Den alpina trädgränsen i ett föränderligt klimat - Studie över trädgränsen i de svenska fjällen

Sammanfattning: As temperatures on Earth are rising, the Polar regions experience most rapid climatic changes. In the Swedish Scandes, the alpine tree line is considered as one of the most sensitive indicators of climate change. Therefore, the aim of this study is to study the most important abiotic factors driving position change of the alpine tree line. Through a literature study, these mechanisms were studied and furthermore explored in relation to climate change and its possible future effects on the tree line. This study shows that temperature can be considered as the most important factor behind tree line position. Other main factors are vegetation season length, snow cover and wind. It was found that tree lines have advanced to higher altitudes during the last century in the Swedish mountains. The maximum detected change found reported in literature, was 200 m. These changes correlates to the atmospheric temperature rise during the same period. Thus, the changes align with recent climate change. The climate in the Swedish mountain range is according to climate scenarios thought to get both warmer and wetter. This will have implications for the alpine vegetation as rising tree lines alter alpine ecosystems. Through simulations of future tree line advance, the alpine tundra is considered a threatened ecosystem. This could have implications for the biodiversity and the reindeer grazing opportunities of these areas.