Carbon Exchange in Mountainous Regions

NACP Breakout Session IWed. 18 Feb 2009, 3:00 pm - 4:30 pm

Terrace Salon ThreeChair: Ankur Desai, U. Wisconsin

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

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?

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

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

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

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

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?

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?