Impact of host composition and shade tree spatial ... · PDF fileImpact of host composition...
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Impact of host composition and shade tree spatial structure on pest infestation in cocoa agroforests Cynthia Gidoin [email protected] UR 106 Marie Ange Ngo Bieng, Christian Cilas, Régis Babin, Martijn ten Hoopen, Leila Bagny Beilhe 18 August 2013 the 11th INTECOL Congress. Montpellier France Yaoundé, Cameroon
Transcript of Impact of host composition and shade tree spatial ... · PDF fileImpact of host composition...
Impact of host composition and shade tree spatial structure on pest infestation in cocoa agroforests
Cynthia [email protected]
UR 106
Marie Ange Ngo Bieng, Christian Cilas, Rgis Babin, Martijn ten Hoopen, Leila Bagny Beilhe
18 August 2013 the 11th INTECOL Congress.
Montpellier FranceYaound, Cameroon
Ecosystem servicesMultispecies agroecosystems
Avelino et al. 2011 ; Ratnadass et al., 2012 ; Maleizeux et al., 20082
Cacao agroforests
Ecosystem servicesMultispecies agroecosystems
Complexvegetation structure
Avelino et al. 2011 ; Ratnadass et al., 2012 ; Maleizeux et al., 20083
Cacao agroforests
Ecosystem servicesMultispecies agroecosystems
Complexvegetation structure?
Avelino et al. 2011 ; Ratnadass et al., 2012 ; Maleizeux et al., 20084
Cacao agroforests
Ecosystem servicesMultispecies agroecosystems
Complexvegetation structure?
Pest
Avelino et al. 2011 ; Ratnadass et al., 2012 ; Maleizeux et al., 20085
Cacao agroforests
PestMirids
S. singularis
Chocolate
Pod
cacaoComplexvegetation structure
Crop
Ploetz 2007 ; Babin 20096
Ligneous
Vertical structure
Horizontalstructure
Multi strata Not regular
Crop
Cacao agroforests S. singularis
Pod
cacao
Chocolate
Malezieux et al., 2008 ; Schroth et al., 2004; Ploetz 2007 ; Babin 20097
PestMirids
Pod
Microclimate Resource
Vertical structure
Horizontalstructure
Multi strata Not regular
Crop
Cacao agroforests S. singularis
Shade
- -
-
Malezieux et al., 2008 ; Schroth et al., 2004; Ploetz 2007 ; Babin 20098
PestMirids
Ligneous spatial structure
Microclimate Resource
Vertical structure
Horizontalstructure
Multi strata Not regular
Cacao agroforests S. singularis
Shade
- -
Host composition
Pod
Crop
-
-
AbundanceDensity
Host composition
Stephens et al. 2012 ; Malezieux et al., 2008 ; Schroth et al., 2004; Ploetz 2007 ; Babin 20099
PestMirids
Ligneous spatial structure
Microclimate Resource
Vertical structure
Horizontalstructure
Multi strata Not regular
Cacao agroforests S. singularis
Shade
- -
Host composition
Pod
Crop
-
-
AbundanceDensity
Host composition
Alternativehost
Cola spp.
+
+
Stephens et al. 2012 ; Malezieux et al., 2008 ; Schroth et al., 2004; Ploetz 2007 ; Babin 200910
PestMirids
Ligneous spatial structure
Microclimate Resource
Vertical structure
Horizontalstructure
Multi strata Not regular
Cacao agroforests S. singularis
Shade
- -
Host composition
Pod
Crop
-
-
AbundanceDensity
Host composition
Alternativehost
Cola spp.
+
+
1- What are the independent effects and relative importance of host composition and shade tree spatial structure in mirid density at the plot scale ?
2- What is the vegetation structure of agroforest to promote in order to reduce the mirid density at the plot scale.
Ligneous spatial structure
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PestMirids
Yaound
Obala
Centre
7m
Sampling unit: 50 x 50 m
Plot (x 20)
Cacao
Fruit tree
Forest tree
Dcov %Fo HSfo HSfu
Plant spatial structure
Cacao agroforests
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Dcov %Fo HSfo HSfu
7m
Plot (x 20)
Cacao
Fruit treeAggregated RandomLow density
Forest trees (HSfo)
Fruit trees (HSfu)
Low density/Random/Regular
Ripleys function Typology
Sampling unit: 50 x 50 m
Forest tree
Plant spatial structure
Cacao agroforests
Ripley 1977 ; Ngo Bieng et al., 201313
Dcov %Fo HSfo HSfuPlot (x 20)
Cacao 7 m
Sampling unit: 50 x 50 m
Cacao tree abundanceCacao tree densityCola spp. DensityProduction
Cola spp.
Plant spatial structure
Cacao agroforests
Host composition
Abca Dca Dcola Prod
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Plot (x 20)
Cacao
Mirid density Cola spp.
x 80
2011 and 2012
Cacao tree abundanceCacao tree densityCola spp. DensityProduction
Cacao agroforests
Sampling unit: 50 x 50 m
Dcov %Fo HSfo HSfu
Plant spatial structureHost composition
Abca Dca Dcola Prod
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Mirid density
Hierarchical partitionning
More causal factor explaining mirid density ?
Y ~ Xi Ri : total variance explained
Ri = Ii + Ji
I : Independent contributionJ : Joint contribution
Xi collinearity
Y
Xi : Host composition
Abca Dca Dcola Prod Dcov %Fo HSfo HSfu
Plant spatial structure
Mac Nally 2000
1- What are the independent effects and relative importance of host composition and shade tree spatial structure in mirid density at the plot scale ?
16
56.38 %
Hierarchical partitionning
15
10
5
0
13.9%
Dcov %Fo HSfo HSfu
Plant spatial structure
Mirid density% variance explained
21 % 79 %
Host composition
49%12.0%
IndependentJoint
Abca Dca Dcola Prod
1- What are the independent effects and relative importance of host composition and shade tree spatial structure in mirid density at the plot scale ?
17
56.38 %
12.0%
13.4%
Dcov %Fo HSfo HSfu
Hierarchical partitionning
-Mirid density% variance explained
Plant spatial structure
R2 = 0.22
Plant spatial structureVertical structure
%Fo
Log(
Dm
ir)
00 100%Fo
F = 10.8**
4
2
Forest ratherthan fruit trees
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2- What is the vegetation structure of agroforest to promote in order to reduce the mirid density at the plot scale.
Forest ratherthan fruit trees 56.38 %
12.0%
13.4%
Dcov %Fo HSfo HSfu
Hierarchical partitionning
Plant spatial structure
R2 = 0.22
Plant spatial structureVertical structure
Horizontal structure
%Fo
HSfo
ab b
3,5 2,7 2,1
a
Aggregated RandomLow density
Log(
Dm
ir)Lo
g(D
mir)
00 100%Fo
F = 10.8**
4
2
Mirid density% variance explained
F = 3.9* Randomrather thanaggregated
R2 = 0.17
-
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2- What is the vegetation structure of agroforest to promote in order to reduce the mirid density at the plot scale.
Hierarchical partitionning
R2 = 0.22
Plant spatial structureVertical structure
Horizontal structure
%Fo
HSfo
ab b
3,5 2,7 2,1
a
Aggregated RandomLow density
R2 = 0.17
Log(
Dm
ir) F = 3.9*
Log(
Dm
ir)
00 100%Fo
F = 10.8**
4
2
Babin et al., 2010
- Homogeneous shadeForest rather
than fruit trees
Randomrather thanaggregated
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2- What is the vegetation structure of agroforest to promote in order to reduce the mirid density at the plot scale.
%trans.light
Mirid/cacao
Hierarchical partitionning
R2 = 0.22
Plant spatial structureVertical structure
Horizontal structure
%Fo
HSfo
ab b
3,5 2,7 2,1
a
Aggregated RandomLow density
Log(
Dm
ir)Lo
g(D
mir)
00 100%Fo
F = 10.8**
4
2
- Homogeneous shade
Architectural characteristics
Our data
Babin, 2009
R2 = 0.17
F = 3.9*
Forest ratherthan fruit trees
Randomrather thanaggregated
Fu
Fo
20
5Cro
wn
heig
ht(m
)21
2- What is the vegetation structure of agroforest to promote in order to reduce the mirid density at the plot scale.
Hierarchical partitionning
R2 = 0.22
Plant spatial structureVertical structure
Horizontal structure
%Fo
HSfo
ab b
3,5 2,7 2,1
a
Aggregated RandomLow density
Log(
Dm
ir)Lo
g(D
mir)
00 100%Fo
F = 10.8**
4
2
- Homogeneous shade
% light variance reduction
Martens, 2009
40%
3
16
80%Canopy cover
2- What is the vegetation structure of agroforest to promote in order to reduce the mirid density at the plot scale.
R2 = 0.17
F = 3.9*
Forest ratherthan fruit trees
Randomrather thanaggregated
Architectural characteristics
Our data
Babin, 2009
Fu
Fo
20
5Cro
wn
heig
ht(m
)
PA
R v
aria
nce
(.10
6 )
22
Host composition
Microclimate
Mirids pest
Ligneous spatial structure
Resource
Vertical structure
Horizontalstructure
Crop
AbundanceDensity
Amount
cacao
Shade
-
Alternativehost
Cola spp.Forest ratherthan fruit trees
Random ratherthan aggregated
79%21%
ConclusionSignificance of the study: Mirid density is more explained by shade tree spatial structure than by host composition. Promoting forest trees randomly distributed.
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Pod
Host composition
Microclimate
Mirids pest
Ligneous spat
