deforestation n.
Skip this Video
Download Presentation

Loading in 2 Seconds...

play fullscreen
1 / 22

DEFORESTATION - PowerPoint PPT Presentation

  • Uploaded on

DEFORESTATION. How Forests Reduce Natural Hazards. Trees prevent sediment runoff Forests hold and use more water than farms and grasslands Leaves capture rainwater and reduce raindrop impact, which decreases soil erosion

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'DEFORESTATION' - barclay-young

Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
how forests reduce natural hazards
How Forests Reduce Natural Hazards
  • Trees prevent sediment runoff
  • Forests hold and use more water than farms and grasslands
  • Leaves capture rainwater and reduce raindrop impact, which decreases soil erosion
  • Roots hold soil in place, reducing the movement of sediment, preventing landslides
  • Roots create dry soil by absorbing water, which prevents overflow of rainwater
what who and why deforestation
What, Who, and Why?Deforestation
  • Clear-cuts for logging and pulp wood (for paper)
  • Cultivation of land for agriculture
  • Permanent pastures
  • Open-pit mining
  • Dam Construction
  • Chemical Defoliants
  • Urban Expansion
  • Wildfires
harmful behaviors harmful side effects
Harmful Behaviors, Harmful Side-Effects
  • Paving roads and infrastructures within forests
    • Causes soil compaction
    • Blocks culverts that funnel water underground and focus runoff into gullies
    • Alter water runoff patterns and permanently disrupt subsurface water flow
    • Enables greater human access to forests, increasing the number and severity of forest fires
  • Roads are permanent whereas clear-cuts are temporary and allow for regeneration
Logging roads trigger debris avalanches that accelerate erosion 25 to 340 times more than intact forests
effects of deforestation
Effects of Deforestation
  • Soil erosion
    • Heavy impact of rain causes increased sedimentary erosion and quicker runoff
    • The eroded soil is deposited into river beds, shrinking the channels and lowering the carrying capacity of water, increasing the likelihood of flooding exponentially
effects of deforestation1
Effects of Deforestation
  • Landslides
    • Without the roots of trees to hold the soil in place, moderate to heavy rainwater can cause massive mudslides
    • Landslides, particularly mudslides, usually occur in steep, narrow stream channels that allow them to move very quickly and pick up more debris as they go
Once the landslide has slowed down and reached a more level plane, the debris and mud solidify to cause blockage of valleys and streams, backing up water and leading to large, sudden floods
effects of deforestation2
Effects of Deforestation
  • Floods
    • Deforestation does not directly cause floods, but it does exacerbate the magnitude and force of the floods
    • Without trees, the soil cannot absorb enough rainwater, causing massive runoff
effects of deforestation3
Effects of Deforestation

Trees use CO2, converting it into oxygen for other organisms to breathe. Deforestation leads to higher CO2 levels, which directly contribute to global warming.

  • Deforestation began when the island was annexed as a French colony in 1896
  • Due to famine and unstable politics, the natives fled to the forests, where they began using “shifting cultivation,” in which they cleared regions of the forests, sometimes by burning them, and used the land for subsistence agriculture
  • Beginning in the 1950’s, the rate of deforestation increased dramatically due to population increase and improvements in technology
  • Social Consequences
    • Today, the majority of the Malagasy people live in poverty due to the economic exploitation of their country and are unable to find jobs
    • In order to create some sort of income, many natives turn to exploitation of their natural resources, mainly the forests. For them, it is a choice between their own lives and livelihood of the forest
    • Large corporations have a great deal of influence on whether or not deforestation continues because the Malagasy government needs their investments in order to survive.
  • Environmental Consequences
    • By 1985, only 34% of the original forest in Madagascar remained
    • Lack of trees leads to increased likelihood of violent floods and mudslides
    • Soil erosion causes the runoff of sediments, leaving the deforested area barren. The runoff prevents not only the regeneration of the forest but also inhibits further growth from relief efforts.

Due to the color of the sediment runoff in Madagascar, many have commented on aerial photography, like this one, by saying that it appears as though the country itself is bleeding. In a way, that is exactly what is happening.

yellow river floods yangtze china is deforestation to blame
Yellow River Floods: Yangtze, ChinaIs Deforestation to Blame?
  • Controversy over whether two decades of deforestation contributed to serious floods in 1998 (4,000+ casualties)
  • “logging carried out without a policy of sustainable forest management”
  • Lost 30% of forest cover in the last 15 years, 85% altogether
1998 floods
1998 Floods
  • Soil erosion on higher part of the Yellow River caused silting of the riverbed. This caused a build up of water in the central/lower part of the river, which eventually lead to flooding
  • Deforestation robbed the land of important flood plain waterways
controversy in beijing
Controversy in Beijing
  • Beijing government blamed floods on small-scale loggers and farmers.
  • Established a plan to mitigate against further floods:
    • relocated more than 1 million logging employees
    • closed hillsides to herders to allow for regrowth
    • protected 60 million hectares of forests upstream and began replanting programs
    • Began construction of Xiaolangdi Dam
  • China linked to logging in Africa, the Amazon, Burma, Indonesia
haiti and hurricane jeanne
Haiti and Hurricane Jeanne
  • Haiti has lost more than 90% of its original forest cover
  • Jeanne left the country completely devastated by massive floods triggered by the hurricane
  • Deforestation due to centuries of forced poverty by imperial domination and capitalist exploitation
  • Jeanne had less of an impact upon Bahamas and Florida
it s not just the forests
It’s Not Just The Forests…
  • Environmental Refugees: people displaced due to environmental degradation
  • Worldwide, more people are displaced each year due to environmental disasters than by war.

“The rapidity at which this country is being stripped of its forests must alarm everything thinking man…It is high time that we should turn our earnest attention to this subject which so seriously concerns our national prosperity”-U.S. Secretary of the Interior Carl Shurz, 1877


Butler, Rhett A. "A World Imperiled: Forces Behind Forest Loss." / A Place Out of Time: Tropical Rainforests and the Perils They Face. 9 January 2006.

Chin, Pat. "Haiti, Hurriane Jeanne, and Class Struggle." Workers World. 7 Oct. 2004. <>.

Draffan, George, and Derrick Jensen. Strangely Like War: the Global Assault on Forests. White River Junction, Vt: Chelsea Green, 2003.

Jarosz, Lucy. "Defining and explaining tropical deforestation: shifting cultivation and population growth in colonial Madagascar." Economic Geography 64.9 (Oct 1993): 366-80.

Miles, James. "China Tries to Combat Floods." BBC News. 13 July 1999. <>.

"Deforestation Case Study: Madagascar".

"Flood of Evidence." The Why Files. < >.

"Is China Ready for More Floods?" BBC News. 12 June 2002. <>.

“Landslides” (United States Search and Rescue Task Force)