At the Sunnig Aar grows a loose forest of Swiss stone pines, mountain pines, larch and birch. It is a real primeval forest: some of the gnarled Swiss stone pines resist already 500 years the cold winters and harsh conditions in mountain areas. This slow-growing tree species is found mainly at altitudes between 1500 to 2000 meters. It is considered the most frost resistant tree species in the Alps: it can survive unscathed temperatures of - 43 °C. A bird contributes decisively to the distribution of the Swiss stone pine: the nutcracker is hiding the nutritious nuts of the stone pine as storage for the wintertime. A single animal hides them at up to 10.000 places. Around 20 % of these reserves are forgotten until spring and the seeds may germinate.