On the tree line. Photo: Naturcentrum AB.On the tree line. Photo: Naturcentrum AB.

Forest advancing up the mountains

When the thick inland ice began to melt, the highest peaks in Gränslandet were bared. The mountains that first saw the light of day were Storvigeln, Elgåhogna, Store Svuku and Gröthogna. Soon small trees began to sprout. First mountain birch, followed by pine and shortly after that, the odd spruce. The climate became warmer and many of the peaks in Gränslandet were forested. The tree line was 400–500 metres higher up than it is today. In some areas there were even broad-leaved deciduous trees such as oak, elm and linden growing at high altitudes.

In the last 9 000 years, however, the trees have mostly “retreated”, albeit at a slow pace. Not only climate, but also felling and grazing have influenced how high up the slopes the trees grow.

But the effect of grazing has been reduced in the last 100 years. And something even more dramatic is taking place. We have become familiar with words such as greenhouse effect and climate change. The Earth is getting warmer at an increasing rate. This has an effect on Gränslandet and the forests that grow here.

In the past 100 years, the tree line for pine, spruce and mountain birch has risen by around 100 metres. What will walking be like in Gränslandet in the future if this development continues?

Sweden’s highest tree lines...

... are found in Gränslandet. On Mount Brattriet in Rogen Nature Reserve birch grow at 1 137 metres and pine at 1 044 metres above sea level. Spruce has its highest location on Mount Städjan, where it reaches up to 1 115 metres above sea level.