Everything about The Pacific Temperate Rain Forests totally explained
The
Pacific temperate rain forests of
North America are the largest
temperate rain forest zone on the planet. The Pacific temperate
rain forests lie on west-facing
coastal mountains along the Pacific coast of
North America — the
Pacific Northwest — from
Kodiak Island in
Alaska through
Canada to
Northern California, and are part of the
Nearctic ecozone. The Pacific temperate rain forests are characterized by a high amount of rainfall, in some areas more than 300 cm (120 inches) per year and moderate temperatures in both the summer and winter months (between 10-24°C).
These rain forests occur in a number of
ecoregions, which vary in their species composition, but are predominantly of
conifers, sometimes with an understory of
broadleaf trees and
shrubs. Pacific Temperate rain forests can be found in the
Northern Pacific coastal forests,
Queen Charlotte Islands,
British Columbia mainland coastal forests,
Central Pacific coastal forests,
Central and Southern Cascades forests,
Klamath-Siskiyou forests, and
Northern California coastal forests ecoregions.
The forests in the north contain predominantly
Sitka Spruce and
Western Hemlock, while those in the coastal forests are home as well to
Coast Redwood (Sequoia sempervirens),
Coast Douglas-fir (Pseudotsuga menziesii),
Western Redcedar and
Shore Pine. Notably, the three tallest species of trees are found here. Dense growths of
epiphytes and
mosses cover the trees, and lush vegetation is present everywhere.
History
About 200 million years ago (during the
Triassic and
Jurassic periods), the landscape was dominated by
conifers, which were the most diverse group of trees and constituted the greatest majority of large trees. When
flowering plants emerged (in the following
Cretaceous period), they quickly prevailed, causing most conifers to become extinct, and those that survived to adapt to harsh conditions. Perhaps the most significant difference in this change is that the primitive conifers invested their energy in the basic food supply for every seed, with no certainty of fertilization; by contrast, flowering plants create the food supply for a seed only after it's triggered by fertilization. The Pacific temperate rain forest now remains the only region on Earth of noteworthy size and significance where, due to unique climatic conditions, the conifers flourish as they did before being displaced by flowering plants (Davis 2000).
The northern Pacific temperate rain forests are relatively young, emerging in the past few thousand years following the retreat of the
ice sheets of the last
ice age (Davis 2000).
Ecology
The ecosystem of Pacific temperate rain forests is so productive that the
biomass in the best sites is at least four times greater than that of any comparable area in the
tropics (Davis 2000). In sheer mass of living and decaying material - trees, mosses, shrubs, and soil - these forests are more massive than any other ecosystem on the planet. In part, this is due to the rarity of fire. Unlike drier forests, which burn periodically, temperate rain forests are naturally subject to only small-scale disturbances, such as blow-downs and avalanches.
This rain forest spans a wide range of latitude - from about 40 degrees north to about 60 degrees north. The differences in climate from south to north create several major forest zones, characterized by different species.
- At the southern limit in northern California is the "coast redwood zone".
- Beginning at the California/Oregon border, and extending through the north end of Vancouver Island is the "seasonal rain forest zone". The major tree species here are Douglas fir, western red cedar, Sitka spruce, and western hemlock.
- Beyond the northern end of Vancouver Island, we pass into the "perhumid rain forest zone". Douglas fir wanes as a dominant species, and the forest is primarily made up of western red cedar, Sitka spruce, and western hemlock.
- The Gulf of Alaska begins where the fjords of southeast Alaska end, and marks the transition into "sub-polar rain forest". Here the forest occupies only a very narrow strip between the ocean and the icy alpine zone. The cedar trees no longer thrive in this harsher climate, and the dominant trees are limited to Sitka spruce, and western and mountain hemlock.
- The northern limits of the rain forest are scattered in thin bands in the Kenai Fjords, eastern Kodiak Island, and western Cook Inlet.
Wildlife
The first survey to systematically explore the
forest canopy in the
Carmanah Valley of
Vancouver Island yielded 15,000 new species, a third of all
invertebrates known to exist in all of
Canada. Among the collection were 500 species previously unknown to science (Davis 2000).
The rain forest exists in a complicated landscape of islands and fjords, and many species depend on both the forest and the ocean.
Salmon are one of the primary species of the rainforest, spawning in the forest streams, and fertilizing the land. The
marbled murrelet nests in old growth trees at night, but feeds in the ocean during the day.
Many of the most iconic photos of these forests include a large bear somewhere in the frame.
Grizzly bears and
black bears once thrived throughout the rain forest zone and beyond. Black bears can still be found throughout the forest's range, while grizzlies are largely confined to areas north of the Canadian border. These forests have some of the largest concentrations of grizzly bears in the world, mainly due to the region's rich salmon streams. The
Great Bear Rainforest in Canada is home to the rare white variant of the black bear known as the "spirit bear". The endangered
spotted owl was at the center of logging controversies in Oregon and Washington. Other wildlife species of note include the
bald eagle,
marbled murrelet,
wolf, and
sitka deer.
Logging
Pacific temperate rain forests have been subject to ongoing large-scale industrial
logging since the end of the
Second World War, cutting over half of their total area. In California, only 4% of the redwoods have been protected. In
Oregon and
Washington, less than 10% of original coastal rain forest remains.
And an even larger percentage of the productive forest has been logged. Much of the land is rock, ice, muskeg, or less productive forest on steep slopes. The stereotypical old growth is limited to lowland flats and valleys, which have been preferentially targeted for logging. Historically, the most common protocol has been to place protected areas in the mountains, leaving the valleys to the timber industry. So while some very large areas are protected as parks and monuments, very little of the highest-value habitat has been protected. Much of it has already been cut.
In the
Tongass National Forest, in the 1950s, in part to aid in Japanese recovery from WWII, the Forest Service set up long term contracts with two pulp mills: the Ketchikan Pulp Company and the Alaska Pulp Company. These contracts were for 50 years, and divided up the forest into areas slated for APC logs and areas slated for KPC logs. These two companies conspired to drive log prices down, conspired to drive smaller logging operations out of business, and were major and recalcitrant polluters of their local areas. These long term contracts guaranteed low prices to the pulp companies — in some cases resulting in trees being given away for less than the price of a hamburger. Since 1980, the forest service has lost over a billion dollars in Tongass timber sales.
Half a million acres (2,000 km²) of the Tongass was selected by native corporations under the 1971
Alaska Native Claims Settlement Act. Most of this area has been clearcut.
The most controversial timber sales in the Tongass are in the roadless areas. In September 2006, a landmark court decision overturned Bush's repeal of the
Roadless Rule, reverting to the 2001 roadless area protections established under Clinton. However, the Tongass was exempted from that ruling, and it's unclear what the fate of its vast roadless areas will be.
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