Pinus banksiana, commonly known as jack pine, has the widest distribution of all pines in Canada. Its ecology provides insight into the interconnectivity that exists within ecosystems; since its success as a species is disturbance-driven, you could say that what kills it (or burns it) makes it stronger.
These jack pine cones were photographed in Minnesota, near the southern extent of the distribution of the species. The range of Pinus banksiana starts in northern Canada and expands eastward through the boreal forest to cover much of central & eastern Canada and several of the bordering lower 48 states. The waxy-coated cones will only release seeds when exposed to intense heat from fire or (occasionally) hot weather. They can persist, closed, on the tree for 10-20 years. This adaptation, along with its intrinsically fast initial growth rate, allows this species to quickly recolonize newly-bare sites after fires. However, the trees are intolerant of shade, and with enough time between stand-replacing fires, black spruce, white spruce, and balsam fir will emerge from the understory and eventually replace jack pine. Pinus banksiana is noted to be the best-adapted conifer to fire (PDF) in Canada’s boreal forest–“a forest shaped by fire“. Deciduous species that can respond immediately to fire alongside jack pine may do so through sprouting from stumps or roots. Since jack pine grows predominantly on acidic soils, it is often accompanied by acidophilic blueberry shrubs in the understory.
Where jack pine extends a small portion of its range into Michigan, it plays a key ecological role for Kirtland’s warblers. As a species, Kirtland’s warblers were once critically endangered with fewer than 200 singing males in the latter part of the 20th century. Their recovery has been moderately successful (IUCN Red List). Sometimes known as jack pine warblers, they strictly require stands of young jack pine for breeding habitat. While threats such as cowbird parasitism at breeding sites and disturbance to wintering grounds were at the forefront of their decline (and have been addressed in recovery management), management of jack pine stands to mimic natural fires has increased the potential breeding habitat in Michigan significantly, and perhaps is the biggest factor in recovery.
I found determining conifer identities to be fun when I was faced with the task for a plant identification exam last year. However, it definitely becomes more challenging when tasked to identify a conifer based on just a shoot and no cone. The main identifiable features of jack pine (among other pines it grows with) are: a) needles in pairs of two; b) cones usually-incurved and pointing towards the shoot apex; and c) cones with minimal or no sharp points on the scales. Included in my identification exam were all native pines of British Columbia, so I assumed that jack pine was a common tree in this province where I did not grow up. In reality, you’d only encounter it in the wild in British Columbia if you were in the very northeastern corner of the province.
The works of renowned Canadian painter Tom Thomson have featured jack pines in a few pieces. Most famously, perhaps, his painting The Jack Pine depicts a rather abstracted jack pine with a beautifully contrasting sunset in the background. This painting invokes fond memories of northern Ontario, where endless lakes surrounded by foothills cover the landscape.
Jack pine is the preferred host of the jack pine budworm (Choristoneura pinus) which defoliates mature trees and whose range coincides very closely with that of jack pine. After devastating many lodgepole pines in British Columbia, the mountain pine beetle (Dendroctonus ponderosae) poses a potential threat to these boreal pines in the future, though the seriousness of the impacts of the mountain pine beetle are difficult to predict as it spreads eastward into the smaller and less dense jack pine stands of the boreal forest.