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- •Normalization of the harmful substances, disposal with sewage.
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- •Global Warming
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Dynamic parameters of a population: birth rate, death rate, growth rate of the population.
Dynamic parameters of community reflect the processes proceeding in the community for certain time interval. The basic parameters from them: birth rate, death rate, growth rate of the community.
Birth rate is a number of the new species who have appeared in the community for a time unit in the result of breeding.
There are the maximal and actual birth rates.
Death rate (velocity of the death rate) is a number of the species who have lost in the community for a time unit (from predators, illnesses, an old age and other reasons). Death rate is a size return to the birth rate.
There are the minimal and actual death rates.
Rate of a growth community is a change of the community number in unit of time. Rate of a growth community can be positive, zero and negative. It depends on parameters of birth rate, death rate and migration (immigrations and emigrations). The rise (profit) of number occurs in the result of the birth rate and immigration of species, and reduction (loss) of number is in the result of the death rate and emigration of species.
Symbiosis
Symbiosis (from Ancient Greek σύν "together" and βίωσις "living") is close and often long-term interaction between two or more different biological species. In 1877, Bennett used the word symbiosis (which previously had been used to depict people living together in community) to describe the mutualistic relationship in lichens. In 1879, the German mycologist Heinrich Anton de Bary defined it as "the living together of unlike organisms."
The definition of symbiosis is controversial among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any types of persistent biological interactions (i.e. mutualistic, commensalistic, or parasitic).[5]
Some symbiotic relationships are obligate, meaning that both symbionts entirely depend on each other for survival. For example, many lichens consist of fungal and photosynthetic symbionts that cannot live on their own.
Symbiotic relationships include those associations in which one organism lives on another , or where one partner lives inside the other.
Cosmopolitans, ubikvists and endemics
The community is a totality of individuals of one species capable to self-reproduction which long exists in the certain part of area rather separately from other totality of the same species. Contacts between individuals of one community more often, than between individuals of different communities. The community is structural unit of species and unit of evolution.
Area. A space on which the community or species as a whole meets during all ability to live is called an area of distribution. The area can be continuous or broken off (disjunctive), that is, if between its parts there are various barriers (water, orographical, etc.), the spaces are not populated by representatives of the given species. There are various centers of areas: the geometrical center; the center of species occurrence within the limits of an area; the center of abundance is a part of area to which the greatest quantity of individuals is concentrated.
Depending on size of area and character of distribution there are cosmopolitans, ubikvists and endemics. Cosmopolitans are species of plants and animals which representatives meet on a greater part of inhabitant areas of the Earth (for example, the room fly, grey rat). Ubikvists are species of plants and animals with wide ecological valency, they are capable to exist in various conditions of environment, have extensive areas (for example, a reed ordinary, the wolf). Endemics are species of plants and animals which have the small limited areas (often they are met on islands of an oceanic origin, in mountain areas and the isolated basin).
For animals there are trophic and reproductive areas between which there is a communication in the form of ways of flight for birds or ways of migration for some mammals and fishes.