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Sökning: WFRF:(Heurich Marco)

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1.
  • Aikens, Ellen O., et al. (författare)
  • Wave-like Patterns of Plant Phenology Determine Ungulate Movement Tactics
  • 2020
  • Ingår i: Current Biology. - Cambridge : Cell Press. - 0960-9822 .- 1879-0445. ; 30:17, s. 3444-3449
  • Tidskriftsartikel (refereegranskat)abstract
    • Animals exhibit a diversity of movement tactics [1]. Tracking resources that change across space and time is predicted to be a fundamental driver of animal movement [2]. For example, some migratory ungulates (i.e., hooved mammals) closely track the progression of highly nutritious plant green-up, a phenomenon called "green-wave surfing" [3-5]. Yet general principles describing how the dynamic nature of resources determine movement tactics are lacking [6]. We tested an emerging theory that predicts surfing and the existence of migratory behavior will be favored in environments where green-up is fleeting and moves sequentially across large landscapes (i.e., wave-like green-up) [7]. Landscapes exhibiting wave-like patterns of green-up facilitated surfing and explained the existence of migratory behavior across 61 populations of four ungulate species on two continents (n = 1,696 individuals). At the species level, foraging benefits were equivalent between tactics, suggesting that each movement tactic is fine-tuned to local patterns of plant phenology. For decades, ecologists have sought to understand how animals move to select habitat, commonly defining habitat as a set of static patches [8, 9]. Our findings indicate that animal movement tactics emerge as a function of the flux of resources across space and time, underscoring the need to redefine habitat to include its dynamic attributes. As global habitats continue to be modified by anthropogenic disturbance and climate change [10], our synthesis provides a generalizable framework to understand how animal movement will be influenced by altered patterns of resource phenology.© 2020 Elsevier Inc.
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2.
  • Milotić, Tanja, et al. (författare)
  • Dung beetle assemblages, dung removal and secondary seed dispersal : data from a large-scale, multi-site experiment in the Western Palaearctic
  • 2018
  • Ingår i: Frontiers of Biogeography. - : eScholarship. - 1948-6596. ; 10:1-2
  • Tidskriftsartikel (refereegranskat)abstract
    • By manipulating faeces during feeding and breeding, dung beetles (Coleoptera: Scarabaeidae) fulfil important ecosystem functions in terrestrial ecosystems throughout the world. In a pan-European multi-site experiment (MSE), we estimated the ecosystem functions of dung removal and secondary seed dispersal by differing combinations of dung beetle functional groups. Therefore, we classified dung beetles into five functional groups according to their body size and dung manipulation method: dwellers, large and small tunnelers, and large and small rollers. Furthermore, we set up a dung beetle sampling database containing all sampled dung beetles during the project. By identifying dung beetle specimens to the species level, we obtained a detailed insight into the dung beetle communities at each study location. By establishing experimental plots allowing and inhibiting specific combinations of functional groups in the local dung beetle assemblage from removing dung and seeds, we estimated the role of each group in dung removal and secondary seed dispersal during a 4-week period. We performed all experiments in grazed (semi-) natural grasslands, and used different dung types (cattle, horse, sheep, goat or red deer) to match the herbivore species grazing in close vicinity of each of the study areas. Simultaneously, we sampled dung beetle assemblages by using pitfalls baited with the same dung types as used in the experiments. This data paper documents two datasets collected in the framework of this MSE project. All the experiments took place between 2013 and 2016 at 17 study sites in 10 countries and 11 biogeographic zones. The entire dung beetle sampling dataset was published as a sampling event dataset at GBIF. The dataset includes the sampling results of all 17 study sites, which contain 1,050 sampling events and 4,362 occurrence records of 94 species. The second dataset contains the results of the dung removal and secondary seed dispersal experiments in which we used 11 experimental treatments and the five dung types mentioned above. This experimental results dataset holds all experimental results of the MSE project (11,537 records), and was published in the online data repository Zenodo.
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3.
  • Milotic, Tanja, et al. (författare)
  • Functionally richer communities improve ecosystem functioning : dung removal and secondary seed dispersal by dung beetles in the Western Palaearctic
  • 2019
  • Ingår i: Journal of Biogeography. - : John Wiley & Sons. - 0305-0270 .- 1365-2699. ; 46:1, s. 70-82
  • Tidskriftsartikel (refereegranskat)abstract
    • Aim: In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal.Location: Seventeen grassland locations across the Western Palaearctic.Methods: We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro-invertebrates. By sampling the dung beetle community and measuring the remaining dung and seeds after the experiment, the impact of each functional group was estimated.Results: Dung beetle assemblages differed along a north-south and east-west gradient. Dwellers dominated northernmost sites, whereas at lower latitudes we observed more tunnellers and rollers indicating a functional shift. Resource specialists were more abundant in southern and eastern areas. Overall, functional group diversity enhanced dung removal. More dung (+46.9%) and seeds (+32.1%) were removed in the southern sites and tunnellers and rollers were more effective. At the northernmost sites, where tunnellers were scarce or absent, other soil macro-invertebrates removed the majority of dung.Main conclusions: The conservation of functionally complete dung beetle assemblages is crucial to maintain the ecosystem functions provided by dung beetles. Given the latitudinal variation in functional group diversity, it is reasonable to expect compositional changes due to climate change. These changes could lead to increased dung removal and a higher secondary seed dispersal rate in northern regions.
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4.
  • Nielsen, Michael Meinild, 1981-, et al. (författare)
  • Automatic mapping of standing dead trees after an insect outbreak using the Window Independent Context Segmentation method
  • 2014
  • Ingår i: Journal of forestry. - 0022-1201 .- 1938-3746. ; 112:6, s. 564-571
  • Tidskriftsartikel (refereegranskat)abstract
    • Since the 1980s, there has been an increase in the spruce bark beetle population in the Bavarian Forest National Park in southeastern Germany. There is a need for accurate and time-effective methods for monitoring the outbreak, because manual interpretation of image data is time-consuming and expensive. In this article, the window independent context segmentation method is used to map deadwood areas. The aim is to evaluate the method’s ability to monitor deadwood areas on a yearly basis. Two-color infrared scenes with a spatial resolution of 40 × 40 cm from 2001 and 2008 were used for the study. The method was found to be effective with an overall accuracy of 88% for the 2001 scene and 90% for the 2008 scene.
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5.
  • Peters, Wibke, et al. (författare)
  • Large herbivore migration plasticity along environmental gradients in Europe : life-history traits modulate forage effects
  • 2018
  • Ingår i: Oikos. - Chichester : Wiley-Blackwell Publishing Inc.. - 0030-1299 .- 1600-0706. ; 128:3, s. 416-429
  • Tidskriftsartikel (refereegranskat)abstract
    • The most common framework under which ungulate migration is studied predicts that it is driven by spatio–temporal variation in plant phenology, yet other hypotheses may explain differences within and between species. To disentangle more complex patterns than those based on single species/ single populations, we quantified migration variability using two sympatric ungulate species differing in their foraging strategy, mating system and physiological constraints due to body size. We related observed variation to a set of hypotheses. We used GPS-collar data from 537 individuals in 10 roe Capreolus capreolus and 12 red deer Cervus elaphus populations spanning environmental gradients across Europe to assess variation in migration propensity, distance and timing. Using time-to-event models, we explored how the probability of migration varied in relation to sex, landscape (e.g. topography, forest cover) and temporally-varying environmental factors (e.g. plant green-up, snow cover). Migration propensity varied across study areas. Red deer were, on average, three times more migratory than roe deer (56% versus 18%). This relationship was mainly driven by red deer males which were twice as migratory as females (82% versus 38%). The probability of roe deer migration was similar between sexes. Roe deer (both sexes) migrated earliest in spring. While territorial male roe deer migrated last in autumn, male and female red deer migrated around the same time in autumn, likely due to their polygynous mating system. Plant productivity determined the onset of spring migration in both species, but if plant productivity on winter ranges was sufficiently high, roe deer were less likely to leave. In autumn, migration coincided with reduced plant productivity for both species. This relationship was stronger for red deer. Our results confirm that ungulate migration is influenced by plant phenology, but in a novel way, that these effects appear to be modulated by species-specific traits, especially mating strategies. © 2018 The Authors. Oikos © 2018 Nordic Society Oikos
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