Tuesday, January 15, 2008

Mosses: the Dense Forests of Antarctica

Not many plants grow on Antarctica, especially in the area of the Dry Valleys. However, there are in fact plants here! They are mosses. Mosses are small, simple plants that are very short and soft. They are not like the things you think of when you hear the word "plant". They do not have flowers or seeds, do not have big leaves and long stems, and do not grow very tall.

Mosses grow in most places around the world. You've seen them before, especially growing in or near streams or other wet places. There are many different types of mosses around the world. But, here in the Dry Valleys of Antarctica, there are only four species off moss. They are the only plants that grow in the soil. So, on Antarctica, moss patches are equivalent to redwood forests in the U.S.! Here is Elizabeth sitting next to an Antarctic "forest":

During the summers, mosses grow in wet areas beside streams, lakes, or snow patches. They grow very slowly, less than a millimeter each year. During the winter, when there is no sunlight for months, the mosses become dormant.

Elizabeth studies mosses. She wants to know why mosses grow in some places in the Dry Valleys, but not others. She also wants to know whether the mosses change the soil that they grow in.

To learn about the mosses and soils, we take a lot of samples. In areas where we find mosses, we take a small piece of moss and the soil beneath it. We also take soil from similar nearby areas that do not have mosses, so that we can look for differences between areas where mosses live and do not live.

We have to be very careful when we walk around these areas, so that we do not crush the mosses we want to study! We have to "rock hop" through the streams, stepping only on large rocks, and not the sediment or mosses.

We also measure the productivity of the mosses in these different areas. Mosses are plants, which means they photosynthesize and use up carbon dioxide. We measure how much carbon dioxide is being used to determine how active the mosses are. To do this, we place a plastic box over an area with mosses. This traps all of the gas in the area. The mosses are still receiving sunlight, which means they can still photosynthesize and use the carbon dioxide trapped in the box. A machine measures the concentration of carbon dioxide in the box, which tells us how quickly it is decreasing as the mosses use it up. If carbon dioxide disappears quickly, the mosses are very active. If it disappears slowly, the mosses are less active.
We still have a lot more samples to take for Elizabeth's project. We spent time last week sampling streams near Lake Fryxell. Later this week and next week, we will visit many more sites to sample for mosses along lakes, streams, and snow patches.