Environmental environmental factors
Test on the topic “Ecological environmental factors”
Choose one correct answer:
1.What abiotic factor can lead to a sharp decline in the population of the river beaver?
1) heavy rains in summer
2) increase in the number of aquatic plants
3) drying up of the reservoir
4) intensive shooting of animals
(correct answer: 3)
2. What anthropogenic factor can lead to an increase in the population of hares in the forest?
1) cutting down trees
2) shooting wolves and foxes
3) trampling of plants
4) making fires
(Correct answer: 2)
3. What environmental factor serves as a signal for birds to prepare for migration?
1) decrease in air temperature
2) change in daylight hours
3) increase in cloudiness
4) change in atmospheric pressure
(correct answer: 2)
4.The greenhouse effect can contribute to the rapid development of plants in the biosphere, as it leads
1) to the accumulation of oxygen in the atmosphere
2) to increase the transparency of the atmosphere
3) to an increase in atmospheric density
4) to the accumulation of carbon dioxide in the atmosphere
(correct answer: 1)
5. All factors of living and inanimate nature that affect individuals, populations, species are called
1) abiotic
2) biotic
3) environmental
4) anthropogenic
(correct answer: 3)
6. Abiotic factors include
1) boars tearing up roots
2) locust invasion
3) formation of bird colonies
4) heavy snowfall
(correct answer: 4)
7.Food connections in an ecosystem are called
1) abiotic
2) anthropogenic
3) limiting
4) biotic
(correct answer: 4)
8.Factors causing environmental pollution
associated with human activities are called
1) limiting
2) anthropogenic
3) biotic
4) abiotic
(correct answer: 2)
9.What factors are called anthropogenic?
1) related to human activities
2) abiotic nature
3) biotic nature
4) determining the functioning of agrocenoses
(correct answer: 1)
10. The biotic components of the ecosystem include
1) gas composition of the atmosphere
2) composition and structure of the soil
3) climate and weather features
4) producers, consumers, decomposers
(correct answer: 4)
Choose one correct answer
Question 1. Environmental conditions are usually defined as:
1. environmental factors that influence (positive or negative) the existence and geographical distribution of living beings;
2. changes in environment-forming components or their combinations, which have an oscillatory nature with the restoration of previous living conditions;
3. the degree of compliance of natural conditions with the needs of people or other living organisms;
4. balance of natural or human-modified environment-forming components and natural processes;
5. the addition of natural and anthropogenic factors, which together create new ecological conditions for the habitat of organisms and biotic communities.
(correct answer: 1)
Question 2. What definition corresponds to the concept of “abiotic environmental factors”:
1. components and phenomena of inanimate, inorganic nature, directly or indirectly affecting living organisms;
2. natural bodies and phenomena with which the organism is in direct or indirect relationships;
3. a change in the environment-forming components or their combinations, which cannot be compensated during natural restoration processes;
4. factors that have both direct and indirect effects on organisms;
5. relationships between species, in which organisms of one species live off the nutrients of other species.
(correct answer: 1)
Question 3. Biotic environmental factors are:
1. the totality of influences of the life activity of some organisms on the life activity of others, as well as on the inanimate environment;
2. physiological and ecological adaptation of organisms, ensuring a high level of metabolism during the period of animal activity and low energy losses during hibernation;
3. the relationship between the energy received by the body from the outside and its expenditure on the construction of the body and vital processes;
4. environmental factors that have the greatest impact on the number and vital activity of organisms.
5. forces and natural phenomena, the origin of which is not directly related to the life activity of living organisms.
(correct answer: 1)
Question 4. Anthropogenic factors are:
1. forms of human activity that affect the natural environment, changing the living conditions of living organisms;
2. the totality of influences of the life activity of some organisms on the life activity of others, as well as on the inanimate environment;
3. a set of natural features of the existence of organisms and anthropogenic influences;
4. a group of factors associated with both direct and indirect influence of living organisms on the environment;
5. factors that ensure a high level of metabolism during the period of animal activity and low energy losses during hibernation.
(correct answer: 1)
Question 5: The construction of a dam can be considered an example of a factor:
1. abiotic;
2. biotic;
3. anthropogenic;
4. not environmentally friendly at all;
5. hydrobiont.
(correct answer: 3)
B 4. Establish a correspondence between the characteristics of the environment and its factor
ENVIRONMENTAL FACTORS
A) biotic
B) abiotic
CHARACTERISTIC
1) constancy of the gas composition of the atmosphere
2) change in the thickness of the ozone screen
3) change in air humidity
4) change in the number of consumers
5) change in the number of producers
(correct answer: A-4,5,6. B-1,2,3.)
Q 6. Establish the sequence in which the levels of organization of living things are located:
A) biocenotic
B) species
B) population
D) biogeocenotic
D) organismic
E) biosphere
(correct answer:D, B, C, A, D, E.)
C 3. Read the text and find sentences in it that contain biological errors. First write down the numbers of these sentences, and then formulate them correctly.
1. All environmental factors acting on organisms are divided into biotic, geological and anthropogenic.
2. Biotic factors are temperature, climatic conditions, humidity, light.
3. Anthropogenic factors - the influence of humans and the products of their activities on the environment.
4. The factor whose value is currently within the limits of endurance and deviates to the greatest extent from the optimal value is called limiting.
5. Mutualism is a form of mutually negative interactions between organisms.
Answers:
1-on Abiotic, Biotic and Anthropogenic.
3 is correct
4 is correct
5-mutually positive interactions (mutually beneficial relationships between individuals)
Environmental factors is a complex of environmental conditions affecting living organisms. Distinguish inanimate factors— abiotic (climatic, edaphic, orographic, hydrographic, chemical, pyrogenic), wildlife factors— biotic (phytogenic and zoogenic) and anthropogenic factors (impact of human activity). Limiting factors include any factors that limit the growth and development of organisms. The adaptation of an organism to its environment is called adaptation. The external appearance of an organism, reflecting its adaptability to environmental conditions, is called life form.
The concept of environmental environmental factors, their classification
Individual components of the environment that affect living organisms, to which they respond with adaptive reactions (adaptations), are called environmental factors, or ecological factors. In other words, the complex of environmental conditions affecting the life of organisms is called environmental environmental factors.
All environmental factors are divided into groups:
1. include components and phenomena of inanimate nature that directly or indirectly affect living organisms. Among the many abiotic factors, the main role is played by:
- climatic(solar radiation, light and light conditions, temperature, humidity, precipitation, wind, atmospheric pressure, etc.);
- edaphic(mechanical structure and chemical composition of the soil, moisture capacity, water, air and thermal conditions of the soil, acidity, humidity, gas composition, groundwater level, etc.);
- orographic(relief, slope exposure, slope steepness, elevation difference, altitude above sea level);
- hydrographic(water transparency, fluidity, flow, temperature, acidity, gas composition, content of mineral and organic substances, etc.);
- chemical(gas composition of the atmosphere, salt composition of water);
- pyrogenic(exposure to fire).
2. - the totality of relationships between living organisms, as well as their mutual influences on the habitat. The effect of biotic factors can be not only direct, but also indirect, expressed in the adjustment of abiotic factors (for example, changes in soil composition, microclimate under the forest canopy, etc.). Biotic factors include:
- phytogenic(the influence of plants on each other and on the environment);
- zoogenic(the influence of animals on each other and on the environment).
3. reflect the intense influence of humans (directly) or human activities (indirectly) on the environment and living organisms. Such factors include all forms of human activity and human society that lead to changes in nature as a habitat for other species and directly affect their lives. Every living organism is influenced by inanimate nature, organisms of other species, including humans, and in turn has an impact on each of these components.
The influence of anthropogenic factors in nature can be either conscious, accidental, or unconscious. Man, plowing virgin and fallow lands, creates agricultural land, breeds highly productive and disease-resistant forms, spreads some species and destroys others. These influences (conscious) are often negative, for example, the thoughtless resettlement of many animals, plants, microorganisms, the predatory destruction of a number of species, environmental pollution, etc.
Biotic environmental factors are manifested through the relationships of organisms belonging to the same community. In nature, many species are closely interrelated, and their relationships with each other as components of the environment can be extremely complex. As for the connections between the community and the surrounding inorganic environment, they are always two-way, reciprocal. Thus, the nature of the forest depends on the corresponding type of soil, but the soil itself is largely formed under the influence of the forest. Similarly, temperature, humidity and light in the forest are determined by vegetation, but the prevailing climatic conditions in turn affect the community of organisms living in the forest.
Impact of environmental factors on the body
The impact of the environment is perceived by organisms through environmental factors called environmental. It should be noted that the environmental factor is only a changing element of the environment, causing in organisms, when it changes again, adaptive ecological and physiological reactions that are hereditarily fixed in the process of evolution. They are divided into abiotic, biotic and anthropogenic (Fig. 1).
They name the entire set of factors in the inorganic environment that influence the life and distribution of animals and plants. Among them there are: physical, chemical and edaphic.
Physical factors - those whose source is a physical state or phenomenon (mechanical, wave, etc.). For example, temperature.
Chemical factors- those that originate from the chemical composition of the environment. For example, water salinity, oxygen content, etc.
Edaphic (or soil) factors are a set of chemical, physical and mechanical properties of soils and rocks that affect both the organisms for which they are a habitat and the root system of plants. For example, the influence of nutrients, humidity, soil structure, humus content, etc. on plant growth and development.
Rice. 1. Scheme of the impact of the habitat (environment) on the body
— human activity factors affecting the natural environment (hydrosphere, soil erosion, forest destruction, etc.).
Limiting (limiting) environmental factors These are factors that limit the development of organisms due to a lack or excess of nutrients compared to the need (optimal content).
Thus, when growing plants at different temperatures, the point at which maximum growth occurs will be optimum. The entire temperature range, from minimum to maximum, at which growth is still possible is called range of stability (endurance), or tolerance. The points limiting it, i.e. the maximum and minimum temperatures suitable for life are the limits of stability. Between the optimum zone and the limits of stability, as it approaches the latter, the plant experiences increasing stress, i.e. we're talking about about stress zones, or zones of oppression, within the stability range (Fig. 2). As you move further down and up the scale from the optimum, not only does stress intensify, but when the limits of the body's resistance are reached, its death occurs.
Rice. 2. Dependence of the action of an environmental factor on its intensity
Thus, for each species of plant or animal there is an optimum, stress zones and limits of stability (or endurance) in relation to each environmental factor. When the factor is close to the limits of endurance, the organism can usually exist only for a short time. In a narrower range of conditions, long-term existence and growth of individuals is possible. In an even narrower range, reproduction occurs, and the species can exist indefinitely. Typically, somewhere in the middle of the resistance range there are conditions that are most favorable for life, growth and reproduction. These conditions are called optimal, in which individuals of a given species are the most fit, i.e. leave the greatest number of descendants. In practice, it is difficult to identify such conditions, so the optimum is usually determined by individual vital signs (growth rate, survival rate, etc.).
Adaptation consists in adapting the body to environmental conditions.
The ability to adapt is one of the main properties of life in general, ensuring the possibility of its existence, the ability of organisms to survive and reproduce. Adaptations manifest themselves at different levels - from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. All adaptations of organisms to existence in various conditions have been developed historically. As a result, groupings of plants and animals specific to each geographical zone were formed.
Adaptations may be morphological, when the structure of an organism changes until a new species is formed, and physiological, when changes occur in the functioning of the body. Closely related to morphological adaptations is the adaptive coloration of animals, the ability to change it depending on the light (flounder, chameleon, etc.).
Widely known examples of physiological adaptation are winter hibernation of animals, seasonal migrations of birds.
Very important for organisms are behavioral adaptations. For example, instinctive behavior determines the action of insects and lower vertebrates: fish, amphibians, reptiles, birds, etc. This behavior is genetically programmed and inherited (innate behavior). This includes: the method of building a nest in birds, mating, raising offspring, etc.
There is also an acquired command, received by an individual in the course of his life. Education(or learning) - the main way of transmitting acquired behavior from one generation to another.
The ability of an individual to manage his cognitive abilities to survive unexpected changes in his environment is intelligence. The role of learning and intelligence in behavior increases with the improvement of the nervous system—an increase in the cerebral cortex. For humans, this is the defining mechanism of evolution. The ability of species to adapt to a particular range of environmental factors is denoted by the concept ecological mystique of the species.
The combined effect of environmental factors on the body
Environmental factors usually act not one at a time, but in a complex manner. The effect of one factor depends on the strength of the influence of others. The combination of different factors has a noticeable impact on the optimal living conditions of the organism (see Fig. 2). The action of one factor does not replace the action of another. However, with the complex influence of the environment, one can often observe a “substitution effect”, which manifests itself in the similarity of the results of the influence of different factors. Thus, light cannot be replaced by excess heat or an abundance of carbon dioxide, but by influencing temperature changes, it is possible to stop, for example, plant photosynthesis.
In the complex influence of the environment, the impact of various factors on organisms is unequal. They can be divided into main, accompanying and secondary. The leading factors are different for different organisms, even if they live in the same place. The role of a leading factor at different stages of an organism’s life can be played by one or another element of the environment. For example, in the life of many cultivated plants, such as cereals, the leading factor during the germination period is temperature, during the heading and flowering period - soil moisture, and during the ripening period - the amount of nutrients and air humidity. The role of the leading factor may change at different times of the year.
The leading factor may be different for the same species living in different physical and geographical conditions.
The concept of leading factors should not be confused with the concept of. A factor whose level in qualitative or quantitative terms (deficiency or excess) turns out to be close to the limits of endurance of a given organism, called limiting. The effect of the limiting factor will also manifest itself in the case when other environmental factors are favorable or even optimal. Both leading and secondary environmental factors can act as limiting factors.
The concept of limiting factors was introduced in 1840 by the chemist 10. Liebig. Studying the influence of the content of various chemical elements in the soil on plant growth, he formulated the principle: “The substance found in the minimum controls the yield and determines the size and stability of the latter over time.” This principle is known as Liebig's law of the minimum.
The limiting factor can be not only a deficiency, as Liebig pointed out, but also an excess of factors such as, for example, heat, light and water. As noted earlier, organisms are characterized by ecological minimums and maximums. The range between these two values is usually called the limits of stability, or tolerance.
In general, the complexity of the influence of environmental factors on the body is reflected by V. Shelford’s law of tolerance: the absence or impossibility of prosperity is determined by a deficiency or, conversely, an excess of any of a number of factors, the level of which may be close to the limits tolerated by a given organism (1913). These two limits are called tolerance limits.
Numerous studies have been carried out on the “ecology of tolerance”, thanks to which the limits of existence of many plants and animals have become known. Such an example is the effect of air pollutants on the human body (Fig. 3).
Rice. 3. The influence of air pollutants on the human body. Max - maximum vital activity; Additional - permissible vital activity; Opt is the optimal (not affecting vital activity) concentration of a harmful substance; MPC is the maximum permissible concentration of a substance that does not significantly change vital activity; Years - lethal concentration
The concentration of the influencing factor (harmful substance) in Fig. 5.2 is indicated by the symbol C. At concentration values of C = C years, a person will die, but irreversible changes in his body will occur at significantly lower values of C = C MPC. Consequently, the range of tolerance is limited precisely by the value C MPC = C limit. Hence, Cmax must be determined experimentally for each pollutant or any harmful chemical compound and its Cmax must not be exceeded in a specific habitat (living environment).
In protecting the environment, it is important upper limits of body resistance to harmful substances.
Thus, the actual concentration of the pollutant C actual should not exceed C maximum permissible concentration (C fact ≤ C maximum permissible value = C lim).
The value of the concept of limiting factors (Clim) is that it gives the ecologist a starting point when studying complex situations. If an organism is characterized by a wide range of tolerance to a factor that is relatively constant, and it is present in the environment in moderate quantities, then such a factor is unlikely to be limiting. On the contrary, if it is known that a particular organism has a narrow range of tolerance to some variable factor, then it is this factor that deserves careful study, since it may be limiting.
Definition
Ecology is the science of the relationships 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, follower of Charles Darwin, E. Haeckel.
Environmental objectives:
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).
Study of the composition and spatial structure of communities, the circulation of substances and energy in biosystems (community ecology, or ecosystem ecology).
Study of the interaction of individual taxonomic groups of organisms with the environment (plant ecology, animal ecology, microbial ecology, etc.).
Study of various ecosystems: aquatic (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.
Environmental calculations use methods of mathematical and computer modeling, and the method of statistical data analysis.
environmental factors
Environmental factors- environmental components that affect a living organism.
The existence of a particular species depends on a combination of many different factors. Moreover, for each type the significance of individual factors, as well as their combinations, are very specific.
Types of environmental factors:
Abiotic factors- factors of inanimate nature that directly or indirectly affect the body.
Examples: relief, temperature and humidity, light, current and wind.
Biotic factors- factors of living nature that affect the body.
Examples: microorganisms, animals and plants.
Anthropogenic factors- factors associated with human activities.
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 metabolism
hydratophytes - plants that constantly live in water;
hydrophytes - plants partially submerged in water;
helophytes - marsh plants;
hygrophytes - terrestrial plants that live in excessively moist places;
mesophytes - plants that prefer moderate moisture;
xerophytes - plants adapted to constant lack of moisture (including succulents--plants that accumulate water in the tissues of their bodies (for example, Crassulaceae and cacti);
sclerophytes are drought-resistant plants with tough, leathery leaves and stems.
edaphic (soil): soil mechanical composition, soil air permeability, soil acidity, soil chemical composition;
ECOLOGICAL GROUPS OF PLANTS
In relation to soil fertility The following ecological groups of plants are distinguished:
oligotrophs - plants of poor, infertile soils (Scots pine);
mesotrophs - plants with a moderate need for nutrients (most forest plants of temperate latitudes);
eutrophic plants - plants that require large amounts of nutrients in the soil (oak, hazel, gooseberry).
ECOLOGICAL GROUPS OF PLANTS
All plants in relation to the light 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 herbs).
Facultative heliophytes are shade-tolerant plants that can develop in both very high and low amounts of light (common spruce, Norway maple, hornbeam, hazel, hawthorn, strawberry, field geranium, many indoor plants).
The combination of various abiotic factors determines the distribution of species of organisms across different regions of the globe. A certain biological species is not found everywhere, but in areas where the conditions necessary for its existence exist.
phytogenic - influence of plants;
mycogenic - the influence of fungi;
zoogenic - the influence of animals;
microbiogenic - the influence of microorganisms.
ANTHROPOGENIC FACTORS
Although humans influence living nature through changes in abiotic factors and biotic relationships of species, human activity on the planet is of particular importance.
physical: use of nuclear energy, travel on trains and airplanes, the effects of noise and vibration;
chemical: the use of mineral fertilizers and pesticides, pollution of the Earth's shells with industrial and transport waste;
biological: food; organisms for which humans can be a habitat or source of food;
social - related to human 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: importation of plants and animals, reduction of habitats and destruction of species, direct impact on vegetation cover, plowing of land, cutting and burning of forests, grazing of domestic animals, mowing, drainage, irrigation and watering, air pollution, creation of garbage dumps and wastelands, creation of cultural phytocenoses. To this should be added various forms of crop and livestock farming activities, measures for plant protection, protection of rare and exotic species, animal hunting, their acclimatization, etc.
The influence of the anthropogenic factor has been constantly increasing since the appearance of man on Earth.
ECOLOGICAL OPTIMUM OF THE SPECIES
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 exists safely 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 action of the factor that is most favorable for the life of a given species.
Deviations from the optimum are determined zonesoppression (zonespessimum). The greater 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 beyond which the organism dies.
Area of tolerance- the range of values of the environmental factor at which the existence of an organism is possible.
Each organism is characterized by its own maximums, optimums and minimums of environmental factors. For example, a housefly can withstand temperature fluctuations from 7 to 50 °C, but 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 certain species.
An ecological niche characterizes the way of life of an organism, its living conditions and nutrition. In contrast to a niche, the concept of habitat denotes the territory where an organism lives, i.e. its “address”. For example, herbivorous inhabitants of the steppes - cows and kangaroos - occupy the same ecological niche, but have different habitats. On the contrary, the inhabitants of the forest - squirrel and elk, also classified as herbivores - occupy different ecological niches.
The ecological niche always determines the distribution of an organism and its role in the community.
In one community, two species cannot occupy the same ecological niche.
LIMITING FACTOR
Limiting factor- any factor that limits the development or existence of an organism, species or community.
For example, if the soil lacks a certain microelement, this causes a decrease in plant productivity. Due to the lack of food, the insects that fed on these plants die. The latter affects the survival of entomophagous predators: other insects, birds and amphibians.
Limiting factors determine the distribution area of each species. For example, the spread of many animal species to the north is hampered by a lack of heat and light, and to the south by a lack of moisture.
Shelford's Law of Tolerance
The limiting factor limiting the development of an organism can be either a minimum or maximum environmental impact.
The law of tolerance can be formulated more simply: it is bad to both underfeed and overfeed a plant or animal.
A corollary 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 may be considered a pollutant.
So, for each species there are limits to the values of vital factors of the abiotic environment that limit the zone of its tolerance (stability). A living organism can exist within a certain range of factor values. The wider this interval, the higher the body’s resistance. The law of tolerance is one of the fundamental ones in modern ecology.
REGULARITIES OF ENVIRONMENTAL FACTORS ACTION
LAW OF OPTIMUM
Law of Optimum
Any environmental factor has certain limits of positive influence on living organisms.
Factors have a positive effect on organisms only within certain limits. Their insufficient or excessive effect has a negative effect on organisms.
The law of optimum is universal. It determines the boundaries of the conditions in which the existence of species is possible, as well as the measure of variability of these conditions.
Stenobionts- highly specialized species that can live only in relatively constant conditions. For example, deep-sea fish, echinoderms, and crustaceans cannot tolerate temperature fluctuations even within 2–3 °C. Plants in 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 endurance (ecologically flexible species). For example, cosmopolitan species.
If it is necessary to emphasize the relationship to any factor, use the combinations “steno-” and “eury-” in relation to its name, for example, stenothermic species - cannot tolerate temperature fluctuations, euryhaline - capable of living with wide fluctuations in water salinity, etc.
LIEBICH'S LAW OF MINIMUM
Liebig's law of the minimum, or the law of the limiting factor
The most significant factor for the body is the one that deviates most from its optimal value.
It is on this minimally (or maximally) represented environmental factor at a given moment that the survival of the organism depends. At other times, other factors may be limiting. During their lives, individuals of species encounter a variety of limitations to their life activities. Thus, the factor limiting the spread of deer is the depth of the snow cover; moths - winter temperature; and for grayling - the concentration of oxygen dissolved in water.
This law is taken into account in agricultural practice. The German chemist Justus von Liebig found that the productivity of cultivated plants primarily depends on the nutrient (mineral element) present in the soil most weakly. For example, if phosphorus in the soil is only 20% of the required norm, and calcium is 50% of the norm, then the limiting factor will be a lack of phosphorus; It is necessary first of all to add phosphorus-containing fertilizers to the soil.
The figurative representation of this law is named after the scientist - the so-called “Liebig barrel” (see figure). The essence of the model is that when the barrel is filled, water begins to flow over the smallest board in the barrel and the length of the remaining boards no longer matters.
INTERACTION OF ECOLOGICAL FACTORS
A change in the intensity of one environmental factor can narrow the limit of the body's endurance to another factor or, conversely, increase it.
In the natural environment, the effects 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 increase the threat to human health several times more than each of these factors separately.
Mutual reinforcement (the phenomenon of synergy). The consequence of this is a decrease in the vitality of the body. High humidity significantly reduces the body's resistance to high temperatures. A decrease in nitrogen content in the soil leads to a decrease in the drought resistance of cereals.
Compensation. Example: ducks left to spend the winter in temperate latitudes compensate for the lack of warmth with abundant food; the poverty of the soil in the humid equatorial forest is compensated by the rapid and efficient cycle of substances; in places where there is a lot of strontium, mollusks 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 with an abundance of light, and the mineral elements necessary for plant nutrition cannot be replaced with 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 exposure to environmental factors is directly dependent on the duration of this exposure. Long-term exposure to high or low temperatures is detrimental to many plants, while plants tolerate short-term changes normally.
Thus, environmental factors act on organisms jointly and simultaneously. The presence and prosperity of organisms in a given habitat depend on a whole range of conditions.
Environmental factors and the concept of ecological niche
Concept of environmental factor
1.1.1. The concept of environmental factors and their classification
From an environmental perspective Wednesday - these are natural bodies and phenomena with which the organism is in direct or indirect relationships. The environment surrounding an organism is characterized by enormous diversity, consisting of many elements, phenomena, conditions that are dynamic in time and space, which are considered as factors .
Environmental factor - this is any environmental condition, capable of exerting a direct or indirect influence on living organisms, at least during one of the phases of their individual development. In turn, the body reacts to the environmental factor with specific adaptive reactions.
Thus, environmental factors- these are all elements of the natural environment that influence the existence and development of organisms, and to which living beings react with adaptation reactions (beyond the ability of adaptation, death occurs).
It should be noted that in nature, environmental factors act in a complex manner. This is especially important to remember when assessing the impact of chemical pollutants. In this case, the “total” effect, when the negative effect of one substance is superimposed on the negative effect of others, and to this is added the influence of a stressful situation, noise, and various physical fields, significantly changes the MPC values given in reference books. This effect is called synergistic.
The most important concept is limiting factor, that is, one whose level (dose) approaches the limit of the body’s endurance, the concentration of which is lower or higher than optimal. This concept is defined by Liebig's laws of minimum (1840) and Shelford's laws of tolerance (1913). The most often limiting factors are temperature, light, nutrients, currents and pressure in the environment, fires, etc.
The most common organisms are those with a wide range of tolerance to 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 determining 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 branch of ecology that studies the associations of populations of various species of plants, animals, microorganisms (biocenoses), the ways of their formation and interaction with the environment is called synecology . Within the boundaries of synecology there are phytocenology, or geobotany (the object of study is groupings of plants), biocenology (groupings of animals).
Thus, the concept of an environmental factor is one of the most general and extremely broad concepts of ecology. Accordingly, the task of classifying environmental factors has proven to be very difficult, so there is still no generally accepted option. At the same time, agreement has been reached regarding the advisability of using certain characteristics when classifying environmental factors.
Traditionally, three groups of environmental factors have been identified:
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, there are ten groups of environmental factors (the total number is about sixty), combined into a special classification:
1. by time – factors of time (evolutionary, historical, active), periodicity (periodic and non-periodic), primary and secondary;
2. by origin (cosmic, abiotic, biotic, natural, technogenic, anthropogenic);
3. by environment of occurrence (atmospheric, water, geomorphological, ecosystem);
4. by nature (informational, physical, chemical, energy, biogenic, complex, climatic);
5. by object of influence (individual, group, species, social);
6. by degree of influence (lethal, extreme, limiting, disturbing, mutagenic, teratogenic);
7. according to the conditions of action (density-dependent or independent);
8. according to the spectrum of influence (selective or general action).
First of all, environmental factors are divided into external (exogenous or entopic) And internal (endogenous) in relation to a given ecosystem.
TO external These include factors whose actions, to one degree or another, determine the changes occurring in the ecosystem, but they themselves practically do not experience its reverse influence. 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. These are the numbers and biomass of populations, reserves of various substances, characteristics of the ground layer of air, water or soil mass, etc.
The second common classification principle is the division of factors into biotic And abiotic . The first includes various variables that characterize the properties of living matter, and the second - the non-living components of the ecosystem and its external environment. The division of factors into endogenous - exogenous and biotic - abiotic does 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 ground layer of air or water.
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, migration (biogeographic), anthropogenic factors, and among endogenous factors - micrometeorological (bioclimatic), soil (edaphic), water and biotic.
An important classification indicator is nature of dynamics environmental factors, especially the presence or absence of its frequency (daily, lunar, seasonal, perennial). 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 influence of these factors, that is, their frequency.
Biologist A.S. Monchadsky (1958) distinguished primary periodic factors, secondary periodic factors and non-periodic factors.
TO primary periodic factors These include mainly phenomena associated with the rotation of the Earth: the change of seasons, daily changes in illumination, tidal phenomena, etc. These factors, which are characterized by regular 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, the dynamics of plant food, the content of dissolved gases in water, etc.
TO non-periodic These include factors that do not have the correct periodicity or cyclicity. These are soil factors and various types of natural phenomena. Anthropogenic impacts on the environment are often non-periodic factors that can occur 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 numbers, biomass or population densities of organisms, as well as 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 the 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, i.e. .To. conservation laws do not apply to them.
The number of possible environmental factors seems 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 different types some factors stand out as the most significant, or imperative . In terrestrial ecosystems, among the exogenous factors, these 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 ground 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 nutrients, redox potential;
3) biotic - population density 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 characterized numerically, that is, described by a mathematical variable that takes a value on a certain scale.
Environmental factors can be ordered by their strength relative to their impact on an organism, population, ecosystem, that is ranked . If the value of the first most influential factor is measured by the variable X 1, second - variable X 2 , … , n th - variable x n etc., then the entire complex of environmental factors can be represented by the sequence ( X 1 , X 2 , … , x n, ...).In order to characterize the many possible complexes of environmental factors that obtain at different values of each of them, it is advisable to introduce the concept of a space of environmental factors, or, in other words, 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 quantitatively characterize the impact of environmental factors on the vital signs of individuals, such as growth rate, development, fertility, life expectancy, mortality, nutrition, metabolism, physical activity, etc. (let them be numbered with an index k= 1, …, m), the concept of f at n To ts And I X
O T To l And ka
.
Values accepted by the indicator with number k on a certain scale with varying environmental factors, as a rule, they are limited from below and from above. Let us denote by 
a segment on the scale of values of one of the indicators ( k th) vital activity of the ecosystem.
Response function k- indicator on the totality of environmental factors ( X 1 , X 2 , … , x n, ...) is called a function φ k, displaying ecological space E to the scale Ik:
,
which to each point ( X 1 , X 2 , … , x n, …) space E matches the number φ k(X 1 , X 2 , … , x n, …) on the scale Ik .
Although the number of environmental factors is potentially unlimited and, therefore, the dimensions of ecological space are infinite E and the number of response function arguments φ k(X 1 , X 2 , … , x n, ...), in reality it is possible to identify a finite number of factors, for example n, with the help of which it is possible to explain a given 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 list of factors indicated, do not have a decisive impact on the indicator being studied. Their influence can be considered 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 φ k 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 on 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 tolerance limit) to a maximum at the optimal factor value xj 0 and monotonically decreasing towards the maximum value of the factor xj e (upper limit of tolerance).
Interval Xj = [x j s, x j e ] is called tolerance interval for this factor, and point xj 0 at which the response function reaches an extremum is called optimum point on this factor.
The same environmental factors have different effects on organisms of different species living together. For some they may be favorable, for others they may not. An important element is the reaction of organisms to the influence of an environmental factor, the negative effect of which can occur in the event of an excess or deficiency of the dose. Therefore, there is the concept of a favorable dose or optimum zones factor and pessimum zones (range of factor dose values in which organisms feel depressed).
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. It is expressed quantitatively 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 air temperature fluctuations 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 beetle, mice, rats, wolves, cockroaches, reeds, wheatgrass). Within the boundaries of eurybionts and stenobionts, depending on a specific factor, organisms are divided into eurythermic and stenothermic (based on their response to temperature), euryhaline and stenohaline (based on their response to the salinity of the aquatic environment), euryphotes and stenophotes (based on their response to lighting).
To express the relative degree of tolerance, there are a number of terms in ecology that use the prefixes steno -, which means narrow, and evry - - wide. Species that have a narrow tolerance range (1) are called stenoeks , and species with a wide range of tolerance (2) – euryecami on this factor. Imperative factors have their own terms:
by temperature: stenothermic - eurythermic;
by water: stenohydric – euryhydric;
according to salinity: stenohaline – euryhaline;
according to food: stenophagous – euryphagous;
according to the choice of habitat: stenooic – euryoic.
1.1.3. Law of limiting factor
The presence or prosperity of an organism in a given habitat depends on a complex of environmental factors. For each factor there is a range of tolerance, beyond which the body is not able to exist. The impossibility of flourishing or the absence of an organism is determined by those factors whose values approach or exceed the limits of tolerance.
Limiting We will consider a factor according to which, in order to achieve a given (small) relative change in the response function, a minimum relative change in this factor is required. If
then the limiting factor will be Xl, that is, the limiting factor is along which the gradient of the response function is directed.
It is obvious that the gradient is directed normal to the boundary of the tolerance region. And for the limiting factor, all other things being equal, there is a greater chance of going beyond the area of tolerance. That is, the limiting factor is the factor 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 demonstrated in 1840. organic chemist Yu. Liebig, one of the founders of agrochemistry, who put forward theory of mineral nutrition of plants. He was the first to study the influence of various factors on plant growth, establishing that crop yield is 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 abundance, but those that are required in minute quantities, for example, zinc, boron or iron, of which there is very little in the soil. Liebig's conclusion that "the growth of a plant depends on the element of nutrition that is present in the minimum quantity" became known as Liebig's "law of the minimum."
70 years later, the American scientist V. Shelford showed that not only a substance present in a minimum can determine the yield or viability of an organism, but an excess of some element can lead to undesirable deviations. For example, an excess of mercury in the human body relative to a certain norm causes severe functional disorders. If there is 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: suffocation of the roots, the occurrence of anaerobic processes, acidification of the soil, etc. are possible. Excess and lack of pH in the soil also reduces the yield in a given location. According to V. Shelford, factors present in both excess and deficiency are called limiting, and the corresponding rule is called the law of “limiting factor” or “ 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 air and water poses a serious threat to human health.
A number of auxiliary principles can be formulated that complement the “law of tolerance”:
1. Organisms may 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 widespread.
3. If conditions for one environmental factor are not optimal for a 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. Tolerance limits for reproducing individuals, seeds, embryos and seedlings are usually narrower than for non-reproducing 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 factors narrow the range of tolerance. As conditions approach extremes, adaptation becomes increasingly costly, and the body becomes increasingly less protected from other factors, such as diseases and predators.
1.1.4. Some basic abiotic factors
Abiotic factors of the terrestrial environment . The abiotic component of the terrestrial environment represents a set of climatic and soil factors, consisting of many dynamic elements that influence 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). 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 solving this problem. Light is not only a vital factor, but also a limiting one, both at maximum and minimum levels. About 99% of the total energy of solar radiation consists of rays with a wavelength of 0.17÷4.0 microns, including 48% in the visible part of the spectrum with a wavelength of 0.4÷0.76 microns, 45% in the infrared (wavelength from 0.75 microns to 1 mm) and about 7% for ultraviolet (wavelength less than 0.4 microns). Infrared rays are of primary importance for life, and in the processes of photosynthesis, orange-red and ultraviolet rays play the most important role.
2) Illumination of the earth's surface , associated with radiant energy and determined by the duration and intensity of the luminous flux. Due to the rotation of the Earth, light and dark periods periodically alternate. Illumination plays a vital role for all living things, and organisms are physiologically adapted to the cycle of day and night, to the ratio of dark and light periods of the day. Almost all animals have so-called circadian (circadian) rhythms of activity associated with the cycle 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 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 temperature range - from -200°C to 100°C. As a rule, the upper limit values of the factor turn out to be more critical than the lower ones. The range of temperature fluctuations in water is usually smaller than on land, and the temperature tolerance range of aquatic organisms is usually narrower than that of 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 daily activity of plants and animals. Temperature often creates zonation and stratification of habitats.
4) Ambient 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 air temperature. The higher the temperature, the more moisture the air contains. For each temperature there is a certain limit of air saturation with water vapor, which is called maximum . The difference between maximum and given saturation is called moisture 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 deficiency during certain periods of the growing season promotes 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 deficiency.
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 most important 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 large movements of air masses, or so-called “weather systems”. The distribution of precipitation over the seasons is an extremely important limiting factor for organisms. Precipitation - one of the links in the water cycle on Earth, and in their loss there is a sharp unevenness, and therefore they distinguish humid (wet) and arid (dry) zones. The maximum precipitation is in tropical forests (up to 2000 mm/year), the minimum in deserts (0.18 mm/year). Zones with precipitation less than 250 mm/year are already considered arid. As a rule, an uneven distribution of precipitation over the seasons is found 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 more evenly distributed throughout the seasons.
6) Gas composition of the atmosphere . Its composition is relatively constant and includes predominantly nitrogen and oxygen with an admixture of small amounts of CO 2 and argon. Other gases - in trace quantities. In addition, the upper layers of the atmosphere contain ozone. Typically, atmospheric air contains 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 (CO 2) is a natural damper of solar and reciprocal terrestrial radiation; ozone plays a screening role in relation to the ultraviolet part of the solar spectrum, which is destructive for all living things. Impurities of tiny particles affect the transparency of the atmosphere and prevent the passage of sunlight to the surface of the Earth. The concentrations of oxygen (21% by volume) and CO 2 (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 cause of wind is a pressure difference caused by unequal heating of the earth's surface. The wind flow is directed towards 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 atmospheric air. Wind performs an important function of transporting matter and living organisms between ecosystems. In addition, wind has a direct mechanical effect on vegetation and soil, damaging or destroying plants and destroying 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 direct limiting factor, 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 factors of soil cover . Soil factors are clearly endogenous in nature, 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 original material - the underlying mineral substrate And organic component, in which organisms and their waste products are mixed with finely ground and modified starting material. The spaces between the particles are filled with gases and water. Texture and soil porosity – the most important characteristics that largely determine the availability of nutrients to plants and soil animals. In the soil, processes of synthesis and biosynthesis take place, and various chemical reactions of the transformation of substances occur, associated with the life of bacteria.
1.1.5. Biotic factors
Under biotic factors understand the totality of influences of the life activity of some organisms on others.
Relationships between animals, plants, microorganisms (they are also called co-actions ) are extremely diverse. They can be divided into straight And indirect, are mediated through changes in their presence of relevant abiotic factors.
The interactions of living organisms are classified in terms of their reactions to each other. In particular, they highlight homotypic reactions between interacting individuals of the same species and heterotypic reactions during co-actions 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 type of animal or plant has a clear selectivity to the composition of food. There are different types monophagous feeding on only one species, polyphages , feeding on several species, as well as species feeding on a more or less limited range of food, called broad or narrow oligophages .
Relationships between species are naturally necessary. Species cannot be divided into enemies and them victims, since the relationships between species are reciprocal. Disappearance² victims² may lead to extinction ² enemy².
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.
