AP Environmental Science Ch 12 Notes

2013-2014

AP ENVIRONMENTAL SCIENCE CH 12

NOTES

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

RecreationClimate regulation (surface color,

transpiration/evaporation which reduces erosion, rate of greenhouse gas release, wind speed)

PUBLIC-SERVICE FUNCTIONS OF FORESTS INCLUDE

Silviculture is the professional growing of treesA 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

A plantation is a stand of a single species, typically planted in straight rowsSometimes fertilized by helicopterRequire intensive management (if the previous point didn’t convince you)

Rotation time is the time between cuts of a stand

TREE TERMS

HarvestingClear-cuttingSelective 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

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

The ConflictsCommodity vs. Conservation vs. Compromise

Sustainable managementRole in global environment/climateEndangered speciesWater supply

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

MODERN CONFLICTS OVER FORESTLAND AND FOREST

RESOURCES

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)

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).

Tree NichesWater content of soil

Shade tolerance (related to succession)

Wilderness is an area undisturbed by people, with the exception of visitors

According to the US Wilderness Act of 1964, wilderness has the following qualitiesthe imprint of human work is unnoticeable

there are opportunities for solitude and for primitive and unconfined recreation

there are at least 5000 acres

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

WILDERNESS

APES 2013-2014

FOREST FIRES AND PRESCRIBED BURNS

Removal of carbon/release of oxygen

Food for humans (ex. Deer, nuts, fungi)

Provide habitats for many speciesWood (fuel, material)Others from previous notes

ECOSYSTEM SERVICES OF FORESTS

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.

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.

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

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

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.

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

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

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

Clearing of forest floor, which removes combustible material and decreases likelihood of wildfire

Creation of nutrient-rich ashPromotes growth of fire-tolerant and fire-dependent species

Releases less air pollution than a wildfire

BENEFITS OF PRESCRIBED BURNS