Head: prof. RNDr. Petr Pyšek, CSc.
- Factors determining naturalization and spread of alien species
- The role of species traits in plant invasions
- Invasiveness of alien plant species and invasibility of habitats
- Developing schemes for standardized scoring of impacts of invasive plants and animals
- Global database of naturalized alien plants (GloNAF)
- Case studies of invasive species
Selected recent results
1/ Persistent soil seed banks promote invasiveness in plants
With globalization facilitating the movement of plants beyond their native range, preventing potentially harmful introductions requires knowledge of what drives the successful establishment and spread of alien plants. We examined global-scale relationships between naturalization and invasion success, soil seed bank properties (type and densities) and key species traits (seed mass, seed dormancy and life form) for 2350 species of angiosperms. Naturalization and invasiveness were strongly associated with the ability to form persistent seed banks but relatively weakly with seed bank densities and other traits. Our findings suggest that seed bank persistence is a trait that better captures the ability to become naturalized and invasive compared to seed traits more widely available in trait databases. Knowledge of seed persistence can contribute to our ability to predict global naturalization and invasiveness and to identify potentially invasive flowering plants before they are introduced.
- Gioria M., Carta A., Baskin C. C., Dawson W., Essl F., Kreft H., Pergl J., van Kleunen M., Weigelt P., Winter M. & Pyšek P. 2021: Persistent soil seed banks promote naturalisation and invasiveness in flowering plants. Ecology Letters 24, 1655 – 1667. doi:10.1111/ele.13783
Global naturalization incidence and extent of alien plants in relation to seed bank properties.
2/ Comparing impacts of native and invasive dominants on species diversity of plant communities
Invasive alien plants are known to reduce the diversity of recipient communities, but there is an ongoing debate on whether or not native dominant species have similar effects. To answer this question, we compared invasive dominant species of plant communities in central Europe with native species that dominate uninvaded communities in that region. The results showed that both native and invasive dominants can reduce the diversity of vegetation. In total, 17 dominants (nine native and eight invasive) significantly reduced community species richness, with Reynoutria ×bohemica, Calamagrostis epigejos, Phalaris arundinacea and Urtica dioica having the strongest effect. To conserve biodiversity, measures should be adopted to mitigate not only the impacts of invasive species but also those of native dominants, spreading in the current landscape; this would be best achieved by promoting traditional management and land-use.
- Hejda M., Sádlo J., Kutlvašr J., Petřík P., Vítková M., Vojík M., Pyšek P. & Pergl J. 2021: Impact of invasive and native dominants on species richness and diversity of plant communities. Preslia 93, 181 – 201. doi:10.23855/preslia.2021.181
Comparison of the impact of native and invasive dominants on species diversity of plant communities. The longer the bar the stronger the negative impact.
3/ Latitudinal patterns of plant invasions
Using the native and alien plant distribution data from 801 regions (including islands), we compared invasion levels (i.e. alien richness/total richness) in the Northern and Southern Hemispheres and across continental regions and islands around the globe. We show declining richness with increasing latitude, but the patterns differ among mainland and islands. Invasion levels decrease towards higher latitudes on islands but in continental regions, we found a unimodal pattern on each hemisphere. We identified significantly greater invasion levels on islands than in continental regions. Our findings identified latitudes with invasion hotspots where management is urgently needed, and latitudes with many areas of low invasions but high conservation potential where prevention of future invasions should be the priority.
- Guo Q., Cade B. S., Dawson W., Essl F., Kreft H., Pergl J., van Kleunen M., Weigelt P., Winter M. & Pyšek P. 2021: Latitudinal patterns of alien plant invasions. Journal of Biogeography 48, 253 – 262. doi:10.1111/jbi.13943
Comparative global patterns of plant invasion levels (alien richness/overall species richness) across latitudes and hemispheres when both islands and continental regions around the globe are combined.
4/ Phylogenetic relatedness mediates persistence of seeds in soil
Using a global seed bank database (GloSSBank) comprising data for 2,350 angiosperms, we examined whether soil seed bank type (transient vs. persistent) and density are determined by phylogenetic relatedness. We found a significant phylogenetic signal in seed bank type and density, providing evidence that the ability to form persistent seed banks is not randomly distributed across the phylogeny. The ability to persist in the soil was phylogenetically correlated with the production of dormant and smaller seeds, but seed mass and seed dormancy per se were poor predictors of seed persistence. Interestingly, habitat-related variables (mainly disturbance and canopy openness) but not climate significantly affect the ability of seed plants to form persistent seed banks. Our study is the first to show that phylogenetic relatedness plays an important role in explaining seed bank properties in angiosperms and how these properties relate to early life-history traits, climate and habitat-related variables. These findings represent important insights into plant behaviour in unpredictable environments and how seed plants might respond to global environmental changes.
- Gioria M., Pyšek P., Baskin C. C. & Carta A. (2020) Phylogenetic relatedness mediates persistence and density of soil seed banks. Journal of Ecology 108: 2121–2131. doi: 10.1111/1365-2745.13437
5/ Socioeconomic factors in biological invasions: which plants we cultivate and how we chose them?
To analyse how human cultivation habits contribute to naturalization success, we combined global databases on economic uses and naturalization success of the world’s seed plants. We found that naturalization likelihood is 18 times higher for plants with economic value than for noneconomic plants. Naturalization success is highest for plants grown as animal food or for environmental uses (e.g. ornamentals) and increases with number of uses. Taxa from the Northern Hemisphere are over-represented among economic plants, and economic plants from Asia have the greatest naturalization success. Phylogenetic patterns in the naturalized flora partly result from phylogenetic patterns in the plants that humans choose to cultivate (van Kleunen et al. 2020). Which plants and animals are selected for cultivation and captivity, though, is partly determined by species charisma, defined as a set of characteristics, and the perception thereof, that affect people’s attitudes and behaviours toward a species. We show that such charisma can influence all stages of the invasion process, from introduction patterns to management actions by influencing public support or contributing to social conflicts (Jaric et al. 2020).
- van Kleunen M., Xu X., Yang Q., Maurel N., Zhang Z., Dawson W., Essl F., Kreft H., Pergl J., Pyšek P., Weigelt P., Moser D., Lenzner B. & Fristoe T. (2020): Economic use of plants is key to unravelling their naturalization success. – Nature Communications 11: 3201. doi: 10.1038/s41467-020-16982-3
- Jarić I., Courchamp F., Correia R. A., Crowley S. L., Essl F., Fischer A., González-Moreno P., Kalinkat G., Lambin X., Lenzner B., Meinard Y., Mill A., Musseau C., Novoa A., Pergl J., Pyšek P., Pyšková K., Robertson P., von Schmalensee M., Shackleton R. T., Stefansson R. A., Štajerová K., Veríssimo D. & Jeschke J. M. (2020): The role of species charisma in biological invasions. – Frontiers in Ecology and the Environment 18: 345–353 (doi: 10.1002/fee.2195). doi: 10.1002/fee.2195
6/ Mycorrhizal fungi and other symbionts as drivers of plant geography and implications for invasions
Mycorrhizal associations are less common among native island plants than native mainland plants, but naturalized floras show a greater proportion of mycorrhizal plant species on islands than in mainland regions. Mycorrhizal plant species are more likely to naturalize than non-mycorrhizal plants, and species with facultative mycorrhizal associations are more successful than those with obligate mycorrhizal associations. Mycorrhizae are an overlooked driver of global plant biogeographical patterns.
Naturalized floras show a greater proportion of mycorrhizal plant species on islands than in mainland regions, as expected from the anthropogenic co-introduction of plants with their symbionts to islands and anthropogenic disturbance of symbionts in mainland regions. Taken from Delavaux et al., Nature Ecology and Evolution 2019.
- Delavaux C. S., Weigelt P., Dawson W., Duchicela J., Ess F., van Kleunen M., König C., Pergl J., Pyšek P., Stein A., Winter M., Schultz P., Kreft H. & Bever J. D. (2019) Mycorrhizal fungi influence global plant geography. Nature Ecology and Evolution 3: 424–429. doi: 10.1038/s41559-019-0823-4
- Pyšek P., Guo W.-Y., Štajerová K., Moora M., Bueno C. G., Dawson W., Essl F., Gerz M., Kreft H., Pergl J., van Kleunen M., Weigelt P., Winter M. & Zobel M. (2019) Facultative mycorrhizal associations promote plant naturalization worldwide. Ecosphere 10: e02937. doi: 10.1002/ecs2.2937
- Warrington S., Ellis A., Novoa A., Wandrag E. M., Hulme P. E., Duncan R. P., Valentine A. & Le Roux J. J. 2019. Cointroductions of Australian acacias and their rhizobial mutualists in the Southern Hemisphere. Journal of Biogeography 46: 1519-1531. doi: 10.1111/jbi.13602
7/ Changes in species richness in the Anthropocene: from global inventories to theoretical concepts
The first global analysis of the effects of biogeographic factors, the physical environment and socioeconomy on the richness of naturalized and invasive alien plants revealed that socioeconomic factors were more important in explaining invasion than naturalization (1). The analysis was based on publicly released Global Naturalized Alien Flora (GloNAF) database, including 13,939 naturalized taxa and their distribution in 1,029 regions of the world, including 381 islands (2). To contribute to the global data on plant invasions we also developed global inventories of two functional groups, terrestrial alien ferns (3) and tall stature naturalized grasses (4). A separate analysis revealed that North and South America might face contrasting challenges in terms of potential threats to biodiversity posed by alien plant species, because of the different past and present dynamics of invasions and predictions of future development. In North America and South America additions of naturalized species to the native flora from other continents make up 6.9 and 1.4 %, respectively (5). As a theoretical concept we argue that it is important to distinguish species for which human-induced environmental changes are important indirect drivers of range expansion into new regions and that such species will become an essential feature for biodiversity management and science in the Anthropocene. We propose the term neonative for these taxa (6).
Dynamics over time of new species introductions to North and South America. (A, left panel) cumulative numbers of species, (B, right panel), numbers recorded as per year. Taken from Pyšek et al., Global Ecology and Biogeography 2019
- 1. Essl F., Dawson W., Kreft H., Pergl J., Pyšek P., van Kleunen M., Weigelt P. et al. (2019) Drivers of the relative richness of naturalized and invasive plant species on the Earth. AoB Plants 11: plz051. doi: 10.1093/aobpla/plz051
- 2. van Kleunen M., Pyšek P., Dawson W., Essl F., Kreft H., Pergl J., Weigelt P. et al. (2019) The Global Naturalized Alien Flora (GloNAF) database. – Ecology 100: e02542. doi: 10.1002/ecy.2542
- 3. Jones E. J., Kraaij T., Fritz H. & Moodley D. 2019. A global assessment of terrestrial alien ferns (Polypodiophyta): species’ traits as drivers of naturalisation and invasion. Biological Invasions 21:861-873. doi: 10.1007/s10530-018-1866-1
- 4. Canavan S., Meyerson L. A., Packer J. G., Pyšek P., Maurel N., Lozano V., Richardson D. M., Brundu G., Canavan K., Cicatelli A., Čuda J., Dawson W., Essl F., Guarino F., Guo W-Y, van Kleunen M., Kreft H., Lambertini C., Pergl J., Skálová H., Soreng R. J., Visser V., Vorontsova M. S., Weigelt P., Winter M. & Wilson J. R. U. 2019. Tall-statured grasses: a useful functional group for invasion science. Biological Invasions 21: 37-58.doi: 10.1007/s10530-018-1815-z
- 5. Pyšek P., Dawson W., Essl F., Kreft H., Pergl J., Seebens H., van Kleunen M., Weigelt P. & Winter M. (2019): Contrasting patterns of naturalized plant richness in Americas: numbers are higher in the North but expected to rise sharply in the South. Global Ecology and Biogeography 28: 779–783. doi: 10.1111/geb.12891
- 6. Essl F., Dullinger S., Genovesi P., Hulme P. E., Jeschke J., Katsanevakis S., Kühn I., Lenzner B., Pauchard A., Pyšek P., Rabitsch W., Richardson D. M., Seebens H., van Kleunen M., van der Putten W., Vilà M. & Bacher S. (2019) A conceptual framework for range-expanding species that track human-induced environmental change. BioScience 69: 908–919. doi: 10.1093/biosci/biz101