Invasive plants – general concepts

Invasive plants are non-native plant species that have been introduced intentionally or accidentally by humans outside their area of origin and that reproduce and spread extensively, to the detriment of native species. Most often originating from other continents, they profoundly disrupt ecosystems and reduce local biological diversity.

The main characteristics of an invasive plant are:

• Adaptation to all types of environments, even the most unfavourable ones.
• Extensive vegetative reproduction, enabling rapid occupation of space.
• High seed production, which is easily dispersed by wind.
• Very rapid growth, increasing competition with native species.

These neophytes therefore represent a real ecological and economic threat and must be combated consistently. In Valais, as throughout Switzerland, measures are being taken to inform and raise awareness among the population in order to counter this serious ecological threat.

Switzerland has around 700 exotic plant species, of which approximately 90 are invasive or potentially invasive. Conversely, some native plants can also behave as locally invasive species and may therefore be undesirable.

It turns out that a number of these plants are melliferous, or even highly melliferous. However, environmentally conscious beekeepers must be prepared to forgo this problematic honey flow and should report the presence of potentially problematic plants to the relevant cantonal authorities  (www.infoflora.ch/fr/participer/mes-observations/carnet-en-ligne.html), bearing in mind that these alien plants also reduce the diversity of native melliferous species.

The main invasive melliferous plants in Valais are giant hogweed, Cape ragwort, tree of heaven, buddleia