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The Alaska Region occupies the rugged, mountainous coast of
the northeast Pacific Ocean. The maze of fjords and islands,
streams and mountains characterizing the Region support a wide
array of vegetation types ranging from vast wetlands to
luxuriant temperate rainforests to magnificent alpine
ecosystems.
There are about 1,700 types of plants in the Alaskan Tundra.
What most of them have in common are growth characteristics;
they tend to grow low to the ground. The long day length that
accompanies the short summer is a boon to plants, which are able
to photosynthesize 24 hours a day in some places. This leads to
rapid plant growth. Among the common types of tundra plants are
willows, sedges and grasses, many in dwarf forms compared to
their growth forms in warmer climes. Lichens and mosses are also
important, particularly in the harshest climates.
Lichens are specialized fungi that “farm” algae as a food
source. Unlike molds, mildews, and mushrooms that parasitize or
scavenge food from other organisms, the fungus of a lichen
cultivates algae and / or blue-green bacteria (called
cyanobacteria) within the fabric of interwoven fungal threads
that form the body of the lichen. Lichens come in many shapes,
sizes, and colors. A lichen thallus has one of three general
growth forms: foliose, fructose, or crustose. Foliose lichens
are leaf-like with different upper and lower surfaces. Fructose
lichens are hair-like or bushy with no obvious difference
between upper and lower surfaces. Crustose lichens are so
closely attached to a surface, like paint spots, that the lower
surface is not easily observable.
Many of the plants in the Alaska Region produce spectacular
wildflowers and colorful foliage, providing excellent
opportunities to enjoy native plants from spring through autumn. Many native Alaskan plant seeds require 4-6 months of cold stratification. This
is most easily accomplished by sowing the seed into a moist growth medium
such as Pro-Mix in the Fall, and leaving it outside or in a refrigerator. Do not let
the seed dry out.
Blueberry plants are cold hardy and blueberries are a favorite
native bush to grow in Alaska. Blueberry plants are native to
Southern Alaska soils. During the Fall the leaves of the
blueberry plant turn a brilliant scarlet color. Plum trees can
be grown in Alaska, but some winters the plum tree is not as
cold hardy as cherry trees or apple trees.
Glacier Bay is blanketed by a mosaic of plant life, from a few
pioneer species in recently exposed areas to intricately
balanced climax communities in coastal and alpine regions. Since
virtually all the vegetation in the bay has returned to the land
in the past 300 years following the retreat of the glaciers,
this area is one of the premier sites on the planet to study
plant recolonization.
A trip into Glacier Bay mimics glacial retreat and rolls back
plant succession, from the mature forest at Bartlett Cove to the
naked earth structure at the fjords' farthest reaches.
Biological succession produces profound change here in a mere
decade. Earnest, long-range studies of plant succession began in
Glacier Bay in 1916, with the work of Professor William S.
Cooper. His plant studies were continued in 1941 by Professor
Donald Lawrence and others
Plant recovery may begin here with no more than "black
crust", a mostly algal, feltlike nap that stabilizes the silt
and retains water. Moss will begin to add more conspicuous
tufts. Next come scouring rush and fireweed, dryas, alder,
willows, then spruce, and finally hemlock forest. (on the park's
outer coast the final or climax stage of plant succession may be
muskeg, because soil packing causes poor drainage.)
Where plants' seeds happen to land, of course, can be
critical. The chaotic rock-and-rubble aftermath of a glacial
romp is deficient in nitrogen. Alder and dryas are important
pioneers because they improve the soil by adding to it nitrogen
from the air. Much of northern Europe and America were pioneered
by dryas when the last Ice Age ended. Sitka alder eventually
forms dense entanglements that are the bane of hikers. But these
alders also fix nitrogen in their root nodules, and drop leaves
that add valuable nitrogen to the soil. This enables spruce to
take hold and eventually shade out the alder. A forest community
is begun.
Each successive plant community leading up to the climax
community creates new conditions that lead to its replacement by
plants more competitive under those new conditions. The theory
holds that plant competition modifies the environment- light and
moisture availability, and soil nutrients- so that plant
populations also change. Over time, successive plant communities
will occupy the environment, hence plant succession.
The time from naked rock to revegetation is not necessarily
long. A naturalist doing field studies here about 1920 collected
bird specimens of willow ptarmigan so gorged on plump ripe
strawberries that juice ran out of their mouths when they were
held up by their legs.
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