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National Laboratory for Health Security

Ecologists and hikers have a major role in the seed dispersal of weedy and invasive plant species

Nowadays, one of the most effective seed dispersal vectors are humans. The key our efficiency is the rapidly growing rate of global transport, trade and tourism, which enables us to move more and more easily and quickly between distant biogeographical regions, and even between continents. Based on the results of studies so far, nearly 500 species have been registered to be able to spread on clothing, and most of thes are weed and invasive species that cause serious conservation problems, especially in the isolated habitats.
In a study, published in the journal Science of the Total Environment, members of the HUN-REN Centre for Ecological Research, ‘Lendület‘ Seed Ecology Research Group, analysed the potential mechanisms that might affect the outcome of seed dispersal on clothing. Their research involved 88 volunteers in a multi-site field experiment with samples collected from Hungary, Romania, and the Czech Republic. Researchers accompanied volunteers on 39 sampling occasions during fieldwork or filed trips and provided each participants a new pair of socks at the beginning of the day. At the end of the outdoor activity, they collected the seeds from socks. They also collected seeds from the inside and outside of volunteers’ shoes (a total of 251 samples and 2,008 subsamples were collected). During the experiment, they also recorded the sampling date, distance walked, and time spent outside, a list of plants to characterise the species pool of the visited site and the participants’ clothing type.
Their results show that dispersal on clothing can play an important role in seed dispersal between habitats and regions. The process allows the spread of many species: researchers have found nearly 36,000 seeds from nearly 230 plant species. Nearly half of the dispersed species were disturbance-tolerant or weed species, but there were also large numbers of species associated with natural habitats. In total, researchers observed the spread of 11 invasive and adventive species. Interestingly, most seeds were spread by men and field biologists during visits to grassland habitats. The type of clothing and footwear also had a significant effect on the dispersal efficiency: wearing long pants and high-top shoes can decrease seed dispersal potential compared to wearing short pants and low-top shoes (e.g., sneakers). Based on the result, it is crucial to inform people about this phenomenon, as our individual habits and behaviour can reduce the spread of weeds and invasive plant species.

Community science based monitoring of invasive mammal and bird species

Community science based monitoring of invasive mammal and bird species of Hungary has begun in a cooperation between the Institute for Wildlife Management and Nature Conservation of Hungarian University of Agriculture and Life Sciences (MATE) and the Institute of Ecology and Botany, Centre for Ecological Research.
On the BeaverMap website [], maintained by the Centre for Ecological Research, researchers are collecting data about five semi-aquatic mammal species, which are the following: Eurasian beaver – a native species with community interest in the European Union; nutria, American mink and muskrat – invasive alien species; Eurasian otter – a strictly protected native species in Hungary. If the informant is unsure in the identification of the observed semi-aquatic mammal species, he can ask for help from the researchers. When submitting an observation, the informant has to upload at least one documentative photo, mark the location on the map, and fill out a short questionnaire. In the frame of the questionnaire, it is also possible to share experiences and opinions related to the activity and effects of the species.
The new website [] of the MATE Institute for Wildlife Management and Nature Conservation aims to collect data about some invasive mammalian and bird species with game management interest. Informants can submit data about the raccoon, raccoon dog, muskrat, nutria, American mink, Canada goose and Egyptian goose. Based on photos and descriptions placed on the website, it is possible to recognize the observed species with a high certainty. On the basis of these, we expect registered users to provide data on species observations, supported by photos if possible.

Invasion Biology Division research at the Eurasian Grassland Conference

This year, the Eurasian Grassland Conference was held in Szarvas, organized by the Lendület Seed Ecology Research Group of the HUN-REN Ecological Research Centre and the Körös-Maros National Park Directorate, where several research groups of the Invasion Biology Division presented their latest results. In the opening plenary lecture, Dr. András Kelemen, researcher of the Lendület Seed Ecology Research Group, talked about the invasive species threatening the grasslands of the Kiskunság region. He showed the results of a citizen science programme to survey naturalized cacti populations and a study to test the control of sand dropseed, and reported on the emergence of new invasive species such as the knotgrass (Paspalum distichum). Katalin Lukács, also a member of the research group, presented a poster showing that seeds remaining on clothing do not lose their germinative capacity even after washing and can therefore continue to spread. She was awarded the Best Young Investigator prize in the poster category for her high-quality work. The very first session of the conference was dedicated to invasive species. The first session of the conference was dedicated to invasive species. In it, Dr. Melinda Halassy, head of the Restoration Ecology Research Group of the HUN-REN Centre for Ecological Research, first presented the impact of the combined seeding of native competitor species on the establishment of invasive species. She was followed by Boglárka Berki, PhD student of the HUN-REN Ecological Research Centre’s Large-scale Vegetation Ecology Research Group, who presented the results of their research on the possible management of the common milkweed, one of the most common invasive species. During the post-conference programme f, led by Dr. András Kelemen, Dr. György Kröel-Dulay and experts from the Kiskunság National Park Directorate, participants were able to learn about the invasive species and possible management methods in Kiskunság.

Indirect effects of plant invasion and fragmentation on native plants and grassland arthropods

Plant invasion and habitat fragmentation have adverse effects on biodiversity in almost all ecosystems. Our research explored the direct and indirect effects of common milkweed (Asclepias syriaca) invasion on plant and arthropod biodiversity. For our study, we selected 30 Hungarian forest-steppe fragments of different sizes. Each was sampled in a common milkweed-invaded area and a control area. We recorded vegetation structure, measured temperature and soil moisture, and collected data on arthropods with different ecological roles in the invaded and control areas of the fragments. We studied plants, bees, butterflies, flower-visiting wasps and flies, true bugs and spiders.
Temperature and soil moisture were lower in the invaded area than in the control area. Common milkweed had a positive effect on plant species richness and flower density. We found mainly indirect effects of invasion on arthropods through changes in habitat microclimatic characteristics and food sources. Pollinators responded positively to the abundance of native flowers, so that the common milkweed had an indirect positive effect on pollinators. Similarly, we found higher numbers of true bug species in invaded areas than in control areas, as the species richness of true bugs also increased with increasing diversity of native plant species. Predators were positively affected by complex vegetation structure, higher soil moisture and lower temperatures. Furthermore, increasing fragment size negatively affected spider species richness in control areas but did not affect areas invaded by common milkweed. Grassland specialist spiders were more sensitive to fragment size than generalists, while generalist spider species were more sensitive to invasion.
The positive effect of milkweed on generalist species may homogenise communities in the long term. The density of common milkweed and the success of its dispersal may increase with fragmentation, and we therefore recommend removing invasive plants from small habitat fragments to preserve native habitat. The study of generalist species and the indirect effects of invasion are essential to understanding the impact of invasive plant presence.

Citizen science and mosquito research: the relationship between urbanisation and invasive mosquitoes in Hungary

Urbanisation can contribute significantly to the spread of invasive mosquito species and the diseases they spread. Urbanised habitats provide access to large food sources (humans and domestic animals) and offer abundant breeding sites for mosquitoes. Although human-formed landscapes are often associated with the presence of invasive mosquito species, there still remains a lack of knowledge about the relationship between each species and the built environment. In the present study, the relationship between the extent of urbanisation and the presence of invasive mosquito species was investigated, with a focus on the distribution of the Asian tiger mosquito, the Japanese bush mosquito and the Korean mosquito. Data were collected using citizen science, within the framework of the mosquito, which collected invasive mosquito occurrence data between 2019 and 2022 with the contribution of the general public.

The research found that the relationship between each species and urbanized landscapes was found to be different. The presence of the Asian tiger mosquito showed a statistically significant and positive relationship with urbanization, while the presence of the other two invasive mosquito species showed no relationship with urbanization.

The results highlight the importance of citizen science in scientific research, as data collected using this approach can be used to better understand the drivers of invasion and the ecological needs of invasive species.

Garamszegi, László Zsolt; Soltész, Zoltán; Kurucz, Kornélia; Szentiványi, Tamara: Using community science data to assess the association between urbanization and the presence of invasive Aedes species in Hungary Parasites & Vectors, 2023

Sowing large quantities of native species can reduce the establishment of invasive alien species

Invasions of alien species are a major cause of biodiversity loss, threatening both natural and human-managed ecosystems. Ecological restoration of habitats is key to controlling invasion, and seeding restored habitats with appropriate species can increase their resistance to invasion. In this research, the Centre for Ecological Research’s Restoration Ecology Research Group sought to answer the question: is similarity of plant traits or higher seeding rates of native species more effective at reducing invasive species in the early stages of development?

Seeding experiments were set up in the National Botanic Garden with three alien invasive species that are widespread in Hungary: Common milkweed (Asclepias syriaca), Horseweed (Conyza canadensis) and European bur grass (Tragus racemosus).

The invasive species were grown in pots, sown separately and together with native species. Three dicotyledonous species (Yellow bedstraw Galium verum, Baby’s breath Gypsophila paniculata, Common soapwort Saponaria officinalis) were selected from the Pannonian sandy grassland flora, which have similar plant characteristics, and therefore are expected to have similar resource requirements and stronger competition with the selected invasive species. In addition, a fescue species (Festuca vaginata), the dominant grass species in sand grasslands, and a mixture of all species were also seeded in the experiment. All native species were sown in two different quantities: the same quantity as the invasive species (12-12 seeds) or five times that quantity (60 seeds of the native species).
There were no significant differences between the laboratory-tested germination and germination in pots of the native and alien invasive species. However, it was found that the germination rate of alien species, and consequently their establishment, was reduced when native species were sown at the same time as alien species in higher quantities, although to different extents depending on the species. Seeding of the sand grassland perennial grass (F. vaginata) instead of species with similar characteristics reduced germination the most for all invasive species studied.

These results confirm that invasive alien species can be effectively controlled by sowing native seeds at an early establishment stage, especially at higher densities and using competitive species. Invasion-resistant habitat restoration is best achieved through a combination of several factors. It is important that native species are sown in large quantities and that the seed mixes used include species, such as dominant grasses, that are competitive with invasive species at an early stage of development.

Grassland restoration on roadsides – a nature-based solution to control invasive plant species

Roadside verges are a key corridor for the spread of invasive species and are often considered as invasion hotspots. Invasive plant species are a source of serious problems for both road managers and conservationists. Grassland restoration with seeds of native grassland plant species is a promising solution to control these species. In a recent publication, the CER ‘Lendület’ Seed Ecology Research Group reviewed grassland restoration methods on roadside verges.

The global road network is more than 64 million km long and growing, with road verges occupying nearly 1% of the land area of developed countries. Roadside verges are generally not suitable for industrial, agricultural, or other uses, and can therefore be suitable sites for habitat restoration and creating ecological corridors. For road managers, the ideal situation is to establish a low-input, low-maintenance, permanent vegetation adapted to the site conditions. In many biogeographical regions, roadside verges can provide suitable habitat for drought-tolerant grassland species native to the region, so a well-designed grassland restoration can be an ideal solution from both a conservation and a road management perspective. In the article, the researchers highlight the synergies between these two aspects and the potential and limitations of grassland restoration on roadsides with native species. The most effective way to control invasive plant species is to sow seed mixtures of drought-tolerant and highly competitive plant species native to the region. Although the cost of purchasing these mixtures may exceed the cost of purchasing seed mixtures commonly available commercially, they can provide a more cost-effective solution. Usually, commercial seed mixtures contain seeds of species that are not native or not adapted to the site conditions, and therefore the establishment and survival of the species sown is often unsuccessful. The main message of the review article is that grassland restoration in roadside habitats offers a unique opportunity to control invasive species, establish green corridors, create new habitats, and provide a range of ecosystem services.

The paper can be downloaded from here:
Valkó, O., Fekete, R., Molnár V., A., Halassy, M., Deák, B. (2023): Roadside grassland restoration: Challenges and opportunities in the UN decade on ecosystem restoration. Current Opinion in Environmental Science and Health 34:100490.

Ecological effects of an intensively spreading native species: evaluation of the beavers’ foraging strategy

The Eurasian beaver is a native species with community interest in the European Union. The species was previously extinct in Hungary, but today it is spreading intensively in the country, recolonising its former habitats. The selective foraging activity of the beaver can induce significant changes in the woody vegetation along streams and canals, influencing the competition of native and invasive plant species, as well as the structure of floodplain forests.

An extensive study was conducted by researchers working in the Institute of Ecology and Botany, which aimed at the understanding of the beavers’ foraging strategy. In their new publication, they examined the difference in the frequency of utilization between woody plant taxa, and they also explored the impact of the trunk diameter on the utilization. Based on their results, the selective foraging has a stronger direct impact on the native willow and poplar species than on other native species and on the invasive species present in the supply. Even though smaller trunks are generally preferred against the larger ones, thicker trunks of willow and poplar species can gain a high utilization ratio.

A detailed analysis of the vegetation’s response to this disturbance is still a task for the future. The changes in the floodplain vegetation following the beavers’ activity depends on the survival, sprouting, and regeneration abilities of different woody plant species. Native willow and poplar species, which are foundation species in the floodplain ecosystems, can be supported by improving the hydrological conditions and conducting landscape-level water retention.

Juhász, E., Molnár, Z., Bede-Fazekas, Á., & Biró, M. (2023). General patterns of beavers’ selective foraging: how to evaluate the effects of a re-emerging driver of vegetation change along Central European small watercourses. Biodiversity and Conservation 1-24.

Control of invasive plant species during grassland restoration: timing of seed sowing is key

Timing and the right quantity and composition of the seed mixture are key in seeded grassland restoration. Research by the Centre for Ecological Research has sought to answer the question of how to time the sowing of seed mix components to best establish grassland species and effectively control invasive species and weed. Grasses are usually the backbone of seed mixtures: they form the matrix of the grassland and play an important role in suppressing weed. In landscape-scale habitat restoration projects, it is often not feasible to sow a large area with a diverse seed mix, as there is often not enough seed mix with the right species composition available. In case of the restored species-poor, closed grasslands, additional effort and work is required to establish forb species and control invasive species in later stages of restoration.

In this study, the researchers of the ‘Lendület’ Vegetation and Seedbank Dynamics Research Group combined the sowing of a diverse seed mixture of 20 dry grassland species with the sowing of grass seeds (Festuca pseudovina). They tested how the composition of the plant communities varied depending on whether forb species were sown at the same time as the grass seeds or in the 1st, 2nd or 3rd year after sowing.

The results showed that more work invested in the early stages of grassland reconstruction pays off and leads to more successful outcomes. The results suggest that the best solution is to sow the forb species seeds at the same time as the grass seeds. These plots had the highest diversity of established grassland, the lowest levels of weed infestation and invasive species cover, and the most successful establishment of companion species. The results suggest that the most cost-effective and efficient method is to sow a diverse seed mix at the same time as grass seed sowing, at the beginning of the reconstruction.

The first author of the paper, Réka Kiss, has been awarded the MTA Environmental Youth Prize in recognition of her results.



Kiss, R., Deák, B., Tóth, K., Lukács, K., Rádai, Z., Kelemen, A., Miglécz, T., Tóth, Á., Godó, L., Valkó, O. (2022). Co-seeding grasses and forbs supports restoration of species-rich grasslands and improves weed control in ex-arable land. Scientific Reports 12: 21239. Doi: 10.1038/s41598-022-25837-4

Escape from the gardens: one of our favourite ornamental plants is becoming an invasive species before our eyes

Ornamental plants are introduced to new habitats when they are planted in gardens, where the maintaince creates the suitable conditions for them. Later, in natural habitats, they can easily occupy open niches by escaping from gardens and become invasive. This is the path taken by the great blanketflower, whose ecological effects have been studied by researchers at the Centre for Ecological Research.

The great blanketflower and its relatives are ornamental species planted all over the world. Its escape from gardens and establishment in new habitats have been reported in several countries, but its invasive behaviour has been unknown. However, this species has found suitable habitat conditions in Hungary and has become invasive in some places. Therefore, the researchers aimed to map the distribution of great blanketflower in Hungary, evaluate its impact on the local plant community and determine its invasive potential.

The distribution data show that great blanketflower occurs mainly as casual escapes, but a significant number of naturalised and invasive populations have been found within the country. The species spreads successfully mainly near gardens and disturbed or sandy habitats, but also occurs in semi-natural and natural grasslands. Its establishment has reduced the species richness of the local plant community. Its invasion is facilitated by its well germination capacity, long flowering period and spread by the fur of grazing animals. The great blanketflower does not yet appear to be a strong ecosystem transformer species, but more attention needs to be paid to it, as it could spread strongly and become invasive in the future due to drier weather caused by climate change.

The results of the research suggest that planting blanketflower species in gardens is not recommended, as they can easily colonise natural plant communities once out of the garden, and their sale in seed mixtures is not recommended. There is a need for a survey of great blanketflower and similar alien ornamental plant populations, their long-term monitoring and a more detailed evaluation of their invasion properties.



Süle, G., Miholcsa, Z., Molnár, C., Kovács-Hostyánszki, A., Fenesi, A., Bauer, N., Szigeti, V. Escape from the garden: spreading, effects and traits. NEOBIOTA, 83 pp. 43-69. , 27 p. (2023)