Environmental Engineering Reference
In-Depth Information
Forestry
The challenge of forestry is to balance humans' use of wood products with the importance of forests as ecosys-
tems. Wood is used as fuel and provides the chief material for many products, including furniture, paper, pack-
aging, and homes. Additionally, the timber industry is a major global resource, and many people depend on the
jobs and income it creates. This necessitates finding a balance between human needs and ecological preserva-
tion.
Tree Plantations
Many timber companies are now planting fast growth species to most efficiently produce timber on land and
maximize economic gain. These timber plantations are monocultural, with only one species being planted at
a time. Since the trees are all planted and then harvested at the same time, they are all the same age, or even-
aged. Once the trees are harvested, new seedlings are planted. Plantation forests have minimal diversity since
the trees are all the same species, which limits the habitat they can provide for other organisms. However, tim-
ber plantations can potentially be used as a restoration strategy for previously degraded land, stimulating sec-
ondary growth.
Old Growth, Secondary Growth
Because of the extensive deforestation that has occurred globally and throughout the United States, many re-
maining forests are considered to be secondary growth. Secondary growth occurs when an original, old-
growth forest is cut down and new growth emerges. Much of the original deforestation in the United States oc-
curred soon after European colonization and subsequent westward movement, during which wood was used for
building and fuel and land was cleared to make room for agriculture and development of homes and towns.
Many of the forests have since been reforested with secondary-growth forests.
Currently deforestation continues on a grand scale in developing countries. The reason for extensive deforesta-
tion in these countries is the resulting economic gain—directly from the timber, from selling the rights for tim-
ber harvesting, or from the use of the land once it is cleared.
The negative consequences of deforestation include the following:
• Loss of species and biodiversity
• Release of excess carbon into the atmosphere, contributing to climate change
• Reduced conversion of carbon dioxide into oxygen in the process of photosynthesis
• Erosion of unprotected soils
• Depletion of soil nutrients
• Increased desertification
• Flow of effects through an ecosystem
Forest Fires
Forest fires are certainly destructive and can be dangerous, but they are also a necessary part of the forest eco-
system. Many ecosystems depend on fires to help seeds germinate and to return nutrients to the soil. For ex-
ample, in a chaparral ecosystem, fire's extreme heat causes some species' seeds to open. Periodic fires also help
to thin the underbrush in an ecosystem. Small fires that burn branches, twigs, and dead trees help to reduce a
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