What is an ecosystem and what is its role? This is one of the components of ecology.
The term, which is an abbreviation for "ecological system", means a system of connections of all both living and nonliving organisms in the sphere of their habitat.
What is an ecosystem
This term was introduced by the ecologist A. Tensley back in 1935. It was this ecologist who united all the components of nature, both living and non-living origin, the properties of which are in the interchange of energy in the concept of an ecosystem.
Within the ecosystem, a full cycle occurs from the origin of an organic species to its decomposition into inorganic substances.
Ecosystem types
By type, ecosystems are divided into several types, namely:
- Microecosystem -it is a closed miniature ecosystem that needs only one solar energy. Such a system means lake reservoirs, puddles, an aquarium, the trunk of a fallen tree with all the organisms living on it, etc.
- Mesoecosystem -a medium-sized system with a wider range of living organisms. These are rivers, meadows, lakes, forests, etc.
- Macroecosystemrepresents a large ecological system such as continents, oceans, biome, etc.
- Megaecosystemcombines all existing ecosystems into one whole, that is, it is a global biosphere.
Types of ecosystems
To classify ecological systems, scientists have divided them by location for the reasons that each differs in biological, bioenergetic and climatic characteristics.
Natural or natural ecosystem
It has a sign of spontaneity, as it arises due to natural elements.
It is a solid part of the ecosystem - deserts, mountains, equatorial forest, coniferous forest, mixed forest, and terrestrial water resources.
Anthropogenic or artificial ecosystem
This is everything that is created by man, namely: gardens, fields, reserves, planted forests, artificial reservoirs, even aquariums and greenhouses.
The differences between artificial and natural ecosystems are:
- one species is more concentrated than others (example: a field in which cereals are grown; animal farms);
- small variety of species;
- short food chains;
- open circulation of substances;
- impossibility of existence without human intervention.
Socio-natural ecosystem
It is a system formed due to human interaction with nature, and not due to certain human activities.
To satisfy his needs, a person carries out activities that are interconnected with the world around him, and in the course of this activity, natural ecosystems begin to adjust and are already transformed into socio-natural ecosystems.
Autotrophic ecological systems
They independently provide themselves with energy and are divided into subspecies: photoautotrophic and chemoautotrophic. The former acquire energy from the sun through photoautotrophs, while the latter acquire chemical energy through chemoautotrophs.
For example, agricultural land belongs to photoautotrophic ecosystems, as a person participates using energy-producing substances in soil cultivation. The formation of chemoautotrophic ecosystems occurs in groundwater.
Heterotrophic ecosystem
Depends on the use of chemical energy. This energy is obtained from organic substances, or from energy devices that are created by man.
The formation of a heterotrophic system naturally occurs at the bottom of the ocean depths, where the formation occurs due to the absence of the light of the sun.
Ecosystem structure and factors
All living organisms, everything that interacts with the physicochemical inanimate environment is a natural ecological unit, that is, an ecological system.
The ecosystem has the ability to maintain stability for some time due to abiotic and biotic components.
Spatial structure biocenosis is part of the ecosystem, namely all terrestrial life with their underground part, including animal world.
Species structure implies a set of relationships, as well as the ratio of the number of species. And different communities that belong to ecological systems consist of species diversity. For example, in the steppe, there can be a large number of different plants.
Ecological structure Is the ratio of different groups of organisms that characterize different types of biocenoses, which determine the ecological factor of the community. At the same time, the ecological structure has a strict pattern due to certain landscape and climatic conditions.
Trophic structure is a type of ecosystem. Hit process organic matter producers move from one trophic level to the next, this transition is called the food chain, the scheme of which forms the trophic chain.
Border factorarises in an ecosystem due to the role of diverse conditions in different species. The complexity of the species composition depends on different habitats. This is the only way to form and interact species with a wide variety of fauna and flora. Communities with maximum respect for the ecological requirements of the species.
Conclusion
It follows from this that everything that is around us is an integral ecosystem, which consists of its varieties. At the same time, ecological systems that are contrary to natural principles are not sustainable.
The main conclusion from the considered material is quite clear: systems that contradict natural principles and laws are unstable, thereby upsetting the balance of the ecosystem. This instability is due to the global intervention of mankind in the natural environment.
General properties of systems... The central concept in ecology - the ecosystem reflects the fundamental concept of this science that nature functions as a holistic system, regardless of what kind of environment we are talking about: freshwater, marine or terrestrial. The general theory of complex systems, which includes the study of the integral properties of ecosystems, began with the works of the biologist Ludwig von Bertalanffy in the late 40s of the XX century. A systematic approach to solving environmental problems is becoming more and more practical.
A system is understood as the ordering of interacting and interdependent components that form a single whole.
The whole is a certain unity of elements that has its own structure. The concept of "structure" reflects the arrangement of elements and the nature of their interaction.
The systems have the following specific properties:
Insulation;
Integration;
Integrity;
Stability;
Equilibrium;
Control;
Stability (homeostasis);
Emergence.
Emergence (from the English. emergence - appearance) is a universal characteristic of systems, including ecosystems, which consists in the fact that the properties of the system as a whole are not a simple sum of the properties of its constituent parts or elements. As the components are combined into larger functional units, the latter acquire new properties that were absent at the previous level (component level). Such qualitatively new, emergent, properties of the system level of an organization cannot be predicted from the properties of the components that make up this level or unit.
The emergent properties of systems arise as a result of the interaction of components, and not as a result of a change in their nature. Given the emergent properties, to study the whole, it is not necessary to know all its components, which is very important for ecology, since many ecosystems include thousands of components-populations, which are not possible to thoroughly study. Therefore, in the first place in terms of importance are the integral properties of integral complex ecological systems: total biomass, production and destruction of individual trophic levels, without knowing the patterns, changes in which cannot describe the behavior of the entire system in time and predict its future.
The stability of self-regulating systems determines their ability to return to their original state after a slight deviation. In this case, the principle applies Le Chatelier - Braun: under external influence, which brings the system out of a stable equilibrium state, the equilibrium shifts in the direction in which the effect of external influence is weakened.
The existence of systems is unthinkable without directand reverse connections. Direct connection is called such a connection in which one element (A) acts on another (B) without a response. If there is a response, then they talk about feedback (Figure 12.1).
Figure: 12.1 Feedback mechanism
This type of connection plays an essential role in the functioning of ecosystems and determines their stability and development. Feedbacks can be positive and negative.
Positive feedback causes the strengthening of the process in one direction. For example, after deforestation, territories become swamped, sphagnum mosses (moisture accumulators) appear, and swamping intensifies. Negative feedback causes, in response to the strengthening of the action of element A, an increase in the opposite direction of the action of element B. This is the most widespread and important type of connections in natural ecosystems. They are primarily based on the sustainability and stability of ecosystems. An example of such a relationship is the relationship between predator and prey. An increase in the population of prey as a food resource creates conditions for reproduction and an increase in the population of predators. The latter, in turn, begin to destroy prey more intensively, reducing their number, and thereby worsen their own feeding conditions. In less favorable conditions, the birth rate in the predator population decreases and after a while the number of the predator population also decreases, as a result of which the pressure on the prey population decreases. This connection allows the system to remain in a state of stable dynamic equilibrium (i.e., self-regulation).
There are usually three types of systems:
1) isolated - existing within certain boundaries, through which the exchange of substances and energy does not occur (such systems are created only artificially);
2) closed - exchanging only energy with the environment;
3) open - exchanging matter and energy with the environment (these are natural ecosystems).
The most important value of the general theory of systems for ecology as a science is that it allowed the creation of a new scientific methodology - system analysis,in which natural objects are represented as systems. The latter are distinguished based on the objectives of the study. On the one hand, the system is viewed as a single whole, and on the other, as a set of elements. The tasks of system analysis are to identify:
Connections that make the system whole;
System connections with surrounding objects;
System management processes;
Probabilities of the nature of the behavior of the investigated object (forecast).
Any system has the following basic parameters:
Borders;
Properties of elements and the system as a whole;
Structure;
The nature of connections and interactions between the elements of the system, as well as between the system and its external environment.
Borders - the most complex characteristic of the system, due to its integrity and determined by the fact that internal connections and interactions are much stronger than external ones. The latter circumstance determines the stability of the system to external influences.
Element and system properties in general, they are characterized by qualitative and quantitative features, which are called indicators.
System structure is determined by the ratio in space and time of its constituent elements and their connections. The spatial aspect of the structure characterizes the order of the elements in the system, and the temporal aspect reflects the change in the states of the system in time (i.e., it shows the development of the system). The structure expresses the hierarchy (subordination of levels) and the organization of the system.
The nature of connections and interactions between the elements of the system and the system with the external environment represents various forms of material, energy and information exchange. If there are connections between the system and the external environment, the borders are open, otherwise they are closed.
Ecosystem... Living organisms and their environment (abiotic habitat) are inseparably connected with each other and are in constant interaction, forming an ecological system (ecosystem).
Ecosystem is a community of living beings and their habitat, forming a single functional whole based on causal relationships between individual ecological components.
The main properties of ecosystems are determined by their ability to carry out the circulation of substances and create biological products, that is, to synthesize organic matter. Natural ecosystems as opposed to artificial ones created by man, under stable conditions environment can exist indefinitely, as they are able to withstand external influences and maintain structural and functional constancy (homeostasis). Large ecosystems include ecosystems of lesser rank.
Depending on the size of the occupied space, ecosystems are usually divided into:
Microecosystems (a small body of water, the trunk of a fallen tree in the decay stage, an aquarium, etc.);
Mesoecosystems (forest, pond, lake, river, etc.);
Macroecosystems (oceans, continents, natural zones, etc.),
The global ecosystem (biosphere as a whole).
Large terrestrial ecosystems that are characteristic of certain geographic natural areas are called biomes (for example, taiga, steppe, desert, etc.). Each biome will include a range of smaller, interconnected ecosystems.
The ecosystem consists of two main blocks. One of them is a complex of interconnected populations of living organisms, i.e. biocenosis, and the second is a set of environmental factors, i.e. ecotope... An ecosystem is a functional unit of living nature, which includes biotic (biocenosis) and abiotic (habitat) parts of the ecosystem, interconnected by a continuous cycle (exchange) of chemicals, energy for which is supplied by the Sun (Figure 12.2).
Figure: 12.2. Energy flow and the cycle of chemicals in the ecosystem
Photosynthetic (photoautotrophs) organisms (plants, microalgae) synthesize organic matter from the mineral components of soil, water and air, using the energy of sunlight. The organic substances formed in the process of photosynthesis serve as a source of energy for plants to maintain their functions, reproduction, as well as a building material from which they form their tissues (phytomass). Heterotrophic organisms (animals, bacteria, fungi) in the process of feeding use various organic compounds created by photoautotrophs to build their bodies and as a source of energy. In the process of metabolism in heterotrophs, the release of stored chemical energy and mineralization of organic matter to carbon dioxide, water, nitrates, phosphates occur. Since the products of mineralization of organic matter are again used by autotrophs, there is a constant circulation of substances in the ecosystem.
Ecosystem structure... The structure of any system is determined by the laws in the relationship and connections of its parts. Each ecosystem necessarily contains two main blocks of elements: living organisms and factors of the inanimate environment surrounding them. The set of organisms (plants, animals, microorganisms, fungi, etc.) is called the biocenosis or biota of the ecosystem. The system of relationships between organisms, as well as between the biota and the habitat, including abiotic factors, determines the structure of the ecosystem.
As part of any ecosystem, the following main components can be distinguished:
- inorganic substances - mineral forms of carbon, nitrogen, phosphorus, water and others chemical compoundsentering the cycle;
- organic compounds - proteins, carbohydrates, fats, etc .;
- air, water and substrate environmentincluding climatic regime (temperature and other physical and chemical factors);
- producers - autotrophic organisms that create organic food from simple inorganic substances due to the energy of the Sun (photoautrophs), mainly green plants and unicellular microscopic algae in water, some groups of photosynthetic bacteria and chemoautotrophs, bacteria using the energy of redox reactions (sulfur bacteria, iron bacteria, etc. .);
- consumers - herbivorous and carnivorous heterotrophic organisms, mainly animals that eat other organisms;
- reducers (destructors) - heterotrophic organisms, mainly bacteria and fungi, and some invertebrates that decompose dead organic matter.
The first three groups of components (inorganic substances, organic substances, physicochemical factors) make up the inanimate part of the ecosystem (biotope), and the rest - the living part (biocenosis). The last three components located relative to the flow of incoming energy are ecosystem structure (fig.12.3). Producers capture solar energy and convert it into energy chemical bonds organic matter. Consumables, eating producers, use this energy for active life and building their own body. As a result, all the energy stored by the producers is used up. Reducers break down complex organic compounds to mineral components suitable for use by producers (water, carbon dioxide, etc.).
Figure: 12.3. The structure of the ecosystem, including the flow of energy (double arrow) and two cycles of substances: solid (thick arrow) and gaseous (thin arrow)
Thus, the structure of ecosystems is formed by three main groups of organisms (producers, consumers and reducers) participating in the circulation of solid and gaseous substances, transformation and use of the energy of the Sun.
One of the common features of all ecosystems, whether terrestrial, freshwater, marine or artificial ecosystems, is the interaction of autotrophic (producers) and heterotrophic (consumers and reducers) organisms, which are partially separated in space ( the spatial structure of the ecosystem).
Autotrophic processes (photosynthesis of organic matter by plants) are most active in the upper layer of the ecosystem, where sunlight is available. Heterotrophic processes (biological processes associated with the consumption of organic matter) most intensively occur in the lower tier, in soils and sediments, where organic matter accumulates.
The system of food interactions between organisms forms trophic structure(from the Greek trophe - food), which for terrestrial ecosystems can be divided into two tiers:
1) top autotrophic layer (self-feeding), or "green belt", including plants or their parts containing chlorophyll, in which the fixation of light energy, the use of simple inorganic compounds and the accumulation of complex organic compounds, and 2) lower heterotrophic layer (fed by others), or "brown belt" of soils and sediments, decaying substances, roots, etc., in which the use, transformation and decomposition of complex organic compounds predominate.
The functioning of autotrophs and heterotrophs can also be separated in time, since the use of the production of autotrophic organisms by heterotrophs can take place not immediately, but with a significant delay. For example, in a forest ecosystem, photosynthesis occurs mainly in tree crowns. Moreover, only a small part of the products of photosynthesis is immediately and directly processed by heterotrophs that feed on foliage and young wood. The bulk of the synthesized organic matter (in the form of leaves, wood and reserve nutrients in seeds, roots) eventually enters the soil, where these substances are relatively slowly used by heterotrophs. It can take many weeks, months, years or even millennia (in the case of fossil fuels) before all this accumulated organic matter is used up.
It should be borne in mind that organisms in nature live for themselves, and not in order to play any role in the ecosystem. The properties of ecosystems are formed due to the combined activities of the plants and animals included in it. Only with this in mind, we can understand its structure and functions, as well as the fact that the ecosystem reacts to changes in environmental factors as a whole.
Each ecosystem is characterized by a strictly defined species structure- the diversity of species (species richness) and the ratio of their number or biomass. The greater the variety of environmental conditions, the greater the number of species in the biocenosis. From this point of view, the richest in species diversity are, for example, the ecosystems of tropical rainforests and coral reefs. The number of species of organisms inhabiting these ecosystems is in the thousands. And in ecosystems of deserts there are only a few dozen species.
Species diversity also depends on the age of ecosystems. In young developing ecosystems, which have arisen, for example, on a lifeless substrate of sand dunes, mountain dumps, and fires, the number of species is extremely small, but as ecosystems develop, the species richness increases.
Of the total number of species living in an ecosystem, usually only a few dominate, that is, they have a large biomass, abundance, productivity or other indicators of significance for the ecosystem. Most of the species in the ecosystem are characterized by relatively low indicators of significance.
Not all species influence their biotic environment in the same way. there is species-edificators, which in the process of their vital activity form the environment for the community as a whole and without them the existence of most other species in the ecosystem is impossible. For example, a spruce in a spruce forest is an edificator species, since it creates a kind of microclimate, an acidic reaction of the soil and specific conditions for the development of other plant and animal species adapted to exist in these conditions. When a spruce forest changes (for example, after a fire or a felling) with a birch forest, the ecotope in this area changes significantly, which determines the change in the entire biological community of the ecosystem.
Ecosystem names are formed based on the most important parameters that determine the characteristic conditions of the habitat. So, for terrestrial ecosystems, the names include the names of edificator species or dominant plant species (spruce-bilberry, cereal-forb steppe ecosystems, etc.).
Functioning of ecosystems. Ecosystems are open systems, that is, those that receive energy and matter from the outside and give them to the external environment, therefore, an important component ecosystems - external environment (input environment and output environment). Living organisms that are part of ecosystems, in order to exist, must constantly replenish and expend energy. Unlike substances that are continuously circulating through different components of the ecosystem, energy can be used only once, that is, energy passes through the ecosystem in the form of a linear flow.
The functional diagram of the ecosystem reflects the interaction of three main components, namely: community, energy flow and circulation of substances. The energy flow is directed only in one direction. Part of the incoming solar energy is converted by the biological community and moves to a qualitatively higher level, transforming into organic matter. But most of the energy degrades: after passing through the system, it comes out in the form of low-quality thermal energy called heat sink. Energy can be stored in an ecosystem, then released or exported again, but it cannot be reused. Unlike energy, nutrients and water can be reused.
One-way flow of energy is the result of the laws of thermodynamics. The first law of thermodynamics (the law of conservation of energy) states that energy can pass from one form (sunlight) to another (potential energy of chemical bonds in organic matter), but it does not disappear and is not created anew, that is, the total amount of energy in the processes remains constant ... The second law of thermodynamics (the law of entropy) states that in any processes of energy conversion, some of it is always dissipated in the form of thermal energy inaccessible for use, therefore, the efficiency of spontaneous conversion of kinetic energy (for example, light) into potential energy (for example, into the energy of chemical bonds in organic matter) always less than 100%.
Living organisms convert energy, and every time energy is converted (for example, food is digested), some of it is lost as heat. Ultimately, all of the energy entering the biotic cycle of the ecosystem is dissipated as heat. However, living organisms that inhabit ecosystems cannot use heat energy to do work. For this purpose, they use the energy of solar radiation stored in the form of chemical energy in organic matter, created by producers in the process of photosynthesis.
Food created by the photosynthetic activity of green plants contains potential energy, which, when used by heterotrophic organisms, is converted into other forms of chemical energy.
Most of the solar energy that hits the ground is converted into heat and only a very small part of it (on average for the globe at least 1%) is converted by green plants into the potential energy of chemical bonds in organic matter.
The entire animal world of the Earth receives the necessary potential chemical energy from organic substances created by photosynthesizing plants, and most of it in the process of respiration is converted into heat, and a smaller part is converted again into chemical energy of the newly synthesized biomass. At each stage of energy transfer from one organism to another, a significant part of it is dissipated in the form of heat.
The balance of food and energy for an individual living organism can be represented as follows:
E p \u003d E d + E pr + E pv,
where E p is the energy of food consumption;
E d - breath energy;
E pr - growth energy;
E pv - energy of excretion products.
The release of energy in the form of heat in the process of life in carnivores (predators) is small, and in herbivores it is more significant. For example, caterpillars of some insects that feed on plants release up to 70% of the energy absorbed from food in the form of heat. However, with all the variety of values \u200b\u200bof energy expenditure for vital activity, the maximum expenditure on respiration is about 90% of all energy consumed in the form of food. Therefore, the transition of energy from one trophic level to another is taken on average as 10% of the energy consumed with food. This pattern is known as usually ten percent... From this rule it follows that the power supply circuit can have a limited number of levels, usually no more than 4-5 levels, passing through which, almost all the energy is dissipated.
Food chains. Within the ecosystem, organic matter created by autotrophic organisms serves as food (a source of energy and matter) for heterotrophs. Typical example: an animal eats a plant. This animal, in turn, can be eaten by another animal, and in this way energy can be transferred through a number of organisms - each subsequent one feeds on the previous one, supplying it with raw materials and energy. This sequence of organisms is called the food chain, and each of its links is trophic level... The first trophic level is occupied by autotrophs (primary producers). Organisms of the second trophic level are called primary consumers, the third - secondary consumers, etc.
The main property of the food chain is the implementation of the biological cycle of substances and the release of energy stored in organic matter.
Representatives of different trophic levels are interconnected in food chains by processes of one-way directional transfer of biomass (in the form of food containing an energy reserve).
Food chains can be classified into two main types:
1) pasture chainsthat start with a green plant and move on to grazing animals, and then to predators;
2) detrital chainsthat start with small organisms feeding on dead organic matter and go to small and large predators.
Food chains are not isolated from each other; they are closely intertwined in the ecosystem to form food webs.
Ecological pyramids.To study the relationships between organisms in an ecosystem and to graphically represent these relationships, it is more convenient to use not schemes of food webs, but ecological pyramids, the base of which is the first trophic level (the level of producers), and the subsequent levels form the floors and the top of the pyramid. Ecological pyramids can be classified into three main types:
1) population pyramidsreflecting the number of organisms at each trophic level;
2) biomass pyramidsthat characterize the total mass of living matter at each trophic level;
3) energy pyramidsshowing the magnitude of energy flow or productivity at successive trophic levels.
To graphically represent the structure of the ecosystem in the form of a pyramid of numbers, the number of different organisms in a given territory is first counted, grouping them by trophic levels. After such calculations, it becomes obvious that the number of animals progressively decreases with the transition from the second trophic level to the next. The number of plants of the first trophic level also often exceeds the number of animals that make up the second level. Two examples of size pyramids are shown in Fig. 12.4, where the length of the rectangle is proportional to the number of organisms at each trophic level. The shapes of the pyramid numbers vary greatly for different communities, depending on the size of their constituent organisms (Fig. 12.4).
In the biomass pyramids, the total mass of organisms (biomass) of each trophic level is taken into account, i.e., the quantitative ratios of biomasses in the community are shown (Fig. 12.5). The numbers indicate the amount of biomass in grams of dry matter per 1 m 2. In this case, the size of the rectangles is proportional to the mass of living matter of the corresponding trophic level, per unit area or volume. However, the value of biomass at the trophic level does not give any idea about the rate of its formation (productivity) and consumption. For example, producers of small sizes (algae) are characterized by a high rate of growth and reproduction (an increase in the biomass of producers), balanced by their intensive consumption for food by other organisms (a decrease in the biomass of producers). Thus, although the biomass at a particular moment may be low, productivity can be high.
Of the three types ecological pyramids the energy pyramid gives the most complete picture of the functional organization of the community.
In the energy pyramid (Fig. 12.6), where the numbers indicate the amount of energy (kJ / m2 per year), the size of the rectangles is proportional to the energy equivalent, i.e. the amount of energy (per unit area or volume) that has passed through a certain trophic level for a specific period. The energy pyramid reflects the dynamics of the passage of a mass of food through the food (trophic) chain, which fundamentally distinguishes it from the pyramids of abundance and biomass reflecting the static state of the ecosystem (the number of organisms at a given moment).
Ecosystem productivity -the formation of organic matter in the form of biomass of animals, plants and microorganisms that make up the biotic part of the ecosystem, per unit of time per unit of area or volume. The ability to create organic matter ( biological productivity) is one of the most important properties of organisms, their populations and ecosystems in general.
Due to the energy of light during photosynthesis, the main, or primary, products of the ecosystem are created. Primary productivity is the rate at which solar energy is absorbed by producers (plants) during photosynthesis, accumulating in the form of organic matter. In other words, it is the value of the growth rate of plant biomass.
It is customary to distinguish four successive stages in the process of producing organic matter:
1) gross primary productivity - the overall rate of photosynthesis, that is, the rate of formation of the entire mass of organic matter by producers, including the amount of organic matter that was consumed by producers to maintain activity (P G);
2) net primary productivity - the rate of accumulation of organic matter in plant tissues minus the organic matter that was synthesized by plants and used to maintain their vital activity (P N);
3) net productivity of the community - the rate of accumulation of organic matter not consumed by heterotrophs (animals and bacteria) in the community for a specific period (for example, the increase in plant biomass by the end of the summer season).
4) secondary productivity - the rate of energy accumulation (in the form of biomass) at the level of consumers (animals) that do not create organic matter from inorganic ones (as in the case of photosynthesis), but only use organic matter obtained from food, part of which is spent on maintaining vital activity and the rest turning into their own tissues.
High rates of production of organic matter are found with favorable environmental factors, especially when additional energy is supplied from the outside, which reduces the organisms' own costs for maintaining vital activity. For example, in the coastal zone of the sea, additional energy can come in the form of the energy of tides, which bring particles of organic matter to sedentary organisms.
The day of visual representation of regional features of the functioning of the biosphere in Fig. 12.7 shows a model of productivity of large ecosystems of the biosphere in the form of a turbine powered by the flow of sunlight. The width of a turbine wheel for land corresponds to the percentage of land in a particular natural area, the width of the wheel for the sea is taken arbitrarily. The blades of this model turbine (plant species in a specific ecosystem) perceive sunlight during photosynthesis and provide energy for all life processes in ecosystems. At the same time, a land turbine has the largest number of blades (plant species) in the tropics, where 40 thousand plant species can produce annual biological products of 10 11 tons of organic matter. In tropical terrestrial ecosystems, on average, about 800 g / m2 carbon is re-created annually. Marine ecosystems (Figure 12.7) are most productive in the temperate boreal regions, where about 200 g of carbon per square meter is produced annually.
The value of biological productivity is decisive for most systems for classifying water bodies by the level of trophicity, i.e. nutrients for the development of biocenosis. The level of trophicity of a reservoir is determined by the content of the main photosynthetic pigment (chlorophyll), by the value of the total biomass and by the rate of production of organic matter. According to this classification, there are four types of lakes: oligotrophic, eutrophic, mesotrophic and hypertrophic (Table 12.1).
In the proposed classification system, the level of biological productivity (trophicity) of water bodies is closely related to abiotic factors (depth, color, transparency of the water body, the presence of oxygen in the bottom layers of water, water acidity (pH), concentration of biogenic elements, etc.), with geographic location reservoir and the nature of the drainage basin.
Oligotrophic water bodies(from the Greek - insignificant, poor) contain a small amount of nutrients, have high transparency, low color, great depth. Phytoplankton in them is poorly developed, since autotrophic organisms are not provided with mineral nutrition, mainly nitrogen and phosphorus. Organic matter synthesized in a reservoir ( autochthonous substance) almost completely (up to 90..95%) undergoes biochemical decomposition. As a result, the amount of organic matter in the bottom sediments is small; therefore, the oxygen content in the bottom water layers is high. Pasture trophic chains prevail in the reservoir, there are few microorganisms and destruction processes are weakly expressed. Such lakes are characterized by large sizes and great depths.
Eutrophic bodies of water (from the Greek eutrophia, good nutrition) are characterized by an increased content of biogenic elements (nitrogen and phosphorus), therefore phytoplankton is provided with mineral nutrition and the intensity of production processes is high. With an increase in the degree of eutrophication, the transparency and depth of the photosynthetic zone decrease. An excess of oxygen often occurs in the upper layers of water due to the high rate of photosynthesis, while in the bottom layers of water there is a significant deficiency of oxygen due to its use by microorganisms in the oxidation of organic matter. Detrital food chains are becoming increasingly important in the reservoir.
Mesotrophic type (from the Greek mesos - medium) - an intermediate type of water bodies between oligotrophic and eutrophic. Usually, mesotrophic water bodies arise from oligotrophic ones and turn into eutrophic ones. In many cases, this process is associated with eutrophication- an increase in the level of primary production of waters due to an increase in the concentration of nutrients, mainly nitrogen and phosphorus. The input of nutrients into water bodies increases as a result of the washing off of fertilizers from the fields, as well as the ingress of industrial and municipal wastewater into them.
Hypertrophic reservoirs (from the Greek hyper - over, over) are characterized by a very high level primary production and, as a consequence, high biomass of phytoplankton. The transparency and oxygen content in water bodies is minimal. The content of a large amount of organic matter leads to the massive development of microorganisms, which predominate in the biocenosis.
Ecosystem homeostasis.Ecosystems, like their constituent populations and organisms, are capable of self-maintenance and self-regulation. Homeostasis (from the Greek. similar, the same) - the ability of biological systems to resist changes and maintain a dynamic relative constancy of composition and properties. The instability of the habitat in ecosystems is compensated by biocenotic adaptive mechanisms.
Along with the flows of energy and the circulation of substances, the ecosystem is characterized by developed information networks, which include flows of physical and chemical signals that connect all parts of the system and control it as a whole. Therefore, it can be assumed that ecosystems have a cybernetic nature.
Homeostasis is based on the feedback principle, which can be demonstrated by the example of the dependence of population density on food resources. Feedback occurs if the “product” (the number of organisms) has a regulatory effect on the “sensor” (food). IN this example the amount of food resources determines the rate of population growth. When the population density deviates from the optimum in one direction or another, the birth rate or mortality increases, as a result of which the density is brought to the optimum. This feedback, which reduces the deviation from the norm, is called negative feedback.
In addition to feedback systems, the stability of the ecosystem is ensured by the redundancy of functional components. For example, if a community has several types of autotrophs, each of which is characterized by its own temperature optimum, then with fluctuations in ambient temperature, the rate of photosynthesis of the community as a whole will remain unchanged.
Homeostatic mechanisms operate within certain limits, beyond which already unrestricted positive feedbacks lead to the death of the system if additional tuning is impossible. As stress builds up, the system, while still being controlled, may not be able to return to its previous level.
The area of \u200b\u200baction of negative feedback can be depicted as a homeostatic plateau (Figure 12.8). It consists of steps; negative feedback acts within each step. The transition from step to step can occur as a result of a change in the "sensor". So, increase or decrease
The earth is shaped like a ball. But if this is so, then why do not the objects on it fall from its surface? Quite the opposite happens. A stone thrown upward comes back, snowflakes and raindrops fall down, dishes overturned from the table fly down. It is all the fault of the earth's gravity, which attracts all material bodies to the earth's surface.
It turns out that forces of attraction arise between all bodies, including cosmic ones. If we follow the logic, then the smaller body, which, for example, is the same Moon, must necessarily fall to the Earth. A similar version can be put forward about our solar system. In theory, all the planets included in it should have long ago fallen into the Sun. However, this does not happen. A completely logical question arises, why?
Firstly, all the planets of the solar system keep close to the sun, thanks to its enormous gravitational force, and do not fall on it just because they are in constant motion, which occurs in an elliptical orbit. The same can be said about the Moon, which also moves around the Earth, and therefore does not fall on it. If there were no forces of gravity, then there would be no solar system. The Earth would roam freely in space, remaining deserted and lifeless.
Its satellite, the Moon, would have suffered a similar fate. It would not be circling the Earth in an elliptical orbit, but would have chosen an independent route for itself long ago. But, having got into the zone of action of the earth's gravity, it is forced to change the rectilinear trajectory of movement to an elliptical one. If it were not for the constant movement of the moon, it would have fallen to Earth long ago. It turns out that as long as the planets move around the Sun, they cannot fall on it. And all because two forces constantly act on them, the force of gravity and the force of inertia of motion. As a result, all planets do not move in a straight line, but in an elliptical orbit.
In fact, the existing order in the Universe is preserved only thanks to the law universal gravitation, which was discovered by Isaac Newton. All space objects, including artificial earth satellites launched by man, are subject to him. The same ebb and flow that we are witnessing is also due to the action of the mutual gravitational forces of the Moon, Earth and the Sun. In this case, the actions of the moon are more pronounced, since it is much closer to the Earth than the sun.
And yet, why does the Earth not fall on the Sun, because its mass, in comparison with the celestial body, is hundreds of thousands of times less, and logically, it should instantly stick to it? This would certainly happen, but only if our planet stopped. But since it moves around the Sun at a speed of 30 kilometers per second, this does not happen. She also cannot fly away from him, due to the enormous forces of solar attraction. As a result, straight motion The earth gradually bends and becomes elliptical. Other planets of the solar system move similarly.
So high speeds the rotation of the planets, scientists associated with the formation of the solar system. In their opinion, it arose from a rapidly rotating cosmic cloud, which underwent gravitational compression to the center, from which, subsequently, the Sun arose. The cloud itself had both angular and translational velocities. After shrinking, their value increased, and then was transferred to the formed planets. Not only the planets of the solar system move progressively, but also it itself, moreover, at a speed of 20 km / h. The trajectory of this movement is directed towards the constellation "Hercules".
What caused the rotation and translational motion of the dust cloud itself?
Scientists agree that this is how the entire galaxy behaves. In this case, all objects located closer to its center rotate at a higher speed, and those that are further away - at a lower speed. The resulting difference in forces rotates the Galaxy, which is the reason for the complex motion of the gas complexes included in it. In addition, the trajectory of their movement is influenced by galactic magnetic fields, explosions of stars and stellar wind.
Why won't the moon be attracted to the sun, because its gravity is 2 times greater ??? and got the best answer
Answer from Uncle Fedor [guru]
Something in general is complete nonsense at the expense of "double strength" ...
The moon is attracted to the sun. And the Earth is also attracted to the Sun. Thanks to this attraction, the Earth and the Moon move in an orbit around the Sun, rather than flying away in a straight line.
Answer from Nikolay Gorelov[guru]
Before answering this question, you must admit it is nonsense.
Answer from Vladimir Medvedev[newbie]
The question comes from the fact that there are two given - the Earth and the Sun, and the Moon must choose between them what to be attracted to.
If the attraction is more to the Earth - to revolve around the Earth, if more to the Sun - to revolve around the Sun - or even fall on it.
The implicit assumption here is that the Earth and the Sun themselves are fixed at some points in space, since they are considered as two different bases, to one of which the Moon must belong. At least the influence of the Earth and the Sun on each other is not considered.
But in fact, this influence is. And as the Sun attracts the Moon, it also strongly, and even more strongly, it attracts the Earth.
Accordingly, they are attracted in tandem and "fall" on the Sun. But the rotation of the Earth-Moon system around the Sun allows balancing the centrifugal force and the gravitational force of the Sun.
Answer from Anatoly Nizgodinsky[guru]
It is necessary to consider not the Moon separately, but the Earth-Moon pair! And at the same time, do not forget that they ROTATE around the sun !!!
Answer from Konstantin Okhotnik[guru]
Yes, one should not look at the answers, but read a scientific book, at least a school textbook.
Don't worry, the Moon is attracted by both the Sun and the Earth! And it falls both on the Earth and on the Sun, only it cannot get there.
And why does the Sun act on the Moon with a vengeance?
Answer from Evgeny Yurtaev[expert]
then why don't leaves or dust swirl around us? logically, we are more and have iron inside and dust should be our companion 😀
Answer from Vlada Shatrova[active]
The earth is closer to the moon and the attraction is greater, while the sun is farther and the force of attraction decreases. So it turns out that the Moon "hangs" between the Sun and the Earth.
Answer from White rabbit[guru]
Uncle Fyodor has the correct answer.
ALL bodies in a gravitational field move in the same way, including the Moon and the Earth, if we consider the Earth-Moon system, then you can temporarily forget about the Sun
This is a consequence of the fact that there is actually no FORCE of attraction (not twice as much, but in general NO
Answer from Danilochkin fedor[guru]
The earth won't let go. Do not forget about the mutual attraction of the earth and the moon.
Answer from 3 answers[guru]
Hello! Here is a selection of topics with answers to your question: Why the Moon is not attracted to the Sun, because its gravity is 2 times greater ???