Wednesday, June 20, 2012

Root Depth and Distribution

Victoria Sloan, a post-doctorate research associate at ORNL working on the NGEE Arctic project with Rich Norby, has a keen interest in how plant species differ in their rooting depth and distribution. Victoria joins us from Sheffield University in the UK where she worked on her PhD as a member of a team studying plant distribution, leaf and root turnover times, and carbon cycle processes in Sweden and Finland.

Yesterday, Victoria spent her day identifying plant species in the vicinity of our field plots. She brings a good working knowledge of species distribution and associated characteristics to the project. Because it is still early in the season, the main plant species actively growing are sedges and grasses in the wetter areas of the tundra. Victoria took the opportunity to carefully excavate a few root systems and examine them for root length, root size, degree of suberization, and branching patterns. Although her sample size was admittedly small, the differences between species were fairly marked. Some species had long white roots with little branching, while others were dark and highly branched and fibrous. It is still far too early to draw any conclusions but ideas and hypotheses are many.

Our goal in looking at how rooting depth and distribution varies by species is to relate this variation to water and nutrient acquisition strategies. If we can do that, then we have a good opportunity to incorporate this into our descriptions of plant functional types and further into models. We have a lot of fundamental biology to conduct, however, before we can make those associations. Victoria will dedicate a lot of her summer to measurements in support of this goal, as will Colleen Iversen (ORNL) and others. The team at LANL will be especially engaged as we look at stable isotopes and what they can tell us about water, carbon, and nitrogen processes in these Arctic plant communities. The LANL team is developing their sampling strategy now in preparation for a trip to Barrow later in the summer.