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  • 1.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Schmucki, Reto
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Reimark, Josefin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Grazing networks provide useful functional connectivity for plants in fragmented systems2012In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 23, no 5, p. 970-977Article in journal (Refereed)
    Abstract [en]

    Question To what extent does the movement of animals between fragmented habitat patches provide functional connectivity via endozoochorous seed dispersal? Location The Stockholm archipelago, Sweden. Methods We followed all movements of livestock between islands during one grazing season. After each movement, manure was collected and its seed content assessed through seedling emergence. Seedling data were then compared to vegetation surveys from the grazed islands with regard to functional traits. Results Light- and nitrogen-demanding locally abundant species, and those with relatively small and persistent seeds were more likely to be moved between islands. For quantitative traits, only a subset of the available trait ranges were dispersed, with extreme values left behind. Species apparently specialized to other means of dispersal emerged from the manure samples. Neither dispersed traits nor seed density changed with timing of movement, but seed richness and diversity both increased throughout the season. The subsets of endozoochorously-dispersed species in the established vegetation were more similar than non-dispersed subsets between islands linked by livestock. Conclusions Grazing networks contribute to the connectivity of the core species in the system, and could provide useful tools for grassland management in fragmented landscapes.

  • 2.
    Bruun, H. H.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Moen, Jon
    Virtanen, Risto
    Grytnes, J. A.
    Oksanen, Lauri
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Effects of altitude and topography on species richness of vascular plants, bryophytes and lichens in alpine communities2006In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 17, no 1, p. 37-46Article in journal (Refereed)
    Abstract [en]

    Question: What is the relationship between species richness of vascular plants, bryophytes and macrolichens, and two important gradients in the alpine environment, altitude and local topography? Location: Northernmost Fennoscandia, 250-152 m a.s.l. corresponding to the range between timberline and mountain top. Methods: The vegetation was sampled in six mountain areas. For each 25 vertical metres, the local topographic gradient from wind-blown ridge to snowbed was sampled in quadrats of 0.8 m x 0.8 m. Patterns in species richness were explored using Poisson regression (Generalized Linear Models). Functional groups of species, i.e. evergreen and deciduous dwarf-shrubs, forbs, graminoids, mosses, hepatics and lichens were investigated separately. Results: Functional groups showed markedly different patterns with respect to both altitude and topography. Species richness of all vascular plants showed a unimodal relationship with altitude. The same was true for graminoids, forbs and lichens analysed separately, but forb richness peaked at Much higher altitudes than total richness. The richness of dwarf-shrubs decreased monotonically with altitude, whereas richness of mosses and liverworts showed an increasing trend. Significant interactions between altitude and local topography were present for several groups. The unimodal pattern for total plant species richness was interpreted in terms of local productivity, physical disturbance, trophic interactions, and in terms of species pool effects. Conclusions: Patterns in local species richness result from the action of two opposing forces: declining species pool and decreasing intensity of competition with altitude.

  • 3.
    Cousins, Sara
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Extinction debt in fragmented grasslands: paid or not?2009In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 20, no 1, p. 3-7Article in journal (Refereed)
    Abstract [en]

    Fragmentation of grasslands and forests is considered amajor threat to biodiversity. In the case of plants, theeffect of fragmentation or landscape context is still unclearand published results are divergent. One explanation forthis divergence is the slow response of long-lived plants,creating an extinction debt. However, this has not beenempirically confirmed. In this study, data were compiledfrom broad-scale studies of grasslands from throughoutthe world that relate plant diversity to fragmentationeffects. Only seven studies from northern Europe, out ofa total 61, gave any information on actual habitat fragmentationin time and space. In landscapes with 410%grassland remaining, present-day species richness wasrelated to past landscape or habitat pattern. In landscapeswith o10% grassland remaining, in contrast, plant speciesrichness was more related to contemporary landscapeor habitat pattern. Studies from landscapes with 410%grassland remaining supported the concept of an extinctiondebt, while studies from more fragmented landscapesdid not provide any evidence of an extinction debt. Inorder to make generalisations about historical legacies onspecies diversity in grasslands it is important to consider arange of highly transformed landscapes, and not onlylandscapes with a high amount of grassland remaining.

  • 4.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Moving towards the edge: matrix matters!2013In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 24, no 1, p. 7-8Article in journal (Refereed)
    Abstract [en]

    In this issue of the Journal of Vegetation Science, Chabrerie et al. use plant inventories and geographical data to investigate effects on species richness and turnover caused by management intensity in the surrounding matrix in new and old forest fragments. Although forest edge age was important, more intensive management of the matrix clearly sharpened the edgeinterior gradient.

  • 5.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    A closer look at the species behind abundance-occupancy relationships2013In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 24, no 4, p. 589-590Article in journal (Refereed)
    Abstract [en]

    Guedo & Lamb (), in this issue of the Journal of Vegetation Science, used a 35-yr data series from two prairie communities to show that abundance-occupancy relationships change over time. Scrutinizing the details behind this finding, they show that species groups follow different trajectories during succession after disturbance. These results will inspire further species-level studies unraveling mechanisms behind abundance-occupancy relationships.

  • 6.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Vegetation change and eco-evolutionary dynamics2014In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 25, no 5, p. 1141-1147Article in journal (Refereed)
    Abstract [en]

    Question: Eco-evolutionary dynamics is a concept encapsulating a feedback between ecology and evolution, acting on short ecological time-scales. Recent studies suggest that such dynamics have been generally over-looked. The objective of this paper is to examine how eco-evolutionary dynamics may contribute to vegetation science. Location: Global. Methods: In this paper I discuss eco-evolutionary dynamics in the context of vegetation science, with a focus on effects derived from human-mediated niche construction, manifested as new habitats, non-native species, and changing connectivity and spatial configuration of habitats. Results and Conclusions: I suggest that eco-evolutionary dynamics have the potential to influence plant community composition and assembly, and thus that eco-evolutionary dynamics should become focus of studies in vegetation science.

  • 7.
    Eriksson, Ove
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Bruun, Hans Henrik
    Stockholm University, Faculty of Science, Department of Botany.
    Land-use history and fragmentation of traditionally managed grasslands in Scandinavia2002In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 13, no 5, p. 743-748Article in journal (Refereed)
    Abstract [en]

    Plants associated with traditional agricultural landscapes in northern Europe and Scandinavia are subjected to drastic habitat fragmentation. In this paper we discuss species response to fragmentation, against a background of vegetation and land-use history. Recent evidence suggests that grassland-forest mosaics have been prevalent long before the onset of human agriculture. We suggest that the creation of infield meadows and outland grazing (during the Iron Age) increased the amount and spatial predictability of grasslands, resulting in plant communities with exceptionally high species densities. Thus, distribution of plant species in the present-day landscape reflects historical land-use. This holds also when traditional management has ceased, due to a slow response by many species to abandonment and fragmentation. The distribution patterns are thus not in equilibrium with the present habitat distribution. Fragmentation influences remaining semi-natural grasslands such that species density is likely to decline as a result of local extinctions and invasion by habitat generalists. However, species that for a long time have been subjected to changing mosaic landscapes may be more resistant to fragmentation than is usually believed. Conservation should focus not only on 'hot-spots' with high species richness, but also consider species dynamics in a landscape context.

  • 8.
    Hylander, Kristoffer
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Johnson, Samuel
    Stockholm University, Faculty of Science, Department of Botany.
    In situ survival of forest bryophytes in small-scale refugia after an intense forest fire2010In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 21, no 6, p. 1099-1109Article in journal (Refereed)
    Abstract [en]

    Question Species can persist in landscapes with recurring disturbances either by migrating to places suitable for the moment or by enduring the threatening conditions. We investigated to what extent boreal forest bryophytes survived an intense forest fire in situ and whether bryophytes had started to recolonize the area 7-8 years later. Location Tyresta National Park, eastern Sweden. Methods We recorded bryophytes in 14 burnt and 12 forest reference plots (50 x 50 m). In each plot we investigated 15 random 1-m2 micro-plots. In plots in the burnt area we also examined micro-plots at locations of all fire refugia, and in case of the forest references, of 10 potential refugia. Results We found on average three small refugia per 50 x 50-m plot; each containing on average 4.8 forest bryophytes, a level similar to that of micro-plots in the references, but significantly higher than in random micro-plots in the burnt plots (1.5 species). Many refugia were located in rocky areas, but few were in wet sites. The burnt area remained dominated by a few fire-favoured species, even if recolonization of forest bryophytes had begun. There was, however, no significant correlation between number of refugia and number of forest species in random micro-plots, leaving open the question of the importance of refugia as regulators of early succession. Conclusion We conclude that small-scale refugia can also occur for sensitive species such as forest bryophytes, and that the refugia in our case were frequently found on rocky or mesic rather than wet sites. The role of such refugia in recolonization, however, warrants further investigation.

  • 9.
    Jakobsson, Simon
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Fukamachi, Katsue
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Connectivity and management enables fast recovery of plant diversity in new linear grassland elements2016In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 27, no 1, p. 19-28Article in journal (Refereed)
    Abstract [en]

    Questions: How does small linear grassland elements (paddy levees and road verges) contribute to plant diversity patterns in sites with modern or traditional management? Which factors determine small-scale plant species richness of small linear grassland elements in a Japanese agricultural landscape?

    Location: Shiga Prefecture, Japan.

    Methods: Aerial photos from 1963, 1985, 1995 and 2008 were used to investigate landscape changes and to measure landscape structures within a typical agricultural landscape (25km(2)). Plant diversity was investigated in ten paddy levees and ten road verges in each of four traditional (barely any land cover alterations after 1963) and five modern (almost completely changed after 1985) sites. -diversity (mean number of species per plot) and -diversity (total number of species) for all species, specialist and invasive species, respectively, were analysed in relation to site history types and landscape structures. Plot species richness was analysed in relation to site history type, patch age and width, proximity to forest and litter removal.

    Results: In total, 204 plant species were found, 55 species unique to traditional sites and 13 unique to modern sites. - and -diversity of paddy levees and road verges was significantly higher in traditional sites. Number of specialist species on paddy levees and number of invasive species in road verges was also higher in traditional sites. Age was the strongest predictor of plot species richness on levees; older levees supported higher species richness than younger ones. Litter removal was the strongest predictor (positive effect) of plot species richness in road verges.

    Conclusions: These results suggest that the colonization credit of new levees in modern sites is decreasing quite rapidly as species quickly establish, approaching almost the same richness values as in traditional sites. However, long continuity of traditional management is still one of the most important contributors to plant diversity and crucial for many species. But small grassland elements can still be of great significance for preserving and enhancing plant diversity in otherwise depleted landscapes, as long as they are managed and connected throughout the landscape.

  • 10.
    Marteinsdottir, Bryndis
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Plant community assembly in semi-natural grasslands and ex-arable fields: a trait-based approach2014In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 25, no 1, p. 77-87Article in journal (Refereed)
    Abstract [en]

    QuestionThe assembly of plants into communities is one of the central topics in plant community ecology. The objective of this study was to investigate how plant functional trait diversity and environmental factors influence community assembly in two different grassland communities, and if variation in these factors could explain the difference in species assembly between these communities. LocationSix grazed ex-arable fields and eight semi-natural grasslands in southeast Sweden. MethodsWe estimated species abundance and measured soil attributes at each site. For each species within each site we measured specific leaf area (SLA), leaf dry matter content (LDMC) and seed mass. We analysed the data both for abundance-weighted species values and species occurrence. ResultsTrait gradient analysis indicated random distribution of species among sites, while CCA analysis indicated that both soil phosphorus and moisture were related to species assembly at a site. Correlations and fourth-corner analysis also revealed a relationship between measured species traits and soil phosphorus and moisture. There was a lower average seed mass and higher SLA of species in ex-arable fields compared to species in semi-natural grasslands. ConclusionsEven though trait gradient analysis indicated that plant community assembly in the studied grasslands was random, other results implied that species occurrence and abundance was influenced both by environmental factors and species traits. Higher species richness in semi-natural grasslands was associated with more large-seeded species found there compared to ex-arable fields, indicating that large-seeded species establish in grasslands later than small-seeded species.

  • 11.
    Marteinsdottir, Bryndis
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Svavarsdottir, Kristin
    Thorhallsdottir, Thora Ellen
    Development of vegetation patterns in early primary succession2010In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 21, no 3, p. 531-540Article in journal (Refereed)
    Abstract [en]

    Question We investigated colonisation filters in early plant community development on a glacial outwash plain. We asked if these were related to seed limitation or to a lack of safe sites, if topographical heterogeneity affected species patchiness and how species life cycles influence successional trajectories. Location An outwash plain (Skeithararsandur) in southeast Iceland. Methods We identified surface heterogeneity at two different scales, ca. 10-15 cm (larger stones and established plants) and ca. 50 m (shallow depressions representing dry river beds) at two study sites. We quantified species cover, flowering plant density, seed production, seed rain, seed bank density, seedling emergence and seedling survival from June 2005 to June 2007 for the whole plant community, and measured seed production for five species. Results Mean vegetation cover was < 2.5% at the sites. Low emergence rates and high seedling mortality were the two main recruitment filters. Only 1.4% of seedlings emerging in 2005 survived into the 2007 growing season. Topographical heterogeneity had little effect on plant colonisation. High annual variation was recorded, and the two study sites (ca. 2 km apart) differed in their colonisation success. Of the five species, establishment of Cerastium alpinum and Silene uniflora was most limited by lack of seeds, whereas establishment of Luzula spicata, Poa glauca and Rumex acetosella was most limited by safe sites. Conclusions We conclude that colonisation processes and patterns in early primary succession on Skeithararsandur were largely influenced by stochastic factors.

  • 12.
    Plue, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Södertörn University, Sweden; University of Bremen, Germany.
    De Frenne, Pieter
    Acharya, Kamal
    Brunet, Jörg
    Chabrerie, Olivier
    Decocq, Guillaume
    Diekmann, Martin
    Graae, Bente J.
    Heinken, Thilo
    Hermy, Martin
    Kolb, Annette
    Lemke, Isgard
    Liira, Jaan
    Naaf, Tobias
    Verheyen, Kris
    Wulf, Monika
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Where does the community start, and where does it end? Including the seed bank to reassess forest herb layer responses to the environment2017In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 28, no 2, p. 424-435Article in journal (Refereed)
    Abstract [en]

    QuestionBelow-ground processes are key determinants of above-ground plant population and community dynamics. Still, our understanding of how environmental drivers shape plant communities is mostly based on above-ground diversity patterns, bypassing below-ground plant diversity stored in seed banks. As seed banks may shape above-ground plant communities, we question whether concurrently analysing the above- and below-ground species assemblages may potentially enhance our understanding of community responses to environmental variation. LocationTemperate deciduous forests along a 2000km latitudinal gradient in NW Europe. MethodsHerb layer, seed bank and local environmental data including soil pH, canopy cover, forest cover continuity and time since last canopy disturbance were collected in 129 temperate deciduous forest plots. We quantified herb layer and seed bank diversity per plot and evaluated how environmental variation structured community diversity in the herb layer, seed bank and the combined herb layer-seed bank community. ResultsSeed banks consistently held more plant species than the herb layer. How local plot diversity was partitioned across the herb layer and seed bank was mediated by environmental variation in drivers serving as proxies of light availability. The herb layer and seed bank contained an ever smaller and ever larger share of local diversity, respectively, as both canopy cover and time since last canopy disturbance decreased. Species richness and -diversity of the combined herb layer-seed bank community responded distinctly differently compared to the separate assemblages in response to environmental variation in, e.g. forest cover continuity and canopy cover. ConclusionsThe seed bank is a below-ground diversity reservoir of the herbaceous forest community, which interacts with the herb layer, although constrained by environmental variation in e.g. light availability. The herb layer and seed bank co-exist as a single community by means of the so-called storage effect, resulting in distinct responses to environmental variation not necessarily recorded in the individual herb layer or seed bank assemblages. Thus, concurrently analysing above- and below-ground diversity will improve our ecological understanding of how understorey plant communities respond to environmental variation.

  • 13.
    Plue, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hermy, Martin
    Consistent seed bank spatial structure across semi natural habitats determines plot sampling2012In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 23, no 3, p. 505-516Article in journal (Refereed)
    Abstract [en]

    Question: Seed bank sampling remains a critical bottleneck to the quality of studies investigating community patterns in the seed bank. The main cause is a large knowledge gap in two aspects critical to sampling, i. e. spatial autocorrelation and species-area relations. The central question of this study is howthe seed bank of a single plot should be sampled, in order to obtain more precise estimates on plot seed bank characteristics, without resorting to a disproportionate investment of available resources. Similar seed bank samples may then enable better plot-based statistical inference of ecological patterns in the seed bank in community ecology studies. Location: Semi-natural habitats in Flanders (Belgium) and northern France. Methods: We investigated the fine-scale spatial structure of individual seed banking species across 12 2.1 m 9 2.1 m plots in three widespread habitats: temperate forest, grassland and heathland. Soil core samples (128) were collected in each plot, using a combined systematic (64) and random design (64). This enabled both geostatistical analyses of the fine-scale spatial structure of individual species-plot combinations as well as the calculation of sampled-based species rarefaction curves. Results: Fine-scale (i. e. within plot) spatial seed bank structure was detected in all plots in each habitat, in at least one or usually more plant species. Over half of the species records displayed significant spatial structure -visible as a random distribution of seed clusters -with medium to strong spatial dependence between point observations of a species of ca. 30 cm. Species rarefaction curves did not attain an asymptote at the actual sampling intensity of 128 samples. Seven out of 12 extrapolated species rarefaction curves did reach an asymptote in less than 384 samples. Conclusions: Using these consistent results in spatial structure and species-area relations across habitats, we present a method of how researchers can develop a tailor-made seed bank design to accommodate their individual needs, abiding by simple predefined boundaries. When the tailored design samples ca. 3% of a plot surface area along a systematic grid with a mesh width of at least 30 cm, these studies will potentially significantly increase the comparability among future seed bank community studies in semi-natural habitats.

  • 14. 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.

  • 15.
    Schmalholz, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Granath, Gustaf
    Effects of microhabitat and growth form on bryophyte mortality associated with leaf litter burial in a boreal spruce forest2014In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 25, no 2, p. 439-446Article in journal (Refereed)
    Abstract [en]

    Questions Do mortality rates of boreal bryophytes associated with leaf litter burial vary with degree of shelter on forest floor microsites in spruce-dominated forests? Do erect and prostrate species respond similarly? What is the relative importance of deciduous leaves (from aspen and birch) vs conifer needles as bryophyte mortality agents? Location Boreal spruce forests of central Sweden. Methods A transplant study examining mortality was set up with four different bryophyte species: two creeping, prostrate liverworts (Calypogeia integristipula and Lepidozia reptans) and two more erect mosses (Rhytidiadelphus triquetrus and Hylocomiastrum umbratum). We tested for differences in mortality rates associated with leaf litter burial in three microhabitats differing in degree of shelter on the forest floor, i.e. sheltered (large boulders, tree bases of spruce) and unsheltered (open forest floor). Results After two growing seasons, 12.7% of the bryophyte transplants (40 out of 316, of which 37 transplants were prostrate liverworts) were dead, presumably due to litter burial. These two prostrate liverworts displayed significantly higher mortality rates close to boulders and at tree bases compared to unsheltered forest floors. Furthermore, although only comprising a small portion of the canopy (<10%), deciduous litter accounted for 53% of all transplants that were buried by litter, compared to 47% for conifer needle litter. Conclusion We find fine-scale spatial patchiness in the responses of bryophytes to litter fall. Mortality of prostrate liverworts associated with litter burial varies among microhabitats on the forest floor, with significantly higher mortality at sheltered microsites (here exemplified by boulders and tree bases) compared to erect moss species. Bryophytes close to microtopographic structures (e.g. boulders and trees) are more strongly exposed to litter burial, but such structures can also function as refuges under disturbance events such as clear-cuts and windthrows. In addition, they may contain convex surfaces that accumulate less litter than flat or convex forest floor surfaces. The observed large effect of litter burial associated with bryophyte mortality, and the variation among microhabitats and species growth forms, suggest that incorporation of litter fall is of vital importance for our understanding of the dynamics of forest bryophyte communities.

  • 16. Wasof, Safaa
    et al.
    Lenoir, Jonathan
    Hattab, Tarek
    Jamoneau, Aurélien
    Gallet-Moron, Emilie
    Ampoorter, Evy
    Saguez, Robert
    Bennsadek, Lamine
    Bertrand, Romain
    Valdès, Alicia
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Jules Verne University of Picardie, France.
    Verheyen, Kris
    Decocq, Guillaume
    Dominance of individual plant species is more important than diversity in explaining plant biomass in the forest understorey2018In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 29, no 3, p. 521-531Article in journal (Refereed)
    Abstract [en]

    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.

  • 17.
    Öster, Mathias
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Size and heterogeneity rather than landscape context determine plant species richness in semi-natural grasslands2007In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 18, no 6, p. 859-868Article in journal (Refereed)
    Abstract [en]

    Question: Is plant diversity in fragmented semi-natural grasslands related to present and historical landscape context?

    Location: Southern Sweden.

    Methods: Plant diversity was described at 30 semi-natural grassland sites in terms of total and specialist plant species richness at the site and species density at different scales (0.5–10 m2). These measures are commonly used to assess conservation value of semi-natural grasslands. Landscape context was measured as contemporary connectivity to other semi-natural grasslands, historical connectivity 50 years ago, amount of linear elements potentially suitable for dispersal (road verges, power line clearings), and amount of forest (inverse of the openness of the landscape).

    Results: The diversity measures were generally correlated with each other, implying that species richness in a subset of the grassland can predict the total richness. Plant species density at three scales (0.5 m2, 10 m2 and total) was related to the landscape context using an information theoretic approach. Results showed that total species richness increased with increased size of grasslands, contrary to earlier diversity studies in semi-natural grasslands. Larger grasslands were more heterogeneous than smaller grasslands, and this is a likely reason for the species-area relationship. Heterogeneity was also of high importance at the smaller scales (0.5 m2, 10 m2). With increased amount of forest, total species richness increased but species density on 10 m2 decreased. There was no influence of connectivity in either the contemporary or the historical landscape, contrary to previous studies.

    Conclusions: Grassland size and heterogeneity are of greater importance for plant diversity in semi-natural grassland, than grassland connectivity in the landscape.

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