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近似文章 Saving a Forgotten forests
The longleaf pine
Found only in the Deep South of America, longleaf pine
woodlands have dwindled to about 3percent of their former range,
but new efforts are under way to restore them.
A The beauty and the biodiversity of the longleaf pine forest are
well-kept secrets, even in its native South. Yet it is among the richest
ecosystems in North America, rivaling tallgrass prairies and the
ancient forests of the Pacific Northwest in the number of species it
shelters. And like those two other disappearing wildlife habitats,
longleaf is also critically endangered.
B In longleaf pine forests, trees grow widely scattered, creating
an open, park like environment, more like a savanna than a forest.
The trees are not so dense as to block the sun. This openness
creates a forest floor that is among the most diverse in the world,
where plants such as many-flowered grass pinks, trumpet pitcher
plants, Venus flytraps, lavender ladies and pineland bog-buttons
grow. As many as 50different species of wildflowers, shrubs, grasses
and ferns have been cataloged in just a single square meter.
C Once, nearly 92 million acres of longleaf forest flourished
from Virginia to Texas, the only place in the world where it is found.
By the turn of the 21st century, however, virtually all of it had been
logged, paved or farmed into oblivion. Only about 3 percent of the
original range still supports longleaf forest, and only about 10,000
acres of that is uncut old-growth—the rest is forest that has regrown
after cutting.
D Figuring out how to bring back the piney woods also will
allow biologists to help the plants and animals that depend on this
habitat. Nearly two-thirds of the declining, threatened or endangered
species in the southeastern United States are associated with
longleaf. The outright destruction of longleaf is only part of their story,
says Mark Danaher, the biologist for South Carolina’s Francis Marion
National Forest. He says the demise of these animals and plants also
is tied to a lack of fire, which once swept through the southern forests
on a regular basis. "Fire is absolutely critical for this ecosystem and
for the species that depend on it," says Danaher.
E Name just about any species that occurs in longleaf and you
can find a connection to fire. Bachman’s sparrow is a secretive bird
with a beautiful song that echoes across the longleaf flatwoods. It
tucks its nest on the ground beneath dumps of wiregrass and little
bluestem in the open under- story. But once fire has been absent for
several years, and a tangle of shrubs starts to grow, the sparrows
disappear. Gopher tortoises, the only native land tortoises east of the
Mississippi, are also abundant in longleaf. A keystone species for
these forests, its burrows provide homes and safety to more than 300
species of vertebrates and invertebrates ranging from eastern
diamond- back rattlesnakes to gopher frogs. If fire is suppressed,
however, the tortoises are choked out. "If we lose fire," says Bob
Mitchell, an ecologist at the Jones Center, "we lose wildlife.’
F Without fire, we also lose longleaf. Fire knocks back the oaks
and other hardwoods that can grow up to overwhelm longleaf forests.
"They are fire forests," Mitchell says. "They evolved in the lightning
capital of the eastern United States." And it wasn’t only lightning
strikes that set the forest aflame. “Native Americans also lit fires to
keep the forest open," Mitchell says. “So did the early pioneers. They
helped create the longleaf pine forests that we know today."
G Fire also changes how nutrients flow throughout longleaf
ecosystems, in ways we are just beginning to understand. For
example, researchers have discovered that frequent fires provide
extra calcium, which is critical for egg prod uction, to endangered
red-cockaded woodpeckers. Frances James, a retired avian
ecologist from Florida State University, has studied these small
black- and-white birds for more than two decades in Florida’s
sorawling Apalachicola National Forest. When she realised female
woodpeckers laid larger clutches in the first breeding season after
their territories were burned, she and her colleagues went searching
for answers. "We learned calcium is stashed away in woody shrubs
when the forest is not burned," James says. "But when there is a fire,
a pulse of calcium moves down into the soil and up into the longleaf."
Eventually, this calcium makes its way up the food chain to a
tree-dwelling species of ant, which is the red- cockaded’s favorite
food. The result: more calcium for the birds, which leads to more
eggs, more young and more woodpeckers.
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H Today, fire is used as a vital management tool for preserving
both longleaf and its wildlife. Most of these fires are prescribed burns,
deliberately set with a drip torch. Although the public often opposes
any type of fire—and the smoke that goes with it—these frequent,
low-intensity bums reduce the risk of catastrophic conflagrations.
"Forests are going to bum," says Amadou Diop, NWF’s southern
forests restoration manager. "It’s just a question of when. With
prescribed bums, we can pick the time and the place."
Restoring longleaf is not an easy task. The herbaceous
layer—the understory of wiregrasses and other plants, also needs to
be re-created. In areas where the land has not been chewed up by
farming, but converted to loblolly or slash pine plantations, the seed
bank of the longleaf forest usually remains viable beneath the soil. In
time, this original vegetation can be coaxed back. Where agriculture
has destroyed the seeds, however, wiregrass must be replanted.
Right now, the expense is prohibitive, but researchers are searching
for low-cost solutions.
J Bringing back longleaf is not for the short-sighted, however.
Few of us will be alive when the pines being planted today become
mature forests in 70 to 80 years. But that is not stopping longleaf
enthusiasts. "Today, it’s getting hard to find longleaf seedlings to
buy," one of the private landowners says. “Everyone wants them.
Longleaf is in a resurgence."
Questions 1-6
Choose NO MORE THAN TWO WORDS from the passage for
each answer.
Write your answers in boxes 1-5 on your answer sheet.
Forest fire ensures that:
it help the Birds locate their 1____ in the ground.
The burrows of a species of 2_____ provide homes to many
other animals. Hardwoods such as 3_____ don’t take over.
Apart from fires lit by 4____.
Fires are created by 5____ and European settlers.
Fires deliberately lit are called 6____
Question 7-9
Complete the flow-chart below.
Choose ONE WORD ONLY from the passage for each answer.
Write your answers in boxes 6-9 on your answer sheet.
How to increase the number of cockaded woodpeckers Calcium
stored in shrubs
↓
Shrubs are burned
Calcium released into 7......
And travel up to the leaves
↓
8....... are eaten
↓
Number of 9...... increases
↓
More cockaded woodpeckers
Questions 10-13
Do the following statements agree with the information given in
Reading Passage 1?
In boxes 10-13 on your answer sheet, write
TRUE
if the statement agrees with the information
FALSE
if the statement contradicts the information
NOT GIVEN
if there is no information on this
10 The sparse distribution of longleaf pine trees leads to the
most diversity of species.
11 It is easier to restore forests converted to farms than forests
converted to plantations.
12 The technology in recreating the herbaceous layer will phase
out in near future due to the high cost
13 Few people in this restoration program will see the replanted
forest reach its maturity.
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