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Environmental Science Ch. 14

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1 Environmental Science Ch. 14
LAND Environmental Science Ch. 14

2 Bell Ringer

3 Objectives Distinguish between urban and rural land.
Describe three major ways in which humans use land. Explain the concept of ecosystem services.

4 I. How We Use Land A. Land Use and Land Cover
We us land for many purposes including farming, mining, recreation, and building cities and highways Land cover is what you find on a patch of land – it depends on how the land is used -forest, field of grain, parking lot

5 2 Types of Land Urban land – land that is covered mainly with buildings and roads -contains 2,500 or more people and usually has a government body like a city council Any area not classified as urban is rural Rural land – land that contains relatively few people and large areas of open space Most land provides one or more resources that humans consume – table 1


7 B. Where We Live Until 1850 most people lived in rural areas -many were farmers who grew crops and raised livestock for food, clothing, and manufacturing others managed forests, worked in local mines or mills, or manufactured necessities of life for a town

8 The Industrial Revolution changed this pattern
-machinery was built that made it possible for fewer people to operate a farm or grain mill -better transportation allowed manufacturers to be located far from their customers -thousands of jobs in rural areas were eliminated so people moved to cities to find jobs Urban areas grew rapidly in the 20th century and spread over more land -today most people in the world live in urban areas -happened rapidly in developed countries between 1880 and 1950 -now happening rapidly in developing countries

9 Where We Live

10 C. The Urban-Rural Connection
Whether people live in the cities or countryside, they are dependent on the resources produced in rural areas -these resources include clean drinking water, fertile soil and land for crops, trees for wood and paper and much of the oxygen we breathe


12 Ecosystem services Ecosystem services – the resources that are produced by natural and artificial ecosystems -examples are listed in table 2 Supporting Urban areas -area of rural land is needed to support one person depends on many factors -the climate, standard of living, how efficiently resources are used -each person in a developed country uses the ecosystem services proved by about 8 hectares of land and water

13 Answer on Your Dry erase Card for EC

14 How we compare -in the US each person uses the ecosystem services from more than 12 hectares whereas each person in Germany uses about 6 hectares worth -individuals in developing countries do not have access to all the resources for a healthy life – they may use ecosystem services from less than a hectare of land

15 Bell Ringer

16 Objectives Describe the urban crisis, and explain what people are doing to deal with it. Explain how urban sprawl affects the environment. Question how open spaces provide urban areas with environmental benefits. Formulate how the heat-island effect occurs. Predict how people can use the geographic information system as a tool for land-use planning.

17 Predict There are two types of land represented here, Open and Urban. One is covered with soil and vegetation, the other is covered with impermeable material. Predict which will be warmer at the end of class and record that in the margin of your notes. What is this phenomenon called?

18 II. Urban Land Use A. Urbanization
Urbanization – the movement of people from rural areas to cities -people 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 larger urban areas -called metropolitan areas -Urban areas that have grown slowly are often relatively pleasant places to live – roads and public transportation have been built to handle the growth so that traffic flows freely

19 Urbanization The Urban Crisis
-buildings, roads, and parking lots are mixed in with green spaces and recreational areas -green spaces may provide these urban areas with much needed ecosystem services such as moderation of temperature, infiltration of rainwater runoff, and aesthetic value The Urban Crisis -when urban areas grow rapidly, they often run into trouble -can overwhelm the infrastructure and lead to traffic jams, substandard housing, and polluted air and water

20 GIS Views Of Seattle, WA

21 Urban Needs infrastructure – all the things that a society builds for public use -roads, sewers, railroads, bridges, canals, fire and police stations, schools, libraries, hospitals, etc. -when more people live in a city than its infrastructure can support the living conditions deteriorate causing an urban crisis

22 Urban sprawl – the rapid expansion of a city into the countryside around the city
-building suburbs or housing and associated commercial buildings on the boundary of a larger town -people living in the suburbs commute to work in the city by car -suburbs build on land previously used for food production -each year in the US suburbs spread over another 1 million hectares of land

23 Development on Marginal lands
-many cities were first built where there was little room for expansion -as cities grew the suburbs were often built on marginal land –land that is poorly suited for building Other Impacts of Urbanization -cities generate and trap more heat – roads and buildings trap more heat than vegetation does and retains heat longer -increased temperature in a city is called a heat island -heat islands can affect local weather patterns

24 What Is an Urban Heat Island?
As urban areas develop, changes occur in their landscape. Buildings, roads, and other infrastructure replace open land and vegetation. Surfaces that were once permeable and moist become impermeable and dry. These changes cause urban regions to become warmer than their rural surroundings, forming an "island" of higher temperatures in the landscape

25 Why Do We Care About Heat Islands?
Elevated temperature from urban heat islands, particularly during the summer, can affect a community's environment and quality of life. While some heat island impacts seem positive, such as lengthening the plant-growing season, most impacts are negative and include: More energy used for cooling Promotes ground level ozone Thermal water pollution

26 How do we prevent the Urban Heat Island
increasing tree and vegetative cover creating green roofs (also called "rooftop gardens" or "eco-roofs") installing cool—mainly reflective—roofs using cool pavements.

27 B. Urban Planning Land-use planning – determining in advance how land will be used -where houses, businesses, and factories will be built, where land will be protected for recreation, etc. -land use planners determine the best locations for shopping malls, sewers, electrical lines, and other infrastructure

28 -making land-use plans is a complex and controversial process
-federal, state, and local developers prepare detailed reports assessing the environmental impact of any projects -developers, city governments, local businesses, and citizens often disagree about land-use plans Technological Tools -land use planners have sophisticated methods and tools available for them

29 (GIS) Geographic information system (GIS) – a computerized system for storing, manipulating, and viewing geographic data -GIS software allows a user to enter different types of data about an area and create maps – uses GPS Transportation -most cities in the US are difficult to travel in without a car -many cities have a mass transit system – have been constructed to get people where they want to go -Mass transit is a planning solution that saves energy, reduces highway congestion, reduces air pollution, and limits the loss of land to roadways and parking lots

30 Wide Open Spaces Open space – land within an urban area set aside for scenic and recreational enjoyment -parks, public gardens, bicycle and hiking trails Greenbelts – open spaces left in their natural condition -provide important ecological services Have plants that absorb carbon dioxide, produce oxygen, and filter out pollutants from air and water, keep the city cooler, reduce drainage problems by absorbing more rainwater runoff resulting in less flooding provide places for exercise and relaxation

31 Bell Ringer

32 Objectives Explain the benefits of preserving farmland.
Describe two ways that rangeland can be managed sustainably. Describe the environmental effects of deforestation. Explain the function of parks and of wilderness areas.

33 III. Land Management and Conservation
As human populations grow, the resources of more rural land are needed to support the population The main categories of rural land are farmland, rangeland, forest land, national and state parks, and wilderness -we have reduced their productivity by overusing or polluting them -condition of rural land is important because of the ecological services that it provides

34 A. Farmlands Farmland is land that is used to grow crops and fruit
-urban development in some places threatens some of the most productive farmland -in 1996, the US government established a national Farmland Protection Program to help state, county, and local governments protect farmland in danger of being developed

35 B. Rangelands Rangeland – land that supports different vegetation types like grasslands, shrublands, and deserts that is not used for farming or timber production -can be arid or wet -most common use of rangelands is for the grazing of livestock like cattle, sheep, goats which are valued for their meat, milk, wool, and hides -native wildlife species also graze this land -necessary for maintaining the world’s food supply

36 Problems on the Range -rangelands in the US have become degraded by poor land management strategies -overgrazing – allowing more animals to graze in an area than the range can support -cause most damage to rangelands -when animals overgraze, too many of the plants are eaten and the land can become degraded -less desirable plant species may invade the area and replace more desirable plant species -in severe cases all vegetation is eaten -once the plants are gone there is nothing to keep the soil from eroding leading to Desertification

37 Maintaining the Range -much of the rangeland in the US is public land managed by the federal government which leases the rangeland to ranchers -much of it is degraded -1978 Public Rangelands Improvement Act – enacted to reverse this trend and improve land management practices -sustaining the productivity of the rangeland generally means reducing overgrazing by limiting herds to sizes that do not degrade the land

38 Rotational Grazing may be left unused for periods of time so that the vegetation can recover -improving rangeland that has been damaged includes -killing invasive plants and planting native vegetation -fencing areas to let them recover -ranchers dig several small water holes so that livestock to not overgraze around a single water hole

39 C. Forest Lands Harvesting Trees
Trees are harvested to proved products we use every day, paper, furniture, lumber and plywood for home -forest products such as maple syrup and turpentine -one of the most important services is the removal of CO2 from the air Harvesting Trees -people use enormous amounts of wood -each person in the US uses 3.5 times the worldwide average of 1,800 cm3 per person each day -each person cutting down a tree 30m tall every year

40 Trees developing nation individuals depend on firewood as their main source of fuel -timber industry classifies forest lands into three categories -virgin forest – a forest that has never been cut -native forest – forest that is planted and managed -tree farms – areas where trees are planted in rows and harvested like other crops

41 two most widely-used methods of tree harvesting are
-clear cutting – process of removing all the trees in an area of land -destroys established wildlife habitat and causes soil erosion -selective cutting – process of cutting and removing only middle-aged or mature trees -more expensive than clear cutting but much less destructive

42 Harvesting Trees

43 Deforestation Deforestation – the clearing of trees from an area without replacing them -countries become severely deforested as populations expand and the demand for forest products increases -forests are cleared to convert land into farmland or to make space for roads, homes, factories, and office buildings -deforestation reduces wildlife habitat

44 Deforestation -causes soil erosion – there are not tree roots to hold the soil in place and it is easily washed or blown away -rate of deforestation is high in tropical rain forests where the soil is relatively thin -farmers who clear forests in these areas must always move from one plot of land to another and clear more forest each time they move -whether cleared for farming or wood, if trees are not replanted natural resources are steadily depleted

45 Reforestation Reforestation – the process by which trees are planted to re-establish trees that have been cut down in forest land -in some places reforestation is happening faster than trees are being cut down – New England -some governments require reforestation after timber has been harvested -private organizations have established tree-planting programs on roadsides in cities

46 Reforestation

47 D. Parks and Preserves In 1870, the first national park was established – Yellowstone National Park -today, the US has about 50 national parks Public lands have many purposes -most are not protected as national parks -leased to private companies for logging, mining, and ranching -maintained for hunting and fishing or as wildlife refuges or for protecting endangered species International efforts have set up several hundred biosphere reserves around the world – include people in their management plan

48 Wilderness Under the US Wilderness Act of 1964, designated certain lands as wilderness areas Wilderness – an area in which the land and the ecosystems it supports are protected from all exploitation -open to hiking, fishing, boating (without motors), and camping -building roads or structures and using motorized equipment are not allowed

49 Parks & Preserves


51 Benefits of Protected Areas
-without national and private parks and preserves around the world, many more species would be extinct -provide recreation for people -only place where unspoiled forests, deserts, or prairies remain -serve as outdoor classrooms and research labs where people can learn more about the natural world

52 Threats to protected areas
-constant battle between our conservation efforts and the growing population -litter and traffic jams, rangelands, mining, logging, oil and gas drilling operations, factories, power plants, and urban areas are often close enough to the park to affect them -preserved areas are affected by climate change and air and water pollution

53 Threats to protected areas
-wilderness areas have limits to the number of people permitted in some areas if at all -volunteer programs to pick up trash, build trails, control invading or exotic species, and educate the visiting public


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