Popular Science: Will we lose the views in the Giant Mountains and Jeseníky Mountains?
There is a lot of talk about the consequences in connection with global climate change and increasing temperatures, with faster changes in mountains being one of these results, often related to the treeline. But we must realize that there are many more factors.
Climatic factors are generally the most important; they prevent trees from growing in higher elevations. There are also geomorphological factors and disturbances disrupting forests. They include, for example, steep slopes, mass movements, avalanches and insect outbreaks. Land use and human activities are changing in the study area as well. The human impact was greater in the past. Livestock was grazing there and this contributed to the present-day timberline.
The timberline on the upper areas in the Hrubý Jeseník Mountains and in the Giant Mountains has 1600 ha, respectively 5500 ha. The temperature has increased by 1°C in the last hundred years and the annual average is about 1-2 °C. The annual rainfall is high, about 1200-1400 mm (the average in the Czech Republic is 671 mm) and there is also a short vegetation season. The treeline is situated about 1200-1400 m above sea level.
The authors compared aerial images from 1936 from the Giant Mountains (and in the case of the Hrubý Jeseník Mountains from 1953) with the present images from 2005. On the website http://kontaminace.cenia.cz/ you can see aerial images of all of the Czech Republic from 1949-1954.
The period was divided into two parts. In the first one, to the end of sixties, the treeline grew more than in the second part. One of the causes is the decline of agriculture and subsequently the forest could expand faster on the site of former pastures. The vegetation and topography of relief were the most important factors. Groups of trees are resistant against climatic conditions and they can also compete more successfully with unoriginal shrubs of dwarf pine. In the event of low density spruce trees, the importance of topography (the aspect and slope of the hillside) increased. In the Hrubý Jeseník Mountains the forest reached the edge of the rounded range, where climate conditions prevent further expansion, mainly due to long-lying snow, wind and frozen soil and also the influence of vegetation. These places are more suitable for shrubs, for instance dwarf pine.
In comparison with other mountains in Europe the treeline increase is small; it is about 0.3 m per year in the Hrubý Jeseník Mountains and 0.43 m per year in the Giant Mountains. This is a result of the factors mentioned in the case of the Jeseníky Mountains and is also caused by acid rain in the forests. Moreover, the comparison shows the more important role of winter temperatures than summer temperatures for treeline movement in all the mountains in Europe.
The treeline in the Hrubý Jeseník and Giant Mountains has moved less than half a meter a year in the last eighty years. This change is small compared to other European mountain ranges. The movement has a few reasons. Climatic: increasing temperatures, geomorphological: related to mass movements and topography, biogeographical: competition among species and condition of forest before investigation and finally human factors related to acid rain anda decline in the agricultural usage of upper locations in the mountains.
TREML, V., CHUMAN, T. (2015): Ecotonal Dynamics of the Altitudinal Forest Limit are Affected by Terrain and Vegetation Structure Variables: An Example from the Sudetes Mountains in Central Europe. Arctic, Antarctic and Alpine Research 47, s. 133-146.