The habitat choice of the small hindgut fermenter, the European rabbit (Oryctolagus cuniculus L.), was studied in relation to sward height, forage quality, population size fluctuations and spatial distribution of burrows in a temperate grassland. In a multi-phase differential clipping experiment with alternating short and tall vegetation strips, rabbits tended to graze near the closest burrows in situations of equal vegetation heights, while a clear preference for short swards was found during summer (July). In this period, general crude protein content was significantly lower than in spring (April) and autumn (September), apparently leading to a potential forage quality deficit. The summer behavioural pattern with short sward preference coincided with the relatively higher crude protein content of short swards as compared to tall swards in this period, and with higher intraspecific competition, due to significantly larger numbers of animals present in summer. In autumn, rabbit densities decreased, while crude protein content of both short and tall vegetation increased to a higher, though not significantly different level, comparable with spring crude protein content. In those conditions, significant preference for low vegetation height could no longer be detected. Data suggest that selection for nutritive quality appears when intraspecific competition is high and nutritive quality remains under a certain threshold value. When, in autumn, competition decreases and nutritive quality increases again, short sward preference disappears. We conclude that short sward preference is primarily caused by the better forage quality of re-growth in periods of forage quality limitation, while this preference disappears when forage quality limitation no longer occurs.
We aimed to assess the distribution and trends in abundance and rooting elevation in relation to substrate type (soft sediment/riprap) for three Schoenoplectus club-rush species in the Zeeschelde estuary (Belgium). Surveys took place in 1995, 2003 and 2013, following dike fortifications for the SIGMA flood control plan. Compared to 1995 club-rush tufts are now positioned lower in the tidal frame, especially their upper margin. Club-rush cover decreased by 50% in the last time interval. This is linked to marsh succession after a vegetation set-back by SIGMA works and increasing competition with Phragmites and Salix . The lower margin of club-rushes shifted downwards on riprap, but not on soft sediment. This substrate-dependent rooting elevation reach likely indicates that substrate stability can be an important factor for club-rush persistence and growth on the lower marsh margin. This emerged only recently probably because tufts needed time to expand after the SIGMA works and because of the improved water quality. Currently, Schoenoplectus club-rushes on soft sediment in the Zeeschelde suffer from the lack of suitable areas with cyclic natural morphodynamics that maintain pioneer habitat. To maintain club-rush diversity we suggest to manage threatened club-rush populations or to translocate them to newly created restoration sites.
Dung removal by macrofauna such as dung beetles is an important process for nutrient cycling in pasturelands. Intensification of farming practices generally reduces species and functional diversity of terrestrial invertebrates, which may negatively affect ecosystem services. Here, we investigate the effects of cattle-grazing intensification on dung removal by dung beetles in field experiments replicated in 38 pastures around the world. Within each study site, we measured dung removal in pastures managed with low- and high-intensity regimes to assess between-regime differences in dung beetle diversity and dung removal, whilst also considering climate and regional variations. The impacts of intensification were heterogeneous, either diminishing or increasing dung beetle species richness, functional diversity, and dung removal rates. The effects of beetle diversity on dung removal were more variable across sites than within sites. Dung removal increased with species richness across sites, while functional diversity consistently enhanced dung removal within sites, independently of cattle grazing intensity or climate. Our findings indicate that, despite intensified cattle stocking rates, ecosystem services related to decomposition and nutrient cycling can be maintained when a functionally diverse dung beetle community inhabits the human-modified landscape.
© Springer Medizin Verlag GmbH, ein Teil von Springer Nature 2021 I. Werner · A. Meyer-Gelbhaar · M. Esmail · J. Röther · M. Hoffmann · J. Schaumberg 1 Neurologie, Städtisches Klinikum Braunschweig, Braunschweig, Deutschland Neurologie mit Neurologischer Frührehabilitation,Helios KlinikumUelzen, Uelzen, Deutschland MVZ-DiagnostikzentrumMarburg, Marburg, Deutschland Neurologie, Asklepios Klinik Altona, Hamburg, Deutschland Neurologie, Sana Kliniken Lübeck, Lübeck, Deutschland
Authors: Tanja Milotić, Christophe Baltzinger, Carsten Eichberg, Amy E. Eycott, Marco Heurich, Jörg Müller, Jorge A. Noriega, Rosa Menendez, Jutta Stadler, Réka Ádám, Tessa Bargmann, Isabelle Bilger, Jörn Buse, Joaquin Calatayud, Constantin Ciubuc, Gergely Boros, Pierre Jay-Robert, Märt Kruus, Enno Merivee, Geoffrey Miessen, Anne Must, Elham Ardali, Elena Preda, Iraj Rahimi, Dirk Rohwedder, Rob Rose, Eleanor M. Slade, László Somay, Pejman Tahmasebi, Stefano Ziani and Maurice Hoffmann
By manipulating faeces during feeding and breeding, dung beetles (Coleoptera: Scarabaeidae) fulfil important ecosystem functions in terrestrial ecosystems throughout the world. In a pan-European multi-site experiment (MSE), we estimated the ecosystem functions of dung removal and secondary seed dispersal by differing combinations of dung beetle functional groups. Therefore, we classified dung beetles into five functional groups according to their body size and dung manipulation method: dwellers, large and small tunnelers, and large and small rollers. Furthermore, we set up a dung beetle sampling database containing all sampled dung beetles during the project. By identifying dung beetle specimens to the species level, we obtained a detailed insight into the dung beetle communities at each study location. By establishing experimental plots allowing and inhibiting specific combinations of functional groups in the local dung beetle assemblage from removing dung and seeds, we estimated the role of each group in dung removal and secondary seed dispersal during a 4-week period. We performed all experiments in grazed (semi-) natural grasslands, and used different dung types (cattle, horse, sheep, goat or red deer) to match the herbivore species grazing in close vicinity of each of the study areas. Simultaneously, we sampled dung beetle assemblages by using pitfalls baited with the same dung types as used in the experiments. This data paper documents two datasets collected in the framework of this MSE project. All the experiments took place between 2013 and 2016 at 17 study sites in 10 countries and 11 biogeographic zones. The entire dung beetle sampling dataset was published as a sampling event dataset at GBIF. The dataset includes the sampling results of all 17 study sites, which contain 1,050 sampling events and 4,362 occurrence records of 94 species. The second dataset contains the results of the dung removal and secondary seed dispersal experiments in which we used 11 experimental treatments and the five dung types mentioned above. This experimental results dataset holds all experimental results of the MSE project (11,537 records), and was published in the online data repository Zenodo.
Aim In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal. Location Seventeen grassland locations across the Western Palaearctic. Methods We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro-invertebrates. By sampling the dung beetle community and measuring the remaining dung and seeds after the experiment, the impact of each functional group was estimated. Results Dung beetle assemblages differed along a north-south and east-west gradient. Dwellers dominated northernmost sites, whereas at lower latitudes we observed more tunnellers and rollers indicating a functional shift. Resource specialists were more abundant in southern and eastern areas. Overall, functional group diversity enhanced dung removal. More dung (+46.9%) and seeds (+32.1%) were removed in the southern sites and tunnellers and rollers were more effective. At the northernmost sites, where tunnellers were scarce or absent, other soil macro-invertebrates removed the majority of dung. Main conclusions The conservation of functionally complete dung beetle assemblages is crucial to maintain the ecosystem functions provided by dung beetles. Given the latitudinal variation in functional group diversity, it is reasonable to expect compositional changes due to climate change. These changes could lead to increased dung removal and a higher secondary seed dispersal rate in northern regions.
Dung beetles form an insect group that fulfils important functions in terrestrial ecosystems throughout the world. These include nutrient cycling through dung removal, soil bioturbation, plant growth, secondary seed dispersal and parasite control. We conducted field experiments at two sites in the northern hemisphere temperate region in which dung removal and secondary seed dispersal were assessed. Dung beetles were classified in three functional groups, depending on their size and dung manipulation method: dwellers, large and small tunnelers. Other soil inhabiting fauna were included as a fourth functional group. Dung removal and seed dispersal by each individual functional group and combinations thereof were estimated in exclusion experiments using different dung types. Dwellers were the most diverse and abundant group, but tunnelers were dominant in terms of biomass. All dung beetle functional groups had a clear preference for fresh dung. The ecosystem services in dung removal and secondary seed dispersal provided by dung beetles were significant and differed between functional groups. Although in absolute numbers more dwellers were found, large tunnelers were disproportionally important for dung burial and seed removal. In the absence of dung beetles, other soil inhabiting fauna, such as earthworms, partly took over the dung decomposing role of dung beetles while most dung was processed when all native functional groups were present. Our results, therefore, emphasize the need to conserve functionally complete dung ecosystems to maintain full ecosystem functioning.
Questions: In temperate grasslands, seeds of numerous dry-fruited plant species are dispersed via ingestion and subsequent defecation by grazing animals. Depending on the herbivore species and season, dung pats may contain a large assemblage of conspecific or heterospecific seeds competing for space, light and nutrients in the space-limited environment of an individual dung pat. In an environment rich in nutrients, such as herbivore dung, the outcome of inter- and intraspecific competition might differ from situations where nutrients are limiting. Additionally, dung pats being small and spatially isolated habitats with very specific conditions may also impact competitive interactions. Besides the plant-soil interactions on competition known from literature, the specific quality and structure of dung pats might provoke more complex interactions between different seed densities and species combinations.Methods: We conducted a greenhouse competition experiment using three common perennial grassland species. Agrostis stolonifera, Trifolium pratense and Trifolium repens were used in two-species combinations with different proportions of each species and in monocultures. Seeds were sown in three seed densities (50, 150 and 250 seeds) and the effects of cattle and horse dung on establishment, growth and flowering were tested.Results: Interactions, most probably attributable to interspecific competition, differed between species mixtures. Seeds sown in polycultures generally emerged sooner, but the resulting seedlings had lower relative growth rates compared with seeds sown in monocultures. Increased biomass was measured for each species when growing in polycultures while evidence for intraspecific competition was found in monocultures. T.pratense developed relatively more flowers when plants were growing in polycultures compared with monocultures. Few effects of seed densities were found, although higher seed densities led to lower establishment success in both monocultures and polycultures. Adding dung generally increased the time needed to emerge, relative growth rates and flowering, but decreased establishment success in monocultures.Conclusions: Both seed density and the presence of dung shape the post-dispersal fate of seeds. While high seed densities imply a cost due to lower germinability, the nutritive environment of dung acts as compensation, resulting in faster growth and an increased investment in reproductive tissues.
Extensive grazing often has a strong influence on the structure and composition of herbaceous plant communities with increasing population sizes for some species and decreasing presence in others. Herbivores affect plant communities directly by selective grazing of plant species, and indirectly by either epizoochory or endozoochory. Helianthemum nummularium is considered an increasing species because its distribution increased after the introduction of large, free-ranging grazers in at least two coastal dune grassland areas in Belgium. However, its seeds lack any obvious adaptations for epizoochory, and direct observations of plant/seed consumption are scarce. Through field and lab experiments, we assessed the dispersal ability of H. nummularium via endozoochory and epizoochory. In a differentiated grazer exclusion experiment, evidence was found that plants are grazed by large domestic ungulates and small wild herbivores although these incidences were rare. Direct endozoochory evidence remained scarce. No seeds were found germinating in field-collected dung, and only few seedlings emerged following a seed feeding experiment. However, once deposited, we found higher growth rates when seeds were mixed with dung and decreased establishment success when seeds were sown in combination with competitively superior species. Epizoochory was plausible because both fur and hooves of cattle and horses were potentially capable of contributing to the transport of H. nummularium seeds. We conclude that herbivores play a role in seed dispersal, while their selective grazing behaviour most probably creates an appropriate environment for Helianthemum establishment and maintenance.
There is growing evidence that species are able to coexist in communities through niche separation, and that consistent community structuring can take place at the biogeographical scale, as the same biotic interactions can determine species’ fate at large scales. In this study, we document niche differentiation at a larger scale within a specific plant community of softwater lakes in Western Europe. Five species were selected for their relative frequency and wide geographical distribution within the dataset that we collected. Their niches were modelled both from presence–absence data and from ordinal abundance data, using mixed regression techniques (generalized linear mixed models and proportional odds mixed models, respectively). The modelled realized niches differed among the species on the West-European scale, although strict separation was not shown and geographical coverage is not complete. Plant strategy characterization of the species supported the assumption that functional traits underpin the niche differentiation among the species through fitness trade-offs. Mechanistic experimental research at a range of spatial scales is needed to test the importance of different community structuring mechanisms at the biogeographical scale, such as biotic interactions and environmental filtering.
Ecological sustainability has been recognized as one of the main aspects of sustainable development of rangelands, at which different kinds of animal including insects, make substantial contributions. Dung beetles, known as dung-visiting insects, play several key roles in many ecological functions from which benefit both terrestrial ecosystems and human population. Specifically, they benefit rangelands through reducing greenhouse gas emission, nutrient cycling, plant growth enhancement, trophic regulation and pollination and secondary seed dispersal. This study examined secondary seed dispersal as one of the ecological functions of dung beetles, in Chaharmahal and Bakhtiari province, Iran. We applied an experimental approach to measure ecological function (i.e. seed removal) by functional groups of dung beetles. We tested whether functional dung beetle groups influence secondary seed dispersal differently. Through repeated standardized samples of sheep dung, data obtained regularly during two different months August and November in 2013. The results show that dung beetles play a role in secondary seed dispersal. However, it is affected by seed size, so that seed removal increased in the order of, large, medium and small size, respectively. The significant differences between treatments were found for small seeds in the both months. More seeds were dispersed from treatment t02 (all combinations of functional groups except large rollers) in August, while in November more seeds from treatments t01 (dwellers plus large and small tunnelers plus large and small rollers) and t03 (the combinations of dwellers plus small tunnelers, and small rollers) were removed. As a conclusion, it is suggested that if it is to guarantee the ecological sustainability of rangelands, paying attention to the ecological functions of dung beetles is crucial.
Endozoochory of temperate grassland species is a widespread phenomenon and may accelerate and/or increase germination in some plant species. However, the mechanisms causing this altered germination success are only partly understood. In this study, germination of common grassland species was evaluated after simulated herbivore digestion in a standardized lab environment. Ruminants (cattle) and hindgut fermenters (horses) were used as model organisms in this simulation experiment. Three major digestive processes were studied through mechanical, thermal and chemical treatments of the seeds simulating mastication, body temperature and digestive fluids, respectively. Congeneric groups of annuals and perennials were tested with 15 species belonging to the plant families Cistaceae, Cyperaceae, Fabaceae, Poaceae and Urticaceae. No differences between the impact of the simulated herbivore gut environments of cattle and horses could be found, but major differences in germination behaviour were found among plant species. For most of the tested plant species, treatments had a decelerating and inhibiting effect on germination compared to the untreated seeds. However, species of the Cistaceae and Fabaceae benefitted from mechanical treatments. Species of the Cyperaceae and Poaceae were hardly impaired by any of the treatments and even germinated better after chemical treatments. Thermal treatments, simulating the body temperature, prohibited germination in most cases. The germination success of Urtica [veils was signiticafal y higher after all treatments, which suggests seeds are specifically well adapted to gut passage, and hence to endozoochorous dispersal.
Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining plant populations of its constituents and enabling plants to colonize new habitats. Successful endozoochorous dispersal implies that seeds not only get consumed and survive the digestive tract but are also able to develop into viable seedlings in a dung environment.We experimentally assessed the germination probability and timing of 15 annual and perennial temperate European grassland species in cattle and horse dung and in different climatic conditions (greenhouse and outdoor conditions).Interspecific variation in germinability and germination timing are found, while life strategy had only an effect on germination timing. We found adverse effects of both cattle and horse dung on the germination characteristics of all tested grassland species, but the effects of cattle dung were more pronounced. In comparison with the control treatment, fewer seeds emerged in dung and more time was needed to germinate. Also, germination metrics clearly differed between the artificial greenhouse and outdoor conditions, with generally a lower germinability in outdoor conditions.According to our results, a large cost seems to be associated with endozoochorous dispersal in this stage of the life cycle, as seed dispersal effectiveness strongly depends on the quality of the deposition site with a lowered survival and germination probability when seeds are deposited in dung.
Endozoochory is a potential dispersal mode for numerous plant species. Although germination following endozoochory is well-documented, less is known about the costs and benefits associated with this dispersal mode in later life stages of established plants. The chemical and physical nature of dung differs between herbivores and might have specific effects on seedling establishment, growth and flowering. We conducted a growth experiment using 12 temperate grassland species with a known potential for endozoochory. We studied the effects of cattle and horse dung on the juvenile, growth and reproductive phase. Being a ruminant and a hindgut fermenter, respectively, cattle and horses are two physiologically contrasting herbivore species, producing structurally quite different dung types. They are additionally interesting model species as both are frequently introduced in temperate Europe grassland management. Seedling biomass and growth rate, height, ramification, flowering and biomass of grown plants were measured in an attempt to quantify the benefits of endozoochorously dispersed seeds compared to seeds dispersed by other means and thus growing in a virtually dung-free environment. Few species were affected by the presence of dung in the juvenile phase while most species generally benefitted from being deposited in dung in later life stages. Positive responses of Agrostis capillaris, Agrostis stolonifera, Alopecurus myosuroides, Helianthemum nummularium, Poa annua, Trifolium repens and Trifolium pratense were found, while dung had a negative effect on Juncus bufonius. The initial losses of viable seeds through the digestive system of herbivores might, therefore, be partially compensated by enhanced growth and flowering in some species.
The overall goal of the Habitats Directive is to maintain or restore natural habitats and species in a favourable conservation status. An important role in the implementation process is assigned to science. For three core elements, defining the favourable conservation status, development of best practice measures, and monitoring of the conservation status, we outline how science can support decision making. To do so, we use experiences from the ongoing process in Flanders (northern Belgium). First, when determining the favourable conservation status, information on reference values are embedded in a specifically developed calibration model where thresholds on range, area, and quality are set for habitats. Subsequently, socio-economical requirements are taken into consideration, without compromising the favourable conservation status. When it comes to conducting measures, science adds to the knowledge on developing and optimizing cost-effective conservation and restoration management measures. Finally, monitoring of the conservation status will be based on the principle of statistically sound methodologies, enabling the identification of reliability in the assessments made. For habitats, information on area will be gathered through a surface-covering mapping, while quality will be assessed via a sample-oriented monitoring scheme. For species, maximal collaboration with non-governmental organisations will be undertaken, with scientific support on data recording and processing. Overall, the obtained insights will help policy makers to define the framework and set priorities, take the appropriate measures, and keep a finger on the pulse through monitoring data.
Species-rich grassland communities are one of the most important habitats for biodiversity and of high conservation priority in Europe. Restoration actions are mainly focused on the improvement of abiotic conditions, such as nutrient depletion techniques, and are generally based on the assumption that the target community will re-establish at the restored site when the target species exist in the neighborhood. Information on the contemporary seed-dispersal range is therefore crucial to develop effective conservation measures. Here, we investigated the contemporary long-distance seed dispersal and genetic structure of the grassland herb Thymus pulegioides in an intensively managed agricultural landscape in Flanders (Northern Belgium). Assignment tests based on amplified fragment length polymorphisms revealed very low levels of effective seed dispersal between populations although seed availability and seed viability was not a limiting factor. The process of fragmentation has resulted in a high population differentiation and without further incoming gene flow the remnant populations are prone to further genetic erosion and perhaps extinction. Our findings illustrate that restoring suitable abiotic habitat conditions in the neighborhood of existing populations does likely not guarantee colonization for this grassland specialist. For the survival of the species, existing populations should be functionally connected and seed addition may be necessary for successful conservation to overcome dispersal-limitation.
For successful operation of X-ray Free Electron Lasers, one crucial parameter is the ultrashort electron bunch length yielding a high peak current and a short saturation length. In order to effectively compress the bunches during the acceleration process, a detailed understanding of the full longitudinal phase space distribution already in the injector is required. Transverse deflecting RF structures (TDS) can shear the bunch transversely, mapping the longitudinal coordinate to a transverse axis on an observation screen downstream. In addition to the bunch length, the slice emittance along the bunch as well as the full longitudinal phase space can be obtained. At the Photo Injector Test Facility at DESY, Zeuthen site (PITZ), an S-band traveling wave TDS is under commissioning since 2015. This cavity is a prototype for the TDS in the injector part of the European XFEL and has been designed and manufactured by the Institute for Nuclear Research (INR RAS, Moscow, Russia). In this paper, first commissioning results of the system at PITZ are presented and discussed.
Plant communities are often dispersal‐limited and zoochory can be an efficient mechanism for plants to colonize new patches of potentially suitable habitat. We predicted that seed dispersal by ungulates acts as an ecological filter – which differentially affects individuals according to their characteristics and shapes species assemblages – and that the filter varies according to the dispersal mechanism (endozoochory, fur‐epizoochory and hoof‐epizoochory). We conducted two‐step individual participant data meta‐analyses of 52 studies on plant dispersal by ungulates in fragmented landscapes, comparing eight plant traits and two habitat indicators between dispersed and non‐dispersed plants. We found that ungulates dispersed at least 44% of the available plant species. Moreover, some plant traits and habitat indicators increased the likelihood for plant of being dispersed. Persistent or nitrophilous plant species from open habitats or bearing dry or elongated diaspores were more likely to be dispersed by ungulates, whatever the dispersal mechanism. In addition, endozoochory was more likely for diaspores bearing elongated appendages whereas epizoochory was more likely for diaspores released relatively high in vegetation. Hoof‐epizoochory was more likely for light diaspores without hooked appendages. Fur‐epizoochory was more likely for diaspores with appendages, particularly elongated or hooked ones. We thus observed a gradient of filtering effect among the three dispersal mechanisms. Endozoochory had an effect of rather weak intensity (impacting six plant characteristics with variations between ungulate‐dispersed and non‐dispersed plant species mostly below 25%), whereas hoof‐epizoochory had a stronger effect (eight characteristics included five ones with above 75% variation), and fur‐epizoochory an even stronger one (nine characteristics included six ones with above 75% variation). Our results demonstrate that seed dispersal by ungulates is an ecological filter whose intensity varies according to the dispersal mechanism considered. Ungulates can thus play a key role in plant community dynamics and have implications for plant spatial distribution patterns at multiple scales.SynthesisPlant communities are often dispersal‐limited and zoochory can be an efficient mechanism for plants to colonize new patches of potentially suitable habitat. Our analysis is the first synthesis of ungulate seed dispersal that compares characteristics from both non‐dispersed and dispersed diaspores, distinguishing the three zoochory mechanisms ungulates are involved in: endozoochory, hoof‐epizoochory and fur‐epizoochory. We confirmed that seed dispersal by ungulates is an ecological filter whose intensity increases from endozoochory, then hoof‐epizoochory to finally fur‐epizoochory. By filtering seed traits through dispersal, ungulates can thus play a key role in plant community dynamics and have implications for plant spatial distribution patterns at multiple scales.