Part I

Principles of Ecology: Ecosystem

Structure and Function

Never does nature say one thing, and wisdom another.

Juvenal

I. Read the text, explain the main idea of the text:

Albert Camus wrote, “Man is the only creature that refuses to be what he is.” It is too temping to think of ourselves as apart from, and even above, nature. It is too easy to think that technology has made us immune to the rules that govern all living organisms. In the words of the ecologist Raymond Dasmann, however, “A human apart from environment is an abstraction – in reality no such thing exists.” We humans are very much a part of the environment. Our lives are rooted in the soil and dependent on the air, water, plants, and algae. They are subject to the ecological rules that govern all the earth’s living things.

Ecology is the study of living organisms and their relationship to one another and to the environment. Ecology takes the entire living world as its domain in an attempt to understand all organism – environment interactions. Given the vast number of organisms in the world, the realm of ecology is immense.

Our study of ecology will begin with a look at the way life is organized on earth, starting on a grand scale and focusing on the smaller organizational patterns.

The Biosphere.

The part of the earth that supports life is called the biosphere, or ecosphere. The biosphere extends from the floor of the ocean, approximately 11000 meters (36000 feet) below the surface, to the tops of the highest mountains, about 9000 meters (30000 feet) above sea level. If the earth were the size of au apple, the biosphere would be a thin layer only about as thick as its skin.

Life forms are scarce at the far extremes of the biosphere: on the highest mountaintops only inert spores of bacteria and fungi can be found, and on the deep ocean floor few organisms can survive.

Life exists mostly at the intersection of land (lithosphere), air (atmosphere), and water (hydrosphere). And from these vast domains come the ingredients that make life possible – minerals from the soil, oxygen and carbon dioxide from the air, and water from oceans and lakes.

The biosphere – this living skin of planet earth – is, in many ways, like a sealed terrarium. If carefully set up with soil, water, plants, and a snail or two, a sealed terrarium operates without interference; water is reused over and over as are minerals. The terrarium is a sustainable system less complicated but much like the biosphere, which recycles water, oxygen, carbon, and other substances over and over in a perpetual cycle. Only one thing must come from the outside for life to continue in the terrarium and in the biosphere: sunlight. Unlike the materials that make life possible, sunlight energy cannot be recycled.

Because the biosphere recycles all matter, it is called a closed system. The closed nature of the biosphere makes all species throughout all time cousins of sorts: for example: the atoms in your body may some day be part of the great leaders or the citizens of a society living centuries in the future.

The first law we glean from our study of ecology is that life on earth is possible only because of the recycling of matter. It is a rule, many ecologists believe, that we humans break at our peril and the peril of those yet to come.