Chapitre III. Utilisation des ressources de la biodiversité

Date de sortie 27/03/2009
Donateur hdekoeijer

 

Chapitre III. UTILISATION DES RESSOURCES DE LA BIODIVERSITÉ

Les plantes et les animaux qui viennent d'être décrits à travers les ressources génétiques constituent les ressources de base pour le développement économique et socioculturel du Mali. Ces ressources exploitées par les générations passées doivent être utilisées rationnellement aujourd'hui pour permettre aux générations futures de subvenir à leurs besoins.

De ces ressources, l'homme tire sa nourriture, ses médicaments, son énergie, ses engrais pour l'agriculture, ses ressources fourragères, ses matières premières pour l'industrie et l'artisanat, ses produits cosmétiques et parfumés, ses matériels culturels et touristiques, etc.

3.1 SOURCES D'ALIMENTATION

3.1.1 Plantes sauvages

Plusieurs plantes sauvages sont des sources de nourriture régulières (Baumer, 1995). Leur valeur nutritive est souvent supérieure à celle des plantes cultivées. Ce rôle peut être illustré par quelques exemples :

  • les jeunes feuilles fraîches d'  Adansonia digitata (Baobab)  donnent un excellent légume ; séchées et réduites en poudre, elles sont vendues comme ingrédient dans de nombreux plats et sauces. Les quantités de feuilles consommées au Mali ont été évaluées à 2 kg/personne/an. La pulpe de son fruit contient une forte teneur en vitamine C ;

  • les graines de  Boscia senegalensis  , utilisées en cas de pénurie, ont une teneur élevée en protéines. La consommation des graines nécessite cependant des précautions pour leur préparation en raison des substances toxiques qu'elles contiennent ;

  • les fruits du karité (  Vitallaria paradoxa  ), ou  shii  , sont consommés directement et le beurre extrait de l'amandier constitue la principale source de lipides végétaux en milieu rural (0,62 kg/personne/an, alors que les autres graisses végétales ne représentent pas moins de 0,09 kg). Les amandes et le beurre de karité occupent une place importante dans les exportations du Mali ;

  • la pulpe du fruit de  Parkia biglobosa  (  neré  ), riche en glucides, se consomme fraîche ou bouillie après séchage. Les graines sont utilisées pour préparer le "Soumbala", un condiment très commercialisé dans la sous-région. La pulpe est utilisée comme farine alimentaire en Europe ;

  • les fruits de  Saba senegalensis  (  sable  ),  Tamarindus indica (n'tomi)  et  Lanea microcarpa (n'pékou)  sont consommés directement. Ils sont utilisés pour préparer des boissons ou utilisés comme ferments de bouillie de céréales ;

  • Borassus aethiopium (seb)  : le bourgeon se consomme cru ; le fruit bouilli est aussi consommé tandis que le bois est excellent en construction ;

  • Sclerocarya birrea (n'gunan)  : le fruit est transformé en boisson alcoolisée ;

  • Detarium microcarpa (n'taba coumba)  : le fruit est sucé et la pulpe sert à faire des boulettes qui sont également consommées ;

  • Nymphea sp (n'gokou)  : le fruit se consomme cru ou bouilli ;

  • les graminées sauvages (  Panicum laetum  ,  Cenchrus biflorus  ou  noronan  ,  Eragrostis pilosa  ,  Echinochloa stagnina ou bourgou  , etc.) sont courantes dans l'alimentation des régions nordiques. Ils contiennent environ 10 % de protéines, presque autant que le riz ;

  • le  rhizome Cyperus rotundus  (n'guéni)  est utilisé comme encens ;

  • les feuilles de plusieurs espèces de  Corchorus (fakouhoï en sonrhaï)  sont transformées en ingrédient de la "sauce noire".

3.1.2 Plantes cultivées

L'homme a très vite domestiqué de nombreuses plantes et constitué une collection de variétés utilisées pour la production alimentaire. Elle a développé des technologies agricoles adaptées aux caractéristiques génétiques et agro-écologiques. Les principales cultures sont : le mil, le sorgho, le maïs et le riz (Cf. Tableau 8) qui constituent la base de l'apport calorique de la population (80%) et le coton, principale source de recettes d'exportation du secteur primaire.

Tableau 8 : Evolution de la production céréalière de 1987 à 1997, en tonnes

Campagne

 mil   Sorgho    Mais  Riz Fonio Maïs  Total

des céréales
 1987/1988 693.526  513.176  178.609  236.568   15.589 1.425  1 638 893
 1988/1989  999.901  672.429  214.519  287.797   20.184  1.115  2 195 945
 1989/1990  841.793  730.836  225.393  337.749  18.929  1.710  2 156 410
 1990/1991  737.007  531.433  196.579  282.366  21.768  -  1 769 153
1991/1992  889.896   770.044  256.775  454.349  40.506  2 540  2 414 110
1992/1993  582.296  602.254  192.530  410.018   20.898  1.256  1.809.252
1993/1994  708.062  776.879  283.373  427.609   29.735  2.210  2,227,868
1994/1995  897.592  746.218  322.492  469.127   190.271  2,650  2,457,350
1995/1996  706.666  710.275  264.457  462.702  22.179  6.150   2,172,429
1996/1997   738.856  540.273  289.761  613.965  14.992  3.086  2,200,933
Mean  770.093  659.382  242.449  398.225   22.415  2,460  2,104,034

 Source: DNSI/CPS, 1998

In addition to cereals, other crop plants such as potato, sweet potato, cassava, yam, okra, tomato, eggplant, onion, etc. enter the ration of the population. They are intensively produced in peri-urban areas and in the Office du Niger, the Dogon Plateau, the circle of Sikasso and the Upper Niger Valley.

3.1.3 Animal resources

Animal resources represent an essential source of protein intake. The evolution of bioclimatic conditions has influenced the distribution of livestock, particularly cattle, at the national level. As a result of the drought, part of the livestock from the northern pastoral zones is now found in the Sudanese and Sudano-Guinean agricultural zones.

Table 9 below gives the distribution of livestock in 1995.

Table 9: Number of national livestock by region in 1995*

Species

Regions

 Cattle Sheep goats Equine Assins Camelin Pigs
 Kayes  865.150  364.325  577,000  38,400  72.290  70 -
 Koulikoro  799.300  493.730  681,800  17,200  67,400  180  520.100
 Sikasso  1,123,750  472.911  423.200  1,700  51,700  -  12.051
 Segou  836.400  804.101  1,130,500  25,900  99.100  160  46,500
 Mopti  1,280,000  1,274,736  1,877,900  21,900  123,700  5.040  210
 Timbuktu  524.250  1,058,898  1.954.00  2,470  120.850  99,000  -
 Gao  268.110  928,000  1,100,000  520.070  88.890  189.551  -
 DistrictBamako  11,040  14,300  2,600  359  1.069  -  140
 Total  5,708,000  5.430.99 7,748,000   119.999  624.999  292.001  63,000

 Source: DNE - Report 1995.

Meat production, which was estimated at 168,000 t in 1997 (FAO), is provided by cattle (51%), small ruminants (32%), poultry (15%) and pigs (2%) (TRAORE Ng et al, 1999). These production levels should encourage us to direct more efforts towards the intensification of production.

Milk production is ensured essentially by traditional breeding: 139,000 tonnes (FAO statistics, 1997) and constitutes the basis of the diet of the populations in the breeding regions of the north. This production varies from one season to another, depending on the quantity and quality of fodder resources on the one hand and the availability of drinking water on the other.

The Mopti region remains the 1st breeding region with 22.42% of the cattle herd; it is followed by Sikasso (19.6%), Kayes (15.5%) and Ségou (14.6%). The large traditional breeding regions such as Timbuktu and Gao no longer even reach 10% of cattle each; but harbor 19.50% and 17.09% of sheep; 25.22% and 14.20% of goats; and 33.90 and 64.91% of camels respectively for Timbuktu and Gao.

In peri-urban areas, more or less intensive livestock farming is developing using mixed breeds of local and foreign breeds and improved and continuous feeding techniques. These farms are a significant source of milk supply for urban populations. Their development depends on the expansion of the urban market, in terms of population growth and improved incomes.

3.1.4 Fish resources

Annual fish production varies between 50,000 and 160,000 tons from year to year. More than 80% of the products come from the Central Niger Delta. Annual consumption is 10 kg per inhabitant (Breuil and Quenseère, 1995). This average is low in view of the potential and mastery of fishing techniques by Malians.

3.1.5 Wildlife resources

The varied and diversified wildlife resources constitute an important source of protein. They contribute more than 80% of animal protein consumption in certain southern rural areas (Sikasso region and southern Kayes and Koulikoro regions).

3.2 FORAGE RESOURCES

Generally speaking, fodder resources consist of herbaceous plants (in particular grasses) and ligneous plants. The production of the herbaceous cover varies from 0.5 t DM/ha/year in the northern Sahelian zone to 2.4 t DM/ha/year in the northern Sudanian zone.

Among the most palatable herbaceous species are: Cenchrus biflorus, Cenchrus ciliaris, Schoenefeldia gracilis, Andropogon gayanus, Echinochloa stagnina, Eragrostis tremula, Aristida spp .

Woody fodder represents a non-negligible part of the resources, especially in the dry season when the dried grasses have a low nutritional value (Touré, 1992). The main fodder trees are: Pterocarpus erinaceus, Pterocarpus lucens, Acacia albida, Balanites aegyptiaca, Acacia seyal . The production of the ligneous stratum varies from 0.2 t DM/ha with a nitrogen content of 18.2 g/kg in the northern Sahelian zone to 1.2 t DM/ha with a nitrogen content of 15.4 g/ kg in the northern Sudanian zone. Around urban centres, certain ligneous species contribute to the food of the animals in the hut. In Bamako, for example, four species are concerned: Pterocarpus erinaceus, Pterocarpus lucens, Pterocarpus santalinoides and Afzelia africana. The average quantities exploited per day by "gatherer-trader" have been evaluated at 47 - 69 kg of fresh matter, or approximately 1.357 tonnes of fresh Pterocarpus erinaceus fodder per year (Ayuk et al., 1998).

Certain cultivated plants (cowpea, groundnut, cowpea and voandzou) play an important role in animal feed. Their seeds and tops have a high nitrogen content.

3.3 ENERGY SOURCES

The energy needs of the Malian population are more than 90% covered by wood and charcoal which come from natural formations, old fallow land, agro-forestry parks and very rarely from plantations. Daily consumption is estimated at 1.5 kg/person, i.e. an annual national consumption of 5 million tonnes in 1995.

Overall, the accessible production potential currently covers this need. The productivity of the different natural formations varies from 0.3 to 0.4 m 3 /ha/year in the Sahelian zones, from 0.5 to 1m 3 /ha/year in the Sudanian zones and from 1 to 2 m 3 /ha /year in the Guinean zone. Production, which varies from region to region, is given in Table 10 below:

Table 10: Forest capital of Mali

REGIONS

 

Area of ​​formations

(1000 hectares)

Total wood volume

(1000 m 3 )
 Kayes  10,885.2  184,730.2
 Koulikoro  7,050.9  100,543.2
 Sikasso  5,637.7  149,077.4
 

Segou

  8,003.5  52,112.1
 Mopti  4,449.3  34,318.1
 Total  36,026.6  520 781

 Source: DNEF/Timber Resources Inventory Project, 1992

3.4 USE IN TRADITIONAL PHARMACOPEIA

All parts of plants and animals are used in pharmacopoeia. It can be leaves, bark, flowers, roots or the whole plant for plants; of skin, fat, horns, flesh for animals. Efforts are currently being made for a scientific exploitation of the potential of plants in the production of medicines and the health coverage of populations.

3.4.1 Plants

The vast majority of the population, not only in rural areas, but also in urban areas, is treated with medicinal plants. Most plant species, both woody and herbaceous, are used as medicines. A widespread belief is that all plants heal.

Plant substances are used not only in human medicine (Box 5) but also in veterinary medicine. Abundant documentation already exists on the use of plants in medicine. In addition to the work carried out by the Traditional Medicine Division of the INRSP, many studies have been carried out in the form of end-of-study dissertations by students from the Ecole Normale Supérieure and their professors or doctoral theses in medicine. by students from the Faculty of Medicine, Pharmacy and Odonto-Stomatology of Bamako.

Box 5: PLANTS THAT HEAL

The Traditional Medicine Division of the INRSP has developed from plants: malarial for the treatment of malaria ( Lippia chevalieri, Spilanthes oleracea and Cassia occidentalis ), hepatisane for certain liver diseases ( Combretum micranthum ), Balembo syrup for the treatment of cough ( Crossopteryx febrifuga ), diabetisane against diabetes ( Sclerocarya birrea ), to name but a few.

 Pharmacodynamic analysis showed that Kita quinqueliba is a hypotensor (leaf decoction). A leaf decoction is also used as a diuretic. The bark of Acacia albida is used as an anti-emetic and against pneumonia. Arabic gum ( Acacia senegal ) finds several uses in the pharmaceutical industry (preparation of syrup, lozenges, etc.).

 Saving useful plants for medicine is one of the major short-, medium- and long-term objectives of the preservation of biological diversity. This aspect of conservation has not been sufficiently taken into account until now, while several medicinal species are threatened with extinction because of their overexploitation. These include Vepris heterophylla, Lippia chevalieri, Crossopteryx febrifuga and Nauclea latifolia .

 3.4.2 Animals

Wildlife products are therapeutic items. The results of IUCN studies (1990) revealed that 8% of wildlife products in Mali enter traditional therapeutic practice.

At the level of the traditional healers of Bamako, 37 common diseases are treated by organs of 26 animal species. As examples, the powder of the ivory of the elephant would cure rheumatisms, its skin certain dermatoses, the extracts of placenta would cure female sterility and difficult childbirths and the sperm would cure male sterility. Hyena fat is said to be used against ear infections and its meat against blindness. Python meat would cure certain forms of jaundice.

Although fully protected, the manatee ( Trichecus senegalensis ) is used in traditional medicine. Given the rarity of the species, this form of exploitation is a threat to its survival.

3.5 SOURCES OF RAW MATERIALS FOR INDUSTRY AND CRAFTS

Certain biological resources have played an important role in the development of Mali's young industry. Groundnuts, whose production is 81,927 tons/year, are exploited for the manufacture of oil and soap. Cotton, whose production reached 500,000 tons in 1998, is used in the textile industry and the by-products are used to make soap, oil and animal feed.

A large fringe of craftsmanship lives from the exploitation of ligneous resources: wood (furniture, sculpture, musical instruments, etc.). The stems of the ronier ( Borassus aethiopium) and the doumier ( Hyphaena thebaica ), rot-proof and resistant to attack by insects, are used as beams, rafters, slats and in the manufacture of small boats. The wood of Acacia albida , Khaya senegalensis is used to make mortars, pestles, handles of agricultural and musical instruments, etc. The hardwoods of Balanites aegytiaca, Pterocarpus erinaceus, Dalbergia melanoxylon, Acacia albida are exploited in carpentry and local cabinetmaking.

The leaves and bark of Anogeissus leocarpus, Terminalia spp. are used as raw materials in the local dyehouse (bogolan) and the fruits of Acacia scorpioides variety nilotica in the tannery. The leaves of Hyphaenae thebaica and Borassus aethiopium are used in the manufacture of many basketry objects and the making of ropes and mats.

The rhizomes of vetiver and the bark of certain species serve as a deodorant and for settling water. Gum arabic is used in confectionery and in the glue and shoe polish manufacturing industry. Shea and wild dates provide fats used in the manufacture of soap, chocolate and cosmetics.

3.6 CULTURAL AND TOURIST SUPPORT

In addition to their food, medicinal, industrial and artisanal importance, biological resources fulfill cultural functions in Malian society and play a major role in the development of tourism.

It is common to find in regions where animism is still a living religion, "sacred woods", shreds of forests more or less well preserved, defended by various "prohibitions". These groves can be visual and educational examples of what natural plant formations could be without the destructive actions of man. They are safe havens for certain rare plant species.

In regions where Islam is the dominant religion, it is not uncommon to find cemeteries which are the only places where a sample of the original vegetation (even more or less altered) can be observed with species that have become rare elsewhere. . In terms of the protection of rangelands and pastures, the rules of the Dinna are still respected in the Central Niger Delta. The rules for the protection of Acacia albida , a species that fertilizes fields, were very strict (IUCN, 1995).

Several species are venerated and therefore protected by the populations. This is the case, for example, of Adansonia digitata and Acacia albida in the western and central regions of the country. Other species are subject to ritual practices. This is the case, for example, of pastoralists when they find themselves alone in the bush and wish to meet people, cut a few leaves of Boscia senegalensis and carry them, preferably on their heads. These same shepherds, to rest in the shade of Balanites aegyptiaca without danger to their lives, tear off seven leaves or thorns from it, which they throw aside.

Bien que ces pratiques coutumières et animistes jouent un rôle important dans la protection des ressources biologiques, elles sont en train de disparaître. Cette disparition s'explique principalement par la forte présence de l'islam, la sédentarisation et la monétarisation de l'économie.