The document discusses research conducted by ICRAF on water and agroforestry from 1991-2007. It focuses on several key areas: 1) Studies in Machakos, Kenya showing that integrating trees with crops can improve soil and water conservation compared to crops alone. 2) Research on how tree roots capture water and influence microclimates to benefit crops. Studies looked at different tree species and arrangements. 3) Long-term consequences of different tree resource capture strategies, including deciduous vs evergreen species. 4) Evidence that deforestation of areas like the Mau Forest Complex in Kenya can negatively impact streamflow. More erosive rains are also predicted.

1. Water and Agroforestry ICRISAT Center, Patancheru, India, 1985 Chin Ong, 29 June 2007

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?

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

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

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

29. The future is bamboo For zero carbon footprints! Economy class Club class