Surely each of us noticed how plants of the same species perfectly develop in the forest, but feel bad in open spaces. Or, for example, some species of mammals have a large population, while others are more limited under seemingly identical conditions. All life on Earth in one way or another obeys its own laws and rules. Ecology is engaged in their study. One of the fundamental statements is the law of the Liebig minimum (limiting factor).
Environmental limiting factor: what is it?
The 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 the fundamental law of ecology: a limiting factor. It was formulated in 1840, and later supplemented and summarized by Shelford. The law says that for any living organism the most significant factor is that which deviates to a greater degree from its optimal value. In other words, the existence of an animal or plant depends on the severity (minimum or maximum) of a particular condition. Individuals are found throughout their lives with a wide variety of limiting factors.
"Barrel Liebig"
The factor limiting the vital activity of organisms can be different. The formulated law is still actively used in agriculture. Y. Libikh found that plant productivity depends primarily on the mineral substance (nutrient), the most weakly 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 the normal development is the lack of the first element. Therefore, nitrogen-containing fertilizers should first be introduced into the soil. The meaning of the law was most clearly and clearly stated in the so-called “Liebig barrel” (pictured above). Its essence is that when the vessel is filled, water begins to overflow over the edge where the shortest board is, and the length of the rest no longer matters.
Water
This factor is the most stringent and significant compared to the rest. 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 or animal. Water as a limiting factor for life, due to the uneven distribution of moisture on the Earth's surface throughout the year. In the process of evolution, many organisms have adapted to the economical use of moisture, experiencing a dry period in a state of hibernation or dormancy. This factor is most pronounced in deserts and semi-deserts, where there is a very meager and peculiar flora and fauna.
Shine
The light coming in the form of solar radiation provides all life processes on the planet. Organisms are important in its wavelength, duration of exposure, radiation intensity. Depending on these indicators, the organism adapts to environmental conditions. As a limiting factor, it is especially pronounced at great depths of the sea. 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. Contrast this with the humid tropical forests of South America, as the most favorable territory for life.
Ambient temperature
It's no secret that all physiological processes that occur 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 devices have been formed that make it possible to overcome this limited factor. So, evaporation of water during hot weather in order to avoid overheating in plants is enhanced through the stomata, in animals through the skin and respiratory system, as well as behavioral characteristics (hiding in the shade, burrows, etc.).
Pollutants
The value of the anthropogenic factor cannot be underestimated. The last few centuries for man have been marked by rapid technological progress, the rapid development of industry. This has led to the fact that harmful emissions into water bodies, soil and the atmosphere have increased several times. It is possible to understand what factor limits a particular species only after research. This state of affairs is explained by the fact that the species diversity of individual regions or regions has changed beyond recognition. Organisms change and adapt, some replace the others.
All these are the main factors limiting life. In addition to them, there are many others that are simply impossible to list. Each species and even individual is individual, therefore, limiting factors will be the most 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. For some, they are wide enough, for others - narrow. Depending on this indicator, eurybionts and stenobionts are distinguished. The former are able to tolerate large amplitude oscillations of various limiting factors. For example, an ordinary fox that lives everywhere from the steppes to the forest-tundra, wolves, etc. Stenobionts, on the contrary, are able to withstand very narrow fluctuations; almost all plants of rainforests are among them.