• White pine is one of 52 tree species considered native to Minnesota forests. ten species are softwoods, also called conifers or evergreens because they constantly replace their needles. 42 are hardwoods, also called deciduous trees because they shed their leaves in the fall.

• When white settlers entered Minnesota (around 1830) forests covered about two-thirds of the state. East to west forests covered 300 of the state’s 375-mile width and north to south they spanned 364 of its 400-mile depth. Clearings for agriculture and community development have reduced the state’s forestland base by about 50% to about 16.7 million acres. Tree species composition has also changed noticeably. In the absence of wildfires, which have been suppressed for most of this century, thin-barked, fire-sensitive species—most notably aspen, which sprouts from its own roots—have greatly expanded their range.

• A century ago, three forest types dominated Great Lakes region forests. Nutrient-poor near-boreal forests held a mixture of jack pine, aspen, paper birch and black spruce covering some 11 million acres in northeast Minnesota. Fires were frequent. Nutrient-rich northern hardwood-hemlock forests covered almost 38 million acres in northern Michigan and Wisconsin and held a mix of three shade tolerant species: northern hemlock, sugar maple and yellow birch. Fires were infrequent. White-red pine forests were found in all three states in areas where catastrophic fires occurred at 150-300 year intervals. These mixed species forests, which covered about ten million acres, usually established themselves beneath the canopies of faster growing aspen, birch, red maple or oak, species that quickly colonize areas cleared by stand replacing fires. Where fire was more frequent, white pine dominated, sometimes for hundreds of years; but where fires burned infrequently, heavily shaded hardwood forests kept pine from expanding its range.

When Boise Cascade Corporation harvested a mixed aspen stand north of Grand Rapids it reserved about a dozen mature eastern white pine trees as part of its program to assist the state of Minnesota in its efforts to conserve older white pine. Using bright orange water-soluble paint, the company marked each tree with the word “save” to make certain loggers did not cut them by mistake.

• Today, there are 14 forest types, or cover types, in Minnesota, each bearing the name of one or more tree species that form a majority of wood volume in the stand. Aspen is the most common hardwood forest type, accounting for 35% of the state’s 14.8 million-acre timberland base. Black spruce is the most common conifer cover type, accounting for about 9% of the timberland base. Hardwood forests include maplebasswood, oak-hickory and elm-ash-soft maple and birch, which together account for 36% of the timberland base; and softwoods include jack-redwhite pine, which accounts for 5% of the timberland base. Most Minnesota forests contain multiple tree species—in part the result of wide variations in soil types left by retreating glaciers.

• Minnesota’s pioneers devised their own simplistic grouping. “The Big Woods” region was mostly hardwood. It spanned about 5,000 square miles but counted for little in the fortunes of pioneers who saw its rich soil as having more value than its timber. Wheat fields gradually replaced big oaks, maples and hickories. “The pineries” or “North woods” lay east of the Mississippi and ran north into Canada embracing a region larger than the entire state of Maine. These were mixed conifer forests, but it was white pine that gave the region its singular character. No wonder: white pine could be found in every county east of the Mississippi from Minneapolis north to Canada.

• White pine is thought to have entered Minnesota about 7,000 years ago, following the last ice age. No one knows for sure how white pine survived the 40-plus glacial periods that preceded the last ice age, but fossil-pollen records suggest it persisted on exposed continental shelves off the mid-Atlantic coast. As the glaciers melted and the sea level rose again, it came ashore in Virginia’s Shenandoah Valley about 12,000 years ago. From there it worked its way north into Maine 10,000 years ago, then west across the Great Lakes region 9,000 years ago. The prairies that lie west of present-day Itasca State Park halted its westward migration.

• Fossil-pollen records also indicate that beginning about 7,000 years ago, white pine and oak pushed each other back and forth across Minnesota for 3,000 years. During warm dry periods, caused by a shift in the earth’s orbit, oak pushed east more than 60 miles. Thereafter, the climate cooled, allowing pine to push west again.

• The scientific name given to eastern white pine is Pinus strobus, which can be literally translated from Greek as “pine cone,” a reference to its conspicuous long, narrow cone. The tree was first classified by Swedish botanist Carolus Linnaeus, (1707-1778). Early lumbermen called it “white pine,” a reference to its creamy white wood which, because of its softness, is easily worked with hand tools. Its long, slender blue-green needles are grouped in bundles of five, making the tree easy to identify.

• European foresters recognize eastern white pine as Weymouth Pine, for Lord Weymouth, who planted seedlings imported from the U.S. on his English estate more than 200 years ago.

• Next to the sugar pines that grow in southern Oregon and northern California, eastern white pine is the largest pine that grows in the U.S. Early Minnesota lumbermen described monarchs 250 feet tall with trunks six feet in diameter. Minnesota’s largest white pine is located on state-owned land in Itasca County. It measures 131 feet tall, 180 inches in circumference and has a crown spread of 51 feet.

• Eastern white pine is a favorite with many wildlife species. Red squirrels, rabbits, black bears and birds eat its seeds. Beaver, snowshoe hares, rabbits, field mice and porcupines are fond of its bark, and eagles sometimes nest in its massive mast-like crown. Browsing deer enjoy its buds, a fact that poses huge
problems for foresters and Tree Farmers interested in regenerating the species.

• White pine grows slowly at first—usually only about three feet in its first five years. Because it is easily overtaken by competing vegetation, controlling brush is especially important to its early survival and growth. Growth accelerates at about year five. 10 to 30 year-old trees often grow 20 inches a year.

• Unlike aspen or even red pine, white pine seed production is irregular and infrequent. If seed production does not coincide with seedbed preparation (meaning mineral soil is exposed by plowing or fire) successful regeneration is unlikely. White pines begin to produce seeds when they are 20-30 years old.

• White pine is fire-dependent, meaning it cannot regenerate itself in the absence of wildfire or some other kind of disturbance, like harvesting, that creates an opening in the forest canopy while also exposing mineral soil. Even then, white pine lacks important regeneration attributes held by other firedependent species. It does not sprout vegetatively like aspen, and it does not possess serotinous cones that open under the heat of fire, like jack pine or black spruce. And unlike paper birch, it does not produce abundant seed crops year after year.

• No tree growing in America is more susceptible to insect and disease attack than eastern white pine. By one count, 277 different insects and 110 diseases have been known to attack it, though only 16 insects and seven diseases are considered fatal. Among the killers, white pine blister rust is the most prominent. Blister rust is a fungus that entered Minnesota around 1916 in nursery stock imported from England. After entering the needles (turning them a rustbrown color) it advances down the branch to the tree trunk, girdling the stem. Its ability to infect trees depends on the presence of a very narrow range of temperature, wind and moisture conditions. Ironically, these conditions are most often found in low moist sites where white pine thrives. Despite blister rust’s devastating impact, many think pine weevils—which deform trees, causing their trunks to fork—are a greater impediment to commercial white pine management.

• Unlike red pine, young white pines will tolerate some shading from taller nearby trees. Thus, the species thrives in mixed stands, associating itself with red pine, white cedar, birch, aspen, tamarack, oak, jack pine, balsam fir, black spruce, and northern hardwoods including sugar maple. Foresters and tree farmers interested in adding species diversity to their forests often plant white pine in small sunlit openings in their forests. About 2.3 million white pine seedlings are planted annually in Minnesota, twice the amount that was planted before 1998 implementation of the White Pine Initiative.

• White pine’s fire-dependence, its inability to successfully re-seed itself except in exposed mineral soil, its early intolerance for competing vegetation and its vulnerability to insects, diseases and deer, creates a multiple paradox for those who believe restoration is simply a matter of reserving remaining forests in no harvest reserves. Eastern white pine restoration rests on successful regeneration through (1) planting seedlings on the best-suited sites (2) under-planting in mixed species forests (3) selection harvesting to promote natural reseeding during good seed years (4) controlling competing vegetation, blister rust, pine weevil and deer browsing. Prescribed fire can also be used to expose mineral soil seedbeds while reducing competition from hazel, though use of such fire may raise air quality concerns. As an alternative, the soil around white pine seed trees can also be exposed using machines that scarify the ground.

• A 1996 survey by the Minnesota Forest Resources Partnership, a consortium of public and private timberland owners and managers, describes both the potential and the challenge facing those who support white pine restoration. Respondents reported they manage 82,000 acres where white pine is the dominant cover type, but the species is “significantly present” on another 491,000 acres. Statewide, there are 1,008,900 acres of timberland with at least one white pine per acre.

• Before the 1880s, eastern white pine accounted for more than half of all softwood lumber consumed in the United States. Once Minnesota’s mature stands were cut lumbermen turned to Douglas-fir which (because of its structural superiority) quickly replaced pine in many building applications. In 1997, white pine harvesting accounted for less than 5% of total jack-red-white pine harvest, about 2% of total softwood harvest and less than onehalf of 1% of combined hardwoodsoftwood harvest. White pine harvesting is proportionately greater on private and countyowned forests than it is on state and federal ownerships. Between 1989 and 1995, the state lands harvest declined from 333,000 to 43,000 board feet. By comparison, in the 1920s, the Virginia and Rainy Lake Company mills at Virginia, Minnesota, were milling 875,000 board feet per day. About 70% of what was milled was white pine.

• White pine remains a favorite with woodworkers because it is soft and easily painted or stained. It is thus still widely used in window frames, door casings and moldings. And because it is free of objectionable odors and tastes, it is still widely used to make tongue depressors and ice cream sticks.