Welcome to an overview of what Economic Botany has to offer.
It will be a distance learning course this spring 2000, so below are highlights of what I plan
to be doing in the TopClass format
LECTURE 9 HIGHLIGHTS FOR BIOLOGY 03074, ECONOMIC BOTANY:
(NORTHERN AND TEMPERATE) FORESTS AND FOREST ISSUES
Text: 2nd ed.: Ch. 18 (pp. 298-308); 1st. ed.: Ch. 18 (pp. 273-282)
possible web site: http://www.sierraclub.org/forests/
(Sierra Club's view on forest activities--probably not the same as Rush Limbaugh's!)
FOREST ECOLOGY
Biome: a large, terrestial ecosystem characterized by particular forms of vegetation. The locations of these biomes are determined by climate, especially temperature and precipitation.
Taiga: the boreal forest, short-growing season, mineral-poor soil, and many conifers, with spruces (white and black) and firs (balsam) predominating in Canada. Conifers ("cone-bearing") are gymnosperms, with separate male and female cones (strobili).
Pinaceae, the pine family: trees with persistent leaves that are spirally arranged on shoots or spurs. Pinus, pine; Picea, spruce; Tsuga, hemlock. Major identifying characters of above:
pines: longer needles in clusters of 2 to 5
spruces: single needles all around branch, up to 2" long, with woody base
hemlocks: flattened needles on sides of branch
Temperate forest: We are most familiar with the temperate deciduous forest that you can see on the HVCC nature walk, with its moderate precipitation, warm summers, and cold winters. Typical aspects of the temperature deciduous forest include a rich soil with distinctive layers of topsoil with organic matter and a lower, clay-rich level. As the name implies, these forests are dominated by hardwoods that shed their leaves in the fall.
FOREST PRODUCTS
Wood and wood products are of major importance to society. Derived items include construction materials, furniture, paper, fuel, and synthetic materials based on cellulose, e.g., rayon and cellophane.
Wood: secondary xylem, with strength and durability stemming from cellulose and lignin.
hardwood: wood from angiosperm (flowering) trees.
softwood: wood from gymnosperm trees.
In general, angiosperm wood denser than gymnosperm wood, as a reflection of the increased amount of lignin.
Rings of secondary xylem develop each growing season. Centermost region of secondary xylem is the heartwood, usually stained with tannins and resins (so support, not transport). In contrast, the superficial, conductive sapwood is usually wet. Woods demonstrate different grains. Knots are the bases of branches covered over by subsequent lateral growth of the tree trunk.
USA and Canada are leading lumber-producing countries. Pine is often used in house construction, as it is light but strong. P. strobus was the most important timber tree in US until 1900s, when white pine blister rust introduced. In the US, oaks are the most economically important hardwoods.
A veneer is over a less expensive wood, e.g., black walnut, mahogany, teak.
Plywood: three or more layers of thick veneers glued together at right angles.
Wood pulp: watery suspension of pulverized wood. In industrialized world, about half of harvested wood turned into pulp with most of that for paper. The idea here is to separate lignin from the wood to create a cellulose product. Paper: USA uses 1/3 of the wood harvest for paper and cardboard
FOREST HARVESTING ISSUES
Deforestation: destruction of all tree cover in an area. Deforestation is not a new phenomenon, with loss of trees having a major impact on early civilizations, e.g., Mesopotamia, Indus River Valley, Greece (olive trees planted to grow on the badly eroded, rocky soil). 1/3 of the world land surface covered by forests, with up to 1/2 of that destroyed by human activity. Overall, there is little replanting and thoughtful management of overall forest resources being done. Sustainable approaches to forestry include leaving enough ecosystem intact for a semblance of the forest to continue, not just perform large patches of clear-cutting.
FOREST FIRES
Fire needs to be included as an evolutionary force in the development of communities, with lightning as the major cause of natural fires. Fire dominates the history of the forests, grasslands, and chaparral communities.
ACID RAIN AND OTHER POLLUTION
A major effect on forests, particularly in the Adirondacks, is from acid rain, or precipitation of pH < 5.7. Sulfur and nitrogen oxides are converted into sulfuric and nitric acids that can precipitate down and adversely affect trees.
|main page| |background| |03028: Physiology| |03048: Anatomy|
|03050: Invertebrate Zoology| |03051: Vertebrate Zoology| |03074: Economic Botany|
Please send comments and questions to: cronewil@hvcc.edu
Copyright 1999 by Wilson Crone
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This page updated on October 4, 1999