Water And Agroforestry Chin (Nxpowerlite)

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Water And Agroforestry Chin (Nxpowerlite)

  1. 1. Water and Agroforestry Chin Ong, 29 June 2007 ICRISAT Center, Patancheru, India, 1985
  2. 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 1986 2000 Upper Mbeere Thika Thika Machakos Source: Anyango, 2005
  3. 3. More people, less erosion Tiffin & Gichuki,1997 Machakos, 1991 Machakos, 2006
  4. 4. More people, more trees Embu, 1997
  5. 5. Majjia Valley,Niger, 1975-2002 More rain or more soil conservation? Source: C. Reij
  6. 6. Impacts of land recovery in Niger & Machakos • More adoption of water harvesting • Increase in dry season cultivation • Higher incomes • Improved nutrition • More firewood • More fodder • Less time fetching water Quickbird image of Lare, Nakuru District, 2006 Malesu et al. 2006
  7. 7. Machakos, 1991-2000 Hypothesis: Trees can capture and use resources more efficiently than crops
  8. 8. Machakos Research, 1985-1992 1991 1991 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)
  9. 9. Microclimate improvements 1993 1995 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
  10. 10. Shade benefit on coffee? Which tree species?
  11. 11. Shade benefit on tea? Which tree species?
  12. 12. Complementarity in water uptake 1992 1995 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
  13. 13. Fast-growing trees & competition 1997 1997 RAC: Root studies of fast-growing trees Is the answer below-ground? Ong et al, 2002. Agr. Water Manag. 53: 171-186
  14. 14. Fractal index & root studies 1994 1996 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
  15. 15. Water balance 1996 1996 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
  16. 16. Long-term consequences of different resource capture strategies? July 2006 Melia volkensii, 13 yr Cautious spender: deciduous & lateral rooting Machakos, July 2006 Grevillea, 15 yr Big spender: evergreen & deep rooting
  17. 17. Comparison of deciduous & evergreen trees Melia volkensii, Machakos, 1997 Paulownia fortunei, Naro Moro, 2001
  18. 18. Land use change & stream flow Loss of watershed function of the Mau Complex Evidence? Sondu-Miriu hydropower plant
  19. 19. Mau Forest Change 1973 - 2005 Key areas of deforestation include:  Eastern Mau  Western Mau  Masai Mau Lowery, 2005
  20. 20. Stream flow of Nyando River Nyando, 1968-1991 1600 Cumulative streamflow (mm) 1400 1200 1000 800 600 400 200 0 0 5000 10000 15000 20000 25000 30000 35000 40000 Cumulative rainfall (mm) Long term river flow is 4% of annual rainfall ( Sang, 2007)
  21. 21. More erosive rain is predicted for Lake Victoria Basin! Katuk Odeyo, 1998 Quickbird, Katuk Odeyo, 2004 Source : Meshak
  22. 22. Green-blue water globally Source: SEI
  23. 23. Green and blue water fluxes in Kenya Source: SEI
  24. 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. • 250m3 of water for one ton of carbon! grevillea 1 year old eucalyptus uses 30 litres of water per day! Juja 2007 Sap flow equipment for water uptake
  25. 25. Map of Eucalyptus Impact on Streamflow in South Africa Source: Mark Gush,2005
  26. 26. More trees with less water? Naro Moro: Muthuri et al. 2004
  27. 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 De Wit 2006 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?
  28. 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. 29. The future is bamboo Economy class Club class For zero carbon footprints!

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