The south side of Lake Hoare in Taylor Valley is the site of many of our former and current core LTER experiments. Today we needed to sample the Long Term Manipulation (LTM) experiment, the Elevational Transect experiment (ET) and the Algae experiment. The LTM experiment was set up in 1995 to investigate the effects of increased temperature, moisture, and carbon inputs. In 2005 the experiment was broken down, and we are sampling it now to determine whether or not the site is on a path to recovery.

Despite all our good intentions, our experiments have an effect on the landscape and the soil. Therefore, it is our hope that when we stop an experiment, the soil will return to pre-experiment condition. This may not always be possible. For example, in areas where people walk, paths are formed, and the abundance of nematodes that live on those paths can be less than half of the undisturbed population. That’s a significant drop in population size just from walking on the soil. Because of this, we treat the soil as carefully as possible and walk on established paths or in polygon cracks whenever possible.

Here you can see the large polygons across the surface, with Lake Hoare in the background. Somewhere in the middle of this picture are Dorota and Breana.
Polygons

The LTM and Algae experiments are close to the lake, so we marched down there to sample them. The Algae experiment is also an older experiment that included the addition of algae to plots as a natural nutrient input. We sampled this experiment to see if the addition of algae all those years ago had a lasting effect on the soil biology. When we arrived at the LTM plots, Ed noticed that the metal signs outside the plots were bent and worn by the wind.

Wind Damage

The wind in the valley is so strong, especially in the winter, that we have to secure all of our scientific equipment with several bungee cords and metal stakes pounded into the ground. One year the wind was so bad it destroyed a food cache at one of the field camps. Food caches are stored in heavy wooden boxes and secured very tightly, but sometimes it’s not enough. Winds that blow down from the glacier are called “katabatic winds” and can reach speeds of 200 miles per hour. Combine high winds with unstructured Taylor Valley soil and you get a sandstorm. Definitely powerful enough to bend and “erase” a metal sign.

After all that hard work, Breana, Ed, Diana and Dorota decided to break for lunch.
LTM Team

Byron decided to break for a nap, but Dorota had plans of her own.
Conquering Mt. Byron

In the afternoon we sampled the ET experiment, a study of the differences in nematode populations at different elevations and sampling scales. Nematodes are so small, there could be totally different populations within several feet of each other, so the places we decide to sample from have to be picked very carefully. Also, the soil environment changes dramatically as elevation increases. Sampling for nematodes at low, medium and high (very high!) elevations at different scales (9 samples 5 meters apart v 9 samples 0.5 meters apart) gives us valuable information about the distribution and abundance of our Antarctic invertebrates.

For example, the A-plots are down by the lake, where the soil is wet, while the B-plots are both higher and drier. Nematodes that we find in the A plots but not the B plots may not tolerate dry soils very well, and vice versa. With this information we can predict which nematodes we can find in various soil environments. It also tells us a little bit about the life history and environmental requirements for different species of invertebrates. We hope to use this data to predict the effects of climate change on Dry Valley invertebrate species. Invertebrates are responsible for a large portion of the nutrient cycling in the Dry Valleys.

What will happen to the nematodes if the planet gets warmer or colder? What happens to nutrient cycling in Antarctica if worm populations increase or decrease? These are two of the many questions we are trying to answer down here at the bottom of the world.

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