Needles versus Leaves – Wintry Challenges for Trees in the Alps

My favourite place to hike in the Alps in winter? A coniferous forest, without a doubt!

Norway spruce is very common in the Alps.

When tree branches bend down, heavy with snow, and the forest floor is covered with a fresh layer of snow full of wildlife traces, I truly can’t think of a better place to be!  While the deciduous trees, such as beech, hazel, mountain ash, birch and maple trees, in the valleys and lower slopes look bare without their leaves, at higher elevations, the largest extent of forest is beautifully green. Coniferous forest with spruce, fir, and a variety of pine dominate the higher mountain slopes, but why is that? Why are there so many conifers in the Alps?

Some of the answers lie within the differences between needles and leaves:

  • Drought

Needles are smaller than deciduous leaves and have less area to lose water through evaporation. In addition, needles have a waxy layer that prevents evaporation. This means that conifers are generally better able to deal with dry periods. In mountainous areas dry periods are very common, especially in winter when most of the water is frozen. That’s why coniferous trees clearly have an advantage at higher elevations.

Pine needles have a waxy layer that prevents evaporation.
  • Productivity

However, the production from photosynthesis of a needle is less efficient than that of a deciduous leaf. Fortunately, conifers in the Alps – with the exception of the European larch – remain green all year round. This means that the lower productivity of needles is compensated by the longer activity during the year. After all, deciduous trees lose their leaves in the fall and thus also the capacity for photosynthesis.

  • Regrowth

The fact that conifers retain their needles throughout the year has another advantage. In the spring they need less energy than deciduous trees who need a lot of energy having to re-grow all their leaves.

spruce needles
Needles that stay green in winter, can do photosynthesis year round, providing the tree valuable energy.

Opportunities

That coniferous forests dominate at higher elevations in the Alps is great for us! This time of year, these forests provide extraordinary winter hiking opportunities, because they are teeming with life. Forest dwellers as red squirrels, black woodpeckers, red deer, chamois and many other critters: all of them leave their traces behind in the fresh snow for us to find!  

Bend or Break

Another challenge that trees face in the Alps is the amount of snow in winter. Learn more in my previous Alps Hiking Nature blog:  Bend or Break – Wintry Challenges for Trees in the Alps.

Simone van Velzen

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