Succession - a permanent change in one ecological community, the appearance of the other.It can be caused by any natural phenomenon or be under the influence of man.Ecological succession originally studied representatives of this science as geobotany.In the future, this phenomenon has been the subject of interest and other environmentalists.The pioneers who found the value of succession, steel F. Clements, VN Sukachev, SM Razumovsky.Next, we analyze the concept in more detail, we present classification.In addition, the article will be described in the course of the following examples.
Terminology
who introduced the definition?Just the term "succession" was proposed by F. Clements to determine successive time-specific biological communities.They are characterized by the formation of a number or series, so that creates the conditions for the prior development of the next.In the case where there are no factors that could trigger another succession, the series ends with a relatively stable community, which is characterized by a constant exchange.Education, described above, was determined using a special Clements term "menopause".According to the scientist, it is a sustainable community within which there are no factors that contribute to how whatever changes in its development.The duration of the existence of menopause is not important.
Classification
Succession can be ordered on different grounds.Using the classification of various features can be highlighted various types of succession.Among these signs: the rate of formation / decay, duration, reversibility, persistence, the origin, development trend (Progress or degradation), changes in the number and diversity of species.Classify succession can be for a variety of reasons.The process of grouping primarily depends on what goal scientist.At the same time, there are kinds of succession, grouped by nature occurring in this sustainable community processes.On this basis, scientists have identified two main categories: endogenous and exogenous.What is the difference?Endogenous succession - this change is due to the activities of the communities themselves.The primary reason for the process usually becomes an imbalance in the exchange.In other words, a change made by the activity of the internal factors.Exogenous succession - this change provoked by external factors.
Microbiology
the forest floor, for example, can be examined in several successional stages simultaneously.This ability is due to the change in the direction of downward motion.Besides, the phenomenon can cause changes in humidity, the contents of any specific compounds or gases and the temperature T. N. This process is accompanied with soil long enough change both plant and microbial communities.
Succession primary and secondary
What are these concepts?Let us continue.Primary succession is characterized by the fact that the flows in the desolate terrain.This may be a bare rock without vegetation, sandy area, hardened lava and the like.When the body begins to settle in these territories, their metabolism affects the environment and changes it.Then begins a more complex development.And then kind of starting to change each other.An example of the succession is the formation of the original soil, settling initially lifeless sandy area, primarily by microorganisms, plants, and then the mushrooms and animals.A special role is played here by the remains of plants and substances produced by the decomposition of organic matter.Thus, begins to form and evolve the soil under the influence of microorganisms, plants and fungi changing climate.As a result of a community of organisms expanded.This succession - a ecogenetic change.It is called so because it alters the very territory on which exists.And the appearance of the original soil in the area is known as the lifeless syngenetic change.
Humidity substrate
This rate influences the type of succession.For example, the following groups:
- Kserarhnaya on dry substrate.
- Psammokseroseriya, on the sands.
- Litokseroseriya on rocky terrain.
- Geokseroseriya, dry clay or loam.
- Mezarhnaya, if the substrate has a fairly large humidity.
- Gidrarhnaya if the substrate is extremely humid.
Primary succession take place in several stages.You can bring interesting examples of succession.For example, in the forest zone of lifeless and dry substrate is replaced first with lichens, moss and then, and then grows herbs (annuals), after they begin development of the territory perennial shrubs, trees, grass.There are other examples of succession.For example, often referred to the settlement of the territory after the lava eruptions or slope after the avalanche.
during the process of development of primary succession occurs simultaneously with the soil formation.The impact on the process has hit the outside of seeds, the withering away of fragile seedlings to extreme conditions and (a certain time) interspecific competition.Or that community develops or replaced mainly due to the difference in the nitrogen content in the soil and the degree of destruction of its mineral part.In the soil and other natural microbial communities succession - this phenomenon is usually caused by entering a certain portion of the organic compound in one way or another.Since microorganisms are adapted to fracture or different polymer complex or absorb any monomers at high concentrations or to the existence in hard conditions hunger during and fracture during use of organic structural changes observed community.
secondary succession
These processes lead to the settlement of the territory after some kinds of damage.For example, forest, partially destroyed by fire.The land on which he had previously settled, keep the soil and seeds.Community herbs have literally formed the following year.And then there are deciduous trees.Under cover of aspen and birch forests begin to grow spruce, subsequently displacing hardwoods.Restoration of conifer trees going for about 100 years.But in some parts of the forest again it subjected to cutting.Therefore, in areas such recovery does not occur.
Kontinuualizm and structuralism in the study of biological communities
Although definitions postulated Clements, applied science everywhere, there are two paradigms differ significantly from each other.We consider these in more detail.Within each of these paradigms sense definitions Clements different.What these approaches differ?The followers of the structuralist paradigm strongly support the findings of Clements and continue the development of his theory.Kontinualisty, on the contrary, do not agree with the actual existence of such phenomena as biological communities, succession, climax, postklimaks, menopause continuum.The latest paradigm of ecosystem processes are reduced to the interaction of a variety of categories with each other.These types according kontinuualizmu accidentally begin to interact with each other and with inanimate nature.How did kontinuualizm?The fact that no one author of this theory: this paradigm was born almost simultaneously in two countries, two independent scientific communities: from L. Ramenskoye in the USSR and the US Mr. Gleason.
successions role in the formation and change of the biosphere
Through succession, the study of which geobotany continues to this day, is the formation of soil, change its composition, the population of the once barren areas first microorganisms, and then the plants, fungi and animals.The study of schemes and mechanisms, which occur both primary and secondary change communities clearly shows that clearly predict which species will replace each other in a chain, you can not.However, the replacement of biological communities often occurs in such a way that increases the biological diversity in the study area.
