Unit 5 Review Book Flashcards
(25 cards)
Tragedy of the Commons
When people talk about managing common property resources such as air, water, and land, the “Tragedy of the Commons” often comes to mind.
This is an important concept introduced by the English economist William Forster Lloyd in 1833 and later applied to the field of natural resource management by Garrett Hardin in a 1968 paper published in Science magazine.
In his paper, Hardin referenced the example used by Lloyd, in which a piece of open land, a commons, was to be used collectively by the townspeople for grazing their cattle.
Each townsperson who used the land continued to add one cow or ox at a time until the commons was overgrazed.
Hardin eloquently says, “Each [person] is locked into a system that compels him to increase his herd without limit—in a world that is limited. Ruin is the destination toward which all [people] rush, each pursuing his own best interest in a society that believes in the freedom of the commons. Freedom in a commons brings ruin to all.”
The tragedy of the commons serves as a foundation for modern conservation.
Conservation and preservation
Conservation is the management or regulation of a resource so that its use does not exceed the capacity of the resource to regenerate itself.
This is different from preservation, which is the maintenance of a species or ecosystem in order to ensure their perpetuation, with no concern as to their potential monetary value.
how human economics influence how we interact with the Earth’s resources.
Bear in mind that natural resources are drawn from the biotic and abiotic components of functioning ecosystems, and so our exploitation of those resources necessarily affects the functioning of those ecosystems. Human impact in turn affects the ability of those ecosystems to continue providing the resources. When we humans exploit a resource for the functioning of society or for economic gain, we are placing an economic value on it; therefore, natural resources are described in terms of their value as ecosystem capital or natural capital.
Renewable resources
Resources that can be regenerated quickly, such as plants and animals.
Water is an abiotic substance that’s renewable because it can be used over and over again and because sources of water are replenished naturally through the water cycle. Certain natural sources of energy—such as the sun, the wind, and the tides—are also considered renewable because their occurrence in nature is perpetual and not depleted with use.
The time necessary for hardwood trees to mature (about 50 years) is widely considered the crossover point from renewable resources to nonrenewable resources.
But, in purely practical terms, a resource is renewable if it can be replenished within the time it takes to draw down its supply.
Bear in mind that even renewable resources must be carefully managed in order to conserve their sources and insure an ongoing supply.
Nonrenewable resources
are resources that do not regenerate quickly, such as minerals and fossil fuels. Nonrenewable resources are typically
formed by very slow geologic processes, so we consider them incapable of being regenerated within the realm of human existence.
There are a couple more terms you should know before we dive into our review of the major resources available to humans on Earth; these are consumption and production.
The consumption of natural resources refers to the day-to-day use of environmental resources such as food, clothing, and housing.
On the other hand, production refers to the use of environmental resources for profit.
An example of this might be a fisherman who sells his fish in a market. Got those terms? Let’s move on.
AGRICULTURE
How do resources relate to your dinner?
Well, 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 ever- increasing population, fewer people than ever in the history of the United States now farm the land. Why is this?
The short answer is that it has a lot to do with increasing urbanization and industrialization.
Now that machines are readily available to work the land and harvest crops, farms have become more like factories—currently only 2 percent of the United States population is directly employed in agriculture.
Farms in the United States today are quite a bit larger than farms of the past.
The average farm is 434 acres, or a little less than an American football field, while in the early 20th century the average farm size was about 100 acres.
The use of machinery in farming has allowed farmers to work more land more efficiently; however, one of the drawbacks of the machinery is the amount of fossil fuel needed to power it. As the cost of fuel rises, the cost of food will also rise.
This rise in agricultural productivity can be tied to new pesticides and fertilizers, expanded irrigation, and the development of new high-yield seed types.
However, it has also resulted in a significant decrease in the genetic variability of crop plants and led to huge problems in erosion.
Traditional subsistence agriculture
Throughout most of history, agriculture all over the world was such that each family grew crops for itself, and families relied primarily on animal and human labor to plant and harvest crops.
This process is called traditional subsistence agriculture, and it provides enough food for one family’s survival.
Traditional subsistence agriculture is currently practiced by about 42 percent of the world’s population, predominantly in developing nations.
Such intensive mixed farming allows people to settle permanently and subsist without having to migrate seasonally.
Extensive subsistence agriculture results in low amounts of labor inputs per unit of land.
Slash-and-burn
One form of traditional agriculture that’s still practiced in many developing countries today is a method called slash-and-burn, a practice that dates back to early humankind and is especially common in the tropics.
In slash-and- burn, an area of vegetation is cut down and burned before being planted with crops.
Tropical soils are typically thin and poor, and whatever fertility they hold is rapidly depleted by the deforestation and subsequent farming.
Therefore, the farmer must leave the area after a relatively short time and find another location to clear.
Practiced indiscriminately on a broad scale, slash-and-burn agriculture has led to rapid deforestation of the tropical rainforest.
The Green Revolution
occurred in the 1950s and 1960s, is generally thought of as the time after the Industrial Revolution when farming became mechanized and crop yields in industrialized nations boomed.
Such innovations also allowed farmers in the Third World to increase crop production on small plots of land.
Later, there was a second green revolution, which promoted integrated pest management and organic methods, such as fertilizers that are not synthetic.
One factor that contributed to the Green Revolution was an increase in the use of fertilizers and pesticides.
Interestingly, when the non-native settlers (the first white settlers) planted their first corn crops, certain tribes of Native Americans taught them to plant fish leftovers (the inedible parts of the fish) along with the corn seed.
The fish acted as a natural fertilizer for the crops.
As you can see, manures and other organic materials have been used as fertilizers by farmers for many years.
However, the development of inorganic (chemical) fertilizers brought about the huge increases in farm production seen during the Green Revolution.
It’s estimated that if chemical fertilizers were suddenly no longer used, then the total output of food in the world would drop about 40 percent!
Issues with increased use of chemical fertilizers
Of course, there are downsides 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 the fertilizers; and the fact that once the fertilizers are washed into watersheds, they are dangerous pollutants.
Issues with increased use of pesticides
Likewise, the increased use of pesticides in the Green Revolution has significantly reduced the number of crops lost to insects, fungi, and other pests, but these chemicals have also had an effect on ecosystems in and surrounding farms.
It’s estimated that the average insect pesticide will only be useful for 5–10 years before its target pest evolves to become immune to its effects through natural selection; therefore, new pesticides must constantly be developed.
However, even with this constant development, crop loss due to pests has not decreased since 1970, although the use of pesticides has tripled!
Because the use of pesticides is so prevalent in the United States, Congress passed the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) in 1947 and amended it in 1972. (DONT HAVE TO MEMORIZE LAW)
This law requires the EPA to approve the use of all pesticides in the United States.
Integrated Pest Management
When dealing with pests, integrated pest management (IPM) uses a combination of several methods and is a more environmentally sensitive approach than chemical pesticides.
Rather than try to get rid of every single pest on the farm, IPM tries to keep the pest population down to an economically viable level.
Some of the methods include introducing natural insect predators to the area, intercropping, using mulch to control weeds, diversifying crops, crop rotation, releasing pheromone or hormone interrupters, using traps, and constructing barriers.
People using IPM consider using chemical pesticides only in the worst-case scenario.
While IPM has great advantages in terms of reducing the risk that traditional pesticides pose to wildlife, water supplies, and human health, it can be complex, requiring a lot of work to implement, and it can also be quite expensive.
Irrigation
Another major contributor to the increased crop yields seen in the Green Revolution was advanced irrigation techniques, which allowed crops to be planted in areas that normally would not have enough precipitation to sustain them.
would not have enough precipitation to sustain them.
Salinization of soil, leads to increased use of water,depletion of aquifers
However, repeated irrigation can cause serious problems, including a significant buildup of salts on the soil’s surface, which makes the land unusable for crops.
To combat this salinization of the land, farmers have begun flooding fields with massive amounts of water in order to move the salt deeper into the soil.
The drawback to this, however, is that the large amounts of water can waterlog plant roots, which will kill the crops, and this process also causes the water table of the region to rise.
Furthermore, the water for these irrigation farms comes from underground water tables called aquifers.
These aquifers are being depleted at a rapid rate and large-scale, grain-producing countries such as India, China, and the United States are examples of those caught in this predicament.
Another drawback to the Green Revolution resulted from the dramatic increase in irrigation worldwide; the largest human use of freshwater, 70%, is for irrigation!
Irrigation methods
furrow
flood
spray
drip
Furrow irrigation
which involves cutting furrows between crop rows and filling them with water, is inexpensive but loses about 1/3 of the water used to evaporation and runoff.
Pros
-Low investment
-High-sediment water can be used
-Allows for some precision of application
Cons
Not efficient on sandy soil
-Difficult to apply small amounts
-33% of water lost to evaporation
-Soil erosion
Flood irrigation
involves flooding a field with water, can lead to waterlogging and loses about 20% of the water to evaporation and runoff.
Pros
-easy
-inexpensive
-mechanization not required
Cons
requires water nearby
-not for all plant types
-land must be graded
-levees needed
-waterlogging/salinization
Spray irrigation
involves pumping water into spray nozzles and spraying fields; it only loses about 1/4 of the water but requires energy to run and can be expensive.
Pros
-Precision application
-Supplements can be introduced into the water
-Efficient: 25% or less lost to evaporation
-Can be programmed to run at certain times of day
Cons
-Larger up-front cost than flood/furrow irrigation
-Can include machinery run with electricity/fossil fuel use
-Nozzles can clog
-Pivot systems can wear ruts in soil
Waterlogging, salinization of soil
if too much water is left to sit in soil, it can raise the water table of the groundwater, causing plants to have trouble absorbing oxygen through their roots.
Additionally, over-irrigated soils undergo salinization.
In salinization, the soil becomes water-logged; when it dries out, salt forms a layer on its surface.
This eventually leads to land degradation.
In order to combat this problem, researchers have developed drip irrigation, which allots an area only as much water as is necessary and delivers the water directly to the roots using perforated hoses that release small amounts of water: this is far more efficient, with only about 5% of water lost to evaporation and runoff, but is more expensive.
Benefits of GMOs
The third and last significant contributor to the Green Revolution was the introduction of genetically engineered plants.
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/drought/pest resistance, faster growth, and higher crop yields.
One beneficial example of this method was the development of golden rice, which contains vitamin A and iron.
The introduction of this rice addresses two of the serious health problems that are seen in developing nations: vitamin A deficiency, which can result in blindness and other serious health problems; and iron deficiency, which leads to anemia.
Problems with GMOS
However, there are many problems that arise from genetically modified organisms (GMOs), as well.
Therefore, GMOs have become a very controversial topic.
Because this is a relatively new technology, scientists don’t know exactly how GMOs will affect the planet ecologically.
Genetically modified plants discourage biodiversity, which may harm beneficial insects and organisms, could pose new allergen risks, may increase antibiotic resistance, and could encourage the rise of new pesticide- resistant pests.
Many farmers and consumers are also concerned that cross- pollination can contaminate other crops, including organic farms that choose not to use GMOs, or cause unwanted mutations with unknown results.
Monotonous Monoculture
Believe it or not, three grains provide more than half of the total calories that are consumed worldwide!
These three crops are rice, wheat, and corn, and the phenomenal increase in the yield of these crops was a result of genetic engineering. G
enetic engineers discovered a way to cause plants to divert more of their photosynthetic products (called photosynthate) to grain biomass rather than plant body biomass.
It’s estimated that of the roughly 30,000 plant species that could possibly be used for food, only 10,000 have been used historically with any regularity.
Today, 90 percent of the caloric intake worldwide is supplied by just fourteen plant species and eight terrestrial animal species! In other words, today’s agriculture represents a major reduction in agricultural biodiversity.
Much of the farming that occurs today is characterized by monoculture.
In a monoculture, just one type of plant is planted in a large area. Monocultures became common in the era of early political civilizations, when farms produced a staple crop in order to feed whole societies and armies.
As we discussed earlier, this has proved to be an unwise practice for numerous reasons.
Plantation farming, which is practiced mainly in tropical developing nations, 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.
Soil fertility, arable soil
In order to be able to grow all of the foods that humans consume, we must have enough arable—suitable for plant growth—soil to meet our agricultural needs.
Soil fertility refers to soil’s ability to provide essential nutrients, like nitrogen (N), potassium (K), and phosphorus (P), to plants.
Humus (remember, it’s in the O layer!) is also an extremely important component of soil because it is rich in organic matter.
Remember that soils composed of a balanced mixture of the three particle sizes (clay, silt, and sand) are described as loamy, and these types of soil are considered the best for plant growth.
Another important characteristic for agricultural purposes is soil structure, or the extent to which it aggregates or clumps.
Soil aggregates are formed and held together by such substances as clay particles and organic matter—plants and roots, the root-like filaments of fungi, and sticky substances released by bacteria and fungi.
The most fertile soils have good structure.
Soil is considered a non-renewable resource due to the great length of time required to form arable soil.
It takes 500 to 1,000 years to form a single inch of soil, and at least 3,000 years to form enough fertile soil to support crop growth.
Unfortunately, certain agricultural activities can change the texture and structure of soil; for example, repeated plowing tends to break down soil aggregates, leaving “plow pan” or “hard pan,” which is hard, unfertile soil.
