According to the College Board's topic outline for AP Environmental Science, about 10% of the questions will ask about subjects we'll review in this chapter.
The fundamental themes of this chapter need to be reviewed.
A resource is defined as an available supply that can be used as needed.
The land, water, and things that grow from them are all resources that humans rely on to live.
Humans use the land and water for many reasons.
We will begin our discussion with a description of the resources of the world, including what happens if people don't get enough resources.
We'll look at the resources from agriculture, forests, oceans, and mining.
When people talk about managing common property resources such as air, water, and land, a paper published in Science magazine in 1968 called " The Tragedy of the Commons" often comes to mind.
In the story, a piece of open land, a commons, was to be used collectively by the townsfolk for grazing their cattle.
The people who used the land would add one cow or ox at a time.
In a world that is limited, each person is locked into a system that forces him to increase his herd without limit.
All people rush to ruin, each pursuing his own best interest in a society that believes in the freedom of the commons.
The use of a resource is regulated so that it doesn't exceed the capacity of the resource to regenerate itself.
This is different from preservation, which is the maintenance of a species in order to ensure their perpetuation, with no concern as to their potential monetary value.
In this chapter, we will show how human economics can affect how we interact with Earth's resources.
Natural resources are often referred to as biotic and abiotic.
Natural resources are described in terms of their value as natural capital because we put an economic value on them.
Let's talk about the two main types of resources.
Plants and animals are renewable resources.
These resources can be regenerated quickly.
The time needed for hardwood trees to mature is considered the cross-over point from renewable resources to nonrenewable resources.
A special renewable resource is soil.
The soil's rate of increase is about 1 inch per 500 years, so it may seem like it's not that renewable.
Minerals and fossil fuels arerenewable resources.
Nonrenewable resources can't be regenerated within the realm of human existence because they are formed by very slow geologic processes.
Before we dive into our review of the major resources available to humans on Earth, we need to know more about consumption and production.
A fisherman sells his fish in a market.
Let's move on.
77 percent of the world's food comes from croplands, 16 percent comes from grazing lands, and 7 percent comes from ocean resources.
Despite the importance of our crops and the fact that the population of the United States has increased, fewer people now farm the land in the history of the United States.
The answer is that it has a lot to do with industrialization and increasing urbanization.
Only 2% of the United States population is employed in the agriculture industry now that machines are readily available to work the land and harvest crops.
Today's farms are larger than the ones of the past.
The average farm size in the early 20th century was about 100 acres, but now it's 434 acres, or a little less than an American football field.
One of the drawbacks of using machinery in farming is the amount of fossil fuel needed to power it.
The cost of food will go up as the cost of fuel goes up.
The development of new high-yield seed types can be linked to the rise in agricultural productivity.
Huge problems in erosion have been caused by a decrease in the genetic variability of crop plants.
Throughout most of the world's history, families relied on animal and human labor to plant and harvest crops, and each family grew their own crops.
Traditional subsistence agriculture provides enough food for one family's survival.
42 percent of the world's population practices traditional subsistence agriculture, which is still practiced in developing nations.
It is possible for people to live permanently without having to migrate.
There are low amounts of labor inputs per unit of lands.
Slash and burn is a method that dates back to early humankind and is still practiced in many developing countries today.
Slash and burn is when vegetation is cut down and burned to make way for crops.
Because soils in these developing countries are generally poor, the farmer must leave the area after a short time and find a new location.
This practice reduces the amount of forest and contributes to the destruction of it.
The time after the Industrial Revolution when farming became mechanized and crop yields in industrialized nations boomed is known as the Green Revolution.
famers in the Third World were able to increase crop production on small plots of land because of these innovations.
Integrated pest management and other techniques that use organic methods are promoted in the second green revolution.
Don't confuse the Green Revolution with the Green Movement, they are both about farming.
An increase in the use of pesticides contributed to the Green Revolution.
When the first white settlers planted their first corn crops, certain tribes of Native Americans taught them to plant fish leftovers along with the corn seed.
The fish helped the crops.
Farmers have used organic materials such as manures for many years.
Huge increases in farm production were seen during the Green Revolution due to the development of chemical fertilizers.
There are drawbacks to the widespread use of chemical fertilizers, including the reduction of organic matter and oxygen in soil, the large amounts of energy needed to produce, transport, and supply thefertilizer, and the fact that once thefertilizer are washed into watersheds, they are dangerous pollutants.
The Green Revolution has reduced the number of crops lost to insects and other pests, but the chemicals used to kill them have an effect on the surrounding farms.
New pesticides must be constantly developed because the average insect pesticide will only be useful for a few years before it becomes useless.
Congress amended the Federal Insecticide, Fungicide, and Rodenticide Act in 1972 because the use of pesticides is so common in the United States.
The law requires the EPA to approve the use of pesticides.
One of the major contributors to the increased crop yields seen in the Green Revolution was advanced irrigation techniques, which allowed crops to be planted in areas that normally wouldn't have enough precipitation to sustain them.
A significant amount of salts on the soil's surface can make the land unusable for crops, which can be caused by repeated irrigation.
Farmers have begun flooding fields with water in order to move salt into the soil in order to combat the salinization of the land.
Large amounts of water can cause the water table of the region to rise, and this is a downside to this, as large amounts of water can waterlog plant roots, which will kill the crops.
These irrigation farms get their water from underground water tables.
Large-scale grain-production countries such as India, China, and the United States are being affected by the rapid decline of the aquifers.
Integrated pest management is a more eco-friendly way to deal with pests than using chemical pesticides.
IPM tries to keep the pest population down to an economically viable level rather than trying to get rid of every single pest on the farm.
Some of the methods include introducing natural insect predators to the area, intercropping, using mulch to control weeds, crop rotation, releasing pheromone or hormone interrupters, and constructing barriers.
The worst-case scenario is when people use IPM.
The introduction of genetically engineered plants was the last significant contributor to the Green Revolution.
In genetic engineering, scientists try to improve plants by adding genes from one species to another to encourage desirable characteristics, such as longer shelf life, disease resistance, and higher crop yields.
The golden rice, which contains vitamins A and iron, was an example of how this method can be used.
The introduction of this rice addresses two of the serious health problems that are seen in developing nations: iron deficiency, which leads to anemia, and vitamin A deficiency, which can result in blindness.
There are many problems with genetically modified organisms.
It has become a very controversial topic.
Scientists don't know how genetically modified organisms will affect the planet.
Genetically modified plants can cause harm to beneficial insects and organisms, cause antibiotic resistance, and cause new pesticide-resistant pests.
Many farmers and consumers are concerned that cross pollination can cause problems with other crops, such as organic farms that choose not to use genetically modified organisms.
The yield of rice, wheat, and corn increased by more than 1000% due to genetic engineering.
Genetic engineers discovered a way to make plants divert more of their photosynthate to become grain.
Approximately 30,000 plant species could be used for food, but only 10,000 have been used historically.
Today's agriculture is a major reduction in agricultural biodiversity.
Today's farming is characterized by monoculture.
In a monoculture, only one type of plant is planted.
In the era of early political civilizations, farms produced a staple crop in large order to feed entire societies and armies.
This has proved to be a bad practice for a number of reasons.
Plantation farming is a type of industrialized agriculture in which a monoculture cash crop such as bananas, coffee, or vegetables is grown and then exported to developed nations.
The story in this book takes place in the 1930s, when the Great Plains were reduced to a giant Dust Bowl.
Farming practices used during the Dust Bowl contributed to the destruction of the land.
The United States Soil and Conservation Service was established in an effort to address the Dust Bowl and other agricultural problems.
The service set up the districts to give education to farmers.
Farmers are able to protect soil from degradation.
The erosion that can occur when rows are cut up and down on a slope can be prevented by the practice of contour plowing.
Terracing helps prevent soil erosion on steep slopes.
Terraces are flat platforms that are cut into the hillside to provide a level planting surface.
In no-till agriculture, farmers plant seeds without using a plow to turn the soil.
Carbon dioxide gas is released into the atmosphere when soil loses most of its carbon content.
Crop rotation can provide soils with nitrogen when there is a cycle of crops in the area.
Intercropping is the practice of planting bands of different crops across a hillside.
An extensive network of roots can be created by this type of planting.
Plant roots hold the soil in place and reduce or prevent soil erosion.
The livestock business has been affected by the introduction of all these new agricultural techniques.
If the area is sufficient for the number of animals, it is a sustainable practice.
If grass is consumed by animals at a faster rate than it can re- grow, land is overgrazed.
Overgrazing can lead to erosion and soil compaction.
Similar to crop rotation, animals can be moved from site to site and away from their source of water.
The control of herd numbers is a solution.
There are tracts of public lands that can be used for rangeland, and cooperation between government agents, environmentalists, and ranchers can help avoid problems of overgrazing on these lands.
Federal rangelands are managed by the Bureau of Land Management.
There is a large amount of animal waste produced because of the large number of animals.
It is not possible to use mére asfertilizer due to transportation issues.
It is the most widespread source of water pollution in the United States.
70 percent of the total grain crop consumed in the United States is eaten by animals.
Many environmentalists are concerned about the destruction of the environment.
The number of trees in North America is the same as 100 years ago, but only 5 percent of the original forests are left.
The numbers are the same because there are more trees in national parks and tree plantations.
It means that most of the trees in North America are young and that most forests have undergone significant succession.
The removal of trees for exportation is a major issue for environmentalists.
The industrialized countries have a higher demand for wood than the developing countries.
This can be explained by the fact that land is being cleared for pastures and farms in developing countries.
Developing countries can import lumber from industrialized countries.
In order to create space for homes and agricultural plots, nearly all of the deforestation that takes place in North America is done.
The impact on resident ecosystems is significant in some sites.
Take Canada's Vancouver Island.
The mountainsides on this island have been stripped bare.
The lumber industry tries to offset the destruction by planting new trees, but they won't be harvestable for another 50 years.
The lumber industry will not be asked to leave the island.
It's the most important source of income.
Fifty cents of every dollar the island earns comes from lumbering--this number easily beats the island's income from tourism.
There are other consequences to this type of clearing.
Due to the loss of root structure, the areas are 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 The environment is not suited for salmon because it is washed into freshwater streams and rivers.
The loss of shade affects aquatic organisms.
In countries with tropical forests there is a negative environmental effect.
The area can only support crops for a short time when trees are removed and farms are placed in the cleared land.
Once the soil is no longer able to support a crop, the land can be used for grazing, but the soil becomes more and more polluted as time goes on.
The negative repercussions of clearing tropical rainforests--the losses in biodiversity, and the erosion and depletion of nutrients in the soil--seem to outweigh the economic gains in many people's opinions.
It is difficult to determine which wood products come from tropical rainforests and which come from sustainable forests, for those who would like to take a stand by refusing to purchase wood from tropical rainforests.
Various organizations, such as the Forest Stewardship Council, have developed certifying procedures that encourage the use of wood from sustainable forests.
The three major types of forests are based on the age and structure of their trees.
An old growth forest has not been disturbed for hundreds of years.
There are instances in which old growth forests are being deforested.
Old growth forests have a lot of habitats and niches for a lot of organisms.
There are areas where cutting has taken place and a new, younger forest has arisen.
95 percent of the world's forests are naturally occurring, and the remaining forests are known as plantations or tree farms.
Plantations were planted by humans at the same time and are managed to harvest trees for commercial use.
It makes sense that those in the business of forest products would be concerned about finding a way to promote sustainable forest products.
The forest needs to be managed to continually supply humans with wood.
silviculture is the management of forest plantations for the purpose of harvesting timber To create a sustainable yield in this field, humans must harvest as many trees as they can replace.
Two basic management plans attempt to uphold this tenet.
The removal of trees is called clear-cutting.
This is done in areas that support fast growing trees.
This is the most efficient way for humans to harvest trees, but it has major impacts on the habitat.
The removal of trees in an area is calledselective cutting.
The majority of the habitat is in place.
It's not easy to remove these trees from the forest.
In areas with trees that take longer to grow, or if the forester is only interested in one or more specific types of trees that grow in the area, this type of management is more common.
Shelter-wood cutting is an example of a type of management that is not evenly aged.
Some mature trees are left in place to reseed the forest after they are cut down for shelter-wood cutting.
The trees and crops are planted together.
The trees create habitats for animals that prey upon pests that harm crops, and their roots also enrich the soil.
The federal government is the largest owner of land in the United States.
President Lincoln recognized the need to preserve some of the land when he set aside a park in California as a land grant.
The National Park System was created in 1916 to manage and preserve forests.
Wilderness Preservation Areas are open only for recreational activities with no logging permitted, and are one of the ways the federal government controls forested land.
The National Forest System, Natural Resource Lands, and National Wildlife refuges are some of the federal lands that allow logging with a permit.
The laws shown below relate to the federal government's policies on preserving public lands.
There has been an increase in the number of greenbelts in recent times.
The outer edge of a city can be a forested area.
Quality of life for people living nearby can be increased because no one is allowed to build in them.
Limits on growth are put on border cities.
Sometimes satellite towns are built outside the city and connected with the city by highways and mass transportation methods; in this way, we can add green spaces in urban areas.
There are two natural problems in forested areas.
The quality of the food and the number of trees that are available for use can be affected by these.
Humans manage these natural events in many different ways: by removing trees that are not disease resistant, by using chemical and natural pest controls, by inspecting imported trees and tree products, and by developing pest- and disease- resistant species of trees.
There are forest fires every now and then.
You should be familiar with the three major types of fires that occur in the forest.