Assessing tree germination
resilience to global warming: a manipulative experiment using sugar maple (Acer saccharum).
Kevin Solarik, Dominique Gravel, Aitor Ameztegui, Yves Bergeron, Christian Messier.
A climate warming of 2–5°C by the end of the century will
impact the likelihood of seed germination of sugar maple
(Acer saccharum), a dominant tree species which possesses
a restricted temperature range to ensure successful
reproduction. We hypothesize that seed origin affects
germination due to the species’ local adaptation to temperature.
We tested this by experimentally investigating
the effect of incubation temperature andtemperatureshifting
on sugarmaple seed germination fromseven different
seed sources representing the current species range.
Survival analysis showed that seeds from the northern
range had the highest germination percentage, while
the southern range had the lowest. The mean germination
percentage under constant temperatures was best when
temperatures were ?5°C, whereas germination percentages
plummeted at temperatures ?11°C (5.8%). Cool
shifting increased germination by 19.1% over constant
temperature treatments and by 29.3% over warm shifting
treatments. Both shifting treatments caused earlier germination
relative to the constant temperature treatments.
A climate warming of up to +5°C is shown to severely
reduce germination of seeds from the southern range.
However, under a more pronounced warming of 7°C,
seed germination at the northern range become more
affected and now comparable to those found from the
southern range. This study states that the high seed germination
percentage found in sugarmaple at the northern
range makes it fairly resilient to the warmest projected
temperature increase for the next century. These findings provide forestmanagerswith the necessary information to
make accurate projections when considering strategies
for future regeneration while also considering climate