An analysis of the landscape spatial structure and diversity in the mountain ranges of Northeast Siberia is essential to assess how tundra and boreal landscapes may respond to climate change and anthropogenic impacts in the vast mountainous permafrost of the Arctic regions. In addition, a precise landscape map is required for knowledge-based territorial planning and management. In this article, we aimed to explore and enhanced methods to analyse and map the permafrost landscape in Orulgan Ridge. The Google Earth Engine cloud platform was used to generate vegetation cover maps based on multi-fusion classification of Sentinel 2 MSI and Landsat 8 OLI time series data. Phenological features based on the monthly median values of time series Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), and Normalized Difference Moisture Index (NDMI) were used to recognize geobotanical units according to the hierarchical concept of permafrost landscapes by the Support Vector Machine (SVM) classifier. In addition, geomorphological variables of megarelief (mountains and river valleys) were identified using the GIS-based terrain analysis and landform classification of the ASTER GDEM scenes mosaic. The resulting environmental variables made it possible to categorize nine classes of mountain permafrost landscapes. The result obtained was compared with previous permafrost landscape maps, which revealed a significant difference in distribution and spatial structure of intrazonal valleys and mountain tundra landscapes. Analysis of the landscape structure revealed a significant distribution of classes of mountain Larix-sparse forests and tundra. Landscape diversity was described by six longitudinal and latitudinal landscape hypsometric profiles. River valleys allow boreal–taiga landscapes to move up to high-mountainous regions. The features of the landscape structure and diversity of the ridge are noted, which, along with the specific spatial organization of vegetation and relief, can be of key importance for environmental monitoring and the study of regional variability of climatic changes.

For the first time, the geoinformation modelling and machine learning approaches have been used to study the vegetation cover of the mountainous part of North-Eastern Siberia – the Orulgan medium-altitude mountain landscape province. These technologies allowed us to distinguish a number of mapping units that were used for creation and analysis of 1:100 000 scale vegetation map of the interpreted key area. Based on the studies, we decided upon the basic principles, approaches and technologies that would serve as a methodology basis for the further studies of vegetation cover of the large region. Relief, slope aspect, genetic types of sediments, and moisture conditions were selected as supplementary factors to the vegetative indices for differentiation of both plant communities and vegetation map units.

Summary The arbuscular mycorrhizal (AM) fungi are a globally distributed group of soil organisms that play critical roles in ecosystem function. However, the ecological niches of individual AM fungal taxa are poorly understood. We collected > 300 soil samples from natural ecosystems worldwide and modelled the realised niches of AM fungal virtual taxa (VT; approximately species‐level phylogroups). We found that environmental and spatial variables jointly explained VT distribution worldwide, with temperature and pH being the most important abiotic drivers, and spatial effects generally occurring at local to regional scales. While dispersal limitation could explain some variation in VT distribution, VT relative abundance was almost exclusively driven by environmental variables. Several environmental and spatial effects on VT distribution and relative abundance were correlated with phylogeny, indicating that closely related VT exhibit similar niche optima and widths. Major clades within the Glomeraceae exhibited distinct niche optima, Acaulosporaceae generally had niche optima in low pH and low temperature conditions, and Gigasporaceae generally had niche optima in high precipitation conditions. Identification of the realised niche space occupied by individual and phylogenetic groups of soil microbial taxa provides a basis for building detailed hypotheses about how soil communities respond to gradients and manipulation in ecosystems worldwide.

A brief history of development of the Prodromus vegetation of Yakutia is given. The characteristic of classes is given in a table.

Aim Soil pH is considered an important driver of fine-scale plant species richness in terrestrial ecosystems. However, it is unclear to what extent this relationship is influenced by precipitation, which often directly affects both soil pH and species richness. We asked: (1) what is the relationship between fine-scale vascular plant species richness and soil pH in regions with different levels of precipitation and (2) what are the relative effects of soil pH and precipitation on species richness?Location Dry grasslands in eight regions of northern Eurasia.Methods Species richness and soil pH were measured in 1055 10 m x 10 m plots and precipitation values were derived from global datasets. Relationships between variables were explored using general linear models, mixed-effect models and partial regressions. Variation partitioning was used to assess the relative effect of each predictor on species richness.Results In wetter regions, soil pH range was broader, mean species richness was higher and the richness-pH relationship was unimodal. In drier regions, mean soil pH was higher and its range narrower, species richness was on average lower and less variable, and the richness-pH relationship was negative or absent. The richness-pH relationship persisted after controlling for the effect of precipitation, but precipitation, uniquely or together with soil pH, explained more variation in species richness in most regions than did pH alone.Main conclusions The relationship between plant species richness and soil pH in dry grasslands changes from unimodal, through negative, to none with decreasing regional precipitation in Eurasia. However, it seems that the species richness-soil pH relationship in dry grasslands over broad areas is substantially influenced and confounded by precipitation either indirectly, by shortening and shifting the pH gradient, or directly, by decreasing the negative effects of drought stress on richness.

Поступило в редакцию 06.11.2014 Submitted 06.11.2014 Принято к публикации 18.12.2015 Accepted 18.12.2015 Аннотация. Район низовий р. Индигирки отличается довольно высоким ценотическим разнообразием, здесь выявлено 9 ассоциаций, 4 субассоциации и 5 вариантов, относящихся к 5 классам эколого-флористической классификации. Пять ассоциации и 4 субассоциаций описаны впервые. Описаны широко распространенные в Сибирской Арктике моховые (асс. Carici arctisibiricae–Hylocomietum alaskani) и дриадовые (асс. Rhytidio rugosi–Dryadetum punctate) тундры, нивальные мохово-разнотравные луга (асс. Deschampsio–Cerastietum regelii) и криофитные травяные болота (асс. Meesio triquetris–Caricetum stantis). Выделены также новые синтаксоны. Для подзоны типичных тундр описаны влагалищнопушицево-лишайниково-моховые тундры (асс. Tephrosero atropurpureae–Salicetum pulchrae), приуроченные к выположенным частям водоразделов, и злаково-кустарничково-зеленомошные нивальные тундры (асс. Astragalo frigidi–Salicetum reptantis), развитые на прирусловых речных террасах. Тундровые моховые ивняки (асс. Sanionio uncinati–Salicetum hastatae) занимают склоны водоразделов как в подзоне южных тундр, так и подгольцовом горном поясе Кондаковского плоскогорья. Осоково-сфагновые болота (асс. Carici rariflorae–Sphagnetum warnstorfii) являются элементом валиково-полигональных тундрово-болотных комплексов в подзоне южных тундр. Эродированные щебнисто-каменистые склоны р. Индигирки занимают сообщества асс. Potentillo arenosae–Thymetum oxyodonti. Выявлены особенности подзонально-поясной дифференциации синтаксонов в зависимости от соотношения географических групп видов. Разнообразие растительности обусловлено выраженностью здесь наряду с равнинными, также и горных ландшафтов Кондаковского плоскогорья.

Local species richness–productivity (SR–P) relationship is usually reported as unimodal if long productivity gradients are sampled. However, it tends to be monotonically increasing in low-productive environments due to the decreasing part of the SR–P curve being truncated. Previous work indicated that this can hold true for forest herb layers, because of an upper bound on productivity caused mainly by canopy shading. Here, we ask whether the same pattern exists in a region with an upper bound on productivity caused by a harsh climate. We sampled herbaceous vegetation of boreal forests and grasslands in a low-productive region of central Yakutia (NE Siberia) with dry and winter-cool continental climate. We collected data on species composition, herb-layer productivity (aboveground herbaceous biomass), soil chemistry and light availability. We applied regression models to discriminate between monotonically increasing, decreasing and unimodal responses of herb-layer species richness to measured variables and analysed trends in the species-pool size and beta diversity along the productivity gradient. Our expectation of the monotonically increasing SR–P relationship was confirmed for neither forest herb layers nor grasslands. In the forest herb layers, no relationship was detected. In grasslands, the relationship was unimodal with species richness decline starting at much lower productivity levels than in more productive temperate grasslands. Potential causes for this decline are either limitation of local species richness by the species pool, which contains few species adapted to more productive habitats, or competitive exclusion, which can become an important control of species richness under lower levels of productivity than is the case in temperate grasslands.

The systematical and geographical analysis of Central Yakutia flora has been done in the article. 998 spesies with the privilege of Mesophyto-Steppes Asreraceae, Poaceae perennial grasses Golarctic Boreal character been revealed.

Using the Braun-Blanquet approach, five associations of boreal forests were distinguished in central Yakutia, the most continental part of eastern Siberia. Ecological features of the syntaxa were explained with the use of the DCA ordination of 50 relevés. All available data from eastern Siberia were involved in the study for syntaxonomic analysis. Central Yakutian boreal forests were classified into two classes:Rhytidio-Laricetea sibiricae Korotkov etErmakov 1999 — ultracontinental light coniferous hemiboreal forests, andVaccinio-Piceetea Br.-Bl. inBr.-Bl. et al. 1939 — typical coniferous taiga forests of northern Eurasia. A new concept of higher syntaxonomic units of the classVaccinio-Piceetea in eastern Siberia has been developed. Three orders represent the diversity of taiga forests: (1)Cladonio-Vaccinietalia Kielland-Lund 1967 (with alliancesHieracio umbellati-Pinion sylvestris Anenkhonov etChytrý 1998 andSaxifrago bronchialis-Pinion sylvestris all. nov.) — light coniferous boreal forests occurring in dry and moderately dry oligotrophic sites in various climatic sectors of Northern Eurasia; (2)Lathyro humilis-Laricetalia cajanderi ord. nov. (with alliancesAulacomnio acuminati-Laricion cajanderi all. nov. andRhododendro daurici-Laricion gmelinii all. nov.) — zonal boreal forests with xeric elements, which are typical of regions of northern Asia with cold, dry ultracontinental climate; (3)Ledo-Laricetalia cajanderi ord. prov. (with allianceLedo-Laricion cajanderi prov.) — North Eurasian boreal forests occurring in cold sites with excessive soil moisture, sometimes water-logged. Phytogeography and ecology of these orders are discussed in comparison with other regions of northern Asia.