Long-term ecosystem development and terrestrial plant diversity

Etienne LalibertéSchool of Plant BiologyThe University of Western Australiawww.elaliberte.infoSTRI, January 8, 2013

Outline• Long-term ecosystem development• Soil chronosequences

– Jurien Bay dune chronosequence• Nutrient limitation and nutrient-use efficiency• Patterns of plant species diversity

– local (alpha) diversity– site-to-site (beta) diversity

Odum (1969) Science

Eugene Odum(1913-2002)

Respiration

BiomassGross production

Netproduction

Peak standing

biomass = ‘climax’

Ecosystem development

Odum (1969) Science

Respiration

BiomassGross production

Netproduction

What about over longer periods?

1000’s

?

Hawaiian 4.1 million-year island sequence

Crews et al. (1995) Ecology

Long-term soil chronosequences

Wardle et al (2004) Science

Ecosystem decline or retrogression

Wardle et al (2004) Science

Long-term soil chronosequences

Peltzer et al (2010) Ecol Monogr

Soil age

Build-up (progressive) phase Maximal phase Decline (retrogressive) phase

Loss of P drives ecosystem decline

Soil age

Mineral P

Organic P

Total P

Apatite(phosphate minerals)

Walker & Syers (1976) Geoderma

• Ancient, low-P soils• Biodiversity hotspot• ~8000 plant species• ~50% endemic• Highest plant

diversity in kwongan– small scales (100 m2)– also between sites (β)

Hopper & Gioia (2004) Ann Rev Ecol Evol Syst

Jurien Bay dune chronosequence

South-western AustraliaSpecies richness

Species endemism

JurienBay

Perth

Jurien Bay >2-million-year dune chronosequence

0-7 ky

120-500 ky

>2000 ky

Holocene

Middle to late Pleistocene

Late Pliocene to Early Pleistocene

Collaboration between UWA and STRI (Ben Turner)

A

C

Stage 1: very young dunes(10’s—100 years)

High P

Laliberté et al. (2012) J Ecol

Very low N

Photo: Graham Zemunik

Stage 2: young dunes(100’s-1000’s years)

High P

Laliberté et al. (2012) J Ecol

Highest N

A

C

Stage 3: young dunes(~7000 years)

Medium P

Laliberté et al. (2012) J Ecol

Medium N

A

C1

C2

CA

C3

Stage 4: old dunes(~120,000 years)

Very low P

Laliberté et al. (2012) J Ecol

Low N

AE

B1E

A

B2

Stage 5: very old dunes(>2,000,000 years)

Extremely low P

Laliberté et al. (2012) J Ecol

Low N

EA

E

O

A

Ecosystem progression and retrogression

Bioassay with canola

Litterfall traps

Laliberté et al. (2012) J Ecol

Nutrient (co)limitation

N limitation

Laliberté et al. (2012) J Ecol

Nutrient (co)limitation

N limitation Co-limitation

Laliberté et al. (2012) J Ecol

Co-limitation

Nutrient (co)limitation

N limitationStrong P

limitationCo-limitation P limitation

Laliberté et al. (2012) J Ecol

Co-limitation

Plant nutrient-use efficiency

Resorption from senescing leaves

NUE = carbon fixed per unit nutrient taken up

Green leaf nutrient concentration

Leaf lifespan

Photo: Patrick Hayes

Leaf P concentration and resorptionPatrick Hayes

Honours studentNFAM EM NM

Plant species richness increases during ecosystem development

Data from Wardle et al. (2008) OikosLaliberté et al. (in review)

Random stratified sampling

6 dune systems * 10 plots = 60

Mean distance = 10 km

Each plot = 10x10 m

Graham Zemunik (PhD student)• Vegetation surveys• cover• count data• height, diameter

Jurien Bay: alpha diversity

All vascular plantsobserved species richness

All vascular plantsrarefied species richness

Time

Pedogenic stage

Multivariate controls over local plant diversity

Increasing dune age

Haast, New Zealand

Turner et al. (2012) Catena

Time

Pedogenic stage

Diversity of N and P forms

Plantdiversit

yresource partitioning (+)

Multivariate controls over local plant diversity

Local processes

Bever et al. (2010) TREE

Nitrogen

Time

Pedogenic stage

Diversity of N and P forms

Plantdiversit

yresource partitioning (+)

Multivariate controls over local plant diversity

Local processes

Turner (2008) J Ecol

Phosphorus

Nutrientavailability and stoichiometry

Time

Pedogenic stage

Diversity of N and P forms

resource partitioning (+)

resource-ratio model, productivity-diversity (+/-)

Multivariate controls over local plant diversity

Local processes

Plantdiversit

y

Grime (1973) Nature

Spec

ies

richn

ess

Humped-back model

Nutrientavailability and stoichiometry

Time

Pedogenic stage

Diversity of N and P forms

resource partitioning (+)

resource-ratio model, productivity-diversity (+/-)

Multivariate controls over local plant diversity

Local processes

Plantdiversit

y

Resource-ratio model

Tilman (1982)

N?

P?

Nutrientavailability and stoichiometry

Soil spatialheterogeneity

Time

Pedogenic stage

Diversity of N and P forms

Plantdiversit

yresource partitioning (+)

niche theory (+)

resource-ratio model, productivity-diversity (+/-)

Multivariate controls over local plant diversity

Local processes

Nutrientavailability and stoichiometry

Soil spatialheterogeneity

Time

Soil biota

Pedogenic stage

Diversity of N and P forms

Plantdiversit

yresource partitioning (+)

negative plant-soil feedback (+)

niche theory (+)

resource-ratio model, productivity-diversity (+/-)

Multivariate controls over local plant diversity

Local processes

Host-specific pathogen

Bever et al. (2010) TREE

Nutrientavailability and stoichiometry

Soil spatialheterogeneity

Time

Soil biota

Pedogenic stage

Diversity of N and P forms

Plantdiversit

yresource partitioning (+)

negative plant-soil feedback (+)

niche theory (+)

resource-ratio model, productivity-diversity (+/-)

Multivariate controls over local plant diversity

Local processes

Host-specific pathogen

Bever et al. (2010) TREE

3-year projectwith Ben Turner (STRI) and other collaborators

Nutrientavailability and stoichiometry

Soil spatialheterogeneity

Time

Soil biota

Stage-specificspecies

pool size

Pedogenic stage

Diversity of N and P forms

Abiotic conditions

Plantdiversit

yresource partitioning (+)

species pool hypothesis (+)

negative plant-soil feedback (+)

niche theory (+)

resource-ratio model, productivity-diversity (+/-)

environmental filtering (-)

Multivariate controls over local plant diversity

Local processes

‘Regional’ processes

Time

Stage-specificspecies

pool size

Pedogenic stage

Abiotic conditions

species pool hypothesis (+)

environmental filtering (-)

Multivariate controls over local plant diversity

‘Regional’ processes

Plantdiversit

y

Young carbonate dunespH > 8

Nutrientavailability and stoichiometry

Soil spatialheterogeneity

Time

Soil biota

Stage-specificspecies

pool size

Pedogenic stage

Diversity of N and P forms

Abiotic conditions

Plantdiversit

yresource partitioning (+)

species pool hypothesis (+)

negative plant-soil feedback (+)

niche theory (+)

resource-ratio model, productivity-diversity (+/-)

environmental filtering (-)

Multivariate controls over local plant diversity

Local processes

‘Regional’ processes

From alpha to beta diversity

0.01 ky 1 ky 7 ky 120 ky 500 ky 2000 ky

10 m X 10 m plot

How many plant species?

Alpha diversity

Dune age

From alpha to beta diversity

0.01 ky 1 ky 7 ky 120 ky 500 ky 2000 ky

Dune age

How much variation in species composition between plots within a dune system?

Beta diversity

Alpha and beta determine gamma diversity (total number of species)

Does beta diversity increase with productivity?

Chase (2010) Science

From alpha to beta diversity

0.01 ky 1 ky 7 ky 120 ky 500 ky 2000 ky

Dune age

Productivity peaks in relatively young soils (1-7 ky), then declines in older soils (>120 ky)

Alpha and gamma diversityStage 2 (~1 ky)

Stage 6 (2000 ky)

Beta diversityStage 2 (~1 ky)

Stage 6 (2000 ky)

Spatial autocorrelation?Condit et al. (2002) Science

Spatial autocorrelation?Condit et al. (2002) Science

In older dunes, community similarity drops faster with geographical distance

Spatial autocorrelation?

di

Mean distance to centroid = measure of spatial dispersion

Condit et al. (2002) Science

Spatial autocorrelation?

di

Mean distance to centroid = measure of spatial dispersion

Condit et al. (2002) Science

β = -1.04P ≤ 0.05

In older dunes where beta diversity is greatest, plots are actually closer to each other

Differences in sampling effort?

After rarefaction, general pattern persists

Environmental heterogeneity?

Laliberté et al. (2012) J Ecol

• Total N• Total P• Resin P• pH• CEC• etc...

Environmental heterogeneity?

Greater beta diversity in older soils not linked to greater environmental heterogeneity

but σ quite small

Summary

• Ecosystem progression & ecosystem retrogression

• Shifts from N to P limitation• Higher P-use efficiency with soil age• α, β, and γ diversity higher in older soils• Higher β diversity in older soils despite:

– plots closer to each other– lower environmental heterogeneity

• Contrary to productivity-beta diversity hypothesis?

• Chronosequences as ‘natural experiments’ for plant community ecology

• Hans Lambers• Graham Zemunik• Ben Turner• François Teste• Patrick Hayes• Stuart Pearse• Thomas Costes• several field workers...

Acknowledgements• Thanks to STRI for the invitation