Abstract
Results of the study and ecological-floristic classification of the forests in the East Khandyga River valley, Republic of Sakha (Yakutia), are presented. The plant communities in floodplain poplar forests, in dry pine forests on floodplain terraces, and in larch-spruce and spruce valley forests are researched. Based on the classification results, four associations were identified, belonging to three alliances. For spruce forests in the valley, a new association, Roso acicularis - Piceetum obovatae, is introduced, whose taxonomic position is a subject of discussion. The authors emphasize high conservation value of spruce forests, serving as refugia for rare boreal plant species in the region.