The first trophic level in an ecosystem. Food chains and trophic levels
TROPHIC LEVEL
TROPHIC LEVEL is a set of organisms occupying a certain position in the overall food chain. The distance of organisms from producers is the same. They are characterized by a certain form of organization and utilization of energy. Organisms of different trophic chains that receive food through an equal number of links in the trophic chain are at the same trophic level. At each trophic level, the food consumed is not completely assimilated, since a significant part of it is lost and spent on exchange. Therefore, the production of organisms at each subsequent trophic level is always less (on average 10 times) than the previous one. The relationship between different trophic levels can be graphically depicted as an ecological pyramid. see also Environmental efficiency.
Ecological encyclopedic dictionary. - Chisinau: Main editorial office of the Moldavian Soviet Encyclopedia. I.I. Dedu. 1989.
TROPHIC LEVEL is a set of organisms united by a type of nutrition. Autotrophic organisms (mainly green plants) occupy the first trophic level (producers), followed by heterotrophs: at the second level, herbivores (consumers of the 1st order); predators feeding on herbivorous animals - in the third (consumers of the 2nd order); secondary predators - on the fourth (consumers of the 3rd order). Saprotrophic organisms (decomposers) can occupy all levels, starting from the second. Organisms of different trophic chains that receive food through an equal number of links are located on the same T.u. The ratio of different T.u. can be graphically depicted as an ecological pyramid.
Ecological dictionary, 2001
Trophic level
a collection of organisms united by a type of nutrition. Autotrophic organisms (mainly green plants) occupy the first trophic level (producers), followed by heterotrophs: at the second level, herbivores (consumers of the 1st order); predators feeding on herbivorous animals - in the third (consumers of the 2nd order); secondary predators - on the fourth (consumers of the 3rd order). Saprotrophic organisms (decomposers) can occupy all levels, starting from the second. Organisms of different trophic chains that receive food through an equal number of links are located on the same T.u. The ratio of different T.u. can be graphically depicted as an ecological pyramid.
EdwART. Dictionary of environmental terms and definitions, 2010
See what "TROPHIC LEVEL" is in other dictionaries:
A set of organisms united by a type of nutrition. The idea of T. u. allows us to understand the dynamics of energy flow and the trophic factors that determine it. structure. Autotrophic organisms (primarily green plants) occupy the first T. (producers),… … Biological encyclopedic dictionary
trophic level- 1. The level at which energy in the form of food is transferred from one organism to another as part of a food chain. 2. The level of distribution of nutrients in the reservoir, especially in relation to the content of nitrates and phosphates in the water... Dictionary of Geography
TROPHIC LEVEL, the position that an organism occupies in the FOOD CHAIN. Usually determined by the boundaries within which food is provided. The first trophic link is PRIMARY PRODUCERS green plants that use photosynthesis for... ... Scientific and technical encyclopedic dictionary
trophic level- A set of organisms of one ecosystem, united by a type of nutrition. Topics of biotechnology EN trophic level... Technical Translator's Guide
trophic level- 3.23 trophic level: An element of the functional classification of organisms within a community, which is based on the food products used.
Every organism must receive energy to live. For example, plants consume energy from the sun, animals eat plants, and some animals eat other animals.
A food (trophic) chain is the sequence of who eats whom in a biological community () to obtain nutrients and energy that support life.
Autotrophs (producers)
Autotrophs- living organisms that make their own food, that is, their own organic compounds, from simple molecules such as carbon dioxide. There are two main types of autotrophs:
- Photoautotrophs (photosynthetic organisms) such as plants process energy from sunlight to produce organic compounds - sugars - from carbon dioxide in the process. Other examples of photoautotrophs are algae and cyanobacteria.
- Chemoautotrophs obtain organic substances due to chemical reactions that involve inorganic compounds (hydrogen, hydrogen sulfide, ammonia, etc.). This process is called chemosynthesis.
Autotrophs are the basis of every ecosystem on the planet. They make up the majority of food chains and webs, and the energy obtained through photosynthesis or chemosynthesis supports all other organisms in ecological systems. When it comes to their role in food chains, autotrophs can be called producers or producers.
Heterotrophs (consumers)
Heterotrophs, also known as consumers, cannot use solar or chemical energy to produce their own food from carbon dioxide. Instead, heterotrophs obtain energy by consuming other organisms or their byproducts. People, animals, fungi and many bacteria are heterotrophs. Their role in food chains is to consume other living organisms. There are many species of heterotrophs with different ecological roles, from insects and plants to predators and fungi.
Destructors (reducers)
Another consumer group should be mentioned, although it does not always appear in food chain diagrams. This group consists of decomposers, organisms that process dead organic matter and waste, turning them into inorganic compounds.
Decomposers are sometimes considered a separate trophic level. As a group, they feed on dead organisms coming from various trophic levels. (For example, they are able to process decaying plant matter, the body of a squirrel malnourished by predators, or the remains of a deceased eagle.) In a sense, the trophic level of decomposers runs parallel to the standard hierarchy of primary, secondary, and tertiary consumers. Fungi and bacteria are key decomposers in many ecosystems.
Decomposers, as part of the food chain, play an important role in maintaining a healthy ecosystem because they return nutrients and moisture to the soil, which are then used by producers.
Levels of the food (trophic) chain
Diagram of the levels of the food (trophic) chain
A food chain is a linear sequence of organisms that transfer nutrients and energy from producers to top predators.
The trophic level of an organism is the position it occupies in the food chain.
First trophic level
The food chain starts with autotrophic organism or producer, producing its own food from a primary energy source, usually solar or energy from hydrothermal vents at mid-ocean ridges. For example, photosynthetic plants, chemosynthetic plants, etc.
Second trophic level
Next come the organisms that feed on autotrophs. These organisms are called herbivores or primary consumers and consume green plants. Examples include insects, hares, sheep, caterpillars and even cows.
Third trophic level
The next link in the food chain are animals that eat herbivores - they are called secondary consumers or carnivorous (predatory) animals(for example, a snake that feeds on hares or rodents).
Fourth trophic level
In turn, these animals are eaten by larger predators - tertiary consumers(for example, an owl eats snakes).
Fifth trophic level
Tertiary consumers are eaten quaternary consumers(for example, a hawk eats owls).
Every food chain ends with an apex predator or superpredator - an animal with no natural enemies (eg crocodile, polar bear, shark, etc.). They are the "masters" of their ecosystems.
When any organism dies, it is eventually eaten by detritivores (such as hyenas, vultures, worms, crabs, etc.) and the rest is decomposed by decomposers (mainly bacteria and fungi), and energy exchange continues.
Arrows in a food chain show the flow of energy, from the sun or hydrothermal vents to top predators. As energy flows from body to body, it is lost at each link in the chain. The collection of many food chains is called food web.
The position of some organisms in the food chain may vary because their diet is different. For example, when a bear eats berries, it acts as a herbivore. When it eats a plant-eating rodent, it becomes a primary predator. When a bear eats salmon, it acts as a superpredator (this is due to the fact that salmon is the primary predator because it feeds on herring, which eats zooplankton, which feeds on phytoplankton, which generate their own energy from sunlight). Think about how people's place in the food chain changes, even often within a single meal.
Types of food chains
In nature, as a rule, there are two types of food chains: pasture and detritus.
Grassland food chain
Grassland food chain diagram
This type of food chain begins with living green plants to feed the herbivores on which carnivores feed. Ecosystems with this type of circuit are directly dependent on solar energy.
Thus, the grazing type of food chain depends on the autotrophic capture of energy and its movement along the links of the chain. Most ecosystems in nature follow this type of food chain.
Examples of grazing food chains:
- Grass → Grasshopper → Bird → Hawk;
- Plants → Hare → Fox → Lion.
Detrital food chain
Detrital food chain diagram
This type of food chain begins with decaying organic material - detritus - which is consumed by detritivores. Then, predators feed on detritivores. Thus, such food chains are less dependent on direct solar energy than grazing ones. 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 decomposing litter.
Energy in the food chain
Energy is transferred between trophic levels when one organism feeds on and receives nutrients from another. However, this movement of energy is inefficient, and this inefficiency limits the length of food chains.
When energy enters a trophic level, some of it is stored as biomass, as part of the body of organisms. This energy is available for the next trophic level. Typically, only about 10% of the energy that is stored as biomass at one trophic level is stored as biomass at the next level.
This principle of partial energy transfer limits the length of food chains, which typically have 3-6 levels.
At each level, energy is lost in the form of heat, as well as in the form of waste and dead matter that decomposers use.
Why does so much energy leave the food web between one trophic level and the next? Here are some of the main reasons for inefficient energy transfer:
- At each trophic level, a significant portion of energy is dissipated as heat as organisms perform cellular respiration and move around in daily life.
- Some organic molecules that organisms feed on cannot be digested and are excreted as feces.
- Not all individual organisms in a trophic level will be eaten by organisms from the next level. Instead, they die without being eaten.
- Feces and uneaten dead organisms become food for decomposers, who metabolize them and convert them into their energy.
So, none of the energy actually disappears - it all ends up producing heat.
Food chain meaning
1. Food chain studies help understand feeding relationships and interactions between organisms in any ecosystem.
2. Thanks to them, it is possible to evaluate the mechanism of energy flow and the circulation of substances in the ecosystem, as well as understand the movement of toxic substances in the ecosystem.
3. Studying the food chain provides insight into biomagnification issues.
In any food chain, energy is lost every time one organism is consumed by another. Due to this, there should be many more plants than herbivores. There are more autotrophs than heterotrophs, and therefore most of them are herbivores rather than carnivores. Although there is intense competition between animals, they are all interconnected. When one species goes extinct, it can affect many other species and have unpredictable consequences.
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DIFFERENCE OF LIFE FORMS AND BIOGENIC CYCLE
The sustainable existence of life is possible only with the diversity and quality of its forms, the specificity of exchange, which is ensured by the consistent use of metabolic products released into the environment, forming the biogenic cycle.
In its simplest form, such a complementary set of qualities of life forms is represented by: producers, consumers, decomposers, joint activity, which is ensured by the extraction of substances from the external environment, their transformation at various levels of trophic chains and the mineralization of organic substances to components available for the next inclusion in the cycle.
Producers- these are living organisms that are capable of synthesizing organic matter from inorganic components using external energy sources. According to the nature of the energy source for the synthesis of organic substances, all producers are divided into photoautotrophs And chemoautotrophs.
Consumers - living beings that are not capable of building their body on the basis of the use of inorganic substances that require the supply of organic substances from the outside, as part of food. Organisms that consume organic substances along the flow of substances in the cycle occupy the level of consumers obligately associated with autotrophic organisms (consumers of the 1st order) or with other heterotraphs on which they feed (consumers of the 2nd order).
| SUN | ||||
| 1ST ORDER CONSUMERS | ||||
| PRODUCERS | CONSUMERS OF ORDER | |||
| REDUCENTS | ||||
| MINERALS |
Simplified diagram of the transfer of matter and energy in the process of biogenic cycle (Nikonorov et al.)
The importance of consumers in the cycle of substances:
1. In the process of metabolism, heterotrophs decompose organic substances obtained in food. The transformation of substances primarily reduced by autotrophs in the organisms of consumers leads to an increase in the diversity of living matter, and this is a necessary condition for the stability of any ecosystem (Eshbin’s principle of external and internal disturbance).
2. Animals that make up the bulk of consumer organisms are mobile and capable of active movement in space. By doing this, they contribute to the migration of living matter and its dispersion on the surface of the planet, which stimulates the spatial distribution of life and serves as a kind of guarantee mechanism in the event of the destruction of life in one place.
3. The important role of consumers, especially animals, as regulators of the intensity of the flow of matter and energy.
Decomposers - organisms decompose substances, partial mineralization of organic matter occurs in all animals, so during the process of respiration CO2 is released, H2O, mineral salts, and ammonia are excreted.
True decomposers, completing the cycle of destruction of organic substances, can only be considered those organisms that release into the external environment only inorganic substances that are ready to be involved in a new cycle. The decomposers category includes many types of bacteria and fungi. By the nature of their metabolism, these are reducing organisms (N denitrifying bacteria, reducing nitrogen to an elemental state).
TROPHIC LEVELS AND THEIR CHARACTERISTICS
All organisms performing trophic functions in an ecosystem constitute trophic levels:
1. Trophic level form autotrophic organisms. They create the level of primary production and are the primary producers. It is they who utilize the external energy of the sun, create a mass of organic matter (biomass), and are the basis for the existence of life in general and biocenosis in particular.
Living organisms are born, grow, develop, and during these processes their biomass changes. Biomass is expressed in units of energy or mass, not unit area (N: J/m, or t/m). In communities, the main share of biomass comes from plants (primary production - autotrophs).
The amount of production created by autotrophs is called primary products, in this case the total amount of biomass is called gross output, and the increase in biomass is clean products.
Part of the energy goes to maintaining the life and respiration of the plants themselves - this amounts to 40-70% of the gross production. The difference between gross production and respiration is net production.
Clean products - this is the rate of increase in biomass available for consumption by heterotrophs.
The rate of formation of primary production is called biological productivity of the ecosystem. It is expressed in units of energy or matter per area per day.
Animals, fungi, and bacteria obtain energy by feeding on plants (autotrophs) or other organisms that also feed on plants and are heterotrophs by the nature of their nutrition. They are classified as secondary producers.
The amount of biomass created by secondary producers is called secondary products. This group is united to the second trophic level, which is represented by consumers. They are called heterotrophic transformers.
Consumers secrete various bioactive substances that stimulate or inhibit other organisms. There are several levels in this group:
n Consumers of the 1st order
n Consumers of the second order
n and others.
The third group of organisms forms a functioning biocenosis in the ecosystem - decomposers.
The following groups of consumers of dead organisms are distinguished:
1. Necrophages(groups of animals);
2. Coprophagous(excrement);
3. Saprophages(dead plant debris);
4. Detritivores(consumers of dilapidated organic substances).
In general terms, decomposers can be divided into phytophages, zoophages, and mixophages (mixed). The contribution of each group to the functioning of the ecosystem is unequal.
N: for the complete cycle of matter in a reservoir, the species composition of producers and decomposers is not of great importance, but for commercial organisms it is decisive.
Organisms of different groups react differently to anthropogenic influences.
TYPES OF RELATIONSHIP
The following types of relationships between populations are distinguished:
n neutralism in which the association of two populations does not affect either of them;
n mutual competitive suppression, in which both populations actively suppress each other;
n competition for resources in which each population adversely affects others when competing for food resources in conditions of their scarcity;
n amensalism, in which one population suppresses another, but does not itself experience negative influence;
n predation- one population adversely affects another as a result of direct attack, but nevertheless depends on the other;
n commensalism- one population benefits from the unification, for the other this unification is indifferent;
n proto-cooperation - both populations take advantage of the union, but their connection is not obligate (not obligatory);
n mutualism - the connection of populations is favorable for the growth and survival of both.
Yu. Odum emphasizes 2 important principles:
1. In the course of evolution and development of ecosystems, there is a tendency to reduce the role of negative interactions at the expense of positive ones that increase the survival of interacting species.
Within the framework of the biosphere as an integrity, this does not happen, since dangers and overcoming them contribute to evolution.
In nature there is nothing harmful to the species, since what is harmful to the individual and population is beneficial to the species from evolution. The concept of evolution well explains evolution in the “predator-prey” system - the constant improvement of both components of the ecosystem.
The condition for reducing the negative impact is the stability of the ecosystem and the fact that its spatial structure provides the possibility of mutual adaptation of populations. Negative and positive relationships between populations in an ecosystem that reach a stable state eventually cancel each other out.
Energy is transferred from organism to organism, creating a food or trophic (Greek trophe-food) chain from autotrophs, producers (creators) to heterotrophs, consumers (eaters) and so on 4-6 times from one trophic level to another.
The trophic level is the location of each link in the food chain. The first trophic level is producers, all the rest are consumers. The second trophic level is herbivorous consumers; the third - carnivorous consumers feeding on herbivorous forms; the fourth is consumers who consume other carnivores, etc. Consequently, consumers can be divided into levels: consumers of the first, second, third, etc. orders of magnitude.
Only consumers specializing in a certain type of food are clearly divided into levels. However, there are species that feed on meat and plant foods (humans, bears, etc.), which can be included in food chains at any level.
The food absorbed by the consumer is not completely absorbed - from 12 to 20% in some herbivores, up to 75% or more in carnivores. Energy costs are associated primarily with maintaining metabolic processes, breathing costs, estimated by the total amount of CO 2 released by the body. A significantly smaller part goes to the formation of tissues and a certain supply of nutrients, i.e. for growth. The rest of the food is excreted as excrement. In addition, a significant part of the energy is dissipated in the form of heat during chemical reactions in the body and especially during active muscular work. Ultimately, all the Energy used for metabolism is converted into heat and dissipated in the environment.
Thus, most of the energy is lost during the transition from one trophic level to another, higher one. The loss is approximately 90%. No more than 10% of the energy from the previous level is transferred to each next level. So, if the calorie content of the producer is 1000 J, then when it enters the body of the phytophage, 100 J remain, in the body of the predator there are already 10 J, and if this predator is eaten by another, then only 1 J will remain for its share, i.e. 0.1% of the calorie content of plant foods.
However, such a strict picture of the transfer of energy from level to level is not entirely realistic, since the trophic chains of ecosystems are complexly intertwined, forming trophic networks. But the final result: dissipation and loss of energy, which must be renewed for life to exist.
We must also not forget dead organic matter, which a significant part of heterotrophs feed on. Among them there are saprophages and saprophytes (fungi), which use the energy contained in detritus. Therefore, two types of trophic chains are distinguished:
- Pasture (grazing chains)- start with producers; Such chains, when moving from one trophic level to another, are characterized by an increase in the size of individuals with a simultaneous decrease in density
TROPHIC LEVEL, a collection of organisms united by a type of nutrition. The concept of the trophic level allows us to understand the dynamics of energy flow and the trophic structure that determines it.
Autotrophic organisms (mainly green plants) occupy the first trophic level (producers), herbivores occupy the second (first-order consumers), predators that feed on herbivores occupy the third (second-order consumers), and secondary predators occupy the fourth (third-order consumers). Organisms of different trophic chains, but receiving food through an equal number of links in the trophic chain, are at the same trophic level. Thus, a cow and a weevil of the genus Siton that feed on alfalfa leaves are consumers of the first order. The actual relationships between trophic levels in a community are very complex. Populations of the same species, participating in different trophic chains, can be at different trophic levels, depending on the source of energy used. At each trophic level, the food consumed is not completely assimilated, since a significant part of it is spent on metabolism. Therefore, the production of organisms of each subsequent trophic level is always less than the production of the previous trophic level, on average 10 times. The relative amount of energy transferred from one trophic level to another is called community ecological efficiency or food chain efficiency.
The relationship between different trophic levels (trophic structure) can be depicted graphically as ecological pyramid, the basis of which is the first level (the level of producers).
Ecological pyramid can be of three types:
1)
pyramid of numbers - reflects the number of individual organisms at each level;
2)
biomass pyramid - total dry weight, energy content, or other measure of the total amount of living matter;
3)
pyramid of energy - the amount of energy flow.
The base in the pyramids of numbers and biomass may be smaller than subsequent levels (depending on the ratio of the sizes of producers and consumers). The pyramid of energy always narrows upward. In terrestrial ecosystems, a decrease in the amount of available energy is usually accompanied by a decrease in biomass and the number of individuals at each trophic level.
Pyramid of numbers (1) shows that if a boy were to eat only veal for one year, then he would need 4.5 calves, and to feed the calves it is necessary to sow a 4 hectare field with alfalfa (2x10 (7) plants). In the biomass pyramid (2) the number of individuals is replaced by biomass values. In the pyramid of energy (3) solar energy taken into account Lucerne uses 0.24% solar energy. To accumulate production, calves use 8% of the energy accumulated by alfalfa throughout the year. 0.7% of the energy accumulated by calves is used for the development and growth of a child during the year. As a result, just over one millionth of the solar energy falling on a 4-hectare field is used to feed a child for one year. (according to Yu. Odum)
