Transcript Ch 12 notes and Prescribed Burn 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
Recreation
Climate regulation (surface color,
transpiration/evaporation which reduces
erosion, rate of greenhouse gas release, wind
speed)
TREE TERMS
 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
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
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
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
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
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
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 Niches
Water content
of soil
Shade
tolerance
(related to
succession)
WILDERNESS
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
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
FOREST FIRES AND
PRESCRIBED BURNS
APES 20132014
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
THREE T YPES 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.
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.
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 firetolerant 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.
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
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, costeffective and safe tool when properly planned
and implemented.
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.
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 firedependent species
Releases less air pollution than a
wildfire