Biological production (efficiency) of ecosystem

The gain of a biomass in the ecosystem, created for a time unit, is called biological production (efficiency). There are primary and secondary productions of community.

Primary production is a biomass created by producers for a time unit. It is divided into total and pure productions. Total primary production (the general assimilation) is the general biomass created by plants during photosynthesis. Its part is discharged for maintenance of ability to live of plants (expenses for breath (40-70 %). The remained part makes up pure primary production (pure assimilation) which in the further is used by consumers and reducers, or it is collected in the ecosystem.

Secondary production is a biomass created by consumers for a time unit. It is various for each following trophic level.

The weight of organisms of the certain group (producers, consumers, reducers) or communities as a whole is called a biomass. Tropical rain woods posses the highest biomass and efficiency, and the lowest is desert and tundra (tab. 8).

If velocity of the plants growth (formation of the primary production) in the ecosystem is above rates of its processing by consumers and reducers it results in increase of producer biomass. If recycling of products decomposition in chain of decomposition is insufficient an accumulation of dead organic substance proceeds. It results in peatining bogs, in formation of a powerful wood laying, etc. In stable ecosystems the biomass remains constant as practically all production is spent in the food chains.

8. Сукцессии

Translational changes are changes in biocenosis, finally, resulting in change of this community by another. Succession is a consecutive change of biocenosis (ecosystem), expressed in change of specific structure and structure of community. Successions are desertification of steppes, overgrown of lakes and formation of bogs, etc.

Depending on the reasons caused change of biocenosis, сукцессии are divided into natural and anthropogenous, autogenious and allogenious.

Сукцессия of Siberian darkneedle forests (fir-cedar taiga) after devastating forest fire

Numbers in rectangular are vibrations in duration of passage of сукцессии phases (in brackets term their termination is specified). The biomass and biological efficiency are shown in unspecified scale. (Curves reflect the qualitative and quantitative parties of the process.) (Rejmers, 1990.)

Natural succession occurs under action of the natural reasons which have been not connected with activity of man. Anthropogenous succession is caused by activity of the person.

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