Variant – 17

1. Pedosphere (a soil cover) as a part of biosphere

The pedosphere (from Greek πέδον pedon "soil" or "earth" and σφαίρα sfaíra "sphere") is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The sum total of all the organisms, soils, water and air is termed as the "pedosphere". The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere (air in and above the soil), biosphere (living organisms), lithosphere (unconsolidated regolith and consolidated bedrock) and the hydrosphere (water in, on and below the soil). The pedosphere is the foundation of life on this planet. There is a realization that the pedosphere needs to be distinctly recognized as a dynamic interface of all terrestrial ecosystems and be integrated into the Earth System Science knowledge base. Also, the pedosphere needs to be studied, valued, enhanced and treated in a sustainable and an ethical manner.

The pedosphere acts as the mediator of chemical and biogeochemical flux into and out of these respective systems and is made up of gaseous, mineralic, fluid and biologic components. The pedosphere lies within the Critical Zone, a broader interface that includes vegetation, pedosphere, groundwater aquifer systems, regolith and finally ends at some depth in the bedrock where the biosphere and hydrosphere cease to make significant changes to the chemistry at depth. As part of the larger global system, any particular environment in which soil forms is influenced solely by its geographic position on the globe as climatic, geologic, biologic and anthropogenic changes occur with changes inlongitude and latitude.

2. The structural organization of ecosystem

The structure of ecosystem

From the point of view of trophic structure ecosystem is divided into two circles – autotrophic and heterotrophic (Odum, 1986).

1. The top autotrophic circle, or «a green belt» is a circle of plants or their parts containing a chlorophyll where fixing of light energy, use of simple inorganic compounds and accumulation of complex organic compounds prevail.

2) The bottom heterotrophic circle, or «a brown belt» is a circle of soil and the precipitation, decompositing substances, roots and etc. in which use, transformation and decomposition of complex compounds prevail.

From the biological point of view in structure of ecosystem there are following components (Odum, 1986):

1) inorganic substances;

2) organic compounds;

3) air, water and substrate medium;

4) producers;

5) macroconsumers;

6) microconsumers.

1. Producers are the autotrophic organisms, which are capable to produce organic substances from inorganic, using photosynthesis or chemosynthesis (plants and autotrophic bacteria).

2. Consumers (macroconsumers) are the heterotrophic organisms consuming organic substance of producers or others consumers (animals, heterotrophic plants, some microorganisms). There are consumers of the first order and the second order.

3. Reducers (microconsumers, destructors) are the heterotrophic organisms, eating fossils and decomposing them to mineral substances (saprotrophic bacteria and mushrooms).

As a rule, in any ecosystem it is possible to note three functional groups of organisms: producers, consumers and reducers. In ecosystems formed only by microorganisms, consumers are absent. Each group consists of set of the populations occupying ecosystem.

In ecosystem, food and power bonds proceed in a line: producers->consumers-> reducers.

3. Classification of community.

Classification of community. Community is differed in sizes and a degree of «genetic independence», duration of existence, a way of breeding of species, etc.

Depending on sizes of occupied community of territory and communication degree between species there are elementary (local), ecological and geographical communities. The elementary (local) community is an elementary grouping of the species, described practically full panmixia. Ecological community is a totality of spatially adjacent elementary communities. A geographical community is a totality of groups of spatially adjacent ecological communities.

According to ability to self-reproduction and independent evolution there are permanent (constants) and (time) communities. Permanent (constants) communities are ones which are rather steadily in space and in time and which are capable to unlimitedly long self-reproduction, are elementary units of evolution. Time communities are ones which are unstable in space and in time and unable to long self-reproduction. Eventually or they will be transformed in permanent, or they will disappear.

Depending on breeding, communities are divided into panmictic, clonal and clonal-panmictic. Panmictic communities consist of the species, breeding by sexual way for which cross impregnation is characteristic. Clonal communities consist of species for which only sexual breeding is characteristic. Clonal-panmictic communities are formed by species with alternation sexual and sexual breeding.

communities, being group associations, possess a number of specific properties which are not inherent in each separate individual: number, density, birth rate, death rate, growth rate, etc. In addition to this, community has certain organization: sexual, age, genetic, spatially and other structures.