Shrub Thickets Research Articles

HABITATION CONDITIONS OF THE CAVE LION IN THE MIDDLE INDIGIRKA RIVER BASIN, NORTH-EAST SIBERIA, DURING THE MIDDLE AND LATE PLENIGLACIAL: RECONSTRUCTION BASED ON PALYNOLOGICAL DATA

Pollen analyses of the sediment from skulls cavities of two cave lions Panthera spelaea from the middle Indigirka River basin, North-East Siberia, were performed to reconstruct the habitat conditions of the animals and to estimate changes in vegetation and climatic conditions in the region. Composition of the pollen and non-pollen palynomorphs indicates that the predators most likely died on the river floodplain or near the shore of the thermokarst lake, where grass/sedge meadows and shrub thickets, providing rich grazing grounds for large herbivores, existed. Palynological data indicate that both in the early Middle Pleniglacial and in the LGM the regional vegetation included forest, shrub tundra, meadow, mire and steppe communities similar to modern cold steppes in central Yakutia. During early Marine Isotope Stage (MIS) 3, the participation of arboreal vegetation was greater than in the Last Glacial Maximum (LGM) due to higher summer temperatures. In MIS 2, the role of open herbaceous cryoxerotic communities was greater, which is associated with a higher continentality of climate and a decrease in winter temperatures. This reconstruction is consistent with the general sequence of landscape and climatic changes in the Arctic and Subarctic regions of Siberia in the Middle and Late Pleniglacial, based on paleobotanical studies of the locations of mammoth fauna and multidisciplinary studies of the Late Pleniglacial sediments from a broader area.

ОЦЕНКА СОВРЕМЕННОГО СОСТОЯНИЯ РАСТИТЕЛЬНОГО ПОКРОВА Г. ОБЛУЧЬЕ ПО МУЛЬТИСПЕКТРАЛЬНЫМ ДАННЫМ

A sustainable development of regional towns and small settlements demands the urban modern landscape infrastructure study and assessment. For this purpose, geoinformation systems and remote sensing data are widespread used. The aim of the study was to analyze the green spaces in the small town of Obluchye (Jewish Autonomous region) using multispectral data with an assessment of indicators of the town sustainable development. The sources of information were as follows: Sentinel-2A multispectral products, the Rules of land use and development for Obluchye, field research materials, ICARP FEB RAS stock materials, special literature. The identification and analysis of green spaces distribution in Obluchye are based on calculation results of the normalized vegetation index (NDVI). It is stated that the NDVI value of 0.55 or more is the boundary value for the allocation of green spaces in Obluchye; 0.75 or more - for woody vegetation. The NDVI boundary value of 0.55...0.74 is for herbaceous and shrubby vegetation on lawns, unsettled areas, as well as for natural and produced meadows. The NDVI values of 0.75 or more in the image determine the forest vegetation of the Obluchye recreation zone, tree and shrub thickets along riverbeds and floodplain forests, and woodlands in the town built-up zone. The green spaces distribution across the town functional zones is uneven. The high and very high landscaping areas are characteristic of the Obluchye periphery and correspond to the zones of recreational and residential development. In most cases, tree plantations are located in a recreational area, mainly outside the town. However, all urban development zones have high values of landscaping average level (from 71 to 93%). The calculated indicators of sustainable development in Obluchye show, on the one hand, a significant exceeding level of landscaping (53%), as compared to the established norms (at least 40%). On the other hand, the share of green areas of common use in the total area of green spaces in Obluchye is very low – only 1.6%. Thus, there is a need in a qualitative improvement of green infrastructure in the town of Obluchye.

The Holocene evolution of floodplain mire geosystems in the southeastern part of the Meshchera lowlands

The results of paleoecological studies of peat deposits in the area of the southeastern part of the Meshchera lowlands (Mostovoye mire) based on the analyses of peat properties, plant macrofossils, charcoal, pollen and radiocarbon dating are presented. The mire was formed in the oxbow depression on the floodplain of the Goose River around 9480 cal. yr. BP and was eutrophic throughout most of the Holocene. Drastic changes in the dynamics of the mire, namely its transition to the mesotrophic stage, characterized by a decrease in the degree of peat decomposition, occurred about 70 years ago. The results of the pollen analysis show the existence of birch-pine forests in combination with shrub thickets formed by Betula nana in the period 9480-8750 cal. yr. BP. In the subsequent stages, the vegetation cover turned to a combination of broad-leaved, birch-pine forests and riverine forests with alder. Frequent fires, both natural and anthropogenic, have favored the development of birch and pine forests over the last millennium.

Flora synopsis of the “Kamenny lake tract” natural monument (Kostanay region)

The article presents the results of the floristic diversity study of the state natural monument of local significance ‒ “Kamenny lake tract” with a total area of 2.5 hectares. According to natural conditions, this territory is included in the subzone of arid forb-feather grass steppes on low-humus southern chernozems and dark chestnut soils, plowed up to 80%. Under the birch forest soils are dark gray, loamy, and sandy; on slopes they are leached chernozem; near-shore soils are meadow-marsh soils. The studies were carried out in 2019-2022. On the basis of field studies, five main ecotopes were identified: shrub thickets on slopes, birch forest on steep slopes, upland meadows with shrub thickets, meadow-marsh communities on coasts, and meadow-steppe communities. A synopsis containing species’ habitat information within the specially protected natural area was compiled. In the study area, the total list of higher vascular plants includes 177 species from 48 families and 132 genera. The leading families areAsteraceae, Rosaceae, Poaceae, Fabaceae, Lamiaceae, and Caryophyllaceae. The basis of the flora is herbaceous plants, followed by woody, aquatic plants. The steppe ecological-coenotic group is the richest by the volume of species. In the flora of the “Kamenny lake tract” a large proportion of species has significant extent areas: cosmopolitan, holarctic, and palearctic. The holarctic and palearctic types are the largest number of species. The Red Book of Kazakhstan species in the study area areAdonis wolgensis, Stipa pennata, and Tulipa biebersteiniana.

Thresholds and alternative states in a Neotropical dry forest in response to fire severity.

Neotropical xerophytic forest ecosystems evolved with fires that shaped their resilience to disturbance events. However, it is unknown whether forest resilience to fires persists under a new fire regime influenced by anthropogenic disturbance and climate change. We asked whether there was evidence for a fire severity threshold causing an abrupt transition from a forest to an alternative shrub thicket state in the presence of typical postfire management. We studied a heterogeneous wildfire event to assess medium-term effects (11 years) of varying fire severity in a xerophytic Caldén forest in central Argentina. We conducted vegetation surveys in patches that were exposed to low (LFS), medium (MFS), and high (HFS) fire severities but had similar prefire woody canopy cover. Satellite images were used to quantify fire severity using a delta Normalized Burning Ratio (dNBR) and to map prefire canopy cover. Postfire total woody canopy cover was higher in low and medium than high severity patches, but the understory woody component was highest in HFS patches. The density of woody plants was over three times higher under HFS than MFS and LFS due to the contribution of small woody plants to the total density. Unlike LFS and MFS patches, the small plants in HFS patches were persistent, multistem shrubs that resulted from the resprouting of top-killed Prosopis caldenia trees and, more importantly, from young shrubs that probably established after the wildfire. Our results suggest that the Caldén forest is resilient to fires of low to moderate severities but not to high-severity fires. Fire severities with dNBR values > ~600 triggered an abrupt transition to a shrub thicket state. Postfire grazing and controlled-fire treatments likely contributed to shrub dominance after high-severity wildfire. Forest to shrub thicket transitions enable recurring high-severity fire events. We propose that repeated fires combined with grazing can trap the system in a shrub thicket state. Further studies are needed to determine whether the relationships between fire and vegetation structure examined in this case study represent general mechanisms of irreversible state changes across the Caldenal forest region and whether analogous threshold relationships exist in other fire-prone woodland ecosystems.

Post-accident dynamics of flora and vegetation in the Belarusian sector exclusion zone of the Chernobyl nuclear power plant

The issues of vegetation cover dynamics in the Chernobyl accident area considered in the article. The research carried out within the boundaries of the Polessky State Radiation-Ecological Reserve. The objects of research are the flora and vegetation of the region. The research is based on as classical methods for studying flora and vegetation, as modern ones, using a long-term archive of Landsat satellite imagery. The article interprets that the flora and vegetation transformation processes of the Chernobyl exclusion zone are mainly due to natural changes and anthropogenically stimulated processes associated with the economic activity cessation. The authors noted a progressive increase of the vascular plant species number within the Reserve, which explained by the restoration processes beginning of the vegetation cover after the population evacuation and the economic activity complete stopping. The spatial isolation of the Polessky State Radiation-Ecological Reserve territory led to the preservation of flora synanthropization level, similar to the end of the 1980s. Former settlements, wastelands, former arable lands, linear objects (roads) and other former anthropogenic habitats are the retention and penetration centers of synanthropic species within the Reserve. The forested territory increasing is a key moment of the vegetation demutational successions in the Chernobyl exclusion zone. A large increase of derived small-leaved forests participation characterizes the dynamics of the forest vegetation formational structure during the post-accident period. Indigenous coniferous and deciduous fen forests also tend to distribution increase, but their dynamics is not rapid. Forests formation, bushing, waterlogging due to the degradation of drainage systems are the processes of meadow dynamics. Fragments of unchanged meadows preserved only in the Pripyat River floodplain. Restoration of bog-forming processes observed on disturbed peatlands, part of unforested fens transformed into forested fens, sparse forests and shrub thickets in the post-accident period. The processes of forest formation, local swamping prevail on the former agricultural and residential lands.

Slow development of woodland vegetation and bird communities during 33 years of passive rewilding in open farmland.

Passive rewilding is a potential tool for expanding woodland cover and restoring biodiversity by abandoning land management and allowing natural vegetation succession to occur. Land can be abandoned to passive rewilding deliberately or due to socio-economic change. Despite abandonment being a major driver of land use change, few have studied the long-term outcomes for vegetation and biodiversity in Western Europe. Studies are also biased towards sites that are close to seed sources and favourable to woodland colonisation. In this case-study, we reconstruct a time series of passive rewilding over 33 years on 25 ha of former farmland that had been subject to soil tipping, far from woodland seed sources. Natural colonisation by shrubs and trees was surveyed at three points during the time series, using field mapping and lidar. Breeding birds were surveyed at three time points, and compared with surveys from nearby farmland. Results showed that natural colonisation of woody vegetation was slow, with open grassland dominating the old fields for two decades, and small wetlands developing spontaneously. After 33 years, thorny shrub thickets covered 53% of the site and former hedgerows became subsumed or degraded, but trees remained scarce. However, the resulting habitat mosaic of shrubland, grassland and wetland supported a locally distinctive bird community. Farmland bird species declined as passive rewilding progressed, but this was countered by relatively more wetland birds and an increase in woodland birds, particularly songbirds, compared to nearby farmland. Alongside biodiversity benefits, shrubland establishment by passive rewilding could potentially provide ecosystem services via abundant blossom resources for pollinators, and recreation and berry-gathering opportunities for people. Although closed-canopy woodland remained a distant prospect even after 33 years, the habitat mosaic arising from passive rewilding could be considered a valuable outcome, which could contribute to nature recovery and provision of ecosystem services.

DESERT SOLAR POWER INDIA: A SYSTEMATIC STUDY OF POTENTIAL DEVELOPMENT OF SOLAR POWER IN THE INDIAN DESERT

The deserts of Rajasthan have long been known for their spare beauty and their intense sunshine. Now that sun is being turned into a surge of solar power expansion that may one day power not just Rajasthan but a wide swath of India with clean energy. Rajasthan, with its 300 days a year of sunshine and relatively cheap desert land, has set a goal even more ambitious than Indias. In this years state budget, the newly formed state government announced it hoped to install 25,000 megawatts of solar energy in the state within the next five years, and infrastructure to transmit that power to the national grid. Rajasthan is no newcomer to renewable energy. Since the 1990s, the state has been home to a range of wind energy projects, with about 2,800 megawatts of wind capacity now installed, out of an estimated potential capacity of 5,000 megawatts. Altogether wind power in Rajasthan accounts for about 13 percent of Indias wind energy production. But Rajasthans Great Indian Thar Desert, the test site for Indias first underground explosion of a nuclear weapon 15 years ago, may now help make India a solar power as well. The desert set in Rajasthans largest district Jaisalmer, near the border with Pakistan, it is a place of sand dunes and shrub thickets – but also, increasingly, solar installations that could help change the character of Indias energy development. India committed at the U.N. Framework Convention on Climate Change negotiations in Copenhagen in 2009 to reduce its climate-changing emissions, per unit of GDP, by 20 to 25 percent by 2020, compared to 2005 levels. The country is currently the worlds seventh largest emitter of global warming pollution and the fifth biggest producer of emissions from burning fossil fuels. Sixty-eight percent of those emissions from fossil fuel use come from creating energy for the worlds second most populous country, according to Indias energy ministry. Today the country has 2.28 million megawatts of power generating capacity, and about 12.4 percent of that comes from renewable energy. Of the 2,632 megawatts of solar power now installed in India, Rajasthan so far has only 730 megawatts, putting it in second place behind the state of Gujarat, with 916 megawatts, according to Indias Ministry of New and Renewable Energy. But Rajasthan, Indias largest state and 60 percent covered by sunny desert, is now attracting the worlds interest as a solar hotspot. Around 1 lakh (100,000) square kilometers of barren land is available in the northwest arid belt of the state at cheaper rates that could be utilized for large scale solar projects. The government is formulating the policy to harness the enormous solar potential of the region to meet the countrys growing energy requirements. Besides large solar installations, the government is studying the possibility of grid-connected rooftop solar photovoltaic units for households. The Solar Energy Corporation of India estimates that 130 million homes could potentially be equipped with the units, creating 25,000 megawatts of generating capacity. said Alok, Rajasthans Energy Secretary.

Spiders (Arachnida: Araneae) in dry grasslands of South Ukraine: a case study of Yelanetskyi Steppe Natural Reserve

Dry grassland areas of Ukraine are highly fragmented due to human activity. All of them require protection and thorough study of their biota. Arachnological research in the Yelanetskyi Steppe Natural Reserve has been conducted for the first time. An annotated list of spiders includes 113 species in 23 families. Salticidae (20 species, 17.7% of the species list) and Gnaphosidae (18 species, 15.9%) are the most species rich. The studied reserve is the westernmost locality of Ero koreana Paik, 1967 and Zelotes eugeneiKovblyuk, 2009. Richest were the ecotone habitats on the edges of forest plantations and shrub thickets (43–45 species), while the poorest were the most disturbed open grassland habitats like grazed steppe, secondary steppe and meadows (25–26 species). Spider assemblages of the undisturbed forb-fescue-feather grass and petrophytic steppe habitats accounted for 33–37 species. A comparison of the dry grassland spider faunas of 11 protected areas in the steppe and forest-steppe zones of Ukraine showed that the araneofauna of the Yelanetskyi Steppe is most similar to those of both forb-fescue-feather grass steppes of Southeast Ukraine and fescue-feather grass steppes of South Ukraine. Moreover, the spider fauna of the Yelanetskyi Steppe contains the least specific elements. 33% of the species are widespread and only 3.8% are recorded from one or only two close sites. Similarity of the spider faunas depends on the geographical location of the study area and on the types of the grasslands.

Decreased temperature variance associated with biotic composition enhances coastal shrub encroachment

Regime shift from grasslands to shrub-dominated landscapes occur worldwide driven by altered land-use and climate change, affecting landscape function, biodiversity, and productivity. Warming winter temperatures are a main driver of expansion of the native, evergreen shrub, Morella cerifera, in coastal landscapes. Shrub establishment in these habitats alters microclimate, but little is known about seasonal differences and microclimate variance. We assessed influence of shrubs on microclimate variance, community composition, and community physiological functioning across three vegetation zones: grass, transitional, and shrub in a coastal grassland. Using a novel application of a time-series analysis, we interpret microclimatic variance modification and elucidate mechanisms of shrub encroachment at the Virginia Coast Reserve, Long-Term Ecological Research site. As shrub thickets form, diversity is reduced with little grass/forb cover, while transpiration and annual productivity increase. Shrub thickets significantly reduced temperature variance with a positive influence of one day on the next in maximum air, minimum air, and maximum ground temperature. We also show that microclimatic temperature moderation reduces summer extreme temperatures in transition areas, even before coalescence into full thickets. Encroachment of Morella cerifera on the Virginia barrier islands is driven by reduced local exposure to cold temperatures and enhanced by abiotic microclimatic modification and biotic physiological functioning. This shift in plant community composition from grassland to shrub thicket alters the role of barrier islands in productivity and can have impacts on the natural resilience of the islands.

Ecological and physiognomic vegetation types of Zhetysu Alatau mountains

The article presents the studying outcomes from 2014 to 2019 of vegetation cover of Zhetysu Alatau mountains, and also it summarized types of compiled ecological-phytocenotic classification. The main methods of compiling environmental classifications are briefly represented, and the advantages and disadvantages of each approach are described: dominant and determinant. While creating of vegetation classification, the dominant approach to the allocation of taxa is adopted. The taxonomic hierarchy includes units: vegetation types, class formation (ecological-physiognomic type), group association. The vegetation cover of Zhetysu Alatau belons to 6 types of vegetation: forest, shrubby, meadow, swamp, steppe, deserts. Each type includes ecological and physiognomic vegetation categories (20 in total): forests – dark coniferous, small-leaved, floodplain; shrub thickets – petrophytic, halophytic, mesophytic and mesoxerophytic along river valleys, evergreen elfin woods; meadows – high-mountain low-herb alpine, high-mountain mid-herb subalpine, mid-mountain high-herb, steppes, halophytic, floodplain (swamp, typical); swamp grass; steppes – wormwood-grasses (deserts), grasses (true), rich forb-grass (meadow), high-mountain; deserts – halophytic semi-shrubs, psammophytic shrubs. Phytocenotic characteristics of species diversity for each type of vegetation and its association with high-altitude zones are given. Key words: Zhetysu Alatau mountains, vegetation classification, ecological physiognomic approach, plant communities, phytocoenotic characteristics.

Patterns of mercury accumulation in the organs of bank vole Myodes glareolus (Rodentia, Cricetidae)

Mercury (Hg) and its compounds are among the most hazardous environmental pollutants with a high cumulative potential and they can have toxic effects on human and animal health even in low concentrations. Due to the increasing rate of human economic activity and the increase in the amount of Hg in the total cycling of matter, the study of its distribution, transformation, redistribution and accumulation in the abiotic and biotic components of various ecosystems remains important up to the present time. We assessed the content of metal in organs and tissues of the bank vole Myodes (Clethrionomys) glareolus Schreber, 1780 (Rodentia, Cricetidae), a widespread small rodent, caught in different biotopes of forest-steppe and steppe zones of Voronezh region. Measurements of Hg in samples were carried out with a mercury analyzer RA-915+ with the accessory PYRO (Lumex) using the atomic absorption method of cold steam without preliminary sample preparation (the lower limit of mercury detection in samples was 0.001 mg/kg). The sample size was 344 specimens. Mean Hg concentrations ranged from values below the analytical determination threshold to 0.887 mg/kg dry weight in the kidneys, 0.411 in the liver, 0.031 in the muscle tissue, and 0.040 in the brain. A positive correlation was found between the metal content in all possible pairs of organs (except for the “muscle – brain” pair) and a weak negative correlation was found between the Hg level and the mass of the animals. Hg concentrations in the studied organs did not differ between males and females. The metal content in the liver and kidneys of voles from the forest-steppe zone was significantly higher than in those from the steppe zone. Among all studied biotopes (meadow, pine and mixed forest, shrub thickets), the lowest concentrations were observed in animals living in pine forests, while the highest one – in more humidified bush thickets. During the vegetation season, there was a decrease in the average values of animal body mass in the samples and an increase in the content of Hg in the liver and kidneys. The results of the study are relevant in the assessment of atmospheric mercury pollution of terrestrial ecosystems using small mammals, such as Myodes glareolus, as a model object.

Recruitment dynamics and population structure of willows in tundra disturbed by retrogressive thaw slump thermokarst on Alaska’s North slope

Retrogressive thaw slumps (RTS) are large (> 1 ha) depressions of exposed mineral soil on hillslopes caused by the thaw and displacement of ice-rich permafrost soils in high-latitude regions; since the 1980s the number of RTS observed on Alaska’s North Slope has increased by two-thirds. Some RTS in the Toolik Lake area are filled with tall (≥ 0.5 m) willow thickets, likely within decades after disturbance. Tall shrub thickets are different in structure and function from mixed dwarf tundra communities and may have different long-term impacts on ecosystems and wildlife. Currently it is unknown to what degree seedlings versus clonal recruitment contribute to shrub thickets. We assessed size and distribution of clones (modular stems of individuals) using eight microsatellite (SSR) markers to genotype leaf tissue of 223 willow ramets (stems) at two sites: an RTS aged 11–30 years since disturbance, and nearby undisturbed moist acidic tussock (MAT) tundra. Genotypes of known clones from excavated ramets were used to determine the mutation rate of clones. Spatial arrangement of ramets within clones was assessed in 18 × 18 m sampling grids nested at 2 m (“far clones”), 1 m (intermediate), and 0.25 m (“near clones”) between ramets. We identified 121 genotypes including 10 clonal genotypes in the RTS, and 63 genotypes including 11 clonal genotypes in the undisturbed MAT. Percent distinguishable was greater than 76% at both sites. Mean spatial distance between clonal ramets was not different at either site but among far clones, ramets were separated 7–16 m downslope in the RTS. Salix pulchra was the dominant willow at both sites; a third of willow genotypes in the RTS were identified as S. glauca, a disturbance colonizer. Rarer and hybrid species comprised 4–20% of all genotypes but were more abundant in the RTS. At both sites, within-species expected heterozygosity (HT) ranged from 0.49 - 0.85. Our results suggest: 1) sexual recruitment and low clonal expansion likely explain genetic diversity of willows in disturbed and late-successional sites; and 2) downslope separation of far clones in the RTS suggests disturbance effects; and 3) species richness was higher in the disturbed site.

Extrazonal steppes of forest belt on eastern macroslope of the Urals

Extrazonal steppes of forest belt on eastern macroslope of the Middle and South Urals have small coenotic diversity. The most part of studied communities are petrophytic steppes on outcrops, which determine regional features of plant cover and provide habitats to rare, endemic and relict plant species. Petrophytic steppes correspond to order Helictotricho- Stipetalia, meadow steppes and xeric meadows, shrub thickets correspond to order Brachypodietalia pinnati (class Festuco-Brometea).

Short-Term Vegetation Responses to Invasive Shrub Control Techniques for Amur Honeysuckle (Lonicera maackii [Rupr.] Herder)

Invasive shrubs in forest understories threaten biodiversity and forest regeneration in the eastern United States. Controlling these extensive monotypic shrub thickets is a protracted process that slows the restoration of degraded forest land. Invasive shrub removal can be accelerated by using forestry mulching heads, but evidence from the western United States indicates that mulching heads can promote exotic species establishment and mulch deposition can reduce native plant species abundance. We compared the effectiveness of the mulching head and the “cut-stump” method for controlling the invasive shrub Amur honeysuckle (Lonicera maackii), as well as their impacts on native plant community recovery, in mixed-hardwood forests of Indiana. After two growing seasons, mulching head treatment resulted in greater L. maackii regrowth and regeneration. The recovery of native plant abundance and diversity following shrub removal did not differ between the two methods. However, mulch deposition was associated with increased abundance of garlic mustard (Alliaria petiolata), an invasive forb. Increasing mulching head treatment depth reduced L. maackii regrowth, but additional study is needed to determine how it affects plant community responses. The mulching head is a promising technique for invasive shrub control and investigating tradeoffs between reducing landscape-scale propagule pressure and increased local establishment will further inform its utility.

Influence of invasive shrubs and deer browsing on regeneration in temperate deciduous forests

While both chronic white-tailed deer (Odocoileus virginianus Zimmermann) overbrowsing and invasive shrubs have been linked to native regeneration failure in temperate hardwood forests, little is known of their relative importance and possible synergistic effects. Therefore, we established three study areas in Connecticut to examine the interaction of three levels of invasive shrub control and absence or presence of deer herbivory on forest regeneration over 9 years. Five observations suggest that obtaining forest regeneration requires a comprehensive management strategy. First, competitive interference by invasive shrubs in intact thickets continued to impede forest regeneration, especially taller seedlings, after deer were excluded. Second, density of small seedlings increased following removal of the competitive interference by invasive shrubs. Third, deer browsing depressed growth of small seedlings into taller height classes. Fourth, preferential browsing reduced species richness, especially in taller seedling classes, by favoring growth of low palatability species such as beech. Lastly, if a disturbance (e.g., cutting) does not kill the root system of the invasive shrubs, the window of forest regeneration recruitment may be narrow because invasive shrubs can quickly recover. In stands with both established shrub thickets and high deer densities, invasive shrub control and multiyear reduction of deer densities are both recommended to obtain adequate forest regeneration.

Biodiversity of the vascular plants in the young fluvioglacial landscapes in the Severo-Chuiskiy centre of present-day glaciation (the Central Altai)

This article reports the species richness of vascular plants in the young fluvioglacial landscapes in the Severo-Chuiskiy centre of present-day glaciation using the example of the fluvioglacial deposits of the mountain-glacial basin Aktru. These landscapes are four well distinguished classes of habitats: open pebble fields with minimal vegetation, young larch forests on elevated parts of the relief, shrub thickets on the banks of the Aktru river, and sites with ground-frazil near the valley slopes. There are 132 species of vascular plants in the young fluvioglacial landscapes. These include 36 families and 77 genera. There are 3 species of pteridophytes (only Equisetum), 4 species of gymnosperms, and 125 species of angiosperms. The highest species diversity was recorded for Asteraceae, Poaceae and Salicaceae families, and for Salix, Poa, and Carex genera. The highest species richness – 100 species – were recorded for open pebble fields. There were 76 species in the young larch forests, and 58 species occurred in shrub thickets. The lowest richness is characterised for the sites with ground frazil, where 31 species were recorded.

Expanded Range Limits of Boreal Birds in the Torngat Mountains of Northern Labrador

The Torngat Mountains lie at the southeastern limit of the Canadian Arctic in northern Labrador, and bird distributions in the region are poorly understood. I visited the Torngat Mountains every summer from 2008 to 2016 and recorded all birds observed. Several boreal bird species were widespread and breeding in the region, representing expansion of known ranges by 100–350 km north along the Labrador coast and 40–90 km east from Ungava Bay. Shrub thickets have expanded dramatically in the Torngat Mountains since the 1980s; thus, these observations may reflect range expansion by boreal birds in response to increased habitat availability.

Vegetation Succession and Environmental Conditions following Catastrophic Lake Drainage in Old Crow Flats, Yukon

Increases in the frequency and magnitude of disturbances associated with the thawing of ice-rich permafrost highlight the need to understand long-term vegetation succession in permafrost environments. This study uses field sampling and remote sensing to explore vegetation development and soil conditions following catastrophic lake drainage in Old Crow Flats (OCF). The data presented show that vegetation on drained lake basins in OCF is characterized by two distinct assemblages: tall willow stands and sedge swards. Field sampling indicates that these alternative successional trajectories result from variation in soil moisture following drainage. Increased willow mortality on older drained basins suggests that intraspecific competition drives self-thinning in shrub thickets. This finding, combined with data from paleoecological studies and contemporary vegetation in OCF, suggests that willow stands on drained lake basins are seral communities. These results also indicate that the increase in number of catastrophic drainages that occurred between 1972 and 2010 will alter regional vegetation in ways that affect wildlife habitat, permafrost conditions, and local hydrology.

Immediate effects of microclimate modification enhance native shrub encroachment

AbstractShrubs have become more dense and expanded beyond their range all over the world for a variety of reasons including increased temperatures, overgrazing, and alteration of historical fire regime. Native shrubs have been encroaching on Virginia barrier island grasslands for over half a century for unknown reasons. Species composition, soil nutrients, leaf area index (LAI), and ground and air temperature were recorded across the shrub to grass transition and at free‐standing shrubs in a coastal grassland in order to determine the effect of shrub encroachment on plant community and microclimate. Species richness was significantly lower inside shrub thickets. Soil water content, organic matter, nitrogen (N), carbon (C), and LAI were higher in shrub thickets and free‐standing shrubs compared to grasslands. Summer and fall maximum temperatures were lower and more moderate where shrubs were present. Fall and winter minimum temperatures were highest inside shrub thickets. Native shrubs impact microclimate and species composition immediately upon encroachment. These shrubs lower overall species composition, increase soil nutrients and moisture, moderate summer temperature, and increase winter temperature, which has consequences on a larger scale. As barrier islands are critical for protecting marsh and mainland habitats, understanding this mechanism for shrub expansion is important to predict future encroachment of shrubs and displacement of grassland habitat.