They cover more than 80% of the total area of the Krkonoše Mountains and, with the exception of most of the upper alpine zone, they are distributed in all other vegetation levels. Their species composition and spatial distribution have been greatly influenced by man in the past and by air pollution at the end of the last century. The area of today's forest cover is approximately 37,000 ha on the Czech side and 4,000 ha on the Polish side of the mountains. They are home to more than 60 species of tree species.
The main ones in the sub-alpine zone are Norway maple, ash, mountain ash, mountain elm, summer and winter oak, sticky and grey alder and hazel. In the alpine zone, spruce, white fir, beech, silver birch and downy birch, rowan, sycamore maple and pussy willow. In the lower alpine zone, Scots pine, rowan, Sudeten rowan, Carpathian birch, Silesian willow and Lapland willow.