Country Pasture/Forage Resource Profiles

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Botswana - continued.

by

Jeremy Burgess

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5. THE PASTURE RESOURCE

The pasture resources of the country are almost entirely natural grasslands. Research was conducted over the period 1970-1990, on improving natural pastures by introduction of high value indigenous grasses and legumes, as well as exotic legumes, to reinforce the range. Additional research was conducted on supplementary fertilizer applications to the natural range to boost its productivity. These and other research topics and findings are discussed in more detail in Section 6.

Natural Pastures
Natural pastures cover almost the entire country. For details see the various vegetation and landscape types described in Appendix 1.

Many grasses have a very short growing season, which is an adaptation to unreliable rainfall. Heavy trampling by livestock, especially in sandy soils, tends to uproot herbaceous plants with shallow root systems, leaving large expanses of bare soil until the next rains fall. Within the natural pastures, there are abundant legumes (Papilionoideae family), and common trees such as the Acacia family are leguminous.

Limitations of the Forage Resource
The major limitation to forage production is the very low and erratic rainfall that occurs over almost the entire country. Natural pastures are subject to extreme variations in climatic conditions, on a daily basis, and also between seasons and between years. Diurnal temperatures vary by as much as 20ºC throughout the year.

In many seasons the grazing is available in a brief flush, and then animals have to cover great distances to find new grazing, until more rain falls. Often, an area is likely to be grazed only once in a year, although animals will come back and "mop-up" any standing stalks and grass tufts, once they have exhausted all the more freely available material.

Many grass species are annuals, especially in the sandveld regions, where grass tufts are physically pulled from the ground by non-selective grazers such as cattle. Then, in the subsequent and limited rainfall periods, many grasses cannot cope with competition for moisture and light by woody plant species which have established root systems. Grass yields are therefore extremely low, being in the order of only 1-2t/ha.

In addition, many grasses appear to be unpalatable, both to livestock and to wildlife. Some suggestions for lack of palatability are high concentrations of acidity, high levels of silica, are too "woody", or have unpleasant tastes due to the presence of aromatic compounds such as turpenes. Interestingly enough, it is monogastric, as opposed to ruminant livestock, such as horses and donkeys that fare better in these conditions, as long as they are given adequate supplies of drinking water.

Some shrubs are browsed, but many are covered in protective thorns or spines, or have high levels of tannins, aromatic and other unpalatable compounds in their leaves. Others are just too high to be reached by most livestock. Leaves are most commonly eaten when they have fallen from the shrubs during the winter and the early dry, summer season prior to the rains.

Another major limitation is the low soil phosphate levels, throughout the country as a whole. Phosphate is provided by commercial farmers, through the provision of mineral licks and in supplementary feeds that include urea, and which is provided most commonly in the form of chicken manure. Other limitations include eradication of the most palatable and valuable plants in natural pasture due to heavy grazing.

Rainfall patterns are such that grazing and other forage is produced during the relatively short summer rainfall period. Once the rains stop grass growth also stops; once grass reserves have been depleted, they will not be available until the next rainy season.

Areas most prone to land degradation under sandy soil conditions are those surrounding the cattle-post, and/or livestock watering point. These areas are sacrifice zones, which tend to become covered in dense scrub and can extend as far as 1-1.5 km in radius around each watering point.

There is a lack of surface water, and a dependence on deep boreholes for providing livestock drinking water. Draw-down profiles on the ground water supplies have shown that boreholes should not be located any closer than 8 km from one another, in most areas of the country. This means that the smallest feasible ranch size in such areas is 8km by 8km in extent.

The commonest limiting factors in natural pasture productivity are the short rainy season, high surface water evaporation rates, and rapid soil moisture percolation rates to beyond most herbaceous plant root zones. These all lead to interplant competition for moisture. In addition, there is competition between classes of animals for the grass resources. Livestock not only compete amongst themselves for grazing, but also with termites, rodents, and large wild herbivores.

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6. OPPORTUNITIES FOR IMPROVEMENT OF FODDER RESOURCES

Improved pastures and sown forages
Research has been conducted on improved pastures and sown forages, but these are rarely found, except in research farms and on small dairy and ostrich farms.

Crop residues
These are widely used in the common/tribal lands areas. Also in the areas of the country which are suitable for cropping, livestock are permitted onto arable lands areas once the crops have been harvested.

Pastures research summaries for 1970-1990
The Animal Production and Research Unit (APRU) summarised pastures research over a period of 20 years, from 1970 to 1990.

Factors Limiting Productivity from Natural Pastures 1972-1973 .Pasture research work has been going on since 1937 in Botswana. A more comprehensive programme was started in 1972, collecting basic data from all over the country on pasture productivity and animal live weights. Digestibility was found to be the major factor limiting liveweight gain in grazing animals followed by crude protein content particularly during the dry season. Ranches on the hardveld had the highest amount of phosphorus whilst sandveld areas had the lowest phosphorus content in herbage. Overall, calcium and phosphorus content in herbage tended to increase during the wet season but was lower during the dry season. Supplementation of growing steers with phosphorus therefore showed an increase of 0.2 kg/day in growth rate. In the 9 research ranches, grazing indices ranged from 4 kg to more than 60 kg dry matter per kg liveweight. The variation in rainfall from year to year was the major factor influencing the index. Forage selectivity by animals during grazing tended to be higher when the crude protein level was below 5 %.

Evaluation of Grass Species 1974-1977.
Grasses or grass types (see table 7) found in the sandveld were rarely found in the hardveld and vice versa. On both the hard and sandveld species fell into fairly distinct groups and greater differences were observed during the dry season.

Table 7. Better Species for the Two Veld Types
		Crude Protein Content %
Veld type season	Species	Wet season	Dry
Sandveld	Brachiaria nigropedata Digitaria milanjiana Anthephora pubescens Cymbopogon excavatus	8.43 (42) 7.86 (47) 8.17 (49) 8.05	4.96 5.26 4.27 5.08
Hardveld	Panicum maximum Urochloa trichopus Cymbopogon excavatus Brachiaria nigropedata Bothriochloa insculpta	10.42 (49) 10.71 (46) 8.46 8.52 (40) 7.46	8.76 7.83 5.58 5.23 5.34
()Mean annual values for Digestibility

Although Cymbopogon excavatus has high crude protein and digestibility values, it is unpalatable to cattle because of its bitter taste.

Bush Clearing 1974 - 1979. Removal of bush was expected to have a beneficial effect on the botanical composition of the grass layer, because of better access to sunlight and interception of rain water. An experiment involving cleared, partially cleared and un-cleared areas (see table 8) showed that cleared areas had consistently higher dry matter yield than un-cleared areas (20%); increased basal cover and yield of desirable species increased.

Table 8. Yield and botanical composition
Treatment	Dry matter Yield^1 kg/ha	Desirable species ^2 kg/ha	Other species kg/ha
Cleared	2041	464	540
Un-cleared	1725	258	382
Partially cleared	2001	734	714
^1Five year mean (1974-1979) ^21978/9 season only

The extent of the benefit from bush clearing depended upon the degree of suppression of pasture growth by trees. However, total clearing or eradication of bush may not be necessary as some of the shrubs provide good browse for livestock.

Techniques of bush control and clearing. This study was aimed at determining the biological and economic efficiency of alternative methods for control and eradication of woody plants.

1. Mechanical and Chemical methods involving physical removal of bush or trees using machinery (such as bulldozers etc.) and chemicals are expensive. Environmental considerations should be given priority where the use of chemicals to control or eradicate bush is considered, because of possible effects on animals and vegetation.

2. Fire. Prescribed burning at intervals of seven to ten years will control bush and will kill bush up to a height of two metres but additional control measures were required for coppice regrowth. There should be enough vegetation fuel to make this effective.

3. Goats. Goats effected significant reductions in bush density by browsing post-burning regrowth. One goat per hectare can effect a 70% reduction in the density of Acacia and associated woody species in four to five years.

Grazing Systems 1975 - (continuing). The use of multi-paddock grazing systems to bring about improvements in range and animal performance is being investigated as a range management system for maintaining desirable grasses and controlling encroachment of undesirable plants. Initial studies conducted in 1975-1979 showed relatively small differences between systems in animal performance, botanical composition and basal cover. Greater advantages are required from the multi-paddock systems to justify the fencing costs. A new trial was started in 1979 and it incorporates 3 grazing systems: Continuous grazing; 3 paddocks per herd (1 month graze, 2 months rest); 9 paddocks per herd (4 days graze, 32 days rest).

In an attempt to effect stock control and grazing systems and management in communal areas, it was decided that 12 grazing cells be established. Technical advice and monitoring of these trials were to be provided by APRU. Two control cells were also established. This project however did not bring about the expected outcome and the following conclusions were made: projects of this nature should operate through local institutions; identification and recognition of a community or group grazing area boundary is essential for voluntary stock control to succeed; the grazing cell concept was seen to benefit a few people while reducing grazing for others. Work on control cell (Makhi II) is still continuing.

Western Kalahari Range Ecology Studies 1975 - 1979. Construction of commercial ranches in the Ncojane area for lease to cattle owners was a major part of the first Livestock Development Project initiated in 1972. A pasture ecology project was therefore established in 1975 to follow the ecological influence of cattle in the Ncojane grazing area.

Although no firm conclusions could be drawn from a 5 year project, based on the experience of the investigations certain recommendation were made:

1. Stocking rates were more important in grazing management in this fragile environment than were grazing systems. Therefore continuous grazing at a moderate stocking rate would seem suitable.
2. Grazing pressure would be effectively controlled through better distribution of water points which should not be more than 5 km apart based on observations made on grazing patterns around water points.
3. Destocking during drought will be necessary.
4. It is essential that means to control stocking rates are developed for this area to avoid overgrazing.

Makhi II Grazing Systems Trial 1980 - continuing. The results of this trial are inconsistent between years. During the first year, pasture condition in continuous grazing was poorer than other systems but improved the following year. In the following three successive years, the 9 paddock system was better than the other two. This was followed by better conditions in the continuous grazing system. Continuous grazing may have a negative effect on pasture condition in drought years, and extended drought periods affect liveweight gain, since the system does not provide a rest period to allow vegetation regrowth.

Stocking Rate Trials 1980, continuing. Stocking rates of 2, 4, 6, 8, 10 and 12 ha/LSU were used. Preliminary results indicate that good herbaceous plants and litter increased with decreased stocking rate. As expected cattle liveweight gains also increased with a decrease in stocking rate. The study is expected to look at the economic implications of the stocking rates in the long term i.e. as regards total production over time.

The issue of stocking rate is related to the concept of carrying capacity of rangeland which is estimated for extended periods of time. When such fixed rates are used over long periods, there will be years of adequate rainfall where un-used herbage will be wasted and there will be years below average rainfall or drought where this will create temporary overstocked conditions. It is therefore better to view grazing management in relation to annual productive potential, where stocking rates are dependent on range condition thus eliminating possible under-use or over-use.

Reclamation of Degraded Rangelands 1982, continuing. The problem of rangeland degradation has been attributed mainly to lack of grazing management and control of stock numbers particularly in the communal areas; this has resulted in degradation of extensive grazing areas. Trials were established at Morale Ranch Western Kalahari (Tshane) communal area grazing, to study the processes of degradation and to develop effective and appropriate reclamation methods. And also to evaluate the effects on herbaceous plants and livestock performance. The trail at Tshane is looking at rehabilitation of an already degraded area while initial trials at Morale are monitoring the process of degradation.

Results from Tshane indicated an increase in standing crop of good grass species with increase in distance from the water point and forbs seemed to decrease with increased distance from water in the exclosures (i.e. areas closed from grazing during the growing season). Significant differences in grass cover were observed between exclosures and adjacent areas open to grazing (up to a distance of 14 km from water) at the end of the growing season. However, differences were less in areas further away from the water source (i.e. 18 km and more).

Morale Communal Grazing Simulation Trial 1984, continuing. Poor management and degradation have caused some concern about sustainability of communal grazing lands. In order to make sound recommendations on how to reclaim degraded lands and establish appropriate stocking rates and livestock management interventions, a degradation and phosphorus supplementation study was initiated at Morale ranch. Steers were grazed at stocking rates of 3, 6, and 9 ha/LSU continuously in two blocks. Steers in one block were supplemented with phosphorus. The effect of stocking rate was assessed on the standing crop of herbaceous plants and steer liveweight gain. The standing crop in 1985 was highest in the 9 ha/LSU than other stocking rates and there were more materials lost from the initial standing crop in 3 ha/LSU than in the 6 and 9 ha/LSU. The same trend was observed in 1987, 1988 and 1989. Cattle liveweight gain increased with lower stocking rates as expected. The highest liveweight gain was observed at the 9 ha/LSU with phosphorus supplementation. Phosphorus supplementation seemed to have more advantages in stocking rates higher than 9 ha/LSU in poor rainfall years.

Forage and Pasture 1976 - continuing. Opportunities for fodder and pasture production in areas with high or average rainfall are more appropriate when intensive or semi intensive livestock production systems such as dairy are to be established. Early work in Botswana prior to independence included: introduction of saltbush, cattle melon and fodder cactus; cultivation of some indigenous grasses and introduction of some tropical pasture legumes. Findings were not well documented and thus were not adopted by livestock producers.

Introduction of Fodder Species 1977, continuing. Introductions were done at Sebele, Mahalapye and Pelotshetlha. A total of 25 grass species and 77 legumes were introduced Local Grasses Cenchrus ciliaris, Panicum coloratum, Eragrostis curvula, Urochloa mosambicensis, Chloris gayana, Cynodon dactylon Local Legumes Glycine wightii, Indigofera sp., Desmodium, Dolichos lablab, Sesbania. Potentially useful legumes include Indigofera , Tephrosia, and Siratro

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7. RESEARCH AND DEVELOPMENT ORGANIZATIONS AND PERSONNEL

APRU - Botswana College of Agriculture. The Animal Production & Research Unit (APRU) is the key body for range, pastures and forage research in Botswana. It is at the Botswana College of Agriculture, Sebele, Gabarone.

The APRU has several outstations, where livestock and range research are conducted on the different range types, and with different livestock breeds and production systems. Key personnel here are:

Dr. Wanda Mphinyane

Head of the Division

Tel: 3153 068 e-mail: wmphinyane@gov.bw

Dr. Peter Wandera

Pastures Research

Tel: 3153 068 e-mail: pwandera@gov.bw

Ms. S Mangope

Pastures and Forage based at Mahalapye Research Station

Tel: 4712 711 e-mail: smangope@gov.bw

Mr. K. Kaonga

Pastures and Forage based at Mahalapye Research Station

Tel: 4712 711 e-mail: kkaonga@gov.bw

BRIMP - Ministry of Agriculture. Another key unit, is the Botswana Range Inventory and Monitoring Programme, based in the Range Ecology Division, Department of Crops and Forestry, Ministry of Agriculture, Gaborone. It draws from extensive databases, and is used to interpret Satellite Imagery and draw on Meteorological Forecasts, to interpret trends in range productivity on a seasonal basis.

Contacts for BRIMP include:

Mr. Raymond Kwerepe

Head of the Division

Tel: 3950 511 e-mail: rkwerepe@gov.bw

Mr. Victor Tlhalerwa

Principal Range Ecologist

Tel: 3950 438 e-mail: vtlhalerwa@gov.bw

Ms. Neelo Sebele

Senior Range Ecologist

Tel: 3950 756 e-mail: nsebele@gov.bw

Mr. David Stimela

BRIMP, GIS specialist

Tel: 3950 662 e-mail: dstimela@gov.bw

FAO - Botswana’s Resident Contact
The FAO contact in Gaborone, who is also based at the Botswana College of Agriculture, Sebele, is Mr. Poloko Nkepu, Tel: 3928 715.

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8. REFERENCES

Large scale studies

APRU, ~1991. Twenty Years of Animal Production and Range Research in Botswana. 1970-1990. Ministry of Agriculture.

APRU, 1978. An Integrated Programme of Beef Cattle and Range Research in Botswana, 1970-1977. Animal Production and Research Unit, Ministry of Agriculture, Gaborone.

Bhalotra Y.P. R., 1985. Drought in Botswana. Dept. Met. Services. Ministry of Works, Communications & Transport. Republic of Botswana.

BRIMP Botswana Range Inventory & Monitoring Project. Ministry of Agriculture, Gaborone, Botswana. Jointly funded by DFID, UK.

Carney J. N., Aldiss D. T., and Lock N. P., 1994. The Geology of Botswana. Bulletin 37. Geological Surveys Department, Ministry of Natural Resources and Water Affairs, Republic of Botswana. Govt. Printer, Gaborone.

Cook H. J., 1978. Botswana’s present climate and evidence for past change. Proc. Of Symposium on "Drought in Botswana". The Botswana Society, Gaborone, Botswana.

CSO, 1996. Agriculture Statistics:1996. Central Statistics Office, Gaborone. Republic of Botswana.

DHV Consulting Engineers, 1980. Countrywide Animal and Range Assessment Project. Seven Vols., with Maps. DHV, PO Box 85, 3800 AB, Amersfoort, The Netherlands.

Ecosurv, 1997. Strategic Assessment of the South Western Wildlife System of Botswana: Rehabilitation Measures. IFAD funded programs on SW Strategic Environmental and Countrywide Assessments.

Environmental Consultants, 1991. Central District Planning Study. Main Report, Vol. 1. MLGL&H/Central District Administration. Gaborone.

FAO, 1990 a. Soil Map of the Republic of Botswana. . Soil Mapping and Advisory Services Project. AG:DP/BOT/85/011. Ministry of Agriculture, Gaborone Botswana/FAO/UNDP.

FAO, 1990b. Explanatory Note on the Soil Map of the Republic of Botswana. Soil Mapping and Advisory Services Project. AG:DP/BOT/85/011, Field Document #30. Ministry of Agriculture, Gaborone Botswana/FAO/UNDP.

FAO, 1990c. Land Systems Map of the republic of Botswana. Soil Mapping and Advisory Services Project. AG:DP/BOT/85/011. Ministry of Agriculture, Gaborone Botswana/FAO/UNDP.

FAO, 1991. Contribution to the Vegetation Classification of Botswana. Soil Mapping and Advisory Services Project. AG:DP/BOT/85/011. Field Document #34. Ministry of Agriculture, Gaborone Botswana/FAO/UNDP.

FAO 1992. Map of Land Suitability for Rainfed Crop Production, plus the Explanatory Note and Legend. TCP/BOT/0053, Field Document #3.

FAO/UNDP Soils and Land Utilisation documents and maps:

Ministry of Agriculture, 1993. Monitoring and Progress Report 1991-1992/3. Ministry of Agriculture.

Moyo S., O’Keefe P., & Sill M., 1993. The Southern African Environment: Profiles of the SADC Countries. EARTHSCAN. ISBN 1353331719.

National Development Plan 8, 1997/98-2002/03. Ministry of Finance and Development Panning. Govt. Printer, Gaborone.

Roe E., 1973. Development of Livestock, Agriculture & Water Supplies before Independence, in Botswana: A short History and Policy Analysis. Cornell University and Ministry of Agriculture. Rural Development Committee, Occasional Papers #10.

Sims D., 1981. Agro-Climatological Information, Crop Requirements and Agricultural Zones for Botswana. Land Utilisation Divisions, Ministry of Agriculture, Gaborone.

Smith R. A. 1984. The Lithostratigraphy of the Karoo Supergroup in Botswana. Botswana Geological Survey Bulletin. 26. 239 pp.

Thomas, D.S.G. and P.A. Shaw 1991. The Kalahari Environment. Cambridge University Press.

UNDP/FAO, 1982. Co-ordinator, Animal Production and Range Research. BOTS. AG:DP/BOT/74/002 Internal report. Rome 1982.

Weare, P.R. and A. Yalala. 1971. Provisional Vegetation Map of Botswana (First Revision). Botswana Notes and Records 3:131-147.

WMA studies including - various National Parks and Game Reserves,

General Reading

Botswana Notes and Records, published by the Botswana Society in Gaborone. (These journals cover issues on the environment - plants and wildlife, agriculture, society, culture and cultural history, and new research findings on Botswana related topics.)

IUCN 1990. The Nature of Botswana: A Guide to Conservation and Development. IUCN, Field Operations Division, Gland, Switzerland.

Tlou T & Campbell A, 1984. History of Botswana. Macmillan, Botswana.

Recent Studies

• Management of Indigenous Vegetation for the Rehabilitation of Degraded Rangelands in the Arid Zone of Africa - Botswana, Kenya, Mali. A joint UNEP/GEF funded program , combining inter-regional programs from the three countries, working through the three Governments. The study is a progression from the Kalahari-Namib study within Botswana.
  Click here to visit the Website

Policies

Ministry of Agriculture, 1974. Draft Livestock Development Policy. National Land Management & Livestock Project. Animal Production Division, Ministry of Agriculture.

Conventions

• RAMSAR www.ramsar.org/
• Convention to Combat Desertification (CCD) < http://www.iisd.ca/linkages/vol04/enb04118e.html >
• International Biodiversity Convention: www.biodiv.org/
• CITES www.cites.org/
• Kalahari-Namib Project www.unep.org/geo2000/english/0147.htm

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9. CONTACTS

Jeremy Burgess, is a free-lance ecologist with wide experience of Botswana.
Address:
Plot 560, Lenganeng, Tlokweng - Gaborone.
Tel: 3930972, Cell: 71755933
e-mail: jburgess@info.bw

Acknowledgements
Several people gave freely of their time and resources, and without their help this profile would not have been completed. Particular thanks are due to the following: (1) the BRIMP team, for their inputs and for providing information on sources of materials, especially Victor Tlhalerwa, Principal Range Ecologist and Deputy of the Range Ecology Section, Ministry of Agriculture who also provided valuable editorial comments; also to David Stimela (GIS section) for providing the various digitized maps. (2) Mr S "Bings" Bingana, of the Botswana National Productivity Centre, for providing time and material for the socio-economic background, and also for the figures relating to BMC (Botswana Meat Commission) statistics. (3) Dr. Wanda Mphinyane, for providing backdated copies of APRU (Animal Production and Research Unit - Sebele) research summaries. (4) Finally thanks to Raymond Kwerepe, Head of the Division of Forestry, Range Ecology and Beekeeping, for his time in editing and proof reading this document.

[This profile was prepared in 2002 by the author and was edited by J.M. Suttie and S.G. Reynolds with final inputs in the period January - March 2003; livestock data in Table 6 were updated in October 2006 by S.G. Reynolds].

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APPENDIX

APPENDIX 1. Detailed Regional Vegetation Associations

The following sub-sections describe the vegetation according to region, as provided on the associated map.

Figure 14. Vegetation Regions as Taken from the FAO Soils Map
[Click to enlarge map]

Region 1. Extreme South-West

Sandveld - Extremely Arid

This region forms a narrow zone along the Nossop and the Molopo from the Gemsbok National Park via Bokspits to Khuis.

Along the Nossop bare rolling dunes are present.

Undulating to rolling dunes found further inland are covered by a vegetation mosaic varying in structure from grassland to low shrub savanna and shrub savanna with as most conspicuous species Acacia haematoxylon and the grasses Stipagrostis amabilis, S. uniplumis and Schmidtia kalahariensis. The interdunes mainly support a shrub savanna characterised by Acacia haematoxylon and Rhigozum trichotomum. The vegetation of this dune-interdune complex has an association of Acacia haematoxylon and Rhigozum trichotomum.

Region 2. South-West

Sandveld - Arid

Region 2 extends north from Region 1 and from the Molopo River via Phitshane, Jwaneng and Kang to the Tropic of Capricorn.

Due to higher precipitation rates to the north, the shrub savannas of Region 1 gradually change into savannas in Region 2.

The largest part of this sandveld region is characterised by a savanna with an Acacia mellifera, A. luederitzii, Boscia albitrunca association.

Frequent pans are observed in the central and northern section of this zone. The pans are fringed by a dense savanna and have a central area that is bare or is covered by grassland with species from genera such as Sporobolus, Panicum, and Eragrostis.

In the south-east of the region a (open) shrub savanna has been established, belonging to the same sandveld association. There the grass layer varies in coverage from 10-70%, and is dominated by Eragrostis lehmanniana, Stipagrostis uniplumis and Anthephora pubescens.

In the west of this region (open) shrub savannas are found, which form part of a Catophractes alexandri, Rhus tenuinervis association.

The most eastern land systems are characterised by open shrub savannas and open savannas. They occupy a floristic intermediate position between the Terminalia sericea, Lonchocarpus nelsii / Acacia erioloba sandveld association and the eastern hardveld associations Peltophorum africanum, Acacia tortilis, / A. karroo, Ziziphus mucronata and Peltophorum africanum, Acacia tortilis / Terminalia sericea.

Throughout the region several zones with superficial aeolian sand deposits can be recognised. These areas are mainly characterised by shrub savannas and savannas which fit in the Acacia mellifera, A. luederitzii, Boscia albitrunca association.

In the north, some isolated patches of shrub savanna and savanna occur that belong to a Terminalia sericea, Lonchocarpus nelsii / Acacia erioloba association (see Region 3).

Region 3. Mid-West

Sandveld - Arid to Semi-arid

This region is enclosed by the Tropic of Capricorn in the south, the Okwa/Quoxo valley system in the north and east and the Namibian border in the west. A small zone extends southwards along the international boundary to the Nossop.

In this region the vegetation structure ranges from low shrub savannas to dense savannas. The vegetation of the whole area is part of a Terminalia sericea, Lonchocarpus nelsii, Acacia erioloba and A. leuderitzii association. Predominant grass species include Anthephora pubescens, Eragrostis lehmanniana, Schmidtia kalahariensis, S. pappophoroides, Stipagrostis uniplumis, Aristida congesta, Pogonarthria squarrosa.

Region 4. Okwa/Quoxo valley system

Sandveld - Fossil Valley Systems

This fossil river system, located in the centre of the country, is mainly covered by a shrub savanna and savanna mosaic, which floristically belongs to the Terminalia sericea, Lonchocarpus nelsii / Acacia erioloba association. The grass layer is dominated by Aristida congests, Eragrostis lehmanniana, Pogonarthria squarrosa, Schmidtia pappophoroides, Stipagrostis uniplumis.

Region 5. Mid-East

Sandveld - Shallow with Hardveld Interface

Region 5 is confined by the Quoxo in the west and the hardveld in the east and is roughly situated between Letlhakane in the north and Dibete in the south. This region mainly consists of sandveld vegetation types. Towards the boundary between the sandveld and the eastern hardveld transitional vegetation types and one hardveld association occurs.

The principal vegetation structure in the sandveld is savanna. The savannas belong to the Terminalia sericea, Lonchocarpus nelsii / Acacia erioloba association.

Hardveld land systems are located at the eastern fringe of the sandveld. They support a transitional vegetation with elements of the sandveld association and species of the hardveld associations Peltophorum africanum, Acacia tortilis / Terminalia sericea, and Combretum apiculatum, Acacia nigrescens, and A. tortilis. A system of superficial aeolian sand deposits, mainly surrounded by hardveld consists of the hardveld association Colophospermum mopane, Acacia nigrescens / Combretum apiculatum, Acacia tortilis (see Region 6). The grass layer is dominated by Aristida congesta, Digitaria milanjiana, Eragrostis pallens, Stipagrostis uniplumis., with 10-30% basal cover.

One land system is covered by a transition community with elements of the sandveld association and the hardveld association Colophospermum mopane, Acacia nigrescens / Combretum imberbe, forming an association of Colophospermum mopane, Terminalia sericea / Combretum imberbe. Part of this land system is also characterised in places by a vegetation transition between sandveld and hardveld resulting in a Colophospermum mopane, Terminalia sericea / Sclerocarya caffra association. The grass layer here is dominated by Anthephora pubescens, Digitaria sp., Eragrostis pallens, and Stipagrostis uniplumis, with 10-70% cover.

The mopane-line roughly follows the boundary between sandveld and hardveld. It crosses land and divides it in a southern part with typical sandveld vegetation and a northern zone with an association of Colophospermum mopane and Terminalia prunioides. The grass layer is dominated by Cenchrus ciliaris, Digitaria milanjiana, Eragrostis sp.

Region 6. Eastern Hardveld

Hardveld - with Minor Sandveld Intrusions

The eastern hardveld extends from approximately 26º south to 20º south and is confined by the sandveld in the west and the international boundary in the east.

The hardveld has a vegetation cover ranging from shrub savanna over savanna to tree savanna. In comparison with the sandveld, the hardveld is typified by a denser and taller vegetation. This difference can be contributed to the heavier texture and higher nutrient content of the hardveld soils.

From south to north shrub savannas decrease and tree savannas increase. This tendency is probably due to the increase of the precipitation towards the north.

In the hardveld two provisional alliances consisting of two and three associations respectively and three independent association have been distinguished.

From 26º south to 23.5º south a Peltophorum africanum, Acacia tortilis alliance is found, consisting of two associations:

• The southern association is characterised by structures varying from shrub savanna and savanna to tree savanna and the species Peltophorum africanum, Acacia tortilis / Acacia karroo, Ziziphus mucronata.
• The northern association is typified by shrub savannas and savannas, marked by Peltophorum africanum, Acacia tortilis / Terminalia sericea.

Between 23º south and 20º south a Colophospermum mopane, Acacia nigrescens alliance is present, which consists of four associations:

• The southern one is predominated by savannas, which form a Colophospermum mopane, Acacia nigrescens / Combretum apiculatum, A. tortilis association.
• The eastern central section of this zone is covered by relatively tall (12-16m height), close-canopy woodlands that are dominated by Acacia nigrescens and Sclerocarya birrea, with a secondary woodland storey of (4-10m height) dominated by Combretum apiculatum. This vegetation association coincides with shallow-basalt-derived soils that overlie a granitic parent geology.
• The eastern land systems are covered by an association of open tree savannas typified by Colophospermum mopane, Acacia nigrescens / Burkea africana. B.africana is usually associated with sandy soils, but occurs here, in pockets of deep sand, which are generally old drainage lines and erosion surfaces that have infilled with sand.
• In the north-western area of the hardveld and in some patches of the north- I east savannas and tree savannas are found, which belong to a Colophospermum mopane, Acacia nigrescens / Combretum imberbe association. The grass layer is dominated by Aristida congests, Eragrostis lehmanniana, E. rigidior, E. superba, with 10-70% basal cover.

The hardveld land systems situated between 23.5º and 23º south, predominantly consist of savannas, which form an independent association of Combretum apiculatum, Acacia nigrescens, A. tortilis.

There is an intermediate land system between the Peltophorum africanum, Acacia tortilis / Terminalia sericea association and the Combretum apiculatum, Acacia nigrescens, A. tortilis association and can be classified as an Acacia erubescens, A. tortilis, Boscia albitrunca association. The grass layer is dominated by Bothriochloa insculpta, Chloris virgata , Perotis patens, and Setaria sp., with 30-70% basal cover.

There are two sandveld land systems that are included in this region, and which are typified by a range of vegetation structures from open shrub savannas to open tree savannas. One system is classified as an Acacia tortilis, Combretum erythrophyllum, Lonchocarpus capassa association, while the other is classified as an Acacia erubescens, A. tortilis, Boscia albitrunca association.

The mopane-line separates the Combretum apiculatum, Acacia nigrescens, A. tortilis association from the more northern located Colophospermum mopane, Acacia nigrescens alliance. The grass layer is dominated by Aristida congest a , Cenchrus ciliaris, Chloris virgata, and Eragrostis lehmanniana, with 10-30% basal cover.

Region 7. Letiahau, Ghanzi, Hainaveld area

Northern Sandveld

Region 7 extends from the Okwa to the Boteti and is confined by the almost flat fossil lagoon in the east and the international border in the west.

Both on the eastern and western side of the Ghanzi ridge, the sandveld is mainly characterised by shrub savannas and savannas belonging to the Terminalia sericea, Lonchocarpus nelsii / Acacia erioloba association. Typical grass species include Anthephora pubescens, Aristida meridionalis, Cenchrus ciliaris, Digitaria eriantha, Enneapogon cenchroides, Eragrostis lehmanniana, Pogonarthria squarrosa, Rhynchelytrum repens, Schmidtia bulbosa, Stipagrostis uniplumis, Tragus berteronianus and Urochloa mossambicensis.

Part of the land system consists of parabolic dunes and fossil rivers. The parabolic dunes carry a continuity of Terminalia sericea, Lonchocarpus nelsii, Acacia luederitzii. The fossil rivers provide carbonate rich soils and favour the occurrence of the species Catophractes alexandri and Acacia tortilis. The vegetation is dominated by Terminalia sericea, Lonchocarpus nelsii, Acacia tortilis, Catophractes alexandri association.

The Ghanzi ridge has a complex vegetation, which ranges in structure from shrub savanna and open savanna to tree savanna. A compilation of the floristic characteristics leads to an association of Acacia mellifera, A. erioloba, Terminalia prunioides, Catophractes alexandri.

Region 8. North-West

Northern Sandveld - Western Delta Fringes

This region is situated in the north-western corner of the country and extends from Lake Ngami in the south to the Caprivi Strip in the north. Its eastern boundary is formed by the Okavango Delta, while the Namibian border forms its western limit.

The area is predominated by savannas and dense savannas, although shrub savannas and tree savannas occur as well.

In spite of the different parent materials (sandveld, alluvium and limited hardveld) the vegetation of the region developed in a rather uniform way, according to associations on massive fossil sand dunes.

On the sandy soils of the dune system and the fossil alluvium the Terminalia sericea, Lonchocarpus nelsii / Acacia erioloba association is found. Associated grass species include Anthephora pubescens, Aristida meridionalis, Eragrostis sp., and Stipagrostis uniplumis.

There is an apparent division in the vegetation on the western side of the Delta with the boundary occurring along a parallel with the Tsodilo Hills (Tlhalerwa, Pers. Comm.). The northern part is predominated by the Miombo tree savanna on very deep sands, similar to the one found east of the delta pan handle; e.g. the Pterocarpus angolensis association found along the Tamacha to Tsodilo road. The vegetation described here is found south of the Miombo tree savanna. Ihe grass species Anthephora pubescens is generally found south of the Nokaneng to Xangwa road, which is generally the boundary between the Miombo tree savanna and the vegetation described here.

Lake Ngami only contains water during wet years. The lake shore and the lake bed (in dry years) consist of a forbland of Sesbania sp., and Asclepias fruticosa. The forbland merges into a zone of shrub and tree savanna on the flats, belonging to the Terminalia sericea, Lonchocarpus nelsii I Acacia erioloba association. Associated grass species include Aristida congesta, Cenchrus ciliaris, Cynodon dactylon, and Panicum repens.

The mopane-line enters the region just north of Lake Ngami and runs around the Okavango Delta to the north in the direction of Nokaneng. From Nokaneng up to Shakawe Colophospermum mopane only occurs in a 5 - 15 km wide zone along the Okavango Delta and the Panhandle.

East of the mopane-line a mosaic of savanna and woodland is recognised typified a by Combretum imberbe, Acacia erioloba, Colophospermum mopane association. This association is found on the fossil delta floodplain towards the mainland edges. Associated grass species include Aristida congesta, Cenchrus ciliaris, Cynodon dactylon, Echinochloa pyramidalis and Setaria sphacelata.

Region 9. Makgadikgadi system, Nxai Pan area

Makgadikgadi Pan System

This region comprises the lacustrine land systems belonging to the Makgadikgadi Pans and their surroundings.

The Pans are dry and without any vegetation during the greatest part of the year. They are only submerged a few months each year. The shallow coastal zones support a swamp vegetation characterised by Scirpus maritimus. Grasslands typified by halophytic species such as Odyssea paucinervis and Sporobolus spicatus surround the pans. The catena is divided, with the grass Cenchrus ciliaris as a major dominant in the upper slopes of the catena, while Odyssea paucinervis and Sporobolus spicatus predominate in the lower parts of the catena.

South of the Makgadikgadi Pans land system the mopane-line divides this land system in a northern mopane free area and a southern mopane dominated zone.

The northern part is characterised by grasslands and occasionally open savannas. Clumps of Hyphaene petersiana and Catophractes alexandri are observed on calcareous substrates. Chrysopogon montanus is a dominant grass species part of this association (Tlhalerwa, Pers. Comm.). The grasslands with species Odyssea paucinervis, Sporobolus spicatus, Cymbopogon sp., Eragrostis rigidior and Enneapogon desvauxii belong to the Odyssea paucinervis association.

The southern area is covered by grasslands and savannas belonging to the Colophospermum mopane, Terminalia prunioides association, which is also found in the bordering Region 5.

East and north of the grasslands that surround the Makgadikgadi Pan system a variety of vegetation structures from shrub savanna to tree savanna are recognised. The vegetation belongs to a Colophospermum mopane, Terminalia sericea alliance.

The eastern part of the land system is typified by shrub savannas belonging to a Colophospermum mopane, Terminalia sericea Sclerocarya caffra association. This land system consists of five different zones:

• The grasslands around the Makgadikgadi Pans were mentioned above.

• South of 20º south Hyphaene petersiana and Adansonia digitata are frequently observed. In this area an association can be established, typified by Colophospermum mopane, Terminalia sericea I Hyphaene petersiana, Adansonia digitata, belonging to the Colophospermum mopane, Terminalia sericea alliance.

• In the north a range of vegetation structures from shrub savannas, savannas to tree savannas is found, belonging to a Colophospermum mopane, Terminalia sericea I Combretum imberbe association.

• Nxai Pan is covered by an open tree savanna. The landscape is characterised by grasslands of Cenchrus ciliaris, Panicum repens, Odyssea paucinervis and Cymbopogon sp. and clumps of Acacia tortilis trees.

• East and west of the Boteti River a zone is found, which is covered by shrub savannas and savannas belonging to the Terminalia sericea, Lonchocarpus nelsii Acacia erioloba sandveld association.

• The floodplains and courses of the Boteti River are typified by a swamp vegetation and sedge- and grasslands of Phragmites australis, Scirpus inclinatus, Cyperus articularis and Typha capensis. The banks and terraces are covered by shrub savannas and savannas with Acacia tortilis, A. erioloba, A. mellifera and Terminalia prunioides. An association of Acacia tortilis, Phragmites australis, A. erioloba, Terminalia prunioides could be established for this land system.

Region 10. Mid-North

Northern Sandveld Bordering on Eastern Hardveld and the Delta in the West

This region, mainly sandveld, extends from Maun to Basotho and is located north of the Makgadikgadi Pans system and south of the Chobe area.

Savannas with a Colophospermum mopane, Terminalia sericea alliance are predominantly found in the east and the centre of the region. The communities of the land systems Ar3 and Sa17 south are classified as a Colophospermum mopane, Terminalia sericea, Dicrostachys cinerea association. The vegetation is part of a Colophospermum mopane, Terminalia sericea I Lonchocarpus nelsii association.

There is a 10 km wide fringe along the Thamalakane River with woodland of the same alliance which can be classified as a Colophospermum mopane, Terminalia sericea I Dicrostachys cinerea association.

A variety of structure types from shrub savanna and savanna to tree savanna and forest forming a Colophospermum mopane, Combretum sp., association. Grass species found here include Aristida sp., Cenchrus ciliaris, Chrysopogon montanus, Digitaria milanjiana, Eragrostis rigidior, Schmidtia bulbosa, and Urochloa trichopus.

The north-western area is covered by shrub savannas and savannas belonging to a Terminalia sericea, Lonchocarpus nelsii I Combretum sp. association.

In the north-eastern part of the region shrub savannas and savannas are found. Miombo species as Pterocarpus angolensis and Ricinodendron rautanenii are invading from the north forming a Terminalia sericea, Lonchocarpus nelsii I Pterocarpus angolensis association.

Region 11. North-East

Sand Forest Region

This region occupies the north-eastern part of Botswana. It comprises the Chobe area, Kasane and the Mpandamatenga plains.

The Chobe area is basically characterised by sand plains supporting savannas, tree savannas and woodland with a floristic association of Pterocarpus angolensis, Baikiaea plurijuga in which Colophospermum mopane frequently occurs.

This vegetation forms a transition between the northern miombo woodland, found in Zambia and Zimbabwe, and the southern Kalahari savannas. Other typical miombo species occurring in the Chobe area are Ricinodendron rautanenii, Croton gratissimus, Guibourtia coleosperma, Burkea africana, Brachystegia boehmii, Julbernardia globiflora and Isoberlinia sp.

The Mpandamatenga plains are characterised by grasslands, shrub savannas and open savannas fringed by open savannas and tree savannas. The savannas are part of a Colophospermum mopane, Acacia nilotica, Combretum sp. association. Grass species found here include Andropogon sp., Cenchrus ciliaris, Chloris gayana, Cymbopogon sp., Digitaria eriantha, Eragrostis sp., Hyparrhenia filipendula, Panicum maximum, Perotis patens, Setaria sphacelata, and Sporobolus sp.,

The vegetation varies in places from (open) savanna and tree savanna to woodland, and can be classified as part of the Colophospermum mopane, Terminalia sericea Combretum imberbe association.

A gently undulating basalt plain in the far east supports an open savanna and savanna vegetation, which forms part of the Colophospermum mopane, Acacia nigrescens I Combretum imberbe hardveld association.

Along the Chobe River grasslands are found on the floodplains. Savannas and forest, in literature often described as riverine woodland, are recognised on the banks. The riverine woodlands have a Combretum imberbe, Acacia erioloba, Colophospermum mopane association with associated species Lonchocarpus capassa and Croton megalobotrys. Grass species found here include Andropogon sp., Aristida sp., Cymbopogon sp., Dichanthium annulatum, Digitaria eriantha, Eragrostis sp., Hyparrhenia filipendula, Panicum maximum, Perotis patens, Schmidtia bulbosa, Setaria sphacelata, and Sporobolus sp..

The Chobe Enclave is a marshy area with floodplains and islands. The islands are predominantly covered by savannas with an association of Hyphaene petersiana, Lonchocarpus capassa, Phoenix reclinata, while the floodplains carry grasslands.

Region 12. Mababe, Kwando-Linyanti, Okavango

Alluvial Flood Plains

Region 12 is located in the north of the country and includes the Mababe Depression in the east, fossil alluvium in the centre and longitudinal dune systems in the west. The region is bordered by the Caprivi Strip in the north and by the Okavango Delta in the south.

The Mababe Depression can be divided in a clay rich central depression, a sandy terrace in the east and a beach ridge in the west.

The centre is covered by a shrub savanna of Acacia tortilis, surrounded by shrubland and woodland with associated species Colophospermum mopane, Acacia erioloba , A. nigrescens, Lonchocarpus capassa, resulting in a Colophospermum mopane, Acacia tortilis association. Grass species include Grass species found here include Aristida meridionalis, Digitaria eriantha, Eragrostis sp., Schmidtia pappophoroides and Stipagrostis uniplumis.

On the terrace a dense shrub savanna with an association of Colophospermum mopane, Combretum sp. is recognised. The beach ridge is covered by a sandveld savanna belonging to the Terminalia sericea, Lonchocarpus nelsii, Acacia erioloba association.

The Savute Marsh, which only floods in extremely wet years, is covered by grassland dominated by Cynodon dactylon, surrounded by Acacia erioloba and A. nigrescens, forming an Acacia tortilis, Cynodon dactylon, Cenchrus ciliaris, Combretum imberbe association.

The fossil lagoon sands around the Mababe Depression have a typical sandveld vegetation with savannas consisting of the Terminalia sericea, Lonchocarpus nelsii Acacia erioloba association.

The fossil alluvium from the Okavango Delta and the fluvially eroded longitudinal dune systems are covered by shrub savannas, (dense) savannas and tree savannas, which are part of the Colophospermum mopane, Terminalia sericea Lonchocarpus nelsii association.

On the longitudinal dunes along the Caprivi Strip (dense) savannas with Terminalia sericea and Baphia massaiensis are well developed.

The interdunes are typified by an open savanna with as most characteristic species Peltophorum africanum and Combretum hereroense. The vegetation of the entire dunefield can be classified as an association of Terminalia sericea, Baphia massaiensis, Peltophorum africanum, Combretum hereroense.

The floodplains of the Kwando and Linyanti Rivers and of the Savute Channel are covered by grasslands. The river banks and terraces support savannas and forests, which can be classified as the riverine woodland association of Combretum imberbe, Acacia erioloba, Colophospermum mopane.

Region 13. Okavango Delta

Okavango Delta and Associated Floodplains

Region 13 comprises the Okavango River (the Panhandle zone) and the Okavango Delta.

Five land systems have been observed in this region: permanent swamp, delta- floodplain, river floodplain and two types of fossil alluvium respectively.

• The permanent swamp and the delta-floodplain are characterised by the land elements swamp, floodplains and islands. The swamp is typified by emergent, floating and submerged vegetation communities, consisting of hydrophytic grasses, sedges and aquatic species. The floodplains consist of grassland.

The swamp and floodplain communities can be grouped in an alliance of Cyperus papyrus, Phragmites australis, Imperata cylindrica. This alliance comprises three associations: a permanent swamp association of Cyperus papyrus and Miscanthus junceus, a delta-floodplain (seasonal swamp) association of Phragmites australis, Schoenoplectus corymbosus, Cyperus articularis and a floodplain association of Imperata cylindrica, Setaria sphacelata, Hyparrhenia rufa.

• On the islands a variety of structural vegetation types is found: grassland, (dense) savanna, tree savanna, woodland and forest. The central part of the islands may consist of halophytic grasslands or savannas, while the fringes support a much denser riverine vegetation.

The island vegetation can be classified in a Hyphaene petersiana, Garcinia livingstonei alliance, which consists of two associations.

• In the perennial swamp a Hyphaene petersiana, Garcinia livingstonei Phoenix reclinata, Ficus verruculosa association is found.
• The islands of the delta-floodplain belong to a Hyphaene petersiana, Garcinia livingstonei Lonchocarpus capassa, Acacia nigrescens association.
• Peninsulas and large islands as the Mopane Tongue and Chief's Island are mainly covered by a mosaic of savanna and woodland, which form part of a Colophospermum mopane, Terminalia sericea Lonchocarpus nelsii association.
• On both sides of the Panhandle a zone of fossil river floodplain is recognised. The vegetation structure is varying from savanna to tree savanna, supporting a Terminalia sericea, Lonchocarpus nelsii Baphia massaiensis association.
• Along the Okavango River, floodplains and scattered islands occur. The floodplains are covered with grassland belonging to the Imperata cylindrica, Setaria sphacelata, Hyparrhenia rufa association. The islands resemble the permanent swamp islands and support the same Hyphaene petersiana, Garcinia livingstonei I Phoenix reclinata, Ficus verruculosa association.
• Along the borders of the Okavango Delta patches of riverine woodland occur, characterised by the species Ficus sycomorus, Garcinia livingstonei, Diospyros mespiliformis, Acacia erioloba, Combretum imberbe and Colophospermum mopane. Grass species found here include, Aristida stipoides Eragrostis sp., Hyparrhenia rufa, Hyperthelia dissoluta, Imperata cylindrica, and Setaria sphacelata.

APPENDIX 2.

A brief palaeo-history of the land formation processes that have created the current land-systems
Thomas & Shaw (1991) have written a fascinating book on the pre-historic land formations of Botswana, with hypotheses on how the present land-forms have been derived from these.

Much of the Makgadikgadi pans area was a lake which was fed by several rivers including the Okavango, Kwando, Chobe and possibly even the Zambezi. The lake then drained out through what are now the Shashe and Motloutse river systems, that run eastwards into the Limpopo River. The major rivers brought in massive quantities of sand from upstream, which began to fill the lake bed.

The western Kalahari Region was also once a massive, shallow inland lake, that also drained into the Limpopo River through the Serorome Valley, on the tropic of Capricorn.

With a gradual change to a much drier climate (but with several periods of heavy rainfall interrupting this period), and some major geological upheavals to the south east of the Makgadikgadi Pans, the ancient lakes gradually dried up. Additionally, several major geological upheavals resulted in all but the Okavango river turning to the North-east, to join the present Zambezi River, which is their current alignment.

After going through a process of looking rather like the Okavango Delta does today, the Pans cover an area of open white sands with saline rich waters lying below the surface. It is this sub-surface salinity that is a major determinant in the current landscape and vegetation associations that characterise the Pans.

To the west, climate change resulted in fine sands being blown in from the west, and deposited in an almost flat layer of sand over several thousands of square kilometres. This layer was then reshaped by subsequent wet and dry cycles to form the flat to rolling countryside, which is broken in places by fossil drainage lines, ridges and ancient sand dunes. The sand dunes form in two ways, as linear dunes, and as elliptical dunes, around existing major pan systems, in the South-west of the country.

The eastern side of the country is generally more broken with hills and drainage lines due to surface uplifting. Many of the drainage lines, however, are dry for much of the year, and rivers and streams only run during the rainy season.

Contribution of the land formation processes to the existing landscape
The Western portion of the country, is covered by a great depth of sand over a large part, and which is up to 200m deep in places. In these areas, ground water is generally found at great depths, from 40m to below 200m. The ground water is also very often too salty for people, and often even for livestock, to drink safely and survive in the long term.

The inherent salinity of the ground water associated with rising and falling ground water levels through long-term wet and dry cycles, over a very long period, has resulted in the formation of sub-surface lenses. These lenses, have formed as water levels rise and fall, and minerals have been deposited and then hardened into solid rock. The lenses are made primarily of calcrete (a form of limestone) and silcrete (a form of limestone which has hardened by silica from the sand deposits). These lenses then form a barrier to rainfall percolating down through the sand, which leads to the creation of scattered pans and outcrops of exposed calcrete, mainly around the pans and along the rim of the fossil drainage lines.

The combined landscape formation factors have resulted in the development of vegetation systems that can survive on very little rainfall, and livestock production strategies have historically been mostly nomadic, to capitalise on localised rainfall and vegetation growth particularly in drainage lines, and around pans.

In the east and northern parts of the country, people have been more settled, as rainfall is generally higher, and surface water is available in places. In other places water can be found by digging shallow wells in the sandy river beds, of the major drainage lines, or by drilling shallow boreholes into the banks of these rivers.

More recently, deep boreholes have been drilled in the western and southern portions of the country and these have enabled "cattle posts" to develop.

As more and more boreholes develop, however, there has been increased pressure on the range resources. Ground water resources, are also becoming depleted in places, as extraction rates exceed replenishment rates, and salinity levels increase as removal of fresh water layers result in an increase in the levels of dissolved salts.

APPENDIX 3. THE DEVELOPMENT OF THE LIVESTOCK SECTOR IN BOTSWANA, 1895 to 1965

[From Roe (1973)]