Saturday, January 31, 2009

How to Walk in the Dry Valleys

The dry valleys are a very sensitive ecosystem. Because it's such a harsh place for organisms to live, they do not grow very fast. We don't want to make it any harder for them! Plus, we want the ecosystem to stay as clean and healthy as possible, without creating too much of a disturbance ourselves. We want to avoid damaging the ecosystem and the organisms as much as possible. Therefore have to be very careful when we work in the dry valleys.

The main way we can disturb the environment is by walking. We have to walk a lot to get to our camp and field sites for work. There are very specific ways we walk here to minimize the amount of disturbance we create with our feet.

When we're walking on the ground to and from our field sites, we always walk single-file so that only one line of footprints is made. We follow paths made by the polygon cracks in the ground. These cracks are made by the repeated freezing and thawing of the ground, and they form a variety of interesting shapes, called polygons. When you look at the ground from a helicopter, you see all of the polygons that make up the dry valley landscape.
Our previous research has shown us that soil biodiversity is lowest in these cracks. There are fewer animals living in the soil at the cracks than in the flat part of the ground. So, we try to always walk in the cracks. That way, our footsteps are trampling the least amount of organisms as possible. It unfortunately means that we can't walk in a straight line anywhere! You have to follow the zig-zagging of the polygon cracks to get from one place to another, which means sometimes you walk twice as much as the distance you need to go! Here's what it looks like as you walk in the polygon cracks:
video

When we're working at our field sites, we try our best to not trample the soil too much. We stand on rocks as much as possible. If we want to sit down, we sit on rocks, like Katie is doing:

Sometimes we work near streams, especially for our moss research. We don't want to disturb the algae and moss growing in the sediment in the streams. To avoid trampling anything, we rock hop. Every step we take has to be on a rock, where algae are not growing. This is pretty easy when the stream flow is low and the rocks are exposed, but it can get tricky if the water is high!
video

Sometimes we even have to rock hop to walk across the dry ground. The polygon cracks cover most of the soil, but they're not everywhere. When there are no cracks, we rockhop across the ground so that we don't disturb the soil!

Most of the places we walk are on soil and near streams. But, sometimes we walk on the ice. We don't have to be as careful about the ecosystem when we're on the ice, because there's not much damage we can do. But, we still have to be careful! The ice is slippery, of course, so we wear stabilizers attached to our shoes that give us better traction. Also, the glaciers and lake ice are covered with cryoconite holes. These holes are formed when dirt or rocks are blown onto the ice. Because the rocks are dark, they absorb more of the sun's heat and melt the ice around them. The rocks sink down as the ice melts, leaving a lot of little holes in the ice. These holes might be several inches deep, or even deeper! They can be just a couple inches wide, or they can be much bigger! It depends on the size of the rock that landed there to melt the ice. Sometimes the holes are filled with water. We have to be careful not to step in them, because if you do, you'll suddenly find yourself standing in a deep, wet hole! Sometimes the cryoconite holes have been covered back over with a layer of ice on top that maes the holes hard to see. But, that layer of ice is not strong enough to hold a person, so you crash through unexpectedly. You have to keep an eye on the ground so that you know you're stepping on thick ice. This is what it looks like to walk over the top of a glacier in the dry valleys. This is from our Christmas Eve hike over the Canada Glacier:
video

We do a lot of walking while we're here. Now you know what it's like!