When we use plants that come from other parts of the planet in our area, for example, to plant in our garden because their flowers, colours or shapes are awesome, we are actually moving those plants from their original habitat to another different one.
Those alien species that here can cause serious environmental problems, their place of origin are not problematic at all, because they live in balance with their natural competitors.
Although most of the alien flora can coexist with our native flora without harming it, some of these species become invasive: once they reach the natural habitats in our area, they can overly expand because there are not neither natural competitors nor environmental conditions that can limit their propagation.
In this way, these invasive alien plants occupy all available space and endanger the survival and conservation of native flora species, seriously modifying the functioning of our habitats and ecosystems, and causing landscapes to become the same everywhere.
How do plants move from a garden into the wild?
Introduced alien plants easily escape from the sites where they are planted into natural habitats, either by seed dispersal or some other type of propagule.
Apart from the fact that seeds can be dispersed naturally by the wind or by birds or other animals, we humans contribute greatly to the dispersal of these species into the natural environment, perhaps without being too aware of it: we give cuttings to friends, we plant them in places too close to natural areas or we do not dispose of pruning waste properly.
All this makes it easier for alien plants to thrive in natural habitats, aggravating the problem in the case of species with a high invasive potential.
What are the most affected areas in Catalonia?
In Catalonia, invasive plants issues affect mostly the coastal areas.
One of the most affected habitats most affected is HIC 1240 – Mediterranean vegetated coastal cliffs with endemic Limonium spp.), which is present mainly in the Costa Brava area, with around 610 ha through only 130 km of coastline, and representing almost half of the total area of the habitat in the Iberian Peninsula.
The coastal cliffs have small bushes with wind-modulated forms, sparse discrete grasses and some pine trees and constitute an iconic Mediterranean landscape with high social, cultural and economic value. They are home to unique endemic species of high ecological value, such as Seseli farrenyi, Limonium tremolsii and Limonium geronense, which grow in the Cap de Creus area, or Limonium revolutum, which grows in the Montgrí-Medes area.
The increasing presence of invasive flora on Mediterranean cliffs, which have difficult access to control the invasives, limits both the conservation of the native biodiversity and the maintenance of its ecosystem values, especially in relation to the landscape.
How can you help?
The best way to stop the impact of invasive plants, and especially on coastal cliffs, is to PREVENT, that is, to avoid having potentially invasive species planted in our garden or terrace, especially if we are in an area very close to a natural area.
To do this, the first step is to be aware of what species we have in our garden, to know if they are invasive or potentially invasive, and to know their impact on the natural environment. If you have invasive species, the best thing to do would be to eliminate them and replace them with safe species, i.e. native or exotic plant species that for sure are known not be invasive.
Spring is already here and for sure you will meet your family and friend in your terrace or garden to enjoy a really good time… but remember to look at your plants and try to find out what species they are! If you don’t know what they are, take pictures and upload them to apps like iNaturalist or PlantNet, where you can easily find out what they are.
LIFE medCLIFFS provides you with useful tools, stay tuned!
Once you know which plants you have, check the LIFE medCLIFFS invasive flora factsheets to know if they are invasive or potentially invasive species, and to know their impact on the natural environment. If you want more details, you can also check the online catalogue of the Association Flora Catalana.
In addition to these factsheets, on 14 March 2023, some members of LIFE medCLIFFS met at the headquarters of the Association of Nurseries of Girona province, in Celrà, with the group of external experts who voluntarily collaborate with the project through action C4. They met to reach a consensus on which species should be included in the two lists of not recommended plants:
- A consensus list, which compiles the invasive ornamental species that should be eliminated and no longer traded.
- A watch list for those species that have a significant invasive nature but which do not, a priori, affect the habitat of Mediterranean cliffs.
Once these two lists will be ready, the C4 action group will start working on the list of recommeded plants, which will include all those safe species, i.e. both native and alien species that do not have invasive behaviour. In addition, a code of conduct for the use of ornamental flora will be developed to prevent the spread of invasive plants.
Both the lists and the code can help you to know the Do’s and Dont’s with several plants, so that you can make your garden or terrace safe for our natural habitats. Watch out for their publication!
You can stop plants from moving, get involved!
Photo credits: Roser Melero (photo 1), Gerard Carrion (photo 2) and Associació de Viveristes de Catalunya (photo 3).