Contrasting tissue strategies explain functional beta diversity in Amazonian trees

C. Fortunel, C.E.T. Paine, N. Kraft, P.V.A. Fine, C. Baraloto*

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)

Lewis et al. 2011. ScienceAsner et al. 2010. Conserv Lett

Introduction Material and methods ResultsConclusion and perspectives

Impact on functional diversity

Reu et al. 2011. Biogeosciences

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.

• Loss of biodiversity, especially in the tropics, with consequences for ecosystem services

• Predictions of loss of functional diversity limited by poor description of spatial patterns

Introduction Material and methods ResultsConclusion and perspectives

Community assembly

Regional species pool

Local community

Stochastic processesNiche-based processes

Dispersal limitation

Speciation rate

Demographic stochasticity

Species functional strategies

Niche differentiation (limiting similarity)Density-dependent mechanisms (e.g. Janzen-Connell)

Environmental filtering

Introduction Material and methods ResultsConclusion and perspectives

Fitness

Community assembly and species traits

Reproduction

Growth

Survival

Introduction Material and methods ResultsConclusion and perspectives

•Trait = any morphological, physiological or phenological feature measurable at the individual level(Violle et al. 2007. Oikos)

•Traits reflect tradeoffs that determine • Species performance in a given environment• Species abundances along environmental gradients

•Importance of environmental filteringEx: environmental filtering on SLAKraft et al. 2008. Science

To what extent environmental filtering has predictable consequences on the functional composition of communities across the landscape?

Functional strategies of tropical trees

leaf – stem economics

668 species, French Guiana

(project BRIDGE)

Baraloto et al. 2010. Ecology Letters

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.00.20.40.60.81.0

0.0

0.2

0.4

0.6

0.8

1.0

LChl

LthickLtough

L13C

LA

LC.N

LCC

LKC

LNC

LPC

LTD

R wood H

R wood D

S wood H

S wood D

SLA

Bark thick

Dim 1: 23.02 %

Dim

2: 1

5.45

%

Fortunel et al. submitted

leaf – wood (stem/root) economics

800 species, French Guiana and Peru

(project AmaLin)

Introduction Material and methods ResultsConclusion and perspectives

Regional pool (trait distribution)

Terra firme TF

Seasonally floodedSF

White sandWS

wood economics(stem/root)

leaf economics

Wood density SLA

Prediction of direction of environmental filtering

Introduction Material and methods ResultsConclusion and perspectives

Plot network of AmaLin project

Introduction Material and methods ResultsConclusion and perspectives

74 plotsModified-GentryFrench Guiana and Peru

Baraloto et al. 2011. Global Change Biology

Three contrasting habitatsacross a broad environmental gradient

Terra firme (TF)

Seasonnally flooded(SF)

White sand(WS)

• Botanical records (species identification and abundance)• Description of environmental factors (climate and soil)

Environmental factors Plots per habitats

Introduction Material and methods ResultsConclusion and perspectives

Functional trait measurements

For each species in each plot, traits were measured at the level of:

• LeafSLA, LA, toughness, thickness, LTD, LChl, LCC, LNC, LC:N, LPC, LKC, L 13C, L 15N

• Stemwood density, humidity

• Trunkbark thickness

• Rootwood density, humidity

Introduction Material and methods ResultsConclusion and perspectives

Evaluation of environmental filtering

Regional species pool (FG or Peru)

999 random communities (equal number of individuals x)

Random assemblage function of species abundances

irrespective of species traits

Focal plot(number of individuals=x)

Observed community functional composition• Community-weighted mean• Convex Hull volume

Predicted distribution of community functional composition• Community-weighted mean• Convex Hull volume

Introduction Material and methods ResultsConclusion and perspectives

For each of 13 plots• Species traits• Species abundance

TFG4

SFG8

WSG2

wood economics leaf economics

Introduction Material and methods ResultsConclusion and perspectives

Environmental filtering on community functional composition

Environmental filtering on community functional composition

Introduction Material and methods ResultsConclusion and perspectives

CH overlap CH overlap

Den

sity

Den

sity

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)

White sand(WS)

Wood densityor 1/SLA

Wood densityor 1/SLA

Introduction Material and methods ResultsConclusion and perspectives

Perspectives

• Implications for modeling community shifts across the landscape

• Implications for ecosystem services under global changes scenarios

Introduction Material and methods ResultsConclusion and perspectives

Research was supported by a collaborative NSF DEB-0743103/0743800 to CB and PVAF and by an INRA Package grant to CB.