In the Lower St. Lawrence region, jack pines manage to persist under very different conditions to those found in the boreal forest where they thrive best. While regular forest fire cycles – which are more frequent in the north – usually cause their resin-saturated cones to open and drop their seeds, at the southern edge of its range, the species has adapted to infrequent and unpredictable fires.
a professor in the Department of Biology, Chemistry and Geography at the Université du Québec à Rimouski, wanted to find out more. Indeed, a better understanding of this conifer population will provide insight into the responses to be expected in the context of climate change.
Does the presence of jack pines in the temperate forest of the Lower St. Lawrence mean that forest fires were more frequent there in the past? Instead, charcoal dating has revealed that jack pine populations have managed to persist there for over 7,000 years, even in the absence of a forest fire regime comparable to that found in northern Québec.
The scientist has put forward an explanation: jack pines are much more diverse in the south than in the north. While northern cones are all very serotinous, those of jack pines at the southern limit are more variable, sometimes even on the same branch. This gives these trees every chance of regenerating, with or without the heat of a fire.
The researcher now wishes to study the genetic variability of southern jack pines. Indeed, if temperate species are moving north as a result of climate change, it is vital to understand whether the jack pine still has what it takes in its genetic baggage to reproduce without fire in tomorrow’s uncertain conditions. It may be best to protect these distinct populations, often found on private land, to ensure that this biodiversity is preserved.
Sources:
Pelletier, E., de Lafontaine, G. (2023). Jack pine of all trades: Deciphering intraspecific variability of a key adaptive trait at the rear edge of a widespread fire-embracing North American conifer. American Journal of Botany, 110, e16111. doi: 10.1002/ajb2.16111
Pelletier, E., Couture, M. et de Lafontaine, G. (2023). Hedging at the rear edge: Intraspecific trait variability drives the trajectory of marginal populations in a widespread boreal tree species. Journal of Ecology, 111, 479-494. doi: 10.1111.1365-2745.14041