Historic disturbance events may overrule climatic factors as drivers of
ruderal species distributions in the Scandinavian mountains
Abstract
The contemporary interaction of climate and land use change drives
vegetation composition and species distribution shifts, making their
respective roles difficult to disentangle. In this study, we
investigated long-term ruderal plant species distributions along the
‘Rallarvägen’ trail in Abisko, subarctic Sweden – a trail established
for railroad construction in 1903 and paralleled by the E10 Highway
(since 1982). Using vegetation and climate data from 1903, 1913, 1983,
and 2021, we found that warm-adapted ruderal plant species were already
common along the Rallarvägen at its initial creation at the start of the
20th century. Interestingly, however, many of these native and
non-native ruderals with relatively high temperature affinity that were
present in 1903 and 1913, disappeared since then and did not return,
despite the substantial rise in temperature in the region over the last
decades. The historical disturbances also had long-lasting effects on
the current spatial distribution of the ruderal vegetation. Most
ruderals still reside close to the railroad tracks and are progressively
filtered out with increasing distance from anthropogenically disturbed
introductory points, such as train stations, where they peak in richness
– a process we coined Horizontal Directional Ecological Filtering, in
parallel to the established concept of Directional Ecological Filtering
along elevational gradients. We conclude that it is important to know
the disturbance history of a system to get a good understanding of the
long-term dynamics in the vegetation community, and thus its possible
future in a changing climate.