Deflation patches are everywhere! Well, more accurately, they are often on south facing slopes and relatively close to the ice sheet. Ruth, our resident deflation patch expert, has been taking Cohort 4 around to lots of deflation patches so that we can measure how much vegetation is present in and around the patches. Deflation patches are easy to identify- they are areas of exposed rock and loess (sediment deposited by wind) in an otherwise vegetated ground cover, with a ‘scarp’ on the uphill edge of the patch.
Deflation patches expand when wind digs away at the loess and the surface vegetation no longer has anything under it; so, the presence of a scarp, or wind-eroded cliff, can often be the tell-tale sign of a deflation patch.These patches can vary in size from a few feet to hundreds of feet across. Judging from all of the satellite and airborne imagery that we have attained, the deflation patches have not expanded noticeably in the last 70 years!
A lot of our work on deflation patches has been to go out to many randomly chosen locations within Ruth’s study areas and simply record what we see (Ruth will later compare these observations to her satellite imagery). So out we all go with Ruth, hiking up and down the rolling hills of Kangerlussuaq with a 0.5 m by 0.5 m PVC quadrant in hand. We lay down the quadrant and estimate a percentage of vegetation cover for that location. Next, Ruth types in a new survey location and the GPS leads us off into the hills again. We have over 100 randomly chosen locations to visit during our stay at Sea Horse Lake.
Since the airborne imagery of this area is fairly recent, and deflation patches expand slowly, we need some other way to determine the age of these patches. Enter lichenometry! Lichens are capable of existing in some of the harshest environments on Earth- out here in Greenland they come in many varieties and colors, but all seem to enjoy growing on rocks. A few characteristics of lichen make them useful for dating: 1. They need the sun to grow and 2. They expand at a predictable rate. By measuring the width of lichen on rocks within the deflation patches, we can determine when the loess that covered them was removed. Ruth, to date, has already measured over 3,000 lichens!
Being out here in Kangerlussuaq with Ruth, I was finally able to see the deflation patches and lichen she’s been writing proposals and talking about for the last year- it’s incredible to see everything finally coming together! Cohort 4 has had lots of fun going on deflation patch hikes and estimating vegetation cover during our time at Sea Horse Lake- be sure to check back in and see all the other science we’re doing up here!