Siberian larch forests in the north of European Russia.II. Northern and middle taiga forests

According to the dominant-floristic approach to vegetation, 10 syntaxa of northernand/or middle taiga Siberian larch (Larix sibirica Ledeb.) forests, namely 4 associationswith 9 subassociations, were distinguished in the North-East of European Russia (all theunits are given in the synoptic table). The 4 of them are known to grow both in the North-East Europe, the Urals, and the Western Siberia. These are all the 3 subassociations(empetretosum, typicum, and myrtilletosum) of the post-fire feathermoss-dwarfshrublarchforest Hylocomio-Vaccinio-Laricetum (L.), also the Rubo saxatili-Vaccinio-L.subass. gymnocarpietosum which is formed both on limestone and gypsum outcrops andafter fires in silicate boreal-forest landscapes.The Ledo-L. in the Pinega R. basin (Arkhangelsk Region) represents the southwesternmostkarst-restricted outcrop of the association widespread in the boreal north ofWestern Siberia. Within the boreal-forest zone of Europe, it is a peculiar syntaxon withthe ancient-Holocene hypoarctic features of its vascular flora, rich in dwarfshrub specieslike Empetrum hermaphroditum, Ledum palustre, Vaccinium uliginosum, Arctous alpina,sometimes even Dryas octopetala.The herb-feathermoss larch forest association Rubo saxatili-Vaccinio-L. is mainlytypical of the carbonate/sulfate landscapes of the area. Its subassociations typicum andjuniperetosum seem to be endemic for the European North-East and the sulfate karstlandscapes of the Pinega R. area, respectively. Subass. juniperetosum is distinguishedby a set of calciphytes (Epipactis atrorubens, Carex ornithopoda, Viola collina, Koeleriagrandis) and also light-demanding disturbance-dependent species (Calamagrostisepigeios, Hieracium laevigatum s.l., etc.); its stands are usually with a dense layer ofJuniperus communis s.l.The Rubo saxatili-Vaccinio-L. as a vegetation type probably evolved from theAconito-L. subass. typicum, a tall-herb larch forest type with Aconitum septentrionalewhich occurs both in limestone/gypsum areas and in non-flooded localities in silicatelandscapes of the Russian plain north and the Northern Urals. The Aconito-L. typicum,in its turn, probably originated from the herb larch forests of the Middle and theSouthern Urals, preserved since the Late Pleistocene. The Aconito-L. subass.spiraetosum medii represents a relict type, preserved on limestone of the Timan Ridgeand the Northern Cis-Urals since the Riss-Wurm interglacial. Its stands are typical offindings of both arctic-alpine (Poa glauca) and forest-steppe (Pulsatilla patens,P. flavescens, Spiraea media) plants.Whereas the Aconito-L. subass. calamagrostietosum langsdorffii is neo-endemic,restricted to the Holocene terraces in the Timan floodplains. The dwarfshrubfeathermossforest types could also develop from the herb-feathermoss ones probablyduring the Middle or even Late Holocene.

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