Invasive neophytes

© Caroline Winklmair, Himalayan balsam.
Habitat: Wild river LechSide valleysAuwälderBrunnwässer

Invasive neophytes

What are invasive neophytes? What can I do?

Neophytes ("new plants") are alien plant species that were introduced into a new area by humans after the discovery of America (1492). This was either intentional (e.g. useful, medicinal, forestry or ornamental plants) or unintentional (e.g. seeds in bird food).

Neophytes are often portrayed as "something to be controlled". However, the term "neophyte" is basically a completely neutral one. In addition to the emotional discussions about the negative effects, it is often forgotten that highly valued species such as the potato or horse chestnut are also neophytes in this country.

A rule of thumb (Tens Rule) states that out of 1,000 introduced species, around 100 will become wild and of these, only 10 will become permanently established. Of the 10 established species, only 1 becomes a "problem neophyte" with negative effects. In order to distinguish problematic neophytes from unproblematic ones, the former are labelled as "invasive" labelled. Their "success strategies": - efficient reproduction - rapid growth - strong competitiveness.

In North Tyrol we find approx. 2,300 plant species, of which approx. 500 are neophytes. Of these 500 species, 15 are considered invasive. They can cause ecological, economic and/or health damage and therefore high costs.

The costs caused by invasive alien species (IAS) are estimated to be at least EUR 12.5 billion per year in Europe*.


The negative effects vary depending on the neophyte species and cannot be generalised. Invasive neophytes are generally a threat to health, the economy and/or nature!

Himalayan balsam (Impatiens glandulifera):

  • Weak or lack of rooting (death of the plant in autumn) " Soil erosion
  • Covering the soil with dead plants " Difficult germination of native plants
  • Extensive spread (dominant stands) " Impoverishment of the accompanying vegetation due to light deprivation
  • High nectar production " Reduced pollination of native plants

Giant hogweed (Heracleum mantegazzianum):

  • Plant sap with harmful ingredients " Burn-like damage to the skin on contact and in combination with sunlight
  • Extensive spread (dominance stands) " Displacement of native plants and the native animals adapted to them
  • Death of the above-ground plant parts in autumn " Erosion on the "open" (vegetation-free) soils

Canadian goldenrod (Solidago canadensis), Late goldenrod (S. gigantea):

  • Effective shoot growth (dominance stands) " Decrease in native species diversity
  • Release of substances into the soil " Suppression of native species
  • Low nutritional value of pollen and nectar " Endangerment of wild bees in particular
  • Near-surface and shallow rhizome network " Soil erosion

Japanese knotweed (Fallopia japonica), Sakhalin knotweed (F. sachalinensis), Bastard knotweed (F. x bohemica):

  • Strong growth in length and thickness of the rhizome (explosive effect) " Damage to buildings, walls, roads, etc.
  • High fragility of the rhizome " On watercourses: Erosion on banks
  • Extensive distribution (dominant stands) " Habitat modification
  • Death of the above-ground plant parts in autumn " Erosion on the "open" (vegetation-free) soils

What can I do?

Intact nature means quality of life. Let's make a joint contribution to preserving our native diversity and our health!

  • Say let your friends know!
  • Plant no invasive neophytes in your garden!
  • Replace invasive neophytes in your garden with native plants!
  • Remove invasive neophytes on your land!
    • "Resist the beginnings" - react as early as possible, because as time passes, the negative effects and the difficulties of combating them increase!
    • Suitable measure: Choose the method depends on the plant species, the stage of development of the plant and the area and density of the crop think and the protection of amphibians, reptiles, birds (ground breeders) and small mammals!
    • The right time and space: Prevent a seed formation!
    • Continuous success checks and, if necessary, follow-up treatments over several years - seed "stock" in the soil, etc.
    • Possible subsequent maintenance of the site (e.g. sowing of site-appropriate seed mixture, planting of site-appropriate trees and shrubs)
  • Avoid the spread of invasive neophytes, because "Prevention is better than aftercare"!
    • Please note: Soil, seeds, bird food, etc. may contain seeds and/or rhizome fragments!
    • Disposal your garden waste properly and not in the open countryside!
  • Report Locations of invasive neophytes (as detailed as possible and with photos)!
  • Turnaround If you have any questions, contact a specialist!

* Institute for European Environmental Policy, Technical support to EU strategy on invasive alien species (IAS). August 2009.


Tyrolean Lech Nature Park
Klimm 2, A-6644 Elmen
Tel.: +43 676 9780136 or +43 664 4168466

Neophyte Competence Centre Tyrol
Dr Konrad Pagitz
University of Innsbruck, Institute of Botany
Sternwartestrasse 15, A-6020 Innsbruck
Phone: +43 512 507 51059

Caroline Winklmair_Springkraut Blüte_Drüsiges Springkraut
© Caroline-Winklmair. Canada goldenrod (yellow), Japanese knotweed, giant hogweed, balsam balsam.

Nature Park