Friday, June 22, 2012
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.
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.
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.
Wednesday, June 20, 2012
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.
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 .
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.
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.
Tuesday, June 19, 2012
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.
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.
Today, we completed laying out trail mat to our field sites. It was a well-defined task that required two days of intensive work by three or four people from our team. What we ended up with is a trail that now does two things. It protects the tundra from disturbance caused by foot traffic, we all feel good that the site will not suffer from our repeated trips across the tundra. In addition, we can now, within the first month of our field season, ensure that NGEE Arctic scientists and collaborators can access plots for the fundamental science we intend to conduct. Measurements can be co-located within specific areas and our team can take measurements and obtain samples from similar ice-wedge polygons that dot the landscape. This will ensure that our team will remain integrated, as will our science, as we focus our attentions on delivering a process-rich model of landscape dynamics for the Arctic coastal plain. Mission accomplished...
Monday, June 18, 2012
Those who have followed this blog will remember that our team laid out trail mat across the tundra in May. At the time, we transported almost 800 meters of trail mat to our site and positioned individual one meters sections end-to-end so that we formed pathways to each of our four research plots.
The challenge this trip was to connect the many pieces into safe and solid surface for walking. The GeoBlock trail mat has interlocking tabs that can be screwed together. That seems to work well, but placing screws and using a drill with gloves proved cumbersome in an initial test last May, so I have been looking for an alternative. I thought of cable ties, which would have worked, but they would be expensive. In searching the web, I found reference to double loop wire ties used to connect rebar. I ordered 2500 ties, each 9 inches long, and a couple of twisting tools with the thought that they would be quick, effective, and inexpensive.
They worked great! Joanne Childs (ORNL), Jessie Cable (UAF) and I could place sections of trail mat end-to-end, wrap one of the loop ties through the mat, and twist the ties into place. We could connect two pieces in under a minute and build long sections in just 5 minutes. These could then be easily carried into the field of placement to each of our polygon plots.
Right now, we are almost finished with this task. We have built a trail and added spur trails that now allow our NGEE Arctic team to access vegetation, hydrology, and biogeochemical plots. This should really facilitate data collection as we get our field season underway.
I'll post more detailed pictures tomorrow.
The last time we traveled to Barrow, we conducted field studies in temperatures that approached -25F below zero. Today, we stepped off the airplane and were greeted by unseasonably warm temperatures that rose well above 45F. Given that magnitude of a temperature swing over a period of a month, it should come as no surprise that most of the snow has melted; a sure sign of summer. The other sure sign of summer is the report we received from Tony from UMIAQ when he picked us up at the airport - "We saw our first mosquito yesterday!"
It was a long trip from Boulder to Barrow, but it was good to meet up with my colleagues from ORNL, LANL, BNL, and UAF. We signed in and received a safety briefing from UMIAQ, picked up our vehicles, and unpacked a few boxes that had been delivered earlier.
With 24 hours of daylight, we took our time getting organized, then met with Mark Ivey in the Barrow Arctic Research Center. Mark works with the DOE Atmospheric Radiation Measurement (ARM) program and has years of experience working in the Barrow area. He has been helpful in locating laboratory space for those in our project who need quality lab space for trace gas measurements, sample preparation, etc. Lab space is at a premium in Barrow and fortunately Mark had space that he was not using and offered it in support of the NGEE Arctic project. Once we discussed safety-related issues of the laboratory, we spent a couple of hours moving in a gas chromatograph, leaf area meter, balance, oven, and miscellaneous field and lab supplies.
We then drove out CakeEater Road and walked out to the control shed on the Barrow Environmental Observatory (BEO). This was a good time to look over the field plots and examine the differences in vegetation across the low- and high-centered polygons. During previous trips to Barrow, the ground was covered in snow and today was the first time we got a good look at the snow-free landscape. It will take a few days to sort out our plot design, especially for those working on the vegetation dynamics task of our project. We have a good team, however, and they are up to the challenge.
Friday, June 15, 2012
Eric Kasischke, University of Maryland, and his team have done a good job of bringing people together from multiple disciplines to discuss key science questions for the ABoVE project. These questions reflect the strengths of the NASA Terrestrial Ecosystems program and are highly relevant to regional and global climate models, land managers, and society.
The scientists assembled for this workshop are actively engaged, with the emphasis and the majority of our time spent in one or more breakout groups. Each group is tasked with looking at a set of questions from one of several perspectives in hopes that we can develop an overall compelling vision for the ABoVE project. It is clear that the team leading ABoVE have already given this considerable thought and our input this week will supplement or fine-tune the vision already developed in previous scoping workshops. It is obvious that there are numerous points of potential interaction between ABoVE and NGEE Arctic. Our process studies and emphasis on scaling could complement and indeed benefit from a close association with ABoVE.
Although the majority of our time has been spent in breakout discussions, there were a series of plenary talks. One of those was presented by Dave McGuire (UAF) who spoke about critical knowledge gaps in our understanding of Arctic systems. Another presentation by Piers Seller (NASA) highlighted the strengths and weaknesses of current Earth System Models. He derived many of his comments from a NASA-sponsored workshop held in May to discuss the state of "Arctic Boreal Modeling". This was an outstanding presentation and, in summarizing the workshop, Piers emphasized that the needs of the climate model community could clearly be met by the ABoVE project. Much like the NGEE Arctic project, ABoVE would want to target key uncertainties in the models and identify strategies for scaling process-based studies to that of the scale of climate model grid cells. My discussions with Eric and his leadership team is that NGEE Arctic could uniquely contribute to ABoVE in two important ways. One would be to conduct process-level studies in support of gaining new knowledge needed to reduce model uncertainties. We view this as a strength of our project and our planned integration of surface and subsurface sciences. Another contribution would be in providing a multiscale modeling framework that ultimately would link to remote-sensing products generated through ABoVE. We could use these data products to evaluate model performance at scales relevant to climate models.
In addition to the plenary talks and group discussions, I had a couple good interactions with Michelle Walvoord, who is with the US Geological Survey. Michelle and her colleagues have used an airborne electromagnetic system to characterize permafrost to depths of several 100 meters. The approach provides information, for example, on active layer thickness and talik conditions beneath thaw lakes in the Alaska. Our NGEE Arctic geophyics team, led by Susan Hubbard at LBNL, has looked into this approach as a complement to our ground-based EM, GPR, and seismic measurements in Barrow.
I also spoke with Ted Hogg, who is with the Canadian Forest Service, Natural Resources Canada. Ted has made a series of observations of aspen mortality in boreal forests. It appears that this die-off of trees is initiated by drought, that then pre-disposes trees to insects and disease. The exact mechanism of mortality is unknown, although it is just this mechanism that represents a critical uncertainty in ecosystem and climate models that needs to be tackled in the coming years.
I leave Boulder for Alaska later this evening. My all night flight will allow me to join others from our team in Barrow tomorrow. We have a lot of work to do in the next week and it will be great to visit our plots now that snow melt has occurred. I will post pictures and updates once we get underway.
Thursday, June 14, 2012
Bear safety is a complex issue that became at lot clearer after attending Joe Nava's Bear Safety Course this afternoon. We learned a lot from a no-nonsense, straight-talking, bear expert, including how to recognize different bear behavior, the use of bear spray, and instruction on the safe use of shotguns for bear defense. It was a great course and "team veggie" did some good shooting.
Wednesday, June 13, 2012
My travel plans usually call for me to fly from Knoxville to Anchorage and then onto Barrow. This week, my travel plans include a detour to Boulder, Colorado where I will represent the NGEE Arctic project at a NASA ABoVE workshop. The Arctic-Boreal Vulnerability Experiment (ABoVE) is led by Eric Kasischke, Scott Goetz, John Kimball, Michele Mack, and others. Research carried out as part of ABoVE would provide the opportunity to not only focus on key process associated with the land surface, but on key interfaces between the land, coastal oceans, and atmospheric boundary layer as they interact with climate-mediated terrestrial processes. There are strong connections between the DOE-sponsored NGEE Arctic project and ABoVE, so I am looking forward to interacting with this group to understand their goals and how our field studies can contribute. NGEE Arctic and ABoVE are both consistent with the recently released Interagency IARPC Arctic Research Plan (http://www.nsf.gov/od/opp/arctic/iarpc/arc_res_plan_index.jsp) which calls for interagency collaboration in the study of Arctic systems.
During the workshop, later this morning in fact, I have the opportunity to present a "speed talk" that will highlight the NGEE Arctic project. A 5-minute snippet of our team, our goal and scientific approach, and how others can become engaged in the project. My four slides include:
We have already had multiple requests from university faculty and national laboratory staff who have expressed an interest in collaborations. We have had a few inquiries from potential international collaborators as well.
My poster will be similar to the one presented recently at the DOE Terrestrial Ecosystem Science (TES) PI Meeting, April 23-24 in Washington, DC.
A copy of this poster and two others that our team presented at the PI meeting can be downloaded at the NGEE Arctic web site (http://ngee.ornl.gov/).