Silviculture--Deforestation

Forestry & Society

HORT/RGSC 302

Fall 2007

Forestry & Society

World Forests & Land Use/ Pop. Act. Int’l 1999

0

1

2

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6

7

8

6000BC 0 AD1000 1500 1800 1900 1950 1990 2000 2010

Forest landCroplandPopulation

Billions

Forestry & Society

Loss of World Forests/ Stanturf & Madsen Plt Biosys 136(2):143:2002

0

10

20

30

40

50

60

70

80

Asia-Pacific Africa Europe LatinAmerica

NorthAmerica

Loss of Original Forest Cover (%)

6 kkk ha

3.45kkk ha

Forestry & Society

Human Impacts on Forests

• Places we have clearcut!!!– Middle East – Iceland– Easter Island– Chaco Canyon

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Human Impacts on Forests Easter Island

• ‘Discovered’ by the Dutch in 1722– Barren, eroding wasteland with few

people (~2,000) and no trees, but huge monoliths (14-80 tons)

• Polynesians arrived ~400 AD– forest included 80 ft palms (for

skids), hauhau tree (for rope), and toromiro (for fuelwood)[pollen analysis]

– population grew to ~20,000 (hunted dolphin from canoes)

– last tree cut about 1400--population declined, but couldn’t leave!

J. Kaspersen, Erosion Control 8(2)Mar/Apr:6: 2001

Forestry & Society

Human Impacts on Forests Chaco Canyon

• Anasazi inhabited 850-1250 AD– Center of culture– Multi-storied home sites– Clearcut region and abandoned

sites

Where have all the trees gone?50 most forested countries

22

4

3

21

Forestry & Society

Changes in Forest Cover (1980-1990)/ FAO 1997

% Change

Forestry & SocietyThreatened Original forests-The Africa & Russia/ WRI 1997

Low to no threat

Medium to high threat

Second growth forests

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Threatened Original forests-The Americas/ WRI 1997

Low to no threat

Medium to high threat

Second growth forests

Unknown

Forestry & Society

World Forest Loss/ Pop. Act. Int’l 1999

Land Degradation

Land Abandonment

Forest Clearing

Migration

Population Growthand Resettlement

Forest to Farmland Loss Model

Forestry & Society

World Forest Loss/ Pop. Act. Int’l 1999

Underlying CausesPopulation Change

growthdensitymigration

Economic Growthrising incomedietary changehousing preference

PovertyMarket failures

forest valuationPolicy Failures

population resettlementcorruption

Direct CausesAgricultural clearing of forests

subsistence agriculturecommercial farmingcattle ranching

Industrial loggingInfrastructure & industrial development

roadsdamsmininghousing

Fuelwood & charcoal production

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Tropical Deforestation/ Sharma 1992

Original Forest Cover

Present Forest Cover

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Tropical Deforestation/

• Worldwide = 3 KKK ac of tropical forests– <5% sustainably managed– Latin America = 1.3 KKK ac (27KK ac protected)

• Brazil (975 KK ac of tropical forest land) [For.Sourc. #10 7/05]

– Loses > 6.2 KK ac/yr to deforestation

– Has lost > 17% of tropical forests

– In 2000, 33 KK ac planted to soybeans

– Asia & Pacific = 415 KK ac (48KK protected)

– Africa = 272 KK ac (14.8KK protected)L.J. Adams Alb. J. 5/27/06 p.A8

Forestry & Society

Tropical Deforestation/Brazil

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5000

10000

15000

20000

25000

30000

35000

1988 1989 1990 1991 1992 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

km2/yr

Deforestation (km2/yr)

The For.Sourc. #10 7/05

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Tropical Deforestation/Cuba

• 1600 > 90% forest• 1959 < 14% “• Today ~ 24% “

• 2,618,700 ha (~90% native)• 126 kk m3 (+7.5 kk m3 /yr)

– Harvest 1.6 kk m3 /yr (65% fuelwood)

– ~40,000 workers

http://www.rcfa-cfan.org/english/profile.20.htm

Tocororo bird

Deforestation in Haiti

A truck carrying peasants and bags of freshly

made charcoal rumbles through the Pine Forest Reserve.

DANIEL MOREL/SPECIAL TO THE HERALD

A young girl carries pine branches torn from trees in

La Visite Park, a reserve outside Port-au-Prince.

1492 = 75% Forested1998 = 1% Forested

Forestry & SocietyTropical Forests- Deforestation / Thailand

Longman & Jenik 1987

Shaded = Deforested

18 yrs

• Land Area = 11.86 billion ha– 16.5% forested (1.96

billion ha)– 11 Western provinces

= 9.06% forested– 5 NW provinces =

3.34% forested– 1/3 of country faces

serious erosion

• Population ~ 1.2 billion people– 400 million affected by

deforestation

Deforestation in China

Hainan island• 3.4 kk ha • 370 k ha rubber tree• 130 k ha eucalyptus

– 4% ↑ in forest cover

• 6-8% of island has been reforested or rehabilitated

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1930 1950 1970 1980 1995

Year

Forest Cover (%)

Deforestation in China Zhang et al. Res. for Fut. 2003

• 42 billion trees have been planted since 1982

• number of sandstorms has grown from 5 in the ‘60's to 24 in the ‘90's

• deserts are expanding at a rate of 3,800 square miles a year

Stuart Isett/Polaris, for The New York Times

In northwest China, the Taklimakan's sands are shifting toward poplar trees planted west of Aksu in a vast project intended to halt desertification.

Forestry & Society

Tropical Forests- Deforestation Affects/ Longman & Jenik 1987

0

200

400

600

800

25 45 55 65 75 85

Soil loss Soil loss

Run-off Run-off

Run-off (ml/m2) Soil loss (g/m2)

6

4

2

0

Canopy Cover (%)

>20 mm/hr

<10 mm/hr

Thailand

Forestry & Society

Deforestation

• Things to Know– What is deforestation?– What are direct and indirect causes of

deforestation?– What are some of the effects of

deforestation?– How would you solve the problem of

deforestation?