Surely each of us noticed how plants of the same species develop well in the forest, but feel bad in open spaces. Or, for example, some species of mammals have large populations, while others are more limited under seemingly the same conditions. All living things on Earth in one way or another obey their own laws and rules. Ecology deals with their study. One of the fundamental statements is Liebig's law of the minimum (limiting factor).
Limiting environmental factor: what is it?
German chemist and founder of agricultural chemistry, Professor Justus von Liebig, made many discoveries. One of the most famous and recognized is the discovery of a fundamental law of ecology: the limiting factor. It was formulated in 1840 and later supplemented and generalized by Shelford. The law says that for any living organism, the most significant factor is the one that deviates to a greater extent from its optimal value. In other words, the existence of an animal or plant depends on the degree of expression (minimum or maximum) of a particular condition. Individuals encounter a variety of limiting factors throughout their lives.
Liebig's Barrel
The factor limiting the vital activity of organisms can be different. The formulated law is still actively used in agriculture. J. Liebig found that the productivity of plants depends primarily on the mineral (nutrient) substance, which is most poorly expressed in the soil. For example, if nitrogen in the soil is only 10% of the required norm, and phosphorus is 20%, then the factor limiting normal development is the lack of the first element. Therefore, nitrogen-containing fertilizers should be applied to the soil initially. The meaning of the law was set out as clearly and clearly as possible in the so-called “Liebig barrel” (pictured above). Its essence is that when the vessel is filled, water begins to overflow where the shortest board is, and the length of the rest does not really matter.
Water
This factor is the toughest and most significant compared to the others. Water is the basis of life, as it plays an important role in the life of an individual cell and the whole organism as a whole. Maintaining its quantity at the proper level is one of the main physiological functions of any plant oranimal. Water as a factor limiting life activity is due to the uneven distribution of moisture over the Earth's surface throughout the year. In the process of evolution, many organisms have adapted to economical use of moisture, experiencing a dry period in a state of hibernation or rest. This factor is most pronounced in deserts and semi-deserts, where there is very scarce and peculiar flora and fauna.
Light
Coming in the form of solar radiation, the light provides all life processes on the planet. For organisms, its wavelength, duration of exposure, and intensity of radiation are important. Depending on these indicators, the organism adapts to environmental conditions. As a factor limiting existence, it is especially pronounced at great sea depths. For example, plants at a depth of 200 m are no longer found. In conjunction with lighting, at least two more limiting factors “work” here: pressure and oxygen concentration. This can be contrasted with the tropical rainforests of South America, as the most favorable territory for life.
Ambient temperature
It's no secret that all physiological processes in the body depend on external and internal temperature. Moreover, most of the species are adapted to a rather narrow range (15-30 °C). The dependence is especially pronounced in organisms that are not able to independently maintain a constant body temperature, for example,reptiles (reptiles). In the process of evolution, many adaptations have been formed to overcome this limited factor. Thus, the evaporation of water in hot weather in order to avoid overheating in plants increases through the stomata, in animals - through the skin and respiratory system, as well as behavioral features (hiding in the shade, burrows, etc.).
Pollutants
The importance of the anthropogenic factor cannot be underestimated. The last few centuries for man were marked by rapid technical progress, the rapid development of industry. This led to the fact that harmful emissions into water bodies, soil and atmosphere increased several times. It is possible to understand what factor limits this or that species only after research. This state of affairs explains the fact that the species diversity of individual regions or areas has changed beyond recognition. Organisms change and adapt, one after the other.
All these are the main factors limiting life. In addition to them, there are many others, which are simply impossible to list. Each species and even individual is individual, therefore, the limiting factors will be very diverse. For example, for trout, the percentage of oxygen dissolved in water is important, for plants - the quantitative and qualitative composition of pollinating insects, etc.
All living organisms have certain limits of endurance for one or another limiting factor. Some are quite wide, others are narrow. Depending on thisindicator distinguish between eurybionts and stenobionts. The former are able to tolerate a large amplitude of fluctuations of various limiting factors. For example, the common fox, which lives everywhere from the steppes to the forest-tundra, wolves, etc. Stenobionts, on the other hand, are able to withstand very narrow fluctuations, and they include almost all rainforest plants.
