For any ecosystem, inconstancy andvariability. Nature periodically changes, taking a new form and forming qualitative bonds between living organisms. Biogeocenosis is an example of a typical ecosystem, which is characterized by a large number of connections between animals, plants and microorganisms.
If you take any piece of land on which, althoughin some form there is life, you can find many kinds of organisms, interconnected through a cycle of energy and substances. Such biotopes, i.e. land areas, are called biogeocenoses. This is one of the types of ecosystem, which is characterized by all the signs of the latter:
To determine what causes a shiftbiogeocenosis, it is necessary to understand the integrity and complexity of the organization of this natural system. Its components are animals, plants, fungi, bacteria and other microorganisms. Between them tropical, trophic, factory, topical connections are formed, which are the basis of the cycle of organic and inorganic substances.
Food Chains are the main way to transferenergy between organisms. They are pasture and detritnye, strongly branched and weakly ligated, with a large number of links and a small number of links. All this together gives the biogeocoenosis an ability to self-regulation and self-reproduction.
What are the reasons for changing biogeocenosis? First of all, this is a cycle of substances. Mineral and organic substances are an important component of each ecosystem. For example, plants produce oxygen, which is necessary for breathing animals. In turn, animals release into the atmosphere carbon dioxide, which is necessary for plants for the process of photosynthesis. This simplest example shows how closely the organisms are related to each other.
The reasons for biogeocenosis change often lie inthe disappearance of one of the links in the supply chain. The cycle of organic matter takes place in the community according to the following scheme: producers synthesize the organics, consumes consumes it, and the decomposers translate the organic remains of the consumers into the material for a new synthesis of proteins, fats and carbohydrates.
Accordingly, among the consumers are allocatedherbivores and predators. If the number of predators sharply increases, the herbivorous animals disappear from the ecosystem. If they were the only source of food, predators can also die of hunger. If the number of herbivores prevails, then the stocks of their food end rather. These examples show what causes a change in biogeocenosis: the absence of one of the links in any cycle can lead to further self-destruction of the ecosystem. Therefore, for its preservation, such concepts as interchangeability and diversity of species of organisms are important.
Ecosystem is a dynamic naturalstructure in which its own "laws and rules" of development are maintained. If we consider it for a long period of time, we can note the difference in the ratio of organic and inorganic substances, and also to detect a constant replacement of some organisms by others. What are the main reasons for changing biogeocenosis?
1. Normal natural processes within the community (succession).
2. Anthropogenic factors: deforestation, draining of marshes, in a larger scale - pollution of the atmosphere and reservoirs.
3. The impact of any climate anomalies: dry land, severe frost, storms and storm (catastrophic factors).
In today's realities, the impact of the anthropogenic factor on ecosystems and nature as a whole has increased dramatically. Now only in remote corners can one observe a natural change of one biotope to another.
The sustainability of the ecosystem is determined by severalfactors that depend on the level of its organization, territory, the number of different types of organisms. Here are the main criteria by which one can judge the stability of biogeocenosis:
1. Degree of closedness of the cycle of substances.
For the ecosystem to last longer, all substancesmust be inscribed in the general exchange cycle. If organic and inorganic substances are washed away in some way, is not in demand in the population of animals or plants of this environment, then a gradual outflow of substances from the ecosystem occurs. Conversely, if all food chains have several links, and for each organic or inorganic substance there is a consumer, the result is a constant composition of the community.
On this basis, in general, it is possible to determine what causes cause a change in biogeocenosis.
2. Type of internal cycle of substances.
Here ecosystems are divided into three groups: independent, dependent and subordinate. Independent biogeocenoses are located near water sources, which makes it possible to obtain moisture without any difficulties. Dependent ecosystems are located in places where the flow of water is difficult and occurs at certain intervals (for example, biocenoses of rocks or deserts). The latter group includes such territories, which are located in the lowlands and receive only the moisture that accumulates there after precipitation.
3. The rate of metabolism
Another important characteristic of the stability of the ecosystem, which depends on the rate of decomposition and the synthesis of organic substances. The higher this indicator, the longer the biogeocoenosis can survive.
Regardless of what causes a shiftbiogeocoenoses, climatic changes and anomalies can be disastrous for any of them. Examples are scorched forests due to drought, floods, lightning and strong wind that destroy trees and can tear them up with a root.
Succession is a natural change of onebiogeocenosis to others. Any ecosystem can undergo changes in its composition and development. Natural competition between species of organisms leads to a restructuring of the entire ecosystem, which results in a change in ecosystems. The reasons for the change in this case are the appearance of new plants and animals that are more adapted to the area. An example is a deciduous forest, which consists of maple, pine, birch and other trees. After a long period of time, these plants are replaced by conifers.
The stages of succession are most easily explained by relying onon the vegetative composition of the biogeocoenosis. Flora has the greatest influence on the further formation of the biotope and fauna, which explains the classification of the stages of development.
The first stage is a shallow herbaceouscover, the height of which may not exceed half a meter. These are ordinary meadows, the flora of which consists mainly of different perennial and annual grasses, flowers, horsetails and ferns.
The second stage is characterized by the appearance of shrubs in the biogeocoenosis. Fauna also undergoes changes, which is reflected in interspecific relationships.
The third stage is the development of broadleafa forest that can last a long time. New species of trees, animals and microorganisms appear. In the biogeocenosis with rapid development of the flora, longitude is formed: a litter of forest appears, animals develop new territories and habitats.
The fourth stage is called the climax, orclimax. It is a coniferous forest, which gradually replaces the deciduous forest by darkening the lower tiers. As a result, light-loving plants such as birch, oak, ash can not grow to normal size. The fourth stage is final in the development of the biogeocenosis, since the lowest energy losses, the closer and more developed links between organisms are observed here.
All of the above steps arenatural natural process, which is called succession. Any ecosystem tends to go through all 4 stages of development, ranging from grasses and ending with the climax coniferous forest. However, succession is also of two kinds: primary and secondary.
Primary succession is characteristic of thoseterritories on which there were initially no signs of life. It can be rocks, frozen lava, wasteland. Any of these places is sooner or later populated by microorganisms, then seeds of non-forcing plants get there, insects appear.
If you look again, what causes causechange of biogeocoenosis, anthropogenic and climatic factors are often in the first lines of the list. Most often they lead to the destruction of the ecosystem. However, even on the scorched devastated earth there are plant seeds, under the ground larvae of insects, worms survive. What can we say about bacteria and protists that can survive any climatic anomaly. All this is the foundation for a secondary succession - the process of restoration of biogeocenosis in place of the disappeared old.
Any biotic and abiotic factors canaffect the development of the ecosystem. These are normal processes that take place in nature, so it is very difficult to influence them. An exception is, perhaps, human interference in the environment, but in most cases this leads to negative consequences. Here are the main reasons for the change in biogeocoenosis.