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Manuella Struckelj Hedi Kebli Suzanne Brais

Can partial harvesting in boreal mixedwoods maintain processes and fungal communities a ssociated with coarse woody debris ?. Manuella Struckelj Hedi Kebli Suzanne Brais. Acknowledgements. Presentation plan. Why deadwood? Hypotheses The Canadian boreal mixedwoods The SAFE project

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Manuella Struckelj Hedi Kebli Suzanne Brais

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  1. Can partial harvesting in boreal mixedwoods maintain processes and fungal communities associated with coarse woody debris? Manuella Struckelj Hedi Kebli Suzanne Brais

  2. Acknowledgements

  3. Presentation plan Why deadwood? Hypotheses The Canadian boreal mixedwoods The SAFE project Methods Deadwood dynamics and C pools Wood-inhabiting fungal community Conclusion

  4. Whydeadwood? • Supports more heterotrophic biomass and diversity than live trees; • Scarcity of dead organic matter in managed forests is the leading cause of decreases in species diversity • Contributes to the structural heterogeneity of the forest floor. • Long-term pool of carbon and nutrients.

  5. Hypotheses • Partial harvesting will maintain C pools and dynamics within the limits of those of natural stands. • By maintaining higher substrate availability, partial harvesting will mitigate the negative effects of harvesting on saproxylic fungal species richness and species composition.

  6. The Canadian boreal mixedwoods • Boreal mixedwoods are highly productive • More diverse than Fennoscandian boreal forests • Human impact relatively recent

  7. clearcut selectioncut clearcut clearcut softwooddominated stands mixed stands pionneerspecies hardwoods partial cut partial cut even-agedsilviculture fire fire Insectoutbreak insectoutbreak fire softwooddominated stands intoleranthardwoods mixed stands Time since last stand-replacingfire uneven-agedsilviculture Harvey et al. 2002

  8. Ecosystem-based silviculture in aspen-dominated stands (SAFE 1) Control Lowthin 31 % BA High thin 60 % BA Clearcut Control burn

  9. Monitoring C pools and fluxes

  10. Characterisation of wood-inhabiting fungi community • 191 logs (aspen) • 48 snags (aspen) • DNA extraction, cloning and sequencing • Snag and log characteristics • Stand deadwood volume

  11. Effects of partial and clear-cut harvesting on aboveground C pools associated with trees, snags, and downed logs. Live trees Snags Logs Time sinceharvesting

  12. Nine year cumulative C fluxes to dead organic matter associated with leaf litterfall and tree death.

  13. Effects of partial and clear-cut harvesting on decomposition of leaf litter and wood of trembling aspen.

  14. Effect of partial and clear-cut harvesting on C pools over a 9-year period following harvesting

  15. Harvesting prescriptions modifieddeadwoodcharacteristics Small logs Mid-decayed logs Welldecayed logs Large logs

  16. Fungal communities on aspen snags and logs • 35 different operational taxonomic units (OTU) were found on logs, 31 on snags. • Mean number of OTUs per log = 5.5 (maximum of 20) • Mean number on snags = 5.4 (maximum of 12) • Resiniciumbicolor and Phialophora sp. were found predominantly on snags • Athelianeuhoffii , Phellinuscinereus, Calocera cornea on logs

  17. Large logs had the highest rrichness and the effect was more pronounced in highly disturbed stands • Independent of harvesting intensity, large well-decayed logs (>10 cm) had the highest richness. • + nearly 2 OTUs (10%) compared to small mid-decayed logs • + 1.5 OTUs (7.5%) compared to large, mid-decayed logs Negative values indicate that fungal species richness was higher on small logs while positive values indicate that more OTUs were found on large logs.

  18. Conclusion • Carbon dynamics after partial cutting conserved many characteristics of natural stands • Partial harvesting prescription has incidence on deadwood abundance and recruitment • Wood inhabiting fungal community responds to changes in deadwood abundance and size distribution. The most severe disturbances affect fungal species richness • Specific objectives (recruitment, abundance, size) can be incorporated into partial harvesting prescriptions • Large logs can buffer adverse environmental conditions following disturbance

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