To eat or not to eat—relationship of lichen herbivory by snails with secondary compounds and field frequency of lichens

Aims The biochemical defense of lichens against herbivores and its relationship to lichen frequency are poorly understood. Therefore, we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen frequency in the field. Methods In a no-choice feeding experiment, we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing. Then, we related experimental lichen consumption with the frequency of lichen species among 158 forest plots in the field (Schwäbische Alb, Germany), where we had also sampled snail and lichen species. Important findings In five lichen species, snails preferred treated samples over untreated controls, indicating chemical feeding defense, and vice versa in two species, indicating chemical feeding stimulus. Interestingly, compared with less frequent lichen species, snails consumed more of untreated and less of treated samples of more frequent lichen species. Removing one outlier species resulted in the loss of a significant positive relationship when untreated samples were analyzed separately. However, the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa, indicating that our results were robust and that lumping the species to two taxa was justified. Our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound recognition. This supports the idea that consumers adapt to the most abundant food sourc

Species–area relationships in continuous vegetation : evidence from Palaearctic grasslands

Aim: Species-area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas power laws best represent SARs. Yet, it remains unclear whether SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape. Location: Palaearctic grasslands and other non-forested habitats. Taxa: Vascular plants, bryophytes and lichens. Methods: We used the GrassPlot database, containing standardised vegetation-plot data from vascular plants, bryophytes, and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2057 nested-plot series with at least seven grain sizes ranging from 1 cm2 to 1024 m². Using non-linear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis-Menten). Based on AICc, we tested whether the ranking of functions differed among taxa, methodological settings, biomes or vegetation types. Results: The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted-presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law. Main conclusions: We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis-Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area

Lichen Endozoochory by Snails

Endozoochory plays a prominent role for the dispersal of seed plants. However, for most other plant taxa it is not known whether this mode of dispersal occurs at all. Among those other taxa, lichens as symbiotic associations of algae and fungi are peculiar as their successful dispersal requires movement of propagules that leaves the symbiosis functional. However, the potential for endozoochorous dispersal of lichen fragments has been completely overlooked. We fed sterile thalli of two foliose lichen species (Lobaria pulmonaria and Physcia adscendens) differing in habitat and air-quality requirements to nine snail species common in temperate Europe. We demonstrated morphologically that L. pulmonaria regenerated from 29.0% of all 379 fecal pellets, whereas P. adscendens regenerated from 40.9% of all 433 fecal pellets, showing that lichen fragments survived gut passage of all snail species. Moreover, molecular analysis of regenerated lichens confirmed the species identity for a subset of samples. Regeneration rates were higher for the generalist lichen species P. adscendens than for the specialist lichen species L. pulmonaria. Furthermore, lichen regeneration rates varied among snail species with higher rates after gut passage of heavier snail species. We suggest that gastropods generally grazing on lichen communities are important, but so far completely overlooked, as vectors for lichen dispersal. This opens new ecological perspectives and questions the traditional view of an entirely antagonistic relationship between gastropods and lichens

Gastropods slow down succession and maintain diversity in cryptogam communities

Herbivore effects on diversity and succession were often studied in plants, but not in cryptogams. Besides direct herbivore effects on cryptogams, we expected indirect effects by changes in competitive interactions among cryptogams. Therefore, we conducted a long-term gastropod exclusion experiment testing for grazing effects on epiphytic cryptogam communities. We estimated the grazing damage, cover and diversity of cryptogams before gastropods were excluded and three and six years thereafter. Gastropod herbivory pronouncedly affected cryptogams, except for bryophytes, strongly depending on host tree species and duration of gastropod exclusion. On control trees, gastropod grazing regulated the growth of algae and non-lichenized fungi and thereby maintained a high lichen diversity and cover. On European beech, the release from gastropod grazing temporarily increased lichen vitality, cover, and species richness, but later caused rapid succession where algae and fungi overgrew lichens and thereby reduced their cover and diversity compared with the control. On Norway spruce, without gastropods lichen richness decreased and lichen cover increased compared with the control. Our findings highlight the importance of long-term exclusion experiments to disentangle short-term, direct effects from longer-term, indirect effects via changes in competitive relationships between taxa. We further demonstrated that gastropod feeding maintains the diversity of cryptogam communities

Fern and bryophyte endozoochory by slugs

Endozoochory plays a prominent role for the dispersal of seed plants, and dispersal vectors are well known. However, for taxa such as ferns and bryophytes, endozoochory has only been suggested anecdotally but never tested in controlled experiments. We fed fertile leaflets of three ferns and capsules of four bryophyte species to three slug species. We found that, overall, spores germinated from slug feces in 57.3% of all 89 fern and in 51.3% of all 117 bryophyte samples, showing that the spores survived gut passage of slugs. Moreover, the number of samples within which spores successfully germinated did not differ among plant species but varied strongly among slug species. This opens new ecological perspectives suggesting that fern and bryophyte endozoochory by gastropods is a so-far-overlooked mode of dispersal, which might increase local population sizes of these taxa by spore deposition on suitable substrate

Surveying lichen diversity in forests: A comparison of expert mapping and eDNA metabarcoding of bark surfaces

Lichens are an important part of forest ecosystems, contributing to forest biodiversity, the formation of micro-niches and nutrient cycling. Assessing the diversity of lichenised fungi in complex ecosystems, such as forests, requires time and substantial skills in collecting and identifying lichens. The completeness of inventories thus largely depends on the expertise of the collector, time available for the survey and size of the studied area. Molecular methods of surveying biodiversity hold the promise to overcome these challenges. DNA barcoding of individual lichen specimens and bulk collections is already being applied; however, eDNA methods have not yet been evaluated as a tool for lichen surveys. Here, we assess which species of lichenised fungi can be detected in eDNA swabbed from bark surfaces of living trees in central European forests. We compare our findings to an expert floristic survey carried out in the same plots about a decade earlier. In total, we studied 150 plots located in three study regions across Germany. In each plot, we took one composite sample based on six trees, belonging to the species Fagus sylvatica, Picea abies and Pinus sylvestris. The eDNA method yielded 123 species, the floristic survey 87. The total number of species found with both methods was 167, of which 48% were detected only in eDNA, 26% only in the floristic survey and 26% in both methods. The eDNA contained a higher diversity of inconspicuous species. Many prevalent taxa reported in the floristic survey could not be found in the eDNA due to gaps in molecular reference databases. We conclude that, currently, eDNA has merit as a complementary tool to monitor lichen biodiversity at large scales, but cannot be used on its own. We advocate for the further development of specialised and more complete databases

On the trails of Josias Braun-Blanquet II : first results from the 12th EDGG Field Workshop studying the dry grasslands of the inneralpine dry valleys of Switzerland

The 12th EDGG Field Workshop took place from 11 to 19 May 2019, organised by the Vegetation Ecology Group of the Institute of Natural Resource Sciences (IUNR) of the Zurich University of Applied Sciences (ZHAW). Like in the 11th Field Workshop in Austria, the main target was the "Inneralpine Trockenvegetation" (Festuco-Brometea and Sedo-Scleranthetea), which was first extensively sampled by Josias Braun-Blanquet and collaborators during the 1950s. We visited the Rhône valley in the cantons of Vaud and Valais, one of the most ex-treme xerothermic islands of the Alps and the Rhine and Inn valleys in the canton of Grison. In total, 30 nested-plot series (EDGG biodi-versity plots) of 0.0001 to 100 m² and 82 plots of 10 m² were sampled in meso-xeric, xeric and rocky grasslands of 25 different sites, rang-ing from 500 to 1,656 m a.s.l., under different topographic, bedrock and landuse conditions. All vascular plants, bryophytes and lichens were recorded in each plot, along with their cover values. We found on average 28.9 vascular plants on 10 m²; which was the lowest mean species richness of any previous EDGG Field Workshop. These values are comparable to the average species richness values of dry grasslands of the Aosta valley in Italy. The data sampled will be used to understand the biodiversity patterns regionally and in the Palae-arctic context as well as to place the Swiss dry grasslands in the modern European syntaxonomic system

Grasländer des gemäßigten Europas in einer sich verändernden Welt : Vorwort zum 16. EDGG-Sonderteil in Tuexenia

Mitglieder der Eurasian Dry Grassland Group (EDGG) und deren Vorgängerorganisationen geben seit 16 Jahren Grasland-Sonderausgaben (Special Features) in Tuexeniaheraus. Das diesjährige Special Feature mit dem Titel Grasländer des gemäßigten Europas in einer sich verändernden Welt umfasst sieben Artikel, die verschiedene Aspekte der Graslandforschung beleuchten und dabei unterschiedliche Organismengruppen einbeziehen: LLUMIQUINGA et al. untersuchten Langzeiteffekte von Einsaat, Mahd und Kohlenstoffzusatz (Reduktion der Nährstoffverfügbarkeit durch Verschiebung des C/N-Verhältnis) auf den Renaturierungserfolg von pannonischem Sandgrasland auf ehemaligen Äckern. BÓDIS et al. verglichen die kurzfristigen Effekte verschiedener Pflegemaßnahmen (Mahd mit/ohne Abfuhr des Schnittguts sowie Brennen) auf den ökologischen Zustand aufgegebener Pfeifengraswiesen in Westun-garn. BALOGH et al. analysierten Verzehrraten und Ernährungspräferenzen von Rindern in artenreichen Steppenwiesen der ungarischen Tiefebene, um eine nachhaltige Grasland- und Viehwirtschaft zu er-möglichen. HEER et al. untersuchten Dichteeffekte der zwei Hemiparasiten Melampyrum arvense und M. nemorosum auf die Pflanzenartenvielfalt im Grasland der Insel Saaremaa (Estland). KUMMLI et al. führten 25 Jahre nach der Ersterfassung eine Wiedererhebung der Artenzusammensetzung und Diversi-tät und der Vegetation von urbanen Grasländern in Zürich durch. CHARMILLOT et al. (2021) untersuch-ten die Vegetationsveränderungen von Kalkhalbtrockenrasen des Schweizer Juras in den vergangenen 40 Jahren mittels Wiedererhebungen von bekannten Untersuchungsflächen. ROLEČEKet al. (2021) korrigierten den 2019 in Tuexenia veröffentlichten Höchstwert von 106 Arten (ROLEČEKet al. 2019) in einer siebenbürgischen Steppenwiese (Rumänien), der aufgrund einer fehlerhaften Flächenabgren-zung in einer 10,9 m2-Fläche und nicht wie angegeben in einer 10 m2 großen Fläche ermittelt wurde,und meldeten gleichzeitig neue Höchstwerte für den Artenreichtum an Gefäßpflanzen, die jemals in 10 m2-Flächen ermittelt wurden (115 und 110 Arten in zwei benachbarten Flächen)

Traditional land use, management and biodiversity of European semi-natural grasslands : editorial to the 15th EDGG Special Feature

Seit 15 Jahren geben Mitglieder der Eurasian Dry Grassland Group (EDGG) und deren Vorgängerorganisationen Grasland-Sonderausgaben (Special Features) in Tuexenia heraus. Das diesjährige Special Feature mit dem Titel Traditionelle Landnutzung, Management und Biodiversität von halb-natürlichem Grasland in Europa umfasst acht Artikel, die viele Aspekte der Graslandforschung beleuchten und verschiedene Organismengruppen miteinbeziehen: JANIŠOVÁ et al. (2020a) untersuchten den Einfluss verschiedener traditioneller Landnutzungsformen auf den Artenreichtum des extensiven Graslands im Apuseni-Gebirge in Westrumänien. LABADESSA et al. (2020) verglichen die Artenzusammensetzung von beweidetem und unbeweidetem Grasland im Rahmen eines Renaturierungsprojektes in Südostitalien. PÁPAY et al. (2020) untersuchten den Einfluss der Gehölzdeckung auf die Artenzusammensetzung des halbnatürlichen Graslands im Mátra-Gebirge in Nordungarn und inwieweit wilde Huftiere die Verbuschung eindämmen können. DAYNEKO et al. (2020) beschrieben den Einfluss antiker Siedlungen aus skythischer und sarmathianischer Zeit auf die Biodiversität von Steppenhabitaten im Dnipro-Becken in der Südukraine. ZANIEWSKI et al. (2020) untersuchten, ob Störungen durch Geländefahrzeuge die Sukzession von Binnendünen in Zentralpolen aufhalten und dadurch die ehemalige Landnutzung ersetzen können, um die Kryptogamendiversität zu erhalten. JANIŠOVÁ et al. (2020b) charakterisierten Diversitätsmuster von Carex humilis-dominierten Felsen-steppen in vier biogeographischen Regionen des östlichen Mitteleuropas entlang eines Höhengradienten über 1240 m. BÜCHLER et al. (2020) gingen der Frage nach, inwieweit der Naturschutzwert von Mesobromion-Halbtrockenrasen im Kanton Zürich in der Schweiz auf unterschiedliche Standortbedingungen zurückgeführt werden kann. CANCELLIERI et al. (2020) gaben einen Überblick über die Pflanzengesellschaften und die ökologischen Bedingungen der Trockenrasen des Nationalparks Abruzzen, Latium und Molise in Mittelitalien. Insgesamt haben 47 Autoren aus zehn Ländern zur 15. Grasland-Sonderausgabe beigetragen

Restoration, monitoring, conservation and phytosociology of semi-natural and natural grasslands in Central Europe : editorial to the 14th EDGG special feature

Seit 14 Jahren werden von Mitgliedern der Eurasian Dry Grassland Group (EDGG) und deren Vorgängerorganisationen Grasland-Sonderteile (Special Features) in Tuexenia herausgegeben. Das diesjährige Special Feature mit dem Titel Wiederherstellung, Überwachung, Schutz und Soziologie des halbnatürlichen und natürlichen Graslands in Mitteleuropa umfasst sechs Artikel: BOCH et al. untersuchen die Eignung von Quasidauerflächen zum Langzeitmonitoring mittlerer Zeigerwerte sowie Zusammensetzung und Turnover der Arten in Trockenrasen. CHYTRÝ et al. beschreiben die Vegetation der Trockenrasen des Tieflands der Transkarpaten und gleichzeitig drei neue Assoziationen für die Ukraine. ERDŐS et al. zeigen Trends in der Artenzusammensetzung und dem Artenreichtum entlang eines Gradienten vom Zentrum zum Rand in Waldsteppen im südlichen Karpatenbecken. GHEZA et al. beschreiben die Syntaxonomie, Ökologie und den Naturschutzwert der Erdflechtengesellschaften bodensaurer Thero-Airion-Pionierrasen in der Poebene in Italien. Mardari et al. untersuchen die Populationstruktur und Lebensraumeigenschaften von Arnica montana in den Karpaten. ROLEČEK et al. berichten über neue Maxima des kleinräumigen Gefäßpflanzenartenreichtums rumänischer und ukrainischer Halbtrockenrasen. Insgesamt haben 40 Autoren zum 14. Special Feature beigetragen