Change search
Refine search result
12 51 - 80 of 80
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51.
    Lönnell, Niklas
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sundberg, Sebastian
    Norros, Veera
    Rannik, Üllar
    Johansson, Victor
    Ovaskainen, Otso
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Colonization patterns of a wind-dispersed moss in relation to modelled dispersal based on meteorological data.Manuscript (preprint) (Other academic)
  • 52. Medina, Rafael
    et al.
    Yang, Liu
    Wang, Li-Song
    Guo, Shuiliang
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Goffinet, Bernard
    DNA based revised geographic circumscription of species of Physcomitrella s.l. (Funariaceae): P. patens new to East Asia and P. magdalenae new to East Africa2015In: The Bryologist, ISSN 0007-2745, E-ISSN 1938-4378, Vol. 118, no 1, p. 22-31Article in journal (Refereed)
    Abstract [en]

    Physcomitrella, as traditionally defined, accommodates certain Funariaceae with immersed and cleistocarpous capsules. Recent molecular inferences revealed that the three or four taxa typically recognized within Physcomitrella did not arise from a unique common ancestor, and hence that their morphological similarities likely resulted from convergence, while one potential taxon, P. patens subsp. californica (=Physcomitridium readeri s.l.), is currently regarded as a polyphyletic entity, making Physcomitridium polyphyletic. Following recent discoveries that would greatly expand the known range of two taxa, we sampled populations of Physcomitrella s.l. from all main geographic regions, and sequenced the nuclear ITS regions and four plastid loci to assess the geographic circumscription of each clade. We recovered three unambiguous monophyletic entities matching the three morphotypes recognized by Fife, each with a distinct geographic range: Physcomitrella patens s.str. with a range in Europe and North America extended to East Asia (China); P. magdalenae with a range from West and Central Africa extended eastwards to Ethiopia; and Physcomitridium (Physcomitrella) readeri from western Europe and western North America to Japan and Australia, plus a doubtful occurrence in China. Although the distinction of P. californica from P. readeri remains doubtful, we reject the hypothesis that Physcomitridium is polyphyletic, arguing that this resulted from a misidentification of the sequenced voucher.

  • 53.
    Meineri, Eric
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Dahlberg, C. Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Using Gaussian Bayesian Networks to disentangle direct and indirect associations between landscape physiography, environmental variables and species distribution2015In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 313, p. 127-136Article in journal (Refereed)
    Abstract [en]

    Landscape physiography affects temperature, soil moisture and solar radiation. In turn, these variables are thought to determine how species are distributed across landscapes. Systems involving direct and indirect associations between variables can be described using path models. However, studies applying these to species distribution modelling are rare. Bayesian Networks are path models designed to represent associations across observed variables. Here, we demonstrate the use of Bayesian Networks to disentangle the direct and indirect associations between landscape physiography, soil moisture, solar radiation, temperature and the distribution patterns of four plants at their northern range limit in Sweden. Fine scale variations in maximum temperatures were associated with variations in elevation, distance to coast and solar radiation. In contrast, fine scale variations in minimum temperature were associated with distance to coast, cold air drainage and soil moisture. These associations between landscape physiography and minimum and maximum temperature were predicted, furthermore, to be associated with growing season length, growing degree day and ultimately species distributions. All species were indirectly associated with aspect through their responses to either solar radiation or temperature. The models demonstrated strong indirect associations between landscape physiography and species distributions. The models suggested that local variation in light can be as important as temperature for species distributions. Disentangling the direct and indirect associations between landscape physiography, environmental variables and species distribution can provide new and important insights into how landscape components are linked to species distributions.

  • 54.
    Meineri, Eric
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Fine-grain, large-domain climate models based on climate station and comprehensive topographic information improve microrefugia detection2017In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, no 8, p. 1003-1013Article in journal (Refereed)
    Abstract [en]

    Large-domain species distribution models (SDMs) fail to identify microrefugia, as they are based on climate estimates that are either too coarse or that ignore relevant topographic climate-forcing factors. Climate station data are considered inadequate to produce such estimates, a viewpoint we challenge here. Using climate stations and topographic data, we developed three sets of large-domain (450 000 km(2)), fine-grain (50m) temperature grids accounting for different levels of topographic complexity. Using these fine-grain grids and the Worldclim data, we fitted SDMs for 78 alpine species over Sweden, and assessed over-versus underestimations of local extinction and area of microrefugia by comparing modelled distributions at species' rear edges. Accounting for well-known topographic climate-forcing factors improved our ability to model fine-scale climate, despite using only climate station data. This approach captured the effect of cool air pooling, distance to sea, and relative humidity on local-scale temperature, but the effect of solar radiation could not be accurately accounted for. Predicted extinction rate decreased with increasing spatial resolution of the climate models and with increasing number of topographic climate-forcing factors accounted for. About half of the microrefugia detected in the most topographically complete models were not detected in the coarser SDMs and in the models calibrated from climate variables extracted from elevation only. Although major limitations remain, climate station data can potentially be used to produce fine-grain topoclimate grids, opening up the opportunity to model local-scale ecological processes over large domains. Accounting for the topographic complexity encountered within landscapes permits the detection of microrefugia that would otherwise remain undetected. Topographic heterogeneity is likely to have a massive impact on species persistence, and should be included in studies on the effects of climate change.

  • 55.
    Moor, Helen
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Norberg, Jon
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Predicting climate change effects on wetland ecosystem services using species distribution modeling and plant functional traits2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, p. 113-126Article in journal (Refereed)
    Abstract [en]

    Wetlands provide multiple ecosystem services, the sustainable use of which requires knowledge of the underlying ecological mechanisms. Functional traits, particularly the community-weighted mean trait (CWMT), provide a strong link between species communities and ecosystem functioning. We here combine species distribution modeling and plant functional traits to estimate the direction of change of ecosystem processes under climate change. We model changes in CWMT values for traits relevant to three key services, focusing on the regional species pool in the Norrstrom area (central Sweden) and three main wetland types. Our method predicts proportional shifts toward faster growing, more productive and taller species, which tend to increase CWMT values of specific leaf area and canopy height, whereas changes in root depth vary. The predicted changes in CWMT values suggest a potential increase in flood attenuation services, a potential increase in short (but not long)-term nutrient retention, and ambiguous outcomes for carbon sequestration.

  • 56.
    Moor, Helen
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Rydin, Håkan
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nilsson, Mats B.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Norberg, Jon
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Towards a trait-based ecology of wetland vegetation2017In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 105, no 6, p. 1623-1635Article, review/survey (Refereed)
    Abstract [en]

    1. Functional traits mechanistically capture plant responses to environmental gradients as well as plant effects on ecosystem functioning. Yet most trait-based theory stems from terrestrial systems and extension to other habitats can provide new insights. 2. Wetlands differ from terrestrial systems in conditions (e.g. soil water saturation, anoxia, pH extremes), plant adaptations (e.g. aerenchyma, clonality, ubiquity of bryophytes) and important processes (e.g. denitrification, peat accumulation, methane emission). Wetland plant adaptations and trait (co-)variation can be situated along major plant trait trade-off axes (e.g. the resource economics spectrum), but soil saturation represents a complex stress gradient beyond a simple extension of commonly studied water availability gradients. 3. Traits that affect ecosystem functioning overlap with patterns in terrestrial systems. But wetland-specific traits that mediate plant effects on soil redox conditions, microbial communities and on water flow, as well as trait spectra of mosses, vary among wetland types. 4. Synthesis. With increasing availability of quantitative plant traits a trait-based ecology of wetlands is emerging, with the potential to advance process-based understanding and prediction. We provide an interactive cause-and-effect framework that may guide research efforts to disentangle the multiple interacting processes involved in scaling from environmental conditions to ecosystem functioning via plant communities.

  • 57.
    Moor, Helen
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Rydin, Håkan
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nilsson, Mats B.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Norberg, Jon
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Towards a trait-based ecology of wetland vegetationManuscript (preprint) (Other academic)
    Abstract [en]

    1. Functional traits mechanistically capture plant responses to environmental gradients as well as plant effects on ecosystem functioning. Yet most trait-based theory stems from terrestrial systems and extension to other habitats can provide new insights.

    2. Wetlands differ from terrestrial systems in conditions (e.g. soil water saturation, anoxia, pH extremes), plant adaptations (e.g. aerenchyma, clonality, ubiquity of bryophytes) and important processes (e.g. denitrification, peat accumulation, methane emission). Wetland plant adaptations and trait (co-)variation can be situated along major plant trait trade-off axes (e.g. the resource economics spectrum), but soil saturation represents a complex stress gradient beyond a simple extension of commonly studied water availability gradients.

    3. Traits that affect ecosystem functioning overlap with patterns in terrestrial systems. But wetland-specific traits that mediate plant effects on soil redox conditions, microbial communities and on water flow, as well as trait spectra of mosses, vary among wetland types.

    4. Synthesis: With increasing availability of quantitative plant traits a trait-based ecology of wetlands is emerging, with the potential to advance process-based understanding and prediction. We provide an interactive cause-and-effect framework that may guide research efforts to disentangle the multiple interacting processes involved in scaling from environmental conditions to ecosystem functioning via plant communities. 

  • 58. Patino, Jairo
    et al.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Gonzalez-Mancebo, Juana M.
    Effect of forest clear-cutting on subtropical bryophyte communities in waterfalls, on dripping walls, and along streams2010In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 20, no 6, p. 1648-1663Article in journal (Refereed)
    Abstract [en]

    Forested freshwater ecosystems worldwide are threatened by a number of anthropogenic disturbances, such as water pollution and canalization. Transient or permanent deforestation can also be a serious threat to organisms in forested watersheds, but its effects on different types of freshwater systems has been little studied. We investigated lotic bryophyte communities on rock and soil in subtropical cloud laurel forests on La Gomera Island in the Canary Islands, Spain, and asked whether the response to forest clear-cutting varied among the communities associated with dripping walls, streams, and waterfalls. We compared three successional forest stages: ancient forests (>250 years), young forests (20-50 years after clear-cutting), and open stands (5-15 years after clear-cutting). In each of 56 study sites we sampled general vegetation and substrate data in a 0.01-ha plot and took composition data of bryophyte species in 3 + 3 subplots of 1 x 1 m. The general pattern of decline in species richness and change in species composition after forest clear-cutting was stronger for streamside assemblages compared to assemblages on dripping walls and in waterfalls. The change in species numbers on rocks was larger than that on soils, because a guild of species growing on soil (but not on rocks) were favored by disturbance and thus increased in the disturbed sites. Most of the sensitive species could be classified as typical laurel forest species. Mosses were generally more tolerant to forest clear-cutting than were liverworts. We suggest that streamsides are more sensitive to disturbance than waterfalls and dripping walls because of a larger variation in microclimate before than after clear-cutting and because they are more easily invaded by early-successional species (both bryophytes and highly competitive vascular plants). We propose that special care should be taken along small streams within disturbed watersheds if bryophyte assemblages and threatened species should be protected. The susceptibility to anthropogenic pressures is probably rather high in ecosystems that do not regularly experience large-scale stand-replacing disturbances, especially on oceanic islands because of isolation and a small total habitat area for focal organisms.

  • 59. Rancka, Birte
    et al.
    von Proschwitz, Ted
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Götmark, Frank
    Conservation Thinning in Secondary Forest: Negative but Mild Effect on Land Molluscs in Closed-Canopy Mixed Oak Forest in Sweden2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 3, article id e0120085Article in journal (Refereed)
    Abstract [en]

    Secondary succession is changing the character of many temperate forests and often leads to closed-canopy stands. In such forests set aside for conservation, habitat management alternatives need to be tested experimentally, but this is rarely done. The Swedish Oak Project compares two often debated alternatives: minimal intervention and non-traditional active management (conservation thinning) on plots of each type replicated at 25 sites. We study responses of several taxa, and here report results for land molluscs. They are considered to be sensitive to more open, drier forest and we predicted a negative effect of the thinning (26% reduction of the basal area; mean value for 25 experimental forests). We sampled molluscs in the litter in ten 20 x 25 cm subplots, and by standardised visual search, in each plot. In total, we recorded 53 species of snails and slugs (24 369 individuals) and the mean species richness in plots was 17. Two seasons after thinning, mean (+/- SE) species richness had decreased by 1.4 (+/- 0.9) species in thinning plots, but increased by 0.7 (+/- 1.0) species in minimal intervention plots, a significant but small change with considerable variation among sites. In matched comparisons with minimal intervention, thinning reduced the overall abundance of molluscs. Most species responded negatively to thinning - but only five of the 53 species were significantly affected, and reproduction seemed to be negatively affected in only one species. An ordination analysis did not reveal any particular change in the species community due to thinning. Thus, the negative effect of conservation thinning on land molluscs was apparently mild - one reason was that many trees, shrubs and other forest structures remained after the treatment. Conservation thinning may be recommended, since other taxa are favoured, but minimal intervention is also a useful form of management for molluscs and saproxylic taxa.

  • 60. Ranlund, Åsa
    et al.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Johansson, Victor
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Swedish University of Agricultural Sciences, Sweden.
    Jonsson, Fredrik
    Nordin, Ulrika
    Gustafsson, Lena
    Epiphytic lichen responses to environmental change due to clear-cutting differ among tree taxa2018In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 29, no 6, p. 1065-1074Article in journal (Refereed)
    Abstract [en]

    Question Many species-rich communities are associated with a foundation species. While we often have detailed information about the foundation species, we know less about its associated species. We explore such a situation, comparing the responses of lichen species associated with different tree taxa, which differ in successional strategy, to the environmental change that takes place when the surrounding trees are clear-cut. Location Boreal forests in Sweden. Methods We illustrated general differences in lichen species composition among four tree taxa and three stand categories using ordination of species occurrences. To analyse responses to clear-cutting we modelled the occurrence probability individually for 144 epiphytic lichen species from the lower 2 m of 2,400 tree trunks of four tree taxa in 130 stands, and compared trees in closed-canopy forests with those retained in logged stands, using Bayesian hierarchical models. Results The composition of lichens on aspen trees deviated clearly from that on the other tree species. Also lichen responses to logging differed among main host tree taxa, where lichen species associated with birches, European aspen, and Scots pine increased in probability of occurrence on trees in logged areas compared to intact forest, while lichen species associated with Norway spruce decreased. We found that time lags for changes in occupancy existed primarily in the increase, but not in the decline, of the groups of lichens associated with different tree taxa. Conclusions Lichens associated with different tree taxa vary in their response to the environmental change brought about by logging, but in a way that differs from the differences in species composition among host trees. Our results highlight the importance of considering the taxa of trees in forest management for the conservation of their associated lichen species. The extent to which the ecology of foundation species influences their associated species merits further inquiry, since such knowledge may facilitate predictions of responses of associated species also in other species-rich communities.

  • 61. Rodrigues, Patrícia
    et al.
    Shumi, Girma
    Dorresteijn, Ine
    Schultner, Jannik
    Hanspach, Jan
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Senbeta, Feyera
    Fischer, Joern
    Coffee management and the conservation of forest bird diversity in southwestern Ethiopia2018In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 217, p. 131-139Article in journal (Refereed)
    Abstract [en]

    Moist evergreen forests of southwestern Ethiopia host high levels of biodiversity and have a high economic value due to coffee production. Coffee is a native shrub that is harvested under different management systems; its production can have both beneficial and detrimental effects for biodiversity. We investigated how bird community composition and richness, and abundance of different bird groups responded to different intensities of coffee management and the landscape context. We surveyed birds at 66 points in forest habitat with different intensities of coffee management and at different distances from the forest edge. We explored community composition using detrended correspondence analysis in combination with canonical correspondence analysis and indicator species analysis, and used generalized linear mixed models to investigate the responses of different bird groups to coffee management and landscape context. Our results show that (1) despite considerable bird diversity including some endemics, species turnover in the forest was relatively low; (2) total richness and abundance of birds were not affected by management or landscape context; but (3) the richness of forest and dietary specialists increased with higher forest naturalness, and with increasing distance from the edge and amount of forest cover. These findings show that traditional shade coffee management practices can maintain a diverse suite of forest birds. To conserve forest specialists, retaining undisturbed, remote forest is particularly important, but structurally diverse locations near the forest edge can also harbour a high diversity of specialists.

  • 62.
    Samnegård, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eardley, Connal
    Nemomissa, Sileshi
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Turnover in bee species composition and functional trait distributions between seasons in a tropical agricultural landscape2015In: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 211, p. 185-194Article in journal (Refereed)
    Abstract [en]

    A comprehensive understanding of how spatial variation across landscapes regulates local abundances and species richness also needs to consider possible temporal changes in such relationships. In many tropical areas, the contrast between dry and rainy season is pronounced and the types and distributions of the main floral resources differ (herbs vs trees). This shift in resources could result in different pollinator abundances, species richness and trait compositions between seasons, as well as in how these components are spatially distributed. We compared the bee species composition between dry and rainy season in an agricultural mosaic landscape in southwestern Ethiopia, and analyzed it in relation to forest cover. We sampled bees for 67 days in the dry season and 86 days in the rainy season with pan and vane traps in 28 homegardens covering a gradient from low to high tree cover in the surrounding area. We found a clear shift in species composition between seasons, with more small bee species and more below-ground nesting bees in the rainy season compared to the dry season. The distribution of height at which the bees were foraging shifted between seasons with a higher proportion of the bees foraging at tree level in the dry season. Bee abundance and richness were generally positively affected by higher forest cover surrounding the homegardens, but there were no clear interaction effects between seasons, in contrast to our hypothesis. The clear turnover in species composition between seasons and the positive effect of forest cover show that mechanisms acting both at spatial and temporal scales are important in regulating local bee communities.

  • 63.
    Samnegård, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Lund University, Sweden.
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Lemessa, Debissa
    Nemomissa, Sileshi
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    A heterogeneous landscape does not guarantee high crop pollination2016In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 283, no 1838, article id 20161472Article in journal (Refereed)
    Abstract [en]

    The expansion of pollinator-dependent crops, especially in the developing world, together with reports of worldwide pollinator declines, raises concern of possible yield gaps. Farmers directly reliant on pollination services for food supply often live in regions where our knowledge of pollination services is poor. In a manipulative experiment replicated at 23 sites across an Ethiopian agricultural landscape, we found poor pollination services and severe pollen limitation in a common oil crop. With supplementary pollination, the yield increased on average by 91%. Despite the heterogeneous agricultural matrix, we found a low bee abundance, which may explain poor pollination services. The variation in pollen limitation was unrelated to surrounding forest cover, local bee richness and bee abundance. While practices that commonly increase pollinators (restricted pesticide use, flower strips) are an integral part of the landscape, these elements are apparently insufficient. Management to increase pollination services is therefore in need of urgent investigation.

  • 64.
    Samnegård, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nemomissa, Sileshi
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Dominance of the semi-wild honeybee as coffee pollinator across a gradient of shade-tree structure in Ethiopia2014In: Journal of Tropical Ecology, ISSN 0266-4674, E-ISSN 1469-7831, Vol. 30, p. 401-408Article in journal (Refereed)
    Abstract [en]

    Mass-flowering plant species are often pollinated by social bees that are able to use the abundant resource by recruiting workers from their colonies. In this study we surveyed pollinators on the mass-flowering perennial crop coffee (Coffea arabica) in its native range in Ethiopia. Previous studies in areas where coffee is introduced often find the social honeybee, Apis mellifera, to be the dominant pollinator. In those areas, the bee-species composition visiting coffee varies with a higher bee diversity closer to forest or in less modified habitats. We surveyed pollinators of coffee under different shade-tree structures, by collecting hoverflies and bees landing on coffee flowers in 19 sites in south-west Ethiopia. We found the native honeybee (A. mellifera) to be the dominant visitor of coffee flowers in all sites. Honeybee abundance was not affected by the local shade-tree structure, but was positively affected by the amount of coffee flower resources. Other pollinators were positively affected by complex shade-tree structures. To conclude, the honeybee is clearly the dominant pollinator of coffee in Ethiopia along the whole shade-tree structure gradient. Its high abundance could be a consequence of the provision of traditional bee hives in the landscape, which are colonized by wild swarming honeybees.

  • 65.
    Samnegård, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nemomissa, Sileshi
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Local and Regional Variation in Local Frequency of Multiple Coffee Pests Across a Mosaic Landscape in Coffea arabica's Native Range2014In: Biotropica, ISSN 0006-3606, E-ISSN 1744-7429, Vol. 46, no 3, p. 276-284Article in journal (Refereed)
    Abstract [en]

    Shaded coffee has been highlighted for its potential to conserve biodiversity, and thus perhaps also a diversity of natural enemies that could control pest organisms. In southwestern Ethiopia, coffee is grown in shade both in contiguous forests and in forest patches with native trees surrounded by open fields. We hypothesized that coffee grown in contiguous forests, which is the natural habitat for coffee (Coffea arabica) and its interacting organisms, would have less pest damage due to high protection by natural enemies. We surveyed pests on coffee plants in plots within contiguous forests (10 sites) and in forest patches (21 sites). In general, the variation in number of damaged or attacked leaves by individual insect or fungal pests was larger between plants than between plots, which suggests that very local conditions or processes are important. The spatial signals were generally weak. Coffee rust and coffee blotch miner tended to have lower infestation rates in accordance with our hypothesis, while fruit flies in ripe berries were more abundant in forest patches closer to contiguous forest. Based on interviews, olive baboons showed a clear dependency on contiguous forest habitat and were regarded as a problem only in contiguous forests and forest patches close to contiguous forests. In conclusion, we found no support for a generally stronger top-down control on coffee pests in sites within, or with connectivity to, contiguous moist afromontane forests in the native range of coffee.

  • 66.
    Samnegård, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hambäck, Peter
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Lemessa, Debissa
    Nemomissa, Sileshi
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    A heterogeneous landscape does not guarantee high crop pollinationManuscript (preprint) (Other academic)
    Abstract [en]

    The expansion of pollinator-dependent crops, especially in the developing world, together with reports of world-wide pollinator declines, raises concern of possible yield gaps. Farmers directly reliant on pollination services for food supply often live in regions where our knowledge of pollination services is poor. In a manipulative experiment replicated at 23 sites across an Ethiopian agricultural landscape, we found poor pollination services and severe pollen limitation in a common oil crop. With supplementary pollination, the yield increased on average by 91%. Despite the heterogeneous agricultural matrix, we found a low bee abundance, which may explain poor pollination services. The variation in pollen limitation was unrelated to surrounding forest cover, local bee richness and bee abundance. While practices that commonly increase pollinators (e.g. organic farming, flower strips) are an integral part of the landscape, these elements are apparently insufficient. Management to increase pollination services is therefore in need of urgent investigation.

  • 67.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Boulders increase resistance to clear-cut logging but not subsequent recolonization rates of boreal bryophytes2011In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 167, no 4, p. 1093-1101Article in journal (Refereed)
    Abstract [en]

    The extent to which a plant assemblage might recolonize a disturbed system is in general related to the availability of propagule sources and sites with appropriate conditions for establishment. Both these factors might be sensitive to aspects of spatial heterogeneity. Microtopographic variation may enhance initial resistance by reducing the impact of the disturbance and facilitating establishment of incoming propagules by providing shaded safe-sites. This study explores the influence of microtopographic heterogeneity (caused by variation in surface boulder cover) on the recolonization of closed-canopy forest floor bryophytes using a chronosequence of 75 spruce-dominated forests in south-central Sweden (2-163 years after clear-cutting). We found that high boulder cover did increase survival and subsequent persistence in young forests at both investigated scales (i.e. 1,000 and 100 m(2)), although this pattern became less evident on the smaller spatial scale. Species accumulation in boulder-poor subplots was not different when surrounded by boulder-rich compared with boulder-poor subplots suggesting short-distance recolonization from boulder-created refugia to be of little importance during recolonization. To conclude, it seems that boulders increase initial resistance to clear-cutting for this bryophyte guild, but that the subsequent recolonization process is more likely to depend on external propagule sources and factors affecting establishment such as the microclimate in the developing stand.

  • 68.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Bryophyte species density and composition in young forests regenerating after clear-cut logging, wildfire and spruce budworm outbreakManuscript (preprint) (Other academic)
    Abstract [en]

    The disturbance regime in the interface of the boreal forests and the north-temperate deciduous forests in eastern Canada is characterized by both natural disturbances such as wildfires and insect outbreaks as well as anthropogenic disturbances such as production forestry. The current understanding of how understorey plant assemblages respond to different disturbances is mostly based on short-term wildfire-logging comparisons and has traditionally emphasized vascular plants. In this study we explore patterns of species density and composition of four bryophyte guilds in young forests (approximately 40 years old) regenerating after clear-cut logging, wildfire, and spruce budworm outbreak in the Acadian forest region of New Brunswick, eastern Canada. Although being similar in overall species density at the scale of 1000 m2 all three young forest types had fewer species than mature reference forests. All groups were found to be compositionally distinct. Stands developed after spruce budworm outbreaks had the highest canopy closure and the highest amount of coarse woody debris. These stands had similar number of woody debris species as mature forests and an overall species composition that was most similar to mature forests among the three groups. Wildfire-disturbed sites were characterized by a high litter cover, perhaps due to the larger deciduous component of the canopy. A high number of treebase species was typical of these sites. Finally, young managed forest had the highest number of forest floor bryophytes at the scale of 100 m2 among the three young forest types, but was compositionally very far from mature forests in their woody debris flora. In conclusion, young seral stages of forest succession following different disturbances seem to have complementary roles in maintaining landscape level diversity, but if natural disturbances are eliminated certain species (e.g., among the epixylics and treebase species) might become more restricted to older stands in the landscape.

  • 69.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Microtopographic influence on recolonization patterns of forest floor bryophytes following clear-cut loggingManuscript (preprint) (Other academic)
    Abstract [en]

    The extent to which a plant assemblage might recolonize a disturbed system is in general related to the availability of propagule sources and sites with appropriate conditions for establishment. Both of these factors might be sensitive to aspects of spatial heterogeneity. Microtopographic variation may enhance initial resistance by reducing the impact of the disturbance and facilitate establishment of incoming propagules by providing shaded “safe-sites” for establishment. This study explores the influence of microtopographic heterogeneity (caused by variation in surface boulder cover) on the recolonization of closed-canopy forest floor bryophytes using a chronosequence of 75 spruce-dominated forests in south-central Sweden (2-163 years after clear-cutting). We found that high boulder cover did increase survival and subsequent persistence in young forests at the scale of 1000 m2, but that this effect disappeared on a smaller spatial scale (100 m2). At the smaller scale there was a steady accumulation of species over time in both sites with few and many boulders. Furthermore, species accumulation in boulder-poor subplots was not different when surrounded by boulder-rich compared with boulder-poor subplots suggesting short-distance recolonization from boulder-created refugia to be of little importance during the recolonization process. Apparently, boulders function as creators of refugia, but such events seem to be relatively infrequent, which can explain why we were only able to detect such a pattern at larger scales. To conclude it seems like boulders (and probably microtopographic surface structures in general) increase initial resistance to clear-cutting for this bryophyte guild, but that the subsequent recolonization process is more likely to depend on external propagule sources and factors affecting establishment such as microclimate.

  • 70.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Microtopography creates small-scale refugia for boreal bryophytes during clear-cut loggingIn: Ecography, ISSN 0906-7590, E-ISSN 1600-0587Article in journal (Other academic)
    Abstract [en]

    The biotic response of ecological systems to disturbances has traditionally been explained by attributes of the disturbance event itself, such as its intensity, the distribution of traits within a community related to resistance (e.g., physiological, morphological or life-history) or their interaction. Another less investigated mechanism explaining variation in response to disturbance is microtopographic heterogeneity, which might modify survival rates unevenly. We tested the hypothesis that forest floor microtopography creates small-scale refugia for bryophytes following conventional clear-cut logging by comparing a) survival of transplanted bryophytes and b) compositional changes of forest floor bryophytes among three different positions: on the northern side of boulders and stumps and on unsheltered forest floor. The investigation was carried out as a before-and-after study in 12 Swedish boreal forests (eight stands subjected to clear-cutting and four reference stands). Significantly more bryophyte transplants survived where they were shelter by boulders and stumps (30 % and 29 % respectively) compared to on level forest floor (10 %) and and less compositional changes occurred in sheltered microtopographic positions compared to on level forest floor. Shelter from boulders and stumps increased survival from both microclimatic stress and mechanical disturbance but not from burying by logging residues. Our findings provide evidence that microtopography can modify initial responses to disturbances by creating small-scale refugia. Further studies are needed to determine whether this phenomenon is commonly occurring among other organisms and in other ecosystems and to what extent scattered in-situ survivors can increase the recovery rate following disturbances.

  • 71.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Microtopography creates small-scale refugia for boreal forest floor bryophytes during clear-cut logging2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 4, p. 637-648Article in journal (Refereed)
    Abstract [en]

    The biotic response of ecological systems to disturbances has traditionally been explained by attributes of the disturbance event itself, such as its intensity, the distribution of traits within a community related to resistance (e. g. physiological, morphological or life-history) or their interaction. Another less investigated mechanism explaining variation in response to disturbance is microtopographic heterogeneity, which might modify survival rates unevenly. We tested the hypothesis that forest floor microtopography creates small-scale refugia for bryophytes following conventional clear-cut logging by comparing a) survival of transplanted bryophytes and b) compositional changes of forest floor bryophytes among three different positions: on the northern side of boulders and stumps and on unsheltered forest floor. The investigation was carried out as a before-and-after study in 12 Swedish boreal forests (eight stands subjected to clear-cutting and four reference stands). Significantly more bryophyte transplants survived where they were sheltered by boulders and stumps (30 and 29% respectively) compared to on level forest floor (10%) and less compositional changes occurred in sheltered microtopographic positions than on level forest floor. Shelter from boulders and stumps increased survival from both microclimatic stress and mechanical disturbance but not from burial by logging residues. Our findings provide evidence that microtopography can modify initial responses to disturbances by creating small-scale refugia. Further studies are needed to determine whether this phenomenon is commonly occurring among other organisms and in other ecosystems and to what extent scattered in-situ survivors can increase the recovery rate following disturbances.

  • 72.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Succession of bryophyte assemblages following clear-cut logging in boreal spruce-dominated forests in south-central Sweden - Does retrogressive succession occur?2009In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 39, no 10, p. 1871-1880Article in journal (Refereed)
    Abstract [en]

    The recovery process of boreal bryophyte communities after clear-cutting was studied in a chronosequence in south-central Sweden. We hypothesized that high initial grass cover on clearcuts, high litter cover and low light levels during canopy closure, and shortage of coarse woody substrates would constrain recovery in different ways. Instead, both epigeic and epixylic guilds (i.e., species growing on forest floor and deadwood) displayed a gradual increase in similarity over time from the clear-cut phase, perhaps because of the absence of distinct peaks in needle litter and canopy cover. Epixylic species started to recover long before the accumulation of deadwood, indicating that microclimate rather than substrate availability was the most constraining factor during the first 50 years. Since we did not find any other bottlenecks during the succession after clear-cutting, conservation measures aiming at decreasing local extinction rates during clearcutting may also increase long-term persistence. On the other hand, as the results from the epixylic guild suggest, other factors during the forest succession, such as the development of a suitable microclimate, might be more important for some organisms, thus possibly mitigating such long-term positive effects of adjusted management during the clear-cutting operation.

  • 73.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Frego, Katherine
    Bryophyte species richness and composition in young forests regenerated after clear-cut logging versus after wildfire and spruce budworm outbreak2011In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710, Vol. 20, no 12, p. 2575-2596Article in journal (Refereed)
    Abstract [en]

    The disturbance regime in mixed-wood forests of eastern Canada is characterized by both natural disturbances including wildfires and insect outbreaks as well as forestry. The understanding of how understorey plant assemblages respond to different disturbances is mostly limited to short-term wildfire-logging comparisons of vascular plants. Here, we compare patterns of species richness and composition of four bryophyte guilds in young forests (approx. 40 years old) regenerating after clear-cut logging, wildfire, and spruce budworm outbreak. In addition, young forests were compared with mature spruce-fir dominated stands (approx. 90 years old). Although similar in overall species richness at the scale of 1,000 m(2) all young forest types were compositionally distinct with fewer species than mature forests. Stands developed after spruce budworm outbreaks had the highest canopy cover values and the highest surface area of coarse woody debris. These stands had similar numbers of woody debris species as mature forests and were closest to mature forests in species composition. Wildfire-disturbed sites were dominated by deciduous trees and a high number of treebase species. Finally, young managed forest had the highest number of forest floor bryophytes at the scale of 100 m(2) among the three young forest types, but was compositionally far from mature forests in their woody debris flora. In conclusion, young forests regenerating after natural disturbances are distinctly different from young forests regenerated after clear-cutting and if natural disturbances are eliminated certain species (e. g., epixylic and treebase species) might become more restricted to older stands in the landscape.

  • 74. Shumi, Girma
    et al.
    Rodrigues, Patricia
    Schultner, Jannik
    Dorresteijn, Ine
    Hanspach, Jan
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Senbeta, Feyera
    Fischer, Joern
    Conservation value of moist evergreen Afromontane forest sites with different management and history in southwestern Ethiopia2019In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 232, p. 117-126Article in journal (Refereed)
    Abstract [en]

    Tropical forest ecosystems harbor high biodiversity, but they have suffered from ongoing human-induced degradation. We investigated the conservation value of moist evergreen Afromontane forest sites across gradients of site-level disturbance, landscape context and forest history in southwestern Ethiopia. We surveyed woody plants at 108 randomly selected sites and grouped them into forest specialist, pioneer, and generalist species. First, we investigated if coffee dominance, current distance from the forest edge, forest history, heat load and altitude structured the variation in species composition using constrained correspondence analysis. Second, we modelled species richness in response to the same explanatory variables. Our findings show that woody plant community composition was significantly structured by altitude, forest history, coffee dominance and current distance from forest edge. Specifically, (1) total species richness and forest specialist species richness were affected by coffee management intensity; (2) forest specialist species richness increased, while pioneer species decreased with increasing distance from the forest edge; and (3) forest specialist species richness was lower in secondary forest compared to in primary forest. These findings show that coffee management intensity, landscape context and forest history in combination influence local and landscape level biodiversity. We suggest conservation strategies that foster the maintenance of large undisturbed forest sites and that prioritize local species in managed and regenerating forests. Creation of a biosphere reserve and shade coffee certification could be useful to benefit both effective conservation and people's livelihoods.

  • 75. Shumi, Girma
    et al.
    Schultner, Jannik
    Dorresteijn, Ine
    Rodrigues, Patricia
    Hanspach, Jan
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Senbeta, Feyera
    Fischer, Joern
    Land use legacy effects on woody vegetation in agricultural landscapes of south-western Ethiopia2018In: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 24, no 8, p. 1136-1148Article in journal (Refereed)
    Abstract [en]

    Aim: Past land use legacy effectsextinction debts and immigration creditsmight be particularly pronounced in regions characterized by complex and dynamic landscape change. The aim of this study was to evaluate how current woody plant species distribution, composition and richness related to historical and present land uses. Location: A smallholder farming landscape in south-western Ethiopia. Methods: We surveyed woody plants in 72 randomly selected 1-ha sites in farmland and grouped them into forest specialist, generalist and pioneer species. First, we investigated woody plant composition and distribution using non-metric multidimensional scaling. Second, we modelled species richness in response to historical and current distance from the forest edge. Third, we examined diameter class distributions of trees in recently converted vs. permanent farmland. Results: Historical distance was a primary driver of woody plant composition and distribution. Generalist and pioneer species richness increased with historical distance. Forest specialists, however, did not respond to historical distance. Only few old individuals of forest specialist species remained in both recently converted and permanent farmlands. Main conclusions: Our findings suggest that any possible extinction debt for forest specialist species in farmland at the landscape scale was rapidly paid off, possibly because farmers cleared large remnant trees. In contrast, we found substantial evidence of immigration credits in farmland for generalist and pioneer species. This suggests that long-established farmland may have unrecognized conservation values, although apparently not for forest specialist species. We suggest that conservation policies in south-western Ethiopia should recognize not only forests, but also the complementary value of the agricultural mosaicsimilar to the case of European cultural landscapes. A possible future priority could be to better reintegrate forest species in the farmland mosaic.

  • 76. Telila, Habte
    et al.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nemomissa, Sileshi
    The potential of small Eucalyptus plantations in farmscapes to foster native woody plant diversity: local and landscape constraints2015In: Restoration Ecology, ISSN 1061-2971, E-ISSN 1526-100X, Vol. 23, no 6, p. 918-926Article in journal (Refereed)
    Abstract [en]

    The major focus of ecological restorations has been on understanding local factors. However, landscape factors such as dispersal limitation of individuals or propagules across the surrounding matrix can also constrain the restoration progress. We investigated to what extent native woody species colonize and thrive in plantations, focusing on both the role of local factors such as grazing and canopy cover as well as on landscape factors. We recorded all native tree and shrub species in 60 small Eucalyptus plantations embedded in an open agricultural landscape at 0.1-12 km from a remnant continuous forest in central Ethiopia. We found a total of 1,571 individuals of native woody plants belonging to 55 species. Number of such species in a plantation increased significantly with the height of the grass sword indicating their sensitivity to grazing. Moreover, the number of woody species in the patches decreased significantly with distance to the forest. Our results illustrate the need for regulating the grazing pressure for a successful regeneration of native species in Eucalyptus plantations. In addition, sowing or planting native trees will be necessary in most plantations, as only few remnant natural forests that could act as seed sources occur across the Ethiopian highlands. Another main obstacle might be the prohibition of selling timber of native trees, which indirectly discourage farmers from letting native trees regenerate. Thus, the increasing cover of Eucalyptus seen across the country will not automatically foster a recovery of native woody plant biodiversity, even if managed to optimize local environmental conditions.

  • 77.
    Vercauteren, Nikki
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dahlberg, Carl Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Fine-Resolved, Near-Coastal Spatiotemporal Variation of Temperature in Response to Insolation2013In: Journal of Applied Meteorology and Climatology, ISSN 1558-8424, E-ISSN 1558-8432, Vol. 52, no 5, p. 1208-1220Article in journal (Refereed)
    Abstract [en]

    This study uses GIS-based modeling of incoming solar radiation to quantify fine-resolved spatiotemporal responses of monthly average temperature, and diurnal temperature variation, at different times and locations within a field study area located on the eastern coast of Sweden. Near-surface temperatures are measured by a network of temperature sensors during the spring and summer of 2011 and then used as the basis for model development and testing. The modeling of finescale spatiotemporal variation considers topography, distance from the sea, and observed variations in atmospheric conditions, accounting for site latitude, elevation, surface orientation, daily and seasonal shifts in sun angle, and effects of shadows from surrounding topography. The authors find a lag time between insolation and subsequent temperature response that follows an exponential decay from coastal to inland locations. They further develop a linear regression model that accounts for this lag time in quantifying fine-resolved spatiotemporal temperature evolution. This model applies in the considered growing season for spatial distribution across the studied near-coastal landscape.

  • 78. Wasof, Safaa
    et al.
    Lenoir, Jonathan
    Aarrestad, Per Arild
    Alsos, Inger Greve
    Armbruster, W. Scott
    Austrheim, Gunnar
    Bakkestuen, Vegar
    Birks, H. John B.
    Bråthen, Kari Anne
    Broennimann, Olivier
    Brunet, Jörg
    Bruun, Hans Henrik
    Dahlberg, Carl Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Diekmann, Martin
    Dullinger, Stefan
    Dynesius, Mats
    Ejrnaes, Rasmus
    Gegout, Jean-Claude
    Graae, Bente Jessen
    Grytnes, John-Arvid
    Guisan, Antoine
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jonsdottir, Ingibjörg S.
    Kapfer, Jutta
    Klanderud, Kari
    Luoto, Miska
    Milbau, Ann
    Moora, Mari
    Nygaard, Bettina
    Odland, Arvid
    Pauli, Harald
    Ravolainen, Virve
    Reinhardt, Stefanie
    Sandvik, Sylvi Marlen
    Schei, Fride Hoistad
    Speed, James D. M.
    Svenning, Jens-Christian
    Thuiller, Wilfried
    Tveraabak, Liv Unn
    Vandvik, Vigdis
    Velle, Liv Guri
    Virtanen, Risto
    Vittoz, Pascal
    Willner, Wolfgang
    Wohlgemuth, Thomas
    Zimmermann, Niklaus E.
    Zobel, Martin
    Decocq, Guillaume
    Disjunct populations of European vascular plant species keep the same climatic niches2015In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 24, no 12, p. 1401-1412Article in journal (Refereed)
    Abstract [en]

    Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestrial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distribution modelling to test for a region effect on each species' climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with strictly disjunct populations and 58 species (16%) of the 358 species with distant populations showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic-alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000-15,000 years. Therefore, the basic assumption of species distribution models that a species' climatic niche is constant in space and time-at least on time scales 104 years or less-seems to be largely valid for arctic-alpine plants.

  • 79. Zanatta, Florian
    et al.
    Patiño, Jairo
    Lebeau, Frederic
    Massinon, Mathieu
    Hylander, Kristofer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    de Haan, Myriam
    Ballings, Petra
    Degreef, Jerôme
    Vanderpoorten, Alain
    Measuring spore settling velocity for an improved assessment of dispersal rates in mosses2016In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 118, no 2, p. 197-206Article in journal (Refereed)
    Abstract [en]

    Background and Aims The settling velocity of diaspores is a key parameter for the measurement of dispersal ability in wind-dispersed plants and one of the most relevant parameters in explicit dispersal models, but remains largely undocumented in bryophytes. The settling velocities of moss spores were measured and it was determined whether settling velocities can be derived from spore diameter using Stokes' Law or if specific traits of spore ornamentation cause departures from theoretical expectations. Methods A fall tower design combined with a high-speed camera was used to document spore settling velocities in nine moss species selected to cover the range of spore diameters within the group. Linear mixed effect models were employed to determine whether settling velocity can be predicted from spore diameter, taking specific variation in shape and surface roughness into account. Key Results Average settling velocity of moss spores ranged from 0 center dot 49 to 8 center dot 52 cm s(-1). There was a significant positive relationship between spore settling velocity and size, but the inclusion of variables of shape and texture of spores in the best-fit models provides evidence for their role in shaping spore settling velocities. Conclusions Settling velocities in mosses can significantly depart from expectations derived from Stokes' Law. We suggest that variation in spore shape and ornamentation affects the balance between density and drag, and results in different dispersal capacities, which may be correlated with different life-history traits or ecological requirements. Further studies on spore ultrastructure would be necessary to determine the role of complex spore ornamentation patterns in the drag-to-mass ratio and ultimately identify what is the still poorly understood function of the striking and highly variable ornamentation patterns of the perine layer on moss spores.

  • 80. Zanatta, Florian
    et al.
    Vanderpoorten, Alain
    Hedenäs, Lars
    Johansson, Victor
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Swedish University of Agricultural Sciences, Sweden.
    Patiño, Jairo
    Lönnell, Niklas
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Under which humidity conditions are moss spores released? A comparison between species with perfect and specialized peristomes2018In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 8, no 23, p. 11484-11491Article in journal (Refereed)
    Abstract [en]

    Dispersal is a fundamental biological process that can be divided into three phases: release, transportation, and deposition. Determining the mechanisms of diaspore release is of prime importance to understand under which climatic conditions and at which frequency diaspores are released and transported. In mosses, wherein spore dispersal takes place through the hygroscopic movements of the peristome, the factors enhancing spore release has received little attention. Here, we determine the levels of relative humidity (RH) at which peristome movements are induced, contrasting the response of species with perfect (fully developed) and specialized (reduced) peristomes. All nine investigated species with perfect peristomes displayed a xerochastic behavior, initiating a closing movement from around 50%–65% RH upon increasing humidity and an opening movement from around 90% RH upon drying. Five of the seven species with specialized peristomes exhibited a hygrochastic behavior, initiating an opening movement under increasing RH (from about 80%) and a closing movement upon drying (from about 90%). These differences between species with hygrochastic and xerochastic peristomes suggest that spore dispersal does not randomly occur regardless of the prevailing climate conditions, which can impact their dispersal distances. In species with xerochastic peristomes, the release of spores under decreasing RH can be interpreted as an adaptive mechanism to disperse spores under optimal conditions for long‐distance wind dispersal. In species with hygrochastic peristomes, conversely, the release of spores under wet conditions, which decreases their wind long‐distance dispersal capacities, might be seen as a safe‐site strategy, forcing spores to land in appropriate (micro‐) habitats where their survival is favored. Significant variations were observed in the RH thresholds triggering peristome movements among species, especially in those with hygrochastic peristomes, raising the question of what mechanisms are responsible for such differences.

12 51 - 80 of 80
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf