Potential contribution of surface-dwelling Sargassum algae to deep-sea ecosystems in the southern North Atlantic

Deep-sea ecosystems, limited by their inability to use primary production as a source of carbon, rely on other sources to maintain life. Sedimentation of organic carbon into the deep sea has been previously studied, however, the high biomass of sedimented Sargassum algae discovered during the VEMA Transit expedition in 2014/2015 to the southern North Atlantic, and its potential as a regular carbon input, has been an underestimated phenomenon. To determine the potential for this carbon flux, a literature survey of previous studies that estimated the abundance of surface water Sargassum was conducted. We compared these estimates with quantitative analyses of sedimented Sargassum appearing on photos taken with an autonomous underwater vehicle (AUV) directly above the abyssal sediment during the expedition. Organismal communities associated to Sargassum fluitans from surface waters were investigated and Sargassum samples collected from surface waters and the deep sea were biochemically analyzed (fatty acids, stable isotopes, C:N ratios) to determine degradation potential and the trophic significance within deep-sea communities. The estimated Sargassum biomass (fresh weight) in the deep sea (0.07 − 3.75 g/m2) was several times higher than that estimated from surface waters in the North Atlantic (0.024 – 0.84 g/m2). Biochemical analysis showed degradation of Sargassum occurring during sedimentation or in the deep sea, however, fatty acid and stable isotope analysis did not indicate direct trophic interactions between the algae and benthic organisms. Thus, it is assumed that components of the deep-sea microbial food web form an important link between the macroalgae and larger benthic organisms. Evaluation of the epifauna showed a diverse nano- micro-, meio, and macrofauna on surface Sargassum and maybe transported across the Atlantic, but we had no evidence for a vertical exchange of fauna components. The large-scale sedimentation of Sargassum forms an important trophic link between surface and benthic production and has to be further considered in the future as a regular carbon input to the deep-sea floor in the North Atlantic

ReSurveyGermany: Vegetation-plot time-series over the past hundred years in Germany

Vegetation-plot resurvey data are a main source of information on terrestrial biodiversity change, with records reaching back more than one century. Although more and more data from re-sampled plots have been published, there is not yet a comprehensive open-access dataset available for analysis. Here, we compiled and harmonised vegetation-plot resurvey data from Germany covering almost 100 years. We show the distribution of the plot data in space, time and across habitat types of the European Nature Information System (EUNIS). In addition, we include metadata on geographic location, plot size and vegetation structure. The data allow temporal biodiversity change to be assessed at the community scale, reaching back further into the past than most comparable data yet available. They also enable tracking changes in the incidence and distribution of individual species across Germany. In summary, the data come at a level of detail that holds promise for broadening our understanding of the mechanisms and drivers behind plant diversity change over the last century

<scp>ReSurveyEurope</scp>: A database of resurveyed vegetation plots in Europe

AbstractAimsWe introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions.ResultsReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun‐Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020.ConclusionsReSurveyEurope is a new resource to address a wide range of research questions on fine‐scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well‐established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.</jats:sec

Gisbert Große-Brauckmann (1926-2001)

Am 25. April verstarb im 75. Lebensjahr nach langer schwerer Krankheit Gisbert Große-Brauckmann. In Göttingen am 12. Mai 1926 geboren, wuchs er in einem durch die Altphilologie geprägten Elternhaus auf. Vater und Großvater waren Altphilologen; dennoch zeigte sich schon früh das besondere Interesse von Gisbert Große-Brauckmann für die Biologie und insbesondere die Botanik

Zur Soziologie Alnus incana-reicher Waldgesellschaften im Schwarzwald unter besonderer Berücksichtigung der Phänologie

Alnus incana-reiche Waldgesellschaften haben im Schwarzwald eine sehr spezifische Verbreitung und sind auf ein kleineres Gebiet südlich und südöstlich des Feldbergs beschränkt, wo sie in einer Höhenlage von 620 bis 1100 m ü.M. stocken. Es handelt sich um winterkalte Gebiete mit 150 Frosttagen oder mehr, die würmglazial überformt wurden und mächtige fluvioglaziale Schotterkörper haben. Die Gewässer erreichen ihre Abflussmaxima im April. In diesen Gebieten fehlt Alnus glutinosa aus wärmeklimatischen Gründen. Es konnten mit Hilfe der pflanzensoziologischen Tabelle vier voneinander verschiedene Standortstypen ausgeschieden werden, die von der Grauerle besiedelt werden und z.T. kleinstandörtlich weiter untergliederbar sind: a) Der bach- und flußbegleitende Grauerlenwald (Alnetum incanae) mit den Subassoziationen "typicum" und "aceretosum" sowie Varianten und Höhenformen; b) der Alnus incana-Rangwald; c) der Alnus incana-Bruchwald; d) die Alnus incana-Carex remota-Ges. (nur als Fragment). Hinzu kommt als weiterer Typ der Alnus incana-Weidewald. Besonderes Augenmerk galt der Untersuchung der Symphänologie verschiedener Höhenformen des Alnetum incanae, die eine Reihe zeitlich gestaffelter Blumenwellen erkennen lässt. Ferner wurden synökologische Untersuchungen (Bodenprofile, pH-Werte während der Vegetationsperiode) durchgeführt. Alnus incana-reiche Gesellschaften des Schwarzwaldes sind aus biologischen, landschaftspflegerischen und landschaftsästhetischen Gründen besonders schützenswerte Vegetationseinheiten.Alnus incana-rich forest communities in the Black Forest have a very specific distribution restricted to a small area south and southeast of the Feldberg, where they grow from 620 to 1100 m above sea level. These regions have rather low winter temperatures, with 150 or more frost days per year. These areas were formed during the Würm glacial period and have thick fluvioglacial deposits. Streamflow is highest in April. In these regions Alnus glutinosa is absent due to insufficient warmth. By means of phytosociological tables it was possible to distinguish four site-related Alnus incana communities: a) Alnetum incanae along streams, with subassociations typicum and aceretosum plus different variants and altitudinal forms; b) Alnus incana community on slopes; c) Alnus incana swamp forest; d) Alnus incana-Carex remota community (only fragmentary stands). Grazed Alnus incana woodlands can be considered an additional type. The comparative symphenological investigation of different altitudinal forms of the Alnetum incanae deserves special attention, since it shows a clear staggering of flowering times ("flowering waves"). Synecological investigations (soil profiles, pH measurements) were also carried out. On account of their biological, ecological and aesthetical importance to the landscape, Alnus incana woodlands are especially deserving of protection

Veränderungen in montanen Borstgrasrasen durch Düngung und Brachlegung : Antennaria dioica und Vaccinium vitis-idaea als Indikatoren

Durch vergleichende vegetationskundliche Untersuchungen in den Jahren 1977/78 und 1989 sowie Dauerquadrat-Untersuchungen konnte belegt werden, dass 2 Indikatorarten: Antennaria dioica (L.) Gaertn. und Vaccinium vitis-idaea L. sehr viel rascher auf Düngungseinflüsse reagieren als die Phytocoenose (Festuco-Genistetum sagittalis). Aktualistische Vergleiche der pflanzenverfügbaren N- und P-Gehalte im Oberboden belegen gering erhöhte Ammonium-Werte in Flächen, denen die beiden Arten inzwischen fehlen. Stärkere Rückgänge in Flächen mit Düngereinfluss zeigt auch Calluna vulgaris. Schon bei geringen Intensitätssteigerungen der Rinderbeweidung wird Antennaria in dem dichter werdenden Rasen verdrängt, Vaccinium vitis-idaea stirbt bei Faeces-Einwirkung ab. In Brachen verhalten sich beide Arten verschieden: Antennaria vermag sich in höherwüchsigen Brachen nicht zu halten; Vaccinium vitis-idaea zeigt auch in Brachen gute Vitalität. Antennaria dioica hat in extensiv beweideten Flächen und in Brachen unterschiedliche Wuchsformen: an offenen Stellen bildet die Pflanze oberirdische plagiotrop wachsende Stolonen; es können sich hier pro Jahr und Altrosette bis zu 5 junge Rosetten bilden. In höherwüchsigen Brachen wachsen die Stolonen orthotrop und bilden einen Rosettenschopf, der bald sein Wachstum einstellt. Die Keimraten sind nach experimentellen Untersuchungen sehr gering; eine Samenbank wird nach allen bisherigen Befunden auch anderer Autoren nicht aufgebaut. Floristische Änderungen in Brachen, die auf atmogene N-Immissionen zurückgeführt werden könnten, sind (noch) nicht festzustellen. Auch die Calluna-Populationen haben sich hier halten können, und die Standorte weisen in den Brache-Untersuchungsflächen keine Vergrasungserscheinungen auf. Antennaria dioica und Vaccinium vitis-idaea eignen sich als Monitor-Organismen für N-Dünger-freie Bewirtschaftung.It was possible to show by comparative phytosociological research in 1977/78 and 1989 and by permanent-plot investigations, that the reaction of two indicator species (Antennaria dioica and Vaccinium vitis-idaea) to fertilization is quicker than the reaction of the phytocoenosis in general (Festuco-Genistetum sagittalis). Comparisons of Nmin and Pmin contents in the Ah-horizon show slightly increased values of NH4-N in areas where both species were absent in 1989. Vanishing populations of Calluna vulgaris can also be recognized here. Even if the increase of grazing intensity is low, Antennaria is displaced by the dense grass canopy while Vaccinium vitis-idaea dies from the direct influence of feces deposition. Antennaria dioica and Vaccinium vitis-idaea show different behaviour in abandoned land. While Antennaria cannot exist at all, Vaccinium vitis-idaea still shows good vitality. Antennaria shows different growth forms in extensively grazed areas and in fallow land, areas with gaps are characterized by creeping stolons with plagiotropic growth. In such situations Antennaria can produce up to five young rosettes per old rosette. In fallow land with tall grass the stolons grow orthotropically and produce a tuft of rosettes, which soon stops growing. Experiments have shown that the rates of germination are very low in such situations, and a soil seed bank has not been found by this or other authors. Floristic changes in fallow land caused by atmogenic nitrogen immissions could not yet be identified including the continuation of the Calluna populations and the lack of increase of the grasses. Antennaria dioica and Vaccinium vitis-idaea show themselves as indicator species for cultivation without N-fertilization

1. Workshop der Floristisch-soziologischen Arbeitsgemeinschaft „Floristik und Geobotanik - Beiträge zu angewandten Fragestellungen“ an der Technischen Universität Darmstadt

Die Floristisch-soziologische Arbeitsgemeinschaft hat bisher - außer im Rahmen von Arbeitskreisen - keine Tagungsveranstaltung angeboten, die unabhängig von den Jahrestagungen mit Exkursion bestimmte Themen aufgreift und diskutiert. Auf Vorschlag von unserem jetzigen Ehrenmitglied Prof. Dr. E.-G. Mahn (Halle/Saale) und von Dr. P. Thomas (Hatzenbühl) wurde bereits auf der Mitgliederversammlung in Erlangen 2005 auf den Bedarf zusätzlicher Aktivitäten der Arbeitsgemeinschaft, z. B. zu praxisrelevanten Fragen, hingewiesen. An dem 1. Workshop in Darmstadt nahmen etwa 70 Mitglieder und Interessenten teil. Die insgesamt 14 Vorträge und 16 Poster-Demonstrationen deckten eine breite Palette angewandter Fragestellungen ab. Eine Kooperation mit der „Arbeitsgemeinschaft Forstliche Standorts- und Vegetationskunde“, die auf der Mitgliederversammlung 2006 beschlossen wurde (Tuexenia 27: WALENTOWSKI et al., Waldoekologie online 3: 102) spiegelte sich bereits bei diesem Workshop mit insgesamt vier waldökologischen Vorträgen und drei Postern wider

Sheep versus donkey grazing or mixed treatment : results from a 4-year field experiment in Armerio-Festucetum trachyphyllae sand vegetation

The abandonment of former land-use often leads to an increasing grass encroachment and a related decrease in plant species richness. Extensive grazing can be an adequate management method, but the effects on the vegetation depend on the livestock species. We investigated two different subtypes of the Armerio-Festucetum trachyphyllae Hohenester 1960 (Armerion elongatae Poetsch 1962) where the Armerio-Festucetum trachyphyllae typicum is characterised by a stronger topsoil acidification and a denser vegetation sward than the Festuca duvalii subtype. The investigation area is a dry and nutrient-poor inland sand ecosystem located in the Upper Rhine Valley (Germany). Therefore we chose local sheep breeds and donkeys as grazing animals which are adapted to these conditions. In four vegetation periods (2002-2005), the influence of sheep grazing (s), donkey grazing (d) and successive sheep and donkey grazing (s+d) on the floristic structure of the plant communities was investigated. For both vegetation subtypes, every treatment was replicated thrice on paddocks 700 m(2) in area. The vegetation was recorded by 1200 releves (2002-2005: s, d) and by further 429 releves (2003-2005: s+d). Additionally, we obtained data on species composition, nitrogen input and phytomass at special donkey-generated microsites. The factors "year" and "vegetational subtype" had a strong influence on vegetation parameters. For all investigated treatments, nature management goals such as an increase of herbs and a decrease of grasses and litter are reached. Species number, especially therophytes, was higher for donkey grazing than for sheep grazing. But since donkey grazing produced a nitrogen input of 223 kg N * ha(-1) at the donkeys' faeces accumulation sites, ungrazed areas covering 4% of the paddock area, the combination of sheep and donkeys can also become an important management tool because with the mixed grazing regime no ungrazed areas occur