1. How often and under what circumstances does wetland drying or thawing of permafrost cause a change in ecosystem state? 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 2007 PNAS

3. Barber et al. 2004 Climatic 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.

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

9. Riordan et al. JGR 2006

11. Yoshikawa et al.2002 JGR

14. 15-June-1986 Image

15. 16-June-2001 Image

17. 1988 Burn

19. 25-June-2001

20. 28-June-2005

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

25. Plant fixation and allocation Peat accumulation Climate Microbial metabolism

26. www.apex.msu.edu

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

28. LoweredControlRaised www.apex.msu.e du

33. NEE (mol m -2 s -1 ) PAR (mol m -2 s -1 ) Raised Control Lowered Light response curves

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

35. mol CH 4 m -2 min -1 0 1 2 3 4 5 6 7 8 ControlLoweredRaised c cd d e a b warming Coupled carbon – water dynamics CH 4 flux sensitive to soil hydroclimate (Treat et al. in review) no warming

38. 050100150200250 100 150 200 300 350 400 450 250 Annual organic matter storage (g organic matter m -2 yr -1 ) Time since permafrost degradation Turetsky et al. 2006

39. -0.2 0.0 0.2 0.4 0.6 0.8 1.0 3/204/94/295/196/86/287/188/78/279/1610/6 Permafrost Plateau Thermokarst Edges Thermokarst Wetlands mmol CH 4 m -2 hr -1 Methane Fluxes, 2003 *Each point is the mean ± one standard deviation of one to five measurements. Measurements on 3/25 were made in 2004. Measurements on 3/25 were made in 2004. Wickland et al., 2006

40. Flashier! Wetland ecohydrology can be surprising Vegetation -> peat properties -> hydrology