Trophic chain. Pasture food chain. Trophic food chain

The trophic chain is a relationship at the nutritional level between various macro- and microorganisms through which the transformation of energy and matter takes place in ecosystems. All plant, animal and microscopic organisms are closely linked by the principle of "food-consumer".

Basic Definitions

The trophic chain is one of the most significant properties of any ecosystem. This is a food chain. It shows a certain horizontal sequence of species. This reflects the movement in the ecosystem in the process of feeding biochemical energy and organic substances. For example: grass - hare - wolf - bacteria. As a rule, there is a large predator at the top of the trophic pyramid. The term itself is a derivative of the Greek word "trophy", which means "food". Before you figure out what a food chain is, you need to consider such concepts as producers, consumers and decomposers.

Producers

Producers call a group of organisms that are able to synthesize complex organic substances from mineral compounds. These include, in the first place, autotrophs. These are plants and microscopic algae, which are able by photosynthesis to convert external solar energy into biochemical. It accumulates in cells and participates in metabolism. In ecosystems, examples of producers are ferns, mosses, gymnosperms and flowering plants. In the ocean it is plankton. The smallest green algae is an example of the producers of all aquatic ecosystems.

Consumables

Consumers are different kinds of organisms, feeding exclusively on organic matter, which producers synthesize. In the ecosystem, consumers are called heterotrophs. It can be carnivorous and herbivorous animals, insects. There are consumers of different orders. This division is based on the position of organisms in the food chain.

To consumers of the first order are herbivorous animals, insects and birds. For example, the forest food chain may include a hare, mouse, roe deer, elk. All these animals are consumers of the first order. Their distinctive feature is that they eat the producers, that is, the plants. They are mainly rodents, ungulates, snakes, lizards and various amphibians, as well as insects, fish, small birds.

Consumers of the second and subsequent orders are exclusively predatory species. They build their proteins from organic material of animal and plant origin. This group includes bears, a family of canine, feline, large predatory birds, reptiles and snakes. In the ocean ecosystem this niche is occupied by whales and dolphins.

Reedents

Reducers are called microorganisms utilizing organic residues. These are bacteria and fungi. They live in the soil and activate the processes of decay. A synonym for the word "decomposers" is the term "destructors". At present, bacteriophages are also added to this group.

The main types of trophic chains

There are only two main types of food chains: detrital and pasture. They have significant differences. The pasture food chain (or chain of eating) is built on the complex relationships of various groups of plants, animals and saprophytes. Its basis is autotrophic organisms. This is primarily a plant. Then there are herbivorous animals. For example, ungulates or rodents. In the oceans and seas it can be zooplankton. And, finally, at the top of the food chain are predators of the 2nd order. These are species that are not hunted in the wild. For example, bears, representatives of the cat family, birds of prey. Especially the long pasture food chains in the oceans. Here, consumers of the 6th and 7th order are found.

Detrital trophic chains are based on decomposition processes. They always have mushrooms or microorganisms-saprophytes.

Detrital trophic chains

Such decomposition chains are most common in forests, and also where most of the plant mass is not directly consumed by herbivorous animals. But at the same time it disappears. It is processed by microscopic fungi and bacteria, called saprophytes. All detrital food trophic chains always begin with detritus. They continue with microorganisms that destroy them and utilize them. Then there are detritophages and their consumers - predatory species. Detrital chains also predominate in the ecosystems of the seas and the ocean, especially at great depths. Here, conditions are created in which a large number of predators do not survive, so microorganisms take their place.

Trophic levels

The trophic chain consists of several levels. These links can be easily detected in any ecosystem of the planet. The first level is always represented by producers. The second - consumers of different orders. In short chains, as a rule, there are three links, in long chains there are no restrictions. But microorganisms and mushrooms will always be the last. Any trophic food chain ends up with decomposers. Their main function in various ecosystems is the utilization of organic matter to mineral compounds. The longest trophic food chains are formed in the oceans and seas. The shortest of them is in the forest and meadows. Such an interconnected series of successive trophic levels forms a food chain.

It is very important to clarify that the food chain is not always complete. It may lack some links. Sometimes they "drop out" for one reason or another. Firstly, not always in the chain are plant-producers. They are absent in those communities that were formed on the basis of rotting plant and (or) animal remains. A striking example is the litter of leaves in the woods. Secondly, in trophic chains there may be no heterotrophs, that is, animals. Either they may be few. For example, in the same forests falling fruits and branches, bypassing consumers, immediately begin to decompose. In this case, the producers immediately follow the decomposers. In each ecosystem, trophic chains are formed, based on environmental conditions. Under certain influences, especially from the human side, these chains can increase or, as it often happens, decrease due to the disappearance of certain links.

Examples of trophic chains

The trophic chain, depending on the number of links it consists of, can be simple and multilevel. An example of a simple complete chain, in which producers, consumers and decomposers are present, can look as follows: aspen-beaver-bacteria.

Complex trophic chains contain a greater number of links. But usually their number does not exceed 6-7 in existing natural ecosystems. Such long chains can be found in the seas and oceans. In the rest of the real ecosystems, the links are usually 5. There are several examples of how to compose a food chain for different ranges:

1. Algae - roach - perch - burbot - bacteria.

2. Plankton - coral - pomatsentrovye fish - white shark - bacteria.

3. Grass - a grasshopper - a frog - so - a falcon.

All these are examples of pasture predator chains. But there are other types of relationships. For example, a chain of parasites. They look like this: grass - cow - tapeworm - bacteria. Sometimes from the chain can drop out the consumer: Currantum - mildewed mushroom - phage. Pasture food chain differs from parasitic in that the size of predators in them increases as the level of the link sequence increases. But in the role of decomposers there are still saprophytes in both cases. The detrital chains look a little different: leaf litter - microscopic mold fungi - bacteria.