Gerhard Karrer

University of Natural Resources and Life Sciences Vienna | boku · Institute of Botany

The European Commission requested EFSA to provide an assessment of the processing conditions which make Ambrosia seeds non-viable in feed materials and compound feed. This assessment also includes information on a reliable procedure to verify the non-viability of the seeds. Ambrosia seeds are known contaminants in feed with maximum levels set in th...

The perennial western ragweed (Ambrosia psilostachya DC.) arrived from North America to Europe in the late nineteenth century and behaves invasive in its non-native range. Due to its efficient vegetative propagation via root suckers, A. psilostachya got naturalized in major parts of Europe forming extensive populations in Mediterranean coastal area...

Aims: To develop a consistent ecological indicator value system for Europe for five of the main plant niche dimensions: soil moisture (M), soil nitrogen (N), soil reaction (R), light (L) and temperature (T). Study area: Europe (and closely adjacent regions). Methods: We identified 31 indicator value systems for vascular plants in Europe that contai...

Aims Ellenberg-type indicator values are expert-based rankings of plant species according to their ecological optima on main environmental gradients. Here we extend the indicator-value system proposed by Heinz Ellenberg and co-authors for Central Europe by incorporating other systems of Ellenberg-type indicator values (i.e., those using scales comp...

Invasive species are a key driver of the global biodiversity crisis, but the drivers of invasiveness, including the role of pathogens, remain debated. We investigated the genomic basis of invasiveness in Ambrosia artemisiifolia (common ragweed), introduced to Europe in the late 19th century, by resequencing 655 ragweed genomes, including 308 herbar...

Common ragweed (Ambrosia artemisiifolia) is an invasive plant with allergenic pollen. Due to environmental changes, ragweed pollen (RWP) airborne concentrations are predicted to quadruple in Europe by 2050 and more than double allergic sensitization of Europeans by 2060. We developed an experimental RWP model of allergy in BALB/c mice to evaluate h...

(1) Background: Forestry will have to react to climate change because many tree species suffer. Mitigation can be realized either by planting non-native trees from regions with high climatic stress or by utilizing native tree provenances already adapted to stressful environments. Non-native trees have often generated problems in the past due to unc...

While invasive species are a key driver of the global biodiversity crisis, the drivers of invasiveness remain debated. To investigate the genomic basis of invasiveness in plants, we use the invasive weed Ambrosia artemisiifolia , introduced to Europe in the late 19 th century, resequencing 655 ragweed genomes, including 308 herbarium specimens coll...

bstract: In this paper, Ambrosia tenuifolia (Asteraceae) is reported for the first time in the alien flora of Romania. Data resulting from the revision of herbarium specimens of the perennial ragweed previously collected from the locality of C. A. Rosetti (Danube Delta), as well as the results of our recent field work, revealed that A. psilostachya...

Common ragweed ( Ambrosia artemisiifolia L.) is an annual Asteraceae species native to North America which is highly invasive across Europe and has harmful impacts, especially on human health and agriculture. Besides its wide ecological range, particularly its high reproductive power by seeds is promoting its spread to various habitats and regions....

Ambrosia artemisiifolia L. (Asteraceae), known as common ragweed, is an annual herbaceous species native to North America that has become one of the most economically important weeds in arable fields throughout Central Europe. Its large ecological amplitude enables the species to become established in several types of environments, and management o...

Abstract Since the first documentation of the occurrence of the multivoltine ragweed leaf beetle Ophraella communa in Europe near the Milano airport (Boriani et al., 2013, Bosio et al. 2014) and Southern Switzerland (Müller-Schärer et al. 2014) this species behaves invasively, expanding its distribution towards the Northeastern part of Italy (Augus...

Invasive alien species (IAS) can substantially affect ecosystem services and human well-being. However, quantitative assessments of their impact on human health are rare and the benefits of implementing IAS management likely to be underestimated. Here we report the effects of the allergenic plant Ambrosia artemisiifolia on public health in Europe a...

Common ragweed (Ambrosia artemisiifolia L.) is a widely distributed and harmful invasive plant that is an important source of highly allergenic pollen grains and a prominent cropweed. As a result, ragweed causes huge costs to both human health and agriculture in affected areas. Efficient mitigation requires accurate mapping of ragweed densities tha...

Jacobaea aquatica (=Senecio aquaticus, Asteraceae), marsh ragwort, grows regionally in low management intensity wet grasslands in various European countries. The plant can be regarded as a noxious weed as it contains pyrrolizidine alkaloids (PAs), which cause health problems in livestock. In the Waldviertel region of Northern Austria, marsh ragwort...

Both weed science and plant invasion science deal with noxious plants. Yet, they have historically developed as two distinct research areas in Europe, with different target species, approaches and management aims, as well as with diverging institutions and researchers involved. We argue that the strengths of these two disciplines can be highly comp...

Roadsides are an important habitat for invasive common ragweed, Ambrosiaartemisiifolia L., by facilitating seed dispersal. Reducing the size of roadside populations is therefore essential for confining this highly allergenic species. Here, we aim to determine the cost-effectiveness of mowing regimes varying in frequency and timing, by analysing pop...

To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergen...

Question Disturbed areas offer great opportunities for restoring native biodiversity, but they are also prone to invasion by alien plants. Following the limiting similarity hypothesis, we address the question of whether or not similarity of plant functional traits helps developing seed mixtures of native communities with high resistance to invasive...

Ambrosia artemisiifolia is an annual weed from North America that nowadays is invasive in many countries worldwide. In Austria, numerous populations of A. artemisiifolia are located along the Danube River, especially along the ‘New Danube’ (Vienna). This area is characterised by ruderal and riparian sites, which are regularly flooded. To better und...

Protocol developed to obtain estimates of vital rates (establishment of plants, plant survival, plant growth, reproduction, and seed survival) of populations of the annual common ragweed.

Background: Common ragweed, Ambrosia artemisiifolia, is one of the economically most important worldwide plant invaders, due to its huge production of seeds and allergenic pollen, while its range and impact are expected to increase in future. Knowledge of the population dynamics is essential to understand what factors drive spatio-temporal variatio...

In this contribution, the conservation status assessment of four vascular plants are presented according to IUCN categories and criteria. It includes the assessment at global level of Crepis lacera Ten subsp. titani (Pamp.) Roma-Marzio, G.Astuti & Peruzzi and Anthyllis hermanniae L. subsp. sicula Brullo & Giusso and the regional assessment of Commi...

In this contribution, the conservation status assessment of four vascular plants are presented according to IUCN categories and criteria. It includes the assessment at global level of Crepis lacera Ten subsp. titani (Pamp.) Roma-Marzio, G.Astuti & Peruzzi and Anthyllis hermanniae L. subsp. sicula Brullo & Giusso and the regional assessment of Commi...

Semi-natural pastures have rich plant and animal communities of high conservation value which depend on extensive management. As the area of such land decreases, abandoned semi-natural grasslands have been restored to re-establish biodiversity. Restoration schemes, which include thinning of woody plants and reintroduction of grazing, are mainly des...

Whole vegetation assemblages of 60 relevés (4m²) split in a block design were examined at two montane hay meadow stands over a two year period. All sites were situated at a certified organic farm, managed according to the guidelines of organic farming since 1995. According to the traditional management of this farm acreages are mowed two times per...

The documentation of biological invasions is often incomplete with records lagging behind the species’ actual spread to a spatio-temporally heterogeneous extent. Such imperfect observation bears the risk of underestimating the already realised distribution of the invading species, misguiding management efforts and misjudging potential future impact...

Jacobaea aquatica is a monocarpic Asteraceae growing in wet grasslands of low management intensity. It is considered a noxious weed because it contains pyrrolizidine alkaloids, which cause health problems to livestock. The aim of this study was to develop management options to reduce the population density of J. aquatica in meadows of high nature c...

Background: Ecological indicator values (EIVs) have a long tradition in vegetation ecological research in Europe. EIVs characterise the ecological optimum of species along major environmental gradients using ordinal scales. Calculating mean indicator values per plot is an effective way of bioindication. Following first systems in Russia and Central...

Background: A taxonomic reference list is an indispensable tool to sample, manage and match biodiversity data from different sources. Merging vegetation databases or combining them with taxon-related attributes needs reliable and consistent information about the taxon concepts used and an appropriate naming. Aim: Creating a “taxonomic backbone” of...

Ambrosia artemisiifolia is an invasive annual herb infamous for the high allergenicity of its pollen, which is related to increasing medical costs. Additionally, it can cause serious yield losses as agricultural weed. Common ragweed seeds accumulate in the soil and can remain therein viable for decades, which poses a problem for the sustainable man...

1.This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to envir...

Jacobaea aquatica (Asteraceae) growing in wet grasslands with low management intensity is regarded as a noxious weed with pyrrolizidine alkaloids (PAs), which cause health problems to livestock. The influence of different management practices on the production of PAs and on the proportion of J. aquatica in the fodder was studied. Five cutting regim...

Common ragweed (Ambrosia artemisiifolia) is an invasive annual plant with highly allergenic pollen. Its spread in introduced and native ranges often occurs on roadsides, where it builds stable and rapidly growing populations. The most sustainable way of controlling the population size of this species is to prevent seed production in order to deplet...

The European Union handed over the regulation of common ragweed (Ambrosia artemisiifolia) to the member states. Austrian administration started to ask for control measures, i.e. the Ministry of Agriculture and most federal states of Austria contributed financially to a 3-years national ragweed-project coordinated by the University of Natural Resour...

Ambrosia artemisiifolia (common ragweed) is a highly allergenic alien weed in Europe, which spreads rapidly along roadsides. Road verges are subject to frequent mowing, which further increases the spreading of the plants’ seeds. Ambrosia artemisiifolia reacts to cutting by producing new shoots, which are able to develop flowers and ultimately new s...

Common or short ragweed (Ambrosia artemisiifolia L.) is an annual herb belonging to the Asteraceae family that was described by Carl Linnaeus in the 18th century. It is a noxious invasive species that is an important weed in agriculture and a source of highly allergenic pollen. The importance placed on A. artemisiifolia is reflected by the number o...

The Editorial presents the focus, scope, policies, and the inaugural issue of NeoBiota, a new open access peer-reviewed journal of biological invasions. The new journal NeoBiota is a continuation of the former NEOBIOTA publication series. The journal will deal with all aspects of invasion biology and impose no restrictions on manuscript size neithe...