E.I. Warrag52, E. A. Elsheiksh53 and A. A. Elfeel54
Conservation of forest genetic resources in Sudan at national level is complex due to the size of the country, species diversity, large variation in climatic conditions and institutional awareness of needs and priorities. Few activities are directed for saving gene pools for present and future use. Silvicultural practices, management, laws and policies are targeted for use and conservation of the forestry resources, resulting in "conservation in use" for the forest genetic resources.
The country (about 2.5 m sq km) lies entirely in the subtropical arid zone of Africa. Seven vegetation zones are recognized according to rainfall, from 0 mm in the north to 1500 mm in the south, and there is a wide range of soil types (Harrison and Jackson 1958). It is rich with natural populations of more than 100 tree species. Large variation exists between and within species due to the variation in rainfall and soil types (Hussein 1993, Elfeel 1995, Yahia 1997). Major and sub- genecological zones were delineated by Aalb_k and Kananji (1995) for use by the National Tree Seed centre (NTSC) as seed collection zones.
There have been few planned management interventions in Sudan's forests but there has been widespread influence of human activity. In limited areas many exotic species were introduced and established from the 1950s, Eucalyptus camaldulensis and Eucalyptus microtheca were planted in connection with irrigated agricultural schemes. Five Morus species were introduced in 1995 for silk production. Prosopis species were introduced as suitable for the arid conditions and Prosopis chilensis was considered a priority species in the 1991 by the NTSC. The species has, however, spread to agricultural lands where it is considered a weed, and measures have been taken for eradication.
Forests range from savanna woodland of annual rainfall of about 400 mm to tropical high rainfall forest in the southern mountains with desert and semi-desert in the northern parts of the country and closed high forests in the very southern parts55. The arid northern parts of the country have scattered vegetation; woody species are limited to a few species of Acacia in the seasonally flooded areas. The central part of the country with a rainy season of 3-5 months is dominated by deciduous drought tolerant tree species. The influence of the soil type is marked. E.g. Acacia senegal is found in areas with a rainfall of 400 mm in sandy soils, while it requires 600 mm in heavy clay soils areas. In the lower rainfall savanna the main species currently utilized are Acacia senegal and Acacia nilotica of the riverine forests. Other important species are Anogeissus leiocarpus, Terminalia spp. Combretum spp, Bowswelia spp, and some palms mainly Hyphaene and Borassus spp. The higher rainfall savanna areas contain more valuable tree species, with potential of producing sawn timber.
The important species grouped according to product produced, were listed by Warrag et al. (1998). The woody products are fuelwood, sawn timber and round poles. About 100 species were reported to produce non-woody products (Badi, 1993). These range from honey bees keeping, fibre, food, fodder, medicinal materials, dyes to tannins. Forest trees also provide many service functions, such as the stabilization of sand dunes in the semi-desert region, improvement of soil fertility, provision of habitats for wildlife and the conservation of biodiversity. The most important species listed were:
1) Acacia senegal:
produces gum Arabic and fuelwood, acts as a fallow crop and stabilizes sand
2) Acacia nilotica: produces sawn timber and tannins,
3) Acacia seyal: produces fuelwood and gum,
4) Eucalyptus camaldulensis: Fast growing exotic species used for the production of shelter, fuelwood and poles, grown in blocks irrigated agricultural schemes.
Threats to tree species and consequently to forest genetic resources are related to:
A) human factors
1. conversion of natural forests to plantations of
exotic tree species and
2. lack of management of natural forest and woodlands, regulated and unregulated cutting for timber and fuelwood,
3. extensive clearing for large scale mechanized farming operation,
4. over grazing of livestock,
6. civil wars;
B) non-human factors;
1. drought, The drought experienced in Sudan
during the eighties affected tree species especially in the low rainfall
savannah areas and the arid zones.
2. natural fires, and
Tree vegetation has declined in the past century and has now reached to around 17 percent forest land plus an additional 10 percent as other wooded land in the year 2000 with an annual change of -1.4 percent (= 960 000 ha/year) between 1990 and 2000 (FAO 2000).
The following species are declared endangered by the Ministry of Agriculture: Balanites aegyptiaca; 2) Commiphora africana; 3) Dablergia melanoxylon; 4) Hyphaene thebaica; 5) Salvadora persica; 6) Sclerocarya birrea; and 7) Sterculia setigera.
Laws for conservation were in-acted since 1901, 1908 and 1917 with reservation of 15 percent of the country as forest. The 1986 policy raised the goal of forest reserves to 20 percent of the country area. The 1997 policy influenced by national changes and the international agreements calls for: a) assigning 25 percent of the country to natural resources mainly forestry, b) limited felling and use of trees for domestic products to the areas where regeneration is assured, c) replanting according to needs, d) limiting the local people rights and privileges from the reserved forests and to promote private, communal and rural forest. Several directives were issued to ban the cutting of tree species that are endangered or requiring some special attention. In 2001 a ministerial decrees was issued that ban the expansion of mechanized farms and felling of trees outside the reserved forest.
Forest legislation also regulates tree cutting outside forest reserves with the objective to avoid felling to inside the forest reserves. These measures are expected to reduce the pressure on natural stands and consequently help in conserving genetic resources. Native and tribal administrations are using their own methods for tree conservation.
The laws, policies and activities are directed towards conservation of the forest resources and indirectly resulting in genetic conservation at the ecosystem, species and geographical sources. The forest genetic resources are mostly conserved in national parks, natural stands and plantations.
The gazetted forest reserves covered 1 278 000 ha by 1979, distributed as: 167 000 ha in the semi-desert, 547 000 in the low rainfall woodland savannah and 564 000 in the high rainfall woodland savannah. The reserved area was increased substantially after 1993 (following the Convention on Biological Diversity) to reach 8 million ha (2.8 percent of the country area) distributed in the different vegetation zones. Due to the control cuttings of trees and replanting using bulk seeds from natural stands, the genetic resources are reasonably conserved.
Protection of endangered tree species
Ministerial decrees are in place that ban the removal or cutting of any declared endangered forest tree species.
National parks contribute significantly to the conservation of genetic resources especially in the savanna woodlands as felling of trees is prohibited there. Eight national parks "Bioreserves" exclusively for wildlife are distributed in the different vegetation zones with a total area of 8.5 million ha.
Reforestation and afforestation programs use bulk seed collected from natural stands. The annual consumption of seed through the organized channels is about 50 tons and expected to increase. The top priority species accounts for most of the demand as Acacia senegal constitute about 30 percent of the present seed use (15 tons), followed by Acacia seyal, Acacia nilotica, Acacia tortilis, Acacia mellifera, Balanities aegyptiaca and other species (mostly exotics) with a use of 12.7, 12.2, 6.0, 2.9, 0.2 and 0.5 tons respectively. The exotic species account for less than 10 percent of the present use.
The NTSC has identified and demarcated 79 sources for important species with a total area of about 6oo ha scattered in the country. However due to lack of funds these sources are not well managed for seed production
Little efforts are directed towards this end due to its high cost. Research in the storage of tree seed are currently investigated.
Besides exotics, mainly Eucalyptus species, which were first introduced in 1915, little efforts were made in tree improvement. A few attempts were made to select high gum yielder trees of Acacia senegal in 1967 from the gum belt areas and planting their progenies in a progeny test in western Sudan. In 1984 two provenance trials were established with 15 provenances of Acacia nilotica and one provenance each of A. seyal and Eucalyptus microthera and another trial with five provenances of Acacia tortilis plus one provenance each of A. albida, A. seyal and Prosopis chilensis as part of the "International Series of Trials of Arid and Semi-Arid Zone Arboreal Species", a program coordinated by FAO in collaboration with international and national partners, in which seed was collected and species and provenance trials were established in a number of countries in arid and semi-arid areas in Africa, Asia and South America. (anon., 1988; Raebild, A. and Graudal, L. in prep. a and b).
Future efforts should start by planning for the conservation of the priority species and the endangered ones and then implementation of conservational plans. This requires inter-country collaboration especially in view of the uniqueness of the vulnerable dry land zone and that the important and endangered species are shared in the Sahelian and North - Sudanian Africa (FAO 2001). The NTSC requires financial and professional support to advance this work and to be able to provide improved seeds while maintaining the genetic variability of the forest genetic resources.
Aalb_k, A., and Kananji, B. 1995. Tree seed zones for Sudan. NTSC publication No. 6.
Abdel Rahman Gorashi. 2001. State of Forest Genetic Resources in Sudan. Prepared for the sub-regional workshop FAO/IPGRI/ICRAF on conservation, management, sustainable utilization and enhancement of forest genetic resources in Sahelian and North-Sudanian Africa (Ouagadougou, 22-24 September. 1998). FAO Forest Genetic Resources Working Papers, Working Paper FGR/20E. Forest Resources Division. FAO, Rome (unpublished).
Abdelnour, H.O., Abdelmagid, T.D. (1997): The Human activities in the Sudan during the 20th century and its effect on the forests of the Sudan.
Anon.. 1988. Final Statement on the FAO/IBPGR/UNEP Project on Genetic Resources of Arid and Semi-Arid Zone Arboreal Species for the Improvement of Rural Living, 1979-1987. Forest Genetic Resources Information, No. 16. pp 2-8.
Badi, K.H. 1993. Study on consumption of forest products: an exhaustive list of forest species bearing non-wood forest products. GCP/SUD/049/NET, Khartoum, Sudan.
Elfeel, A.A.1996: Provenance variation in seed characteristics, germination and early seedlings growth traits of Acacia senegal in Sudan. M.Sc. thesis, University of Khartoum.
FAO 2000. Global Forest Resources Assessment 2000. Main report. FAO Forestry paper 140.
FAO 2001. State of Forest Genetic Resources in the Sahelian and North-Sudanian Africa & Regional Action Plan for their conservation and Sustainable Use. Forest Genetic Resources Working papers, Working paper No.2.
Glowka, L., Burhenne-Guilmin, F., Synge, H., Mcneelly J.A., Gündling,L. 1994: A Guide to the Convention on Biological Diversity. Environmental Policy and Law Paper No. 30. IUCN Environmental Law centre and Biodiversity programme.
Harrison M.N., and Jackson, J.K. (1958). Ecological classification of the vegetation of the Sudan. Forest Bulletin No.2.
Hussein, K. A., 1994: Genetic variation in growth traits between location, gum production and families of Acacia senegal (L.) Willd. seedlings from northern Kordofan, Sudan. M.Sc. Thesis, University of Khartoum.
Rębild, A. & Graudal, L. (in prep.a): Evaluation of an Acacia nilotica provenance trial at Khor Donia, Sudan. Trial no. 25 in the Arid Zone Series. Danida Forest Seed Centre.
Rębild, A. & Graudal, L. (in prep.b): Evaluation of an Acacia tortilis provenance trial at Khor Donia, Sudan. Trial no. 26 in the Arid Zone Series. Danida Forest Seed Centre.
Yahia, B. O. 1997. Genetic variation in seed parameters, germination, and early seedling growth traits of Acacia melifera at the provenance and individual levels. M.Sc. thesis, University of Khartoum.
Warrag, E.I, A.G. Elmahi, A. M. Ibrahim, E.A. Elsheiksh 1998: Status of forest genetic resources in the Sudan. October, 1998.
51 Received June 2002. Original language:
52 Faculty of Forestry, University of Khartoum
53 National Tree Seed Centre
54 Faculty of Forestry and Range Sciences, Sudan University for Science and Technology
55 The forest cover was 61 627 000 ha in 2000 or 17% of the country (FAO, 2001).