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Träfflista för sökning "WFRF:(Macek Petr) "

Search: WFRF:(Macek Petr)

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1.
  • Björkman, Anne, 1981, et al. (author)
  • Tundra Trait Team: A database of plant traits spanning the tundra biome
  • 2018
  • In: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 27:12, s. 1402-1411
  • Journal article (peer-reviewed)abstract
    • © 2018 The Authors Global Ecology and Biogeography Published by John Wiley & Sons Ltd Motivation: The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (>1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.
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2.
  • De Schuyter, Wim, et al. (author)
  • Declining potential nectar production of the herb layer in temperate forests under global change
  • 2024
  • In: Journal of Ecology. - 0022-0477 .- 1365-2745. ; 112:4, s. 832-847
  • Journal article (peer-reviewed)abstract
    • Wild pollinators are crucial for ecosystem functioning and human food production and often rely on floral resources provided by different (semi-) natural ecosystems for survival. Yet, the role of European forests, and especially the European forest herb layer, as a potential provider of floral resources for pollinators has scarcely been quantified.In this study, we measured the potential nectar production (PNP) of the forest herb layer using resurvey data across 3326 plots in temperate forests in Europe, with an average time interval of 41 years between both surveys in order to assess (i) the importance of the forest herb layer in providing nectar for wild pollinators, (ii) the intra-annual variation of PNP, (iii) the overall change in PNP between survey periods and (iv) the change in intra-annual variation of PNP between survey periods. The PNP estimates nectar availability based on the relative cover of different plant species in the forest herb layer. Although PNP overestimates actual nectar production, relative differences amongst plots provide a valid and informative way to analyse differences across time and space.Our results show that the forest herb layer has a large potential for providing nectar for wild pollinator communities, which is greatest in spring, with an average PNP of almost 16 g sugar/m2/year. However, this potential has drastically declined (mean plot-level decline >24%).Change in light availability, associated with shifts in canopy structure and canopy composition, is the key driver of temporal PNP changes.Synthesis. Our study shows that if management activities are carefully planned to sustain nectar-producing plant species for wild pollinators, European forest herb layers and European forests as a whole can play key roles in sustaining wild pollinator populations.
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3.
  • Tuomi, Maria, et al. (author)
  • Stomping in silence : Conceptualizing trampling effects on soils in polar tundra
  • 2021
  • In: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 35:2, s. 306-317
  • Research review (peer-reviewed)abstract
    • Ungulate trampling modifies soils and interlinked ecosystem functions across biomes. Until today, most research has focused on temperate ecosystems and mineral soils while trampling effects on cold and organic matter-rich tundra soils remain largely unknown. We aimed to develop a general model of trampling effects on soil structure, biota, microclimate and biogeochemical processes, with a particular focus on polar tundra soils. To reach this goal, we reviewed literature about the effects of trampling and physical disturbances on soils across biomes and used this to discuss the knowns and unknowns of trampling effects on tundra soils. We identified the following four pathways through which trampling affects soils: (a) soil compaction; (b) reductions in soil fauna and fungi; (c) rapid losses in vegetation biomass and cover; and (d) longer term shifts in vegetation community composition. We found that, in polar tundra, soil responses to trampling pathways 1 and 3 could be characterized by nonlinear dynamics and tundra-specific context dependencies that we formulated into testable hypotheses. In conclusion, trampling may affect tundra soil significantly but many direct, interacting and cascading responses remain unknown. We call for research to advance the understanding of trampling effects on soils to support informed efforts to manage and predict the functioning of tundra systems under global changes. A free Plain Language Summary can be found within the Supporting Information of this article.
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4.
  • Tzankova, Iana, et al. (author)
  • Adolescents’ Patterns of Citizenship Orientations and Correlated Contextual Variables : Results From a Two-Wave Study in Five European Countries
  • 2021
  • In: Youth & society. - : Sage Publications. - 0044-118X .- 1552-8499. ; 53:8, s. 1311-1334
  • Journal article (peer-reviewed)abstract
    • Studies on youth participation tend to characterize youth as either active and trustful or as passive and alienated. This cross-national and longitudinal study examines patterns of citizenship orientations characterized by both manifest and latent involvement differentiated by one’s position toward institutional politics (trustful or distrustful) among 1,914 adolescents from five European countries (53.5% female; Mage = 16.27). Demographic and proximal contextual correlates associated with different orientations at a 1-year interval were also assessed. Latent profile analysis identified four groups of citizenship orientations among adolescents: engaged trustful, engaged distrustful, unengaged trustful, and unengaged distrustful. Differences of membership likelihood were found for background characteristics (gender and family income), school characteristics (track, democratic climate, student participation, and its perceived quality), family, and peer norms of participation.
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5.
  • Verheyen, Kris, et al. (author)
  • 201 Combining Biodiversity Resurveys across Regions to Advance Global Change Research
  • 2017
  • In: BioScience. - : Oxford University Press (OUP). - 0006-3568 .- 1525-3244. ; 67:1, s. 73-83
  • Journal article (peer-reviewed)abstract
    • More and more ecologists have started to resurvey communities sampled in earlier decades to determine long-term shifts in community composition and infer the likely drivers of the ecological changes observed. However, to assess the relative importance of and interactions among multiple drivers, joint analyses of resurvey data from many regions spanning large environmental gradients are needed. In this article, we illustrate how combining resurvey data from multiple regions can increase the likelihood of driver orthogonality within the design and show that repeatedly surveying across multiple regions provides higher representativeness and comprehensiveness, allowing us to answer more completely a broader range of questions. We provide general guidelines to aid the implementation of multiregion resurvey databases. In so doing, we aim to encourage resurvey database development across other community types and biomes to advance global environmental change research.
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