It is not an environmental factor. Fundamentals of ecology
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 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 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 weakly expressed in the soil. For example, if nitrogen in the soil is only 10% of the required norm, and phosphorus - 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 over the edge where the shortest board is, and the length of the rest no longer matters much.
Water
This factor is the most severe and significant in comparison with 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 or animal. 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 a very scarce and peculiar flora and fauna.
Light
The light coming in the form of solar radiation ensures 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 occurring in the body depend on external and internal temperature. Moreover, most of the species are adapted to a rather narrow range (15-30 °C). 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. So, in hot weather, in order to avoid overheating in plants, it increases through the stomata, in animals - through the skin and the respiratory system, as well as behavioral features (hide in the shade, burrows, etc.).
Pollutants
The value 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 replaces 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 wide enough, others are narrow. Depending on this indicator, eurybionts and stenobionts are distinguished. The former are able to tolerate a large amplitude of fluctuations of various limiting factors. For example, living everywhere from the steppes to the forest-tundra, wolves, etc. Stenobionts, on the contrary, are able to withstand very narrow fluctuations, and they include almost all rainforest plants.
Definition
Ecology- is the science of the relationship of organisms with each other and with the surrounding inanimate nature.
The term "ecology" was introduced into scientific use in 1866 by the German zoologist and evolutionist, a follower of Charles Darwin E. Haeckel.
Ecology tasks:
The study of the spatial distribution and adaptive capabilities of living organisms, their role in the cycle of substances (ecology of individuals, or autecology).
Study of population dynamics and structure (population ecology).
The study of the composition and spatial structure of communities, the circulation of matter and energy in biosystems (ecology of communities, or ecosystem ecology).
Study of the interaction with the environment of individual taxonomic groups of organisms (ecology of plants, ecology of animals, ecology of microorganisms, etc.).
The study of various ecosystems: water (hydrobiology), forest (forestry).
Reconstruction and study of the evolution of ancient communities (paleoecology).
Ecology is closely related to other sciences: physiology, genetics, physics, geography and biogeography, geology and evolutionary theory.
In environmental calculations, methods of mathematical and computer modeling, the method of statistical data analysis are used.
environmental factors
Environmental factors- components of the environment that affect a living organism.
The existence of a particular species depends on a combination of many different factors. Moreover, for each species, the significance of individual factors, as well as their combinations, are very specific.
Types of environmental factors:
Abiotic factors- factors of inanimate nature, directly or indirectly acting on the body.
Examples: relief, temperature and humidity, light, current and wind.
Biotic factors- factors of nature that affect the body.
Examples: microorganisms, animals and plants.
Anthropogenic factors- factors associated with human activity.
Examples: road construction, land plowing, industry and transport.
Abiotic factors
climatic: annual sum of temperatures, average annual temperature, humidity, air pressure;
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ECOLOGICAL GROUPS OF PLANTS
In relation to water exchange
hydrophytes - plants that constantly live in water;
hydrophytes - plants partially submerged in water;
helophytes - marsh plants;
hygrophytes - terrestrial plants that live in excessively humid places;
mesophytes - plants that prefer moderate moisture;
xerophytes - plants adapted to a constant lack of moisture (including succulents- plants that accumulate water in their body tissues (for example, Crassula and cacti);
sclerophytes are drought-resistant plants with tough, leathery leaves and stems.
edaphic (soil): mechanical composition of the soil, air permeability of the soil, acidity of the soil, chemical composition of the soil;
ECOLOGICAL GROUPS OF PLANTS
In relation to soil fertility The following ecological groups of plants are distinguished:
oligotrophs - plants of poor, infertile soils (scotch pine);
mesotrophs - plants with a moderate need for nutrients (most forest plants of temperate latitudes);
eutrophic - plants that require a large amount of nutrients in the soil (oak, hazel, gout).
ECOLOGICAL GROUPS OF PLANTS
All plants in relation to the world can be divided into three groups: heliophytes, sciophytes, facultative heliophytes.
Heliophytes are light-loving plants (steppe and meadow grasses, tundra plants, early spring plants, most open ground cultivated plants, many weeds).
Sciophytes are shade-loving plants (forest grasses).
Facultative heliophytes are shade-tolerant plants, capable of developing both with very large and with a small amount of light (common spruce, Norway maple, common hornbeam, hazel, hawthorn, strawberry, field geranium, many indoor plants).
The combination of various abiotic factors determines the distribution of species of organisms in different regions of the globe. A certain biological species is not found everywhere, but in areas where there are conditions necessary for its existence.
phytogenic - influence of plants;
mycogenic - the influence of fungi;
zoogenic - the influence of animals;
microbiogenic - the influence of microorganisms.
ANTHROPOGENIC FACTORS
Although a person influences living nature through a change in abiotic factors and biotic relationships of species, the activities of people on the planet are distinguished as a special force.
physical: the use of nuclear energy, travel in trains and planes, the impact of noise and vibration;
chemical: the use of mineral fertilizers and pesticides, pollution of the Earth's shells by industrial and transport waste;
biological: food; organisms for which a person can be a habitat or a source of food;
social - related to people's relationships and life in society: interaction with domestic animals, synanthropic species (flies, rats, etc.), the use of circus and farm animals.
The main methods of anthropogenic influence are: the importation of plants and animals, the reduction of habitats and the destruction of species, the direct impact on vegetation, the plowing of land, cutting down and burning forests, grazing domestic animals, mowing, drainage, irrigation and watering, air pollution, the creation of garbage dumps and wastelands, creation of cultural phytocenoses. To this should be added various forms of crop and livestock activities, measures for the protection of plants, the protection of rare and exotic species, the hunting of animals, their acclimatization, etc.
The influence of the anthropogenic factor has been constantly increasing since the appearance of man on Earth.
ECOLOGICAL OPTIMUM OF THE VIEW
It is possible to establish the general nature of the impact of environmental factors on a living organism. Any organism has a specific set of adaptations to environmental factors and successfully exists only within certain limits of their variability.
Ecological optimum- the value of one or more environmental factors that are most favorable for the existence of a given species or community.
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Optimum zone- this is the range of the factor that is most favorable for the life of this species.
Deviations from the optimum determine zonesoppression (zonespessimism). The stronger the deviation from the optimum, the more pronounced the inhibitory effect of this factor on organisms.
Critical points- minimum and maximum tolerated values of the factor, behind which the organism dies.
Tolerance area- the range of values of the environmental factor, in which the existence of the organism is possible.
Each organism has its own maximums, optimums and minimums of environmental factors. For example, a housefly can withstand temperature fluctuations from 7 to 50 ° C, and the human roundworm lives only at human body temperature.
ECOLOGICAL NICHE
ecological niche- a set of environmental factors (abiotic and biotic) that are necessary for the existence of a particular species.
The ecological niche characterizes the way of life of the organism, the conditions of its habitat and nutrition. In contrast to a niche, the concept of habitat refers to the territory where an organism lives, i.e. its “address”. For example, herbivorous inhabitants of the steppes - a cow and a kangaroo - occupy the same ecological niche, but have different habitats. On the contrary, the inhabitants of the forest - squirrel and elk, also related to herbivores - occupy different ecological niches.
The ecological niche always determines the distribution of the organism and its role in the community.
In the same community, two species cannot occupy the same ecological niche.
LIMITING FACTOR
Limiting (limiting) factor- any factor that limits the development or existence of an organism, species or community.
For example, if a particular micronutrient is lacking in the soil, this causes a decrease in plant productivity. Due to the lack of food, insects that feed on these plants die. The latter is reflected in the survival of entomophagous predators: other insects, birds, and amphibians.
Limiting factors determine the distribution range of each species. For example, the spread of many species of animals to the north is constrained by a lack of heat and light, to the south by a lack of moisture.
Shelford's Law of Tolerance
The limiting factor limiting the development of an organism can be both a minimum and a maximum of environmental impact.
The law of tolerance can be formulated more simply: it is bad both to underfeed and to overfeed a plant or animal.
A consequence follows from this law: any excess of matter or energy is a polluting component. For example, in arid areas, excess water is harmful, and water can be seen as a pollutant.
So, for each species there are limits to the values of the vital factors of the abiotic environment, which limit the zone of its tolerance (stability). A living organism can exist in a certain range of factor values. The wider this interval, the higher the resistance of the organism. The law of tolerance is one of the fundamental ones in modern ecology.
REGULARITIES OF THE ACTION OF ENVIRONMENTAL FACTORS
LAW OF OPTIMUM
Law of Optimum
Any environmental factor has certain limits of positive impact on living organisms.
Factors positively affect organisms only within certain limits. Insufficient or excessive their action affects organisms negatively.
The law of optimum is universal. It defines the boundaries of the conditions under which the existence of species is possible, as well as the measure of the variability of these conditions.
Stenobionts- highly specialized species that can only live in relatively constant conditions. For example, deep-sea fish, echinoderms, crustaceans do not tolerate temperature fluctuations even within 2–3 °C. Plants of humid habitats (marsh marigold, impatiens, etc.) instantly wither if the air around them is not saturated with water vapor.
eurybionts- species with a large range of hardiness (ecologically plastic species). For example, cosmopolitan species.
If it is necessary to emphasize the attitude to any factor, use the combinations "steno-" and "evry-" in relation to its name, for example, a stenothermic species - not tolerant of temperature fluctuations, euryhaline - capable of living with wide fluctuations in water salinity, etc.
LIEBIG'S LAW OF THE MINIMUM
Liebig's law of the minimum, or law of the limiting factor
The most significant factor for the organism is the factor that most of all deviates from its optimal value.
The survival of the organism depends on this minimally (or maximally) ecological factor presented at this particular moment. 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 - winter temperature; and for grayling - the concentration of oxygen dissolved in water.
This law is taken into account in the practice of agriculture. The German chemist Justus von Liebig found that the productivity of cultivated plants primarily depends on the nutrient (mineral element) that is present in the soil. weakest. For example, if phosphorus in the soil is only 20% of the required rate, and calcium is 50% of the rate, 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" (see fig.). 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.
INTERACTION OF ENVIRONMENTAL FACTORS
A change in the intensity of one environmental factor can narrow the endurance limit of an organism to another factor or, conversely, increase it.
In the natural environment, the effect of factors on the body can be summed up, mutually enhanced or compensated.
summation of factors. Example: high radioactivity of the environment and the simultaneous content of nitrate nitrogen in drinking water and food several times increase the threat to human health than each of these factors separately.
Mutual strengthening (the phenomenon of synergy). The consequence of this is a decrease in the viability of the organism. High humidity significantly reduces the body's resistance to high temperatures. A decrease in the nitrogen content in the soil leads to a decrease in the drought resistance of cereals.
Compensation. Example: ducks left to winter in temperate latitudes compensate for the lack of heat with abundant food; the poverty of the soil in the humid equatorial forest is compensated by the rapid and efficient circulation of substances; in places where there is a lot of strontium, molluscs can replace calcium in their shells with strontium. Optimal temperature increases tolerance to lack of moisture and food.
At the same time, none of the factors necessary for the body can be completely replaced by another. For example, a lack of moisture slows down the process of photosynthesis even with optimal illumination and $CO_2$ concentration in the atmosphere; the lack of heat cannot be replaced by an abundance of light, and the mineral elements necessary for plant nutrition cannot be replaced by water. Therefore, if the value of at least one of the necessary factors goes beyond the tolerance range, then the existence of the organism becomes impossible (see Liebig's law).
The intensity of the impact of environmental factors is directly dependent on the duration of this impact. Prolonged exposure to high or low temperatures is detrimental to many plants, while plants tolerate short-term drops normally.
Thus, environmental factors act on organisms jointly and simultaneously. The presence and prosperity of organisms in a particular habitat depends on a whole range of conditions.
Environmental factors and the concept of an ecological niche
The concept of environmental factor
1.1.1. The concept of environmental factors and their classification
From an environmental point of view Wednesday - These are natural bodies and phenomena with which the organism is in direct or indirect relations. The environment surrounding the body is characterized by great diversity, consisting of many elements, phenomena, conditions that are dynamic in time and space, which are considered as factors .
Environmental factor - is any environmental condition, capable of exerting a direct or indirect effect on living organisms, at least during one of the phases of their individual development. In turn, the organism reacts to the environmental factor with specific adaptive reactions.
Thus, environmental factors- these are all elements of the natural environment that affect the existence and development of organisms, and to which living creatures they react with adaptation reactions (death occurs outside the ability of adaptation).
It should be noted that in nature, environmental factors act in a complex way. It is especially important to keep this in mind when evaluating the impact of chemical contaminants. In this case, the "total" effect, when the negative effect of one substance is superimposed on the negative effect of others, and the influence of a stressful situation, noise, and various physical fields is added to this, significantly changes the MPC values given in reference books. This effect is called synergistic.
The most important concept is limiting factor, that is, the level (dose) of which approaches the endurance limit of the organism, the concentration of which is lower or higher than optimal. This concept is defined by Liebig's (1840) minimum laws and Shelford's (1913) tolerance laws. The most frequently limiting factors are temperature, light, nutrients, currents and pressure in the environment, fires, etc.
The most common are organisms with a wide range of tolerance for all environmental factors. The highest tolerance is characteristic of bacteria and blue-green algae, which survive in a wide range of temperatures, radiation, salinity, pH, etc.
Ecological studies related to the determination of the influence of environmental factors on the existence and development of certain types of organisms, the relationship of the organism with the environment, are the subject of science autecology . The section of ecology that studies the associations of populations of various plant, animal, microbial species (biocenoses), the ways of their formation and interaction with the environment is called synecology . Within the boundaries of synecology, phytocenology, or geobotany (the object of study is plant groups), biocenology (groups of animals) is distinguished.
Thus, the concept of an ecological factor is one of the most general and extremely broad concepts of ecology. In accordance with this, the task of classifying environmental factors turned out to be very difficult, so there is still no generally accepted version. At the same time, agreement was reached on the advisability of using certain features in the classification of environmental factors.
Traditionally, three groups of environmental factors have been distinguished:
1) abiotic (inorganic conditions - chemical and physical, such as the composition of air, water, soil, temperature, light, humidity, radiation, pressure, etc.);
2) biotic (forms of interaction between organisms);
3) anthropogenic (forms of human activity).
Today, ten groups of environmental factors are distinguished (the total number is about sixty), united in a special classification:
1. by time - factors of time (evolutionary, historical, acting), periodicity (periodic and non-periodic), primary and secondary;
2. by origin (cosmic, abiotic, biotic, natural, technogenic, anthropogenic);
3. by the environment of occurrence (atmospheric, water, geomorphological, ecosystem);
4. by nature (informational, physical, chemical, energy, biogenic, complex, climatic);
5. by the object of influence (individual, group, specific, social);
6. according to the degree of influence (lethal, extreme, limiting, disturbing, mutagenic, teratogenic);
7. according to the conditions of action (dependent or independent of density);
8. according to the spectrum of influence (selective or general action).
First of all, environmental factors are divided into external (exogenous or entopic) and domestic (endogenous) in relation to this ecosystem.
To external include factors whose actions, to one degree or another, determine the changes taking place in the ecosystem, but they themselves practically do not experience its reverse impact. These are solar radiation, precipitation intensity, atmospheric pressure, wind speed, current speed, etc.
Unlike them internal factors correlate with the properties of the ecosystem itself (or its individual components) and actually form its composition. Such are the numbers and biomass of populations, the reserves of various substances, the characteristics of the surface layer of air, water or soil mass, etc.
The second common classification principle is the division of factors into biotic and abiotic . The former include a variety of variables that characterize the properties of living matter, and the latter - non-living components of the ecosystem and its environment. The division of factors into endogenous - exogenous and biotic - abiotic do not coincide. In particular, there are both exogenous biotic factors, for example, the intensity of the introduction of seeds of a certain species into the ecosystem from outside, and endogenous abiotic factors, such as the concentration of O 2 or CO 2 in the surface layer of air or water.
Widespread use in environmental literature is the classification of factors according to the general nature of their origin or object of influence. For example, among exogenous factors, there are meteorological (climatic), geological, hydrological, migratory (biogeographic), anthropogenic factors, and among endogenous - micrometeorological (bioclimatic), soil (edaphic), water and biotic.
An important classification indicator is nature of dynamics environmental factors, in particular the presence or absence of its periodicity (daily, lunar, seasonal, long-term). This is due to the fact that the adaptive reactions of organisms to certain environmental factors are determined by the degree of constancy of the impact of these factors, that is, their periodicity.
Biologist A.S. Monchadsky (1958) singled out primary periodic factors, secondary periodic factors, and non-periodic factors.
To primary periodic factors are mainly phenomena associated with the rotation of the Earth: the change of seasons, the daily change in illumination, tidal phenomena, etc. These factors, which are characterized by the correct periodicity, acted even before the appearance of life on Earth, and emerging living organisms had to immediately adapt to them.
Secondary periodic factors - a consequence of primary periodic ones: for example, humidity, temperature, precipitation, dynamics of plant food, the content of dissolved gases in water, etc.
To non-periodic include factors that do not have the correct periodicity, cyclicality. These are the soil and ground factors, all sorts of natural phenomena. Anthropogenic impacts on the environment are often referred to as non-periodic factors that may appear suddenly and irregularly. Since the dynamics of natural periodic factors is one of the driving forces of natural selection and evolution, living organisms, as a rule, do not have time to develop adaptive reactions, for example, to a sharp change in the content of certain impurities in the environment.
A special role among environmental factors belongs to summative (additive) factors characterizing the abundance, biomass or density of populations of organisms, as well as the reserves or concentrations of various forms of matter and energy, the temporal changes of which are subject to conservation laws. Such factors are called resources . For example, they talk about the resources of heat, moisture, organic and mineral food, etc. In contrast, factors such as intensity and spectral composition of radiation, noise level, redox potential, wind or current speed, size and shape of food, etc., which greatly affect organisms, are not classified as resources, because .to. conservation laws do not apply to them.
The number of possible environmental factors seems to be potentially unlimited. However, in terms of the degree of impact on organisms, they are far from equivalent, as a result of which, in ecosystems of various types, some factors stand out as the most significant, or imperative . In terrestrial ecosystems, among the exogenous factors, they usually include the intensity of solar radiation, air temperature and humidity, the intensity of precipitation, wind speed, the rate of introduction of spores, seeds and other embryos or the influx of adults from other ecosystems, as well as all kinds of forms anthropogenic impact. Endogenous imperative factors in terrestrial ecosystems are the following:
1) micrometeorological - illumination, temperature and humidity of the surface layer of air, the content of CO 2 and O 2 in it;
2) soil - temperature, humidity, soil aeration, physical and mechanical properties, chemical composition, humus content, availability of mineral nutrition elements, redox potential;
3) biotic - the density of populations of different species, their age and sex composition, morphological, physiological and behavioral characteristics.
1.1.2. The space of environmental factors and the function of the response of organisms to a set of environmental factors
The intensity of the impact of each environmental factor can be numerically characterized, that is, described by a mathematical variable that takes on a value on a certain scale.
Environmental factors can be ordered by their strength relative to the impact on the organism, population, ecosystem, that is ranked . If the value of the first influencing factor is measured by the variable X 1 , second - variable X 2 , … , n-th - variable x n etc., then the whole complex of environmental factors can be represented by a sequence ( X 1 , X 2 , … , x n, …). In order to characterize the set of various complexes of environmental factors that are obtained at different values of each of them, it is advisable to introduce the concept of the space of environmental factors, or, in other words, the ecological space.
The space of environmental factors Let's call the Euclidean space, the coordinates of which are compared to the ranked environmental factors:
To quantify the impact of environmental factors on the vital activity of individuals, such as the rate of growth, development, fertility, life expectancy, mortality, nutrition, metabolism, motor activity, etc. (let them be numbered with an index k= 1, …, m), the concept of f at n to c and I X
about t to l and ka
.
Values accepted by an indicator with a number k on a certain scale when varying environmental factors, as a rule, are limited from below and from above. Denote by 
segment on the scale of values of one of the indicators ( k th) the life of the ecosystem.
response function k-th indicator on the totality of environmental factors ( X 1 , X 2 , … , x n, …) is called a function φk, representing ecological space E on the scale Ik:
,
which to each point ( X 1 , X 2 , … , x n, …) spaces E matches a number φk(X 1 , X 2 , … , x n, …) on the scale Ik .
Although the number of environmental factors is potentially unlimited and, therefore, the dimensions of the ecological space are infinite. E and number of response function arguments φk(X 1 , X 2 , … , x n, …), in fact, it is possible to isolate a finite number of factors, for example n, which can be used to explain the specified part of the total variation of the response function. For example, the first 3 factors can explain 80% of the total variation in the indicator φ , the first 5 factors - 95%, the first 10 - 99%, etc. The rest, not included in the number of these factors, do not have a decisive impact on the indicator under study. Their influence can be seen as some " ecological"noise superimposed on the action of imperative factors.
This allows from infinite dimensional space E go to it n-dimensional subspace En and consider the narrowing of the response function φk to this subspace:
and , where εn+1 - random " environmental noise".
Any living organism does not need temperature, humidity, mineral and organic substances or any other factors in general, but their specific regime, that is, there are some upper and lower limits of the amplitude of permissible fluctuations of these factors. The wider the limits of any factor, the higher the stability, that is tolerance of this organism.
In typical cases, the response function has the form of a convex curve, monotonically increasing from the minimum value of the factor xj s (lower limit of tolerance) to a maximum at the optimal value of the factor xj 0 and monotonically decreasing to the maximum value of the factor xj e (upper limit of tolerance).
Interval Xj = [xj s , xj e] is called tolerance interval on this factor, and the point xj 0 , at which the response function reaches an extremum, is called optimum point on this factor.
The same environmental factors affect organisms of different species living together in different ways. For some they may be favorable, for others they may not. An important element is the reaction of organisms to the strength of the impact of an environmental factor, the negative effect of which may occur in case of an excess or lack of a dose. Therefore, there is the concept of a favorable dose or optimum zone factor and pessimum zones (the range of dose values of the factor in which organisms feel oppressed).
The ranges of the optimum and pessimum zones are the criterion for determining ecological valency - the ability of a living organism to adapt to changes in environmental conditions. Quantitatively, it is expressed by the range of the environment within which the species normally exists. The ecological valency of different species can be very different (reindeer can withstand fluctuations in air temperature from -55 to +25÷30°C, and tropical corals die even when the temperature changes by 5-6°C). According to ecological valency, organisms are divided into stenobionts - with low adaptability to environmental changes (orchids, trout, Far Eastern hazel grouse, deep-sea fish) and eurybionts - with greater adaptability to environmental changes (Colorado potato beetle, mice, rats, wolves, cockroaches, reeds, wheatgrass). Within the boundaries of eurybionts and stenobionts, depending on a specific factor, organisms are divided into eurythermal and stenothermic (by reaction to temperature), euryhaline and stenohaline (by reaction to salinity of the aquatic environment), eurythoty and stenofoty (by reaction to lighting).
To express the relative degree of tolerance, there are a number of terms in ecology that use prefixes steno -, which means narrow, and evry - - wide. Species that have a narrow tolerance interval (1) are called stenoeks , and species with a wide tolerance interval (2) euryekami on this factor. Imperative factors have their own terms:
by temperature: stenothermic - eurythermal;
by water: stenohydric - euryhydric;
by salinity: stenohaline - euryhaline;
by food: stenophagous - euryphagic;
according to the choice of habitat: wall-stained - euryoic.
1.1.3. Law of the limiting factor
The presence or prosperity of an organism in a given habitat depends on a complex of ecological factors. For each factor there is a range of tolerance beyond which the organism is not able to exist. The impossibility of prosperity or the absence of an organism is determined by those factors whose values approach or go beyond tolerance.
limiting we will consider such a factor for which, in order to achieve a given (small) relative change in the response function, a minimum relative change in this factor is required. If a
then the limiting factor will be Xl, that is, the limiting factor is the one along which the gradient of the response function is directed.
It is obvious that the gradient is directed along the normal to the boundary of the tolerance region. And for the limiting factor, there are more chances, all other things being equal, to go beyond the tolerance area. That is, the limiting factor is the one whose value is closest to the lower limit of the tolerance interval. This concept is known as " law of the minimum " Liebig.
The idea that the endurance of an organism is determined by the weakest link in the chain of its ecological needs was first clearly shown in 1840. organic chemist J. Liebig, one of the founders of agricultural chemistry, who put forward theory of mineral nutrition of plants. He was the first to start studying the influence of various factors on plant growth, establishing that crop yields are often limited by nutrients that are not required in large quantities, such as carbon dioxide and water, since these substances are usually present in the environment in in abundance, but those that are required in the smallest quantities, for example, zinc, boron or iron, which are very few in the soil. Liebig's conclusion that "the growth of a plant depends on that element of nutrition which is present in the minimum amount" became known as Liebig's "Law of the Minimum".
After 70 years, the American scientist W. Shelford showed that not only a substance present in a minimum can determine the yield or viability of an organism, but also an excess of some element can lead to undesirable deviations. For example, an excess of mercury in the human body in relation to a certain norm causes severe functional disorders. With a lack of water in the soil, the assimilation of mineral nutrition elements by the plant is difficult, but an excess of water leads to similar consequences: it is possible for the roots to suffocate, the occurrence of anaerobic processes, the acidification of the soil, etc. Excess and lack of pH in the soil also reduces the yield in a given location. According to W. Shelford, factors present both in excess and in deficiency are called limiting, and the corresponding rule is called the law of the "limiting factor" or " the law of tolerance ".
The law of the limiting factor is taken into account in measures to protect the environment from pollution. Exceeding the norm of harmful impurities in the air and water poses a serious threat to human health.
We can formulate a number of auxiliary principles that complement the "law of tolerance":
1. Organisms can have a wide range of tolerance for one factor and a narrow range for another.
2. Organisms with a wide range of tolerance to all factors are usually the most widely distributed.
3. If the conditions for one environmental factor are not optimal for the species, then the range of tolerance to other environmental factors may narrow.
4. In nature, organisms very often find themselves in conditions that do not correspond to the optimal range of one or another environmental factor, determined in the laboratory.
5. The breeding season is usually critical; during this period, many environmental factors often become limiting. The tolerance limits for breeding individuals, seeds, embryos and seedlings are usually narrower than for non-breeding adult plants or animals.
The actual limits of tolerance in nature are almost always narrower than the potential range of activity. This is due to the fact that the metabolic costs of physiological regulation at extreme values of the factors narrow the range of tolerance. As conditions approach extremes, adaptation becomes increasingly costly and the body less and less protected from other factors such as disease and predators.
1.1.4. Some basic abiotic factors
Abiotic factors of the terrestrial environment . The abiotic component of the terrestrial environment is a set of climatic and soil-ground factors, consisting of many dynamic elements that affect both each other and living beings.
The main abiotic factors of the terrestrial environment are as follows:
1) Radiant energy coming from the sun (radiation). It propagates in space in the form of electromagnetic waves. Serves as the main source of energy for most processes in ecosystems. On the one hand, the direct effect of light on protoplasm is fatal to the organism, on the other hand, light serves as the primary source of energy, without which life is impossible. Therefore, many morphological and behavioral characteristics of organisms are associated with the solution of this problem. Light is not only a vital factor, but also a limiting one, both at the maximum and at the minimum levels. About 99% of the total energy of solar radiation is rays with a wavelength of 0.17÷4.0 µm, including 48% is in the visible part of the spectrum with a wavelength of 0.4÷0.76 µm, 45% is in the infrared (wavelength from 0.75 µm to 1 mm) and about 7% - to ultraviolet (wavelength less than 0.4 microns). Infrared rays are of primary importance for life, and orange-red and ultraviolet rays play the most important role in the processes of photosynthesis.
2) Illumination of the earth's surface associated with radiant energy and determined by the duration and intensity of the light flux. Due to the rotation of the Earth, daylight and darkness alternate periodically. Illumination plays a crucial role for all living things and organisms are physiologically adapted to the change of day and night, to the ratio of dark and light periods of the day. Almost all animals have so-called circadian (diurnal) rhythms of activity associated with the change of day and night. In relation to light, plants are divided into light-loving and shade-tolerant.
3) Temperature on the surface of the globe is determined by the temperature regime of the atmosphere and is closely related to solar radiation. It depends both on the latitude of the area (the angle of incidence of solar radiation on the surface), and on the temperature of the incoming air masses. Living organisms can exist only within a narrow range of temperatures - from -200°C to 100°C. As a rule, the upper limit values of the factor are more critical than the lower ones. The range of temperature fluctuations in water is usually smaller than on land, and the range of temperature tolerance in aquatic organisms is usually narrower than that of the corresponding terrestrial animals. Thus, temperature is an important and very often limiting factor. Temperature rhythms, together with light, tidal and humidity rhythms, largely control the seasonal and diurnal activity of plants and animals. Temperature often creates zoning and stratification of habitats.
4) Atmospheric air humidity associated with its saturation with water vapor. The lower layers of the atmosphere are richest in moisture (up to a height of 1.5–2 km), where up to 50% of all moisture is concentrated. The amount of water vapor contained in the air depends on the temperature of the air. The higher the temperature, the more moisture the air contains. For each temperature there is a certain limit of saturation of air with water vapor, which is called maximum . The difference between the maximum and given saturation is called humidity deficiency (lack of saturation). Humidity deficiency - the most important environmental parameter, since it characterizes two quantities at once: temperature and humidity. It is known that an increase in moisture deficit in certain periods of the growing season contributes to increased fruiting of plants, and in a number of animals, such as insects, leads to reproduction up to the so-called "outbreaks". Therefore, many methods for predicting various phenomena in the world of living organisms are based on the analysis of the dynamics of moisture deficit.
5) Precipitation , closely related to air humidity, are the result of condensation of water vapor. Atmospheric precipitation and air humidity are of decisive importance for the formation of the water regime of the ecosystem and, thus, are among the most important imperative environmental factors, since water supply is the main condition for the life of any organism, from a microscopic bacterium to a giant sequoia. The amount of precipitation depends mainly on the paths and nature of the large movements of air masses, or the so-called "weather systems". The distribution of precipitation by season is an extremely important limiting factor for organisms. Precipitation - one of the links in the water cycle on Earth, and in their fallout there is a sharp unevenness, in connection with which they distinguish humid (wet) and arid (dry) zones. The maximum precipitation is in tropical forests (up to 2000 mm/year), the minimum is in deserts (0.18 mm/year). Zones with rainfall less than 250 mm/year are already considered dry. As a rule, uneven distribution of precipitation over the seasons occurs in the tropics and subtropics, where the wet and dry seasons are often well defined. In the tropics, this seasonal rhythm of humidity regulates the seasonal activity of organisms (especially reproduction) in much the same way that the seasonal rhythm of temperature and light regulates the activity of organisms in the temperate zone. In temperate climates, precipitation is usually distributed more evenly over the seasons.
6) Gas composition of the atmosphere . Its composition is relatively constant and includes mainly nitrogen and oxygen with an admixture of a small amount of CO 2 and argon. Other gases - in trace amounts. In addition, the upper atmosphere contains ozone. Usually in the atmospheric air there are solid and liquid particles of water, oxides of various substances, dust and smoke. Nitrogen - the most important biogenic element involved in the formation of protein structures of organisms; oxygen , mainly coming from green plants, provides oxidative processes; carbon dioxide (СО 2) is a natural damper of solar and reciprocal terrestrial radiation; ozone performs a shielding role in relation to the ultraviolet part of the solar spectrum, which is detrimental to all living things. Impurities of the smallest particles affect the transparency of the atmosphere, prevent the passage of sunlight to the surface of the Earth. The concentrations of oxygen (21% by volume) and CO2 (0.03% by volume) in the modern atmosphere are to some extent limiting for many higher plants and animals.
7) Movement of air masses (wind) . The reason for the occurrence of wind is the pressure drop caused by uneven heating of the earth's surface. The wind flow is directed in the direction of lower pressure, that is, where the air is warmer. The force of the Earth's rotation affects the circulation of air masses. In the surface layer of air, their movement affects all meteorological elements of the climate: temperature, humidity, evaporation from the Earth's surface, and plant transpiration. Wind - the most important factor in the transfer and distribution of impurities in the atmospheric air. The wind performs an important function of transporting matter and living organisms between ecosystems. In addition, the wind has a direct mechanical effect on vegetation and soil, damaging or destroying plants and destroying the soil cover. Such wind activity is most typical for open flat areas of land, seas, coasts and mountainous regions.
8) atmospheric pressure . Pressure cannot be called a limiting factor of direct action, although some animals undoubtedly react to its changes; however, pressure is directly related to weather and climate, which have a direct limiting effect on organisms.
Abiotic soil cover factors . Soil factors are clearly endogenous, since the soil is not only a factor of the environment surrounding organisms, but also a product of their vital activity. The soil - this is the framework, the foundation on which almost any ecosystem is built.
The soil - the final result of the action of climate and organisms, especially plants, on the parent rock. Thus, the soil consists of the source material - the underlying mineral substrate and organic component, in which organisms and their metabolic products are mixed with finely divided and modified source material. The gaps between the particles are filled with gases and water. texture and soil porosity are the most important characteristics that largely determine the availability of biogenic elements to plants and soil animals. In the soil, the processes of synthesis, biosynthesis are carried out, various chemical reactions of transformation of substances occur, associated with the vital activity of bacteria.
1.1.5. Biotic factors
Under biotic factors understand the totality of the influences of the life activity of some organisms on others.
The relationship between animals, plants, microorganisms (they are also called co-shares ) are extremely diverse. They can be divided into straight and indirect, are mediated through change by their presence of appropriate abiotic factors.
The interactions of living organisms are classified in terms of their reaction to each other. In particular, they highlight homotypic reactions between interacting individuals of the same species and heterotypic reactions during coactions between individuals of different species.
One of the most important biotic factors is food (trophic) factor . The trophic factor is characterized by the quantity, quality and availability of food. Any kind of animal or plant has a clear selectivity to the composition of food. Distinguish types monophages that feed on only one species, polyphages , feeding on several species, as well as species feeding on a more or less limited range of food, called wide or narrow oligophages .
Relationships between species are naturally necessary. Cannot be divided into enemies and them victims because the relationships between species are mutually reversible. Disappearance² victims² can lead to extinction ² enemy².
Communities) with each other and with the environment. This term was first proposed by the German biologist Ernst Haeckel in 1869. As an independent science, it stood out at the beginning of the 20th century along with physiology, genetics and others. The scope of ecology is organisms, populations and communities. Ecology considers them as a living component of a system called an ecosystem. In ecology, the concepts of population - communities and ecosystems have clear definitions.
A population (in terms of ecology) is a group of individuals of the same species, occupying a certain territory and, usually, to some extent 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 relationships.
An ecosystem is a community of organisms with their environment interacting with each other and forming an ecological unit.
All ecosystems of the Earth are combined into or 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 the study of ecosystems are possible.
Ecosystem Approach.With the ecosystem approach, the ecologist studies the flow of energy in the ecosystem as well. 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 interconnections in an ecosystem and give recommendations for rational nature management.
Community studies. With this approach, the species composition of communities and the factors that limit 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 implies, is the population.
Habitat research. In this case, a relatively homogeneous area of the environment where the given organism lives is studied. Separately, as an independent line of research, it is usually not used, but it provides the necessary material for understanding the ecosystem as a whole.
It should be noted that all the approaches listed above should ideally be applied in combination, but at the moment this is practically impossible due to the large 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.
Ecological research methods:
- observation
- experiment
- population count
- simulation method
We begin our acquaintance with ecology, perhaps, with one of the most developed and studied sections - autecology. The attention of 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 ecological factor, that is, the environmental factor that affects the body.
No environmental protection measures are possible without studying the optimum effect of one or another factor on a given biological species. In fact, how to protect this or that species, if you do not know what living conditions he prefers. Even the "protection" of such a species as a reasonable person requires knowledge of sanitary and hygienic standards, which are nothing more than the optimum of various environmental factors in relation to a person.
The influence of the environment on the body is called the environmental factor. The exact scientific definition is:
ECOLOGICAL FACTOR - any environmental condition to which the living reacts with adaptive reactions.
An environmental factor is any element of the environment that has a direct or indirect effect on living organisms at least during 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 wildlife.
anthropogenic factors - influences caused by reasonable and unreasonable human activity ("anthropos" - a person).
Man modifies animate 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 with carbon dioxide). Therefore, anthropogenic factors in terms of scope and global impact are approaching geological forces.
Not infrequently, environmental factors are also subjected to a more detailed classification, when it is necessary to point to a specific group of factors. For example, there are climatic (relating to climate), edaphic (soil) environmental factors.
As a textbook example of the indirect action of environmental factors, the so-called bird colonies, 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, an increased concentration of minerals leads to an increase in the number of algae, and after them - zooplankton. The lower crustaceans included in the zooplankton are fed by fish, and the birds inhabiting the bird rookery feed on fish. The chain closes. Bird droppings act as an environmental factor that indirectly increases the number of bird colonies.
How to compare the action of factors so different in nature? Despite the huge number of factors, from the very definition of the environmental factor as an element of the environment that affects the body, something in common follows. Namely: the action of environmental factors is always expressed in a change in the vital activity of organisms, and in the end, it leads to a change in the size of the population. This makes it possible to compare the effect 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 the light of the above, and even simple life experience, it becomes obvious that the effect is determined precisely by the dose of the factor. Indeed, what is the factor "temperature"? This is quite an abstraction, but if you say that the temperature is -40 Celsius - there is no time for abstractions, it would be better to wrap yourself 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 the minimum, maximum and optimal doses, as well as those values at which the life of an individual stops (they are called lethal, or lethal).
The effect of various doses on the population as a whole is very clearly described graphically:
The ordinate axis plots the population size depending on the dose of one or another factor (abscissa axis). The optimal doses of the factor and the doses of the action of the factor are distinguished, at which the inhibition of the vital activity of the given organism occurs. On the graph, this corresponds to 5 zones:
optimum zone
to the right and left of it are the pessimum zones (from the border of the optimum zone to max or min)
lethal zones (beyond max and min) where the population is 0.
The range of values of the factor, beyond which the normal life 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, the next lesson will focus on the ecological groups of organisms, as well as the Liebig barrel and how all this is related to the definition of MPC.
Glossary
FACTOR ABIOTIC - 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 - a set of organisms that live in the water column and are unable to actively resist the transfer of currents, that is, "floating" in the water.
BIRD MARKET - a colonial settlement of birds associated with the aquatic environment (guillemots, gulls).
What ecological factors out of all their variety does the researcher pay attention to first of all? Not infrequently, a researcher is faced with the task of identifying those environmental factors that inhibit the vital activity of representatives of a given population, limit growth and development. For example, it is necessary to find out the reasons for the decline in the yield or the reasons for the extinction of the natural population.
With all the variety 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 are of unequal significance. Back in the 19th century, Liebig (Liebig, 1840), studying the effect of various microelements on plant growth, established that plant growth is limited by the element whose concentration is at a minimum. The deficient factor was called the limiting factor. Figuratively, this position helps to present the so-called "Liebig's barrel".
Liebig barrel
Imagine a barrel with wooden slats on the sides of different heights, as shown in the picture. It is clear, no matter how high the other slats are, but you can pour water into the barrel exactly as much as the length of the shortest slat (in this case, 4 dies).
It remains only 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 rails will indicate the degree of deviation of the dose of one or another factor from the optimum.
At present Liebig's law of the minimum is interpreted more widely. A limiting factor can be a factor that is not only in short supply, but also in excess.
The environmental factor plays the role of a LIMITING FACTOR if this factor is below the 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 content of phosphates in sea water is a limiting factor that determines the development of plankton and the overall productivity of communities.
The concept of "limiting factor" applies not only to various elements, but to all environmental factors. Competitive relations often act as a limiting factor.
Each organism has its own 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 endure a wide range of intensity of various environmental factors. For example, the habitat of a fox is from the forest-tundra to the steppes. Stenobionts, on the contrary, endure only very narrow fluctuations in the intensity of the environmental factor. For example, almost all tropical rainforest plants are stenobionts.
It is not uncommon to indicate which factor is meant. So, we can talk about eurythermal (tolerating large temperature fluctuations) organisms (many insects) and stenothermal (for tropical forest plants, temperature fluctuations within +5 ... +8 degrees C can be fatal); eury / stenohaline (tolerating / not tolerating fluctuations in water salinity); evry / stenobats (living in wide / narrow limits of the depth of the 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.
With the independent action of environmental factors, it is sufficient to operate with the concept of "limiting factor" in order to determine the combined effect of a complex of environmental factors on a given organism. However, in real conditions, environmental factors can enhance or weaken each other. For example, frost in the Kirov region is easier to bear than in St. Petersburg, since the latter has higher humidity.
Accounting for the interaction of environmental factors is an important scientific problem. There are three main types of interaction factors:
additive - the interaction of factors is a simple algebraic sum of the effects of each of the factors with an independent action;
synergistic - the joint action of factors enhances the effect (that is, the effect of their joint action is greater than the simple sum of the effects of each factor with independent action);
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 important to know about the interaction of environmental factors? The theoretical substantiation of the value of maximum permissible concentrations (MPC) of pollutants or maximum permissible levels (MPL) of the impact of polluting agents (for example, noise, radiation) is based on the law of the limiting factor. MPC is set experimentally at a level at which pathological changes do not yet occur in the body. At the same time, there are difficulties (for example, most often it is necessary to extrapolate data obtained on animals to humans). However, this is not about them.
It is not uncommon to hear how 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 Supervision authorities state an increased level of respiratory diseases in children. The explanation could be like this. It is no secret that many air pollutants have a similar effect: they irritate the mucous membranes of the upper respiratory tract, provoke respiratory diseases, etc. And the joint action of these pollutants gives an additive (or synergistic) effect.
Therefore, ideally, when developing MPC standards and assessing the existing environmental situation, the interaction of factors should be taken into account. Unfortunately, in practice this can be very difficult to do: it is difficult to plan such an experiment, it is difficult to evaluate the interaction, plus the tightening of MPCs has negative economic effects.
Glossary
MICROELEMENTS - chemical elements necessary for organisms in negligible quantities, but determining the success of their development. M. in the form of microfertilizers is used to increase the yield of plants.
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) consistent consumption, transformation, use, accumulation and loss of substances and energy in living organisms. Life is possible only through metabolism.
eurybiont - an organism that lives in various environmental conditions
STENOBIONT - an organism that requires strictly defined conditions of existence.
XENOBIOTIC - a chemical substance alien 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 the enterprises of the city, heating and lighting of the apartments of the townspeople are located outside the city. These are deposits of oil, gas, coal, hydro and nuclear power plants.
The city consumes a huge amount of water, only a small part of which a person uses for direct consumption. The main part of the water is spent on production processes and domestic needs. Personal water consumption in cities ranges from 150 to 500 liters per day, and taking into account industry, one citizen accounts for up to 1000 liters per day. Water used by cities returns to nature in a polluted state - it is saturated with heavy metals, oil residues, complex organic substances like phenol, etc. It may contain pathogens. The city emits toxic gases and dust into the atmosphere, concentrates toxic waste in landfills, which, with spring water flows, enter aquatic ecosystems. 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 purify the atmosphere from harmful gases and dust that enter it during the operation of industrial enterprises and transport. Plants are also of great aesthetic and decorative value.
Animals in the city are represented not only by species common in natural ecosystems (birds live in 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 includes 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 the 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 the ecological balance is disturbed in them. All processes of regulating the flow of matter and energy a person has to take over. A person must regulate both the consumption of energy and resources by the city - raw materials for industry and food for people, and the amount of toxic waste entering the atmosphere, water and soil as a result of industry and transport. Finally, it also determines the size of these ecosystems, which in developed countries, and in recent years in Russia, are rapidly “spreading” due to suburban cottage construction. Low-rise areas reduce the area of forests and agricultural land, their "spreading" requires the construction of new highways, which reduces the proportion of ecosystems capable of producing food and cycling oxygen.
Industrial pollution of the environment.
In urban ecosystems, industrial pollution is the most dangerous for nature.
Chemical pollution of the atmosphere. This factor is one of the most dangerous for human life. The most common contaminants
Sulfur dioxide, nitrogen oxides, carbon monoxide, chlorine, etc. In some cases, two or relatively several relatively harmless substances released into the atmosphere can form toxic compounds under the influence of sunlight. Ecologists number about 2,000 air pollutants.
The main sources of pollution are thermal power plants. Boiler houses, oil refineries and vehicles also heavily pollute the atmosphere.
Chemical pollution of water bodies. Enterprises dump oil products, nitrogen compounds, phenol and many other industrial wastes into water bodies. During oil production, water bodies are polluted with saline species, oil and oil products are also spilled during transportation. In Russia, the lakes of the North of Western Siberia suffer the most from oil pollution. In recent years, the danger to aquatic ecosystems of domestic wastewater from urban sewers has increased. In these effluents, the concentration of detergents has increased, which microorganisms decompose with difficulty.
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.
The water becomes undrinkable and dangerous to humans. Polluted water is not suitable for many industries.
Pollution of the soil surface with solid waste. City dumps of industrial and household waste occupy large areas. Garbage may contain toxic substances such as mercury or other heavy metals, chemical compounds that dissolve in rain and snow water and then enter water bodies and groundwater. Can get into garbage and devices containing radioactive substances.
The surface of the soil can be polluted by ash deposited from the smoke of coal-fired thermal power plants, cement factories, refractory bricks, etc. To prevent this contamination, special dust collectors are installed on the pipes.
Chemical pollution 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 washing out of toxic substances by rain and snow water from industrial landfills. Groundwater pollution also occurs during oil production using modern methods, when, in order to increase the return of oil reservoirs, salt water is re-injected into the wells, which has risen to the surface along with the oil during its pumping.
Salt water enters the aquifers, the water in the wells becomes bitter and undrinkable.
Noise pollution. The source of noise pollution can be an industrial enterprise or transport. Especially heavy dump trucks and trams produce a lot of 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 should be moved from the central parts of cities to sparsely populated areas and green spaces should be created around them that absorb noise well.
Planes should not fly over cities.
Noise is measured in decibels. Clock ticking - 10 dB, whisper - 25, noise from a busy highway - 80, aircraft takeoff noise - 130 dB. The pain threshold of noise is 140 dB. On the territory of residential development during the day, the noise should not exceed 50-66 dB.
Also, pollutants include: contamination of the soil surface with overburden and ash dumps, biological pollution, thermal pollution, radiation pollution, electromagnetic pollution.
Air pollution. If air pollution over the ocean is taken 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 benz-a-pyrene, nitrogen dioxide, formaldehyde, and dust. In the European part of Russia and the Urals, on average, during the year per 1 sq. km. km, more than 450 kg of atmospheric pollutants fell.
Compared to 1980, the amount of sulfur dioxide emissions increased by 1.5 times; 19 million tons of atmospheric pollutants were thrown into the atmosphere by road transport.
Wastewater discharge into rivers amounted to 68.2 cubic meters. km with a post-consumption of 105.8 cubic meters. km. Water consumption by industry 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 air pollutants from its western neighbors than it sends to them.
Acid rains have negatively affected half of the forests of Europe, and the process of drying out of forests has begun in Russia as well. In Scandinavia, 20,000 lakes have already died due to acid rain coming from the UK and Germany. Under the influence of acid rain, architectural monuments are dying.
Harmful substances coming out of a chimney 100 m high are dispersed within a radius of 20 km, 250 m high - 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.
Ozone-depleting chlorofluorocarbons (CFCs) enter the atmosphere from cooling system gases (in the US - 48%, and in other countries - 20%), from the use of aerosol cans (in the USA - 2%, and a few years ago their sale was banned; in other countries - 35%), solvents used in dry cleaning (20%) and in the production of foams, including styroform (25-
The main source of freons that destroy the ozone layer are industrial refrigerators - refrigerators. In an ordinary household refrigerator, 350 g of freon, and in industrial refrigerators - tens of kilograms. Refrigeration only in
Moscow annually uses 120 tons of freon. A significant part of it, due to the imperfection of the equipment, ends up in the atmosphere.
Pollution of freshwater ecosystems. In 1989, 1.8 tons of phenols, 69.7 tons of sulfates, 116.7 tons of synthetic surface-active substances (surfactants) were discharged into Lake Ladoga - a reservoir of drinking water for the six millionth St. Petersburg - in 1989.
Pollutes aquatic ecosystems and river transport. On Lake Baikal, for example, 400 ships of various sizes float, they dump about 8 tons of oil products into the water per year.
At most Russian enterprises, toxic production wastes are either dumped into water bodies, poisoning them, or accumulated without processing, often in huge quantities. These accumulations of deadly waste can be called "environmental mines"; when dams break, they can end up in water bodies. An example of such an "environmental mine" is the Cherepovets chemical plant "Ammophos". Its septic tank covers an area of 200 hectares and contains 15 million tons of waste. The dam that encloses the sump is raised annually by
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 lack drinking water.
Pollution of marine ecosystems. About 20 billion tons of garbage have been dumped into the World Ocean - from domestic sewage to radioactive waste. Every year for every 1 sq. km of the water surface add another 17 tons of garbage.
More than 10 million tons of oil is poured into the ocean every year, which forms a film covering 10-15% of its surface; and 5 g of petroleum products is enough to tighten the film 50 square meters. m of water surface. This film not only reduces the evaporation and absorption of carbon dioxide, but also causes oxygen starvation and the death of eggs and young fish.
Radiation pollution. It is assumed that by the year 2000 the world will have accumulated
1 million cubic meters m of high-level radioactive waste.
The 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 lifetime, 73% of which comes from the radiation of natural bodies (for example, granite in monuments, house cladding, etc.), 14% from medical procedures (primarily from visiting an X-ray room) and 14% - on cosmic rays. Over a lifetime (70 years), a person can, without much risk, gain radiation of 35 rem (7 rem from natural sources, 3 rem from space sources and x-ray machines). In the zone of the Chernobyl nuclear power plant in the most polluted areas, you can get up to 1 rem per hour. The radiation power on the roof during the period of extinguishing a fire at a nuclear power plant reached 30,000 roentgens per hour, and therefore, without radiation protection (a lead suit), a lethal dose of radiation could be obtained in 1 minute.
The hourly dose of radiation, lethal to 50% of organisms, is 400 rem for humans, 1000-2000 rem for fish and birds, from 1000 to 150,000 for plants, and 100,000 rem for insects. Thus, the strongest pollution is not a hindrance to the mass reproduction of insects. Of the plants, trees are the least resistant to radiation and grasses are the most resistant.
Pollution with household waste. The amount of accumulated garbage is constantly growing. Now it is from 150 to 600 kg per year for every city dweller. Most of the 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.
In order 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 - chemical. There are three main ways to reduce the harm from them.
Dilution. Even treated effluents must be diluted 10 times (and untreated - 100-200 times). High chimneys are built at enterprises so that the emitted gases and dust are dispersed evenly. Dilution is an ineffective way to reduce the harm from pollution, acceptable only 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 treatment, a lot of concentrated liquid and solid wastes are generated, which also have to be stored.
Replacing old technologies with new low-waste technologies. Due to deeper processing, it is possible to reduce the amount of harmful emissions by dozens of times. Waste from one industry becomes raw material for another.
Figurative names for these three ways to reduce environmental pollution were given by German ecologists: “lengthen 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 the waste of industrial giants was dumped. This was done only in the 80s, when, finally, "the pipe was tied in a knot."
The level of environmental pollution in Russia is still very high, and an ecologically unfavorable situation dangerous for the health of the population 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 reduction of emissions of toxic substances into the environment can be achieved if less hazardous low-waste technologies are introduced. However, in order to “tie the pipe in a knot”, it is necessary to upgrade equipment at enterprises, which requires very large investments and therefore will be carried out gradually.
Cities and industrial facilities (oil fields, quarries for the development of coal and ore, chemical and metallurgical plants) operate on the energy that comes from other industrial ecosystems (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 is not found in nature.
The problems of urban ecology are, first of all, the 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 an important role in mitigating the impact 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 citizens.
Literature:
Mirkin B.M., Naumova L.G. Ecology of Russia. A textbook from the federal set for grades 9-11 of a comprehensive school. Ed. 2nd, revised.
And extra. - M.: AO MDS, 1996. - 272 with ill.
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