Plant trait-mediated drag forces on seedlings of four tidal marsh pioneer species

Salt marshes play an important role in coastal protection by reducing the impact of waves and shoreline erosion risks. While mature vegetation is responsible for the persistence and stability of marsh ecosystems, seedling survival of pioneer species is especially crucial for marsh propagation. Marsh seedlings, however, may be threatened by climate change induced increased coastal storm surge intensity and accompanying (extreme) wave conditions, imposing stronger drag forces on marsh seedlings. We test the hypothesis that drag forces experienced by seedlings increase with horizontal orbital velocity (Uw) in a species-specific manner, and that the drag forces experienced are individual-plant trait-mediated. To test our hypotheses, seedlings of four contrasting pioneer marsh species (Bolboschoenus maritimus, Schoenoplectus tabernaemontani, Spartina anglica, and Puccinellia maritima) were exposed to storm wave conditions in a flume, where Uw and experienced drag forces were measured. Linear mixed effect models demonstrated that seedling’s susceptibility to storm wave conditions is at least partly mediated by individual plant traits. Drag forces experienced by seedlings tended to increase with Uw, and with stem length and diameter. The interplay of both traits was complex, with increasing stem length being the most important trait accounting for increases in drag forces experienced at low to moderate Uw, while the stem diameter became more important with increasing Uw. Furthermore, experienced drag forces appeared to be affected by species-specific traits such as rigidity and leaf growth, being highest for Bolboschoenus maritimus and lowest for Puccinellia maritima. Our results provide important mechanistic insights into the drivers of tidal marsh seedling vulnerability to storm wave conditions due to experienced drag, both based on the traits of individual plants and species-specific ones. This type of knowledge is of key importance when modelling saltmarsh establishment and resilience under climate change

GrassPlot v. 2.00 – first update on the database of multi-scale plant diversity in Palaearctic grasslands

Abstract: GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). Following a previous Long Database Report (Dengler et al. 2018, Phyto- coenologia 48, 331–347), we provide here the first update on content and functionality of GrassPlot. The current version (GrassPlot v. 2.00) contains a total of 190,673 plots of different grain sizes across 28,171 independent plots, with 4,654 nested-plot series including at least four grain sizes. The database has improved its content as well as its functionality, including addition and harmonization of header data (land use, information on nestedness, structure and ecology) and preparation of species composition data. Currently, GrassPlot data are intensively used for broad-scale analyses of different aspects of alpha and beta diversity in grassland ecosystems

GrassPlot - a database of multi-scale plant diversity in Palaearctic grasslands

GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database " sPlot". Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board

Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes

The aim of this thesis was to increase knowledge about metapopulation and metacommunity processes in patchy, dynamic landscapes, using epiphytic bryophytes as a model system. Host trees and deciduous forest stands in the coniferous landscape are patchy, temporal and undergo changes in habitat quality during succession. Epiphytes must track this dynamic habitat network for their long-term survival. Community patterns at different spatial scales were explored and linked to regional metapopulation processes and local population dynamics. Spatial structuring in species richness both at a local and regional scale indicated stronger dispersal limitation but lower sensitivity to habitat quality in species with large asexual than in species with small sexual diaspores. In sexually dispersed species, a strong rescue effect was indicated by a bimodal frequency distribution of the species and by increasing local abundance with increasing patch connectivity. Present connectivity to other deciduous forest patches had positive effects on richness of asexually dispersed species, whereas richness of sexually dispersed species was instead related to the landscape connectivity 30 years ago. A study of local growth and reproduction suggested that this is caused by delayed sexual, but not asexual, reproduction. Habitat conditions affected the production of sporophytes, but not of asexual diaspores. No differences in either growth rates or competitive abilities among species with different dispersal and life-history strategies were found. In vitro experiments showed that establishment is higher from large asexual diaspores than from small sexual. Establishment of all diaspore types was limited by pH. There were indications of trade-offs between high germination and protonemal growth rates, desiccation tolerance and a rapid development of shoots from protonema. The results indicated that the epiphyte metacommunity is structured by two main trade-offs: dispersal distance (diaspore size) versus age at first reproduction, and dispersal distance versus sensitivity to habitat quality. Trade-offs in species traits may have evolved as a consequence of conflicting selection pressures imposed by habitat turnover, connectivity and irregular water supply rather than by species interactions. Syndromes of interrelated species traits imply that fairly small changes in habitat conditions can lead to distinct changes in metacommunity diversity: the results indicate that increasing distances among patches cause most harm to asexually dispersed species, whereas cuttings of forests of high age and quality as well as increasing patch dynamics are most harmful to sexually dispersed species.Senarelagd disputation från: 2009-09-26, Lindahlsalen, EBC, Villavägen 9, 75236 Uppsala, Uppsala, 10:0

Species distribution modelling data for 23 dead-wood inhabiting bryophytes

These data consist of (inferred) presence-absence records for 23 dead-wood inhabiting bryophytes in Sweden and the associated environmental variables at each data point at the 100 m grid cell resolution. The data were applied to fit single species distribution models, and multi-species predictive fourth-corner models. Full details of data compilation, sources and application can be found in: Löbel, S., Mair, L., Lönnell, N., Schröder, B., & Snäll, T. (2018). Biological traits explain bryophyte species distributions and responses to forest fragmentation and climatic variation. Journal of Ecology, 106(4), 1700-1713. doi:10.1111/1365-2745.12930Antagna artförekomstdata för 23 bryofyter i trä i Sverige. Se den engelska katalogsidan för utförligare information: https://snd.gu.se/en/catalogue/study/ECDS0251 Fullständig information om datasamling, källor och applikationer finns i: Löbel, S., Mair, L., Lönnell, N., Schröder, B., & Snäll, T. (2018). Biological traits explain bryophyte species distributions and responses to forest fragmentation and climatic variation. Journal of Ecology, 106(4), 1700-1713. doi:10.1111/1365-2745.1293

Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes

The aim of this thesis was to increase knowledge about metapopulation and metacommunity processes in patchy, dynamic landscapes, using epiphytic bryophytes as a model system. Host trees and deciduous forest stands in the coniferous landscape are patchy, temporal and undergo changes in habitat quality during succession. Epiphytes must track this dynamic habitat network for their long-term survival. Community patterns at different spatial scales were explored and linked to regional metapopulation processes and local population dynamics. Spatial structuring in species richness both at a local and regional scale indicated stronger dispersal limitation but lower sensitivity to habitat quality in species with large asexual than in species with small sexual diaspores. In sexually dispersed species, a strong rescue effect was indicated by a bimodal frequency distribution of the species and by increasing local abundance with increasing patch connectivity. Present connectivity to other deciduous forest patches had positive effects on richness of asexually dispersed species, whereas richness of sexually dispersed species was instead related to the landscape connectivity 30 years ago. A study of local growth and reproduction suggested that this is caused by delayed sexual, but not asexual, reproduction. Habitat conditions affected the production of sporophytes, but not of asexual diaspores. No differences in either growth rates or competitive abilities among species with different dispersal and life-history strategies were found. In vitro experiments showed that establishment is higher from large asexual diaspores than from small sexual. Establishment of all diaspore types was limited by pH. There were indications of trade-offs between high germination and protonemal growth rates, desiccation tolerance and a rapid development of shoots from protonema. The results indicated that the epiphyte metacommunity is structured by two main trade-offs: dispersal distance (diaspore size) versus age at first reproduction, and dispersal distance versus sensitivity to habitat quality. Trade-offs in species traits may have evolved as a consequence of conflicting selection pressures imposed by habitat turnover, connectivity and irregular water supply rather than by species interactions. Syndromes of interrelated species traits imply that fairly small changes in habitat conditions can lead to distinct changes in metacommunity diversity: the results indicate that increasing distances among patches cause most harm to asexually dispersed species, whereas cuttings of forests of high age and quality as well as increasing patch dynamics are most harmful to sexually dispersed species.Senarelagd disputation från: 2009-09-26, Lindahlsalen, EBC, Villavägen 9, 75236 Uppsala, Uppsala, 10:0

Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes

The aim of this thesis was to increase knowledge about metapopulation and metacommunity processes in patchy, dynamic landscapes, using epiphytic bryophytes as a model system. Host trees and deciduous forest stands in the coniferous landscape are patchy, temporal and undergo changes in habitat quality during succession. Epiphytes must track this dynamic habitat network for their long-term survival. Community patterns at different spatial scales were explored and linked to regional metapopulation processes and local population dynamics. Spatial structuring in species richness both at a local and regional scale indicated stronger dispersal limitation but lower sensitivity to habitat quality in species with large asexual than in species with small sexual diaspores. In sexually dispersed species, a strong rescue effect was indicated by a bimodal frequency distribution of the species and by increasing local abundance with increasing patch connectivity. Present connectivity to other deciduous forest patches had positive effects on richness of asexually dispersed species, whereas richness of sexually dispersed species was instead related to the landscape connectivity 30 years ago. A study of local growth and reproduction suggested that this is caused by delayed sexual, but not asexual, reproduction. Habitat conditions affected the production of sporophytes, but not of asexual diaspores. No differences in either growth rates or competitive abilities among species with different dispersal and life-history strategies were found. In vitro experiments showed that establishment is higher from large asexual diaspores than from small sexual. Establishment of all diaspore types was limited by pH. There were indications of trade-offs between high germination and protonemal growth rates, desiccation tolerance and a rapid development of shoots from protonema. The results indicated that the epiphyte metacommunity is structured by two main trade-offs: dispersal distance (diaspore size) versus age at first reproduction, and dispersal distance versus sensitivity to habitat quality. Trade-offs in species traits may have evolved as a consequence of conflicting selection pressures imposed by habitat turnover, connectivity and irregular water supply rather than by species interactions. Syndromes of interrelated species traits imply that fairly small changes in habitat conditions can lead to distinct changes in metacommunity diversity: the results indicate that increasing distances among patches cause most harm to asexually dispersed species, whereas cuttings of forests of high age and quality as well as increasing patch dynamics are most harmful to sexually dispersed species.Senarelagd disputation från: 2009-09-26, Lindahlsalen, EBC, Villavägen 9, 75236 Uppsala, Uppsala, 10:0

Felsgrusgesellschaften (Sedo-Scleranthenea) im nördlichen Europa

We studied the dry grasslands of shallow, skeletal soils (Sedo-Scleranthenea, Koelerio-Corynephoretea) in northern Europe, based on a combination of new relevés from southern Oland (Sweden, n = 182) and Saaremaa (Estonia, n = 73) as well as a comprehensive evaluation of literature data, of which 65 suitable relevés were directly included in our analyses. Apart from a few vague indications of acidophytic Sedo-Scleranthenea communities (order Sedo-Scleranthetalia), all data refer to basiphytic communities (Alysso-Sedetalia); our analyses are thus focussed on the latter. The Nordic Alysso-Sedetalia communities proved to be quite different from their temperate counterparts and thus are included in a separate alliance, Tortello tortuosae-Sedion albi, which forms the northern counterpart to the central European Alysso-Sedion. Within the northern alliance, we distinguish two suballiances. The more widespread central suballiance Tortello tortuosae-Sedenion albi inhabits different types of base-rich substrata in both natural and anthropogenic sites, and is comprised of the Cladonio symphicarpiae-Sedetum albi and the Ditricho flexicaulis-Sedetum acris. The second suballiance Tortello rigentis-Helianthemenion oelandici is restricted to the alvar sites (= treeless limestone plateaus) in Oland, Gotland, Västergötland and Estonia. It is characterised by several endemic taxa and a large number of cryptogams typical of alvar. It is comprised of four associations, Crepido pumilae-Allietum alvarensis, Fulgensio bracteatae-Poetum alpinae, Helianthemo oelandici-Galietum oelandici and Gypsophilo fastigiatae-Globularietum vulgaris. All six Nordic associations are described in detail with respect to their floristic composition, ecology, distribution and lower-ranked units, and each is represented by a vegetation table. The floristic differences within the Nordic communities are worked out in a synoptic table. Whereas several vegetation scientists have pointed out that vegetation types occurring at the limits of their distribution ranges in northern Europe are generally difficult to classify, our application of the Braun-Blanquet approach, which is based on a priori separated structural types and the general application of the central syntaxon concept, has enabled us to characterise and adequately define all Nordic communities. The Tortello-Sedion associations are two to three times as species-rich as those of the Alysso-Sedion and are among the most diverse small-scale plant communities ever described. We discuss the reasons for this exceptionally high plant diversity and the peculiar species mixture in the Tortello-Sedion and compare the relationship between Alysso-Sedion and Tortello-Sedion to the situation of other Nordic syntaxa of predominantly temperate vegetation types. Our results further underline the uniqueness of Baltic alvars and their paramount importance for conservation at the European level.Wir haben die Felsgrusgesellschaften (Sedo-Scleranthenea, Koelerio-Corynephoretea) Nordeuropas auf der Basis eigener Aufnahmen aus Süd-Öland (Schweden, n = 182) und Saaremaa (Estland, n = 73) sowie einer umfassenden Auswertung der Literatur (davon fanden 65 geeignete Aufnahmen unmittelbar in den Analysen Verwendung) untersucht. Abgesehen von spärlichen und vagen Hinweisen auf bodensaure Sedo-Scleranthenea-Gesellschaften (Sedo-Scleranthetalia) beziehen sich alle verfügbaren Daten auf basiphytische Typen (Alysso-Sedetalia), weswegen wir uns im Kern mit diesen beschäftigen. Die nordischen Alysso-Sedetalia-Gesellschaften unterscheiden sich erheblich von ihren in der temperaten Zone verbreiteten Pendants. Daher stellen wir sie als eigenen Verband Tortello tortuosae-Sedion albi dem mitteleuropäischen Alysso-Sedion gegenüber. Innerhalb des nordischen Verbandes lassen sich zwei Unterverbände trennen. Der relativ weit verbreitete zentrale Unterverband Tortello tortuosae-Sedenion albi besiedelt unterschiedliche basenreiche Substrate sowohl natürlichen als auch anthropogenen Ursprungs. Der zweite Unterverband Tortello rigentis-Helianthemenion oelandici ist auf die Alvare (= baumfreie Kalksteinplateaus) in Öland, Gotland, Västergötland und Estland beschränkt. Er ist durch eine Reihe endemischer Sippen sowie viele alvartypische Kryptogamen gekennzeichnet und umfasst vier Assoziationen: Crepido pumilae-Allietum alvarensis, Fulgensio bracteatae-Poetum alpinae, Helianthemo oelandici-Galietum oelandici und Gypsophilo fastigiatae-Globularietum vulgaris. Die sechs nordischen Assoziationen werden detailliert bezüglich floristischer Zusammensetzung, Ökologie, Verbreitung und Untergliederung beschrieben und mit je einer Vegetationstabelle präsentiert. Die floristischen Unterschiede der nordischen Gesellschaften untereinander illustrieren wir in einer Stetigkeitstabelle. Zwar haben verschiedene Vegetationskundler in der Vergangenheit darauf hingewiesen, dass es generell schwierig sei, Vegetationstypen zu klassifizieren, die in Nordeuropa am Rande ihres Synareals Vorkommen, doch ermöglichte unsere Konkretisierung des Braun-Blanquet-Ansatzes, die auf einer strukturtypenbezogenen Klassifikation und der Anwendung des Zentralsyntaxonkonzeptes auf allen hierarchischen Ebenen beruht, eine sachgerechte Charakterisierung und Klassifizierung aller in Nordeuropa vorkommenden Typen. Die Artendichte in den Tortello-Sedion-Assoziationen ist zwei- bis dreimal so hoch wie im Alysso-Sedion, womit die basiphilen Felsgrusgesellschaften Nordeuropas zu den auf kleinen Flächen artenreichsten Vegetationstypen überhaupt gehören. Wir diskutieren Gründe der herausragenden Phytodiversität und der eigentümlichen Artenzusammensetzung des Tortello-Sedion und vergleichen die Unterschiede zwischen Tortello-Sedion und Alysso-Sedion mit der Situation in anderen nordischen Syntaxa. Unsere Ergebnisse unterstreichen die Einzigartigkeit der baltischen Alvargesellschaften und ihre herausragende Bedeutung für den Naturschutz auf europäischer Ebene