Geoscience Reference
In-Depth Information
tal winter food for these small mammals. But white-tailed deer also consume large quantities of acorns to build
up fat reserves for winter, depriving other wildlife of this food source.
Mature white oaks typically produce ten thousand acorns a year, but they produce bumper crops—as many
as sixty thousand—every four to ten years. Such a strategy seems intended to overwhelm the seed predators,
improving the chances that some of the acorns will germinate and sprout, but the trigger for this strategy re-
mains a mystery. Although animals can hinder oak regeneration when they consume too many acorns, they are
also responsible for their dispersal.
Gray squirrels and eastern chipmunks bury acorns in leaf litter—a behavior called scatter hoarding—where
many are likely never recovered and some germinate successfully. Blue jays also scatter hoard acorns, and it is
believed that the blue jay was responsible for the rapid spread of oaks in eastern North America following the
retreat of the glaciers at the end of the Pleistocene.
CATASTROPHIC DISTURBANCES TO
New England forests from blowdowns and fire occur relatively infre-
quently, at intervals of about 1,150 and 800 years, respectively. Major storms such as the hurricane of 1938
and the ice storm of 1998 occur more frequently, on average every 150 years. Although they destroy mature
trees, such storms do not appear to have much impact on the successional trends or overall species composi-
tion, since New England's pioneer species are resilient and survive in the understory.
Native Americans in southern New England used fire more frequently than those in northern New England
to clear fields for planting, open the forest for easier travel, and drive game for hunting. Indians raised corn,
beans, squash, pumpkins, and tobacco, moving their fields every eight to ten years when fertility declined.
Beaver meadows, periodic fires on dry sites, and this pattern of shifting native agriculture maintained an open
landscape along many of the major rivers as well as the coast. Burning usually occurred in the spring and fall
and produced parklike woodlands with a rich herbaceous growth on the forest floor. In turn, this habitat en-
couraged an abundance of such game animals as deer, turkey, rabbit, and partridge.
By 1860, three-quarters of the arable land in southern and central New England had been cleared for pasture
and farm crops. These lands began to be abandoned as early as 1825, however, when the Erie Canal opened ac-
cess to the rich farmlands of Ohio and people began following the frontier west. In fact, nowhere else in the
world was such a large area of land cleared and then suddenly deserted as in New England. Today, the situ-
ation is a complete reversal of what it was a century ago; 65 percent of southern New England and fully 90
percent of the northern region is now forested.
Consequently, it is the grassland and shrubland species of birds— bobolinks, grasshopper sparrows, and
yellow-breasted chats—that have shown the most dramatic declines in recent decades. Bobolinks, for example,
require large expanses of grassland or old hayfields with a high level of litter cover and broad-leafed weeds in
which to hide their nests. The loss of agricultural land to development and the change to earlier and more fre-
quent mowing have contributed to the bobolink's decline in the Northeast. At the same time, resident forest
birds such as the dramatic pileated woodpecker, which requires trees 50 centimeters (20 inches) in diameter in
which to nest and roost, have significantly increased in numbers.
