Syntaxonomic diversity of the vegetation in the southern tundra subzone of the Tazovsky Peninsula is represented by six associations, three subassociations and three variants. Four associations (Dicrano maji–Salicetum lanatae Khitun ass. nov. hoc loco, Sphagno girgensohnii–Betuletum nanae Khitun ass. nov. hoc loco, Empetro subholarctici– Eriophoretum vaginati Khitun ass. nov. hoc loco, Eriophoro leiocarpi–Caricetum rotundatae Khitun ass. nov. hoc loco), the three subassociations (Hierochloo alpinae– Hylocomietum splendentis empetretosum subholarctici Khitun subass. nov. hoc loco, Eriophoro leiocarpi–Caricetum rotundatae typicum Khitun subass. nov. hoc loco, Eriophoro leiocarpi–Caricetum rotundatae caricetosum chordorrhizae Khitun subass. nov. hoc loco) and the three variants are described for the first time. A high degree of similarity was found between vegetation of the Tazovsky Peninsula and vegetation of the southern part of the Gydansky Peninsula (the typical tundra subzone). They have four of six associations in common, whereas with the northern part of the typical tundra there is only one association in common.

The syntaxonomic diversity of vegetation in the upper reaches of the Enga-Yu River is described. The specificity of the vegetation in the study area was determined by the ubiquitous occurrence of ultramafic rocks, which contributed to an increase in the harshness of habitats due to the high concentration of heavy metals and the low calcium content. Unfavorable geochemical environments caused the absence of several common in this region species and in the same time the change of ecological preferences and ecological amplitude of other species. Within the lower and middle parts of the alpine belt, we distinguished and described for the first time 4 associations and 2 subassociations. Cladonio rangiferinae–Caricetum arctisibiricae ass. nov. with 2 subassociations (C. r.–C. a. typicum subass. nov., C. r.–C. a. dicranetosum acutifolii subass. nov.) we assigned to the class Loiseleurio procumbentis– Vaccinietea Eggler ex Schubert 1960. Asahineo chrysanthae–Racomitrietum lanuginosi ass. nov. is placed into the class Carici rupestris–Kobresietea bellardii Ohba 1974. Two associations were distinguished as provisional. Tephroserido tundricolae–Bistortetum ellipticae ass. prov. comprising snowbed vegetation, is not assigned yet to any higher unit. Festuco arcticae–Caricetum arctisibiricae ass. prov. comprises meadow communities, it is assigned to the class Juncetea trifidi Hadač in Klika et Hadač 1944 and order Juncetalia trifidi Daniёls 1994. It is not assigned to any alliance due to the shortage of data. The peculiarity of these provisional associations we explain by the influence of ultramafic rocks.

The syntaxonomic diversity of mountain tundra vegetation within the axial part of the Polar Urals is described. We distinguished 5 associations and 3 subassociations assigned to 3 classes of phytosociological classification. 4 associations and 3 subassociations are described for the first time: Pediculari lapponicae–Betuletum nanae ass. nov., Dactylino arcticae–Empetretum subholarctici ass. nov. and Br yocaulo diverg entis–Vaccinietum uliginosi solorinetosum croceae subass. nov. we assigned to the class Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960; Dicrano laevidentis– Bistortetum viviparae ass. nov. – to the class Carici arctisibiricae– Hylocomietea alaskani Matveyeva et Lavrinenko 2023, Rhytidio rugosi–Dryadetum octopetalae ass. nov. with 2 subassociations – typicum subass. nov. and salicetosum arcticae subass. nov. – to the class Carici rupestris–Kobresietea bellardii Ohba 1974. Specificity of altitudinal and latitudinal distribution of different syntaxa in Polar Urals is shown. Communities of the mountain tundra in the southern part of the Polar Urals are analogous to the zonal communities of the southern tundra, those in the middle part of Polar Urals are similar to such in the southern stripe of the typical tundra, and those in the northern part are analogous to the northern stripe of the typical tundra subzone.