Lichen Tundra Research Articles

К флоре верховья р. Озерное Горло (Чукотка, северные отроги Чуванского хребта)

The survey conducted in August 2021 revealed the main core of the local flora in the upper reaches of the Ozyornoe Gorlo River (southern Chukotka, Anadyr River basin, northern spurs of the Chuvansky Ridge), which had not previously been studied botanically. The peaks in the Chuvansky Ridge system within the research area vary from (900) 1200 to 1300 (1400) m above sea level. On the mountain slopes, cedar elfin loci are spread, higher up transforming into shrubby and lichen tundra. 127 species from 77 genera and 38 families were identified within the flora of the research area. As a consequence of the low anthropogenic impact, the flora here is represented exclusively by the aboriginal fraction, no introduced species identified. Interesting finds, rarely found in adjacent territories, include Poa aff. tuonnachensis, Juncus brachyspathus, Luzula wahlenbergii, Aruncus kamtschaticus, Pyrola minor, Phyllodoce caerulea, Rhododendron camtschaticum, Antennaria angustata, Saussurea oxyodonta, and Taraxacum sibiricum.

Morphological and anatomical structure of two species of the genus Alchemilla L. (Rosaceae Juss.) in the Alpine belt of the northwestern Caucasus

Two species of the genus Alchemilla L. growing in the alpine zone of the Northwestern Caucasus are considered. A. sericea Willd. occupies rock crevices, A. caucasica Buser grows in alpine lichen tundra. A. sericea, in comparison with A. caucasica, has more compact sizes, a reduced leaf series, rare branching, and later formation of adventitious roots, which secondarily thicken only one season. Its main root is secondary thickens and preserved for a long time. When dying, it is replaced by a lateral one, in which an additional cambium is formed for secondary thickening. A. caucasica forms more branches and adventitious roots to feed and take over new territory. It has the system of epigeogenic rhizomes with a supply of nutrients lying in the upper soil layer. In anatomy, the general plan of the structure of organs is preserved, with the exception of the structure of the main root. A. caucasica is characterized by the accumulation of orange or black contents in the endodermis, phloem, in the cells layer under the epidermis, to protect against the adverse effects of ultraviolet light.

Variation in CO2 and CH4 fluxes among land cover types in heterogeneous Arctic tundra in northeastern Siberia

Abstract. Arctic tundra is facing unprecedented warming, resulting in shifts in the vegetation, thaw regimes, and potentially in the ecosystem–atmosphere exchange of carbon (C). However, the estimates of regional carbon dioxide (CO2) and methane (CH4) budgets are highly uncertain. We measured CO2 and CH4 fluxes, vegetation composition and leaf area index (LAI), thaw depth, and soil wetness in Tiksi (71∘ N, 128∘ E), a heterogeneous site located within the prostrate dwarf-shrub tundra zone in northeastern Siberia. Using the closed chamber method, we determined the net ecosystem exchange (NEE) of CO2, ecosystem respiration in the dark (ER), ecosystem gross photosynthesis (Pg), and CH4 flux during the growing season. We applied a previously developed high-spatial-resolution land cover map over an area of 35.8 km2 for spatial extrapolation. Among the land cover types varying from barren to dwarf-shrub tundra and tundra wetlands, the NEE and Pg at the photosynthetically active photon flux density of 800 µmol m−2 h−1 (NEE800 and Pg800) were greatest in the graminoid-dominated habitats, i.e., streamside meadow and fens, with NEE800 and Pg800 of up to −21 (uptake) and 28 mmol m−2 h−1, respectively. Vascular LAI was a robust predictor of both NEE800 and Pg800 and, on a landscape scale, the fens were disproportionately important for the summertime CO2 sequestration. Dry tundra, including the dwarf-shrub and lichen tundra, had smaller CO2 exchange rates. The fens were the largest source of CH4, while the dry mineral soil tundra consumed atmospheric CH4, which on a landscape scale amounted to −9 % of the total CH4 balance during the growing season. The largest seasonal mean CH4 consumption rate of 0.02 mmol m−2 h−1 occurred in sand- and stone-covered barren areas. The high consumption rate agrees with the estimate based on the eddy covariance measurements at the same site. We acknowledge the uncertainty involved in spatial extrapolations due to a small number of replicates per land cover type. This study highlights the need to distinguish different land cover types including the dry tundra habitats to account for their different CO2 and CH4 flux patterns, especially the consumption of atmospheric CH4, when estimating tundra C exchange on a larger spatial scale.

The first report on the oribatid mites (Acari: Oribatida) in tundra of the Chunatundra Mountains on the Kola Peninsula, Russia

The aim of this research was to obtain initial data on the fauna and abundance of the oribatid mites from the main types of the mountain tundra habitats of the Chunatundra Mountains. Four plots, including two lichen tundra plots, one dwarf shrub tundra plot and one sphagnum bog in the belt of mountain tundra were investigated. Multidimensional scaling and discriminant function analysis were used to identify trends in the fauna and abundance of oribatid species through the explored plots. A total of 70 species and one subspecies from 37 genera and 24 families were found during the course of this investigation. Nine species, one subspecies, one genus and one family of oribatid mites have been added to the fauna of the Kola Peninsula. The families Brachychthoniidae, Oppiidae and Suctobelbidae are the most diverse in the discovered local fauna. According to literature data, the first two families are characteristic of the low tundra communities, the third family is more common for the boreal zone. The discovered oribatid fauna is similar to the fauna of other tundra sites of the Kola Peninsula studied previously and is significantly different to the local oribatid mite faunae of the Scandinavian Peninsula. The abundance of the adult oribatid mites reached 39 080 ind./m2 in the lichen tundra and 56 200 ind./m2 in the dwarf shrub tundra. The minimum abundance of oribatid mites, 18 640 ind./m2 was found in the sphagnum bog. Differences in the oribatid mite complexes of lichen tundra, dwarf shrub tundra and the sphagnum bog were found. The species Carabodes labyrinthicus, Nothrus borussicus, Sellnickochthonius immaculatus, Mycobates sarekensis, and Tectocepheus velatus were associated with the lichen tundra habitats. Nanhermannia sellnicki, Chamobates borealis and a few species of Oppiella and Suctobelbella were associated with the dwarf shrub tundra. Mucronothrus nasalis, Limnozetes ciliatus, Platynothrus peltifer, Trimalaconothrus foveolatus, Limnozetes cf. rugosus, and Trimalaconothrus maior are most characteristic of the sphagnum bog. The family Suctobelbidae was represented by a large number of species, while the families Ceratozetidae and Camisiidae were much less diverse. The low diversity of Ceratozetidae, a high diversity of Suctobelbidae and relatively high abundance of oribatid mites in the explored tundra habitats may be explained by an ambivalent nature of the oribatid community, which combines boreal and arctic features due to marine climate. Also, this result may be a feature of a local mountain tundra which is surrounded by the underlying belts of the mountain forests that are a source of the increasingly diversity of species.

Разнообразие горных тундр с преобладанием в напочвенном покрове лишайников в пределах западного макросклона Приполярного и Северного Урала

В статье приведены данные о разнообразии сообществ горных тундр с преобладанием в напочвенном покрове лишайников ключевых участков Приполярного (хребты Малдынырд, Юаснырд, горы Баркова, Еркусей) и Северного (горный массив Тэлпозиз) Урала. Дана характеристика их структуры, видовой насыщенности, приведены списки доминирующего комплекса видов. Проведена NMS-ординация сообществ, позволившая выделить группы описаний, соответствующие синтаксонам, и показавшая высокую степень зависимости распределения выделенных групп от высоты расположения сообществ. Выявлено 12 синтаксонов лишайниковых тундр ранга ассоциации.

The relationship between the morphological structure and the ecological niche occupied by cereals and sedges in Alpine lichen tundra northwest Caucasus

The relationship between the life form and distribution of cereals, sedges and Lusula spicata (L.) DC. in theAlpine lichen tundra association was revealed. The dependence of plants to forms of relief and certain ecological nicheswas studied. Within the framework of the carousel model (van der Maarel, Sykes, 1993) their occurrence and the speedof the small-scale turnover in the community were estimated.

The first report on oribatid mites in tundra belts of the Lovozersky Mountains on the Kola Peninsula, Russia

The fauna of oribatid mites (Acari, Oribatida) in the mountain tundra on the Kola Peninsula (Russia) is still poorly studied. The main aim of this research is to obtain initial data on the fauna and abundance of oribatid mites of the Lovozersky Mountains. We investigated five plots, including three lichen tundra plots, one dwarf shrub tundra plot and one wetted tundra plot in one of the largest mountain massifs of the Kola Peninsula — the Lovozersky Mountains. Multidimensional scaling and discriminant function analysis were used to identify some trends in the fauna and abundance of species on the explored plots. The abundance of oribatid mites in the lichen tundra reached 23,680 ind./m2. In the dwarf shrub tundra, this value is over three times higher — up to 81,160 ind./m2, which is comparable with the oribatid mite abundance of forest habitats. The minimum values were discovered in wetted tundra (6,200 ind./m2). A total of 71 species, 38 genera, and 24 families of oribatid mites were found during the course of this study. Eight species of Oribatida have been added to the fauna of the Kola Peninsula. A significant difference was observed in the structure of oribatid faunas of the explored habitats. The occurrence in samples and relative abundance of Mycobates sarekensis, Oribatula amblyptera, Tectocepheus velatus and Carabodes labyrinthicus increased in lichen tundra compared to dwarf shrub tundra. Species of Suctobelbidae and Oppiidae were higher in occurrence and relative abundance in dwarf shrub tundra compared to lichen tundra. The occurrence and relative abundance of Trimalaconothrus angulatus, T. maior and Platynothrus peltifer prevailed in wetted tundra as compared to automorphic tundra habitats. The family Suctobelbidae was represented by a large number of species, while the family Ceratozetidae showed a small number of species in the discovered fauna. According to the literature, these features of the fauna are unusual for tundra. A low diversity of Ceratozetidae, a high diversity of Suctobelbidae and high abundance of oribatid mites in dwarf shrub tundra may be explained by the ambivalent nature of the oribatid community in the explored region, which combines boreal and arctic features due to marine climate.

Пространственный анализ распределения мерзлотных условий на Федеральной автодороге Р504 «Колыма» (Якутский участок)

The Yakutsky site of the Federal highway P504 "Kolyma" with a length of 1197 km was investigated. A GIS project was created in ArcGIS format. A spatial geographical analysis of geocryological conditions (soil temperature, seasonal thawing depth, cryogenic processes) using GIS technology was carried out. 12 types of terrain have been identified by cutting out a scale of 1:1 500 000 from the Permafrost-landscape map of the Republic of Sakha (Yakutia). Spatial analysis results are reflected in the form of maps. Quantitative characteristics of permafrost conditions are given in the form of diagrams. It was revealed that the road was mainly laid along sections of low terraces (33,2% of the total area of 100 m of the zone) and the inter-alas type of terrain (10,3%), composed of high-ice deposits. In these areas, frost cracking is most often expressed in combination with other cryogenic processes (53,6%) and thermokarst (21,7%). The temperature of soils in the landscapes of the studied territory most of all varies from −2 to −4 °, the lowest temperatures (−9 °) are found in 3% of the territory in the mountain lichen tundra of the Verkhoyansk Range. The maximum depths of seasonal thawing (> 2,5 m) can be traced only 5% of the total territory. The prevailing value of seasonal thawing depth is from 1,5 to 2 m. Keywords: permafrost conditions, GIS technologies, spatial analysis, soil temperature, permafrost processes, Kolyma highway.

The carbon sink due to shrub growth on Arctic tundra: a case study in a carbon-poor soil in eastern Canada

The microbial respiration of ancient permafrost carbon represents a positive feedback to climate warming. However, warming-induced shrub expansion in circumpolar latitudes may partly offset these emissions, due to greater biomass and litter inputs than that of primary tundra vegetation. Quantifying this carbon sink is challenging as the simultaneous mineralization of ancient carbon renders the attribution of changes in soil carbon stocks uncertain. We measured the contribution of shrubs to the terrestrial carbon reservoir in a Low-Arctic region where ancient carbon stocks are among the lowest in the Arctic. The study site near the eastern shore of Hudson Bay is experiencing rapid Betula glandulosa Michx. expansion throughout lichen tundra. We find that the terrestrial carbon stocks (i.e. soil and vegetation) under a cover of low to medium-size shrubs is increased by 3.9 ± 1.3 kg m−2 , regardless of shrub cover age. Along water tracks, taller shrubs and the transition to moss understories provide an even greater increase in terrestrial carbon (6.5 ± 3.5 kg m−2). Using published maps of vegetation change from 1994 to 2010, we estimate that the carbon sink associated to shrub expansion in our study area (5.228 km2) has been 2.4 ± 0.8 Gg or 29 ± 9 g m−2 yr−1. Extrapolating this result to the Arctic requires additional studies in representative environments.

Ценотическое разнообразие растительности горно-тундрового и подгольцового поясов хребта Маньпупунёр (Северный Урал, Печоро-Илычский заповедник)

The study of coenotical diversity of mountain tundra and open woodland altitudinal belts at Manpupuner ridge (Pechoro-Ilych Nature Reserve) in 2012–2013 continues the previous researches by Institute of Biology Komi Scientific Centre RAS at ridges Schuka-Yol-is, Kychyl-is, Makar-is, Tonder and Turynya-ner, and Mankhambo in 2007–2011 (Deg­teva, Dubrovskiy 2009, 2012, 2014). The data were obtained using the complex of traditional and modern methods of phytocoenotical and floristical researches (Ipatov, Mirin, 2008). 184 relevés (kept in the Phytocoenarium of the Institute of Biology KSC RAS), made at 400 m2 plots in open woodland and forests stands, at 100 m2 plots in meadow, tundra and shrub stands or within the limits of the communities, were set along the profiles at the elevation gradients. The assessment of vertical and horizontal structure, species number and abundance of vascular plants, main mosses and lichens as well as community classification according the dominant approach was carried out. In mountain tundra communities which are located at flat plates and terraces of the upper part of slopes 122 species of vascular plants, 36 of mosses and 37 of lichens were found. Three associations (Fruticuleto-betuletum nanae flavocetrariosum (Fig. 2), Fruticuletum cladinosum, Myrtilletum cladinosum, Fruticuletum cladinosum) of lichen tundra (Table 2), two ones (Fruticuleto-betuletum nanae hylocomiosum, Myrtilletum hylocomiosum) of green moss tundra (Fig. 3, 4) and ass. Bistorto majoris-avenelletum poly­trichosum of Polytrichum-dominated tundra (Table 3) were distinguished. More diverse is vegetation of the open woodland belt where the complex of open woodlands, bushes and meadows is presented. Poor in species number spruce open woodlands with total tree crown density is 0.1–0.2 and of 2–3 m height in the upper part of the belt and 6 m in the lower slope parts, which occur at about 680–760 m,1 belong to associations Piceetum betuloso nanae–caricoso-empetroso-cladinosum and P. avenelloso-myrtilloso-hylocomiosum (Table 4; Fig. 5). Pinus sibirica open woodlands (Table 4) of lichen (Cembretum betuloso nanae–arctoetoso alpinae–flavocetrariosum (Fig. 6) and C. caricoso globularis–vaccinioso uliginosii–cladinosum) and green moss (C. caricoso globularis–vaccinioso uliginosii–hylocomiosum) types were met at 620–640 m at flat terraces (first time in the Pechoro-Ilych Nature Reserve). Open woodlands dominated by mountain ecological form of Betula pubescens occur at 580–770 m more common at east and north-west exposition, but also occur at south-west and north slopes and in the southern part of the Manpupuner Ridge, on terraces. Taxation parameters of the stands change with the elevation changes. In the upper part of this belt, the canopy density is 0.1–0.2, tree height 1.5–2.5 m and stem diameter 2–4 cm, at elevations about 600 m, 0.4–0.6, 8–12 m and 18–26 cm respectively. Five associations are distinguished within this formation: Montano-Betuletum gymnocarpiosum, M.-B. geraniosum albiflorii, M.-B. calamagrostidosum, M.-B. aconitosum (Fig. 7), M.- B. avenellosum (Table 5). Shrub vegetation is presented by Salix spp., Betu­la nana and Juniperus sibirica stands. The willows (Sali­cetum lanatae geraniosum albiflorii and Salicetum lanatae mixtoherboso–calamagrostidosum) (Table 6, Fig. 8) are developed in stream runoffs/valleys at ele­vations 700–770 m. Juniperus communis communities (Juniperetum sibiricae avenelloso-myrtilloso-hylocomiosum (Fig. 9) and Juniperetum sibiricae gymnocarpiosum; Table 6) in the Pechoro-Ilych Nature Reserve are found at 670–780 m in the drained ecotopes at terraces, flat and convex slopes. Betula nana stands (Betuletum nanae empetroso-caricoso-hylocomioso-cladinosum (Fig. 10), Betuletum nanae caricoso-hylocomiosum (Fig. 11) and Betuletum nanae fruticuloso-hylocomiosum; Table 6) cover the largest areas at 680–750 m on terraces, flat, convex and concave slopes and saddles between the individual vertices. In mountain meadows (Calamagrostidetum geraniosum (Fig. 12) and Geranietum mixtoherbosum (Fig. 13)) which do not cover large areas at the ridge and occur on rich wet soils at stream runoffs, valleys and the borders of the stone-fields, 117 species of vascular plants, 27 of mosses and 32 of lichens are found (Table 7). Coenotical core of their flora is formed by species of meadow and mountain meadow eco-coenotical group. Species number at 100 m2 plot vary from 12 to 45 (mean 27). Three associations (Piceetum fruticuloso-hylocomiosum, P. aconitosum and P. dryopteridosum expansae) dominate in the mountain forest belt. The common number of syntaxa of association level at the Manpupuner Ridge is 27 including mountain tundras, bushes, meadows, open woodlands and forests.

Tundra landscape heterogeneity, not interannual variability, controls the decadal regional carbon balance in the Western Russian Arctic.

Across the Arctic, the net ecosystem carbon (C) balance of tundra ecosystems is highly uncertain due to substantial temporal variability of C fluxes and to landscape heterogeneity. We modeled both carbon dioxide (CO2 ) and methane (CH4 ) fluxes for the dominant land cover types in a ~100-km2 sub-Arctic tundra region in northeast European Russia for the period of 2006-2015 using process-based biogeochemical models. Modeled net annual CO2 fluxes ranged from -300gCm-2 year-1 [net uptake] in a willow fen to 3gCm-2 year-1 [net source] in dry lichen tundra. Modeled annual CH4 emissions ranged from -0.2 to 22.3gCm-2 year-1 at a peat plateau site and a willow fen site, respectively. Interannual variability over the decade was relatively small (20%-25%) in comparison with variability among the land cover types (150%). Using high-resolution land cover classification, the region was a net sink of atmospheric CO2 across most land cover types but a net source of CH4 to the atmosphere due to high emissions from permafrost-free fens. Using a lower resolution for land cover classification resulted in a 20%-65% underestimation of regional CH4 flux relative to high-resolution classification and smaller (10%) overestimation of regional CO2 uptake due to the underestimation of wetland area by 60%. The relative fraction of uplands versus wetlands was key to determining the net regional C balance at this and other Arctic tundra sites because wetlands were hot spots for C cycling in Arctic tundra ecosystems.

Spatial variation and linkages of soil and vegetation in the Siberian Arctic tundra – coupling field observations with remote sensing data

Abstract. Arctic tundra ecosystems will play a key role in future climate change due to intensifying permafrost thawing, plant growth and ecosystem carbon exchange, but monitoring these changes may be challenging due to the heterogeneity of Arctic landscapes. We examined spatial variation and linkages of soil and plant attributes in a site of Siberian Arctic tundra in Tiksi, northeast Russia, and evaluated possibilities to capture this variation by remote sensing for the benefit of carbon exchange measurements and landscape extrapolation. We distinguished nine land cover types (LCTs) and to characterize them, sampled 92 study plots for plant and soil attributes in 2014. Moreover, to test if variation in plant and soil attributes can be detected using remote sensing, we produced a normalized difference vegetation index (NDVI) and topographical parameters for each study plot using three very high spatial resolution multispectral satellite images. We found that soils ranged from mineral soils in bare soil and lichen tundra LCTs to soils of high percentage of organic matter (OM) in graminoid tundra, bog, dry fen and wet fen. OM content of the top soil was on average 14 g dm−3 in bare soil and lichen tundra and 89 g dm−3 in other LCTs. Total moss biomass varied from 0 to 820 g m−2, total vascular shoot mass from 7 to 112 g m−2 and vascular leaf area index (LAI) from 0.04 to 0.95 among LCTs. In late summer, soil temperatures at 15 cm depth were on average 14 ∘C in bare soil and lichen tundra, and varied from 5 to 9 ∘C in other LCTs. On average, depth of the biologically active, unfrozen soil layer doubled from early July to mid-August. When contrasted across study plots, moss biomass was positively associated with soil OM % and OM content and negatively associated with soil temperature, explaining 14–34 % of variation. Vascular shoot mass and LAI were also positively associated with soil OM content, and LAI with active layer depth, but only explained 6–15 % of variation. NDVI captured variation in vascular LAI better than in moss biomass, but while this difference was significant with late season NDVI, it was minimal with early season NDVI. For this reason, soil attributes associated with moss mass were better captured by early season NDVI. Topographic attributes were related to LAI and many soil attributes, but not to moss biomass and could not increase the amount of spatial variation explained in plant and soil attributes above that achieved by NDVI. The LCT map we produced had low to moderate uncertainty in predictions for plant and soil properties except for moss biomass and bare soil and lichen tundra LCTs. Our results illustrate a typical tundra ecosystem with great fine-scale spatial variation in both plant and soil attributes. Mosses dominate plant biomass and control many soil attributes, including OM % and temperature, but variation in moss biomass is difficult to capture by remote sensing reflectance, topography or a LCT map. Despite the general accuracy of landscape level predictions in our LCT approach, this indicates challenges in the spatial extrapolation of some of those vegetation and soil attributes that are relevant for the regional ecosystem and global climate models.

Metals in Racomitrium lanuginosum from Arctic (SW Spitsbergen, Svalbard archipelago) and alpine (Karkonosze, SW Poland) tundra.

Arctic-alpine tundra habitats are very vulnerable to the input of relatively small amounts of xenobiotics, and thus their level in such areas must be carefully controlled. Therefore, we collected the terrestrial widespread moss Racomitrium lanuginosum (Hedw.) Brid. in Spitsbergen in the Arctic moss lichen tundra and, for comparison, in the Arctic-alpine tundra in the Karkonosze (SW Poland). Concentrations of the elements Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Na, Ni, Pb, V, and Zn in this species and in the parent rock material were measured. We tested the following hypothesis: R. lanuginosum from Spitsbergen contains lower metal levels than the species from the Karkonosze collected at altitudes influenced by long-range transport from former Black Triangle industry. Principal component and classification analysis (PCCA) ordination revealed that mosses of Spitsbergen were distinguished by a significantly higher Na concentration of marine spray origin and mosses of Karkonosze were distinguished by significantly higher concentrations of Cd, Cr, Cu, Fe, Hg, Li, Mn, Pb, V, and Zn probably from long-range atmospheric transport. The influence of the polar station with a waste incinerator resulted in significantly higher Co, Li, and Ni concentrations in neighbouring mosses in comparison with this species from other sites. This investigation contributes to the use of R. lanuginosum as a bioindicator for metal contamination in Arctic and alpine tundra regions characterised by severe climate habitats with a restricted number of species. This moss enables the control of pollution usually brought solely by long-range atmospheric transport in high mountains as well as in Arctic areas.

Distribution of oribatid mites (Acari: Oribatida) along an altitudinal profile of Mount Vud’yavrchorr (the Khibiny Mountains)

The species composition and distribution of oribatid mites by altitudinal zones of the northeastern slope of Vud’yavrchorr Mount in the Khibiny Mountains were studied. Fifty-two species of oribatids from 30 genera and 20 families were found; 21 species were found in the Khibiny region for the first time. The maximum number of species (33) were found in the mountainous taiga zone under herbaceous–dwarf-shrub spruce forest. Maximum values of population density (more than 190000 per m2) were recorded in the forest-tundra zone under crooked birch forest. Minimum values of population density and species diversity of oribatids were found in tundra ecotopes, especially in the area of lichen tundra. However, maximum values of the indices of oribatid diversity and evenness of oribatid taxocene were recorded under dwarf- birch tundra. The analysis of relationships between the representatives of different morphoecotypes of oribatid mites in the studied altitudinal zones demonstrated that the relative portion of carabodoid species regularly increases with the altitude.

Amorphous silica pools in permafrost soils of the Central Canadian Arctic and the potential impact of climate change

We investigated the distribution, storage and landscape partitioning of soil amorphous silica (ASi) in a central Canadian region dominated by tundra and peatlands to provide a first estimate of the amount of ASi stored in Arctic permafrost ecosystems. We hypothesize that, similar to soil organic matter, Arctic soils store large amounts of ASi which may be affected by projected climate changes and associated changes in permafrost regimes. Average soil ASi storage (top 1 m) ranged between 9600 and 83,500 kg SiO2 ha(-1) among different land-cover types. Lichen tundra contained the lowest amounts of ASi while no significant differences were found in ASi storage among other land-cover types. Clear differences were observed between ASi storage allocated into the top organic versus the mineral horizon of soils. Bog peatlands, fen peatlands and wet shrub tundra stored between 7090 and 45,400 kg SiO2 ha(-1) in the top organic horizon, while the corresponding storage in lichen tundra, moist shrub- and dry shrub tundra only amounted to 1500-1760 kg SiO2 ha(-1). Diatoms and phytoliths are important components of ASi storage in the top organic horizon of peatlands and shrub tundra systems, while it appears to be a negligible component of ASi storage in the mineral horizon of shrub tundra classes. ASi concentrations decrease with depth in the soil profile for fen peatlands and all shrub tundra classes, suggesting recycling of ASi, whereas bog peatlands appeared to act as sinks retaining stored ASi on millennial time scales. Our results provide a conceptual framework to assess the potential effects of climate change impacts on terrestrial Si cycling in the Arctic. We believe that ASi stored in peatlands are particularly sensitive to climate change, because a larger fraction of the ASi pool is stored in perennially frozen ground compared to shrub tundra systems. A likely outcome of climate warming and permafrost thaw could be mobilization of previously frozen ASi, altered soil storage of biogenically derived ASi and an increased Si flux to the Arctic Ocean.

К синтаксономии мелкобугристых болотных комплексов в лесотундре и тундре на севере Кольского полуострова

Mires of the Kola Peninsula were investigated mainly in its southern part (Botch, 1989; Payanskaya-Gvozdeva, 1990; Smagin, 1999а, 1999b). The published relevés of tundra mires of the Peninsula are poor (Kalliola, 1939; Koroleva, 2001, 2006), and this paper surveys pounikkos mire complexes in its northern part, represents their classification according to the Braun-Blanquet approach accompanied by syntaxonomical tables. The investigated area is situated in the north of the Kola Peninsula within the forest tundra and in southern arctic tundra, with the mean annual air temperature between –0.5 °C and –2.0 °C and annual precipitation 600–700 mm. The geological basis is Archean and Proterozoic crystalline rocks, covered by coarse gravelly moraine and sandy fluvial-glacial deposits, and peat deposits in wetlands. Plant cover represents the combination of subarctic birch forests, tundra and mires. The mire complexes occur in river valleys, in lake and between moraine hill depressions, alternating with shrub and dwarf-shrub lichen tundra and forest-tundra on hill tops and slopes. Peat hummock (pounikkos) height is 0.3–0.5 (up to 1.0) м, their diameter is 0.3–0.7 (up to 1.5) м. In July the ice core is kept at 20–30 cm below the surface. Water-logged narrow ditches separate hummocks from each other. Inundated sedges- and water-cotton-dominated lawns, willow thickets along the water currents and small lakes are common within the mire complex. In the 2012 field season mounds and hummocks were densely inhabited by rodents, in particular by Lemmus lemmus. Oligotrophic and ombrogenous mosses lichens dwarf-shrub dominated communities of mounds, small turf hummocks (pounus, pounikkos) and on the margin of mire massifs belong to the alliance Oxycocco−Empetrion hermaphroditi Nordh. 1936 ex Neuhäusl 1969 (diagnostic taxa (DT): Eriophorum vaginatum, Oxycoccus microcarpus, Rubus chamaemorus, Mylia anomala, Sphagnum fuscum) with the ass. Empetro−Sphagnetum fusci subass. typicum Dierssen (1982) 1996 (DT Ledum palustre and Orthocaulis kunzeanus) and Empetro−Sphagnetum fusci subass. dicranetosum elongati (Regel 1923) stat. nov. (DT Dicranum elongatum). Species poor sedges- and cottongrass dominated oligo-, oligomesotrophic fens of flark and lawns belong to the alliance Caricion rotundatae (Kalliola 1939) stat. nov. (DT Carex concolor, C. rariflora, C. rotundata, Baeothryon cespitosum, Eriophorum polystachion, Sphagnum lindbergii, S. compactum, Warnstorfia exannulata, Sarmentypnum sarmentosum, Calliergon stramineum) with three associations: ass. Gymnocoleo inflatae−Caricetum rariflorae ass. nov. (DT Nardus stricta, Sphagnum compactum, Gymnocolea inflata, Anthelia juratzkana), ass. Warnstorfio sarmentosi−Caricetum concoloris ass. nov. (DT the same as for the alliance), ass. Eriophoro polystachii−Sphagnetum lindbergii (Kalliola 1939) stat. nov. (DT Sphagnum lindbergii). Low willows and sedges dominated communities along mire springs or in percolated areas are described as ass. Salici lapponi−Caricetum concoloris ass. nov. (DT Betula nana, Salix lapponum, S. phylicifolia, Calamagrostis strictа, Carex rostrata, Comarum palustre, Molinia caerulea, Viola palustris, Lophozia longiflora) with no affiliation to any alliance. Proposed new alliance Caricion rotundatae occurs in tundra and forest-tundra zone to the north of main areal of alliances Rhynchosporion albae Koch 1926 and Caricion lasiocarpae Vanden Berghen ap. Lebrun et al. 1949, which comprise oligotrophic and mesotrophic flark communities of boreal mires. Among diagnostic taxa of Caricion rotundatae are low sedges and brown mosses and in opposite to the alliance Rhynchosporion albae it doesn’t include the character species of Rhynchosporion albae (Carex livida, Scheuchzeria palustris, Rhynchospora alba). The studied mire complexes are very characteristic for the entire subarctic Fennoscandia, being located in the north of the Kola Peninsula close to the east-northern border of their European distribution area. They are considered to include more fast-growing permafrost hummocks comparing with palsa mires (Grab, 2003). Based upon their high alpha diversity and important ecological and scientific role, the discussed pounus mire massifs are perspective to be examined as possible value natural habitats.

Dynamics of vegetation in the tundra-taiga ecotone on the Kola Peninsula depending on climate fluctuations

The dynamics of northern forest boundary and the state of vegetation in the tundra-taiga ecotone in the northwestern Kola Peninsula have been evaluated using Landsat satellite images obtained in 1986 and 2005, the years encompassing the period of recent climate warming. Values of the normalized difference vegetation index (NDVI) in these years have been calculated to construct a differential index image reflecting changes in the vegetation. Its analysis has revealed an increase in the density of open forests and in the thickness of dwarf shrub vegetation, which has expanded to the lichen tundra.

Effect of reindeer overgrazing on vegetation and animals of tundra ecosystems of the Yamal peninsula

Currently, 380 000 domestic reindeers are grazed on 106000 km2 of the Yamal peninsula. This unique situation was analyzed from a view of an ecosystem role of indigenous people. Attention was paied to two key points: the impact of overgrazing on (1) vegetation and (2) vertebrates. The results of our 30-years investigations were compared with the published vegetation data from the 1930-ies. In our paper, it is demonstrated, that overgrazing has resulted in a substantial transformation of vegetation, mostly in lichen tundra. Recent situation is close to total extinction of lichen pastures on the Yamal peninsula. Due to overgrazing, total availability of grasses and shrubs have also decreased, in grasses by 1.5-2.0 times, low shrubs - almost 8 times, tall shrubs – 2.0 times. The degradation of vegetation leads to desertification of the peninsula. The area of ​​sandy spots with no vegetation is on average about 5.5% of the peninsula land, however, it could reach up to 19% locally. Overgrazing affected the animal populations too. Since 1990, the peaks of lemmings have never reached former high values and become locally-limited and patchy. This has led to a decrease in the number of predators. The number of other tundra birds decreased as well. The decrease reached almost 2 times lower numbers in geese, 3 times in hygrophillous waders, 5.5 times in Lapland bunting, and 2 times in long-tailed Duck and Willow grouse on watershed. The Nenets themselves can not control reindeer population because of rigid social and psychological attitudes based on their traditions. The main aim of the Nenets reindeer-farming is not to create marketable products for a profit, but increasing the reindeer number of itself. A situation has formed, that, on the one hand, the Nenets are not economically dependent upon the society, and on the other hand, the society contributes to preservation of their traditional farming. The Nenets reindeer-farming, thus become an important factor contributing to rapid transformation of tundra ecosystem.

AEROSPACE MAPPING OF THE STATUS AND POSITION OF NORTHERN FOREST LIMIT

We study changes in the position of the northern forest limit and state of vegetation in the taiga-tundra ecotone through aerial and satellite imagery in the context of climate variability and of the projected advance of forests to the north. Our research of reference sites in Kola Peninsula and in Central Siberia has been part of PPS Arctic project of the International Polar Year. Studying the dynamics of ecotones by remote sensing is difficult due to poor display of ecotone vegetation in satellite images, and this required a range of techniques, regionally adapted and based on remotely sensed data of different spatial resolution. We characterize the newly developed techniques that enabled to identify vegetation change in recent decades: advance of forest up the slopes by 30 m in the Khibiny Mountains; advance of lichen-dwarf shrub tundra into lichen tundra in the north of Kola Peninsula; increasing stand density in sparse larch forests in the Khatanga River basin in the Taimyr Peninsula.

Preliminary results of a study on active layer hydrology in the discontinuous zone at Schefferville, Nouveau-Québec

A detailed study of the water balance of a lichen tundra underlain by permafrost was started in September 1976. Data collection at the 9 000 m2 site near Schefferville, Québec includes air and ground temperatures, precipitation, évapotranspiration, and changes in soil moisture storage as well as incoming short-wave and net all-wave radiation. It is shown that the development of the active layer is strongly influenced by the amount and distribution of moisture in the soil at freeze-up. Moisture transfer within the unsaturated zone is shown to be strongly influenced by the temperature field within the active layer during freeze-up. During the thaw season the confinement of infiltrated water by permafrost is not only a major soil moisture reservoir and medium for suprapermafrost ground water flow, but it is also shown to maintain évapotranspiration at or near the equilibrium rate for the tundra as well as causing a significant increase in evaporation from permafrost induced wetlands.