The majority of untouched natural boreal forests have been regenerated through large catastrophes, occurring by intervals between 50 and
100 years. Storm and fire will open the landscape, result in a huge amount of dead or dying trees and let the pioneer tree species germinate.
These processes are the guideline for Finnish forest management today.
The main focus by maintaining the biodiversity in Finnish boreal forest zone is directed to managed forests. Nature-orientated silviculture
on stand level is practised. The site type classification, a reflection of the modern concept of biodiversity and developed by Cajander early in
1900s, on the basis of natural vegetation composition of the site, has the central role by choosing tree species, regeneration methods and
thinning procedure, and reflects also on the site productivity. The small size of stands, the abundance of natural seedlings in planted stands
and the popularity of mixed stands have a positive impact on biodiversity of forests. The protection of small-sized valuable habitats in
commercially managed stands, the leaving of retention trees standing and lying in the forest in all phases of the rotation, are activities made
for biodiversity. Many insects and fungi are adapted to catastrophes and so they can survive in single stems left on regeneration areas.
Maintaining the biodiversity in multifunctional forests is also supported by the new forest legislation and by the criteria of Finnish Forest
Certification System.
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