3.1.1 - biosphere

Concept of the biosphere

In the past scientists have studied the various parts of the Earth. They have looked at botany (plants), zoology (animals), geology (rocks), and physics(forces), but few have studied how all of these work together. Now we are discovering that the Earth is much more than a bunch of parts. It is a whole.The Earth is a whole system that works together. This means that there is an interconnection between all of Earth’s living and non-living parts.Everything works together in important ways. Scientists divide the Earth’s System into four sub-systems:

•biosphere (life)

•lithosphere (land)

•hydrosphere (water)

•atmosphere (air)

To see how the sub-systems of the Earth interact, watch the video: The Earth as a System: http://www.oercommons.org/courses/earth-as-a-system/view

Biosphere

From: http://cnx.org/content/m16693/latest/?collection=col10548/latest

The biosphere is the region of the earth that encompasses all living organisms: plants, animals and bacteria. It is a feature that distinguishes the earth fromthe other planets in the solar system. "Bio" means life, and the term biosphere was first coined by a Russian scientist (Vladimir Vernadsky) in the 1920s.Another term sometimes used is ecosphere ("eco" meaning home). The biosphere includes the outer region of the earth (the lithosphere) and the lower regionof the atmosphere (the troposphere). It also includes the hydrosphere, the region of lakes, oceans, streams, ice and clouds comprising the earth's waterresources. Traditionally, the biosphere is considered to extend from the bottom of the oceans to the highest mountaintops, a layer with an average thickness ofabout 20 kilometers. Scientists now know that some forms of microbes live at great depths, sometimes several thousand meters into the earth's crust.

Nonetheless, the biosphere is a very tiny region on the scale of the whole earth, analogous to the thickness of the skin on an apple. The bulk of livingorganisms actually live within a smaller fraction of the biosphere, from about 500 meters below the ocean's surface to about 6 kilometers above sea level.

Dynamic interactions occur between the biotic region (biosphere) and the abiotic regions (atmosphere, lithosphere and hydrosphere) of the earth. Energy, water,gases and nutrients are exchanged between the regions on various spatial and time scales. Such exchanges depend upon, and can be altered by, theenvironments of the regions. For example, the chemical processes of early life on earth (e.g. photosynthesis, respiration, carbonate formation) transformedthe reducing ancient atmosphere into the oxidizing (free oxygen) environment of today. The interactive processes between the biosphere and the abiotic regionswork to maintain a kind of planetary equilibrium. These processes, as well as those that might disrupt this equilibrium, involve a range of scientific andsocioeconomic issues.

The study of the relationships of living organisms with one another and with their environment is the science known as ecology. The word ecology comes fromthe Greek words oikos and logos, and literally means "study of the home." The ecology of the earth can be studied at various levels: an individual(organism), a population, a community, an ecosystem, a biome or the entire biosphere. The variety of living organisms that inhabit an environment is ameasure of its biodiversity.