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AP Environmental Science Ch 12 Notes

AP Environmental Science Ch 12 Notes. 2013-2014. Public-service functions of forests include. Retarding erosion and moderating the availability of water, which improves the water supply from major watersheds to cities Serving as habitats for endangered species and other wildlife

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AP Environmental Science Ch 12 Notes

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  1. AP Environmental Science Ch 12 Notes 2013-2014

  2. Public-service functions of forests include • Retarding erosion and moderating the availability of water, which improves the water supply from major watersheds to cities • Serving as habitats for endangered species and other wildlife • Recreation • Climate regulation (surface color, transpiration/evaporation which reduces erosion, rate of greenhouse gas release, wind speed)

  3. Tree Terms • Silvicultureis the professional growing of trees • A stand of trees is a group of trees of the same species or group of species and often at the same successional age (can measure up to several hundred hectares; 1 hectare = 10,000 square meters) • Even-aged stands (germinated the same year) • Uneven-aged stands (at least three distinct age classes) • An old-growth forest is a forest that has never been cut, while a forest that has been cut and has regrown is called a second-growth forest

  4. Tree Terms • A plantation is a stand of a single species, typically planted in straight rows • Sometimes fertilized by helicopter • Require intensive management (if the previous point didn’t convince you) • Rotation time is the time between cuts of a stand

  5. Tree Terms • Harvesting • Clear-cutting • Selective cutting: individual trees are marked and cut • Thinning: smaller, poorly-formed trees are selectively removed • Strip-cutting: narrow rows of forest are cut, leaving the rest intact • Shelterwood cutting: cutting dead/less desirable trees first, and later cutting mature trees • Seed-tree cutting: removes all but a few seed trees to promote regeneration of forest

  6. Modern Conflicts over Forestland and Forest Resources • The Players • Industrial forest companies: own forestland, harvest timber, plan how to do it; hire professional foresters; support sound management of forests • Environmental groups: what it sounds like; sometimes criticize industrial forest companies but share commitment to management of forests • Timber investment management organizations (TIMOs): financial investors who view forestland as an opportunity to profit by buying and selling timber (in other words, they view it as a commercial commodity). There is a danger that TIMOs will abandon forests once they have been used up

  7. Modern Conflicts over Forestland and Forest Resources • The Conflicts • Commodity vs. Conservation vs. Compromise • Sustainable management • Role in global environment/climate • Endangered species • Water supply

  8. Modern Conflicts over Forestland and Forest Resources • Forests can be certified as “sustainable” but it’s uncertain whether the qualifications for it indicate true sustainability

  9. There are approximately 15 million square miles of forest on Earth. Ten nations have ⅔ of this (Russia, Brazil, Canada, U.S., China, Australia, Democratic Republic of the Congo, Congo, Indonesia, Angola, Peru, in descending order)

  10. World trade in timber does not appear to have grown much, if at all, over the last few decades. • About 63% of all wood produced in the world is used for firewood; this accounts for 5% of the world’s total energy use. • The annual rate of deforestation across the world is estimated at 7.3 million hectares a year (lower than the rate from the 1990’s).

  11. Tree Niches • Water content of soil • Shade tolerance (related to succession)

  12. Wilderness • Wildernessis an area undisturbed by people, with the exception of visitors • According to the US Wilderness Act of 1964, wilderness has the following qualities • the imprint of human work is unnoticeable • there are opportunities for solitude and for primitive and unconfined recreation • there are at least 5000 acres

  13. Wilderness • Countries with a significant amount of wilderness include New Zealand, Canada, Sweden, Norway, Finland, Russia, Australia, Antarctica, Greenland, and Iceland. This is not an exhaustive list. • Many countries have no wilderness left to preserve; Switzerland is an example of a country in which wilderness is not preserved

  14. Forest Fires and Prescribed Burns APES 2013-2014

  15. Ecosystem services of forests • Removal of carbon/release of oxygen • Food for humans (ex. Deer, nuts, fungi) • Provide habitats for many species • Wood (fuel, material) • Others from previous notes

  16. Three types of forest fires • A brush fire spreads along low-lying vegetation, moss and lichen, while trees remain unaffected. Travel at 1-3 meters per minute. • A crown fire burns the crowns of trees and tall shrubs. Travels at 3-100 meters per minute. • A mild peat fire can start at depths of ~25 cm, while a massive one will burn at a depth of over 50 cm.

  17. Ecological consequences of forest fires • Fluorosurfactantsare widely used for smothering forest fires. The chemicals are harmful for the environment, causing irreversible genetic mutations of animals and destroying the ozone layer.

  18. Ecological consequences of forest fires continued • The burning of one hectare of forest releases 10-12 tons of carbon monoxide, sulfur oxides, and nitrogen oxides into the atmosphere. • The most vulnerable trees in fire are oak, linden, ash, and spruce.

  19. Fire suppression • Long-term fire suppression leads to a number of risk factors for forests. • accumulation of combustible material (increase in understory growth, larger trees, increase in tree density) • increase in ratio of fire-intolerant to fire-tolerant species

  20. Prescribed Burns • Prescribed burning can be defined as the thoughtful and skillful application of fire to a specific site under selected weather conditions to accomplish specific land management objectives.

  21. Purposes of a prescribed burn • reduces the invasion of woody growth in grassland habitats • reduces the accumulation of hazardous fuel loads • boosts pasture productivity by releasing nutrients bound to dead organic material

  22. Prescribed burning has been used as a tool throughout history • Native Americans used fire to maintain clearings and encourage the growth of plants for later harvest. • Farmers have used fire to revitalize pasture, aid in crop harvest, and maintain fencerows and ditch banks. • Prescribed burning can be a very useful, cost-effective and safe tool when properly planned and implemented.

  23. Prescribed burns vs wildfires • Prescribed burns differ greatly from wildfires. • Wildfires are accidental and uncontrolled. They threaten lives and property and can do great harm. • Prescribed burns, on the other hand, are set intentionally after considering the safety of people and property. They are controlled to limit unwanted damage.

  24. Benefits of prescribed burns • Clearing of forest floor, which removes combustible material and decreases likelihood of wildfire • Creation of nutrient-rich ash • Promotes growth of fire-tolerant and fire-dependent species • Releases less air pollution than a wildfire

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