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Fungal feedbacks on global change Kathleen Treseder Jennifer Lansing Nathan Choi Univ. of California Irvine.

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Presentation on theme: "Fungal feedbacks on global change Kathleen Treseder Jennifer Lansing Nathan Choi Univ. of California Irvine."— Presentation transcript:

1 Fungal feedbacks on global change Kathleen Treseder Jennifer Lansing Nathan Choi Univ. of California Irvine

2 Fungal communities shift in response to environmental change Elevated CO 2 Elevated CO 2 Nitrogen deposition Nitrogen deposition Plant distributions Plant distributions Disturbance Disturbance Land use change Land use change e.g. Grogan et al. 2000; Lilleskov et al. 2002

3 Fungal feedbacks Fungalgroups Ecosystemfunction Globalchange

4 Fungalgrowth Soil CO2 release Globalwarming + + +

5 Fungal feedbacks ? EctomycorrhizaeSaprotrophs ? ?

6 ? Ectomycorrhizae Lignin degraders Cellulose degraders Sugar degraders ? ?

7 Fungal feedbacks Soil CO2 release Globalwarming ? ? ?

8 Warming more pronounced at higher latitudes John Walsh & Amanda Lynch °C

9 Forest fires increasing in Alaska Kasischke & Stocks, 2000

10 Models: decomposition increases in the first few decades after burning

11 Better conditions for decomposers? Fire scar Mature forest

12 Does fire affect all fungal groups equally? Ectomycorrhizal fungi Saprotrophic fungi

13 Hypotheses Fire alters the species composition of fungi Fire alters the species composition of fungi Fungal species specialize in use of different organic compounds in the soil Fungal species specialize in use of different organic compounds in the soil Shifts in fungal community composition may alter the decomposition rate of different organic pools Shifts in fungal community composition may alter the decomposition rate of different organic pools

14 Fire chronosequence 3-yr15-yr 47-yr80-yr

15 Experimental design Six 50-m long transects in each site Six 50-m long transects in each site Surveyed each week during 2002 growing season Surveyed each week during 2002 growing season Collected 6,146 sporocarps Collected 6,146 sporocarps

16 Sporocarp biomass varied among sites

17 Species composition varied Site * species: P < 0.001

18 15 N indicated ectomycorrhizal versus saprotrophic species Cortinarius sp A Cortinarius sp B Cortinarius sp C Hebeloma crustuliniforme Lactarius torminosus Leccinum insigne Leccinum scabrum Russula brevipes Russula sp A Russula sp B Russula sp C Russula sp D Gloeophyllum sepiarium Lycoperdon sp Psilocybe sp P = 0.021

19 Ectomycorrhizal fungi peaked at intermediate succession

20

21 Are saprotrophs specializing on different compounds?

22 Approach: Radiocarbon isotopes Atmospheric  14 C (‰)

23 Saprotrophs displayed widely different signatures

24 Calculating abundance of different functional groups Ages of C used: Ages of C used: 0 to 4 years 0 to 4 years 5 to 14 years 5 to 14 years >50 years >50 years Total sporocarp weight for each functional group Total sporocarp weight for each functional group

25 Saprotrophic groups shifted across sites

26 Dead wood common in younger sites

27 Hypotheses  Fire alters the species composition of fungi  Fungal species specialize in use of different organic compounds in soil  Shifts in fungal community composition may alter the decomposition rate of different organic pools

28 Hypotheses  Fire alters the species composition of fungi  Fungal species specialize in use of different organic compounds in soil  Shifts in fungal community composition may alter the decomposition rate of different organic pools

29 Fire OrganicmatterSaprotrophiccommunity Decomposition of available carbon pools Host plant growth altered shifted Ectomycorrhizalabundance + + projected

30 Acknowledgements China Hanson Katie Turner Sue Trumbore Julianna Fessenden UC Davis Stable Isotope Facility Keck AMS Facility, UCI NSF (EAR , DEB ) China Hanson Katie Turner Sue Trumbore Julianna Fessenden UC Davis Stable Isotope Facility Keck AMS Facility, UCI NSF (EAR , DEB )


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