Page 694 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

658 part IV Soils, Ecosystems, and Biomes
of old-growth forest habitat as the primary cause for its decline. The next year, logging practices in areas with spotted owl habitat were halted by court order. The en- suing controversy pitted conservationists against log- gers and other forest users, with the end result being large-scale changes in forest management throughout the Pacific Northwest. The Canadian spotted owl popu- lation was declared endangered by the Committee on the Status of Endangered Wildlife in Canada under the 2002 Species at Risk Act.
Later research by the U.S. Forest Service and inde- pendent scientists noted the failing health of temper- ate rain forests and suggested that timber-management plans balance resource use with ecosystem preservation. Sustainable forestry practices emphasize the continuing health and productivity of forests into the future and are increasingly based on a multi-use ethic that serves local, national, and global interests.
The tallest trees in the world occur in this biome—the coast redwoods (Sequoia sempervirens) of the California and Oregon coasts. These trees can exceed 1500 years in
age and typically range in height from 60 to 90 m, with some exceeding 100 m. Virgin stands of other representa- tive trees, such as Douglas fir, spruce, cedar, and hemlock, have been reduced by timber harvests to a few remaining valleys in Oregon and Washington, less than 10% of the original forest that existed when Europeans first arrived. Most forests in this biome are secondary-growth forests, which have regrown from a major disturbance, usually human-caused. In similar forests in Chile, large-scale timber harvests and new mills began operations in 2000. Currently, U.S. corporations are shifting their logging op- erations to these forests, many of which are located in the Chilean Lake District and northern Patagonia.
The opposing sides in this conflict between log- ging and society interests should combine their efforts in a sustainable forestry model, as was done for the boreal forest (cpaws.org/news/cpaws-proud-partner-in-new- boreal-forest-leadership-agreement, and specific to Canada, see canadianborealforestagreement.ca/).
Mediterranean Shrubland
The Mediterranean shrubland biome, also referred to as a temperate shru- bland, occupies temperate regions that have dry summers, generally corresponding to the Mediterranean climates. The dominant shrub for- mations that occupy these regions are low growing and able to with- stand hot-summer drought. The veg- etation is sclerophyllous (from sclero, for “hard,” and phyllos, for “leaf”). Most shrubs average a metre or two in height, with deep, well-developed roots, leathery leaves, and uneven low branches.
Typically, the vegetation varies between woody shrubs covering more than 50% of the ground and grassy woodlands covering 25%–60% of the ground. In California, the Spanish
word chaparro for “scrubby evergreen” gives us the name chaparral for this vegetation type (Figure 20.16a). This scrubland includes species such as manzanita, toyon, red bud, ceanothus, mountain mahogany, blue and live oaks, and the dreaded poison oak.
This biome is located poleward of the shifting sub- tropical high-pressure cells in both hemispheres. The stable high pressure produces the characteristic dry- summer climate and establishes conditions conducive to fire. The vegetation is adapted for rapid recovery after fire—many species are able to resprout from roots or burls after a burn, or have seeds that require fire for ger- mination (Figure 20.16b).
A counterpart to the California chaparral in North America is the maquis of the Mediterranean region of Europe, which includes live and cork oak trees (the source of cork) as well as pine and olive trees. In Chile,
(a) Chaparral vegetation, southern California.
(b) Fire-adapted chaparral sends out sprouts from roots, a few months after a wildfire in the San Jacinto Mountains, southern California.
▲Figure 20.16 Mediterranean chaparral and fire adaptations. [Bobbé Christopherson.]