We have seen evidence of solifluction at several locations
this week and today we took the opportunity to visit one such site on a modest
hillslope just 15 to 20 miles outside Nome on the Teller Road. Joel and Eitan
spend the afternoon excavating a small section of an advancing lobe trying to
better characterize thaw depth, ice content, soil texture, and moisture
content. Larry, David, and Cathy took time to collect soil cores from across
the lobes and adjacent areas, as well as quantify the spatial variation in thaw
depth across the area. Since one of these solifluction features can cover an
entire hillslope I took the afternoon to walk each lobe and examine the
distribution of water and vegetation along the advancing front. It was clear
that the lobes were fairly massive with most of them being multiple meters in
height. The advancing faces of these features were heavily colonized by willow
shrubs. These shrubs were quite productive and seemed to thrive in areas of
physical disturbance. Downslope of the advancing face the soils were saturated
and vegetation was largely sedges and forbs. So these geomorphological features
created a highly variable environment for vegetation cover. The implications
for albedo, energy balance, and the carbon cycle of these solifluction features
are unknown, but they represent interesting features in the landscape. While the
solifluction process itself may not be of interest to our NGEE Arctic team, the
mechanisms that promote shrub expansion are and we will want to return to this
and other disturbed areas in order to learn more.
