Trophic chains and trophic levels. Trophic levels

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Resistant biogeochemical cycles of the substance and energy in the biosphere of our planet are formed due to biological diversity Conducted by the organisms of the set of substances and allocated in the natural medium of products of vital activity. The base of the biological cycle of substances is trophic levelswhich are represented by specific types of living organisms divided by three main groups: producers, consvers and relegates. The trophic level is the population of organisms performing the same trophic functions in the ecosystem and having a different species composition (from Greek. Trophe - "Power").

First trophic level - the level of primary products - Form autotrophic. These are organisms that synthesize organic matter (carbohydrates, fats, proteins, nucleic acids) from not organic compoundsUsing the energy of the sun. Primary products are biomass of vegetable fabrics. Primary producers - plants, photoauthotrophic bacteria and chemosynthetic bacteria (chemotrophs). Chemotrofa - microorganisms synthesizing the organic matter due to the energy of ammonia oxidation, hydrogen sulfide and other substances in water and soil.

The second trophic level is represented consiefs (heterotrophs):

1) first order - phytophages - use as a plant as food;

2) second order - feed animal food.

On the third trophic level - roducenie. These are organisms decomposing to minerals, carbon dioxide and water waste and dead organisms. Consiefs also participate in mineralization organic substances.

All organisms are used in food biomass of previous trophic levels, losing energy with loss of breathing, body heating, on various forms Activities for excretion.

Between the species of different trophic levels, there are a relationship forming a system of trophic chains (power circuits). The use of resources on each trophic level depends on the species diversity of the ecosystem.

The species diversity can decrease in pollution zones, causing simplifying the trophic structure.

Today, violations of the structure of biocenoses are recorded due to pollution of the surrounding natural environment. Toxcans are transmitted by supply chains and contribute to the death of animals, birds, hydrobionts, and also accumulate in food productsconsumed by man.

Trophic chain

The main feature of the ecosystem is the presence of food networks and chains in them.

Definition 1.

The trophic (food) chain is a number of organisms of a certain, which reflects the movement of organic substances in the ecosystem and the biochemical energy in it obtained by the nutrition of organisms.

Next, consider the resulting terms: consversions, reederunts and producers. Products are organisms that produce organic compounds from inorganic substances. In the ecosystem producers are autotrophic organisms that convert external energy into biochemical energy by photosynthesis located in an organic compound.

Example 1.

Example of producers - plants (for ground ecosystems). Example of producers for aquatic ecosystems - Phytoplankton - small algae.

Consumes are organisms that eat organic matter that produce producers during their activities. Allocate consvers of various order (1st and 2nd).

• Consiefs of the 1st order - organisms eating plants (for example, goat, hare).
• Consons of the 2nd order - organisms that build their proteins from animals and plant proteins (second-order consversions are also called predators).

Recurates - organisms (mainly mushrooms, bacteria, etc.), which turn organic residues in inorganic compounds.

Trophic (Food) Levels

In each ecosystem, a certain number of trophic links or levels can be noted. The very first level is depicted by producers, and the second and the following levels are represented by consultations. The last level is mainly formed by mushrooms and microorganisms that feed on a dead organic compound (Rindunts).

Their main function in the ecosystem is to decompose organic compounds to the initial mineral elements. The interrelated range of trophic levels is a trophic chain or power circuit.

It should be noted that the supply chain is not complete all the time. First, maybe the lack of producers (plants). The data of the power chain is characteristic of communities that are generated on the basis of the decay of plant or animal residues, for example, accumulating in the forests on the soil (forest litter).

Secondly, in the supply chains may be absent (or in a very small amount) heterotrophs (animals). For example, in the forests, dying plants or their parts (branches, leaves, etc.), i.e. Products are immediately included in the links of the renders.

In the natural community, some organisms that get food from vegetation through equal number Stages include one trophic level. It is right to note that this trophic classification distributes in groups not species themselves, but types of their livelihoods; The population of this species will occupy one and more trophic levels, it depends on which energy sources it uses.

The relative role of the food circuits in the ecosystem is determined by the value of the energy flow coming into one or another chain, and the effectiveness of its use of trophic levels. So, if in plankton communities, the main role in the transfer of energy (and, consequently, in the release of mineral compounds) belongs to consultations of the pasture chain, then in terrestrial ecosystems - Detritret. In particular, in the forests

Each organism should receive energy for life. For example, plants consume the energy of the Sun, animals feed on plants, and some animals feed on other animals.

Food (trophic) chain is a sequence of who eats whom in the biological community () to produce nutrients and energy supporting vital activity.

AutoTrophy (producers)

Avtotropy. - Living organisms that produce their food, that is, their own organic compounds, from simple molecules, such as carbon dioxide. There are two main types of autotrophic:

• PhotoAvtotrofa (photosynthetic organisms) such as plants, process the energy of sunlight to obtain organic compounds - Sakharov - from carbon dioxide in the process . Other examples of photoautotrophs are algae and cyanobacteria.

• Hemoautotrophs get organic substances thanks chemical reactionsin which inorganic compounds (hydrogen, hydrogen sulfide, ammonia, etc.) are involved. This process is called chemosynthesis.

Avtotrophs are the basis of each ecosystem on the planet. They constitute most of the food chains and networks, and the energy obtained in the process of photosynthesis or chemosynthesis maintains all other organisms of environmental systems. When it comes to their role in the food chains, the autotrophic can be called producers or manufacturers.

Heterotrophs (consversions)

Heterotrophs.Also known as consumers cannot use solar or chemical energy to produce their own carbon dioxide food. Instead, heterotrophs get energy, consuming other organisms or their by-products. People, animals, mushrooms and many bacteria - heterotrophs. Their role in food chains is the consumption of other living organisms. There are many types of heterotrophs with different environmental roles: from insects and plants to predators and mushrooms.

Destructors (relegates)

Another group of consumers should be mentioned, although it does not always appear in the schemes of food chains. This group consists of reinstituents, organisms that process dead organic matter and waste, turning them into inorganic compounds.

Roduznuts are sometimes considered a separate trophic level. As a group, they feed on extreme organisms entering various trophic levels. (For example, they are able to recycle the decaying vegetable substance, the body of the proteins under all predators or the remains of the deceased eagle.) In a certain sense, the trophic level of the relevant is parallel to the standard hierarchy of primary, secondary and tertiary consumers. Mushrooms and bacteria are key ministers in many ecosystems.

Recurates, as part of the food chain, play an important role in maintaining a healthy ecosystem, because thanks to them, in the soil are returned nutrients and moisture, which are further used by producers.

Food levels (trophic) chain

Scheme of food levels (trophic) chain

The food chain is a linear sequence of organisms that transmit nutrients and energy from producers and to higher predators.

The trophic level of the body is the position he occupies in the food chain.

First trophic level

Food chain begins with autotrophic organism or producer, producing its own food from the primary source of energy, as a rule, solar or energy of hydrothermal sources of mid-ocean ridges. For example, photosynthetic plants, chemosyntheses and.

Second trophic level

Then follow the organisms that feed on autotrophs. These organisms are called purbitating animals or primary consumersand consume green plants. Examples include insects, hares, sheep, caterpillars and even cows.

Third trophic level

The next link in the food chain is animals that eat herbivores - they are called secondary consumers or carnivorous (predatory) animals (for example, a snake that is powered by hares or rodents).

Fourth trophic level

In turn, these animals eat larger predators - tertiary consumers (For example, Owl eats snakes).

Fifth trophic level

Tertiary consumers eating quaternary consumers (for example, hawk eating owls).

Each nutritional chain ends with a higher predator or superhireman - animals without natural enemies (for example, a crocodile, a polar bear, shark, etc.). They are "owners" of their ecosystems.

When any body dies, it will eventually eat childhood (such as hyenas, vultures, worms, crabs, etc.), and the rest is decomposed with the help of renders (mainly bacteria and fungi), and energy exchange continues.

The arrows in the food chain show the stream of energy, from the sun or hydrothermal sources to higher predators. As energy flows from the body into the body, it is lost on each chain link. The combination of many food chains is called food Network.

The position of some organisms in the food chain may vary, since their diet is different. For example, when the bear eats berries, he acts as a herbivorous animal. When he eats a rodent feeding with plants, it becomes a primary predator. When the Bear eats salmon, he acts as a superhireman (this is due to the fact that salmon is a primary predator, because it feeds on a herring, and it eats zooplankton, which feeds on phytoplankton, producing its own energy thanks sunlight). Think about how the place of people in the food chain is changing, even often for one meal.

Types of food chains

In nature, as a rule, two types of food chains are distinguished: pasture and dedicated.

Pasture food chain

Pasture Food Chain Scheme

This type of food chain begins with live green plants intended for the nutritional animals that feed predators. Ecosystems with such a type of chain directly depend on solar energy.

Thus, the pasteure type of the food chain depends on the authotrophic seizure of energy and move it along the links of the chain. Most ecosystems in nature follow this type of food chain.

Examples of a pasture food chain:

• Grass → Grasshopper → Bird → Hawk;
• Plants → Hare → Lisa → Lion.

Detritritis food chain

Detritretic Food Chain Scheme

This type of food chain begins with a decompanying organic material - Detritis - which is used by Dtritanophagi. Then, child predators feed. Thus, similar food chains are less dependent on straight solar energy than pasture. The main thing for them is the influx of organic substances produced in another system.

For example, this type of food chain is found in a decomposing litter.

Energy in the food chain

Energy is transferred between the trophic levels, when one organism is powered by others and receives nutrients from it. However, this energy movement is ineffective, and this inefficiency limits the length of food chains.

When energy enters the trophic level, part of it is preserved as biomass, as part of the body of organisms. This energy is available for the next trophic level. As a rule, only about 10% of energy, which is stored in the form of biomass on one trophic level, is maintained in the form of biomass at the next level.

This principle of partial energy transfer limits the length of food chains, which, as a rule, have 3-6 levels.

At each level, the energy is lost in the form of heat, as well as in the form of waste and outstanding matter that are used by the relegates.

Why so much energy comes out of the food network between one trophic level and others? Here are some of the main reasons for inefficient energy transfer:

• At each trophic level, a significant part of the energy is dissipated in the form of heat, since the organisms perform cellular respiration and move in everyday life.
• Some organic molecules that feed organisms can not digest and extend in the form of feces.
• Not all individual organisms in the trophic level will be eaten by organisms from the following level. Instead, they die without being eaten.
• Cal and unselected dead organisms become food for the reasons, which are metabolized and transformed into their energy.

So, none of the energies actually disappears - all this ultimately leads to heat release.

The value of the food chain

1. Studies of the food chain help to understand the fodder relations and interaction between organisms in any ecosystem.

2. Thanks to them, it is possible to estimate the mechanism of energy flow and circulation of substances in the ecosystem, as well as to understand the movement of toxic substances in the ecosystem.

3. Studying the food chain allows you to understand the problems of bios.

In any food chain, energy is lost every time one organism is consumed to others. In this regard, there must be much more plants than herpodium animals. Avtotrophov exists more than heterotrophs, and therefore most of them are roasting than predators. Although there is an acute competition between animals, they are all interconnected. When one species dies, it can affect many other species and have unpredictable consequences.

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The energy of the sun plays a huge role in the reproduction of life. The amount of this energy is very large (approximately 55 kcal per 1 cm 2 per year). From this number of producers - green plants - as a result of photosynthesis, not more than 1-2% of energy, and the desert and ocean - hundredths of the percentage are fixed.

The number of links in the food chain may be different, but usually there are 3-4 (less often 5). The fact is that there is so little energy to the ultimate link of the food chain that it is not enough in the event of an increase in the number of organisms.

Fig. 1. Food chains in ground ecosystem

The combination of organisms combined with one type of nutrition and occupying a certain position in the food chain, is called Trophic level. To one trophic level belongs to organisms that receive their energy from the Sun through the same number of steps.

The simplest food chain (or supply chain) can consist of phytoplankton, then larger herbal plankton crustaceans (zooplankton) come, and the chain of whales (or small predators) is ends, which are filtered by these crustaceans from water.

Nature is complex. All its elements, alive and inanimate, is one whole, complex adapted to each other, interacting and interrelated phenomena and creatures. This is the links of one chain. And if you remove from the total chain at least one such link, the results may be unexpected.

Especially negatively rupture of power circuits can affect the forests - whether forest biocenoses of a moderate zone or distinguished by a rich specious diversity of biocenoses tropical forest. Many types of trees, shrubs or herbaceous plants use the services of a particular pollinator - bees, wasps, butterflies or hummingbirds, dwelling within the range of this plant species. As soon as the last blooming tree Or a herbaceous plant, the pollinator will have to leave this habitat. As a result, phytophages feeding on these plants or fruits (herbivores) will die. Without writing, predators will be left without writing, and then the changes consistently touches the rest of the food chain units. As a result, they will affect both a person, as he has its own definite place in the food chain.

Food chains can be divided into two main types: pasture and detractive. Food value, which begin with carotrophic photosynthesising organisms, are called pasture, or Chains of remedy. On the top of the pasture chain there are green plants. In the second level of the pasture chain, phytophages are usually located, i.e. Pets feed on plants. An example of a pasture food chain can serve as a relationship between organisms on the floodplain meadow. This chain begins with a meadow flower plant. The next link is a butterfly that feeds the nectar of the flower. Then there is a dweller wet habitats - a frog. Her patronizing coloring allows her to restore the victim, but does not save from another predator - ordinary horns. Heron, catching the horns, closes the food chain on the floodplain meadow.

If the food chain begins with dead remnants of plants, corpses and excrement of animals - Derita, it is called Detritret, or Chain decomposition. The term "child" means the decay product. It is borrowed from geology, where Destrite is called destruction products mountain breeds. In ecology, child is the organic substance involved in the decomposition process. Such chains are characteristic of the bottom of the bottom of the deep lakes, the oceans, where many organisms are powered by the settlement of the Detritis, formed by the exposed organisms of the upper lighted layers of the reservoir.

In forest biocenoses, the detritus chain begins with the decomposition of the dead organic matter with animal-saprophages. The most active participation in the decomposition of the organics here is the soil invertebrate animals (arthropods, worms) and microorganisms. Large saprophages are present - insects that prepare a substrate for organisms carrying out mineralization processes (for bacteria and mushrooms).

In contrast to the pasture chain, the size of the organisms during the movement along the Detrain chain do not increase, but, on the contrary, decrease. So, at the second level there may be insects-gravers. But the most typical representatives of the Detriton Chain are mushrooms and microorganisms that feed on the dead substance and trust the decomposition process of bioorgians to the state of the simplest mineral and organic substances, which are then consumed in dissolved form by the roots of green plants on the top of the pasture chain, thereby the new circle of the substance movement.

In some ecosystems, pasture, in others - detritus chains are dominated. For example, the forest is considered an ecosystem with a predominance of dedicated chains. In the ecosystem of the roting stump, the pasteure chain is generally absent. At the same time, for example, in the sea surface ecosystems, almost all producers represented by phytoplankton are consumed by animals, and their corpses are lowered to the bottom, i.e. The abandoned ecosystem is leaving. In such ecosystems, pasture food chains are dominated, or the remedy chain.

General ruleconcerning any the food chain, Person: At every trophic community level most of Energy absorbed from food is spent on maintaining vital activity, dissipates and no longer can be used by other organisms. Thus, the consumed food at each trophic level is not completely assimilated. Significant part of it is spent on metabolism. When switching to each subsequent food chain link, the total amount suitable for the use of energy transmitted to the next, higher trophic level decreases.