Field day

The Collins Glacier here on King George Island has been shrinking. The edge of the glacier has receded back further than it was even just a few years ago. That has exposed soil that is now undergoing succession, which is the focus of our research this year.

One of the ways we are studying succession is by looking at the plants and soil that have been exposed for different lengths of time. Yesterday, we collected samples from the early succession zone that has recently been uncovered by the glacier. This area is still fairly close to the glacier, like you can see in this photo:

This soil has been exposed for only a few years. There are moss and lichens growing on it, but only certain species that are good at being "pioneers". They tend to like wet areas, because the melting glacier provides a lot of it. But they have to be able to gather nutrients in creative ways, because there is not a lot in the soil yet. Those are species like moss in the genus Sanionia, and cyanobacteria who are able to fix nitrogen from the atmosphere.

This moss is in the genus Sanionia. It likes living in wet places, like this channel where melt water flows down from the glacier.

We will also take samples further from the glacier, all the way out into the areas that have been exposed for a long time. These sites have had enough time to reach a "climax community", which is the mature, fully-developed plant community.  That would be a place like I showed you a couple days ago from our scouting trip:

A climax community on King George Island has many species of moss, not just the hardy pioneer species, as well as the grass. The Antarctic hairgrass requires a lot of nitrogen to grow, but can't fix it from the atmosphere like a cyanobacteria. They can only arrive later in succession when the cyanobacteria have done the work for them!

So we are taking samples from across these successional zones: some from early succession, some from a transitional "mid-succession" zone with a few more moss species and grass starting to move in, and then from the "climax community". We use the samples we take to learn about the soil conditions and the community of microorganisms that live at those successional zones. We know that the plants change like I showed you in the photos, but how do the soil invertebrates change as the ecosystem ages? How does that relate to the chemistry of the soil? These are the questions we will be able to answer with our samples.