On the diversity and ecology of charophyte communities in lakes of the Altai Mountains
Authors: Kipriyanova L. M. , Vishnyakov V. S. , Romanov R. E. , Goponenko A. Yu. 
Published: December 2024

Data on the charophyte communities in Siberia are very scarce (Ilin, 1976, 1984a,b; Kipriyanova, 2005, 2022; Kipriyanova, Romanov, 2013; Sviridenko, Sviridenko, 2016), as well as data on the hydrochemical preferences of charophytes in southern Siberia (Sviridenko, 2000; Sviridenko, Sviridenko, 2003, 2016; Kipriyanova, 2005, 2022; Kipriyanova, Romanov, 2013;). The purpose of this paper is to provide new data on the coenotic diversity of charophytes of the Altai Mountains in the light of the approaches of the Braun-Blanquet classification (Braun-Blanquet, 1964), as well as to characterize the hydrochemical conditions of the water bodies with charophyte communities.

During expeditions in 2018, 2020, 2021 and 2023, new data on the species composition and coenotic diversity of charophytes in 17 lakes in the Ulagansky, Ongudaysky, Ust-Kansky, Turochaksky districts of the Republic of Altai and three lakes in the Altaisky, Zmeinogorsky and Kurinsky districts of the Altai Territory were obtained (Table 1, Fig. 1). In 17 lakes 16 species of charophytes were identified from the genera Chara (11 species), Nitella (4) and Nitellopsis (1) (Table 2). New species for the Altai Territory are Nitella wahlbergiana and N. syncarpa. N. flexilis is noted for the Republic of Altai for the first time. The most common species were Chara strigosa, Nitellaflexilis (in 6 lakes each), Chara globularis (5) and C. contraria (4). The other species were found in one or two lakes. Chara strigosa was previously known in the Altai Mountains only from a single locality, Lake Tashtumes-Kol (Romanov et al., 2014).

In the studied lakes of the Altai region, there are 11 associations and one community from three alliances and two orders within the Charetea intermediae class (Tables 3–4, Fig. 2–5). Six associations were recorded for the Altai Mountains for the first time. They are indicated below by asterisk.

The communities in the order Nitelletalia were observed only in ultra-fresh water bodies with neutral reaction and low alkalinity: associations Nitelletum flexilis, Nitelletum hyalinae, community Nitella wahlbergiana. The communities of associations Nitellopsidetum obtusae, Charetum globularis and Charetum strigosae also are formed under the similar conditions. Communities of the ass. Charetum intermediae were found only in hard waters. The communities of the ass. Charetum contrariae were found in both ultra-fresh and brackish waters. The ass. Charetum canescentis was recorded only in the brackish, hardwater Lake Bukalu. The communities of the ass. Charetum rudis and Charetum tomentosae occur in fresh (but not ultra-fresh) waters. The fact that in Altai communities with a lot of the genus Nitella species were found not in acidic, but in neutral and slightly alkaline waters, does not allow us to accept that these are communities of acidic waters, as indicated by European phytosociologists (Mucina et al., 2016) in the characteristics of the order Nitelletalia and the alliance Nitellion. Thus, on the scale of Eurasia, it is no longer correct to consider syntaxa with the numerous species of the genus Nitella associated only with acidic waters, and it is more correct to consider them as communities of waters with low mineralization.

Nitelletum flexilis was recorded only in the tundra and forest altitudinal belts. The associations Charetum globularis, Charetum strigosae were noted only in the forest belt, while the pattern of Nitelletum hyalinae, Nitellopsidetum obtusae, Charetum intermediae, Charetum tomentosae, Charetum canescentis, community Nitella wahlbergiana, is restricted to the steppe belt, this of Charetum virgatae — to the forest-steppe, and Charetum rudis and Charetum contrariae to both forest and steppe belts.

The productivity of charophyte communities was also studied (Table 5). It was shown that the phytomass can reach 977±429 g abs. dry weight /m2 in case of Charetum intermediae (dominant species Chara papillosa) in Lake Tenginskoye. The phytomass in Charetum contrariae was 790±407, Charetum canescentis — 470±251, Charetum strigosae — 354±177, Nitelletum flexilis — 212±76, Charetum globularis — 144±31 g abs. dry weight/m2.

Similar to previous studies conducted ca. 50 years ago (Ilin, 1984a, b), the charophytes were primarily formers of current communities in lakes Tenginskoye, Yaboganskoye, Bolshoye, and Presnoye. However, it was shown that Lake Aiskoe has undergone considerable changes over this period, as the charophytes that previously occupied depths of 5 to 7.5 m, have disappeared.

From a conservation point of view, communities of perennial species that are confined to oligotrophic and mesotrophic water bodies with stable hydrological and hydrochemical regimes deserve attention. These are primarily communities of Chara strigosa, a species with a disjunctive pattern (Romanov et al., 2014). There are not many regions in Siberia where its relatively numerous and stable populations are known. C. strigosa is listed as a species of concern in most European countries where this species is recorded. On the territory of the Russian Federation, this species is included in the Red Data Books and Lists of the Republic of Buryatia, the Komi Republic, the Udmurt Republic, Arkhangelsk Region (Krasnaya..., 2019, 2020, 2023) and of some other regions. The main threatening factor for C. strigosa, as for most other charophytes, is eutrophication (Romanov et al., 2014). Considering the narrow ecological niche and rarity of C. strigosa, this species has already been recommended for inclusion in the Red Data Book of the Republic of Altai (Romanov et al., 2014). We recommend communities with its dominance to be included in the lists of rare communities, as well as communities of Nitella wahlbergiana, an annual plant that reproduces exclusively by oospores as a low-competitive species, which is sensitive to decline water transparency. On the territory of the Russian Federation, this species is included in the Red Data Books of the Komi Republic and the Arkhangelsk Region (Krasnaya..., 2019; 2020).