| 1. |
- Acharya, Kamal Prasad, et al.
(författare)
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Latitudinal variation of life-history traits of an exotic and a native impatiens species in Europe
- 2017
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Ingår i: Acta Oecologica. - : Elsevier BV. - 1146-609X .- 1873-6238. ; 81, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the responses of invasive and native populations to environmental change is crucial for reliable predictions of invasions in the face of global change. While comparisons of responses across invasive species with different life histories have been performed before, comparing functional traits of congeneric native and invasive species may help to reveal driving factors associated with invasion. Here we compared morphological functional trait patterns of an invasive species (Impatiens parviflora) with its congeneric native species (I. noli-tangere) along an approximately 1600 km European latitudinal gradient from France (49 degrees 34'N) to Norway (63 degrees 40'N). Soil nitrogen was recorded during six weeks of the growing season, and light, soil moisture, and nutrient availability were estimated for each sampled population using community weighted means of indicator values for co-occurring species. Temperature data were gathered from nearby weather stations. Both the native and invasive species are taller at higher latitudes and this response is strongest in the invasive species. Seed mass and number of seeds per capsule increase in I. noli-tangere but decrease in I. parviflora towards higher latitudes. Surprisingly, plant height in the invasive I. parviflora decreases with increasing soil nitrogen availability. The latitudinal pattern in seed mass is positively related to temperature in I. noli-tangere and negatively in I. parviflora. Leaf area of both species decreases with increasing Ellenberg indicator values for nitrogen and light but increases with increasing soil moisture. Soil nitrogen concentrations and Ellenberg indicator values for nitrogen have significant positive (I. nolitangere) and negative (I. parviflora) effects on the number of seeds per capsule. Our results show that the native I. noli-tangere has efficient reproduction at its range edge while the invasive I. parviflora shows a marked decrease in seed size and seed number per capsule. These patterns are unrelated to the growth and obtained size of the plants: even low soil nitrogen availability in the north seemed not to limit plant growth and size. Our results suggest that the invasive I. parviflora tends to become more invasive at lower latitudes by producing heavier seeds and more seeds per capsule.
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| 2. |
- Albert, Aurélie, et al.
(författare)
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Seed dispersal by ungulates as an ecological filter : a trait-based meta-analysis
- 2015
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 124:9, s. 1109-1120
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Tidskriftsartikel (refereegranskat)abstract
- Plant communities are often dispersal-limited and zoochory can be an efficient mechanism for plants to colonize new patches of potentially suitable habitat. We predicted that seed dispersal by ungulates acts as an ecological filter - which differentially affects individuals according to their characteristics and shapes species assemblages - and that the filter varies according to the dispersal mechanism (endozoochory, fur-epizoochory and hoof-epizoochory). We conducted two-step individual participant data meta-analyses of 52 studies on plant dispersal by ungulates in fragmented landscapes, comparing eight plant traits and two habitat indicators between dispersed and non-dispersed plants. We found that ungulates dispersed at least 44% of the available plant species. Moreover, some plant traits and habitat indicators increased the likelihood for plant of being dispersed. Persistent or nitrophilous plant species from open habitats or bearing dry or elongated diaspores were more likely to be dispersed by ungulates, whatever the dispersal mechanism. In addition, endozoochory was more likely for diaspores bearing elongated appendages whereas epizoochory was more likely for diaspores released relatively high in vegetation. Hoof-epizoochory was more likely for light diaspores without hooked appendages. Fur-epizoochory was more likely for diaspores with appendages, particularly elongated or hooked ones. We thus observed a gradient of filtering effect among the three dispersal mechanisms. Endozoochory had an effect of rather weak intensity (impacting six plant characteristics with variations between ungulate-dispersed and non-dispersed plant species mostly below 25%), whereas hoof-epizoochory had a stronger effect (eight characteristics included five ones with above 75% variation), and fur-epizoochory an even stronger one (nine characteristics included six ones with above 75% variation). Our results demonstrate that seed dispersal by ungulates is an ecological filter whose intensity varies according to the dispersal mechanism considered. Ungulates can thus play a key role in plant community dynamics and have implications for plant spatial distribution patterns at multiple scales.
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| 3. |
- Auffret, Alistair G., et al.
(författare)
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HistMapR : Rapid digitization of historical land-use maps in R
- 2017
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Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 8:11, s. 1453-1457
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Tidskriftsartikel (refereegranskat)abstract
- Habitat destruction and degradation represent serious threats to biodiversity, and quantification of land-use change over time is important for understanding the consequences of these changes to organisms and ecosystem service provision. Comparing land use between maps from different time periods allows estimation of the magnitude of habitat change in an area. However, digitizing historical maps manually is time-consuming and analyses of change are usually carried out at small spatial extents or at low resolutions. HistMapR contains a number of functions that can be used to semi-automatically digitize historical land use according to a map's colours, as defined by the RGB bands of the raster image. We test the method on different historical land-use map series and compare results to manual digitizations. Digitization is fast, and agreement with manually digitized maps of around 80-90% meets common targets for image classification. We hope that the ability to quickly classify large areas of historical land use will promote the inclusion of land-use change into analyses of biodiversity, species distributions and ecosystem services.
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| 4. |
- Auffret, Alistair G., et al.
(författare)
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Spatial scale and specialization affect how biogeography and functional traits predict long-term patterns of community turnover
- 2017
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 31:2, s. 436-443
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Tidskriftsartikel (refereegranskat)abstract
- 1. Immigration, extirpation and persistence of individual populations of species are key processes determining community responses to environmental change. However, they are difficult to study over long time periods without corresponding historical and modern-day species occurrences.2. We used historical and present-day plant species occurrence data from two different spatial scales (resolutions) to investigate the plant community turnover during the 20th century in a Baltic Sea archipelago. Patterns of turnover were analysed in relation to plant functional traits relating to dispersal and competition/persistence, as well as biogeographical variables.3. Turnover was largely driven by interactions between functional traits and measures of area, connectivity and distance to mainland. However, the combinations of traits and biogeographical variables that were most important for predicting immigration and extirpation differed between data sets, and between species associated with grassland management and the entire species pool.4. Taller plants were more likely to persist regardless of scale and biogeography, reflecting the grazing abandonment that occurred in the study area. Interactions between dispersal traits and biogeography were related to immigrations when the entire species pool was considered. However, increased dispersal potential, a smaller island size and increasing distance to mainland combined to promote extirpations in management-associated species. A perennial life span and seed banking contributed to species persistence. At the larger spatial scale, trait-driven turnover was not mediated by the biogeographical context.5. We showed that it is important to consider functional traits, biogeographical variables and their interactions when analysing community turnover over time. Furthermore, we found that the understanding of how combinations of traits and biogeography predict turnover depends on the source and spatial scale of the available data, and the species pool analysed.
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| 5. |
- Auffret, Alistair G., et al.
(författare)
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Super-regional land-use change and effects on the grassland specialist flora
- 2018
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Habitat loss through land-use change is the most pressing threat to biodiversity worldwide. European semi-natural grasslands have suffered an ongoing decline since the early twentieth century, but we have limited knowledge of how grassland loss has affected biodiversity across large spatial scales. We quantify land-use change over 50-70 years across a 175,000 km(2) super-region in southern Sweden, identifying a widespread loss of open cover and a homogenisation of landscape structure, although these patterns vary considerably depending on the historical composition of the landscape. Analysing species inventories from 46,796 semi-natural grasslands, our results indicate that habitat loss and degradation have resulted in a decline in grassland specialist plant species. Local factors are the best predictors of specialist richness, but the historical landscape predicts present-day richness better than the contemporary landscape. This supports the widespread existence of time-lagged biodiversity responses, indicating that further species losses could occur in the future.
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| 6. |
- Auffret, Alistair G., et al.
(författare)
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The spatial and temporal components of functional connectivity in fragmented landscapes
- 2015
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44, s. s51-S59
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Tidskriftsartikel (refereegranskat)abstract
- Connectivity is key for understanding how ecological systems respond to the challenges of land-use change and habitat fragmentation. Structural and functional connectivity are both established concepts in ecology, but the temporal component of connectivity deserves more attention. Whereas functional connectivity is often associated with spatial patterns (spatial functional connectivity), temporal functional connectivity relates to the persistence of organisms in time, in the same place. Both temporal and spatial processes determine biodiversity responses to changes in landscape structure, and it is therefore necessary that all aspects of connectivity are considered together. In this perspective, we use a case study to outline why we believe that both the spatial and temporal components of functional connectivity are important for understanding biodiversity patterns in the present-day landscape, and how they can also help us to make better-informed decisions about conserving and restoring landscapes and improving resilience to future change.
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| 7. |
- Bagger-Sjöbäck, Dan, et al.
(författare)
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A Randomised, Double Blind Trial of N-Acetylcysteine for Hearing Protection during Stapes Surgery
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Background Otosclerosis is a disorder that impairs middle ear function, leading to conductive hearing loss. Surgical treatment results in large improvement of hearing at low sound frequencies, but high-frequency hearing often suffers. A likely reason for this is that inner ear sensory cells are damaged by surgical trauma and loud sounds generated during the operation. Animal studies have shown that antioxidants such as N-Acetylcysteine can protect the inner ear from noise, surgical trauma, and some ototoxic substances, but it is not known if this works in humans. This trial was performed to determine whether antioxidants improve surgical results at high frequencies. Methods We performed a randomized, double-blind and placebo-controlled parallel group clinical trial at three Swedish university clinics. Using block-stratified randomization, 156 adult patients undergoing stapedotomy were assigned to intravenous N-Acetylcysteine (150 mg/kg body weight) or matching placebo (1:1 ratio), starting one hour before surgery. The primary outcome was the hearing threshold at 6 and 8 kHz; secondary outcomes included the severity of tinnitus and vertigo. Findings One year after surgery, high-frequency hearing had improved 2.7 +/- 3.8 dB in the placebo group (67 patients analysed) and 2.4 +/- 3.7 dB in the treated group (72 patients; means +/- 95% confidence interval, p = 0.54; linear mixed model). Surgery improved tinnitus, but there was no significant intergroup difference. Post-operative balance disturbance was common but improved during the first year, without significant difference between groups. Four patients receiving N-Acetylcysteine experienced mild side effects such as nausea and vomiting. Conclusions N-Acetylcysteine has no effect on hearing thresholds, tinnitus, or balance disturbance after stapedotomy.
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| 8. |
- Caron, M. M., et al.
(författare)
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Divergent regeneration responses of two closely related tree species to direct abiotic and indirect biotic effects of climate change
- 2015
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 342, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Changing temperature and precipitation can strongly influence plant reproduction. However, also biotic interactions might indirectly affect the reproduction and recruitment success of plants in the context of climate change. Information about the interactive effects of changes in abiotic and biotic factors is essential, but still largely lacking, to better understand the potential effects of a changing climate on plant populations. Here we analyze the regeneration from seeds of Acer platanoides and Acer pseudoplatanus, two currently secondary forest tree species from seven regions along a 2200 km-wide latitudinal gradient in Europe. We assessed the germination, seedling survival and growth during two years in a common garden experiment where temperature, precipitation and competition with the understory vegetation were manipulated. A. platanoides was more sensitive to changes in biotic conditions while A. pseudoplatanus was affected by both abiotic and biotic changes. In general, competition reduced (in A. platanoides) and warming enhanced (in A. pseudoplatanus) germination and survival, respectively. Reduced competition strongly increased the growth of A. platanoides seedlings. Seedling responses were independent of the conditions experienced by the mother tree during seed production and maturation. Our results indicate that, due to the negative effects of competition on the regeneration of A. platanoides, it is likely that under stronger competition (projected under future climatic conditions) this species will be negatively affected in terms of germination, survival and seedling biomass. Climate-change experiments including both abiotic and biotic factors constitute a key step forward to better understand the response of tree species' regeneration to climate change.
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| 9. |
- Caron, M. M., et al.
(författare)
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Impacts of warming and changes in precipitation frequency on the regeneration of two Acer species
- 2015
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Ingår i: Flora. - : Elsevier BV. - 0367-2530 .- 1618-0585. ; 214, s. 24-33
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Tidskriftsartikel (refereegranskat)abstract
- Climate projections indicate that temperatures will increase by up to 4.5 degrees C in Europe by the end of this century, and that more extreme rainfall events and longer intervening dry periods will take place. Climate change will likely affect all phases of the life cycle of plants, but plant reproduction has been suggested to be especially sensitive. Here, using a combination of approaches (soil heaters and different provenances along a latitudinal gradient), we analyzed the regeneration from seeds of Acer platanoides and A. pseudoplatanus, two tree species considered, from a management point of view, of secondary relevance. We studied germination, seedling survival and growth in a full-factorial experiment including warming and changes in watering frequency. Both species responded to warming, watering frequency and seed provenance, with stronger (negative) effects of warming and provenance than of watering frequency. In general, the central provenances performed better than the northernmost and southern-most provenances. We also detected interactive effects between warming, watering frequency and/or seed provenance. Based on these results, both species are expected to show dissimilar responses to the changes in the studied climatic factors, but also the impacts of climate change on the different phases of plant regeneration may differ in direction and magnitude. In general increases in the precipitation, frequency will stimulate germination while warming will reduce survival and growth. Moreover, the frequent divergent responses of seedlings along the latitudinal gradient suggest that climate change will likely have heterogeneous impacts across Europe, with stronger impacts in the northern and southern parts of the species' distribution ranges.
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| 10. |
- Caron, M. M., et al.
(författare)
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Interacting effects of warming and drought on regeneration and early growth of Acer pseudoplatanus and A. platanoides
- 2015
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 17:1, s. 52-62
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A.platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A.platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A.platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A.pseudoplatanus in the face of climate change.
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