Similarity In Species Composition Research Articles

The variety of abomasal nematode communities of captive and free-roaming populations of European bison, Bison bonasus (L.): a morphometric and molecular approach.

Most studies concerning parasitic infections in European bison have been performed on free-ranging animals: comparatively little is known about the abomasal nematodes of captive wisents, which are widely used in reintroduction programmes. The aim of the study was to determine the infection level and species composition of abomasal nematodes in captive European bison in enclosures (including zoos) and breeding centres compared to free-ranging individuals. It also includes a morphological analysis of the parasites based on figures and measurement data. Altogether, 11 species of nematodes were detected, with both captive and free-ranging animals demonstrating similar species compositions. Among those, 2 species of blood-sucking nematodes were detected, including Ashworthius sidemi and Haemonchus contortus. Interestingly, A. sidemi was found in almost all free-roaming animals, but only in 1 captive European bison. In addition, H. contortus was predominant in captive animals. The morphological identification was confirmed molecularly for 5 nematode species: A. sidemi, H. contortus, Ostertagia kolchida, O. ostertagi and Spiculopteragia boehmi. The identification was performed using small subunit ribosomal rDNA. The study provides the first available set of specular lengths of the gastric nematodes of European bison, and the first molecular data of O. kolchida and S. boehmi derived from the same host species. Our findings may simplify the morphometrical and molecular identification of Trichostrongylidae species infecting European bison, and can be useful in developing new management strategies for populations of this near-threatened species in Europe.

Eco-Habitat Assessment of One of the Most Expensive Edible Mushrooms (Tricholoma matsutake) in Genekha, Thimphu, Bhutan

Tricholoma matsutake (S. Ito & Imai) Singer is most expensive edible mushroom, naturally grown dispersed in temperate oak pine forested areas in Bhutan. It is ectomycorrhizal fungi with high ecological and economic value requiring an important ecological niche and symbiotic tree associates. The present study is an attempt to give an account on floristic composition and vegetation structure of Tricholoma matsutake habitat in Genekha, Thimphu. A total of 10 plots were enumerated with plot size of 20m X 20m, 5m X 5m and 2m X 2m for trees, shrubs and herbs respectively. PAST (Paleontological Statistics) 4.10 software was used for diversity analysis. A total of 58 species under 44 genera belonging to 26 families were recorded in the natural habitat of matsutake. The study revealed that T. matsutake is associated with Quercus semecarpifolia Sm., Pinus wallichiana A.B. Jack., Rhododendron spp., and Pieris formosa (Wall.) D. Don. J-shaped distribution curve of DBH and height class with fair regeneration status is obtained for associated species in the habitat. The Menhinick’s species richness of (2.26, 2) for both North facing habitat (NFH) and South facing habitats (SFH) indicated high species richness. Moderate and low diversity is indicated with Simpsons index 0.94 (NFH) and 0.76 (SFH), Shannon index 3.06 (NFH) and 2.49 (SFH) with moderately even distribution 0.74(NFH) and 0.73 (SFH) of species in the habitats. Sorensens similarity index of 0.9 indicated highly similar species composition between two habitats. This research provides current floristic and vegetation structure of Tricholoma matsutake habitat, that will have high significance in habitat management and conservation.

Phylogeography of Pleurospermum foetens (Apiaceae) From the Sky Islands of Southwest China.

Sky islands provide insights on how glacial-interglacial cycles have shaped species distribution and help for predicting species' responses to climate warming. The alpine subnival belt of southwest China, especially in the Hengduan Mountains and adjacent areas, is sky island-like. Among them, the Yunnan-Kweichow Plateau harbors several isolated mountains with well-developed alpine subnival vegetation, sharing a similar species composition with the Hengduan Mountains. However, the relationship between the sky islands of the Hengduan Mountains and the Yunnan-Kweichow Plateau remains insufficiently explored. Pleurospermum foetens (Apiaceae) is a species endemic to the alpine screes of the Yunnan-Kweichow Plateau and the Hengduan Mountains. We used DNA sequence data from 59 individuals across 9 populations, combined with ecological niche modeling, to investigate the evolution history and future distribution of P. foetens within this sky island region. The results indicate the following: (1) P. foetens exhibits a significant phylogeographic structure and can be classified into three nrDNA clades and two cpDNA clades, respectively, (2) a nuclear-plastid discordance observed in P. foetens and its relatives based on phylogenetic analysis. P. foetens is monophyletic in the nrDNA phylogeny, while two major clades (HDM and YGP) are present in the cpDNA phylogeny, each forming a clade with other congeneric species. (3) Ecological niche modeling of P. foetens indicated that the species had the most extensive suitable habitat during the last glacial maximum (LGM). However, anticipated climate warming in the coming decades is expected to reduce the suitable range of P. foetens, posing a significant threat to isolated marginal populations (e.g., Shizi Mountain) with restricted alpine scree habitats. In conclusion, our study highlights the substantial effect of sky island and glacial-interglacial cycles on the population divergence of P. foetens. Conservation efforts for marginal populations of alpine plants in the Yunnan-Kweichow Plateau require increased attention and prioritization.

Xylotrophic Agaricomycetes Monitoring in Some Types of Spruce and Birch Forests (Subzone of the Southern Taiga, Perm Territory, Russia)

We have summarized the results of xylotrophic agaricoid basidiomycetes long-term monitoring in some types of indigenous and derived forests in the southern taiga subzone of Perm Krai. We carried out the research by a stationary method on the test 50×20 m areas, one in each type of forest: spruce forest at the brook, sorrel spruce forest and birch forest. We did the work in three periods: I – 1975–1977, II – 1994–1996, III – 2010–2012. The collection of material was carried out annually: in August 3 times with an interval of 10 days (the species composition, number and air-dry biomass of basidiomes were taken into account), and in September once (only the species composition of fungi was taken into account). To date, we have established that the number of xylotrophic agaricoid fungi in the studied forest types varies from 60 (sorrel spruce forest) to 66 (birch forest). Most of the identified species belong to the Tricholomataceae family (37.7–43.3% of the total number of xylotrophic fungi species in each of the biogeocoenoses). There was an annual accumulation of detectable fungal species, with the largest number of species (67–75%) detected from 2 to 9 times, and 2–3% of them were permanent, occurring annually. There was relative stability of the species composition of higher vascular plants (Jaccard generality coefficient: J = 56–88) over time and more significant changes in the species composition of xylotrophic fungi (J = 36–50). The spruce forests had the most similarity of fungi species composition between the cenoses by periods (J = 44–52), and for the entire observation period, the sorrel spruce forest and birch forest had the maximum Jaccard index between cenoses (J = 56). The yield of xylotrophic agaricoid fungi in the studied cenoses varies by years of observation. The birch forest had the largest number and biomass of basidiomata for all the three periods of the research. A decrease in the number of basidiomes of xylotrophic fungi in the sorrel spruce forest was established with an increase in the average monthly air temperature in August (Spearman correlation coefficient: rs = −0.70). The sorrel spruce forest was the most favorable for the biota of xylotrophic agaricoid basidiomycetes, both in number (Shannon index: H = 1.23) and in biomass (H = 1.20), during all the research, since the biota of xylotrophes of the specified cenosis was more diverse and its components were most aligned.

CURRENT STATUS OF SCABIOSA ISETENSIS POPULATIONS IN CENTRAL KAZAKHSTAN

The paper presents the results of studying the structure of 6 populations of Scabiosa isetensis growing in Central Kazakhstan. The floristic composition of communities, the ratio of life forms, ecological groups and age spectrum were evaluated. The floristic composition of the populations was 79 species from 56 genera and 23 families, of which the leading are the families of Asteraceae and Fabaceae. Herbaceous perennials predominate among life forms, mesophytes and xerophytes by ecological groups. Such a spectrum of families in populations with Scabiosa isetensis and ecological and biomorphic composition is a vivid indicator of the degree of habitat heterogeneity. Analysis of Jaccard's similarity indices showed similarity in species composition between populations 4 and 5; 1 and 2; 3 and 6, which is explained by similar habitat conditions. All studied populations are characterized by a single type of ontogenetic spectrum - left-handed type with predominance of juvenile individuals, i.e. populations with Scabiosa isetensis are young, developing, and suitable for practical use.

Seasonal variability of epipelic microphytobenthos community in two subtidal areas of the Northern Adriatic Sea

We investigated the biodiversity and seasonality of subtidal benthic diatoms at two sites of the Northern Adriatic Sea differently affected by anthropogenic inputs. Sediment samples were collected seasonally, and diatom cells were then separated from the sediment using the density gradient centrifugation method. The total abundance of benthic diatoms ranged between 4,409 ± 1,638 and 77,663 ± 30,415 cells cm-2 and the biomass between 0.41 ± 0.22 and 3.66 ± 2.01 μg C cm-2. At both stations, the benthic diatoms showed a marked seasonal pattern, with maximum abundance, biomass and biodiversity in spring and minimum in summer. Motile life forms, such as Navicula, Nitzschia, Fallacia, and Psammodictyon, dominated in terms of abundance at both stations throughout the study period, while plocon (centric diatoms mainly belonging to Biddulphiaceae) increased under mixing conditions, when they represented the largest contributor to biomass. At both stations and in all seasons, the Si:N:P ratio highlighted the strong P limitation, typical of the Adriatic Sea. The ammonium concentration was the highest component of DIN in spring and summer when we observed the highest and lowest MPB abundance respectively. The preference of diatoms for ammonia, coupled with the increased daylight period, may have enhanced the spring growth, whereas in summer the hypoxic conditions may have caused a decrease. Despite the different environmental conditions, the two stations exhibited similar species compositions and seasonal trends, highlighting relative stability against anthropogenic pressures of a different nature.

Long-term directional changes in urban bird communities of Mar del Plata City, Argentina

Urban environments have been characterized by their temporal stability of resources, which could promote stability in bird composition. Several studies have found that bird communities in urban environments persist over the years, showing a similar species composition in the short term. However, studies analyzing continuous changes in urban communities over the long term are scarce. This study aimed to analyze the stability or directional changes (instability) in bird communities along an urban gradient. Bird counts were conducted in urban, suburban, and periurban areas over 8-10 years in 2002-2019. Changes in species composition were analyzed over periods ranging from one year to the next, to changes from one year to the seventeenth. Urban bird communities were more similar between years than suburban and periurban communities. Compositional changes were greater as time lags increased, indicating directional compositional shifts. The magnitude of these changes was similar across the urban gradient. The Chimango Caracara (Milvago chimango), the Picazuro Pigeon (Patagioenas picazuro), the Rufous Hornero (Furnarius rufus), and the Red-bellied Thrush (Turdus rufiventris) significantly increased their abundances during the period, while the House Sparrow (Passer domesticus) significantly decreased its abundance. Regional changes in species abundance, urban vegetation succession, and biotic interactions could explain the changes in bird communities.

Effects of developmental stages, sex difference, and diet types of the host marmalade hoverfly (Episyrphus balteatus) on symbiotic bacteria.

Symbiotic bacteria play key roles in a variety of important life processes of insects such as development, reproduction and environmental adaptation, and the elucidation of symbiont population structure and dynamics is crucial for revealing the underlying regulatory mechanisms. The marmalade hoverfly (Episyrphus balteatus) is not only a remarkable aphid predator, but also a worldwide pollinator second to honeybees. However, its symbiont composition and dynamics remain unclear. Herein, we investigate the symbiotic bacterial dynamics in marmalade hoverfly throughout whole life cycle, across two sexes, and in its prey Megoura crassicauda by 16S rRNA sequencing. In general, the dominant phyla were Proteobacteria and Firmicutes, and the dominant genera were Serratia and Wolbachia. Serratia mainly existed in the larval stage of hoverfly with the highest relative abundance of 86.24% in the 1st instar larvae. Wolbachia was found in adults and eggs with the highest relative abundance of 62.80% in eggs. Significant difference in species diversity was observed between the adults feeding on pollen and larvae feeding on M. crassicauda, in which the dominant symbiotic bacteria were Asaia and Serratia, respectively. However, between two sexes, the symbionts exhibited high similarity in species composition. In addition, our results suggested that E. balteatus obtainded Serratia mainly through horizontal transmission by feeding on prey aphids, whereas it acquired Wolbachia mainly through intergeneration vertical transmission. Taken together, our study revealed the effects of development stages, diet types and genders of E. balteatus on symbionts, and explored transmission modes of dominant bacteria Serratia and Wolbachia. Our findings lay a foundation for further studying the roles of symbiotic bacteria in E. balteatus life cycle, which will benefit for revealing the co-adaptation mechanisms of insects and symbiotic bacteria.

Spatiotemporal Dynamics of Plankton Communities in the Chongqing Section of the National Nature Reserve for Rare and Endemic Fishes in the Upper Yangtze River

In order to understand the community structure of plankton and environmental factors in the Chongqing section of the National Nature Reserve for Rare and Endemic Fishes (referred to as the “Reserve”) along the upper Yangtze River, this study investigated phytoplankton and zooplankton in the water body from 2021 to 2022. The results revealed a diverse phytoplankton community with 243 species from 105 genera and 8 phyla, dominated by Bacillariophyta and Chlorophyta. Phytoplankton showed average densities of 1.7 × 106 cells/L and biomass of 2.6221 mg/L, following a seasonal pattern of summer > spring > winter. Zooplankton analysis identified 141 species from 77 genera and 4 phyla, with rotifers most abundant, followed by protozoa. Zooplankton displayed average densities of 0.17 × 104 ind./L and biomass of 0.3226 mg/L, also following a seasonal pattern of summer > spring > winter. Total phosphorus (TP) emerged as the primary environmental factor influencing plankton community structure, positively correlating with phytoplankton density and zooplankton biomass. Plankton biodiversity indices classified water quality in the Chongqing section of the “Reserve” as oligo-/mesotrophic. Overall, plankton diversity in this section is notably rich, with similar species composition between mainstems and tributaries but seasonal variations in community structure. While mainstem water quality generally meets standards, some tributaries exhibit varying degrees of pollution, underscoring the need for improved ecological management and protection measures. This is crucial for maintaining the sustainability of the ecosystem.

Clustering and unconstrained ordination with Dirichlet process mixture models

Abstract Assessment of similarity in species composition or abundance across sampled locations is a common goal in multi‐species monitoring programs. Existing ordination techniques provide a framework for clustering sample locations based on species composition by projecting high‐dimensional community data into a low‐dimensional, latent ecological gradient representing species composition. However, these techniques require specification of the number of distinct ecological communities present in the latent space, which can be difficult to determine in advance. We develop an ordination model capable of simultaneous clustering and ordination that allows for estimation of the number of clusters present in the latent ecological gradient. This model draws latent coordinates for each sample location from a Dirichlet process mixture model, affording researchers with probabilistic statements about the number of clusters present in the latent ecological gradient. The model is compared to existing methods for simultaneous clustering and ordination via simulation and applied to two empirical datasets; JAGS code to fit the proposed model is provided in an appendix. The first dataset concerns presence‐absence records of fish in the Doubs river in eastern France and the second dataset describes presence‐absence records of plant species in Craters of the Moon National Monument and Preserve (CRMO) in Idaho, USA. Results from both analyses align with existing ecological gradients at each location. Development of the Dirichlet process ordination model provides wildlife managers with data‐driven inferences about the number of distinct communities present across monitored locations, allowing for more cost‐effective monitoring and reliable decision‐making for conservation management.

Changes in vegetation composition and structure following landslide-induced disturbance in the Himalaya

The Himalaya cover 12% of India's landmass and are prone to approximately one-seventh of global rainfall-triggered landslides. Still, very few studies have examined the after-effects of landslides on native vegetation structure and composition. This study aims to fulfill this gap by analyzing the vegetation structure and composition of 10 landslide-impacted sites in Uttarakhand Himalaya along an elevational gradient between 1400–3500 m. The investigations revealed that physiognomically, the younger landslide-disturbed sites were dominated by herbaceous taxa while shrubs and trees dominated the older landslide-disturbed sites. Shannon–Wiener diversity values were highest at the old-low disturbed site compared with recent and young disturbed sites. Sorensen similarity index values indicated that the older landslide sites had the highest similarity in species composition of disturbed and undisturbed sites. The younger and recently disturbed landslide sites were highly dissimilar in species composition and structure as compared to the adjacent undisturbed sites. Notably, both the landslide-disturbed and undisturbed sites had a high percentage of native species (90%–95%). The fundamental understanding developed from this study can have potential applications in evolving management practices for ecological restoration of the degraded ecosystems in the Himalaya and other mountain ecosystems around the world.

Identification of metacommunities in bioregions with historical habitat networks.

Although metacommunity theory provides many useful insights for conservation planning, the transfer of this knowledge to practice is hampered due to the difficulty of identifying metacommunities in bioregions. This study aims to identify the spatial extent of metacommunities at bioregional scales using current and historical habitat data, especially because contemporary biodiversity patterns may be a result of time-lagged responses to historical habitat configurations. Further, this estimation of the metacommunity spatial extent is based on both the habitat structure and the dispersal ability of the species. Focusing on dragonfly and damselfly (odonate) species in the eastern Swiss Plateau, the research uses wetland habitat information spanning over 110 years to create a time series of nine habitat networks between 1899 and 2010. From these networks, we identified the spatial extents of metacommunities based on the year of habitat information as well as on watershed boundaries. To identify the best metacommunity spatial extents, the study investigates whether patch pairs within a metacommunity exhibit greater similarity in species composition (i.e. lower beta-diversity) than patch pairs between metacommunities. For the different metacommunities, we further investigated correlations between gamma diversity and metacommunity size and compare them to theoretical expectations. In both analyses we found that augmenting spatial metacommunity identification with historical geographical proximity results in stronger associations with biodiversity patterns (beta and gamma diversity) than when using only current-day habitat or watershed information.

Comparison of the coexistence pattern of mangrove macrobenthos between natural and artificial reforestation.

The abandoned pond-to-mangrove restoration project provides greater advantages than tidal flats afforestation in restoring mangrove ecosystem services and will be the primary method for mangrove restoration in the future. The existing methods for abandoned pond-to-mangrove restoration include artificial restoration through 'dike-breaking, filling with imported soil and tree planting' and natural restoration through 'dike-breaking and natural succession'. However, little is known about which restoration strategy (natural or artificial restoration) provides more benefits to the biodiversity of mangrove macrobethos. Given a prevailing view suggested that artificial restoration should be the preferred approach for accelerating recovery of biodiversity and vegetation structure in tropical regions, we hypothesised higher macrobenthic biodiversity and more complex community structure in artificial restoration than in natural restoration. To test this hypothesis, macrobenthic biodiversity and ecological processes were monitored in a typical abandoned pond-to-mangrove area of Dongzhaigang Bay, China, where artificial and natural restoration methods were used concurrently. Differences in macrobenthic biodiversity, community structure and ecological processes were compared using diversity indices, complex network analysis and null models. Similar species composition and ecological niche overlap and width among macrobenthos were observed at artificial and natural restoration sites. The biotic heterogeneity and interaction among macrobenthos were higher at the natural restoration sites than at the artificial restoration sites. Macrobenthos community assembly at natural and artificial restoration sites was both determined by deterministic processes, with environmental filtering dominating, which explained 52% and 54% of the variations in macrobenthic community structures respectively. Although our findings did not validate the research hypothesis, higher biotic heterogeneity and species interaction among macrobenthos could support natural restoration as the primary method for abandoned pond-to-mangrove projects, because it is a nature-based solution for mangrove restoration.

Through the green mosaic: Different tropical vegetation types have complementary effects on parasitoid diversity and biological control in organic agroecosystems

Land use change threaten global biodiversity, impacting ecosystem services, especially in diverse tropical regions. Yet, biodiversity conservation does not guarantee ecosystem services provision, given species' variable responses to local and landscape factors. Here, we evaluate how the landscape and local resources affect parasitoid diversity and aphid biological control in a tropical organic crop. Locally, we compared parasitoid communities within the crops and on adjacent non-crop plant strips and evaluated the effect of flower resource abundance on parasitoid diversity. At the landscape scale, we analyzed the effect of natural areas and their specific vegetational types on parasitoid diversity and the scale of these effects. Finally, we evaluated the relationship between biodiversity and biological control. Non-crop plant strips had higher parasitoid species richness and abundance than the crops, but similar species composition. Flower resource abundance in the non-crop strips negatively affected parasitoid richness. Natural areas in the landscape benefited parasitoid richness at a close range (0.42 km) and reduced parasitoid abundance at a wider scale (1.75 km). Forests and savannas increased parasitoid richness and reduced abundance, while grasslands drive parasitoid abundance and may disrupt species richness. Savannah areas, where trees and grasses coexist boosted the positive effects of forests on species richness and of grasslands on abundance. Parasitoid species richness benefited biological control exclusively in communities with intermediate and high number of parasitoid species. Our findings show that natural vegetation types with different wood densities have complementary effects in parasitoid diversity in tropical agroecosystems and represent a useful baseline for development of management and zoning plans.

Medium and large-sized mammals in human-dominated landscape of the former Dhidhessa wildlife sanctuary, Western Ethiopia

Abstract Assessment of medium- and large-sized mammals’ species diversity, abundance, distribution, and habitat association is necessary to promote their conservation measures. The study was conducted in the former Dhidhessa wildlife sanctuary (FDWS), to assess the medium- and large-sized mammals’ composition, distribution, and diversity. Transect lines were used to collect the data. A total of 1,146 ± 91 individuals belonging to 25 species, seven orders, and 14 families were recorded. Among these, 607 ± 186.5 (52.97%) were recorded during the wet season, whereas 539 ± 144.5 (47.03%) during the dry season. The order Carnivora was the most diverse one, followed by Artiodactyla and Primates, respectively, while Rodentia, Hyracoidea, Tubulidentata, and Lagomorpha were the least diverse orders. Olive baboon (Papio anubis) was the most abundant species (19.2%), followed by Hippopotamus (Hippopotamus amphibious) (17.63%) and Vervet monkey (Chlorocebus aethiops) (13.18%). Species diversity was higher in the savanna-wooded than in the riverine forest during both the wet (H’ = 2.72, Fisher’s alpha = 6.33) and dry (H’= 2.79, Fisher’s alpha = 6.26) seasons. Species evenness was higher in the savanna-wooded habitat than in the riverine forest habitat during both the wet (J’ = 0.87 and J’ = 0.77, respectively) and dry (J’ = 0.9 and J’ = 0.80, respectively) seasons. The highest similarity in species composition was between the wet and dry seasons in the riverine forest habitat (SI = 85.58%). The lowest similarity was recorded between the dry and wet seasons of the riverine forest and the wet season of the savanna wooded habitat (SI = 45.46% and SI = 46.49%, respectively). The study suggests that mammals are at risk of anthropogenic factors in the area. So, an urgent conservation measure that involves the participation of the local community has paramount significance for the sustainable conservation of mammals in the former Dhidhessa wildlife sanctuary.

Transport and preservation of calcareous and organic-walled dinoflagellate cysts off Cape Blanc (NW africa) in relation to nepheloid layers

Our understanding of dinoflagellates' present-day and past ecology is limited due to the scarcity of data on the transport of dinoflagellate cysts in oceanic environments. Previous studies have shown that lateral transport affects the source-to-sink trajectory of cysts in the very productive region off Cape Blanc (NW Africa). Unsolved questions remain, such as: how far these cysts can be advected, whether the cyst sources vary over time and whether lateral transport is a permanent feature or restricted to individual events. To fill these gaps and assess the role of nepheloid layers on the lateral transport and preservation of dinoflagellate cysts, new data on dinoflagellate cyst distributions in the water column and sediments along a land-sea transect were obtained.Samples were collected in November 2018 along a shelf break-offshore transect during intense upwelling, notably, within and between the nepheloid layers. The composition and abundance of cysts with organic walls in the water column and surface sediments were studied. Moreover, the distribution of calcareous cysts was also analysed in the water samples, using non-destructive acid-free preparation methods. The records were dominated by empty cysts, but no clear indications that these originated from local resuspension of older sediments were observed. Clustering, principal component analysis and redundant discriminant analysis were used to compare cyst assemblages in the water column and surface sediments, and environmental conditions in the upper water column. The strong similarity in species composition of water samples collected in the active upwelling region to those collected from the more onshore parts of the Benthic Nepheloid Layer (BNL), upper Intermediate Nepheloid Layer (INL) (∼1000 m depth) and lower INL (∼2200 m depth) indicated that lateral transport of cysts within these NLs occurred until about ∼110 km from the shelf break. Cyst assemblages from above and below these NLs showed significantly different taxa composition reinforcing the role of NLs in the lateral advection of cysts. In the more offshore stations, vertically similar cyst assemblages were observed in the same station, independent of the sample depth, within or between the NLs, which supported that at these stations vertical transport was the dominant process influencing cyst assemblages. Consequently, the cyst signal in sediments off Cape Blanc may be affected both by horizontal transport of allochthonous cysts and vertical deposition of locally-produced cysts, particularly in the more offshore stations (>2000 m depth). Despite lateral transport and possible species-specific preservation effects, horizontal distributions of most cyst taxa in the water column and the surface sediments could be explained to a great extent by the main environmental gradients in the upper water column. This agrees with observations made in other regions, and reinforces that dinoflagellate cysts as good proxies to reconstruct past environmental conditions in offshore environments. New data on dinoflagellate cyst distribution, transport and accumulation patterns in deep environments off Cape Blanc may be useful for interpreting past environmental signals in the region. This is particularly relevant regarding calcareous cysts, as information on their distribution and ecology is very scarce. The present work contributes to a better understanding of the dispersal patterns of dinoflagellate cysts in the deep ocean, highlighting the significant role played by nepheloid layers in this process and thus on the dinoflagellate cyst signature in deep-sea sediments.

Temporal changes in species richness, composition and diversity of the forest stands over 36-year period, Western Himalaya, India

This study investigates the temporal changes in species richness, composition, and diversity in forest stands spanning a 36-year period in the Western Himalaya. Four forest stands (subtropical Sal-forest, subtropical Chir-pine forest, temperate Banj-oak forest, and temperate Mixed-oak Forest) studied in 1980–1981 were resurveyed using similar methods. Over the past 36 years, 19 new species have been recorded in the four stands; eight species planted and eleven species naturally introduced. Dominant species continue to dominate in the forest stands. However, their contribution to the total tree density has decreased over the year. Species diversity, richness, and evenness increased in all forests except the Sal stand. Three species were newly introduced in the Sal stand, seven in the Chir-pine stand, eight in the Banj-oak stand, and seven in the Mixed-oak stand. The highest similarity in species composition was observed in the Sal stand (59 %), followed by the mixed-oak stand (57 %), Chir-pine stand (50 %), and Banj-oak stand (47 %). The results indicate an increase in tree density across all sites, with the Mixed-oak forest exhibiting the highest increase in tree density due to least biotic pressure. The findings of this study, based on two-time composition datasets, provide valuable insights into forest dynamics, supporting biodiversity conservation and management planning.

Abandonment or biomass production? Phytodiversity responses to land-use changes of semi-natural grasslands in northern Europe

European semi-natural grasslands are hotspots for biodiversity and important for the provisioning of multiple ecosystem services, but their extent has declined considerably during the past century. Increasing demands for agricultural and forest biomass risk causing further loss of grasslands, raising concern about a goal conflict between climate mitigation and biodiversity conservation. This study focused on the loss of semi-natural grasslands in a mixed farm-forest landscape in southern Sweden by comparing plant diversity in grasslands with continuous grazing regimes to recently abandoned grasslands, improved grasslands (sown leys), and afforested grasslands. Compared to actively grazed grasslands, grasslands where grazing had been abandoned showed a lower plant species richness and fewer plant species of conservation concern, but similar species composition. In contrast, both improved and afforested grasslands showed >50 % lower species richness than abandoned and grazed grasslands, with profoundly different species composition. The dissimilarity in plant diversity between sites was primarily driven by the replacement of species (turnover), and trait-based analyses indicated that environmental filtering of light, management, and nutrient requirements of plants shaped the community differences. Furthermore, an increased cover of semi-natural grassland around the sites positively related to plant species richness and diversity, while an increased cropland coverage around the sites showed a negative relationship. Our results emphasize the importance of integrated land-use strategies that prioritize biodiversity conservation in mixed farm-forest landscapes, such as restoration of semi-natural grasslands and strategic planning of biomass production to avoid serious biodiversity losses.

Vertical distribution patterns of macrofauna in the sediments of the Arctic cross-shelf trough and adjacent shelf - Similarities and differences from lower latitudes

Vertical distribution of macrobenthos in sediments remains poorly studied; data from higher latitudes are especially scarce. At the same time, it is believed to contain important information about communities that should not be neglected. Hence, our main objectives are to study the peculiarities of macrobenthos vertical patterns in the Arctic and to find out features specific to this region. For this, 24 stations were sampled in 2019 aboard the R/V “Akademik Tryoshnikov” while drifting in the North Barents Sea and along a transect south-west of the Franz Joseph Land. Sediments were obtained using a box corer; afterwards, subsamples were taken by a tube corer and cut into vertical sub-cores. Three to four strata (depending on biotope) characterized by similar species composition and abundance were distinguished. No direct relation between the increase in species richness and the complication of vertical structure was found. Avoiding competition through dwelling in different layers at one station was observed in some groups of closely related species. Factors playing important roles in determining infaunal properties depended on the layer. The thin upper layer played a more important role in terms of species number and abundance as compared to lower latitudes. However, the most abundant and widespread polychaete species Spiochaetopterus typicus penetrated down to 30 cm. It formed vertical distribution patterns in deeper sediment layers at most stations, including facilitating penetration into deep layers for other species. The exception was stations dominated by large maldanid polychaetes. Such a vertical pattern, with a particularly large share of species richness and abundance concentrated in the several upper cm combined with the very deep penetration of a few species, is likely typical of the Eurasian Arctic shelf.

Structure and Carbon Capture of a Temperate Mixed Forest across Altitudinal Gradients in Northern Mexico

Maximizing the ability of forests to capture carbon (C) from the atmosphere is critical to mitigate global warming. This is a daunting task as the warming climate is adversely affecting forests with increasing forest fires, pests, and a shift to tree species that can tolerate the newer climate conditions. A large (about 1 million hectares) mixed pine–oak forest in Chihuahua, Mexico, was characterized via 151 plots to determine its floristic diversity and biomass with respect to species, age (tree diameter), and at four altitudinal gradients equally distributed between 1850 and 2850 masl. Higher richness and diversity were found at the altitudinal gradient of 2101–2350 m with 36 species and a Shannon’s index (H’) of 2.95, and the lowest at 2601–2850 m with 17 species and H’ of 2.37. The Sorensen Index showed a high similarity in species composition, with the highest values (71% to 79%) obtained for the 2351–2600 gradient. C storage of the mixed forest increased with altitude from 7.85 Mg C ha−1 in the 1850–2100 m gradient to 14.82 Mg C ha−1 in the 2601–2850 m gradient. C storage in oak decreased with altitude while C storage of pine increased. Viable strategies to maximize C storage under changing climate conditions are discussed, including social safeguards and sale of carbon credits.