Scott Peckham will present a poster at the 4th Global Vegetation Workshop hosted by the Numerical Terradynamic Simulation Group at the University of Montana in June, 2009.

The Carbon Model group assembled a new Xgrid of 10 quad-core dual Xeon Xserves that will be dedicated to Biome-BGC computing. The cluster provides a combined CPU of 240 GHz with 30 TB of RAID and 320 GB of combined RAM connected at Gigabit speed. And, it does so at a total peak power consumption of 7,500 Watts. In other words, about 2.5 times the power of the previous cluster of 25 older Xserves at about 60% of power consumption.

Changes in fire regimes are driving the carbon balance of much of the North American boreal forest, but few studies have examined fire-driven changes in evapotranspiration (ET) at a regional scale. This study used a version of the Biome-BGC process model with dynamic and competing vegetation types, and explicit spatial representation of a large (106 km2) region, to simulate the effects of wildfire on ET and its components from 1948 to 2005 by comparing the fire dynamics of the 1948-1967 period with those of 1968-2005. Simulated ET averaged, over the entire temporal and spatial modeling domain, 323 mm yr-1; simulation results indicated that changes in fire in recent decades decreased regional ET by 1.4% over the entire simulation, and by 3.9% in the last 10 years (1996-2005). Conifers dominated the transpiration (EC) flux (120 mm yr-1) but decreased by 18% relative to deciduous broadleaf trees in the last part of the 20th century, when increased fire resulted in increased soil evaporation, lower canopy evaporation, lower EC, and a younger and more deciduous forest. Well- and poorly drained areas had similar rates of evaporation from the canopy and soil, but EC was twice as high in the well-drained areas. Mosses comprised a significant part of the evaporative flux to the atmosphere (22 mm yr-1). Modeled annual ET was correlated with net primary production, but not with temperature or precipitation; ET and its components were consistent with previous field and modeling studies. Wildfire is driving significant changes in hydrological processes by affecting mean stand age, forest species, and energy balance. These changes, particularly in poorly drained areas, may control the future carbon balance of the boreal forest.

Bond-Lamberty, Ben, Scott D. Peckham, Stith T. Gower and Brent E. Ewers. 2009. Effects of fire on regional evapotranspiration in the central Canadian boreal forest. Global Change Biology.
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Bryophytes are the dominant ground cover vegetation layer in many boreal forests and in some of these forests the net primary production of bryophytes exceeds the overstory. Therefore it is necessary to quantify their spatial coverage and species composition in boreal forests to improve boreal forest carbon budget estimates. We present results from a small exploratory test using airborne lidar and multispectral remote sensing data to estimate the percentage of ground cover for mosses in a boreal black spruce forest in Manitoba, Canada. Multiple linear regression was used to fit models that combined spectral reflectance data from CASI and indices computed from the SLICER canopy height profile. Three models explained 63-79% of the measured variation of feathermoss cover while three models explained 69-92% of the measured variation of sphagnum cover. Root mean square errors ranged from 3-15% when predicting feathermoss, sphagnum, and total moss ground cover. The results from this case study warrant further testing for a wider range of boreal forest types and geographic regions

Peckham, Scott D., Douglas E. Ahl and Stith T. Gower. 2009. Bryophyte cover estimation in a boreal black spruce forest using airborne lidar and multispectral sensors. Remote Sensing of Environment.

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