Chapter #12

#1 – Why are we so unsuccessful in making rats an endangered species?

The main reason I believe that we are so unsuccessful in making rats and endangered species is because they can live in many varied climates and locations. Rats also require little to sustain them, and are able to eat a wide range of food. Another cause of their abundance is evident by their birth rates, which average 8-12 kittens (source: http://www.afrma.org/rminfo7a.htm). With so many births by Does (female Rates), their populations are at an almost constant level of increase without predators, environmental risks, catastrophe, etc. Even if a population risk factor below is evident, there are enough separate populations to cover the losses in another habitat or location.

#2 – What have been causes of extinction in:

a) recent times – the introduction of exotic species(parasites, predators, and competitors of species), the disruption of habitats by human encroachment, intentional hunting or harvesting, and pollution of the environment.

b) Before people existed on earth

1) Population risk – This where low numbers of a species have natural variations in their birthrates. Some reasons cited in the text are the inability to find a suitable mate, due to vast distances, like in the case of the blue whales. Another reason a population may be at risk is due to the habitat that a species lives in. The habitat may only exist in a few places on earth, where proper conditions are abundant enough to propagate the species.

2) Environmental risk – involves a variation in the physical or biological environment.

3) Natural Catastrophe – A sudden change in the environment not caused by humans (fires, earthquakes, major storms, floods on land, and changes in the currents and upwellings in the ocean).

4) Genetic Risk – A detrimental change in the genetic make-up, not caused by external or environmental changes. This occurs in small populations where little genetic variation is present. This risk is characterized by genetic drift and mutations in the gene code.

Chapter #13

#8 – Salmon spawn in freshwater streams that flow through forested areas. How might (a) clear cutting and (b) strip cutting of forests affect the reproduction of salmon?

a) In clear-cutting, reasons for low salmon reproduction can be attributed to altered chemical cycles, increased erosion; decay of dead materials is quicker, which increases nitrogen in the soil, which then leads to soil leeching. With the increase of all of the above events, salmon spawning can decrease.

b) Strip cutting can be less disastrous to the above-mentioned items, which in turn does less harm to fish populations. With more trees and shrubs to prevent erosion, the chemical cycles are maintained in their natural state, dead material decays at a normal rate, thus keeping nitrogen levels in the soil and water low. Leeching of the soils is a byproduct of less logging on lands, in turn making the waters of streams healthier and more conducive to salmon spawning.

Week #10

Ch. 10

#1 – Explain the difference between demand and resource based agriculture. Which characterizes traditional swidden culture?

The difference is that resource based agriculture preserves the environment, while producing as much food as possible. A potential loss of revenue and value is incurred, and indefinite sustainment of a crop is feasible. In demand based agriculture an indefinite sustainment of a crop isn’t the primary motive. Demand based farmers grow food, without regard to the amount of resources in the soil. They either move on after they have leeched the soil of all useable resources or go out of business.

Swidden agriculture is characterized by resource based agriculture because the land is used indefinitely without depleting all natural resources/minerals

#2 – A city dump is filled; it is suggested that the are be turned into a farm. What factors in the dump might make it a good are to farm and what might make it a poor area to farm?

If the landfill was strictly used for non-hazardous bio waste the landfill are has the potential to be highly productive. Other factors affecting the use of the landfill for farmland are the availability of water and pesticide use on adjacent lands. If pesticides were used on adjacent lands the land could be hazardous to produce foods for human consumption. other reasons the landfill would be poor for farming is the large amounts of decomposition of biomass. The decomposition would cause increased levels of nitrogen, which will hinder crop growth. Another factor to consider is the abundance of trace elements. Trace elements in to high of values will render crop lands infertile. Some trace elements would be any of the various heavy metals.

#4- What are advantages/disadvantages of wild game ranching?

Some advantages are the preservation of a species within its ecosystem. Strict accountability of the population is also attainable when game ranches are maintained. Some disadvantages are destroyed habitat outside the protected ranches, encroachment by urban centers. The greatest damage would be caused by over grazing of the lands, or over hunting by predator species in a closed ecosystem, like a park. A cause of over grazing is the over population of a species, well past the maximum sustainable population.

#5 – What is meant by the following statement, “World food problem is one of distribution, not production.”? What are the major solutions to this world food problem?

It means that famine is a local production problem. This is caused by the ability of different areas of the world to produce varying amounts of food. For instance, the US climate and lands are conducive to growing large amounts of food, where as the Central African nations are less able to produce their own food easily. This leads to the second part of the quote about distribution. With food an expensive commodity, getting food to the areas of the world that need it the most is an expensive proposition. With the US already, the leading exporter of humanitarian assistance, there is little else America can do. Until the equitability between the nations that produce food, and the ones with little to share increase across the worldwide spectrum, people will continue to starve and die.

#2 Based on your reading what agricultural and farming practices can be used to produce sustainable yields of crops and livestock?

I believe that to produce sustainable yields the world may have to rely more on genetically modified foods. Since this field of farming is in it’s infancy I believe that yields will surpass that of naturally occurring crops. The world’s farmers also need to be able to farm without using so many chemicals in the form of pesticides and herbicides. I believe there will be a day when a designer chemical will no longer work on our world’s bugs and weeds. Of particular interest worth noting, I found that crop rotation along with field rotation appears to be a feasible alternative to leeching the land dry of it’s important elements and minerals; which also includes water. By rotating crops, and even leaving some native plants within fields, less leaching of minerals occurs, as well as making crops less susceptible to insect damage.

To successfully maintain the quality of livestock without disrupting the environment, I believe farmers with the aid of scientists must come up with a way to prevent the massive spills and the contamination of thousands of miles of rivers and streams each year, from manure spills. To maintain a sustainable livestock population without hurting the environment, I believe that farmers need to consider using a rotational pattern, like that used in some farming communities. By rotating livestock through a series of pens or open areas, then moving them to the next, the land will have greater time to recoup.

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