High Beta Diversity Research Articles

Spatiotemporal distributions, co-occurrence networks, and assembly mechanisms of the bacterial community in sediments of the Yangtze River: comprehensive insights into abundant and rare taxa.

Sediments are key reservoirs for rare bacterial biospheres that provide broad ecological services and resilience in riverine ecosystems. Compared with planktons, there is a lack of knowledge regarding the ecological differences between abundant and rare taxa in benthic bacteria along a large river. Here, we offer comprehensive insights into the spatiotemporal distributions, co-occurrence networks, and assembly processes of three divided categories namely always rare taxa (ART), conditionally rare taxa (CRT), and conditionally rare and abundant taxa (CRAT) in sediments covering a distance of 4,300 km in the Yangtze River. Our study demonstrated that ART/CRT contributed greatly to the higher Chao-1 index, Shannon-Wiener index, and phylogenetic alpha diversity of benthic bacteria in autumn than in spring. ART showed high overall beta diversity, and CRT/CRAT exhibited more significant distance-decay patterns than ART in both seasons, mainly corresponding to macroscopic landform types. CRT predominated the nonrandom co-occurrence network, with 97% of the keystone species mostly affiliated with Acidobacteriota flourishing in the lower-reach plain. Two selection processes had the greatest influences on the assembly of CRT (74.7-77.6%), whereas CRAT were driven primarily by dispersal limitation (74.9-86.8%) and ART were driven by heterogeneous selection (33.9-48.5%) and undominated stochasticity (32.7-36.5%). Natural factors such as river flow and channel slope exhibited more significant correlations with community variation than nutrients in all three groups, and total organic carbon mediated the balance among the distinct assembly processes of the ART and CRT in both seasons. Taken together, these results provide an improved ecological understanding of the discrepancy in biogeographic patterns between abundant and rare bacterial taxa in the sediments of Asia's largest river.

Differences in the abundance and diversity of endosymbiotic bacteria drive host resistance of Philodromus cespitum, a dominant spider of central European orchards, to selected insecticides

The ability of tissue endosymbionts to degrade and detoxify agrochemicals is increasingly recognized as a mechanism supporting the survival of arthropods in agroecosystems. Therefore, tissue endosymbionts have the potential to drive insecticide resistance in agrobiont spiders, i.e., in major generalist predators and pest control agents within agroecosystems. We hypothesized that the abundance and diversity of the endosymbiotic bacteria of Philodromus cespitum, a philodromid spider dominating central European apple orchards, vary with regard to differences in predation capacity and drive host insecticide resistance. We provisioned P. cespitum with diets of varying protein and lipid content and topically exposed them to field-relevant doses of commonly used insecticides, namely Mospilan (acetamiprid), Movento (spirotetramat), Gondola (sulfoxaflor), Decis (deltamethrin), Coragen (chlorantraniliprole), and Benevia (cyantraniliprole). The analyses were based on 16S rDNA profiles from lysates of the cephalothorax and legs of the tested spiders. The application of Benevia, Mospilan, and Movento was partially lethal. The spiders that were resistant to the treatments with Benevia, Mospilan, or Movento were associated with the increased relative abundance of Mycoplasmatota by more than one order of magnitude. Additionally, the abundance of other bacteria differed in Mospilan-resistant and Mospilan-sensitive individuals. In contrast, the diet regimens were not associated with any major differences in the microbiome diversity nor the diversity of endosymbionts. Philodromus cespitum hosts assemblages with unexpectedly high beta diversity of endosymbionts. The OTU identified as the alpha proteobacterium endosymbiont of Coelostomidia zealandica was an obligate endosymbiont of the analyzed P. cespitum population. Wolbachia, Rickettsia, and Spiroplasma endosymbionts were also highly prevalent and differed in their responses to the applied treatments. In conclusion, differences in the abundance and diversity of endosymbiotic bacteria drove the resistance of the spider host to selected insecticides.

Dispersal shapes compositional and functional diversity in aquatic microbial communities.

We experimentally assessed the compositional and functional responses of freshwater bacterial assemblages exposed to two consecutive dispersal-related events (dispersal limitation and homogenizing dispersal) under identical growth conditions. While segregation led to a decreased local diversity, high beta diversity sustained regional diversity and functional variability. In contrast, homogenizing dispersal reduced the species pool and functional variability of the metacommunity. Our findings highlight the role of dispersal in regulating both diversity and functional variability of aquatic microbial metacommunities, thereby providing crucial insight to predict changes in ecosystem functioning.

Taxonomic diversity of terrestrial vertebrates in west-central Mexico: Conservation from a multi-taxa perspective.

Multi-taxa approaches are increasingly used because they describe complementary aspects of ecosystem dynamics from a community ecology perspective. In west-central Mexico, the complex biogeography and topography have created an environment where temperate and tropical forests converge, resulting in great biological diversity. Within this region, the Sierra de Quila Natural Protected Area (SQPA) offers an important example for understanding ecological community dynamics. We analyze the taxonomic diversity of terrestrial vertebrates in the SQPA by incorporating taxonomic levels associated with species. We evaluated the taxonomic diversity with i) an average taxonomic distinctiveness analysis (alpha diversity) and ii) an analysis of taxonomic dissimilarity and partitioning of turnover and differences in richness components (beta diversity). Tropical forests boast the highest taxonomic diversity of amphibians, reptiles, and birds, while temperate gallery forests exhibit lower values. Our results showed that terrestrial vertebrate alpha and beta diversity patterns respond mainly to contrasting vegetation types (tropical vs. temperate). Regarding beta diversity, the multi-vegetation type analysis showed the highest values for reptiles, followed by amphibians, birds, and mammals. Turnover had the highest contribution to beta diversity, while differences in richness were relevant for amphibians and reptiles, which could be related to their low mobility and sensitivity to environmental conditions. Despite the local scale, the SQPA presented high beta diversity, reflecting historical ecological processes in taxonomic composition derived from contrasting environments and constraints imposed on species. Evaluating taxonomic structure from a multi-taxa perspective is essential for conservation efforts because it allows the spatial recognition of biological assemblages as a first step for local interventions.

High beta diversity of gaps contributes to plot-level tree diversity in a tropical forest.

Canopy gaps are widely recognized as being crucial for maintaining the diversity of forest tree communities. But empirical studies have found mixed results because the differences in diversity between individual gaps and non-gaps are often small and statistically undetectable. One overlooked factor, however, is how small individual gap versus non-gap differences may accumulate across sites and potentially have a large effect on forest diversity at the plot scale. Our study investigated sapling richness, density, and composition in 124 treefall gaps, and 200 non-gap sites in the 50-ha tropical forest plot at Barro Colorado Island (BCI), Panama. Additionally, we analyzed species accumulation curves to understand how species richness increases with increasing stem numbers. We observed that sapling richness and density were only slightly higher in gaps 7 years after formation and statistically indistinguishable from non-gaps after 12 years. However, species accumulation curves across multiple gaps were substantially higher than those across non-gaps. Species composition showed small differences between individual gaps and non-gaps but differed significantly between collections of gaps and non-gaps. Specifically, 55 species specialized in 7-year-old gaps compared with 24 in non-gaps; of these, 23 gap-specialized species and zero non-gap species were pioneers. Our results indicate that tree species richness is higher in gaps because of both higher stem density and the presence of gap-specialized species. Our study has finally provided compelling evidence to support the idea that gaps enhance the overall diversity of tropical forest tree communities.

Supralittoral isopod (Oniscidea) diversity at three ecoregions along the Colombian Caribbean: useful data for environmental management

Introduction: Terrestrial isopods (Oniscidea) play important roles in the ecological processes of the soil in tropical ecosystems and are employed as indicators of environmental impact. Despite their importance, studies on the ecology of this suborder in the Neotropics are scarce. Objective: To assess spatial changes in alpha and beta diversity of Oniscidea in the supralittoral zone across Archipiélagos Coralinos (ARCO), Magdalena (MAG), and Morrosquillo (MOR) ecoregions in the Colombian Caribbean. Methods: We conducted Direct Intuitive Searches of specimens and measured soil temperature and moisture in 19 transects with logs, leaf litter, coral remains, and decomposing plant material. Results: A total of 1 970 individuals representing 17 species were collected, with Tylidae, Halophilosciidae, and Ligiidae being the most abundant families. Alpha diversity orders were higher in ARCO than MAG and MOR ecoregions. MAG and MOR differed in observed richness. The structure of the assemblage varied in dominant species and abundances. In ARCO, the indicator species were Tylos niveus, Littorophiloscia denticulata, Halophiloscia trichoniscoides, and Ligia baudiniana; in MOR, it was Tylos marcuzzii, and in MAG, it was Littorophiloscia tropicalis. High beta diversity (> 60 %), with significant differences in the assemblage structure among ecoregions, was confirmed by the NMDS, which distinctly separated each group. CCA analysis revealed a negative relationship between most species with soil temperature and moisture, with a positive relationship observed with T. marcuzzii. Conclusions: This is the first effort to describe spatial changes in the diversity of oniscideans in the supralittoral zone of the Neotropical region, providing a baseline for future studies. This information could be instrumental in identifying priority areas for conservation efforts.

Long-term biotic homogenization in the East African Rift System over the last 6 million years of hominin evolution.

Eastern Africa preserves the most complete record of human evolution anywhere in the world but we have little knowledge of how long-term biogeographic dynamics in the region influenced hominin diversity and distributions. Here, we use spatial beta diversity analyses of mammal fossil records from the East African Rift System to reveal long-term biotic homogenization (increasing compositional similarity of faunas) over the last 6 Myr. Late Miocene and Pliocene faunas (~6-3 million years ago (Ma)) were largely composed of endemic species, with the shift towards biotic homogenization after ~3 Ma being driven by the loss of endemic species across functional groups and a growing number of shared grazing species. This major biogeographic transition closely tracks the regional expansion of grass-dominated ecosystems. Although grazers exhibit low beta diversity in open environments of the Early Pleistocene, the high beta diversity of Mio-Pliocene browsers and frugivores occurred in the context of extensive woody vegetation. We identify other key aspects of the Late Cenozoic biogeographic development of eastern Africa, their likely drivers and place the hominin fossil record in this context. Because hominins were undoubtedly influenced by many of the same factors as other eastern African mammals, this provides a new perspective on the links between environmental and human evolutionary histories.

Centimetre scale functional dispersal limitation of freshwater copiotrophs.

The freshwater microbiome harbours numerous copiotrophic bacteria that rapidly respond to elevated substrate concentrations. We hypothesized that their high centimetre-scale beta diversity in lake water translates into pronounced metabolic variability, and that a large fraction of microbial 'metabolic potential' originates from point sources such as fragile organic aggregates. Three experiments were conducted in pre-alpine Lake Zurich over the course of a harmful cyanobacterial bloom: Spatially explicit 9 ml 'syringe' samples were collected in situ at centimetre distances along with equally sized 'mixed' samples drawn from pre-homogenized lake water and incubated in BIOLOG EcoPlate substrate arrays. Fewer compounds promoted bacterial growth in the syringe than in the mixed samples, in particular during the pre- and late bloom periods. Community analysis of enrichments on three frequently utilized substrates revealed both pronounced heterogeneity and functional redundancy. Bacterial consortia had higher richness in mixed than in syringe samples and differed in composition. Members of the Enterobacter cloacae complex dominated the EcoPlate assemblages during the mid-bloom period irrespective of treatment or substrate. We conclude that small-scale functional dispersal limitation among free-living copiotrophs in lake water reduces local biotransformation potential, and that lacustrine blooms of harmful cyanobacteria can be environmental reservoirs for metabolically versatile potential pathogens.

Beta diversity of restored river dike grasslands is strongly influenced by uncontrolled spatio‐temporal variability

AbstractAimsUnderstanding the spatio‐temporal patterns of restoration outcomes is crucial to improve predictability of restoration. High beta diversity of species‐rich communities is sought because it increases overall biodiversity and improves ecosystem stability and multifunctionality. For predictive restoration, it is important to identify the significance of drivers like site characteristics but also uncontrolled factors such as spatial effects, historical factors, and year effects.LocationDikes at river Danube, SE Germany.MethodsWe studied dike grasslands 4–19 years after restoration over five years (2017–2021, 41 plots in 12 sites). We calculated beta diversity indices to describe spatial variation and temporal turnover, including their additive components ‘replacement’ and ‘nestedness’, or ‘gains’ and ‘losses’. We analysed the main drivers of beta diversity like local site characteristics, landscape, and historical factors.ResultsSpatial variation of the restored dike grasslands was dominated by the replacement component and showed no homogenisation despite a significant temporal turnover. The replacement drivers changed over time, although replacement was mainly affected by slope aspect and landscape factors. Historical factors were inconsistent over time, and no statistically clear drivers of nestedness were found. The dike grasslands exhibited a year‐to‐year turnover in species composition of 37 ± 11%. Gains and losses were balanced over time, although the ratio changed and was most pronounced on south‐facing slopes.ConclusionsThe restored grasslands exhibited spatial variation by site characteristics but also by spatial factors which were not controlled by restorations. Moreover, high non‐directional temporal turnover occurred, caused most likely by weather fluctuations, slightly varying management, and stochastic biotic dynamics. Thus, flexible targets are recommended for restoration monitoring, by defining a set of desired states within a certain range. Furthermore, the dominance of the replacement component of spatial variation should move the focus from defining one precise restoration approach to defining a set of possible methods which together would foster beta diversity.

Contrasting patterns and drivers of soil nematode community in regions with different urbanization levels

Rapid urbanization profoundly affects global biodiversity. To date, numerous studies have been conducted on how urbanization affects aboveground flora and fauna. However, the effects of urbanization on the diversity and composition of belowground biota, such as nematodes, remain unknown. To address this knowledge gap, high-throughput sequencing was used to investigate the impact of different urbanization levels (urban regions, suburban regions, and ecoregions) on soil nematode communities in Baoding City, China. Our results revealed that the soil nematode communities in urban regions exhibited a lower alpha diversity (richness) and a higher beta diversity than those in ecoregions. This is potentially due to the loss of native specialist species in urban regions and higher environmental heterogeneity of urban regions compared with other regions. Random forest and network analysis revealed that heavy metals, soil properties, and a few representative nematode taxa mainly contributed to the variations of nematode community diversity among regions with different urbanization levels. The main drivers of variations include lead content and the Tylenchida order in urban regions, cadmium and the Rhabditida order in suburban regions, and total organic carbon and numerous taxa in ecoregions. It is not difficult to find that soil heavy metal pollution originating from human activity plays an important role in the variations of soil nematode communities. Structural equation models revealed that the diversity of the soil nematode community was altered by urbanization directly or indirectly via either bacterial diversity or nematode abundance, and the pathways were contrasting for different regions. Overall, our results indicated that urbanization reduced soil nematode diversity and changed the composition of soil nematode communities, likely leading to biodiversity loss, and the establishment of ecological preservation areas maybe help improve the situation.

Implementing ITS1 metabarcoding for the analysis of soil microeukariotic diversity in the Mountain Cloud Forest

PurposeIn threatened diversity hotspots, such as mountain cloud forests, microbiome studies have focused essentially on bacteria. Unlike prokaryotic microbiomes, the study of the microeukaryotes has largely been restricted to the visual identification of specific groups. Herein, microeukaryotic edaphic diversity from a pristine mountain cloud forest (MCF) of Mexico was analyzed via the metabarcoding of the ITS1 region of ribosomal DNA.Materials and methodsAn exploratory triangular sampling was conducted in the mountain cloud forest located in El Relámpago Mount, Santiago Comaltepec, Oaxaca, Mexico. Each vertex was located adjacent to a dominant plant species in the ecosystem (Oreomunnea mexicana and Alsophila salvinii). After DNA extraction the ITS1 region (rDNA) was amplified. Microeukaryotic sequences were filtered by computational subtraction against the ITS2 Database. Next, alpha and beta diversity indexes were calculated, and the relationship between abiotic variables and diversity patterns were inferred by means of a Canonical Correspondence Analysis.ResultsOverall, 138 inferred sequence variants were identified, including 87 protists, 35 animals (microfauna), and 16 algae. Within the animals, the nematodes were the dominant group, chlorophytes dominated algae, and in Protista, no dominance patterns were observed given the high diversity and equitability of this group. Soil available carbon, carbon degrading enzymes and the pH play a key role in modeling the community structure. Remarkably, high beta diversity levels were obtained, evidencing a strong spatial heterogeneity at the small scale.ConclusionsThe ITS metabarcoding proved to be a useful tool to conduct multi-taxa diversity assessments for microeukaryotes, allowing the identification of alpha and beta diversity patterns and overcoming limitations of sampling and the direct observation of individuals. The results presented in this work evidenced high microeukaryotic diversity levels in the soil of MCF and encourage future studies aiming to explore the taxonomic diversity of individual taxa.

Dissimilarity among Species and Higher Taxa of Amphibians in a Hotspot of Biodiversity and Endemism in the Neotropics

The Mexican Republic ranks fifth in the world in terms of amphibian diversity, and within Mexico, the state of Oaxaca has the greatest amphibian richness and endemism. Unfortunately, various factors, such as land use change and global warming, have caused a global crisis that threatens the conservation of this class. In the face of these threats, an analysis of beta diversity provides information that can be applied to conservation strategies, since its study reveals the spatial scaling of diversity loss and clarifies the mechanisms of regional diversity maintenance. In this work, we analyzed the beta diversity at the species and higher taxa level (order, family, subfamily, genus and species) for the amphibians of Oaxaca and their replacement components and the differences in richness for anurans and caudates separately between physiographic subprovinces. Very high beta diversity was recorded, with higher diversity occurring among caudates (0.92) than among anurans (0.84). Species replacement was the component that most contributed to this result, and the subprovinces with substantial environmental differences had the most dissimilar amphibian communities. The results of this study show the need to implement conservation strategies in subprovinces with high amphibian richness and endemism levels, following the example of Sierra Madre de Oaxaca (SMO), where local communities have developed conservation actions in most of the territory.

Effects of land use and climate on the diversity and population structure in natural stands of Detarium microcarpum Guill. & Perr. (Fabaceae) in Burkina Faso (West Africa)

Detarium microcarpum Guill. & Perr. is a multipurpose species, providing many ecosystem services. However, in its geographical range, its multiple uses represent a major challenge to the sustainable management and conservation of its resources. This study aimed to determine the effect of climatic zones, land uses, and their interaction on the natural stands of D. microcarpum. Inventories were conducted in 165 plots in two climatic zones and land use types in Burkina Faso. Hill diversity indices were used to determine the effects of climatic zones, land uses, and their interaction on D. microcarpum stand diversity. Generalized linear models were used to assess the effect of the abiotic and biotic factors on the species' structural parameters. Land uses and climatic zones significantly affected D. microcarpum stand diversity and structure. The lowest stand diversity was recorded in the unprotected areas. The similarity in woody species composition between land uses and climatic zones was low, indicating high beta diversity. The generalized linear model showed that rainfall, temperature, habitat heterospecific density, and habitat-specific richness significantly influenced the structural parameters of the D. microcarpum population. The diameter classes’ distribution revealed unstable populations for the adult stratum, independent of climatic zones and land use types, except for the protected area in the Sudanian zone. The height class distribution of the juvenile stratum highlighted the instability regeneration of D. microcarpum populations. This study highlighted the instability of D. microcarpum populations and the specific effects of biotic and abiotic variables on the species' structural parameters. Thus, the findings suggest urgent conservation measures to ensure sustainable utilisation and management of the species.

Evaluating ecosystem protection and fragmentation of the world's major mountain regions.

Conserving mountains is important for protecting biodiversity because they have high beta diversity and endemicity, facilitate species movement, and provide numerous ecosystem benefits for people. Mountains are often thought to have lower levels of human modification and contain more protected area than surrounding lowlands. To examine this, we compared biogeographic attributes of the largest, contiguous, mountainous region on each continent. In each region, we generated detailed ecosystems based on Köppen-Geiger climate regions, ecoregions, and detailed landforms. We quantified anthropogenic fragmentation of these ecosystems based on human modification classes of large wild areas, shared lands, and cities and farms. Human modification for half the mountainous regions approached the global average, and fragmentation reduced the ecological integrity of mountain ecosystems up to 40%. Only one-third of the major mountainous regions currently meet the Kunming-Montreal Global Biodiversity Framework target of 30% coverage for all protected areas; furthermore, the vast majority of ecosystem types present in mountains were underrepresented in protected areas. By measuring ecological integrity and human-caused fragmentation with a detailed representation of mountain ecosystems, our approach facilitates tracking progress toward achieving conservation goals and better informs mountain conservation.

Distinct microbial communities are linked to organic matter properties in millimetre-sized soil aggregates.

Soils provide essential ecosystem services and represent the most diverse habitat on Earth. It has been suggested that the presence of various physico-chemically heterogeneous microhabitats supports the enormous diversity of microbial communities in soil. However, little is known about the relationship between microbial communities and their immediate environment at the micro- to millimetre scale. In this study, we examined whether bacteria, archaea, and fungi organize into distinct communities in individual 2-mm-sized soil aggregates and compared them to communities of homogenized bulk soil samples. Furthermore, we investigated their relationship to their local environment by concomitantly determining microbial community structure and physico-chemical properties from the same individual aggregates. Aggregate communities displayed exceptionally high beta-diversity, with 3-4 aggregates collectively capturing more diversity than their homogenized parent soil core. Up to 20%-30% of ASVs (particularly rare ones) were unique to individual aggregates selected within a few centimetres. Aggregates and bulk soil samples showed partly different dominant phyla, indicating that taxa that are potentially driving biogeochemical processes at the small scale may not be recognized when analysing larger soil volumes. Microbial community composition and richness of individual aggregates were closely related to aggregate-specific carbon and nitrogen content, carbon stable-isotope composition, and soil moisture, indicating that aggregates provide a stable environment for sufficient time to allow co-development of communities and their environment. We conclude that the soil microbiome is a metacommunity of variable subcommunities. Our study highlights the necessity to study small, spatially coherent soil samples to better understand controls of community structure and community-mediated processes in soils.

The difference and variation of gut bacterial community and host physiology can support adaptation during and after overwintering in frog population.

The hibernation of amphibians can offer a unique window into overwintering adaptation processes and host-gut microbiota interactions through changes in metabolic availability and homeostasis. We attempted to identify differences in the physiology and gut microbiome during and after hibernation in Japanese wrinkled frogs (Glandirana rugosa), an aquatic overwintering amphibian. After hibernation, the high alpha and beta diversity of the gut bacterial community appears to reflect the more diverse and complex environmental conditions. During winter, Proteobacteria dominated the majority of the gut bacterial community, likely due to high oxygen saturation. After hibernation, Firmicutes and Bacteroidetes increased, which are supportive of host metabolism by gut microbiota. Corticosterone also showed high values and variances after hibernation, presumably allowing the population to remain adaptable across a broad range of environmental gradients. Innate immunity was high after hibernation but exhibited low variation among populations, which supports the idea of a prioritized investment in immunity after hibernation. Blood biochemistry suggests that aquatic overwintering frogs have a mechanism to adapt through overhydration and regulate homeostasis through water excretion associated with the kidney and urine after hibernation. Frog populations exhibit variations and adaptability in gut microbiota and physiology during and after hibernation: Through this, they may demonstrate an adaptive response that regulates metabolic availability in preparation for unpredictable environmental changes. We also propose that the maintenance of Proteobacteria during hibernation can support the colonization of Firmicutes and Bacteroidetes after hibernation, underscoring the need to study the complex effects of gut microbiota across multiple life stages.

Diversidade beta de assembleias de macroinvertebrados associados a macrófitas aquáticas em lagos rasos na planície de inundação de um rio tropical represado

Abstract: Aims We assessed the beta diversity of macroinvertebrates associated with aquatic macrophytes in a dam-regulated river floodplain. We tested two hypotheses: (1) macroinvertebrates associated with aquatic macrophytes have higher beta diversity (higher turnover and nestedness components) in the downstream areas closer to the São Francisco River compared to upstream sites; (2) closer lakes share a higher similarity of aquatic macroinvertebrates, disregarding their position relative to the dam. Methods We sampled four lakes, including two upstream (L1- natural and L2- regulated by a Small Hydropower Dam - SHD) and two downstream (L3, L4, unregulated) by the SHD. Results We corroborated our first hypothesis because we found a higher turnover of macroinvertebrates associated with aquatic macrophytes close to the São Francisco River (L4 downstream), where higher non-native mollusk species richness occurs, while we found higher nestedness upstream and downstream of the SHD (L1, L2, L3). We corroborated our second hypothesis, as closer lakes are more similar than distant lakes. Finally, these differences were consistent between lakes for emergent, floating leaf, and submerged aquatic macrophytes. Conclusions Aquatic macrophytes are essential habitats for macroinvertebrates in the Pandeiros River basin, with higher beta diversity in the lake closer to the São Francisco River.

Водные и прибрежно-водные сообщества в водоемах Ненецкого автономного округа

Syntaxonomic diversity of aquatic and helophyte communities was identified on the basis of 267 relevés carried out from 2005 to 2023 in 16 sites in the Bolshezemelskaya and Malozemelskaya tundras, Kolguyev Isl. and the Pechora River delta. For almost all described communities it was possible to determine their belonging to the association level, as many of them consist of species with extensive ranges (circum-, cosmopolitans) and occur in numerous regions on different continents. Prodromus contains 30 associations (with 3 subassociations and 8 variants) from 14 alliances, 9 orders and 6 classes. Four syntaxa of the association rank were left at the community rank due to the small number of relevés. Aquatic vegetation is represented by communities of the classes Lemnetea (free-floating duckweed communities), Potametea (rooted hydrophytes with leaves floating on the water surface and/or in the water column communities) and Littorelletea uniflorae (amphibious plants in fluctuating shallow water bodies communities). One association — Lemnetum trisulcae (Table 1, rel. 19–21; Fig. 5) is described in the class Lemnetea. The class Potametea turned out to be the richest, with 10 associations in 2 orders and 2 alliances. These are associations Myriophylletum sibirici, Myriophylletum verticillati, Potametum berchtoldii, Potametum filiformis, Potametum pectinati, Potametum perfoliati, Potametum praelongi, Potametum tenuifolii and community Potamogeton sibiricus (Table 2, rel. 1–38; Table 3, rel. 1–18; Fig. 6–12) in the alliance Potamion within the order Potametalia; Callitrichetum hermaphroditicae and Callitricho–Ranunculetum trichophylli (Table 3, rel. 19–27; Fig. 13, 14) in the alliance Ranunculion aquatilis within the order Callitricho hamulatae–Ranunculetalia aquatilis. Four associations of two alliances are described in the order Littorelletalia uniflorae within the class Littorelletea uniflorae: Callitricho palustris–Sparganietum angustifolii and Sparganietum hyperborei (Table 4, rel. 1–35; Fig. 15, 16) in Sparganion hyperborei, and Callitrichetum palustris and Litorello–Eleocharitetum acicularis (Table 5, rel. 1–5; Fig. 17, 18) in Littorellion uniflorae. Helophyte vegetation is represented by communities from 3 orders of the class Phragmito-Magnocaricetea. There are associations Petasitetum radiatae (alliance Petasition radiatae) and Equisetetum fluviatilis (alliance Phragmition australis) in the order Phragmitetalia australis (Table 6, rel. 1–21; Fig. 19, 20); and Caricetum aquatilis and Equiseto fluviatilis–Caricetum rostratae (alliance Magnocaricion elatae), Comaretum palustris, Menyanthetum trifoliatae and com. Cicuta virosa (alliance Carici–Rumicion hydrolapathi) (Table 6, rel. 22–34; Table 7, rel. 1–41; Fig. 21–25) in the order Magnocaricetalia. The order Oenanthetalia aquaticae includes the following described or validated associatios: Arctophiletum fulvae (alliance Arctophilion fulvae) with 2 subassociations — typicum and validated ranunculetosum hyperborei Möller ex O. Lavrinenko, I. Lavrinenko, Tsyvkunova et D’yachkova subass. nov. hoc loco, Ceratophyllo demersi–Eleocharitetum mamillatae, Eleocharitetum palustris subass. arctophiletosum fulvae, Hippuridetum lanceolatae Pestryakov et Gogoleva ex O. Lavrinenko, I. Lavrinenko, Tsyvkunova et D’yachkova ass. nov. hoc loco and com. Ranunculus pallasii (alliance Eleocharito palustris–Sagittarion sagittifoliae (Table 8, rel. 1–29; Table 9, rel. 1–28; Fig. 27–31). The class Isoёto-Nanojuncetea, which unites pioneer ephemeral low grass communities in periodically flooded freshwater habitats, contains one association — Juncetum bufonii (Table 10, rel. 6–8, Fig. 32) from the alliance Eleocharition soloniensis within the order Nanocyperetalia. Summer-annual pioneer vegetation of periodically nutrient-rich river alluvia, drained muddy bottoms of eutrophic lakes and heavily nutrientloaded anthropogenic habitats is represented by the ass. Tephroseridetum palustrisMirkin, Gogoleva et Kononov nom. mut. nov. (Table 10, rel. 1–2, Fig. 33) from the alliance Bidention tripartitae within the order Bidentetalia and the class Bidentetea. For aquatic bryophyte vegetation (Mucina et al., 2016: EuroVegChecklist 2) a provisional alliance Calliergonion megalophylli O. Lavrinenko all. prov. is proposed. It unites two associations and one community of hypnum mosses (Calliergonetum megalophylli, Sarmentypnetum trichophylli, com. Sarmentypnum exannulatum) growing underwater, in the water column and and over-watered shores in shallow meso- and eutrophic lakes. The highest beta-diversity (19 syntaxa) is established in floodplain and river-formed lakes, usually overgrowing, with muddy and sandy-silt bottoms. The lower stand richness (13 syntaxa) and high accumulation of macrophyte phytomass are noted in shallow, well-warmed lagoonal lakes and baths with a thick layer of bottom silt on brackish marshes at the mouths of rivers flowing into the bays. Aquatic plants literally fill such reservoirs, with a single species often growing in these. Comparable stand diversity (13 syntaxa) is established for thermokarst lakes with mineral soils on flat watersheds. The number of syntaxa is much lower (7) in thermokarst lakes on peatlands. Phytocenotic diversity is determined by ecological conditions of habitats — richness of substrate, water acidity, and water temperature, which depends on the proximity of permafrost.

Local and regional diversity of frog communities along an extensive rainforest elevation gradient in Papua New Guinea

AbstractRainforests on high tropical mountains are globally important species diversity hotspots. We studied amphibians along an extensive rainforest elevation gradient on Mt. Wilhelm (4509 m) in Papua New Guinea. We established eight sites at 500 m elevation increments between 200 and 3700 m a.s.l. and relate their community composition to the known species pool of New Guinea island. We recorded 3390 frogs from 55 species, which is three times more species than at any local community along the elevation gradient. Species diversity peaked at 1700 m a.s.l. for Mt. Wilhelm communities, and at 500–1100 m a.s.l. in the broader New Guinea fauna, probably reflecting increasing speciation and decreasing dispersal rates with increasing elevation. The beta diversity between frog communities was high and increased with increasing elevation. The change in frog community composition across 500 m elevation corresponded to the change over 200 km distance within lowland forests. A majority of frog species were distributed over narrow <500 m elevational ranges, at Mt Wilhelm and the New Guinea fauna more broadly. We did not detect Rapoport's pattern of wider elevation range for species at higher elevations than for lowland species, for Mt. Wilhelm communities or the New Guinea fauna. The high beta diversity patterns along elevation gradients generated by rapid species turnover with narrow elevation ranges make frog communities vulnerable to change in environment, including climate change.Abstract in Melanesian Pidgin is available with online material.

Soil microbial diversity under different types of interference in birch secondary forest in the Greater Khingan Mountains in China.

Soil microorganisms are an important component of soil ecosystems with an indispensable role in forest ecosystems. We analyzed the soil microbial diversity in birch secondary forest formed by natural restoration or artificial reconstruction after interference by burning, clear cutting, and gradient cutting, and the Betula platyphylla Suk undisturbed forest in the Greater Khingan Mountains in China. Illumina high-throughput sequencing technology was used to analyze the characteristics of the soil microbial community during the restoration process of birch secondary forest caused by the different types of interference. The relationships between bacteria and fungi were analyzed. The gene functions of the soil bacterial community and the ecological functions of soil fungi were predicted using PICRUSt and FunGuild, respectively. At the phylum level, the species and quantity of bacteria were more abundant than that of fungi. At the genus level, no obvious differences in the abundance of bacteria were observed; there were obvious differences in the abundance of fungi. Among the eight sample plots, the artificial larch forest belt had the highest bacterial and fungal alpha diversity, which was slightly higher than undisturbed forest, while the other sample plots were significantly lower. Gradual cutting pure birch forest bacteria and fungi had the highest beta diversity, and artificial larch forest belt bacteria and heavy burn sample plot fungi had the lowest beta diversity. Samples from the cutting and burning sample plots were significantly different from the undisturbed forest at the phylum level of Acidobacteriae, Acidimicrobiia, Mortierellomycetes and Sordariomycetes. We found statistical differences in biomarkers between bacterial and fungal communities in undisturbed forest and artificial larch forest belt and burn sample plots. PICRUSt prediction and FunGuild prediction showed that soil bacterial and fungal communities were rich in gene and ecological functions, respectively. In the microbial network, the stability or anti-interference performance of the fungal community was higher than that of bacteria. Our data reveal the characteristics of the soil microbial community during the restoration process of Betula platyphylla Suk secondary forest under different types of disturbance, which is of great significance for understanding the role of soil microorganisms in the forest ecological cycle.