Retention trees on regeneration areas are the most
important indicators for measuring the biodiversity value
of forest stand among forest management practices.
Retention trees are ‘lifeboating’ the species of the old
forest throughout the regeneration phase. They also provide
a source of decaying wood throughout the rotation and
provide the habitat for the species that are adapted to the
disturbances and open areas. It has been reported that the
number of species living on the retention trees is greater or
equal to that of the trees of similar size growing inside the
forest. Especially, there have been observed a great number
of rare and endangered species living on the retention trees.
(Ahnlund and Lindhe, 1992; Martikainen et al., 2000;
Siitonen et al., 2000). The research results have not yet
given any proven indications on the optimum amount of
retention trees on various growing conditions.