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Plant – soil food web interactions and
climate change
Franciska T. de Vries
Outline
1. Soil food webs and aboveground-belowground linkages
2. Land use impacts on soil food webs and their functioning
3. Resistance and resilience of soil food webs to climate
change
4. Conclusions and outlook
Linkages between plants and soil organisms
Wardle et al. 2004. Science 304, 1629-1633
The detritus soil food web
mites and
Collembola
fungi
fungalfeeding
nematodes
Fungal
decomposition
pathway
predatory
mites
organic
matter
bacteria
bacterialfeeding
nematodes
earthworms
protozoa
omnivorous
and
predatory
nematodes
Bacterial
decomposition
pathway
Aboveground – belowground linkages
Intensity of management
Fast
Fast growing,
growing, short
short lived
lived
High
High N
N uptake
uptake
High
High litter
litter quality
quality
Slow
Slow growing,
growing, long
long lived
lived
Low
Low N
N uptake
uptake
Low
Low litter
litter quality
quality
Plants
Bacterial-dominated
Bacterial-dominated soil
soil
food
food web
web
Fungal-dominated
Fungal-dominated soil
soil
food
food web
web
Food web
Rapid
Rapid decomposition
decomposition
and
and mineralization
mineralization
Low
Low soil
soil CC sequestration
sequestration
High
High N
N supply
supply rates
rates
Low
Low potential
potential plantplantmicrobial
microbial associations
associations
Slow
Slow decomposition
decomposition and
and
mineralization
mineralization
High
High soil
soil CC sequestration
sequestration
Low
Low N
N supply
supply rates
rates
High
High plant-microbial
plant-microbial
associations
associations
Processes
Restoration management
Modified after Wardle et al., 2004
Science 304, 1629-1633
Linkages between plant traits and microbial communities
across spatial scales
A. Individual plant level
Orwin et al. 2010. J. Ecol 98:1074-1083.
B. Community/landscape-level
De Vries et al. 2012, in review
Microbes control N form and availability in soil
De Vries and Bardgett 2012. Frontiers in Ecology and the Environment, in press.
Background painting Tiny van Velzen
Reduced N leaching with higher fungal biomass
7
4.0
3.5
Improved
3.0
Unimproved
6
5
2.5
4
2.0
3
1.5
2
1.0
0.5
1
0.0
0
0
0.05
0.1
F/B ratio
0.15
0
2
4
6
8
10
Fungal PLFA (nmol g-1)
Smaller amount of 15N leached with greater F/B ratio
Microbial community immobilises more 15N if more fungi present
De Vries, Bloem, Quirk, Stevens, Bol, and Bardgett, in review
Potential threats to soil biodiversity
“…a preliminary assessment of
where soil
biodiversity is threatened. This
includes areas of high population
density and/or
intense agricultural activity (e.g.
cereals and industrial crops,
animal husbandry,
greenhouses, fruit orchards,
vineyards and horticulture).”
From: The implementation of
the Soil Thematic Strategy and
ongoing activities, 13 February
2012, EC report
EU 7th Framework SOILSERVICE project
Land use impacts on soil food webs and their
functioning across Europe
5 farms in each country
3 intensities
High – wheat rotation
Czech Republic (CZ)
Greece (GR)
Sweden (SE)
England (UK)
Increasing
temperature
Medium – bean rotation
Low – permanent grassland
Increasing
rainfall
Land use effects on soil food webs
- Fungal energy channel more
vulnerable to agricultural
management
- Fungal energy channel biomass
increases with organic matter
De Vries, Thébault, Liiri, Birkhofer et al. in prep.
Links between soil food webs and ecosystem services
Bacterial decomposition channel linked to increased N mineralisation and leaching
AM fungi linked to reduced N leaching
De Vries, Thébault, Liiri, Birkhofer et al. in prep.
Land use impacts on soil food webs are consistent
across Europe:
1.Intensive management reduces biomass and
diversity
2.Fungal decomposition pathway more vulnerable
Bacterial decomposition channel linked to increased
N leaching
Does this have consequences for ecosystem
functioning under climate change?
Impacts of climate change
CLIMATE CHANGE
Direct feedback
Indirect feedback
Temperature
Extreme events
Elevated CO2
Temperature/precipitation
Net Primary
Production
Litter
DOC
CO2
Autotrophic
respiration
Nutrient cycle
feedback
Rhizodeposits
Heterotrophic
respiration
Microbial biomass
Soil fauna
SOIL ORGANIC MATTER
Bardgett et al. (2008) The ISME Journal 2:805-814.
Increased frequency of extreme weather events drought followed by heavy rainfall
-disrupts soil structure
-kills microbes and soil fauna
→ loss of functional stability
increased losses of C and N
Effects of field drought on food webs
Wheat
Control
Grass
Drought
Control
Drought favours the fungal decomposition pathway
Drought
Soil food web resistance to glasshouse-based drought
Resistance of grassland soil food web increases after field drought
Grassland microarthropods more resistant to drought
Fungal decomposition channel more resistant to drought than bacterial
decomposition channel
De Vries, Liiri, Bjørnlund, Bowker, Christensen, Setälä, and
Bardgett 2012. Nature Climate Change 2:276-280
Soil food web and ecosystem functioning (day 1)
-0.17
N2O
production
-0
.0
3
-0.14P = 0.04
1
4
0.0
0 .0 0
R2 =0.02
Respiration
1
0
.
-0
0 .1
PLFA
evenness
0.51 P<0.001
6
0.0
7
0
-0.
-0.13
0.08
Microarthropod
richness
F/B channel
ratio
R2 =0.32
-0.26P =0.03
Respiration strongly controls N cycling
F/B channel ratio mitigates CO2 flush
Microbial evenness controls N leaching
-0.39 P <0.001
R2 =0.02
R2 =0.25
Total N
leached
De Vries, Liiri, Bjørnlund, Bowker, Christensen, Setälä, and
Bardgett 2012. Nature Climate Change 2:276-280
Fungal-based soil food webs more resistant and better
able to adapt to drought
Soil food web controls ecosystem functioning:
-C and N losses less affected by drought in fungal-based
soil food webs
Legacy effects of drought on plant growth
4
3.5
3
2.5
2
1.5
no plants
1
plants
0.5
0
C
D
Control
C
D
Field
drought
Wheat
C
D
Control
C
D
Field
drought
Grass
Drought increased plant growth
Presence of a plant increased DOC leaching (but reduced
N leaching)
De Vries, Liiri, Bjørnlund, Setälä, Christensen, and Bardgett
2012. Oecologia, in press
Legacy effects of drought on soil food webs
Wheat
Grass
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
-0.2
-0.2
-0.4
-0.4
-0.6
-0.6
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
-0.2
-0.2
-0.4
-0.4
-0.6
-0.6
No plant
Plant
Field control
Field drought
No plant
Plant
Wheat plant increases recovery of fungal- and bacterial-feeding
nematodes
De Vries, Liiri, Bjørnlund, Setälä, Christensen, and Bardgett
2012. Oecologia, in press
Recovery of the soil food web linked to soil C availability
Plants can affect the recovery of soil organisms through
their belowground C inputs
De Vries, Liiri, Bjørnlund, Setälä, Christensen, and Bardgett
2012. Oecologia, in press
Conclusions
Plants and soil food webs tightly linked:
•Plant traits explain microbial communities on a landscape scale
•Belowground plant inputs govern response to drought
Intensive agriculture reduces diversity and biomass of the soil food
web, and causes a shift towards more bacterial-based soil
communities, with implications for ecosystem functioning!
Fungal-based food webs deliver ecosystem services:
•They reduce N losses from soil;
•They are more resistant to drought
•C-rich soils have greater recovery after drought
Can we promote fungal-based food webs to make agriculture more
sustainable?
Conclusions
Management options to promote fungal-based food webs:
De Vries and Bardgett 2012. Frontiers in Ecology and the Environment, in press
Richard Bardgett
Jake Bishop
Lisa Bjornlund
Jaap Bloem
Roland Bol
Matt Bowker
Soren Christensen
Tina d’Hertefeld
Cristina Escolar
Lena Folkvard Petersen
Katarina Hedlund
Mira Liiri
Marina Louzada
Pete Manning
Simon Mortimer
Helen Quirk
Heikki Setälä
Annette Spangenberg
Carly Stevens
Elisa Thébault
Nicola Thompson
Lorna Trimnell
Louise Walker
Victor van Velzen
Meint Veninga
An Vos
All SOILSERVICE project
partners