Topology, Vegetation and Stratigraphy of Far Eastern Aapa Mires (Khabarovsk Region, Russia)

Aapa mires (string-flark fens) are one of the main types of mires in northern Eurasia. It has an almost continuous distribution from Scandinavia to Kamchatka, disappearing in continental climate areas and becoming one of the dominant types in more oceanic zones. This article first presents the topological features of string-flark aapa, their vegetation and peat stratigraphy related to different elements of microrelief at the southernmost borders of boreal mires of cryolithozone (51–52 N), in the Lower Amur region (Russia). String-flark fens are very similar to the aapa mires originally reported for the European North. The waterlogged minerotrophic central fen, with a ribbed surface pattern, is surrounded by oligotrophic bogs. The mosaic structure of the vegetation cover in the fens is determined by microtopography: mesooligotrophic dwarf shrub–herb–sphagnum strings, mesoeutrophic herb–sphagnum lawns, and sparse herb cover in water flarks. The flora, for the most part, corresponds with the European aapa, and has some characteristics of eastern features. We relate the localized evolution of string-flark complexes with water basin hydrology changes. The formation of string-flark complexes in pre-existing fens was preceded by the cessation of river flood waters over the surface of the mires. The further decline of erosion has led to the development of dwarf shrub–sphagnum communities containing microrelief. The immature strings of the aapa mires attest to the ongoing active change processes of the mires.

Influence of culture medium composition on the micropropagation of Thymus tauricus Klokov et Des.-Shost.

Thymus tauricus Klokov et Des.-Shost. is a perennial dwarf shrub of the Lamiaceae family. This plant has anti-inflammatory, antispasmodic, analgesic and antiseptic properties. The use of biotechnological methods makes it possible to increase the efficiency of traditional methods of breeding and seed production. Our investigation aimed to study the influence of the culture medium composition on the explants morphogenesis at 1-2th stages of Thymus tauricus clonal micropropagation. When comparing three cytokinins, the best explants development was revealed on culture media containing kinetin. Both high vitrification rate of microshoots (31.2-90.2%) and formation of small shoots were observed on media supplemented with BAP or TDZ. The most effective culture medium at the introduction stage is MS with 1.0 mg/l kinetin and 1.0 mg/l GA3 or 1.0 mg/l kinetin. On this medium, on average, 8.4-10.1 microshoots per explant and shoots length of 1.9 cm were obtained. It was found that the optimal culture medium at the actually propagation stage is MS with 1.0 mg/l Kin or 1.0 mg/l kinetin and 0.5 mg/l IAA, on which the multiplication index 26.9-28.5 were obtained. Induction of rhizogenesis with a frequency of 30.2-94.4% and a root length of 1.6-3.0 cm was noted on culture media for the second stage of clonal micropropagation. The results of the studies are the basis for development T. tauricus clonal micropropagation method.

An Annotated and Updated Checklist of the Hungarian Dendroflora

The checklist includes tree, shrub, dwarf shrub, woody liana and epiphyte species that occur or have occurred in Hungary except the settlements and other intensively utilised objects. 437 dendrotaxa were included and evaluated in this list. This means 281 species, 22 subspecies, 128 nothospecies and 6 nothosubspecies. Based on the indigenat, 260 native, 92 alien and 9 cryptogenic dendrotaxa live in Hungary, furthermore 54 cultivated dendrotaxa and 22 dendrotaxa with questionable occurrence. Analysing the invasive status of alien species, 19 invasive or being in the early stages of invasion, 12 naturalised and 61 casual dendrotaxa can be distinguished. According to residence time status, the number of archaeophytes is 16 and that of neophytes is 76. Of the 260 native dendrotaxa, 9 were extinct or presumably extinct. 44 dendrotaxa are considered to be proven endemic, and there are 8 subendemic. Of the 134 nothotaxa on the list, 14 are artificial and 120 are of natural origin.

New data on vegetation of two localities in the southern part of the typical tundra subzone in the Gydan Peninsula

The syntaxonomic diversity of vegetation of two localities in the southern part of the typical tundra subzone in the Gydansky Peninsula includes seven associations, three subassociations and eight variants. New associations (Tanaceto bipinnati–Salicetum polaris Khitun ass. nov. hoc loco, Calliergono cordifolii–Salicetum lanatae Khitun ass. nov. hoc loco), subassociations (Hierochloo alpinae–Hylocomietum splendentis asahinetosumchrysantae Khitun subass. nov. hoc loco, Carici rariflorae–Sphagnetum baltici sphagnetosum steerei Khitun subass. nov. hoc loco) and eight variants are described in this region for the first time. Although in the northern part of the typical tundra subzone they occupy zonal positions, dwarf shrub communities with abundant herbs (Luzula tundricolae–Hylocomietum splendentis Telyatnikov et al. 2019) were not found in the studied locations. Tussock tundra (Sphagno–Eriophoretum vaginati typicum) occupies flat or gently sloping hills, and we consider it as the predominant zonal vegetation. The position of the boundary between the southern and the typical tundra subzones is corrected. According to our observations, it lies further north (up to 100 km on the eastern part of the peninsula) than it was shown on previous zoning schemes. Comparison of the syntaxonomic diversity in the southern and northern parts of the typical tundra showed little similarity, only two associations are common (Hierochloo alpinae–Hylocomietum splendentis Telyatnikov et al. 2019 and Tripleurospermo hookerii–Poetum alpigenae Czerosov, Sleptsova et Mironova 2005). We explain this by differences in local lithology: loams were predominant in the northern part and sands dominated in the southern part.

Polycyclic aromatic hydrocarbons in permafrost peatlands

The concentrations of 15 individual PAHs in 93 peat cores have been determined by using high-performance liquid chromatography methods. In the profile the qualitative and quantitative composition of PAHs was non-uniform estimated in a wide range: from 112 to 3673 ng/g with mean 1214 ± 794 ng/g. Among 15 identified individual PAHs, the main contribution to their total amount was made by heavy highly condensed PAHs in the Eastern European peat plateaus, in particular, 6-nuclear benzo[ghi]perylene (1021 ± 707 ng/g), whereas in West Siberian permafrost peatlands, light PAHs were dominating, mostly naphthalene and phenanthrene (211 ± 87 and 64 ± 25 ng/g, respectively). The grass-equisetum peat contained the maximum of heavy PAHs and the dwarf shrub-grass—the minimum. In grass-dwarf shrub, grass-moss and moss peat, the share of 2-nuclear PAHs was most significant: naphthalene and fluorene, as well as 6-nuclear benzo[ghi]perylene. The presence of benzo[ghi]perylene in the entire peat strata, including its permafrost layer, was a marker of the anaerobic conditions that persisted throughout the Holocene and they were necessary for the synthesis of this compound.

Simulating shrubs and their energy and carbon dioxide fluxes in Canada's Low Arctic with the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC)

Climate change in the Arctic is leading to shifts in vegetation communities, permafrost degradation and alteration of tundra surface–atmosphere energy and carbon (C) fluxes, among other changes. However, year-round C and energy flux measurements at high-latitude sites remain rare. This poses a challenge for evaluating the impacts of climate change on Arctic tundra ecosystems and for developing and evaluating process-based models, which may be used to predict regional and global energy and C feedbacks to the climate system. Our study used 14 years of seasonal eddy covariance (EC) measurements of carbon dioxide (CO2), water and energy fluxes, and winter soil chamber CO2 flux measurements at a dwarf-shrub tundra site underlain by continuous permafrost in Canada’s Southern Arctic ecozone to evaluate the incorporation of shrub plant functional types (PFTs) in the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC), the land surface component of the Canadian Earth System Model. In addition to new PFTs, a modification of the efficiency with which water evaporates from the ground surface was applied. This modification addressed a high ground evaporation bias that reduced model performance when soils became very dry, limited heat flow into the ground, and reduced plant productivity through water stress effects. Compared to the grass and tree PFTs previously used by CLASSIC to represent the vegetation in Arctic permafrost-affected regions, simulations with the new shrub PFTs better capture the physical and biogeochemical impact of shrubs on the magnitude and seasonality of energy and CO2 fluxes at the dwarf-shrub tundra evaluation site. The revised model, however, tends to overestimate gross primary productivity, particularly in spring, and overestimated late-winter CO2 emissions. On average, annual net ecosystem CO2 exchange was positive for all simulations, suggesting this site was a net CO2 source of 18 ± 4 g C m−2 yr−1 using shrub PFTs, 15 ± 6 g C m−2 yr−1 using grass PFTs, and 25 ± 5 g C m−2 yr−1 using tree PFTs. These results highlight the importance of using appropriate PFTs in process-based models to simulate current and future Arctic surface–atmosphere interactions.