In the complex of action of factors, it is possible to single out some patterns that are largely universal (general) in relation to organisms. These patterns include the rule of optimum, the rule of interaction of factors, the rule of limiting factors, and some others.

Optimum rule . In accordance with this rule, for an organism or a certain stage of its development, there is a range of the most favorable (optimal) value of the factor. The more significant the deviation of the action of the factor from the optimum, the more this factor inhibits the vital activity of the organism. This range is called the zone of oppression. The maximum and minimum tolerated values ​​of the factor are critical points, beyond which the existence of the organism is no longer possible.

The maximum population density is usually confined to the optimum zone. Zones of optimum for different organisms are not the same. The wider the amplitude of fluctuations of the factor, at which the organism can remain viable, the higher its stability, i.e. tolerance to one or another factor (from Lat. tolerance- patience). Organisms with a wide amplitude of resistance belong to the group eurybionts (gr. eury- wide, bios- life). Organisms with a narrow range of adaptation to factors are called stenobionts (gr. stenos- narrow). It is important to emphasize that the zones of optimum in relation to various factors differ, and therefore organisms fully show their potential capabilities if they exist under conditions of the entire spectrum of factors with optimal values.

Rule of interaction of factors . Its essence lies in the fact that some factors can enhance or mitigate the force of other factors. For example, an excess of heat can be somewhat mitigated by low air humidity, a lack of light for plant photosynthesis can be compensated by an increased content of carbon dioxide in the air, and so on. It does not, however, follow that the factors can be interchanged. They are not interchangeable.

Rule of Limiting Factors . The essence of this rule lies in the fact that a factor that is in deficiency or excess (near critical points) negatively affects organisms and, in addition, limits the possibility of manifestation of the strength of other factors, including those at the optimum. Limiting factors usually determine the boundaries of the distribution of species, their ranges. The productivity of organisms depends on them.

A person by his activity often violates almost all of the listed patterns of factors. This is especially true for limiting factors (destruction of habitats, disruption of water and mineral nutrition, etc.).

Lecture 14

The impact of the environment on the biota.

1. Environmental factors.

2. General patterns of their action on living organisms.

environmental factors. General patterns of their action on living organisms.

Organisms' adaptations to their environment are called adaptations. The ability to adapt is one of the main properties of life in general, as it provides the very 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. Adaptations arise and change during the evolution of species.

Separate properties or elements of the environment that affect organisms are called environmental factors. . Environmental factors are diverse. They may be necessary or, conversely, harmful to living beings, promote or hinder survival and reproduction. Environmental factors have a different nature and specificity of action. Environmental factors are divided into abiotic and biotic, anthropogenic.

Abiotic factors - temperature, light, radioactive radiation, pressure, air humidity, salt composition of water, wind, currents, terrain - these are all properties of inanimate nature that directly or indirectly affect living organisms.

Biotic factors are forms of influence of living beings on each other. Each organism constantly experiences the direct or indirect influence of other beings, enters into communication with representatives of its own species and other species, depends on them and itself influences them. The surrounding organic world is an integral part of the environment of every living being.

Mutual connections of organisms are the basis for the existence of biocenoses and populations; consideration of them belongs to the field of synecology.

Anthropogenic factors - these are forms of activity of human society that lead to a change in nature as a habitat for other species or directly affect their lives. Although man influences living nature through changes in abiotic factors and biotic relationships of species, anthropogenic activity should be singled out as a special force that does not fit into the framework of this classification. The significance of anthropogenic influence on the living world of the planet continues to grow rapidly.

The same environmental factor has a different meaning in the life of cohabiting organisms of different species. For example, a strong wind in winter is unfavorable for large, open-dwelling animals, but does not affect smaller ones that take refuge in burrows or under snow. The salt composition of the soil is important for plant nutrition, but is indifferent to most terrestrial animals, etc.

Changes in environmental factors over time can be: 1) regularly-periodic, changing the strength of the impact in connection with the time of day or season of the year or the rhythm of the tides in the ocean; 2) irregular, without a clear periodicity, for example, changes in weather conditions in different years, catastrophic phenomena - storms, downpours, landslides, etc.; 3) directed over known, sometimes long, periods of time, for example, during a cooling or warming of the climate, overgrowing of water bodies, constant grazing in the same area, etc.

Environmental environmental factors have various effects on living organisms, that is, they can act as irritants that cause adaptive changes in physiological and biochemical functions; as limiters, making it impossible to exist in these conditions; as modifiers causing anatomical and morphological changes in organisms; as signals indicating changes in other environmental factors.

Despite the wide variety of environmental factors, a number of general patterns can be identified in the nature of their impact on organisms and in the responses of living beings.

1. The law of optimum. Each factor has only certain limits of positive influence on organisms. The result of the action of a variable factor depends primarily on the strength of its manifestation. Both insufficient and excessive action of the factor negatively affects the life of individuals. Favorable impact force is called the zone of optimum environmental factor or simply the optimum for organisms of this species. The stronger the deviations from the optimum, the more pronounced the inhibitory effect of this factor on organisms (pessimum zone). The maximum and minimum tolerated values ​​of the factor are critical points, beyond which existence is no longer possible, death occurs. The endurance limits between critical points are called ecological valence (tolerance range) living beings in relation to a specific environmental factor.

Representatives different types differ greatly from each other both in the position of the optimum and in ecological valency. For example, arctic foxes in the tundra can tolerate fluctuations in air temperature in the range of about 80°С (from +30° to -55°С), while warm-water crustaceans Copilia mirabilis withstand changes in water temperature in the range of no more than 6°С (from 23 ° to 29°С). The emergence of narrow tolerance ranges in evolution can be viewed as a form of specialization, as a result of which greater efficiency is achieved at the expense of adaptability and diversity increases in the community.

The same force of manifestation of a factor can be optimal for one species, pessimal for another, and go beyond the limits of endurance for the third.

The wide ecological valence of a species in relation to abiotic environmental factors is indicated by adding the prefix "evry" to the name of the factor. Eurythermal species - enduring significant temperature fluctuations, eurybatic species - a wide range of pressure, euryhaline - varying degrees of salinity.

The inability to tolerate significant fluctuations in the factor, or narrow ecological valence, is characterized by the prefix "steno" - stenothermic, stenobatic, stenohaline species, etc. In a broader sense, species that require strictly defined environmental conditions for their existence are called stenobiont , and those that are able to adapt to different environmental conditions - eurybiont.

2. Ambiguity of the action of the factor on different functions. Each factor affects different functions of the body in different ways. The optimum for some processes may be the pessimum for others. Thus, the air temperature from 40 ° to 45 ° C in cold-blooded animals greatly increases the rate of metabolic processes in the body, but inhibits motor activity, and the animals fall into a thermal stupor. For many fish, the water temperature that is optimal for the maturation of reproductive products is unfavorable for spawning, which occurs in a different temperature range.

The life cycle, in which at certain periods the organism predominantly performs certain functions (nutrition, growth, reproduction, resettlement, etc.), is always consistent with seasonal changes in the complex of environmental factors. Mobile organisms can also change habitats for the successful implementation of all their life functions.

The breeding season is usually critical; during this period, many environmental factors often become limiting. The tolerance limits for breeding individuals, seeds, eggs, embryos, seedlings and larvae are usually narrower than for non-breeding adult plants or animals. So, an adult cypress can grow both on a dry highland and immersed in water, but it breeds only where there is moist, but not flooded soil for the development of seedlings. Many marine animals can tolerate brackish or fresh water with a high chloride content, so they often enter upstream rivers. But their larvae cannot live in such waters, so the species cannot breed in the river and does not settle here permanently.

3. Variability, variability and diversity of responses to the action of environmental factors in individual individuals of the species.

The degree of endurance, critical points, optimal and pessimal zones of individual individuals do not coincide. This variability is determined both by the hereditary qualities of individuals and by sex, age, and physiological differences. For example, in the mill moth butterfly, one of the pests of flour and grain products, the critical minimum temperature for caterpillars is -7°C, for adult forms -22°C, and for eggs -27°C. Frost at 10°C kills caterpillars, but is not dangerous for adults and eggs of this pest. Consequently, the ecological valence of a species is always wider than the ecological valence of each individual.

4. To each of the environmental factors, species adapt in a relatively independent way. The degree of tolerance to any factor does not mean the corresponding ecological valence of the species in relation to other factors. For example, species that tolerate wide temperature changes need not also be adapted to wide fluctuations in humidity or salinity. Eurythermal species can be stenohaline, stenobatic, or vice versa. The ecological valencies of a species in relation to different factors can be very diverse. This creates an extraordinary variety of adaptations in nature. A set of ecological valences in relation to various environmental factors constitutes the ecological spectrum of a species.

5. Non-coincidence of the ecological spectra of individual species. Each species is specific in its ecological capabilities. Even among species that are close in terms of ways of adapting to the environment, there are differences in their attitude to any individual factors.

6. Interaction of factors.

The optimal zone and limits of endurance of organisms in relation to any environmental factor can shift depending on the strength and combination of other factors acting simultaneously. This pattern is called the interaction of factors. For example, heat is easier to bear in dry rather than moist air. The threat of freezing is much higher in frost with strong winds than in calm weather. Thus, the same factor in combination with others has an unequal environmental impact. On the contrary, the same ecological result can be obtained in different ways. For example, wilting of plants can be stopped by both increasing the amount of moisture in the soil and lowering the air temperature, which reduces evaporation. The effect of partial mutual substitution of factors is created.

At the same time, the mutual compensation of the action of environmental factors has certain limits, and it is impossible to completely replace one of them with another. The complete absence of water, or even one of the main elements of mineral nutrition, makes the life of the plant impossible, despite the most favorable combination of other conditions. The extreme lack of heat in the polar deserts cannot be made up for either by an abundance of moisture or round-the-clock illumination.

7. The rule of limiting (limiting) factors. Environmental factors that are farthest away from the optimum make it especially difficult for the species to exist under given conditions. If at least one of the environmental factors approaches or goes beyond critical values, then, despite the optimal combination of other conditions, individuals are threatened with death. Such strongly deviating from the optimum factors become of paramount importance in the life of the species or its individual representatives at any particular time interval.

Environmental limiting factors determine the geographic range of a species. The nature of these factors may be different. Thus, the movement of a species to the north can be limited by a lack of heat, and to arid regions by a lack of moisture or too high temperatures. Biotic relations, for example, the occupation of a territory by a stronger competitor or the lack of pollinators for plants, can also serve as a factor limiting the distribution.

To determine whether a species can exist in a given geographical area, one must first find out whether any environmental factors go beyond its ecological valence, especially in the most vulnerable period of development.

Organisms with a wide range of tolerance to all factors are usually the most widely distributed.

8. The rule of conformity of environmental conditions with the genetic predetermination of the organism. A species of organisms can exist as long as and insofar as its natural environment corresponds to the genetic possibilities of adapting this species to its environment. fluctuations and changes. Each species of living arose in a certain environment, to one degree or another adapted to it, and its further existence is possible only in it or a close environment. A sharp and rapid change in the environment of life can lead to the fact that the genetic capabilities of the species will be insufficient to adapt to new conditions.

Habitat - this is that part of nature that surrounds a living organism and with which it directly interacts. The components and properties of the environment are diverse and changeable. Any living being lives in a complex, changing world, constantly adapting to it and regulating its life activity in accordance with its changes.

Separate properties or elements of the environment that affect organisms are called environmental factors. Environmental factors are diverse. They may be necessary or, conversely, harmful to living beings, promote or hinder survival and reproduction. Environmental factors have a different nature and specificity of action. Among them are abiotic and biotic, anthropogenic.

Abiotic factors - temperature, light, radioactive radiation, pressure, air humidity, salt composition of water, wind, currents, terrain - these are all properties of inanimate nature that directly or indirectly affect living organisms.

Biotic factors - these are forms of influence of living beings on each other. Each organism constantly experiences the direct or indirect influence of other creatures, enters into contact with representatives of its own species and other species - plants, animals, microorganisms, depends on them and itself has an impact on them. The surrounding organic world is an integral part of the environment of every living being.

Mutual connections of organisms are the basis for the existence of biocenoses and populations; consideration of them belongs to the field of syn-ecology.

Anthropogenic factors - these are forms of activity of human society that lead to a change in nature as a habitat for other species or directly affect their lives. In the course of human history, the development of first hunting, and then agriculture, industry, and transport has greatly changed the nature of our planet. Meaning anthropogenic impacts to the entire living world of the Earth continues to grow rapidly.

Although man influences wildlife through a change in abiotic factors and biotic relationships of species, the activities of people on the planet should be singled out as a special force that does not fit into the framework of this classification. At present, practically the fate of the living cover of the Earth, all kinds of organisms, is in the hands of human society, depends on the anthropogenic influence on nature.

The same environmental factor has a different meaning in the life of cohabiting organisms of different species. For example, a strong wind in winter is unfavorable for large, open-dwelling animals, but does not affect smaller ones that take refuge in burrows or under snow. The salt composition of the soil is important for plant nutrition, but is indifferent to most land animals, etc.

Changes in environmental factors over time can be: 1) regularly-periodic, changing the strength of the impact in connection with the time of day, or the season of the year, or the rhythm of the tides in the ocean; 2) irregular, without a clear periodicity, for example, changes in weather conditions in different years, catastrophic phenomena - storms, downpours, landslides, etc.; 3) directed over known, sometimes long, periods of time, for example, during a cooling or warming of the climate, overgrowing of water bodies, constant grazing in the same area, etc.

Among the environmental factors, resources and conditions are distinguished. Resources environment, organisms use, consume, thereby reducing their number. Resources include food, water when it is scarce, shelters, convenient places for breeding, etc. Terms - these are factors to which organisms are forced to adapt, but usually cannot influence them. One and the same environmental factor can be a resource for some and a condition for other species. For example, light is a vital energy resource for plants, and for animals with vision, it is a condition for visual orientation. Water for many organisms can be both a condition of life and a resource.

2.2. Organism adaptations

Organisms' adaptations to their environment are called adaptation. Adaptations are any changes in the structure and functions of organisms that increase their chances of survival.

The ability to adapt is one of the main properties of life in general, as it provides the very 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. Adaptations arise and develop in the course of the evolution of species.

The main mechanisms of adaptation at the level of the organism: 1) biochemical- manifest themselves in intracellular processes, such as a change in the work of enzymes or a change in their number; 2) physiological– for example, increased sweating with increasing temperature in a number of species; 3) morpho-anatomical- features of the structure and shape of the body associated with lifestyle; four) behavioral- for example, the search for favorable habitats by animals, the creation of burrows, nests, etc.; 5) ontogenetic- acceleration or deceleration of individual development, contributing to survival under changing conditions.

Environmental environmental factors have various effects on living organisms, i.e., they can affect how irritants, causing adaptive changes in physiological and biochemical functions; how limiters, causing the impossibility of existence in these conditions; how modifiers, causing morphological and anatomical changes in organisms; how signals, indicating changes in other environmental factors.

2.3. General laws of the action of environmental factors on organisms

Despite the wide variety of environmental factors, a number of general patterns can be identified in the nature of their impact on organisms and in the responses of living beings.

1. The law of optimum.

Each factor has certain limits of positive influence on organisms (Fig. 1). The result of the action of a variable factor depends primarily on the strength of its manifestation. Both insufficient and excessive action of the factor negatively affects the life of individuals. The beneficial effect is called zone of optimum ecological factor or simply optimum for organisms of this species. The stronger the deviation from the optimum, the more pronounced the inhibitory effect of this factor on organisms. (pessimum zone). The maximum and minimum tolerated values ​​of the factor are critical points per beyond which existence is no longer possible, death occurs. The endurance limits between critical points are called environmental valence living beings in relation to a specific environmental factor.

Rice. one. Scheme of the action of environmental factors on living organisms

Representatives of different species differ greatly from each other both in the position of the optimum and in ecological valency. For example, arctic foxes in the tundra can tolerate fluctuations in air temperature in the range of more than 80 °C (from +30 to -55 °C), while warm-water crustaceans Copilia mirabilis withstand changes in water temperature in the range of no more than 6 °C (from +23 up to +29 °C). One and the same force of manifestation of a factor can be optimal for one species, pessimal for another, and go beyond the limits of endurance for the third (Fig. 2).

The wide ecological valency of a species in relation to abiotic environmental factors is indicated by adding the prefix "evry" to the name of the factor. eurythermal species - enduring significant temperature fluctuations, eurybatic– wide pressure range, euryhaline– different degree of salinization of the environment.

Rice. 2. The position of the optimum curves on the temperature scale for different species:

1, 2 - stenothermic species, cryophiles;

3–7 – eurythermal species;

8, 9 - stenothermic species, thermophiles

The inability to endure significant fluctuations in the factor, or narrow ecological valence, is characterized by the prefix "steno" - stenothermal, stenobate, stenohaline species, etc. In a broader sense, species whose existence requires strictly defined environmental conditions are called stenobiont, and those that are able to adapt to different environmental conditions - eurybiontic.

Conditions approaching critical points in one or several factors at once are called extreme.

The position of the optimum and critical points on the factor gradient can be shifted within certain limits by the action of environmental conditions. This occurs regularly in many species as the seasons change. In winter, for example, sparrows withstand severe frosts, and in summer they die from cooling at temperatures just below zero. The phenomenon of shifting the optimum with respect to any factor is called acclimation. With regard to temperature, this is a well-known process of thermal hardening of the body. Temperature acclimation requires a significant period of time. The mechanism is the change in cells of enzymes that catalyze the same reactions, but at different temperatures (the so-called isoenzymes). Each enzyme is encoded by its own gene, therefore, it is necessary to turn off some genes and activate others, transcription, translation, assembly of a sufficient amount of a new protein, etc. The overall process takes an average of about two weeks and is stimulated by changes in the environment. Acclimation, or hardening, is an important adaptation of organisms that occurs under gradually impending adverse conditions or when they enter territories with a different climate. In these cases, it is an integral part overall process acclimatization.

2. Ambiguity of the action of the factor on different functions.

Each factor affects different body functions differently (Fig. 3). The optimum for some processes may be the pessimum for others. Thus, the air temperature from +40 to +45 ° C in cold-blooded animals greatly increases the rate of metabolic processes in the body, but inhibits motor activity, and the animals fall into a thermal stupor. For many fish, the water temperature that is optimal for the maturation of reproductive products is unfavorable for spawning, which occurs at a different temperature range.

Rice. 3. Scheme of the dependence of photosynthesis and respiration of a plant on temperature (according to V. Larcher, 1978): t min, t opt, t max– temperature minimum, optimum and maximum for plant growth (shaded area)

The life cycle, in which at certain periods the organism predominantly performs certain functions (nutrition, growth, reproduction, resettlement, etc.), is always consistent with seasonal changes in the complex of environmental factors. Mobile organisms can also change habitats for the successful implementation of all their life functions.

3. Variety of individual reactions to environmental factors. The degree of endurance, critical points, optimal and pessimal zones of individual individuals do not coincide. This variability is determined both by the hereditary qualities of individuals and by sex, age, and physiological differences. For example, in the mill moth butterfly, one of the pests of flour and grain products, the critical minimum temperature for caterpillars is -7 ° C, for adult forms -22 ° C, and for eggs -27 ° C. Frost at -10 °C kills caterpillars, but is not dangerous for adults and eggs of this pest. Consequently, the ecological valence of a species is always wider than the ecological valence of each individual.

4. Relative independence of adaptation of organisms to different factors. The degree of tolerance to any factor does not mean the corresponding ecological valence of the species in relation to other factors. For example, species that tolerate wide temperature changes need not also be adapted to wide fluctuations in humidity or salinity. Eurythermal species can be stenohaline, stenobatic, or vice versa. The ecological valencies of a species in relation to different factors can be very diverse. This creates an extraordinary variety of adaptations in nature. The set of ecological valences in relation to various environmental factors is ecological spectrum of the species.

5. Non-coincidence of the ecological spectra of individual species. Each species is specific in its ecological capabilities. Even among species that are close in terms of ways of adapting to the environment, there are differences in their attitude to any individual factors.

Rice. four. Changes in the participation of certain plant species in meadow grass stands depending on moisture (according to L. G. Ramensky et al., 1956): 1 – meadow clover; 2 - common yarrow; 3 - Delyavina's cellar; 4 – meadow bluegrass; 5 - tipchak; 6 - real bedstraw; 7 – early sedge; 8 - meadowsweet ordinary; 9 - hill geranium; 10 – field barnacle; 11 - short-nosed goat-beard

The rule of ecological individuality of species formulated by the Russian botanist L. G. Ramensky (1924) in relation to plants (Fig. 4), then it was widely confirmed by zoological studies.

6. Interaction of factors. The optimal zone and limits of endurance of organisms in relation to any environmental factor can shift depending on the strength and combination of other factors acting simultaneously (Fig. 5). This pattern has been named interactions of factors. For example, heat is easier to bear in dry rather than moist air. The threat of freezing is much higher in frost with strong winds than in calm weather. Thus, the same factor in combination with others has an unequal environmental impact. On the contrary, the same ecological result can be obtained in different ways. For example, wilting of plants can be stopped by both increasing the amount of moisture in the soil and lowering the air temperature, which reduces evaporation. The effect of partial mutual substitution of factors is created.

Rice. 5. Mortality of eggs of the pine silkworm Dendrolimus pini at different combinations of temperature and humidity

At the same time, the mutual compensation of the action of environmental factors has certain limits, and it is impossible to completely replace one of them with another. The complete absence of water, or even one of the main elements of mineral nutrition, makes the life of the plant impossible, despite the most favorable combination of other conditions. The extreme lack of heat in the polar deserts cannot be made up for either by an abundance of moisture or round-the-clock illumination.

Taking into account the patterns of interaction of environmental factors in agricultural practice, it is possible to skillfully maintain optimal conditions for the vital activity of cultivated plants and domestic animals.

7. The rule of limiting factors. The possibilities of the existence of organisms are primarily limited by those environmental factors that are most distant from the optimum. If at least one of the environmental factors approaches or goes beyond critical values, then, despite the optimal combination of other conditions, individuals are threatened with death. Any factors that strongly deviate from the optimum acquire paramount importance in the life of the species or its individual representatives in specific periods of time.

Environmental limiting factors determine the geographic range of a species. The nature of these factors may be different (Fig. 6). Thus, the movement of a species to the north can be limited by a lack of heat, and to arid regions by a lack of moisture or too high temperatures. Biotic relations, for example, the occupation of a territory by a stronger competitor or the lack of pollinators for plants, can also serve as a factor limiting the distribution. Thus, the pollination of figs depends entirely on a single insect species - the wasp Blastophaga psenes. This tree is native to the Mediterranean. Figs brought to California did not bear fruit until pollinator wasps were brought there. The distribution of legumes in the Arctic is limited by the distribution of bumblebees that pollinate them. On the island of Dixon, where there are no bumblebees, legumes are not found either, although the existence of these plants there is still permissible due to temperature conditions.

Rice. 6. Deep snow cover is a limiting factor in the distribution of deer (according to G. A. Novikov, 1981)

To determine whether a species can exist in a given geographical area, one must first find out whether any environmental factors go beyond its ecological valence, especially in the most vulnerable period of development.

The identification of limiting factors is very important in the practice of agriculture, since, by directing the main efforts to eliminate them, one can quickly and effectively increase crop yields or animal productivity. So, on highly acidic soils, the yield of wheat can be somewhat increased by applying various agronomic influences, but the best effect will be obtained only as a result of liming, which will remove the limiting effects of acidity. Knowing the limiting factors is thus the key to controlling the life of organisms. At different periods of life of individuals, various environmental factors act as limiting factors, therefore, skillful and constant regulation of the living conditions of grown plants and animals is required.

2.4. Principles of ecological classification of organisms

In ecology, the diversity and variety of ways and means of adaptation to the environment create the need for multiple classifications. Using any single criterion, it is impossible to reflect all aspects of the adaptability of organisms to the environment. Ecological classifications reflect the similarities that occur among members of very different groups if they use similar ways of adaptation. For example, if we classify animals according to the methods of movement, then the ecological group of species that move in the water by jet means such animals of different systematic position as jellyfish, cephalopods, some ciliates and flagellates, larvae of a number of dragonflies, etc. (Fig. 7). Ecological classifications can be based on a variety of criteria: methods of nutrition, movement, attitude to temperature, humidity, salinity, pressure etc. The division of all organisms into eurybiont and stenobiont according to the breadth of the range of adaptations to the environment is an example of the simplest ecological classification.

Rice. 7. Representatives of the ecological group of organisms moving in water in a jet way (according to S. A. Zernov, 1949):

1 – flagellar Medusochloris phiale;

2 – ciliate Craspedotella pileosus;

3 – jellyfish Cytaeis vulgaris;

4 – pelagic holothurian Pelagothuria;

5 - a larva of a dragonfly-rocker;

6 – swimming octopus Octopus vulgaris:

a- the direction of the water jet;

b- the direction of movement of the animal

Another example is the division of organisms into groups by the nature of nutrition.Autotrophs- These are organisms that use inorganic compounds as a source for building their body. Heterotrophs- all living beings that need food of organic origin. In turn, autotrophs are divided into phototrophs and chemotrophs. The first for the synthesis of organic molecules use the energy of sunlight, the second - the energy of chemical bonds. Heterotrophs are divided into saprophytes, using solutions of simple organic compounds, and Holozoic. Holozoans have a complex set of digestive enzymes and can eat complex organic compounds, decomposing them into simpler constituents. Holozoic are divided into saprophages(feed on dead plant matter) phytophages(consumers of living plants), zoophagous(needing living food) and necrophages(carnivorous animals). In turn, each of these groups can be subdivided into smaller ones, which have their own specifics in the nature of nutrition.

Otherwise, you can build a classification by way of getting food. Among animals, for example, such groups as filtrators(small crustaceans, toothless, whale, etc.), grazing forms(ungulates, leaf beetles), collectors(woodpeckers, moles, shrews, chicken), moving prey hunters(wolves, lions, ktyr flies, etc.) and a number of other groups. So, despite the great dissimilarity in organization, the same way of mastering prey in lions and flies leads to a number of analogies in their hunting habits and general structural features: leanness of the body, strong development of muscles, the ability to develop high speed for a short time, etc.

Ecological classifications help to identify possible ways in nature to adapt organisms to the environment.

2.5. Active and hidden life

Metabolism is one of the most important properties of life, which determines the close material-energy connection of organisms with the environment. Metabolism shows a strong dependence on the conditions of existence. In nature, we observe two main states of life: active life and rest. With active life, organisms feed, grow, move, develop, multiply, being characterized by an intensive metabolism. Rest can be different in depth and duration, while many functions of the body are weakened or not performed at all, since the level of metabolism falls under the influence of external and internal factors.

In a state of deep rest, i.e., a reduced material-energy metabolism, organisms become less dependent on the environment, acquire a high degree resilience and are able to endure conditions that they could not withstand with active life. These two states alternate in the life of many species, being an adaptation to habitats with an unstable climate, sharp seasonal changes, which is typical for most of the planet.

With a deep suppression of metabolism, organisms may not show visible signs of life at all. The question of whether a complete stop of metabolism is possible with a subsequent return to active life, that is, a kind of "resurrection from the dead", has been discussed in science for more than two centuries.

First time phenomenon imaginary death was discovered in 1702 by Anthony van Leeuwenhoek, the discoverer of the microscopic world of living beings. The “animalcules” (rotifers) observed by him, when the drops of water dried, wrinkled, looked dead and could remain in this state for a long time (Fig. 8). Placed again in the water, they swelled and moved to an active life. Leeuwenhoek explained this phenomenon by the fact that the shell of the "animalcules" apparently "does not allow the slightest evaporation" and they remain alive in dry conditions. However, a few decades later, natural scientists were already arguing about the possibility that "life can be completely stopped" and restored again "in 20, 40, 100 years or more."

In the 70s of the XVIII century. the phenomenon of "resurrection" after drying was discovered and confirmed by numerous experiments in a number of other small organisms - wheaten eels, free-living nematodes and tardigrades. J. Buffon, repeating the experiments of J. Needham with acne, argued that "these organisms can be made to die and come to life as many times as you like in a row." L. Spallanzani was the first to draw attention to the deep dormancy of seeds and spores of plants, regarding it as their preservation in time.

Rice. eight. Rotifer Philidina roseola at different stages of drying (according to P. Yu. Schmidt, 1948):

1 – active; 2 - starting to shrink 3 – completely reduced before drying; 4 - in a state of suspended animation

In the middle of the XIX century. it was convincingly established that the resistance of dry rotifers, tardigrades and nematodes to high and low temperatures, lack or absence of oxygen increases in proportion to the degree of their dehydration. However, the question remained open whether there was a complete interruption of life or only its deep oppression. In 1878, Claude Bernal put forward the concept "hidden life" which he characterized by the cessation of metabolism and "a break in the relationship between the being and the environment."

This issue was finally resolved only in the first third of the 20th century with the development of deep vacuum dehydration technology. The experiments of G. Rama, P. Becquerel and other scientists showed the possibility complete reversible cessation of life. In a dry state, when no more than 2% of water remained in the cells in a chemically bound form, such organisms as rotifers, tardigrades, small nematodes, seeds and spores of plants, spores of bacteria and fungi survived in liquid oxygen (-218.4 ° C ), liquid hydrogen (-259.4 °C), liquid helium (-269.0 °C), i.e. temperatures close to absolute zero. At the same time, the contents of the cells harden, there is not even a thermal movement of molecules, and any metabolism, of course, is stopped. Once placed under normal conditions, these organisms continue to develop. In some species, stopping metabolism at ultra-low temperatures is possible even without drying, provided that water freezes not in a crystalline, but in an amorphous state.

The complete temporary suspension of life is called suspended animation. The term was proposed by W. Preyer back in 1891. In a state of suspended animation, organisms become resistant to a wide variety of influences. For example, tardigrades withstood ionizing radiation of up to 570 thousand roentgens for 24 hours in an experiment. Dehydrated larvae of one of the African chironomus mosquitoes - Polypodium vanderplanki - retain the ability to revive after exposure to a temperature of +102 ° C.

The state of anabiosis greatly expands the boundaries of life preservation, including in time. For example, in the thickness of the glacier of Antarctica, during deep drilling, microorganisms (spores of bacteria, fungi and yeast) were found, which subsequently developed on ordinary nutrient media. The age of the corresponding ice horizons reaches 10–13 thousand years. Spores of some viable bacteria have also been isolated from deeper layers hundreds of thousands of years old.

Anabiosis, however, is a fairly rare occurrence. It is far from possible for all species and is an extreme state of rest in wildlife. Its necessary condition is the preservation of intact thin intracellular structures (organelles and membranes) during drying or deep cooling of organisms. This condition is not feasible for most species that have a complex organization of cells, tissues and organs.

The ability to anabiosis is found in species that have a simple or simplified structure and live in conditions of sharp fluctuations in humidity (drying shallow water bodies, upper layers of soil, cushions of mosses and lichens, etc.).

Much more widespread in nature are other forms of dormancy associated with a state of reduced vital activity as a result of partial inhibition of metabolism. Any degree of reduction in the level of metabolism increases the resistance of organisms and allows more economical use of energy.

Forms of rest in a state of reduced vital activity are divided into hypobiosis and cryptobiosis, or compelled rest and physiological rest. In hypobiosis, inhibition of activity, or torpor, occurs under the direct pressure of unfavorable conditions and stops almost immediately after these conditions return to normal (Fig. 9). Such suppression of vital processes can occur with a lack of heat, water, oxygen, with an increase in osmotic pressure, etc. In accordance with the leading external factor of forced rest, cryobiosis(at low temperatures), anhydrobiosis(with lack of water), anoxybiosis(under anaerobic conditions), hyperosmobiosis(with a high salt content in water), etc.

Not only in the Arctic and Antarctic, but also in the middle latitudes, some frost-resistant species of arthropods (springtails, a number of flies, ground beetles, etc.) hibernate in a state of stupor, quickly thawing and turning to activity under the rays of the sun, and then again lose their mobility when the temperature drops . Plants sprouting in spring stop and resume growth and development following cooling and warming. After a rainfall, bare soil often turns green due to the rapid reproduction of soil algae, which were in forced rest.

Rice. 9. Pagon - a piece of ice with freshwater inhabitants frozen into it (from S. A. Zernov, 1949)

The depth and duration of suppression of metabolism during hypobiosis depends on the duration and intensity of the inhibitory factor. Forced rest occurs at any stage of ontogeny. The benefits of hypobiosis are the rapid restoration of active life. However, this relatively unstable state of organisms can be damaging for a long time due to the imbalance of metabolic processes, depletion of energy resources, accumulation of underoxidized metabolic products, and other unfavorable physiological changes.

Cryptobiosis is a fundamentally different type of dormancy. It is associated with a complex of endogenous physiological rearrangements that occur in advance, before the onset of adverse seasonal changes, and the organisms are ready for them. Cryptobiosis is an adaptation primarily to the seasonal or other periodicity of abiotic environmental factors, their regular cyclicity. It is part of the life cycle of organisms; it does not occur at any, but at a certain stage of individual development, timed to coincide with the experience of critical periods of the year.

The transition to a state of physiological rest takes time. It is preceded by the accumulation of reserve substances, partial dehydration of tissues and organs, a decrease in the intensity of oxidative processes, and a number of other changes that generally lower tissue metabolism. In a state of cryptobiosis, organisms become many times more resistant to adverse effects external environment (Fig. 10). In this case, the main biochemical rearrangements are in many respects common for plants, animals and microorganisms (for example, switching of metabolism to a different degree to the path of glycolysis due to reserve carbohydrates, etc.). The way out of cryptobiosis also requires time and energy and cannot be carried out simply by stopping the negative effect of the factor. This requires special conditions that are different for different species (for example, freezing, the presence of drip-liquid water, a certain length of daylight hours, a certain quality of light, mandatory temperature fluctuations, etc.).

Cryptobiosis as a survival strategy in periodically unfavorable conditions for active life is a product of long evolution and natural selection. It is widely distributed in nature. The state of cryptobiosis is typical, for example, for plant seeds, cysts and spores of various microorganisms, fungi, algae. Diapause of arthropods, hibernation of mammals, deep dormancy of plants are also different types of cryptobiosis.

Rice. ten. An earthworm in a state of diapause (according to V. Tishler, 1971)

The states of hypobiosis, cryptobiosis and anabiosis ensure the survival of species in natural conditions of different latitudes, often extreme ones, allow organisms to survive for long unfavorable periods, settle in space and in many ways push the boundaries of the possibility and spread of life in general.

1. Habitat: water, land-air, soil and environment as a living organism.

2. Conditions and environmental factors: abiotic, biotic and anthropogenic factors.

1. There are four main habitats on Earth, developed and inhabited by organisms. It - water, land-air, soil and, finally, the environment formed by themselves living organisms . Each of them has its own specific living conditions.

The aquatic environment is characterized by a liquid state of aggregation and, depending on the depth, can be either aerobic (surface layers of various water bodies), and anaerobic (at great depths of the ocean, in water bodies with high temperatures). This environment is denser than air, more favorable from the standpoint of the production of water by the body and its preservation in it, and is also richer in food resources. Life originated in the aquatic environment in the distant geological past.

The forms of organisms living in water are diverse; among them there are those that breathe oxygen both dissolved in water and contained in the atmosphere, as well as anaerobic organisms. Various protozoa, algae, fish, arthropods, molluscs, echinoderms and representatives of other types and classes of the animal and plant world live in this environment.

Ground-air environment in the course of evolution it was mastered later than water, it is more complex and requires a higher level of organization of the living. Here, air temperature, oxygen content, humidity, weather, light intensity play an essential role, which is especially important for plants. it aerobic an environment in which an intensive exchange of gases and water is carried out, which is necessary for the life of living beings. Therefore, organisms living in this environment are adapted to obtaining and maintaining moisture, and animals have the ability to move quite quickly and actively. Birds, many species of arthropods, mammals, various types of angiosperms, etc. live in this environment.

The soil as a habitat for many micro- and macro-organisms, as well as plant roots, has its own ecological characteristics. In the soil, factors such as structure, chemical composition and moisture are of paramount importance, but light or sharp temperature fluctuations practically do not play a role. The inhabitants of the soil environment are called edophobic or geobionts . Here you can meet various representatives of the type of protozoa, various algae, fungi, various types of various worms, mollusks, various representatives of higher animals. Soil is a substrate for various types of higher plants, which are characterized by a terrestrial environment.

2. Conditions and environmental factors- interrelated concepts that characterize the habitat of organisms. The environmental conditions are usually defined as environmental factors that have an impact (positive or negative) on the existence and geographical distribution of living beings.

Environmental factors are very diverse both in nature and in their impact on living organisms. Conventionally, all environmental factors are divided into three main groups - abiotic, biotic and anthropogenic.

Abiotic factors called the whole set of factors of the inorganic environment that affect the life and distribution of animals and plants. This is, first of all climatic:

sunlight, temperature, humidity,

and local:

topography, soil properties, salinity, currents, wind, radiation, etc.

These factors can affect organisms directly, i.e. directly, as light or heat, or indirectly, such as relief, which determines the action of direct factors - illumination, moisture, wind, etc.

Biotic factors- this is various forms of influence of living organisms on each other and on the environment. Biotic relationships are extremely complex and idiosyncratic and can also be direct and indirect.

Anthropogenic factors- it's all those forms of human activity that affect the natural natural environment, changing the living conditions of living organisms, or directly affect individual species of plants and animals.

In turn, organisms themselves can influence the conditions of their existence. For example, the presence of vegetation cover moderates diurnal temperature fluctuations near the Earth's surface, fluctuations in humidity and wind, and also affects the structure and chemical composition of soils.

All environmental factors present in nature affect the life of organisms in different ways and have varying degrees of importance for individual species. At the same time, the set of factors and their significance for organisms depend on the environment.

Habitat organism - a set of abiotic and biotic conditions of its life. The properties of the environment are constantly changing, and organisms are adapting to these changes.

Adaptations to constantly changing (during the day, year, life) environmental conditions are called adaptations. They manifest themselves at all levels of the organization of living things - from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. The study of adaptations of organisms and ecosystems to living conditions is one of the main tasks of ecology.

The impact of the environment is perceived by organisms through its factors, which are called environmental. Environmental factors These are certain conditions and elements of the environment that have a specific effect on the body. Among the environmental factors on which organisms depend, resources and conditions are distinguished. Organisms use resources by reducing their amount for other organisms.

Resources include food, shelter, good breeding grounds, and so on. Conditions are factors to which organisms are forced to adapt, but usually cannot influence them. One and the same environmental factor can be both a resource for some and a condition for other species. So light is a vital energy resource for photosynthetic plants (leaf mosaic is a device that allows the plant to use light energy to the fullest), and for animals with vision it is a necessary condition that allows them to see surrounding objects and navigate in space. Water for many organisms can also be both a condition of life and a resource.

The diversity of environmental factors Russian scientist E.A. Eversman in his work "Natural History of the Orenburg Region" (1840) divided into abiotic and biotic. Later, the concept of anthropogenic factors was added to them.

Abiotic factors call the whole set of factors. Among them, physical, chemical and edaphic factors are distinguished.

Physical factors- their source is a physical phenomenon or state. These include: intensity, quality and duration of lighting; temperature, water flow, wind, air humidity, atmospheric pressure, pressure of the water column, as well as topographic characteristics (height, slope exposure and steepness).

Chemical Factors- determined by the chemical composition of the organism's habitat. For example, air composition, water salinity, pH reaction, cation and anion content, oxygen saturation, etc. Most importance Six elements play a role in life: carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. The closed paths along which chemical elements circulate from the external environment to organisms and back to the external environment are called biogeochemical cycles.

Edaphic factors, i.e. soil - this is a combination of chemical, physical and mechanical properties of soils and rocks that affect the organisms living in them and the root systems of plants. Although the soil is considered as an abiotic environmental factor, it is more correct to consider it the most important link between biotic and abiotic components of terrestrial ecosystems.

The composition of the soil includes four major structural components: the mineral base - an inorganic component that was formed from the parent rock as a result of its weathering (usually 50-60% of the total soil composition), organic matter (up to 10%), air (15-25%) and water (25-35%). organic matter soil is formed by the decomposition of dead organisms, their parts and excrement. Incompletely decomposed organic matter is called bedding, and the end product of decomposition is humus, an amorphous substance in which it is no longer possible to recognize the original material. Thanks to its chemical and physical properties humus improves soil structure and aeration, increases the ability to retain water and nutrients.

Soil air is located in the pores between soil particles. Free gas exchange occurs between the soil and the atmosphere, as a result of which the air of both environments has a similar composition. However, in the air of the soil, due to the respiration of the organisms inhabiting it, there is somewhat less oxygen and more carbon dioxide than in atmospheric air.

Water, like air, is in the pores. Part of it can freely seep down to the groundwater level - gravitational water. The other part of the water is held around individual soil particles in the form of a thin, firmly bound film - hygroscopic water. This water is the least available for plant roots. Hygroscopic water gradually turns into capillary water, which is held between soil particles by surface tension forces.

Plants easily absorb this water, so capillary water plays the most important role in their regular water supply. The total amount of water that can be held by the soil is called field capacity.

Water is necessary for all soil organisms and enters living cells by osmosis. Water is important as a solvent for nutrients and respiratory gases absorbed from the aqueous solution by plant roots. It takes part in the processes of destruction of the parent rock underlying the soil.

Biotic factors - a set of influences of the vital activity of some organisms on the vital activity of others, as well as on the non-living environment. In turn, biotic factors can be divided into 2 groups: 1) factors of interaction between individuals of the same species; 2) factors of interaction between individuals of different species. Intraspecific interactions are made up of a group effect (association of animals of the same species into groups of two or more individuals) and a mass effect (caused by overpopulation of the environment). These effects are currently referred to as demographic factors, they characterize the dynamics of population size, which is based on intraspecific competition, manifested in the struggle for food, territory, breeding partners, etc.

Interspecies relationships much more varied. Two species living side by side can be indifferent to each other, influence favorably or unfavorably. Possible types of combinations are presented in Table 1.

Table 1

Classification of biotic interactions between populations of two species

(according to Y. Odum, 1986)

Type of interaction			General nature of interaction
Neutralism			The cohabitation of two species in the same territory does not entail either positive or negative consequences for them. The species are not directly related or even in contact. For example, squirrels and moose in the forest, monkeys and elephants. Such relationships are characteristic of communities rich in species.
Interspecies competition			Any interaction between populations that adversely affects their growth and survival. The result of interspecific competition may be either the mutual adaptation of two species, or the replacement of one species by another and its resettlement or transition to another food. For example, the distribution of ungulates by food tiers in the savannah (giraffe, antelope, rhinoceros, elephant, zebra). Or a tier of shade-loving and light-loving plants in the forest.
Amensalism			Population 2 suppresses population 1, but is itself not adversely affected. Usually, in this case, the growth of one species is inhibited by the products of the excretion of another. This phenomenon is best studied in plants that release toxic substances in the fight against competitors - allelopathy. It is very common in the aquatic environment: blue-green algae cause water blooms, thereby poisoning the aquatic fauna.
Predation			Predator 1 individuals are usually larger than prey 2 individuals. Predators are animals that feed on other animals that they catch and kill. Predators are characterized by hunting behavior (sharks, wolves, lions, snakes, etc.). In other cases, the abundance of prey, their small size and easy accessibility (insects, plankton) turns the activity of predators (birds, whales) into a simple “gathering” of prey. Commensalism			Population 1 benefits from association with population 2, for which this association is indifferent. The simplest type of positive interaction. Most often, in this case, the organism uses the dwelling of another organism, without causing him any harm or benefit. For example, in the oceans and seas, a mass of small organisms settle in each shell, which receive shelter here, but do no harm or benefit to the owner.
Protocooperation			The interaction is favorable for both species, but not necessarily. For example, crabs and sea anemones: the crab “plants” the coelenterates on its back, which masks and protects it (having stinging cells), and it, in turn, receives pieces of food from the crab and uses it as a vehicle.
Mutualism (symbiosis)			The interaction is favorable for both species and is mandatory. The most important symbiotic systems arise between autotrophs and heterotrophs. For example, nitrogen-fixing bacteria and legumes; ruminants and bacteria living in their rumen. A well-known example is the symbiosis of an algae and a fungus, resulting in the formation lichens. In this table, "0" means the absence of any influence; "+" - the species benefits from the interaction; "-" - the species is harmed by the interaction. Interspecific relationships underlie the existence of biotic communities. According to their action, biotic and abiotic factors can be divided into direct acting(light, heat, soil fertility - for plants) and indirectly acting(they are for animals through the food chain). The place of the species in nature, mainly in the biocenosis, including both the position in space and the functional role in the community, as well as the attitude to the abiotic conditions of existence, is called ecological niche . It is important to emphasize that an econiche is not just the physical space occupied by an organism, but also its role in the community. Y. Odum figuratively presented the ecological niche as the "profession" of the organism, and its habitat - the "address". Anthropogenic factors are human factors. They can also be divided into positive and negative. Positive- reproduction of natural resources, restoration of groundwater reserves, field-protective and water-protective afforestation, land reclamation at the site of mineral development, etc. Negative(negative) - deforestation, depletion of fresh water, salinization and desertification of land, destruction or reduction in the number of animals and plants, and much more. The most important and most common type of negative human impact on the biosphere is pollution- admission to environment any solid, liquid and gaseous substances, energies (sounds, noises, radiation) or organisms (biological pollution) in quantities harmful to the state of ecosystems and human health. According to the types of pollution, chemical, physical and biological pollution is distinguished. In terms of scale and distribution - local, regional and global. Environmental scientists give priority to the following pollutants: - sulfur dioxide(causes the so-called acid rain); - heavy metals(lead, cadmium, mercury); - carcinogens(benz(a)pyrene); - oil and oil products(in the oceans); - pesticides(in rural areas); - carbon monoxide and nitric oxide(in cities). The whole range of anthropogenic factors is studied by applied ecology. Most factors change qualitatively and quantitatively over time. So, climatic factors change during the day, season, year, year by year. Factors that change regularly over time are called periodical. These include climatic, hydrographic (ebb and flow, ocean currents), and other factors. Unexpected factors - non-periodic(volcanic eruption, predator attack, etc.). Such a subdivision is very important in studying the adaptability of organisms to living conditions, i.e. adaptation. The main adaptations of organisms are hereditarily determined. They were formed during the evolutionary development of organisms and changed along with the variability of environmental factors. Organisms are adapted to constantly operating periodic factors, but among them it is important to distinguish between primary and secondary ones. Primary factors existed on Earth even before the emergence of life (temperature, light, ebbs and flows, etc.). Adaptations to them are the most ancient and most perfect. Secondary periodic factors are a consequence and change of the primary ones (air humidity, depending on temperature; plant food, depending on the cyclicity in the development of plants, etc.). Adaptations to them arose later and are not always clearly expressed. Under normal conditions, only periodic factors should act, and non-periodic ones should be absent. Non-periodic factors can cause disease and death of the body (poisoning of insect pests, pathogenic bacteria and viruses). But prolonged exposure to these factors can cause adaptation to them (insects have adapted to DDT, bacteria and viruses to antibiotics). Limiting factors limit the development of the species due to their lack or, conversely, excess in comparison with the need. Also called limiting factors. For the first time, the German agricultural chemist J. Liebig pointed out the importance of these factors in the middle of the 19th century. He installed law of the minimum : the yield (production) depends on the factor that is at a minimum. For example, if beneficial components are generally balanced in the soil and only phosphorus is contained in a minimal amount, then this can reduce the yield. But it turned out that an excess of a substance can also reduce the yield and, in general, the yield depends on the combined action of all factors in the life of the plant, so the law of the minimum has a very limited effect. Differences in cumulative and isolated actions apply to other factors as well. Thus, the effect of low temperatures is exacerbated by wind and humidity. But despite the mutual influence of factors, they cannot replace each other - the law of independence of factors V.R. Williams : living conditions are equivalent, none of the factors can be replaced by another. Thus, the action of moisture cannot be replaced by the action of carbon dioxide or sunlight. Most fully and in the most general form, the complexity of the influence of environmental factors on the body reflects W. 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 tolerance limits of a given organism. These limits are called limits of tolerance. Organisms living in a narrow range between tolerance limits - stenobionts. And those who are able to live in a wide range of tolerance - eurybionts. Thus, not a single organism in nature exists without connections with its environment and with other organisms. These connections are the main condition for the functioning of ecosystems. In the process of interrelations, energy is absorbed and dissipated and, ultimately, the environment-forming, environmental protection and environment-stabilizing functions of ecosystems are carried out. Odum Yu. Ecology / Per. from English. 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The concept of succession. The concept of habitat. Types of habitats. Ecological factors and their classification. abiotic factors. biotic factors. Examples of positive, negative and neutral interactions. anthropogenic factors. limiting factors. The concept of adaptation. The concept and types of environmental monitoring. What is a lichen. Lichen types. Ecological groups of lichens. Lichen zones in cities.