Transcript Land Use and Urbanization

Land Use
Land Use
• 29% of the earth is land
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29% forests and woodlands
27% range and pastures
11% cropland
33% tundra, marsh, desert, urban areas, bare rock,
ice or snow
Forest Use
• More than ½ converted to cropland, pasture,
settlements, and wasteland
• Ecological roles?
• Used for:
• ~25% of world’s forests are actively managed for wood
production.
Forest Management
• Harvesting methods
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Selective cutting
Seed tree cutting
Strip cutting
Clear cutting
Urbanization & Urban growth
• Urban area-contains more than 1000 people per
square mile
• Urban growth due to:
– natural increase - births
– immigration
• Trends of urban growth:
– ~75% of people in developed countries live in urban
areas
– Increase of 2% to 45% of people in urban areas since
1950
– By 2050 about 66% of the world’s people will be living
in urban areas.
Urbanization & Urban growth
• The number of large cities is
mushrooming
– megacities and megalopolis
– Today, more than 400 cities have over 1 mil. or
more people.
• 19 megacities with over 10 mil. people i.e. Tokyo
(35.7 mil), Mexico City (18 mil), New York (19
mil).
Urbanization & Urban Growth
• Developing countries-most will be urban
growth
• Poverty is becoming increasingly urbanized
– slums, squatter settlements and shantytowns
– at least 1 billion people live in crowed slums of
inner cities.
– No access to water, sewer, electricity, education etc.
100 mil people are homeless & sleep on the streets
• Case study - Mexico City
Mexico City
• Tied for 2nd largest city with 19 million people (1 in 5
Mexicans)
– severe air pollution (over 4 million cars) within a valley
that causes an estimated 100,000 premature deaths/year
– high unemployment rate, close to 50%
– high crime rate
– Over 1/3 (6 million) of its residents live in slums (barrios)
without running water, sewer (but running sewage), or
electricity
– high infection rates i.e. salmonella, hepatitis
Urban Resources & Environmental Problems
• 50% of people living in 5% of land – cities
– consume 75% of the world’s resources
• Urban areas depend upon imports
Urban Resource and Environmental
Problems
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Destruction of plant life - what is $ value?
Cities produce little of own food
Urban heat island effect --> dust dome
Water supply and flooding problems
High pollution exposure
Urban Resource & Environmental Problems
• Excessive noise exposure  health effects
– Hearing loss, hypertension, muscle tension,
migraines, headaches, higher cholesterol levels,
gastric ulcers, irritability, insomnia,
psychological disorders, aggression
Benefits of urbanization
• recycling more economically feasible
• decreased birth rates reduces environmental
pressures
• population concentration impacts biodiversity
less
United States Urbanization
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Migration to large central cities
Migration from cities to suburbs
Migration from north & east to south & west
Urban sprawl, growth of low-density development
on the edge of cities.
• Main causes:
• Automobiles and highway construction
• Living costs
• Urban blight (positive feedback)
• Government policies
– Highway Trust Fund
Impacts of Urban Sprawl
Fig. 25-8
p. 666
Impacts of Urban Sprawl
Motor vehicle concentration
• Ground transportation: individual (cars, etc)
and mass (buses and rail)
Drive alone 80%
Other 4%
Public transit 5%
Car pool 11%
Pros and Cons of Mass transit
• 3% mass transit use in U.S. to 47% in Japan
• Rapid rail, suburban trains and trolley - efficient
at high population density
• High speed rail lines – replace planes, buses and
private cars; but require large government
subsidies
• Bus systems more flexible than rail systems
Alternatives to Urban Land Use?
• Smart Growth-efficient use of land resources and
existing urban infrastructure
– Using zoning laws to prevent sprawl, direct growth in
certain areas
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Mixed land uses
Create a range of housing opportunities and choices
Create walkable neighborhoods
Encourage community and stakeholder collaboration in development
decisions
Take advantage of compact building design
Foster distinctive, attractive communities with a strong sense of place
Preserve open space, farmland, natural beauty, and critical environmental
areas
Provide a variety of transportation choices
Strengthen and direct development toward existing communities
Make development decisions predictable, fair, cost effective (no cookie
cutters)