Any properties or components of the external environment that influence organisms are called environmental factors. Light, heat, salt concentration in water or soil, wind, hail, enemies and pathogens - all these are environmental factors, the list of which can be very large.
Among them there are abiotic related to inanimate nature, and biotic related to the influence of organisms on each other.
Environmental factors are extremely diverse, and each species, experiencing their influence, responds to it differently. However, there are some general laws that govern the responses of organisms to any environmental factor.
The main one is law of optimum. It reflects how living organisms tolerate different strengths of environmental factors. The strength of each of them is constantly changing. We live in a world with variable conditions, and only in certain places on the planet the values of some factors are more or less constant (in the depths of caves, at the bottom of the oceans).
The law of optimum is expressed in the fact that any environmental factor has certain limits of positive influence on living organisms.
When deviating from these limits, the sign of the effect changes to the opposite. For example, animals and plants do not tolerate extreme heat and severe frost; Medium temperatures are optimal. Likewise, drought and constant heavy rain are equally unfavorable to the crop. The law of optimum indicates the extent of each factor for the viability of organisms. On the graph it is expressed by a symmetrical curve showing how the vital activity of the species changes with a gradual increase in the influence of the factor (Fig. 13).
Figure 13. Scheme of the action of environmental factors on living organisms. 1,2 - critical points
(to enlarge the image, click on the picture)
In the center under the curve - optimum zone. At optimal values of the factor, organisms actively grow, feed, and reproduce. The more the factor value deviates to the right or to the left, that is, in the direction of decreasing or increasing the force of action, the less favorable it is for organisms. The curve reflecting vital activity descends sharply on either side of the optimum. There are two pessimum zones. When the curve intersects the horizontal axis, there are two critical points. These are the values of the factor that organisms can no longer withstand, beyond which death occurs. The distance between critical points shows the degree of tolerance of organisms to changes in the factor. Conditions close to critical points are especially difficult for survival. Such conditions are called extreme.
If you draw optimum curves for a factor, such as temperature, for different species, they will not coincide. Often what is optimal for one species is pessimistic for another or even lies outside the critical points. Camels and jerboas could not live in the tundra, and reindeer and lemmings could not live in the hot southern deserts.
The ecological diversity of species is also manifested in the position of critical points: for some they are close together, for others they are widely spaced. This means that a number of species can live only in very stable conditions, with minor changes in environmental factors, while others can withstand wide fluctuations. For example, the impatiens plant withers if the air is not saturated with water vapor, and feather grass tolerates changes in humidity well and does not die even in drought.
Thus, the law of optimum shows us that for each type there is its own measure of the influence of each factor. Both a decrease and an increase in exposure beyond this measure leads to the death of organisms.
For understanding the relationship of species with the environment, it is no less important limiting factor law.
In nature, organisms are simultaneously influenced by a whole complex of environmental factors in different combinations and with different strengths. It is not easy to isolate the role of each of them. Which one means more than the others? What we know about the law of optimum allows us to understand that there are no entirely positive or negative, important or secondary factors, but everything depends on the strength of each influence.
The law of the limiting factor states that the most significant factor is the one that deviates the most from the optimal values for the body.
The survival of individuals in this particular period depends on it. At other periods of time, other factors may become limiting, and throughout life, organisms encounter a variety of restrictions on their life activity.
Agricultural practice constantly faces the laws of optimum and limiting factors. For example, the growth and development of wheat, and therefore the yield, are constantly limited by critical temperatures, a lack or excess of moisture, a lack of mineral fertilizers, and sometimes by such catastrophic influences as hail and storms. It takes a lot of effort and money to maintain optimal conditions for crops, and at the same time, first of all, compensate or mitigate the effect of limiting factors.
The habitats of different species are surprisingly varied. Some of them, for example, some small mites or insects, spend their entire lives inside the leaf of a plant, which is the whole world for them, others master vast and varied spaces, such as reindeer, whales in the ocean, migratory birds.
Depending on where representatives of different species live, they are affected by different sets of environmental factors. On our planet there are several basic living environments, very different in terms of living conditions: water, ground-air, soil. Habitats are also the organisms themselves in which others live.
Aquatic living environment. All aquatic inhabitants, despite differences in lifestyle, must be adapted to the main features of their environment. These features are determined, first of all, by the physical properties of water: its density, thermal conductivity, and ability to dissolve salts and gases.
Density water determines its significant buoyant force. This means that the weight of organisms in water is lightened and it becomes possible to lead a permanent life in the water column without sinking to the bottom. Many species, mostly small, incapable of fast active swimming, seem to float in the water, being suspended in it. The collection of such small aquatic inhabitants is called plankton. Plankton includes microscopic algae, small crustaceans, fish eggs and larvae, jellyfish and many other species. Planktonic organisms are carried by currents and are unable to resist them. The presence of plankton in water makes possible the filtration type of nutrition, i.e., straining, using various devices, small organisms and food particles suspended in water. It is developed in both swimming and sessile bottom animals, such as crinoids, mussels, oysters and others. A sedentary lifestyle would be impossible for aquatic inhabitants if there were no plankton, and this, in turn, is possible only in an environment with sufficient density.
The density of water makes active movement in it difficult, so fast-swimming animals, such as fish, dolphins, squids, must have strong muscles and a streamlined body shape. Due to the high density of water, pressure increases greatly with depth. Deep-sea inhabitants are able to withstand pressure that is thousands of times higher than on the land surface.
Light penetrates water only to a shallow depth, so plant organisms can only exist in the upper horizons of the water column. Even in the cleanest seas, photosynthesis is possible only to depths of 100-200 m. At greater depths there are no plants, and deep-sea animals live in complete darkness.
Temperature in water bodies it is softer than on land. Due to the high heat capacity of water, temperature fluctuations in it are smoothed out, and aquatic inhabitants do not face the need to adapt to severe frosts or forty-degree heat. Only in hot springs can the water temperature approach the boiling point.
One of the difficulties in the life of aquatic inhabitants is limited amount of oxygen. Its solubility is not very high and, moreover, decreases greatly when the water is polluted or heated. Therefore, in reservoirs there are sometimes freezes- mass death of inhabitants due to lack of oxygen, which occurs for various reasons.
Salt composition The environment is also very important for aquatic organisms. Marine species cannot live in fresh waters, and freshwater species cannot live in seas due to disruption of cell function.
Ground-air environment of life. This environment has a different set of features. It is generally more complex and varied than aquatic. It has a lot of oxygen, a lot of light, sharper temperature changes in time and space, significantly weaker pressure drops and moisture deficiency often occurs. Although many species can fly, and small insects, spiders, microorganisms, seeds and plant spores are carried by air currents, feeding and reproduction of organisms occurs on the surface of the ground or plants. In such a low-density environment as air, organisms need support. Therefore, terrestrial plants have developed mechanical tissues, and terrestrial animals have a more pronounced internal or external skeleton than aquatic animals. The low density of air makes it easier to move around in it.
M. S. Gilyarov (1912-1985), a prominent zoologist, ecologist, academician, founder of extensive research into the world of soil animals, passive flight was mastered by about two-thirds of land inhabitants. Most of them are insects and birds.
Air is a poor conductor of heat. This makes it easier to conserve heat generated inside organisms and maintain a constant temperature in warm-blooded animals. The very development of warm-bloodedness became possible in a terrestrial environment. The ancestors of modern aquatic mammals - whales, dolphins, walruses, seals - once lived on land.
Land dwellers have a wide variety of adaptations related to providing themselves with water, especially in dry conditions. In plants, this is a powerful root system, a waterproof layer on the surface of leaves and stems, and the ability to regulate water evaporation through stomata. In animals, these are also different structural features of the body and integument, but, in addition, appropriate behavior also contributes to maintaining water balance. They may, for example, migrate to watering holes or actively avoid particularly dry conditions. Some animals can live their entire lives on dry food, such as jerboas or the well-known clothes moth. In this case, the water needed by the body arises due to the oxidation of food components.
Many other environmental factors also play an important role in the life of terrestrial organisms, such as air composition, winds, and the topography of the earth's surface. Weather and climate are especially important. The inhabitants of the land-air environment must be adapted to the climate of the part of the Earth where they live and tolerate variability in weather conditions.
Soil as a living environment. Soil is a thin layer of land surface, processed by the activity of living beings. Solid particles are permeated in the soil with pores and cavities, filled partly with water and partly with air, so small aquatic organisms can also inhabit the soil. The volume of small cavities in the soil is a very important characteristic of it. In loose soils it can be up to 70%, and in dense soils it can be about 20%. In these pores and cavities or on the surface of solid particles live a huge variety of microscopic creatures: bacteria, fungi, protozoa, roundworms, arthropods. Larger animals make passages in the soil themselves. The entire soil is penetrated by plant roots. Soil depth is determined by the depth of root penetration and the activity of burrowing animals. It is no more than 1.5-2 m.
The air in soil cavities is always saturated with water vapor, and its composition is enriched in carbon dioxide and depleted in oxygen. In this way, the living conditions in the soil resemble the aquatic environment. On the other hand, the ratio of water and air in soils is constantly changing depending on weather conditions. Temperature fluctuations are very sharp at the surface, but quickly smooth out with depth.
The main feature of the soil environment is the constant supply of organic matter, mainly due to dying plant roots and falling leaves. It is a valuable source of energy for bacteria, fungi and many animals, so soil is the most vibrant environment. Her hidden world is very rich and diverse.
By the appearance of different species of animals and plants, one can understand not only what environment they live in, but also what kind of life they lead in it.
If we have in front of us a four-legged animal with highly developed muscles of the thighs on the hind legs and much weaker muscles on the front legs, which are also shortened, with a relatively short neck and a long tail, then we can confidently say that this is a ground jumper, capable for fast and maneuverable movements, inhabitant of open spaces. The famous Australian kangaroos, desert Asian jerboas, African jumpers, and many other jumping mammals - representatives of various orders living on different continents - look like this. They live in steppes, prairies, and savannas - where fast movement on the ground is the main means of escape from predators. The long tail serves as a balancer during fast turns, otherwise the animals would lose their balance.
The hips are strongly developed on the hind limbs and in jumping insects - locusts, grasshoppers, fleas, psyllid beetles.
A compact body with a short tail and short limbs, of which the front ones are very powerful and look like a shovel or rake, blind eyes, a short neck and short, as if trimmed, fur tell us that this is an underground animal that digs holes and galleries. . This could be a forest mole, a steppe mole rat, an Australian marsupial mole, and many other mammals leading a similar lifestyle.
Burrowing insects - mole crickets are also distinguished by their compact, stocky body and powerful forelimbs, similar to a reduced bulldozer bucket. In appearance they resemble a small mole.
All flying species have developed wide planes - wings in birds, bats, insects, or straightening folds of skin on the sides of the body, like in gliding flying squirrels or lizards.
Organisms that disperse through passive flight, with air currents, are characterized by small sizes and very diverse shapes. However, they all have one thing in common - strong surface development compared to body weight. This is achieved in different ways: due to long hairs, bristles, various outgrowths of the body, its elongation or flattening, and lighter specific gravity. This is what small insects and flying fruits of plants look like.
External similarity that arises among representatives of different unrelated groups and species as a result of a similar lifestyle is called convergence.
It affects mainly those organs that directly interact with the external environment, and is much less pronounced in the structure of internal systems - digestive, excretory, nervous.
The shape of a plant determines the characteristics of its relationship with the external environment, for example, the way it tolerates the cold season. Trees and tall shrubs have the highest branches.
The form of a vine - with a weak trunk entwining other plants, can be found in both woody and herbaceous species. These include grapes, hops, meadow dodder, and tropical vines. Wrapping around the trunks and stems of upright species, liana-like plants bring their leaves and flowers to the light.
In similar climatic conditions on different continents, a similar appearance of vegetation arises, which consists of different, often completely unrelated species.
The external form, reflecting the way it interacts with the environment, is called the life form of the species. Different species may have similar life forms, if they lead a close lifestyle.
The life form is developed during the centuries-long evolution of species. Those species that develop with metamorphosis naturally change their life form during the life cycle. Compare, for example, a caterpillar and an adult butterfly or a frog and its tadpole. Some plants can take on different life forms depending on their growing conditions. For example, linden or bird cherry can be both an upright tree and a bush.
Communities of plants and animals are more stable and more complete if they include representatives of different life forms. This means that such a community makes fuller use of environmental resources and has more diverse internal connections.
The composition of life forms of organisms in communities serves as an indicator of the characteristics of their environment and the changes occurring in it.
Engineers who design aircraft carefully study the different life forms of flying insects. Models of machines with flapping flight have been created, based on the principle of movement in the air of Diptera and Hymenoptera. Modern technology has constructed walking machines, as well as robots with lever and hydraulic methods of movement, like animals of different life forms. Such vehicles are capable of moving on steep slopes and off-road.
Life on Earth developed under conditions of regular day and night and alternating seasons due to the rotation of the planet around its axis and around the Sun. The rhythm of the external environment creates periodicity, i.e., repeatability of conditions in the life of most species. Both critical periods, difficult for survival, and favorable ones are repeated regularly.
Adaptation to periodic changes in the external environment is expressed in living beings not only by a direct reaction to changing factors, but also in hereditarily fixed internal rhythms.
Circadian rhythms. Circadian rhythms adapt organisms to the cycle of day and night. In plants, intensive growth and flower blooming are timed to a certain time of day. Animals change their activity greatly throughout the day. Based on this feature, diurnal and nocturnal species are distinguished.
The daily rhythm of organisms is not only a reflection of changing external conditions. If you place a person, or animals, or plants in a constant, stable environment without a change of day and night, then the rhythm of life processes is maintained, close to the daily rhythm. The body seems to live according to its internal clock, counting down time.
The circadian rhythm can affect many processes in the body. In humans, about 100 physiological characteristics are subject to the daily cycle: heart rate, breathing rhythm, secretion of hormones, secretions of the digestive glands, blood pressure, body temperature and many others. Therefore, when a person is awake instead of sleeping, the body is still tuned to the night state and sleepless nights have a bad effect on health.
However, circadian rhythms do not appear in all species, but only in those in whose lives the change of day and night plays an important ecological role. The inhabitants of caves or deep waters, where there is no such change, live according to different rhythms. And even among land dwellers, not everyone exhibits daily periodicity.
In experiments under strictly constant conditions, Drosophila fruit flies maintain a daily rhythm for tens of generations. This periodicity is inherited in them, as in many other species. So profound are the adaptive reactions associated with the daily cycle of the external environment.
Disturbances in the body's circadian rhythm during night work, space flights, scuba diving, etc. represent a serious medical problem.
Annual rhythms. Annual rhythms adapt organisms to seasonal changes in conditions. In the life of species, periods of growth, reproduction, molting, migration, and deep dormancy naturally alternate and repeat in such a way that organisms meet the critical time of year in the most stable state. The most vulnerable process - reproduction and rearing of young animals - occurs during the most favorable season. This periodicity of changes in physiological state throughout the year is largely innate, that is, it manifests itself as an internal annual rhythm. If, for example, Australian ostriches or the wild dog dingo are placed in a zoo in the Northern Hemisphere, their breeding season will begin in the fall, when it is spring in Australia. The restructuring of internal annual rhythms occurs with great difficulty, over a number of generations.
Preparation for reproduction or overwintering is a long process that begins in organisms long before the onset of critical periods.
Sharp short-term changes in weather (summer frosts, winter thaws) usually do not disrupt the annual rhythms of plants and animals. The main environmental factor to which organisms respond in their annual cycles is not random changes in weather, but photoperiod- changes in the ratio of day and night.
The length of daylight hours naturally changes throughout the year, and it is these changes that serve as an accurate signal of the approach of spring, summer, autumn or winter.
The ability of organisms to respond to changes in day length is called photoperiodism.
If the day shortens, species begin to prepare for winter; if it lengthens, they begin to actively grow and reproduce. In this case, what is important for the life of organisms is not the change in the length of day and night itself, but its signal value, indicating impending profound changes in nature.
As you know, the length of the day greatly depends on geographic latitude. In the northern hemisphere, summer days are much shorter in the south than in the north. Therefore, southern and northern species react differently to the same amount of day change: southern species begin to reproduce with shorter days than northern ones.
ENVIRONMENTAL FACTORS
Ivanova T.V., Kalinova G.S., Myagkova A.N. "General Biology". Moscow, "Enlightenment", 2000
- Topic 18. "Habitat. Environmental factors." Chapter 1; pp. 10-58
- Topic 19. "Populations. Types of relationships between organisms." chapter 2 §8-14; pp. 60-99; Chapter 5 § 30-33
- Topic 20. "Ecosystems." chapter 2 §15-22; pp. 106-137
- Topic 21. "Biosphere. Cycles of matter." Chapter 6 §34-42; pp. 217-290
We begin our acquaintance with ecology, perhaps, with one of the most developed and studied sections - autecology. Autecology focuses on the interaction of individuals or groups of individuals with the conditions of their environment. Therefore, the key concept of autecology is the environmental factor, that is, the environmental factor affecting the body.
No environmental measures are possible without studying the optimal effect of a particular factor on a given biological species. Indeed, how can one protect one species or another if one does not know what living conditions it prefers? Even the “protection” of a species such as Homo sapiens requires knowledge of sanitary and hygienic standards, which are nothing more than the optimum of various environmental factors as applied to humans.
The influence of the environment on the body is called an environmental factor. The exact scientific definition is:
ECOLOGICAL FACTOR - any environmental condition to which living things react with adaptive reactions.
An environmental factor is any element of the environment that has a direct or indirect effect on living organisms during at least one of the phases of their development.
By their nature, environmental factors are divided into at least three groups:
abiotic factors - the influence of inanimate nature;
biotic factors - the influence of living nature.
anthropogenic factors - influences caused by reasonable and unreasonable human activity ("anthropos" - man).
Man modifies living and inanimate nature, and in a certain sense takes on a geochemical role (for example, releasing carbon immured in the form of coal and oil for many millions of years and releasing it into the air as carbon dioxide). Therefore, anthropogenic factors in the scope and globality of their impact are approaching geological forces.
It is not uncommon for environmental factors to be subjected to a more detailed classification, when it is necessary to point out a specific group of factors. For example, there are climatic (climate-related) and edaphic (soil) environmental factors.
As a textbook example of the indirect action of environmental factors, the so-called bird markets, which are huge concentrations of birds, are cited. The high density of birds is explained by a whole chain of cause and effect relationships. Bird droppings enter the water, organic substances in the water are mineralized by bacteria, the increased concentration of mineral substances leads to an increase in the number of algae, and after them, zooplankton. Fish feed on lower crustaceans that are part of zooplankton, and birds that inhabit the bird colony feed on fish. The chain is closed. Bird droppings act as an environmental factor that indirectly increases the size of a bird colony.
How can we compare the effects of factors so different in nature? Despite the huge number of factors, from the very definition of an environmental factor as an element of the environment that influences the body, something in common follows. Namely: the effect of environmental factors is always expressed in changes in the life activity of organisms, and ultimately leads to a change in population size. This allows us to compare the effects of various environmental factors.
Needless to say, the effect of a factor on an individual is determined not by the nature of the factor, but by its dose. In light of the above, and simple life experience, it becomes obvious that it is the dose of the factor that determines the effect. Indeed, what is the “temperature” factor? This is quite an abstraction, but if you say that the temperature is -40 Celsius, there is no time for abstractions, you better wrap yourself up in everything warm! On the other hand, +50 degrees will not seem much better to us.
Thus, the factor affects the body with a certain dose, and among these doses one can distinguish minimum, maximum and optimal doses, as well as those values at which the life of an individual ceases (they are called lethal, or lethal).
The effect of different doses on the population as a whole is very clearly described graphically:
The ordinate axis shows the population size depending on the dose of a particular factor (abscissa axis). The optimal dose of the factor and the dose of the factor at which the vital activity of a given organism is inhibited are identified. On the graph this corresponds to 5 zones:
optimum zone
to the right and left of it are the pessimum zones (from the boundary of the optimum zone to max or min)
lethal zones (beyond max and min), in which the population size is 0.
The range of factor values, beyond which the normal functioning of individuals becomes impossible, is called the limits of endurance.
In the next lesson we will look at how organisms differ in relation to various environmental factors. In other words, in the next lesson we will talk about ecological groups of organisms, as well as about the Liebig barrel and how all this is connected with the determination of the maximum permissible concentration.
Glossary
ABIOTIC FACTOR - a condition or set of conditions of the inorganic world; ecological factor of inanimate nature.
ANTHROPOGENIC FACTOR - an environmental factor that owes its origin to human activity.
PLANKTON is a set of organisms that live in the water column and are unable to actively resist being carried by currents, that is, “floating” in the water.
BIRD MARKET - a colonial settlement of birds associated with the aquatic environment (guillemots, gulls).
Which environmental factors, out of all their diversity, does the researcher primarily pay attention to? It is not uncommon for a researcher to be faced with the task of identifying those environmental factors that inhibit the life activity of representatives of a given population and limit growth and development. For example, it is necessary to find out the reasons for the decline in yield or the reasons for the extinction of a natural population.
With all the diversity of environmental factors and the difficulties that arise when trying to assess their joint (complex) impact, it is important that the factors that make up the natural complex have unequal importance. Back in the 19th century, Liebig (1840), studying the influence of various microelements on plant growth, established: plant growth is limited by the element whose concentration is at a minimum. The deficient factor was called limiting. The so-called “Liebig barrel” helps to represent this situation figuratively.
Liebig barrel
Imagine a barrel with wooden slats on the sides of different heights, as shown in the figure. It’s clear, no matter what height the other slats are, you can only pour as much water into the barrel as the length of the shortest slats (in this case, 4 dies).
All that remains is to “replace” some terms: let the height of the poured water be some biological or ecological function (for example, productivity), and the height of the slats will indicate the degree of deviation of the dose of one or another factor from the optimum.
Currently, Liebig's law of the minimum is interpreted more broadly. A limiting factor can be a factor that is not only in short supply, but also in excess.
An environmental factor plays the role of a LIMITING FACTOR if this factor is below a critical level or exceeds the maximum tolerable level.
The limiting factor determines the distribution area of the species or (under less severe conditions) affects the general level of metabolism. For example, the phosphate content in seawater is a limiting factor that determines the development of plankton and the productivity of communities in general.
The concept of "limiting factor" applies not only to various elements, but also to all environmental factors. Often, competitive relations act as a limiting factor.
Each organism has limits of endurance in relation to various environmental factors. Depending on how wide or narrow these limits are, eurybiont and stenobiont organisms are distinguished. Eurybionts are able to tolerate a wide range of intensities of various environmental factors. Let's say the fox's habitat ranges from forest-tundra to steppes. Stenobionts, on the contrary, tolerate only very narrow fluctuations in the intensity of the environmental factor. For example, almost all plants of tropical rainforests are stenobionts.
It is not uncommon to indicate which factor is meant. Thus, we can talk about eurythermic (tolerating large temperature fluctuations) organisms (many insects) and stenothermic (for tropical forest plants, temperature fluctuations within +5... +8 degrees C can be destructive); eury/stenohaline (tolerating/not tolerating fluctuations in water salinity); evry/stenobate (living in wide/narrow depth limits of a reservoir) and so on.
The emergence of stenobiont species in the process of biological evolution can be considered as a form of specialization in which greater efficiency is achieved at the expense of adaptability.
Interaction of factors. MPC.
When environmental factors act independently, it is enough to use the concept of “limiting factor” to determine the joint impact of a complex of environmental factors on a given organism. However, in real conditions, environmental factors can enhance or weaken each other's effects. For example, frost in the Kirov region is more easily tolerated than in St. Petersburg, since the latter has higher humidity.
Taking into account the interaction of environmental factors is an important scientific problem. Three main types of interaction of factors can be distinguished:
additive - the interaction of factors is a simple algebraic sum of the effects of each factor when acting independently;
synergetic - the joint action of factors enhances the effect (that is, the effect when they act together is greater than the simple sum of the effects of each factor when acting independently);
antagonistic - the joint action of factors weakens the effect (that is, the effect of their joint action is less than the simple sum of the effects of each factor).
Why is it so important to know about the interaction of environmental factors? The theoretical justification for the value of maximum permissible concentrations (MAC) of pollutants or maximum permissible levels (MPL) of exposure to polluting agents (for example, noise, radiation) is based on the law of the limiting factor. The maximum permissible concentration is set experimentally at a level at which pathological changes do not yet occur in the body. This has its own difficulties (for example, most often it is necessary to extrapolate data obtained on animals to humans). However, we are not talking about them now.
It is not uncommon to hear environmental authorities happily report that the level of most pollutants in the city’s atmosphere is within the MPC. At the same time, the state sanitary and epidemiological authorities are reporting an increased level of respiratory diseases in children. The explanation could be like this. It is no secret that many atmospheric pollutants have a similar effect: they irritate the mucous membranes of the upper respiratory tract, cause respiratory diseases, etc. And the combined action of these pollutants gives an additive (or synergistic) effect.
Therefore, ideally, when developing MPC standards and when assessing the existing environmental situation, the interaction of factors should be taken into account. Unfortunately, this can be very difficult to do in practice: it is difficult to plan such an experiment, it is difficult to assess the interaction, plus tightening the MPC has negative economic effects.
Glossary
MICROELEMENTS - chemical elements needed by organisms in minute quantities, but determining the success of their development. M. in the form of microfertilizers is used to increase plant productivity.
LIMITING FACTOR - a factor that sets the framework (determining) for the course of some process or for the existence of an organism (species, community).
AREAL - the area of distribution of any systematic group of organisms (species, genus, family) or a certain type of community of organisms (for example, the area of lichen pine forests).
METABOLISM - (in relation to the body) the sequential consumption, transformation, use, accumulation and loss of substances and energy in living organisms. Life is possible only thanks to metabolism.
EURYBIONT - an organism living in various environmental conditions
STENOBIONT is an organism that requires strictly defined conditions of existence.
XENOBIOTIC - a chemical substance foreign to the body, naturally not included in the biotic cycle. As a rule, a xenobiotic is of anthropogenic origin.
Ecosystem
URBAN AND INDUSTRIAL ECOSYSTEMS
General characteristics of urban ecosystems.
Urban ecosystems are heterotrophic; the share of solar energy fixed by urban plants or solar panels located on the roofs of houses is insignificant. The main sources of energy for city enterprises, heating and lighting of city residents' apartments are located outside the city. These are oil, gas, coal deposits, hydro and nuclear power plants.
The city consumes a huge amount of water, only a small part of which is used by humans for direct consumption. The bulk of water is spent on production processes and household needs. Personal water consumption in cities ranges from 150 to 500 liters per day, and taking into account industry, up to 1000 liters per day per citizen. The water used by cities returns to nature in a polluted state - it is saturated with heavy metals, residues of petroleum products, complex organic substances like phenol, etc. It may contain pathogenic microorganisms. The city emits toxic gases and dust into the atmosphere, and concentrates toxic waste in landfills, which enter aquatic ecosystems with spring water flows. Plants as part of urban ecosystems grow in parks, gardens, and lawns; their main purpose is to regulate the gas composition of the atmosphere. They release oxygen, absorb carbon dioxide and cleanse the atmosphere of harmful gases and dust that enter it during the operation of industrial enterprises and transport. Plants also have great aesthetic and decorative value.
Animals in the city are represented not only by species common in natural ecosystems (birds live in the parks: redstart, nightingale, wagtail; mammals: voles, squirrels and representatives of other groups of animals), but also by a special group of urban animals - human companions. It consists of birds (sparrows, starlings, pigeons), rodents (rats and mice), and insects (cockroaches, bedbugs, moths). Many animals associated with humans feed on garbage in garbage dumps (jackdaws, sparrows). These are city nurses. The decomposition of organic waste is accelerated by fly larvae and other animals and microorganisms.
The main feature of the ecosystems of modern cities is that their ecological balance is disturbed. Man has to take on all the processes of regulating the flow of matter and energy. A person must regulate both the city’s consumption of energy and resources - raw materials for industry and food for people, and the amount of toxic waste entering the atmosphere, water and soil as a result of industrial and transport activities. Finally, it determines the size of these ecosystems, which in developed countries, and in recent years in Russia, are quickly “spreading” due to suburban cottage construction. Low-rise development areas reduce the area of forests and agricultural land, their “sprawling” requires the construction of new highways, which reduces the share of ecosystems capable of producing food and carrying out the oxygen cycle.
Industrial pollution.
In urban ecosystems, industrial pollution is the most dangerous for nature.
Chemical pollution of the atmosphere. This factor is one of the most dangerous to human life. Most common pollutants
Sulfur dioxide, nitrogen oxides, carbon monoxide, chlorine, etc. In some cases, toxic compounds can be formed from two or relatively several relatively harmless substances emitted into the atmosphere under the influence of sunlight. Environmentalists count about 2,000 air pollutants.
The main sources of pollution are thermal power plants. Boiler houses, oil refineries and motor vehicles also heavily pollute the atmosphere.
Chemical pollution of water bodies. Enterprises discharge petroleum products, nitrogen compounds, phenol and many other industrial wastes into water bodies. During oil production, water bodies are polluted with saline species; oil and petroleum products also spill during transportation. In Russia, the lakes of the North of Western Siberia suffer most from oil pollution. In recent years, the danger to aquatic ecosystems from municipal wastewater has increased. These effluents contain an increased concentration of detergents, which are difficult for microorganisms to decompose.
As long as the amount of pollutants emitted into the atmosphere or discharged into rivers is small, ecosystems themselves are able to cope with them. With moderate pollution, the water in the river becomes almost clean after 3-10 km from the source of pollution. If there are too many pollutants, ecosystems cannot cope with them and irreversible consequences begin.
Water becomes unfit for drinking and dangerous for humans. Contaminated water is also unsuitable for many industries.
Soil surface contamination with solid waste. City landfills for industrial and household waste occupy large areas. The garbage may contain toxic substances, such as mercury or other heavy metals, chemical compounds that dissolve in rain and snow waters and then end up in water bodies and groundwater. Devices containing radioactive substances can also get into the trash.
The soil surface can be contaminated with ash deposited from the smoke of coal-fired thermal power plants, enterprises producing cement, refractory bricks, etc. To prevent this contamination, special dust collectors are installed on the pipes.
Chemical contamination of groundwater. Groundwater currents transport industrial pollution over long distances, and it is not always possible to determine their source. The cause of pollution may be the leaching of toxic substances by rain and snow water from industrial landfills. Pollution of groundwater also occurs during oil production using modern methods, when, to increase the recovery of oil reservoirs, salt water that rose to the surface along with the oil during its pumping is reinjected into wells.
Saline water enters aquifers, and the water in wells acquires a bitter taste and is not suitable for drinking.
Noise pollution. The source of noise pollution can be an industrial enterprise or transport. Heavy dump trucks and trams produce especially loud noise. Noise affects the human nervous system, and therefore noise protection measures are taken in cities and enterprises.
Railway and tram lines and roads along which freight transport passes need to be moved from the central parts of cities to sparsely populated areas and green spaces created around them that absorb noise well.
Airplanes should not fly over cities.
Noise is measured in decibels. The ticking of a clock is 10 dB, the whisper is 25, the noise from a busy highway is 80, the noise of an airplane during takeoff is 130 dB. Noise pain threshold - 140 dB. In residential areas during the day, noise should not exceed 50-66 dB.
Pollutants also include: contamination of the soil surface by dumps of overburden and ash, biological pollution, thermal pollution, radiation pollution, electromagnetic pollution.
Air pollution. If we take air pollution over the ocean as a unit, then over villages it is 10 times higher, over small towns - 35 times, and over large cities - 150 times. The thickness of the layer of polluted air over the city is 1.5 - 2 km.
The most dangerous pollutants are benzo-a-pyrene, nitrogen dioxide, formaldehyde, and dust. In the European part of Russia and the Urals, on average, per 1 sq. km, over 450 kg of atmospheric pollutants fell.
Compared to 1980, the amount of sulfur dioxide emissions increased 1.5 times; 19 million tons of atmospheric pollutants were released into the atmosphere by road transport.
Wastewater discharge into rivers amounted to 68.2 cubic meters. km with post-consumption 105.8 cubic meters. km. Industrial water consumption is 46%. The share of untreated wastewater has been decreasing since 1989 and amounts to 28%.
Due to the predominance of westerly winds, Russia receives 8-10 times more atmospheric pollutants from its western neighbors than it sends to them.
Acid rain has negatively affected half of the forests in Europe, and the process of forest drying has begun in Russia. In Scandinavia, 20,000 lakes have already died due to acid rain coming from Great Britain and Germany. Architectural monuments are dying under the influence of acid rain.
Harmful substances coming out of a chimney 100 m high are dispersed within a radius of 20 km, and at a height of 250 m - up to 75 km. The champion pipe was built at a copper-nickel plant in Sudbury (Canada) and has a height of more than 400 m.
Chlorofluorocarbons (CFCs) that destroy the ozone layer enter the atmosphere from gases from cooling systems (in the USA - 48%, and in other countries - 20%), from the use of aerosol cans (in the USA - 2%, and several years ago their sale was banned; in other countries - 35%), solvents used in dry cleaning (20%) and in the production of foam plastics, including styroform (25-
The main source of freons that destroy the ozone layer is industrial refrigerators. A typical household refrigerator contains 350 g of freon, while an industrial refrigerator contains tens of kilograms. Refrigeration facilities only in
Moscow annually uses 120 tons of freon. A significant part of it ends up in the atmosphere due to imperfect equipment.
Pollution of freshwater ecosystems. In 1989, 1.8 tons of phenols, 69.7 tons of sulfates, and 116.7 tons of synthetic surfactants were discharged into Lake Ladoga, a drinking water reservoir for St. Petersburg with a population of six million.
Pollutes aquatic ecosystems and river transport. On Lake Baikal, for example, 400 ships of various sizes sail, they discharge about 8 tons of oil products into the water per year.
At most Russian enterprises, toxic production waste is either dumped into water bodies, poisoning them, or accumulated without recycling, often in huge quantities. These accumulations of deadly waste can be called “ecological mines”; when dams break, they can end up in water bodies. An example of such an “ecological mine” is the Cherepovets chemical plant “Ammophos”. Its settling basin covers an area of 200 hectares and contains 15 million tons of waste. The dam that encloses the settling basin is raised annually to
4 m. Unfortunately, the “Cherepovets mine” is not the only one.
In developing countries, 9 million people die every year. By the year 2000, more than 1 billion people will not have enough drinking water.
Pollution of marine ecosystems. About 20 billion tons of garbage have been dumped into the World Ocean - from household waste to radioactive waste. Every year for every 1 sq. km of water surface add another 17 tons of garbage.
Every year, more than 10 million tons of oil are poured into the ocean, which forms a film covering 10-15% of its surface; and 5 g of petroleum products is enough to cover 50 square meters with film. m of water surface. This film not only reduces the evaporation and absorption of carbon dioxide, but also causes oxygen starvation and death of eggs and juvenile fish.
Radiation pollution. It is expected that by 2000 the world will have accumulated
1 million cubic meters m of high-level radioactive waste.
Natural radioactive background affects every person, even those who do not come into contact with nuclear power plants or nuclear weapons. We all receive a certain dose of radiation in our lives, 73% of which comes from radiation from natural bodies (for example, granite in monuments, cladding of houses, etc.), 14% from medical procedures (primarily from visiting an X-ray room) and 14% - to cosmic rays. Over a lifetime (70 years), a person can, without much risk, accumulate radiation of 35 rem (7 rem from natural sources, 3 rem from space sources and X-ray machines). In the area of the Chernobyl nuclear power plant in the most contaminated areas you can get up to 1 rem per hour. The radiation power on the roof during the fire extinguishing period at the nuclear power plant reached 30,000 roentgens per hour, and therefore, without radiation protection (lead spacesuit), a lethal dose of radiation could be received in 1 minute.
The hourly dose of radiation, lethal for 50% of organisms, is 400 rem for humans, 1000-2000 for fish and birds, from 1000 to 150,000 for plants and 100,000 rem for insects. Thus, the most severe pollution is not an obstacle to the mass reproduction of insects. Among plants, trees are the least resistant to radiation and grasses are the most resistant.
Pollution from household waste. The amount of accumulated garbage is constantly growing. Now there is from 150 to 600 kg of it per year for each city resident. The most garbage is produced in the USA (520 kg per year per inhabitant), in Norway, Spain, Sweden, the Netherlands - 200-300 kg, and in Moscow - 300-320 kg.
For paper to decompose in the natural environment, it takes from 2 to 10 years, a tin can - more than 90 years, a cigarette filter - 100 years, a plastic bag - more than 200 years, plastic - 500 years, glass - more than 1000 years.
Ways to reduce harm from chemical pollution
The most common pollution is chemical. There are three main ways to reduce harm from them.
Dilution. Even treated wastewater must be diluted 10 times (and untreated waste water - 100-200 times). Factories build tall chimneys to ensure that emitted gases and dust are dispersed evenly. Dilution is an ineffective way to reduce harm from pollution and is only permissible as a temporary measure.
Cleaning. This is the main way to reduce emissions of harmful substances into the environment in Russia today. However, as a result of cleaning, a lot of concentrated liquid and solid waste is generated, which also has to be stored.
Replacement of old technologies with new ones - low-waste. Due to deeper processing, it is possible to reduce the amount of harmful emissions tens of times. Waste from one production becomes raw material for another.
Ecologists in Germany gave figurative names to these three methods of reducing environmental pollution: “extend the pipe” (dilution by dispersion), “plug the pipe” (cleaning) and “tie the pipe in a knot” (low-waste technologies). The Germans restored the ecosystem of the Rhine, which for many years was a sewer where waste from industrial giants was dumped. This was only done in the 80s, when they finally “tie the pipe in a knot.”
The level of environmental pollution in Russia is still very high, and an environmentally unfavorable situation dangerous to public health has developed in almost 100 cities of the country.
Some improvement in the environmental situation in Russia has been achieved due to improved operation of treatment facilities and a drop in production.
Further reductions in emissions of toxic substances into the environment can be achieved by introducing less hazardous, low-waste technologies. However, in order to “tie the pipe in a knot,” it is necessary to update equipment at enterprises, which requires very large investments and therefore will be carried out gradually.
Cities and industrial facilities (oil fields, quarries for coal and ore development, chemical and metallurgical plants) operate on energy that comes from other industrial ecosystems (the energy complex), and their products are not plant and animal biomass, but steel, cast iron and aluminum, various machines and devices, building materials, plastics and much more that does not exist in nature.
Urban environmental problems are primarily problems of reducing emissions of various pollutants into the environment and protecting water, atmosphere, and soil from cities. They are solved by creating new low-waste technologies and production processes and efficient treatment facilities.
Plants play a major role in mitigating the influence of urban environmental factors on humans. Green spaces improve the microclimate, trap dust and gases, and have a beneficial effect on the mental state of city residents.
Literature:
Mirkin B.M., Naumova L.G. Ecology of Russia. Textbook from the Federal set for grades 9 - 11 of secondary schools. Ed. 2nd, revised
And additional - M.: JSC MDS, 1996. - 272 pp.
communities) among themselves and with their environment. This term was first proposed by the German biologist Ernst Haeckel in 1869. It emerged as an independent science at the beginning of the 20th century along with physiology, genetics and others. The field of application of ecology is organisms, populations and communities. Ecology views them as a living component of a system called an ecosystem. In ecology, the concepts of population—community and ecosystem—have clear definitions.
A population (from an ecological point of view) is a group of individuals of the same species occupying a certain territory and, usually, to one degree or another, isolated from other similar groups.
A community is any group of organisms of different species living in the same area and interacting with each other through trophic (food) or spatial connections.
An ecosystem is a community of organisms with their environment that interact with each other and form an ecological unit.
All ecosystems of the Earth are united into the ecosphere. It is clear that it is absolutely impossible to cover the entire biosphere of the Earth with research. Therefore, the point of application of ecology is the ecosystem. However, an ecosystem, as can be seen from the definitions, consists of populations, individual organisms and all factors of inanimate nature. Based on this, several different approaches to studying ecosystems are possible.
Ecosystem approach.In the ecosystem approach, the ecologist studies the flow of energy in the ecosystem. The greatest interest in this case is the relationship of organisms with each other and with the environment. This approach makes it possible to explain the complex structure of relationships in an ecosystem and provide recommendations for rational environmental management.
Studying communities. With this approach, the species composition of communities and the factors limiting the distribution of specific species are studied in detail. In this case, clearly distinguishable biotic units (meadow, forest, swamp, etc.) are studied.
an approach. The point of application of this approach, as the name suggests, is the population.
Habitat study. In this case, a relatively homogeneous area of the environment where a given organism lives is studied. It is usually not used separately as an independent area of research, but it provides the necessary material for understanding the ecosystem as a whole.
It should be noted that all of the above approaches should ideally be used in combination, but at the moment this is practically impossible due to the significant scale of the objects under study and the limited number of field researchers.
Ecology as a science uses a variety of research methods to obtain objective information about the functioning of natural systems.
Methods of environmental research:
- observation
- experiment
- population counting
- modeling method
Remember:
What is meant by the natural and social nature of man?
Answer. Man, like all other living beings, is part of nature and a product of natural, biological evolution. Man, like animals, is characterized by instincts and vital needs. There are also biologically programmed patterns of human behavior as a specific biological species. Biological factors that determine existence and development are determined by the set of genes in humans, the balance of hormones produced, metabolism and other biological factors. All this characterizes a person as a biological being and determines his biological nature. But at the same time, it differs from any animal and, above all, in the following features:
Produces its own environment (housing, clothing, tools), but the animal does not produce, only uses what is available;
It changes the world around it not only according to the measure of its utilitarian needs, but also according to the laws of knowledge of this world, as well as according to the laws of morality and beauty, but an animal can change its world only according to the needs of its species;
It can act not only according to need, but also in accordance with the freedom of its will and imagination, while the action of an animal is oriented exclusively towards satisfying a physical need (hunger, procreation instinct, group, species instincts, etc.);
Capable of acting universally, an animal only in relation to specific circumstances;
He makes his life activity an object (he treats it meaningfully, purposefully changes it, plans it), but the animal is identical to his life activity and does not distinguish it from himself.
What factors are called biotic and abiotic?
Answer. Abiotic factors - conditions of the atmosphere, sea and fresh water, soil or bottom sediments) and physical or climatic (temperature, pressure, wind, currents, radiation regime, etc.). The structure of the surface (relief), geological and climatic differences of the earth's surface create a huge variety of abiotic factors that play a different role in the life of species of animals, plants and microorganisms that have adapted to them.
What is the diversity of anthropogenic factors?
Answer. Anthropogenic factors are very diverse. By nature, anthropogenic factors are divided into:
Mechanical - pressure from car wheels, deforestation, obstacles to the movement of organisms, and the like;
Physical - heat, light, electric field, color, changes in humidity, etc.;
Chemical - the action of various chemical elements and their compounds;
Biological - the influence of introduced organisms, breeding of plants and animals, forest planting and the like.
Landscape - artificial rivers and lakes, beaches, forests, meadows, etc.
Based on the time of origin and duration of action, anthropogenic factors are divided into the following groups:
Factors produced in the past: a) those that have ceased to act, but its consequences are still felt now (destruction of certain types of organisms, excessive grazing, etc.); b) those that continue to operate in our time (artificial relief, reservoirs, introduction, etc.);
Factors that are produced in our time: a) those that act only at the moment of production (radio waves, noise, light); b) those that operate for a certain time and after the end of production (persistent chemical pollution, cut down forest, etc.).
Questions after § 9
Describe the patterns of action of environmental factors on the body?
The ability of organisms to adapt to a certain range of variability in environmental factors is called ecological plasticity. This feature is one of the most important properties of all living things: by regulating their life activity in accordance with changes in environmental conditions, organisms acquire the ability to survive and leave offspring. There are upper and lower limits to endurance.
Environmental factors affect a living organism jointly and simultaneously. Moreover, the effect of one factor depends on the strength with which and in what combination other factors act simultaneously. This pattern is called the interaction of factors. For example, heat or frost is easier to bear in dry rather than humid air. The rate of water evaporation from plant leaves (transpiration) is much higher if the air temperature is high and the weather is windy.
In some cases, the deficiency of one factor is partially compensated by the strengthening of another. The phenomenon of partial interchangeability of the effects of environmental factors is called the compensation effect. For example, the wilting of plants can be stopped both by increasing the amount of moisture in the soil and by decreasing the air temperature, which reduces transpiration; in deserts, the lack of precipitation is compensated to a certain extent by increased relative humidity at night; In the Arctic, long daylight hours in summer compensate for the lack of heat.
At the same time, none of the environmental factors necessary for the body can be completely replaced by another. The absence of light makes plant life impossible, despite the most favorable combinations of other conditions. Therefore, if the value of at least one of the vital environmental factors approaches a critical value or goes beyond its limits (below the minimum or above the maximum), then, despite the optimal combination of other conditions, the individuals are threatened with death. Such factors are called limiting factors.
What is the optimum, the limits of endurance?
Answer. Environmental factors have quantitative expression. In relation to each factor, one can distinguish an optimum zone (a zone of normal life activity), a zone of depression and the limits of the body’s endurance. Optimum is the amount of environmental factor at which the intensity of vital activity of organisms is maximum. In the zone of oppression, the vital activity of organisms is suppressed. Beyond the limits of endurance, the existence of an organism is impossible. There are lower and upper limits of endurance.
What factor is called the limiting factor?
Answer. An environmental factor, the quantitative value of which goes beyond the endurance of the species, is called a limiting factor. This factor will limit the spread of the species even if all other factors are favorable. Limiting factors determine the geographic range of a species. Human knowledge of the limiting factors for a particular type of organism allows, by changing environmental conditions, to either suppress or stimulate its development.
Environmental factors are any external factors that have a direct or indirect effect on the number (abundance) and geographic distribution of organisms.
Environmental factors are very diverse both in nature and in their impact on living organisms. Conventionally, all environmental factors are usually divided into three large groups - abiotic, biotic and anthropogenic.
Abiotic factors- These are factors of inanimate nature.
Climatic (sunlight, temperature, air humidity) and local (relief, soil properties, salinity, currents, wind, radiation, etc.). Can be direct or indirect.
Anthropogenic factors- these are those forms of human activity that, by affecting the environment, change the living conditions of living organisms or directly affect certain species of plants and animals. One of the most important anthropogenic factors is pollution.
Environmental conditions.
Environmental conditions, or ecological conditions, are abiotic environmental factors that vary in time and space, to which organisms react differently depending on their strength. Environmental conditions impose certain restrictions on organisms.
The most important factors determining the living conditions of organisms in almost all living environments include temperature, humidity and light.
Temperature.
Any organism is able to live only within a certain temperature range: individuals of the species die at too high or too low temperatures. The limits of temperature tolerance vary among different organisms. There are species that can tolerate temperature fluctuations over a wide range. For example, lichens and many bacteria are able to live at very different temperatures. Among animals, warm-blooded animals have the greatest range of temperature tolerance. The tiger, for example, tolerates both the Siberian cold and the heat of the tropical regions of India or the Malay Archipelago equally well. But there are also species that can live only within more or less narrow temperature limits. In the land-air environment and even in many parts of the aquatic environment, the temperature does not remain constant and can vary greatly depending on the season of the year or the time of day. In tropical areas, annual temperature variations may be even less noticeable than daily ones. Conversely, in temperate areas, temperatures vary significantly between seasons. Animals and plants are forced to adapt to the unfavorable winter season, during which active life is difficult or simply impossible. In tropical areas such adaptations are less pronounced. During a cold period with unfavorable temperature conditions, there seems to be a pause in the life of many organisms: hibernation in mammals, shedding of leaves in plants, etc. Some animals make long migrations to places with a more suitable climate.
Humidity.
Water is an integral part of the vast majority of living things: it is necessary for their normal functioning. A normally developing organism constantly loses water and therefore cannot live in completely dry air. Sooner or later, such losses can lead to the death of the body.
The simplest and most convenient indicator characterizing the humidity of a particular area is the amount of precipitation falling there over a year or another period of time.
Plants extract water from the soil using their roots. Lichens can capture water vapor from the air. Plants have a number of adaptations that ensure minimal water loss. All land animals require periodic supply of water to compensate for the inevitable loss of water due to evaporation or excretion. Many animals drink water; others, such as amphibians, some insects and mites, absorb it in a liquid or vapor state through their body coverings. Most desert animals never drink. They satisfy their needs from water supplied with food. Finally, there are animals that obtain water in an even more complex way - through the process of fat oxidation, for example the camel. Animals, like plants, have many adaptations to save water.
Light.
There are light-loving plants, which are able to develop only under the sun's rays, and shade-tolerant plants, which are able to grow well under the forest canopy. This is of great practical importance for the natural regeneration of the forest stand: young shoots of many tree species are able to develop under the cover of large trees. In many animals, normal lighting conditions manifest themselves in a positive or negative reaction to light. Nocturnal insects flock to the light, and cockroaches scatter in search of shelter if only the light is turned on in a dark room. Photoperiodism (the change of day and night) is of great ecological importance for many animals that are exclusively diurnal (most passerines) or exclusively nocturnal (many small rodents, bats). Small crustaceans, floating in the water column, stay in surface waters at night, and during the day they descend to the depths, avoiding too bright light.
Light has almost no direct effect on animals. It serves only as a signal for the restructuring of processes occurring in the body.
Light, humidity, and temperature do not at all exhaust the set of environmental conditions that determine the life and distribution of organisms. Factors such as wind, atmospheric pressure, and altitude are also important. Wind has an indirect effect: by increasing evaporation, it increases dryness. Strong winds contribute to cooling. This action is important in cold places, high mountains or polar regions.
Anthropogenic factors. Anthropogenic factors are very diverse in their composition. Man influences living nature by laying roads, building cities, conducting agriculture, blocking rivers, etc. Modern human activity is increasingly manifested in environmental pollution with by-products, often poisonous. In industrial areas, concentrations of pollutants sometimes reach threshold values, that is, lethal for many organisms. However, no matter what, there will almost always be at least a few individuals of several species that can survive in such conditions. The reason is that resistant individuals are rarely found in natural populations. As pollution levels increase, resistant individuals may be the only survivors. Moreover, they can become the founders of a stable population that has inherited immunity to this type of pollution. For this reason, pollution gives us the opportunity to, as it were, observe evolution in action. However, not every population is endowed with the ability to resist pollution. Thus, the effect of any pollutant is twofold.
Law of Optimum.
Many factors are tolerated by the body only within certain limits. The organism dies if, for example, the environmental temperature is too low or too high. In environments where temperatures are close to these extremes, living inhabitants are rare. However, their number increases as the temperature approaches the average value, which is the best (optimal) for a given species. And this pattern can be transferred to any other factor.
The range of factor parameters at which the body feels comfortable is optimal. Organisms with wide margins of resistance certainly have a chance of becoming more widespread. However, wide limits of endurance for one factor do not mean wide limits for all factors. The plant may be tolerant of large temperature fluctuations, but have narrow ranges of water tolerance. An animal like trout can be very temperature sensitive but eat a wide variety of foods.
Sometimes during the life of an individual, its tolerance (selectivity) may change. The body, finding itself in harsh conditions, after a while gets used to it and adapts to it. The consequence of this is a change in the physiological optimum, and the process is called adaptation or acclimatization.
Law of the minimum was formulated by the founder of the science of mineral fertilizers, Justus Liebig (1803-1873).
Yu. Liebig discovered that plant yield can be limited by any of the basic nutritional elements, if only this element is in short supply. It is known that different environmental factors can interact, that is, a deficiency of one substance can lead to a deficiency of other substances. Therefore, in general, the law of the minimum can be formulated as follows: an element or factor of the environment that is at a minimum limits (limites) the vital activity of the organism to the greatest extent.
Despite the complexity of the relationships between organisms and their environment, not all factors have the same ecological significance. For example, oxygen is a factor of physiological necessity for all animals, but from an ecological point of view it becomes limiting only in certain habitats. If fish die in a river, the oxygen concentration in the water must first be measured, since it is highly variable, oxygen reserves are easily depleted and there is often not enough oxygen. If the death of birds is observed in nature, it is necessary to look for another reason, since the oxygen content in the air is relatively constant and sufficient from the point of view of the requirements of terrestrial organisms.
Self-test questions:
List the main living environments.
What are environmental conditions?
Describe the living conditions of organisms in soil, aquatic and land-air habitats.
Give examples of how organisms adapt to living in different habitats?
What are the adaptations of organisms that use other organisms as a habitat?
What effect does temperature have on different types of organisms?
How do animals and plants get the water they need?
What effect does light have on organisms?
How does the impact of pollutants on organisms manifest?
Justify what environmental factors are and how they affect living organisms?
What factors are called limiting?
What is acclimatization and what significance does it have in the dispersal of organisms?
How do the laws of optimum and minimum manifest themselves?