IN environmental parlance, the ecotone is the zone where two habitats merge, that threshold where water meets the shore, where the forest comes to meadow, or where woodland ends at a cultivated lawn. It is the edge habitat where everything — soil content, vegetation, moisture, humidity, light, pollination — changes. It’s also where species from both sides converge, rendering it a place of complex interaction and diversity.

All of which makes it a good place to work. My small office here in the Hudson Valley of New York is situated at the edge of our yard, where the woods of oak, maples and hickories meet the brambles, the rye grass and timothy. Things are always happening here: White-tailed deer wander out from the woods foraging for something to eat, and wild turkeys often parade through the long grass. Once, at dusk, I saw a coyote slipping through the trees, and for a few brief moments two winters ago, a small gray bobcat. And one morning last summer I was astonished to see a black bear amble out from the trees.

The view from my window is of a place of constant change and unexpected appearances. Such a landscape can be helpful when you’re trying to distill a nebulous idea into a handful of words. It could be nothing more than a ring-necked pheasant pecking at the dry leaves, its iridescent green feathers picking up the glint of afternoon light, but a glance outdoors is enough to remind me of the intensity and complexity in these places of transition, where one thing manages to become another.

Aldo Leopold, forester, writer and dean of American wildlife conservation, articulated the idea of the edge effect in his 1933 classic, “Game Management.” Observing how different species search out different peripheries, he wrote that the grouse hunter looks to the edges of the woods “with its grape tangles, haw-bushes, and little grassy bays,” while the quail hunter “follows the common edge between the brushy draw and the weedy corn,” and the deer hunter “the edge between the oaks of the south slope and the pine thicket of the north slope.”