Carbon Exchange in Mountainous Regions

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 • SudeepSamanta, 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?