1. Detecting Thresholds How to detect thresholds? Major state changes (talik formation), first order understanding of ecosystem function (WT controls on peatland function), suggestions from models? Core datasets will need to be supplemented with experiments and more regional measurements Change relative to paleo-context v. important Climate sensitivity versus step-function threshold change Thresholds as change in rates (carbon accumulation, fire severity) step above normal variation or compared in gradients; Some thresholds could be reversible

2. “Hydrology” theme We focused on current research but also tasks for future proposal Drying/thawing across landscapes Obvious thresholds, drying ponds, dying birch forest in Tanana Flats, viability of white spruce Permafrost monitoring, historic locations where permafrost thawed like Healy site. Active layer/soil moisture/veg interactions Glacial melt as a driver of wetland hydrology

3. Metrics of State Change C14 (old carbon liberation) response SOM thresholds at which permafrost cannot be maintained, increased fire severity? Threshold SOM different (seedling, permafrost) Loss of keystone functional groups

4. Key Thresholds Identified (and ongoing LTER efforts) Permafrost change –Development of talik –Thermokarst –Erosion of old carbon –Fire as a driver of permafrost change Drying –Rainout shelter---decomposition, tree growth, threshold to viability of white spruce –water table manipulation at APEX –Snow exclusion experiments

5. More Integration Monthly talks Common approach across landscape units (wetlands, rainout shelter, snow exclusion experiments) Input from modelers, how are models using thresholds? Model needs for threshold information?

6. Monthly Talks Conceptual model: linkages permafrost, wildfire, SOM, hydrology (Jones) Hydrology manipulations and their usefulness for threshold studies (Valentine et al.) River stage/wetland formation, peat buffering river influence? (Jones and Turetsky) Permafrost driving variables and response (thresholds causing thresholds) (Schuur et al.) Loss of moss as potential threshold (rescheduled talk from Michelle, Teresa, Merritt)