1. Land Management, Mycorrhizal Diversity, and Soil Carbon Sequestration
Mark Hunter & Tim James
Ecology & Evolutionary Biology

2. Background & Premise
Ongoing paradigm shift in understanding the origin of soil carbon stocks
Declining focus on the “recalcitrance” of leaf litter inputs (Schmidt et al. 2011, Lehman & Kleber 2015)
Increasing focus on root and (especially) microbial inputs in generating soil organic matter

3. Roots & Fungi
Roots and mycorrhizal fungi appear to drive long-term carbon sequestration in boreal forest soils (Clemmensen et al. 2013)
Increasing carbon storage with forest age appears related to changes in mycorrhizal fungal community composition (Clemmensen et al. 2015; Kyaschenko et al. 2017)
Precise mechanisms and generality across ecosystems remain controversial (Averill et al. 2014; Terrer et al. 2016; Norby et al. 2017; Pellitier & Zak 2017)

4. Our Big Questions
What are the relationships among mycorrhizal abundance, mycorrhizal diversity, mycorrhizal identity and soil carbon storage?
Do forest management practices differ in their potential to store carbon in soils based on their mycorrhizal communities?

5. General Methods
Field sampling of soils and their associated mycorrhizal communities in red pine and mixed hardwood forests under different management practices in the Great Lakes Region
Literature search to assess the state of knowledge on land management, mycorrhizal fungi, and carbon sequestration

6. Field Methods
Sampled 3 old growth red pine stands and 4 red pine plantations (dating from 1930s)
Sampled 3 stands each of 3 hardwood management regimes (established 1951)
Extensive extraction, leaving 60 sq feet/acre
Medium extraction, leaving 75 sq feet/acre
Unmanaged since 1905 clearcut

7. 3 horizons x 5 cores x 16 forest stands = 240 soil samplesOa
30 cm
12.5m E
5 cm B
3 horizons x 5 cores x 16 forest stands = 240 soil samples
(actually 205 after accounting for some missing horizons)

8. Soil Chemistry
Soil carbon
Soil nitrogen
Chitin
Ergosterol

9. Red Pine Plantations Favor Deeper Soil Carbon Stores
Mixed Model Interaction F2,94 = 4.39, P = 0.015
(Forest Type Main Effect F1,94 = 2.82, P = 0.096)

10. Red Pine Plantations Also Favor Deeper Soil Nitrogen Stores
Mixed Model Interaction F2,94 = 7.34, P =
(Forest Type Main Effect F1,94 = 3.74, P = )

11. Soil Chitin Concentrations Follow Patterns of Carbon Sequestration
Management Main Effect F1,97 = 3.30, P =0.072

12. Soil Chitin Concentrations Follow Patterns of Carbon Storage
REGRESSION F1,97 = 43.29, P <

13. Harvesting Rate of Hardwoods Does Not Influence Soil Carbon Stores
Mixed Model Management F2,84 = 0.33, P = 0.723
High rate leaves 60 sq feet remaining/acre
Medium rate leaves 75 sq feet remaining/acre

14. Harvesting Rate of Hardwoods Does Not Influence Soil Nitrogen Stores
Mixed Model Management F2,84 = 1.07, P = 0.349
High rate leaves 60 sq feet remaining/acre
Medium rate leaves 75 sq feet remaining/acre

15. Patterns of Diversity and Identity of the Soil Fungi

16. In Red Pine Stands, Fungal Diversity Declines With Soil Depth and is Lower in Plantations than in Old Growth
Observed OTUs
Management:
p = e -7, F=
Horizon:
p = e -07, F=
Management*Horizon:
p = , F =
O/A

17. In Hardwood Stands, Soil Fungal Diversity is Highest in the O/A Soil HorizonB B
Observed OTUs
Management:
p = , F =
Horizon:
p =4.446e-6, F =
Management*Horizon:
p = , F =
O/A

18. Fungal Community Composition Is More Closely Associated With Soil Carbon Stores

19. The Structure of Soil Fungal Communities Varies Markedly Between Pines and Hardwoods
= Conifer
= Deciduous

20. Within Pine Stands, Soil Fungal Communities Vary With Stand Management and Soil Horizon
O/A
Management
PERMANOVA:
p = 0.001, F=
Horizon
p = 0.001, F=3.5385

21. Red Pine Plantations Host a Higher Percentage of Ectomycorrhizal Fungi Than Do Old Growth Stands

22. The Higher Percentage of Ectomycorrhizal Fungi in Plantation Soils Holds Across Soil Horizons
Management:
p =
F =
Horizon:
p =
F =
Management * Horizon:
p = , F =
O/A

23. Within Hardwood Stands, Soil Fungal Communities Vary With Stand Management and Soil Horizon
PERMANOVA:
p = 0.001, F=
Horizon
p = 0.001, F=3.4811

24. Carbon Storage is Linked to Fungal Community Composition in Hardwood Forests
PCoA1 F1,92 = 92.35, P<0.0001
PCoA2 F1,92 = 8.89, P=0.0037
Model r-sqd = 0.52

25. Low Values of both PCoA 1 and PCoA 2 are Associated with High Soil Carbon
PCoA1 F1,92 = 92.35, P<0.0001
PCoA2 F1,92 = 8.89, P=0.0037
Model r-sqd = 0.52

26. In Hardwood Stands, the Percentage of Ectomycorrhizal Fungi Declines Under High Rates of Timber Extraction

27. The Lower Percentage of Ectomycorrhizal Fungi Under High Timber Extraction Holds Across Soil Horizons
Management:
p = , F =
Horizon:
p = , F =
Management * Horizon:
p = , F =
O/A

28. Overall Conclusions
Pine plantations may provide a suitable tool for soil carbon storage
Their soil carbon stocks correlate positively with chitin (a fungal biomarker) and with the percentage of ectomycorrhizal taxa in samples
In hardwood stands, fungal community composition is a strong predictor of soil carbon stocks
Moreover, representation by ectomycorrhizal fungi appears depressed under high rates of timber removal, although effects on C stocks are unclear

29. Plenty Left to Do!
We have many analyses still to run at finer levels of resolution
We want to develop an international network of colleagues who are exploring relationships among fungal community composition and C storage
We want to expand our ecosystem management comparisons

30. Thanks!
Energy Institute
Lucas Michelotti
Hillary Streit

32. Management Has No Significant Effect on the Thickness of Soil Horizons
Red Pine
Hardwoods

33. Conifer taxonomy: Order

34. Deciduous taxonomy: Order

35. Conifer taxonomy: Class

36. Deciduous taxonomy: Class