Oak forests    Today forests with prevalence of Q. mongolica occupy significant areas on the eastern and western slopes of Sikhote Alin in the south and central Primorye, on the western and southwestern foothills of Sikhote Alin, on the spurs of Chornye Gory, which penetrate to the southwest of Primorye from Manchuria, and on the ridges surrounding the Hanka-Ussuri plain. Thirty five-forty years ago, forests with prevalence of Q. mongolica occupied 15-16% of Primoryes forest area. Today their area has increased because Pinus koraiensis, Fraxinus mandshurica and other species in high demand on the timber market were felled from mixed forests with considerable share of Q. mongolica to make the latter prevalent among tree stocks.
    Several basic groups of forest types would form depending on afforestation conditions.
    Thin oak groves, grade V-Va, with prevalence of Rhododendron mucronulatum in the underbrush grow on rocky peaks and very steep, preferentially southern slopes. They occupy about 10-12% of the total oak forest area of Primorye, but have very high ecoprotective significance. The tree stocks are commonly found to have an admixture of Larix sp. in the north, and Fraxinus rhynohophylla, Juniperus rigida, and Pinus funebris (P. densiflora?) in the south.
    Oak groves with prevalence of Lespedeza bicolor in the underbrush and with participation of Corylus heterophylla develop over less steep and less rocky, also preferentially southerly slopes, and Weigela praecox in the south, where Vitis amurensis is also commonly present. The rare grass cover consists of xeromesophyte-like species. The tree stock grade is IV, occasionally III. Their composition also includes Larix sp., Picea koraiensis and Pinus koraiensis in the north of Primorye, and Betula schmidtii, Fraxinus rhynchophylla and Abies holophylla in the south. These forests occupy about 40% of Q. mongolica forests in Primorye.
    Q. mongolica forests with prevalence in the underbrush of Corylus heterophylla and C. mandshurica, and involving Eleutherococcus senticosus, Eunonimus spp., Deutzia amurensis, etc. occupy approximately the same areas in Primorye. Liana species include Actinidia kolomicta, A. polygama (in the south) and Vitis amurensis. They occupy gently sloping and not-very-steep slopes of various, but more often southerly directions. Tree stock quality is commonly grade III, seldom IV. The underbrush is dense and consists of representatives of the genera Lonicera, Euonimus, Corylus, Eleutherococcus, etc. Liana species are present in quite large numbers. The grass cover is dense, with prevalence therein of representatives of the fam. Polypodiacea, among which the genera Pteridium, Dryopteris and Athyrium are most numerous. Cacalia spp., Aconitum spp., Valeriana spp., Angelica, etc. participate significantly in the grass cover.
   The main species of these forests,  Quercus mongolica, is characterized by wide ecological amplitude and can therefore occupy such different habitats. Besides, it is considerably more stable than all other tree species against forest fires and felling, retaining its viability after multiple fires  and its growth ability after felling and fires for  decades. Ultimately, oak forests degrade, albeit slowly. Their extreme degradation degree shows in so-called undergrowth tree-shrub thickets, in which Q. mongolica, Lespedeza bicolor and other shrubs form a single 0.5-2-2.5 m-tall canopy. In Primorye, such thickets occupy over one million hectares on ridges of the Hanka-Ussuri plain and the surrounding foothills.
    In addition to  Q. mongolica, Q. dentata grows in the very south of Primorye to form shrub-herbage rare forests on the southwestern coast of Peter the Great Bay. These tree stocks are rare not because of the biological properties of Q. dentata itself, but due to many centuries of man-made influence, chiefly forest fires.