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In the northern forelands of the Alps, farmers report an increase of Jacobaea aquatica in production grasslands. Due to its toxicity, the species affects grassland productivity and calls for costly control measures. We are investigating the extent to which management practices or climatic factors are responsible for the increase of the species and how the situation will change due to climate change. We tested for effects of management intensity, fertilization, agri-environmental measures, and soil disturbance, and modeled the occurrence of the species under rcp4.5 and rcp8.5 scenarios. The main determinants of the occurrence of the species are soil type and summer rainfall. A high risk is associated with wet soils and > 400 mm of rain between June and August; an influence of the management-related factors could not be detected. Under the climate-change scenarios, the overall distribution decreases and shifts to the wetter alpine regions. Thus, the current increase is rather a shift in the occurrence of the species due to the altered precipitation situation. Under future climatic conditions, the species will decline and retreat to higher regions in the Alps. This will decrease the risk of forage contamination for production grassland in the lowlands. [ABSTRACT FROM AUTHOR]

From construction and demolition of buildings, brick wastes accumulate in large quantities and are difficult to recycle. Re-using bricks as planting substrate could partly substitute gravel or other raw materials, and would reduce deposition of bricks in landfills. High water-holding capacity and a high specific surface of such substrates are beneficial for plant growth, while high pH could be a disadvantage. This study focuses on potential effects of brick-based substrates on survival, growth and functional traits of two urban trees (Acer platanoides, Tilia cordata). We compared the effects of brick quantity (5 vs. 30%), pre-treatment with phosphoric acid, nutrient-poor vs. -rich soil, and mycorrhiza inoculation upon saplings in two greenhouse experiments. There were no effects on survival, while a high brick ratio slightly reduced growth of A. platanoides and its branching in nutrient-rich soil, and tend to increase the root-to-shoot ratio in both species. The acid pre-treatment caused negative effects on relative growth rate of A. platanoides. Mycorrhiza inoculation had a tendency for a positive effect on growth in T. cordata, but only with 5% brick ratio. Overall, the brick-based substrates have no clear effect on the study species. Thus, bricks can be recommended as a neutral component within constructed Technosols, and can be used to modify grain size distribution without negative effects on survival, growth and performance, while further studies are needed on bricks with cement and gypsum contaminations. Highlights: Brick rubble is a promising component of urban plant substrates. Tree saplings of Acer platanoides and Tilia cordata have good survival and grow well on brick-based substrates. Mycorrhiza inoculation has no effect on survival and growth or A. platanoides and T. cordata. Acid pre-treatment of bricks has no effect on survival and growth of the tree saplings. [ABSTRACT FROM AUTHOR]

Arthropods respond to vegetation in multiple ways since plants provide habitat and food resources and indicate local abiotic conditions. However, the relative importance of these factors for arthropod assemblages is less well understood. We aimed to disentangle the effects of plant species composition and environmental drivers on arthropod taxonomic composition and to assess which aspects of vegetation contribute to the relationships between plant and arthropod assemblages. In a multi-scale field study in Southern Germany, we sampled vascular plants and terrestrial arthropods in typical habitats of temperate landscapes. We compared independent and shared effects of vegetation and abiotic predictors on arthropod composition distinguishing between four large orders (Lepidoptera, Coleoptera, Hymenoptera, Diptera), and five functional groups (herbivores, pollinators, predators, parasitoids, detritivores). Across all investigated groups, plant species composition explained the major fraction of variation in arthropod composition, while land-cover composition was another important predictor. Moreover, the local habitat conditions depicted by the indicator values of the plant communities were more important for arthropod composition than trophic relationships between certain plant and arthropod species. Among trophic groups, predators showed the strongest response to plant species composition, while responses of herbivores and pollinators were stronger than those of parasitoids and detritivores. Our results highlight the relevance of plant community composition for terrestrial arthropod assemblages across multiple taxa and trophic levels and emphasize the value of plants as a proxy for characterizing habitat conditions that are hardly accessible to direct environmental measurements. [ABSTRACT FROM AUTHOR]

Ecological restoration aims at supporting biodiversity and ecosystem services, and urban greening is a great opportunity to achieve this goal. This is facilitated by species-rich seed mixtures based on local provenances, which are designed for certain nutrient and moisture regimes based on functional plant traits. Such grassland mixtures might be cultivated on crushed waste bricks, which would be a new component of water-holding urban substrates. Thus, we studied the effects of brick quantity and quality, acid pre-treatment of bricks, soil type and moisture on biomass of designed seed mixtures. Three greenhouse experiments were conducted, with substrates consisting of different brick ratios (5% vs. 30%), brick types (clean production waste vs. demolition material), and brick treatments (acid vs. control) tested on three trait-based mixtures and a non-regional commercial standard mixture. The trait-based mixtures included information on specific leaf area, seed mass and grass-to-legume ratio. There were no negative effects of demolition bricks, soil texture and moisture on grassland biomass. Acid-treated clean porous bricks improved biomass production of the standard and intermediate mixtures, while the effect was minimal with demolition bricks. Designed seed mixtures had a biomass similar to the standard mixture under dry conditions but did not benefit from high moisture like the standard mixture. In conclusion, waste bricks are a useful additive for urban restoration substrates to save raw material, and specifically designed regional mixtures can replace commercial grassland types on these substrates. [ABSTRACT FROM AUTHOR]

Higher temperatures can increase metabolic rates and carbon demands of invertebrate herbivores, which may shift leaf-chewing herbivory among plant functional groups differing in C:N (carbon:nitrogen) ratios. Biotic factors influencing herbivore species richness may modulate these temperature effects. Yet, systematic studies comparing leaf-chewing herbivory among plant functional groups in different habitats and landscapes along temperature gradients are lacking. This study was conducted on 80 plots covering large gradients of temperature, plant richness and land use in Bavaria, Germany. We investigated proportional leaf area loss by chewing invertebrates ('herbivory') in three plant functional groups on open herbaceous vegetation. As potential drivers, we considered local mean temperature (range 8.4–18.8 °C), multi-annual mean temperature (range 6.5–10.0 °C), local plant richness (species and family level, ranges 10–51 species, 5–25 families), adjacent habitat type (forest, grassland, arable field, settlement), proportion of grassland and landscape diversity (0.2–3 km scale). We observed differential responses of leaf-chewing herbivory among plant functional groups in response to plant richness (family level only) and habitat type, but not to grassland proportion, landscape diversity and temperature—except for multi-annual mean temperature influencing herbivory on grassland plots. Three-way interactions of plant functional group, temperature and predictors of plant richness or land use did not substantially impact herbivory. We conclude that abiotic and biotic factors can assert different effects on leaf-chewing herbivory among plant functional groups. At present, effects of plant richness and habitat type outweigh effects of temperature and landscape-scale land use on herbivory among legumes, forbs and grasses. [ABSTRACT FROM AUTHOR]

Invasive non-native plants challenge ecosystems restoration, and understanding the factors that determine the establishment of invasive plants is crucial to improve restoration outcomes. However, the drivers of invasibility of plant communities are not sufficiently clear, and combined effects are not understood. Therefore, we investigated the contribution of the main drivers of invasion success during early phases of restoration, i.e., biotic resistance, invasive propagule pressure, and environmental fluctuations. We compared the contribution of these drivers in a series of mesocosms experiments using designed grasslands as a model system, and Solidago gigantea as invasive model species. Two grassland communities were designed according to competitive trait hierarchies with different sowing patterns, reflecting variation in biotic resistance. We then manipulated invader propagule pressure and applied different scenarios of environmental fluctuation, i.e., flood, heat, and N fertilization. Invasive biomass was considered as proxy for invasion success, while native biomass represented restoration success. There were consistent effects of biotic resistance to S. gigantea invasion via competitive trait hierarchies in the three experiments. Communities dominated by species with high-competition traits were more resistant regardless of environmental fluctuation. Clumped seeding of the native community reduced invasibility, whereas high non-native propagule density increased invasion. The effects of environmental fluctuation were less consistent and context-dependent, thus playing a secondary role when compared to biotic drivers of invasion. Restoration initiatives on grasslands impacted by invasive plants should consider biotic resistance of the restored community as a key driver and the importance of controlling further arrivals of invasive species during community assembly. [ABSTRACT FROM AUTHOR]

One of the main questions in ecosystem restoration is where to obtain the seeds to re-establish plant communities. While the most commonly advocated approach is to use seeds from local sources, some experts argue against this because local populations may harbour little genetic variability for the restored populations to be able to adapt to and survive global change. Instead, they propose alternative strategies such as mixing seeds from various sources to increase genetic variability and adaptive potential, or using seeds from populations that have a similar climate as predicted for the target locality in the future. All these alternative seed-sourcing strategies have in common that they involve a transplanting of plant ecotypes, sometimes over large spatial scales. This is risky because plants from distant origins may be maladapted to the current local abiotic and biotic environment. In addition, introduction of non-local provenances will disrupt natural patterns of within-species biodiversity and will affect ecological networks, with unpredictable consequences. To balance the value of local adaptation with the need for future adaptation potential, we propose 'regional admixture provenancing' as a compromise strategy. Here seeds are sourced from multiple populations within the same region as the target locality and mixed prior to use. The mixing of seeds will increase the genetic diversity necessary for future adaptation, while restricting seed origins to a regional scale will maintain regional adaptation and reduce the risk of unintended effects on other biota. This approach is feasible in practice and has recently been implemented in Germany. We believe that it represents a compromise to reconcile opposing views on ecological restoration. [ABSTRACT FROM AUTHOR]

Temporarily flooded depressions in arable fields support populations of specialised plant species that are affected by flooding and agricultural management. Depending on the degree of flooding, different proportions of wetland and arable species contribute to the seed bank. This is reflected by high inter-annual variations in plant communities with a high conservation value. Due to ongoing agricultural intensification, the biodiversity of temporarily flooded depressions has declined, and several plant species have become regionally extinct. Because seed banks harbour persistent seeds over long periods, they play a crucial role in the conservation and restoration of temporary wetland vegetation. This study focuses on the effects of different flooding regimes on plant species emerging from seed banks of temporarily flooded depressions in arable fields in northeast Germany. We cultivated soil samples from upper and lower wetland zones under short, intermediate and long-term flooding (5, 15 and 40 cm above soil surface) in a common garden experiment over 2 years. We observed significant changes in species composition depending on the flooding duration. Species richness declined and evenness increased with increasing flooding duration. Upper and lower zones showed similar species richness and evenness, but species compositions differed. Red List species emerged from all treatments although the species differed, indicating that all communities emerging under different flooding regimes have a high conservation value. Seed banks under fluctuating site conditions can constitute a series of alternating plant communities. This could be used to develop management strategies that benefit different communities with high conservation values. [ABSTRACT FROM AUTHOR]

Land managers face the challenge to set priorities in monitoring and managing non-native plant species, as resources are limited and not all non-natives become invasive. Existing frameworks that have been proposed to rank non-native species require extensive information on their distribution, abundance, and impact. This information is difficult to obtain and often not available for many species and regions. National watch or priority lists are helpful, but it is questionable whether they provide sufficient information for environmental management on a regional scale. We therefore propose a decision tree that ranks species based on more simple albeit robust information, but still provides reliable management recommendations. To test the decision tree, we collected and evaluated distribution data from non-native plants in highland grasslands of Southern Brazil. We compared the results with a national list from the Brazilian Invasive Species Database for the state to discuss advantages and disadvantages of the different approaches on a regional scale. Out of 38 non-native species found, only four were also present on the national list. If management would solely rely on this list, many species that were identified as spreading based on the decision tree would go unnoticed. With the suggested scheme, it is possible to assign species to active management, to monitoring, or further evaluation. While national lists are certainly important, management on a regional scale should employ additional tools that adequately consider the actual risk of non-natives to become invasive. [ABSTRACT FROM AUTHOR]

Invasion ecology has much advanced since its early beginnings. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. We argue that progress in invasion research can be accelerated by, first, pointing out difficulties this field is currently facing and, second, looking for measures to overcome them. We see basic and applied research in invasion ecology confronted with difficulties arising from (A) societal issues, e.g., disparate perceptions of invasive species; (B) the peculiarity of the invasion process, e.g., its complexity and context dependency; and (C) the scientific methodology, e.g., imprecise hypotheses. To overcome these difficulties, we propose three key measures: (1) a checklist for definitions to encourage explicit definitions; (2) implementation of a hierarchy of hypotheses (HoH), where general hypotheses branch into specific and precisely testable hypotheses; and (3) platforms for improved communication. These measures may significantly increase conceptual clarity and enhance communication, thus advancing invasion ecology. [ABSTRACT FROM AUTHOR]

The scope of re-introduction as a measure for plant species protection is increasing, but as long as no standardized methods are available, species-specific assessments are necessary to determine whether seeds, adult plants or plant fragments should be used. The endangered German False Tamarisk ( Myricaria germanica), which occurs on gravel bars along pre-alpine rivers, is difficult to grow from seeds. Thus, propagation of stem cuttings was investigated as an alternative method. Experiments were conducted in a greenhouse and a field site with three treatments: cutting length 5 or 10 cm, vertical burial 5 or 10 cm, and water level low or high. Plants grown in the greenhouse were transplanted to the River Isar to test establishment of rooted cuttings on gravel bars. The cuttings in the greenhouse showed high survival (34-96 %). Survival and biomass production were greatest for 10-cm cuttings buried at 10-cm depth, while only one of the 5-cm cuttings survived at this depth, and no significant effect of variation in water level was observed. None of the cuttings transplanted to field sites survived, most likely because of drought stress and competition. We conclude that for re-introduction of Myricaria germanica rooted cuttings can be easily produced in large quantities, while transplantation to near-natural environments has to be improved to reduce mortality. [ABSTRACT FROM AUTHOR]

Rapid range expansions are becoming more prevalent, especially as climate continues to change. The escape of ornamental plants within their native range represents a significant, but often overlooked component of this process. Few studies have focused on the role of ornamental plants in range expansions using molecular markers to identify the possibility of mixed native and cultivar populations. The purpose of the present study was to determine the genetic variation of a native woody plant with ornamental conspecifics at the edge of its distribution. We selected Ilex aquifolium L. (English holly) which grows naturally in Denmark but is spreading eastward in Scandinavia, possibly due to a combination of climate change and introduction of more frost-tolerant cultivars. We sampled 187 individuals from older and recently established populations, and cultivated I. aquifolium throughout Denmark, and compared them using nuclear SSR and AFLP. The overall results showed no structure or clustering of plants from the historical or the expanding range, or of wild or cultivated plants. The only clusters found were for a group of cultivated hybrid I. aquifolium. The samples represented four genetic groupings, indicating either hybridization between cultivated and wild I. aquifolium or replacement of the latter by cultivars. Thus, ornamental genotypes of I. aquifolium contribute to the northeastern range expansion of the species and eventual invasiveness within its native range. [ABSTRACT FROM AUTHOR]

The theoretical underpinnings of the assessment of invasive alien species impacts need to be improved. At present most approaches are unreliable to quantify impact at regional scales and do not allow for comparison of different invasive species. There are four basic problems that need to be addressed: (1) Some impacted ecosystem traits are spatially not additive; (2) invader effects may increase non-linearly with abundance or there may be effect thresholds impairing estimates of linear impact models; (3) the abundance and impact of alien species will often co-vary with environmental variation; and (4) the total invaded range is an inappropriate measure for quantifying regional impact because the habitat area available for invasion can vary markedly among invasive species. Mathematical models and empirical data using an invasive alien plant species ( Heracleum mantegazzianum) indicate that ignoring these issues leads to impact estimates almost an order of magnitude from the real values. Thus, we propose a habitat-sensitive formula for regional impact assessment that is unaffected by non-linearity. Furthermore, we make some statistical suggestions on how to assess invader effects properly and we discuss the quantification of the invaded range. These improvements are crucial for impact assessment with the overall aim of prioritizing management of invasive species. [ABSTRACT FROM AUTHOR]

Control of plant invasions requires regional knowledge of invasive species' distribution and the factors that promote their spread. We studied the distribution of invasive alien plants in Denmark at 2 spatial scales ("site" and "municipality") based on habitat descriptions and species lists from 2343 sites recorded within environmental assessments for planned infrastructure projects and conservation management. We created a Geographic Information System database of the sites and supplemented the field data with information on traffic routes, water courses, and socioeconomic indicators from the respective municipalities. The percentage of invaded sites within a municipality decreased with increasing tax percentage and it increased with (sub-)urbanity. The number of invasive species at the sites was positively correlated with resident plant diversity, disturbance, and proximity to traffic routes. We conclude that current plant invasions in Denmark are mainly an anthropogenic (sub-)urban phenomenon. The results are discussed with respect to the utility of environmental assessment data for studying plant invasions and improving control of invasive species. [ABSTRACT FROM AUTHOR]

Analysis of nuclear microsatellites in six small populations of Sorbus torminalis on its northern distribution limit was carried out to evaluate the dominating mode of reproduction as well as genetic diversity within and among populations. Within populations there was a low genetic diversity with heterozygote excess in five populations. Genetic differentiation was high among populations and the amount of clonally arisen recruits was 94-100%. This suggests that clonal growth, small population size and a possible self-incompability system maintain heterozygosity, although some genetic drift would also be expected. The results are discussed with respect to potential conservation strategies for S. torminalis in the study region. [ABSTRACT FROM AUTHOR]

This is the first review on taxonomy, morphology, ecology, conservation and utilisation of Abies guatemalensis, an endangered endemic conifer in Central America. The species became recently split up in seven varieties with a distinct geographic pattern. A number of morphological traits separate the species from the co-occurring A. hickelii and A. religiosa. The species is used for charcoal production, as valuable timber and (more recently) as highly priced greenery. However, utilisation is not sustainable and may lead to regional extinction within few decades. Protection of the species seems to be most efficient if based on community forest management. As a new conservation tool we suggest establishment of Christmas tree and greenery plantations which could generate significant income for the local farmers. The existing knowledge on A. guatemalensis should be used to steer utilisation, to generate livelihood improvements for the local Maya communities, and to optimise regional and national conservation efforts. Conservation of the species is urgent because it occurs in endangered highland forests which provide significant ecosystem services including erosion control and supply of drinking water. Inconsistencies in description of the species and gaps in knowledge are highlighted and future research directions suggested. [ABSTRACT FROM AUTHOR]

Kollmann J. and Pflugshaupt K. 2005. Population structure of a fleshy-fruited species at its range edge – the case of Prunus mahaleb L. in northern Switzerland. Bot. Helv. 115: 49–61. Little is known about age structure and reproduction in small populations of woody species at their range edge. Here, we report on the demographic structure of the fleshy-fruited Prunus mahaleb at the margin of its distributional range in northern Switzerland. The aim of the study was to investigate distribution patterns, age structure and plant performance as affected by population size and isolation, altitude and climate. Fifteen small populations were chosen in the Swiss and French Jura, where the species is rare and restricted to exposed cliffs and scree slopes, which are surrounded by beech and oak forests. Plant distribution within populations was often clumped or linear. Irregular recruitment was indicated by uneven age structures with a low number of young plants and missing age classes in some populations. Mean plant age per population ranged from 14 to 42 years. Plant age, stem length and diameter, photosynthetically active crown volume and annual growth increment all differed significally among populations albeit without correlation to population size or altitude. However, recruitment was highest at altitudes between 500 and 600 m, and recruitment and mean plant age were negatively correlated with precipitation during the vegetation period. Plant size was negatively correlated with distance to the nearest population, and positively correlated with nearest neighbour distance. As a conservation tool, forest tree removal may reduce shading and thus increase both vegetative and sexual recruitment in P. mahaleb. [ABSTRACT FROM AUTHOR]

Seed predation by rodents affects plant population dynamics and it may respond to changes in vegetation structure at forest edges. This study investigates the magnitude and direction of a potential edge effect in temperate deciduous forests, and it seeks possible explanations based on predator abundance and vegetation structure. The study was conducted at twelve forest edges in northern Switzerland; in six sites all shrubs at the forest edge were removed, whereas the other sites maintained a structurally rich shrub layer. In each site three transects were laid out from the edge towards the forest interior. In six plots along these transects (at 1, 3, 6, 12, 25, 50 m) we studied seed removal from experimental dishes, rodent abundance in live-traps and four characteristics of the vegetation structure. For both woody seed species (Prunus avium, Viburnum lantana) predation was significantly higher near the forest edge in the structurally rich sites; in the other sites no such gradient was found. Selectively accessible dishes revealed that rodents were the main predators, whereas predation by insects or molluscs was not observed. Abundance of rodents (Apodemus flavicollis, A. sylvaticus, Clethrionomys glareolus) was highest under dense shrubs close to the forest edge. In the structurally rich sites there was a clear gradient of decreasing shrub cover from the edge towards the forest interior; a weaker gradient was observed in the structurally poor sites. We conclude that high shrub cover near the forest edge is the main determinant for edge effects in seed predation, and edges without a shrub belt show no such effect. [ABSTRACT FROM AUTHOR]

This study investigates correlations between mean α-diversity of woody species (fleshy-fruited and non-fleshy-fruited) at forest edges and the attributes of the sites and of the adjacent landscape that might influence it. For a total of 45 forest edges in three areas in northern Switzerland species composition and structure of the edges were recorded. Based on aerial photographs, maps and a ground survey, the adjacent landscape within a radius of 100 m was mapped with GIS for two time periods (1952–1954 and 1994–1997). Diversity of fleshy-fruited species was higher at forest edges adjacent to nutrient-poor grassland or small roads compared with fertilized meadows. A positive correlation existed between diversity of fleshy-fruited species and density of isolated trees in the surroundings, although some trees have disappeared since 1952. Multiple regression analyses revealed that the diversity of fleshy-fruited species correlated positively with edge height and depth, and negatively with mean patch size in the adjacent landscape; a significant fraction of the variation among sites was also explained by the geological bedrock. Only a few other attributes of the sites and of their surroundings had a significant effect. Mean α-diversity of non-fleshy-fruited species correlated with only two landscape attributes, i.e. total forest area and geology. The results are discussed on the basis of dispersal of fleshy-fruited species by passerine birds. The resulting hypothesis is that an increase in species diversity along forest edges is partly controlled by bird-mediated landscape effects. [ABSTRACT FROM AUTHOR]