Planter i Oslo havn - Nina

NINA Rapport 637
Abstract
Often, A. & Stabbetorp, O. 2010. Plants at Oslo Harbour - NINA Report 637, 72 p.
In summer 2010 the flora of vascular plants at Oslo Harbour was surveyed. There were found
359 species and subspecies, and 2 hybrids.
We found 7 red-listed species:
Anisantha tectorum EN Endangered, 11 sites
Erigeron acer subsp. droebackiensis NT Near threatened, 2 sites
Fraxinus excelsior NT Near threatened, 15 sites
Juncus minutulus DD Data deficient, 2 sites
Odontites vernus subsp. litoralis VU Vulnerable, one site
Ulmus glabra NT Near threatened, 25 sites
Urtica urens VU Vulnerable, one site
Among the red-listed species we judge the fairly large populations of Anisantha tectorum to be
most valuable. Pastinaca sativa subsp. urens was found as new to Norway, whereas the ornamental
Buddleia davidii was found as escape for the first time in Norway. Nationally rare, urban
weeds as Chenopodium rubrum, Hordeum jubatum and Verbascum lychnitis seem to be fairly
well established at Oslo Harbour. Halophytes were sparse, only 20 species were recorded.
The survey was initiated because there was reported an extensive stand of the invasive species
Senecio inaequidens at Kongshavn, just south of Oslo centre. This turned out to be a mistake.
However, a large stand of S. inaequidens was later found at Sjursøya, a little bit further south. In
addition single plants of S. inaequidens were found scattered within the harbour. All these plants
were eradicated.
There were several small occurrences of species classified as invasive plants on national level, in
addition to S. inaequidens e.g. Bunias orientalis, Fallopia japonica, Fallopia x bohemica, Lupinus
polyphyllos, Solidago canadensis, Rosa rugosa and Vincetoxicum rossicum. These occurrences
are worth to eradicate.
In general the flora was more species-rich on granite-quay compared to quays made of concrete
or wood. However, the most valuable botanical site was a strip of semi-natural meadow between
the new-built Opera and the west bank of the river Akerselva (site 37). At this single patch there
were found 131 taxa including several regionally rare species. We suggest this strip of land to be
managed as an urban patch of semi-natural grassland.
Anders Often (anders.often@nina.no), Odd Stabbetorp (odd.stabbetorp@nina.no), Norwegian
Institute for Nature research (NINA) Gaustadalléen 21, NO-0349 Oslo, Norway
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