Techniques to evaluate diurnal and seasonal carbon budgets of the western montane region

Montane coniferous forests are responsible for a large percentage of the carbon uptake in the Northern Hemisphere.  Unfortunately, the rugged terrain and climatic dynamics of high altitude forests makes precise measurements of net ecosystem productivity (NEP) difficult to obtain.  Recent research using the SiPnET model has refined our understanding of the processes regulating these complex systems. Current simulations are "data constrained" to areas that have climatic and flux tower data.  The method we propose is to use the general biogeochemical Daycent model and satellite-based MODIS gross primary production estimates (GPP) to provide constrained inputs for SiPnET, and expand the model to a regional level estimation of NEP.  The Daycent model has been tested against many soil and plant systems so this technique would be applicable to areas larger than current flux tower coverage. This will allow us the evaluate ecosystem feedback to the atmosphere which incorporates disturbance, land use and climate effects. We currently estimate that forested systems represent approximately 2 million metric tons (MMT) carbon sink with grassland and woodlands contributing approximately 0.2 MMT.  Niwot ridge flux tower data and climate data is used for data assimilation and is tested against other tower sites at Storm Peak and Fraiser Experimental Forest. New data modeling techniques described here will aid in accessing the carbon budgets for regional areas and across multiple plant functional types.