Second order consumables are. Food chain

Plant material ( e.g. nectar) → fly → spider → shrew → owl

Rose bush juice → aphids → ladybug → spider → insectivorous bird → bird of prey

Reducers and detritivores (detrital food chains)

There are two main types of food webs - grazing and detrital. Above were examples of pasture chains in which the first trophic level is occupied by green plants, the second by pasture animals and the third by predators. The bodies of dead plants and animals still contain energy and " construction material", As well as intravital secretions such as urine and faeces. These organic materials are degraded by microorganisms, namely fungi and bacteria that live as saprophytes on organic debris. Such organisms are called reducers... They release digestive enzymes into dead bodies or waste products and absorb the products of their digestion. The decomposition rate can vary. Organic matter from urine, faeces and animal carcasses is consumed in a few weeks, while fallen trees and branches can decompose for many years. A very significant role in the decomposition of wood (and other plant residues) are played by mushrooms that secrete an enzyme called cellulose, which softens the wood, allowing small animals to enter and absorb the softened material.

Pieces of partially decomposed material are called detritus, and many small animals (deposit feeders) feed on it, accelerating the decomposition process. Since this process involves both true decomposers (fungi and bacteria) and detritivores (animals), both are sometimes called decomposers, although in reality this term refers only to saprophytic organisms.

Larger organisms, in turn, can feed on detritus feeders, and then a food chain of a different type is created - a chain that begins with detritus:

Detritus → detritophage → predator

Detritus feeders of forest and coastal communities include earthworm, wood lice, carrion fly larva (forest), polychaete, scarlet, sea cucumber (coastal zone).

Here are two typical detrital food chains in our forests:

Litter → Earthworm → Blackbird → Sparrowhawk

Dead Animal → Carrion Fly Larvae → Common Frog → Common Snake

Some typical detritophages are earthworms, wood lice, two-legged and smaller (<0,5 мм) животные, такие, как клещи, ногохвостки, нематоды и черви-энхитреиды.

Food webs

In food chain diagrams, each organism is represented as feeding on other organisms of one type. However, the real food connections in an ecosystem are much more complex, since an animal can feed on organisms of different types from the same food chain or even from different food chains. This is especially true for the predators of the upper trophic levels. Some animals feed on both other animals and plants; they are called omnivores (such is, in particular, man). In reality, food chains are intertwined in such a way that a food (trophic) web is formed. A food web diagram can show only a few of the many possible relationships, and it usually includes only one or two predators from each of the upper trophic levels. Such diagrams illustrate nutritional relationships between organisms in an ecosystem and serve as a basis for quantitative studies of ecological pyramids and ecosystem productivity.

Ecological pyramids.

The pyramids of numbers.

To study the relationships between organisms in an ecosystem and to graphically represent these relationships, it is more convenient to use not food web diagrams, but ecological pyramids... In this case, the number of different organisms in a given territory is first counted, grouping them according to 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. This can be displayed as a population pyramid.

For convenience, the number of organisms at a given trophic level can be represented as a rectangle, the length (or area) of which is proportional to the number of organisms inhabiting a given area (or in a given volume, if it is an aquatic ecosystem). The figure shows a pyramid of numbers that reflects the real situation in nature. Predators located at the highest trophic level are called terminal predators.

Fourth trophic level Tertiary consumers

Third trophic level Secondary consumers

Second trophic level Primary consumers

First trophic Primary producers

level

Biomass pyramids.

The disadvantages associated with the use of size pyramids can be avoided by constructing biomass pyramids, which 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. Thus, the rectangles in the biomass pyramids represent the mass of organisms of each trophic level per unit area or volume.

When sampling - in other words, at a given point in time - the so-called growing biomass, or growing yield, is always determined. It is important to understand 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 biomass consumption (loss due to eating) roughly corresponds to the rate of its formation, then the growing crop does not necessarily indicate productivity, i.e. about the amount of energy and matter passing from one trophic level to another over a given period of time, for example, 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. Producer of small size, such as algae, is characterized by a high rate of regeneration, i.e. high growth and reproduction rate, balanced by their intensive consumption for food by other organisms and natural death. Thus, while standing biomass may be low compared to large producers (eg trees), productivity may not be lower, since trees accumulate biomass over a long period of 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 durable plants and animals have a lower rate of renewal compared to small and short-lived ones and accumulate matter and energy for a longer time. Zooplankton has a higher biomass than the phytoplankton 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.

PRIMARY CONSUMMENT - an organism, for example, a rabbit or deer, which feeds mainly or exclusively on green plants, their fruits or seeds. [...]

They are primary consumers that feed on algae, bacteria and detritus. They reproduce sexually (although crustaceans and rotifers can reproduce in other ways) and therefore reproduce more slowly than phytoplankton. The process of feeding zooplankton occurs through filtration and grazing of phytoplankton; in mesotrophic water bodies, consumption can be comparable to the rate of primary production. Most are 0.5-1mm in length, but some may be less than 0.1mm. Zooplankton includes both plant and carnivorous organisms. In lakes, they migrate during daylight hours into deeper waters, an almost transparent outer shell protects them from death (being devoured by fish). [...]

Against the background of primary zoning, based mainly on physical factors, secondary zoning is clearly traced - both vertical and horizontal; this secondary zoning manifests itself in the distribution of communities. Communities of each primary zone, with the exception of the euphotic one, are subdivided into two fairly distinct vertical components - benthic, or bottom (benthos), and pelagic. In the sea, as well as in large lakes, plant producers are represented by microscopic phytoplankton, although large multicellular algae (macrophytes) may be of significant importance in some coastal areas. The primary consumers, therefore, are mainly zooplankton. Medium-sized animals feed on either plankton or detritus formed from plankton, while large animals are mainly predators. There are only a small number of large animals, which, like large land animals such as deer, cows and horses, feed exclusively on plant foods. [...]

Primary macroconsumptions, or plant-eating animals (see Fig. 2.3, IIA and IIB), feed directly on living plants or parts of them. There are two types of primary macroconsumptions in the pond: zooplankton (animal plankton) and benthos (bottom forms), corresponding to two types of producers. In a grassland ecosystem, herbivorous animals are also divided into two size groups: small - herbivorous insects and other invertebrates, and large - herbivorous rodents and ungulate mammals. Another important type of consumers is represented by detritivores (IIIA and IIIB), which exist due to the "rain" of organic detritus falling from the upper autotrophic layers. Together with herbivores, detritivores serve as food for carnivores. Many, and perhaps even all, detritivorous animals receive most of their food by digesting microorganisms that have colonized detritus particles. [...]

Р - producers С, - primary consumers. D. Soil arthropods - according to Engelian (1968). [...]

Then the primary consumers are connected - herbivorous animals (T) and, finally, carnivorous consumers (X). All of them occupy a certain place in the hierarchy of participants in the biotic cycle and perform their functions in transforming the branches of the energy flow that reach them and in transferring biomass. But all are united, impersonalizes their substances and the system of unicellular destructors closes the common circle. They return to the abiotic environment of the biosphere all the elements necessary for new and new turns of the cycle. [...]

The second group is represented by consumers, i.e. consumers (from Lat. consumo - to consume) - heterotrophic organisms, mainly animals that eat other organisms. Distinguish between primary consumers (animals that eat green plants, herbivores) and secondary consumers (predators, carnivores that eat herbivores). A secondary consumer can serve as a food source for another predator - a consumer of the third order, etc. [...]

A person eating cow meat is a secondary consumer at the third trophic level, and eating plants is a primary consumer at a second trophic level. Each person for the physiological functioning of the body requires about 1 million kcal of energy per year, obtained through food. Humanity produces about 810 5 kcal (with a population of over 6 billion people), but this energy is distributed extremely unevenly. For example, in a city, energy consumption per person reaches 80 million kcal per year, i.e. for all types of activities (transport, household, industry) a person spends 80 times more energy than is necessary for his body. [...]

All producers belong to the first trophic level, all primary consumers, regardless of whether they feed on living or dead producers, belong to the second trophic level, respectively, consumers of the second order - to the third, etc. As a rule, the number of trophic levels is not exceeds three-four. B. Nebel (1993) confirms this conclusion as follows: the total mass of organisms (their biomass) at each trophic level can be calculated by collecting (or trapping) and then weighing the corresponding samples of plants and animals. Thus, it has been established that at each trophic level the biomass is 90-99% less than at the previous one. From this, it is easy to imagine that the existence of a large number of trophic levels is impossible due to the fact that the biomass will very quickly approach zero. Graphically, this is represented as a biomass pyramid (Fig. 47). [...]

The amount of detritus formed also increases. Corresponding changes are taking place in food webs. Detritus becomes the main source of nutrients. [...]

3.15

In the case of pasture forest food chains, when trees are producers and insects are primary consumers, the level of primary consumers is numerically richer than individuals of the producer level. Thus, the pyramids of numbers can be reversed. For example, in Fig. 9.7 shows the pyramids of the ecosystems of the steppe and forest of the temperate zone. [...]

A fish pond is a good example of how secondary production depends on 1) the length of the food chain, 2) primary productivity, and 3) the nature and amount of energy supplied from outside to the pond system. As shown in table. 3.11, large lakes and seas yield 1 m2 less fish than small productive fertilized ponds with intensive farming, and the point is not only that in large reservoirs the primary productivity is lower and food chains are longer, but also in the fact that in these In large reservoirs, a person collects only a part of the consumer population, namely that part that is beneficial to him. In addition, the yield is several times higher when breeding herbivorous species (for example, carp) than when breeding predatory species (perches, etc.); the latter, of course, need a longer food chain. High yields of products indicated in table. 3.11. Therefore, when calculating production per unit of area in such cases, it would be necessary to include the area of ​​the land from which additional food comes. Many people incorrectly assess the high productivity of water bodies in the countries of the East, comparing it with the productivity of fish ponds in the United States, where additional food is usually not supplied. Naturally, the method of pond farming depends on the population density in the area. [...]

Upstream communities are said to be shaded by tree canopy and receive little light. Consumables depend mainly on leaf litter and other allochthonous organic matter. The fauna of the river is represented mainly by primary consumers related to mechanical destroyers. [...]

Despite the diversity of food chains, they have common patterns: from green plants to primary consumers, from them to secondary consumers, etc., then to detritophages. Detritivores are always in last place, they close the food chain. [...]

The lakes are home to fish that can consume large amounts of phytoplankton. They belong to primary consumers, since they feed on ready-made organic matter, they cannot create kiyuro on their own. Other animals, mainly insect larvae and some fish, feed on zooplankton; they are secondary consumers. Fish use as food a variety of inhabitants of the reservoir (Fig. 2.22). [...]

Biotic communities of each of the indicated zones, except for the euphotic one, are divided into benthic and pelagic. In them, zooplankton are the primary consumers; crustaceans are ecologically replacing insects in the sea. The overwhelming majority of large animals are predators. The sea is characterized by a very important group of animals, which are called sessile (attached). They are not found in freshwater systems. Many of them resemble plants and hence their names, such as sea lilies. Mutualism and commensalism are widely developed here. All benthos animals in their life cycle go through the pelagic stage in the form of larvae. [...]

Each link in the food chain is called a trophic level. The first trophic level is occupied by autotrophs, otherwise referred to as primary producers. Organisms of the second trophic level are called primary consumers, the third - secondary consumers, etc. Usually there are four or five trophic levels and rarely more than six (Fig. 5.1). [...]

A deer eating buds and young bark from trees will already be the first consumer of these substances and the energy contained in them, or the primary consumer. Moving from tree to tree, he loses energy, but at the same time gains much more than he spends. A large predator, for example a wolf, is a secondary consumer, since by eating a deer, it receives energy, so to speak, from second hand. [...]

[ ...]

VEGETABLE - an organism, such as a rabbit or deer, which feeds mainly on green plants or their fruits and seeds. [...]

TROPHIC LEVEL - the stage of movement of solar energy (as part of food) through the ecosystem. Green plants are at the first trophic level, primary consumers - at the second, secondary - at the third, etc. [...]

The place of each link in the food chain is the trophic level. The first trophic level, as noted earlier, is occupied by auto-trophies, or the so-called primary producers. Organisms of the second trophic. level are called primary consumers, the third - secondary consumers, etc. [...]

The metabolism of the system is carried out by solar energy, and the metabolic rate and the relative stability of the pond system depend on the intensity of the influx of substances with atmospheric precipitation and runoff from the drainage basin. [...]

Complex forms of interdependence of plants and animals were also formed on the basis of direct trophic connections. The balance of the plant biomass withdrawn by phytophages, which determines the stable relations between the populations of producers and primary consumers, is largely determined by the adaptations of plants to restrict their grazing by animals. Such adaptations include, in particular, the formation of a hard bark, various kinds of thorns, thorns, etc. for effective reproduction of the number and density of populations of the species. [...]

First, multicellular plants (P) develop - the highest producers. Together with unicellular organisms, they create organic matter in the process of photosynthesis, using the energy of solar radiation. In the future, the primary consumers are connected - herbivorous animals (T), and then carnivorous consumers. We have considered the biotic circulation of the land. This fully applies to the biotic cycle of aquatic ecosystems, for example, the ocean (Fig. 12.17). [...]

On the ecosystem “step”, there is a shift in the ratio of the links of the ecological (in this case, energy) pyramid. For example, the general energy balance of two similar (say, meadow) ecosystems, in one of which large ungulates are the dominant primary consumers, and in the other small phytophagous invertebrates (after large herbivorous mammals have been destroyed in the ecosystem, most of the rodents and even a significant proportion of arthropods) may be similar. [...]

Due to a certain sequence of food relations, individual trophic levels of the transfer of substances and energy in the ecosystem, associated with the nutrition of a certain group of organisms, differ. Thus, the first trophic level in all ecosystems is formed by producers - plants; the second - primary consumers - phytophages, the third - secondary consumers - zoophages, etc. As already noted, many animals feed not at one, but at several trophic levels (for example, the diets of the gray rat, brown bear and humans). [...]

Analysis of the trophic relationships between fish larvae and food invertebrates makes it possible to imagine the complexity of these relationships. Fish larvae at different stages of development consume food items of different energy significance and thereby determine their distribution over trophic levels from consumers of the second to consumers of the fourth and fifth orders, and at the same stage of development they can simultaneously occupy different trophic levels. The larvae of pike perch, for example, pass through all links of the trophic chain from primary consumers to predators of the n-order, occupying at the same time two, sometimes three trophic levels. The transition of larvae at one or another stage of development to feeding on organisms of lower energy levels, which shortens the length of the food chain, can be considered as an adaptation leading to a balanced supply of energy through food during the period of their larval development. This is especially important in years with an unfavorable state of the food supply in the reservoir. Of the three trophic complexes of larvae in reservoirs - coastal phytophilic, coastal pelagic, and pelagic) - the most significant with a large number of species is coastal phytophilous. The larvae of this complex live in protected shallow waters, forming common schools, and do not make long-distance movements during the entire larval period of development, since different depths, islands, flooded shrubs, and different densities of coastal-aquatic vegetation create conditions for the ecological isolation of individual sections of the littoral zone. Larvae of perch and pike perch from open coastal areas also enter here, which, starting from stages D1 and Dg, form significant accumulations in the dark. Based on this, the protected coastal area should be considered not only a breeding ground for phytophilous fish, but also a feeding area for larvae of the main commercial species, requiring special treatment and protection. [...]

In the case of acidification of a watercourse, changes in its ecosystem have a different direction in many respects. Despite the fact that the biological diversity of the ecosystem is decreasing, the general structure of the river continuum is preserved. At the same time, the processes of destruction of organic matter by bacteria are suppressed and the biomass of primary consumers is significantly reduced, which often leads to an increase in biomass and complication of the spatial structure of the periphyton. The role of secondary consumers sharply increases, among which the predatory larvae of aquatic insects dominate. Many of them have a multi-year life cycle and can be classified as r-strategists. In general, acidification leads to the predominance of pasture food chains, a decrease in the rate of destruction of organic matter and an increase in the P / R and K2 ratio of the ecosystem and, therefore, causes a shift in the functioning of the ecological system of the watercourse to an equilibrium state. [...]

The remoteness of the food chain organism from the producers is called the food or trophic level. Organisms that receive energy from the Sun in the food chain through the same number of steps are considered to belong to the same trophic level. So. green plants occupy the first trophic level (producer level), herbivores - the second (primary consumer level), primary predators eating herbivores, the third (secondary consumer level), and secondary predators - the fourth (tertiary consumer level). An organism of a given species can occupy one or several trophic levels, depending on what energy sources it uses. [...]

There are calculations showing that 1 hectare of a certain forest receives an average of 2.1 109 kJ of solar energy annually. However, if all the plant matter stored in a year is burned, then as a result we will receive only 1.1 106 kJ, which is less than 0.5% of the incoming energy. This means that the actual productivity of photosynthetics (green plants), or primary productivity, does not exceed 0.5%. Secondary productivity is extremely low: during the transfer from each previous link of the trophic chain to the next, 90-99% of energy is lost. If, for example, per 1 m2 of soil surface, plants create an amount of a substance equivalent to about 84 kJ per day, then the production of primary consumers will be 8.4 kJ, and secondary ones will not exceed 0.8 kJ. There are specific calculations that for the formation of 1 kg of beef, for example, 70-90 kg of fresh grass is needed. [...]

Secondary production is defined as the rate of formation of new biomass by heterotrophic organisms. Unlike plants, bacteria, fungi, and animals are unable to synthesize the complex, energy-rich compounds they need from simple molecules. They grow and receive energy by consuming plant matter either directly or indirectly by eating other heterotrophs. Plants, the primary producers, constitute the first trophic level in the community. On the second are the primary consumers; on the third - secondary consumers (predators), etc. [...]

The concept of energy flow not only allows one to compare ecosystems with each other, but also provides a means for assessing the relative role of populations in them. Table 14 shows estimates of density, biomass and energy flow rate for 6 populations that differ in the size of individuals and in habitat. The numbers in this series vary by 17 orders of magnitude (1017 times), the biomass - by about 5 orders of magnitude (10 ° times), and the energy flow - only about 5 times.This comparative uniformity of energy flows indicates that all 6 belong to the same trophic level in their communities (primary consumers), although this cannot be assumed either in terms of abundance or biomass. A kind of "ecological rule" can be formulated: data on abundance lead to an exaggeration of the importance of small organisms, and data on biomass - to an exaggeration of the role of large organisms; Consequently, these criteria are unsuitable for comparing the functional role of populations that differ greatly in the ratio of metabolic rate to individual size, although, as a rule, biomass is still a more reliable criterion than abundance. At the same time, the flow of energy (ie, P-D) serves as a more suitable indicator for comparing any component with another and all components of the ecosystem with each other. [...]

In fig. Figure 4.11 presents a graphical model of the “lower” part of the water cycle, showing how biotic communities adapt to changing conditions in the so-called continuum of rivers (gradient from small to large rivers; see Wanzo-le et al., 1980). The upper reaches of the rivers are small and often completely shaded so that the aquatic community receives little light. Consumers depend mainly on leaf and other organic detritus from the drainage basin. Detritus is dominated by large organic particles, for example, fragments of leaves, and the fauna is represented mainly by aquatic insects and other primary consumers, which ecologists studying river ecosystems refer to as mechanical destroyers. The ecosystem of the upper reaches is heterotrophic; the P / I ratio is much less than one. [...]

Precipitation from atomic explosions differs from radioactive waste in that the radioactive isotopes generated by the explosion combine with iron, silicon, dust, and everything else in the vicinity, resulting in relatively insoluble particles. These particles, often resembling tiny marbled beads of various colors under the microscope, range in size from a few hundred microns to nearly colloidal sizes. The smallest of them adhere tightly to plant leaves, causing radioactive damage to the leaf tissue; if such leaves are eaten by any herbivorous animal, the radioactive particles are dissolved in its digestive juices. Thus, this type of sediment can be directly included in the food chain at the trophic level of herbivorous, or primary, consumers. [...]

The transfer of food energy from its source - plants - through a number of organisms, which occurs by eating some organisms by others, is called the food chain. With each next transfer, most (80-90%) of the potential energy is lost, turning into heat. This limits the number of steps, or "links" in the chain, possible, usually to four or five. The shorter the food chain (or the closer the body is to its beginning), the greater the amount of available energy. Food chains can be divided into two main types: grazing chains, which begin with a green plant and go on to grazing, herbivorous animals (that is, organisms that eat green plants) and predators (organisms that eat animals), and detrital chains , which start from dead organic matter, go to microorganisms that feed on them, and then to detritus feeders and their predators. Food chains are not isolated from one another, but closely intertwined. Their plexus is often referred to as the food web. In a complex natural community, organisms that receive their food from plants through the same number of stages are considered to belong to the same trophic level. Thus, green plants occupy the first trophic level (the level of producers), herbivores - the second (level of primary consumers), predators eating herbivores - the third (level of secondary consumers), and secondary predators - the fourth level (level of tertiary consumers). It must be emphasized that this trophic classification divides into groups not the species themselves, but their types of vital activity; a population of one species can occupy one or more trophic levels, depending on what energy sources it uses. The flow of energy through the trophic level is equal to the total assimilation (L) at this level, and the total assimilation, in turn, is equal to the production of biomass (P) plus respiration (/?).

According to their participation in the biogenic circulation of substances in biocenoses, three groups of organisms are distinguished:

1) Producers(producers) - autotrophic organisms that create organic substances from inorganic ones. The main producers in all biocenoses are green plants. The activity of producers determines the initial accumulation of organic matter in the biocenosis;

Order I consumables.

This trophic level is compiled by the direct consumers of primary production. In the most typical cases, when the latter is created by photoautotrophs, these are herbivorous animals. (phytophages). The species and ecological forms representing this level are very diverse and adapted to feeding on various types of plant food. Due to the fact that plants are usually attached to the substrate, and their tissues are often very strong, many phytophages have evolved a gnawing type of mouth apparatus and various adaptations for grinding and grinding food. These are dental systems of the gnawing and grinding type in various herbivorous mammals, the gizzard of birds, which is especially pronounced in granivores, etc. n. The combination of these structures determines the ability to grind solid food. The gnawing mouth apparatus is characteristic of many insects, etc.

Some animals are adapted to feeding on plant sap or flower nectar. This food is rich in high-calorie, easily digestible substances. The oral apparatus in species feeding in this way is arranged in the form of a tube, with the help of which liquid food is absorbed.

Adaptations to plant nutrition are also found at the physiological level. They are especially pronounced in animals that feed on the coarse tissues of the vegetative parts of plants, which contain a large amount of fiber. In the body of most animals, cellulolytic enzymes are not produced, and the breakdown of fiber is carried out by symbiotic bacteria (and some protozoa of the intestinal tract).

Consumables partly use food to support life processes ("breathing costs"), and partly build their own body on its basis, thus carrying out the first, fundamental stage of the transformation of organic matter synthesized by producers. The process of creating and accumulating biomass at the consumer level is referred to as , secondary products.

Order II consumables.

This level unites animals with a carnivorous diet. (zoophages). Usually, all predators are considered in this group, since their specific features practically do not depend on whether the prey is a phytophagous or carnivorous. But strictly speaking, consumers of the second order should be considered only predators that feed on herbivorous animals and, accordingly, represent the second stage of the transformation of organic matter in the food chains. The chemical substances from which the tissues of an animal organism are built are rather homogeneous, therefore, the transformation during the transition from one level of consumers to another does not have such a fundamental character as the transformation of plant tissues into animals.

With a more careful approach, the level of consumers of the second order should be divided into sublevels according to the direction of the flow of matter and energy. For example, in the trophic chain "cereals - grasshoppers - frogs - snakes - eagles" frogs, snakes and eagles constitute successive sublevels of consumers of the second order.

In ecology, for the analysis of the system, an elementary structural unit is chosen as the object of research, which is subjected to comprehensive study. A necessary condition for constructing a structural unit is that it retains all the properties of the system.

The concept of “system” means a set of interconnected, mutually influencing, interdependent components not accidentally found together, but constituting a single whole.

For natural ecosystems, biogeocenosis is taken as the object of research, the structural diagram of which is shown in Fig. 1.

Fig. 1. Scheme of biogeocenosis (ecosystem), according to V.N. Sukachev

In accordance with the structural diagram, the biogeocenosis includes two main blocks:

biotope - a set of abiotic environmental factors or the whole complex of factors of inanimate nature;

(ecotope is a term close to a biotope, but with an emphasis on environmental factors external to the community, not only abiotic, but also biotic)

biocenosis - a set of living organisms.

Biotope, in turn consists of a set of climatic (climatopes) and soil (edaphotop) and hydrological (hydrotope) environmental factors.

Biocenosis includes plant communities (phytocenosis ), animals (zoocenosis) and microorganisms (microbocenosis ).

Arrows in Fig. 1 denote information transmission channels between different components of the biogeocenosis.

One of the most important properties of biogeocenosis is interconnection and interdependence of all its components.

It is quite understandable that the climate completely determines the state and regime of soil-soil factors, creates a habitat for living organisms.

In turn, the soil to some extent determines the climatic features (for example, its reflectivity (albedo) depends on the color of the soil surface, and, consequently, the heating and humidity of the air), and also affects animals, plants and microorganisms.

All living organisms are closely related to each other by various food, spatial or environment-forming relationships, being for each other either a food source, or a habitat, or a factor of mortality.

Particularly important is the role of microorganisms (primarily bacteria) in the processes of soil formation, mineralization of organic substances and often acting as causative agents of diseases of plants and animals.

2.2. Functional organization of ecosystems.

The main function of ecosystems is to maintain the cycle of substances in the biosphere, which is based on the food relationships of species.

Despite the huge variety of species that make up various communities, each ecosystem necessarily includes representatives of three functional groups of organisms - producers, consumers and reducers.

The vast majority of biogeocenoses are based on producers (manufacturers) - these are autotrophic organisms (from the Greek "auto" - itself and "trofo" - food) , which have the ability to synthesize organic matter from inorganic, using solar energy or the energy of chemical bonds.

Depending on the source of energy used, two types of organisms are distinguished: photoautotrophs and chemoautotrophs.

Photoautotrophs are organisms that, using solar energy, are able to create organic matter during photosynthesis.

Photoautotrophic organisms include plants, as well as blue-green algae (cyanobacteria).

However, not all plants are producers, for example:

some mushrooms (caps, molds), as well as some flowering species (for example, codwood), which do not contain chlorophyll, are not capable of photosynthesis and therefore feed on ready-made organic substances.

Chemoautotrophs are organisms that use the energy of chemical bonds as an energy source for the formation of organic substances.

Chemoautotrophic organisms include: hydrogen, nitrifying bacteria, iron bacteria, etc.

The group of chemoautotrophic organisms is not numerous and does not play a fundamental role in the biosphere.

Only producers (producers) are able to produce for themselves energy-rich food, i.e. are self-feeding. Moreover, they directly or indirectly provide consumers and decomposers with nutrients.

Consumptions (consumers) - these are heterotrophic organisms (from the Greek "hetero" - different) , which use living organic matter as food for obtaining and storing energy.

The main source of energy for heterotrophic organisms is the energy released during the cleavage of chemical bonds of organic substances created by autotrophic organisms.

Thus, heterotrophs are entirely dependent on autotrophs.

Depending on the power sources, a distinction is made between:

First-order consumables (phytophages) are herbivorous organisms that feed on various types of plant food (producers).

Examples of primary consumers are:

birds eat seeds, buds and foliage;

deer and hares feed on branches and leaves;

grasshoppers and many other types of insects consume all parts of plants for food;

In aquatic ecosystems, zooplankton (small animals that move mainly with the flow of water) feed on phytoplankton (microscopic, usually unicellular algae).

Second-order consumables (zoophages) are carnivorous organisms that feed exclusively on herbivorous organisms (phytophages).

Examples of secondary consumers are:

insectivorous mammals, birds and insect-eating spiders;

seagulls eating shellfish and crabs;

fox feeding on hares;

tuna that feeds on herring and anchovies.

Third-order consumables are carnivores that feed only on carnivores.

Examples of tertiary consumers are:

a hawk or falcon that feeds on snakes and ermines;

sharks that feed on other fish.

Meet consumers of the fourth and higher orders.

In addition, there are many types with mixed type of food :

when a person eats fruits and vegetables, he is a first-order consumer;

when a person eats meat of a herbivorous animal, then he is a secondary consumer;

when a person eats fish that feeds on other animals, which in turn eat algae, then the person acts as a consumer of the third order.

Euryphages are omnivorous organisms that feed on both plant and animal foods.

For example: pigs, rats, foxes, cockroaches and humans.

Reducers (destroyers)are heterotrophic organisms that feed on dead organic matter and mineralize it to simple inorganic compounds.

There are two main types of reducers: detritus feeders and destructors.

Detritus feeders are organisms that directly consume dead plant and animal debris (detritus).

Detritus feeders include: jackals, vultures, crabs, termites, ants, earthworms, millipedes, etc.

Destroyers are organisms that decompose complex organic compounds of dead matter into simpler inorganic substances, which are then used by producers.

The main destructors are: bacteria and fungi.

In this case, bacteria take part in the decomposition of animal residues, as they gravitate towards substrates with a slightly alkaline reaction.

Fungi, on the other hand, prefer slightly acidic substrates, so they are mainly involved in the decomposition of plant residues.

Thus, each living organism in the biogeocenosis performs a specific function, i.e. occupies a certain ecological niche in a complex system of ecological relationships with other organisms and factors of inanimate nature.

So, for example, in different parts of the world and in different territories there are systematically dissimilar, but ecologically similar species that perform the same functions in their biogeocenoses:

Herbaceous and forest vegetation in Australia differs significantly in species composition from the vegetation of a similar climatic region in Europe or Asia, but as producers in their biogeocenoses they perform the same functions, i.e. occupy basically the same ecological niches;

antelopes in the savannas of Africa, bison in the prairies of America, kangaroos in the savannas of Australia, being consumers of the first order, perform the same functions, i.e. occupy similar ecological niches in their biogeocenoses.

At the same time, often systematically close species, settling side by side in the same biogeocenosis, perform different functions, i.e. occupy different ecological niches:

two species of water bugs in the same body of water play a different role: one species leads a predatory lifestyle and is a tertiary consumer, and the other feeds on dead and decaying organisms and is a decomposer. This leads to a decrease in the competitive tension between them.

In addition, the same species at different periods of its development can perform different functions, i.e. occupy various ecological niches:

the tadpole eats plant food and is the primary consumer, and the adult frog, a typical carnivore, is the second order consumer;

among algae, there are species that function either as autotrophs or as heterotrophs. As a result, at certain periods of their lives, they perform various functions and occupy certain ecological niches.

Are you familiar with such concepts as consumers, reducers and producers? If not, then our article is for you. In fact, these organisms are well known to everyone. Who are they? Let's figure it out together.

The concept of the trophic chain

All components of the ecosystem are closely interconnected. Thanks to this, various communities are formed in nature. The structure of any ecosystem includes an abiotic and biotic part. The first is a collection of living organisms. It is called a biocenosis. The abiotic part includes mineral and organic compounds.

The functioning of any ecosystem is associated with the conversion of energy. Its main source is sunlight. Photosynthetic organisms use it to synthesize organic matter. Heterotrophs receive energy from the breakdown of organic matter. Only a small part of it is used for growth. And the rest is spent for oh the existence of vital processes.

As a result, queues are formed in which individuals of some species, their remains, or are a source of nutrition for others. They are called trophic or food chains.

Trophic levels

Each power chain consists of a certain number of links. It has been established that during the transition from one to the other, part of the energy is constantly lost. Therefore, the number of links is usually 4-5. The position of the population of certain species in the food chain is called the trophic level.

What are consumers

All organisms are grouped. These include representatives of absolutely all kingdoms of living nature, regardless of their level of organization. Let's consider each of them.

Consumables: orders

Heterotrophs occupy different levels in the food chain. All herbivorous species are The next level is predators. They are already second-order consumers.

Let's consider this hierarchy with a specific example. Let's say the food web looks like a mosquito, a frog, a stork. Which one is the first order consumer? This is a frog. Then the stork is a consumer of the second order. In nature, there are heterotrophs that feed on both plants and animals. Such consumers can simultaneously be at several trophic levels.

Producers

Speaking about what consumers are, we paid attention to the type of their food. Consider from this perspective another group of the food web. Producers are a group of organisms that are autotrophs. They are able to synthesize organic substances from minerals.

There are two types of producers: auto - and chemotrophs. The first use the energy of sunlight to create organics. These are plants, cyanobacteria, and some of the simplest animals. Chemotrophs have the ability to oxidize various chemical compounds. At the same time, energy is generated, which they use to carry out waste products. These include nitrogen-fixing, sulfur and iron bacteria.

The presence of producers is a prerequisite for the development of any ecosystem. This fact is explained by the fact that photosynthetic organisms are a source of energy supply.

Reducers

Another role in the ecosystem belongs to heterotrophic organisms, which feed on organic matter of residues or waste products of other species, which they decompose to mineral substances. This function is performed by reducers. Representatives of this group are bacteria and fungi.

It is at the level of producers in the ecosystem that energy is accumulated. Then it goes through consumers and producers, where it is consumed. At each subsequent trophic level, part of the energy is dissipated in the form of heat.

Types of power circuits

The energy in the ecosystem is divided into two streams. The first is directed to consumers from producers, in the second - from dead organics. Depending on this, food webs of the pasture and detrital types are distinguished. In the first case, the initial trophic level is the producers who transfer energy to consumers of different levels. The pasture chain ends with reducers.

The detrital chain begins with dead organic matter, and continues with saprotrophs, which are representatives of consumers. The last link in this chain is also the decomposers.

Within any ecosystem, many food chains exist simultaneously. They are all inseparable from each other and closely intertwined. This happens because representatives of one species can simultaneously be links in different chains. Thanks to this, food webs are formed. And the more ramified they are, the more stable the ecosystem.