Geoscience Reference
In-Depth Information
ATLANTIC WHITE CEDAR
The Dismal Swamp was a name given in colonial days to Atlantic white cedar habitat that included 404,000
undrained hectares (998,000 acres) between the James River in southeastern Virginia and the Albemarle Sound
in North Carolina. Today the Great Dismal Swamp National Wildlife Refuge, established in 1973, occupies a
43,000-hectare (106,000-acre) remnant of the former swamp. Cedar stands in the refuge support some of the
greatest bird densities found in coniferous forests in the eastern United States, holding nearly twice as many
birds as an equal area in the surrounding red maple- black tupelo forest.
Parulid warblers are the dominant bird life in the Great Dismal cedar stands: prairie, prothonotory, hooded
and worm-eating warblers, ovenbirds, and yellowthroats account for three-fourths of the breeding birds. Prairie
and worm-eating warblers appear to be particularly dependent on the Great Dismal cedars. Cedar also seems to
be a particularly important food source and habitat for wintering birds. On one occasion, ten thousand pine sis-
kin were observed feeding in a single Great Dismal stand—the largest such gathering ever reported.
In the northeast, Atlantic white cedar is the preferred browse of white-tailed deer. Cottontail rabbit and
meadow mouse also feed on cedar seedlings.
Green Monster: The Boreal Forest
The boreal forest has been compared to a green shawl draped over the shoulders of the continent. In fact, this
great northern coniferous biome mantles the globe. Circumpolar in extent, it is constrained in the north by the
treeless tundra and in the south by the temperate deciduous forest. It is vast, covering roughly 28 percent of the
North American continent, stretching from Alaska to Labrador, where it crosses the water onto the island of
Newfoundland. In Russia it is called the taiga, and its vastness was perhaps best captured by the great Russian
playwright Anton Chekhov when he made an expedition across Siberia on horseback: “The strength and charm
of Siberia does not lie in its giant trees and its silence, like that of a tomb, but in that only migratory birds
know where it finishes. On the first day one does not take any notice of the taiga; on the second and third day
one begins to wonder, but on the fourth and fifth day one experiences a mood as if one would never get out of
this green monster.”
Despite the vast extent of the boreal forest, its flora is marked by simplicity. The overall impression of a
boreal forest—say, looking down on it from a plane—is one of conformity. The few hardy trees of the “north
woods” are the ones adapted to survive the harshness of a boreal winter. In a square mile of forest there might
only be one or two species of trees, compared with hundreds in the same area of tropical rain forest. But those
trees, unlike their tropical counterparts, can occupy a wide range of habitats—they are not adapted to fit a par-
ticular environmental niche.
The boreal forest is dominated by four genera of conifers, namely, Picea (spruce), Pinus (pine), Larix
(tamarack or larch), and Abies (fir), with a few species of deciduous trees mixed in, especially Populus (pop-
lars and aspen) and Betula (birch). The proportions and dominance of these players vary across the vast boreal
region that borders the Atlantic, reaching as it does from northern Labrador to Maritime Canada and northern
