Transcript Environmental filtering

Contrasting tissue strategies explain functional
beta diversity in Amazonian trees
C. Fortunel, C.E.T. Paine, N. Kraft, P.V.A. Fine, C. Baraloto*
Introduction
Material and methods
Results
Conclusion and perspectives
Global changes in the tropics
•
Land use changes through logging, deforestation, fragmentation, and fire use
•
Climate changes with increases in extreme climatic events (e.g. droughts)
Asner et al. 2010. Conserv Lett
Lewis et al. 2011. Science
Introduction
Material and methods
Results
Conclusion and perspectives
Impact on functional diversity
•
Loss of biodiversity, especially in the tropics, with consequences for ecosystem services
Fig. 2. Mean shifts in the geographic variation of functional richness (FR) between present-day (1960–1989) and future climate scenarios (2070–2099)
B1 (a) and A2 (b). FR increase and decrease is calculated relative to FR of present-day climates.
Reu et al. 2011. Biogeosciences
•
Predictions of loss of functional diversity limited by poor description of spatial patterns
Introduction
Material and methods
Results
Conclusion and perspectives
Community assembly
Niche-based processes
Regional species pool
Stochastic processes
Species functional strategies
Speciation rate
Environmental filtering
Dispersal limitation
Niche differentiation
(limiting similarity)
Density-dependent mechanisms
(e.g. Janzen-Connell)
Demographic stochasticity
Local community
Introduction
Material and methods
Results
Conclusion and perspectives
Community assembly and species traits
•
Trait = any morphological, physiological or phenological feature measurable at the individual level
(Violle et al. 2007. Oikos)
Reproduction
Survival
Fitness
Growth
•
Traits reflect tradeoffs that determine
• Species performance in a given environment
• Species abundances along environmental gradients
•
Importance of environmental filtering
Ex: environmental filtering on SLA
Kraft et al. 2008. Science
To what extent environmental filtering has predictable consequences on the functional
composition of communities across the landscape?
Introduction
Material and methods
Results
Conclusion and perspectives
Functional strategies of tropical trees
leaf – stem economics
leaf – wood (stem/root) economics
668 species, French Guiana
800 species, French Guiana and Peru
(project BRIDGE)
(project AmaLin)
1.0
0.8
Dim 2: 15.45 %
S wood D
R wood D
0.6
SLA
LNC
0.4
0.2
LKC LPC
0.0
1.0
0.8
0.6
0.4
L13C0.2
LTD
0.2
0.0
LCC LChl
0.2 thick
Bark
0.4
0.6
0.8
1.0
LC.N
Lthick
Ltough
0.4
LA
R wood H
S wood H
0.6
0.8
1.0
Dim 1: 23.02 %
Baraloto et al. 2010. Ecology Letters
Fortunel et al. submitted
Introduction
Material and methods
Results
Conclusion and perspectives
Prediction of direction of environmental filtering
wood economics
(stem/root)
leaf economics
Regional pool
(trait distribution)
Wood density
Terra firme
TF
Seasonally
flooded
SF
White sand
WS
SLA
Introduction
Material and methods
Results
Plot network of AmaLin project
74 plots
Modified-Gentry
French Guiana and Peru
Baraloto et al. 2011. Global Change Biology
Conclusion and perspectives
Introduction
Material and methods
Results
Conclusion and perspectives
Three contrasting habitats
across a broad environmental gradient
Terra firme
(TF)
•
•
Seasonnally flooded
(SF)
Botanical records (species identification and abundance)
Description of environmental factors (climate and soil)
Environmental factors
Plots per habitats
White sand
(WS)
Introduction
Material and methods
Results
Conclusion and perspectives
Functional trait measurements
For each species in each plot, traits were measured at the level of:
• Leaf
SLA, LA, toughness, thickness, LTD, LChl,
LCC, LNC, LC:N, LPC, LKC, L 13C, L 15N
• Stem
wood density, humidity
• Trunk
bark thickness
• Root
wood density, humidity
Introduction
Material and methods
Results
Conclusion and perspectives
Evaluation of environmental filtering
Regional species pool
(FG or Peru)
For each of 13 plots
• Species traits
• Species abundance
Focal plot
(number of individuals=x)
Observed community functional composition
• Community-weighted mean
• Convex Hull volume
Random assemblage
function of species abundances
irrespective of species traits
999 random communities
(equal number of individuals x)
Predicted distribution of community functional composition
• Community-weighted mean
• Convex Hull volume
Introduction
Material and methods
Results
Conclusion and perspectives
Environmental filtering on community functional composition
wood economics
TF
G4
SF
G8
WS
G2
leaf economics
Introduction
Material and methods
Results
Conclusion and perspectives
Density
Density
Environmental filtering on community functional composition
CH overlap
CH overlap
Introduction
Material and methods
Results
Conclusion and perspectives
Directional shifts in community functional composition
across the Amazonian landscape
Environmental filtering for denser leaf, stem and root tissues in dry and poor environments.
Terra firme
(TF)
Seasonnally flooded
(SF)
Wood density
or 1/SLA
White sand
(WS)
Wood density
or 1/SLA
Introduction
Material and methods
Results
Perspectives
• Implications for modeling community shifts across the landscape
• Implications for ecosystem services under global changes scenarios
Conclusion and perspectives
Research was supported by
a collaborative NSF DEB-0743103/0743800 to CB and PVAF
and by an INRA Package grant to CB.