The Concept of Biosphere and Its Structure

The term "biosphere" was introduced in 1875 by the Austrian scientist E. Zyuss. The doctrine of biosphere as a complex multicomponent planetary system was created by V. I. Vernadsky.

Biosphere — the sphere of life on Earth — includes:

· Troposphere — a surface layer of atmosphere (its height is up to 25 km)

· Ground — lithosphere (its depth is up to 10 km)

· Hydrosphere (depth of oceans is up to 12 km).

Ecosystem is a set of organisms interacting with each other, as well as with the environment, in which they live.

Any ecosystem consists of two parts:

The 1st part is called biocenosis. It includes all living organisms of ecosystem.

The 2nd part is called biotope. It is a part of the earth surface with particular physicochemical properties, on which biocenosis lives.

Types of Ecosystems

· Microecosystems — a small stream, glade.

· Mesoecosystems — a sea, wood, pond, river.

· Macroecosystems — an ocean, continent.

· Global ecosystems — biosphere as a whole.

Larger ecosystems include smaller ecosystems.

 

Fig. 3. Types of ecosystems

 

 

Environment is a wider concept. The environment consists of biocenosis, biotope and also physical, chemical, biological, anthropogenic factors (forces) effecting a living organism (Fig. 4).

 

Fig. 4. Structure of the environment

 

Ecological Factors

· аbiotic(factors of lifeless nature)

· biotic (mutual relations of alive organisms, trophic chains, etc.)

· anthropogenic (connected with a human activity)

At effect on a living organism the ecological factors depending on their intensity can be:

· irritantscausing adaptive reactions;

· signalstestifying to the change of other factors of the environment;

· modifierscausing morphological changes;

· terminatorsstopping or suppressing the vital activity of organism.

 

The rule of limiting ecological factors. The more the value of a separate ecological factor keeps away from the zone of optimum for the given kind, the more it suppresses the vital activity and is called limiting.

 

Ecological niche is a set of ecological factors providing the normal vital activity of the given kind of organisms.

 

Ecosystem is a set of in common living species of living organisms and conditions of their existence.

 

Biogeocenosisis a set of homogeneous ecological factors and species of living organisms in a certain territory; it consists of 2 parts:

· ecotope — a set of аbiotic factors,

· biocenosis — a complex of living organisms.

The basic parameters of ecosystem are:

· Qualitative — a species variety of ecosystem, amount of species of living organisms

· Quantitative — a number of species of a separate kind.

Every ecosystem is in a condition of mobile-stable balance — homeostasis. A gradual change of parameters of ecosystem under the influence of any factors is a succession of ecosystem.