Appearance. This relatively tall, slender tree can grow to 100 feet in height and have a trunk diameter of 20 inches. Most jack pines are smaller because they often live in nutrient-poor sandy or rocky soil, where they grow very well but not very tall. Jack pine needles are short, rarely more than 2 ½ inches long, and packed in bundles of two. The bark of mature trees is usually dark gray and scaly, sometimes almost flaky. Unopened cones tend to grow parallel to the branch, pointing forward, typically with the tip curving inward.
Range and Habitat. Jack pine is common throughout the vast boreal region of Canada. It extends south into the Great Lakes region, primarily in Minnesota, Wisconsin, and Michigan. It also grows in parts of New England. In Minnesota, jack pine is found predominantly in the northern and central forested regions. Small outliers exist in southeastern counties. The largest native stands are on bedrock in the Boundary Waters Canoe Area Wilderness and in sandy outwash plains in north-central Minnesota.
Natural History. Most wild jack pines begin life in the aftermath of a devastating fire. That's not a coincidence; it's a strategy. It begins with the seeds, many of which are sealed inside the cones with resin, which protects them from drying out. In the heat of a wildfire, the resin melts and the seeds are released. Although the fire may kill the parent trees, the seeds survive and grow quickly, more quickly than most other trees in the forest. Jack pines as young as 5 years old will start producing the next generation of seeds. This species is so well adapted to fire that in parts of boreal Canada where the interval between wildfire is short, nearly all trees except jack pine have gradually been eliminated. Jack pine does not, on average, live as long as other pines. The record age in Minnesota may be a 243-year-old jack pine found in the BWCAW. Where it is not protected, jack pine is usually cut for pulp before reaching 65 years.
Status. Jack pine is the most common species of pine in Minnesota and is likely to remain so for the foreseeable future. Even though it is vulnerable to canker-producing fungi, dwarf mistletoe, sawflies, and, most seriously, jack pine budworm, the species appears to be secure in Minnesota.
However, substantial forests of jack pine of natural origin are in steep decline. Native stands are likely to survive only in protected areas. This is due to a number of factors, particularly the recent expansion of potato farming in the Park Rapids area, high industrial demand for wood fiber, changing forestry practices, and loss of important ecosystem functions, especially fire.
Welby Smith, DNR botanist