The share of present invasive species in the last decade shows an increasing trend. An increase in the share of invasive species is evident along the great rivers Sava, Mura and Drava, as well as along the Kolpa. In higher areas of Slovenia, particularly in the Alps and the Dinaric region, invasive species are very few or entirely absent. However, a notable increase in their share along the western border of the Dinaric region raises concerns.
From the perspective of nature protection, invasive species are generally those expanding spontaneously in their new natural or semi-natural environment and consequently causing serious disturbances/changes in the functioning of the ecosystem.
The indicator shows the comparison between periods by share of invasive species, based on the available data. For the calculation of shares, all available data from the period 1957–2006 were taken into account, while the comparison was made between the periods 1987–1996 (approximately 100,000 pieces of data) and 1997–2006 (approximately 130,000 pieces of data).
To draw up and adopt an operative programme of non-native invasive species management (Resolution on the National Programme of Environmental Protection, 2005):
· to stop or reverse the trend of the increasing share of invasive species in local flora by 2010;
· to prevent the introduction of new invasive species and take immediate action in cases of the beginnings of expansion of new invasive species in order to completely eliminate invasive species.