Geoscience Reference
In-Depth Information
(a)
(b)
Figure 10.29 Slash and burn agriculture in the Amazon rainforest.
(a) Subsistence farmer in Brazil setting a fire in a cleared plot.
(b) The forest in this image has been cut and burned to prepare the ground for cultivation. Organic matter from the burned forest temporarily
increases soil fertility.
prior strong link between deforestation and the economy may
be weakening. Although the reasons for this decoupling are
complex, they appear to belated to such factors as improved
satellite monitoring (see Figure 10.28), increased enforcement
of environmental laws, and growing awareness of the Amazon
ecosystems' value, to name a few. It is hoped that this trend
continues.
Although deforestation is often considered a tropical is-
sue, the history of forest management has also been mixed
in the higher latitudes. In the Great Lakes region of North
America, for example, virtually all the native pine forest was
cut in the late 19th and early 20th centuries (Figure 10.30)
to provide timber for buildings in growing cities such as
Chicago, Milwaukee, and St. Louis. The forest in this region
is still heavily managed, with large jack and red pine planta-
tions in many parts of the region that are grown for pulpwood.
A similar history has also transpired in the needle-leaf forests
of the Pacific Northwest. Most of the old-growth forests are
gone in this area, and the second- and third-growth forests
continue to be extensively logged (Figure 10.31). The ongoing
Figure 10.30 Stump prairie in northern Michigan.
These
stumps are the remnants of old-growth pine trees on the Kings-
ton Plains that were cut in the 1890s. Following this period of
deforestation, many dried limb and branch fragments lay on the
ground. This
slash
subsequently burned in a very hot fire that
torched seedlings and essentially cooked the soil. As a result, for-
est has not regenerated over much of the area.
Figure 10.31 Clear cutting in the Pacific Northwest.
Defor-
ested areas on mountain hillslopes south of Olympic National
Park in Washington.
