Fungal feedbacks Fungal feedbacks on global changeon global change
Kathleen TresederKathleen TresederJennifer LansingJennifer Lansing
Nathan ChoiNathan ChoiUniv. of California Univ. of California
IrvineIrvine
Fungal communities shift in Fungal communities shift in response to environmental changeresponse to environmental change
Elevated COElevated CO22
Nitrogen depositionNitrogen deposition Plant distributionsPlant distributions DisturbanceDisturbance Land use changeLand use change
e.g. Grogan et al. 2000; Lilleskov et al. 2002
Fungal feedbacksFungal feedbacks
FungalFungalgroupsgroups
EcosystemEcosystemfunctionfunction
GlobalGlobalchangechange
Fungal feedbacksFungal feedbacks
FungalFungalgrowthgrowth
Soil COSoil CO22
releaserelease
GlobalGlobalwarmingwarming
+
+ +
Fungal feedbacksFungal feedbacks
Soil COSoil CO22
releaserelease
GlobalGlobalwarmingwarming
?
EctomycorrhizaeEctomycorrhizaeSaprotrophsSaprotrophs
?
?
Fungal feedbacksFungal feedbacks
Soil COSoil CO22
releaserelease
GlobalGlobalwarmingwarming
?
EctomycorrhizaeEctomycorrhizaeLignin degradersLignin degradersCellulose degradersCellulose degradersSugar degradersSugar degraders
?
?
Fungal feedbacksFungal feedbacks
Soil COSoil CO22
releaserelease
GlobalGlobalwarmingwarming
?
?
?
Warming Warming more more
pronounced pronounced at higher at higher latitudeslatitudes
John Walsh & Amanda LynchJohn Walsh & Amanda Lynch
°C
Forest fires increasing in Forest fires increasing in AlaskaAlaska
Kasischke & Stocks, 2000
Models: decomposition Models: decomposition increases in the first few increases in the first few decades after burningdecades after burning
Better conditions for Better conditions for decomposers?decomposers?
Fire scarFire scarMature forestMature forest
Does fire affect all fungal groups Does fire affect all fungal groups equally?equally?
Ectomycorrhizal fungiEctomycorrhizal fungi Saprotrophic fungiSaprotrophic fungi
HypothesesHypotheses
Fire alters the species composition of fungiFire alters the species composition of fungi Fungal species specialize in use of Fungal species specialize in use of
different organic compounds in the soildifferent organic compounds in the soil
Shifts in fungal community composition Shifts in fungal community composition may alter the decomposition rate of may alter the decomposition rate of different organic poolsdifferent organic pools
Fire chronosequenceFire chronosequence
3-yr 15-yr
47-yr80-yr
Experimental designExperimental design
Six 50-m long Six 50-m long transects in each transects in each sitesite
Surveyed each Surveyed each week during 2002 week during 2002 growing seasongrowing season
Collected 6,146 Collected 6,146 sporocarpssporocarps
Sporocarp biomass varied Sporocarp biomass varied among sitesamong sites
Time after burn (yr)
10 100
Spo
roca
rp b
iom
ass
(g m
-2)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
ab
b
a
b
P = 0.010
Species composition variedSpecies composition varied
Time after burn (yr)
10 100
Spo
roca
rp b
iom
ass
(g m
-2)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
ab
b
a
b
Site * species: P < 0.001
Fungal group
Ectomycorrhizal Saprotrophic
15N
of s
poro
carp
s (‰
)
-4
-2
0
2
4
6
8
10
1515N indicated ectomycorrhizal N indicated ectomycorrhizal versus saprotrophic speciesversus saprotrophic species
Cortinarius sp ACortinarius sp BCortinarius sp C
Hebeloma crustuliniformeLactarius torminosus
Leccinum insigneLeccinum scabrumRussula brevipes
Russula sp ARussula sp BRussula sp CRussula sp D
Gloeophyllum sepiariumLycoperdon spPsilocybe sp
P = 0.021
Ectomycorrhizal fungi peaked Ectomycorrhizal fungi peaked at intermediate successionat intermediate succession
Time after burn (yr)
10 100
Spo
roca
rp b
iom
ass
(g/m
2 )
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4Ectomycorrhizal (P = 0.011)Saprotrophic (NS)
Ectomycorrhizal fungi peaked Ectomycorrhizal fungi peaked at intermediate successionat intermediate succession
Time after burn (yr)
10 100
Spo
roca
rp b
iom
ass
(g/m
2 )
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 Ectom
ycorrhizal colonization (%
root length)
-10
0
10
20
30
40
50
60
Ectomycorrhizalroot colonization
Ectomycorrhizal (P = 0.011)Saprotrophic (NS)
Are saprotrophs specializing on Are saprotrophs specializing on different compounds?different compounds?
Time after burn (yr)
10 100
Spo
roca
rp b
iom
ass
(g/m
2 )
0.00
0.05
0.10
0.15
0.20
0.25
Saprotrophic (NS)
Approach: Radiocarbon isotopesApproach: Radiocarbon isotopes
Date
'55 '60 '65 '70 '75 '80 '85 '90 '95 '00 '05 0
200
400
600
800
1000
Atm
osph
eric
1
4C
(‰
)
Saprotrophs displayed Saprotrophs displayed widely different signatureswidely different signatures
14C (‰)
-100 -50 0 50 100 150 200
Num
ber
of s
peci
es
0
2
4
6
8
10
12
14
16
EctomycorrhizalSaprotrophic
0-2 y old C
7-16>50>50
3-6
Calculating abundance of Calculating abundance of different functional groupsdifferent functional groups
Ages of C used:Ages of C used: 0 to 4 years0 to 4 years 5 to 14 years5 to 14 years >50 years>50 years
Total sporocarp weight for each Total sporocarp weight for each functional groupfunctional group
Saprotrophic groups shifted Saprotrophic groups shifted across sitesacross sites
Time after burn (yr)
10 100
Spo
roca
rp b
iom
ass
(g m
-2)
0.00
0.03
0.06
0.09
0.12
0.15
0.18
RecalcitrantC users
IntermediateC users
Labile C users
Site * saprotrophic group: P < 0.001
Dead wood common in Dead wood common in younger sitesyounger sites
HypothesesHypotheses
Fire alters the species composition of Fire alters the species composition of fungifungi
Fungal species specialize in use of Fungal species specialize in use of different organic compounds in soildifferent organic compounds in soil
Shifts in fungal community composition Shifts in fungal community composition may alter the decomposition rate of may alter the decomposition rate of different organic poolsdifferent organic pools
HypothesesHypotheses
Fire alters the species composition of Fire alters the species composition of fungifungi
Fungal species specialize in use of Fungal species specialize in use of different organic compounds in soildifferent organic compounds in soil
Shifts in fungal community composition Shifts in fungal community composition may alter the decomposition rate of may alter the decomposition rate of different organic poolsdifferent organic pools
FireFire
OrganicOrganicmattermatter
SaprotrophicSaprotrophiccommunitycommunity
Decomposition Decomposition of available of available carbon poolscarbon pools
Host Host plant plant
growthgrowth
alteredshifted
EctomycorrhizalEctomycorrhizalabundanceabundance
+
+
projected
AcknowledgementsAcknowledgements
China Hanson Katie Turner Sue Trumbore Julianna Fessenden UC Davis Stable
Isotope Facility Keck AMS Facility,
UCI NSF (EAR-0433918,
DEB-0430111)
China Hanson Katie Turner Sue Trumbore Julianna Fessenden UC Davis Stable
Isotope Facility Keck AMS Facility,
UCI NSF (EAR-0433918,
DEB-0430111)
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