2 UrbanizationUrbanization is an increase in the ratio or density of people living in urban areas rather than in rural areas. People usually leave rural areas for more plentiful and better paying jobs in towns and cities.As urban populations have grown, many small towns have grown together and formed large urban areas called metropolitan areas. An example would be Washington D.C.-Baltimore.
4 Urban SprawlWhen people move into an area, they have to have infrastructure to support them.Infrastructure is the basic facilities of a country or region, such as roads, bridges, sewers, and railroads.
5 Urban CrisisWhen more people live in a city than its infrastructure can support, the living conditions deteriorate. This growth problem has become so widespread throughout the world that the term urban crisis was coined to describe it
6 Urban SprawlUrban sprawl is the rapid spread of a city into adjoining suburbs and rural areas
8 Other Impacts of Urbanization City environments differ from rural environments…1. Heat island is an area in which the air temperature is generally higher than the temperature of surrounding rural areas.Roads and buildings absorb and retain heat longer then vegetation does.
10 Other Impacts of Urbanization Scientists are beginning to see that heat islands can affect local weather patterns. Hot air rises over a city, cooling as it rises, and eventually produces rain clouds.Reduce heat-island effect by planting trees for shade and reflecting rooftops.In Atlanta, Georgia, and many other cities, increased rainfall is a side effect of the heat island effect.
12 FarmlandsFarmland is land that is used to grow crops and fruit. The U.S. contains more than 100 million hectares of prime farmland.In 1996, the U.S. government established a national Farmland Protection Program to help state, county, and local governments protect farmland in danger of being paved over or otherwise developed.
13 How does Farmland add to land pollution? PesticidesInsecticidesFertilizersFarm Machinery
14 RangelandsLand that supports different vegetation types like grasslands, shrublands, and deserts and that is not used for farming or timber production is called rangeland.Like farmland, rangeland is essential for maintaining the world’s food supply. World population growth may require a 40 percent increase in the food production of rangeland from 1977 to 2030.
15 Problems on the RangeOvergrazing is the depletion of vegetation due to the continuous feeding of too many animals.The Public Rangelands Improvement Act of 1978 was enacted to reverse this trend and improve land management practices.
17 Forest LandsLand used to harvest trees. Trees provide paper, furniture, lumber/plywood, syrup and turpentineAlso important for their removal of CO2 from air
18 Harvesting Trees People use enormous amounts of wood. The worldwide average is 1,800 cm3 of wood used per person each day.However, on average, each person in the United states uses about 3.5 times this amount.
19 Harvesting Trees 3 Categories of Forest land: Virgin forests: forests that have never been cut.Native forests: forests that are planted and managed.Tree farms: areas where trees are planted in rows and harvested like other crops.
21 2 Methods of Harvesting Trees 1. Clear-cutting is the process of removing all of the trees from and area of land. Clear-cutting large areas destroys wildlife habitat and causes soil erosion.2. Selective cutting is the process of cutting and removing only middle-aged or mature trees. It is more expensive than clear-cutting, but is usually much less destructive. It is usually practiced on smaller areas owned by individuals.
23 DeforestationDeforestation is the process of clearing forests.
24 Impacts of Deforestation 1. When forests are cleared from hillsides, soil erosion usually results if the area is not quickly planted with a cover crop. Without tree roots to hold the soil in place, it is easily washed or blown away into the valley below.2. Deforestation reduces wildlife habitat3. Reduction of the amount of carbon dioxide taken out of atmosphere
25 ReforestationReforestation is the reestablishment and development of trees in a forest land.
26 Parks and PreservesIn the 1870s, a group of explorers approached Congress with news of a magnificent expanse of land in Wyoming and Montana they believed would be damaged by the development that had changed the northeastern United States.Congress agreed to protect this land by setting it aside for the public to use and enjoy, and the first national park, Yellowstone, was created.Today, the U.S. has about 50 national parks.
28 WildernessThe U.S. Wilderness Act, passed in 1964, designated certain lands as wilderness areas.Wilderness is a region that is not cultivated and that is not inhabited by humans.So far, 474 regions covering 32 million acres have been designated as wilderness in the United States. These areas are open to hiking, fishing, and camping. Building roads or structures and using motorized equipment is not allowed in wilderness areas.
29 Benefits of Protected Areas Protected areas often provide the only place where unspoiled forests, deserts, or prairies remain.Wilderness areas serve as outdoor classrooms and research labs where people can learn more about the natural world.These protected areas also provide recreation, such as hiking and camping, for many people.
30 Threats to Protects Areas 1.Litter and traffic jams now plague many of our national parks.2. Rangelands, mining and logging sites, oil and gas operations, power plants, and urban areas are often close enough to affect the parks.3. In addition, preserved areas are affected by climate change and by air and water pollution, as are most other parts of the world.