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Invasive species in Slovenia

Throughout whole the world, invasive alien species are recognized among researchers, as a large problem for biodiversity, economy and health. This is also the case for Slovenia.

Invasive species spread easily and are more competitive for resources then other species. For example we have the plant species canadian Goldenrod (Solidago canadensis) which grows faster than other plants and gets more sun but also attract more pollinators then other plant species. Therefore they are a threat for more vulnerable species.

The grey squirrel is another example, this species was first discovered in Great Britain and nowadays strips the bark from the tree stem, so the tree dies. This gives a lot of economical damage among forestry.

The last example is the case of Ambrosius spp. in the Balkan. This species makes a lot of pollen, which is very aggressive towards humans.

Impatiens glandulifera outcompetes other native plants (Photo: Nejc Jogan)

These are some examples of invasive species and their effects. But how come they get such an advantages above other (related) species. One of the explanations is that they don't have any natural enemies anymore and they can use their energy for other purposes then defense, like increasing growth speed, more floral rewards, etc.

Density of invasive plant species in Slovenia (c) dr. N. Jogan, 2006. Data is based on the "Materials for the atlas of Flora of Slovenia", Center of Carthography for Flora and Fauna (CKFF).

Till now, 42 invasive plant species are recorded for Slovenia. They mainly are confined to human settlements and places where they are easily transported like rivers and roads. The large densities of invasive plant species in the southwest (Koper), west (Nova Gorica), central Slovenia (Ljubljana and vicinity), southeast (Novo Mesto) and north east (Maribor), which are the largest cities and towns of Slovenia. The large stripe in the north west is the Mura river. The places with the lowest density of invasive species are the mountaneous parts, like the Alps and the Sneznik.