🌳 The tree that lost its forest

Before 1904 the American chestnut was, in the Park Service’s words, “a dominant tree of the eastern U.S.,” and in some forests the chestnuts “made up more than half the mass of living trees.” The Forest Service’s handbook says its range “extended from central Maine west to southeastern Michigan, and south to northern Mississippi, Alabama, and Georgia,” and that “the finest stands were in the southern Appalachians, where mature trees were generally 3 to 5 feet in diameter and 60 to 90 feet in height.” The record giants were bigger still — “scattered specimens were as large as 7 feet in diameter and 120 feet high.” Seven feet across is wider than a grown-up is tall. A hundred and twenty feet is roughly a ten-storey building, made of wood, with nuts falling out of the top of it.

Basis: U.S. National Park Service, “American Chestnuts in the Capital Region”: “The American chestnut was once a dominant tree of the eastern U.S. …”; “In some forests, they made up more than half the mass of living trees.” USDA Forest Service, “American Chestnut … an American wood” (FS-230): “Before American chestnut was attacked by the blight, its range extended from central Maine west to southeastern Michigan, and south to northern Mississippi, Alabama, and Georgia.”; “The finest stands were in the southern Appalachians, where mature trees were generally 3 to 5 feet in diameter and 60 to 90 feet in height. Scattered specimens were as large as 7 feet in diameter and 120 feet high.”

Then something microscopic arrived on imported trees, and the clock on a whole species started running. The National Park Service records it in two sentences: “In 1904 however, the non-native chestnut blight fungus (Cryphonectria parasitica) was introduced and quickly spread through forests of the eastern U.S. By 1950, almost all American chestnuts in their native range were dead.” Forty-six years. A tree that needs a century to grow up was removed from the roof of a continent inside one person’s lifetime.

Basis: U.S. National Park Service, “American Chestnuts in Rock Creek”: “In 1904 however, the non-native chestnut blight fungus (Cryphonectria parasitica) was introduced and quickly spread through forests of the eastern U.S. By 1950, almost all American chestnuts in their native range were dead.”

Here is the part that surprises everyone: the species is not extinct. The fungus kills the trunk, not the roots. “Because the blight fungus does not kill the root system of trees, American chestnuts persist today in natural areas as re-sprouts from blight-free root systems,” says the Park Service — and the Forest Service supplies the other half of the sentence: the chestnut’s “ability to sprout vigorously from the stump has helped chestnut to exist in spite of continued attack by the fungus blight, which persists in living stumps and eventually kills the sprouts.” Root systems older than your great-grandparents keep sending up shoots; the fungus keeps cutting them down. When Park Service scientists inventoried eleven national parks around Washington, D.C. in 2014, they found 234 living American chestnuts — and 91 percent were classed as “overtopped,” their crowns entirely below the forest canopy, receiving no direct sunlight. Exactly one tree in the whole survey was tall enough to reach the canopy.

Basis: U.S. National Park Service, “American Chestnuts in the Capital Region” (2014 NCRN inventory of eleven parks): “In all, we documented 234 trees.”; “91% were classified as ‘overtopped,’ meaning that the tree’s crown is entirely below the level of the canopy and receives no direct sunlight. Only one tree was tall enough to reach the forest canopy.” USDA Forest Service FS-230: “Its ability to sprout vigorously from the stump has helped chestnut to exist in spite of continued attack by the fungus blight, which persists in living stumps and eventually kills the sprouts.”

To feel the size of the hole, count the things that used to be made of chestnut. “In 1908 telephone, telegraph, and electric-power companies purchased 516,000 chestnut poles. The number rose to 808,000 in 1928. This was more than 25 percent of the total of all poles purchased in that year.” Railroads bought “approximately 8 million chestnut crossties” in 1908; by 1931 the number was “only 115,000.” The wood was also the country’s main source of tannin for turning hides into leather — “before its near extinction, it was the primary source of tannin for the leather industry” — and it resisted rot as well as “cedars, cypress, and redwood.” One fungus, and an entire building material walked out of the economy.

Basis: USDA Forest Service, “American Chestnut … an American wood” (FS-230), sections on production and principal uses. The pole, crosstie, tannin and decay-resistance sentences are quoted from that publication.