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J. Bayala1, J. Sanou2, ., Ouédraogo S.J.3,Z. Teklehaimanot4, M. van Noordwijk1, U. Ilstedt5, A.
Kalinganire1
1World Agroforestry Centre-WCA/Sahel Node, Bamako, Mali2Institut de l’Environnement et de Recherches Agricoles (INERA), Burkina Faso
3Institut du Sahel4Bangor 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
Outline• Introduction
• Supporting services
• Regulating services
• Provisioning services
• Processes
• Experimental designs used
• Scaling up
• Concluding remarks
• Unexplored and insufficiently explored areas
Reduced vegetation
cover
o 9-month dry seasono Frequent droughts during the rainy seasono High vulnerability to CV o High vulnerability to CC
o Low inherent fertilityo Subsistence agriculture (85%)o Food GR (2%)
o 19 million in 1960’ to 50 by 2000o High human pressure: 3% PGRo High animal pressure
oReduced vegetal coveroNutrient depletiono Reduced SOM and CEC
o Reduced IC o Increased runoffo Reduced WHCo Exacerbated competition for water
Introduction (1)
Some characteristics Some challenges
o High level of illiteracyo High level of unemploymento Low investment in agriculture
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)
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)
Supporting services (1)Relative contribution of trees and crops to soil carbon content in a parkland
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
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
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)
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
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 karitéand 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 oCTranspiration (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)
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)
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
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.
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);
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
Tra
nsp
ira
tio
n r
ate
(l/
hr)
Time (GMT)
Total pruned
Half-pruned
Unpruned
Karite
0.30.20.1
0-10
10-20
20-30
30-40
40-50
Dep
th (
cm)
Root length density (cm cm-3)
a: Karite
Unpruned
Half-pruned
Total-pruned
0.350.300.250.200.150.100.050.000-10
10-20
20-30
30-40
40-50
Dep
th (
cm)
Root length density (cm cm-3)b: Nere
0.060.050.040.030.020-10
10-20
20-30
30-40
40-50
Dep
th (c
m)
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
Dep
th (c
m)
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
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
Ren
dem
en
t g
rain
(kg
.ha-1
)
non taillé
taille totale
b-
0
500
1000
1500
2000
2500
Ren
dem
en
t m
ati
ère
sèch
e (
kg
.ha-1
)
non taillé
taille totale
Unpruned néré
Totally-pruned néré
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
Parkia biglobosa
Pennise
tumglaucum
Colocasia
escule
nta
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 AfricaSanou J, Bayala J, Teklehaimanot Z, Bazie P
Agroforestry Systems (2012) 85: 431-441
0
250
500
750
1000
Baobab Néré
Yie
ld (
kg
ha
-1)
0
1000
2000
3000
4000
5000
6000
Baobab Néré
Yie
ld (
kg
ha
-1)
Parkia biglobosa
Adansonia digitata
Pennise
tumglaucum
Colocasia
escule
nta
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)
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
Simulated yield (kg m-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
Simulated TDM (kg m-2)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Nere
Measured yield (kg m-2)
0.00.10.20.30.40.50.60.7
Simulated yield (kg m-2 )
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Measured TDM (kg m-2)
0.00.10.20.30.40.50.60.7
Simulated TDM (kg m-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 (Vitellariaparadoxa) 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)
Studied factors: N, P and waterCombination: 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)
• 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)
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)
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
Complexity of the systems
Overview of experimental designs used (2)
Scaling up: CAWT in Sahel (1)J. Bayala, A. Kalinganire, Z. Tchoundjeu, F. Sinclair, D. Garrity
ICRAF Occasional Paper No. 14.
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)
Rainfall
Practices (number of pairs) Rainfall class D (t ha-1) LCI UCIParkland (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 0.77601-800 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 0.95601-800 mm 0.21 0.06 0.35> 800 mm 0.49 -0.16 1.14
Rotation/association (180) < 601 mm -0.06 -0.38 0.26601-800 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 0.51601-800 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)
Concluding remarksBayala J., Sanou J., Teklehaimanot Z., Kalinganire A., Ouédraogo S.J.
Current Opinion in Environmental Sustainability 6 (2014):28-34
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
