1. Carbon Exchange in Mountainous Regions NACP Breakout Session I Wed. 18 Feb 2009, 3:00 pm - 4:30 pm Terrace Salon Three Chair: Ankur Desai, U. Wisconsin

2. Background Large ecosystem pressures in North American Mountain regions – Rapid climate warming at high elevation Increasing drought length and severity Changes in intensity/frequency of fire Increase in range of pests and invasives – Land use change from forestry and population growth Poor constraint on biogeochemical cycling in mountains and complex terrain in general – Untested assumptions that high elevation NEE is near 0 – Yet, mountains contain significant fraction of forest in U.S. – Methodological limitations for flux towers, remote sensing, ecosystem models, inversions, inventories, and ecological methods

4. Questions Challenges – What is the state of the science on mountain carbon exchange? – What is our predictive ability on ecosystem responses to large-scale disturbance, climate range shifts, and elevation specific processes? Opportunities – What are the opportunities for NACP to improve observations, models, and decision support in North American mountain regions?

5. Participants Ankur Desai, UW-Madison, Atmospheric & Oceanic Sciences Jeff Hicke, U. Idaho, Geography John Bradford, USFS Northern Res. Station Brian McGlynn, Montana State Diego Riveros-Iregui, U. Colorado Betsy Failey, U. Colorado Sudeep Samanta, Woods Hole Research Center Don McKenzie, USFS / U. Washington

6. Challenges Terrain creates a compression of environmental gradients – Makes interpolation/upscaling particularly difficult – But easier to assess effects of gradients in drivers in experimental studies Disturbance strongly interacts with terrain – Fire, pest, species spread are all elevation sensitive Lateral processes can matter more than in flat areas – Hydrology has an overarching role in carbon cycling in terrain. 1-D ecosystem models are likely to miss this. Mesoscale and microscale flows are prevalent – Increases uncertainty in observations such as flux-towers (cold air drainage) and tracer transport models and interpolation of surface meteorology Slope and aspect variations affects canopy radiative transfer – Increased uncertainty in remotely sensed data and models Difficulty of access for field-based study – Sparse data leads to extemporaneous extrapolation – Carbon, land, and fire management are particularly difficult but need is high

7. Opportunities Synthesis of ongoing projects – e.g., ORCA, ACME, BEACHON – Assessment of state of the science – data, projects, literature – Uncertainty in regional NEE – Development of an NCEAS Working Group? MCI-West, where everything can go wrong? – How wrong can we be in terms of NACP goals at the subregional scale? Intermountain West (AK->Mexico)? West Coast? Rapid response intensive to episodic extreme disturbance events? – Lack of understanding of post-disturbance carbon dynamics, especially after large events – Ongoing bark beetle damage could possibly have large effect/add uncertainty on future carbon cycling in North America Data product and model improvement – Maps of meteorological drivers (slope/aspect corrections) – Assessment of high elevation carbon stocks – Transport model uncertainty – Carbon-water coupling and lateral flows in ecosystem models – Carbon cycle response to fire and insects

8. Thanks More information contact: – Ankur Desai – desai@aos.wisc.edu

10. Challenges – Carbon management at fine scales? Forest management, fire control overlap – Are our data representative of all kinds of mountain systems? – We may have data, but even so, we lack process understanding for some systems Microclimate variation and substrate variation Disturbance – drought, fire, insects, harvest? Species shift – done a good bit (maybe), but extrapolation problem – key for forest management and future carbon cycle Modes of spatial hetereogeneity, ways to scale What drivers/processes are elevation, slope, aspect dependent Spatial linkages (lateral) matter more that flat terrain?

11. Charge to Breakout in ~80 minutes: – Highlight state of the science on carbon exchange in mountain regions (globally and North America) What do we know? – Discuss methodological and theoretical challenges to diagnosing and predicting carbon exchange in terrain What don’t we know? – Identify opportunities for future NACP diagnosis, attribution, prediction, decision support in mountain regions What would we like to do?