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Litterfall and soil respiration fluxes in the MELNHE study. Thomas Mann

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Litterfall and soil respiration fluxes in the MELNHE study. Thomas Mann

  1. 1. Litterfall and soil respiration fluxes in the MELNHE study Thomas Mann, Ruth Yanai, Tim Fahey, Melany Fisk
  2. 2. N P P P N Allocation of resources
  3. 3. N N N P P P N P N P N P N P N P N P N Allocation of resources
  4. 4. How are soil respiration and litterfall controlled by nutrient availability?
  5. 5. Hypotheses ● N addition will lower soil respiration ● N and P addition will increase litterfall mass
  6. 6. Methods Soil respiration (2008-2019) ● Soil CO2 fluxes are measured at 5-7 locations within each treatment plot across all 13 stands Litterfall mass (2008-2019) ● Fine litter (excluding twigs) is collected from 5 litter baskets placed in each treatment plot of every stand
  7. 7. Results Pre-treatment ○ Soil respiration was lowest in N- rich sites Image source: Bae et al., 2015
  8. 8. Results Pre-treatment ○ Soil respiration was lowest in N- rich sites Image source: Kang et al., 2016 2011-2013 ○ N addition lowered soil respiration in N-poor sites
  9. 9. Adj R2: 0.5822
  10. 10. Adj R2: 0.6074
  11. 11. Adj R2: 0.2631
  12. 12. Adj R2: 0.2359
  13. 13. Conclusions ● Apparent trends ○ Soil respiration may not have responded to nutrient additions ○ Fertilization effects on litterfall may be complicated! ● Next steps ○ Statistical analysis ○ Explore explanations for lack of treatment effect on soil respiration ■ Consider N mineralization and pretreatment fertility ■ Uncertainty analysis
  14. 14. Questions, comments, or suggestions are welcome! Please feel free to email me at thmann@esf.edu. Many thanks to the dozens of folks who have been involved in the collection, processing, and analysis of this data over the history of the MELNHE project! The MELNHE Project is funded by USDA NIFA (2019-67019-29464) and NSF (DEB- 1637685) . For more information, please visit www.esf.edu/melnhe

Editor's Notes

  • Pre-treatment
    Soil respiration was lowest where N mineralization and net nitrification were highest (p<0.05) (Bae et al., 2015)

    2011-2013
    Overall, no significant effect of N or P addition
    Soil respiration was significantly lowered by nutrient addition in N-poor sites
  • Pre-treatment
    Soil respiration was lowest where N mineralization and net nitrification were highest (p<0.05) (Bae et al., 2015)

    2011-2013
    Overall, no significant effect of N or P addition
    Soil respiration was significantly lowered by nutrient addition in N-poor sites

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