Conclusions
In this study, ruderal species composition and distributions along the
Rallarvägen showed to be mostly related to the original disturbance
event since its inception at the start of the 20thcentury, as well as to continuous gradients in disturbance intensity,
while recent climate change effects were not (yet) significant.
Different parts of our investigation support this conclusion: 1) the
number of ruderal species that has remained stable over time and the
higher influx of non-native ruderals during railroad building back in
1903 and settlement expansion in 1913, 2) the lower EIV-T-values of
recent ruderal observations, 3) the higher abundance of ruderals closer
to the railroad and train stations in 2021, and 4) the upward migration
of ruderals that was not related to the species’ climatic constraints,
but rather (positively) to their first year of observation. Most
importantly, these findings demonstrate that historic disturbances, not
climate change, have resulted in an influx of warm-adapted species into
this subarctic region. We therefore conclude that these findings warrant
for discretion when we make conclusions about the exact impacts of
climate change to ecosystems, especially when historic disturbances have
been present. Such significant disturbance events can have long-lasting
effects on vegetation compositions and distributions and therefore
overrule climatic factors as drivers of species distributions (Lenoir et
al. 2022). Most importantly, our results highlight the importance of the
knowledge of disturbance history of a system when interpreting species
distributions. Nevertheless, the rapid changes in climate observed in
the Abisko region suggest that we will likely see the fingerprints of
climate change effects on the vegetation communities in the future.