Forest for the Trees: How Humans Shaped the North Woods

9 The Big Blow Down

9 The Big Blow Down There are few places left on the North American continent where men can still see the country as it was before Europeans came and know some of the challenges and freedoms of those who saw it first, but in the . . . Northwest it can still be done. sigurd olson In the end, the greatest ecological damage to the bwcaw came not from the lumberjack but from the well-intentioned fledgling foresters trying to reestablish a timber industry, from their ambitious tree-planting campaign and their remarkably effective fire-suppression programs. After the creation of Superior National Forest, the usfs led citizens’ organizations, state conservation agencies, churches, schools, and the Boy Scouts in planting white pine seedlings in the cutovers around Ely and Winton. During the depression the Civilian Conservation Corps (ccc) accelerated this effort. By 1943, more than 32,000 acres of Superior National Forest had been replanted in red, white, and jack pine, and an additional few thousand acres of state, county, and private lands had been sown by other agencies and groups. With every hunting license the state dispensed packets of pine seeds for sportsmen to distribute as they roamed after grouse, deer, ducks, and bear. Foresters scattered seed while making their rounds.1 Foresters replanted seedlings on more than three thousand acres within the bwca. While they grew some seedlings at Birch Lake’s nurs155 ery and at others in Eveleth and Two Harbors, many of the trees came from commercial plantations. This flurry of tree planting was not limited to the Winton watershed, for all the Great Lakes states as well as defunct pineries in the east had caught the arbor bug. When American nurseries could not meet demand, groups bought seedlings from European nurseries, mostly in Germany. Some of this seed stock carried the white pine blister rust (Cronartium ribicola), a disease well known in Europe, typically causing only minor damage to that continent’s white pine. In the United States, however, the disease flourished and was far more destructive.2 As early as 1897 scientists in Maine discovered blister rust on English stock of black currant, an alternate host of the disease, but this awareness did not halt import of the foreign seedlings. In 1905 foresters found the rust in Pennsylvania; the following year, in New York. When Congress finally acted against the threat with the Plant Quarantine Act of 1912, it was too late. Three years later, white pine blister rust reached Minnesota, where native flora plus the Arrowhead’s weather offered it a particularly accommodating home.3 Blister rust spends part of its life on white pine and part on plants belonging to the genus Ribes, such as currants and gooseberries, the latter of which thrives in Minnesota’s cutover areas. Blister rust requires both species to reproduce, and its spores can spread from Ribes plants to white pine trees only when the temperature is less than sixty degrees and the pine needles are covered with moisture for at least twenty-four hours. Renowned for cool, still, foggy fall days that come one after another , the border lakes offer perfect conditions for infection. Blister rust zones are rated on a scale from one, where the disease has the least effective reproduction and spread, to four, where the disease is most destructive. The Arrowhead sets the top of the scale. Fire suppression only contributed to the spread and intensification of the disease. White pine regeneration depends on periodic lowintensity fire to clear competing plants from beneath the overstory. Such fire also suppresses Ribes plants by consuming the litter on the forest floor, wiping out not only the plant but also its seed bank stored there. The dense undergrowth that flourishes in the absence of fire increases blister rust infection by trapping moisture near the ground, by the big blow down 156 crowding and stressing pine seedlings, and by creating denser concentrations of Ribes. Fire has always been part of white pine’s growing cycle. Historically, moderate-intensity fires crept through the northern forests about once every thirty to fifty years, destroying Ribes seeds, burning the leaf litter , and leaving mineral soils exposed. White pine seed will only take hold when it is in direct contact with mineral soils; without periodic fires to clear the forest floor, very few sites had exposed soils on which the seedlings could establish themselves. Fire also tends to move quickly up...