Data from: Local adaptation of trees at the range margins impact range shifts in the face of climate change

The ability of tree species to track their climatic niche at rates
comparable to global warming is concerning, particularly if they are
constrained by local adaptation. If a species is locally adapted at its
range margin it could be beneficial for range expansion as it ensures that
the genotypes colonizing new areas are the fittest because environmental
conditions are more similar to the current ones. In trees, local
adaptation can slow range expansion when climate change happens much
faster than their ability to migrate. We investigate experimentally a
series of factors thought to constrain the seedling phase at the leading
edge of the distribution of a dominant tree species, sugar maple (Acer
saccharum Marshall.). We established a seed transplant experiment using
six provenances, representing the latitudinal species range, and
transplanted them to 12 sites within, at, and beyond the current northern
species range margin. Northern provenances currently provide the best
opportunity for establishment beyond the actual range, where climatic
conditions are more similar than those of the warmer central or southern
portions of the species range. While establishment was highest within the
species range, survival rates were comparable to those at the range margin
and beyond, regardless of provenance. We also find that the local climate
is the most influential factor for early seedling establishment and
survival; however, a lack of suitable microsites also significantly
constrained recruitment. Our study highlights the complex interaction
between provenance, climate, and microsite conditions that are required to
ensure successful seedling recruitment. While sugar maple is currently
displaying evidence for local adaptation to facilitate range shifts, it
could risk maladaptation in the future if the local climate warms beyond
threshold required to ensure seed germination and a lack of favourable
microsite conditions beyond the range.