The main process that occurs in all ecosystems is the transfer and circulation of matter or energy. Moreover, 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 up, which, as links in a chain, are connected by the food – consumer relationship. This sequence is called trophic, or food chain. And the links in it are trophic levels. The first level of the chain is producers, autotrophic organisms (plants), because only they can form organic substances from inorganic ones. The following links are consumers (animals) of various orders. Herbivores are consumers of the 1st order, and predators feeding on herbivores will be consumers of the 2nd order. The next link in the chain will be reducers - organisms whose food is the remnants of life or the corpses of living organisms.
Graphic pyramids
The British ecologist Charles Elton (1900-1991) in 1927, based on the analysis of quantitative changes in trophic 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.
Pyramid patterns
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 measurement 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 trophic chain decreases from level to level. The rules of the ecological pyramid are the quantitative ratio of the products of all levels of a particular food chain. It says that the chain level indicator is about 10 times smaller than that at the previous level.
The given simple example, which will dot all the “and”. Consider the trophic chain of algae - invertebrate crustaceans - herring - dolphin. A forty-kilogram dolphin needs to eat 400 kilograms of herring in order to survive. And in order for these 400 kilograms of fish to exist, about 4 tons of their food, invertebrate crustaceans, are needed. For the formation of 4 tons of crustaceans, already 40 tons of algae are needed. This is what the rules of the ecological pyramid reflect. And only in this ratio will this ecological structure be sustainable.
Types of Ecopyramids
Based on the criterion, which will be taken into account when evaluating the pyramids, allocate:
- Numeric.
- Estimates of biomass.
- Energy consumption.
In all cases, the ecological pyramid rule reflects a 10-fold decrease in the main evaluation criterion.
Number of individuals and trophic steps
The pyramid of numbers takes into account the number of organisms in the trophic chain, which is reflected in the rule of the ecological pyramid. And the dolphin example is fully suited to characterizing this type of pyramid. But there are exceptions - the forest ecosystem with a chain of plants - insects. The pyramid will be turned upside down (a huge number of insects feeding on one tree). That is why the pyramid of numbers is considered not the most informative and indicative.
What is left over?
The biomass pyramid as a criterion for evaluation uses the dry (less often - raw) mass of individuals of the same level. The units are gram / square meter, kilogram / hectare or gram / cubic meter. But 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 of them are large and have a long life cycle. But for water systems, the pyramid may again turn upside down. For example, in the seas, the biomass of zooplankton feeding on algae is sometimes 3 times greater than the biomass of plant plankton itself. The stability of the system is saved by the high reproduction rate of phytoplankton.
Energy flow is the most accurate indicator
Energy pyramids show the passage of food (its mass) through trophic levels. The law of the energy pyramid was formulated by an outstanding environmentalist from America, Raymond Lindeman (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 goes to each subsequent level, the remaining 90% is the loss that goes to support the body's vital functions (respiration, heat regulation).
The value of the pyramids
What the rules of ecological pyramids reflect, we have made out. But why do we need this knowledge? Pyramids of numbers and biomass make it possible to solve some practical problems, since they describe a static and stable state of the system. For example, they are used in calculating the permissible values of fish catch or counting the number of animals for shooting in order not to violate the stability of the ecosystem and determine the maximum size of a particular population of individuals for a given ecosystem in its entirety. And the energy pyramid gives a clear idea of the organization of functional communities, allows you to compare different ecosystems by their productivity.
Now the reader is not taken aback, having received a task of the type “describe what the rules of the ecological pyramids reflect”, and boldly answer that these are losses of matter and energy in a particular trophic chain.