Chapter 9: LAND TRANSFORMATION AND SOIL QUALITY

Authors: Theunis Meyer (1) , Prof. Klaus Kellner(2) and Chris Viljoen(3)

1.Centre for Environmental Management, Potchefstroom University, Potchefstroom
2.Subject Group Botany, School for Environmental Sciences and Management, Potchefstroom University,
3.Wates, Meiring & Barnard, Midrand, Johannesburg


CONTENTS
  1. Introduction
  2. Driving Forces
  3. Pressures
  4. State
  5. Impact
  6. Responses
  7. Outcomes
  8. Linkages
  9. Data Issues and Indicators
  10. Conclusions and Recommendations
    11.
References

Maps:
Main land uses in the North West Province (Map 21)
Percentage area of magisterial districts managed under a communal land tenure system (Map 27)
Land use intensity changes over the past ten years - croplands (Map 28)
Land use intensity changes over the past ten years - grazinglands (Map 29)
Land use intensity changes over the past ten years - settlement development (Map 30)
Other land use intensity changes over the past ten years (Map 31)
Land degradation extent per magisterial district (Map 32)
Soil degradation extent per magisterial district (Map 33)
Major forms of soil erosion in croplands (Map 34)
Major forms of soil erosion in grazinglands (Map 35)
Major forms of soil erosion in urban areas (Map 36)
Main types of soil erosion associated with other land uses (Map 37)
Veld degradation severity per magisterial district (Map 38)
Main type of veld degradation in each magisterial district (Map 39)
Vegetation cover loss priority ranking per magisterial district (Map 40)
Change in species composition priority ranking per magisterial district (Map 41)
Bush encroachment priority ranking per magisterial district (Map 42)
Bush encroachment by Acacia mellifera and Acacia karroo (Map 43)
Bush encroachment by Acacia tortillis per magisterial district (Map 44)
Bush encroachment by Dicrostachys cinerea and Protasparagus species (Map 45)
Percentage of catchment area invaded by alien plants (Map 46)
Alien plant invasion priority ranking per magisterial district (Map 47)
Deforestation priority ranking per magisterial district (Map 48)

9.1 Introduction

The United Nations Convention on the Combating of Desertification (UNCCD) in those countries experiencing serious drought and/or desertification, particularly in Africa defines land degradation as the:

"reduction or loss of the biological or economic productivity and complexity of rainfed cropland, irrigated cropland, or range, pasture, forest and woodlands in arid, semi-arid and dry sub-humid areas, resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns such as:
  1. Soil erosion caused by wind and/or water;
  2. Deterioration of the physical, chemical and biological or economic properties of
    soil (see section 9.2); and
  3. Long-term loss of natural vegetation."
This chapter will provide information on the three types of land degradation mentioned above, concentrating on the soil degradation and veld degradation.

Soil degradation is made up of two components, soil erosion and soil quality. The phenomenon of soil erosion is considered the most destructive soil degradation process world-wide. It does not only involve the loss of soil but also of much needed plant nutrients at rates far higher than those occurring through leaching. The soil that is removed through erosion also finds its way into streams, rivers and lakes and becomes a pollution problem. Soil pollution is the pollution of the soil as a result of heavy metals, pesticides, herbicides and other agricultural pollutants. The persistence of contaminants in soil is much longer than in other components of the biosphere, and can have a detrimental effect on ecosystems reliant on that soil.

Veld degradation is a general decrease in the productivity and the natural functioning of the ecosystem. Hoffman & Todd (1999b) recognised six main types of veld degradation in South Africa. These are:

  1. Losses of cover largely as a result of the grazing and trampling patterns of domestic livestock;
  2. Change in species composition of the vegetation, again largely as a result of the selective grazing patterns of domestic animals;
  3. Bush encroachment as a result of the increase in cover of indigenous trees and shrubs;
  4. Alien plant invasions;
  5. Deforestation as a result of the removal of trees and shrubs by people usually for domestic energy or construction purposes; and
  6. Other forms of veld degradation, which usually encompasses the clearing of veld for the planting of agricultural crops, or mining pollution.

9.2 Driving Forces

The most important driving forces behind land degradation include population growth, national policy and legislation, population mobility, and natural disturbances. Driving forces are often interlinked and can produce more severe impacts than each force would create separately. For example, the development of a settlement, together with a small forestry development, and establishment of an agricultural enterprise, all within one vegetation type, may transform or fragment a large area of natural habitat.

Population growth
Population growth increases the demand for land transformation for settlements, agriculture, and recreation, as well as the demand for resources such as food, fuel, building and furniture materials, paper and board, minerals and water. High population growth rates are also an important factor contributing to the creation of poverty. Urbanisation, industrialisation, infrastructure development, and pollution also result from an expanding population (DEAT 1999).

Government laws and policies
Policy and legislation have the potential to be both positive and negative driving forces on land degradation. No other policies or laws had such a huge impact on South Africa's environment as the historical land and development policies (e.g. the Land Act of 1913), which led to distorted demography and settlement patterns (see Chapter 6).

Uneven distribution of wealth
In rural or undeveloped areas where incomes are very low, people are dependent on natural resources to meet their own nutritional, medicinal, housing, and energy needs. However, they also collect (and often exploit) the natural resources from these areas to generate much needed income in supplying such products to meet demands from urbanised or more developed areas. Poverty forces people to live unsustainably in their struggle for survival. This leads to overexploitation of the land in the short-term, which has long-term negative consequences.

Climate change
Climate changes alter the physical environment in ways that directly affect living organisms. Changing temperatures and water availability conditions are likely to induce stresses in vegetation and component plant species, and may encourage mobile organisms to alter their distributions in the medium to long term. Climate changes will possibly cause a gradually increasing pressure on the tolerance limits of native species, (i.e. if the average temperature increases by 2°C, the plant or animal species may not be able to withstand a fluctuation of a further 1°C). By causing these stresses in native species, climate changes could also favour the success and spread of alien plant species (Richardson et al. 1999).

Natural disturbances
Natural disturbances, including floods and droughts, winds, fire, earthquakes, and outbreaks of pests and diseases, occur from time to time. Although man has little or no control over these natural events, risk management to minimise their economic, social and environmental effects is important. Responsible management of land, which helps maintaining their proper functioning, also favours the recovery of ecosystems after natural disturbances. For example, drought may form a catalyst for desertification, but soils that are already degraded are more prone to drought. Degraded soils will also suffer more severely from the impacts of drought (Hoffman & Todd 1999d).

Increased mobility of people
The recent acceleration of international human movements and international trade has introduced many alien species into this country, both intentionally and unintentionally. Certain introduced species can rapidly dominate ecosystems, particularly when they are disturbed or stressed, replacing natural vegetation and animals, or using large amounts of water. This reduces the functionality of the natural system and lowers their ability to support the natural life forms, including humans (DEAT 1999).

9.3 Pressures

Population growth, income disparity, population mobility and government policies have resulted in a steadily increasing demand for resources. This manifests as pressures to exploit natural resources, to convert land from natural to man made systems, and to increase productivity of agricultural, forestry and industrial systems, in order to meet this demand. Increased productivity is often associated with generation of wastes and pollutants, which compromise the environment's ability to function normally.

Land tenure
The settlement policies of the previous Government created a patchwork of communal areas within a matrix comprising predominantly commercial areas. The location of communal areas in the North West Province is shown in Map 27. The former TBVC states (homelands) and self-governing territories were largely managed under communal land tenure, even though numerous commercial ventures may currently be underway within these areas (Hoffman & Todd 1999a). As a result, individuals in the communal areas generally have few rights to own and sell land, especially large parcels of rural land. Characteristics of these two land tenure types are shown in Table 9.1. The commercial and communal areas in the North West Province are fairly similar in terms of biophysical and climatic attributes. The huge differences between communal and commercial areas in the province only really emerge when land use, human population, labour and employment and economic production indicators are considered (Table 9.1). Although these latter differences can also be attributed to other factors, it is perceived as largely being the result of government policies and laws (Hoffman & Todd 1999a).

Table 9.1. Characteristics of communal area districts and commercial districts in the North West Province. (Sources: Hoffman & Todd 1999a; annual stock census and 1991 population census).
Variable Communal
area district		 Commercial
district
Biophysical indicators    9
Size (million ha) 3242 4749
Altitude (height (m) above sea level) 1155 1330
Slope (% change in altitude) 1 1
Run-off intensity (million m3/km2 secondary catchment area) 11211 15439
Erodibility index 14 15
Soil fertility index 5.7 5.3
Climatic indicators    
Amount of rainfall (mm) 508 549
Reliability of rainfall (CV as % of mean annual rainfall) 31 30
Summer aridity index 3.4 3.3
Mean annual temperatures (°C) 19 18
Soil fertility index 5.7 5.3
Agricultural meaningful grow days 62 63
Recommended grazing capacity (LSU/ha) 0.14 0.16
Soil fertility index 5.7 5.3
Land use indicators    
Area used for crops (%) 19 38
Area used for grazing lands (%) 56 53
Area used for commercial forests (%) 0.2 0.1
Area used for conservation areas (%) 1.6 1.0
Area used for settlements (%) 21 5
Area used for mines (%) 3.0 3.5
1995/96 Stocking densities (LSU/ha) 0.19 0.18
Human population indicators    
Population density (number of people/ km2) 88 28
Number of males (%) 45 43
Number of economically active people (15-64 yrs) (%) 48 61
Number of people living in rural, as opposed to urban areas (%) 91 62
Labour and employment indicators    
Unemployment levels (%) 42 12
Number of people dependent on one wage earner's salary 3.0 1.6
Number of people formally employed in the agricultural sector (%) 8 39
Growth in employment in agricultural sector(% of provincial average) 83 98
Economic production indicators    
Poverty index (GGP per capita)(rands/person) 1405 5669
Contribution of agriculture to the GGP 10 26
Growth in contribution of agriculture to the GGP (1981-1991) 7.0 -5.0
Annual growth rate in GGP 7.0 -1.0


Exploitation of natural resources
Exploitation of natural resources to meet nutritional, medicinal, housing, energy and construction needs, as well as to generating much needed income has led to the depletion of resources, and degradation of these systems. This has resulted in a range of land degradation types, including soil erosion, veld degradation bush encroachment and deforestation (DEAT 1999). Game farming and wildlife tourism are examples of resource exploitation with beneficial outcomes. Commercial game ranching can increase the number and range of species in the area, by restoring or maintaining natural habitat conditions. These conditions attract small mammals, birds, insects, and provide germination grounds for seeds, in addition to the species that are stocked intentionally (DEAT 1999).

Conversion from natural to man-made systems (land-use patterns)
Cultivation of land and aforestation often involves replacement of natural or near-natural habitats. In the process, the surface area of natural habitat is reduced and fragmented, and impacted by pollution, alteration of hydrological cycles, and by management actions which are aimed at increasing production (e.g. veld burning) These practices result in increased pressures on habitats and biological diversity (DEAT 1999). The expansion of human settlements also contributes to the conversion from natural to man-made systems. Urbanisation is encroaching upon more and more arable land, reducing the available land for farming and forcing existing land to be farmed more intensively. Conversion of natural habitats to urban, industrial and agricultural uses is often permanent (in terms of human life span) and usually has wide-ranging effects such as urban sprawl and pollution of rivers (DEAT 1999).

Increased productivity of man-made systems
Increasing populations of people and their animals necessitates more intensive land use and higher production in some parts of the North West Province. The economic marginalisation of farmers has also forced them to utilise unsuitable natural resources, in risky climatic areas, in order to produce food (DEAT 1999). In crop farming, changes in land use intensity include an increasing reliance on the use of irrigation, fertilisers, pesticides and herbicides, and, more recently, genetically-engineered crops (DEAT 1999). Continuous cropping and especially mono cropping, which exhausts the nutrient and organic matter of the soil, reduce productivity and result in wind and water erosion. Incorrect irrigation practices, especially in poorly drained soil types, causes salts to build up in the soil. This may impact plant growth negatively and prevent sensitive crop species from growing well. In livestock farming, changes in land use intensity have led to stocking rates above recommended levels, resulting in overgrazing. Most magisterial districts in the North West Province have shown an increase in land use intensity for croplands over the last ten years (Hoffman & Todd 1999a) (Map 28). These increases are attributed to increased mechanisation; an increase in the use of stubble cultivation and minimum tillage practices; an increase in intensive and specialist crops; the use of more environmentally-suitable and improved seed cultivars and varieties; better pest control, harvesting procedures and automated packing sheds; and improved the skills of crop farmers as a result of improved extension services (Hoffman & Todd 1999a).

Most magisterial districts in the North West Province have also shown an increase in land use intensity for grazing lands over the last ten years (Map 29). The mean value for the Province had also increased, while the increase for the commercial districts was two times higher than for communal areas. Increases in land use intensity of the grazing land, which are mostly applicable to the commercial districts, have occurred as a result of the employment of better management systems, including the adoption of research recommendations; the provision of improved extension and education programmes, including the use of demonstration farms; improved infrastructure, including water points, fencing; the planning of more commercial farms by the provincial Department of Agriculture, Conservation and Environment and an increased awareness amongst farmers of the impact of high numbers of animals on vegetation cover and composition, as well as stock condition (Hoffman & Todd. 1999a). Changes in land use intensity trends in the North West Province for the last 10 years were greatest for settlement areas. Land use intensity for settlements had increased in the majority of magisterial districts (Map 30), while the mean value for the Province as a whole had also increased. The main reasons for this are increased electrification; telephone exchanges; better water supply and improved sewerage system development; better road networks and housing programmes, all resulting from the RDP programme; as well as improvements on some commercial farms (e.g. improved housing, provision of schools) as a result of local farmer initiatives (Hoffman & Todd. 1999a).

Pollution
In terms of land degradation, pollution has a major impact on the soil quality. The main sources of soil pollution are from the mining, industry and manufacturing sectors from the major cities and towns, as well as agriculture. Expansion of industrial and manufacturing activities leads to increase in use of both organic and inorganic chemicals. Increased platinum-mining activities in the north-eastern regions of the Province resulted in increased solid wastes and effluent discharged into the soil. It is anticipated in the context of an emerging and growing platinum market that solid and effluent waste outputs will increase in the short (1-2 years), medium (2-10 years) and long term (10+ years). The increase in outputs lead invariably in the increase in solid wastes and effluent, which are discharged into the soil.

The decline in the gold industry results in major mining and plant infrastructure that needs to be closed and demolished. A significant amount of gold mine residue deposits are present in the eastern regions of the North West Province. These mine residue deposits constantly generate hostile organic and inorganic discharges into the soils. Likewise, diamond mining and exploration leads to disturbance of soil and consequent contamination with chemicals used in the mining process. The decline in fertility and health status of most soil and the desire by farmers to increase productivity and enhance profits is a major pressure to increase the use of agricultural chemicals and biocides that causes severe soil and water pollution. Marginal soils are over fertilised in order to achieve production yields and ultimately leads to salinisation of the soil.

Alien invasive organisms
Invasions of exotic trees and shrubs, especially in the wetter regions of South Africa and in riparian habitats specifically, pose a severe threat to plant and animal diversity. The Catalogue of Problem Plants in Southern Africa (Wells et al. 1986) lists 789 alien invasive species in South Africa, some of which have dominated areas to the extent that natural vegetation has been almost lost. Others, for example pine and eucalyptus trees present a threat to ecosystem functioning, because they use greater amounts of water than the natural vegetation, and therefore reduce the amount of runoff that reaches the streams and rivers. These impacts reduce the diversity and cover of indigenous plant species, but may be reversible even after up to 20 years of dense infestation. Other ecological impacts of the invasion process include alteration of soil nutrient cycling, increased river bank erosion, altered fire intensity and reduction of light to the forest floor or near to the ground (Macdonald 1989; Macdonald & Richardson 1986).

9.4 State

9.4.1 Land use patterns
Understanding land use patterns provides an important context for understanding land degradation. Approximately 30% of the land in the North West Province is being used for crop production, 54% for grazing lands, 11% for settlements and 5% for forestry, conservation and other land uses (mining) (Map 21). Similar percentages of land are used for grazing land and other land uses (mining) in commercial and communal districts. When compared to communal magisterial districts, about twice as much land is used for cropping purposes in the commercial districts. Settlements comprise about five times more land in communal districts than in commercial magisterial districts (Hoffman & Todd 1999a). Because the transformation of ecosystems is considered to be the most important human impact in the southern African subcontinent (Macdonald 1989), understanding the extent of conversions from natural to man-made systems in the North West Province will assist in understanding land degradation.

Although land use intensity has increased, the size of the areas used for cropping and grazing in the North West Province has decreased over the last 10 years. The land used for settlements and other uses (mining) has increased (Map 31). The extent of the changes for cropping land and settlements were fairly similar for commercial and communal districts. However, the shrinking of grazing lands was almost two times greater in communal magisterial districts when compared to commercial districts, while the expansion of other land uses (mining) was five times greater in commercial districts when compared to communal magisterial districts (Hoffman & Todd 1999a).

9.4.2 General land degradation
Hoffman (1999) developed land degradation indices to evaluate the extent and severity of land degradation. The Soil Degradation Index (SDI) is calculated as the sum of the severity and rate of soil degradation for each land use type multiplied by the % area of each land use type, added together to calculate one SDI. The Veld Degradation Index (VDI) is calculated as the sum of the severity and rate of veld degradation multiplied by the % veld in a district. The VDI considers all the types of veld degradation, including the loss in vegetation cover, change in species composition, bush encroachment, alien plant invasions, deforestation and other degradation impacts. The Combined Degradation Index (CDI) is calculated by adding the soil and veld degradation indices together to form a single combined index of land degradation, which incorporates, both soil and vegetation parameters.

The Combined Degradation Index (CDI), combining soil and veld degradation, for the magisterial districts in the North West Province is illustrated in Map 32. It is clear that all 28 districts showed signs of degradation and desertification. This indicates that land degradation is a problem throughout the Province. Although a few districts appear at either ends of the degradation range, the degradation in the majority of districts fall within the middle (average) categories. In general it seems as if the most degraded districts are all primarily communally managed, i.e. Madikwe (CDI = 711), Lehurutshe (CDI = 693), Mankwe (CDI = 604) and Taung (CDI = 472). The commercial districts seems to be less degraded, i.e. Coligny, Delareyville, Lichtenburg and Potchefstroom (CDI ranging from 126 - 143) and Koster (CDI = 48). The average combined degradation index, as well as the soil degradation (SDI) and vegetation degradation (VDI) indices for all the provinces of South Africa is shown in Table 9.2. If the North West Province is compared with the other provinces, it is listed fourth of the nine provinces in terms of the collective/combined degradation index. In terms of the soil and veld degradation indexes, the Province is listed fifth and fourth respectively.

Table 9.2: The mean values for each Province and for commercial and communal areas for the soil degradation index (SDI), veld degradation index (VDI) and combined index of degradation (SDI+VDI) (N=367) (Source: Hoffman & Todd, 1999c).
Province Number of
magisterial
district		 Mean values for degradation index
SDI VDI SDI+VDI
Eastern Cape 78 200 116 316
Free State 51 44 86 134
Gauteng 22 113 31 143
KwaZulu-Natal 51 253 187 440
Mpumalanga 30 143 81 223
Northern Cape 26 923 140 232
Northern Province 39 255 189 444
North West 28 149 122 270
Western Cape 42 77 93 170
Commercial districts 262 102 96 198
Communal districts 105 292 183 475


9.4.3 Soil degradation
Garland et al. (1999) recognised eleven types of soil degradation, split into two main forms: erosive forms such as water and wind erosion, and non-erosive forms such as acidification or salinisation (Table 9.3). The state of soil degradation in the North West Province is presented in Map 33. The soil degradation indices (SDI) for five types of land use, as well as the total soil degradation index for the commercial and communal districts in the North West Province are shown in Table 9.4.

When considered across all land use types, it is clear that soil degradation seems to be more of a problem in communal districts than in commercial districts. The average SDI for communal areas is almost three times higher than for commercial districts. Soil degradation in South Africa is most strongly related to the land tenure system, which defines the district. Soil degradation is also strongly related to a suite of variables, which differentiate the commercial and communal areas of South Africa. For example, soil degradation appears most strongly correlated with the high human, animal and settlement density which characterises the rural areas, where unemployment and poverty are prevalent and where a higher proportion of the economically active population, especially the males, are absent from the region. However, biophysical and climatic variables should not be ignored (Garland et al. 1999).

Table 9.3: Types of soil degradation in South Africa. (Sources: SARCCUS 1981; Dardis et al. 1988; Barrow 1991; Garland 1995; Garland et al. 1999).

Type Distriction and comments
Erosive forms
Water  
Sheet erosion The detachments of soil particles by rain drops, which are then taken
up in suspension and transported away, resulting in a relatively
uniform removal of surface soil. Crusting and compaction can lead to
a decrease in water infiltration capacity and accelerated run-off.
Rill, gully &
donga erosion		 The detachment of soil particles and aggregates by flowing water to
form streams and gullies which further concentrate water flow. River
and stream bank erosion, landslides and landslips are included in this
category.
Wind  
Loss of topsoil Uniform removal of soil particles by wind, which are held in
suspension or bounce across the land surface during strong winds.
Loss of vegetative cover usually exacerbates the problem.
Deflation hollows & dunes Uneven removal of soil particles leading to localized deflation hollows
and dunes usually following extreme wind erosion events.
Overblowing (deposition) Deposition of soil particles on agricultural lands and infrastructure
(e.g. roads and fences). Soil often originates far from its depositional site.
Non-Erosive forms
Salinization The accumulation of salts, usually in a cropland soil, and often
occurring under poor drainage conditions.
Acidification Acid deposition usually from air-borne pollutants following the
widespread use of coal for fuel.
Waterlogging Saturation of the soil interstitial spaces by water, usually under poor
drainage condition.
Pollution Pollution of the soil as a result of heavy metals, pesticides, herbicides
and other agricultural pollutants.
Soil mining Physical removal of the topsoil and sand for building and construction
purposes.
Compaction and crusting Formation of a dense, less permeable soil layer just below the surface
by use of heavy machinery, or development of a soil crust on bare
soil, caused rainsplash


Table 9.4: The Soil Degradation Index value for different types of land use and mean values for commercial and communal areas for the index of soil degradation calculated as the severity plus the rate multiplied by the percentage area of each land use type. (Source: Garland et al. 1999).

District Soil Degradation index for each land use type and the total for each district
  Cropland veld Conserv. Setle-
ment		 Other Total
Communal 34.1 136.1 2.5 62.1 2.7 237.5
Commercial 50.9 28.2 0.5 8.1 1.9 89.6
Average 43.6 72.5 1.3 29.0 2.2 148.5

Land use is also an important determinant of soil degradation. Soil degradation in the North West Province is primarily associated with the use of land for crop production, livestock production (veld) and settlements, based on the average SDI for the land use types. It is clear that total soil degradation in the communal districts of the province exceeds that in the commercial districts. This is primarily due to the SDI values for veld and settlements in the communal districts being at least four times as high as in commercial districts. Soil degradation on cropland in the commercial districts, however, is worse than that in communal districts (Table 9.4).

Sheet erosion and rill, gully & donga erosion through water action, as well as loss of topsoil through wind erosion are the dominant forms of soil degradation in the majority of magisterial districts in the North West Province. These types of degradation are primarily associated with the use of land for crop production (Map 34); livestock production from veld (Map 35), human settlements (Map 36) and other land uses (i.e. mining) (Map 37). The formation of deflation hollows & dunes, overblowing (deposition of sand) and salinisation only occur on a very limited scale under crop production. The only other form of soil degradation is soil pollution that occurs in a number of commercial districts as a result of other activities (i.e. mining) (Garland et al. 1999).

Soil erosion
Water-related erosion is the most important type of soil erosion in the North West Province and is mainly associated with veld (18 districts) and settlements (12 districts), but also with croplands (4 districts) and other uses (5 districts). The second most important type of soil erosion is the loss of topsoil (wind related), which is primarily associated with croplands (14 districts) and settlements (10 districts), but also with veld (5 districts) and other uses (3 districts). The two more serious types of wind erosion, i.e. the formation of dunes and hollows and overblowing (deposition) are the most important types of soil erosion in the Lichtenburg and Wolmaranstad districts respectively. There are distinct differences between commercial and communal areas with regard to the average severity and rate of soil erosion on cropland. Although this type of erosion is practically twice as severe in commercial districts, it is occurring at a negative rate, i.e. the erosion has been reduced over the last ten years. In contrast, this type of erosion is slowly increasing in communal districts. The severity of soil erosion in veld is similar in commercial and communal districts, although it is slowly being reduced in commercial districts and increasing in communal districts. Both the severity and rate of soil erosion associated with settlements are approximately twice as high in communal, as compared to commercial districts (Table 9.5).

Table 9.5: The value for each district and mean values for commercial and communal areas for the severity and the rate of soil erosion on the three most important types of land use in the North West Province. (Source: Garland et al. 1999).
District Cropland   Veld   Setlement  
  Severity Rate Severity Rate Severity Rate
Communal 1.1 0.5 1.5 0.7 2.0 1.3
Commercial 2.1 -0.8 1.1 -0.6 1.0 0.6
Average 1.7 -0.2 1.3 0.0 1.5 0.9

Severity
  1. Infrequent, light or moderate degradation;
    Common, light degradation
  2. Infrequent, strong or extreme degradation;
    Common, moderate degradation;
    Frequent or very frequent, light degradation
  3. Common, strong or extreme degradation;
    Frequent, moderate or strong degradation;
    Very frequent, moderate degradation;
    Dominant, light degradation
  4. Frequent, extreme degradation;
    Very frequent, strong or extreme degradation;
    Dominant, moderate, strong or extreme degradation


Rate
When compared to the situation in other provinces, both the severity and rate of soil erosion in croplands and settlement areas in the North West Province seem to be above average. Both the severity and rates of soil erosion for the other types of land use similar to other provinces (Garland et. al. 1999).

Soil pollution and salinisation
Soil pollution has two main sources: mining and agricultural activity.
  1. Agriculture - In the heavily irrigated areas of the Province including the Taung   irrigation scheme, and commercial agricultural centres of Brits, Ventersdorp,   Rustenburg, Lichtenburg, Potchefstroom and Coligny, about 30% of the soils of these   irrigated land have salinity problems. About 10% of soil samples submitted from   rainfed arable lands in North West Province have sub-optimal acidity levels (low pH)   and need to be ameliorated with lime. This is ascribed to the acidifying effect of nitrogen fertilisers (Bloem & Botha 1996). This condition reduces the soil's ability to hold air, water and nutrients essential for plant growth, and makes it difficult for plants to take moisture in through their roots.

  2. Mining - Soil pollution from mining occurs by virtue of their emissions and use of toxic chemicals such as arsenic, mercury, lead and chlorine, among others. According to Garland et al. (1999) soil pollution occurs in the Mankwe, Odi 2, Delareyville, Klerksdorp, Potchefstroom, Schweizer-Reneke, Ventersdorp and Wolmaranstad districts mostly as a result of mining activities.
9.4.4 Veld degradation

Table 9.6 and Map 38 show the level of veld degradation in the North West Province (Hoffman & Todd 1999b). Three measures of veld degradation are presented:
  1. The severity of veld degradation in each of the 28 magisterial districts in the North West Province linking the perceived degree of veld degradation to the perceived extent of veld degradation;
  2. The rate of veld degradation over the last 10 years as determined subjectively by workshop participants;
  3. An Index of Veld Degradation (Map 38) calculated as the severity plus the rate of veld degradation multiplied by the area of grazing land in each magisterial district.
Table 9.6: The severity (degree and extent) and rate of veld degradation in the magisterial districts of the North West Province (N=28), as well as the mean values for commercial and communal areas and an index of veld degradation, calculated as the severity plus the rate multiplied by the % area of veld. (Source: Hoffman & Todd 1999b).
District Land management Severity Rate Index
Ditsobotla Communal 2 2 12
Lehurutshe Communal 3 2 370
Madikwe Communal 3 2 355
Marico Commercial 4 1 410
Molopo Communal 2 1 207
Bafokeng Bafokeng 2 1 102
Brits Commercial 2 -1 63
Koster Commercial 1 0 20
Mankwe Communal 3 1 300
Moretele Communal 2 1 114
Odi 1 Communal 2 1 126
Rustenburg Commercial 2 1 117
Swartruggens Commercial 2 1 195
Bloemhof Bloemhof 1 0 174
Christiana Commercial 1 0 75
Coligny Commercial 1 -1 0
Delareyville Commercial 1 -1 0
Klerksdorp Commercial 1 0 59
Lichtenburg Commercial 1 -1 0
Potchefstroom Commercial 1 -1 0
Schweizer-Reneke Commercial 1 0 52
Ventersdorp Commercial 1 0 51
Wolmaransstad Commercial 1 0 43
Ganyesa Communal 3 -1 124
Kudumane Communal 3 -1 148
Taung Communal 2 3 51
Vryburg Commercial 2 -2 0
Communal districts 11 2.6 0.9 195.3
Commercial districts 17 1.4 -0.1 78.8
Average   1.9 0.3 122.8
Severity
1: Insignificant
2: Light
3: Moderate
4: Severe 		Rate
-1: Slowly decreasing
0: No change in 10 years
1: Slowly increasing
2: Moderately increasing


In comparison with the other provinces of South Africa, the severity of veld degradation of the North West Province is 1.9, third highest of all the provinces. The estimated rate of veld degradation over the last 10 years in the North West Province is 0.3 (second highest of all the provinces), resulting in a fourth highest combined veld degradation index of 122. Veld degradation in the communal districts of the Province exceeds the veld degradation in the commercial districts. The grazing lands of the communal areas are generally perceived to be twice as degraded as those of the commercial areas.

Bush encroachment is perceived as the most important type of veld degradation in the North West Province. It is rated a 1st priority in all the savannah areas of the province (43% of the districts). A loss of vegetative cover and changes in species composition (which together define the concept of "veld condition") only represent the 1st priority in 36% and 14% of the districts in the North West Province respectively. While alien plant invasions are widespread, they are only perceived as a 1st order priority in 7% of the districts. Deforestation is only perceived as a priority in two districts within the North West Province. Other forms of veld degradation appear to be relatively unimportant in the Province (Map 39) (Hoffman & Todd 1999b).

The extent of veld degradation caused by the different types of degradation is linked to the priority given to the specific degradation type. A priority of three indicates that the productivity of the veld is somewhat reduced, but the veld is still biologically intact and restoration possible without major interventions. A priority of two indicates that the veld productivity is greatly reduced and major improvements are required for restoration, while a priority of one indicates that veld degradation had reached such proportions that the veld is not reclaimable at farmer level and major government interventions will be required to rectify the problem.

Loss of vegetation cover and change in species composition
The extent of vegetation cover loss and change in species composition for each of the districts in the three regions of the North West Province is depicted in Map 40 and Map 41 respectively. Loss of vegetation cover and species compositional changes is perceived as more important veld degradation problems in the higher rainfall, grassland-dominated central and eastern parts of the North West Province. While the loss of vegetation cover is perceived as an important veld degradation problem in both the communal and commercial districts, a change in species composition is considered a greater problem in the commercial areas than in the communal areas.

Bush encroachment
Numerous general statements on the extent of the bush encroachment problem in the savannah biome of South Africa exist, but the subject is characterised by a general absence of scientific data. The problem in non-savannah areas is even more poorly described (Hoffman & Todd 1999b). The extent of bush encroachment in 1980 for the old Transvaal and Orange Free State regions of the North West Province are presented in Table 9.7. Although the information is nearly twenty years old and is based on the untested estimates of agricultural extension workers in the regions, it provides a fairly comprehensive picture of the problem.

Table 9.7: The area of bush encroachment in 1980 according to four infestation categories for two pre-1994 agricultural regions in South Africa that today forms part of the North West Province. The data were extracted from Donaldson (1980a) and Fourie (1980), and exclude the communal areas of the former homelands and national states. No data for the other pre-1994 agricultural region, the Highveld region, which also today forms part of the North West Province, is available.

Agricultural
Region		 Infestation category Total
1 2 3 4
  Ha % Ha % Ha % Ha % Ha
Transvaal 222 968 2.2 3 296 082 33.1 No data - 6 456 714 64.7 9 975 764
Free State 802 000 5.5 3 144 000 21.5 5 013 000 34.2 5 700 000 38.9 14 659 000
Total ha & % 1 024968 4.2 6 440 082 26.1 5 013 000 20.3 12 156 714 49.3 24 634 764
The infestation categories are:
1 = Heavy infestations with little or no grass production;
2 = Light to moderate infestations that are getting worse;
3 = Areas vulnerable to bush encroachment (isolated stands may occur);
4 = Areas that are not vulnerable (no isolated stands).

The information shows that, of the more than 24 million ha of veld in the former Transvaal and Orange Free State regions evaluated in the analysis, 4.2% (±1.0 million ha) possessed heavy infestations and 26.1% (±6.4 million ha) was lightly to moderately affected by bush encroachment. A further 20.3% (±5.0 million ha) was vulnerable to bush encroachment and slightly less than half (49.3% or ±12.2 million ha) of the area was not affected by the problem at all. However, communal areas were excluded from this analysis.
Hoffman & Todd (1999b) suggest that bush encroachment remains a serious problem in the North West Province. It is a first, second or third order veld degradation priority in 12 (42,9 %), 2 (7,1%) and 9 (32,1%) of the magisterial districts of the Province, respectively. Only in 5 districts was it not seen as a priority (Map 42). Bush encroachment was considered a first, second or third order veld degradation priority in 12 (70.1 %) of the commercial magisterial districts and 11 (100 %) of the communal districts. The latter result confirms that communal land tenure is not in itself able to control encroaching woody species.

Although bush encroachment is a widespread phenomenon, only a few species are perceived as problematic in the North West Province. The most important of these are a suite of small-leafed Acacia and other legume species, including sweet thorn (Acacia karroo), umbrella thorn (A. tortilis), black thorn (A. mellifera), scented thorn (A. nilotica), candle bush (A. hebeclada), sickle bush (Dichrostachys cinerea) and camphor bush (Tarchonanthus camphoratus). Shrubby encroaching plants include asparagus (Protasparagus) species and honey thorn (Lycium) species. The perceived extent of encroachment by some of these species per magisterial district is shown in Map 43, Map 44 and Map 45.

Alien woody invader plants
The North West Province appears to be relatively lightly invaded by alien species compared to the rest of South Africa (approximately 400 000 ha; 3,5% of the total surface area; Versveld et al. 1998), although the arid western parts of the Province have not been thoroughly mapped. Of the three primary catchments located in the province, the Limpopo catchment seemed to be the worst invaded (5,6% of the total surface area), followed by the Vaal and Orange River catchments. The invasion of tertiary catchments in the Province is depicted in Map 46. The light invasion is primarily attributed to the fact that the Province is the second driest in the country and it is argued that the low rainfall limits the spread of alien invaders, except along riverbanks, where most of the invaders occur at present. The levels of invasion are generally sparse, with some districts being little affected. Local managers view the problems as controllable, with a concerted, dedicated effort (Versveld et al. 1998). The independent results from Le Maitre (1999) conform closely to the above mentioned results. Alien plants are generally not perceived as a veld degradation priority for the North West Province. It was rated as a first, second or third priority in 2 (7%), 3 (11%) and 5 (18%) magisterial districts, respectively (Map 47). Alien plants appear to have an equal priority in communal and commercial areas of the Province.

Versveld et al. (1998) listed a total of 20 invader species in the North West Province. The most important invader specie is mesquite (Prosopis), which has invaded some 210 000 ha, mainly along the seasonal river systems found in the upper Limpopo and the Vaal catchments. Syringa (Melia azedarach), blue gum (Eucalyptus) species and other riparian invaders were surprisingly abundant in the wetter eastern parts of this province, where they are restricted, by and large, to perennial river systems. Riparian invasions are far more important than landscape invasions In the North West Province, in terms of the area invaded the density of the invasions, and the impacts on water resources. Only 4 of the 20 species listed, two of which are aquatic invaders, do not occur in riparian habitats (Versveld et al. 1998).

Deforestation
In South Africa, initial figures suggested that the total annual biomass supply in the communal areas of the former homelands is about 11,6 million tons per year. However, only 50% of this amount could be considered useable for fuelwood, because not all of this production is available to rural people without transport, and because it may not be the right size or species and part of it may also be wasted (Aron et al. 1989). The most recent analysis suggests that the woodlands of the communal areas currently yield 20 % less than this value, or about 4.6 million tonnes of harvestable fuelwood per year (Mander & Quinn 1995). Fuelwood is used by a large number of people, primarily by those living in rural areas and as labourers on farms (97% and 98% respectively). Households in peri-urban areas and townships are less dependent on fuelwood for their energy needs with only 68 % and 38 % of the households respectively using fuelwood (Eberhard 1990).

Data from several household energy surveys indicate that each rural household consumes between 0,9 and 6,9 tonnes of fuelwood per household per year (mean = 3,3 tonnes/year). This gives a per capita fuelwood consumption rate of between 0,5 and 1,28 tonnes/person/year (mean = 0,69 tonnes/person/year) (Williams 1996). If multiplied by the number of households or people living in the rural areas and using fuelwood, then it is clear that the wood resources in the communal areas are under increasing pressure (Van Horen 1994). Fuelwood consumption, however, varies a great deal from location to location depending largely on availability and need (Bembridge 1990). Therefore, generalisations about energy use, fuelwood scarcity and unsustainable rates of harvesting have recently been discouraged (Eberhard & Van Horen 1995).

Hoffman & Todd (1999b) estimated that only the magisterial districts of the former Bophuthatswana (now North West Province) appear to enjoy a surplus of harvestable wood in comparison with other old "homeland" areas. An annual surplus production of approximately 500 000 tonnes of fuelwood is predicted for the Bophuthatswana areas, although local shortages undoubtedly also occur in these areas. Whatever the exact figures, all statistics suggest that less fuelwood is being produced than consumed (Eberhard 1990). Local perceptions confirm this view and suggest that fuelwood availability, together with many other services provided by woodlands, such as fruit and woodcraft species, has decreased in the recent past (Shackleton et al. 1995; Mander & Quinn 1995).

While it may be premature, and perhaps too general for effective planning purposes, Map 48 provides some idea of where deforestation is considered a first, second or third order vegetation degradation priority in the North West Province and according to land tenure system. This clearly shows that deforestation is only to a lesser extent apparent in the North West Province and occurring predominantly in the communal areas (Hoffman & Todd 1999b).

9.5 Impacts

9.5.1 Soil degradation

Soil erosion
The impacts of erosive soil degradation fall into two broad categories, i.e. physical degradation and biological degradation. The impacts of physical soil degradation are structural collapse; densification; degradation of hydrological and thermal properties; desertification; loss of organic matter and dispersion through salinisation. Signs of biological degradation include depletion of organic matter, decrease in soil fauna and an increase in soil-borne diseases (Table 9.8). The biggest impact of man's mismanagement of the soil has been the loss of soil carbon, arising from agronomic cultivation and chemical fertiliser use and the clearing and burning of vegetation and debris, which in turn leads to soil erosion in the chemical, physical and qualitative senses. Further secondary impacts and effects can be categorised as social, environmental and economic (http://enso.unl.edu.htm) (see Table 9.8).

Table 9.8: Primary and secondary impacts of soil erosion.

PRIMARY IMPACT SECONDARY IMPACT
SOCIAL
Marginal lands become unsustainable Poverty, unemployment
Reduced lands become unsustainable Overstocking, reduced quality of living
Employment layoffs Reduced or no income
Food insecurity Malnutrition and famine, civil strife and conflict
Increased pollutant concentrations Public health risks
Urbanisation Social pressure, reduced safety
ENVIRONMENTAL IMPACT
Damage to natural habitats Loss of biodiversity
Reduced forest, crop, and range land productivity Reduced income and food shortages
More dust and sand storms Increased soil erosion, increased air pollution
Decreased soil productivity Desertification and soil degradation (topsoil and erosion)
Reduced water quality More waterborne diseases, increased salt concentrations
Increased incidence of animal diseases and mortality Loss of income and food, reduced breeding stock
Soil desiccation Increased soil mobility
Degradation of landscape quality Permanent loss of biological productivity of landscape
ECONOMIC IMPACT
Reduced business with retailers Increased prices for farming commodities
Food and energy shortages Drastic price increases, expensive imports/substitutes
Loss of crops for food income Increased expense of buying food from shops
Reduction of livestock quality Sale of livestock at reduced market price
Loss of jobs, income and property Deepening poverty, increased unemployment
Less income from tourism and recreation Increased capital shortfall
Forced financial loans Increased debts, increased credit risk for financial institutions


Soil pollution and salinisation
The main impacts of soil pollution through the application of pesticides, herbicides, discharge of solid waste and effluent include:
  1. Alteration of the pH of the soil solution causing mobilisation of heavy metals and immobilisation and precipitation of nutrients leading to reduction in soil productivity due to      fertility decline;
  2. Accumulation of organic and inorganic salts resulting in sodic and saline soils;
  3. Destruction of beneficial micro-organisms;
  4. The gradual and systematic accumulation of potentially toxic levels of carcinogenic chemicals in food plants, which are dangerous to humans and animals;
  5. Soil pollution invariably also results in surface and underground water pollution; and
  6. Compaction and crusting of soils.
9.5.2 Veld degradation

Loss of vegetation cover and change in species composition
Long-term impacts on veld degradation can be measured by the change in hydrological soil factors, as well as erosion severity and biomass production. It also has an effect on the species present. In "good" veld plant cover is high, water infiltration is deeper, and runoff and soil loss rates are reduced (Table 9.9). The nutrient status of the soils is higher in veld in good condition as well as the average dry matter production values. The range of production is greater and water use efficiency values were also enhanced in good condition veld.

Table 9.9: The influence of veld condition on several grassland ecosystem processes (Source: Snyman 1994; 1998). (* = p<0.05; ** = p< 0.01).

Variable Veld condition
  Good Moderate Poor
Mean evapotranspiration (mm/day) 1.73* 1.67* 1.55*
Percolation (>1 m) (% of annual rainfall) 0.5* 0.2* 0.1*
Runoff (% of annual rainfall) 3.50** 5.55** 8.71**
Sediment loss (t/ha/yr.) 0.41** 1.20** 3.55**
Relative loss of organic C (kg/ha 1977-1991) 0 2659 5225
Relative loss of total N (kg/ha 1977-1991) 0 180 331
Mean annual dry matter production (kg/ha)1 1238 768 368
Range in dry matter production (kg/ha) 2678-313 1968-200 889-70
Water use efficiency (kgDM/ha/mm) 2.5** 1.58** 0.78**


1 Statistical information is not provided in Snyman (1998) and the variable is not present in Snyman (1994).

The veld conditions and cover affect grazing capacity. Although data is not available for the North West Province, the number of grazing days per ha increases more than four-fold, from 25 GD/ha in vegetation with the lowest veld condition score to about 108 GD/ha for veld with the highest veld condition score (Danckwerts 1982). Grazing capacity is also affected by annual rainfall. Additionally, the proportion of palatable plant species in a paddock also has a significant effect on grazing capacity (see Barnes et al. 1984).

While long-term profitability and veld condition are believed to be significantly co-correlated in commercial livestock production systems, the relationship between animal survival and veld condition in communal areas is less clear. The survival of animals will depend on the available fodder on the land, which is the result of the condition of the range and the type of plant species (i.e. unpalatable and palatable). The latter two parameters can also be used to calculate the carrying capacity of the land.

The change in production and carrying capacity for three districts, situated in different land types and representing certain soil types in the North West Province are provided in Tables 9.10 to 9.13, to illustrate the importance of veld condition for determining grazing capacity in the Province.

Table 9.10: Production results (kg/ha) of the rangeland in a good, medium and poor condition for the Potchefstroom district (Source: Jordaan 2000).

CONDITION PRODUCTION(KG/HA)
  '94/'95 '95/'96 '96/'97 '97/'98 '98//'99 '99/'00 AVERAGE
GOOD 2830 10314 3868 3009 2303 2981 4218
MEDIUM 1652 - 2753 3840 1517 2856 2524
POOR 1542 5825 2206 2684 1107 2647 2669
Table 9.11: Grazing capacity (Ha/LSU) for the different condition classes for the Potchefstroom district (Source: Jordaan 2000).
CONDITION GRAZING CAPACITY(HA/LSU)
  '94/'95 '95/'96 '96/'97 '97/'98 '98//'99 '99/'00 AVERAGE
GOOD 4.3 1.2 3.3 4.2 6.0 4.8 3.0
MEDIUM 12.3 - 6.5 4.5 11.4 5.8 7.0
POOR 29.5 5.9 11.4 12.1 31.7 29.4 13.7

Grazing capacity calculated only from palatable grass component. Assumption made that one large stock unit needs 10kg per day.

Table 9.12: Production results (kg/ha) of the rangeland in a good, medium and poor condition for the Molopo district (Source: Jordaan 2000).

CONDITION PRODUCTION(KG/HA)
  1998/99 1999/00 AVERAGE
GOOD 1108 1986 1547
MEDIUM 747 1563 1155
POOR 757 1356 1057
Table 9.13: Grazing capacity (Ha/LSU) of the rangeland in a good, medium and poor condition for the Molopo district (Source: Jordaan 2000).
CONDITION GRAZING CAPACITY(HA/LSU)
  1998/99 1999/00 AVERAGE
GOOD 10.9 6.5 8.1
MEDIUM 38.0 10.3 16.2
POOR 53.2 13.4 21.4


Grazing capacity calculated only from palatable grass component. Assumption made that one large stock unit needs 10kg per day.

Bush encroachment

The most important effect of bush encroachment is to lower grass production and reduce the grazing capacity of the veld, especially for purposes of cattle production. It is, however, important to realise that not all species suppress grass production to the same extent. In some situations, some species even has a beneficial effect on grass production and grazing capacity. Estimates of the reduction in grass cover with increasing woody plant cover range from 40-90%. Experiments done on the effect of the removal of trees on grass production in the North West Province suggest an increase in grass production of between 40-500 % (Richter 1991, Meyer 2000a). The increase in grass production is ascribed to the competitive release from trees for water and nutrients and the additional nutrients added to the soil by the decaying above and below-ground parts of trees (Teague & Smit 1992).

Reductions in grazing capacity, as a result of bush encroachment, have been shown to be dramatic. In the Molopo area-grazing capacity has been reduced by at least 50% as a result of black thorn (Acacia mellifera) encroachment (Donaldson 1969). Richter (1991) reported reductions in grazing capacity of 37-77%, in stands of trees with a variety of species, in three veld types in the North West Province. Meyer et al. (in press) reported reductions in grazing capacity between 1990 and 2000 of 80-350%, in a trial evaluating the effect of black thorn (Acacia mellifera) thinning on grazing capacity.

In the North West Province good veld condition and high biomass production can be sustained even at high densities of some bush species. Both camphor bush (Tarchonanthus camphoratus) and silver cluster leaf (Terminalia sericea) may have positive effects on grass production at low bush densities (Meyer 2000b, 2000c). From these results it would seem that high bush densities of these species have a minimal impact on the botanical composition of the herbaceous layer, but suppress herbaceous production. Therefore, it is imperative that high bush densities have to be addressed. Total removal of these species is not recommended although thinning to lower densities should be considered.

Alien woody invader plants

Alien vegetation is often able to develop and spread much more quickly and easily than native species. Such alien plant invasions have a number of significant effects on natural systems and on those which humans have partially or completely transformed. These include both direct and indirect impacts on semi-natural and natural systems. The direct impacts of invaders are those generally recognised by the landowner or manager, for example, the loss of potentially productive land and the associated loss of grazing and livestock production or poisoning of stock (Harding & Bate 1991). Alien vegetation can damage soil properties (e.g. bluegum trees cause acidification of the soil), choke existing areas and prevent access and proper management (e.g. Prosopis). Invasions by alien plants also uses up vast quantities of scarce water, not only reduce the volume of water in streams and rivers, which is available for human use, but also drastically affecting upon ecosystems downstream that depend upon water from higher regions (Le Maitre 1999).

The indirect effects of invaders are caused by the effects that they have on ecosystem processes, structure and diversity, which are essential for maintaining the health of ecosystems. Such effects alter the benefits of those systems to society. The most obvious effect is the reduction in biodiversity caused by alien plants displacing, suppressing and eliminating indigenous species and communities (Richardson et al. 1989). The true costs of these impacts have not yet been estimated for South Africa, but a limited amount of information is available for some resources and from local case studies and this is reviewed below.

Invading alien trees and shrubs also use more water than indigenous species. In South Africa, they are using about 3 300 million m³ of water per year, or about 6.7% of the mean annual surface runoff. The incremental water use (i.e. how much more water is used by the alien invaders when compared with the natural vegetation) of alien invaders in the North West Province reduces the mean annual runoff in the Province by approximately 9%, or the equivalent of 170 mm of rainfall per annum. Five groups of species, i.e. mesquite (Prosopis) species (43%), blue gum (Eucalyptus) species, syringa (Melia azedarach), poplar (Populus) species, black wattle (Acacia mearnsii) and jacaranda (Jacaranda mimosifolia) account for about 90% of the impact in the province. An analysis of the impact on the runoff in the different tertiary catchments in the Province highlights some of the worst affected areas (Table 9.14) (Versveld et al. 1998).

Table 9.14: Summary of the impact of alien plant species on the mean annual runoff (MAR) of tertiary catchments in the North West Province (Source: Versveld et al. 1998).

Tertiary catchment River system Condensed area invaded(ha) MAR(millions of m3) Reduction in MAR
(millions of m3) (%)
A10 Lehurutshe 755 15.03 1.61 10.71
A21 Crocodile (Witwatersrand) 2 039 267.63 16.88 6.31
A22 Elands & Hex 11 006 112.86 25.67 22.74
A23 Sand & Pienaars (Pretoria) 73 163.28 4.58 2.80
A24 Lower Crocodile, Bier & Sand 3 927 137.28 4.72 3.44
A31 Groot Marico 2 846 94.41 0.45 0.48
A32 Lower Groot Marico area 452 43.53 1.08 2.48
C22 Klip (Jhb) & Vaal Barrage 135 131.59 38.11 28.96
C23 Mooi & Upper Middle Vaal 2 044 252.19 8.64 3.43
C24 Schoonspruit & Middle Vaal 1 769 203.17 3.33 1.64
C25 Lower Middle Vaal 4 758 43.39 6.41 14.77
C31 Upper Harts 1 249 86.53 1.45 1.68
C31 Upper Harts 1 249 86.53 1.45 1.68
C32 Dry Harts 12 995 78.70 23.53 29.90
C33 Lower Harts 31 71.18 0.08 0.11
C70 Rhenoster 0   0 0
C91 Lower Vaal (Vaalharts) 2 016 54.74 3.93 7.18
D41 Kuruman/Molopo area 10 137 83.31 12.00 14.40
Total   56 232 1 838.82 152.47 8.29


The direct costs of the water used by aliens are difficult to estimate, but they are undoubtedly substantial when compared with the alternative uses for that water. Analyses of specific catchments and data collated for management plans show that clearing aliens is cost effective compared with building dams to provide the same volume of water (Van Wilgen et al. 1997). Dams will also not be effective if alien plants are using the water they were built to store. The indirect effect of alien invaders on arid areas is more subtle. Invasions by Prosopis in the arid interior depend on groundwater for their survival (Harding & Bate 1991). According to Versveld et al. (1998) Prosopis invasions in the North West Province could be using 41.15 million m³ of water per year, the majority of this from groundwater resources. The groundwater resources are critical for the survival of many farmers and rural communities, but no estimates have been made of the impacts and the potential consequences for humans and for the natural systems (e.g. riverine communities dependent on aquifers in riverbanks and beds).

Invasions by alien plants can also alter the proportion of the rain ending up in spates after storms, reduce groundwater recharge and alter sediment dynamics in stream and river courses, contributing to the silting up of dams (Wells et al. 1980). Black wattle (Acacia mearnsii) is an example of a species which stabilises sediments by colonising deposits, (e.g. banks) but its shallow root system is easily washed out during floods, releasing sediments and blocking bridge arches and storm drainage systems. Willow (Salix) and poplar (Populus) species develop very extensive root systems, which tend to trap and stabilise sediments. Both forms of stabilisation can aggravate flood damage by obstructing and narrowing the channel, or tightening the curvature of bends, increasing flow rates and the energy available for scouring (Le Maitre 1999). The estimated flood damage caused directly by invading alien plants blocking the Crocodile River near Brits, and making it burst its banks in 1996, was R6 million (Le Maitre 1999).

Invasions by woody aliens generally result in changes in species composition and vegetation structure, altering the ecological functioning and resilience of ecosystems. The reduction in the biodiversity in natural communities, caused by alien plants displacing, suppressing and eliminating indigenous species is easily observed. Thickets of alien plant species can also increase the fire hazard, increasing the costs of fire protection and the degree of damage caused by fires (Richardson & Cowling 1992). Invaders can also increase soil erodibility and erosion rates by suppressing the ground-layer so that the root mat no longer binds the soil as effectively (Le Maitre 1999). The direct economic impacts of invasions by alien plants include the loss of potentially productive land, loss of grazing and livestock production, poisoning of humans and livestock, increased costs of fire protection and damage caused by fires (Richardson et al. 1997). They also include opportunity costs, where the money spent on control operations could have been spent on other activities. Versveld et al. (1998) estimated that, if alien invasions were increasing at 5% per year, a 20-year programme to control alien plants would have to clear about 750 000 ha per year and would cost about R600 million per year. This money could have been invested in other ways, for example in improving educational facilities.

The costs of controlling alien invaders are high and typically increase exponentially with increasing density from R300/ha for sparse to R4 000/ha for dense stands (Versveld et al. 1998). Based on data from the labour intensive Working for Water alien invader eradication programme, it was estimated that the mean cost of clearing one hectare of invader plants in the Province (at 1997 prices) is R136. This adds up to a total of approximately R232 million to clear all invader plants in the Province. The figure is based on the assumptions that a clearing programme will take about 20 years to complete and that all species are cleared everywhere (no priorities are set). The total area invaded by aliens is expanding at about 5% per year there are no improvements in the efficiency of clearing operations. Biocontrol does not reduce control cost and the cost should also allow for expenditure on the social requirements of the Working for Water programme.

Deforestation

There are both environmental as well as social costs associated with deforestation, but because the woodlands provide many other products beside fuelwood, it is often very difficult to isolate the impacts of fuelwood collection on woodland ecosystems and human society. Exploitation of natural woodlands and forests to meet energy and construction needs has led to the depletion of resources, and degradation of these systems. Some of the most important environmental costs of deforestation include increased rates of soil erosion, disruption to the hydrological and nutrient cycles and the loss of biodiversity. Perhaps the most important impact that deforestation has on the environment is its influence on ecosystem composition and diversity. The general pattern in heavily utilised areas is a conversion from an open savannah with tall, older trees to shrubby woodland with many smaller shrubs and trees (Gandar & Grossman 1994).

Increased rates of soil erosion are usually measured in woodlands denuded of tree cover. Although less effective than grasses, trees can also reduce the kinetic energy of rain drops and attenuate erosion rates (Milton & Bond 1986). Tree roots also bind the soil and assist in reducing soil erosion. When accompanied by heavy grazing of the ground layer, erosion rates in deforested areas can be extreme (Scholes et al. 1993, Van Horen 1994) although no published comparative data are available. Deforestation can also lead to significant changes in the hydrological cycle in affected areas. Greater discharge rates during high rainfall periods and lower discharge rates during drier rainfall periods are thought to occur in denuded areas (Van Horen 1994). It is possible that deforestation may similarly affect nutrient cycling processes through the loss of soil carbon because of lowered inputs. If tree stems are removed then leaf litter will also be reduced in the long-term. However, more studies on the impact of deforestation on nutrient cycling are needed.

The removal of dead wood could have a negative effect on the diversity of mammals, birds and insects by removing cover and nesting material. For example, it is estimated that between 35% and 50 % of resident forest bird species in southern Africa rely on cavities either for roosting or breeding or both of these activities (Du Plessis 1995). It appears that invertebrates may be similarly affected by the removal of nesting material. The denudation of woodlands also has important social costs, especially for women who collect the wood. The most important social costs of deforestation include the increased time spent collecting fuelwood, heavier wood loads, the negative effects of coping in the home with limited fuelwood supply and the increased cost of paying for alternative fuels (Van Horen 1994).

Data from several household energy surveys indicate that people (mostly women and children) who collect fuelwood for domestic consumption already spend on average about 3.6 hours per trip collecting wood. They often travel considerable distances ranging, from about 3 to 8 km, and may do this several times a week. If local fuelwood supply and also the supply of desirable species decrease, through unsustainable harvesting practices, then the time and energy spent collecting will also increase (Shackleton et al. 1995). Van Horen (1994) has calculated that the total annual opportunity cost associated with women's time spent collecting fuelwood in South Africa already amounts to about R1.5 billion. If just half an hour more is needed per trip then this increases the cost by R150 million.

It has also been found that increased fuelwood scarcity generally leads to an increase in the weight of each fuelwood load. There are obvious health costs associated with the carrying of heavy loads of wood over long distances over several years or decades. Other health costs arise when fuelwood scarcity forces the introduction of various "cost-cutting" measures or coping strategies such as the implementation of bulk cooking, reduced cooking time, or fewer cooked meals (Van Horen 1994). Finally, as fuelwood scarcity increases, people may be forced to spend more of what little money they have on commercialised fuels thus exacerbating the already dire problem of rural poverty.

9.6 Responses

An impressive array of responses to land degradation and desertification in the form of intervention schemes, strategies, policies and legislation have been undertaken, by both the national and provincial government, as well as individual Departments. These include past initiatives, such as the stock reduction schemes (1969-1978), the Betterment Scheme (1930) and the National Grazing Strategy of 1985.

9.6.1 National legislation
The legislation pertinent to land degradation in South Africa, and its possible effect includes:
  1. Environment Conservation Act (No. 73 of 1989);
  2. National Environmental Management Act (No. 107 of 1998);
  3. Atmospheric Pollution Prevention Act (No. 45 of 1965);
  4. National Water Act (No. 36 of 1998);
  5. Hazardous Substance Act (No. 15 of 1973);
  6. Health Act (No. 63 of 1977);
  7. Conservation of Agricultural Resources Act (No. 43 of 1983);
  8. Fencing Act (No. 31 of 1963);
  9. Fertilisers, Farm Feeds, Agricultural Remedies and Stock Remedies Act (No. 36 of 1947);
  10. Subdivision of Agricultural Land Act (No. 70 of 1970);
  11. Subdivision of Agricultural Land Act Repeal Act (No. 64 of 1998);
  12. Agricultural Pests Act (No. 36 of 1983);
  13. Agricultural Research Act (No. 86 of 1990); and
  14. Plant Improvement Act (No. 53 of 1976).
The most important is the Conservation of Agricultural Resources Act (CARA). The CARA deals with the use and protection of land, wetlands (e.g. vleis, marshes) and vegetation and the control of weeds and invader plants, including both indigenous weeds - also species involved in bush encroachment - and invasive exotic species. In terms of weeds and invader plants, the Act covers all land in South Africa, including land situated in an urban area, except for areas declared under the Mountain Catchment Areas (Act No. 63 of 1970). The introduction of the concept of sustainability by the CARA, the Environment Conservation Act and the Environmental Management Act implies that landowners are obliged to manage their land and natural resources sustainably. This approach has been extended through the inclusion of sustainability as a basic principle in the National Constitution. It is further strengthened in the Principles of the Water Act, the Environmental Conservation discussion document and the Forestry White Paper (Le Maitre 1999).

9.6.2 International agreements

Government has acceded to (or is in the process of acceding to) a total of 44 environmental related international conventions and/or treaties. International agreements pertaining to land degradation include:
  1. United Nations Convention to Combat Desertification (UNCCD) - Basic principles of the UNCCD include the development of strategies to combat desertification and drought through:

  2. United Nations Convention on Biological Diversity (CBD) which aims to effect international co-operation in the conservation of biological diversity and to promote the sustainable use of living natural resources world-wide. Membership of this convention has led to the publication of the White Paper on the Conservation and Sustainable Use of South Africa's Biodiversity (DEAT 1997), which aims to ensure the sustainable use of biodiversity into all sectors, including industry (DEAT 1999). In terms of Article 8 of the Convention, the state is also required to prevent the introduction of those alien species, which threaten ecosystems habitats or species and, where they already occur, to control or eradicate them, and to rehabilitate and restore degraded ecosystems (see chapter 11).

  3. United Nations Framework Convention on Climate Change (UNFCCC). The ultimate objective of the convention is to stabilise greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous interference with the climate system of the world (see chapter 8). The consequences of this for the distribution of biomes and species, and therefore the composition of biomes, will depend on its effectiveness, and on the time delay in regulating concentrations of greenhouse gases in the atmosphere (DEAT 1999).
9.6.3 Government intervention schemes

Land conservation
The Stock Reduction Scheme was applied in commercial rangeland areas from 1969-1978. Its main objectives were to reduce the livestock numbers on rangelands, withdraw eroded and vulnerable areas from grazing, and institute judicious management practices on remaining rangelands. Targeted regions included the western parts of the Savannah and Grassland Biomes that are found in the North West Province. Although R54 million (1978 value) was spent on the scheme, a critical appraisal of this scheme concluded that this amount could not be justified given the inherently low production potential of its target areas (DEAT 1999).

The National Grazing Strategy (NGS) was announced in 1985. Its main objective was to use, develop and manage the natural and cultivated pastures in the RSA sustainably (specifically excluding those in communal areas). Although it had no legal status, several clearly defined actions were proposed. Progress with the scheme seemed mixed after 6 years (Du Toit et al. 1991). Improved law enforcement led to several farmers being successfully prosecuted under the Conservation of Agricultural Resources Act during the 1990's. Greater conservation awareness amongst farmers had been achieved, while research progress improved the knowledge base and understanding of the functioning and management of veld and pasture management.

Numerous government funded Drought Assistance Schemes have been implemented over the last several decades, the most recent being the Disaster Drought Assistance Scheme for stock farmers (effected during 1990). This scheme was linked to the Conservation of Agricultural Resources Act of 1983 and to the implementation of the National Grazing Strategy. While the improvement of veld condition may have been an important argument for introducing the scheme, critics argued that this scheme had more to do with writing-off or rescheduling of debt, than direct drought relief. As a result, it favoured continued farming by the most indebted commercial farmers, preventing foreclosure of a number of farms and thus representing a lost opportunity for land reform (Rimmer 1993).

The South African LandCare Initiative, inspired by a similar successful initiative in Australia, was launched in 1998. Based on the ideal of sustainable agricultural resource utilisation as the basis for establishing a conservation ethic, it includes natural resource, sociological, political and economic dimensions (DEAT 1999). The National LandCare Programme is a community-based and Government-supported land management programme. It will offer financial support to LandCare community groups who will identify, implement and monitor the conservation activities needed to address their land degradation problems. LandCare projects are funded and co-ordinated on national level and carried out on Provincial and local level. Local communities are, however, the stakeholders of LandCare projects.

The LandCare Programme aims to develop and implement integrated approaches to natural resource management in South Africa, which are efficient, sustainable, equitable, and consistent with the principles of ecologically sustainable development. This implies that cultivation, livestock grazing and harvesting of natural resources should be managed in such a manner that degradation (such as soil erosion, nutrient loss, loss of components of the vegetation, increased runoff of water, etc.) is curtailed. The core element of LandCare South Africa is the empowerment of people to take responsibility and care for their own environment through knowledge and understanding. The National LandCare Programme encompasses several components. The Focussed investment and Small Community Grant components are both intended to provide resources for projects that facilitate the achievement of the programme objectives by focussing on three major themes. The primary focus is to encourage best practice in land management. The North West Province operates within the theme of Veldcare, which addresses the reduction of plant cover in grazing lands, exposure of soil to erosion and deterioration of the plant species composition relative to the nutritional requirements of grazing animals. The majority of projects in the Province focus on bush control, due to the negative effects of widespread bush encroachment on livestock numbers and veld productivity.

A Junior LandCare Programme focuses on improving the quality of life of previously disadvantaged youth through promoting sustainable natural resource use. The Local Economic Development component is based on the initiatives of local stakeholders. It involves identifying and using local resources, ideas and skills to stimulate economic growth and development in order to create employment opportunities for local residents, alleviate poverty, and redistribute resources and opportunities to the benefit of all local residents. The following 5 elements serve as the basis for the implementation of LandCare projects:
  1. Major work programmes for resource conservation;
  2. Capacity building of local communities and support staff;
  3. Awareness programme;
  4. Policy and legislation, and
  5. Research and evaluation.
The programme is slowly expanding and implementation in the North West Province was supported by funding to the extent of R 1,2 million (0,05% of the national budget) in 1998/99, R 2,9 million (15% of the national budget) in 1999/00, R 3.0 million for 5 projects (10% of the national budget) in 2000/01 and R 4,5 million for 14 projects (12,9% of the national budget) in 2001/02.

Bush encroachment
During the 1970's, bush eradication subsidy schemes were initiated to assist farmers to control bush encroachment. The then Department of Agriculture and Fisheries funded, as part of a loan scheme, the control of black thorn (Acacia mellifera) in the Molopo area. By 1980, local Soil Conservation Committees had become involved in the assessment of the problem (Baard 1980) and the participants attending a national bush encroachment workshop felt that more extensive state intervention had become necessary to deal with the problem (Hoffman & Todd 1999b). Two separate bush eradication schemes were introduced under the Conservation of Agricultural Resources Act 43 of 1983. The first lasted from 1986-1991 in the Kuruman, Postmasburg and Vryburg districts (Baard 1980). In the Kuruman district the scheme was popular amongst the farming community. About 212 000 ha (or 12 % of the district) was treated and about 40 % of the 450 farmers participated in the scheme at a total cost to the state of R2.65 million for the district. (Wynand Nel, Extension Officer, Kuruman, personal communication). The second subsidy scheme was introduced from 1991-1995 in the Vryburg district. It provided subsidies for aerial and manual application of arboricides, depending on the density of trees in the target area. A total of 140 farmers participated over the five years and about 60 000 ha, or 2 % of the 3.2 million ha in the Vryburg district was treated (Philip Olivier, Extension Officer, Vryburg, personal communication).

From 1996-2000, a new programme, the Bush Control Educational Programme in Previously Disadvantaged Communities and Neighbouring Commercial Farming Areas was introduced by the National Department of Agriculture. The programme focussed on empowering extension officers and farmers in previously disadvantaged communities in the Lehurutshe, Ganyesa, Taung and Kudumane districts. Training of extension officers formed an important part of the programme. They had to convey the message of bush encroachment and control to the farmers in their extension areas. The establishment of plots to demonstrate the effect of bush encroachment on grass production, as well as the effectiveness of a range of bush control measures in local communities, supported the training. The establishment of the plots was subsidised by the National Department of Agriculture, who also provided limited subsidies to commercial farmers in the Marico district for the establishment of similar demonstration plots on a number of farms.

Woody alien invasive plants
Despite the fact that landowners and land users are under a legal duty to remove invasive alien plants, the state, through the various government agencies, has over an extended period provided assistance in many ways and in a wide variety of control schemes. This is in addition to the biocontrol programmes funded through the Plant Protection Research Institute. Considerable amounts have been spent on controlling and subsidising the control of invading cactuses (Le Maitre 1999).

The CARA allows the Minister to establish subsidies and grant schemes for combating weeds or invader plants, including supplying weed killers and providing advisory services. Land can also be expropriated to restore or reclamation of the natural agricultural resources. In 1996 subsidies were available for controlling Opuntia species (prickly pears) in the Republic (Regulation No. R. 1044). A clearing programme for Cereus peruvianus (Queen of the Night) was launched in 1994 and has resulted in the clearing of 8 767 ha of the 11 037 ha originally invaded.

South Africa has a number of highly successful biological control programmes for different species (Richardson et al. 1997). One of the best known is for the control of the 12 cactus species, which have been introduced to this country. A few decades ago, Prickly Pear (Opuntia ficus-indica) became very widespread and dense invasions covered about 1-million ha. Mechanical control was not successful and biocontrol was introduced in 1932, after substantial resistance by farmers who cultivated the spineless form. Following biocontrol, and the introduction of additional agents, the total area was reduced to 350 000 ha by 1965 (Neser & Annecke 1973). However, funding for the biocontrol of environmental weeds was drastically cut during the reorganisation of agricultural research in the early 1990s. This programme is currently being supported by the Working for Water Programme.

The Working for Water Programme: This programme, with its focus on eradicating invasive alien plants and on rehabilitating wetlands, may be seen as a practical initiative by the government of South Africa to discharge the responsibility placed on it by the Convention on Biodiversity. The programme was launched in 1995 with the aims of sustainably controlling alien plants to increase water yield from catchments; conserving biodiversity and land productivity; and providing worthwhile employment and improving the life-skills and quality of life, particularly of the unemployed and poor, in rural and urban communities (Le Maitre 1999).

The Programme has the potential to make a significant impact on alien invaders in the country. It is in a unique position to co-ordinate the existing control measures and make really effective use of the available resources, unlike the scattered efforts in the past. In certain areas the programme employs area and project managers to manage clearing and rehabilitation work, in other areas implementing agents are appointed for this purpose. The programme has grown to be probably the largest alien invader-clearing programme in the world (Le Maitre 1999). In 2001, the total area that had been initially cleared was about 170 000 ha and follow-up operations had been done on 183 000 ha. Total direct employment in 2001 was 23 998 people, excluding management. In the North West Province, a limited number of projects employ 1428 workers (Working for Water 2001).

Deforestation
Several recent initiatives, however, have placed the issue of fuelwood security and deforestation on the national agenda. One of the most important of these is the Biomass Initiative, which was started in 1992 to assess the fuelwood situation in South Africa, and to make recommendations for intervention (Williams et al. 1996). The establishment and management of woodlots have been a key government response in communal areas. Several new projects are also currently underway to establish woodlots for firewood in order to address the imbalance between supply and demand (Van Wyk & Gericke 2000). A total of 38 woodlots exist in 8 districts of the North West Province, covering a total area of 1069 ha. The first woodlot was established in 1947, followed by another 22 during the 1940s, 1950s, 1960s and 1970s. The average size of these earlier woodlots is more than 40 ha. Another 15 smaller woodlots (average size of approximately 7 ha) were established during the late 1980s and early 1990s. The woodlots (blue gum trees) (Eucalyptus) were planted to provide firewood, windbreaks and poles. Although not primarily aimed at addressing the problems of deforestation, the supply of cheap electricity is an important priority in South Africa and will have some effect on the use of fuelwood. Eskom, supported by government initiatives to reduce poverty, is busy with extensive electrification programmes in urban and rural areas throughout South Africa. At present large numbers of households are connected to the national electricity grid annually.

9.6.4 Research and development

Veld management systems
The Department of Agriculture has a long history of research into the development of appropriate veld management systems for particular commercial livestock production areas. This effort has resulted in several regional accounts, in varying degrees of detail, which outline the most appropriate system for a particular area (e.g. Fourie et al. 1982). These accounts generally provide information on stocking rate, rotational grazing, resting and burning regime, paddock layout and implementation and are usually derived from research projects. Local agricultural extension officers are usually trained in the principles of each system and incorporate such a veld management approach in farm planning guidelines.

The same long history of research has not occurred in South Africa's communal areas (Bembridge 1988). While interest has increased dramatically in recent years, most research is still in a descriptive phase of defining differences in management objectives, production coefficients and resource status between communal and commercial areas. Hoffman & Todd (1999b) cautions against imposing the ideas developed from commercial agricultural research programmes directly on communal areas to fill the knowledge vacuum that clearly exists, as the theoretical basis for communal management objectives is questionable and they have generally failed elsewhere in African communal areas in the past. Similarly, however, the imposition of ideas which stem from a new thinking that animal numbers are not a critical issue in communal range management (Behnke et al. 1993) might be equally inappropriate. A long and difficult road lies ahead and extreme caution is advised before replacing existing land use practices and policy on the basis of some dogmatic bias (Hoffman & Todd 1999b).

Alien woody invader plants
The North West Department of Agriculture, Conservation and Environment (Directorate Technical Support Services) has also played a leading role in doing research with regard to the chemical control of Prosopis in South Africa. Since the early 1990's, a research programme in the Vryburg district has attracted the attention of several key role players. A collaborative research project, involving private sector agrochemical companies is currently underway.

9.7 Outcomes

Various interventions have been implemented on a national scale in South Africa. Most of these interventions, especially the LandCare and Working for Water programmes, are focussed on the communal and formerly disadvantaged regions in the country. These programmes do not only aim to address the problems of land degradation and natural resource conservation, but also the poverty problem in South Africa. Inherent to all projects are job creating initiatives contributing to an increase in the standard of living and improvement in livelihoods of the formally disadvantaged, of the poverty stricken communities. It is a great challenge to manage programmes based on resource conservation and land degradation problems in such a way that they will be sustainable in the long term. This will require the communities, who are the main stakeholders, to adopt the principles, processes and technologies for natural resource conservation and combating of degradation and desertification. With balanced attention to the needs of both the commercial and communal sectors, through research, extension and education, as well as a renewed focus on conservation in general, land degradation can be halted. These efforts can result in credible, improved management practices to help ensure sustainable utilisation (DEAT 1999).

In terms of soil degradation, erosion control programmes have rarely been successful in the North West Province, as these were imposed on farmers who were expected to supply labour without obvious benefits (Booth 1994). In addition, many of these programmes aimed at treating the symptoms of erosion, rather than the causes of soil degradation. The development of soil erodibility and sediment yield maps is expected to increase the efficiency of soil conservation efforts. The outcomes of various interventions have been more successful in the commercial districts than in the communal areas. This is attributed to, among others, the active role of the North West DACE in commercial areas, State subsidies for soil conservation works, the application of the Agricultural Resources Conservation Act of 1983 and better cultivation and irrigation practices. The same has not been done to the communal areas due to the neglect of these areas by the previous regime. In terms of bush encroachment, some of the activities conducted under the bush eradication schemes had positive outcomes in the districts where they were implemented. In all of the areas, individual farmers are currently practising bush control on a voluntary basis. However, this practise is also being applied in areas where the schemes were never implemented, possibly due to higher levels of awareness in the Province generally.

Government's response in terms of providing a legislative framework for dealing with the alien invader plant problem has certainly been successful in providing a comprehensive framework for dealing with the problem, and should definitely succeed in preventing the continued introduction of potentially new invader species. Large quantities of resources have also been spent on controlling and eradicating alien invader plants. Although the success of some efforts, especially the biocontrol programmes, is not always as visible as some of the other efforts, they play a very important role in dealing with the issue in an integrated way. Other efforts, such as the Working for Water programme and the LandCare Initiative, have established an impetus with regard to the problem and should be sustained. These programmes should be used as the vehicle to not only address the eradication of invader plants in new areas, but also the continued efforts to follow up the re-establishment in areas that had previously been treated (Le Maitre 1999).

The establishment of woodlots in communal areas have played an important role mitigating against deforestation in some communal areas (Gandar 1988), but have also been relatively unsuccessful in others (Bembridge 1990). The condition and yield from woodlots is currently low and they probably contribute less than 80 000 tons per annum or about 1% of the total amount of fuelwood consumed in communal areas in South Africa (Aron et al. 1989; Eberhard & Van Horen 1995). On their own, woodlot development programmes are clearly not able to solve the fuelwood crisis for South Africa. Even if land were available for woodlots, dramatic improvements in management and access would be needed if they were to contribute meaningfully to rural people's livelihoods. The provision of electricity should definitely contribute in reducing deforestation. Although many rural households may be able to afford the cost of electricity, the very poor will most probably continue to rely primarily on fuelwood for their energy needs. This is clearly illustrated by the continued use of large quantities of firewood, even in areas with a reliable supply of electricity (Eberhard et al. 1991).

9.8 Linkages

This chapter has linkages with:
  1. Chapter 3 on the social environment;
  2. Chapter 4 on the economic environment;
  3. Chapter 5 on policy and legislative environment;
  4. Chapter 6 on settlement and land use patterns;
  5. Chapter 7 on major economic and industrial activities, especially mining and agriculture;
  6. Chapter 10 on water resources;
  7. Chapter 11 on biodiversity and conservation;
  8. Chapter 12 on heritage resources;
  9. Chapter 13 on human health and well-being; and
  10. Chapter 15 on environmental monitoring, auditing and rehabilitation.

9.9 Data Issues and Indicators

9.9.1 Land degradation
Agricultural and environmental officers, extension workers, as well as contributions mainly base data regarding the degradation and desertification problem in South Africa, and especially the North West Province, on qualitative assessments by land users. This is mainly true for the commercial agricultural sector of the province, since very little work regarding the quantitative evaluation of the degradation problem has been carried out in the communal and formerly disadvantaged areas, including the former homelands and TBVC states.

Soil pollution and salinisation

Scattered data are available from various research initiatives:
  1. Pollution insurance for the agricultural sector (Aihoon 1994);
  2. General soil degradation (Garland et. al. 1999);
  3. The nature and properties of soils (Brady 1990);
  4. Land reform (LAPC1995).
However, there is no monitoring programme in place in the North West Province.

Soil erosion
Scattered data on soil erosion are obtainable from various research materials, journals, technical reviews and texts. However, data availability is fragmented and often outdated.

9.9.2 Veld degradation
Loss of vegetation cover and change in species composition
Current projects and initiatives are based on the work carried out by Hoffman et al. (1999), which serves as a basis for the South African National Action Programme for the CCD. A few localized studies have been carried out by the North West DACE, which include reports that form part of the Environmental Impact Assessments necessary for resettlement schemes conducted by the Department of Land Affairs. There is no coherent monitoring programme within the Province.

Bush encroachment
Quantitative data regarding the extent of bush encroachment in the North West Province is limited to the assessments made for the 1980 bush encroachment workshop of the Department of Agriculture. This primarily relates to the commercial agricultural areas of the Province. The qualitative assessments made by agricultural extension officers during the 1997 workshops to establish a degradation baseline for the Province (Hoffman 1999), represent the only comparable data available for the Province as a whole. Quantitative data describing the impact and management of the bush encroachment problem from a number of localised research projects are available from the provincial North West DACE.

Alien woody invader plants
As a result of the study by Versveld et al. (1997), good baseline data on the extent of alien invader plants currently exists for the province, although it is lacking for the more arid, western parts of the Province. The Plant Protection Institute of the Agricultural Research Council managed the National Plant Invader Atlas project during the 1990's in which all exotic plant invasions were mapped. The North West DACE has contributed towards the compilation of the Atlas.
The North West DACE has also been involved in developing a methodology for evaluating the extent of Prosopis invasions on a farm scale. This methodology has been successfully used in determining the extent of Prosopis invasions in the Wolmaranstad, Bloemhof, Schweizer-Reneke and Christiana districts on a farm scale. Data on the presence of Prosopis invasions in the Vryburg districts are available from North West DACE, while some data on invasions of other species are available from the Directorate Resource Conservation of the National Department of Agriculture.

Deforestation
There have been several recent attempts to develop a woody biomass inventory for South Africa (e.g. Mander & Quinn 1995, Williams 1996). Although much is, therefore, known about fuelwood supply and demand in the communal areas of the former homelands and national states (see Mander & Quinn 1995, Williams et al. 1996), no map has been produced of areas in the country subject to deforestation.

Data on woodlots in the North West Province are available from the community forestry branch of the regional offices of the Department of Water Affairs and Forestry.

9.9.3 Indicators

The main indicators used to evaluate the extent and severity of veld and soil degradation are the Veld Degradation Index (VDI) and Soil Degradation Index (SDI), developed by Hoffman (1999). The amalgamation of these two indices forms the basis for the Combined Degradation Index (CDI).
The Veld Degradation Index (VDI) is calculated as the sum of the severity and rate of veld degradation multiplied by the % veld in a district (Map 38). The VDI considers all the types of veld degradation, including the loss in vegetation cover, change in species composition, bush encroachment, alien plant invasions, deforestation and other degradation impacts.
The Soil Degradation Index (SDI) is calculated as the sum of the severity and rate of soil degradation for each land use type multiplied by the % area of each land use type, added together to calculate one SDI (Map 33).
The Combined Degradation Index (CDI) is calculated by adding the soil and veld degradation indices together to form a single combined index of land degradation, which incorporates, both soil and vegetation parameters (Map 32).

Other possible land degradation indicators include:

  1. Consensus estimates of the occurrence and extent of different types of land degradation e.g. soil erosion, soil pollution, change in species composition, bush encroachment and deforestation, based on expert opinion and obtained through a rapid appraisal strategy, such as developed by Hoffman et al. (1999), could provide important information that could be used as indicators.
  2. Distribution of specific species:
  3. Percentage change in land cover over time.
  4. Consumption of coal and electricity.
  5. Rate of electrification.
The South African national Department of Environmental Affairs and Tourism is currently in the process of selecting national environmental indicators for use in South Africa A list of potential indicators of land transformation is presented in Table 9.15 as proposed in the National Core Set of Environmental Indicators, DEAT 2001. In addition to the indicators proposed above, it is recommended that the North West Province identify appropriate indicators from this national set which they can then use at a provincial level for reporting on land transformation.

Table 9.15: The proposed list of Land Transformation Indicators for South Africa (Source: DEAT, 2001).

Issue Indicator Type Level Frequency Scale Linkages
Land degradation
Soil loss S 2 5 yearly National  
Extent of Land Degradation P 2 5 yearly National UNCCD
Wasted and degraded land in mining zones S 2 5 yearly National  
Quality of mining operations R 1 Annual National  
Land use management
Change in land use over time S 2 5 yearly National UNCCD
Enforcement of the Conservation of Agricultural Resources Act R 1 Annual Provincial  
Land Productivity vs Potential S 3 5 yearly National  
Permanent loss of agriculturally productive land S 3 5 yearly National UNCCD
Integrated Issues
Land degradation per GDP in the mining sector P 1 Annual Sectoral  
Wasted and degraded land in mining zones per GDP in the mining sector S 2 Annual Sectoral  
UNCCD: United Nations Convention to Combat Desertification

Type refers to the D-P-S-I-R model categories (Driving Forces, Pressures, States, Impacts, Responses respectively).

Level indicates the current availability of information pertaining to each indicator:
Frequency refers to the proposed frequency of reporting on each indicator for meaningful results and trends to be obtained. However, data collection will necessarily be more frequent than the reporting frequency.

Scale refers to the geographical scale at which the indicator is applicable: national, provincial, local or catchment level.

Linkages refers to possible commonalities between the particular indicator and other indicators used for reporting obligations as required by international conventions ratified by South Africa.

Please refer to the section on environmental and sustainable development indicators for more information on these proposed indicators for future monitoring and reporting.

9.10 Conclusions and Recommendations

9.10.1 General land degradation and desertification
As in all other parts of the world, but mainly in arid- and semi-arid regions and especially the African continent, land degradation and desertification is becoming increasingly important for scientists, land users and policy makers. With the ever increasing human population and the demand for food and water, the pressure on land and other natural resources has never been greater. Climatic variation, erratic rainfall patterns and injudicious management strategies, including phenomena such as global warming and ENSO, all contribute to degradation and desertification.

Although recent efforts to address land degradation and desertification problems have been directed towards the communal and formerly disadvantaged areas of the province, a vacuum concerning the knowledge and understanding of communal land management still exists. Agricultural and other initiatives should be cautioned, not to impose the ideas and understanding obtained from research obtained from the commercial areas, directly onto communal areas. Since most of the National initiatives that address the problem of land degradation and desertification focus on the higher degraded communally-managed sector of the country, it is unlikely that the commercial agricultural sector will continue to receive the same attention as before. This does not mean that the long time experiences, data and principles that have been researched and gathered through the years in the commercial agricultural sector, have to be ignored or left out of consideration when the degradation and desertification problem is being addressed. Some of the main measures that must be taken into account when combating land degradation and desertification, include:
  1. Reduce stock numbers on the grazing land, especially during times of drought;
  2. Sow suitable grass seed in severely degraded areas;
  3. Avoid over cultivation, which is unsuitable for cropping;
  4. Improve the grazing capacity of the land by following sustainable management practices and controlling invasive plants and alien plants;
  5. Enrich the degraded soil by organic material (dung or compost) to promote the infiltration of water, better the growing conditions of suitable plants and preventing runoff and erosion;
  6. Combat poverty by increasing food security and by providing alternative livelihoods.
There are several reasons why the combating of land degradation and desertification can fail. These include:
  1. The multivariate conditions of the degraded sites, which include climatic and physical factors;
  2. Inadequate understanding and awareness of the principles of degradation and ecosystem functioning as a whole;
  3. Ignorance and uncertainty by the land users about the most appropriate technologies for combating degradation and desertification;
  4. The absence of proven techniques that the land user can refer to before applying a specific technology;
  5. The negative cost/benefit ratios of technologies applied to combat degradation over the short term and the uncertainty about comparative costs and benefits of the different technologies;
  6. Insufficient collaboration and co-operation between all parties involved in the process of combating desertification;
  7. Land users and managers, especially in the unprivileged and underdeveloped area of Africa, are more concerned about the day-to-day family survival issues, such as water and food supply, sanitation and housing;
  8. Unsecured land tenure policies; and
  9. Failure to implement all aspects of combating desertification strategies.
If the above problems are not addressed effectively, efforts at combating land degradation desertification will most probably prove to be worthless.

9.10.2 Soil degradation

Soil erosion
Soil degradation through erosion is becoming a major problem and has the potential to have serious social and economic implications. Soil degradation for the North West Province is found to be very high compared to other provinces. Severe degradation of croplands, veld/grazing land and settlement areas occur in most parts of the Province. With a soil degradation index of 149, the North West Province has the fourth most degraded soils in South Africa. Soils of communal areas are more degraded than those in the commercial areas. A focused and dedicated implementation of all statutory laws and legislation as well as soil conservation measures is an urgent necessity to remedy the extent of degradation. Control of livestock numbers, adoption of proper cultivation practices, provision of wind breaks and control of fires which exposes the soil to wind and water action needs to be seriously considered for implementation.

There is also an urgent need for better education and agricultural extension programmes, farmer study groups and Soil Conservation Committees to raise the level of soil conservation. Veld management programmes including longer resting cycles, rotational grazing systems, and increased planted pasture area, which will reduce the pressure on the veld, needs to be implemented. There is a need to assess farm sizes and to increase the average farm size in order to facilitate lower stocking rates. An improvement in the meat and milk price will result in farmers surviving with fewer animals.

Soil quality
Solid waste and effluents from industry, manufacturing and household sources as well as ammonium based fertilisers and chemicals are the most important soil pollutants of the North West Province. However, the amplitude and impact of these have not been assessed and quantified. Urban run-offs containing various levels of waste and effluents are also major sources of soil pollutants, which include various forms of organic and inorganic contaminants. Values for soil chemical or biological pollutions are unavailable for the Province. It is recommended that in the interim, critical minimal levels established for other countries could be adopted as the Province takes steps to investigate and adopt its own critical values. Secondly, industries known to be major polluters may be mandated (with punitive measures if failed to comply) to submit regular reports on the degree of pollution of soils around their areas of operation to a monitoring agency.

More public funded programmes and education of stakeholders on soil pollution problems and hazards may also prove to be useful. The commercial agricultural sector of the Province relies heavily on irrigation for crop production as the region in general experiences relatively harsh semi-arid conditions, especially in the western area of the Province. Farmers need to exercise caution in their irrigation scheduling and stick to set guidelines for irrigation water use to avoid salinisation. Farmers must be encouraged to construct good drainage systems and to systematic apply gypsum to ameliorate the effects of sodic soils.

9.10.3 Veld degradation

Bush encroachment
Bush encroachment is one of the most serious and conspicuous results of imbalances in savannah ecosystems. It usually follows when the natural balance that exists amongst the grass, tree and shrubby components of a healthy savannah is disturbed. Bush encroachment is seen as the single, most important restrictive factor in realising sustainable animal production in the arid savannahs of southern Africa. This includes large parts of the North West Province, as indicated in the discussions. Bush encroachment poses a serious threat to livestock farming in affected areas, primarily due to the suppressive effect of bush encroachment on the productivity of the herbaceous component of veld. This mainly involves available soil water as the primary determinant of production. Woody plants have an exceptional ability to extract moisture from the soil. The extensive root systems of fierce competitors like Mopane and Black thorn are concentrated in the top 500 mm of the soil profile - occupying the same layer as grass roots. These shallow root systems are well adapted to benefit from light rain showers, common to semi-arid regions. On top of this woody plants also often enjoy an "unfair" advantage due to their ability to continue extracting moisture out of the soil after grasses have started to wilt during severe droughts (Richter & Meyer, in press).

Bush encroachment often occurs on a farm level and is usually addressed on that level. It is also a common phenomenon in communal areas, where it is seldom addressed. A number of control measures can be implemented to control or eradicate bush. Control measures can be divided into three broad categories, viz. mechanical, chemical and biological control measures. The method of control is determined by the following factors: bush density, the effect of bush on grass production, the growth form of the dominant bush species, the size (age) of the majority of plants, the size of the area affected, the production potential of the region and the financial position of the farmer. Bush control operations should include comprehensive follow-up programmes, aimed at preventing or delaying any further encroachment (Meyer 2000d).

If conservation of the resource and maintaining the productivity of savannah areas are seen as priorities, it is imperative that the underlying causes of bush encroachment, rather than the symptoms, be addressed. Under the current conditions, the implementing of a bush control strategy could make a far more worthwhile contribution to stabilise farming operations in arid savannah areas as opposed to any other aid scheme, including a drought relief scheme. However, it is important to remember that vegetation change is a long-term process, even after such drastic manipulations as is the case with chemical clearing and mechanical thinning. Sound veld management practises, such as control of stock numbers and ample resting periods, should therefore be applied in order to generate the maximum benefit from these drastic measures, as to ensure that cleared areas are not re-invaded or deteriorate beyond restore (Richter & Meyer in press).

Alien woody invader plants
The estimated 400 000 ha of the North West Province which has been invaded by alien plants to some degree generally excludes invasions by herbaceous and succulent species (Versveld et al. 1998). The total invaded area is not known but it is undoubtedly much greater than 400 000 ha. The invaders are estimated to be using an additional 95.4 million m³ of water per year compared with the vegetation they have replaced. The impact will increase significantly in the next 5-10 years, resulting in the loss of much, or possibly even all, of the available water in certain catchment areas.

The total costs associated with alien plant invasions also are not known. Simply getting invasions in the Province under control over the next 20-years could cost as much as R232 million (Versveld et al. 1998). A number of the major invading species in the Province also produce useful products (wood, tanbark, fodder) and provide an income to a number of people. It is also unfortunately true that, in many cases, the alien species most suitable for use in woodlots or land rehabilitation are known to be invaders in South Africa or elsewhere in the world. The ideal solution would be to replace these alien species with indigenous species or non-invasive alien species. In many cases that cannot be done and the only solution is to educate the communities managing the woodlands or the rehabilitation projects to detect new invasions and to control them at an early stage.

Traditionally, landowners in South Africa have had absolute rights over their land and its natural resources, including - at least implicitly - the "right" to neglect and abuse their land. In many cases the historical approach was to convince rather than compel landowners to clear their land or to allow them to plead poverty. The net result of this has simply been to defer the costs, at the same time increasing them substantially. In essence the costs are being passed from one generation to the next, directly contrary to a basic principle of sustainability. The recognition of the fundamental importance of sustainability, together with the concept of stewardship in recent legislative efforts provides a strong argument that failing to take action against invasive weeds is neither sustainable nor efficient. It should also provide the impetus for taking the steps needed to implement the existing legislation and any new legislation that replaces it (Le Maitre 1999). The country cannot afford to disregard the opportunity and impetus established by the Working for Water Programme. The challenge is enormous and will require fundamental changes in mindset and a concerted national effort. It will also require considerable political will and courage to undertake and complete a 20-year programme in the face of the competing demands for allocation of money to basic human needs and national reconstruction. The issue is not whether invaders should be controlled or not. It is where, when and how to go about it and to make sure control programmes are being as efficient and effective as possible (Le Maitre 1999).

Deforestation
In accordance with recent thinking around the issue of fuelwood security, the need for an integrated intervention strategy has been highlighted (Van Horen 1994, Williams et al. 1996). The problem should not be narrowly defined as an environmental problem (Van Horen 1994) and will not be solved with large-scale technological interventions, although there may well be a place for technology. The problem will also not be solved with top-down interventions based on stringent control measures and fines (Shackleton 1993, Gandar & Grossman 1994) The problem can only be solved if seen in the broader context of rural development programmes, land access and tenure, poverty alleviation and the socio-cultural environment. Local conditions should be considered in all cases and large-scale generalisations of the problem should be avoided (Van Horen 1994). Affected people in target communities need to be involved at all levels of the process and outsider "delivery-package" style intervention strategies are doomed to fail (Eberhard et al. 1991, Van Horen 1994). Finally, multidisciplinary teams and decentralised approaches to dealing with the problem are crucial. A number of specific recommendations have emerged over the last few years within the broad framework of the general principles outlined above (Scholes et al. 1993, Gandar & Grossman 1994). These include the encouragement and promotion of more costly alternative fuels, such as paraffin and solar energy.

Although relatively easy to control, and holding numerous socio-cultural benefits, open fires possess a low energy conversion efficiency of between 8-20% (Bembridge 1990). A second specific recommendation therefore, proposes that fuelwood conservation should be promoted through the more efficient use of wood stoves (Bembridge 1990, Eberhard & Van Horen 1995). However, problems of market access and market knowledge are important constraints for large stove manufacturers, although these could be eased with government assistance. Bush encroachment is an important veld degradation issue in many magisterial districts of South Africa and extremes of woody biomass abundance are often separated by fence-lines dividing commercial and communal rangelands. Numerous authors have suggested that some alleviation of both the bush encroachment, as well as the deforestation problems, would occur if surplus woodland resources could be used by people in areas with a fuelwood deficit (Gandar & Grossman 1994). Although there are examples of people from rural communities using certain resources (e.g. thatch grass) from protected conservation areas as well as from neighbouring commercial farms, it is difficult to imagine how this would translate into a national programme.

The value of woodlots may be strengthened if incorporated into a broader social forestry programme. Such a national programme could include education and training to improve the management of natural woodlands, together with a range of complementary agroforestry efforts such as the encouragement of tree plantings around homesteads, community woodlots, and village nurseries for seedling production and commercial, small-grower agroforestry projects (Mammon et al. 1995). This has important implications for the existing rural extension services, within the separate departments of agriculture, forestry and health. They will all ultimately need to provide a more integrated service (Gandar 1994). An extensive training programme focussed at village level would also need to occur and this should preferably build on traditional practices of woodland management (Scholes et al. 1993, Gandar & Grossman 1994).

While different approaches could do much to improve the value of aforestation programmes, their high cost, in terms of extension and support efforts is an important constraint on their national effectiveness, although local impacts may be important (Van Horen 1994). Aforestation programmes in themselves will probably not solve the problems of the rural environment. Since fuelwood problems are inseparable from poverty and neglect, it is perhaps here that the emphasis should be placed. The large-scale housing and electrification programmes currently underway in the rural areas (Mammon et al. 1995) may go some way in alleviating poverty and are likely to have a large impact on household energy consumption patterns.

References


Aihoon, J.K. 1994. Pollution insurance for the agricultural sector: A study in the Loskop Valley. M.Sc. dissertation. University of Pretoria, Pretoria.
Archer, S., D.S. Schimel, E.A & Holland, E.A. 1995. Mechanism of shrubland expansion: land use, climate or CO2? Climatic Change 29: 91-99.
Aron, J., A.A. Eberhard & M.V. Gandar. 1989. Demand and supply of firewood in the homelands of South Africa. Second Carnegie Inquiry into Poverty and Development
    in Southern Africa. Cape Town. 21pp.
Aucamp, A.J., J.E. Danckwerts, W.R. Teague & J.J. Venter. 1983. The role of Acacia karroo in the false thornveld of the eastern Cape. Proceedings of the Grassland
     Society of southern Africa 18: 151-154.
Ayers, R.S. & D.W. Westcot. 1985. Water quality for agriculture. UN Food and Agriculture Organisation, Rome.
Baard, C.R. 1980. Bosbeheer as grondbewaringsmaatreël. In: Pienaar A. J. (ed). Proceedings of a workshop on bush encroachment and bush thickening held in
     Pretoria, 28-29 October 1980. Department of Agriculture and Fisheries, Pretoria.
     pp. K1-K9.
Ballance, A. and N. King. 1999. State of the Environment in South Africa - An Overview. Department of Environmental Affairs and Tourism, Pretoria.
Barnes, D.L., N.F.G. Rethman, B.H. Beukes, & G.D. Kotze. 1984. Veld composition in relation to grazing capacity. Journal of the Grasslands Society of Southern Africa,
     1:16-19. Barrow, C.J. 1991. Land degradation. Cambridge University Press, Cambridge. 295pp.
Basson, J.A. 1987. Energy implications of accelerated urbanisation. South African Journal of Science 83: 284-290.
Behnke R. H., I. Scoones & C. Kerven (eds). 1993. Range ecology at disequilibrium: new models of natural variability and pastoral adaptation in African savannas. Overseas
     Development Institute, London. 248 pp.
Bembridge T.J. 1988. Grassland research and extension: present and future. Journal of the Grasslands Society of Southern Africa 5: 5-7.
Bembridge T.J. 1990. Woodlots, woodfuel and energy strategies for Ciskei. South African Forestry Journal 155: 42-50.
Bloem, A.A. & E.S. Botha. Resultate verkry vanuit grondontledingsdatabasis. North West Focus 1: 13-15, NW DACE, Potchefstroom.
Bosch, J.M., D.J. Alletson, A.F.M.G. Jacot Guillarmod, J.M. King & C.A. Moore. 1986. River response to catchment conditions. CSIR, Pretoria. 131pp.
Bosch, O.J.H. & K. Kellner. 1991. The use of a degradation gradients for the ecological interpretation of condition assessments in the western grassland Biome of Southern Africa.
     Journal of Arid Environments, 21:21-29.
Brady, N.C. 1990. The nature and properties of soils. 10th edition. Macmillan, New York. 621 pp
Brown, C.J. & A.A.Gubb. 1986. Invasive alien organisms in the Namib desert, upper Karoo and the arid and semi-arid savannas of western Southern Africa. In:
     Macdonald I.A.W., F.J. Kruger, A.A. Ferrar A.A. (eds). The ecology and
    management of biological invasions in southern Africa. Oxford University Press,
     Cape Town. pp. 93-108.
Buol, S.W., F.D. Hole & R.J. McCracken. 1973. Soil genesis and classification. Iowa State University Press, Iowa.
CSIR. 199?. The environmental impacts of invading alien plants in South Africa. CSIR, Stellenbosch. 20 pp.
Danckwerts, J.E. & G.C. Stuart-Hill. 1988. The effect of severe drought and management after drought on the mortality and recovery of semi-arid grassland. Journal of
     the Grassland Society of Southern Africa, 5:218-222.
Danckwerts, J.E. & W.R. Teague (eds.). 1989. Veld management. Department of Agriculture and Water Supply, Pretoria. 196 pp.
Danckwerts, J.E. 1982. The grazing capacity of sweetveld: 2. A model to estimate grazing capacity in the False Thornveld of the Eastern Cape. Proceedings of the Grassland
     Society of Southern Africa, 5:218-222.
Dardis, G.F., H. Beckedahl, T.A.S Bowyer-Bower & P.M. Hanvey, P.M. 1988. Soil erosion forms in Southern Africa. In: Dardis, G.F. & B.P. Moon (eds), Geomorphological
     studies in southern Africa. Balkema, Rotterdam: pp. 187-213.
Dean, W.R.J., M.T. Hoffman, M.E. Meadows & S.J. Milton. 1995. Desertification in the semi-arid Karoo, South Africa: a review and assessment. Journal of Arid
     Environments, 30:247-264.
Department of Environmental Affairs and Tourism (DEAT). 1997. White paper on the conservation and sustainable use of South Africa's biological diversity. Government
     Gazette No. 18163. Government Printer, Pretoria. 136 pp.
Department of Environmental Affairs and Tourism (DEAT). 1999. National State of the Environment Report on the Internet for South Africa. www.grida.no/soesa/
Department of Water Affairs and Forestry (DWAF). Undated. Information on present woodlot activities in the North West Province. Community forestry report,
     Mafeking.
Donaldson, C.H. 1980. Omvang van bosindringing in die bosveldgebied van die Transvaalstreek. In: Pienaar A. J. (ed), Proceedings of a workshop on bush
    encroachment and bush thickening held in Pretoria, 28-29 October 1980.
     Department of Agriculture and Fisheries, Pretoria. pp. A1-A3.
Donaldson C.H. 1987. Bush encroachment menaces in the Karoo. Karoo Region Newsletter Summer :16.
Donaldson, C.H. 1969. Bush encroachment with special reference to the Blackthorn problem of the Molopo area. Department of Agricultural Technical Services.
    Pretoria.
Doran, J.W., M. Sarrantonio & M.A. Liebig. 1996. Soil health and sustainability. Advances in Agronomy 56: 1 - 54.
Du Plessis, M.A. 1995. The effects of fuelwood removal on the diversity of some cavity -using birds and mammals in South Africa. Biological Conservation 74: 77-82.
Du Toit, P.F., A.J. Aucamp & J.J. Bruwer. 1991. The national grazing strategy of the Republic of South Africa: Objectives, achievements and future challenges. Journal
     of the Grassland Society of southern Africa 8: 126-130.
Eberhard, A.A. & C.R. van Horen. 1995. Poverty and power: energy and the South African state. University of Cape Town Press,Cape Town. 227 pp.
Eberhard, A.A. 1990. Energy consumption patterns and supply problems in underdeveloped areas in South Africa. Development South Africa 7: 335-346.
Eberhard, A.A., M.L. Borchers & F.M. Archer. 1991. Energy for development: participatory research in Namaqualand. Journal of Energy R & D in Southern Africa 2(1): 12-16.
Food and Agriculture Organisation. 1977. World Map of Desertification. United Nations Conference on Desertification. FAO, Rome.
Foran, B.D., Tainton, N.M. & Booysen, P.D. 1978. The development of a method for assessing veld condition in three grassveld types in Natal. Proceedings of the
    Grassland Society of Southern Africa 13:27-33.
Forbes, R.G. & W.S.W. Trollope. 1991. Veld management in communal areas of Ciskei. Journal of the Grasslands Society of Southern Africa 8:147-152.
Fouche, H.J., J.M. de Jager, & D.P.J. Opperman. 1985. A mathematical model for assessing the influence of stocking rate on the incidence of droughts and for
     estimating the optimal stocking rates. Journal of the Grasslands Society of Southern
     Africa 2:4-6.
Fourie, J.H. 1980. Verslag in verband met bosindringing in die Vrystaatstreek. In: Pienaar A. J. (ed), Proceedings of a workshop on bush encroachment and bush
     thickening held in Pretoria, 28-29 October 1980. Department of Agriculture and
     Fisheries, Pretoria. pp. B1-B11.
Fourie, J.H., J.G. Dry & H. Hamman. 1982. Veld management in the Northern Cape. Farming in South Africa C.13: 1-7.
Fuls, E.R. 1992. Semi-arid and arid rangelands: a resource under siege due to patch- selective grazing. Journal of Arid Environments 22:191-193.v Gandar, M.V. & D. Grossman. 1994. The management of natural woodland for fuelwood and other resources: Review and policy proposals. Green Trust & Energy for
    Development Research Centre, Cape Town. 51pp.
Gandar, M.V. 1988. The history and experience of woodlot development for fuelwood production in Southern Africa. In: Eberhard A.A. & A.T. Williams (eds). Renewable
    energy resources and technology development in southern Africa. Elan Press, Cape
    Town. pp. 247-261.
Garland, G.G. 1995. Soil erosion in South Africa: a technical review. 1-52, National Department of Agriculture, Pretoria.
Garland, G., Hoffman M.T. & S.W. Todd. 1999. Chapter 6: Soil degradation. In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review of land degradation
in South Africa. DEAT, Pretoria. pp 69-107.
Goodroad, L.L. 1979. Effects of P fertilizers and lime on the As, Cr, Pb and V content of soil and plants. Journal of Environmental Quality 8: 493.
Grossman, D. & M.V. Gandar. 1989. Land transformation in South African savanna regions. South African Geographical Journal 71(1): 38-45.
Harding, G.B. & G.C. Bate. 1991. The occurrence of invasive Prosopis species in the North Western Cape, South Africa. South African Journal of Science 87: 188-192
. Hatch, G.P. 1994. The bioeconomic implications of various stocking strategies in the semi arid savanna of Natal. Unpublished PhD thesis. University of Natal, Pietermaritzburg.
Henderson L. 1995. Plant invaders of southern Africa. Agricultural Research Council. Pretoria. 177 pp.
Henning, J.A.G. & K. Kellner. 1994. Degradation of a soil (Aridosol) and vegetation in the semi-arid grasslands of South Africa. Botanical Bulletin of Academia Sinica 35:195-199.
Hoffman, M.T. 1995. Environmental history and the desertification of the Karoo, South Africa. Giornale Botanica Italano 129: 261-273.
Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. 1999. A national review of land degradation in South Africa. DEAT, Pretoria. 245 pp.
Hoffman M.T. 1999. Chapter 2: General approach. In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review of land degradation in South Africa.
     DEAT, Pretoria. pp 8-18.
Hoffman M.T. & S.W. Todd. 1999a. Chapter 3: The South African environment and land use. In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review of
     land degradation in South Africa. DEAT, Pretoria. pp 17-36.
Hoffman M.T. & S.W. Todd. 1999b. Chapter 7: Vegetation degradation In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review of land degradation
     in South Africa. DEAT, Pretoria. pp 108-161.
Hoffman, M.T. & S.W. Todd. 1999c. Chapter 8: A combined index of degradation. In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review of land
     degradation in South Africa. DEAT, Pretoria. pp 162 - 163.
Hoffman, M.T. & S.W. Todd. 1999d. Causes of degradation. Chapter 9.1: The role of climate. In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review
    of land degradation in South Africa. DEAT, Pretoria. pp 164 - 165.
Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. 1999a. A national review of land degradation in South Africa. DEAT, Pretoria. 245 pp.
Hoffman, M.T., B. Cousins, T.C. Meyer, A. Petersen & H. Hendricks. 1999b. Historical and contemporary agricultural land use and the desertification of the Karoo. In: Dean,
Irvine, L.O.F. 1943. Bosindrining in Noord-Transvaal. Farming in South Africa 18:. 725 729. Jordaan, F.P. 1999. Rangeland degradation and restoration: a LandCare approach. Part 1: the concept of rangeland degradation. In: Jordaan F.P. (editor), LandCare
Symposium, Potchefstroom, 20-21 April 1999. pp. 29-43.
Jordaan, F.P. 2000. Unpublished progress report: Grass production studies in the North West Province 2000. NW DACE, Potchefstroom. 77 pp.
Jordaan, F.P. 2001. Provincial LandCare Programme - Proposal for the North West Province. NW DACE, Potchefstroom. 114 pp.
Kellner, K. & O.J.H. Bosch. 1992. Influence of patch formation in determining the stocking rate for Southern African grasslands. Journal of Arid Environments 22: 99-
105. Kerley, G.I.H. 1996. Desertification of subtropical thicket in the eastern Cape. In: Kerley, G.I.H., S.L. Haschick, C. Fabricius & G. La Cock (eds.) Proceedings of the Second
    Valley Bushveld Symposium. Grassland Society of Southern Africa, Scottsville. pp. 5-
    7. King, A.S. 1996. Water Pollution and Management. In: Chenje, M & P. Johnson (eds.) Water in Southern Africa. Southern African Research and Documentation Center,
     Maseru. pp125-150.
Kitagishi, K. and I. Yamane (eds). 1981. Heavy metal pollution in soils of Japan. Japan Science Society Press, Tokyo, 302.
LAPC. 1995. Land reform research Phase One, provincial synthesis and overviews: North West. Working paper 24, NW2. Land and Agriculture Policy Centre.
Lal, R. & B.A. Stewart. 1990. Soil degradation: a global threat. Adv. Soil Sci. 11: xiii - xvii.
Le Maitre, D.C. 1999. Vegetation degradation. Chapter 7.5: Alien plants In: Hoffman M.T., S.W. Todd, Z. Ntshona & S.D.Turner. A national review of land degradation
    in South Africa. DEAT, Pretoria. pp 139 - 154.
Le Roux, I.G. 1996. Patterns and rate of woody vegetation cluster development in a semi-arid savanna, Natal, South Africa. Unpublished MSc thesis, University of Natal,
     Pietermaritzburg.
Limura, K., H. Ito, M. Chino, T. Morishita & H. Hirata. 1977. Behaviour of contaminant heavy metals in soil-plant systems. Proceedings Inst. Sem. SEFMIA, Tokyo. 357pp.
Macdonald I.A.W., F.J. Kruger, A.A. Ferrar A.A. (eds). 1986. The ecology and management of biological invasions in Southern Africa. Oxford University Press,
     Cape Town. 324 pp.
Macdonald, I.A.W. 1989. Man's role in changing the face of Southern Africa. In B.J. Huntley (ed.), Biotic Diversity in Southern Africa: Concepts and Conservation.
     Oxford University Press, Cape Town. pp. 51-77.
Macdonald, I.A.W. & Richardson, D.M. 1986. Alien species in terrestrial ecosystems of the fynbos biome. In: Macdonald, I.A.W., F.J. Kruger & A.A. Ferrar (eds), The
     ecology and management of biological invasions in Southern Africa. Oxford
University Press, Cape Town. pp. 77 91.
Mammon, N., G. Simmonds & C.R. van Horen. 1995. Energy sector in SADC countries - Environmental challenges and policy change. The case of South Africa. SAEEP
     Working Paper No. 1. Southern African Energy & Environment Programme, Cape
    Town. 50 pp.
Mander, J.J. & N.W. Quinn, 1995. Biomass Assessment. National Overview Report. Report No. PFL-ASS-01. Department of Mineral and Energy Affairs. Pretoria. pp. 1-85.
Mentis, M.T. 1983. Towards objective veld condition assessment. Proceedings of the Grassland Society of Southern Africa 18:77-80.
Meyer, T.C. 2000a. Determining the effect of Acacia mellifera (swarthaak/ /mongana) bush density on the herbaceous layer of veld. Progress Report 3: Project No.
     NW04/06/09 (V5411/21/01/02). Directorate Technical Support Services, NW DACE
Potchefstroom. 9 pp.
Meyer, T.C. 2000b. Determining the effect of Tarchonanthus camphoratus (vaalbos/ /camphor bush) bush density on the herbaceous layer of veld. Progress Report 3:
     Project No. NW04/06/10 (V5411/21/01/04). Directorate Technical Support Services,
     NW DACE Potchefstroom. 11 pp.
Meyer, T.C. 2000c. Determining the effect of Terminalia sericea (silver cluster leaf / sandgeelhout) bush density on the herbaceous layer of veld. Progress Report 3:
     Project No. NW04/06/11 (V5411/21/01/03). Directorate Technical Support Services,
     NW DACE Potchefstroom. 11 pp.
Meyer, T.C. 2000d. Bush problems? How to control and utilise woody problem plants. Resource Identification and Utilisation Course, 14 August - 1 September. Directorate
     Technical Support Services, NW DACE Potchefstroom. pp. 54-66.
Meyer, T.C., C.F.G. Richter & G.N. Smit . 2001. The implications of vegetation dynamics in the Kalahari Thornveld for game ranching. North West Focus 2001(2): 3-10. NW
    DACE, Potchefstroom.
Midgley, D.C. 1952. A preliminary survey of the surface water resources of the Union of South Africa. Unpublished Phd thesis. University of Natal, Pietermaritzburg.
Milton, S.J. & C. Bond. 1986. Thorn trees and the quality of life in Msinga. Social Dynamics 12: 64-76.
Milton, S.J., W.R.J. Dean, C.P. Marincowitz & G.I.H. Kerley. 1995. Effects of the 1990/1991 drought on rangeland in the Steytlerville Karoo. South African Journal of Science
91:78-84.
Moore, A. & A. Odendaal. 1987. Die ekonomiese implikasies van bosverdigting en bos beheer soos van toepassing op 'n speenkalfproduksiestelsel in die doringbosveld van
     die Molopo-gebied. Journal of the Grassland. Society of Southern Africa 4(4): 139
-142.
Mouat, D.A., C.F. Hutchinson & B.C. McClure. 1995. Editors Special Issue on Desertification in Developed Countries. Environmental Monitoring and Asssessment
37 : 1-4. Kluwer Academic Plublishers, Netherland.
Neser, S. & D.P. Annecke. 1973. Biological control of weeds in South Africa. Entomology Memoir 28. Department of Agricultural Technical Services, Pretoria.
Novellie, P. & G. Strydom. 1987. Monitoring the response of vegetation to use by large herbivores: an assessment of some techniques. South African Journal of Wildlife
     Research 17(4): 109-117.
O'Connor, T.G. 1994. Composition and population responses of an African savanna grassland to rainfall and grazing. Journal of Applied Ecology, 31:155-171.
O'Connor, T.G. 1995a. Acacia karroo invasion of grassland: environmental and biotic effects influencing seedling emergence and establishment. Oecologia 103: 214-223.
O'Connor, T.G. & P.W. Roux, 1995. Vegetation changes (1949-71) in a semi-arid, grassy dwarf shrubland in the Karoo, South Africa: influence of rainfall variability and
    grazing by sheep. Journal of Applied Ecology 32:612-626.
O'Connor, T.G. 1985. A synthesis of field experiments concerning the grass layer in the savanna regions of Southern Africa. South African National Scientific Programmes
     Report No. 114. CSIR, Pretoria. 126 pp.
O'Connor, T.G. 1995b. Transformation of a savanna grassland by drought and grazing. African Journal of Range and Forage Science 12:53-60.
O'Reagain, P.J. & M.T. Mentis. 1990. The effect of veld condition on the quality of diet selected by cattle grazing in the Natal Sour Sandveld. Journal of the Grasslands
     Society of Southern Africa 7:190-195.
Parr, J.F., B.A. Stewart, S.B. Hornick & R.P. Singh. 1990. Improving the sustainability of dryland farming systems: a global perspective. Advances in Soil Science 13: 1-8.
Pienaar, A. J. (ed) 1980. Proceedings of a workshop on bush encroachment and bush thickening held in Pretoria, 28-29 October 1980. Department of Agriculture and
     Fisheries, Pretoria. Department of Agriculture and Fisheries, Pretoria.
Purves, D. 1977. The contamination of soil and food crops by toxic elements normally found in municipal waste waters and their consequences for human health. In:
D'Itri, F. M. (ed.) Wastewater Renovation and Reuse.
Rethman, N.F.G. & G.D. Kotze. 1986. Veld condition in the south-eastern Transvaal and its effect on grazing capacity. Journal of the Grasslands Society of Southern Africa,
     3:134-140.
Richardson D.M., W.J. Bond, W.R.J. Dean, S.I. Higgins, G.F. Midgley, S.J. Milton, L.W. Powrie, M.C. Rutherford, M.J. Samways & R.E. Schulze. 1999. Invasive alien
    species and global change: A South African perspective. In: Mooney, H.A. & R.
     Hobbs (eds.) The impact of global change on invasive species. Island Press.
Richardson, D.M. & R.M. Cowling. 1992. Why is mountain fynbos invasible and which species invade? In: Van Wilgen, B.W., D.M. Richardson, F.J Kruger & H.J.
     Hensbergen (eds). Fire in South African Mountain Fynbos: Species, community and
ecosystem response in Swartboskloof. Springer-Verlag, Heidelberg: pp. 161-181.
Richardson, D.M., I.A.W. Macdonald, & G.G. Forsyth. 1989. Reductions in plant species richness under stands of alien trees and shrubs in the fynbos biome. South African
    Forestry Journal 149: 1-8.
Richardson, D.M., I.A.W. Macdonald, J.H Hoffmann, & L. Henderson. 1997. Alien plant invasions. In: Cowling R.M., D.M. Richardson & S.M. Pierce (eds). Vegetation of
     Southern Africa. Cambridge University Press, Cambridge. pp. 535-570.
Richter C.G.F. & T.C. Meyer. 2001. Perspective on bush encroachment in the North West Province. North West Focus 2001(1): 3-4. NW DACE, Potchefstroom.
Richter, C.G.F. 1991. Gras-bosinteraksie in die bosveldgebiede van die Noord-Kaap. Unpublished MSc thesis, Department Pasture Science, University of the Orange Free
     State.
Rimmer, M. 1993. Debt relief and the South African drought relief programme: an overview. Policy paper No. 34. Land and Agriculture Policy Centre.
Rooseboom, A. 1976. Reservoir sediment deposition rates. Proceedings of the Second
International Congress on Large Dams, Mexico.
Rooseboom, A., Verster, E., Zietsman, H.L. & Lotriet, H.H. 1992. The development of the new sediment yield map of Southern Africa. Water Research Commission Report No.
     297/2/92.
Roux, P.W. 1968. Principles of veld management in the Karoo and the adjacent dry sweet- grass veld. In: Hugo, W.J. (ed.), The small stock industry in South Africa.
    Government Printer, Pretoria. pp. 318-340.
Roux, P.W. 1990. The general condition of the veld in the Republic of South Africa: In: National Veld Trust, 'Save the soil', Proceedings of the Veld Trust Conference on the
     conservation status of agricultural resources in the RSA. National Veld Trust Pretoria.
Rowell, D.L. 1988. The management of irrigated saline and sodic soil. In: Wild, A. (ed.), Russell's soil conditions and plant growth (11th ed.).
     Longman Scientific &
     Technical, New York. pp 927-951.
SARCCUS. 1981. A system for classification of soil erosion in the SARRCUS region. Department of Agriculture and Fisheries. Pretoria.
Scholes, R.J., J. Berns, J. Opperman, M.V. Gandar and D. Fig. 1993. Energy and the environment in South Africa. Issues and policies towards the millenium. CSIR,
     Pretoria. 59 pp.
Schwartz, H.I. & Pullen, R.A. 1966. A guide to the estimation of sediment yield in South Africa. Civil Engineering in South Africa. December, 343-346.
Shackelton, C.M. 1993. Demography and dynamics of the dominant woody species in a communal and protected area of the eastern Transvaal Lowveld. South African
    Journal of Botany 59: 569-574.
Shackelton, S.E., J.J. Stadler, K.A Jeenes, S.R. Pollard & J.S. Gear. 1995. Adaptive strategies of the poor in arid and semi-arid lands: in search of sustainable
livelihoods - a case study of the Bushbuckridge district, Eastern Transvaal, South
    Africa. Wits Rural Facility, University of the Witwatersrand, Johannesburg.
Shainberg, I., M.E. Summer, M.P.W. Farina, M.A. Pavan & M.V. Fey. 1989. Use of gypsum on soils: a review. Advances in Soil Science 9: 1-110.
Smithen, A.A., Schulze, R.E. 1982. The spatial distribution in Southern Africa of rainfall erosivity for use in the universal soil loss equation. Water SA 8: 74-78.
Snyman, H.A. & W.L.J. van Rensburg. 1990. Short-term effect of severe drought on veld condition and water use efficiency of grassveld in the central Orange Free State.
     Journal of the Grassland Society of Southern Africa 7:249-256.
Snyman, H.A. 1994. The influence of range conditions on the hydrological characteristics in a semi-arid rangeland. Proceedings of the XVIII International Grassland Congress,
     Canada. 2(23): 1-2
Snyman, H.A. 1998. Dynamics and sustainable utilization of rangeland ecosystem in arid and semi-arid climates of Southern Africa. Journal of Arid Environments 39:645-666.
Southern African Research and Documentation Centre (SARDC), World Conservation Union (IUCN) & South African Development Community (SADC).1994. The State of the
    Environment in Southern Africa. SARDC, Harare. pp 105-132.
Tainton, N.M. 1981. Natural grazing lands and their ecology. In: Tainton, N.M. (ed.), Veld and pasture management in South Africa. Shuter & Shooter, Pietermaritzburg. pp
27-56.
Tainton, N.M. 1988. A consideration of veld condition assessment techniques for commercial livestock production in South Africa. Journal of the Grassland Society of
     Southern Africa 5:76-79.
Tapson, D.R. 1993. Biological sustainability in pastoral systems: the KwaZulu case. In: Behnke, R.H., I. Scoones & C. Kerven (eds.) Range ecology at disequilibrium.
     Overseas Development Institute, London. pp 118-135.
Teague, W.R. & G.N. Smit. 1992. Relations between woody and herbaceous components and the effects of bush-clearing in Southern African savannas. Journal of
    the Grassland Society of Southern Africa 9(2):60-71.
Todd, S.W., C. Seymour, D.F. Joubert & M.T. Hoffman. 1998. Communal rangelands and biodiversity: insights from Paulshoek, Namaqualand. In: De Bruyn T.D., Scogings P.F.
    (eds). Proceedings of a Symposium on 'Policy-making for the sustainable use of
     southern African communal rangelands.' University of Fort Hare, Alice. pp. 177-189.
Trollope, W.S.W., F.O. Hobson, J.E. Danckwerts & J.P. van Niekerk. 1989. Bosindringing en bosbestryding. In: Barnes G. R., J. E. Danckwerts, F.O. Hobson, N.M. Tainton
     W.S.W. Trollope & J.P. van Niekerk (eds). Weiding - 'n strategie vir die toekoms.
     Weidingsbestuurbeginsels en praktyke. Department of Agriculture and Water
     Affairs, Pretoria.
Turner, J.R. & N.M. Tainton. 1989. Interrelationships between veld condition, herbage mass, stocking rate and animal performance in the Tall Grassland of Natal. Journal of the Grasslands Society of Southern Africa 6:175-182.
United Nations Environmental Programme (UNEP) and International Soil Reference and Information Centre (ISRIC). 1990. World Map on Status of Human-Induced Soil
     Degradation. UNEP, Nairobi.
Van den Berg, J.A., B.R. Roberts & L.F. Vorster. 1976. The effect of seasonal grazing onthe infiltration capacity soils in a Cymbopogon-Themeda veld. Proceedings of the
    Grassland Society of Southern Africa 11:91-95.
Van Horen, C.R. 1994. Household energy and environment. Paper No. 16. Energy for Development Research Centre, UCT, Cape Town. 119 pp.
Van Oudtshoorn, F. 1999. Guide to grasses of Southern Africa. Briza Publications, Pretoria. 288 pp.
Van Rooyen, N., D. Bezuidenhout, G.K. Theron & J.D. Bothma. 1990. Monitoring of the vegetation around artificial watering points (windmills) in the Kalahari Gemsbok
    National Park. Koedoe 33:63-88.
Van Wilgen, B.W., P.M. Little, R.A. Chapman, A.H.M. Gorgens, T. Willems & C. Marais. 1997. The sustainable development of water resources: history, financial costs, and
    benefits of alien plant control programmes. South African Journal of Science 93:
404-411.
Van Wyk, B. & N. Gericke. 2000. Chapter 18: Fire-making & firewood. In: Van Wyk, B. & N. Gericke, People's plants: a guide to useful plants of Southern Africa. Briza
    Publications, Pretoria. pp 283-294.
Versveld, D.B., D.C. Le Maitre & R.A. Chapman. 1998. Alien invading plants and water resources in South Africa: a preliminary assessment. Report No. TT99/98. Water
     Research Commission, Pretoria. 286 pp.
Wand, S.J.E., G.F. Midgley & C.F. Musil. 1996. Physiological and growth responses of two African species, Acacia karroo and Themeda triandra, to combined increases in CO2
    and UV-B radiation. Physiologia Plantarum 98: 882-890.
Wells M.J., A.A. Balsinhas, H. Joffe, V.M. Engelbrecht, G. Harding & C.H. Stirton. 1986. A catalogue of problem plants in Southern Africa. Memoirs of the Botanical Survey of
    South Africa 53. 658 pp.
Wells, M.J., K.J. Duggan & L. Henderson. 1980. Woody plant invaders of the Central Transvaal. Balkema, Cape Town
Wiegand, T., S.J. Milton & C. Wissel. 1995. A simulation model for a shrub ecosystem in the semi-arid Karoo, South Africa. Ecology 76:2205-2221.
Williams, A., A.A. Eberhard & B. Dickson 1996. Synthesis Report of the Biomass Initiative. Report No. PFL-SYN-01. Department of Mineral & Energy Affairs, Pretoria. 120 pp.
Working for Water. 2001. Annual Report 2000/1. Working for Water Programme, Cape Town. 12 pp.


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