The role of fire in the mid-Holocene arrival and expansion of lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) in Yukon, Canada

In north-west Canada, Pinus contorta (lodgepole pine) has been migrating northwards and westwards for millennia. Its regeneration is currently enhanced by fire, which may act as a trigger for local population expansion. Using Holocene charcoal records from four small (4000 years after the first local appearance of Pinus, suggesting a long period of stasis at low densities. Population increases – based on pollen accumulation rates (PARs) – occurred at different times at the four sites. Estimated expansion periods were ~2500–800 years, and population doubling times were ~150–600 years, similar to previous estimates. Estimated fire return intervals (FRIs) fluctuated over time. At all sites, the Pinus expansion began during a phase with [...]