Prins, H.H.T. 1992. The pastoral road to
extinction: Competition between wildlife
and traditional pastoralism in East Africa.
Environ. Conserv. 71:107-110.

Pritchard, J.M. 1979. Africa: A study of
geography for advanced students. 3rd ed.
Longman, London.

Pullin, A. 2004. Conservation biology.
Cambridge Univ. Press, UK.

Rachmeler, D. 2003. Trip report: Water
hyacinth infestation at the Inga dam,
Bas Congo, DRC. Innovative Resource
Manage., Washington DC.

Raup, D.M., and J.J. Sepkosky. 1984.
Periodicity of extinction in the geological
past. PNAS 81:801-805.

Raven, P.H. 1987. We are killing our world.
Pres. Conf. AAAS. Chicago. Feb 1987.
Missouri Bot. Garden, St. Louis.

Reid, R.S., and J.E. Ellis. 1995.
Livestock-mediated tree regeneration:
Impacts of pastoralists on dry tropical
woodlands. Ecol. Appl. 5:978-992.

Reij, C. 1996. Evolution et impacts des
techniques de conservation des eaux et des
sols. (In French). Centre for Development
Cooperation Services, Vrije Univeriseit,
Amsterdam.

Reilly, B.K., E.A. Sutherland, and V. Harley.
2003. The nature and extent of wildlife
ranching in Gauteng province, South Africa.
S. Afr. J. Wildlife Res. 32(2):141-144.

Riise, J.C., A. Permin, and K.N. Kryger. 2005.
Strategies for developing family poultry
production at village level: Experiences
from West Africa and Asia. World Poul. Sci.
J. 61:15-22.

Roberts, T.R. 1975. Geographical distribution
of African freshwater fishes. Zool. J. Linn.
Soc. 57:249-319.

Roose, E. 1994. Introduction à la gestion
conservatoire de l’eau, de la biomasse et de
la fertilité des sols (GCES). (In French). Bull.
70. FAO, Rome.

Ruthenberg, H. 1980. Farming systems in the
tropics. Clarendon Press, UK.

Saito, K., and C.J. Weidemann. 1990.
Agricultural extension for women farmers
in Africa. Disc. Pap. 103. World Bank,
Washington DC.

Saito, K., and D. Spurling, and W. Zijp. 1992.
Designing and implementing agricultural
extension for women farmers. Tech. notes.
World Bank, Washington DC.

Sakaguchi, M., H. Nakamura, K. Sonoda,
F. Hamada, and K. Hirai. 1996. Protection
of chicken from Newcastle disease by
vaccination with a kinear plasmid DNA
expressing the F protein of Newcastle
disease virus. Vaccine 14:747-752.

Sanchez, P.A., K.D. Shepherd, M.J. Soule,
F.M. Place, R.J. Buresh, and A-M. Izac.
1997. Soil fertility replenishment in Africa:
An investment in natural resource capital.
p. 1-46. In R.J. Buresh et al. (ed)
Replenishing soil fertility in Africa. Soil Sci.
Soc. Am. Spec. Publ. 51. Madison WI.

Sanders, J.H., B.I. Shapiro and S. Ramaswamy.
1996. The economics of agricultural
technology development in sub-Saharan Africa.
John Hopkins Univ. Press, Baltimore MD.

Sandford, S. 1983. Management of pastoral
development in the third world. John Wiley,
UK.

Schilling, R., and S.M. Misari. 1992.
Assessment of research achievements in the
savanna regions of West Africa. p. 97-112.
In Groundnut: A global perspective. Proc.
Int. Workshop, Patancheru, India. 25-29
Nov. 1991. ICRISAT, Niamey.

Scoones, I. 1989. Economic and ecological
carrying capacity: Implications for livestock
development in Zimbabwe’s communal
areas. Pastoral Dev. Network Pap. 27b.
ODI, London.

Scoones, I. 1992. Coping with drought: Responses
of herders and livestock in contrasting
savanna environments in southern Zimbabwe.
Human Ecol. 20:293-314.

Scoones, I. 1995. Exploiting heterogeneity:
Habitat use by cattle in the communal areas
of Zimbabwe. J. Arid Environ. 29:221-237.

Sere, C., and H. Steinfeld. 1996. World
livestock productions systems: Current
status, issues and trends. Anim. Prod.
Health Pap. 127. FAO, Rome.

Shapiro, B. 1994. Nutrition effects of crossbred
cow adoption in Debre Berhan. ILCA,
Addis Ababa.

Sharma, H.C., and K.F. Nwanze. 1997. Insect
pests of sorghum: Biology, extent of losses
and economic threshold. p. 9-23. In
H.C. Sharma et al. (ed) Plant resistance to
insects in sorghum. ICRISAT, India.

Shumway, C.A., D. Musibono, S. Ifuta,
J. Sullivan, R. Schelly, J. Punga et al. 2002.
Biodiversity survey: Systematics, ecology
and conservation along the Congo River.
Res. Report. USAID, Washington DC.

Simons, A.J., and R.R.B. Leakey. 2004. Tree
domestication in tropical agroforestry.
Agrofor. Syst. 61:167-181.

Sindiga, I., N. Chacha, and M.P. Kanunah (ed)
1995. Traditional medicine in Africa. East
African Educ. Publ., Nairobi.

Singh, S.R., L.E.N. Jackai, G. Thotthapilly,
K.F. Cardwell, and G.O. Myers. 1992.
Status of research on constraints to cowpea
production. p. 21-26. Biotechnology:
Enhancing research on tropical crops in
Africa. CTA. IITA, Ibadan.

Singh, B.B., and H.A. Ajeigbe. 2002. Improving
cowpea-cereals based cropping systems in
the dry savannas of West Africa p. 278-286.
In C.A. Fatokun et al. (ed) Challenges and
opportunities for enhancing sustainable
cowpea production. IITA, Ibadan.

Skonhoft, A. 1998. Resource utilization,
property rights and welfare: Wildlife and
the local people. Ecol. Econ. 26(1):67-80.
Skonhoft, A., and J.T. Solstad. 1998. Investing
in wildlife pay its way? J. Afr. Econ.
7:237-262.

Smale, M., and P.W. Heisey. 1994. Maize

research in Malawi revisited: An emerging
success story? J. Int. Dev. 6:689-706.

Smaling, E.M.A., S.M. Nandwa, and
B.H. Janssen. 1997. Soil fertility in Africa is
at stake. R.J. Buresh et al. (ed) Replenishing
soil fertility in Africa. Soil Sci. Soc. Am.
Spec. Publ. 51. Madison WI.

Spencer, D.C.S., P.J. Matlon, and H. Loffler.
2004. African agricultural production and
productivity in perspective. Background
Pap. 1: Study panel on science and
technology strategies for improving
agricultural productivity and food security
in Africa. IAC, Netherlands.

Staal, S.J., M. Owango, H. Muriuki,
M. Kenyanjui, D. Njubi, F. Musembi et al.
2001. Dairy systems characterization of the
Nairobi milk shed: Application of spatial
and household analysis. KARI, MoARD,
ILRI, Nairobi.

Steiner, K.G. 1996. Causes of soil degradation
and development approaches to sustainable
soil management. Margraf Verlag Publ.,
Germany.

Sterner, T. 2003. Policy instrument for
environmental and natural resource
management. Resources for the Future,
Washington DC.

Stiassny, M.L.J. 1996. An overview of
freshwater biodiversity with some lessons
from African fishFisheries 21(9):7-13.

Stocking, M. 1985. Soil conservation policy in
colonial Africa. Agric. Hist. 59:148-161.

Stoorvogel J.J., and E.M.A. Smaling. 1990.
Assessment of soil nutrient depletion in
sub-Saharan Africa: 1983–2000. Vols. 1-4.
Winand Staring Centre, Wageningen.

Swift, J. 1988.Major issues in pastoral
development with special emphasis on
selected African countries. FAO, Rome.

Swift, J. 1996. Sustainable management of the
soil resources: Developing a framework for
research and development. World Bank,
Washington DC.

Thibault, M., and S. Balney. 2003. The oil
Industry as an underlying factor in the
bushmeat crisis in central Africa. Conserv.
Biol. 17(6):1807-1813.

Tiffen, M., M. Mortimore, and F. Gichuki.
1994. More people, less erosion:
Environmental recovery in Kenya. John
Wiley, Chichester.

Ton, P., S. Tovignan, and S.D. Vodouhe. 2000.
Endosulfan deaths and poisonings in Benin.
Pesticides News 47:12-14. Pesticide Action
Network, UK.

Twongo, T. 1995. Impact of fish species
introductions on the tilapias of Lakes
Victoria and Kyoga. p. 45-57. T.J. Pitcher,
and P.J.B. Hart (ed) The impacts of species
changes in African lakes. Fish Fisheries Ser.
18. Chapman and Hall, UK.

Ukeje, E. 2004. Modernizing small holder
agriculture to ensure food security and
gender empowerment. Available at http://
www.g24.org/ukeje.pdf. Intergov. Group of
Twenty-Four. Washington DC.