Environmental Engineering Reference
In-Depth Information
growing cities up and down the coast. Settlers used fi re
to clear away unwanted forests in interior valleys to
establish farms. They introduced cattle and a large
number of weedy grasses and forbs. The absence of
Indian - set fi res allowed brush to overtake some for-
merly open savannas and woodlands. Others were
kept open, but plant composition was altered from
heavy grazing. Millions of sheep were herded across
open, unclaimed land to distant markets, and nearly
every high meadow was grazed, sometimes down to
bare earth. This led to substantial soil
erosion
in
some areas.
and establishing a fi re patrol system (USFS 1948).
The Great Depression of the 1930s resulted in a large
infl ux of funding and labour, allowing the US Forest
Service to build major recreation facilities like Tim-
berline Lodge on Mount Hood in Oregon, as well as
campgrounds and trails. But timber management
remained a small part of the programme (Bergoffen
1976 ; Steen 2004 ).
This changed during and immediately after the
Second World War. By then, private forests had been
heavily exploited, and the post-war suburban con-
struction boom exponentially increased demand for
timber. The USFS had planned for this moment, and
shifted quickly into a new role as a provider of timber.
This change also happened in Canada, though at a
slower pace due to the much lower level of population
and construction relative to the amount of forest
available.
Forest land cover in the western states has been
remarkably stable since Euro-American settlement.
Rocky Mountain Forests still cover 26% of the total
land area, whereas they once covered 28%. In the
Pacifi c Northwest, 40% of the total land area was for-
ested prior to Euro-American settlement, with the
current amount reduced only to about 37%. But the
nature and condition of these forests have changed
substantially as they have been subjected to
fragmen-
tation
, human-caused and natural
disturbances
,
biological
invasions
, artifi cial fi re exclusion and land
development. There have been shifts from agriculture
to forests and vice versa, while some forest land has
been converted to more intensive uses, such as urban
areas. Since 1991, there has been an increase in the
ratio of forest growth to removal for the Pacifi c coast
and Rocky Mountain regions as a result of decreased
harvesting on public lands and increased tree growth
on timber stands that were regenerated after harvest
during the twentieth century (USFS 2001).
13.3 CONSERVATION AND
RESTORATION POLICIES
Due to rugged terrain or aridity, much of the forest
land of the region was not attractive to settlers. Both
the US and Canadian governments made a series of
decisions that recognized the importance of western
forests for watershed conservation and as eventual
stores of timber that would be needed once private
lowland forests in the east were all gone. In Canada,
forests were held by the Crown, with responsibility for
management eventually turned over to Provincial gov-
ernments. In the United States, the federal government
turned public forest management over to what is now
the US Forest Service (USFS), originally formed as the
Division of Forestry in 1891. It was renamed the
Bureau of Forestry in 1901, and in 1905 it became
the US Department of Agriculture Forest Service
(Steen 2004). The agency was placed under the leader-
ship of Gifford Pinchot, who had studied classical for-
estry in France and Germany, but recognized that the
vast forests of the western United States could not be
managed under the same intensive silviculture para-
digm as then prevailed in Europe. In the fi rst decades
of the twentieth century, there was little demand for
timber from these forests, and no way to get access to
the trees in any case. As a result, the USFS was initially
established as a forest protector, and a key element of
protection was fi re control. This was especially the case
after a major fi re, known as the 'Big Burn', occurred in
western Montana and Idaho in 1910, devastating mil-
lions of hectares of forested land (Pyne 1982).
By the mid-1940s, the USFS had management
responsibility for over 29 million hectares across the
western United States. It was primarily focused on
controlling livestock grazing, building access trails
13.3.1
Pacifi c Northwest forest restoration
Restoration of forests in Cascadia began in the 1990s
as a response to the listing of the Northern spotted owl
(
Stryx occidentalis
) as an
endangered species
. This
species of owl is highly dependent on old-growth forest
conditions, and had been monitored for years as an
indicator of forest conditions (FEMAT 1993). The his-
torical amount of mature or old-growth forest fl uctu-
ated between 25% and 75% of the entire forested area,
