Aquatic and helophyte communities in water bodies of the Nenets Autonomous District
Authors: Lavrinenko O. V. , Lavrinenko I. A. , Tsyvkunova N. V. , D’yachkova T. V. 
Published: December 2024

Syntaxonomic diversity of aquatic and helophyte communities was identified on the basis of 267 relevés carried out from 2005 to 2023 in 16 sites in the Bolshezemelskaya and Malozemelskaya tundras, Kolguyev Isl. and the Pechora River delta. For almost all described communities it was possible to determine their belonging to the association level, as many of them consist of species with extensive ranges (circum-, cosmopolitans) and occur in numerous regions on different continents. Prodromus contains 30 associations (with 3 subassociations and 8 variants) from 14 alliances, 9 orders and 6 classes. Four syntaxa of the association rank were left at the community rank due to the small number of relevés.

Aquatic vegetation is represented by communities of the classes Lemnetea (free-floating duckweed communities), Potametea (rooted hydrophytes with leaves floating on the water surface and/or in the water column communities) and Littorelletea uniflorae (amphibious plants in fluctuating shallow water bodies communities).

One association — Lemnetum trisulcae (Table 1, rel. 19–21; Fig. 5) is described in the class Lemnetea. The class Potametea turned out to be the richest, with 10 associations in 2 orders and 2 alliances. These are associations Myriophylletum sibirici, Myriophylletum verticillati, Potametum berchtoldii, Potametum filiformis, Potametum pectinati, Potametum perfoliati, Potametum praelongi, Potametum tenuifolii and community Potamogeton sibiricus (Table 2, rel. 1–38; Table 3, rel. 1–18; Fig. 6–12) in the alliance Potamion within the order Potametalia; Callitrichetum hermaphroditicae and Callitricho–Ranunculetum trichophylli (Table 3, rel. 19–27; Fig. 13, 14) in the alliance Ranunculion aquatilis within the order Callitricho hamulatae–Ranunculetalia aquatilis. Four associations of two alliances are described in the order Littorelletalia uniflorae within the class Littorelletea uniflorae: Callitricho palustris–Sparganietum angustifolii and Sparganietum hyperborei (Table 4, rel. 1–35; Fig. 15, 16) in Sparganion hyperborei, and Callitrichetum palustris and Litorello–Eleocharitetum acicularis (Table 5, rel. 1–5; Fig. 17, 18) in Littorellion uniflorae.

Helophyte vegetation is represented by communities from 3 orders of the class Phragmito-Magnocaricetea. There are associations Petasitetum radiatae (alliance Petasition radiatae) and Equisetetum fluviatilis (alliance Phragmition australis) in the order Phragmitetalia australis (Table 6, rel. 1–21; Fig. 19, 20); and Caricetum aquatilis and Equiseto fluviatilis–Caricetum rostratae (alliance Magnocaricion elatae), Comaretum palustris, Menyanthetum trifoliatae and com. Cicuta virosa (alliance Carici–Rumicion hydrolapathi) (Table 6, rel. 22–34; Table 7, rel. 1–41; Fig. 21–25) in the order Magnocaricetalia. The order Oenanthetalia aquaticae includes the following described or validated associatios: Arctophiletum fulvae (alliance Arctophilion fulvae) with 2 subassociations — typicum and validated ranunculetosum hyperborei Möller ex O. Lavrinenko, I. Lavrinenko, Tsyvkunova et D’yachkova subass. nov. hoc loco, Ceratophyllo demersi–Eleocharitetum mamillatae, Eleocharitetum palustris subass. arctophiletosum fulvae, Hippuridetum lanceolatae Pestryakov et Gogoleva ex O. Lavrinenko, I. Lavrinenko, Tsyvkunova et D’yachkova ass. nov. hoc loco and com. Ranunculus pallasii (alliance Eleocharito palustris–Sagittarion sagittifoliae (Table 8, rel. 1–29; Table 9, rel. 1–28; Fig. 27–31).

The class Isoёto-Nanojuncetea, which unites pioneer ephemeral low grass communities in periodically flooded freshwater habitats, contains one association — Juncetum bufonii (Table 10, rel. 6–8, Fig. 32) from the alliance Eleocharition soloniensis within the order Nanocyperetalia.

Summer-annual pioneer vegetation of periodically nutrient-rich river alluvia, drained muddy bottoms of eutrophic lakes and heavily nutrientloaded anthropogenic habitats is represented by the ass. Tephroseridetum palustrisMirkin, Gogoleva et Kononov nom. mut. nov. (Table 10, rel. 1–2, Fig. 33) from the alliance Bidention tripartitae within the order Bidentetalia and the class Bidentetea.

For aquatic bryophyte vegetation (Mucina et al., 2016: EuroVegChecklist 2) a provisional alliance Calliergonion megalophylli O. Lavrinenko all. prov. is proposed. It unites two associations and one community of hypnum mosses (Calliergonetum megalophylli, Sarmentypnetum trichophylli, com. Sarmentypnum exannulatum) growing underwater, in the water column and and over-watered shores in shallow meso- and eutrophic lakes.

The highest beta-diversity (19 syntaxa) is established in floodplain and river-formed lakes, usually overgrowing, with muddy and sandy-silt bottoms. The lower stand richness (13 syntaxa) and high accumulation of macrophyte phytomass are noted in shallow, well-warmed lagoonal lakes and baths with a thick layer of bottom silt on brackish marshes at the mouths of rivers flowing into the bays. Aquatic plants literally fill such reservoirs, with a single species often growing in these. Comparable stand diversity (13 syntaxa) is established for thermokarst lakes with mineral soils on flat watersheds. The number of syntaxa is much lower (7) in thermokarst lakes on peatlands. Phytocenotic diversity is determined by ecological conditions of habitats — richness of substrate, water acidity, and water temperature, which depends on the proximity of permafrost.