Vegetation of Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960 class in the East European tundras

Abstract

Communities of Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960 class and Deschampsio flexuosae–Vaccinietalia myrtilli Dahl 1957 order, widespread in the East European tundras, are represented by 2 alliances: Loiseleurio-Arctostaphylion Kalliola ex Nordhagen 1943 (dwarf-shrub-lichen communities in wind-blown habitats with well-drained automorphic soils) and Phyllodoco–Vaccinion myrtilli Nordhagen 1943 (moderately chionophytic dwarf-shrub communities in habitats with well-drained automorphic soils, moderately moist in summer) (definitions by: Ermakov, 2012). Acidic psammozems and podburs composed of sandy sediments are developed in such habitats. In the first half of the 20th century, such vegetation was described in the East European tundras in ecological-physiognomic classification traditions by Soviet geobotanists V. N. Andreyev, I. D. Bogdanovskaya-Giyenef, A. A. Dedov and Z. N. Smirnova. They attributed it to lichen, dwarf-shrub-lichen and dwarf-shrub ve­getation types on sandy substrates. Based upon the analysis of 196 relevés (142 of them are in this paper) from 34 sites on the Kolguyev Isl., Malozemelskaya and Bolshezemelskaya tundras, Pechora River Delta and Northern Timan Ridge (Fig. 1), we described 5 associations (including 3 subassociations and 10 variants) by Braun-Blanquet classification approach; 4 syntaxa are left in the rank of community type. Two associations of Loiseleurio-Arctostaphylion alliance, first described in the mountain regions of Fennoscandia, are also basic in the East European tundras. The area of ass. Empetro–Betuletum nanae Nordhagen 1943 occupying the lower sub-belt of the mountain-tundra belt of Fennoscandia, is also common in the plain areas in more moderate conditions in the south tundra and forest-tundra (Table 4, rel. 1–13; Table 6, syntaxon 10; Fig. 9а, б, 10). Ass. Loiseleurio-Diapensietum (Fries 1913) Nordhagen 1943, described in the upper sub-belt of the mountain-tundra belt, is represented by subass. salicetosum nummulariae Koroleva 2006 in the plain areas with its distribution area from typical tundra on Kolguyev Isl. to the northern forest-tundra in the mainland. Three variants of subassociation are identified on the latitudinal gradient: inops — on the Kolguyev Isl., Diapensia lapponica — in the continental typical tundra and Loiseleuria procumbens — in the south tundra and forest-tundra (Table 2, rel. 1–35; Table 6, syntaxa 6–9; Fig. 4а–в, 5, 6). Subass. Loiseleurio-Diapensietumsalicetosum nummulariae was first described in the tundra zone of the Kola Peninsula for petrophytic communities with a polygonal structure in oligochion and achion habitats (Koroleva, 2006). We attributed dwarf-shrub-lichen communities dominated by chionophobic lichens (Flavocetraria nivalis, Alectoria nigricans, A. ochroleuca, Bryocaulon divergens) with irregularly-mosaic horizontal structure on sandy substrates to this subassociation due to the high similarity of the species composition (Table 2). Ass. Empetro hermaphroditi–Salicetum nummulariae Bogdanovskaya-Giyenef ex Lavrinenko et Lavrinenko ass. nov. hoc loco (Table 1, rel. 1–18; nomenclatural type (neotypus hoc loco) — rel. 6 (author’ number — К157, Kolguyev Isl., Khayropskoye Lake environs, 10.09.2007, authors — O. V. Lavrinenko, I. A. Lavrinenko); Table 6, syntaxa 1–4; Fig. 2а–в, 3) with variants Tanacetum bipinnatum, Racomitrium canescens and Betula nana unites dwarf-shrub communities corresponding to different stages of the succession of the overgrown of open sands. They are common in the typical tundra subzone on Kolguyev Isl. and in the north-east part of Malozemelskaya tundra in sites with large sandy outcrops. The area of ass. Cladonietum rangiferino–arbusculae ass. nov. hoc loco (Table 4, rel. 14–20; nomenclatural type (holotypus hoc loco) — rel. 19 (author’ number — Т29,, Malozemelskaya Tundra, Kolokolkova Bay, Tobseda village (uninhabited) vicinity, 14.07.2002, author — O. V. Lavrinenko); Table 6, syntaxon 11; Fig. 12а, б) is so far limited by the coastal part of the Malozemelskaya tundra (it will probably be expanded). Communities transformed by reindeer grazing are left in the rank of community type — Dicranum elongatum–Salix nummularia com. type (Table 3, rel. 1–28; Table 6, syntaxon 5; Fig. 7а, б, 8) as well as draft-shrub-lichen with Cladonia stellaris — Cladonia stellaris com. type (Table 4, rel. 21–22; Fig. 11а). Regional characteristic species are established for Loiseleurio-Arctostaphylion alliance — psammophy­tic moss Polytrichum piliferum and lichens Cetraria aculeata (incl. C. muricata), C. nigricans, Cladonia pyxidata, C. cervicornis subsp. verticillata. The basic association— Phyllodoco–Vaccinietum myrtilli Nordhagen 1943 in Phyllodoco–Vaccinion myrtilli alliance in the East European tundras is represented by two subassociations: P.–V. m. salicetosum herbaceae subass. nov. hoc loco(Table 5, rel. 1–14; nomenclatural type (holotypus hoc loco) — rel. 4 (author’ number — 88_12, Kolguyev Isl., Bugryanka River in the midstream, 21.08.2012, ­authors — O. V. Lavrinenko, I. A. Lavrinenko); Table 6, syntaxon 12; Fig. 13а and б, 14, 15) — on Kolguyev Isl. and P.–V. m. veratretosum lobeliani subass. nov. hoc. loco (Table 5, rel. 15–33; nomenclatural type (holotypus hoc loco) — rel. 24 (author’ number — БН31_14, Bolshezemelskaya Tundra, Bolvanskiy Nos Cape, 27.07.2014, authors — O. V. Lavrinenko, I. A. Lavrinenko); Table 6, syntaxon 13; Fig. 16а–в, 17 ) — in the mainland areas in typical, south tundra subzones and northern forest-tundra. Floristic differences between them are caused by differences both in area distribution of some species, and habitats. There are some taxa of Salicetea herbaceae Br.-Bl. 1948 class on Kolguyev Isl, which indicates more nival conditions. The subass. P.–V. m. salicetosum herbaceae seems to be widespread on the Kola Peninsula. There are 2 variants in each subassociation: Vaccinium myrtillus and Chamaepericlymenum suecicum. Vaccinium myrtillus communities with Cladonia stellaris and Vacciniumuliginosum subsp. microphyllum are left in the rank of community type — Cladonia stellaris–Vaccinium myrtillus com. type (Table 5, rel. 34, 35; Fig. 18) and Vaccinium microphyllumcom. type (Table 5, rel. 36–39; Table 6, syntaxon 15; Fig. 19) due to the small number of relevés. The results of geographical analysis of vascular plant coenoflora of Loiseleurio-Arctostaphylion alliance syntaxa are as follows: dominating arctic species — 45 %, hypoarctic — 32 % and boreal — 23 %; there are no boreal species among the high-constant ones, the number arctic and hypoarctic species is approximately equal. The analogous data for of Phyllodoco–Vaccinion myrtilli alliance syntaxa: arctic, hypoarctic and boreal fractions — 33 % each; hypoarctic species dominates among the high-constant ones, boreal (including arcto-boreal) — 2times less and only 2 — arctic-alpine species.