Geographical Distribution Of Species Research Articles

A PCR-RFLP Analysis for the Diagnosis of DAS and T-2 Genotypes in Fusarium goolgardi

Fusarium pathogens and their mycotoxins are considered as the main threats to cereal production and food safety worldwide. However, due to the constant discovery of new Fusarium species especially along with mycotoxin production profile differentiation in certain species, efforts on their species composition, geographical distribution, and chemotype proportion are urgently required. In the Fusarium goolgardi species, two distinct trichothecene (TB) genotype populations have recently been identified. Previous studies have shown that the structural variance of TBs biosynthesized by the two genotypes is attributed to the Tri1 gene. Polymorphisms of Tri1 gene from type A TB-producers were investigated in different Fusarium species in the current study. According to these DNA sequence variations identified in Tri1 gene sequences, a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based diagnostic approach for the differentiation of T-2 and 4,15-diacetoxyscirpenol (DAS) genotypes in F. goolgardi was successfully developed. The PCR-RFLP assay will facilitate the studies on geographic distribution, frequency and other aspects of the two genotypes within F. goolgardi species.

Inferring the tree regeneration niche from inventory data using a dynamic forest model

Abstract. The regeneration niche of trees is governed by many processes and factors that are challenging to determine. Besides a species's geographic distribution, which determines if seeds are available, a myriad of local processes in forest ecosystems (e.g., competition and pathogens) exert influences on tree regeneration. Consequently, the representation of tree regeneration in dynamic forest models is a notoriously complicated process which often involves many subprocesses that are often data deficient. The ForClim forest gap model solved this problem by linking species traits to regeneration properties. However, this regeneration module was never validated with large-scale data. Here, we compare this trait-based approach with an inverse calibration approach where we estimate regeneration parameters directly from a large dataset of unmanaged European forests. The inverse calibration was done using Bayesian inference, estimating shade and drought tolerance as well as the temperature requirements for 11 common tree species along with the intensity of regeneration (i.e., the maximum regeneration rate). We find that the parameters determining the species' light niche (i.e., light requirements) are similar for the trait-based and calibrated values for both model variants, but only a more complex model variant that included competition between recruits leads to plausible estimates of the drought niche. The trait-derived temperature niche did not match to the estimates from either model variant using inverse calibration. The parameter estimates differed between the complex and the simple model, with the estimates for the complex model being closer to the trait-based parameters. In both model variants, the calibration strongly changed the parameters that determine regeneration intensity compared to the default. We conclude that the regeneration niche of trees can be recovered from a large forestry dataset in terms of the stand-level parameters light availability and regeneration intensity, while abiotic drivers (temperature and drought) are more elusive. The higher performance (better fit to hold out) of the inversely calibrated models underpins the importance of informing dynamic models by real-world observations. Future research should focus on even greater environmental coverage of observations of demographic processes in unmanaged forests to verify our findings at species range limits under extreme climatic conditions.

Rethinking ecological niches and geographic distributions in face of pervasive human influence in the Anthropocene.

Species are distributed in predictable ways in geographic spaces. The three principal factors that determine geographic distributions of species are biotic interactions (B), abiotic conditions (A), and dispersal ability or mobility (M). A species is expected to be present in areas that are accessible to it and that contain suitable sets of abiotic and biotic conditions for it to persist. A species' probability of presence can be quantified as a combination of responses to B, A, and M via ecological niche modeling (ENM; also frequently referred to as species distribution modeling or SDM). This analytical approach has been used broadly in ecology and biogeography, as well as in conservation planning and decision-making, but commonly in the context of 'natural' settings. However, it is increasingly recognized that human impacts, including changes in climate, land cover, and ecosystem function, greatly influence species' geographic ranges. In this light, historical distinctions between natural and anthropogenic factors have become blurred, and a coupled human-natural landscape is recognized as the new norm. Therefore, B, A, and M (BAM) factors need to be reconsidered to understand and quantify species' distributions in a world with a pervasive signature of human impacts. Here, we present a framework, termed human-influenced BAM (Hi-BAM, for distributional ecology that (i) conceptualizes human impacts in the form of six drivers, and (ii) synthesizes previous studies to show how each driver modifies the natural BAM and species' distributions. Given the importance and prevalence of human impacts on species distributions globally, we also discuss implications of this framework for ENM/SDM methods, and explore strategies by which to incorporate increasing human impacts in the methodology. Human impacts are redefining biogeographic patterns; as such, future studies should incorporate signals of human impacts integrally in modeling and forecasting species' distributions.

Making better use of tracking data can reveal the spatiotemporal and intraspecific variability of species distributions

Understanding geographic ranges and species distributions is crucial for effective conservation, especially in the light of climate and land use change. However, the spatial, temporal and intraspecific resolution of digital accessible information on species distributions is often limited. Here, we suggest to make better use of high‐resolution tracking data to address existing limitations of occurrence records such as spatial biases (e.g. lack of observations in parts of the geographic range), temporal biases (e.g. lack of observations during a certain period of the year), and insufficient information on intraspecific variability (e.g. lack of population‐ or individual‐level variation). Addressing these gaps can improve our knowledge on geographic ranges, intra‐annual changes in species distributions, and population‐level differences in habitat and space use. We demonstrate this with tracking data and species distribution models (SDMs) of the barnacle goose, a migratory bird species wintering in western Europe and breeding in the Arctic. Our analyses show that tracking data can 1) supplement occurrence records from the Global Biodiversity Information Facility (GBIF) in remote areas such as the European and Russian Arctic, 2) improve information on the temporal use of wintering, staging and breeding areas of migratory species and 3) be used to reveal distribution patterns at the population level. We recommend a broader use of tracking data to address the Wallacean shortfall (i.e. the incomplete knowledge on the geographic distribution of species) and to improve forecasts of biodiversity responses to climate and land use change (e.g. species vulnerability assessments). To avoid common pitfalls, we provide six recommendations for consideration during the research cycle when using tracking data in species distribution modelling, including steps to assess biases and integrate information on intraspecific variability in modelling approaches.

Spacial distribution and suitability for Panonychus ulmi (Tetranychidae) in Brazil

Predictive studies project the geographic distribution of species and can be used to infer climatic niches. However, only a few studies have been conducted on mites. This approach helps map areas with potential for the occurrence of endemic, threatened, or potentially invasive species. Panonychus ulmi (Tetranychidae) is of global economic importance, commonly associated with apple orchards and grapevines. Potential distribution modeling is used to predict areas with environmental suitability for the distribution of a species and/or group. Considering that predictive models on national or regional scales present better data reliability, the present study aimed to analyze the distribution of P. ulmi in Brazil through bioclimatic inferences. The presence of species, bioclimatic variables, and MaxEnt algorithm were used to define a predictive model. The median performance rate of the model was 0.992, indicating its robustness. The variable that made the greatest contribution to the model was the average temperature of the coldest quarter (Bio11). The predictive model of the ecological niche indicated that the southern region of Brazil is environmentally favorable for the adaptation of this mite. The data obtained helped us understand the geographical distribution of P. ulmi in Brazil, and climatically suitable areas for its occurrence were inferred. We believe that this tool can offer indirect assistance to the agricultural sector, especially the producers of apples and grapes in Brazil regarding the presence of P. ulmi.

Assessing genetic diversity in critically endangered Chieniodendron hainanense populations within fragmented habitats in Hainan

Habitat fragmentation has led to a reduction in the geographic distribution of species, making small populations vulnerable to extinction due to environmental, demographic, and genetic factors. The wild plant Chieniodendron hainanense, a species with extremely small populations, is currently facing endangerment and thus requires urgent conservation efforts. Understanding its genetic diversity is essential for uncovering the underlying mechanisms of its vulnerability and for developing effective conservation strategies. In our study, we analyzed 35 specimens from six different populations of C. hainanense using genotyping-by-sequencing (GBS) and single nucleotide polymorphism (SNP) methodologies. Our findings indicate that C. hainanense has limited genetic diversity. The observed heterozygosity across the populations ranged from 10.79 to 14.55%, with an average of 13.15%. We categorized the six populations of C. hainanense into two distinct groups: (1) Diaoluoshan and Baishaling, and (2) Wuzhishan, Huishan, Bawangling, and Jianfengling. The genetic differentiation among these populations was found to be relatively weak. The observed loss of diversity is likely a result of the effects of natural selection.

Predicting future climate change impacts on the potential distribution of the black howler monkey (Alouatta pigra): an endangered arboreal primate.

Climate change is one of the main factors affecting biodiversity worldwide at an alarming rate. In addition to increases in global extreme weather events, melting of polar ice caps, and subsequent sea level rise, climate change might shift the geographic distribution of species. In recent years, interest in understanding the effects of climate change on species distribution has increased, including species which depend greatly on forest cover for survival, such as strictly arboreal primates. Here, we generate a series of species distribution models (SDMs) to evaluate future projections under different climate change scenarios on the distribution of the black howler monkey (Alouatta pigra), an endemic endangered primate species. Using SDMs, we assessed current and future projections of their potential distribution for three Social Economic Paths (SSPs) for the years 2030, 2050, 2070, and 2090. Specifically, we found that precipitation seasonality (BIO15, 30.8%), isothermality (BIO3, 25.4%), and mean diurnal range (BIO2, 19.7.%) are the main factors affecting A. pigra distribution. The future climate change models suggested a decrease in the potential distribution of A. pigra by projected scenarios (from - 1.23 to - 12.66%). The highly suitable area was the most affected above all in the more pessimist scenario most likely related to habitat fragmentation. Our study provides new insights into the potential future distribution and suitable habitats of Alouatta pigra. Such information could be used by local communities, governments, and non-governmental organizations for conservation planning of this primate species.

Species richness, geographic distribution and endemism of Pinguicula (Lentibulariaceae) in the Mexican Transition Zone

The genus Pinguicula (Lentibulariaceae) is composed of 115 species of carnivorous plants and Mexico is a center of diversification. The Mexican Transition Zone (MTZ) is the boundary between the Nearctic and Neotropical regions. It includes the main mountain ranges of Mexico, which extend south to northeastern Nicaragua. Its geological history, physiographic diversity and climatic complexity would have provided the environment to support a rich flora as well as angiosperm endemism. It was expected that the distribution of Pinguicula would have the same pattern. To test this hypothesis, a database was constructed based on the review of herbaria specimens, digital herbaria, bibliography, and databases. Species richness distribution and endemism were evaluated by country, biome, biogeographic province, elevation gradient, and three grid-cells sizes. The species richness of Pinguicula was centered in Mexico in an elevation gradient extending from 1,501–2,000 m. Also, species richness was greatest in the Tropical & Subtropical Coniferous Forest biome. However, considering biogeographic criteria, the Sierra Madre Oriental (SMOr) was the richest province. This was also supported by the distribution of the cells with the highest species richness and endemism. The results showed that the pattern of species richness and endemism of Pinguicula was concentrated along the MTZ, particularly in the SMOr.

Responses of Three Pedicularis Species to Geological and Climatic Changes in the Qinling Mountains and Adjacent Areas in East Asia.

The Qinling Mountains in East Asia serve as the geographical boundary between the north and south of China and are also indicative of climatic differences, resulting in rich ecological and species diversity. However, few studies have focused on the responses of plants to geological and climatic changes in the Qinling Mountains and adjacent regions. Therefore, we investigated the evolutionary origins and phylogenetic relationships of three Pedicularis species in there to provide molecular evidence for the origin and evolution of plant species. Ecological niche modeling was used to predict the geographic distributions of three Pedicularis species during the last interglacial period, the last glacial maximum period, and current and future periods, respectively. Furthermore, the distribution patterns of climate fluctuations and the niche dynamics framework were used to assess the equivalence or difference of niches among three Pedicularis species. The results revealed that the divergence of three Pedicularis species took place in the Miocene and Holocene periods, which was significantly associated with the large-scale uplifts of the Qinling Mountains and adjacent regions. In addition, the geographic distributions of three Pedicularis species have undergone a northward migration from the past to the future. The most important environmental variables affecting the geographic distributions of species were the mean diurnal range and annual mean temperature range. The niche divergence analysis suggested that the three Pedicularis species have similar ecological niches. Among them, P. giraldiana showed the highest niche breadth, covering nearly all of the climatic niche spaces of P. dissecta and P. bicolor. In summary, this study provides novel insights into the divergence and origins of three Pedicularis species and their responses to climate and geological changes in the Qinling Mountains and adjacent regions. The findings have also provided new perspectives for the conservation and management of Pedicularis species.

The Dragonflies and Damselflies (Insecta: Odonata) of Canada: species list, geographical distribution, status, and conservation ranks.

As of August 2023, 220 species in 57 genera and 10 families of damselflies and dragonflies (Insecta: Odonata) are recorded for Canada. Since the publication of the first edition in 2005, 14 species have been added to the list; one,Neurocordulia obsoleta (Say) has been removed because of a misidentification and another, Sympetrum occidentale, has been to synonymy. Conservation ranks are given for species in all 13 provinces and territories. English and French names for all listed species are included. Literature sources are discussed and presented, as is information on species status and the addition and exclusion of species. Sections on taxonomy and variation, subspecies, presumed hybrids, the introduction of exotic species, notable range extensions and observations, and conservation and protection are also provided.

Investigating odonates' response to climate change in Great Britain: A tale of two strategies

AbstractAimSpecies are largely thought to maintain broadly static niches over time, an assumption underpinning much theoretical ecology including the implementation of ecological models to project species' current and future distributions. Here, we assess niche conservatism in odonates in Great Britain over the past six decades by simultaneously quantifying changes in species geographic distribution and evaluating temporal trends in species realised climatic niche.LocationGreat Britain.MethodsDistributional changes were assessed by calculating changes in species distribution centres and deriving occupancy trends. Changes in climatic niches were assessed using a principal component analysis to quantify niche overlap, using information on both climate averages and extremes.ResultsWe show that dragonflies and damselflies displayed distinct responses to changing climatic conditions. Dragonflies shifting to higher latitudes maintained, on average, greater consistency in their climatic niches, providing evidence for climate tracking. Greater climate niche flexibility and increased occupancy over time, on the other hand, were more common in damselflies.Main ConclusionsWe unveil evidence for climatic niche divergence in damselflies on a national scale, casting doubt on the relevance of species distribution models for predicting the impacts of climate change on this, and potentially other, groups of species. More broadly, our results call for more multi‐species temporal comparisons of spatial distributions and climate niches during recent periods of changes in climatic conditions to improve our ability to contrast species' vulnerability risk to the ongoing climate crisis.

Metabolic responses to cold and warm extremes in the ocean.

Temperature influences the geographical distribution of species, but its mechanisms are much debated. A new study in PLOS Biology suggests that metabolic constrains can arise in both warm and cold waters at the geographical range limits of marine species.

Wide Distribution of Teratosphaeria epicoccoides and T. destructans Associated with Diseased Eucalyptus Leaves in Plantations in Southern China.

Species of Mycosphaerellaceae and Teratosphaeriaceae represent over 40% of the fungi identified on eucalypt leaves worldwide. These include some important pathogens that mainly cause leaf blight and spot, and result in increasingly negative impacts on global commercial eucalypt industries. Eucalyptus plantations are commonly cultivated in southern China for solid wood and pulp products. However, the species diversity and geographic distribution of Mycosphaerellaceae and Teratosphaeriaceae, associated with diseased plantation Eucalyptus leaves in China, have not been clarified. In this study, we conducted the first systematic surveys and sample collections of Mycosphaerellaceae- and Teratosphaeriaceae-like fungi from diseased plantation Eucalyptus leaves in southern China. In total, 558 isolates were obtained from 59 sampled sites in five provinces. One isolate was isolated from each tree. According to the disease symptoms, conidia morphological characteristics, and DNA sequence comparisons of ITS, tef1 and tub2 gene regions. The 558 isolates were identified as Teratosphaeria epicoccoides (312 isolates; 55.9%) and T. destructans (246 isolates, 44.1%). Both species were widely distributed in the sampled regions in southern China. The genotypes of T. epicoccoides and T. destructans were determined based on ITS, tef1, and tub2 sequences. The results showed that multiple genotypes of each species of T. epicoccoides and T. destructans exist in China. Additionally, isolates with multiple genotypes were obtained in all five sampled provinces. These results suggest that both T. epicoccoides and T. destructans are not clonal. This study proved that both T. epicoccoides and T. destructans are dominant species and widely distributed on diseased Eucalyptus leaves in southern China. The wide geographic distribution and potential high genetic diversity pose challenges for the disease management of Teratosphaeria leaf blight and leaf spot in China.

Trematode species diversity in the faucet snail, Bithynia tentaculata at the western edge of its native distribution, in Ireland.

Trematodes and their snail hosts have developed intimate parasite-host associations, with snails supporting a diverse and often species-specific trematode fauna. In the faucet snail, Bithynia tentaculata (Caenogastropoda, Littorinimorpha), a unique trematode fauna has been recorded recently. However, knowledge of the exact species identity, phylogenetic relationships, and geographical distribution remains limited as many of the species belong to groups with unclear or controversial taxonomical assignment. To contribute to our knowledge of the trematodes, we investigated the trematode fauna of B. tentaculata by examining a total of 556 snails from lakes in County Galway, Ireland. Using an integrative taxonomic approach including DNA sequence data analyses (28S rRNA gene, ITS1-5.8S-ITS2, ITS2, cox1, nad1) and morphological tools (taxonomical drawings and measurements), we identified nine trematode species of seven families, with seven species occurring as cercariae (Cyathocotyle prussica, Lecithodendrium linstowi, Lecithodendrium sp., Asymphylodora progenetica, Sphaerostoma bramae, Metorchis xanthosomus, and Notocotylus sp.) and three species occurring as metacercariae (A. progenetica, Parasymphylodora parasquamosa, and Sphaeridiotrema sp.). Except for S. bramae, all are new species records for Ireland and provide the most western distribution of these trematodes in Europe. The trematode species recorded are known to use a wide range of definitive hosts and have a wide geographical distribution; among them are species members of genera that are zoonotic (Metorchis) and pathogenic to wildlife (Cyathocotyle, Sphaeridiotrema, and Notocotylus). There remains an ongoing need for precise identification of the trematode species to ensure that wider ecological contexts are correctly understood and biodiversity and disease threats can be accurately evaluated.

Species diversity and geographical distribution of marine benthic shell-bearing mollusks around Donghai Island and Naozhou Island, Guangdong Province

Species diversity and geographical distribution of marine benthic shell-bearing mollusks around Donghai Island and Naozhou Island, Guangdong Province

Taxonomic diversity and structure of phytoplankton of the Polui River (tributary of the Ob River)

The study of the Polui River algoflora are resulted. A total of 249 taxa of species and subspecies ranks from 86 genera, 52 families and 8 divisions were identified: Cyanoprokariota, Chrysophyta, Bacillariophyta, Xanthophyta, Cryptophyta, Dinophyta, Euglenophyta, Chlorophyta. For the first time, a systematic list of algae is given, indicating the habitat, saprobicity and geographical distribution of species. The most diverse in the number of families, genera and species are the divisions Chlorophyta (41 % of the total number of taxa) and Bacillariophyta (34 %), as well as Cyanoprokariota (10 %) and Euglenophyta (9 %). Other divisions are not numerous in composition (6 %). Ten genera are leading, and 4 of them are from the Chlorophyta and Bacillariophyta divisions, 2 genera are from the Euglenophyta. Planktonic species with the presence of benthic forms, beta-mesosaprobes and cosmopolitan species predominate. Discovered cryptomonads in the modern period indicate eutrophication.

Simulation of mangrove suitable habitat in the Guangdong-Hong Kong-Macao Area under the background of climate change

Climate change has resulted in great influence on the geographical distribution of species. Mangrove forests are one of the most precious ecosystems on the planet, yet they are being threatened by the habitat destruction and degradation under the situation of global warming. Seeking suitable areas for planting mangroves to tackle climate change has been gradually popular in ecological restoration. In this study, we applied the Maximum Entropy algorithm to assess the contribution of environmental factors on mangrove distribution, simulated mangrove suitable habitat for present and future (scenario of SSP245-2070s), and used kernel density analysis for identifying priority of mangrove reserve construction. Results indicate that mean diurnal range and elevation made the highest contribution on mangrove distribution. At present, the mangrove habitat suitability along the western coast of the Guangdong-Hong Kong-Macao Area (GHMA) was the highest while that along the eastern coast was the lowest. By 2070s, mangrove suitable areas would show a decreasing trend under SSP245 scenario. High suitable areas (HSAs) would change fastest and shift to northeast in the same direction as dominant environmental factors. For further mangrove restoration, it is advisable to select sites with high suitability density in the future but low reclamation density at present as prior mangrove reserves, and these sites distribute along the northeastern and northwestern coast of Zhanjiang, Yangjiang and Jiangmen, the Pearl River Estuary and Honghai Bay of Shanwei. Meanwhile, regions with lower suitability density but higher reclamation density could be listed as secondary mangrove reserves.

Predicting the response of three common subtropical tree species in China to climate change

IntroductionClimate is crucial factor influencing species distribution, and with global climate change, the potential geographic distribution of species will also alter. In this study, three subtropical tree species (Cunninghamia lanceolata, Pinus taiwanensis, and Quercus glauca) of great ecological values were selected as research objects.MethodsWe applied a maximum entropy (MaxEnt) to predict their potential distributions under different climate scenarios in both present and future conditions based on 37 environmental factors. Jackknife test was used in key factors affecting species distribution. In addition, we explored the key environmental variables that affect their distributions and revealed the evolutionary patterns and migration trends of these tree species under future climate.ResultsThe main findings are as follows: (1) Winter temperature, winter precipitation, and annual temperature range are identified as the key environmental variables affecting the potential geographic distribution of the three tree species; moreover, precipitation-related factors have a greater impact than temperature-related factors; (2) Currently suitable habitats for these three tree species are primarily located in subtropical China with decreasing suitability from south to north; (3) Under future climate conditions, the area of potentially suitable habitat for C. lanceolata continues to expand, while P. taiwanensis and Q. glauca tend to experience a reduction due to increasing greenhouse gas emissions over time; and (4) The centroid of suitable habitat for C. lanceolata shifts northward under future climate change, while the centroid of P. taiwanensis and Q. glauca move southward along with shrinking suitable habitat area.DiscussionOur predictions highlight a high risk of habitat loss of Q. glauca under climate change, recommending management and conservation references for these three commonly used afforestation species under current and future climate change scenarios in China.

Effects of different diets on thermal tolerance in the silkworm, Bombyx mori

AbstractThe survival of species is negatively impacted by the increased frequency and intensity of high‐temperature episodes caused by increased global warming. Thermal tolerance can influence population size and the geographic distribution of species, which translates into species‐wide responses to climate and affects interactions between communities of species. The silkworm, Bombyx mori (L.) (Lepidoptera: Bombycidae), is an ectotherm and an internationally recognized model insect for studying sensitivity to the environment. In the present study, we investigated the effects of different diets on the thermal tolerance of silkworm. As such, it was identified that silkworms reared on an artificial diet in instars I–III and mulberry leaves in instar IV (referred as the AM group) exhibited faster weight gain and higher antioxidant enzyme activity at 35 °C, whereas silkworms reared only on mulberry leaves (referred as the ML group) exhibited upregulated transcript levels of key genes regulating antioxidant enzyme signaling pathways including Akt, CncC, and keap1, significantly increased reactive oxygen species (ROS) levels, and severely impaired midgut activity at 35 °C. Thus, the AM group presented stronger thermal tolerance. These findings suggest that diet can affect the thermal tolerance of silkworm. This research improved our understanding of the molecular, biochemical, and physiological changes caused by thermal stress and laid the groundwork for future research regarding the mechanism underlying thermal tolerance. Furthermore, this study provides an important reference for the conservation of biodiversity in the context of global warming.

CLASSIFICATION OF DWARF PINE COMMUNITIES IN THE NORTH OF THE KORYAK DISTRICT (KAMCHATKA TERRITORY)

A detailed geobotanical characteristic of Siberian dwarf-pine (Pinus pumila (Pall.) Regel) communities of the north of the Koryak District is presented. The vegetation classification based on 83 relevés has been elaborated using main principles and classification methods of Russian dominant-determinant approach. As the result 10 associations, 10 subassociations and 9 variants classified within 5 association groups were revealed. The peculiarities of their species composition, community structure, ecology and geographical distribution were characterized. Using soil characteristics, several types of sites were recognized. It was shown that mesophytic moss-rich dwarf-pine shrubs (Pinetum pumilae hylocomiosum) were closely connected to the mean values of soil moisture and soil fertility of the sites. Rhododendron-rich dwarf-pine communities (subass. Pinetum pumilae rhododendroso aurei–hylocomiosum) adjoined them but they usually occurred on higher altitudes. Lichen-rich dwarf-pine shrubs (Pinetum pumilae fruticuloso–cladinosum) occupied the driest and poorest sites at the upper border of dwarf-shrub altitudinal belt (350–400 m a.s.l.). The dwarf-shrub-rich Siberian dwarf-pine communities (ass. group Pineta pumilae fruticulosa) were closely connected to rather dry and poor sites. In wet sites with shallow groundwater, Sphagnum-rich dwarf-pine communities (Pinetum pumilae sphagnosum girgensohnii) were found. Cloudberry-rich dwarf-pine shrubs (subass. Pinetum pumilae chamaemori–rubosum) adjoined them but mainly occurred on the peat hillock of palsas. The variation in the species composition and structure of communities are determined by their position in the relief and the density of the dwarf-pine layer. With a similar density of dwarf-pine, Sphagnum-rich dwarf-pine communities form in the foothills, and lichen-rich dwarf-pine shrubs form in mountains. The species diversity and the abundance of the subordinate layers are significantly reduced at the maximum density of the dwarf-pine; so poor-herb dwarf-pine communities (Pineta pumilae oligoherbosa) are formed.