Classification of ultracontinental boreal forests in central Yakutia

Abstract

Using the Braun-Blanquet approach, five associations of boreal forests were distinguished in central Yakutia, the most continental part of eastern Siberia. Ecological features of the syntaxa were explained with the use of the DCA ordination of 50 relev?s. All available data from eastern Siberia were involved in the study for syntaxonomic analysis. Central Yakutian boreal forests were classified into two classes: Rhytidio-Laricetea sibiricae KOROTKOV et ERMAKOV 1999 - ultracontinental light coniferous hemiboreal forests, and Vaccinio-Piceetea BR.-BL. in BR.-BL. et al. 1939 - typical coniferous taiga forests of northern Eurasia. A new concept of higher syntaxonomic units of the class Vaccinio-Piceetea in eastern Siberia has been developed. Three orders represent the diversity of taiga forests: (1) Cladonio-Vaccinietalia KlELLAND-LUND 1967 (with alliances Hieracio umbellati-Pinion sylvestris ANENKHONOV et CHYTRY 1998 and Sax?frago bronchialis -Pinion sylvestris all. nov.) - light coniferous boreal forests occurring in dry and moderately dry oligotrophic sites in various climatic sectors of Northern Eurasia; (2) Lathyro humilis-Laricetalia cajanderi ord. nov. (with alliances Aulacomnio acuminati-Laricion cajanderi all. nov. and Rhododendro daurici-Laricion gmelinii all. nov.) - zonal boreal forests with xeric elements, which are typical of regions of northern Asia with cold, dry ultracontinental climate; (3) Ledo-Laricetalia cajanderi ord. prov. (with alliance Ledo-Laricion cajanderi prov.) - North Eurasian boreal forests occurring in cold sites with excessive soil moisture, sometimes water-logged. Phytogeography and ecology of these orders are discussed in comparison with other regions of northern Asia.