Forest Species Threatened by Efficient Forestry
Around two thirds of Finland’s land area is covered by forest. For hundreds of years, slash-and-burn agriculture and tar burning have influenced the structure of forests. Also, the intensive forestry practised after World War II has caused significant changes is forest habitats. Few natural forests remain, and they are located mainly in protected areas.
In natural forests, decaying wood of varying size and in various stages of decay is formed all the time. The decaying wood originates from various tree species, and is more abundant than in commercial forests. As trees fall, they create small openings where new saplings grow. Deciduous trees, which demand more light, grow in the slightly larger openings, whereas spruces grow in the more shaded ones. Due to the constant changes, a natural forest is mosaic. Trees of differing size and species grow in random order; occasional small openings are found, as well as thickets.
As a result of effective fire prevention, extensive forest fires hardly ever occur in Finland. In the past, there were frequent forest fires that left behind dead or dying charred wood. If a forest fire is limited to ground level, the entire tree stand may survive. If the fire reaches the tree tops, at least some of the trees die, and sometimes even all of them. Forest fires usually increase the mosaic-like patchwork of forests. After the fire, dead and decaying wood is found unevenly distributed in the forest. Saplings grow in the openings formed. The variations in the age and species distribution of the trees as well as the spatial variation of the forest are often increased. Therefore, fires increase the mosaic-like structure of forests.
Species Have Become Threatened
Intensive forestry has caused the forests to become fractioned and monotone. Due to this development, many Finnish forest species have become threatened.
Approximately three percent of Finland’s forest species are classified as endangered, primarily as a result of forestry use, changes in the age and species distribution of trees, and the decrease of decaying wood.
The number of threatened species in forests:
Source: Rassi, P., Alanen, A., Kanerva, T., Mannerkoski, I. (ed.) 2001: The 2000 Red List of Finnish Species (in Finnish) – Ministry of the Environment &amp; Finnish Environment Institute, Helsinki.
Forests are the primary habitat for 37 percent of the threatened species in Finland. Another 46 percent of the species are found both in forests and in other habitats. One third of the species that have become extinct in Finland were forest species. Particularly invertebrates, especially beetles, as well as fungi have become extinct from forests. The becoming of more threatened has been the most rapid in the forests of southern Finland. Forests also are by far the most important habitat for monitored species.