Recent shifts of alpine treeline ecotone in temperate and boreal part of Northern Hemisphere

Treeline advance is often cited as one of the effects of the global climate change, especially the rise of mean temperatures. However, treeline dynamics is a complex issue. This thesis aims to describe factors that determine the position and dynamics of the alpine treeline and create an overview of treeline dynamics in the temperate and boreal parts of the Northern Hemisphere outside of Europe. A further goal is to create a database of treeline advance at locations in this region and then analyze this database. Of the 20 studied locations, 65 % showed treeline advance while treeline receded at only two locations. The highest rate of advance was recorded in the Rocky Mountains of North Americe, up to 1.59 m/yr. The highest rate of recession was recorded in the San Francisco Peaks, also in North America, where a recession of 1.21 m/yr was recorded. A statistical analysys showed no significant correlation between temperature trends and treeline advance. Locations that had undrgone a change in land use showed both the highest rate of advance and recession. It appears that anthrpogenic activity is an importnant factor influencing the dynamics of alpine treelines