Mustafa M. Baasher
1. Need to Qualify Some Words
The word 'desert' has been used to describe certain terrain of land that receives little or no precipitation, and where temperature extremes limit life from multiplication and survival.
The word "dryland" or "Aridland" are sometimes used to describe geographic zones of the world that receive insufficient amounts of precipitation coupled with high temperatures that add to their aridity.
However, ecologists, geobotanists, and world climatologists as well as agronomists have hardly reached any satisfactory agreement in their attempts to define these two words, namely what should come under "desert" and what should be defined as "arid" or "extremely arid".
Sankary (1967), reviewing world vegetation mapping work, gave the vivid example for such disagreement and confusion where, Emberger (1965) recognized desert in areas being placed by Meiges under "extremely arid". He pursued this rather confusing definitions by mentioning that, Emberger placed "extremely arid" in areas where other workers have placed it under "true desert". World plant geographers resorted to the use of the words "true", "proper", and "real" desert.
In Harrison and Jackson's (1955) vegetation map, desert was defined as area receiving an average annual rainfall of less than 75mm. Such areas, included under desert, support wildlife such as the Addax, the Oryx as well as Ghazzelles and Ostriches. This is more or less contrary to the definition of the word "desert".
2. Need to Up-date and Breakdown the Vegetation Map
Harrison and Jackson's version of the vegetation map (Vegetation Map, 1955), and the different vegetation zones descried by them were verified by Lebon (1965) using Koppen's equation. According to Lebon, Harrison and Jackson's vegetation map gave a good fit.
Recent work by Emberger has improved Koppen's work and indicated that such formula needs to be modified by using phytosociological parameters and analytical techniques to rectify certain deficiencies.
A glance at Harrison and Jackson's classification reveals that the semi-desert zone breakdown is rather confusing.
The word "scrub" alone or "desert scrub" are maintained under semi-desert and then semi-desert is further assigned to subzones within the semi-desert.
The montane zone is no more than a solid red patch shown in isolated places without any further breakdown. We know that zonations of vegetation do exist in the Red Sea Hills, Boma plateaux, Jebel Marra and the Imatong which should justify a further breakdown. This will help to work out a reliable land capability and land classification map.
3. Gap in Knowledge to be Bridged
In our attempt to delineate what constitutes the dryland of Sudan and what treatments they should receive; and in order to tap their potential; i.e., effective manipulation of the existing potential, one should expect that our present knowledge should develop to or reach a reasonable level and be supported by continuous monitoring, compilation of records, keeping of survey records, and carrying on with local research works or adopting applicable research works being conducted under similar conditions.
The need for and the availability of authenticated and reasonably well verified basic data should not be underestimated or dismissed as unattainable or not necessary. Nevertheless, there should be a general acceptance that there are some gaps in our present knowledge (if not many gaps) of Sudan's dryland potential and the physical environment that makes up such dryland.
Leaving things as they are will not help much, but will complicate the problem as time goes. However, areas where information is lacking or need completion are:-
3.1 Assessment and location of underground water - quantity and quality.
3.2 Assessment of surface run-off and guaging of some of the big wadies in the zone e.g. El Hawad, El Atshan, El Sadah, El Mukhazir, El Milk, Howe, Howar, Mugadam, Abu Ghalb Abu Habil, Khor Arab, Wadi Amur and to some extent Barka, Gash and Arab'at.
3.3. Collectionof sufficient meteorological data, e.g. rainfall coverage, temperature (air and soil), humidity, wind speed, solar radiation (computation of evapo-transpiration).
3.4 Soil survey and soil maps to the level of soil groups or soil series and type - their physical and chemical constituents and deficiencies in macro or micro plant nutrients.
3.5 Knowledge of the plant cover to the level of plant community - over and under story and the floristic composition and chemical constituents.
3.6 A good or fair survey of animal and plant diseases and pests of the area.
3.7 A fair knowledge of the fauna and the important wildlife species and their distribution.
4. Finding a Wayout to Make-up for Such Imperfect Knowledge
4.1 Revising Harrison and Jackson's Vegetation map and scrutinizing zonation boundaries and breakdown to sub-zones. Work out further breakdown and improve over present scale. Present scale is 1:8 million.
4.2 Up-date the flora of the Sudan. Review Herbarium collection for better display and observing ecotype and genetical or morphological differences and spread within species.
4.3 Establish some natural history reserves in the order of one to few hectares each in representative areas in the major vegetation zones and subzones. If funds permit carry on to plant association and plant community levels.
4.4 Insist on working a land capability map for the semi-desert zone or the driest part of the dry zone. This will help to single out large areas for the management and conservation of the grazing land. A country-wide land capability and land use map needs much effort and the release of large sum of money. A piecemeal approach might be the answer and should make a short-cut instead of waiting for a country-wide treatment.
4.5 Suggest for working in the dryland areas namely Northern Kordofan and the part of Eastern Sudan that lies in the semi-desert zone (not Butana alone) to adopt and maintain everlasting policy and strategy of team-work approach. Hence, the creation of a "special dryland husbandry task force" to be formed of the different specialities knowledgeable in dryland husbandry work.
Personnel selected should be technically equipped and qualified to deal with problems of dryland management and development.
4.6 Priorities and allocation of funds should be critically and carefully decided upon with the essential aim of bridging gaps in knowledge and working towards setting out targets and fulfilling developmental scores and optimizing resources use and perpetuation.
4.7 Adoption of simple proven techniques and the introduction of appropriate technology which are sometimes frowned upon by both the recipients and the decision makers as being obsolete or a step to the back. Appropriate technology and simple techniques can effectively be applied to the development of the micro-environments. Micro-environment approach should ensure a better use of the resources at hand. It will help conservation of resources at hand, and to prevent excessive pressure on land resources by checking over-crowding of both man and beast.
4.8 Sudan has leaned too much on raising crops under irrigation where the largest part of the country's inputs in agriculture has gone to irrigated farming. Use and development of natural resources should not be limited to the tapping of irrigation potential alone. Dryland husbandry and specially rain-fed crop raising and range- land management should be activated and their problems tackled.
Rangeland and rain-fed subsistence farming receive less attention. The areas they occupy in the country are the largest and the most vulnerable. Such areas suffer from human and animal pressure and over-use. The need to rectify such abuse and negligence is more than eminent and it is high time to strike a balance and change emphasis in priorities.
4.9 Emphasis should be placed on working out project models to answer some chronic problems pertaining to:
Management of resource use around permanent water points.
Adopting reliable inventory methods for rural water development aiming to equate resource potential to amount and type of water supply to be provided.
Devising ways and methods of securing the needed protection to grazing land and forest stands. There is a very obvious need to suggest methods to ensure protection other than that given by barbed wire or metal fencing.
Establishing grazing reserves (Famine-Annual) and forage banks.
5. Some Possible Intervention in Northern Kordofan
The stabilized sand dunes of Western Sudan in the semi-desert zone enjoys a good stand of grass and tree cover. This falls mainly under Harrison and Jackson's classification - Semi-Desert Grassland on Sand. The grass cover is mainly represented by the Genera Cenchrus and Aristida and occasionally the valuable perennial grass, namely, Andropogon gayanus. Leptadenia and Acacia tortilis subspradiana constitute the main tree cover as recorded in the past.
Attempts by the Range Management Administration as early as 1957 to carry out work on range conservation, management and rehabilitation were made. In the first place, a fireline grid was worked out to protect the rangelands from accidental bush and grass fires. Work was limited to Dar Maganin, Northern Hamar and partly Dar Hamid.
Using the existing forest conservation law, two sites were chosen to protect the rangeland and start two grazing reserves, namely Abu Fas Grazing Reserve and Gureih El Sarah Reserve. Beside protection from continuous and untimely grazing, some management plans were worked out and some seeding trials were conducted. Gureih El Sarah received some follow-up and evaluation by different writers and workers. One important result still remains; and that the nomads on those two sites and the tribal administration were convinced and accepted to give such work a try.
The "JUZU" complex has been on focus for some time. Information on this type of spontaneous vegetation depended on notes by Darling (Government Entomologist) and to a greater extent on writings of Sir Newbold. The complex as described by them constituted mainly the following:-
i) Triraphis permulu grass
ii) Aristida papposa "
iii) Aristida hertagluma grass Nissa
iv) Neruda procombens herb Sa'adan
v) Fagonia critica "
vi) Zygophellum simplex "
vii) Crotolaria sudanica " Gutub
viii) Tribulus spp. "
This interesting and rather forgotten vegetation complex warrants further studying. The Bayoda Desert and the Nubian Desert are said to contain some "Juzu". South of the zone in Northern Hamar and in particular around Eial Bachit and, to a lesser extent, between Bur Salam and Khuwi, a good stand of Andropogon gayanus has been observed.
Andropogon was recorded in El Obeid reserve as late as 1962. The genus Andropogon is represented in the Sudan, Somalia, and is considered in the ranges of South America as key range species. In the Sudan two varieties of Andropogon were recorded with two different chromosome numbers. One is quadrimoculatus. The other is bimoculatus.
This brings out the necessity of genetical as well as morphological studies to determine adaptable varieties, ecotypes and attributes that suit dryland and arid conditions. The stretch between Dar Maganin and Dar Kababish house some drought resistant species namely:-
i) Panicum turgidum "Tumam"
ii) Hilaria mutica "gharaz"
iii) Indogofora spinosa "Sangad"
iv) Oypress spp. "Deis"
v) Aristida pallida Um Sememi
vi) Aristida hirtagluma Nissa
None of these plants has received any study. Definitely the plant Planicum turgidum has many ecotypes. The quality of the forage, its palatability and tolerance to moisture and grazing stress can be improved. Selection on phenotypic attributes should not cost much and can be done in a relatively short time. These plants, besides their forage value, can be considered as good dune stablizers and sand dune fixers.
Grazing Reserves and Range Protection in General
The problem of protection is one of the most difficult issues in Range and Forest Management and Development. Protection is needed at various stages in plant development and range management as a whole. It is rather expensive if done in a conventional way of resorting to wire fencing.
Ways and methods of realising effective protection should be thought. These should:
i) Encourage establishment of community rangelands and community forests.
ii) Motivate nomads and villagers to make their own efforts of guarding and securing protection to growing plants or reserved areas.
iii) Resort to local orders and the issue of enactment.
iv) Manipulate physical barriers and hilly areas such as Red Sea areas and some Jebels in Northern Kordofan i.e., Abu Fas.
v) Use plants as green fence of such materials as:-
a) Leptadenia pyrotechnica
b) Capparis decidna
c) Mearua crassifalia
d) Lycium arabicum
e) Comiphora spp.
Equating Water Provision to Grazing Potential and Resource Management
Another problem that needs attention in the semi-arid zone of Western Sudan under open and communal use of the grazing land is control and distribution of livestock watering points. Some suggestions were presented to control and limit range deterioration and over-grazing around water points. Others suggested to equate water provision to the resources on sites for which a water point needs to be installed. Neither of these suggestions was put to practice.
Some Possible Intervention in the Semi-Desert Zone of Eastern Sudan
Red Sea Hills strip is rather a unique area within the set-up. Its omission will deprive workers from exhibiting their excellence. Some of the factors that should be considered to assess Red Sea Hills potential and unique environment are:-
1. Latitude effect
2. Altitude effect
3. Winter and Summer rain peaks
4. Humidity and Sunshine
5. Water harvesting possibilities
6. Presence of salt bush vegetation
7. The inhabitants
Water spreading work had been started in Arba'at as early as 1961 and a huge programme of soil conservation work was once considered as one of the greatest achievements in soil conservation work in Africa. This was no more than the dyke and bunding and water course control work in Erkuwit.
The Butana on the other hand received its quota of water development programme in the period 1950/55 and in 1960/65 in the form of earth-dug tanks (Hafirs). An effective fireline grid has been maintained since 1960.
Land pressure increased and grazing by different livestock as water became continuously available. Cattle numbers increased and with the Gneid, Khashm El Girba Scheme and recently El Rahad, more animals were kept and grazing pattern changed and migration to the south was modified. The valuable grazing species of the Butana were virtually annihilated and destroyed. Blephoris edulis which has been recorded in a survey by Harrison and Baasher (1955), covering the area between Jebel Mundra and Suba'ah is no longer there. Vast areas of Sehima ischaemordes, the valuable grazing grass locally known as "dambalab", had been destroyed. Two other herbs distribution also either became limited or completely disappeared; namely, Ipomea cardiosepla and Crotolaria maxilaris.
A Proposed Rangeland Rehabilitation Project
The Butana clay plains are almost stoneless and contain vast open treeless expanse of land which are suitable for the use of tractor-driven implements and for large scale land preparation and plant establishment.
Tractor operation and maintenance and the cultivation of large tract of land are well-known and practised.
It is suggested that several land units of selected grazing land in Butana (between Kaasmur and El Ghatar Hills) be left aside for grazing improvement work. Improvement can take either of two methods or both:-
i) Protecting area for several years to promote natural rehabilitation of plant cover.
ii) Introducing some indigenous or exotic plants to upgrade grazing potential.
Suggested grazing plants include:
i) Blephoris dulis ii) Sehima ischaemordes
iii) Cenchrus ciliaris iv) Cenchrus setigrus
v) Renchosya memnonea vi) Crotolaria maxilaris
vii) Clitoria terntea viii) Phaseolous trilobus
ix) Indigophora spp.
Protection is very essential and is considered the key in all range development and improvement.
An effective way is to convince people themselves to do the desired protection. Protection can be partial for few months or total for one year or more than that.
A second way of doing it is to select some guards and give them some incentive by letting them make use of the crop of dura grown or dura stalk if the crop fails in such marginal land.
Around the selected area for protection several rows of crop of dura (five disc plough width) are being established around the area to be protected (see diagram below). Several guards can be appointed either on voluntary basis or on nominal payment together with return from the dura crop or dura stalks.
It is customary that nomads respect cultivation and with partial guarding and an obvious demarcated areas a good protection can be realized.
Community grazing land in the same way as community forest can be tried and adopted as a future philosophy of involving people in grazing resource management and rehabilitation.
References
Harrison and Jackson (1955). Vegetation Map 1955. Sudan Survey Department.
N. Sankary (1967). Rangeland in the Arab Rep. of Syria.
Lebon (1965). Land use in the Sudan. Cambridge Univ. Press.
