1. J. Bayala1, J. Sanou2, ., Ouédraogo S.J.3,
Z. Teklehaimanot4, M. van Noordwijk1, U. Ilstedt5, A.
Kalinganire1
1World Agroforestry Centre-WCA/Sahel Node, Bamako, Mali
2Institut de l’Environnement et de Recherches Agricoles (INERA), Burkina Faso
3Institut du Sahel
4Bangor University, UK
5Department of Forest Ecology and Management, Swedish University of Agricultural
Sciences (SLU), Umeå, Sweden
Improving on-farm productivity
of trees and Agroforestry
systems in the Sahel

2. Outline
• Introduction
• Supporting services
• Regulating services
• Provisioning services
• Processes
• Experimental designs used
• Scaling up
• Concluding remarks
• 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 1960’ 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 of…..
Roles and functions such as:
- Supporting services (soil formation, nutrient
cycling, primary production…);
- Regulating services (climate, diseases, water
regulation….);
- Provisioning services (food, fuel wood, …);and
- Cultural services (recreational and ecotourism, …).
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) 76:193–201

7. Regulating services (1)
Empirical data collection of tree effects on temperature and humidity at crop
level
Bayala, J., Sanou, J., Bazié, P., and van Noordwijk, M
CRP 7 Activity report, World Agroforestry Centre (2013)
• Saponé in Burkina Faso
• Species: Parkia biglobosa and Vitellaria
paraodxa
• Each species: 3 big trees and 3 small
• Two fertility levels: Fertilized and unfertilized
• Total number of individuals per species: 6
trees X 2 fertility levels = 12 trees
• Parameters: Temperature, relative humidity,
PAR and wind speed

8. Effect of position relative to a
Karité (Vitellaria paradoxa) or
Néré (Parkia biglobosa) tree on
maximum daily temperature at
crop level (left panels) or
minimum air humidity (right
panels) for zones A (under the
tree) and B (edge of tree canopy )
compared to zone C (in between
trees) in the parkland landscape of
Sapone (Burkina Faso) (data:
Bayala et al., 2013
Buffering effects of trees on maximum daily
temperature (average 1oC up to 2.5oC on hot,
cloudless days) and minimum air humidity (up to
5%), with stronger differences on hotter and drier
days
Regulating services (2)

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

10. After the harvest of the millet crop, the soil shows the ‘normal’ day/night
cycle of rewetting by tree roots (‘hydraulic redistribution’)…
WaNuLCAS simulation showed that 73.0 L and 247.1 L were redistributed per tree per day for karité
and néré, representing respectively 60% and 53% of the amount transpired a day, and 14% and 26% of
the evapotranspiration.
Regulating services (4)
Time (GMT)
-4.00
-3.50
-3.00
-2.50
-2.00
-1.50
-1.00
-0.50
0.00
1
11
21
7
17
3
13
23
9
19
5
15
1
11
21
0
10
20
30
40
50
60
70
Water potential (MPa)
Temperature oC
Transpiration (L hr-1)
-3.30
-3.20
-3.10
-3.00
-2.90
-2.80
-2.70
-2.60
-2.50
1
3
5
7
9
11
13
15
17
19
21
23
0
10
20
30
40
50
60
Water potential (MPa)
Transpiration (L hr-1)

11. Regulating services (5)
Intermediate tree cover can maximize groundwater recharge
U. Ilstedt, A. Bargués Tobella, H.R. Bazié, J. Bayala, E. Verbeeten, G. Nyberg, J. Sanou, L.
Benegas, D. Murdiyarso, H. Laudon, D. Sheil, A. Malmer
Geoscience (submitted)

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

13. Regulating services (7)
The effect of trees on preferential flow and soil infiltrability in an
agroforestry parkland in semiarid Burkina Faso
Bargués Tobella,A., Reese,H., Almaw A., Bayala J. , Malmer A., Laudon H., Ilstedt U.
Water Resources Research (in press)
Stained profiles
(black: dye-stained;
white: non-stained;
grey: roots and black
areas) and their
corresponding
profiles of dye
coverage representing
a gradient with
increasing degree of
preferential flow.

14. Provisioning services (1)
Preferred species and reasons for their
preservation in parklands
 Preferred species and reasons: contribution to
farmers’ annual revenue 26-73% (Gijsbers et al.
1994; Boffa 1995; Lamien et al. 1996; Faye et al.
2010);
 Tree species diversity from 43 to 110 species
(Gijsbers et al. 1994, Boffa 1995; Yaméogo and
Nikiéma 1995; Nikiéma 2004; Nikiéma 2005;
Abegg et al. 2006; Kindt et al. 2008; Bayala et al.
2010);

15. Light (mol m-2 day-1)
reduction under
differentially pruned néré
(Parkia biglobosa) trees in a
parkland agroforestry
system (Bayala et al. 2002)
Year Zone Karité Néré
1999 A 18.3 3.7
B 41.3 36.7
C 49.3 53.3
Co 79.8 79.8
2001 A 16.4 8.9
B 29.3 14.1
C 56.9 36.5
Co 66.7 66.7
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Transpirationrate(l/hr)
Time (GMT)
Total pruned
Half-pruned
Unpruned
Karite
0.30.20.1
0-10
10-20
20-30
30-40
40-50
Depth(cm)
Root length density (cm cm-3)
a: Karite
Unpruned
Half-pruned
Total-pruned
0.350.300.250.200.150.100.050.00
0-10
10-20
20-30
30-40
40-50
Depth(cm)
Root length density (cm cm-3)
b: Nere
0.060.050.040.030.02
0-10
10-20
20-30
30-40
40-50
Depth(cm)
Root length density (cm cm-3)
Unpruned
Half-pruned
Total-pruned
a: Karite
0.0 0.1 0.2 0.3
40-50
30-40
20-30
10-20
0-10
Depth(cm)
Root length density (cm cm-3)
b: Nere
Reduction of fine root density and transpiration in pruned trees (Bayala et al. 2002,
2004)
Provisioning services (2)
Millet production under pruned tree crowns in a parkland system in Burkina Faso
J. Bayala, Z. Teklehaimanot and S. J. Ouedraogo
Agroforestry Systems 54: 203–214, 2002

16. Aboveground grain and dry matter yield of sorghum under differentially
pruned karité (Vitellaria paradoxa) and néré (Parkia biglobosa) trees in a
parkland agroforestry system in Saponé (mean kg ± SE ha-1)
a-
0
500
1000
1500
2000
Rendementgrain(kg.ha-1)
non taillé
taille totale
b-
0
500
1000
1500
2000
2500
Rendementmatièresèche(kg.ha-1)
non taillé
taille totale
Unpruned néré
Totally-pruned néré

17. Effect of pruning on fruit production of karité (Vitellaria paradoxa) and
néré (Parkia biglobosa) trees in a parkland agroforestry system in
Saponé, Burkina Faso (kg ± SE tree-1) (Bayala et al. 2008)
Agroforestry Systems (2008) 72:187–194
Provisioning services (3)
Rejuvenating indigenous trees in agroforestry parkland systems for better fruit
production using crown pruning

18. Parkia biglobosa
Pennisetumglaucum
Colocasiaesculenta
Adansonia digitata
Source: Sanou (2010)
Effect of shading by baobab (Adansonia digitata) and néré (Parkia biglobosa) on
yields of millet (Pennisetum glaucum) and taro (Colocasia esculenta) in parkland
systems in Burkina Faso, West Africa
Sanou J, Bayala J, Teklehaimanot Z, Bazie P
Agroforestry Systems (2012) 85: 431-441

19. 0
250
500
750
1000
Baobab Néré
Yield(kgha-1)
0
1000
2000
3000
4000
5000
6000
Baobab Néré
Yield(kgha-1)
Parkia biglobosa
Adansonia digitata
Pennisetumglaucum
Colocasiaesculenta

20. Pruning
Competition and facilitation-related factors impacts on crop performance in an agro-
forestry parkland system in Burkina Faso
Bayala J., Bazié H.R., and Sanou J.
African Journal of Agricultural Research 8(43): 5303-5310
Processes: manipulative experiment (1)

21. Crop performance overestimated:
 Not all limitations occurring in the field
were adequately represented and/or
 Resource capture in the model (light,
water, N and P) was overestimated
(Bayala et al. 2008)
Light was the most limiting factor for both
tree species and the crops
Karité (Vitellaria paradoxa): Water
limitation dominated for both the tree and
associated crop.
Néré (Parkia biglobosa): P limitation was
more severe corroborating the findings of
Tomlinson et al. (1995).
Karite
0.00.10.20.30.40.50.60.7
Simulatedyield(kgm-2)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.00.10.20.30.40.50.60.7
SimulatedTDM(kgm-2)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Nere
Measuredyield(kgm-2
)
0.00.10.20.30.40.50.60.7
Simulatedyield(kgm-2)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
MeasuredTDM(kgm-2)
0.00.10.20.30.40.50.60.7
SimulatedTDM(kgm-2)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1:1
1:1
Scatter plots of measured and simulated crop yield
and total dry matter (TDM) under karité (Vitellaria
paradoxa) and néré (Parkia biglobosa) trees in a
parkland agroforestry system
Separating the tree-soil-crop interactions in agroforestry parkland
systems in Saponé (Burkina Faso) using WaNuLCAS.
Bayala J., van Noordwijk M., Lusiana B., Kasanah N., Teklehaimanot Z., Ouedraogo S.J.
Advances in Agroforestry (2008) 4: 296-308
Processes: modeling (2)

22. Studied factors: N, P and water
Combination: 8 treatments
Applying irrigation, nitrogen and phosphorus
increased grain yield by 29% and biomass by 23%.
Crown pruning has increased grain yield by 520%
and biomass yield by 348%
S. bicolor production was 56% higher under V.
paradoxa than under P. biglobosa
Light is the most limiting factor under
trees of P. biglobosa and V. paradoxa (Bazié et al.,
2012)
Separating competition-related factors limiting crop performance in an
agroforestry parkland system in Burkina Faso
H. R. Bazié, J. Bayala , G. Zombré, J. Sanou, U. Ilstedt
Agroforestry Systems (2012) 84:377-388
Processes: manipulative experiment (3)

23. • Effect of 10 years cropping without
inorganic fertilizer and with sorghum
residues returning as mulch on sorghum
biomass and yield under current climate.
• 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
• Effect of increase and decrease in the
amount of rainfall as well as changes in
rainfall pattern (occurrence of extreme
events)
• 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
• 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
• Under the current climate, increasing the tree
density does not negatively affect sorghum
growth if crown pruning is applied
• 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
• 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)
 Human mediated processes?
 Landscape level?
Models can help:
 For processes we know sufficiently well to
structure and parameterize them
 If they reveal what we do not know when
simulated and observed data disagree

26. Complexity of the systems
Overview of experimental designs used (2)

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)

30. Concluding remarks
Bayala J., Sanou J., Teklehaimanot Z., Kalinganire A., Ouédraogo S.J.
Current Opinion in Environmental Sustainability 6 (2014):28-34

31. Unexplored or insufficiently explored areas
 Continue the efforts of designing sound experiments to
address methodological difficulties of assessing the park
effect;
 Accelerate modeling efforts at different scales (e.g. tree-
crop, field and landscape) to improve our understanding
and save time and resources;
 Pursue long-term research on processes to be able to
tailor interventions to particular contexts;
 Continue investigating the tradeoffs and synergies
between and among the goods and services that trees in
agro-ecosystems can provide.
 Continue the research on how the systems might respond
or be managed differently in relation to climate change
forecasts