Invasive alien species


The brochure "Invasive plant species and possibility of their eradication" deals with the problem of invasive plant species, i.e. plants that naturally do not occur in our area but have been introduced. Although some invasive species are well known (e.g. the common ragweed) and have been proven to be harmful, people do not generally associate them with the notion of invasiveness. The concept of invasive species is still largely unfamiliar to the general public.

Non-native species are those that were previously not widespread in a specific area. If they start to reproduce independently and begin to have a harmful effect on native organisms, we call them invasive non-native species. The characteristic of invasiveness is a harmful effect on biodiversity and benefits humans have from nature, people's health or simply economic damages to the area of introduction. Invasive non-native plants are usually plants with an extraordinary ability to reproduce and spread in a new environment. They can be introduced into the new environment by human activities, both intentionally and unintentionally. An example of an intentional introduction is planting decorative plants or honey plants. An example of unintentional introduction would be the spread of seeds of an invasive plant species together with seeds of other species, for example common ragweed seeds spreading from America with the seeds of cereal and grain crops.

They have a significant impact on the environment in which they grow and on humans, and the damages they cause to the world economy is estimated at 1,4 billion dollars annually, that is, 5% of the value of world economy. The most affected sectors are economy, health, agriculture, forestry and environment protection. The conditions for their spreading have been man-made because they mostly appear in habitats created by man (e.g. urban areas, agricultural areas, parks, drained wetlands) or as a result of man's disturbance of natural balance which then resulted in decreased resistance to introduction of non-native species. Human activity is the primary driver of their spreading.

The brochure presents only a few invasive non-native species whose impact is such that it is generally agreed that steps should be taken to educate the public about them. Five species that have been selected for the brochure are widespread in Croatia and Europe and have been causing considerable problems. They are the common ragweed, the false indigo bush, the common milkweed, the Himalayan balsam and the knotweed. The common milkweed and the Himalayan balsam have been listed as invasive non-native species which present a major risk in the EU. This means that their introduction, keeping, planting, transportation, placing on market, use, exchange, reproduction, or introduction into environment are prohibited throughout the EU.

If you want to learn more about invasive species, the reasons and manner of their introduction, the effect on habitats and living organisms, their negative effect on biodiversity, or how to eradicate them, click on the link "Invasive plant species and possibility of their eradication".

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