You might be one of those skiing enthusiasts that love snow, even in the spring months of April and May, and in that case this might never have left you wondering. It could also be that you were one of that nature loving kin that prefer having a firm grip on the ground, being in control of you own direction and speed, looking forward to a hike in the mountains. I am more of the second kin, and this might be because that I’m Danish, and that snow covered mountains in the backyard is something new for me. Although I did have my first spring snow experience in March this year, and this opened a whole new world for me. I got some amazing practical examples of how the snow is shaping the alpine mountain vegetation.
As a plant ecologist I know about how snow shapes the vegetation from reading the literature, and I have even been teaching students this. It is something completely different to see things live that you know in theory.
The thing with snow is that it is insulating. We have heard about this insulating effect from people surviving in Eskimo igloos, but this is also what snow does to the soil and the vegetation covered in snow. The surface and soil temperature below a deep snow cover can be 0 °C or even +1 °C even tough air temperature just above the snow is -10 °C.
But then what about those wind exposed places where the snow cover is always very shallow? Well, here the vegetation just has to be really tough, because spots with shallow snow are the first to thaw and become snow free. And what happens in the mountains during the spring (and in these days with warmer climates)? In the night it is freezing and in the day it is sunny, and plus degrees. So the plants have to be able to endure this. These hard conditions are shaping the characteristic ridge- and heath vegetation that in early spring are left uncovered from the snow. Evergreen dwarf shrubs dominating heath vegetation has the same advantage as most conifers, they keep on their leaves for several years, and the leaves contain a lot of compounds that help them live a long time.
However a heath system like the one on the above picture should still have snow cover at this time of the season. Even though the Vaccinium vitis-idea above was in a seemingly healthy state on this mountain, the Empetrum nigrum below was not in a healthy state.
In conclusion the mountain vegetation as we know it is very dependent on the spring snow, so we should just be happy when we see it blocking our way in the mountains.
Also winter ecology is quite fun, and should be exercised some more, because some summer conditions might be explained by the previous winter.