULTIVATION; RAINFALL;

EROSION

Notes : The volume of sediment in the Bulbergfontein Dam was computed after

mapping the area of the dam and ascertaining the depth of the sediment by

digging and augering. The watershed of the impoundment had been delimited by

means of aerial photographs and fieldwork. The catchment has a mean slope of

1,9o which is mostly covered by perennial grasses and xerophytic shrublets.

Approximately 75 per cent of the area is natural pasture and the rest under

maize and wheat cultivation. The mean annual rainfall is 471 mm. The

fortuitous presence of a fine sand layer (marker) in the sediments made it

possible to compute not only the total accumulation of sediment, but also the

accumulation since 1971. From these figures the rates of erosion were found to

be 27,5 mm 10-3 years for the period 1942 to 1971 and 34,6 mm 10-3 year for the

period 1972 to 1978.

Ref ID : 313

1271. Le Roux, J.S. and Roos, Z.N. The rate of soil erosion in the Wuras dam

catchment calculated from sediment trapped in the dam. Annals of Geomorph.

26(3):315-329, 1982.

Reprint : In File,

Keywords : SOIL EROSION; SEDIMENTATION; FREE STATE; EROSION

Abstract : The volume of sediment trapped in Wuras dam was obtained by

calculating the present capacity from numerous depth measurements and

subtracting this value from the original capacity of the dam. In order to

calculate the mass of the trapped sediment eleven core samples were taken and

the average density determined (0,97 g cm-3). The denudation rate was

calculated in terms of ground lowering and for this the average density of the

rocks underlying the catchment area was necessary. This was found to be 2,5 g

cm-3. From these figures in addition to the catchment area and the age of the

dam the rate of erosion was found to be 2.06 cm 10-3 years. As some of the

sediment is lost by overflow during wet spells (about 12%) the absolute rate is

about 2,3 cm 10-3 years.

Ref ID : 314

1272. Le Roux, J.S. and Roos, Z.N. Surface wash on a low-angled slope near

Bloemfontein. South African Geographical Journal 64(2):114-124, 1982.

Reprint : In File,

Keywords : SOIL EROSION; SEDIMENTATION; RUNOFF; FREE STATE; EROSION; RAINFALL

Abstract : Surface wash was measured for three consecutive years on a fairly

low-angled slope by means of 6 pairs of wash-traps. The erosion rate was found

to be more or less constant over the whole slope. This implies that, for the

period under observation, the slope retreated parallel to itself. Multiple

regression analysis of erosion (dependent variable), rainfall, rainfall

intensity and product of rainfall and rainfall intensity indicated that the only

truly significant variable was the product of rainfall and rainfall intensity.

The three variables together accounted for 58 percent of the variance in

erosion. The rate of soil loss calculated from the wash-trap data for 37 run-

off events was 46 g m-2 per year or, calculated as a ground lowering, 18 mm 1000

yr-1 at rock density, or 34 mm 1000 yr-1 at soil density.

Ref ID : 641

1273. Le Roux, J.S. and Roos, Z.N. The relationship between the size of

particles in surface wash sediment and rainfall characteristics on a low angle

slope in a semi-arid climate. Zeitschrift fur Geomorphologie N.F. 30(3):357-362,

1986.

Reprint : In File,

Keywords : SOIL EROSION; RAINFALL EROSIVITY; SEDIMENTATION; RAINFALL

Notes : In this investigation the amount of rainfall proved to be positively

correlated to the relative amounts of the sand fraction and negatively

correlated to the clay fraction being entrained and transported by surface wash.

Rainfall intensity showed the opposite trend, negative correlation to the sand

fraction and positive correlation to the clay fraction. The product of rainfall

intensity - the better indicator of overall soil loss - (Le Roux & Roos 1982:

120), provided to be negatively correlated to the relative amounts of sand and

positively to the clay fraction. The rather low correlations of precipitation

variables to the different mass percentage particle size categories indicate the

importance of other internal and external factors of the soil.

Ref ID : 2283

1274. Lehman, T. Public values, private lands, London:The University of the

North Carolina Press, 1995.

Reprint : In File,

Keywords : POLICY; LAND USE; SOIL CONSERVATION; CONSERVATION; POPULATION; ENERGY

Notes : The author examines the political battles over public policies to

protect farmland from urban sprawl. His detailed account clarifies three larger

themes: the ongoing struggle over land use planning in this country, the

emerging environmental critique of modern agriculture, and the use of social

science expertise in policymaking. Federal efforts to preserve private

farmlands began during the New Deal with modest soil conservation and land use

initiatives, but stalled with the agricultural surpluses of the postwar decades.

Land conservation interests re-emerged during the 1970s as productivity

plateaus, population growth, and the energy crisis heightened concern about the

loss of high-quality farmland. Bureaucrats and social scientists were divided

on the seriousness of the land problem. According to Lehman, the debate pitted

a conservation mentality against a production mentality, virtually guaranteeing

that consensus would be impossible. Land preservation initiatives of the 1970s

achieved a belated and partial success with the conservation measures of the

1985 farm bill, the author says, but the ecological constraints on agriculture

remain significant.

Ref ID : 2521

1275. Leibbrandt, M. and Sperber, F. Income and economic welfare. ISER Research

Report.Anonymous Grahamstown:ISER, Rhodes University. , 1997.

Reprint : Not in File,

Keywords : CISKEI; ECONOMIC ASPECTS; SOCIOECONOMIC ASPECTS; LABOUR; AGRICULTURAL

DEVELOPMENT

Notes : The purpose was to look at the structure of rural household income in

the Keiskammahoek district to identify important trends since 1949, and

isolating the factors that have affected each village's relative development. A

survey was conducted between September 1990 and February 1991 involving

interviews with 98 households taken from Rabula, Burnshill and Chatha. The

survey indicates that the three villages differ in sources of income and access

of employment. Burnshill is fast becoming functionally urbanised, in terms of

activities and aspirations. Chatha continues to conform more to the stereotype

of a poor rural village dependent on long term migrants, while Rabula falls

somewhere in between the two, showing characteristics of both. The survey shows

employment to be important in the Ciskei health, educational, agricultural and

administrative bureaucracies. As of 1990, the unemployment rate was 39%, 23%

and 42% respectively amongst rural households in Rabula, Burnshill and Chatha.

This report is obtainable from the Border Rural Committee, East London. See

also ID no. 2339.

Ref ID : 2519

1276. Leibbrandt, M. and Sperber, F. From reserve to region. Apartheid and

social change in the Keiskammahoek district of (former) Ciskei, 1950 to 1990,

Grahamstown:ISER, 1997.

Reprint : Not in File,

Keywords : CISKEI; POVERTY; POLICY; ECONOMIC ASPECTS; AGRICULTURAL PRODUCTION

Notes : The purpose of the study was to look at the structure of rural household

incomes in three villages of Keiskammahoek. Quantitative data collection in the

form of a survey was used for the study. The findings reveal different degrees

of reliance on agriculture, and different levels of integration into urban

economies. The second section extends the average income comparison of three

villages by documenting the extent of unemployment, poverty and inequality

within each village. The third section strengthens the static, survey-based

picture of previous sections by detailing the process that reproduces such a

static snapshot overtime. The fourth section returns to the policy issues

raised in the introduction. By seeking to understand the resilience of

oscillating migration, some of the crucial behavioural issues surrounding the

framing of regional and urbanization policy are raised. This book is obtainable

from the Border Rural Committee, East London. See also ID ref. no. 2339.

Ref ID : 959

1277. Leistner, G.M.E. International aid and African development. Paper

presented at a meeting of the Bophuthatswana Institute of International Affairs,

Mafikeng, 26 June 1986. 1986.

Reprint : In File,

Keywords : RURAL DEVELOPMENT; INTERNATIONAL ASPECTS; AID

Notes : The author notes that the correlation between the amount of aid received

and a particular country's economic progress is, at best, tenuous. He suggests

that the adverse factors associated with the provision of aid outnumber the

benefits. However, equally strong arguments in favour of aid are adduced by the

immensely powerful interest groups whose very existence is based on provision of

aid. The history of provision of aid is discussed, but the author suggests that

aid in post-war Europe was aimed primarily at reconstruction rather than

development. The author concludes by saying that the benefits as well as the

drawbacks of economic interdependence cannot be detailed in this review.

However, it is important to remember that ties of other countries with the South

African economy can act as growth stimuli for neighbouring countries, an

advantage which Black states further to the north do not enjoy, and are not able

to import through foregn aid. Under certain conditions, aid can facilitate the

process of development, but there is no doubt that normal commercial exchange

across international boundaries can do far more to promote economic progress

than any hand-outs doubtfully termed as 'aid'.

Ref ID : 1323

1278. LeMaitre, D.C., Van Wilgen, B.W., Chapman, R.A., and McKelly, D.H.

Invasive plants and water resouces in the Western Cape Province, South Africa:

modelling the consequences of a lack of management. 1998.

Reprint : In File,

Keywords : WESTERN CAPE; FYNBOS; FIRE; ALIEN PLANTS; RAINFALL; RUNOFF; MODELS;

EROSION; WATER QUALITY

Notes : (1) The invasion of fynbos shrublands by woody weed species can reduce

the water yield from catchment areas dramatically. We modelled the consequences

of uncontrolled invasion on water yield using a geographical information system

(Arc/Info). (2) Five important processes were recognised: the occurrence of

fire; the spread and establishment of alien plants after fire; rainfall to

runoff ratios; growth and changes in biomass between fires; and effects of these

changes on streamflow. (3) The simulations of water yield were modelled with

the Arc/Info GRID module using a 200 x 200 m grid. Fire interval was assumed to

be 15 years, and proliferation and dispersal of alien plants took place only

after fires. (4) Between fires, the model simulated the growth of the

vegetation and its effects on streamflow, using relationships between rainfall

and runoff, and runoff and above-ground biomass. (5) Results for the Kogelberg

area in the Western Cape Province showed that alien plants invaded about 40% of

the grid cells within 50 years. Cover of alien plants increased from an initial

estimate of 5.4% to 80% after 100 years. (6) Invasion of catchment areas would

result in an average decrease of 347 cubic metres of water per hectare per year

over 100 years, resulting in average losses of more than 30% of the water supply

to the city of Cape Town. In individual years, where large areas would be

covered by mature trees, losses would be much greater. (7) In addition,

invasion of fynbos by alien plants will result in the extinction of many plant

species, increase the intensity of fires, destabilise catchment areas with

resultant erosion and decreased water quality, and decrease the aesthetic appeal

of mountain areas. (8) Control of alien weed species is necessary to avert the

above impacts, and the costs of control operations could be justified by

maintaining good levels of water runoff from stable catchments in the long term.

Ref ID : 1203

1279. Lenta, G. Development or stagnation? Agriculture in KwaZulu.Anonymous

Durban:Department of Economics, University of Natal. No. 7:1-55, 1978.

Occasional Paper.

Reprint : In File,

Keywords : AGRICULTURAL PRODUCTION; COMMUNAL AREA; CULTIVATION; ECONOMIC

ASPECTS; KWAZULU; LAND USE; LIVESTOCK PRODUCTION; STOCKING RATE; FORESTRY;

POPULATION

Notes : It is commonly believed that agricultural methods in KwaZulu, as in the

case of most SA homelands, are primitive and output and yields low. It is the

purpose of this study to review the agricultural production of KwaZulu and to

determine to what extent this generally held opinion reflects the actual

situation. Part 1 concerns itself with the state of field production, forestry

activities and animal husbandry over the 16 year period 1957 - 1973. In part 2

the findings of the two analyses are collated in a systematic form so as to

provide an estimate of income originating in the agricultural sector over the

period under review. At the same time the size of the agricultural output is

tested against the food requirements of the local population so as to guage the

performance of acgriculture in the homeland. Finally, the quantitative and

qualitative endowment of factors of production which characterises KwaZulu's

agriculture will be compared with that of White agricuture.

Ref ID : 595

1280. Lenta, G. Land shortage and land unused: the paradoxical patterns of

KwaZulu, Durban:Economic Research Unit: University of Natal, 1981.

Reprint : In File,

Keywords : AGRICULTURAL PRODUCTION; COMMUNAL AREA; KWAZULU; KWAZULU NATAL; LAND

REFORM; LAND USE; POLITICAL ASPECTS; POPULATION; LAND TENURE

Notes : The need for this study arises from the particular situation in SA where

land is divided between Africans and Whites in such a way that the different

tribal groups each receive their separate parts of the 14 per cent allocated to

Africans out of the total area of the country. Moreover, a further puzzle is

that a comparatively large proportion of arable land (20 - 30 per cent) is left

uncultivated every year. The main intention of this study is to attempt to

explain this puzzle. A few questions on the matter will be answered including

the following: In what sense is there a shortage of arable land in KwaZulu?

Why is land left uncultivated? The intention, therefore, is not to investigate

the ways in which land at present cultivated could be made to produce higher

yields, but to try to indicate how a larger extent of land could be cultivated.

The discussion is preceded by an historical review of the way in which the

concept of the Reserves developed and altered from their inceptions until the

present day (section 2), the object being to throw light on the principles on

which, at different times, land was allocated to Africans and to allow some

judgments to be made, in later sections and in the conclusion, on the justice of

those principles. With the exception of Section 2, the study restricts itself

to KwaZulu, or rather to that part of SA at present so called. In Section 3,

trends in crop production during the period 1867 - 1977 are examined. The

amount of land available at different periods is compared with population