If you’re in the Alps in the winter, you’ll notice that surviving in the mountains requires flexibility, especially in winter. When winter arrives in the Alps, some birds migrate south and many other animals (such as birds, mammals and even insects) descend to find protection at lower grounds. After all, a short vertical migration can mean a world of difference in temperature and depth of the snow layer. But if you’re a tree, moving is not an option.
One of the problems that trees face in the Alps in winter is the amount of snow. When hiking in the mountains you can often see evidence of trees that have been damaged by snow, like a tree trunk that has been snapped by an avalanche for example, but also the snow that trees collect on their branches can cause huge problems. Due to the weight of snow, branches – or in the worst case, the entire trunk – can break. Fortunately, most trees species in the mountains have flexible branches that can bend and therefore will break less easily.
Some examples of how trees deal with large about of snow:
- The Conical Shape of Conifers
Coniferous trees in the Alps, such as Norway Spruces (Picea abies) and European Silver Firs (Abies alba), have very flexible branches to prevent snow damage. When snow accumulates on the branches, they bend downwards so that the snow can slides off. The characteristic conical shape of conifers also helps letting the snow slide off the branches, limiting the amount of snow that can accumulate even more.
- The Extremely Flexible Green Alder
Green alder (Alnus viridis) is one of the most flexible wooded species you can find in our mountains. Underneath a thick layer of snow, green alder lies flat on the ground. In the spring, once the snow melts, the alder stands up straight again, undamaged. Thanks to this flexibility, green alder can even grow on avalanche paths, a place where it’s impossible to survive for most other – less flexible – trees with thicker trunks. That’s why it’s green alder that colonizes most avalanche paths of the Mont Blanc massif.
Extraordinary growth forms
Another example of the effect of large amounts of snow on trees growing on mountain slopes in the Alps, are strange twists in tree trunks. The bizarre curves aren’t only striking to see, but also clearly show that the wooded plants on mountain slopes battle with the elements. Again, one of the causes of these extraordinary growth forms can be the amount of snow in winter. On steep slopes snow slides down very slowly – invisible to us – causing young trees to bend (or break). As soon as the snow melts, the trees grow perpendicularly upwards again, but a tree only grows at its top, this leaves the lower part crooked.
Needles versus Leaves
The amount of snow isn’t the only challenge trees face in the Alps in winter. Learn more in my next Alps Hiking Nature blog: Needles versus Leaves – Wintry Challenges for Trees in the Alps.