One of the modern requirements of forest management is the conservation of biodiversity by identifying forests with high conservation value (HCV), especially rare ecosystems and habitats (HCV type 3). Based on the systemic and regional approaches, the methodology for determining HCV 3 has been improved and a system has been created in the Kirov region with the distribution of classes and levels. The class of Fir-spruce forests includes two levels – large-fern with the presence of nemoral elements and tall grasses; with the presence of rare and vulnerable species. The class of Pine forests are divided into sphagnum with the presence of rare and vulnerable species, lichen (with steppe elements) and heather. The Forest class with the participation of broad-leaved species has three levels – linden and multi-species forests in the subzones of the middle and southern taiga of the Kirov region, oak forests (including the subzone of mixed forests). The classes of Larch and Black alder forests, Old-aged aspens are not subdivided into levels. The composition of the stand, the age of the prevailing species of the stand, the species composition of the grass-shrub layer, the conservation value and the recommended conservation and forest management regimes each HCV 3 describes; necessary criteria for assessing forest management, monitoring and compliance of forestry activities with international standards are identified. The developed system is not final; it can be supplemented and expanded in connection with newly emerging data. The use of the proposed materials will ensure the conservation of biodiversity of production forests, compliance with the requirements of the National FSC Standard of the Russian Federation for forest management, and positioning of the Kirov region as a supplier of quality wood.