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2013-2014 AP ENVIRONMENTAL SCIENCE CH 12 NOTES.  Retarding erosion and moderating the availability of water, which improves the water supply from major.

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Presentation on theme: "2013-2014 AP ENVIRONMENTAL SCIENCE CH 12 NOTES.  Retarding erosion and moderating the availability of water, which improves the water supply from major."— Presentation transcript:


2  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) PUBLIC-SERVICE FUNCTIONS OF FORESTS INCLUDE

3  Silviculture is 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 TREE TERMS

4  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 TREE TERMS

5  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 TREE TERMS


7  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 MODERN CONFLICTS OVER FORESTLAND AND FOREST RESOURCES

8  The Conflicts  Commodity vs. Conservation vs. Compromise  Sustainable management  Role in global environment/climate  Endangered species  Water supply MODERN CONFLICTS OVER FORESTLAND AND FOREST RESOURCES

9  Forests can be certified as “sustainable” but it’s uncertain whether the qualifications for it indicate true sustainability MODERN CONFLICTS OVER FORESTLAND AND FOREST RESOURCES

10  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)


12  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).

13  Tree Niches  Water content of soil  Shade tolerance (related to succession)

14  Wilderness is 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 WILDERNESS

15  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 WILDERNESS



18  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 ECOSYSTEM SERVICES OF FORESTS


20 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.


22 ECOLOGICAL CONSEQUENCES OF FOREST FIRES  Fluorosurfactants are widely used for smothering forest fires. The chemicals are harmful for the environment, causing irreversible genetic mutations of animals and destroying the ozone layer.

23  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. ECOLOGICAL CONSEQUENCES OF FOREST FIRES CONTINUED

24 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

25 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.

26  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 PURPOSES OF A PRESCRIBED BURN


28  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. PRESCRIBED BURNING HAS BEEN USED AS A TOOL THROUGHOUT HISTORY

29  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. PRESCRIBED BURNS VS WILDFIRES

30  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 BENEFITS OF PRESCRIBED BURNS

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