Wet Habitats Research Articles

Early Hominin Paleoenvironments and Habitat Heterogeneity

Environmental changes are often cited as the main driver of hominin evolutionary events, including major adaptive events such as bipedalism. Thus, researchers are particularly interested in the paleoenvironment of early hominins. The previous prevailing idea that hominins originated in expanding savannas is contradicted by the association of the earliest hominins with more closed and mesic (i.e., moderately wet) habitats. The Pliocene homi-nins that followed lived in a variety of habitats characterized by high levels of heterogeneity and permanent sources of water. This article reviews what we know of Mio-Pliocene hominin paleoenvironments, discusses the nature of the observed habitat heterogeneity associated with early hominins and implications for hominin paleoecology, and considers the challenges we face in showing a causative relationship between environmental change and major evolutionary events.

Precipitation, solar radiation, and their interaction modify leaf hydraulic efficiency-safety trade-off across angiosperms at the global scale.

In theory, there is a trade-off between hydraulic efficiency and safety. However, the strength and direction of this trade-off at the leaf level are not consistent across studies, and habitat climate may impact this trade-off. We compiled a leaf hydraulic efficiency and safety dataset for 362 species from 81 sites world-wide, with 280 paired observations of both traits, and tested whether climate was associated with departure from the proposed trade-off. The leaf hydraulic efficiency-safety trade-off was weak (R2 = 0.144) at the global scale. Mean annual precipitation and solar radiation (SR) modified the trade-off. Species from dry and high SR habitats (e.g. desert and tropical savanna) were generally located above the trade-off line, indicating that these species tended to have higher leaf hydraulic safety and efficiency than species from wet habitats with low SR (e.g. subtropical monsoon forest and montane rainforest), which were located below the trade-off line. Leaves with high vein density, dry leaf mass per area, and osmotic regulation enhanced safety without compromising hydraulic efficiency. Variation in the hydraulic efficiency-safety trade-off at the leaf level likely facilitates plant survival in specific habitats and allows for a more nuanced view of leaf hydraulic adaption strategies at the global scale.

Peatland vegetation of the Syra Pogonia massif of the Rivneskyi Nature Reserve (Polissia, Ukraine): ecological characteristics

Background. Peat bog complexes are self-sufficient ecosystems in which unique microclimatic conditions leading to a significant diversity of valuable plant communities are formed. Such communities are sensitive to the effects of climate change or any anthropogenic intervention. The lack of reliable information on their distribution on the territory of the Syra Pogonia peat-bog massif of the Rivnenskyi Nature Reserve necessitates a detailed study of the bog vegetation. Therefore, the purpose of the work was to classify the community of peatland vegetation of the Syra Pogonia massif and to determine the features of their syntaxonomic and ecological differentiation for further development of environmental management strategies. Materials and Methods. The study of the peculiarities of peatland vegetation was conducted on transects that represent the variety of local conditions of the complex system. A total of 141 relevés were analysed using the Braun–Blanquet method. The material was analysed using TURBOVEG 2.79 and JUICE 7.0.83 software. Vegetation units were separated using the method of two-factor indicator species analysis (TWINSPAN). Diagnostic species of syntaxa were determined by the fidelity coefficient phi, the fidelity threshold for which was > 25 %. The statistical significance of the phi coefficient was determined with the Fisher’s test at P < 0.001. The DCA-ordination method was used to identify an ecological differentiation of units. Results. Peatland vegetation of the Syra Pogonia massif of the Rivnenskyi Nature Reserve was analysed. We identified 7 associations belonging to 6 alliances, 6 orders and 4 classes and compiled a vegetation syntaxonomic scheme. The leading factor of ecological differentiation of community is humidity of the area. The greatest diversity is inherent in mesotrophic areas, rare species are found and grouped according to diffe­rent ecological conditions. The species composition of 7 associations includes 79 plant species, of which 65 are vascular and 14 are bryophytes. Using methods of phytosociological analysis, we established that the distribution of community in multi-dimensional space of ecological factors occurs under the conditions of their complex action. At the same time, changes in the humidity regime are of crucial importance for the selected syntaxa (Andromedo polifoliae-Sphagnetum magellanicі). The results of the phytoindicative analysis proved that the associations identified on the territory of the Syra Pogonia peat-bog complex are acidophilic in terms of acidity, and oligotrophic in terms of the requirements for the content of nutriens. Conclusions. As orders, and result of the analysis of relevés, 7 associations, which belong to 6 alliances, 6 orders and 4 classes were selected. Based on the results of the dataset analysis, a vegetation classification scheme was compiled. As a result of the cluster analysis of 7 associations, a significant difference between communities of watered and wet habitats was revealed. We established that the differentiation of the vegetation on the territory of the peat massif of Syra Pogonia mainly depends on the change in the moisture regime.

Divergent hydraulic and gas exchange strategies in two closely-related Salix species

Abstract Understanding the physiological mechanisms that trees employ to cope with drought-induced mortality is crucial for predicting their responses to a changing climate. Salix species exhibit distinct habit distributions, with Salix babylonica growing in wet habitats and S. matsudana growing in relatively dry habitats. The objective of this study was to compare hydraulic and gas exchange traits between these two closely-related Salix species with contrasting natural habitats. S. matsudana had lower photosynthesis (Amax), lower stomatal conductance (gs), and lower stem and leaf hydraulic conductance, but it exhibited higher water use efficiency (WUEi), higher hydraulic safety and wider leaf-to-stem vulnerability segmentation as well as narrower, shorter and denser conduits and a lower ratio of leaf area to sapwood area than S. babylonica. These findings suggest that variation in hydraulic vulnerability and gas exchange traits enable closely-related Salix species to adapt to different habitats.

Investigating Thresholds for Drought Resistance in Floodplain Forest Tree Species

Abstract Anthropogenic and climatic variables combine to alter river flow regimes worldwide, which can influence shifts in species composition. Exacerbation of drought events in southeastern United States floodplains may have varying impacts on survival and regeneration of high bottomland, low bottomland, and swamp forest species, causing distribution shifts between these forest types. We tested 7-month-old seedlings of the swamp species water tupelo (Nyssa aquatica), Ogeechee tupelo (Nyssa ogeche), and pop ash (Fraxinus caroliniana), and the low bottomland species overcup oak (Quercus lyrata) and water hickory (Carya aquatica) in a controlled experiment with increasing drought treatment. We compared timing to 95% mortality and determined lethal soil moisture thresholds for species. Swamp species were no more vulnerable to mortality under increasing drought than low bottomland hardwood species found in neighboring wet floodplain habitats, suggesting that duration of drought may not be a main driver of compositional shifts between these forests. Study Implications: Natural flows of river systems around the world have been altered by humans and a changing climate. Increased intensity of drought events can affect tree species growing adjacent to rivers and influence their ability to reproduce, thus changing the composition of floodplain forests. We tested the drought tolerance of three swamp species accustomed to frequent flooding and two low bottomland hardwood species accustomed to less frequent flooding to see which species might be more affected by drought. We observed no differences between these two groups, suggesting that greater flood tolerance may not imply greater drought intolerance.

Home on the range: A multi-isotope investigation of ungulate resource partitioning at Ashfall Fossil Beds, Nebraska, USA

During the Miocene (ca. 23.0–5.3 Ma), North America's Great Plains were a broad mosaic of savanna-woodlands inhabited by a diverse ungulate fauna. We investigated resource partitioning among ungulates at Ashfall Fossil Beds State Historical Park (henceforth “Ashfall”) in north-central Nebraska to establish how taxa shared the landscape. This mid-Miocene (11.86 ± 0.13 Ma) site preserves a watering-hole filled with volcanic ash that entombed hundreds of skeletons of medium- and large-bodied ungulates. We analyzed carbon (δ13C), oxygen (δ18O), and strontium (87Sr/86Sr) isotopes in enamel from seven species: the rhinoceros Teleoceras major (n = 13); three horses (Cormohipparion occidentale, Pliohippus pernix, and Pseudhipparion gratum; n = 3 each); two camels (Procamelus grandis and Protolabis heterodontus; n = 1 each); and one small ruminant artiodactyl (Longirostromeryx wellsi; n = 3). Carbon isotope data indicate that all seven ungulates foraged in open habitats dominated by C3 plants (enamel δ13CVPDB range from −9.6‰ to −6.9‰) with little to no evidence of C4 plant consumption. The overall range in δ18OVPDB values is ca. 6‰ (−7.6‰ to −1.3‰), while the range for 87Sr/86Sr is narrow (0.70864–0.70898). Horses have significantly higher δ18O and 87Sr/86Sr than T. major, which we suggest indicates horses foraged in relatively dry habitats, while T. major inhabited wet habitats with different strontium sources. Both camels isotopically resemble horses, and Longirostromeryx wellsi has intermediate 87Sr/86Sr and wide-ranging δ18O values. Plotting Teleoceras and co-occurring ungulates in a model that tests for semi-aquatic behavior using δ18O suggests that T. major from Ashfall was semi-aquatic; ecology and behavior may have varied among Teleoceras species living in different places at different times. This study exemplifies how 87Sr/86Sr data complement δ13C and δ18O analyses when reconstructing ancient environments; they can provide nuanced ecological information even in landscapes with homogeneous bedrock.

First evidence of plastics in coypu (Myocastor coypus)'s platforms.

Platforms are structures built by coypus for various purposes, such as reproduction, resting, and thermoregulation. In a coastal wetland of central Italy, during a study aimed at investigating the characteristics of coypu's platforms, it was recorded, for the first time worldwide, the presence of plastic in these structures. Through a transect survey, we censused 83 platforms, among which three (3.61%) were found with presence of macro- and megaplastics (polystyrene, polypropylene, and low-density polyethylene in film form; polyester, polyamide, and expanded polystyrene in fragments). Through the FTIR spectra, it was possible to highlight the degradation of the polymeric materials. To stimulate possible in-depth investigations at the level of the food chain (e.g., coypu predators, including canids) in wet habitats, we discussed possible causes and implications of plastic presence in coypus' nest structures.

Influence of habitat on fine-scale space use by brown lemmings (Lemmus trimucronatus) in the High Arctic.

Space use by small mammals should mirror their immediate needs for food and predator shelters but can also be influenced by seasonal changes in biotic and abiotic factors. Lemmings are keystone species of the tundra food web, but information on their spatial distribution in relation to habitat heterogeneity is still scant, especially at a fine scale. In this study, we used spatially explicit capture-recapture methods to determine how topography, hydrology, vegetation, and soil characteristics influence the fine-scale spatial variations in summer density of brown lemmings (Lemmus trimucronatus). Lemmings were monitored throughout the summer in wet and mesic tundra habitats and in a predator exclusion grid, which was also located in mesic tundra. We found that in wet tundra, lemming densities were higher at sites with a rugged topography dominated by hummocks, but only during snow melt. In both mesic tundra sites, lemming densities were higher in sites with poor drainage and low aspect throughout the summer. We found no clear association between lemming densities and any tested vegetation or soil variables. Overall, hydrology and topography appear to play a dominant role in small-scale space use of brown lemmings with a secondary role for predator avoidance and food plant abundance.

Elms (Ulmus L.) in the Branch “Myrhorod Forestry” of the State Specialized Forest Enterprise “Forests of Ukraine”

Introduction Elms are spread in forests, landscaping settlements, and protective forest belts. After several waves of elm mortality from Dutch elm disease (DED) in the 20th century, individual populations recovered or formed resistant hybrids. However, epiphytoties of bacterial and fungal diseases sometimes develop, particularly due to pathogen vectoring by bark beetles. In Ukraine, the spread of elms and their damage by different causes are relatively poorly investigated. This research aimed to discover the features of Ulmus sp. distribution by stand origin, age, and forest site condition in the forest fund of the Branch “Myrhorod Forestry”. Materials and Methods The data as of 2010 and 2017 on the forest fund of enterprises belonging to the Branch “Myrhorod Forestry” of the State Specialized Forest Enterprise “Forests of Ukraine” were selected from the database of Ukrainian State Forest Management Planning Association “Ukrderzhlisproekt” using SQL-query and converted to the *.xls files. Area distribution by types of forest site conditions was assessed following the Ukrainian school of forest typology. Such distributions for the entire area covered with forest vegetation, for subcompartments with elms in the stand composition, and with elms as the dominant species were compared for various elm species and stand origins, using c2-test. The percentages of stand areas of different origins and elm species in 2010 and 2017 were compared using z-test in the two proportions comparisons. The data for subcompartments with various elms as the dominant species and as a part of stands composition have been analyzed by 10-year age classes for different origins (natural and planted). The proportion of the stand area of each 10-year age class was assessed for each set of subcompartments. Then the proportion of the stands’ area, which survives up to a certain age, was evaluated. Results and Conclusions In the Branch “Myrhorod forestry”, an area of natural stands with Ulmus sp. as the dominant species for 2010–2017, and the proportion of U. minor has significantly increased. The most dramatic decrease in the survival rate of all elm species of natural stands occurred in the VI age class and planted stands in the V age class. Respective natural and planted stands were formed in the 1960s and 1970s when the peak of DED occurred in many regions. In the Branch “Myrhorod Forestry”, U. minor prefers moist fertile forest site conditions. U. laevis grows mainly in moist forest site conditions, U. pumila occurs in dry to wet habitats, U. glabra is present only in natural stands and absent in plantations. As part of stand composition, the same elm species grow in a wider range of forest site conditions than elms as the dominant species. 2 Figs., 8 Tables, 31 Refs.

An overview of the drivers of performance in nonbreeding Nearctic–Neotropical migratory songbirds

ABSTRACT Developing conservation and recovery strategies for Nearctic–Neotropical migratory songbirds requires key research because population-limiting factors remain unknown for many species. In particular, the stationary nonbreeding period (sometimes referred to as overwintering) encompasses 6–8 months of the full annual cycle. We conducted a systematic review to assess what is known about the factors that influence individual-level performance (i.e., fitness proxies or indicators of self-maintenance) of Nearctic–Neotropical migratory songbirds during the stationary nonbreeding period. We focused on the metrics of apparent survival, persistence, and body condition (mass-related) indices. We found that 51 of 125 migratory Passeriformes species’ performance has been studied in 57 studies during the nonbreeding period. However, most species appear in only one study; thus, knowledge is skewed toward 3 species appearing in ≥ 10 studies. Body condition indices were the most studied group of metrics and apparent survival was the least studied. Habitat type, food availability, and precipitation were studied much more than other drivers, such as disease and predation. The most studied driver of nonbreeding performance was habitat type. Evidence was found among these studies that suggest that natural habitat types, wetter habitats or precipitation, and high availability of food may positively influence body condition, apparent survival, and persistence. Significant knowledge gaps remain that, if filled, could inform conservation strategies, especially for 59.2% of Passeriformes that are Nearctic–Neotropical migratory species and for areas of the nonbreeding range.

First report of adult †Burmecaelidae with description of a new species from mid-Cretaceous Burmese amber (Orthoptera: Caelifera)

An adult male of †Burmecaelinus armis Uchida, Husemann and Kotthoff, 2023, and a newly identified genus and species †Moban zhengzheminigen. et sp. nov., are reported based on two well preserved adult specimens from mid-Cretaceous Burmese amber. †M. zhengzheminigen. et sp. nov. can be distinguished by following characters: body with irregular small dark spots; pronotum is in uniform width, with dispersed shallow dents and two distinct transverse sulci, posterior angle is protruding forward; posterior thoracic process is shark-tooth shaped; pronotal disc without four longitudinal carinae; tip of apical spurs on metatibia not curved. The morphological diagnosis of the family †Burmecaelidae was emended, and the posterior thoracic process of adult †Burmecaelidae species is possibly specialized scutellum. We proposed a hypothesis that this extinct family was a sister group of Tridactyloidea and species of †Burmecaelidae lived in humid environment near water and had affinity for wet and semi-aquatic habitats.

Evolutionary reversal of physical dormancy to nondormancy: evidence from comparative seed morphoanatomy of Argyreia species (Convolvulaceae).

Argyreia is the most recently evolved genus in the Convolvulaceae, and available information suggests that most species in this family produce seeds with physical dormancy (PY). Our aim was to understand the evolution of seed dormancy in this family via an investigation of dormancy, storage behaviour, morphology and anatomy of seeds of five Argyreia species from Sri Lanka. Imbibition, germination and dye tracking of fresh intact and manually scarified seeds were studied. Scanning electron micrographs and hand sections of the hilar area and the seed coat away from the hilar area were compared. Scarified and intact seeds of A. kleiniana, A. hirsuta and A. zeylanica imbibed water and germinated to a high percentage, but only scarified seeds of A. nervosa and A. osyrensis did so. Thus, seeds of the three former species are non-dormant (ND), while those of the latter two have physical dormancy (PY); this result was confirmed by dye-tracking experiments. Since >90% of A. kleiniana, A. hirsuta and A. zeylanica seeds survived desiccation to 10% moisture content (MC) and >90% of A. nervosa and A. osyrensis seeds with a dispersal MC of ~12% were viable, seeds of the five species were desiccation-tolerant. A. nervosa and A. osyrensis have a wide geographical distribution and PY, while A. kleiniana, A. hirsuta and A. zeylanica have a restricted distribution and ND. Although seeds of A. kleiniana are ND, their seed coat anatomy is similar to that of A. osyrensis with PY. These observations suggest that the ND of A. kleiniana, A. hirsuta and A. zeylanica seeds is the result of an evolutionary reversal from PY and that ND may be an adaptation of these species to the environmental conditions of their wet aseasonal habitats.

Evolving landscape and cultural change during the Middle Palaeolithic in Southeast Zagros (Iran): Insights from a micromammal assemblage

The Iranian Zagros is a remarkable zone to study Middle and Upper Palaeolithic human occupations and Tang-e Shikan (Arsanjan) is a strategic cave site which archaeological evidence can be taken as a proxy for the southeast portion. Micromammals have been extensively used as palaeoecological indicators and here we use the assemblage from Tang-e Shikan to infer the landscape and environment that framed and arguably triggered cultural change. A thorough taphonomic analysis was undertaken prior to any interpretation. Fourteen taxa have been identified: two “insectivores” s.l., nine rodents, two lagomorphs, and unidentified chiropterans. The remains would be the digestion by-products of a category 5 opportunistic predator: either an avian raptor or a mammalian carnivore. Our results show that shrubland and grassland dominated the distribution of habitats in the area during the Middle Palaeolithic (MP), followed by moderate rocky, desert, and steppe components, and sparse patches of woodland. The younger period of the MP occupation (NMP: ∼55-45 ka BP) would be somewhat wetter than the older period (OMP: ∼70-55 ka BP). Within a general environmental stability, slight changes between OMP and NMP are reasonably correlated with a shift in certain cultural patterns, as the use of a water reservoir and a stone drainage system during the OMP or the increase of hunting and moderate change in lithic technology and raw material acquisition during the NMP. Our environmental inferences are further supported by palynological data and match a regional trend towards wetter habitats in moving from the MP to the present.

Large‐scale remote sensing analysis reveals an increasing coupling of grassland vitality to atmospheric water demand

AbstractGrasslands provide important ecosystem services to society, including biodiversity, water security, erosion control, and forage production. Grasslands are also vulnerable to droughts, rendering their future vitality under climate change uncertain. Yet, the grassland response to drought is not well understood, especially for heterogeneous Central European grasslands. We here fill this gap by quantifying the spatiotemporal sensitivity of grasslands to drought using a novel remote sensing dataset from Landsat/Sentinel‐2 paired with climate re‐analysis data. Specifically, we quantified annual grassland vitality at fine spatial scale and national extent (Germany) from 1985 to 2021. We analyzed grassland sensitivity to drought by testing for statistically robust links between grassland vitality and common drought indices. We furthermore explored the spatiotemporal variability of drought sensitivity for 12 grassland habitat types given their different biotic and abiotic features. Grassland vitality maps revealed a large‐scale reduction of grassland vitality during past droughts. The unprecedented drought of 2018–2019 stood out as the largest multi‐year vitality decline since the mid‐1980s. Grassland vitality was consistently coupled to drought (R2 = .09–.22) with Vapor Pressure Deficit explaining vitality best. This suggests that high atmospheric water demand, as observed during recent compounding drought and heatwave events, has major impacts on grassland vitality in Central Europe. We found a significant increase in drought sensitivity over time with highest sensitivities detected in periods of extremely high atmospheric water demand, suggesting that drought impacts on grasslands are becoming more severe with ongoing climate change. The spatial variability of grassland drought sensitivity was linked to different habitat types, with declining sensitivity from dry and mesic to wet habitats. Our study provides the first large‐scale, long‐term, and spatially explicit evidence of increasing drought sensitivities of Central European grasslands. With rising compound droughts and heatwaves under climate change, large‐scale grassland vitality loss, as in 2018–2019, will thus become more likely in the future.

Factors affecting severity of wildfires in Scottish heathlands and blanket bogs

Temperate heathlands and blanket bogs are globally rare and face growing wildfire threats. Ecosystem impacts differ between low and high severity fires, where severity reflects immediate fuel consumption. This study assessed factors influencing fire severity in Scottish heathlands and blanket bogs, including the efficacy of the Canadian Fire Weather Index System (CFWIS). Using remote sensing, we measured the differenced Normalised Burn Ratio at 92 wildfire sites from 2015 to 2021. We used Generalised Additive Mixed Models to investigate the impact of topography, habitat wetness, CFWIS components and 30-day weather on severity. Dry heath exhibited higher severity than wet heath and blanket bog, and slope, elevation and south facing aspect were positively correlated to severity. Weather effects were less clear due to data scale differences, yet still indicated weather's significant role in severity. Rainfall had an increasingly negative effect from approximately 15 days before the fire, whilst temperature had an increasingly positive effect. Vapour Pressure Deficit (VPD) was the weather variable with highest explanatory value, and predicted severity better than any CFWIS component. The best-explained fire severity model (R2 = 0.25) incorporated topography, habitat wetness wind and VPD on the day of the fire. The Drought Code (DC), predicting organic matter flammability at ≥10 cm soil depth, was the CFWIS component with the highest predictive effect across habitats. Our findings suggest that wildfires in wet heath and blanket bogs are typically characterised by low severity, but that warmer, drier weather may increase the risk of severe, smouldering fires which threaten peatland carbon stores.

التنوع البيولوجي وتنوع الكائنات الحية الدقيقة لنباتات الدوكو المتوطنة في موقع النمو الرئيسي الرطب والجاف في جامبي ، إندونيسيا

دوكو Duku نباتات متوطنة في مقاطعة جامبي بإندونيسيا. كانت تنتشر وتنمو جيدًا في الطمي على طول ضفاف الأنهار ، لكنها عانت مؤخرًا من تفشي مرض الموت المفاجئ على مدار العقود الماضية. كان هذا الوضع سائدًا منذ الفيضانات المتكررة بسبب استنفاد مناطق الغابات في أعلى المنبع. بما أن السبب هو العفن المائي Phytophthora palmivora ، فقد كان من المفترض أن يحدث مرض الموت المفاجئ في المناطق الرطبة فقط ، ولكن في الواقع ، ينتشر المرض في المناطق الجافة أيضًا. هذه الحقيقة قادتنا للبحث عن عوامل بيولوجية أخرى في التربة بالمحيط الجذري للنباتات في الموائل الرطبة والجافة. أخذت العينات من المحيط الجذري لنباتات دوكو المريضة والصحية في العديد من المناطق الرسوبية لنهر باتانغ هاري التي تمثل الموائل الرطبة والجافة. أشارت الى أن المجتمع الميكروبي في التربة في الموائل الجافة والرطبة هي مجتمعات مايكورايزا (mycorrhiza) والبكتيريا والفطريات. أظهرت الوفرة النسبية للميكروبات في الموائل الجافة والرطبة في النباتات الصحية والمريضة أنواع متنوعة. ففي النباتات الرطبة للصحة ، كانت الوفرة النسبية كالآتي: 33.33 ٪ ٍSclerocytis، و Gigaspora 33.34 ٪ ، و Glomus 33.33 ٪. في النباتات المصابة بالموائل الرطبة ، كانت الوفرة النسبية للمايكورايزا: 66.67 ٪ ٍSclerocytis ، Glomus 33.33 ٪ ، وغياب Gigaspora. تم العثور على مجموعة البكتيريا لتكون الأكبر عند 70،49 ٪ في الموائل الجافة و 72.13 ٪ في الموائل الرطبة. أماالمجموعة الفطرية فكانت 14،08 ٪ في الموائل الجافة و 16.39 ٪ في الموائل الرطبة. أظهرت المايكورايزا أصغر نسبة في جذور نباتات Duku. أظهرت النتائج وجود ارتباط سلبي لل VAM مع النيتروجين ، و والفسفور في المحيط الجذري. أما وجود Glomus sp كان ارتباطه ايجابيا مع بوتاسيوم التربة.

Reconstructing the Holocene Development of Lake Chaika as an Example of Wetland Formation within the Sand Spit Environment Dynamics: A Case Study from the Curonian Spit, Southeastern Baltic, Russia

The paper provides original data that shed light on the formation dynamics of Lake Chaika, which is situated in the central part of the Curonian Spit and is the only large water body in the sand spits of the southeastern Baltic. Based on the multi-proxy approach, incl. investigation of the lithological structure of the bottom sediment cores, loss-on-ignition analysis, diatom analysis, study of macrofossil remains, and radiocarbon dating, we revealed that Lake Chaika was formed already in historical time, around 200 years ago. Before this period, the lake kettle, presumably, has not submerged during the Littorina transgressions, enabling the terrestrial development of the ecosystems on the moraine protrusion. During the mid-late Holocene (6700–150 cal BP), this depression was occupied by the peat-forming fen and alder carr communities. The peat deposits are separated from the overlying layers of gyttja by the thin sand horizon. We consider it a time marker for the so-called “sand disaster”, which occurred on the territory of the Curonian Spit in the 18th century (≈1700–1800). The change in the hydrological regime of the lake launched the ecosystem shifts during the last two centuries: from the water body to a wetland and vice versa. It is stated eight formation phases of the lake’s ecosystem: the terrestrial development without wet habitats (8900–6700 cal BP), the period of alder carrs (6700–3400 calBP), the sedge fen period (3400–450 cal BP), the period of inundated forest (1500–1700 AD), the “sand disaster” period (1700–1800 AD), the period of eutrophic water body (1800–1900 AD), the period of terrestrialised wetland (1900–1950 AD), and the period of secondary development of eutrophic water body (after 1950 AD).

Aridity thresholds of microbiome-soil function relationship along a climatic aridity gradient in alpine ecosystem

Aridity is known to influence the structure and function of the soil microbiome and their connection with ecosystem functions, however, whether aridity leads to gradual (or abrupt) and systemic (or specific) changes in the microbiome-ecosystem functions relationships in alpine ecosystems is largely unknown. Here, we conducted a survey of 60 sites along an aridity-gradient transect across the Tibetan Plateau to investigate changes in microbial diversity and functions and to evaluate their relationship with soil functionality. We found that plant richness and biomass, soil microbial richness (e.g., bacteria, fungi, diazotrophs, saprotrophs, pathotrophs and symbiotrophs), the relative abundance of copiotrophs and soil functionality (e.g., C-, N-, and P cycling, multifunctionality) decreased along the aridity gradient, whereas the proportion of genes associated with organic matter decomposition and denitrification increased (obtained from metagenomic sequencing). Above an aridity threshold of ∼0.6, soil multifunctionality decreased slowly and supported a larger proportion of genes associated with cellulose, hemicellulose, chitin, lignin and pectin degradation as well as genes associated with denitrification (e.g., nosZ, nosZ atypical 2, norB-cNor and norB-qNor). In drier habitats (>0.6 aridity level), microbial diversity and genes involved in organic matter decomposition and N cycling were strongly correlated with soil multifunctionality, whereas plant diversity was closely associated with soil multifunctionality in wetter habitats (<0.6 aridity level). Plant biomass and soil organic C play a key role in regulating microbial compositional and functional diversity and further affect soil multifunctionality in drier habitats. These findings suggest that soil microbiomes may play a larger role in maintaining soil multifunctionality in more arid environments than in less arid environments. Our results highlight the threshold responses of microbial diversity and functions to aridity and provide novel insight into mechanisms by which climate change affects ecosystem functions.

Detection of Hybrids in Willows (Salix, Salicaceae) Using Genome-Wide DArTseq Markers.

The genus Salix, comprising some 400-500 species, is important in various alluvial or wet habitats of the northern hemisphere. It is a promising crop for applications such as biomass production, biofuels, or environmental projects. Clear species delimitation is crucial in ecology, biotechnology, and horticulture. DArTseq markers, a genome-wide technique, were tested for species and hybrid identification. A total of 179 willow samples were analysed, including six species of Salix subgen. Salix and four species of Salix subgen. Vetrix, including those used in biomass crop production, representing important European taxa. Identification of species-specific markers, clustering analyses (principal coordinate analysis, neighbor-joining) and Bayesian methods (Structure) unambiguously identified putative hybrids. In addition to demonstrating the high efficiency of DArT-seq markers in identifying willow hybrids, we also opened-up new questions about hybridisation processes and systematics. We detected unidirectional hybridisation between S. alba and S. fragilis, forming backcross hybrids, and we rejected the hypothesis that S. fragilis does not occur naturally in Europe. Further, the isolated position of Salix triandra within the genus was confirmed.

Comparison of Growth and Physiological Effects of Soil Moisture Regime on Plantago maritima Plants from Geographically Isolated Sites on the Eastern Coast of the Baltic Sea.

The aim of the present study was to evaluate the morphological and physiological responses of P. maritima plants from five geographically isolated sites growing in habitats with different conditions to different substrate moisture levels in controlled conditions. Plants were produced from seed and cultivated in a greenhouse at four relatively constant soil moisture regimes: at 25, 50, and 75% soil water content and in soil flooded 3 cm above the surface (80% F). The two morphological traits that varied most strikingly among P. maritima accessions were the number of flower stalks and the number of leaves. Only plants from two accessions uniformly produced generative structures, and allocation to flowering was suppressed by both low moisture and flooding. Optimum shoot biomass accumulation for all accessions was at 50 and 75% soil moisture. The Performance Index Total was the most sensitive among the measured photosynthesis-related parameters, and it tended to decrease with an increase in soil water content for all P. maritima accessions. The initial hypothesis-that plants from relatively dry habitats will have a higher tolerance against low soil water levels, but plants from relatively wet habitats will have a higher tolerance against waterlogged or flooded soil-was not proven. The existence of three ecotypes of P. maritima within the five accessions from geographically isolated subpopulations on the eastern coast of the Baltic Sea at the level of morphological responses to soil water content can be proposed. P. maritima plants can be characterized as extremely tolerant to soil waterlogging and highly tolerant to soil flooding and low soil water content.