Sammendrag
We sow or plant vascular plant species on a large scale in revegetation and restoration
projects in Norway today. Some of the species used are already found in Norway, but many
of the species, subspecies or populations used though native are not local, that is, they are
regionally alien. A regionally alien species is a species that is native to Norway (has been in
Norway since 1800) somewhere in the country, but which has been spread by humans to
places in Norway where they do not occur. In theory, and according to the Biodiversity Act, it
is desirable to use local seeds or plants to preserve local biodiversity.
The aim of this report is to define guidelines that helps prevent the planting of vascular plant
species with a high potential for negative effects on local biodiversity. It is assumed that the
native or local populations are better adapted to local environmental conditions than
populations from other areas or regions, and the risk of harmful genetic changes is therefore
considered small when using local plant and seed sources. Arriving at a common definition
for the area within which plants are “local” is difficult, though; vascular plant species are
numerous (3317 species in mainland Norway, of which more than half are alien species
introduced after 1800, Artdatabanken 2015), have different growth forms, different
environmental requirements, and different reproductive and dispersal ecology. Even closely
related vascular plant species can differ in such characteristics and hence in the extent of the
"place" or “area”.
The dispersal ecology of a plant species is of great importance for whether the species has
genetically distinct populations within its range or not. Different strategies (wind pollination
vs. insect pollination, vegetative propagation vs. seed dispersal, large seeds vs. small seeds)
have an impact on the degree of gene flow between populations and thus also how locally
adapted the species is in different areas. Whether the species has primarily vegetative
reproduction or whether it spreads mainly by means of seeds, and whether the seed
dispersal takes place ballistically, with wind or water, or by zookori (attached to animals or
eaten by animals) determines how far the species can spread and how large gene flow there
is between different populations. Whether the species is pollinated by wind or by the help of
insects also affects the degree of gene flow differently.
In Norway, there is great variation in many biophysical and ecological conditions (climate,
topography, hydrology, and geology) over relatively short distances. This means that species
that grow only a few meters apart can grow under different environmental conditions. This
large variation in environmental conditions - on different spatial scales - can give rise to local genetic adaptation. However, plants have been moved around the landscape for several hundred years by our livestock (as seeds in fur and hooves, and in faeces) from lowland
pasture to mountain pasture and along traffic arteries across the country due to the
extensive transport of animals and people. Over time, this has led to expanded geographical
distribution for several species and increased gene flow between populations over relatively
large distances. .............
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