Tuesday, June 19, 2012

Seeing the Unseen

Last April, our NGEE Arctic team obtained permafrost samples from multiple locations across the tundra. Those samples will be used to gain an indepth, mechanistic understanding of CO2 an CH4 fluxes from thawing soils. The Vegetation Dynamics team, led by Rich Norby, also requires soil samples for describing carbon-nitrogen interactions in the active layer with a special focus on root depth and distribution. There is an explicit interest in the NGEE Arctic project to link root structure and function to nitrogen and water uptake and acquisition. This information will, in turn, be used to more quantitatively characterize plant functional types for inclusion in advanced ecosystem and climate models.

Today, we took our first step in that direction by obtaining a few preliminary soil cores from the active layer as it now exists. Surprisingly, although it is the middle of June, the active layer is at best 15 centimeters; a mere 5 inches. Joanne Childs (ORNL) used a manual hammer sampler to take soil cores in wet and dry areas of the tundra. Those cores are full of old and new organic matter in the form of dead and live roots. We are going to ship these cores back to ORNL where Colleen Iversen will begin to develop sampling protocols for extracting roots for subsequent analysis and for subjecting soils at various depths to controlled temperature incubations. It will be from these incubations that we will get Information of root turnover times and the release of carbon and nitrogen during the decomposition process. Climate models need this information for different plant functional types and studies like this in the NGEE Arctic project will begin to provide those insights.