Fuelwood consumption in a central Malian town And its effects on browse availability*

R.T. Wilson

Senior Animal Scientist, International Livestock Centre for Africa, Arid and Semi-arid Programme. Niono, Mali

Introduction

The study area

Current fuel wood use and projected demand

Effects on browse production

Discussion

Acknowledgements

References

Introduction

Estimates of the fuel wood consumption in Africa for 1975 were 264,500 thousand cubic metres with consumption increasing, in line with population increase, at 1.7% per, year. Fuel wood use comprises 84% of total wood use in Africa (FAO, 1978). Assuming that the increase in the rate of consumption remains constant, the fuelwood requirement will double every 41 years.

According to the same source, fuelwood consumption in Mali was 2,792 thousand cubic metres in 1975 and accounted for 91% of total wood use. It is estimated that annual demand is increasing at 2.3% per annum, equivalent to a doubling of demand in 30 years. The greatest demand is around established and developing urban centres and it is in these areas that attention has often been drawn to this phenomenon but few quantitative studies appear to have been made relating present consumption to future requirements and the potential effects on the livestock population.

The study area

Niono is a district administrative headquarters and the commercial and managerial focus for some sixty-five thousand hectares of rice cultivation. Its location in central Mali puts it in the southern Sahelian zone with long-term annual rainfall of 550 mm, although in recent years this has been reduced to a figure below 500 mm.

In the ten-year period 1967–1976 the population of Niono increased at an annual rate of just over 8%, while during the period 1972–1976 it was in excess of 12%. As with many statistics in developing countries these figures need to be treated with caution: the bases for different years are rarely the same and the methodology is not always clear. However, by 1979 the population was probably of the order of 15,000 people.

The natural vegetation, which has been cleared from much of the area, is typically Sahelian, some of the principal woody species being Acacia seyal, A. senegal, Balanites aegyptiaca, Boscia senegalensis, Commiphora africana, Combretum glutinosum, C. micranthum, Grewia bicolor, Pterocarpus lucens and Ziziphus mauritania. The discontinuous annual grass layer is dominated by Aristida spp., Cenchrus biorus, Eragrostis tremula, Pennisetum spp. and Schoenfeldia gracilis (Hiernaux, 1978).

By 1975 the vicinity of Niono had suffered, over a period in excess of 25 years, from the Anal effects of expansion of both irrigated cropping and of rain fed agriculture and the resultant increase in livestock numbers. A comparison of aerial photographs for the period 1952 to 1975 showed that: irrigated areas under rice had more than doubled from 27,760 ha to 65;040 ha rain fed cropping had almost doubled from 140,780 ha. to 255,715 ha, and "degraded" areas (a subjective value based on reflectivity on the aerial photographs)¹ had increased from 4.14% to 26.23% of the area (Haywood, 1978). This more than 500 per cent increase in degradation is due to a combination of factors which include lowered rainfall, shorter fallow periods, increased livestock numbers, greater areas of cultivation and, of course, fuel wood use.

¹ Ground checking showed that such areas correspond to bare ground.

Current fuel wood use and projected demand

Observations were carried out on transport entries into Niono town over a period of a year from April 1979 to March 1980. Niono proved to be a particularly simple town to study on account of the canalisation of the irrigation scheme which limits the points of entry to three roads. A team of observers recorded all movements into the town for periods of six hours each, the period being randomised to cover most of the factors likely to affect traffic movement: day and night, working, market and rest days, Sundays and official holidays, rainy and dry days. The census was confined to transport movements relating to animals, these being by far the largest proportion of all transport entries into the town. We calculated that more than 185,000 such movements into the town were made during the year of observation, averaging 510 per day. Most of these movements (54%) related to transport of building materials, an eloquent enough expression of the rate at which the town is expanding and of the problems which can be expected as a result.

Animal transport movements are largely by donkey cart, enabling one donkey to be between five and ten times more efficient as transport than by simple back packing. In the case of fuelwood transport we recorded 42 loads per day, each of 367 kg, equivalent to 5,622 tonnes of wood utilized by Niono in 1979/1980. Small amounts of wood transported by bicycle and by motorised vehicles were not included in this calculation but we estimate that the wood transported by donkeys is equivalent to about 95% of all wood transported. Total present fuelwood consumption of Niono can thus be put in the region of 6,000 t per year, equivalent to 400 kg per inhabitant. The preferred (and almost the only) species used for fuel wood in the Niono area is Pterocarpus lucens. Although there appear to be no data on the density of this species, other Pterocarpus are described as medium-hard and medium-heavy with a green weight of 950-1,000 kg/m³ and an air dry weight at 12% moisture of 650-800 kg/m³ (Ministére de la Coopération, 1978). Thus, in terms of volume, present annual consumption is of the order of 9,230-7,500 m³ for the whole town or 0.62-0.50 m³ per inhabitant ². These figures compare well with other estimates of urban use where supplies are not yet extremely limited, for example in northern Nigeria where it is 0.63 m³/head (Davies, 1976) and in parts of northern Ethiopia where it is 0.62 m³ (Hunting Technical Services, 1976). Other figures, where wood is an extremely limited supply and where cattle dung is the principal fuel, are as low as 0.15 m³ (author's data for 1975 for Makalle in Tigre province, Ethiopia) and where it is still abundant as high as 1.5 m³ (e.g. Gillet, in this symposium).

² i.e. about 1 kg DM/per person and per day, a figure in complete agreement with previous studies (Le Houérou, 1962).

Projected demands for fuelwood for the 21-year period (using 1979 as the base year) to 2000 assuming that individual consumption rates remain constant are shown in Table 1. This uses three constant growth rates for Niono, the more or less official figure of 8%, the more likely real figure of 12% and a possible accelerated increase of 16%.

Table 1. Projected fuelwood demand (tonnes) for Niono at three different growth rates of the urban population (1979 population: 15,000).

Population increase %	Consumption in year (tonnes)
	1980	1982	1985	1989	1994	2000
8	6480	7558	9521	12954	19033	30203
12	6720	8430	11843	18635	32841	64823
16	6960	9365	14618	16460	55593	135447

Effects on browse production

The principal effects on browse production of fuelwood utilization are the direct ones of destruction of vegetation (or, at the best interpretation, of its normal annual increment). Subsidiary effects of trampling will be not inconsiderable in the future and the probable effects of erosion from decreased cover also need to be considered. In addition the feed requirements of the increased numbers of donkeys for transport and for breeding to maintain the numbers available for transport (a five to twenty-fold increase) will effectively reduce the carrying capacity for other species. The effects of donkeys will be particularly severe on some other preferred browse species such as Leptadenia hastata (Boudet and Leclerq, 1970).

It is Pterocarpus lucens, however, which provides more than 90% of all the wood burnt as fuel in the Niono area. This is one of the most palatable and one of the most nutritious browse species, (Boudet and Leclerq, 1970; Le Houérou, 1979). Estimates of the annual increment of solid volume wood are not readily available for natural rangeland but it is probable that, under long-term rainfall conditions of 550 mm, total annual increment is of the order of 1.0 m³/ha (Whittaker, 1970). In the vegetation associations in which it occurs, Pterocarpus lucens contributes between 3.0 and 61.0% of the total numbers of trees present, but provides from 12.0 to 9.0% of the aerial cover of all species (Hiernaux, 1980). For the purposes of this exercise I have assumed that Pterocarpus lucens provides 20% of the total annual solid volume increment over the area in which it occurs, which is about 32% of the total land area of the Niono region.

At the 1979 level of consumption it is apparent that the annual wood production of Pterocarpus lucens is being used from 37,500 ha of land. Figure 1 shows projections of the total area required for fuelwood consumption of Niono town at annual rates of increase of population of 8,12 and 16% at various periods of time to the year 2000 A.D. At the middle, and most likely, rate of increase the annual solid volume increase of Pterocarpus lucens from almost 400,000 ha will be utilised; at the lower rate it will be 180,000 ha and at the higher rate one can predict the appalling figure of almost 800,000 ha. Even at the lowest rate of population increase the last figure will be achieved by about the year 2020 A.D.

Removing the wood does, of course, mean removing foliar growth, or the potential for foliar growth, or the potential for foliar growth. Average foliar dry matter production for Pterocarpus lucens is of the order of 2.5 kg per tree (Hiernaux, pers. comm.) and there are about 90 trees of P. lucens per hectare over the area on which it occurs (Hiernaux, 1980). Using these data the annual potential foliar dry matter production lost as a result of fuelwood consumption can be calculated and is shown in Table 2.

Table 2. Projected losses of foliar dry matter production (tonnes) from utilization of Pterocarpus lucens for fuelwood at different rates of growth of the Niono population.

Figure 1. Projected area of land required for fuelwood at three different rates of growth of the Niono population

Based on a composite chemical analysis of the edible parts of Pterocarpus lucens given by Le Houérou (1979) the total loss of nutrients resulting from a projected Niono population increase of 12% is shown in Table 3.

Table 3. Reduction in livestock nutrient availability from Pterocarpus lucens as a result of fuelwood use at an annual increase of 12% of the Niono population

According to the criteria of Boudet and Riviere (1968), Pterocarpus lucens is an excellent fodder with a net energy value of 5.9 MJ/kg DM, a digestible protein content of 9.5 per cent and a nutritional ratio of 125. Calcium and phosphorus are both adequate at 1.1 and 0.14% respectively although the Ca:P ratio at almost 8:1 is unbalanced while the magnesium content is 0.4% giving a good Ca:Mg ratio of 2.75:1.

To simplify the effects on carrying capacity of fuelwood consumption, it is therefore proposed to confine the calculations to dry matter intake. While there is still some controversy over the DM requirements of domestic ruminants, and while current work in Mali indicates that DM intake may be as high a 3.2 kg/100 kg liveweight (l.w.) at certain times of the year (Dicko-Touré, pers. comm.), the average year round requirement is probably of the order of 2.5 kg/100 kg l.w. for bovines although it may well be as high as 5.0 to 6.0 kg/100 kg l.w. for caprines (Le Houérou, 1978; Gihad, 1978). The daily requirement for a Tropical Livestock Unit of 250 kg l.w. is thus a minimum of 6.25 kg DM, equivalent to 2.3 tonnes DM per annum. Reductions in potential carrying capacity due to removal of browse for fuelwood will thus be of the order of 4,000 TLU in 1980 increasing to 38,650 TLU in the year 2000 A.D. These figures do not include the reduction of carrying capacity for meat and milk-producing animals occasioned by the increase of animals required for transport. This would probably be in the region of a further 5,000 TLU by 2000 A.D., including the breeding herd of donkeys necessary to maintain a working population of 1,500 donkeys.

Discussion

This paper has attempted to assess developments, over a 20 year period, of the effects of fuelwood requirements on browse production and carrying capacity. This has been done on the basis of current knowledge using parameters which are more or less correct at the present time.

In this respect the predictions are likely to be optimistic. For example, it has been assumed throughout that consumption for fuelwood is confined to renewable supplies of wood and that fodder production lost is only the current year's production. Both these assumptions are likely to be false. Renewed cutting is likely to destroy the trees, which will require recourse to ever larger areas to provide requirements. We have already seen a more than 500% increase in "degradation" between 1952 and 1975. It has also been shown (Hiernaux, 1980) that degradation by overgrazing and fuel cutting causes a reduction in total cover of Pterocarpus lucens from 15% to 2% and in relative cover from 68% to 8% and that the number of trees is reduced from 90 to 40. Natural tree mortality will be responsible for some of this loss but this is probably insignificant in relation to total losses. Some utilization of the potential loss of foliar production also occurs: for example, bundles of P. lucens leaves sold in Niono total, at present, the equivalent of 1,250 kg of foliar DM per week but this is only about one per cent of fuelwood use.

It is evident, therefore, that effects are not going to be as simple as presented here. Additional effects from erosion and from soil impoverishment will be cumulative. The probable reduction in the ability of cattle to utilize coarse standing hay as a result of the non-availability of the high-energy, high protein browse fodder also needs to be considered. The effects on goats, which spend more than 90% of their pasture time on browse in the Niono area (Dicko-Touré, pers. comm.) will be even more serious.

The solutions to the problem of fuelwood supply are in theory well known, even outside the improbable solutions (at least on our time scale) of solar or fossil fuel energy. Niono is perhaps more fortunate than many similar areas in its location in relation to the Office du Niger irrigation scheme. Many areas unsuitable for annual crops, such as drain tails and high and low areas, could provide ideal sites for wood fuel crops. If a situation at least as depressing as the one depicted in this paper is not to develop, action needs to be taken immediately to make these sites productive..

Acknowledgements

I wish to thank my colleagues at Niono, Pierre Hiernaux and Maimouna Dicko-Touré for the provision of data and for comments on the draft. My thanks also go to Henri-Noel Le Houérou who was able to assure the presentation of this paper and suggest relevant particulars and addenda.

References

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