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Soil bacterial community structure remains stable with rising temperature in Hawaiian montane wet forests
Paul C. Selmants, Karen L. Adair, Creighton M. Litton, Christian P. Giardina & Egbert Schwartz
How will soil bacteria respond to climate warming?
Climatic controls on bacterial distribution poorly resolved
How will soil bacteria respond to climate warming?
Climatic controls on bacterial distribution poorly resolved
Shift in diversity could alter biogeochemical cycling
Hawaii Mean Annual Temperature Gradient
800-1600 m (13-18.2 °C)
A model study system: - Constant plant spp. composition
- Constant disturbance histories
- Constant substrate age & type
- Constant soil water balance
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18.2 °C
17.3 °C16.7 °C
16.1 °C
16.1 °C15.5 °C
15.1 °C
13.8 °C13.0 °C
¯0 2 41 Kilometers
Forest Reserve
Natural Area Reserve
National Wildlife Refuge
Island of Hawaii
Hawaii Mean Annual Temperature Gradient
800-1600 m (13-18.2 °C)
A model study system: - Constant plant spp. composition
- Constant disturbance histories
- Constant substrate age & type
- Constant soil water balance
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18.2 °C
17.3 °C16.7 °C
16.1 °C
16.1 °C15.5 °C
15.1 °C
13.8 °C13.0 °C
¯0 2 41 Kilometers
Forest Reserve
Natural Area Reserve
National Wildlife Refuge
Island of Hawaii
Long-term, whole-ecosystem response to rising MAT
Workflow
DNA extraction(8 samples/MAT plot)
16S rDNA amplification
454 Pyrosequencing
Sequence processing(QIIME pipeline)
Rarefaction(2200 seq./sample)
Data analysis(Diversity, composition)
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0
500
1000
1500
2000
13 14 15 16 17 18Mean annual temperature (°C)
Estim
ated
OTU
rich
ness
No effect of rising MAT on OTU richness
No effect of rising MAT on phylogenetic diversity
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0
20
40
60
80
13 14 15 16 17 18Mean annual temperature (°C)
Phyl
ogen
etic
dive
rsity
No effect of rising MAT on composition at phylum level
0
25
50
75
100
13 13.8 15.1 15.5 16.1a 16.1b 16.7 17.3 18.2Mean annual temperature (°C)
Rel
ative
abu
ndan
ce (%
) PhylumProteobacteriaAcidobacteriaActinobacteriaChloroflexiCandidate WPS−2PlanctomycetesOther
Weak effect of rising MAT on OTU composition
R2 = 0.03, p = 0.07 (PERMANOVA)
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NMDS Axis 1
NM
DS
Axis
2
131415161718
MAT (°C)
Why do soil bacterial communities remain stable with rising MAT?
Increase in abundance
Increase in activity
Decrease in dormancy
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18.2 °C
17.3 °C16.7 °C
16.1 °C
16.1 °C15.5 °C
15.1 °C
13.8 °C13.0 °C
¯0 2 41 Kilometers
Forest Reserve
Natural Area Reserve
National Wildlife Refuge
Island of Hawaii
Conclusions
“Rising tide lifts all boats”
Warming alone may be insufficient to alter community structure
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18.2 °C
17.3 °C16.7 °C
16.1 °C
16.1 °C15.5 °C
15.1 °C
13.8 °C13.0 °C
¯0 2 41 Kilometers
Forest Reserve
Natural Area Reserve
National Wildlife Refuge
Island of Hawaii
@biogeocycle