What is Ecology?
This photograph is of cattle grazing in a New Mexico pasture. Study the scene carefully, keeping in mind that its location, New Mexico, is quite different from, say, Michigan, Vermont, or Wyoming. Many plants and animals besides the cattle live in this pasture. You would recognize some of these; others may take some thought on your part to discover. For instance, quail might nest beneath the shrubs in the background. A lizard might rest in the shade of the yucca plant. Long tapeworms might be found in the intestines of the cattle. List any animals and plants you think might live in this New Mexico pasture. Feel free to include both organisms that live here permanently and those that might be common visitors.
Living Things Present in Pasture
1. 11.
2. 12.
3. 13.
4. 14.
5. 15.
6. 16.
7. 17.
8. 18.
9. 19.
10. 20.
Ecologists are interest in studying the living things you listed and others as well. They would study not only the grasses and shrubs but also all other plants and animals inhabiting or visiting the pasture. They would include the cattle as well as the flies, ticks, and parasitic worms that affect the cows. Ecologists would include the ants, earthworms, and beetles that burrow in the soil. The lizards and rodents that scurry among the grasses would be objects of study as well as the snakes and hawks that eat these animals. Ecologists would even study people, since the domestic cattle are evidence of people’s presence in this pasture.
Although ecologists would identify as many living things as possible, this would not be their only purpose. As you listed the animals and plants, you probably though of them in terms of where they lived in the pasture or what they were doing there. Ecologists try to do the same. For example, burrowing insects are associated with the soil. Thir burrows make air spaces in the earth, and their waste materials add nutrients to the soil. The quail and the shrubbery are related to each other, also. Quail might nest beneath the shrubs and hunt for insects harmful to those shrubs.
When studying living things, ecologists might ask the following questions. Try your hand at answering them.
· In what ways are the cattle dependent on the grassland? Explain your answer.
· How is the grassland dependent on the cattle?
· How might the cattle harm the grassland?
· In what ways do the plants in the pasture compete with each other?
· What animals might compete with the cattle for food?
· Why might this competition occur?
· What is the main purpose of raising cattle?
· What might this environment look like in 10 years if humans and their cattle were removed?
Of course, the grass is the main source of food for the cattle. Without it the animals would die unless humans supplied hay and silage in its place. Cattle depend almost totally on grass and other herbs. People’s dependence on cattle, however, is only partial, since they eat other foods besides beef. Cattle can overgraze an area and destroy it as a food source. Whether they did or not would depend on the size of the cattle population. The waste materials from the cattle can also enrich the soil. Such relationships are the types of data the science of ecology deals with.
Ecologists help explain the natural relationships that exist between the plants and animals in our world. These relationships are called interactions. When organisms interact, they affect one another and bring about some type of change. Cows interact with grass. One piece of evidence of this interaction relationship is a size and weight gain in the cow. Cattle manure interacts with soil as evidenced by increased fertility of the grazing land. Ecologists’ study of interactions usually includes the role of people, since people are probably the most influential change agents on earth.
There is one more item to add to your understanding of what ecology is. You are aware that the types of plants and animals found in the New Mexico pasture are very different from those found in Florida. What causes the differences? What factors might influence the kinds of living things that exist in a certain area? Give three examples below:
1.
2.
3.
If you were to study the geographic location and climate of this area of New Mexico, you would discover that it is characterized by a certain elevation, annual rainfall, temperature range, soil type, humidity, and land formations such as the mountains in the background of the photograph. Ecologists have discovered that those nonliving factors, called abiotic factors, greatly influence living things and interact with them. Often one abiotic factor may influence another abiotic factor, which in turn influences living things. For example, there is a decrease in temperature as elevation increases. There is an increase in precipitation as elevation increases. This lowered temperature and increased precipitation interact and cause a shorter growing season. These interacting abiotic factors will limit both the types and sizes of plant life able to survive at upper elevations. Soil type influences the amount of rainfall that can be absorbed. The amount of available moisture in the soil will influence the plants that can grow there. What other examples can you think of?
By putting together the three parts we have just discussed – living things, abiotic factors, and the interactions that exist between them—you should now have a good working definition of ecology.