Topic 3: The Human Population

1. I belive that Dr. Ehrlich is correct. The United States produces little positive products compared to the negative environmental impact it creates. As one country, and one without 6 billion people, we create 1/3 of the worlds pollution. That means that every other country in the world combined makes up the rest of that 2/3 of the pollution.

US citizens demand more, use more, and waste more in their everyday lives. Think about how much trash you throw away daily, how much water you use to flush a toilet or just to rinse your hands before meals. It is easy to see the truth in Dr. Ehrlich's statement that a baby born in the us will cause 1,000 the damage as someone born in a less developed country.

2. I am very much in favor of China's campaign to reduce birth rates. Many of their citizens live in crowded urban areas, and in rural areas they are of subjected to less than sanitary living conditions. In overcrowded urban areas, resources can be difficult to find, and basic utilities such as schools, water supply, and many other needs are stretched thin.

With nearly 1.3 billion people, China has the right idea to campaign for a reduced birth rate. Methods such as sexual education, providing methods of birth control, economic incentives, and female empowerment are all great ways to go about it. Education will, in addition to reducing birth rates, hopefully lower the transmissiion of STD and other diseases. Providing birth control puts women more in control and opens up doors to opportunities they may not have had before. Economic incintives can help people out in tough times, and can also stimulate the economy. All in all China has the right idea. Because when one has 1.3 billion people, and when world population has reached 7 billion, it may be time to make a little breathing room and give the earth a break.

Week 1: Ecology- Ecosystem Interactions

1. One interaction between species that I see everyday is that between horses and grass, and among horses themselves. Nearly every morning I pass at least one horse pasture on my way to school. Usually by then the horses are out and about, eating hay and grass. The grass is a producer, while the horse (and occasional cow) is the consumer.

The grass creates its own food using water, sunlight, and carbon dioxide in the process photosynthesis. During photosynthesis the grass makes carbohydrates with which to feed itself. Along with making food, the grass also releases oxygen into the air during photosynthesis. This oxygen makes up part of the atmosphere. Because grass makes its own food, it is considered to be autotrophic, or a self feeder.

The horses on the other hand do not make their own food. Instead they consume the grass to get their energy for life processes. Because of this, they are considered to be heterotrophic, or dependent on others for food. Without the grass, horses would have nothing to eat and less oxygen to breathe. Therefor they are dependant on the grass in a way that the grass is not dependent on them.

A second interaction I see each day is that between birds and worms (or whatever type of bug they happen to be digging for at the time). Our backyard is rather large, and when the dog isn’t out birds like to hunt for assorted worms and bugs in the grass. Their relationship is much like that of the cows and grass, just higher in the food pyramid.

Worms and bugs are consumers; they depend on producers for their food much like the horses above. Worms and bugs also often depend on the plants in their environment for shelter, not just food. When the worms and bugs consume the producers, the amount of energy available decreases. They are then eaten by the bird, who receives even less energy than the worm or bug did from the producer.

Birds are secondary consumers in this food chain, while the worms and bugs are the primary consumers. The worms and bugs are the first to receive energy by consuming other organisms, while the birds are the second to receive energy by consumer other organisms. As you move up the food chain, the amount of energy available to the next trophic level decreases as does the number of that given organism in the ecosystem. It takes more and more energy to support life as one moves up the food pyramid, which means that more energy sources in the levels below must be consumed, which in turn means that fewer organisms can be supported without putting a strain on the environment.

Both of the above relationships could even be put into a food web, as I am sure there are birds in the horse pasture environment as well. The horses and worms/bugs would then both be sorted into the same trophic level of “primary consumers”. The birds , however, remain in the position of secondary consumers.

The ecosystem that makes up my back yard consists mainly of: bugs, squirrels, birds, a dog, apple and pear trees, berry bushes, an overgrown arbor, and the pine trees that line part of the property (and of course, me and my family but not really for this purpose). The non living components of the ecosystem are: the arbor, the deck/patio, and swing set and fort, and the swimming pool.

The type of bird that ventures into my yard varies from day to day, though it is generally a few robins and a cardinal or two. They build nests in the arbor, the fruit trees, and the crape myrtle bushes on occasion. For food, the birds hunt for bugs and worms in the ground (secondary consumers!), or if they’re humming birds, they may drink from the feeder we occasionally put up.

Squirrels interact with the backyard ecosystem in a manner similar to that of the birds. They enjoy taking the fruit off our apple trees and playing in the pine trees along the edge of the yard (we suspect there is a nest somewhere, though we’ve yet to find it). Their purpose, other than taking our fruit, very much seems to be to amuse the dog.

Our dog, Smurf, is a large part of the backyard ecosystem, literally. He fertilizes the grass, and chases the birds and squirrels (sometimes posing a danger to bird nests when he paws at the trees). By chasing the squirrels he helps protect the fruit produced by the fruit tree from being carried off. He also has a tendency to mess with the plants on the arbor, partially destroying a possible home for the birds. Smurf is most definitely a consumer (of anything edible).

The flora of the backyard ecosystem plays many roles. The fruit trees provide birds and squirrels with food, and occasionally a home. They also provide my family with fresh produce. Our crepe myrtle bushes provide shade for the dog, and homes for the birds. Further back, the berry bushes provide my family with even more fresh produce and plays home to various bugs (such a June bugs that closely resemble Godzilla). All of the plants are producers, and they make their own food through photosynthesis.

Halfway back in the yard is an arbor covered in out of control jasmine bushes, and flanked by roses .The arbor and its surrounds play home to birds and bugs (secondary and primary consumers respectively). It also provides food for the various bug, insects, and other creepy-crawlies in the ecosystem.

Even further back, along the back property line and fence, is the line of pine trees. Many a bird and squirrel has built a nest in the trees there. I don’t imagine that the pine trees produce many tasty meals for anything other than termites, but they do make their own food through photosynthesis just as the arbor and surrounds plants do.

Sadly, our somewhat neglected pool is nearly an ecosystem of its own. It is an aboveground affair, making the water warm and livable for algae in the warm and cold months alike (except when it freezes occasionally in the winter). It will turn green when not properly maintained, and is a magnet for mosquitoes during the warm months.

As for the impact my family has on this backyard ecosystem, it is a rather large one. My dad likes to keep the grass trimmed in the event we have company. On a yearly basis we have to cut back the berry bushes, fruit trees, crepe myrtles, and arbor plants. This reduces the amount of possible living space for birds and squirrels, but also makes their living in the plants possible as it keeps the plants healthy and growing for another year. We have also altered the plants in the backyard by planting different plants each year and building different structures, such as our deck and the swing-set.