Background and aims Understanding the mechanistic
effects of climate change on species key life-history
stages is essential for predicting ecological responses.
In fire-prone regions, long-term seed banks allow
post-fire recovery and persistence of plant populations.
For physically dormant species, seed bank
longevity depends on the maintenance of dormancy
which is controlled primarily by temperature. Successful
inter-fire recruitment is rare and dormancy
loss between fires produces a net loss to the seed
bank. We assessed whether temperature increases related to climate change can affect seed dormancy
and, potentially, seed bank longevity.
Methods We quantified the relationship between air
temperatures and soil temperatures. Seeds of two
shrub species, from four populations along an
altitudinal gradient, were then exposed to a range of
soil temperatures calculated to occur at the end of the
21st century, using projected mean and heat wave
scenarios. Alterations to dormancy were assessed via
Results For every 1°C increase in air temperature,
associated soil temperature increased by 1.5°C. Mean
temperature increase had no affect on seed dormancy.
However, future heat wave conditions produced soil
temperatures that significantly increased dormancy
loss. This impact was greatest in seeds from cooler,
high elevation populations.
Conclusions Projected heat wave events produce conditions
that provide a mechanism for seed bank
compromise. Dormancy-breaking temperatures for each
population were positively related to parental environment
temperatures, indicating local adaptation. Whilst
heat from fire may govern post-fire recruitment
response, we suggest that parental climate is the key
selective force determining dormancy-breaking threshold
temperatures, ensuring inter-fire seed bank