| 1. |
- Lembrechts, Jonas J., et al.
(författare)
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Comparing temperature data sources for use in species distribution models : From in-situ logging to remote sensing
- 2019
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 28:11, s. 1578-1596
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Tidskriftsartikel (refereegranskat)abstract
- Aim Although species distribution models (SDMs) traditionally link species occurrences to free-air temperature data at coarse spatio-temporal resolution, the distribution of organisms might instead be driven by temperatures more proximal to their habitats. Several solutions are currently available, such as downscaled or interpolated coarse-grained free-air temperatures, satellite-measured land surface temperatures (LST) or in-situ-measured soil temperatures. A comprehensive comparison of temperature data sources and their performance in SDMs is, however, currently lacking. Location Northern Scandinavia. Time period 1970-2017. Major taxa studied Higher plants. Methods We evaluated different sources of temperature data (WorldClim, CHELSA, MODIS, E-OBS, topoclimate and soil temperature from miniature data loggers), differing in spatial resolution (from 1 '' to 0.1 degrees), measurement focus (free-air, ground-surface or soil temperature) and temporal extent (year-long versus long-term averages), and used them to fit SDMs for 50 plant species with different growth forms in a high-latitudinal mountain region. Results Differences between these temperature data sources originating from measurement focus and temporal extent overshadow the effects of temporal climatic differences and spatio-temporal resolution, with elevational lapse rates ranging from -0.6 degrees C per 100 m for long-term free-air temperature data to -0.2 degrees C per 100 m for in-situ soil temperatures. Most importantly, we found that the performance of the temperature data in SDMs depended on the growth forms of species. The use of in-situ soil temperatures improved the explanatory power of our SDMs (R-2 on average +16%), especially for forbs and graminoids (R-2 +24 and +21% on average, respectively) compared with the other data sources. Main conclusions We suggest that future studies using SDMs should use the temperature dataset that best reflects the ecology of the species, rather than automatically using coarse-grained data from WorldClim or CHELSA.
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| 2. |
- Papastamatiou, Yannis P., et al.
(författare)
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Sharks surf the slope : Current updrafts reduce energy expenditure for aggregating marine predators
- 2021
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 90:10, s. 2302-2314
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Tidskriftsartikel (refereegranskat)abstract
- An animal's energy landscape considers the power requirements associated with residing in or moving through habitats. Within marine environments, these landscapes can be dynamic as water currents will influence animal power requirements and can change rapidly over diel and tidal cycles. In channels and along slopes with strong currents, updraft zones may reduce energy expenditure of negatively buoyant fishes that are also obligate swimmers. Despite marine predators often residing within high-current area, no study has investigated the potential role of the energetic landscape in driving such habitat selectivity. Over 500 grey reef sharks Carcharhinus amblyrhynchos reside in the southern channel of Fakarava Atoll, French Polynesia. We used diver observations, acoustic telemetry and biologging to show that sharks use regions of predicted updrafts and switch their core area of space use based on tidal state (incoming versus outgoing). During incoming tides, sharks form tight groups and display shuttling behaviour (moving to the front of the group and letting the current move them to the back) to maintain themselves in these potential updraft zones. During outgoing tides, group dispersion increases, swimming depths decrease and shuttling behaviours cease. These changes are likely due to shifts in the nature and location of the updraft zones, as well as turbulence during outgoing tides. Using a biomechanical model, we estimate that routine metabolic rates for sharks may be reduced by 10%-15% when in updraft zones. Grey reef sharks save energy using predicted updraft zones in channels and 'surfing the slope'. Analogous to birds using wind-driven updraft zones, negatively buoyant marine animals may use current-induced updraft zones to reduce energy expenditure. Updrafts should be incorporated into dynamic energy landscapes and may partially explain the distribution, behaviour and potentially abundance of marine predators.
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| 3. |
- Wasof, Safaa, et al.
(författare)
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Dominance of individual plant species is more important than diversity in explaining plant biomass in the forest understorey
- 2018
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Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 29:3, s. 521-531
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Tidskriftsartikel (refereegranskat)abstract
- Questions: How does plant community diversity influence variation in plant biomass? There are two competing hypotheses: the biomass ratio' hypothesis, where biomass is influenced by the abundance and traits of the most dominant species, and the diversity' hypothesis, where the diversity of organisms influences biomass through mechanisms such as niche complementarity. However, no studies have tested which one of these two hypotheses better explains the variation in plant biomass in the forest understorey.Location: Temperate deciduous forests in northern France.Methods: For the forest understorey, we assessed species diversity and biomass as well as soil and light conditions in 133 forest plots of 100m(2) each. Using mixed-effect models and after controlling for potential confounding factors, we tested the biomass ratio' hypothesis by relating the relative abundance of the most dominant species across our study sites and the CWM of plant traits (leaf area and plant height) to biomass. The diversity' hypothesis was tested by relating biomass to various measures of taxonomic, functional and phylogenetic diversity.Results: Biomass of the forest understorey was mainly related to the relative abundance and the trait values of the most dominant species, supporting the biomass ratio' hypothesis. In contrast to the diversity' hypothesis, functional diversity indices had a negative impact on biomass. We found no contribution of taxonomic or phylogenetic diversity indices.Conclusion: The abundance and traits of the most dominant species matter more than taxonomic, functional or phylogenetic diversity of the forest understorey in explaining its biomass. Thus, there is a need for experiments that aim to fully understand keystone species' responses to on-going changing biotic and abiotic conditions and to predict their effects on ecosystem functioning and processes.
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