Sammendrag
Spoil heaps are the visible footprint of hydropower
production, particularly in vulnerable alpine environments.
Speeding up vegetation development by seeding commercial
grass species has been a common restoration practice for the
last 50 years, but we lack information on whether seeded
species decline and allow native plant cover to develop. We
visually estimated cover of native vascular plants and five
seeded grass species (Agrostis capillaris, Festuca ovina,
Festuca rubra, Schedonorus pratensis and Phleum pratense)
on eight spoil heaps at different elevations (boreal–alpine
zone) in western Norway. Spoil heap vegetation was censused
twice (9–20 and 24–36 years after spoil heap construction);
the undisturbed surrounding vegetation was also censused on
the second occasion. Total cover on the spoil heaps showed
some increase, but remained far below that in surrounding
areas. Cover of seeded grass species in the surroundings was
low (but not negligible), indicating suboptimal establishment
ability. Seeded species usually covered less than 20 % of the
spoil heaps, and only F. rubra, F. ovina and A. capillaris contributed
substantially. Proportional cover indicated better initial
establishment by seeded species, but their cover decreased
between the censuses on all but the highest located spoil heap.
The persistence of seeded grass species is problematic, and
despite the decrease in proportional cover, they are likely to
persist for decades on spoil heaps, posing a risk of invasion of
surrounding areas. We therefore recommend replacing the
practice of seeding with more appropriate restoration
measures.
Management implications . Invasion .
Persistence . Restoration . Seeding . Spoil heaps .
Succession . Vegetation
Vis fullstendig beskrivelse