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Water and agroforestry chin (nxpowerlite)

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  • 1. Water and Agroforestry ICRISAT Center, Patancheru, India, 1985 Chin Ong, 29 June 2007
  • 2. ICRAF’s research on water,1991-2007
    • Past, present and future issues
    • Machakos (‘Mecca’ for land recovery & agroforestry)
    • Challenges of more trees & climate change
    Upper Mbeere Machakos Thika Source: Anyango, 2005 Thika 2000 1986
  • 3. More people, less erosion Tiffin & Gichuki,1997 Machakos, 1991 Machakos, 2006
  • 4. More people, more trees Embu, 1997
  • 5. Majjia Valley,Niger, 1975-2002 Source: C. Reij More rain or more soil conservation?
  • 6.
    • More adoption of water harvesting
    • Increase in dry season cultivation
    • Higher incomes
    • Improved nutrition
    • More firewood
    • More fodder
    • Less time fetching water
    Impacts of land recovery in Niger & Machakos Quickbird image of Lare, Nakuru District, 2006 Malesu et al. 2006
  • 7. Machakos, 1991-2000 Hypothesis: Trees can capture and use resources more efficiently than crops
  • 8. Machakos Research, 1985-1992 Strong focus on alley cropping and erosion However, large plots indicate little or no improvement in crop yields. Controls plots invaded by tree roots. (Ayeampong et al. 1995) 1991 1991
  • 9. Microclimate improvements Hypothesis: Improvements in microclimate lower soil evaporation & promote hydraulic lift. Maturity delayed by 2 weeks due to lower temp (-4C). Soil water benefit is not as important. Climate change benefits? Ong et al. 2000. Agric. Ecosyst. Environ. 80: 121-145 1993 1995
  • 10. Shade benefit on coffee? Which tree species?
  • 11. Shade benefit on tea? Which tree species?
  • 12. Complementarity in water uptake Focus attention on Grevillea robusta -maize in different arrangements Hypothesis: Deep roots of grevillea is highly compatible with maize. Howard et al. 1997. Agrofor Sys. 35: 15-29 1992 1995
  • 13. Fast-growing trees & competition RAC: Root studies of fast-growing trees Is the answer below-ground? Ong et al, 2002. Agr. Water Manag. 53: 171-186 1997 1997
  • 14. Fractal index & root studies Fractal index = ratio of lateral vs vertical roots Index determined for a range of species. How useful? Ong et al.1999. Agrofor.Syst.44: 87-103 1994 1996
  • 15. Water balance Total transpiration by sole maize was only 50% rainfall 85% by agroforestry systems, including 25 % during the dry season Lott et al . 2003. For. Ecol. Mange 180: 45-59 1996 1996
  • 16. Long-term consequences of different resource capture strategies? Cautious spender: deciduous & lateral rooting Big spender: evergreen & deep rooting Grevillea, 15 yr Melia volkensii, 13 yr July 2006 Machakos, July 2006
  • 17. Comparison of deciduous & evergreen trees Melia volkensii , Machakos, 1997 Paulownia fortunei , Naro Moro, 2001
  • 18. Land use change & stream flow Loss of watershed function of the Mau Complex Evidence? Sondu-Miriu hydropower plant
  • 19. Mau Forest Change 1973 - 2005
    • Key areas of deforestation include:
    • Eastern Mau
    • Western Mau
    • Masai Mau
    Lowery, 2005
  • 20. Stream flow of Nyando River Long term river flow is 4% of annual rainfall ( Sang, 2007)
  • 21. More erosive rain is predicted for Lake Victoria Basin! Quickbird, Katuk Odeyo, 2004 Katuk Odeyo, 1998 Source : Meshak
  • 22. Green-blue water globally Source: SEI
  • 23. Green and blue water fluxes in Kenya Source: SEI
  • 24. Eucalyptus: an ecological time-bomb?
    • Millions of eucalyptus were planted in Mau & Central Kenya.
    • What will be the ecological impacts?
    • Promoted by Forest Department & for Carbon Trade by TIST.
    • 250m 3 of water for one ton of carbon!
    1 year old eucalyptus uses 30 litres of water per day! Juja 2007 Sap flow equipment for water uptake grevillea
  • 25. Map of Eucalyptus Impact on Streamflow in South Africa Source: Mark Gush,2005
  • 26. More trees with less water? Naro Moro: Muthuri et al. 2004
  • 27. Lessons & challenges for ICRAF
    • Predicted changes in land use & climate will have serious impacts on water supply & erosion
    • Strong tradeoffs with carbon credits: which profitable trees to plant without loss of ecosystem services?
    • Machakos lessons: long-term evidence is needed, reserve water for ecosystem functions.
    • Make science more meaningful to policy makers e.g. eucalyptus, bioenergy & water
    • Connecting upstream & downstream, combining land management across scales e.g. Green blue water initiative with Stockholm Environment Institute on Lake Victoria Basin
    • Where are the future Machakos?
    De Wit 2006
  • 28. Acknowledgements
    • Contributions & dedication of countless
    • students & technicians.
    • Partners: Nottingham, Bangor, Dundee,
    • JKUAT, IH, UWA, Sokoine, Cornell, Florida
    • Donors: DFID, Sida, ACU, DAAD, BMZ
    • ICRAF: Peter Huxley, Tony Young
    • Meka Rao, Ahmed Khan
    • RELMA team
  • 29. The future is bamboo For zero carbon footprints! Economy class Club class