2. Outline
âą Introduction
âą Supporting services
âą Regulating services
âą Provisioning services
âą Processes
âą Experimental designs used
âą Scaling up
âą Concluding remarks
âą Unexplored and insufficiently explored areas
3. Reduced
vegetation
cover
o 9-month dry season
o Frequent droughts during the
rainy season
o High vulnerability to CV
o High vulnerability to CC
o Low inherent fertility
o Subsistence agriculture (85%)
o Food GR (2%)
o 19 million in 1960â to 50 by 2000
o High human pressure: 3% PGR
o High animal pressure
oReduced vegetal cover
oNutrient depletion
o Reduced SOM and CEC
o Reduced IC
o Increased runoff
o Reduced WHC
o Exacerbated competition for water
Introduction (1)
Some characteristics Some challenges
o High level of illiteracy
o High level of unemployment
o Low investment in agriculture
4. Introduction (2)
Parklands are generally made up of
several agroforestry species and genera
that constitute an important source of
medicine, food and nutrition
Parklands are anthropogenic vegetation
assemblages derived from savannas
ecosystems by farmers who select and
preserve naturally regenerated trees when
clearing the bush to make fields (Maranz,
2009)
5. Improving on-farm productivity of trees and agroforestry
systems requires a better understanding ofâŠ..
Roles and functions such as:
- Supporting services (soil formation, nutrient
cycling, primary productionâŠ);
- Regulating services (climate, diseases, water
regulationâŠ.);
- Provisioning services (food, fuel wood, âŠ);and
- Cultural services (recreational and ecotourism, âŠ).
Processes:
- Growth resources (light, water,
nutrients) sharing
Management options
- Species composition and density
- Pruning
- Associations
- Regeneration techniques
- etc.
Introduction (3)
6. Supporting services (1)
Relative contribution of trees and crops to soil carbon content in a parklan
system in Burkina Faso using variations in natural 13C abundance
J. Bayala, J. Balesdent, C. Marol, F. Zapata, Z. Teklehaimanot and S.J. Ouedraogo
Nutrient Cycling in Agroecosystems (2006) 76:193â201
9. Regulating services (3)
Hydraulic redistribution study in native tree species in an agroforestry parkland of
West African dry savanna
J. Bayala, L. K. Heng, M. van Noordwijk, S. J. Ouedraogo
Oecologia Plantarum (2008) 34: 370-378
12. Regulating services (6)
The simulations
are based on
sap flow
measurements
and on the
observed
relationship
between
drainage below
1.5 m soil depth
in 2009 and
distance to the
nearest tree in
an agroforestry
parkland,
Burkina Faso.
Spatial simulations of groundwater recharge in
relation to tree density and canopy cover
Field data from wick lysimeters revealed that subsurface drainage ranges from
1.3% in open to 16% at the edge of tree crown of the annual rainfall
23. âą Effect of 10 years cropping without
inorganic fertilizer and with sorghum
residues returning as mulch on sorghum
biomass and yield under current climate.
âą Effect of reducing and increasing tree
density (9, 16, 25, 36, and 49 trees per
hectare) in association with 20% and 50%
of tree leaf pruning
âą Effect of increase and decrease in the
amount of rainfall as well as changes in
rainfall pattern (occurrence of extreme
events)
âą Tree management as adaptation strategies
to climate change tested in simulating
changes of rainfall regimes were: tree
canopy growth dynamics, hydraulic
redistribution function with deeper and
surface root system.
Observations and simulations
Processes: Modeling (4)
24. Observations and simulations
âą Long cycle sorghum could be cultivated on a
long-term basis in agroforestry parklands without
providing any organic or inorganic fertilizers and
the sorghum performance will remain stable as
opposed to short cycle sorghum varieties
âą Under the current climate, increasing the tree
density does not negatively affect sorghum
growth if crown pruning is applied
âą Applying pruning can also be useful when
flooding occurs as a consequence of changing
climate as this operation will reduce shade due
to accelerated tree growth
âą Tree species with dynamic canopy and
performing hydraulic function with deep root
system are recommended both for flooding and
drought.
Processes: Modeling (5)
25. Overview of experimental designs used (1)
ï¶ Human mediated processes?
ï¶ Landscape level?
Models can help:
ï¶ For processes we know sufficiently well to
structure and parameterize them
ï¶ If they reveal what we do not know when
simulated and observed data disagree
27. Scaling up: CAWT in Sahel (1)
J. Bayala, A. Kalinganire, Z. Tchoundjeu, F. Sinclair, D. Garrity
ICRAF Occasional Paper No. 14.
28. Variation in mean difference in yield of cereal
crops with site productivity in four West
African Sahelian countries (Burkina Faso,
Mali, Niger and Senegal). Vertical bars
represent standard errors
Variation in mean difference in yield (across
cereal crops) with soil and water conservation
practices and site productivity in four West
African Sahelian countries (Burkina Faso, Mali,
Niger and Senegal). Vertical bars represent
standard errors
Site potential
Scaling up: factors affecting yield (2)
29. Rainfall
Practices (number of pairs) Rainfall class D (t ha-1) LCI UCI
Parkland (64) < 601 mm 0.36 0.06 0.65
601-800 mm 0.31 0.07 0.54
> 800 mm -0.05 -0.35 0.25
Coppicing (89) < 601 mm 0.43 0.09 0.77
601-800 mm -0.29 -0.75 0.17
> 800 mm 0.46 0.21 0.72
Green manure (48) < 601 mm - - -
601-800 mm -0.03 -1.0 0.95
> 800 mm 0.79 0.59 1.00
Mulching (89) < 601 mm 0.72 0.49 0.95
601-800 mm 0.21 0.06 0.35
> 800 mm 0.49 -0.16 1.14
Rotation/association (180) < 601 mm -0.06 -0.38 0.26
601-800 mm -0.31 -0.65 0.03
> 800 mm 0.14 0.15 0.42
Soil and water conservation (119) < 601 mm 0.41 0.30 0.51
601-800 mm 0.37 0.24 0.49
> 800 mm -0.24 -0.73 0.25
Effect of rainfall on cereal grain yield (across crops) response to
conservation agriculture practices in four West African Sahelian countries
(Burkina Faso, Mali, Niger and Senegal)
Scaling up: factors affecting yield (3)
31. Unexplored or insufficiently explored areas
ï Continue the efforts of designing sound experiments to
address methodological difficulties of assessing the park
effect;
ï Accelerate modeling efforts at different scales (e.g. tree-
crop, field and landscape) to improve our understanding
and save time and resources;
ï Pursue long-term research on processes to be able to
tailor interventions to particular contexts;
ï Continue investigating the tradeoffs and synergies
between and among the goods and services that trees in
agro-ecosystems can provide.
ï Continue the research on how the systems might respond
or be managed differently in relation to climate change
forecasts