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Soils and vegetation

The two most important interacting factors in producing soils are climate and geological materials. In turn, soils and climate work together to strongly determine the vegetation. In general the type of vegetation on a broad scale is determined by the climate. In this case the whole area may be described as lowrainfall woodland savanna. At a more local scale the soils begin to become more important, with significant vegetational differences between sands, clays, and areas with thin soils. At this level too positions on slopes or in relation to ground water can have profound effect on the vegetation. Clearly, a further factor is human beings themselves. Vegetational changes associated with human activities are deferred to section 3.

In the discussion which follows, the term "soil" is used not in the strict pedological sense but somewhat synonymously with the geological term "superficial deposit". The finer shades of meaning implicit in current detailed pedological classifications are not really relevant to the present discuss sign, and, as the main concern is with wood resources, trees are discussed to the neglect of grasses and other vegetation forms.

A suitable classification of soils in the Nuba Mountains area is threefold:

1. mountain soils

- bare rocks,
- exposed basement plateaux,
- intermontane alluvial soils,
- pediments;

2. residual soils

- the clay plains, including soils with complete, incomplete, and extremely reduced profiles,
- soils of residual and collovial origin,
- fericrete soils within eroded plains;

3. transported soils

- alluvial clays,
- alluvial fans.

This classification is embodied in figure 5.

Mountain Soils

The mountain soils are confined to mountainous areas and inselbergs. Within these areas truly bare rock devoid of vegetation is only found on precipitous slopes, especially in areas of development of domed land-forms Generally mountainsides are cut by numerous fractures or joints, which invite the development of weathering and hence may be marked by weathered material of great depth. This process is particularly intense where two fractures interact. These places are also likely to accumulate ground water and hence are favourable sites for the growth of trees.

Thus granites, granite gneisses, and syenite are often covered by clumps of leafy trees, particularly Ficus spp., including F. populifolia and F. glumosa. In gneissic mountain ranges such as those of the Heiban massif a certain amount of debris tends to accumulate on the slopes of the hills. This scree is usually weathered to some extent and encourages the growth of trees such as Boswellia papyrifera, Ficus spp., Combretum spp., Sterculia setigera, and others. Areas of migmatization and partial granitization, e.g. Jebel Doro southeast of Heiban, usually give rise to rather gentle hilly topography and are favourable sites for human habitation. In such areas Ficus spp. tend to dominate.

When inselbergs occur near human settlements, they are well terraced and the original flora is modified by human use. In less affected areas the vertical sequence of vegetation tends to be as follows: at the very top and in rock fissures Ficus populifolia and F. glumosa are found; on the steep slopes Adenium hongel is very characteristic; on lower slopes Boswellia papyrifera, Combretum spp., and Sterculia setigera are found; and at the bottom Acacia seyal and Balanites together with Combretum spp. dominate.

The larger ranges and groups of hills exhibit similar features but with better stocking. As they differ in height and occupy large areas, they form extensive catchments and provide valuable ecological niches for many rarer species, such as Cordia abyssinica. Among the ridges and troughs of these ranges plant communities relate to the soils formed in the troughs, particularly soil depth and texture, and a variety of trees can be found such as Anogeissus, Albizia, Boswellia, Combretum spp., Sterculia setigera, and Sclerocaria birrea. At the bottom of such ranges, alluvial fans and detritus favour such trees as Boswellia, Adansonia digitata, and Hyphacne thebaica.

On the basement complex plateaux such as the plains east of Rashad and around Jebel Umm Dorein, the granite or gneissic rock is covered by a thin veneer of lateritized soil resting on weathered rock with a high capacity for retaining moisture. This type of terrain is usually well drained and is characterized by very short grasses and a tree assemblage consisting of Albizia amara, Sclerocaria birrea, and Boswellia papyrifera with occasionally Ficus and Combretum spp.

In intermontane alluvial soils the sands and clays dumped by khors form wide terraces which are later homogenized by soil-forming processes. In these valleys two distinct types must be recognized: On the high level flood plains, which are characterized by thick narrow zones of loamy clay traversed by a meandering khor course-e.g. north of Kauda in the Heiban area-the most important tree types are Acacia albida, Balanites aegyptiaca, and Ziziphus spinachristi. In the lower reaches of khors, peneplain inter fluvial areas occur, characterized by the development of ferricrete loamy clay soil, usually intensively cultivated. Their natural vegetation may be inferred to include Anogeissus schemperi and Ziziphus spp.

Residual Soils

The clay plains are geomorphic features of indeterminate age. However, during a wet phase of the late Pleistocene extensive weathering of the largely gneissic and granitic basement took place. Under these conditions most of the alkaline calcareous and siliceous as well as ferromanganesian constituents were removed. This resulted in accumulation of largely montmorillonitic clays. Later on accumulation of CaCO₃ and CaSO₄ as kunkur nodules took place. Usually these nodules start at a depth of 1-1.5 m and increase in numbers downwards. A section of clay soil examined near Delami had the following profile:

- 0-100 cm, dark clay with fine quartz grains,
- 100-200 cm, grayish clay with kunkur nodules and mediumsized quartz grains,
- 200-250 cm, granite with course quartz grains undisturbed, in a greenish grey clay matrix replacing the feldspars,
- 250-315 cm, weathered granite similar to the interval above but with white clay, possibly kaolin,
- below 315 cm, slightly weathered porphyritic micro-granite.

An examination of the soil map (fig. 5) reveals an interesting alternation of soils of complete and reduced profile in narrow northeast-trending strips. This peculiar configuration is closely associated with the pattern of neotectonic movements discussed earlier. It can be demonstrated that the clay plains-especially the area within the DillingKurtala-Delami triangle-are exceptionally prone to erosion (fig. 3). The soils of the plains may be roughly classified into three main types depending on the effects of erosion accentuated by neotectonic movements: soils of complete profile (characterized by a clay layer of 3-5 m or more), soils of reduced profile (less than 3 m thick), and soils of extremely reduced profile (less than 2 m thick). The following is a description of these soil types and their vegetation.

1. On the deep-cracking clay soils of complete profile, Acacia seyal (talh) and Balanites aegyptiaca (heglig) are the type species. When these trees dominate, tall grasses are their associates. The tall grasses are extremely inflammable and grass fires add to the difficulty of natural regeneration of these trees.

2. Clay soils of reduced profile, with a thickness of less than 3 m, are confined mainly to relatively uplifted blocks. The signs of erosion of the clay profile are evidenced by the exposure of the kunkur nodules at the surface and the presence of pebbles and rock fragments. The undulations of relief may give rise to slopes of 10 to 15 degrees. The density of khor systems is greater than in the full-profile clay areas. This soil type is often dotted by areas where the basement comes out at the surface either as low, rocky ground or as small, low hills. The vegetation over such clays is an association of Anogeissus schimperi and Albizia spp., with Acacia seyal appearing where the soil tends to be deeper and Boswellia papyrifera where it becomes more shallow and stony.

3. Clay soils of extremely reduced profile, less than 2 m thick, are characteristic of areas of intensive denudation associated with earlier tectonic movements leading to considerable tilting of the land surface, e.g. west of the Heiban massif and along the east side of northern Wadi el Ghalla. Some of them are related to slightly raised blocks of the basement like that around Jebel Umm Heitan. In such areas the drainage system is very dense, and small, low, hummocky hills are numerous. The clay is greyish and often tends to be ferruginous with a characteristic vegetation. This vegetation was observed in the region between Wadi el Ghalla and the Gulud massif. Along the sides of the water courses the following trees (in order of dominance) occur: Anogeissus leiocarpus (sahab), Dalbergia melanoxylon (babanus), Acacia mellifera (kitr), Albizia sericocephala (arrada), Combretum spp. (habil), Tamarindus indica. In the flat spaces between khors Albizia amara, Anogeissus, Dichrostachys glomerata, Piliostigma reticulata, Dalbergia melanoxylon, and Acacia mellifera occur. Elsewhere, on very shallow clays with numerous drainage lines, a sparse cover of Anogeissus, AlbizIa amara, Dichrostachys cineraria, Piliostigma reticulata, Dalbergia melanoxylon, and Acacia mellifera is found.

Soils of mixed residual and colluvial origin occur in many parts of the Nuba area where the irregularities of relief do not allow for a truly residual soil. One basic type of such mixed soils, that of soils in areas of sharp relief contrasts, is included here. This is notably developed in a large area of rocky terrain between Lagawa and Jebel Demik. Here low ridges of rocky terrain alternate with shallow troughs of clayey soil. While the ridges are partly covered with clay and the rocky outcrops are partly exposed, the troughs are usually covered with clay and some rocky debris. The clay results in part from weathering in situ and in part from short-distance transport from the ridges by solifluction. Under these conditions the vegetation varies with position in the terrain. Anogeissus, Albizia, Boswellia, Combretum, and Dalbergia thrive on the rocky or partly covered ridges, while Acacia sepal, Balarites, and occasionally Combretum and Albizia may develop on the clayfilled troughs.

Ferricrete soils within eroded plains or laterites are widely known in the Nuba area, particularly in the Talodi area to the north and south of the Masakin Hills and along the Kalogi Talodi road. Remnants of these soils may also be encountered along the asphalt road near the old Kadugli airport. The laterites are agglomerations of pisolitic nodules of goethite and limonite iron hydroxides and always rest directly on partly weathered basement, in which some of the feldspar is altered to a gray-green clay. They are certainly partly eroded but the relation of these laterites to the clay soils is not clear. They must have evolved under very special humid conditions and possibly predate the clay plains. It is difficult to characterize their vegetation, but Anogeissus and Ziziphus spp. appear to be important.

Transported Soils

The transported soils consist of alluvial clays in wadis, khors, and alluvial fans. Alluvial clays in khors and wadis are very common in the Nuba area. The wadis are, properly speaking, flood plains, with the actual khor course not exceeding 50 m in width. These systems often exceed 30 km in length and vary from 200 to 1,000 m in width. The alluvial soil is predominantly clay but with occasional layer of sands. The natural vegetation of the khors is variable and has been extensively modified by human interference. In small khors of the Berdab area the following trees were recorded: Ziziphus spinachristi, Sclerocaria birrea, and Diospyros mespilliformis as well as Anogeissus spp., Albizia spp., and Combretum spp.

In large flood plains most of the tree vegetation has long since been cut down. However, it is likely that Acacia seyal and Balanites were the dominant type species. Imposing stands of Borassus aethiopicum and Hyphasne thebaica can still be observed, and there is evidence to suggest that they were once more widely spread than at present. Similarly Cordia spp. were at one time much more common than at present.

Alluvial soils of various kinds surround the large hill masses Coarse eroded material is immediately near the hillsides and finer materials further away. Around large granitic massifs, such as Gulud, sand areas spread out over the clay plains. Such areas are covered by a vegetation typical of clay soils of reduced profile, even though the underlying clays may be quite thick.

The picture presented in this section is somewhat idealized, for it is plain that human activities have greatly reduced the tree stock, in terms of both the number of trees and the variety of types. Some species formerly common are now rare. The areas most affected have been the plains and other areas of more fertile soil. Here clearance has been for agriculture, formerly of a subsistence, land-rotating type but more recently for commercial cotton growing and for mechanized cultivation. Even the more hilly areas have been affected, because unstable conditions on the plains at various times induced people to retreat into the hills and construct terraces on the hillsides to avoid dependence on plains agriculture. Only the isolated and very remote and more precipitous slopes of the mountains retain their pattern of vegetation undisturbed.

At the same time a rising population has given rise to a need to clear more land for farming and increasing demands on the woodland resources for fuel, furniture, and the like, The result has been that the potential wood resources of the Nuba Mountains are less than might be expected, and the need for a rational policy for their use and an inventory of what the resources really are is now essential.

III.3. Wood resources and their use

The present wood resources position
Fuelwood consumption
Wood resources and agricultural land use
Wood for construction
Vegetative resources for furniture and craft industries
A model of wood resource misuse in the Nuba mountains area

Section 2 has given some indication of the potential vegetative cover of the study area without consideration of the human impact on the scene. This section deals with the way people have utilized the resources and some of the results of their intervention. Although most of the discussion deals with wood resources (i.e. trees that produce timber and fuelwood), it is also appropriate to include other elements of the vegetative cover such as bushes and grass as well as other useful parts of the tree, including leaves, fibre, exudates, and fruit. These are extremely useful for cottage industry, food, and local medicine in the community. The way they are obtained sometimes affects the wood resource; for instance, overcutting of zaaf (dom and doleib palm leaves) may kill the tree and over-stripping of the bark of other trees may lead to the same result.

On the basis of the climatic conditions outlined in section 2, one would expect the area to be well covered with natural woodland. Figure 5 in conjunction with the text represents a reconstruction of the original "potential" natural vegetation. The pattern (the details of which have also been outlined in section 2) represents a transition from thorny, small-leaved acacias in the clay areas, interspersed with tall grass, to broad-leaved deciduous species of the woodland savanna in certain gardud (sandy loam) areas.

That general pattern is certainly not the visible pattern of today. Wood is virtually the only source of energy available in rural areas of Sudan such as the Nuba Mountains. Only two of the 396 survey respondents (a senior government official and a large trader) used kerosene for cooking. But even they use firewood for making kisra (thin sheets of sorghum bread) and charcoal for ironing, and turn to charcoal for cooking when kerosene is not available.

Besides its general use for cooking and for making kisra and marisa (local beer), wood is also used for lighting, heating, and other household purposes. Firewood represents the most important source of energy in the whole area. Charcoal is only beginning to gain importance in areas A and B (fig. 3), and the use of kerosene is limited to lighting purposes. Furthermore, although the consumption of charcoal, percentagewise, is far lower than that of firewood, the actual amount of wood converted to charcoal is relatively very much higher because of the poor quality produced by primitive methods and the traditional household method of firing stoves in the open air.

The present wood resources position

Most of the area is covered with thin forests with a limited range of species, with most trees being young, thin, and short. The joint effects of the widely practiced traditional shifting cultivation and fire are responsible for the reduction of wide tracts of the original forest to fire-swept woodland. The introduction and expansion of mechanized farming in the area has led to the total destruction of nearly half a million feddans of woodland, especially in areas B and C. Intensified grazing due to the increasing invasion by both cattle owners and camel owners from areas seriously affected by desertification in the north; increasing consumption of wood resources for fuel and building purposes due to the increase in population, settlement, and urbanization in the area; and the destructive effect of termites in infected regions-all represent further causes of deterioration.

The remaining heavily forested areas are distant from settlements, agricultural fields, and traffic routes. Here tall acacias and tall grass, especially Cymbopogon nervatus ((naal)) and Sorghum vergatum (adar), are to be found. The survival of these forests is explained by either protection, inaccessibility, or lack of water for human occupancy. The existence of some tall trees within or near settlements and other areas of human activity can be related to one or more of the following factors:

- They belong to species resistant to fire.
- They are too large to be cut down with the limited technology available to the local inhabitants.
- They have intentionally been preserved because they serve some important use, such as providing fruit or other parts of nutritive value, materials for local pharmacoutical preparations, or raw material for rural and traditional industries, or providing shade and a place for community meetings (this applies in particular to broad-leaved trees). The trees most commonly preserved are tebeldi, heglig, dom, and doleib.
- They are in a Forest Department reserve, where cutting by local inhabitants is prohibited.
- Cutting has been prevented by the intervention of a kujur (shaman) or sheikh (local chief or headman) for religious or community reasons.

Generally, the higher the technology adopted in human activity, the more destructive is the pattern of deterioration of wood resources, and so the northern area (area C) has suffered destruction and deterioration more than the other two.

The distribution of the existing species is generally associated with the type of soil. On the clay cotton soils, talh (Acacia seyal) is the dominant type, being relatively resistant, to the fires that rage across the plains in the dry season, associated sometimes with natural causes but more often with human activities in clearing for cultivation, burning to stimulate new grass for animals, or hunting. However, talh diminishes on the approach to settlements, an indication of the high consumption of this species by the local inhabitants especially for firewood and charcoal-making.

Most of the slopes of the isolated hill masses are bare of vegetation, either because they are bare of soil or because they have been cleared for settlement and terrace cultivation. But on the sides of the wadis and dry streams, especially in the hilly areas, dam, doleib, habil, and talh can still be found. Dom and doleib palms, indicators of the availability of water, are usually associated with settlements.

Calotropis procera (usher) is a sign of land deterioration and is to be found associated with abandoned mechanically cultivated fields and within or near certain settlements where intensive cutting and grazing takes place. Other bushes, such as Acacia nubica (la'ot), Ziziphus spinachristi (sidr), and Capparis decidus (tundub), have a much more limited distribution than in the past. Grasses often show signs of deterioration and may even be totally absent near big settlements as a result of over-grazing and over-cultivation

The plantations of the Forest Department include such exotic species as teak (Techona grandis), varieties of eucalyptus, and Azadirachta indica (neem) as well as Acacia senegal (hashab) and doleib. Some of the main plantations are to be found at Kalkada, Faggug, Umm Abdalla, Keilak, and Dilling. Neem was introduced during the early days of the Condominium and is therefore also associated with service centres and large villages, where it is grown in abundance.

Fuelwood consumption

The rest of the study is concerned with an analysis of results obtained in the special study areas A, B. and C (fig. 3). It should be borne in mind that area A is the most remote and inaccessible of the three areas, area C is the most accessible because of its proximity to the tarred road to Dilling and El Obeid and the programme of mechanized agriculture initiated here; area B. north-west of Kadugli, falls in between.

The present consumption of fuelwood as revealed by the questionnaire survey is 1.24 m³ per capita per year. Slight variations are found between the different areas:

- area A, 1.15 m³ per capita per year,
- area B. 1.34 m³ per capita per year,
- area C, 1.25 m³ per capita per year;

but wood fuel consumption in all the study areas appears to be far less than the average of 1.83 m³ per capita per year estimated for Sudan as a whole (Mukhtar 1978). Of the total fuelwood used in the study areas, 73 per cent was used directly as firewood and the remaining 27 per cent was converted and used as charcoal (compared to 67.8 and 32.2 per cent respectively for Sudan as a whole). These figures do not reflect the actual rate of consumption of the two forms of fuel, because the traditional local methods of charcoal production in the Nuba Mountains use more wood per unit of charcoal than the somewhat more efficient methods used in most other regions of Sudan.

Firewood

Table 3 shows that firewood is the most important source of fuel in the Nuba Mountains, with 68.4 per cent of the people totally dependent on it for their cooking and heating. It is clear that areas and groups with less access to more advanced technologies, i.e. rural areas and areas A and B. are more dependent on firewood than the urban areas and area C. However, even here two-thirds of the households rely mainly on firewood for their fuel needs. Moreover, because of low incomes, the increasing prices of kerosene and gasoline, and the difficulty of obtaining them from legal outlets, firewood is becoming more important than the other fuels even for lighting purposes (80 per cent of the respondents in area A rely on it for this purpose). The use of kerosene and gasoline is limited to urban centres, government institutions (such as schools and dispensaries), and the houses of government officials and traders who can afford it and manage to acquire it officially or through the black market.

The importance and the widespread use of firewood can only be explained by the fact that it is the cheapest and most available fuel source. In fact nearly ail the firewood in the rural areas and most of it in the urban centres is collected from the neighbouring woodlands free of charge. Even when it is marketed in urban centres, it is always much cheaper and easier to obtain than charcoal or kerosene.

TABLE 3. Dependence on firewood for household purposes (other than fighting)

Source: questionnaire survey
Figures in parentheses are percentages.

In the whole area, rural and urban, firewood collection is a female activity. Males usually regard it as degrading, to the extent that they feel insulted when asked whether they take part in it. The fact that women are responsible for collecting wood and transporting it on their heads and are responsible also for cooking leads to greater rationality of resource use. It is in their interest to maximize the utilization of wood so as to minimize the effort of collection and transportation. For example, they usually try to collect and keep the charcoal produced after burning wood to be used for further cooking purposes, especially for making tea and coffee.

The women usually collect dead dry wood or wood that has fallen. In this respect the activity is rational, since they do not cut green or living trees or bushes. In the rare cases when they cut wood, they usually use the selective coppice method and cut only the small and medium branches. Their primitive technology helps in the conservation of trees since their tools are not capable of cutting mature tree trunks. This is more clearly evident in the rural parts of area A, whereas in the other two areas more intensive wood cutting is increasingly frequently practiced, even in the rural sections.

The collected firewood is usually tied in bundles of a headload weight (ras), each consisting of 10 to 15 pieces 1-2 m in length and with an average diameter of 10 cm. The bundle is then carried from the area of collection to the village, a distance varying from an average of less than 1 km in area A up to an average of 3 km in the large villages of area C. The greater distances in area C are caused by the larger population and more urban or semi-urban centres with higher demands for wood especially for cooking and from bakeries, boarding schools, and similar institutions. Furthermore, the area has experienced more clearing for agriculture and has had to help to satisfy the wood demands of urban centres, such as El Obeid, outside the study area.

Although all dead, dry, or fallen wood may be collected and used, the preferred species are talh (Acacia sepal), sahab (Anogeissus (eiocarpus), and babanus (Dalbergia melanoxylon). They give more heat, burn longer and give more charcoal as a by-product and their smoke, particularly that of talh, is more bearable. (Married women in northern Sudan sometimes burn talh for its smoke as a form of aphrodisiac, though the practice is not as popular in this region as elsewhere.) Babanus and sahab can be broken into small manageable pieces when dried, which facilitates transportation, handling, and use.

Cutting firewood, as opposed to collecting it, is associated with firewood marketing, which is closely linked with urban settlements and service centres. In rural areas, firewood cutting is not usually on a commercial basis and is limited to villages where modern agriculture is practiced, especially in area C. Here, because large areas have been cleared for modern cultivation, simple collection would not satisfy local needs.

Commercial firewood cutting usually takes place 2-5 km from settlements and is essentially an adult male activity. Cutters, who are at the same time wood sellers, range in age between 20 and 50 years and include particularly Arab nomads, such as the Shenabla, Hamar, and Kawahla. However, a small number of cutters are also found among the Dinka and Nuba. Most of the small number of women and children involved are Nuba. Nomads who engage in it usually have only small numbers of animals, which they can leave with another member of the family. This is a dry-season activity which takes them to urban centres, where they can spend their earnings on grain, sugar, tea, and other consumable items. Selling is usually direct to consumers in their own homes. A nomad would normally expect to sell a camel-load each day. If he has a regular customer, such as a bakery or a restaurant, he may very well dispose of two or more loads in a day. Dinka and Nuba sellers could do the same, but they bring smaller quantities with them since they use donkeys or heads for transporting the firewood. Women and children transport wood on their heads and sell it in the marketplace by the piece.

Most of the woodcutters interviewed preferred talh because it brings more money (10 piastres more per camel-load than other types). An average head-load of talh sells for 3 to 4 piastres. Other popular woods include babanus, sahab, kitr, and arrada. Near certain urban centres, such as Lagawa, Habila, and Delami, talh is not locally available because of intensive cultivation and cutting. Here cutters content themselves with any type of tree found in the neighbourhood rather than spend time and effort bringing talh from distant areas.

Although most of the firewood cutting is of the selective coppice type, cutting by certain nomadic tribes, such as the Shenabla and Hamar, is a destructive process. They cut the whole tree and prefer younger trees of two to three years of age. They say that whole trees require less effort in cutting and can be sold in logs rather than being cut into further small pieces. However, this would seem to reflect a particular perception of the tree in their homelands. Faced with the relative rarity of trees there, they always try to cut whatever they find for firewood. Moreover, since only bushes and small thin trees are available in their homelands, they have little experience of cutting older and larger trees.

Commercial firewood cutting is regarded by those engaged in it as a source of supplementary dry-season income. With the first rains the nomads move northwards, and settled peoples move out to their fields on the clay plains to prepare for the new cultivation. During the wet season urban consumers either collect wood themselves, use supplies in store from the dry season, or meet their needs by buying from the Forest Department firewood centres The fact that an average of 46 per cent of those interviewed in urban areas stated that they are usually in the fields during this season and do not need to obtain firewood from the urban shows the strength of the agricultural function in the urban centres of the study area.

TABLE 4. Consumption of firewood (m³) and charcoal (m³ wood equivalent) per capita per year

Source: questionnaire survey

Table 4 shows the amounts of firewood and charcoal consumed as determined by the interviews carried out in each area. Variations between the areas in per capita consumption are significant. Firewood consumption is higher in areas A and B but lower in C, with urban consumption much lower than rural in each case. The higher consumption in areas A and B is a reflection of the greater availability, greater facility of collection, and resultant lower prices of firewood. Furthermore, A and B are somewhat damper regions with less pressure on available resources. However, it should be noted that there is a higher consumption of charcoal in areas B and C.

The mean annual per capita consumption of 0.89 me of solid wood is much lower than the 1976 figures compiled by Mukhtar (Mukhtar 1978) of 1.36 m³ for Darfur and Kordofan and 1.35 m³ for Sudan as a whole. Furthermore, the urban consumption figures are much lower than those suggested for Northern Kordofan. Digernes (1977) suggests 1.32 m³ for Bara Town.

Charcoal

Charcoal, with an average annual household consumption over the area as a whole of two large sacks (equivalent to 100 kg), does not represent an important phenomenon in household energy consumption. It has some importance, however, in urban centres, where its use is increasing because

- there is a lack of local firewood resources due to clearing;
- charcoal is easier to transport and handle than firewood, and
- charcoal produces more heat and is almost smoke-free.

In most rural households the only charcoal used is derived from firewood ashes, and it is only used for making tea and coffee.

In those rare cases where charcoal is produced in the villages, both collecting and/or cutting the wood and burning it is women's work; the quantities produced are small and are mainly for home consumption, with a small surplus sold in the local village market. Charcoal production such as this is usually confined to villages near the small urban centres. The charcoal is carried on the head and sold there by the tin or by the heap (koum). Selling in the market is often carried out by children, usually girls.

The other suppliers of charcoal to meet the expanding demand from the urban centres are local male Arab nomads, Dinak and Nuba charcoal burners, the larger scale illegal charcoal burners, and the Forest Department.

The local male charcoal burners engaged in the industry are mainly between 35 and 50 years of age. They primarily collect dead dry wood, actually cutting wood for charcoal only to a very limited extent. Only about 10 per cent of the burners in this category who were interviewed indicated that they cut wood, and then they usually confined themselves to talk because it is the most suitable wood for their purposes. Although all types of available dead dry wood are collected, talh and sahab are preferred for charcoal production because both are likely to be found in large pieces, their smoke is tolerable, and they produce efficient charcoal. The burning is done in traditional small earthen kilns, which take 15-18 m³ of air-dried wood and have a yield of only 8-12 per cent, producing two to three medium-sized sacks of charcoal, each sack holding 45-50 kg. After three days of burning, the kiln is opened, the fire is put out, and the charcoal is left to cook for a whole day. The product is then put into sacks and transported on donkey-back to the nearest market.

For all the people of this category who engage in charcoal production and marketing, the activity is a supplementary dryseason source of income. In the wet season the local inhabitants are engaged in cultivation away from the settlements, and the nomads move northwards, often loaded with wood, charcoal, and pottery to sell in the northern areas. Charcoal production and dealing is therefore very limited during this season here and is associated with other channels of production.

Illegal charcoal burning takes place on a wider scale, but tracing it and estimating its real extent is difficult, since the people responsible for or engaged in it are not prepared to reveal anything about the volume and areas of production or even to admit that they are involved in the practice.

Just by chance, driving by night from Kadugli to Lagawa, our research team lost its way in the woodland and were following a subsidiary and barely passable track when we came upon many earthen kilns used for charcoal burning. Since we were driving an official Landrover, the six burners in the camp were very hostile and unwilling to respond to our questions. Eventually, after convincing them that we were engaged in research and not connected with government, we ascertained that they were employed by a rich dealer and building contractor from Kadugli and were paid 150-200 piastres per day according to their experience. These workers were responsible both for cutting wood and for burning it in earthen kilns of 40-50 m³ capacity. The average production was about 200 sacks a week and the charcoal was transported in the employer's own truck. Some went to Kadugli, but the larger part went to such towns in Northern Kordofan as El Obeid and En Nahud. Charcoal from the camp was sold in Khartoum during the oil crisis of 1978/79. The activity is almost entirely confined to the dry season because of operational and transport difficulties during the rainy season. Mature trees of at least ten years of age are chosen, talh, kitr, and sahab being preferred.

There was evidence to suggest that at least four other illegal charcoal-burning camps exist in this area. Demand from the northern towns and the newly constructed tarmac road linking Kadugli with El Obeid via Dilling seemed to be the major factors accounting for largescale charcoal burning in this area.

Charcoal production by the Forest Department in the province amounted to some 13,500 sacks in 1979, constituting only 3 per cent of the total consumed in the province. Although this is an insignificant proportion, it is six times higher than the department's share in charcoal production for the country as a whole (Mukhtar 1978). It also gains in importance in that the charcoal is of better quality, has a higher recovery rate of 15 per cent, and is to be found on the market during the rainy season, when most of the traditional indigenous production ceases. More important perhaps is that no wood is cut specifically for this purpose, as the department's supplies derive from land cleared for mechanized cultivation and other agricultural purposes.

The charcoal is produced in earthen kilns by experienced regularly employed burners for the larger centres in the area such as Kadugli, Dilling, Lagawa, Talodi, Er Rahad, and Abu Gubeiha. This department, like many others of its kind in the area, is faced with many difficulties, including shortage of spare parts for its vehicles and other necessary inputs, making it much less efficient than it might otherwise be.

The consumption of charcoal in the study area is shown in table 4, which has been prepared from the answers given relating to consumption by all people interviewed and checked against the money spent in buying charcoal in the whole area. The annual per capita consumption of charcoal is almost half a sack, equivalent to 0.35 m³ of solid wood -much higher than the estimate of 0.05 m³ for western Sudan in 1976 (Mukhtar 1978). However, this was based on "official" production and omitted the informal production described in this paper. Primitive traditional methods of charcoal production help in explaining the fact that the per capita consumption of wood for this purpose is as much as one-third of that firewood even though charcoal plays only a minor role in household energy consumption in the area.

Table 4 also shows again that more charcoal is consumed per capita in urban than in rural areas and more in the relatively more economically advanced area (area C) than in the other surveyed areas.

Charcoal prices range between 18 and 20 piastres for a tin and between 100 and 150 piastres for a medium sack. The prices seem to have increased enormously during the last five years. An average increase of 250 per cent for the whole area has taken place. Moreover, higher prices in the urban centres during the wet season are becoming a common occurrence. An average household in town spends about £S 15 a year on charcoal to supply only about onethird of its fuel requirements. The high rise in prices is due to the overall rise in the cost of living and to an increasing demand for charcoal, which now exceeds the supply. Of those interviewed 68 per cent indicated that they can cope with the price increases and 29 per cent claimed that they cannot. Nearly all those having difficulties with the increased prices were turning to firewood as a substitute, as it is readily available and very cheap. In fact 8 per cent of the respondents in service centres said that formerly they used charcoal but had changed to firewood because it was cheaper. However, all the evidence suggests that charcoal consumption will increase further in the future and this will result in increasing felling and collection of wood in the vicinities of the major towns of the area, with a consequent deterioration in the natural environment.

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