Sycamore maple was introduced to private gardens and church yards more than 150 years ago, and has spread profusely along the southwestern coast, along the central coast (Trøndelag) and, to a considerably lesser degree, north to Vesterålen. It is still most common near cities and villages, but seems certain to continue expansion along the coast and fjords. There are many smaller introduced plants spreading, such as rosa rugosa. However, due to the often steep terrain, forestry has been somewhat limited in the coastal area, and many areas with original vegetation remain, but are often fragmented, especially so in the southern part of the ecoregion. American mink, originally escaped from fur farms, have colonized the whole country, and threaten sea bird colonies in some areas, but have not reached the outermost islands such as Røst, which have the largest sea bird colonies. The native otter seem to be dominant in areas with competition. Boreal rainforest Within this long area is a smaller area classified as boreal rainforest based on botanical criteria. Much of the original forests have been destroyed, but a total of 250 forested areas, most of them not very large, have been classified as boreal rainforest. They are located from 63°20'N in Snillfjord in Sør-Trøndelag county and north along the coast to 66°N in Rana in Nordland county, but restricted to areas with high humidity; often shielded from the sun most of the day. Some inland locations are included; these are located in moist locations, often near waterfalls. This is the main area in Europe for boreal rainforest and Norway thus has a special responsibility for preservation. This coastal forest is mostly found at the lower elevations (below 200 m). Botanical criteria for boreal rainforest Due to the long history of human settlement (millennia) with agriculture and more recently forestry management, only fragments remain of the original forest. The boreal rainforests are made up mostly of Norway Spruce (Picea abies) but also included deciduous trees. Common Juniper (Juniperus communis) is also common. There is a rich understory of mosses and ferns. However, the most distinguishing feature is the diversity of lichens, some of which are endemic for this forest, or have their only location in Europe here (they are often found on the northwest coast of North America). Approximately 15 of the most rare or typical species of lichens have been named Trøndelagselementet (named after the Trøndelag region). Pseudocyphella