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limiting factors. The law of the minimum (J. Liebig's law), the definition of the limiting factor

The limiting factor is an environmental factor that goes beyond the endurance of the organism. The limiting factor limits any manifestation of the organism's vital activity. With the help of limiting factors, the state of organisms and ecosystems is regulated.

J. Liebig's law of the minimum - in ecology - a concept according to which the existence and endurance of an organism is determined by the weakest link in the chain of its environmental needs.

According to the law of the minimum, the vital possibilities of organisms are limited by those environmental factors, the quantity and quality of which are close to the minimum required by the organism or ecosystem.

Definition of the concept of "environmental factors"

The environment is everything that surrounds the body, i.e. it is that part of nature with which the organism is in direct or indirect interactions.

Under the environment we understand the complex of environmental conditions that affect the vital activity of organisms. The complex of conditions consists of various elements - environmental factors. Not all of them have the same effect on organisms. Thus, a strong wind in winter is unfavorable for large, openly living animals, but it does not affect smaller ones that take refuge under the snow or in burrows, or live in the ground. Those factors that have any effect on organisms and cause adaptive reactions in them are called environmental factors.

The influence of environmental factors affects all life processes of organisms and, above all, their metabolism. Organisms' adaptations to their environment are called adaptations. The ability to adapt is one of the main properties of life in general, as it provides the very possibility of its existence, the ability of organisms to survive and reproduce.

Classification of environmental factors.

Environmental factors have a different nature and specificity of action. By their nature, they are divided into two large groups: abiotic and biotic. If we subdivide the factors according to the reasons for their occurrence, then they can be subdivided into natural (natural) and anthropogenic. Anthropogenic factors can also be abiotic and biotic.

Abiotic factors (or physico-chemical factors) - temperature, light, pH of the environment, salinity, radioactive radiation, pressure, air humidity, wind, currents. These are all properties of inanimate nature that directly or indirectly affect living organisms.

Biotic factors are forms of influence of living beings on each other. The surrounding organic world is an integral part of the environment of every living being. The mutual relations of organisms are the basis for the existence of populations and biocenoses.

Anthropogenic factors are forms of human action that lead to a change in nature as a habitat for other species or directly affect their lives.

The action of environmental factors can lead to:

• · elimination of species from biotopes (change of biotope, territory, shift of population area; example: bird migration);
• · to changes in fecundity (population density, reproductive peaks) and mortality (death due to rapid and abrupt changes in environmental conditions);
• · to phenotypic variability and adaptation: modification variability - adaptive modifications, winter and summer hibernation, photoperiodic reactions, etc.

limiting factors. Liebig's law

The reaction of the organism to the influence of a factor is determined by the dosage of this factor. Very often, an environmental factor, especially an abiotic one, is tolerated by the body only within certain limits. The effect of the factor is most effective at some optimal value for a given organism. The range of the environmental factor is limited by the corresponding extreme threshold values ​​(minimum and maximum points) of this factor, at which the existence of an organism is possible. The maximum and minimum tolerated values ​​of the factor are the critical points beyond which death occurs. The limits of endurance between critical points are called ecological valency or tolerance of living beings in relation to a specific environmental factor. The population density distribution follows a normal distribution. The population density is the higher, the closer the value of the factor is to the average value, which is called the ecological optimum of the species for this parameter. Such a distribution law of population density, and consequently, of vital activity, was called the general law of biological stability.

The range of a favorable effect of a factor on organisms of a given species is called the optimum zone (or comfort zone). The optimum, minimum and maximum points are three cardinal points that determine the possibility of the body's reaction to this factor. The stronger the deviation from the optimum, the more pronounced the inhibitory effect of this factor on the body. This range of the factor value is called the zone of pessimum (or the zone of oppression). The considered patterns of the influence of the factor on the body are known as the rule of optimum.

Other regularities characterizing the interactions of the organism and the environment have also been established. One of them was established by the German chemist J. Liebig in 1840 and was called Liebig's law of the minimum, according to which plant growth is limited by the lack of a single nutrient, the concentration of which lies at a minimum. If other elements are contained in sufficient quantities, and the concentration of this single element drops below normal, the plant will die. Such elements are called limiting factors. So, the existence and endurance of an organism are determined by the weakest link in the complex of its ecological needs. Or the relative effect of a factor on the organism is the greater, the more this factor approaches a minimum in comparison with others. The yield value is determined by the presence in the soil of one of the nutrients, the need for which is met the least, i.e. This element is in the minimum quantity. As its content increases, the yield will increase until another element is at a minimum.

Later, the law of the minimum began to be interpreted more broadly, and now they are talking about limiting environmental factors. The environmental factor plays the role of a limiting factor in the case when it is absent or is below a critical level, or exceeds the maximum tolerable limit. In other words, this factor determines the ability of the organism in an attempt to invade a particular environment. The same factors can be either limiting or not. Example with light: for most plants it is a necessary factor as a source of energy for photosynthesis, while for fungi or deep-sea and soil animals this factor is not necessary. Phosphates in sea water are a limiting factor in the development of plankton. Oxygen in the soil is not a limiting factor, but in water it is a limiting factor.

Consequence from Liebig's law: the lack or excessive abundance of any limiting factor can be compensated by another factor that changes the attitude of the organism to the limiting factor.

3.1. "The Law of the Minimum" by J. Liebig

limiting Liebig's Law of the Minimum.

Limits of tolerance. Along with the conclusion that "plant growth depends on the nutrient element that is present in the minimum amount", which became the basis of Liebig's "law of the minimum", J. Liebig pointed to the range limiting indicators. It was found that not only a lack, but also an excess of factors such as light, heat and water can be a limiting factor. The concept of the limiting influence of the ecological maximum, along with the minimum, was introduced by W. Shelford (1913), who formulated the “law of tolerance”. The range between two values, the ecological minimum and the ecological maximum, which is characterized in one way or another by all living organisms was called limit of tolerance(from lat. toleratia - patience, tolerance). If a certain organism has a small range of tolerance to one of the variable factors, then this factor deserves close attention, because it may be limiting. For example, oxygen, which is quite available for organisms living in the terrestrial parts of ecosystems, can rarely be limiting. Whereas for organisms living under water, oxygen can become an important limiting factor. In the case of an extreme narrowing of the tolerance range, a living organism can spend all its metabolic energy on overcoming the stress associated with a decrease in the limits of the limiting factor, and die due to a lack of energy for normal life activity. If a polar bear, due to some circumstances, is moved to warmer climes, then it will have to spend all its metabolic energy on overcoming heat stress, and the animal will not have enough energy to get food and preserve its species in nature.

The concept of limiting factors in general extends widely to both biological and physical factors, and to present all that is known on this subject would require a large amount of printed work, which is beyond the scope of this book. However, given that the environmental engineer has to deal with physical factors more often, we will briefly list the main physical and climatic factors.

"The Law of the Minimum" by J. Liebig

Each individual, population, community is simultaneously affected by various factors, but only some of them are vital. These vital factors are called limiting. Most often, at least one factor lies outside the optimum. And the possibility of the existence of a species in a given place depends on this factor. Back in 1840, J. Liebig established that the endurance of an organism is determined by the weakest link in the chain of its environmental needs. It is his priority to study the various factors in plant growth and to find that plant yields can be most effectively increased by improving the minimum factor (usually by increasing the amount of N and P), rather than those nutrients that are required in large quantities, such as, such as carbon dioxide or water. Substances that are required in the smallest quantities, but which are very few in the soil, such as zinc, these substances become limiting. Liebig's concept that "the growth of a plant depends on that nutrient element present in the smallest amount" became known as Liebig's Law of the Minimum.

For successful application in practice of Liebig's concept, two auxiliary principles must be added to it: the first is restrictive ("Liebig's law is strictly applicable only in a stationary state, i.e. when the inflow and outflow of energy and matter are balanced"); the second is the principle of interaction of factors, which states that "a high concentration or availability of one substance or the action of another (not minimal) factor can change the rate of consumption of a nutrient contained in a minimum amount."

For an environmental engineer, the concept of limiting factors is valuable in that it provides a starting point in the study of complex situations in the "man - technology - nature" system. The relationships between the elements of such a system can be quite complex. In the process of solving problems of new equipment and technology, a specialist can highlight probable weaknesses and focus, at least at the beginning, on those characteristics of the environment that may turn out to be critical or limiting.

Liebig's law of the minimum in ecology (with examples)

In this article, we will briefly understand what Liebig's law of the minimum is, one of the fundamental laws in ecology. Another name for this law is the law of the limiting (limiting) factor. Also at the end of the article are some illustrative examples illustrating the law of the minimum.

Liebig's law of the minimum. A bit of history

The law of the minimum was formulated by the German chemist Justus von Liebig. in 1840.

The scientist was mainly engaged in the study of the conditions for the survival of plants in agriculture. He tried to understand at what point it is necessary to apply certain chemical additions to improve the survival of plants.

As a result of his research, von Liebig formulated a law that later turned out to be true not only for agriculture, but for all ecological systems and living organisms.

The law of the limiting (limiting) factor.

The essence of Liebig's law of the minimum

There are different formulations of this law. But the essence of the law of the minimum (or the law of the limiting factor) can be formulated as follows:

• The life of an organism depends on many factors. But, the most significant at any given time is the factor that is most vulnerable.

• In other words, if any of the factors in the body significantly deviates from the norm, then this factor is the most significant, the most critical for the survival of the organism at a given moment in time.

It is important to understand that for the same organism at different times, such critically important (or otherwise limiting) factors can be completely different factors.

The same reasoning applies to entire ecosystems. At this point in time, for example, lack of food can become a limiting factor. At another point in time - the amount of food will be normal, but the limiting factor will be the ambient temperature (too high or too low).

Summarizing the above, we can formulate the law as follows.

Liebig's law of the minimum is:

For the survival of an organism (or eco-system), the most significant is the environmental factor,

which is the most removed (deviates) from its optimal value.

Liebig barrel

Before moving on to examples, it is worth considering the drawing of the so-called Liebig barrel.

In this half-broken barrel - board height is the limiting factor. Obviously, the water will overflow over the smallest plank in the barrel. In this case, the height of the remaining boards will no longer be important to us - it will still be impossible to fill the barrel.

The smallest board is the very factor that deviated the most from the normal value.

According to Liebig's law of the minimum, the repair of the barrel must be started from this board.

Liebig's law of the minimum. Examples

There is a proverb: “Where it is thin, there it breaks” - by and large, it conveys the main essence of Liebig's law. But, let's give a few examples from completely different areas.

An example from agriculture

There are soils where there is not enough phosphorus - so you need to feed fertilizers with phosphorus. But, at other times, fertilizers with calcium are needed. And so on

An example from the wild

In winter, the limiting factor for a hare is food. In summer - you need to escape from the wolf, although there is plenty of food.

Sports example of the law of the minimum

In football: if the left back of the team is the weakest, then through his left flank the team is most likely to concede a goal.

Thus, Liebig's law of the minimum is a universal ecological and life law.

Additional Information:

• Commoner's Laws of Ecology - Read about Commoner's four basic laws of ecology.

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1. The law of the minimum Yu. Liebig.

In 1840, the German chemist Justus Liebig, growing plants on synthetic media, discovered that a certain number and quantity of chemical elements and compounds are necessary for normal plant growth. Some of them should be in the environment in very large quantities, others in small quantities, and still others in general in the form of traces. And, what is especially important: some elements cannot be replaced by others. A medium containing all elements in abundance, except for one, ensures the growth of the plant only until the moment when the amount of the latter is exhausted. Growth is thus limited by the shortage of a single element, the quantity of which was below the required minimum. This law, formulated by J. Liebig in relation to the role of chemical edaphic factors in plant life and called by him the law of the minimum, has, as it turned out later, a universal ecological character and plays an important role in ecology.

The Law of the Minimum: If all environmental conditions turn out to be favorable for the organism in question, with the exception of one that is insufficiently manifested (the value of which approaches the ecological minimum), then in this case this last condition, called the limiting factor, becomes decisive for the life or death of the organism in question, and therefore, its presence or absence in a given ecosystem”.

2. Shelford's law of tolerance.

In 1913, the American ecologist W. Shelford generalized Liebig's law of the minimum, discovering that in addition to the lower limit of intensity, there is also an upper limit of the intensity of environmental factors, which determines the upper limit of the range of intensities corresponding to the conditions of normal life of organisms. In this formulation, the law, called the ecological law of tolerance, began to have a more general universal character.

The law of tolerance (lat. tolerance- patience): "Each organism is characterized by an ecological minimum and an ecological maximum of the intensity of each environmental factor, within which life activity is possible."

The range of the environmental factor between the minimum and maximum is called the tolerance range or area.

Despite the wide variety of environmental factors, a number of general patterns can be identified in the nature of their impact and in the responses of living organisms.

The quantitative range of the factor that is most favorable for life is called ecological optimum (lat. optimus -

The values ​​of the factor lying in the zone of oppression are called ecological pessimism (lat. pessimum- worst).

The minimum and maximum values ​​of the factor at which death occurs are called respectively ecological minimum and ecological maximum .

Graphically, this is illustrated in fig.3-1. The curve in Figure 3-1 is generally not symmetrical.

For example, according to such a factor as temperature, the ecological maximum corresponds to the temperatures at which enzymes and proteins are destroyed (+50 ¸ +60 °С). However, individual organisms can exist at higher temperatures. So, in the hot springs of Komchatka and America, algae were found at t > +80 °C. The lower temperature limit at which life is possible is about -70 °C, although shrubs in Yakutia do not freeze even at this temperature. In suspended animation (gr. anabiosis- survival), i.e. in an inactive state, some organisms persist at absolute zero (-273 °C).

Rice. 3-1. Dependence of vital activity on intensity

We can formulate a number of provisions that complement the law of tolerance:

1. Organisms can have a wide range of tolerance for one environmental factor and a narrow range for another.

2. Organisms with a wide range of tolerance for most factors are usually the most widely distributed.

3. If the conditions for one ecological factor are not optimal for a given species, then the range of tolerance for other ecological factors may also narrow. For example, when the nitrogen content in the soil is close to the minimum, the drought resistance of cereals decreases.

4. During the breeding season, the range of tolerance tends to narrow.

Organisms with a narrow range of tolerance, or highly adapted species that can exist only with small deviations of the factor from the optimal value, are called stenobiont, or stenoeks (gr. stenos- narrow, cramped).

Organisms with a wide range of tolerance, or widely adapted species that can withstand a large amplitude of fluctuations in the environmental factor, are called eurybiont, or euryek (gr. euros- wide).

The property of organisms to adapt to existence in a particular range of environmental factors is called ecological plasticity .

Close to ecological plasticity is the concept ecological valency , which is defined as the ability of an organism to populate a variety of environments.

Thus, stenobionts are ecologically non-plastic; not hardy, have a low ecological valency; eurybionts, on the contrary, are ecologically plastic; more hardy, and have a high ecological valency.

To indicate the relationship of organisms to a particular factor, prefixes are added to its name: wall- and evry-. So, with respect to temperature, there are stenothermic (dwarf birch, banana tree) and eurythermal (temperate plants) species; in relation to salinity - stenohaline (carp, flounder) and euryhaline (stickleback); in relation to the world stenophonic (spruce) and euryfont (rose hip), etc.

Steno- and eurybiontness is manifested, as a rule, in relation to one or a few factors. Eurybionts are usually widespread. Many protozoan eurybionts (bacteria, fungi, algae) are cosmopolitans. Stenobionts, on the contrary, have a limited distribution area. Ecological plasticity and ecological valency of organisms often change during the transition from one stage of development to another; juveniles, as a rule, are more vulnerable and more demanding on environmental conditions than adults.

At the same time, organisms are not slaves to the physical conditions of the environment; they adapt themselves and change the environmental conditions in such a way as to weaken the influence of the limiting factor. Such compensation of limiting factors is especially effective at the community level, but it is also possible at the population level.

Species with a wide geographical distribution almost always form populations adapted to local conditions, called ecotypes . Their optima and tolerance limits correspond to local conditions. The appearance of ecotypes is sometimes accompanied by the genetic fixation of acquired properties and traits, i.e. to the emergence of races.

Organisms living for a long time in relatively stable conditions lose their ecological plasticity, and those that were subject to significant fluctuations of the factor become more tolerant to it, i.e. increase ecological plasticity. In animals, compensation of limiting factors is possible due to adaptive behavior - they avoid extreme values ​​of limiting factors.

When approaching extreme conditions, the energy price of adaptation increases. If superheated water is dumped into a river, then fish and other organisms spend almost all their energy to overcome this stress. They do not have enough energy to obtain food, protection from predators, reproduction, which leads to extinction.

So, organisms in nature depend on:

Liebig's law of the minimum

A living organism in natural conditions is simultaneously exposed to the influence of not one, but many environmental factors. Moreover, any factor is required by the body in certain quantities / doses. Liebig established that the development of a plant or its condition does not depend on those chemical elements that are present in the soil in sufficient quantities, but on those that are not enough. If a

of any, at least one of the nutrients in the soil is less than required by these plants, then it will develop abnormally, slowly, or have pathological deviations.

J. LIBICH's law of minimum- the concept that the existence and endurance of an organism is determined by the weakest link in the chain of its ecological needs.
According to the law of the minimum, the vital possibilities of organisms are limited by those environmental factors, the quantity and quality of which are close to the necessary organism or ecosystem.

Liebig's law:

The substance present in the minimum controls the yield, determines its size and stability over time. At the beginning of the 20th century, an American scientist Shelford showed that a thing or any other factor, which is present not only in a minimum, but also in excess compared to the level required by the body, can lead to undesirable consequences for the body. Example: if you place a plant/animal in an experimental chamber and measure the air temperature in it, then the state of the organism will change.

At the same time, some best, optimal level of this factor for the organism is revealed, at which the activity (physiological state) will be maximum. If different factors deviate from the optimal up/down, then the activity will decrease. Upon reaching a certain max/min value, the factor will become incompatible with life processes, changes will occur in the body, leading to death. Similar results can be obtained in experiments with changes in humidity, the content of various salts in water, acidity, the concentration of various substances, etc.

The wider the amplitude of the fluctuation of the factor at which the organism can reduce viability, the higher its stability ( tolerance) to one factor or another. From all of the above it follows:

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Cao this rule is one Any heterogeneous system consists of separate homogeneous, physically or chemically different, mechanically separable parts, called phases. For example, a saturated solution of sodium chloride […]

Lecture 2. Habitat, environmental factors and general patterns of their action

2.3. the law of the minimum, the law of tolerance

The existence of each species is limited by that of the factors that most deviates from the optimum. "The Law of the Limiting Factor» was first formulated by the German agricultural chemist, one of the founders of agricultural chemistry, Justus Liebig in 1840. J. Liebig studied the influence of various factors on plant growth and found that the grain yield is often limited not by those nutrients that are required in large quantities, such as carbon dioxide and water, but by those that are required in small quantities (for example, boron) , but which are few in the soil. J. Liebig put forward the principle: "The crop is controlled by the substance that is at a minimum." This principle is widely known as J. Liebig's law of the minimum. According to this law, the relative effect of an individual environmental factor is the stronger, the more it is in comparison with other factors at a minimum (Figure 2.6). J. Liebig's law shows one of the aspects of the dependence of organisms on the environment, it is strictly applicable in a stationary state of the system. If the environmental conditions change, then this or that process will also change, and will depend on other factors.

Figure 2.6 - Model illustrating Liebig's law ("Liebig's barrel")

Studying the various limiting effects of environmental factors (such as light, heat, water), the American zoologist Victor Ernest Shelford (1877–1968) came to the conclusion that not only a deficiency, but also an excess of factors can be a limiting factor. In ecology, such a situation has entered as W. Shelford's law of tolerance formulated by him in 1913. It states: “The limiting factor limiting the development of an organism can be both a minimum and a maximum of environmental impact.” A limiting factor is understood as a factor, the level of which in qualitative and quantitative terms (lack or excess) is close to the endurance limits of a given organism (Figure 2.7).

Figure 2.7 - The effect of temperature on the growth rate of a plant

Endurance limits are the minimum and maximum values ​​of the factor at which life is possible. The limits beyond which the death of organisms occurs are the lower and upper limits of endurance. Numerous examples of limiting factors show that this phenomenon is of general ecological importance. One example of the action of a limiting factor in nature is the suppression of herbaceous plants, deciduous tree species under the canopy of spruce, where the possibilities of development are limited by a lack of light. The ability of organisms to endure deviations of environmental factors from the optimal values ​​of their intensity is called tolerance (from Latin - patience). Organisms can have a wide range of tolerance (endurance) for one factor and a narrow range for another. If the conditions for one of the environmental factors are not optimal for the species, then the range of tolerance to other environmental factors may narrow. For example, with a limiting nitrogen content, the drought resistance of cereals decreases; Low nitrogen levels require more water to prevent plant wilt than high nitrogen levels. Many environmental factors often become limiting during the breeding season, which is usually critical for the survival of organisms. The tolerance limits for breeding individuals are usually narrower than for non-breeding adult plants or animals. They are also already for eggs, embryos, larvae, seedlings.

To express the degree of endurance, in ecology there are a number of terms in which prefixes are used wall-(narrow) and evry- (wide). So, there are stenothermic - eurythermal (in relation to temperature), stenophage - euryphage (in relation to food), stenobatic - eurybate (in relation to pressure) organisms.

Species that withstand significant deviations from the optimal values ​​of various factors, have a wide range of endurance and live in various, sometimes dramatically different environmental conditions, are called eurybiont species. Such species are widespread. For example, the fox belongs to eurybiont organisms, as it lives from the forest-tundra to the steppe, eating both animal and plant foods. But there are stenobiont organisms, narrowly adapted, not tolerating sharp fluctuations in temperature, humidity, etc. The hippopotamus and buffalo are animals only in regions of high humidity and temperature. These are almost all plants of tropical rainforests. Charr eggs develop at a temperature of 0–12°C with an optimum of about 4°C, and frog eggs develop at a temperature of 0–30°C with an optimum of about 22°C. So, in the first case, we can talk about stenothermy, and in the second case - about eurythermy. As you can see, for each organism and for the species as a whole, there is an optimum of conditions. It is not the same not only for different species under different conditions, but also for individual stages of development of one organism. For each species, the degree of endurance is also characteristic, for example, plants and animals of the temperate zone can exist in a fairly wide temperature range, while species of a tropical climate cannot withstand significant fluctuations in it. The ability of species to adapt to a particular range of environmental factors is denoted by the concept of ecological plasticity (ecological valency) of a species. The wider the range of fluctuations of the ecological factor within which a given species can exist, the greater its ecological plasticity, the wider the range of its tolerance (endurance). Ecologically non-plastic, that is, low-hardy species, are stenobiont, more hardy - eurybiont. Stenobiontness and eurybiontness characterize various types of adaptation of organisms for survival. Species that have developed for a long time under relatively stable conditions lose their ecological plasticity and develop stenobiont traits, while species that have existed with significant fluctuations in environmental factors acquire increased ecological plasticity and become eurybiont, that is, species with a wide range of tolerance (Figure 2.8).

Figure 2.8 - Ecological plasticity of species

Since all environmental factors are interconnected and among them there are no absolutely indifferent ones for any organism, each population and species as a whole react to these factors, but perceive them differently. Such selectivity also determines the selective attitude of organisms to the settlement of a particular territory. Different types of organisms have different requirements for soil conditions, temperature, humidity, light, etc. Therefore, different plants grow on different soils in different climatic zones. In turn, different conditions for animals are formed in plant associations.

Historically adapting to abiotic environmental factors and entering into certain biotic relationships with each other, plants, animals, fungi, microorganisms are distributed over various environments and form diverse ecosystems (biogeocenoses), eventually uniting into the Earth's biosphere.

C) Liebig's law, or "the law of the minimum", or the law of the limiting factor

There is no place in nature where one factor acts on the body. All factors act simultaneously and the totality of these actions is called a constellation. The values ​​of the factors are not always equivalent. They can all be insufficient, and then there is a general oppression of the biota (weak development of vegetation cover, a decrease in productivity, a change in the fractional structure of biomass, a change in other indicators of ecosystems), but more often some of them are in abundance, even at an optimum, while others are in short supply. At the same time, the constellation is not a simple sum of the influence of factors, since the degree of influence of some factors on organisms and populations depends on the degree of influence of other factors.

EXAMPLE. With optimal heat supply, the tolerance of plants and animals to a lack of moisture and nutrition increases, and a lack of heat is accompanied by a decrease in the need for moisture and an increased need for nutrients. This is also observed in plants and animals. In plants, with a lack of heat and waterlogging of the soil, nutrients become physiologically inaccessible, and increased soil fertility is required to ensure tolerance. Also in animals - to strengthen the protective functions of the body in the cold, you need to eat well. So, always before lying in the den, the bear accumulates subcutaneous fat. Gas exchange reactions in fish are not the same in water of different salinity. In beetles of the genus Blastophagus, the reaction to light depends on temperature. At a temperature of 25°C, they crawl into the light (positive phototropism), when it drops to 20°C or increases to 30°C, the reaction is neutral, and at values ​​below and above these limits, they hide.

However, the compensatory possibilities of the factors are limited. No factor can be completely replaced by another, and if the value of at least one of the factors goes beyond the upper or lower limits of the biota component's endurance, the existence of the latter becomes impossible, no matter how favorable the other factors are.

EXAMPLE. The normal survival of sika deer in Primorye takes place only in oak forests on the southern slopes, because. here the thickness of the snow is insignificant and provides the deer with a sufficient food base for the winter period. The limiting factor for deer is deep snow. The lack of heat limits the spread to the north of most species and formations of the Manchurian flora: pine forests from densely flowered pine, whole-leaved fir and its formations are common only in Southern Primorye. And in the permafrost zone, larch dominates everywhere. For Siberian dwarf pine and Kamchatka alder, the decisive propagation factors are high air humidity and overwintering conditions. They tolerate frosty winters well only if there is a powerful snow cover that protects the shoots from drying out and frostbite by the winter monsoons of the Far East. These species form thickets only in the coastal areas of the Sea of ​​Okhotsk and the Bering Sea, and in the continental regions - in the subalpine belt at an altitude of at least 1000 m / a.s.l. In the early stages of development, conifers may be limited by too much light. All of them, even the grave pine, require shading in the first years of life.

In the middle of the 19th century (1846), the German agricultural chemist Liebig deduced the "law of the minimum". In an experiment with mineral fertilizers, he found that the greatest influence on the endurance of plants is exerted by those factors that are at a minimum in a given habitat. He wrote in 1955: "Elements wholly absent or not in the right amount prevent other nutrient compounds from producing their effect or reduce their nutritional effect." This is true not only for batteries, but also for other vital factors. Liebig's law is applicable only under conditions of a stationary state of the ecosystem, i.e. when the influx of matter and energy into the system is balanced by their outflow.

A factor whose level is close to the endurance limits of a particular organism, species, and other biota components is called limiting. And it is to this factor that the body adapts (produces adaptations) in the first place. The law of limiting, or limiting, factors extends not only to the situation when these factors are at the “minimum”, but also at the “maximum”, that is, they go beyond the upper limit of the endurance of the organism (ecosystem).

In pessimistic conditions, there are several limiting factors, and their overall overwhelming effect may be higher than the total inhibitory effect of individual factors.

EXAMPLE with southern slopes - insolation increases the dryness of the environment, prevents an increase in soil fertility.

Often the limiting factor is at one of the stages of development of the species. As is known, juveniles are the most vulnerable, and for them there may be limiting factors. several. In different geographical areas, the limiting factors are different: in the Far North it is often warm, in the southern regions it is moisture. Different species react differently to the same factor. According to the reaction of their adult individuals to one or another factor, it is possible to build an ecological series (in descending or increasing order of the factor).

People please help me on ecology (details inside)

The law of the limiting (limiting) factor or Liebig's law of the minimum is one of the fundamental laws in ecology, which states that the most significant factor for an organism is the one that most deviates from its optimal value. Therefore, during the forecasting of environmental conditions or the performance of examinations, it is very important to determine the weak link in the life of organisms.
Liebig barrel

The survival of the organism depends on this, minimally (or maximally) presented at a given particular moment, the ecological factor. In other periods of time, other factors may be limiting. In the course of their lives, individuals of species meet with a variety of restrictions on their vital activity. So, the factor limiting the distribution of deer is the depth of the snow cover; butterflies of the winter scoop (a pest of vegetables and grain crops) - winter temperature, etc.

This law is taken into account in the practice of agriculture. The German chemist Justus Liebig found that the productivity of cultivated plants primarily depends on the nutrient (mineral element) that is least represented in the soil. For example, if phosphorus in the soil is only 20% of the required norm, and calcium is 50% of the norm, then the limiting factor will be a lack of phosphorus; First of all, it is necessary to introduce phosphorus-containing fertilizers into the soil.

A figurative representation of this law is named after the scientist - the so-called Liebig's barrel. The essence of the model is that when filling the barrel, water begins to overflow through the smallest board in the barrel and the length of the remaining boards no longer matters.

Liebig's law of the minimum in ecology (with examples)

In this article, we will briefly understand what Liebig's law of the minimum is, one of the fundamental laws in ecology. Another name for this law is the law of the limiting (limiting) factor. Also at the end of the article are some illustrative examples illustrating the law of the minimum.

Liebig's law of the minimum. A bit of history

The law of the minimum was formulated by the German chemist Justus von Liebig. in 1840.

The scientist was mainly engaged in the study of the conditions for the survival of plants in agriculture. He tried to understand at what point it is necessary to apply certain chemical additions to improve the survival of plants.

As a result of his research, von Liebig formulated a law that later turned out to be true not only for agriculture, but for all ecological systems and living organisms.

The law of the limiting (limiting) factor.

The essence of Liebig's law of the minimum

There are different formulations of this law. But the essence of the law of the minimum (or the law of the limiting factor) can be formulated as follows:

• The life of an organism depends on many factors. But, the most significant at any given time is the factor that is most vulnerable.
• In other words, if any of the factors in the body significantly deviates from the norm, then this factor is the most significant, the most critical for the survival of the organism at a given moment in time.

It is important to understand that for the same organism at different times, such critically important (or otherwise limiting) factors can be completely different factors.

The same reasoning applies to entire ecosystems. At this point in time, for example, lack of food can become a limiting factor. At another point in time - the amount of food will be normal, but the limiting factor will be the ambient temperature (too high or too low).

Summarizing the above, we can formulate the law as follows.

Liebig's law of the minimum is:

For the survival of an organism (or eco-system), the most significant is the environmental factor,

which is the most removed (deviates) from its optimal value.

Liebig barrel

Before moving on to examples, it is worth considering the drawing of the so-called Liebig barrel.



In this half-broken barrel - board height is the limiting factor. Obviously, the water will overflow over the smallest plank in the barrel. In this case, the height of the remaining boards will no longer be important to us - it will still be impossible to fill the barrel.

The smallest board is the very factor that deviated the most from the normal value.

According to Liebig's law of the minimum, the repair of the barrel must be started from this board.

Liebig's law of the minimum. Examples

There is a proverb: “Where it is thin, there it breaks” - by and large, it conveys the main essence of Liebig's law. But, let's give a few examples from completely different areas.

An example from agriculture

There are soils where there is not enough phosphorus - so you need to feed fertilizers with phosphorus. But, at other times, fertilizers with calcium are needed. And so on

An example from the wild

In winter, the limiting factor for a hare is food. In summer - you need to escape from the wolf, although there is plenty of food.

Sports example of the law of the minimum

In football: if the left back of the team is the weakest, then through his left flank the team is most likely to concede a goal.

Thus, Liebig's law of the minimum is a universal ecological and life law.

Additional Information:

• Commoner's Laws of Ecology - Read about Commoner's four basic laws of ecology.

Where to hand over for recycling waste, equipment and other things in your city

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Law of the limiting factor

The law of the limiting (limiting) factor or Liebig's law of the minimum- one of the fundamental laws in ecology, which states that the most significant factor for the body is the one that most of all deviates from its optimal value. Therefore, during the forecasting of environmental conditions or the performance of examinations, it is very important to determine the weak link in the life of organisms.

The survival of the organism depends on this, minimally (or maximally) presented at a given particular moment, the ecological factor. In other periods of time, other factors may be limiting. In the course of their lives, individuals of species meet with a variety of restrictions on their vital activity. So, the factor limiting the distribution of deer is the depth of the snow cover; [ source not specified 2954 days] butterflies of the winter scoop (a pest of vegetable and grain crops) - winter temperature [ source not specified 2954 days] etc.

This law is taken into account in the practice of agriculture. The German chemist Justus Liebig found that the productivity of cultivated plants primarily depends on the nutrient (mineral element) that is least represented in the soil. For example, if phosphorus in the soil is only 20% of the required norm, and calcium is 50% of the norm, then the limiting factor will be a lack of phosphorus; First of all, it is necessary to introduce phosphorus-containing fertilizers into the soil.

A figurative representation of this law is named after the scientist - the so-called "Liebig's barrel". The essence of the model is that when filling the barrel, water begins to overflow through the smallest board in the barrel and the length of the remaining boards no longer matters.