Search

Microbes affect the global carbon cycle that influences climate change and are in turn influenced by environmental change. Here, we use data from a long-term whole-ecosystem warming experiment at a boreal peatland to answer how temperature and CO 2 jointly influence communities of abundant, diverse, yet poorly understood, non-fungi microbial Eukaryotes (protists). These microbes influence ecosystem function directly through photosynthesis and respiration, and indirectly, through predation on decomposers (bacteria and fungi). Using a combination of high-throughput fluid imaging and 18S amplicon sequencing, we report large climate-induced, community-wide shifts in the community functional composition of these microbes (size, shape, and metabolism) that could alter overall function in peatlands. Importantly, we demonstrate a taxonomic convergence but a functional divergence in response to warming and elevated CO 2 with most environmental responses being contingent on organismal size: warming effects on functional composition are reversed by elevated CO 2 and amplified in larger microbes but not smaller ones. These findings show how the interactive effects of warming and rising CO 2 levels could alter the structure and function of peatland microbial food webs-a fragile ecosystem that stores upwards of 25% of all terrestrial carbon and is increasingly threatened by human exploitation., (© 2024 John Wiley & Sons Ltd.)

Treating peat with nutrient-rich ash significantly increases the content of different nutrients in the substrate. Such ash treatment promotes the revegetation of abandoned extracted peatlands. The aim of this study is to analyze the effect of wood ash (WA15 = 15 t ha−1 and WA10 = 10 t ha−1), oil shale ash (OSA8 = 8 t ha−1), and a mixture of wood ash and oil shale ash (WA10 + OSA8) on the revegetation (vascular plants and bryophytes) of the Puhatu abandoned extracted peatland in NE Estonia. The following results were obtained: (1) The MRPP tests indicate that there are compositional differences between the treatments. (2) Altogether, 23 vascular plant and 3 bryophyte species were recorded in the treatment areas. (3) Nine years after these ash treatments, the highest mean vascular plant species richness was recorded for WA15 (3.8 ± 0.3) and the lowest for OSA8 (2.0 ± 0.3). (4) A greater number of vascular plant species was observed in the WA15 area. (5) Mixed ash and wood ash had a significant effect on the amount of biomass in vascular plants. Treating with either wood ash or a mixture of ash ensured the rapid formation of vascular plants and bryophyte layers, contributing to the restoration of the abandoned peatland ecosystem. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the biological and physicochemical quality of Tonga Lake, a RAMSAR site situated in Algeria, during the Coronavirus pandemic. Phytoplankton and zooplankton, as well as several physicochemical variables (water temperature, pH, dissolved oxygen, total suspended particulate, and nutrients), were analyzed monthly at two stations during 2019-2020. The results showed that the physicochemical variables were within the tolerable ranges, except for phosphate, which slightly exceeded the reference threshold. No phytoplankton blooms were encountered; cyanobacteria were the most abundant during the study period and reached their maximum in winter (137888 cells/l), while dinoflagellates and diatoms reached their maxima in autumn and spring, respectively (23809 and 102083 cells/l). while the maximum of all the identified zooplankton groups was recorded in the spring. Dinoflagellates were strongly affected by pH and total suspended particulate. On the other hand, high significant correlations were reported between protozoa and dissolved oxygen, as well as between rotifers and water temperature. Nonetheless, no-significant correlations were detected between the remaining groups (diatoms, cyanobacteria, cladocerans, and copepods) and the investigated environmental variables. [ABSTRACT FROM AUTHOR]

The conservation of decorated caves is highly dependent on airflows in the karst network and through the surrounding host rock. Airflows are driven by the pressure gradient and influenced by the shape of the karst conduits and the permeability of the carbonate rock massif. Cosquer Cave is an Upper Paleolithic decorated cave, half submerged in a coastal karst, where conservation is also dependent on the cave's pools connected to the sea. Hydroclimatic data, such as air pressure and temperature and the water level inside and outside the cave, have been measured for several years to identify the main processes governing the water level variations, the airflows, and the air renewal. The data show unusual behavior for a karst: the karst air pressure is nearly always higher than the atmospheric pressure. As a result, the water level in the cave is below the sea level. The daily variations of the sea tide provide an assessment of the cave volume above the water level in the pools. Although the cave air is confined by the rock and the seawater, there are also external air inflows during short pressurization events connected with waves that can produce and force air bubbles to flow along submarine open fissures or karst conduits inside the massif. Moreover, the effective permeability of the carbonate rocks to air at the massif scale is inferred from the cave air pressure decrease over the summer season by applying Darcy's law in a partially saturated medium. Six years of data show that permeability varies from year to year and according to the cumulative rainfalls during the spring and summer. The driest years are correlated with a higher permeability, a faster air pressure decrease in the cave, and a faster rise in the pools' water level. In the future, in the context of climate change, a perturbation of the rock permeability is then expected in the near-surface caves, which will impact airflows in decorated caves and may alter their fragile hydroclimatic stability. [ABSTRACT FROM AUTHOR]

Peat mosses (Sphagnum spp.) are keystone species in boreal peatlands, where they dominate net primary productivity and facilitate the accumulation of carbon in thick peat deposits. Sphagnum mosses harbor a diverse assemblage of microbial partners, including N 2 -fixing (diazotrophic) and CH 4 -oxidizing (methanotrophic) taxa that support ecosystem function by regulating transformations of carbon and nitrogen. Here, we investigate the response of the Sphagnum phytobiome (plant + constituent microbiome + environment) to a gradient of experimental warming (+0°C to +9°C) and elevated CO 2 (+500 ppm) in an ombrotrophic peatland in northern Minnesota (USA). By tracking changes in carbon (CH 4 , CO 2 ) and nitrogen (NH 4 -N) cycling from the belowground environment up to Sphagnum and its associated microbiome, we identified a series of cascading impacts to the Sphagnum phytobiome triggered by warming and elevated CO 2 . Under ambient CO 2 , warming increased plant-available NH 4 -N in surface peat, excess N accumulated in Sphagnum tissue, and N 2 fixation activity decreased. Elevated CO 2 offset the effects of warming, disrupting the accumulation of N in peat and Sphagnum tissue. Methane concentrations in porewater increased with warming irrespective of CO 2 treatment, resulting in a ~10× rise in methanotrophic activity within Sphagnum from the +9°C enclosures. Warming's divergent impacts on diazotrophy and methanotrophy caused these processes to become decoupled at warmer temperatures, as evidenced by declining rates of methane-induced N 2 fixation and significant losses of keystone microbial taxa. In addition to changes in the Sphagnum microbiome, we observed ~94% mortality of Sphagnum between the +0°C and +9°C treatments, possibly due to the interactive effects of warming on N-availability and competition from vascular plant species. Collectively, these results highlight the vulnerability of the Sphagnum phytobiome to rising temperatures and atmospheric CO 2 concentrations, with significant implications for carbon and nitrogen cycling in boreal peatlands., (© 2023 John Wiley & Sons Ltd.)

Peatlands, constituting over half of terrestrial wetland ecosystems across the globe, hold critical ecological significance and are large stores of carbon (C). Irish oceanic raised bogs are a rare peatland ecosystem offering numerous ecosystem services, including C storage, biodiversity support and water regulation. However, they have been degraded over the centuries due to artificial drainage, followed by peat extraction, afforestation and agriculture. This has an overall negative impact on the functioning of peatlands, shifting them from a moderate C sink to a large C source. Recognizing the importance of these ecosystems, efforts are underway for conservation (rewetting and rehabilitation), while accurately accounting for C stock and greenhouse gas (GHG) emissions. However, the implementation of these efforts requires accurate identification and mapping of artificial drainage ditches. This study utilized very high‐resolution (25 cm) aerial imagery, and a deep learning (U‐Net) approach to map the visible artificial drainage (unobstructed by vegetation or infill) in raised bogs at a national scale. The results show that artificial drainage is widespread, with ~20 000 km of drains mapped. The overall accuracy of the model was 80% on an independent testing dataset. The data were also used to derive the Fracditch which was 0.03 (fraction of artificial drainage on industrial peat extraction sites). This is lower than IPCC Tier 1 Fracditch and can aid in IPCC Tier 2 reporting for Ireland. This is the first study to map drains with diverse sizes and patterns on Irish‐raised bogs using optical aerial imagery and deep learning methods. The map will serve as an important baseline dataset for evaluating the artificial drainage ditch conditions. It will prove useful for sustainable management, conservation and refined estimations of GHG emissions. The model's capacity for generalization implies its potential in mapping artificial drains in peatlands at a regional and global scale, thereby enhancing the comprehension of the global effects of artificial drainage ditches on peatlands. [ABSTRACT FROM AUTHOR]

Spiroplasma virus 4 (SpV4) is a bacteriophage of the Microviridae, which packages circular ssDNA within non-enveloped T = 1 icosahedral capsids. It infects spiroplasmas, which are known pathogens of honeybees. Here, the structure of the SpV4 virion is determined using cryo-electron microscopy to a resolution of 2.5 Å. A striking feature of the SpV4 capsid is the mushroom-like protrusions at the 3-fold axes, which is common among all members of the subfamily Gokushovirinae. While the function of the protrusion is currently unknown, this feature varies widely in this subfamily and is therefore possibly an adaptation for host recognition. Furthermore, on the interior of the SpV4 capsid, the location of DNA-binding protein VP8 was identified and shown to have low structural conservation to the capsids of other viruses in the family. The structural characterization of SpV4 will aid future studies analyzing the virus–host interaction, to understand disease mechanisms at a molecular level. Furthermore, the structural comparisons in this study, including a low-resolution structure of the chlamydia phage 2, provide an overview of the structural repertoire of the viruses in this family that infect various bacterial hosts, which in turn infect a wide range of animals and plants. [ABSTRACT FROM AUTHOR]

Disappearance of lakes is one of the most dangerous processes affecting the entire natural environment, including soil. This phenomenon is considered natural, resulting from climate change, however in recent decades, a significant acceleration of this process has been observed due to the direct impact of human activity. In areas directly adjacent to lakes, organic soils usually predominate. Unfortunately, wetlands are increasingly being drained and used for agricultural purposes. Under such circumstances, changes in the physical and chemical properties of these soils are often irreversible, causing their degradation. As an effect of increased mineralization, a number of typical modifications occur in soils, such as carbon loss, increased degree of peat decomposition, and changes in soil structure. Long-term dehydration has led to muck formation. Additionally, lowering of lake water uncovers previously flooded areas and increases the intensity of soil-forming processes. However, the presence of the Subaquatic qualifier in the World Reference Base for Soil Resources (WRB) suggests that sediments in shallow water bodies no more than 200 cm deep can also be classified as soils. The progressive disappearance of lakes observed all over the world is therefore a process affecting not only the reduction of water bodies, but also changes in the properties and typology of soils and vegetation cover. [ABSTRACT FROM AUTHOR]

Peatlands are major natural carbon pool in terrestrial ecosystems globally and are essential to a variety of fields, including global ecology, hydrology, and ecosystem services. Under the context of climate change, the management and conservation of peatlands has become a topic of international concern. Nevertheless, few studies have yet systematized the overall international dynamics of existing peatland research. In this study, based on an approach integrating bibliometrics and a literature review, we systematically analyzed peatland research from a literature perspective. Alongside traditional bibliometric analyses (e.g., number of publications, research impact, and hot areas), recent top keywords in peatland research were found, including 'oil palm', 'tropical peatland', 'permafrost', and so on. Furthermore, six hot topics of peatland research were identified: (1) peatland development and the impacts and degradations, (2) the history of peatland development and factors of formation, (3) chemical element contaminants in peatlands, (4) tropical peatlands, (5) peat adsorption and its humic acids, and (6) the influence of peatland conservation on the ecosystem. In addition, this review found that the adverse consequences of peatland degradation in the context of climate change merit greater attention, that peatland-mapping techniques suitable for all regions are lacking, that a unified global assessment of carbon stocks in peatlands urgently needs to be established, spanning all countries, and that a reliable system for assessing peatland-ecosystem services needs to be implemented expeditiously. In this study, we argued that enhanced integration in research will bridge knowledge gaps and facilitate the systematic synthesis of peatlands as complex systems, which is an imperative need. [ABSTRACT FROM AUTHOR]

The coastal temperate rainforests (CTRs) of Chilean Patagonia are a valuable forest biome on Earth given their prominent role in biogeochemical cycling and the ecological value and dynamics of surface processes. The Patagonian CTRs are amongst the most carbon-rich biomes on Earth. Together with frequent landscape disturbances, these forests potentially allow for episodic and massive release or sequestration of carbon into and from the atmosphere. We argue that, despite their particular biogeographic, geochemical, and ecological roles, the Patagonian CTRs in particular and the global CTRs in general are not adequately represented in the current catalog listing critical zone observatories (CZOs). Here, we present the Pumalín CZO as the first of its kind, located in Pumalín National Park in northern Chilean Patagonia. We consider our CZO a representative end-member of undisturbed ecosystem functioning of the Patagonian CTRs. We have identified four core research themes for the Pumalín CZO around which our activities circle in an integrative, quantitative, and generic approach using a range of emerging techniques. Our methodological blend includes an environmental seismology that also fills a critical spatiotemporal scale in terms of monitoring critical zone and surface processes with a minimum intervention in those pristine forests. We aim to gain quantitative understanding of these topics: (1) carbon sink functioning; (2) biota-driven landscape evolution; (3) water, biogeological, and energy fluxes; and (4) disturbance regime understanding. Our findings highlight the multitude of active functions that trees in particular and forests in general may have on the entire cascade of surface processes and the concomitant carbon cycling. This highlights the importance of an integrated approach, i.e., "one physical system", as proposed by Richter and Billings (2015), and accounts for the recent advances in pushing nature conservation along the Chilean coast. [ABSTRACT FROM AUTHOR]

Understanding the critical zone processes related to groundwater flows relies on subsurface structure knowledge and its associated parameters. We propose a methodology to draw the patterns of the subsurface critical zone at the catchment scale from seismic refraction data and show its interest for hydrological modelling. The designed patterns define the structure of a physically based distributed hydrological model applied to a mountainous catchment. With that goal, we acquired 10 seismic profiles covering the different geomorphology zones of the studied catchment. We develop a methodology to analyse the geostatistical characteristics of the seismic data and interpolate them over the whole catchment. The applied geostatistical model considers the scale variability of the subsurface structures observed from the seismic data analysis. We use compressional seismic wave velocity thresholds to identify the depth of the soil and saprolite bottom boundaries. Assuming that such porous compartments host the main part of the active aquifer, their patterns are embedded in a distributed hydrological model. We examine the sensitivity of classical hydrological data (piezometric heads) and geophysical data (magnetic resonance soundings) to the applied velocity thresholds used to define the soil and saprolite boundaries. Different sets of hydrogeological parameters are used in order to distinguish general trends or specificities related to the choice of parameter values. The application of the methodology to an actual catchment illustrates the interest of seismic refraction in constraining the structure of the critical zone subsurface compartments. The sensitivity tests highlight the complementarity of the analysed hydrogeophysical data sets. [ABSTRACT FROM AUTHOR]

Aim: The diversity and distribution of soil microorganisms and their potential for long‐distance dispersal (LDD) are poorly documented, making the threats posed by climate change difficult to assess. If microorganisms do not disperse globally, regional endemism may develop and extinction may occur due to environmental changes. Here, we addressed this question using the testate amoeba Apodera vas, a morphologically conspicuous model soil microorganism in microbial biogeography, commonly found in peatlands and forests mainly of former Gondwana. We first documented its distribution. We next assessed whether its distribution could be explained by dispersal (i.e. matching its climatic niche) or vicariance (i.e. palaeogeography), based on the magnitude of potential range expansions or contractions in response to past and on‐going climatic changes. Last, we wanted to assess the likelihood of cryptic diversity and its potential threat from climate and land‐use changes (e.g. due to limited LDD). Location: Documented records: Southern Hemisphere and intertropical zone; modelling: Global. Methods: We first built an updated global distribution map of A. vas using 401 validated georeferenced records. We next used these data to develop a climatic niche model to predict its past (LGM, i.e. 21 ± 3 ka BP; PMIP3 IPSL‐CM5A‐LR), present and future (IPSL‐CMP6A‐LR predictions for 2071–2100, SSP3 and 5) potential distributions in responses to climate, by relating the species occurrences to climatic and topographic predictors. We then used these predictions to test our hypotheses (dispersal/vicariance, cryptic diversity, future threat from LDD limitation). Results: Our models show that favourable climatic conditions for A. vas currently exist in the British Isles, an especially well‐studied region for testate amoebae where this species has never been found. This demonstrates a lack of interhemispheric LDD, congruent with the palaeogeography (vicariance) hypothesis. Longitudinal LDD is, however, confirmed by the presence of A. vas in isolated and geologically young peri‐Antarctic islands. Potential distribution maps for past, current and future climates show favourable climatic conditions existing on parts of all southern continents, with shifts to higher land from LGM to current in the tropics and a strong range contraction from current to future (global warming IPSL‐CM6A‐LR scenario for 2071–2100, SSP3.70 and SSP5.85) with favourable conditions developing on the Antarctic Peninsula. Main Conclusions: This study illustrates the value of climate niche models for research on microbial diversity and biogeography, along with exploring the role played by historical factors and dispersal limitation in shaping microbial biogeography. We assess the discrepancy between latitudinal and longitudinal LDD for A. vas, which is possibly due to contrast in wind patterns and/or likelihood of transport by birds. Our models also suggest that climate change may lead to regional extinction of terrestrial microscopic organisms, thus illustrating the pertinence of including microorganisms in biodiversity conservation research and actions. [ABSTRACT FROM AUTHOR]

Tree carbon allocation is a dynamic process that depends on the tree's environment, but we know relatively little about how biotic interactions influence these dynamics. In central Kenya, the loss of vertebrate herbivores and the savanna's invasion by the ant Pheidole megacephala are disrupting mutualisms between the foundational tree Acacia (Vachellia) drepanolobium and its native ant defenders. Here, we piloted a 13Carbon (C) pulse-labeling method to investigate the influence of these biotic interactions on C allocation to ant partners by adult trees in situ. Trees withstood experimental conditions and took up sufficient labeled 13CO2 for 13C to be detected in various C sinks, including ant mutualists. The δ13C in ants collected shortly after labeling suggested that trees exposed to herbivores allocated relatively more newly assimilated C to native ant defenders. Our results demonstrate the viability of the pulse-labeling method and suggest that C allocation to ant partners depends on the biotic context of the tree, but further investigation with replication is needed to characterize such differences in relation to invasion and herbivore loss. [ABSTRACT FROM AUTHOR]

The present work aimed to study the distribution of Cladocera and Rotifera populations in two reservoirs in western Algeria (Sidi Mhamed Benali Lake and Sarno Dam), taking into account two physical parameters: water temperature and pH in the Mediterranean climate. The abundance of zooplankton groups, specifically Cladocerans and Rotifers, exhibited an evolution closely paralleling the environmental characteristics of the ecosystem. Both populations were monthly sampled from January to July 2017 using a plankton net of 64µm mesh size. In total, 35 taxa were recorded, of which 18 species belong to the Cladocera and 17 others are members of the Rotifera. The results of this comparative study showed, on the one hand, heterogeneity in the specific richness of Cladocera and Rotifera on a spatiotemporal scale and a relationship with the physical quality of the water in the two environments on the other hand. Furthermore, Sidi Mhamed Benali Lake appeared to be more diverse and the richest in Cladocera. Overall, the highest taxon richness and abundance were recorded during the rainy season from January to April (35 species) compared with 22 taxa in the dry season. These results were confirmed and clearly demonstrated by the results of the principal component analysis (PCA). [ABSTRACT FROM AUTHOR]

Testate amoebae are unicellular eukaryotic organisms covered with an external skeleton called a shell. They are an important component of many terrestrial ecosystems, especially peatlands, where they can be preserved in peat deposits and used as a proxy of surface wetness in paleoecological reconstructions. Here, we represent a database from a vast but poorly studied region of the Western Siberia Lowland containing information on TA occurrences in relation to substrate moisture and WTD. The dataset includes 88 species from 32 genera, with 2181 incidences and 21,562 counted individuals. All samples were collected in oligotrophic peatlands and prepared using the method of wet sieving with a subsequent sedimentation of aqueous suspensions. This database contributes to the understanding of the distribution of testate amoebae and can be further used in large-scale investigations. Dataset: https://doi.org/10.15468/avvq78. Dataset License: CC-BY 4.0 [ABSTRACT FROM AUTHOR]

The study of soil organic matter (SOM) can benefit from the use of Fourier‐transform infrared spectroscopy, an analytical method that complements traditional fractionation and extraction methods. This review provides guidance on the use of diffuse reflectance infrared Fourier transform (DRIFT) in the mid‐infrared region (MIR: 4000–400 cm−1). Two distinct applications of DRIFT spectroscopy are reviewed: soil organic matter (1) characterization and (2) quantification. Characterization of SOM involves the qualitative to semi‐quantitative measurement of functional groups that constitute organic matter, and quantification employs chemometrics to predict fractions of SOM. Guidance on decision‐making in how methods are conducted based on sample type and research question, and on interpretation of results are provided. Core Ideas: Fourier‐transform infrared (FTIR) spectroscopy can be used to characterize and quantify soil organic matter (SOM).Diffuse reflectance infrared Fourier transform in the mid‐infrared region of 4000–400 cm−1 is reviewed.Organic functional groups detected by FTIR spectroscopy complement other structural analytical techniques.FTIR spectroscopy can also be used to quantify SOM fractions using chemometrics. [ABSTRACT FROM AUTHOR]

Peatlands store one‐third of the Earth's carbon. Human activities and climate change‐induced peatland vegetation shift from Sphagnum to shrub may lead to peatland degradation. To understand the ecology and functions of these peatlands, we collected samples from 10 peatland mosaics dominated by Sphagnums, mixed plant communities of Sphagnums, and shrubs across south China. Through sequencing the plant rhizosphere microbiome and measuring peat properties, we explored the plant–soil interactions and identified the keystone microbial taxa in peatlands of three vegetation types. Results showed that peat pH decreased along with the plant community shift from Sphagnum to shrub, which may be due to the accumulation of sulfur and phenolics. Lower pH further reduced bacterial diversity in shrub peatlands as Acidobacteriota became predominant in the keystone taxa. Overall, microbiomes in shrub peatlands showed degraded properties, such as a less stable microbial community dominated by few keystone taxa and the loss of methane‐mitigating microbes. The keystone microbial taxa in Sphagnum peatlands included microbes that utilize insoluble organic substances, mono‐ and oligo‐saccharides. Most importantly, the methanotrophic microbes that oxidize methane only appeared in the keystone taxa of Sphagnum peatlands. Mixed plant community peatlands contained the highest concentrations of iron. Slow‐growing fungi and bacteria were in the keystone microbial taxa, indicating slow decomposition rates in these peatlands. Our study suggests that human activity and climate change‐induced peatland vegetation shift from Sphagnum to shrub leads to an unstable belowground community, indicating the degraded peatland, which may exacerbate in the future. [ABSTRACT FROM AUTHOR]

Soil protists are increasingly studied due to a release from previous methodological constraints and the acknowledgement of their immense diversity and functional importance in ecosystems. However, these studies often lack sufficient depth in knowledge, which is visible in the form of falsely used terms and false‐ or over‐interpreted data with conclusions that cannot be drawn from the data obtained. As we welcome that also non‐experts include protists in their still mostly bacterial and/or fungal‐focused studies, our aim here is to help avoid some common errors. We provide suggestions for current terms to use when working on soil protists, like protist instead of protozoa, predator instead of grazer, microorganisms rather than microflora and other terms to be used to describe the prey spectrum of protists. We then highlight some dos and don'ts in soil protist ecology including challenges related to interpreting 18S rRNA gene amplicon sequencing data. We caution against the use of standard bioinformatic settings optimized for bacteria and the uncritical reliance on incomplete and partly erroneous reference databases. We also show why causal inferences cannot be drawn from sequence‐based correlation analyses or any sampling/monitoring, study in the field without thorough experimental confirmation and sound understanding of the biology of taxa. Together, we envision this work to help non‐experts to more easily include protists in their soil ecology analyses and obtain more reliable interpretations from their protist data and other biodiversity data that, in the end, will contribute to a better understanding of soil ecology. [ABSTRACT FROM AUTHOR]

Our study investigates the effect of near-naturalization of plantations on soil physicochemical and bacterial features and the difference between soil layers in Baxianshan National Nature Reserve. Four stands were involved, including two forest types: near-naturalized and natural secondary forests, with the former classified into three stages. Soil physicochemical and bacterial properties were determined and analyzed. TC, TN contents and C/N ratio of the surface soil were higher than the corresponding lower layer. TC, TN contents decreased first and then increased with near-naturalization, lower than the natural secondary forests, while the C/N ratio was the opposite; total and endemic OTUs quantity was more in the surface layer than the lower and both increased with near-naturalization; the dominant phyla were Proteobacteria, Acidobacteria, Gemmatimonadetes, and verrucomicrobia, the relative abundance of Proteobacteria increased with near-naturalization while that of other dominant phyla decreased; the α-diversity increased on the whole during near-naturalization and was lower than the natural secondary forests except for Simpson and Shannon index; environmental factors significantly explained the bacterial α-diversity and community structure of natural secondary forests but not near-naturalized forests. This study helps fully understand the change characteristics and response mechanisms of soil bacterial community structure to the restoration of the plantation. [ABSTRACT FROM AUTHOR]

Draix-Bléone critical zone observatory was created in 1983 to study erosion processes in a mountainous badland region of the French Southern Alps. Six catchments of varying size (0.001 to 22 km 2) and vegetation cover are equipped to measure water and sediment fluxes, both as bedload and suspended load. This paper presents the core dataset of the observatory, including rainfall and meteorology, high-frequency discharge and suspended-sediment concentration, and event-scale bedload volumes. The longest records span almost 40 years. Measurement and data-processing methods are presented, as well as data quality assessment procedures and examples of results. All the data presented in this paper are available on the open repository 10.17180/obs.draix (Draix-Bleone Observatory, 2015), and a 5-year snapshot is available for review at 10.57745/BEYQFQ (Klotz et al., 2023). [ABSTRACT FROM AUTHOR]

Phototrophic microbes are widespread in soils, but their contribution to soil carbon (C) uptake remains underexplored in most terrestrial systems, including C-accreting systems such as peatlands. Here, by means of metabarcoding and ecophysiological measurements, we examined how microbial photosynthesis and its biotic (e.g., phototrophic community structure, biomass) and abiotic drivers (e.g., Sphagnum moisture, light intensity) vary across peatland microhabitats. Using a natural gradient of microhabitat conditions from pool to forest, we show that the structure of phototrophic microbial communities shifted from a dominance of eukaryotes in pools to prokaryotes in forests. We identified five groups of co-occurring phototrophic operational taxonomic units with specific environmental preferences across the gradient. Along with such structural changes, we found that microbial C uptake was the highest in the driest and shadiest microhabitats. This study renews and improves current views on phototrophic microbes in peatlands, as the contribution of microbial photosynthesis to peatland C uptake has essentially been studied in wet microhabitats., (© 2021 Society for Applied Microbiology and John Wiley & Sons Ltd.)

The soil microbiome is recognized as an essential component of healthy soils. Viruses are also diverse and abundant in soils, but their roles in soil systems remain unclear. Here we argue for the consideration of viruses in soil microbial food webs and describe the impact of viruses on soil biogeochemistry. The soil food web is an intricate series of trophic levels that span from autotrophic microorganisms to plants and animals. Each soil system encompasses contrasting and dynamic physicochemical conditions, with labyrinthine habitats composed of particles. Conditions are prone to shifts in space and time, and this variability can obstruct or facilitate interactions of microorganisms and viruses. Because viruses can infect all domains of life, they must be considered as key regulators of soil food web dynamics and biogeochemical cycling. We highlight future research avenues that will enable a more robust understanding of the roles of viruses in soil function and health., (© 2024. Springer Nature Limited.)

Granulometric aggregate fractions (20 µm–2 mm) of chernozem soils with different agriculture-use histories (native steppe, permanent bare fallow, arable land, and shelterbelt) were investigated in mid-IR and far IR regions (4000–100 cm−1) by heating in the air from 25 to 215 °C, using ATR FTIR and linear discriminant analysis to differentiate the land-use samples without chemical perturbation. The temperature dependences of the band maxima significantly differed for bands of silicate matrix and bands with the contribution of soil organic matter and were more stable to experimental conditions compared to the absolute positions. The thermal behavior of the integral intensities of the IR bands at 790–750 cm−1 and 440–420 cm−1 that was different compared to pure quartz, may be attributed to –C–H bending of alkanes and (poly)aromatic structures and skeletal bending, and could be used to distinguish intact soils from agriculturally used samples. The different temperature behaviors of the bands for fractions of soils with different land use are shown, with the maximum difference in fractions below 20–50 µm and medium fractions (50–200 µm). Changes in the band-maximum frequencies and the integral intensities of the bands were reversible for a heating–cooling cycle. The linear discriminant analysis of the spectra obtained for granulometric fractions of chernozem soils made it possible to separate the samples of native steppe, arable land, bare fallow, and shelterbelt with a high probability based on the type of vegetation and agrogenic load, mainly on the basis of the spectral ranges associated with biogenic forms of quartz and phytoliths. [ABSTRACT FROM AUTHOR]

Temperature-dependent IR spectroscopy capable of revealing specific changes in the band intensities, positions, and shape was used to increase the information on humic substances (HS) from soils. Temperature dependences of IR spectra of HS isolated from silicate-based soils differing in the contents and nature of organic matter, chernozem and soddy podzolic soil, were investigated by attenuated total internal reflection FTIR in the mid-IR region (4000–400 cm−1) in the air within the moderate temperature range of 25–215 °C (298–488 K) with a step of 2.5 °C. The dependences of shifts in frequency (wavenumber) corresponding to band maxima and integrated band intensities were built for all major bands. Observed reversible frequency shifts upon heating and cooling can be interpreted as forming structures in the dry state. The behavior of integrated intensities of bands assigned to C–H and C–C vibrations, characteristic vibrations of polyaromatic compounds, carboxylic acids, and carboxylates were shown, and similar behavior for the same group (symmetric and antisymmetric stretches) were revealed. Differences in the temperature trends in chernozem and soddy podzolic soils due to different structures (aliphatic and aromatic) and functional groups (carboxylic and carboxylate) are shown. The different behavior of the bands corresponding to carboxylic groups and skeletal vibrations differentiates soil types with different organic matter. The temperature trends of band maximum and intensity shifts are less prone to measurement conditions and may serve as qualitative parameters characterizing the composition of soil humic substances. [ABSTRACT FROM AUTHOR]

Fifty per cent of European peatlands are in a damaged state. While intact peatlands are natural carbon sinks, degraded sites release important amounts of greenhouse gases into the atmosphere, contributing to global warming. Restoration of the hydrological functionality of peatlands has proved to be an efficient tool to avoid these emissions. In France, Tuffnell & Bignon's ministerial report (2019) emphasized the need for peatlands 'integration into the National Low Carbon Strategy, targeting carbon neutrality by 2050. However, current knowledge regarding French peatlands' distribution and carbon stocks is insufficient and does not allow decision makers and managers to prioritize areas for restoration. The most complete database to date is the 1949 Atlas, an inventory of exploitable peat deposits that was conducted during WWII for peat exploitation as fuel. Until its digitalization, the latter database was archived and never used in a scientific study. It provides detailed information about peatland surfaces, peat thicknesses and carbon contents at that time. We estimated peat carbon stocks from French peatlands to be 111 Mt C in 1949 for 63,290 ha identified as peaty sites, the equivalent of 3% of the organic carbon contained in the upper 30 centimetres of French soils. 34% of this stock was held in Lower Normandy (37.7 Mt C) and 12% in the Picardy's region (13.0 Mt C), in large lowland peatlands. However, not all peatlands were prospected in the 1949 inventory and the characteristics of the prospected peatlands may have changed with anthropic disturbances of the last decades, such as draining or climate change. These first results highlight the need for a recent inventory of French peatlands and carbon stocks based on local data aggregation. Data from the 1949 Atlas could help constituting this new inventory but should be validated before being used to describe the present. [ABSTRACT FROM AUTHOR]

Using statistical methods that do not directly represent the causality between variables to attribute climate and plant traits as controlling ecosystem functions may lead to biased perceptions. We revisited this issue using a causal graphical model, the Bayesian network (BN), capable of quantifying causality by conditional probability tables. Based on expert knowledge and climate, vegetation, and ecosystem function data from the FLUXNET flux stations, we constructed a BN representing the causal relationship of climate–plant-trait–ecosystem functions. Based on the sensitivity analysis function of the BN, we attributed the control of climate and plant traits over ecosystem functions and compared the results with those based on random forests and correlation analysis. The main conclusions of this study include the following: BN can be used for the quantification of causal relationships between complex ecosystems in response to climate change and enables the analysis of indirect effects among variables. The causality reflected in the BN is as good as the expert knowledge of the causal links. Compared to BN, the feature importance difference between "mean vapor pressure deficit and cumulative soil water index" and "maximum leaf area index and maximum vegetation height" reported by random forests is higher and can be overestimated. With the causality relation between correlated variables constructed, a BN-based sensitivity analysis can reduce the uncertainty in quantifying the importance of correlated variables. The understanding of the mechanism of indirect effects of climate variables on ecosystem functions through plant traits can be deepened by the chain casuality quantification in BNs. [ABSTRACT FROM AUTHOR]

Soil water drainage is the main source of groundwater recharge and river flow. It is therefore a key process for water resource management. In this study, we evaluate the soil hydrology and the soil water drainage, simulated by the interactions between soil–biosphere–atmosphere (ISBA) land surface model currently used for hydrological applications from the watershed scale to the global scale, where parameters are generally not calibrated. This evaluation is done using seven lysimeters from two long-term model approach sites measuring hourly water dynamics between 2009 and 2019 in northeastern France. These 2 m depth lysimeters are filled with different soil types and are either maintained as bare soil or covered with vegetation. Four closed-form equations describing soil water retention and hydraulic conductivity functions are tested, namely the commonly used equations from and , a combination of the soil water retention function with the unsaturated hydraulic conductivity function, and, for the very first time in a land surface model (LSM), a modified version of the equations, with a new hydraulic conductivity curve proposed by. The results indicate good performance by ISBA with the different closure equations in terms of soil volumetric water content and water mass. The drained flow at the bottom of the lysimeter is well simulated, using , while some weaknesses appear with due to the abrupt shape near the saturation of its hydraulic conductivity function. The mixed form or the new hydraulic conductivity function from allows the solving of this problem and even improves the simulation of the drainage dynamic, especially for intense drainage events. The study also highlights the importance of the vertical heterogeneity of the soil hydrodynamic parameters to correctly simulate the drainage dynamic, in addition to the primary influence of the parameters characterizing the shape of the soil water retention function. [ABSTRACT FROM AUTHOR]

Peat mosses (Sphagnum spp.) are keystone species in boreal peatlands, where they dominate net primary productivity and facilitate the accumulation of carbon in thick peat deposits. Sphagnum mosses harbor a diverse assemblage of microbial partners, including N2‐fixing (diazotrophic) and CH4‐oxidizing (methanotrophic) taxa that support ecosystem function by regulating transformations of carbon and nitrogen. Here, we investigate the response of the Sphagnum phytobiome (plant + constituent microbiome + environment) to a gradient of experimental warming (+0°C to +9°C) and elevated CO2 (+500 ppm) in an ombrotrophic peatland in northern Minnesota (USA). By tracking changes in carbon (CH4, CO2) and nitrogen (NH4‐N) cycling from the belowground environment up to Sphagnum and its associated microbiome, we identified a series of cascading impacts to the Sphagnum phytobiome triggered by warming and elevated CO2. Under ambient CO2, warming increased plant‐available NH4‐N in surface peat, excess N accumulated in Sphagnum tissue, and N2 fixation activity decreased. Elevated CO2 offset the effects of warming, disrupting the accumulation of N in peat and Sphagnum tissue. Methane concentrations in porewater increased with warming irrespective of CO2 treatment, resulting in a ~10× rise in methanotrophic activity within Sphagnum from the +9°C enclosures. Warming's divergent impacts on diazotrophy and methanotrophy caused these processes to become decoupled at warmer temperatures, as evidenced by declining rates of methane‐induced N2 fixation and significant losses of keystone microbial taxa. In addition to changes in the Sphagnum microbiome, we observed ~94% mortality of Sphagnum between the +0°C and +9°C treatments, possibly due to the interactive effects of warming on N‐availability and competition from vascular plant species. Collectively, these results highlight the vulnerability of the Sphagnum phytobiome to rising temperatures and atmospheric CO2 concentrations, with significant implications for carbon and nitrogen cycling in boreal peatlands. [ABSTRACT FROM AUTHOR]

Soil protists play a key role in driving ecological functions through predation and parasitism. However, little is known about how nitrogen (N) deposition and seasonal variation influence soil protist functions in forest soils.Here, we assessed first the impacts of N deposition (control, 50, 100 and 150 kg N ha−1 year−1) on the functional composition of the soil protist community in summer and winter, using amplicon sequencing of environmental DNA from a subtropical natural forest.We found that soil protists were dominated by consumers (42.6%–51.6%), followed by parasites (32.9%–40.9%) and phototrophs (3.2%–13.1%), implying a predominant role of consumers and potential top‐down effects on the other trophic groups in subtropical forest soils. The functional composition of soil protists was greatly influenced by N deposition, but these responses were dependent on seasonal variation. The diversity of phototrophs was lower in summer than in winter. Instead, an opposite pattern was observed for consumers, resulting in a significantly higher protist diversity in summer than in winter. Furthermore, low and high N deposition simplified the structural complexity of soil protist communities, suggesting a nonlinear response of protist structural stability to N deposition.Synthesis and applications. This study provides unprecedented evidence that seasonal variation plays an important role in regulating responses of soil protist functional composition to N deposition, and highlights the nonlinear effects of rising N deposition on the soil food web. [ABSTRACT FROM AUTHOR]

We develop a phenomenological model of suspended sediment transport on the basis of data acquired in the Capesterre river, which drains a small tropical catchment in Guadeloupe. The model correctly represents the concentration of suspended sediment during floods, provided that the relation between concentration and water level forms a counterclockwise loop. In the model, the properties of the sediment and of the river are all lumped into four parameters: a settling velocity related to the size of the suspended sediment, a threshold water level which acts as a proxy for the threshold shear stress, a characteristic entrainment rate, and a dimensionless exponent. The value of the parameters changes from one flood to the next, probably reflecting changes in the characteristics of the river and the fine sediment. Finally, a test of the model against data acquired in a small catchment in the French Alps suggests that the model is versatile enough to be used in diverse hydrological settings. [ABSTRACT FROM AUTHOR]

Saline soil organic matter (SOM) composition and distribution are largely unknown. A coastal field experiment was designed to investigate the effects of straw and nitrogen addition on SOM characteristics by diffuse reflectance Fourier‐transform mid‐infrared (FTIR) spectral and amino sugar analysis. In each growing season, maize/wheat straw was applied at rates of 5.0 × 103 kg ha−1 (S5) and 1.0 × 104 kg ha−1 (S10), and inorganic nitrogen was applied at rates of 75 kg ha−1 (N75), 150 kg ha−1 (N150), and 300 kg ha−1 (N300). N150 without straw addition was the control treatment (CK). Dry‐sieving technique was used to fractionate soils into macroaggregates (>0.25 mm, MA), microaggregates (0.053–0.25 mm, MI), and silt‐plus‐clay particles (<0.053 mm, SC). Results showed that SOM and amino sugar contents were efficiently increased in the S5 and S10 treatments compared with CK, which were significantly higher in MA and MI than in SC (p < 0.05). In straw‐addition treatments, SOM and amino sugar contents were significantly higher in S5N300 and S10N300 (p < 0.05). The contribution of microbial necromass C to soil organic C (SOC) was 8.9–17.1%, and the fungal residue was dominant in bulk and aggregate soils. The amount of recalcitrant form of organic C decreased with SOM content increase, and the abundance of aromatic C groups increased under higher salt stress. Therefore, we suggested that microbial necromass accumulation could not be the main pathway of SOC sequestration, and enriching recalcitrant organic C probably led to SOM stability in saline soils. [ABSTRACT FROM AUTHOR]

The Coastal Temperate Rainforests (CTRs) of Chilean Patagonia are a valuable forest biome on Earth given its prominent role for biogeochemical cycling, ecological value and dynamic of surface processes. The Patagonian CTRs are amongst the most carbon rich biomes on Earth. Together with frequent landscape disturbances, these forests potentially allow for episodic, massive release of carbon into the atmosphere. We argue that despite their particular biogeographic, geochemical, and ecological role, the Patagonian CTRs in particular, and the global CTRs in general, are not adequately represented in the current catalogue listing critical zone observatories (CZO). Here, we present the Pumalin CZO as the first of its kind, located in the Pumalin National park in northern Chilean Patagonia. We have identified four core research themes for the Pumalin CZO around which our activities circle in an integrative, quantitative, generic approach using a range of emerging techniques. We aim to gain quantitative understanding of these topics: (1) carbon sink functioning, (2) biota-driven landscape evolution, (3) water, biogeological and energy fluxes, and (4) disturbance regime understanding. Our findings highlight the multitude of active functions that trees in particular, and forests in general, may have on the entire chain of carbon cycling. This highlights the importance of an integrated approach, i.e., 'one physical system', as proposed by Richter and Billings (2015), and accounting for the recent advances in pushing nature conservation along the Chilean coast. [ABSTRACT FROM AUTHOR]

The existing techniques for lignosulfonate (LS) in humate fertilizers lack selectivity to humic substances (HS) as the main component; they involve labor- and time-consuming sample preparation to separate the components at the level of detectable LS concentrations. The procedure based on attenuated total reflectance (ATR) FTIR spectroscopy with simple sample preparation for directly quantifying lignosulfonates in aqueous solutions and lignosulfonates and HS in aqueous solutions of preparations based on HS of coal origin (Sigma Aldrich, Powhumus, and Life Force) was developed. Lignosulfonate quantification is possible by exploiting the bands at 1266, 1192, 1093, and 1042 cm−1 with limits of detection of 0.4–2 g/L. Quantifying LS in a mixture with humates includes centrifugation of prepared solutions to separate interfering silicate impurities. LS quantification in the range of 10–100 g/L against HS (up to a 2-fold excess) with an error of up to 5% is possible based on the spectral absorptions at 1093 and 1042 cm−1. Simultaneous quantification of humate in the mixture with an error of up to 10% is possible by exploiting the bands at 1570 and 1383 cm−1 (carboxylates). The study shows the possibility of determining lignosulfonate against an HS background several times higher than lignosulfonate. The developed technique is applicable for analyzing fertilizers of simple composition and quality control of pure humates used for plant growth. Obtaining the most accurate results needs calibration solutions from the same brands that make up the test mixture. [ABSTRACT FROM AUTHOR]

While it is now widely accepted that microorganisms provide essential functions in restoration ecology, the nature of relationships between microbial community assembly and ecosystem recovery remains unclear. There has been a longstanding challenge to decipher whether microorganisms facilitate or simply follow ecosystem recovery, and evidence for each is mixed at best. We propose that understanding microbial community assembly processes is critical to understanding the role of microorganisms during ecosystem restoration and thus optimizing management strategies. We examine how the connection between environment, community structure, and function is fundamentally underpinned by the processes governing community assembly of these microbial communities. We review important factors to consider in evaluating microbial community structure in the context of ecosystem recovery as revealed in studies of microbial succession: (1) variation in community assembly processes, (2) linkages to ecosystem function, and (3) measurable microbial community attributes. We seek to empower restoration ecology with microbial assembly and successional understandings that can generate actionable insights and vital contexts for ecosystem restoration efforts. [ABSTRACT FROM AUTHOR]

Peatland ecosystems cover only 3% of the world's land area; however, they store one-third of the global soil carbon (C). Microbial communities are the main drivers of C decomposition in peatlands, yet we have limited knowledge of their structure and function. While the microbial communities in the Northern Hemisphere peatlands are well documented, we have limited understanding of microbial community composition and function in the Southern Hemisphere peatlands, especially in Australia. We investigated the vertical stratification of prokaryote and fungal communities from Wellington Plains peatland in the Australian Alps. Within the peatland complex, bog peat was sampled from the intact peatland and dried peat from the degraded peatland along a vertical soil depth gradient (i.e., acrotelm, mesotelm, and catotelm). We analyzed the prokaryote and fungal community structure, predicted functional profiles of prokaryotes using PICRUSt, and assigned soil fungal guilds using FUNGuild. We found that the structure and function of prokaryotes were vertically stratified in the intact bog. Soil carbon, manganese, nitrogen, lead, and sodium content best explained the prokaryote composition. Prokaryote richness was significantly higher in the intact bog acrotelm compared to degraded bog acrotelm. Fungal composition remained similar across the soil depth gradient; however, there was a considerable increase in saprotroph abundance and decrease in endophyte abundance along the vertical soil depth gradient. The abundance of saprotrophs and plant pathogens was two-fold higher in the degraded bog acrotelm. Soil manganese and nitrogen content, electrical conductivity, and water table level (cm) best explained the fungal composition. Our results demonstrate that both fungal and prokaryote communities are shaped by soil abiotic factors and that peatland degradation reduces microbial richness and alters microbial functions. Thus, current and future changes to the environmental conditions in these peatlands may lead to altered microbial community structures and associated functions which may have implications for broader ecosystem function changes in peatlands. [ABSTRACT FROM AUTHOR]

The various climate scenarios consistently predict warming and drying of forests in Hungary. Soils play a significant role in the long-term sequestration of atmospheric CO2, while in other cases they can also become net carbon emitters. Therefore, it is important to know what can be expected regarding future changes in the carbon storage capacity of soils in forests. We used precipitation gradient studies to solve this problem, using a type of "space–time" substitution. In this research, we primarily examined the quality parameters of soil organic matter (SOM) to investigate how climate change transforms the ratio of the main SOM compound groups in soils. For our studies, we applied elemental and 13C and 15N isotopic ratio analysis, NMR analysis, FT-IR spectra analysis, thermogravimetric and differential thermal analyses to measure SOM chemistry in samples from different oak forests with contrasting mean annual precipitation from Central Europe. Our results showed that soil organic carbon (SOC) was lower in soils of humid forests due to the enhanced decomposition processes and the leaching of Ca, which stabilizes SOM; however, in particular, the amount of easily degradable SOM compounds (e.g., thermolabile SOM, O-alkyl carbon, carboxylic and carbonyl carbon) decreased. In dry forest soils, the amount of recalcitrant SOM (e.g., thermostable SOM, alkyl carbon, aromatic and phenolic carbon and organo–mineral complexes stabilized by Ca increased, but the amount of easily degradable SOM increased further. The main conclusion of our study is that SOC can increase in forests that become drier, compensating somewhat for the decrease in forest plant biomass. [ABSTRACT FROM AUTHOR]

Nitrogen and phosphorus can influence the stability of soil organic matter (SOM) and aggregate, which are important for ecosystem functions. However, understanding remains limited regarding the impact of nutrient addition on soil aggregate stability, aggregate‐relevant organic matter and nutrients in desert steppe. Here, we studied the variation of soil aggregate stability, nutrients, and the exchangeable cations distribution characteristics, and the chemical composition and thermal stability of SOM were analyzed using thermogravimetric (TG) and Fourier transformed infrared spectroscopy. Samples of soil were collected under four conditions, phosphorus addition (P), nitrogen addition (N), combined phosphorus and nitrogen addition (NP), and no addition (CK), from 0 to 10 cm depth over 4‐year experiments in desert steppe in northern China. The percentage of micro‐aggregates (0.25–0.053 mm) and large macroaggregates (>2 mm) dramatically increased by 34.2% and 18.1%, respectively, under the N treatment condition compared to the CK treatment, and micro‐aggregate content significantly increased under the P treatment, respectively. Nitrogen addition significantly increased the soil aggregate stability index, but the P addition reduced their value. The both macro‐aggregates (>0.25 mm) and silt‐clay (<0.053 mm) were preferentially enriched with soil nutrients and the exchangeable cations. The N and P addition was beneficial to nutrients accumulating in macro‐aggregates, and enhanced the aliphatic‐C and aromatic‐C abundances respectively. The TG‐T50 value (i.e., temperature when 50% of SOM is lost) increased after nutrient addition, indicating that the SOM has higher thermal stability, especially in the micro‐aggregates. The addition of N may have potentially a greater influence on aggregate stability through their influence exchangeable polyvalent cations (Ca2+ and Mg2+), and stability of SOM was influenced by chemical composition and exchangeable K+, Na+, Ca2+ contents in desert steppe. Overall, nutrient addition effects stability of SOM and aggregate by altering chemical composition and exchangeable cations in desert steppe in northern China. [ABSTRACT FROM AUTHOR]

Peatlands play an important role in global biogeochemical cycles and are essential for multiple ecosystem functions. Understanding the environmental drivers of microbial functioning and community structure can provide insights to enable effective and evidence‐based management. However, it remains largely unknown how microbial diversity contributes to the functioning of belowground processes. Addressing this gap in knowledge will provide a better understanding of microbial‐mediated processes in peatlands that are undergoing restoration or reclamation. This study assessed the changes in microbial community diversity and structure as well as soil function by measuring microbial respiration on a range of substrates from three natural fen types found in the Athabasca Oil Sands region of Alberta, Canada (a poor fen, a hypersaline fen, and a tree‐rich fen) and a nearby constructed fen undergoing reclamation following open pit mining. Overall, substrate induced respiration was significantly higher in the constructed fen. Alpha diversity of fungi and prokaryotes was highest in the tree‐rich fen, and the composition of microbial communities was significantly different between fens. Both fungal and prokaryotic communities were strongly related to pore water pH and temperature, with plant richness also contributing to the shape of fungal communities. In summary, microbial community structure reflects the underlying differences in soil condition across different fens but plays essential roles in the ecological functions of soil. These findings provide a new outlook for the management of peatlands undergoing post‐mining reclamation. Future research on peatland reclamation should consider the dynamic interaction between communities and ecosystem functionality, for which this study forms a useful baseline. [ABSTRACT FROM AUTHOR]

Testate (shell-building) amoebae, such as the Arcellinida (Amoebozoa), are useful bioindicators for climate change. Though past work has relied on morphological analyses to characterize Arcellinida diversity, genetic analyses revealed the presence of multiple cryptic species underlying morphospecies. Here, we design and deploy Arcellinida-specific primers for the SSU-rDNA gene to assess the community composition on the molecular level in a pilot study of two samplings from a New England fen: (1) 36-cm horizontal transects and vertical cores; and (2) 26-m horizontal transects fractioned into four size classes (2-10, 10-35, 35-100, and 100-300 μm). Analyses of these data show the following: (1) a considerable genetic diversity within Arcellinida, much of which comes from morphospecies lacking sequences on GenBank; (2) communities characterized by DNA (i.e. active + quiescent) are distinct from those characterized by RNA (i.e. active, indicator of biomass); (3) active communities on the surface tend to be more similar to one another than to core communities, despite considerable heterogeneity; and (4) analyses of communities fractioned by size find some lineages (OTUs) that are abundant in disjunct size categories, suggesting the possibility of life-history stages. Together, these data demonstrate the potential of these primers to elucidate the diversity of Arcellinida communities in diverse habitats., (© 2020 International Society of Protistologists.)

Warming and elevated CO 2 (eCO 2 ) are expected to facilitate vascular plant encroachment in peatlands. The rhizosphere, where microbial activity is fueled by root turnover and exudates, plays a crucial role in biogeochemical cycling, and will likely at least partially dictate the response of the belowground carbon cycle to climate changes. We leveraged the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment, to explore the effects of a whole-ecosystem warming gradient (+0°C to 9°C) and eCO 2 on vascular plant fine roots and their associated microbes. We combined trait-based approaches with the profiling of fungal and prokaryote communities in plant roots and rhizospheres, through amplicon sequencing. Warming promoted self-reliance for resource uptake in trees and shrubs, while saprophytic fungi and putative chemoorganoheterotrophic bacteria utilizing plant-derived carbon substrates were favored in the root zone. Conversely, eCO 2 promoted associations between trees and ectomycorrhizal fungi. Trees mostly associated with short-distance exploration-type fungi that preferentially use labile soil N. Additionally, eCO 2 decreased the relative abundance of saprotrophs in tree roots. Our results indicate that plant fine-root trait variation is a crucial mechanism through which vascular plants in peatlands respond to climate change via their influence on microbial communities that regulate biogeochemical cycles., (© 2024 The Authors. New Phytologist © 2024 New Phytologist Foundation.)

Soil water drainage is the main source of groundwater recharge and river flow. It is therefore a key process for water resource management. In this study, we evaluate the soil hydrology and the soil water drainage, simulated by the Interaction-Soil-Biosphere-Atmosphere (ISBA) land surface model currently used for hydrological applications from the watershed scale to the global scale. This evaluation is done using seven lysimeters from two long term model approach sites measuring hourly water dynamics between 2009 and 2019 in northeastern France. These 2-meter depth lysimeters are filled with different soil types and are either maintained bare soil or covered with vegetation. Four closed-form equations describing soil water retention and hydraulic conductivity functions, are tested: the commonly used equations from Brooks and Corey (1966) and van Genuchten (1980), a combination of the van Genuchten soil water retention function with the Brooks and Corey unsaturated hydraulic conductivity function, and, for the very first time in a Land Surface Model (LSM), a modified version of Van Genuchten equations, with a new hydraulic conductivity curve proposed by Iden et al. (2015). The results indicate a good performance by ISBA with the different closure equations in terms of soil volumetric water content and water mass. The drained flow at the bottom of the lysimeter is well simulated using Brooks and Corey (1966) while some weaknesses appear with van Genuchten (1980) due to the abrupt shape near saturation of its hydraulic conductivity function. The mixed form or the new van Genuchten hydraulic conductivity function from Iden et al. (2015) allows solving this problem and even improves the simulation of the drainage dynamic, especially for intense drainage events. The study also highlights the importance of the vertical heterogeneity of the soil hydrodynamic parameters to correctly simulate the drainage dynamic, as well as the primary influence of the parameters characterizing the shape of the soil water retention function. [ABSTRACT FROM AUTHOR]

Summary: Plants produce a wide diversity of metabolites. Yet, our understanding of how shifts in plant metabolites as a response to climate change feedback on ecosystem processes remains scarce. Here, we test to what extent climate warming shifts the seasonality of metabolites produced by Sphagnum mosses, and what are the consequences of these shifts for peatland C uptake.We used a reciprocal transplant experiment along a climate gradient in Europe to simulate climate change. We evaluated the responses of primary and secondary metabolites in five Sphagnum species and related their responses to gross ecosystem productivity (GEP).When transplanted to a warmer climate, Sphagnum species showed consistent responses to warming, with an upregulation of either their primary or secondary metabolite according to seasons. Moreover, these shifts were correlated to changes in GEP, especially in spring and autumn.Our results indicate that the Sphagnum metabolome is very plastic and sensitive to warming. We also show that warming‐induced changes in the seasonality of Sphagnum metabolites have consequences on peatland GEP. Our findings demonstrate the capacity for plant metabolic plasticity to impact ecosystem C processes and reveal a further mechanism through which Sphagnum could shape peatland responses to climate change. [ABSTRACT FROM AUTHOR]

(1) Ombrotrophic peat bogs provide valuable records of environmental change on long timescales but are rarely preserved near the major centers of industrial activity. Holcroft Moss is a rare example of a stratigraphically intact lowland peat bog in NW England, which provides a valuable opportunity to trace industrial impacts on vegetation in a sensitive environmental archive close to the early industrializing cities of Manchester and Liverpool. (2) We reconstructed environmental changes at Holcroft Moss before and after the Industrial Revolution using a decadal‐scale record of pollen, non‐pollen palynomorphs, microcharcoal, peat composition (organic content and ash‐free bulk density) and heavy metal content, constrained by a radiocarbon and SCP (spheroidal carbonaceous particle) chronology. We examine the relationship between abiotic and biotic environmental tracers using principal component analysis and evaluate the role of local and regional climatic and anthropogenic drivers using canonical redundancy analysis and partitioning of variation. (3) Results show significant changes in bog vegetation composition during the last 700 years. Prior to 1750 CE, climate and agro‐pastoral activity (grazing and fires) were the main drivers of vegetation change. Subsequently, regional coal‐fired industry contributed to major increases in atmospheric pollutants (dust, heavy metals, and acid deposition) that severely impacted vegetation, driving the decline of Sphagnum. Grasses rose to dominance in the 20th century associated especially with bog conversion and cumulative nitrogen deposition. Although atmospheric pollution significantly decreased in the post‐industrial era, vegetation has not returned to pre‐industrial conditions, reflecting the ongoing impact of global change drivers which pose challenges for conservation and restoration. (4) Synthesis. Paleoecological studies are needed to reveal the long‐term history of vegetation degradation and to offer guidelines for restoration and conservation practices. This study reconstructs the last 700 years of a peat bog located between Manchester and Liverpool, revealing the timing and nature of vegetation changes across the trajectory of early industrialization and eventual post‐industrial decline. Our study reveals the progressive dominance of regional anthropogenic forcing and highlights that the present‐day vegetation does not have past analogs within the last 700 years. Conservation measures favoring the reintroduction of Sphagnum are justified in redressing the major biological legacy of the Industrial Revolution, while steps to increase Calluna should also be considered in light of its resilience to dry and fire‐prone conditions. [ABSTRACT FROM AUTHOR]