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Träfflista för sökning "WFRF:(Hajek Michal) srt2:(2015-2019)"

Sökning: WFRF:(Hajek Michal) > (2015-2019)

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1.
  • Dengler, Juergen, et al. (författare)
  • GrassPlot - a database of multi-scale plant diversity in Palaearctic grasslands
  • 2018
  • Ingår i: Phytocoenologia. - : Schweizerbart. - 0340-269X. ; 48:3, s. 331-347
  • Tidskriftsartikel (refereegranskat)abstract
    • GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database " sPlot". Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board.
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2.
  • Dítě, Daniel, et al. (författare)
  • Glacial-relict symptoms in the Western Carpathian flora
  • 2018
  • Ingår i: Folia Geobotanica. - : Springer Science and Business Media LLC. - 1211-9520 .- 1874-9348. ; 53, s. 277-300
  • Tidskriftsartikel (refereegranskat)abstract
    • Glacial relicts have been regionally morecommon in glacial than in recent times. A rigorousassessment of which species are indeed glacial relictsis extremely difficult because direct evidence is untraceableor equivocal for many species.We aimed to identifyspecies of theWestern Carpathian flora (vascular plants,bryophytes and terrestrial lichens) that display apparentbiogeographical and ecological symptoms, suggesting awider regional or supra-regional distribution during glacialtimes, or at least before the middle-Holoceneclimate optimum. We worked with the premise thatexemplary relict species should tolerate continentaland/or arctic climates, should have large distributionranges with disjunctions, being regionally rare and ecologicallyconservative nowadays, should be associatedwith habitats that occurred during glacial times (tundra,steppe, peatland, open coniferous forest) and shoulddisplay a restriction of ecological niches in the studyregion. The assessed species were primarily those withboreo-continental or artcic-alpine distribution.We demonstrateda conspicuous gradient of glacial-relict symptoms,with Carex vaginata, Betula nana, Trichophorumpumilum, Nephroma arcticum, Saxifraga hirculus andCladonia stellaris topping the ranking. Based on thearbitrary ranking, 289 taxa can be considered highprobabilityrelicts. For only a minority of them, thereare any phylogeographical and/or palaeoecological dataavailable from the study area. Biogeographical and ecologicalsymptoms of 144 taxa suggest that they retreatedrapidly after the Last Glacial Maximum whereas otherspecies probably retreated later. The first principal componentof biogeographical symptoms sorted speciesfrom circumpolar arctic-alpine species of acidicpeatlands and wet tundra to strongly continental speciesof steppe, steppe-tundra and mineral-rich fens. Thisdifferentiation may mirror the altitudinal zonation ofglacial vegetation in the Western Carpathians.
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3.
  • Granath, Gustaf, et al. (författare)
  • Environmental and taxonomic controls of carbon and oxygen stable isotope composition in Sphagnum across broad climatic and geographic ranges
  • 2018
  • Ingår i: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 15:16, s. 5189-5202
  • Tidskriftsartikel (refereegranskat)abstract
    • Rain-fed peatlands are dominated by peat mosses (Sphagnum sp.), which for their growth depend on nutrients, water and CO2 uptake from the atmosphere. As the isotopic composition of carbon (C-12(,)13) and oxygen (O-16(,)18) of these Sphagnum mosses are affected by environmental conditions, Sphagnum tissue accumulated in peat constitutes a potential long-term archive that can be used for climate reconstruction. However, there is inadequate understanding of how isotope values are influenced by environmental conditions, which restricts their current use as environmental and palaeoenvironmental indicators. Here we tested (i) to what extent C and O isotopic variation in living tissue of Sphagnum is speciesspecific and associated with local hydrological gradients, climatic gradients (evapotranspiration, temperature, precipitation) and elevation; (ii) whether the C isotopic signature can be a proxy for net primary productivity (NPP) of Sphagnum; and (iii) to what extent Sphagnum tissue delta O-18 tracks the delta O-18 isotope signature of precipitation. In total, we analysed 337 samples from 93 sites across North America and Eurasia us ing two important peat-forming Sphagnum species (S. magellanicum, S. fuscum) common to the Holarctic realm. There were differences in delta C-13 values between species. For S. magellanicum delta C-13 decreased with increasing height above the water table (HWT, R-2 = 17 %) and was positively correlated to productivity (R-2 = 7 %). Together these two variables explained 46 % of the between-site variation in delta C-13 values. For S. fuscum, productivity was the only significant predictor of delta C-13 but had low explanatory power (total R-2 = 6 %). For delta O-18 values, approximately 90 % of the variation was found between sites. Globally modelled annual delta O-18 values in precipitation explained 69 % of the between-site variation in tissue delta O-18. S. magellanicum showed lower delta O-18 enrichment than S. fuscum (-0.83 %0 lower). Elevation and climatic variables were weak predictors of tissue delta O-18 values after controlling for delta O-18 values of the precipitation. To summarize, our study provides evidence for (a) good predictability of tissue delta O-18 values from modelled annual delta O-18 values in precipitation, and (b) the possibility of relating tissue delta C-13 values to HWT and NPP, but this appears to be species-dependent. These results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.
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4.
  • Idoia Biurrun, Idoia, et al. (författare)
  • GrassPlot v. 2.00 – first update on the database of multi-scale plant diversity in Palaearctic grasslands
  • 2019
  • Ingår i: Palaearctic Grasslands. - : Eurasian Dry Grassland Group (EDGG). - 2627-9827. ; :44, s. 26-47
  • Tidskriftsartikel (refereegranskat)abstract
    • GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). Following a previous Long Database Report (Dengler et al. 2018, Phytocoenologia 48, 331–347), we provide here the first update on content and functionality of GrassPlot. The current version (GrassPlot v. 2.00) contains a total of 190,673 plots of different grain sizes across 28,171 independent plots, with 4,654 nested-plot series including at least four grain sizes. The database has improved its content as well as its functionality, including addition and harmonization of header data (land use, information on nestedness, structure and ecology) and preparation of species composition data. Currently, GrassPlot data are intensively used for broad-scale analyses of different aspects of alpha and beta diversity in grassland ecosystems.
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