Today was clear and cool and beautiful. The temperature this morning was -25 F with a nip in the air and no wind. It was another great day to be out in the field conducting science!
Just the other day I had posed a question to the students about what the CO2 levels would be doing at this time of the year. I have received a bunch of very insightful answers and some equally interesting ideas about how the snow, sun, plants, and decomposers are contributing to this picture. So I thought that I would spend some time and talk about what the tundra is doing right now in terms of CO2 balance.
The snow fence causes the snow to pile more on one side. This insulates the ground and keeps it warmer than other areas.
The snow plays a huge role in the activity of the plants. Most of the plants have lost their leaves and cannot carry on photosynthesis. The rest of the plants that do still have some green on them are buried under a considerable amount of snow. The snow blocks the sun from reaching the plants. As far as the plants are concerned, because they are not photosynthesizing, they do not need to be taking in CO2 right now. There is no reason for the CO2 levels to be going down.
The snow blocks the plants from photosynthesizing.
However, keep that thought in mind as we make our way toward the summer. Remember that the snow acts as insulation on the ground, allowing the ground in the deep snow to stay warmer than the ground with little snow. The areas of ground with little snow are exposed to the low air temperatures and get colder. Because the ground is not as cold, or warmer, the plants will have a better chance of growing in the summer as this ground warms up faster.
Elizabeth and I hooked up the gas analyzer and the computer at Site B and recorded the CO2 levels on the control and experimental sides of the snow fence.
The red line shows the CO2 levels increasing under the areas with little snow cover. The blue line shows the increase in areas with deep snow cover.
Now lets look at the decomposers in the frozen ground. They should be out of commission, but they’re not. They are down there doing their thing the best they can in the cold. As they decompose and carry on respiration, they release CO2. Even during the winter when decomposition is low, there is more CO2 being given off from respiration than there is CO2 being taken in from photosynthesis.
So we are here measuring the amounts of CO2 being given off by the tundra during the winter months.