How Do We Affect Equilibrium?

Describe ways that human activities can change the equilibrium in ecosystems. Explain how changes in technology can cause significant changes, either positive or negative, in environmental quality and carrying capacity. Describe ways that human activity can alter geological and chemical cycles as well as food webs and energy pyramids.


Human Activities and Equilibrium

Farming in Canada

Humans are the only species on Earth that uses both living and non-living things to take care of most of our everyday functions. There are other species that use tools; primates use sticks to dig ants out of their holes; blue jays can use leaves to dig food out of places that are hard for them to reach. However, no other species uses technology like we do, which means that we affect the Earth in ways that other species do not.

Among other things, humans use land for farming, mining and timber (trees). Since we have chosen a few crops to farm over other crops, we have changed the equilibrium of the ecosystems around us. Corn is a good example of a crop that we use all of the time. Of course, we get corn on the cob, popcorn, cornmeal, grits and corn syrup. But did you know that we also use corn to get oil, ethanol, buildiing materials, paint, various food ingredients, shoe polish, cosmetics and even toothpaste? Can you imagine what our society would be like without any one of these products? There is so much corn grown on Earth that other species have adapted to feed off of corn and other crops that we farm.

Strip mining

The first farmers on Earth had small farms, and changed where they farmed every season. Now, we have farms where the same crop is grown every year, in the same place. This has a negative impact on the soil because minerals are removed from the soil and there is not enough time for decomposers to get those minerals back into the soil. This means that farmers have to use chemical fertilizers to replace the minerals, which causes excess nitrogen runoff. The high levels of nitrogen disrupts the nitrogen cycle and interrupts plant and animal growth elsewhere.

One way that farmers can make sure that the soil is healthy is crop rotation. When a farmer rotates crops, the farmer does not plant the same crop every year, and they also don’t plant crops in every plot every single year. By letting natural decomposers add minerals back into the soil, it reduces the amount of minerals that need to be artifically added in by the use of fertilizers.

Timber felling

When we mine resources from the Earth, we take them away from the Earth and then use them in products. Those resources don’t get returned to where they are; the land does not get end up the way we found it. We are changing equilibrium in two major ways when we mine: certain resources are unable to be used by plants and organisms are driven off of the land they previously used. Furthermore, when we mine resources like coal, we then burn that coal. The coal is gone, and we have put carbon dioxide and other gases into the atmosphere. This means that more plants need to do more work in order to keep the amount of carbon dioxide in equilibrium.

Timber is often taken from forests that can’t grow trees as fast as they are cut down. This is known as an unsustainable behavior, which is behavior that cannot continue because it is destructive. In order to make sure that forests aren’t completely destroyed, there are several ways to get timber but not destroy an entire forest. However, current human society uses wood for construction, paper products, fuel, tools and even packaging. Even though we do plenty of recycling of wood materials, new wood needs to be obtained from the environment.

Questions
Remember
1. Name one unsustainable behavior for each of farming, mining and timber.
2. Find the nutrition labels for at least two foods or beverages. What are at least three corn products that you've used or eaten? In what form was each one in?
3. What is the effect of one of the mentioned unsustainable behaviors on the energy pyramid?
Put it together
4. What are at least two things that you think our government can do to support farmers who help ecosystems by practicing sustainable behavior?
5. Think of two ways that timber can be obtained without destroying forests.
Think about it
6. Write a letter to a farming, mining or timber company asking them to practice sustainable behavior. The letter must be two paragraphs of at least five sentences each and must include: reasons why their behavior is unsustainable, reasons why you are concerned, what effect their behavior has on food webs and energy pyramids, and what they can do to improve their techniques. You cannot tell them to stop completely!
Review

8. List at least four genetic characteristics.
9. What can radiometric dating tell scientists?
10. Name three crops that you eat in some form.
Resource Misuse

Find an article which involves the misuse of natural resources. Answer:

  1. What is the natural resource?
  2. How is it being misused?
  3. Why is it being misused?
  4. In the form of a one-paragraph letter to an interested leader (e.g., mayor, senator, representative, president, etc.), explain what should be done to fix the situation!
Natural Resource Usage Tracking

For one day, keep track of the following:

  1. Everything you eat
  2. Everything you throw away
  3. All transportation that isn’t your feet
  4. Anything you use at school, at home or elsewhere (TV, pencil, pen, phone, etc.)
  5. Anything you purchase (not listed from above)

Summarize in one paragraph of 5 – 7 sentences what natural resources you seem to use the most of and why you think that is. What could you do to reduce your usage of natural resources?

Niches and Equilibrium

Background

As the environment changes, living things change in response to that environment. In general, we can say that the environment puts pressure on organisms to adapt. If the environment is cold, then an organism that cannot make its own heat will have trouble surviving; if the environment is hot, then an organism that cannot get rid of its own heat will have trouble surviving. This idea is one of the basic ideas of evolution and is responsible for the diversity of living things we see around us!

We may not always think about it, but there are hundreds of different ecosystems (types of environments) around us all of the time. We tend to think of ecosystems as being big places that take up a lot of space, like a jungle, desert, mountain or river. But ecosystems can be much smaller, like the surface of a dog’s body, the inside of your small intestine, or the inside of an abandoned shell on the beach. Each of these environments has many living things that interact with each other under certain environmental conditions that many organisms cannot live in.

In fact, living things in an ecosystem are usually so well-adapted that they are in what’s called a niche, which is a specific role and place that an organism occupies. Those niches don’t change as long as organisms are in equilibrium (or balance) with each other. If there is a change in the environment, then this can cause a disequilibrium (or imbalance) which can change the niches. For example, suppose that a factory dumps leftover paint into a river. Bacteria in the river have adapted to this pollutant by breaking down the paint and using it as food. But let’s say that the government steps in and stops the factory from dumping the leftover paint; suddenly, those bacteria have no food and die. This means that their niche has disappeared (even though the river is still there) because their food source is gone, and it could cause disequilibrium in the ecosystem if there was another organism eating those bacteria.

For this lab, we will be going to visit several different ecosystems (hopefully in Forest Hill Park) and count the diversity of living things that we find there. We will figure out the niches and the equilibrium of the ecosystem using some simple methods.

 

Materials

  • Fresh water
  • Salt water
  • Flashlight
  • Opaque plastic sheeting (25 cm x 25 cm)
  • Hot pack
  • Cold pack
  • Clipboard
  • Pencil / pen
  • Dark marker
  • Paper
  • Insect guide
  • Thermometer
  • Meter stick
  • String (4 m)
  • 4 stakes
  • Trowel

 

Methods

  1. Go to the site. At the site, you will be assigned an ecosystem among all of the different ecosystems available. You will create different environments within this ecosystem where you will change the qualities of the environment.
    1. Stake off an area that is 1 square meter and use the string to section off this square meter. Along the string, make a mark with the dark marker every 25 cm.
    2. On your paper, make a diagram of the area that you just made. Separate the area into 16 equal squares (4 rows and 4 columns). These squares represent the sizes of the squares that you just made with the dark marker every 25 cm. Label these squares on your paper from 1 to 16, going from left to right, then top to bottom:

 

1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
    1. In square #1, saturate the ground with the fresh water and label this square on your paper “fresh water”. Make sure that the water stays within the square. In square #4, saturate the soil with the salt water and label. In square #6, turn on the flashlight and point it towards the ground, and label square #6 “flashlight”. In square #11, put the opaque plastic sheeting and label it on your paper. In square #13, activate and place the hot pack on the square, labeling it on your sheet. Finally, for square #16, activate and place the cold pack on the square, labeling it on your sheet.

Abiotic factors in the environment

 

  1. Observe and record the following abiotic qualities of the environment:
    1. How much water is available from precipitation
      1. Is the area shaded?
      2. Does the area seem to have a stream flowing to it when it rains?
    2. How much water is available from the ground
      1. Is the area wet right now?
      2. Is the area by a stream, river or lake?
    3. How much light is received by the area
    4. The average temperature of the area
      1. Does there seem to be cooler or warmer air that blows into this area?
      2. Is the area in direct sunlight?
      3. Is there another temperature influence in this area?
    5. Describe the other nonliving (abiotic) parts of the ecosystem
      1. How many and what size rocks are there?
      2. Is there soil? Describe the soil, if present.
      3. Is there anything else that is not a living (or dead) thing that is a part of this ecosystem? Describe.
  2. Now you will describe as many of the living things in the ecosystem that you can find. You can include birds and mammals if there’s clear evidence that they are usually in this ecosystem. Don’t exclude them simply because they don’t want to be in the ecosystem because you are there!
    1. Count how many different plant species there are. You don’t have to know what each species is called, you just need to count how many different ones there are. You can count any seeds or leaves that have fallen, or any trees that are directly above your ecosystem.
    2. Count the number of different animal species there are. Insects will most likely be the most numerous in your ecosystem, so make sure to get an accurate count by digging several inches down into some of the squares that you are not experimenting with.
  3. Since you have left the six squares that you experimented with alone for some time now, go back to those squares and make some observations. Answer the following questions for each of squares #1, 4, 6, 11, 13 and 16.
    1. How did your experiment affect the abiotic factors?
    2. How did your experiment affect the biotic factors?
      1. Specifically, how did it affect the plants?
      2. How did it affect the insects? Which insects were attracted by the experiment, and which insects fled from the experiment?

 

Analysis

  1. For each of squares #1, 4, 6, 11, 13, and 16:
    1. How did the experiment change the equilibrium of the ecosystem?
    2. Did the experiment add to or remove niches from this ecosystem?
    3. For any insects that were attracted to the square, what features of those insects caused them to be attracted to it?
    4. For any insects that fled from the square, what features of those insects caused them to flee from it?
  2. Which of the six factors that you tested caused the most disequilibrium? Why?
  3. Which of the six factors that you tested caused the ecosystem to stay in equilibrium the most? Why?