Syntaxonomy and geography of light-coniferous and mixed (Pinus sibirica, Larix sibirica) forests of the Bolshoy Agul River basin (Eastern Sayan, Southern Siberia)

The classification of forests in the Bolshoy Agul river basin (Eastern Sayan) was developed using the Brawn-Blanquet method and cluster analysis. Two zonal forests categories in North Asia – boreal forests of the Vaccinio–Piceetea Br.-Bl. in Br.-Bl. et al. 1939 and hemiboreal forests of the Rhytidio–Laricetea Korotkov et Ermakov 1999 were revealed. Boreal coniferous forests are represented dominantly by two orders of the East Siberian-Mongolian type – Ledo–Laricetalia Ermakov et Alsynbayev 2004 and Lathyro–Laricetalia Ermakov et al. 2002. The first order includes alliance Pino sibiricae–Laricion Ermakov et Alsynbayev 2004 and two associations – Carici globularis–Pinetum sibiricae ass. nov. and Linnaeo–Pinetum sibiricae ass. nov. occurring on long-term frozen soils with different moisture regimes. The second order of the East Siberian-Mongolian type is represented by community Senecio nemorensis – Larix sibirica(Rhododendro–Laricion Ermakov in Krestov et al. 2009). The third order of boreal forests – Piceo obovatae–Pinetalia sibiricae Ermakov 2013 represents extra-zonal communities of the Ural-Siberian geographical type occurring in the moderately warm habitats. Hemiboreal light-coniferous forests of the East Siberian-Mongolian type (class Rhytidio–Laricetea Korotkov et Ermakov 1999, alliance Festuco–Laricion Korotkov et Ermakov ex Ermakov et al. 2000, Campanulo turczaninovii–Laricetum sibiricae ass. nov.) are locally found in the driest sites. The results of the classification and comparative plant-geographical analysis make it possible to correct the border between the East Siberian and Euro-Siberian geobotanical subregions as well as the boundaries of districts, provinces and regions in the forest zonation system of Southern Siberia.