Any ecosystem is characterized by inconstancy and variability. Nature periodically changes, taking a new form and forming high-quality 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.
What is biogeocenosis
If you take any piece of land on which life is present at least in some form, you can find many types of organisms that are interconnected by the cycle of energy and substances. Such biotopes, i.e., land areas, are called biogeocenoses. This is one of the types of ecosystems, for which all the signs of the latter are characteristic:
1. Integrity.
2. Self-regulation.
3. Self-reproduction.
To determine what causes the change of biogeocenoses, 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, Fabric, topical bonds are formed, which are the basis of the cycle of organic and inorganic substances.
Food chains are the main way to transfer energy between organisms. They are pasture and detrital, highly branched and weakly branched, with a large number of links and with a small number of links. All this together gives biogeocenosis the ability to self-regulation and self-reproduction.
The cycle of substances in biogeocenosis
What are the reasons for the change of biogeocenoses? First of all, this is the cycle of substances. Mineral and organic substances are an important component of every ecosystem. For example, plants secrete oxygen, which is needed for animal respiration. In turn, animals emit carbon dioxide into the atmosphere, which plants need for photosynthesis. This simplest example shows how closely related organisms are.
The reasons for the change in biogeocenoses are often the disappearance of one of the links in the food chain. The organic matter cycle takes place in the community according to the following scheme: producers synthesize organic matter, consumers consume it, and reducers convert organic residues of consumers into material for a new synthesis of proteins, fats and carbohydrates.
Accordingly, herbivores and predators are distinguished among consumers. If the number of predators increases sharply, then herbivores disappear from the ecosystem. If they were the only food source, predators could also die of hunger. If the number of herbivores predominates, then their feed reserves are likely to run out. These examples show what causes the change of biogeocenoses: the absence of one of the links of 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.
Changes in biogeocenoses. The main reasons for the change
An ecosystem is a dynamic natural structure in which its own “laws and rules” of development are supported. If we consider it over a long period of time, we can note the difference in the ratio of organic and inorganic substances, as well as detect the constant replacement of some organisms by others. What are the main reasons for the change of biogeocenoses?
1. Normal natural processes within the community (succession).
2. Anthropogenic factors: deforestation, drainage of swamps, in a larger sense - pollution of the atmosphere and water bodies.
3. The impact of any climatic anomalies: land, severe frosts, snowstorms and storms (catastrophic factors).
In today's realities, the influence of the anthropogenic factor on ecosystems and nature as a whole has increased dramatically. Now only in remote corners can one observe the natural change of one biotope to another.
What are the reasons for the stability and change of biogeocenoses?
The stability of an ecosystem is determined by several factors that depend on the level of its organization, territory, and the number of different types of organisms. Here are the main criteria by which to judge the stability of biogeocenosis:
1. The degree of closure of the cycle of substances.
For the ecosystem to survive longer, all substances must be included in the general circulation cycle. If organics and inorganics are washed out in any way, are not in demand in a population of animals or plants of a given 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, then as a result the constant composition of the community is maintained.
On this basis, in general, it is possible to determine what causes the change of biogeocenoses.
2. Type of internal circulation 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 last group includes such territories that are located in the lowlands and receive only the moisture that accumulates there after rainfall.
3. The metabolic rate
Another important characteristic of ecosystem sustainability, which depends on the rate of decomposition and synthesis of organic substances. The higher this indicator, the longer the biogeocenosis can last.
Catastrophic ecosystem changes
Regardless of what causes the change of biogeocenoses, climatic changes and anomalies can be detrimental to any of them. Examples are forests, floods, lightnings, and strong winds that have been burned due to drought, which destroy trees and can uproot them.
Stages of development of biogeocenoses
Succession is a natural change from one biogeocenosis to another. Any ecosystem is able to undergo changes in its composition and development. Natural competition between species of organisms leads to a restructuring of the entire ecosystem, resulting in changes in biogeocenoses. 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 the 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 easiest to explain based on the plant composition of biogeocenosis. Flora has the greatest impact on the further formation of the biotope and fauna, which explains the classification of developmental stages.
The first stage is a shallow grass cover, the height of which may not exceed half a meter. These are ordinary meadows, the flora of which consists mainly of various perennial and annual grasses, flowers, horsetails and ferns.
The second stage is characterized by the appearance of shrubs in the biogeocenosis. The fauna is also undergoing changes, which is reflected in interspecific relationships.
The third stage is the development of broad-leaved forest, which can last a long period of time. New species of trees, animals and microorganisms appear. In a biogeocenosis with rapid development of flora, a tiered formation is formed: a forest litter appears, animals develop new territories and habitats.
The fourth stage is called menopause, or menopause. It represents coniferous forests, which gradually replace deciduous forests by darkening the lower tiers. As a result, light-loving plants such as birch, oak, ash cannot grow to normal sizes. The fourth stage is the final in the development of biogeocenosis, because here the least energy loss, closer and more developed connections between organisms are observed.
Primary succession
All of the above steps are a natural process called succession. Any ecosystem seeks to go through all 4 stages of development, from herbs to climacteric coniferous forest. However, succession is also of two types: primary and secondary.
Primary succession is characteristic of those territories on which initially there were no signs of life. It can be rocks, frozen lava, vacant lots. Sooner or later, any of these places is populated by microorganisms, then the seeds of undemanding plants get there, insects appear.
Secondary succession
If you look again, what causes the change of biogeocenoses, 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 land, plant seeds remain, insect larvae, worms survive underground. What can we say about bacteria and protists that can survive any climatic anomaly. All this is the foundation for secondary succession - the process of restoring biogeocenosis at the site of the disappeared old.
Conclusion
Any biotic and abiotic factors can affect the development of the ecosystem. These are normal processes that take place in nature, so it is very difficult to influence them. The exception is, perhaps, human intervention in the environment, but in most cases this leads to negative consequences. Here are the main reasons for the change of biogeocenoses.