In Primorye, native (natural) larchwood
forests have very limited distribution to occupy as a rule habitats unfavorable
to other forest-forming species. These are mostly perpetually water-logged
and bogged floors of intermontane depressions, e.g. the lower sections
of Bikin and Ussuri river basins, flat expansions of river valleys in the
plain-piedmont areas of Primorye, and wide low coastal terraces in the
north.
The most widespread are herbaceous
larchwood occupying 30-35% of the Primorye’s total larchwood area. With
worsening of habitat drainage and greater bogging, moss-shrub (Vaccinium
ulginosum, Betula midendorfii, Ledum spp., etc.) forests form to be followed
by moss (Spagnosum) larchwood forests. The tree stock quality in herbaceous
types normally corresponds to class III, occasionally II; but in the extreme
row links of increased moistening it can decline to class IV; the quality
of shrub types is not over class IV, and that of sphagnum types is V and
lower. Most of these forests are included in different-purpose protective
belts.
Larchwood forests occupying bogged
depressions in the central areas of basalt plateaus of the main Sikhote
Alin watershed present special interest, being as it were a botanic-geographic
curiosity of Primorye, since they “reproduce” in miniature in the south
of the Russian Far East landscapes typical of more northerly regions. Besides,
they are seed reservations.
Secondary larchwood forests, arising
after fires, chiefly in spruce-fur forests, occupy quite considerable areas
in central and northern Primorye. Many of them regrow and have a second
tier formed by fur and spruce. Mature spruce-fur forests with participation
of old large larchwood trees also occur. This shows that in the presence
of fur and spruce seed sources near fire-causing larchwood forests dark
coniferous forests, return to their former condition, albeit slowly. All
forests with prevalent Larix spp occupy less than 20 percent of the forest-covered
area of Primorye.