Sammendrag
Climate change is affecting the composition
and functioning of ecosystems across the globe.
Mountain ecosystems are particularly sensitive to climate
warming since their biota is generally limited by
low temperatures. Cryptogams such as lichens and
bryophytes are important for the biodiversity and
functioning of these ecosystems, but have not often
been incorporated in vegetation resurvey studies.
Hence, we lack a good understanding of how vascular
plants, lichens and bryophytes respond interactively to
climate warming in alpine communities. Here we
quantified long-term changes in species richness, cover,
composition and thermophilization (i.e. the increasing
dominance of warm-adapted species) of vascular
plants, lichens and bryophytes on four summits at
Dovrefjell, Norway. These summits are situated along
an elevational gradient from the low alpine to high
alpine zone and were surveyed for all species in 2001,
2008 and 2015. During the 15-year period, a decline in
lichen richness and increase in bryophyte richness was
detected, whereas no change in vascular plant richness
was found. Dwarf-shrub abundance progressively increased
at the expense of lichens, and thermophilization
was most pronounced for vascular plants, but occurred
only on the lowest summits and northern aspects. Lichens
showed less thermophilization and, for the
bryophytes, no significant thermophilization was
found. Although recent climate change may have primarily
caused the observed changes in vegetation,
combined effects with non-climatic factors (e.g. grazing
and trampling) are likely important as well. At a larger
scale, alpine vegetation shifts could have a profound
impact on biosphere functioning with feedbacks to the
global climate.
Alpine vegetation, Climate change,
Resurvey study, Thermophilization, Cryptogams
Vis fullstendig beskrivelse