Classification of vegetation of technogenic habitats of Chukotka: new syntaxa of association Arctagrostietum arundinaceae Sumina 1994
Authors: Sumina O. I. 
Published: May 2019

Industrial development of the Arctic is expanding year by year. Instability of tundra ecosystems to external impacts is increasing under the conditions of a changing climate, so the urgency of biodiversity conservation problem is steadily growing for the Far North. To assess the current condition of ecosystems and prevent their undesirable changes an ecological monitoring has to be widely used. Its results are especially valuable if based on data about the long-term dynamics of studied parameters. This paper continues a number of our publications devoted to the classification of vegetation developing on technogenic habitats in various regions of the Russian Far North (Sumina, 1994, 1995, 2012, 2013; Sumina, Koptseva, 2004). We studied vegetation forming during primary successions on disturbed lands where plant and soil cover had been completely removed (quarries for extraction of building materials, bulldozed sites, etc.). Classification (including full relevés) of vegetation on technogenic habitats of Chukotka in the vicinity of the settlements of Egvekinot, Iultin, and in the middle reach of the Amguema River valley was published in 1994 (Sumina, 1994). Later, the data which have been collected in 1984 in the vicinity of Pevek town were also included in analysis, and one of the previously described associations (Arctagrostietum arundinaceae Sumina 1994) was subdivided into 3 subassociations. The synoptic tables for all abovementioned regions were published (Sumina, 2013). Thereby, to finish our study it is necessary to publish relevés from the neighborhood of the Pevek town, which is the aim of the present paper. The Pevek town (69°42′ N, 170°18′ E) is located in the subzone of the northern hypoarctic tundra (Katenin, 2000). The vegetation developing on 2 rubble quarries was investigated. The quarries are located on the slopes of the Janrapaak mountain (69°42′35″ N, 170°22′21″ E) and Peekinei mountain (69°41′40″ N, 170°20′2″ E). In 1984, the time of natural recovery (it was determined using available documentation and interviewing witnesses) was from 2–5 to 12–15 years (we used such age classes: I — up to 5 years, II — from 6 to 10, and III — from 11 to 15). Within the limits of a single quarry, there were sites which recovering for different periods of time. The relevés were made on plots 25 m2, situated in homogeneous stands with constant physiognomy, dominant species, and total cover. There were noted: position in relief, microrelief of ground surface, granulometric composition of substrate, moistening, stand physiognomy, total vegetation cover, cover of vascular plants, mosses, and lichens, and cover-abundance estimates for every species. If cover was less than 1 %, the modified estimates of the Braun-Blanquet abundance scale were used (Barkman et al., 1964). When data were treatment, the species cover estimated in percent was translated according the following point scale (Økland, 1990): 1 — r; 2 — +; 3 — +1 (< 1 %); 3* — 1 %; 4 — 2–4 %; 5 — 5–12 %; 6 — 12.5–25 %; 7 — 25–50 %; 8 — 50–75 %; 9 — 75–100 %). Taking into account the low species number in pioneer communities, wide geographical area, large ecological amplitude, and high frequency along successional gradient which are typical for many apophyte species, we used “differentiating combination of species” (Molenaar, 1976; Matveeva, 2006) to distinguish syntaxa. The final table of vegetation of technogenic habitats in the Pevek town area includes 37 relevés. Plant communities were classified using the Braun-Blanquet approach (Westhoff, Maarel, 1978). The classification involves syntaxa of the following levels: association, subassociation, variant, subvariant, and community type. The vegetation of technogenic habitats of Chukotka belongs to alliance Poion glauco-malacanthae Sumina 1994, which has 4 associations (Sumina, 1994, 2013). Ass. Arctagrostietum arundinaceae Sumina 1994 is the most widespread between them. In the vicinity of the Pevek town the new its subassociation was distinguished and described. Subass. Arctagrostietum arundinaceae oxytropi­de­tosum czukoticae subass. nov. hoc loco (table 1; table 2, N 7–37, holotypus — N 17). Characteristic species: Oxytropis czukotica, Draba nivalis, Minuartia arctica, Peltigera didactyla, Artemisia arctica. The peculiarity of communities is the low frequency of one of the alliance characteristic species (Chamaenerion latifolium), the presence only Arctagrostis arundinacea from the characteristic species of the ass. Arctagrostis arundinacea, and a set of species which are typical for mountain rubbly tundra. Communities of the subassociation are confined to dry or moderately moist (very rarely — to moist) rubbly grounds. The time of vegetation recovery varies from I to III classes of age. Total plant cover ranges from 3 to 70 %; in most cases it is not less than 20 %. Cover of vascular is 1–50 %. Their number in communities is different (11–28), and the average values in the subvariants varies from 14 to 24. Moss cover is <1–60 %, usually it is not less than 10 %. Lichens are present in most communities with cover <1 %. Subassociation includes 2 variants and 6 subvariants, detailed description of which is given. Simultaneously with subass. Arctagrostietum arundinaceae oxytropidetosum czukoticae in the Pevek town area the community type Puccinellia hauptiana–Descurainia sophioides with characteristic species of the alliance and two typical pioneer species (Puccinellia hauptiana and Descurainia sophioides) was distinguished. This community type corresponds to the very first stages of the primary succession. The average value of total cover is 25 %, cover of vascular — about 20 %, mosses — 15 %. Significant features are a small number of species (2–10, the average — 7), and the absence of lichens. In Chukotka, syntaxa which are below than an association level have the same features as in other regions of the Russian Far North (Sumina, 2013). Subassociations always spread in a certain region and do not go beyond its limits. Variants and subvariants have a narrow-local distribution and subtler reflect the specificity of disturbed habitat conditions or position of communities on successional gradient. The diversity of quarries vegetation is driven by random factors as well as complicated process of recovery dynamics. The final stage of primary succession should be tundra coenoses belonged to syntaxa combined the natural vegetation, but incessant technogenic disturbances support the existing of communities of all stages of succession, including pioneer ones. Accordingly, the distinguished syntaxa of thechnogenic vegetation also continue their existence. Only the analysis of the long-term vegetation dynamics can answer the question “has to be confirmed or rejected the last statement?” Our materials can become the basis for such an analysis.