As we moved out to the field site today it became really clear that the season is changing around here. When I first arrived here the snow looked so even and flat and just the same all over. That really wasn’t the situation then, and it is certainly not the situation now. The temperatures have been in the 40’s during the day and some nights are not even dropping below freezing. The snow is really feeling this. It is becoming slushy and thick and actually feeling wet in many places. There is less of it also! The tundra is beginning to make the first holes in the snow and showing the plants that have been waiting all winter. The sun is just one factor that causes this to happen.
The plants are working their way through the snow, but the trails are packed down and thick.
Even where we have been walking at the study site, the snow is melting faster.
The sun is doing a great job on the top of the snow, but the plants and decomposers are working on the underside. From the activity of the decomposers the temperature of the tundra begins to rise just a little bit. This is enough to get things started in helping to thin the snow. Once the snow gets thin, the color that shows through begins to change. Some of the snow patches become darker just a shade. This color change is enough to affect the albedo, or the amount of light that gets reflected from a surface. The darker patches begin to absorb more of the sun’s energy and then warm a little more than the snow around it. Even the plants that are close to the snow surface or were tall enough to extend above the snow, now can gather more heat from the sun’s rays due to their dark branches. This helps to melt the snow around the trees that in turn helps to warm the ground around their bases.
In our footprints are now growing plants!
As the tundra shows itself again, you can see that there are many plants that will populate the area.
We are also seeing the human effect on the snow. In areas where there have been people walking, dog sleds running, and even snowmobiles powering on trails, the color of the snow changes. It changes from dirt or fumes that may have fallen on the surface, but it also changes due to the shadows that have been created. The shadow areas are little spaces where the sun does not hit the snow as much as the other spaces. That area may stay a bit cooler. Also the snow that has been disturbed becomes compressed. The compression of the snow will pack it down making it a more dense as snow continues to pile on top. We see in these areas where the clean snow on the trails tends to stay on the ground longer, and the dirty snow on the trails begins to melt faster. This all sounds very complex but as we look around at the tundra today, you can see many places where these factors is causing some snow to melt rapidly while other areas will last weeks longer. This is one reason why we are very careful to walk only in certain areas in the study site. We want to have as little impact on the tundra as possible.
Can scientists really study something in nature without changing it?
Even the plants, with their dark branches, help with the melting process.
The willow bushes along the trails are beginning to grow buds.