Bibliography: Land Degradation in South Africa project

the suitability of applying these procedures for the detection of trend in veld

condition in the Arid Karoo. This was done by analysing vegetation data

collected in a long-tem grazing capacity trial, where the veld is stocked at

four stocking rates. Monitoring transects were permanently demarcated in all

plots during 1988. Percentage canopy spread cover and botanical composition

were used as basis for the description of the vegetation. Data were gathered in

the autumn of 1988 and 1991, using the descending point method. One-thousand

points per plot were recorded. In the absence of a canopy spread cover strike,

nearest plant data were recorded to determine botanical composition. The data

were analyzed suing the ISPD program. This software provides access to three

well-known mutivarite ordination procedures. An ordination procedure, developed

to analyze data from reasonably homogeneous areas, was also used to analyze the

data. The TWINSPAN classification and DECORANA ordination of both data sets

stressed the temporal variability of Karoo vegetation and the importance of

interpreting classification and ordination results with due cognisance being

taken of environmental and managerial data. The ordination of vegetation data

within reasonably homogeneous areas, in order to identify degradation gradients

(DMOC ordination), presented problems. The effect of a (dominant) species,

which is fairly insensitive to grazing, prevented the identification of a

degradation gradient. Similar problems may be encountered elsewhere where

similar conditions prevail. Ordination of the canopy spread cover data, by

means of the DMOC model, was better related to veld condition trends than the

ordination of botanical composition data. This differs from grassveld areas,

where nearest plant (frequency) data are used in ordinations to quantify changes

in veld condition. It indicates that the same type of data used to calculate

veld condition should be used in ordinations for the purpose of vegetation

monitoring.

Ref ID : 72

1437. Meyer, T.C., Venter, I.S., and Van Zyl, A. The influence of stocking rate

and grazing system in the Tarchonantus-veld of the Ghaap Plateau. Bulletin of

the Grassland Society of southern Africa, 1996. (Abstract)

Reprint : Not in File,

Keywords : NORTHERN CAPE; STOCKING RATE; VELD MANAGEMENT; SAVANNA; GRAZING

EFFECTS

Notes : Paper abstract, GSSA Congress 31 programme, Nelspruit.

Ref ID : 325

1438. Middleton, E.A. and Oliff, W.D. Suspended silt load in the Tugela River.

Civ.Engnr.S.Afr. 3(12):237-244, 1961.

Reprint : In File,

Keywords : SOIL EROSION; SEDIMENTATION; KWAZULU NATAL; COMMUNAL AREA

Notes : This paper describes a silt survey made on the Tugela River during the

periods October, 1955 to May, 1956, and March, 1957 to May, 1958. The methods

of sampling and analysis are set out in some detail and the results of both the

percentage concentration and the total silt loads are given.

Ref ID : 326

1439. Midgley, D.C. A preliminary survey of the surface water resources of the

Union of South Africa.University of Natal, Pietermaritzburg. , 1952. Doctoral

Dissertation.

Reprint : Not in File,

Keywords : HYDROLOGY

Ref ID : 469

1440. Midgley, D.C. Sediment yield map of southern Africa. 1952.

Reprint : Not in File,

Keywords : SOIL EROSION; SEDIMENTATION

Ref ID : 1390

1441. Midgley, G.F., Bond, W.J., Roberts, R., and Wand, S.J.E. Will Gullivers

travel? Potential causes of changes in savanna tree success due to rising

atmospheric CO2.Anonymous Anonymous Gaborone: 1998. The direct effects of

elevated CO2 on plant function may provide an important stimulus to the success

of trees relative to grasses in situations where these growth forms co-occur.

In this paper we suggest two mechanisms by which this could happen, leading to

sharp switches in vegetation structure from savanna to woodland-type vegetation.

The first is based on the observation that tree saplings (Gullivers),

resprouting after fire, may have atmospheric CO2-limited rates of carbohydrate

accumulation and storage. This probably retards the rate at which their

resprouts can escape topkill in the flame zone, fuelled by grasses (the

Lilliputians). Elevated CO2 will probably increase the rate of carbohydrate

accumulation and storage in resprouting tree saplings, thus allowing them

accelerated escape rates. This interaction between growth form performance and

disturbance regime may be the key, under current and historical CO2 levels, to

preventing tree dominance in moist savanna types through higher fire

frequencies. It is interesting to note that increased fire frequency and spread

of open savanna vegetation and associated ungulates can be traced to Miocene

times, when atmospheric CO2 dropped emphatically below 500 ppm. The second

mechanism is suggested by marked reductions in C4 grass water use in elevated

CO2, which have been shown in several African grass species of diverse C4

subtypes (NAD, NAD-Me and NADP-Me). Observed reductions of up to 45% in

transpiration rate at the leaf level under conditions of doubled atmospheric CO2

translate to significant canopy-level water use reductions. This will increase

absolute water infiltration below grass canopies, and favour co-occurring growth

forms such as trees, especially in more arid savanna types. Taken together,

these two mechanismss suggest that rising atmospheric CO2 will strongly favour

tree success relative to grasses under a wide range of climatic conditions.

Reprint : In File,

Keywords : SAVANNA; BOTSWANA; CLIMATE CHANGE; BUSH ENCROACHMENT; PLANT

PHYSIOLOGY; GLOBAL CHANGE; HYDROLOGY; RUNOFF; SOIL PROPERTIES; FIRE

Notes : Proceedings of Kalahari Transect Workshop: "Towards sustainable natural

resource management in the Kalahari region" held at the Botswana National

Productivity Centre, Gaborone, Botswana, 10-13 June 1998.

Ref ID : 1018

1442. Midgley, G.F. and O'Callaghan, M. Review of likely impacts of climate

change on South African flora and vegetation. A report prepared for the South

African Nature Foundation.Anonymous Cape Town, South Africa:National Botanical

Institute. :i-23, 1993.

Reprint : In File,

Keywords : CLIMATE CHANGE; VEGETATION CHANGE; FYNBOS; SUCCULENT KAROO;

BIODIVERSITY; RAINFALL; FIRE; FOREST; CLIMATE; GRASSLAND; NAMA KAROO; SAVANNA

Notes : The authors conclude that the species-rich biomes of southern South

Africa (Fynbos and Succulent Karoo) are at a high risk of loss of biodiversity,

considering the combined threats of rising temperature, changed rainfall

seasonality, increasing UV-b flux, altered fire regime, and possibly disruptive

effects of elevated CO2 on system nutrient cycling. Isolated habitats at high

altitude in mountain Fynbos especially are threatened by rising temperature and

changed fire regime, while lowland Fynbos is threatened by expansion of grassy

elements in the east and invasive woody plants throughout the whole vegetation

type. Forest function and species richness face immediate threats from

fragmentation which may be exacerbated by soil desiccation due to climate

change. Of the inland biomes, the Grassland Biome is most at risk of range

contraction and invasion by shrub and tree elements of the surrounding Nama

Karoo and Savanna Biomes. Finally, we have almost no information about risks

facing vegetation in the Desert Biome, but it seems likely that habitat

specialists existing close to their tolerance limits risk extinction.

Ref ID : 1524

1443. Miller, R.L. Planet of the year: what on earth are we doing? New

York:Robert L. Miller. Time January 2(Special edition):6-51, 1989.

Reprint : In File,

Keywords : DROUGHT; FLOODS; FOREST; FIRE; POLLUTION; INTERNATIONAL ASPECTS;

ENVIRONMENTAL POLICY; DESERTIFICATION CONTROL

Notes : The unorthodox choice of Endangered Earth as Planet of the Year had its

origin in the scorching summer of 1988, when environmental disasters - droughts,

floods, forest fires, polluted beaches - dominated the news. By August, Time

knew it was no longer enough just to describe familiar problems one more time.

It was time to help find solutions and this meant, by definition, international

solutions. This edition reports on the proceedings of a conference called by

Time, charged with producing an action programme. FILED UNDER "TIME MAGAZINE".

Ref ID : 1047

1444. Milton, S.J. Effects of rainfall, competition and grazing on flowering of

Osteospermum sinuatum (Asteraceae) in arid Karoo rangeland. Journal of the

Grassland Society of southern Africa 9(4):158-164, 1992.

Reprint : In File,

Keywords : VEGETATION DYNAMICS; GRAZING EFFECTS; RAINFALL; KAROO DESERTIFICATION

Abstract : The shrub Osteospermum sinuatum, an important fodder plant in Karoo

rangelands, flowered after heavy rain in autumn, winter and spring. The number

of flowers produced per bush was positively correlated with basal stem diameter

and rainfall in the 12 weeks before anthesis. Flowering increased when

neighbouring plants of all species were removed. Grazing during flowering and

seed set, by sheep stocked at recommended densities, reduced potential seed set

by as much as 90%. Birds, hares and small antelope consumed 10 - 50% of the

flowers. Size-class distributions indicated that little recent recruitment had

taken place on a ranch where palatable plants were scarce and where O. sinuatum

flower production was severely depressed by grazing sheep.

Ref ID : 225

1445. Milton, S.J. Growth, flowering and recruitment of shrubs in grazed and in

protected rangeland in the arid Karoo, South Africa. Vegetatio 111:17-27, 1994.

Reprint : In File,

Keywords : SUCCULENT KAROO; VEGETATION DYNAMICS; GRAZING EFFECTS

Abstract : A three-year study involving 1300 marked shrubs of three species

differing in palatability to sheep provided evidence that changes in the

demographic structure of shrub populations in arid rangelands are a function of

seed availability. Sheep reduced canopy size and flowering of their preferred

forage species but had no effect on survivorship of seedlings or established

plants during the study. Although annual turnover in all populations was low

(<6%), abundant recent recruitment of non-forage species was observed on

degraded rangeland. Natality of all three species was positively correlated with

flower abundance. Mortality was correlated with natality because seedlings had a

low probability of surviving their first year. Recruitment of both forage and

non-forage species, appeared to be inhibited by competition and seedlings seldom

survived near adult plants of the same growth form.

Ref ID : 1406

1446. Milton, S.J. and Bond, C. Thorn trees and the quality of life in Msinga.

Social Dynamics 12(2):64-76, 1986.

Reprint : In File,

Keywords : KWAZULU; COMMUNAL AREA; SAVANNA; SUSTAINABLE DEVELOPMENT;

DEFORESTATION; ECONOMIC ASPECTS; ENERGY; AGROFORESTRY

Notes : Thorn trees (Acadia and Dichrostachys) provide the people of Msinga, a

dry and rugged district of KwaZulu, with stockfeed, fuel, building and fencing

materials, tools, string, tannin and dye. The authors estimate that, in terms

of equivalent materials, thorn trees products are currently worth about R425/yr

(R48/ha/yr) to a rural family. Employment of rural people in agroforestry

projects aimed at the rational management of existing plant resources could

improve the quality of life for the people of Msinga.

Ref ID : 953

1447. Milton, S.J. and Dean, W.R.J. An underground index of rangeland

degradation. Oecologia 91:288-291, 1992.

Reprint : In File,

Keywords : LAND DEGRADATION; SOIL PROPERTIES; POPULATION

Notes : The prediction that density of long-lived, underground herbivores

(Cicadidae) is a function of rangeland condition was examined in arid shrublands

in the Karoo, SA. It was found that the density of adult cicadas was correlated

with cover of deep-rooted, perennial plants. Differences in perennial plant

cover were independent of soil type and rock cover. On degraded rangelands,

where perennial plants had been replaced by ephemerals and short-lived plants,

cicada densities were significantly depressed. We concluded that vegetation

transformation by domestic livestock is likely to affect invertebrate

populations and their vertebrate predators.

Ref ID : 256

1448. Milton, S.J. and Dean, W.R.J. South Africa's arid and semiarid rangelands:

why are they changing and can they be restored? Environmental Monitoring &

Assessment 37(1-3):245-264, 1995.

Reprint : Not in File,

Keywords : ECONOMIC ASPECTS; LAND DEGRADATION; GRASSLAND; SAVANNA; NAMA KAROO;

SUCCULENT KAROO; STOCKING RATE; VEGETATION CHANGE; BUSH ENCROACHMENT;

RESTORATION; CONSERVATION

Abstract : Since the mid-19th century settled livestock ranching has been the

major form of land use in South Africa, occupying 68% of the land surface.

Decreases in livestock densities and ranch numbers during the past century imply

that carrying capacities for domestic herbivores are falling. Differences in

carbon isotope signals with soil depth and abrupt shifts in dominant plant

species across ranch boundaries reveal that southern African rangelands are

changing. Case studies suggest ways to control altered grassland composition,

bush encroachment in arid savanna, and dominance by toxic and halophytic shrubs

in arid shrublands. But climatic and biological factors constrain rates of

passive recovery, and guidelines for active restoration are poor and techniques

costly. Moreover, conservation of remaining good rangeland is seldom enforced,

and economic considerations usually outweigh the land user's desire to sustain

diversity and productivity. [References: 85] Reprint available from: Milton SJ

UNIV CAPE TOWN FITZPATRICK INST RONDEBOSCH 7700 SOUTH AFRICA.

Ref ID : 1176

1449. Milton, S.J. and Dean, W.R.J. Karoo veld: ecology and management, Lynn

East, South Africa:ARC-Range and Forage Institute, 1996.pp. 1-94.

Reprint : In File,

Keywords : KAROO DESERTIFICATION; DESERTIFICATION ASSESSMENT; MONITORING; PLANT-

ANIMAL INTERACTIONS

Ref ID : 257

1450. Milton, S.J., Dean, W.R.J., du Plessis, M.A., and Siegfried, W.R. A

conceptual model of arid rangeland degradation: the escalating cost of declining

productivity. BioScience 44(2):70-76, 1994.

Reprint : In File,

Keywords : LAND DEGRADATION; ECONOMIC ASPECTS; PRODUCTION POTENTIAL;

DESERTIFICATION ASSESSMENT; DROUGHT; RAINFALL; FAUNA

Notes : The authors conclude that in arid and semiarid rangelands, drought is to

be expected because rainfall can range from one-tenth to twice the yearly

average. The variability in plant and animal production is 1,5 times greater

than the variability in rainfall (Le Houerou et al. 1988). Unless rangelands

are maintained at the step-one conditon by livestock reduction during dry years,

productivity will be irreparably lost because further degradation involving

changes in secondary productivity, fauna, and soil become too costly to reverse

in an overpopulated, resource-starved world. For many subsistence farmers and

pastoralists, irreversible degradation of drylands and lost secondary

productivity is already a reality.

Ref ID : 1044

1451. Milton, S.J., Dean, W.R.J., and Kerley, G.I.H. Tierberg Karoo research

centre: history, physical environment, flora and fauna. Transactions of the

Royal Society of South Africa 48(Part 1):15-46, 1992.

Reprint : In File,

Keywords : KAROO DESERTIFICATION; MONITORING; CLIMATE; SOUTHERN AFRICA

Notes : The Tierberg Karoo Research Centre near Prince Albert in the southern

Karoo is intended for long-term ecological monitoring and manipulative studies.

This paper summarizes information on the management history, geology, soils,

climate and vegetation, and includes preliminary checklists of 189 vascular

plant species, 25 ant, 90 bird, 18 reptile and 18 mammal species known to occur

on the 1 km2 study site. In comparison with arid shrublands in North America,

Australia, Israel and elsewhere in southern Africa, grasses and annual forbs are

scarce, succulents abundant and there are a few alien taxa.

Ref ID : 668

1452. Milton, S.J., Dean, W.R.J., Marincowitz, C.P., and Kerley, G.I.H. Effects

of the 1990/91drought on rangeland in the Steytlerville Karoo. South African

Journal of Science 91:78-84, 1995.

Reprint : In File,

Keywords : DROUGHT; KAROO DESERTIFICATION; VEGETATION DYNAMICS; VELD MANAGEMENT;

RAINFALL; POPULATION; CARRYING CAPACITY

Abstract : During 1990/91, rainfall was 70% below the long-term annual mean of

271 mm in the Steytlerville Karoo, a semi-arid, small-stock ranching district of

the south-eastern Cape. A drought severity index, that incorporated monthly

rainfall and monthly averages of maximum daily temperature, showed that the

deficit in plant-available moisture increased between January 1990 and September

1991, when drought was broken by 99 mm of rain. Following this unusual (P <

0.015) drought, perennial vegetation cover decreased from 45% to 21%. Mortality

was greater among Karoo bushes (65%) than succulents (42%). Post-drought

vegetation was dominated by grasses, forbs and the alien biennial Atriplex

lindleyi, all of which emerged from soil-stored seed. Surviving shrub

populations recovered slowly by post-drought seeding or rooting from branches.

A change from Pentzia incana shrubland to grass and succulent dominance occurred

within 30 months. Currently acceptable methods of estimating carrying capacity

indicated that 30 months after the drought the capacity of the rangeland to

carry domestic livestock was still 60% below pre-drought levels for the region.

Rodents, inconspicuous when the drought ended, were very numerous in 1994

following summer rain. Carrying capacity of ecotonal Karoo shrublands for

herbivores and granivores appears to be dynamic. Quantifying and tracking such

variability is a challenge for pastoralists and scientists alike.

Ref ID : 971

1453. Milton, S.J. and Hoffman, M.T. The application of state-and-transition

models to rangeland research and management in arid succulent and semi-arid

grassy Karoo, South Africa. African Journal of Range & Forage Science 11(1):18-

26, 1994.

Reprint : In File,

Keywords : MODELS; LAND DEGRADATION; SUSTAINABLE AGRICULTURE; VEGETATION CHANGE;

VELD MANAGEMENT

Ref ID : 243

1454. Milton, S.J., Yeaton, R.I., Dean, W.R.J., and Vlok, J.H.J. Succulent

karoo. In: Vegetation of Southern Africa. edited by Cowling, R.M., Richardson,

D.M., and Pierce, S.M.Cambridge:Cambridge University Press, 1997,p. 131-166.

Reprint : In File,

Keywords : SUCCULENT KAROO; VEGETATION DYNAMICS; VEGETATION CHANGE; BOTANICAL

SURVEY

Ref ID : 2247

1455. Mimosa The struggle against bush encroachment. Farmers' Weekly , 1948.

Reprint : Not in File,

Ref ID : 1133

1456. Mini, S.E. Gender relations of production in the eastern Cape and

restructuring of rural apartheid. Africa Insight 24(4):269-280, 1994.

Reprint : In File,

Keywords : GENDER ASPECTS; LAND REFORM; AGRICULTURAL DEVELOPMENT; EASTERN CAPE;

POLICY; LABOUR; LAND TENURE

Notes : The authro, of the Geography Department of Fort Hare University, argues

that all existing forms of tenure in SA are biased against women and that the

government's land reform policies are likely to fail unless this problem is

addressed. It is concluded that women in the Eastern Cape are farmers and that

they provide a major portion of agricultural labour. However, planners,

development agencies and government policies have presented women farmers as the

problem. Planners, development agencies and government policy have all

attributed the decline and collapse of peasant agriculture to the predominance

of women as farmers. This view presents an important challenge to the proposed

land redistribution and land tenure reforms. The contemporary debate on land

reforms has not as yet confronted the status of women farmers and how the

redefined position of women will relate to the existing land tenure systems.

Women are not recognized as farmers in their own right and despite abundant

evidence pointing to the contrary, farmers are officially assumed to be men and

the involvement of women is subsumed under the concept of household or family

labour. What is clear is that women will not benefit in the proposed land

reallocation as long as this is done within the framework of the existing land

tenure systems. All existing forms of tenure are biased against women.

Evidence from study villages suggest that the manipulation of rights to land

under both customary law and official state law has largely been at the expense

of women. Yet, as a result, while individual men exercise greater autonomy vis-

a-vis the land than women, women individually and collectively are the main

farmers. If women are to have rights to land the proposed land redistribution

should take place under a new form of land tenure system. A more flexible and

simpler form of land tenure sysetm is therefore recommended.

Ref ID : 1152

1457. Mitchell, S.A. The costs of soil erosion on agricultural land in South

Africa. Can they be predicted?University of Natal, Durban. :i-59, 1993. Soil

erosion is a problem of growing concern in SA. There are strong indications

that human impact is increasing the rate of soil loss by performing poor farming

practices and other destructive activities. There are many financial costs

associated with soil loss. The onsite effects of soil erosion result in nutrient

loss, degradation of soil structure, loss of storage capacity and reduction in

rooting depth. All of these can lead to the ultimate cost of a decline in crop

yield. The offisite costs are incurred by silting of reservoirs, damage to

agricultural land and infrastructure as well as from the impact on water quality

and freshwater Biota. These offsite costs may amount to more than R90 million

per year. To calculate these costs theoretical models are developed to measure,