The Cairngorms National Park is said to have a continental climate with summers being generally warmer and winters colder and less wet than you might expect. The high plateaux and the valley floors experience very different climates from each other and to live on the plateaux, plants and animals must be very tough and well adapted to survive.
The wind on the hilltops is a dominant factor that is rarely absent. In winter, high winds blow exposed ridges clear of snow and in summer they can dry out thin soil and blow it away.
Freeze–thaw action and frost at higher altitudes keep the soil structure open and prevent it settling, making it difficult for plants to take root.
Plants that can survive these conditions need to be well adapted and hardy for several reasons:
- To reach deep nutrients and moisture. Most plants are deep-rooted, tough, woody species able to grow through the gravels, such as crowberry and blaeberry.
- To reduce evapotranspiration by wind. Crowberry resists losing water by its low form and small, curled-in leaves with a waxy cuticle. Blaeberry avoids the worst affects of the winter weather by losing its leaves then.
- To actively trap moisture. Other plants retain moisture in hairs on stems or leaves, e.g. alpine lady’s mantle, or by their cushion habit, e.g. the pink-flowered, moss campion.
A short growing season, as a consequence of climate and altitude, means that setting seed is an unreliable way of reproduction for many montane species. Most plants spread by the very slow, but more reliable, method of putting out vegetative shoots, e.g. the tiny least willow, or bulbils, as in the case of the grass viviparous fescue and viviparous (alpine) bistort.