Spiders (Araneae) from coastal heathland on the isle of Hiddensee (Mecklenburg-Western Pomerania

The present paper provides the first checklist of the spiders from coastal heathland on the Baltic Sea island of Hiddensee, Germany. A total of 171 species could be recovered by pitfall trapping in 2008 and 2009. The species inventory comprises several typical dune and heathland species. Ten species (Altella lucida, Centromerus capucinus, Dictyna latens, Drassodes cupreus, Hypsocephalus pusillus, Hypsosinga sanguinea, Micaria lenzi, Micrargus apertus, Philodromus histrio, Walckenaeria capito) are new to the arachnofauna of Mecklenburg-Western Pomerania

Traditional Water Meadows: A Sustainable Management Type for the Future?

Traditional meadow irrigation techniques were once widespread throughout Europe and served as a method of grassland intensification before the era of mineral fertilization. Close to Landau (Palatinate), Germany, there are several hectares of traditionally irrigated water meadows that are irrigated twice a year in parts since the medieval age or irrigation has been reinitiated since the 1990. In a research project “WasserWiesenWerte”, we analyzed the ecological and socio-economic value of meadow irrigation. We compared extensively to semi-intensively used meadows with fertilizer application between 0 and 80 kg N/ha per year which were either irrigated or nonirrigated. The results were very motivating. Biomass production is increased by about one-third with irrigation. At the same time, several species groups did not decrease in frequency and diversity in the meadows under irrigation. In contrast, some especially rare species seemed to even profit. Ditch structures turned out to be especially important refuges for sensible meadow species and added a large quantity of additional species to the landscape diversity. We propose that the revitalization of traditional irrigation techniques should be considered when extensively managed grassland—especially hay meadows—are prone to either intensification or abandonment

Differing impacts of two major plant invaders on urban plant-dwelling spiders (Araneae) during flowering season

Plant invasions can have major impacts on ecosystems and influence global species diversity. In Central Europe, Himalayan balsam (Impatiens glandulifera) and American goldenrods (Solidago canadensis and S. gigantea) are important invaders often establishing dense and homogeneous stands, especially in urban and other disturbed habitats. We investigated their impacts on plant-dwelling spiders (abundance, family structure, guild structure) and potential spider prey items during flowering season within an urbanized landscape using a paired design comparing invaded and native reference vegetation plots. In general, flowering American goldenrods and Himalayan balsam had no significant impacts on the spider family composition. Invasion of American goldenrods further had no effect on total spider abundance and potential prey item abundance. In contrast, goldenrods showed a significantly increased crab spider (Thomisidae) abundance while being less inhabited by web builders. Himalayan balsam negatively influenced free hunters and running crab spider (Philodromidae) abundance, while we found no effects on other groups and total spider abundance. For Himalayan balsam, potential prey item abundance was higher than in native vegetation stands. Notwithstanding that our results only represent a snapshot of the system, they suggest that large-scale removal of urban goldenrod stands during flowering season might negatively influence local spider abundance, especially of crab spiders. Management efforts should therefore be accompanied by compensation measures to avoid disruptive effects on local plant-dwelling spider communities

Fallopia japonica and Impatiens glandulifera are colonized by species-poor root-associated fungal communities but have minor impacts on soil properties in riparian habitats

Fallopia japonica and Impatiens glandulifera are major plant invaders on a global scale that often become dominant in riparian areas. However, little is known about how these species affect interactions in soil-plant systems. The aim of this study was to investigate the impact of both species on abiotic and biotic soil properties, with a special focus on fungi. We investigated eight sites along small streams invaded by F. japonica and I. glandulifera, respectively, and compared each with nearby sites dominated by the native species Urtica dioica. Three different types of samples were collected: bulk soil, rhizosphere soil and roots from invasive and native stands at each site. Bulk soil samples were analysed for soil physicochemical, microbial properties (soil microbial respiration and ergosterol) and soil arthropod abundance (Acari and Collembola). Soil respiration was also evaluated in rhizosphere samples. The fungal community composition of both bulk soil and roots were analysed using a metabarcoding approach. Soil physicochemical properties as well as soil microbial activity, fungal biomass and soil fungal operational unit taxonomic unit (OTU) richness did not differ between invaded and native riparian habitats, indicating only minor belowground impacts of the two invasive plant species. Soil microbial activity, fungal biomass and soil fungal OTU richness were rather related to the soil physicochemical properties. In contrast, Acari abundance decreased by 68% in the presence of F. japonica, while Collembola abundance increased by 11% in I. glandulifera sites. Moreover, root-associated fungal communities differed between the invasive and native plants. In F. japonica roots, fungal OTU richness of all investigated ecological groups (mycorrhiza, endophytes, parasites, saprobes) were lower compared to U. dioica. However, in I. glandulifera roots only the OTU richness of mycorrhiza and saprobic fungi was lower. Overall, our findings show that F. japonica and I. glandulifera can influence the abundance of soil arthropods and are characterized by lower OTU richness of root-associated fungi

Historical Irrigated Meadows at the River Queich, Rhineland-Palatinate

For centuries the meadows at the river Queich in southern Rhineland-Palatinate were irrigated to enhance the quantity and quality of hay. With the introduction of fertili-zers irrigation was stopped in most areas but partly reactivated within the last few years. Today we find a small-scaled mosaic of (non-) irrigated and (un-) fertilized meadows. The Institute for Environmental Sciences Landau at the University of Koblenz - Landau conducts interdisciplinary research on the meadows to investigate the effects of irrigation and the interactions between the involved terrestrial and aquatic systems

Copper Uptake and Its Effects on Two Riparian Plant Species, the Native Urtica dioica, and the Invasive Fallopia japonica

Copper accumulating in stream sediments can be transported to adjacent riparian habitats by flooding. Although being an essential element for plants, copper is toxic at high concentrations and restricts, among other things, plant growth. Besides copper, invasive plants, such as Fallopia japonica, which are known to be tolerant toward heavy metals, modify riparian habitats. If the tolerance of F. japonica is higher compared to native plants, this could accelerate invasion under high heavy metal stress. Therefore, we aimed to compare the effect of copper on two common riparian plants, the invasive F. japonica and the native Urtica dioica. We performed a pot experiment with a gradient from 0 to 2430 mg kg(-1) of soil copper. We hypothesized that (i) negative effects on plant growth increase with increasing soil copper concentrations with F. japonica being less affected and (ii) accumulating higher amounts of copper in plant tissues compared to U. dioica. In support of our first hypothesis, growth (height, leaf number) and biomass (above- and belowground) of F. japonica were impacted at the 810 mg kg(-1) treatment, while the growth of U. dioica was already impacted at 270 mg kg(-1). Due to 100% mortality of plants, the 2430 mg kg(-1) treatment was omitted from the analysis. In contrast, chlorophyll content slightly increased with increasing copper treatment for both species. While U. dioica accumulated more copper in total, the copper uptake by F. japonica increased more strongly after exposure compared to the control. In the 810 mg kg(-1) treatment, copper concentrations in F. japonica were up to 2238% higher than in the control but only up to 634% higher in U. dioica. Our results indicate that F. japonica might be able to more efficiently detoxify internal copper concentrations controlling heavy metal effects compared to the native species. This could give F. japonica a competitive advantage particularly in polluted areas, facilitating its invasion success

Extracting secondary data from citizen science images reveals host flower preferences of the Mexican grass‐carrying wasp Isodontia mexicana in its native and introduced ranges

We investigated the plant-pollinator interactions of the Mexican grass-carrying wasp Isodontia mexicana—native to North America and introduced in Europe in the 1960s—through the use of secondary data from citizen science observations. We applied a novel data exchange workflow from two global citizen science platforms, iNaturalist and Pl@ntNet. Images from iNaturalist of the wasp were used to query the Pl@ntNet application to identify possible plant species present in the pictures. Simultaneously, botanists manually identified the plants at family, genus and species levels and additionally documented flower color and biotic interactions. The goals were to calibrate Pl@ntNet's accuracy in relation to this workflow, update the list of plant species that I. mexicana visits as well as its flower color preferences in its native and introduced ranges. In addition, we investigated the types and corresponding frequencies of other biotic interactions incidentally captured on the citizen scientists' images. Although the list of known host plants could be expanded, identifying the flora from images that predominantly show an insect proved difficult for both experts and the Pl@ntNet app. The workflow performs with a 75% probability of correct identification of the plant at the species level from a score of 0.8, and with over 90% chance of correct family and genus identification from a score of 0.5. Although the number of images above these scores may be limited due to the flower parts present on the pictures, our approach can help to get an overview into species interactions and generate more specific research questions. It could be used as a triaging method to select images for further investigation. Additionally, the manual analysis of the images has shown that the information they contain offers great potential for learning more about the ecology of an introduced species in its new range

Arthropods in a changing environment - A multi-level and -species approach to diversity and ecology in coastal heathlands

Main drivers for biodiversity loss in terrestrial ecosystems are changes in land use, climate change, enhanced nitrogen deposition and biotic exchange (invasive species). These drivers also affect dry, nutrient-poor open anthropo-zoogenic inland and coastal heathlands which often harbor a high biodiversity. To counteract biodiversity loss in coastal ecosystems, a basic step is the assessment of the various threats. Therefore it is important to select suitable model organisms for analyses of biodiversity dynamics. In this thesis the three arthropod groups Orthoptera (Ensifera and Caelifera), carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) were studied, as they are very useful indicators. Besides sampling of the three arthropod groups vegetation and microclimate parameters were recorded. The studies were done between 2008 and 2010 in the coastal heathland on the Baltic island of Hiddensee, Germany. The main aim of the thesis was to analyze the impact of three drivers of heathland biodiversity loss (succession, grass encroachment, moss invasion) on the selected indicator arthropod groups. Based on this multi-level and -species approach, implications for the conservation of coastal heathlands are given. The results show that successional processes and grass encroachment have strong impact on species richness and abundance, species composition and functional groups, as well as life-history traits and functional diversity of the arthropod groups. Main findings were: Orthoptera species richness was highest in the intermediate stages (heath encroached by grasses and heath with shrubs) because of higher habitat heterogeneity and higher food supply (grasses). Opposed to that, species richness of ground-dwelling carabid beetles and spiders did not differ among the five successional stages, which contradicts the ‘habitat heterogeneity hypothesis’. In contrast to species richness, functional diversity differed among successional stages. The concept of functional diversity – which integrates species life-history trait data – therefore might be particularly suitable for biodiversity research, while the explanatory power of species richness alone might not be sufficient. The species compositions of all three taxa changed remarkably along the coastal heathland gradient indicating a high species turnover. In particular, open, dynamic habitats (‘grey dunes’ and ‘dwarf-shrub heath’) could be separated. Here, several specialized, xerothermic and threatened species occurred due to the extreme habitat conditions, but are displaced during grass and shrub encroachment. On a smaller spatial scale, the invasion of Campylopus introflexus alters habitat conditions in grey dunes and therefore affects carabid beetle and spider species and the dominant Orthoptera species Myrmeleotettix maculatus. Species richness of carabid beetles and spiders, and the abundance of adult M. maculatus grasshoppers were reduced. Species compositions of carabids and spiders changed remarkably with a loss of several species. These negative impacts could be explained by the vegetation structure of the moss which is unsuitable for web-building spiders or large carabid beetles, and by reduced germination of higher plants and therefore reduced food supply for M. maculatus and phytophagous carabid species. Within the open coastal heathland, the mosaic of grey dunes and adjacent dwarf-shrubs is important since many species perform a habitat change during their development and, besides the scarcely vegetated, thermally benefited grey dunes, need denser vegetation of adjacent dwarf-shrubs for shelter, as song posts, or for foraging. As grey dunes harbor a high abundance and species richness of threatened and specialized, mainly xerothermic and geobiont species and are important as oviposition and nymphal habitat, they are regarded as a keystone habitat within the coastal heathland. Besides these ecological studies, two studies focused on the method of pitfall trapping. It could have been shown, that pitfall trapping might be a useful sampling method for Orthoptera in open habitats. The other study demonstrated that sampling interval has a strong influence on the capture efficiency of several arthropod groups (‘digging-in effect’). Conservation practices should aim at maintaining a heterogeneous heathland mosaic with open grey dunes and Calluna stands, in addition to scattered grassy and shrub-encroached heath for the survival of species-rich heathland arthropod assemblages with a high proportion of specialized and threatened species.Hauptursachen für den Verlust von Biodiversität in terrestrischen Ökosystemen sind Landnutzungsänderungen, Klimawandel, erhöhte Stickstoffdepositionen und biotischer Austausch (invasive Arten). Auch für trockene nährstoffarme anthropo-zoogen beeinflusste Küstenheiden stellen diese Faktoren eine Gefährdung dar. Eine Grundvoraussetzung, dem Verlust von Biodiversität in Küstenlebensräumen begegnen zu können, ist die Analyse und Bewertung der Gefährdungsursachen. Um Aussagen zur Biodiversitätsdynamik treffen zu können, ist die Auswahl geeigneter Modellorganismen wichtig, In der vorliegenden Dissertation wurden die drei Arthropodengruppen Heuschrecken (Orthoptera: Ensifera und Caelifera), Laufkäfer (Coleoptera: Carabidae) und Spinnen (Araneae) untersucht, die geeignete Indikatoren für die Erfassung von Biodiversitätsdynamik darstellen. Neben der Erfassung der Arthropoden wurden Parameter zur Vegetation und zum Mikroklima aufgenommen. Die Untersuchungen wurden zwischen 2008 und 2010 in der Küstenheide auf der deutschen Ostseeinsel Hiddensee durchgeführt. Hauptziel der Arbeit war es, die Auswirkungen der drei biodiversitätsgefährdenden Faktoren Sukzession, Vergrasung, und Moosinvasion auf die ausgewählten Indikatorgruppen zu analysieren. Basierend auf diesem mehrdimensionalen Ansatz – mit der Betrachtung verschiedener räumlicher Ebenen und verschiedener Arten bzw. Taxa – werden Empfehlungen für Schutz- und Pflegemaßnahmen in Küstenheiden gegeben. Die Ergebnisse zeigen, dass Sukzessionprozesse und Vergrasung einen starken Einfluss auf Artenreichtum und Abundanzen, Artenzusammensetzung und funktionelle Gruppen sowie Anpassungen der Lebensweise (‚life-history traits’) und funktionelle Diversität auf die untersuchten Gruppen haben. Die Hauptaussagen sind: Der Artenreichtum von Heuschrecken ist am höchsten in den mittleren Sukzessionsstadien (vergraste Heide und verbuschte Heide). Ursachen dafür sind die höhere Habitat-Heterogenität und die höhere Verfügbarkeit an Nahrung (Gräser). Im Gegensatz dazu konnten bei Laufkäfer und Spinnen im Widerspruch zur ‚Habitat-Heterogenitäts-Hypothese’ keine Unterschiede im Artenreichtum zwischen den fünf Sukzessionsstadien festgestellt werden. Demgegenüber unterschied sich die funktionelle Diversität beider Gruppen zwischen den Stadien. Das Konzept der funktionellen Diversität könnte somit einen wichtigen Beitrag für die Biodiversitätsforschung leisten, da die Erklärungskraft von Artenreichtum allein nur begrenzt ist. Die Artenzusammensetzungen aller drei Taxa wechselten beträchtlich entlang des Sukzessionsgradienten. Besonders die Artenzusammensetzungen von offenen, dynamischen Habitaten (Graudüne und Zwergstrauchheide) ließen sich deutlich abgrenzen. Auf Grund der extremen Umweltbedingungen kommen zahlreiche spezialisierte und gefährdete Arten in diesen Habitaten vor, die bei einer Vergrasung oder Verbuschung verschwinden. Auf einer kleineren räumlichen Ebene verändert die Invasion des Mooses C. introflexus die Habitatbedingungen in Graudünen und beeinflusst so Laufkäfer und Spinnen sowie die dominierende Heuschreckenart Myrmeleotettix maculatus. Die Artenzusammensetzungen von Laufkäfern und Spinnen veränderten sich deutlich und einige Arten wurden verdrängt, der Artenreichtum dieser Gruppen nahm ab. Auch die Abundanzen von adulten M. maculatus waren geringer als in natürlichen Graudünen. Zu erklären ist dies damit, dass die Vegetationsstruktur des Mooses für netzbauende Spinnen oder große Laufkäfer ungünstig ist und dass eine reduzierte Keimung höherer Pflanzenarten zu einem verringerten Nahrungsangebot für M. maculatus und phytophage Laufkäfer führt. Innerhalb der offenen Küstenheide hat das Mosaik aus Graudünen und angrenzenden Zwergstrauchbeständen eine hohe Bedeutung, da viele Arten während ihrer Entwicklung einen Habitatwechsel vornehmen und neben den schütter bewachsenen und thermisch begünstigten Graudünen die dichtere Vegetation der Zwergsträucher zum Schutz, als Singwarten oder zur Nahrungssuche benötigen. Da Graudünen sich durch einen hohen Arten- und Individuenreichtum von spezialisierten und gefährdeten, vornehmlich xerothermen und geobionten Arten auszeichnen und eine hohe Bedeutung als Eiablage- und Larvalhabitat haben, werden sie als Schlüssellebensraum innerhalb der Küstenheide angesehen. Neben diesen ökologischen Studien wurden zwei methodische Untersuchungen durchgeführt, in denen neue Erkenntnisse zur Fangeffektivität von Bodenfallen präsentiert werden. So konnte gezeigt werden, dass Bodenfallenfänge eine geeignete Erfassungsmethode für Heuschrecken sein können. Die Ergebnisse der zweiten Studie zeigen einen starken Einfluss des Leerungsintervalls auf die Fangeffektivität (‚diggin-in effect’). Für den Erhalt artenreicher Arthropodengemeinschaften mit einem hohen Anteil an spezialisierten und gefährdeten Arten sollten Pflegemaßnahmen ein heterogenes Mosaik aus Graudünen und Zwergsträuchern mit vereinzelten vergrasten und verbuschten Heidebeständen fördern

COVID-19 Pandemic Turns Life-Science Students into “Citizen Scientists”: Data Indicate Multiple Negative Effects of Urbanization on Biota

The COVID-19 pandemic and its restrictions strongly affect the higher education community and require diverse teaching strategies. We designed a course where we combined online teaching with independently conducted ecological data collections by students using a “citizen science” approach. The aim was to analyze the impact of urbanization on biota by comparing urban and rural grasslands. Seventy-five students successfully conducted the data collections and the results provide evidence for prevailing negative effects of urbanization. Individual numbers of ground-dwelling invertebrates (−25%) and pollinating insects (−33%) were generally lower in urban sites. Moreover, animal and seed predation were reduced in urban grasslands, indicating the potential of urbanization to alter ecosystem functions. Despite the general limitations of online teaching and citizen science approaches, outcomes of this course showed this combination can be a useful teaching strategy, which is why this approach could be used to more actively involve students in scientific research

Spinnen (Araneae) in K\ufcstend\ufcnenheiden der Insel Hiddensee (Mecklenburg-Vorpommern)

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