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Crossing the final ecological threshold in high Arctic ponds

How often and under what circumstances does wetland drying or thawing of permafrost cause a change in ecosystem state?. Crossing the final ecological threshold in high Arctic ponds. Smol and Douglas 2007 PNAS. Barber et al. 2004 Climatic Change. Klein et al. Can. J. For. Res. 2005.

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Crossing the final ecological threshold in high Arctic ponds

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  1. How often and under what circumstances does wetland drying or thawing of permafrost cause a change in ecosystem state?

  2. Crossing the final ecological threshold in high Arctic ponds Smol and Douglas 2007PNAS

  3. Barber et al. 2004Climatic Change

  4. Klein et al.Can. J. For. Res. 2005

  5. Burn, C. R. 2005 Permafrost and Periglac. Process.

  6. Yoshikawa and Hinzman 2003 Permafrost and Periglac. Process.

  7. Smith et al. 2005 Science “Disappearing Arctic Lakes”

  8. Riordan et al. JGR 2006

  9. Yoshikawa et al.2002JGR

  10. 15-June-1986 Image

  11. 16-June-2001 Image

  12. 1988 Burn

  13. 1988 Burn

  14. 25-June-2001

  15. 28-June-2005

  16. Consequences of a changing hydroclimate for organic-rich wetlands CZEN

  17. Climate Plant fixation and allocation Microbial metabolism Peat accumulation

  18. www.apex.msu.edu

  19. APEX Gradient sites Black Spruce Willow/Bog Birch Tussock Grass Emergent Rich fen

  20. www.apex.msu.edu Control Lowered Raised

  21. www.apex.msu.edu

  22. www.apex.msu.edu

  23. www.apex.msu.edu

  24. www.apex.msu.edu

  25. -10 -5 0 5 10 15 0 500 1000 1500 2000 www.apex.msu.edu Light response curves Raised Control NEE (mol m-2 s-1) Lowered PAR (mol m-2 s-1)

  26. www.apex.msu.edu • ET & plant responses to water table treatments

  27. Raised 400 Control Lowered 300 200 CH4 flux (mg m-2 d-1) 100 0 -70 -60 -50 -40 -30 -20 -10 0 10 Mean daily WT position (cm) Coupled carbon – water dynamics • CH4 flux sensitive to soil hydroclimate (Treat et al. in review) a 8 warming 7 no warming b 6 c 5 cd mol CH4 m-2 min-1 d 4 e 3 2 1 0 Control Lowered Raised

  28. 450 400 350 300 Annual organic matter storage (g organic matter m-2 yr-1) 250 200 150 100 0 50 100 150 200 250 Time since permafrost degradation Turetsky et al. 2006

  29. Methane Fluxes, 2003 1.0 Permafrost Plateau Thermokarst Edges 0.8 Thermokarst Wetlands 0.6 mmol CH4 m-2 hr-1 0.4 0.2 0.0 -0.2 3/20 4/9 4/29 5/19 6/8 6/28 7/18 8/7 8/27 9/16 10/6 *Each point is the mean ± one standard deviation of one to five measurements. Measurements on 3/25 were made in 2004. Wickland et al., 2006

  30. Water table position (cm) 0 0 0 0 - - - - 5 5 5 5 - - - - 10 10 10 10 - - - - 15 15 15 15 - - - - 20 20 20 20 - - - - 25 25 25 25 - - - - 30 30 30 30 - - - - 35 35 35 35 - - - - 40 40 40 40 1.0 1.0 1.0 0.9 0.9 0.9 0.9 Sphagnum poor fen, QB 0.8 0.8 0.8 0.8 0.7 0.7 0.7 0.7 0.6 Storage Coefficient 0.5 0.5 0.5 0.5 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.1 0.1 0.1 0.1 Brown moss rich fen, AK 0.0 0.0 0.0 0.0 Pristine Drained Wetland ecohydrology can be surprising • Vegetation -> peat properties -> hydrology Flashier!

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