Ecological pyramids in brief. Inverted pyramid. Ecological structure of biogeocenosis

It characterizes the total mass of living matter in dry weight at each trophic level of the ecosystem.

This pyramid may look different for different ecosystems. Biomass pyramids of terrestrial ecosystems are usually characterized by the same shape as an energy pyramid. That is, the amount of biomass at each subsequent level of such an ecosystem is usually less than at the previous level. But this rule is no longer absolute. So for ecosystems of the sea, as a rule, an inverted biomass pyramid is characteristic, the base of which is smaller than the subsequent steps. Thus, the total biomass of all consumers of phytoplankton can be significantly higher than the mass of phytoplankton itself, the total mass of large fish may be less than the mass of small fish. This situation is generally typical for ecosystems with very small producers and large consumers. The reason for this is the sharp differences in life expectancy and productivity of organisms at different levels. For example, the lifespan of phytoplankton is estimated to be several days or even hours, while large animals can accumulate mass for decades. At the same time, phytoplankton has a high productivity, but all production is consumed rather quickly, so that the root yield of phytoplankton at each moment of time turns out to be relatively small. With all this, a much greater flow of energy passes through the trophic level of producers than through the levels of consumers. The disadvantages associated with the use of population pyramids can be avoided by constructing biomass pyramids that take into account the total mass of organisms (biomass) of each trophic level. Determination of biomass involves not only counting the number, but also weighing individual individuals, so this is a more laborious process, requiring more time and special equipment. Ideally, one would have to compare the dry weight, which can either be calculated from the total weight, or directly determined after removing the water.

Thus, the rectangles in the biomass pyramids reflect the mass of organisms of each trophic level per unit area or volume. Figure 5 shows a typical biomass pyramid with a characteristic decrease in biomass at each successive trophic level.

Figure 5 Biomass pyramids

Such a pyramid characterizes well the trophic structure of the ecosystem for assessing the standing crop. When sampling - in other words, at a given point in time - the so-called growing biomass, or growing yield, is always determined. Type A is the most common. Type B refers to inverted pyramids. The numbers refer to the product expressed in grams of dry matter per 1 m3.

It is important to remember that this value does not contain any information about the rate of biomass formation (productivity) or its consumption; otherwise, errors may occur for two reasons:

1.If the rate of consumption of biomass (loss due to eating) approximately corresponds to the rate of its formation, then the growing crop does not necessarily indicate productivity, i.e. the amount of energy and substance passing from one trophic level to another over a given period of time, for example in a year. For example, on a fertile, intensively used pasture, the yield of standing grasses may be lower and productivity is higher than on a less fertile, but little used for grazing.

2. Producers of small sizes, such as algae, are characterized by a high growth and reproduction rate, balanced by their intensive consumption for food by other organisms and natural death. Thus, although the growing biomass may be low compared to large producers (for example, trees), the productivity may not be lower, since the trees accumulate biomass for a long time. In other words, phytoplankton with the same productivity as a tree will have a much lower biomass, although it could support the life of the same mass of animals. In general, populations of large and long-lived plants have a lower renewal rate than small and short-lived ones and accumulate matter and energy for a longer time. One possible consequence of this is shown in Figure 3, where an inverted biomass pyramid describes the English Channel community. Zooplankton has a greater biomass than the phytoplankton that it feeds on. This is typical for planktonic communities of lakes and seas at certain times of the year; the biomass of phytoplankton exceeds the biomass of zooplankton during the spring "bloom", but in other periods the opposite ratio is possible. Such seeming anomalies can be avoided by using energy pyramids.

Often, the study of ecological pyramids causes great difficulty for students. In fact, even the most primitive and light ecological pyramids are beginning to be studied even by preschoolers and schoolchildren in primary grades. In recent years, ecology as a science has begun to be given a large amount of attention, since this science plays a significant role in the modern world. The ecological pyramid is part of ecology as a science. In order to figure out what it is, you need to read this article.

What is an ecological pyramid?

An ecological pyramid is a graphic design that is most often depicted in the form of a triangle. Such models depict the trophic structure of the biocenosis. This means that ecological pyramids reflect the number of individuals, their biomass, or the amount of the energy that they contain. Each of them can demonstrate any one indicator. Accordingly, this means that ecological pyramids can be of several types: a pyramid that displays the number of individuals, a pyramid that reflects the amount of biomass of the individuals represented, as well as the last ecological pyramid, which clearly demonstrates the amount of energy contained in these individuals.

What are pyramids of numbers?

The pyramid of numbers (or numbers) shows the number of organisms at each trophic level. Such an ecological graphical model can be used in science, but it is extremely rare. The links in the ecological pyramid of numbers can be depicted almost indefinitely, that is, it is extremely difficult to depict the structure of the biocenosis in one pyramid. In addition, at each trophic level there are many individuals, because of which it is sometimes almost impossible to demonstrate the whole structure of the biocenosis in one, full scale.

An example of building a pyramid of numbers

In order to understand the pyramid of numbers and its construction, it is necessary to find out which individuals and what interactions between them this ecological pyramid includes. We will now consider examples in detail.

Let 1000 tons of grass become the base of the figure. For example, in 1 year, about 26 million individuals of grasshoppers or other insects will be able to feed on this grass. In this case, grasshoppers will be located above the vegetation and will already form the second trophic level. The third trophic level will be 90 thousand frogs, which will consume the insects located below it in a year. About 300 trout will be able to consume these frogs per year, respectively, they will be located at the fourth trophic level in the pyramid. An adult will be located already at the top of the ecological pyramid, he will become the fifth and final link in this chain, that is, the last trophic level. This will happen because a person will be able to eat about 300 trout in a year. In turn, a person is the highest link in, respectively, no one can already eat him. As shown in the example, missing links in the ecological pyramid of numbers are impossible.

It can have a wide variety of structures depending on the ecosystem. For example, this pyramid for terrestrial ecosystems may look almost the same as an energy pyramid. This means that the biomass pyramid will be built in such a way that the amount of biomass will decrease with each successive trophic level.

In general, biomass pyramids are studied mainly by students, because understanding them requires some knowledge in the fields of biology, ecology and zoology. This ecological pyramid is a graphical drawing that represents the relationship between percentages (that is, producers of organic substances from inorganic substances) and consumers (consumers of these organic substances).

and interest?

In order to definitely understand the principle of building a pyramid of biomass, it is necessary to figure out who the consumers and interest are.

Producers of organic substances from inorganic ones are the percents. These are plants. For example, plant leaves use carbon dioxide (an inorganic substance) and produce organic matter through photosynthesis.

Consumers are consumers of these organic substances. In the terrestrial ecosystem, they are animals and people, and in aquatic ecosystems - various marine animals and fish.

Inverted biomass pyramids

An inverted biomass pyramid has the construction of an inverted triangle, that is, its base is narrower than the top. This pyramid is called inverted or inverted. An ecological pyramid has this structure if the biomass of the percents (producers of organic substances) is less than the biomass of consumers (consumers of organic substances).

As we know, an ecological pyramid is a graphic model of a particular ecosystem. One of the important ecological models is the graphical construction of energy flow. The pyramid that reflects the speed and time of the passage of food through is called the pyramid of energies. It was formulated thanks to the famous American scientist who was an ecologist and zoologist - Raymond Lindemann. Raymond formulated a law (the rule of the ecological pyramid), which argued that during the transition from a lower trophic level to the next one, about 10% (more or less) of the energy that entered the previous level in the ecological pyramid passes through the presented food chains. And the rest of the energy, as a rule, is spent on the process of life, on the embodiment of this process. And as a result of the very process of exchange in each link, organisms lose about 90% of their energy.

The regularity of the pyramid of energies

In fact, the regularity is that much less (several times) energy passes through the upper trophic levels than through the lower ones. It is for this reason that there are much fewer large predatory animals than, for example, frogs or insects.

Consider, for example, such a predatory beast as a bear. It can be at the top, that is, at the very last trophic level, because it is difficult to find an animal that would feed on it. If there were a large number of animals that would consume bears for food, they would have already died out, because they would not be able to feed themselves, since bears are few in number. This is proved by the pyramid of energies.

The pyramid of natural equilibria

Schoolchildren begin to study it in grades 1 or 2, because it is quite easy to understand, but at the same time it is very important as a component of the science of ecology. The natural balance pyramid operates in different ecosystems, both in terrestrial nature and in underwater one. It is often used to educate schoolchildren about the importance of every creature on earth. In order to understand the pyramid of natural equilibria, it is necessary to consider examples.

Examples of building a pyramid of natural equilibria

The pyramid of natural equilibria can be clearly demonstrated by the interaction of the river and the forest. For example, a graphic drawing can show the following interaction of natural resources: a forest grew on the bank of a river, which went deep into the depths. The river was very deep, and flowers, mushrooms, and bushes grew on its banks. There were many fish in its waters. In this example, an ecological balance is observed. The river gives its moisture to the trees, while the trees create a shade, do not allow the water from the river to evaporate. Consider the opposite example of natural balance. If something happens to the forest, the trees are burned or cut down, then the river can dry up without receiving protection. This is an example of destruction

The same can happen with animals and plants. Consider owls and acorns. Acorns are the basis in the ecological pyramid of natural balance, because they do not feed on anything, but at the same time they feed on rodents. Wood mice will become the second component in the next trophic level. They feed on acorns. There will be owls at the top of the pyramid because they feed on mice. If the acorns that grow on the tree disappear, then the mice will have nothing to eat and they will most likely die. But then the owls will have no one to eat, and their entire species will perish. This is the natural balance pyramid.

Thanks to these pyramids, ecologists can monitor the state of nature and fauna and draw appropriate conclusions.

The main process that occurs in all ecosystems is the transfer and circulation of matter or energy. In this case, losses are inevitable. The magnitude of these losses from level to level is what the rules of ecological pyramids reflect.

Some academic terms

The exchange of matter and energy is a directed flow in the chain of producers - consumers. Simply put, eating some organisms by others. At the same time, a chain or sequence of organisms is built, which, like links in a chain, are linked by the relationship "food - consumer". This sequence is called the trophic or food chain. And the links in it are trophic levels. The first level of the chain is the producers (plants), because only they can form organic substances from inorganic ones. The next links are consumers (animals) of various orders. Herbivores are tier 1 consumers, and herbivore predators will be tier 2 consumers. The next link in the chain will be decomposers - organisms whose food is the remains of vital activity or the corpses of living organisms.

Graphic pyramids

British ecologist Charles Elton (1900-1991) in 1927, based on the analysis of quantitative changes in food chains, introduced the concept of ecological pyramids into biology as a graphic illustration of the relationships in the ecosystem of producers and consumers. Elton's pyramid is depicted as a triangle divided by the number of links in the chain. Or in the form of rectangles standing on top of each other.

Patterns of the pyramid

C. Elton analyzed the number of organisms in the chains and found that there are always more plants than animals. Moreover, the ratio of levels in quantitative terms is always the same - a decrease occurs at each next level, and this is an objective conclusion, which is reflected in the rules of ecological pyramids.

Elton's rule

This rule states that the number of individuals in a sequential decreases from level to level. The rules of the ecological pyramid are the quantitative ratio of products at all levels of a particular food chain. It says that the chain level indicator will be approximately 10 times less than that at the previous level.

Given a simple example, which will dot the "and". Consider the algae trophic chain - invertebrate crustaceans - herring - dolphin. A forty-kilogram dolphin needs to eat 400 kilograms of herring to survive. And in order for these 400 kilograms of fish to exist, you need about 4 tons of their food - invertebrate crustaceans. For the formation of 4 tons of crustaceans, 40 tons of algae are needed. This is what the ecological pyramid rules reflect. And only in this ratio will this ecological structure be sustainable.

Types of ecopyramids

Based on the criterion that will be taken into account when evaluating the pyramids, there are:

• Numeric.
• Biomass estimates.
• Energy expenditure.

In all cases, the ecological pyramid rule reflects a decrease in the main criterion of assessment by a factor of 10.

The number of individuals and trophic steps

The pyramid of numbers takes into account the number of organisms, which is reflected by the rule of the ecological pyramid. And the dolphin example fully fits the characteristics of this type of pyramids. But there are exceptions - a forest ecosystem with a plant chain - insects. The pyramid will become inverted (a huge number of insects feeding on the same tree). That is why the pyramid of numbers is considered not the most informative and indicative.

What is the remainder?

The biomass pyramid uses the dry (less often wet) mass of individuals of the same level as an assessment criterion. Units of measurement - gram / square meter, kilogram / hectare or gram / cubic meter. But even here there are exceptions. The rules of ecological pyramids, which reflect a decrease in the biomass of consumers in relation to the biomass of producers, are fulfilled for biocenoses, where both are large and have a long life cycle. But for aquatic systems, the pyramid may again be inverted. For example, in the seas, the biomass of zooplankton feeding on algae is sometimes 3 times the biomass of the plant plankton itself. rescues the high reproduction rate of phytoplankton.

Energy flow is the most accurate indicator

Energy pyramids show the rate of passage of food (its mass) through trophic levels. The energy pyramid law was formulated by the outstanding American ecologist Raymond Lindemann (1915-1942), after his death in 1942 he entered biology as a rule of ten percent. According to him, 10% of the energy from the previous one is transferred to each subsequent level, the remaining 90% are losses that go to support the body's vital activity (respiration, heat regulation).

The meaning of the pyramids

We have analyzed what the rules of ecological pyramids reflect. But why do we need this knowledge? The pyramids of numbers and biomass allow us to solve some practical problems, since they describe the static and steady state of the system. For example, they are used when calculating the permissible catch values ​​of fish or counting the number of animals for shooting, so as not to disturb the stability of the ecosystem and to determine the maximum size of a particular population of individuals for a given ecosystem in its entirety. And the pyramid of energies gives a clear idea of ​​the organization of functional communities, allows you to compare different ecosystems in terms of their productivity.

Now the reader will not be at a loss, having received a task like “describe what the rules of ecological pyramids” reflect, and will boldly answer that this is the loss of matter and energy in a particular trophic chain.

The ecological biomass pyramid is built in a similar way to the population pyramid. Its main meaning is to show the amount of living matter (biomass - the total mass of organisms) at each trophic level. This avoids the inconvenience inherent in the size pyramids. In this case, the size of the rectangles is proportional to the mass of living matter of the corresponding level, per unit area or volume (Fig. 7.5, a, b).

Rice. 7.5. Coral reef biocenoses biomass pyramids (a) and the English Channel (b).

The numbers represent biomass in grams of dry matter,

per 1 sq. m.

The term "biomass pyramid" arose due to the fact that in the vast majority of cases the mass of primary consumers living at the expense of producers is much greater than the mass of secondary consumers. It is customary to show the biomass of destructors separately. During sampling, the growing biomass is determined, which does not contain any information about the rate of formation or consumption of biomass.

The rate at which organic matter is created does not determine its total reserves, i.e., the total biomass of all organisms at each trophic level. Therefore, further analysis may lead to errors if the following is not taken into account:

First, when the rate of biomass consumption is equal (loss due to eating) and the rate of its formation, the standing crop does not indicate productivity, i.e., the amount of energy and matter passing from one trophic level to another, higher, for a certain period of time (for example, a year). So, on a fertile, intensively used pasture, the yield of standing grasses may be lower, and productivity is higher than on a less fertile, but little used for grazing;

Secondly, producers of small sizes, for example, algae, are characterized by a high growth and reproduction rate, balanced by their intensive consumption for food by other organisms and natural death. Therefore, their productivity can be no less than that of large producers (for example, trees), although the biomass at the root can be low. In other words, phytoplankton with the same productivity as a tree will have a much lower biomass, although it could support the life of animals of the same mass.

One of the consequences of the described are "inverted pyramids" (Fig. 7.5, b).

Zooplankton of biocenoses of lakes and seas most often has a higher biomass than its food - phytoplankton, but the rate of reproduction of green algae is so high that they restore all the biomass eaten by zooplankton during the day. Nevertheless, at certain times of the year (during spring flowering), the usual ratio of their biomasses is observed (Fig. 7.6).

Rice. 7.6. Seasonal changes in the pyramids of the biomass of a lake (for example, one of the lakes in Italy): numbers - biomass in grams of dry matter per 1 m 3

The pyramids of energies considered below are devoid of apparent anomalies.

Nature is amazing and diverse, and everything in it is interconnected and balanced. The number of individuals of any species of animals, insects, fish is constantly regulated.

It is impossible to imagine that the number of any species of individuals is constantly increasing. To prevent this from happening, there is natural selection and many other environmental factors that constantly regulate this number. All of you have probably heard such an expression as an ecological pyramid. What it is? What types of ecological pyramids are there? What rules is it based on? You will receive answers to these and other questions below.

The ecological pyramid is ... Definition

So, everyone knows that food chains exist in biology, when some animals, usually predators, feed on other animals.

The ecological pyramid is about the same system, but, in turn, is much more global. What is it like? An ecological pyramid is a kind of system that reflects in its composition the number of creatures, the mass of individuals, plus the energy inherent in them at each level. Another feature is that with an increase in each level, the indicators significantly decrease. By the way, this is precisely the reason for the ecological pyramid rule. Before talking about it, it is worth understanding what this scheme looks like.

Pyramid rule

If you represent it schematically in the figure, then it will be something similar to the pyramid of Cheops: a quadrangular pyramid with a pointed top, where the smallest number of individuals are concentrated.

The ecological pyramid rule defines one very interesting pattern. It consists in the fact that the base of the ecological pyramid, namely vegetation, which is the basis of nutrition, is about ten times larger than the mass of animals that eat plant food.

Moreover, each next level is also ten times less than the previous one. So it turns out that the extreme upper level contains the least mass and energy. What does this pattern give us?

The role of the pyramid rule

Many problems can be solved based on the ecological pyramid rule. For example, how many eagles can grow when there is a certain amount of grain, when frogs, snakes, grasshoppers and an eagle are involved in the food chain.

Based on the fact that only 10% of the energy is transferred to the highest level, such problems can be easily solved. We have learned what ecological pyramids are, identified their rule and patterns. But what kind of ecological pyramids exist in nature, we will now talk.

Types of ecological pyramids

There are three types of pyramids. Based on the initial definition, it can already be concluded that they are associated with the number of individuals, their biomass and the energy contained in them. In general, first things first.

Pyramid of numbers

The name speaks for itself. This pyramid reflects the number of individuals at all levels separately. But it is worth noting that in ecology it is used quite rarely, since there are a very large number of individuals at the same level, and it is rather difficult to give a complete structure of the biocenosis.

All this is much easier to imagine using one specific example. Let's say there are 1,000 tons of green plants at the base of the pyramid. This vegetation is eaten by grasshoppers. Their number, for example, is somewhere around thirty million. Ninety thousand frogs are capable of consuming all these grasshoppers. The frogs themselves are the food of 300 trout. One person can eat this amount of fish in a year. What do we get? And it turns out that at the base of the pyramid there are millions of blades of grass, and at the top of the pyramid there is only one person.

It is here that we can observe how, when moving from one level to each subsequent level, the indicators decrease. The mass, the number of individuals decreases, the energy contained in them decreases. It should be noted that there are exceptions. For example, sometimes there are reversed eco-pyramids of numbers. Let's say insects live on a certain tree in the forest. All insectivorous birds feed on them.

Biomass pyramid

The second scheme is the biomass pyramid. It also represents a ratio. But in this case it is the ratio of the masses. As a rule, the mass at the base of the pyramid is always much greater than at the highest trophic level, and the mass of the second level is higher than the mass of the third level, and so on. If organisms at different trophic levels do not really differ in size, then in the figure it just looks like a quadrangular pyramid tapering upward. One of the American scientists explained the structure of this pyramid using the following example: the weight of the vegetation in the meadow is much greater than the weight of individuals consuming these plants, the weight of herbivores is higher than the weight of carnivores of the first level, the weight of the latter is higher than the weight of carnivores of the second level, and so on.

For example, one lion weighs a lot, but this individual is so rare that compared to the mass of other individuals, its own weight is negligible. Exceptions are also found in such pyramids, when the mass of producers is less than the mass of consumers. Let's consider this using the example of a water system. The mass of phytoplankton, even taking into account the high productivity, is less than the mass of consumers, for example, whales. Such pyramids are called inverted or inverted.

Energy pyramid

And finally, the third type of ecological pyramid is the energy pyramid. It reflects the speed at which a mass of food passes through the chain, as well as the amount of this energy. This law was formulated by R. Lindemann. It was he who proved that with a change in the trophic level, only 10% of the energy that was at the previous level is transferred.

The initial energy percentage is always 100%. But if only a tenth of it passes to the next trophic level, then where does most of the energy go? Its main part, namely 90%, is spent by individuals to ensure all life processes. Thus, there is also a certain pattern here. A much smaller part of the energy flows through the upper trophic levels, where the mass and number of individuals is smaller, than it passes through the lower levels. This can explain the fact that there are not so many predators.

Disadvantages and advantages of ecological pyramids

Despite the number of different types, almost each of them has a number of disadvantages. These are, for example, pyramids of numbers and biomass. What is their disadvantage? The fact is that building the first one causes some difficulties if the spread in the number of different levels is too great. But the difficulty lies not only in this.

The energy pyramid is able to compare productivity, as it takes into account the most important time factor. And, of course, it should be said that such a pyramid never turns upside down. Thanks to this, it is a kind of standard.

The role of the ecological pyramid

The ecological pyramid is what helps us to understand the structure of the biocenosis, to describe the state of the system. Also, these schemes help in determining the permissible amount of fish catch, the number of animals shot.

All this is necessary in order not to violate the overall integrity and sustainability of the environment. The pyramid, in turn, helps us understand the organization of functional communities, as well as compare different ecosystems in terms of their productivity.

Ecological pyramid as a correlation of features

Based on the above types, we can conclude that the ecological pyramid is a certain ratio of indicators related to the number, mass and energy. The levels of the ecological pyramid are different in all respects. Higher rates have lower levels and vice versa. Do not forget about inverted circuits. Here consumers are superior to producers. But this is not surprising. Nature has its own laws, exceptions can be anywhere.

The energy pyramid is the simplest and most reliable, as it takes into account the most important time factor. Thanks to this, it is she who is considered to be a kind of standard. The role of ecological pyramids is very important for maintaining the balance of natural ecosystems and ensuring their sustainability.