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)