stri talk, long-term ecosystem development and plant diversity
Post on 30-Jun-2015
641 Views
Preview:
DESCRIPTION
TRANSCRIPT
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
top related