Burned-out sites and felling in different
forest formations are occasionally replaced by pure aspen trees (P. davidiana)
or mixed with birch and other species. Forests with prevalence of P. davidiana
are most characteristic of gently sloping areas and their trains and of
those above-the-flood-plain terraces of the Hanka-Ussuri plain; however,
some sites occur in various parts of the Sikhote Alin forest belt. These
forests have no independent significance. In mixed young trees with participation
of conifer species, aspen overgrows valuable larchwood and, moreover, conifer
species. Consequently, aspen is felled first of all to shorten the time
needed to restore prevalence of valuable species.
Sites of native forests with prevalence of Alnus hirsuta occur very seldom in widened valleys of small- and medium-size rivers. Sites of pure alder groves form most frequently over wet river terraces, where other valley forests, in which A. hirsuta was a concomitant species, were either destroyed or highly damaged during logging or transportation. Its overall prevalence is relatively short-lived, and by the time its first generation matures conditions arise for mixed tree stocks to form. The significance of A. hirsuta is chiefly in that it rapidly covers exposed defoliated river valley sites to thereby perform a protective role.
Groves of Alnus japonica occur sporadically on the seacoast of Primorye from the very south to Olga Inlet to be of protective significance as communities capable of enduring a certain degree of coastal habitat salinity.