Diversity of larch forests and woodlands of the western macroslope of the Subpolar and Northern Urals

The study of the diversity of plant species and communities on several mountain ridges of Subpolar and Northern Urals (Fig. 1) in the basins of the rivers Kozhym, Kosyu, Bolshaya Synya, Vangyr, Schugor, and Ilych was carried out in 2007–2018 by researches of the Institute of Biology of Federal Research Centre “Komi Science Centre Ural Branch Russian Academy of Sciences”. Special attention was paid to fir (Abies sibirica) forests as well as larch (Larix sibirica) forests and woodlands due to the luck of data on their diversity. The study following both traditional (Polevaya…, 1964) and modern (Ipatov, Mirin, 2008) approaches of geobotanical and floristic researches is based on 168 original relevés (on sample plots of 400 m2 or within the community limits). The geobotanical data set which contains 184 relevés is stored in the archive (phytocoenarium) of the Institute of Biology (above). The community vertical and horizontal structure as well as the diversity and abundance of vascular plants, bryophytes, and lichens were under study. Ecological-phytocoenotical (dominant) approach was used for classification of larch forests and woodlands in the study area using both the author’s and literature data (Yudin, 1954; Gorchakovskiy, 1966; Nepomilueva, 1974; Martynenko, 1999; Neshataeva, Neshataev, 2005; Rysin, 2010; Kucherov, 2019). Larch forests and woodlands of the study area belong to the Montano-Lariceta subformation of the Lariceta sibiricae formation, which belongs to the Therhodendrosa vegetation subtype of the Aciculilignosa vegetation type (Bykov, 1960). The list of syntaxa for subformation Montano-Lariceta (M.-L.) includes 20 associations, 2 subassociations, 23 variants, and 3 community types from 5 forest types — lichen, green moss, herbaceous, hair cap moss and sphagnum ones. Three associations are transitional between various types of forest (Table 2–6, Fig. 2–10). Forest types of this subformation are allocated in different ordination areas of ecological space according to vectors of soil nitrogen content and light (Table 7, Fig. 11). Larch forests and woodlands of type M.-L. cladinosa occur in dry habitats with poor acidic soils, while phytocenoses of M.-L. polytrichosa and M.-L. sphagnosa are common on wet poor and acidic soils and those of M.-L. hylocomiosa on more fertile soils. In the study area, they do not occupy large areas. The communities of type M.-L. herbosa are common in low elevated mesophyte habitats with more fertile soils. Communities of M.-L. hylocomiosa and M.-L. herbosa types widely occur both in mountain forest and woodland altitudinal belts at the western macroslope of the Subpolar Urals northward N 64°. The use of environmental scales and statistical methods to identify classification units of lower rank did not give well-interpreted results. Analysis of the cenotic significance of species in various forest types of Montano-Lariceta revealed the stable and compact “core” of the most frequent species: trees Betula pubescens, Larix sibirica, Picea obovata, Sorbus sibirica, shrubs Betula nana and Juniperus sibirica; dwarf shrubs Vaccinium myrtillus, V. uliginosum, V. vitis-idaea; herbs Avenella flexuosa, Bistorta major, Calamagrostis purpurea, Carex arctisibirica, Empetrum hermaphroditum, Festuca ovina, Trientalis europaea; mosses Dicranum flexicaule, D. scoparium, Pleurozium schreberi, Polytrichum commune (Table 2, 8, 9). Characteristic species of forest type of M.-L. cladinosa are lichens Cladonia arbuscula, C. stellaris, Flavocetraria nivalis, differential species are herbs Silene acaulis, S. pauciflora, Tephroseris residifolia, and lichens Alectoria nigricans, Asahinea chrysantha, Bryocaulon divergens, Cetraria nigricans. The most abundant are dwarf shrubs Arctous alpina, Empetrum hermaphroditum, Dryas octopetala, Ledum decumbens, Vaccinium uliginosum, and herbs Carex arctisibirica and C. globilaris. The moss-lichen layer is dominated by Cetraria islandica, Cladonia arbuscula, C. rangiferina, C. stellaris, Flavocetraria nivalis, and Stereocaulon paschale; also abundant are lichens Cladonia gracilis and C. uncialis, and mosses Dicranum flexicaule and Pleurozium schreberi. Characteristic species of M.-L. hylocomiosa is Avenella flexuosa, differential species are lichens Cetrariella delisei, C. laevigata, Cladonia subfurcata, Cladonia crispata, and mosses Dicranum polysetum and Polytrichum piliferinum; constant and highly abundant species are Avenella flexuosa, Betula nana, Empetrum hermaphroditum, Vaccinium myrtillus, V. uliginosum, and moss Pleurozium schreberi; species with average constancy — Vaccinium vitis-idaea, lichens Cladonia arbuscula, C. rangiferina, and mosses Dicranum flexicaule, Hylocomium splendens, Polytrichum commune. Sometimes dwarf shrubs Ledum decumbens and Rubus arcticus, and bryophytes Barbilophozia hatcheri, B. lycopodioides, Dicranum polysetum, D. scoparium, and Sphagnum angustifolium dominate or co-dominate (Table 8). The mostly diverse is M.-L. herbosa type of larch forests and woodlands (Table 5, 6, 9). Characteristic species are Anemonastrum biarmiense, Anthoxantum alpinum, Calamagrostis purpurea, Chamaenerion angustifolium, Geranium albiflorum, Milium effusum, Rumex acetosa, Veratrum lobelianum, Viola biflora; differential species are Angelica sylvestris, Phleum alpinum, Poa pratensis, Polemonium acutiflorum, Stellaria bungeana, Tanacetum bipinnatum, Trollius europaeus, Viola palustris; mosses Plagiomnium ellipticum, Rhizomnium pseudopunctatum, Rhodobryum roseum. The most constant and abundant are Bistorta major, Calamagrostis purpurea, Geranium albiflorum, Vaccinium myrtillus; abundant but not too constant — Avenella flexuosa; mosses Dicranum flexicaule, D. scoparium, Pleurozium schreberi. Rarely, herbs Aconitum septentrionale, Athyrium distentifolium, Equisetum pretense, Hieracium hypoglaucum, and bryophytes Barbilophozia hatcheri, B. lycopodioides, Hylocomium splendens, Plagiomnium ellipticum, Polytrichum commune, P. juniperinum, P. strictum, Rhizomnium pseudopunctatum dominate or co-dominate. Constant species with low and average frequency are Chamaenerion angustifolium, Solidago virgaurea, Trientalis europaea, Veratrum lobelianum. The most abundant species in tower layers of M. L. polytrichosa communities are herbs Avenella flexuosa, Carex globilaris, and mosses Polytrichum commune, Pleurozium schreberi, Sphagnum girgensohnii (Table 2). Also common are Bistorta major, Calamagrostis purpurea, Rubus chamaemorus, Vaccinium uliginosum. There are no so far characteristic and differential species in this type, perhaps due to lack of data. Shrubs typical for M.-L. cladinosa and M.-L. hylocomiosa types of larch forests and woodlands are abundant in the communities of M.-L. sphagnosa (Table 2): Empetrum hermaphroditum, Ledum decumbens, Vaccinium uliginosum. Some times Vaccinium myrtillus, and V. vitis-idaea dominants. The most abundant but with average or low cover are herbs Bistorta major and Carex arctisibirica. The most abundant in the moss-lichen layer is Sphagnum capillifolium (characteristic species); rarely, also abundant are Sphagnum fuscum, S. girgensohnii, and S. warnstorfii; constant with average abundance is Pleurozium schreberi; Cladonia stellaris and Polytrichum commune are of average constancy. Species of taiga-forest and tundra-mire eco-coenotical groups are common in the dwarf shrub–herb layer of all types of forests under study (Table 2, 8–10). Significance of mountain tundra species is higher in M.-L. cladinosa and M.-L. hylocomiosa types compare to other types. Species of taiga meadow-forest, valley meadow-forest, valley forest and mountain meadow groups are more abundant in the communities of M.-L. herbosa type. Our research contributed to the current literature data on the species and coenotic diversity of the larch forests and woodlands of the western macroslope of the Subpolar and Northern Urals. Although it is obvious that there is a lack of data both for some associations and forest types, so further researches are necessary to clarify the status of syntaxa and to get information about the characteristic and differential species.