The Sixth Extinction: An Unnatural History

direction to move in, you have to go south, but you have 360 meridians to
choose from. Perhaps, like me, you live in the Berkshires and are headed
to the Andes, so you decide that you will follow the seventy-third
meridian west. You ski and ski, and finally, about five hundred miles from
the pole, you reach Ellesmere Island. All this time, of course, you will not
have seen a tree or a land plant of any kind, since you are traveling across
the Arctic Ocean. On Ellesmere, you will still not see any trees, at least not
any that are recognizable as such. The only woody plant that grows on
the island is the Arctic willow, which reaches no higher than your ankle.
(The writer Barry Lopez has noted that if you spend much time wandering
around the Arctic, you eventually realize “that you are standing on top of
a forest.”)
As you continue south, you cross the Nares Strait—getting around is
now becoming more complicated, but we’ll leave that aside—then
traverse the westernmost tip of Greenland, cross Baffin Bay, and reach
Baffin Island. On Baffin, there is also nothing that would really qualify as a
tree, though several species of willow can be found, growing in knots
close to the ground. Finally—and you are now roughly two thousand miles
into your journey—you reach the Ungava Peninsula, in northern Quebec.
Still you are north of the treeline, but if you keep walking for another 250
miles or so, you will reach the edge of the boreal forest. Canada’s boreal
forest is huge; it stretches across almost a billion acres and represents
roughly a quarter of all the intact forest that remains on earth. But
diversity in the boreal forest is low. Across Canada’s billion acres of it, you
will find only about twenty species of tree, including black spruce, white
birch, and balsam fir.
Once you enter the United States, tree diversity will begin, slowly, to
tick up. In Vermont, you’ll hit the Eastern Deciduous Forest, which once
covered almost half the country, but today remains only in patches, most
of them second-growth. Vermont has something like fifty species of
native trees, Massachusetts around fifty-five. North Carolina (which lies
slightly to the west of your path) has more than two hundred species.