Last Day in Barrow

It has been a great 10 days spent first at the NASA-sponsored ABoVE workshop, and then in Barrow for field research. I am confident that we have both a strong team and a great set of collaborators.

This week in Barrow, the NGEE Arctic accomplished many things thanks to the efforts of those from our vegetation dynamics and biogeochemistry teams. We had established scientists, post-docs and students working together to conduct measurements of plant community composition; analyses of plant gas exchange; root depth and distribution surveys; leaf area assessments; soil CO2 and CH4 determinations; and more. We were able to lay out trail mat so that we have a good start on the infrastructure required to support the science goals of the project. And, thanks to Mark Ivey, we have lab space in the BARC building and, as a result, we can develop more sophisticated techniques with which to tackle the complex and interconnected questions of the project. This will all be required if we are to model the dynamic evolution of the Arctic landscape for inclusion into Earth System Models.

While our week was a busy one, we did take time today to participate in one of the Nalukataq's held in Barrow during June. Two whaling crews, Yugu and Savik, hosted a village-wide festival to celebrate their respective successes during the Spring whaling season.

These events are a time when the crews and their families can be recognized for their hard work and, more importantly, when the crews can share a portion of the harvest with the local community. Members of the Yugu and Savik crews served coffee, tea, soups, and meat dishes as families exchanged greetings and the children played. It was a very festive environment and the local natives were quick to include us in discussions and descriptions of the various events. I spoke with a former whaling captain and heard many stories about the importance of whaling to the Inupiat people.

Finally, I found the brightly colored clothing most impressive. The women, in particular had elaborate coats with intricate decorations from beads and various furs from the North Slope region. The kids especially seemed to enjoy the event, including the traditional blanket toss. Alistair, Margaret, Victoria, Melanie and I sampled several of the offerings; the tea and soup helped keep us warm as wind chill temperatures dipped into the thirties due to a strong wind.

The Nalukataq will last all day with various activities. Tonight there will be Eskimo dancing in the community center. Unfortunatel,y I will be departing Barrow in just a few hours so the celebration will have to wait until I return again in July. For now, it was a scientifically productive trip and personally enjoyable. The people who are working with me on the NGEE Arctic project are a pleasure to associate with, as are the people and culture of Barrow.

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.

Physiological ecology and plant functional types

As a physiological ecologist, the NGEE Arctic science question that is especially exciting to me is one related to plant functional types and the way climate models represent vegetation dynamics. We know that plant composition differs by position on the landscape, for example rims and troughs of low- and high-centered polygons, but the controls on this dynamic are unclear. Our team plans to address this question by focusing on water and nutrient acquisition strategies and by understanding how this translates to critical carbon cycle processes for plants and plant communities across the tundra.

It was, therefore, great to have Alistair Rogers (BNL) bring his photosynthesis system to Barrow this week. In a preliminary test of this apparatus, Alistair and Victoria Sloan gathered leaves from various plant species and subjected them to measurements of photosynthesis. Alistair targeted spot measurements of gas exchange, light response curves, and A/Ci curves. The latter provides mechanistic insights into the biochemical controls on gas exchange. Each of these three approaches provides unique information for models.

Over the summer, we will be taking many measurements of leaf gas exchange; and taking them on many plant species. We will relate these results to water and nutrient acquisition strategies and, over time, build new representations of plant functional types for models.

One of the several representations we will explore is that of relating nitrogen allocation and storage strategy to leaf CO2 uptake. We already have a nitrogen allocation model developed by Chonggang Xu at LANL that we will evaluate for this purpose. Chonggang just published his model in PLoS ONE, so we are ahead of the game in this regard. David McGuire and Eugenie Euskirchen, both from the University of Alaska Fairbanks, and Dan Hayes (ORNL) will be helpful as we begin to model these dynamic processes and incorporate them into models.

Alistair and Victoria will get new information over the next few days, and then we will formulate a plan forward in conjunction with our NGEE Arctic modelers .

Trace gas fluxes from the tundra

Melanie Hahn is a PhD student from UC Berkeley who is working on the NGEE Arctic project with Margaret Torn. This is Melanie's first trip to the Arctic and she is jumping in with both feet. Although she has yet to select a topic for her dissertation research, it is likely to encompass some combination of chamber-based measurements of CO2 and CH4, and eddy covariance. These two approaches will allow Melanie to tackle questions related to the controls on greenhouse gas (GHG) emissions from polygonal ground and scaling from plot to landscapes.

Today, Melanie and Margaret were introduced to the rigors of transporting equipment the roughly 2 km to our field site. I pulled into the parking area off Cake Eater Road just in time to catch Melanie and Margaret preparing to transport PVC collars for GHG measurements using static chambers. Melanie kept strapping collars onto her backpack until she was no longer visible from behind. Just a walking mass of PVC chambers.

If transporting a heavy load of plastic collars wasn't enough, the wind was blowing 25 to 30 miles an hour. Leave it to Mother Nature to make a hard job even harder. My understanding is that Melanie and Margaret were able to sample low- and high-center polygons, both rims and troughs, for CO2 and CH4 flux today. These measurements will continue throughout the summer and data will be used to parameterize and evaluate GHG flux estimates derived from climate models. Hopefully, Melanie will be able to post an update to the NGEE Arctic blog in which she describes in more detail the technique that she and Margaret used today.

Breakfast in Barrow

The last conversation I heard last night before falling asleep on the apartment's futon was "Who wants an omelet for breakfast?" I chalked up the question to late night idle chatter. However, I awoke to find our team's plant physiologist, Alistair Rogers (BNL), busy in the kitchen. There were bowls of green onions, tomatoes, and cheese spread across the counter; along with plenty of eggs. It looked far different than the breakfasts that I have grown accustomed to on my trips to Barrow. Those typically tend to consist of granola bars, oatmeal, yogurt, and a strong cup of coffee.

I have known Alistair since he was a post-doc working for George Hendrey and Steve Long, and know him to be quite adept at measuring photosynthesis, leaf gas exchange, and associated biochemistry of plants. He and I have worked together on other projects in the past. While I was aware of his scientific and technical capabilities, I was not aware of his culinary skills. There was a distinct aroma coming from the kitchen that seemed pleasant enough.

Given our circumstances and general lack of "pots and pans" in the cupboard, Alistair did a brilliant job of preparing omelets for everyone on our team. We all rotated through limited seating at the kitchen table as Alistair cooked and served one omelet or eggs over easy after another. Mine was great and it allowed me, for once, to leave my yogurt in the refrigerator. It also gave us a full stomach and just the right mind set to start another day of field work in Barrow...

Thanks Alistair!

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.

Tundra Vegetation Coming to Life

Most of my research thus far has been conducted during the winter months; geophysical surveys in September; collection of permafrost samples in April; and installation of water samplers in May. The snow is now gone, however, and our team is getting to see the first signs of Spring in the North Slope.  Interestingly, the first signs are subtle. On closer examination, however, there is a lot taking place. The low-growing willows are flowering, as are other plants on the tundra. The sedges and grasses are beginning to appear in wet areas like the troughs around low- and high-centered polygons. Members of our team have commented that one of our goals (that of documenting how water, nutrients, and carbon are all inter-connected in these Arctic landscapes) is already apparent. You can imagine the differences between wet and dry areas, each with unique nitrogen dynamics, and the resulting impact on vegetation patterns and flux of CO2 and CH4.

Rich Norby, Alistair Rogers, Margaret Torn, Jessie Cable, and two post-docs Victoria Sloan and Melanie Hahn are studying this cascade of processes. This team has been busy this week taking measurements and samples, and installing nutrient exchange resins, all for accessing the dynamic interplay between water, nitrogen, and biogeochemical cycling of carbon. Only a limited amount of data have been collected so far, but more will be collected as the summer progresses.