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Macrocyclic lactone anthelmintics are widely used to control invertebrate pests in livestock, such as sheep. While anthelmintic effects on non‐target animals, such as dung‐dwelling insects, are well studied, effects on seed germination are largely unknown. Seeds can come into contact with anthelmintics either during passage through the gastro‐intestinal tract of grazing animals or when anthelmintics are excreted with their dung into the environment, which may result in changed germination patterns.We used four commonly applied macrocyclic lactones to assess their effects on germination: moxidectin, ivermectin, abamectin and doramectin as pure substances; moxidectin and ivermectin also in formulated form. We tested these pharmaceuticals on 17 different temperate grassland species from five plant families. Seeds were exposed to three concentrations of macrocyclic lactones (0.1, 1.0 and 10.0 mg·l−1) under controlled conditions, and germination was assessed over a 6‐week period. From these data, we calculated germination percentage, mean germination time and germination synchrony.Most of the tested species were significantly affected in germination percentage and/or mean germination time by at least one of the tested pharmaceuticals, with formulated moxidectin having the largest impact. In general, the effects found were species‐ and pharmaceutical‐specific. While formulated substances generally reduced germination percentage and increased mean germination time, pure substances increased germination percentage. Synchrony showed less clear patterns in all pharmaceuticals.Although effect size and sign varied between species, our study shows that non‐target effects of macrocyclic lactones commonly occur in terrestrial plants. This may impede successful seed exchange between habitats via sheep, and even translate into profound changes to grazed ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: The performance of seedlings is crucial for the survival and persistence of plant populations. Although drought frequently occurs in floodplains and can cause seedling mortality, studies on the effects of drought on seedlings of floodplain grasslands are scarce. We tested the hypotheses that drought reduces aboveground biomass, total biomass, plant height, number of leaves, leaf area and specific leaf area (SLA), and increases root biomass and root‐mass fraction (RMF) and that seedlings from species of wet floodplain grasslands are more affected by drought than species of dry grasslands. In a greenhouse study, we exposed seedlings of three confamilial pairs of species (Pimpinella saxifraga, Selinum carvifolia, Veronica teucrium, Veronica maritima, Sanguisorba minor, Sanguisorba officinalis) to increasing drought treatments. Within each plant family, one species is characteristic of wet and one of dry floodplain grasslands, confamilial in order to avoid phylogenetic bias of the results. In accordance with our hypotheses, drought conditions reduced aboveground biomass, total biomass, plant height, number of leaves and leaf area. Contrary to our hypotheses, drought conditions increased SLA and decreased root biomass and RMF of seedlings. Beyond the effects of the families, the results were species‐specific (V. maritima being the most sensitive species) and habitat‐specific. Species indicative of wet floodplain grasslands appear to be more sensitive to drought than species indicative of dry grasslands. Because of species‐ and habitat‐specific responses to reduced water availability, future drought periods due to climate change may severely affect some species from dry and wet habitats, while others may be unaffected. [ABSTRACT FROM AUTHOR]

Living plant neighbours, but also their dead aboveground remains ( i.e. litter), may individually exert negative or positive effects on plant recruitment. Although living plants and litter co-occur in most ecosystems, few studies have addressed their combined effects, and conclusions are ambivalent. Therefore, we examined the response in terms of seedling emergence and growth of herbaceous grassland and forest species to different litter types and amounts and the presence of competitors. We conducted a pot experiment testing the effects of litter type (grass, oak), litter amount (low, medium, high) and interspecific competition (presence or absence of four Festuca arundinacea individuals) on seedling emergence and biomass of four congeneric pairs of hemicryptophytes from two habitat types (woodland, grassland). Interactions between litter and competition were weak. Litter presence increased competitor biomass. It also had positive effects on seedling emergence at low litter amounts and negative effects at high litter amounts, while competition had no effect on seedling emergence. Seedling biomass was negatively affected by the presence of competitors, and this effect was stronger in combination with high amounts of litter. Litter affected seedling emergence while competition determined the biomass of the emerged individuals, both affecting early stages of seedling recruitment. High litter accumulation also reduced seedling biomass, but this effect seemed to be additive to competitor effects. This suggests that live and dead plant mass can affect species recruitment in natural systems, but the mechanisms by which they operate and their timing differ. [ABSTRACT FROM AUTHOR]

Pore network geometries of intra-aggregate pore spaces are of great importance for water and ion flux rates controlling C sequestration and bioremediation. Advances in non-invasive three-dimensional imaging techniques such as synchrotron-radiation-based x-ray microtomography (SR-μCT), offer excellent opportunities to study the interrelationships between pore network geometry and physical processes at spatial resolutions of a few micrometers. In this paper we present quantitative three-dimensional pore-space geometry analyses of small scale (-5 mm across) soil aggregates from different soil management systems (conventionally tilled vs. grassland). Reconstructed threedimensional microtomography images at approximate isotropic voxel resolutions between 3.2 and 5.4 pm were analyzed for pore-space morphologies using a suite of image processing algorithms associated with the software published by Lindquist et al. Among the features quantified were pore-size distributions (PSDs), throat-area distributions, effective throat/pore radii ratios as well as frequency distributions of pore channel lengths, widths, and flow path tortuosities. We observed differences in storage and transport relevant pore-space morphological features between the two aggregates. Nodal pore volumes and throat surface areas were significantly smaller for the conventionally tilled (Conv.T.) aggregate (mode ≈ 7.9 × 10-7 mm3/≈ 63 μm2) than for the grassland aggregate (mode ≈ 5.0 × 10-6 mm3/≈ 400 μm2), respectively. Path lengths were shorter for the Conv.T. aggregate (maximum lengths < 200 μm) compared with the grassland aggregate (maximum lengths > 600 μm). In summary the soil aggregate from the Conv.T site showed more gas and water transport limiting micromorphological features compared with the aggregate from the grassland management system. [ABSTRACT FROM AUTHOR]

Seedling establishment is influenced by litter cover and by seed predators, but little is known about interactions between these two factors. We tested their effects on emergence of five typical grassland species in a microcosm experiment. We manipulated the amounts of grass litter, seed sowing position and earthworm activity to determine whether: (i) the protective effect of litter against seed predation depends on cover amount and seed sowing position, i.e., on top or beneath litter; (ii) seed transport by earthworms changes the effect of seed sowing position on seedling emergence; and (iii) seeds transported into deeper soil layers by earthworms are still germinable. Litter cover and presence of earthworms lowered seedling emergence. The impact of seed position increased with seed size. Emergence of large-seeded species was reduced when sown on the surface. Additionally, we found an important seed position × earthworm interaction related to seed size. Emergence of large-seeded species sown on top of the litter was up to three times higher when earthworms were present than without earthworms. Earthworms also significantly altered the depth distribution of seeds in the soil and across treatments: on average 6% of seeds germinated after burial. In contrast to the seed position effect, we found no size effect on mobility and germinability of seeds after burial in the soil. Nevertheless, the fate of different-sized seeds may differ. While burial will remove large seeds from the regeneration pool, it may enhance seed bank build up in small-seeded species. Consequently, changes in the amount of litter cover and the invertebrate community play a significant role in plant community composition. [ABSTRACT FROM AUTHOR]