Participants in the NGEE Arctic project are interested in
better understanding feedbacks between ecosystems and climate. These feedbacks,
both negative and positive, can arise through changes in the flux of CO2 and
methane to and from the atmosphere. One of the factors that drive carbon cycle
processes in the Arctic is the distribution of water across the landscape. Our
team began exploring this dynamic last year across a series of inter-connected
low- and high-centered polygons on the BEO. Those studies are going well and we
have made significant progress in gathering the process knowledge required to
inform a range of models from the individual polygon to climate grid cells.
Another important feature of Arctic landscapes that
drives carbon, water, and energy-related dynamics is the presence of drained
thaw lake basins (DTLBs) across the coastal plain. These occupy a large portion
of the land surface and are known to be of various ages (e.g., young to
ancient), each with unique soil and vegetation characteristics. The NGEE Arctic
project will begin to study these this year in an area just south of the BEO.
We laid out transects using LiDAR data, courtesy of Craig Tweedie, and a site
visit in April. However, we had not seen this area in a snow-free condition. That
was our goal today.
Rich, Victoria, Bryan, Gus, and I drove along the west
edge of the BEO before turning east and then south again on a road that goes to
the gravel pit. We stopped just before the entrance to the gravel pit and
headed across the tundra to our west. Our map, an original product of Ken
Hinkel at the University of Cincinnati and his colleagues, showed that we would
walk first across an old DTLB and then up and over a slight ridge to a DTLB
that was considerably younger. The old DTLB was wetter, polygons were filled
with water, and in some areas were beginning to coalesce into larger bodies of
water. Gus confirmed that this was a feature of the admittedly poorly
understood life cycle of DTLBs. By comparison, the younger DTLB had a quite different
composition of vegetation and lacked any well-define polygonal structure or
ponding water.
Our team will lay out a sampling transect across this area and begin a series of measurement campaigns in early July. Our goal is to assess CO2 and methane exchange, and energy budgets, across the various DTLBs and relate those potential differences to soil water content, degree of inundation, soil temperature, and vegetation. All this information will be useful as we add new insights about landscape feedbacks to climate models.
