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  • Journals
  • Articles  (6)
  • Copernicus  (2)
  • Naturalis Biodiversity Center  (2)
  • GEOMAR  (1)
  • Institute of Electrical and Electronics Engineers (IEEE)  (1)
  • 2020-2024  (6)
  • 2021  (6)
  • 1
    Publication Date: 2023-06-21
    Description: Modern digital scientific workflows - often implying Big Data challenges - require data infrastructures and innovative data science methods across disciplines and technologies. Diverse activities within and outside HGF deal with these challenges, on all levels. The series of Data Science Symposia fosters knowledge exchange and collaboration in the Earth and Environment research community. We invited contributions to the overarching topics of data management, data science and data infrastructures. The series of Data Science Symposia is a joint initiative by the three Helmholtz Centers HZG, AWI and GEOMAR Organization: Hela Mehrtens and Daniela Henkel (GEOMAR)
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 2
    Publication Date: 2024-01-30
    Description: Methane emissions from boreal and arctic wetlands, lakes, and rivers are expected to increase in response to warming and associated permafrost thaw. However, the lack of appropriate land cover datasets for scaling field-measured methane emissions to circumpolar scales has contributed to a large uncertainty for our understanding of present-day and future methane emissions. Here we present the Boreal–Arctic Wetland and Lake Dataset (BAWLD), a land cover dataset based on an expert assessment, extrapolated using random forest modelling from available spatial datasets of climate, topography, soils, permafrost conditions, vegetation, wetlands, and surface water extents and dynamics. In BAWLD, we estimate the fractional coverage of five wetland, seven lake, and three river classes within 0.5 × 0.5∘ grid cells that cover the northern boreal and tundra biomes (17 % of the global land surface). Land cover classes were defined using criteria that ensured distinct methane emissions among classes, as indicated by a co-developed comprehensive dataset of methane flux observations. In BAWLD, wetlands occupied 3.2 × 106 km2 (14 % of domain) with a 95 % confidence interval between 2.8 and 3.8 × 106 km2. Bog, fen, and permafrost bog were the most abundant wetland classes, covering ∼ 28 % each of the total wetland area, while the highest-methane-emitting marsh and tundra wetland classes occupied 5 % and 12 %, respectively. Lakes, defined to include all lentic open-water ecosystems regardless of size, covered 1.4 × 106 km2 (6 % of domain). Low-methane-emitting large lakes (〉10 km2) and glacial lakes jointly represented 78 % of the total lake area, while high-emitting peatland and yedoma lakes covered 18 % and 4 %, respectively. Small (〈0.1 km2) glacial, peatland, and yedoma lakes combined covered 17 % of the total lake area but contributed disproportionally to the overall spatial uncertainty in lake area with a 95 % confidence interval between 0.15 and 0.38 × 106 km2. Rivers and streams were estimated to cover 0.12  × 106 km2 (0.5 % of domain), of which 8 % was associated with high-methane-emitting headwaters that drain organic-rich landscapes. Distinct combinations of spatially co-occurring wetland and lake classes were identified across the BAWLD domain, allowing for the mapping of “wetscapes” that have characteristic methane emission magnitudes and sensitivities to climate change at regional scales. With BAWLD, we provide a dataset which avoids double-accounting of wetland, lake, and river extents and which includes confidence intervals for each land cover class. As such, BAWLD will be suitable for many hydrological and biogeochemical modelling and upscaling efforts for the northern boreal and arctic region, in particular those aimed at improving assessments of current and future methane emissions. Data are freely available at https://doi.org/10.18739/A2C824F9X (Olefeldt et al., 2021).
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 3
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    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 46, pp. 116-128
    Publication Date: 2024-04-08
    Description: Several plant pathogenic Parastagonospora species have been identified infecting wheat and other cereals over the past 50 years. As new lineages were discovered, naming conventions grew unwieldy and the relationships with previously recognized species remained unclear. We used genome sequencing to clarify relationships among these species and provided new names for most of these species. Six of the nine described Parastagonospora species were recovered from wheat, with five of these species coming from Iran. Genome sequences revealed that three strains thought to be hybrids between P. nodorum and P. pseudonodorum were not actually hybrids, but rather represented rare gene introgressions between those species. Our data are consistent with the hypothesis that P. nodorum originated as a pathogen of wild grasses in the Fertile Crescent, then emerged as a wheat pathogen via host-tracking during the domestication of wheat in the same region. The discovery of a diverse array of Parastagonospora species infecting wheat in Iran suggests that new wheat pathogens could emerge from this region in the future.
    Keywords: Ecology ; Evolution ; Behavior and Systematics
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
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  • 4
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    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 47, pp. 45-105
    Publication Date: 2024-04-09
    Description: The current list of Chinese quarantine pests includes 130 fungal species. However, recent changes in the taxonomy of fungi following the one fungus = one name initiative and the implementation of DNA phylogeny in taxonomic revisions, resulted in many changes of these species names, necessitating an update of the current list. In addition, many quarantine fungi lack modern morphological descriptions and authentic DNA sequences, posing significant challenges for the development of diagnostic protocols. The aim of the present study was to review the taxonomy and names of the 33 Chinese quarantine fungi in Dothideomycetes, and provide reliable DNA barcodes to facilitate rapid identification. Of these, 23 names were updated according to the single name nomenclature system, including one new combination, namely Cophinforma tumefaciens comb. nov. (syn. Sphaeropsis tumefaciens). On the basis of phylogenetic analyses and morphological comparisons, a new genus Xenosphaeropsis is introduced to accommodate the monotypic species Xenosphaeropsis pyriputrescens comb. nov. (syn. Sphaeropsis pyriputrescens), the causal agent of a post-harvest disease of pears. Furthermore, four lectotypes (Ascochyta petroselini, Mycosphaerella ligulicola, Physalospora laricina, Sphaeria lingam), three epitypes (Ascochyta petroselini, Phoma lycopersici, Sphaeria lingam), and two neotypes (Ascochyta pinodella, Deuterophoma tracheiphila) are designated to stabilise the use of these names. A further four reference strains are introduced for Cophinforma tumefaciens, Helminthosporium solani, Mycocentro spora acerina, and Septoria linicola. In addition, to assist future studies on these important pathogens, we sequenced and assembled whole genomes for 17 species, including Alternaria triticina, Boeremia foveata, B. lycopersici, Cladosporium cucumerinum, Didymella glomerata, Didymella pinodella, Diplodia mutila, Helminthosporium solani, Mycocentrospora acerina, Neofusicoccum laricinum, Parastagonospora pseudonodorum, Plenodomus libanotidis, Plenodomus lingam, Plenodomus tracheiphilus, Septoria petroselini, Stagonosporopsis chrysanthemi, and Xenosphaeropsis pyriputrescens.
    Keywords: Ecology ; Evolution ; Behavior and Systematics ; Chinese quarantine fungi ; DNA barcodes ; genomes ; morphology ; new taxa ; phylogeny ; plant pathogens ; typification
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
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  • 5
    Publication Date: 2024-04-11
    Description: 〈jats:p〉Abstract. The risk of carbon emissions from permafrost ground is linked to ground temperature and thus in particular to thermal insulation by vegetation and organic soil layers in summer and snow cover in winter. This ground insulation is strongly influenced by the presence of large herbivorous animals browsing for food. In this study, we examine the potential impact of large herbivore presence on the ground carbon storage in thermokarst landscapes of northeastern Siberia. Our aim is to understand how intensive animal grazing may affect permafrost thaw and hence organic matter decomposition, leading to different ground carbon storage, which is significant in the active layer. Therefore, we analysed sites with differing large herbivore grazing intensity in the Pleistocene Park near Chersky and measured maximum thaw depth, total organic carbon content and decomposition state by δ13C isotope analysis. In addition, we determined sediment grain size composition as well as ice and water content. We found the thaw depth to be shallower and carbon storage to be higher in intensively grazed areas compared to extensively and non-grazed sites in the same thermokarst basin. The intensive grazing presumably leads to a more stable thermal ground regime and thus to increased carbon storage in the thermokarst deposits and active layer. However, the high carbon content found within the upper 20 cm on intensively grazed sites could also indicate higher carbon input rather than reduced decomposition, which requires further studies. We connect our findings to more animal trampling in winter, which causes snow disturbance and cooler winter ground temperatures during the average annual 225 days below freezing. This winter cooling overcompensates ground warming due to the lower insulation associated with shorter heavily grazed vegetation during the average annual 140 thaw days. We conclude that intensive grazing influences the carbon storage capacities of permafrost areas and hence might be an actively manageable instrument to reduce net carbon emission from these sites. 〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , notRev
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  • 6
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    Institute of Electrical and Electronics Engineers (IEEE)
    In:  EPIC3IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Institute of Electrical and Electronics Engineers (IEEE), 14, pp. 4894-4914, ISSN: 1939-1404
    Publication Date: 2023-12-21
    Description: icrowave radiometry has provided valuable spaceborne observations of Earth’s geophysical properties for decades. The recent SMOS, Aquarius, and SMAP satellites have demonstrated the value of measurements at 1400 MHz for observ- ing surface soil moisture, sea surface salinity, sea ice thickness, soil freeze/thaw state, and other geophysical variables. However, the information obtained is limited by penetration through the subsur- face at 1400 MHz and by a reduced sensitivity to surface salinity in cold or wind-roughened waters. Recent airborne experiments have shown the potential of brightness temperature measurements from 500–1400 MHz to address these limitations by enabling sensing of soil moisture and sea ice thickness to greater depths, sensing of temperature deep within ice sheets, improved sensing of sea salinity in cold waters, and enhanced sensitivity to soil moisture under veg- etation canopies. However, the absence of significant spectrum re- served for passive microwave measurements in the 500–1400 MHz band requires both an opportunistic sensing strategy and systems for reducing the impact of radio-frequency interference. Here, we summarize the potential advantages and applications of 500–1400 MHz microwave radiometry for Earth observation and review recent experiments and demonstrations of these concepts. We also describe the remaining questions and challenges to be addressed in advancing to future spaceborne operation of this technology along with recommendations for future research activities.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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