STRI talk, long-term ecosystem development and plant diversity

Long-term ecosystem development and terrestrial plant diversity

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

http://www.elaliberte.info/

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


Highest N

A

C

Stage 3: young dunes(~7000 years)

Medium P


Medium N

A

C1

C2

CA

C3

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

Very low P


Low N

AE

B1E

A

B2

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

Extremely low P


Low N

EA

E

O

A

Ecosystem progression and retrogression

Bioassay with canola

Litterfall traps


Nutrient (co)limitation

N limitation



N limitation Co-limitation


Co-limitation


N limitationStrong P

limitationCo-limitation P limitation


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 (+)


Local processes

Bever et al. (2010) TREE

Nitrogen

Time

Pedogenic stage


Plantdiversit



Local processes

Turner (2008) J Ecol

Phosphorus

Nutrientavailability and stoichiometry

Time

Pedogenic stage


resource partitioning (+)

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


Local processes

Plantdiversit

y

Grime (1973) Nature

Spec

ies

richn

ess

Humped-back model


Time

Pedogenic stage


resource partitioning (+)



Local processes

Plantdiversit

y

Resource-ratio model

Tilman (1982)

N?

P?


Soil spatialheterogeneity

Time

Pedogenic stage


Plantdiversit


niche theory (+)



Local processes



Time

Soil biota

Pedogenic stage


Plantdiversit


negative plant-soil feedback (+)

niche theory (+)



Local processes

Host-specific pathogen




Time

Soil biota

Pedogenic stage


Plantdiversit



niche theory (+)



Local processes

Host-specific pathogen


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



Time

Soil biota

Stage-specificspecies

pool size

Pedogenic stage


Abiotic conditions

Plantdiversit


species pool hypothesis (+)


niche theory (+)


environmental filtering (-)


Local processes

‘Regional’ processes

Time


pool size

Pedogenic stage

Abiotic conditions





Plantdiversit

y

Young carbonate dunespH > 8



Time

Soil biota


pool size

Pedogenic stage


Abiotic conditions

Plantdiversit




niche theory (+)




Local 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


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


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?


• 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

STRI talk, long-term ecosystem development and plant diversity

Education

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