Characteristics of abiotic factors and their classification. Abiotic, biotic and anthropogenic factors

14.10.2019

Environments are defined climatic conditions, as well as soil and water.

Classification

There are several classifications of abiotic factors. One of the most popular divides them into the following components:

physical factors (barometric pressure, humidity);
chemical factors (atmospheric composition, mineral and organic matter in the soil, pH level in the soil and others)
mechanical factors (wind, landslides, water and soil movements, terrain, etc.)

Abiotic factors environment significantly influence the distribution of species and determine their range, i.e. a geographical area that is the habitat of certain organisms.

Temperature

Special significance is given to temperature, since this is the most important indicator. Depending on temperature, abiotic environmental factors differ in thermal zones with which the life of organisms in nature is associated. These are cold, temperate, tropical, and the temperature that is favorable for the life of organisms is called optimal. Almost all organisms are able to live in the range of 0°-50°C.

Depending on their ability to exist in different temperature conditions, they are classified as:

eurythermic organisms adapted to conditions of sharp temperature fluctuations;
stenothermic organisms that exist in a narrow temperature range.

Eurythermal organisms are considered to be organisms that live primarily in areas where a continental climate predominates. These organisms are able to withstand severe temperature fluctuations (diptera larvae, bacteria, algae, helminths). Some eurythermal organisms can enter a state of hibernation if the temperature factor “tightens”. Metabolism in this state is significantly reduced (badgers, bears, etc.).

Stenothermic organisms can be found among both plants and animals. For example, most marine animals survive at temperatures up to 30°C.

Animals are divided according to their ability to maintain their own thermoregulation, i.e. constant body temperature, in the so-called poikilothermic and homeothermic. The former can change their temperature, while for the latter it is always constant. All mammals and a number of birds are homeothermic animals. Poikilothermic organisms include all organisms, except some species of birds and mammals. Their body temperature is close to the ambient temperature. During the course of evolution, animals classified as homeothermic have adapted to protect themselves from the cold (hibernation, migration, fur, etc.).

Light

Abiotic environmental factors are light and its intensity. Its importance is especially great for photosynthetic plants. The level of photosynthesis is affected by the intensity, qualitative composition of light, and the distribution of light over time. However, bacteria and fungi are known that can multiply for a long time in complete darkness. Plants are divided into light-loving, heat-tolerant and heat-loving.

For many animals, the length of daylight hours is important, which affects sexual function, increasing it during long daylight hours and inhibiting it during short ones (autumn or winter).

Humidity

Humidity is a complex factor and represents the amount of water vapor in the air and water in the soil. The lifespan of cells, and, accordingly, the entire organism, depends on the level of humidity. Soil moisture is affected by the amount of precipitation, the depth of water in the soil and other conditions. Moisture is necessary to dissolve minerals.

Abiotic factors of the aquatic environment

Chemical factors are not inferior in importance to physical factors. A large role belongs to the gas and composition of the aquatic environment. Almost all organisms require oxygen, and a number of organisms require nitrogen, hydrogen sulfide or methane.

Physical abiotic environmental factors are gas composition, which is extremely important for those living beings that live in the aquatic environment. The waters of the Black Sea, for example, contain a lot of hydrogen sulfide, which is why this basin is considered not very favorable for many organisms. Salinity is an important component of the aquatic environment. Most aquatic animals live in salt waters, fewer live in fresh waters, and even fewer live in slightly brackish waters. The distribution and reproduction of aquatic animals is influenced by the ability to maintain the salt composition of the internal environment.

Target: reveal the features of abiotic environmental factors and consider their impact on living organisms.

Tasks: introduce students to environmental environmental factors; reveal the features of abiotic factors, consider the influence of temperature, light and moisture on living organisms; identify different groups of living organisms depending on the influence of different abiotic factors on them; execute practical task by definition of groups of organisms, depending on the abiotic factor.

Equipment: computer presentation, group assignments with pictures of plants and animals, practical assignment.

PROGRESS OF THE LESSON

All living organisms inhabiting the Earth are influenced by environmental factors.

Environmental factors- these are individual properties or elements of the environment that affect living organisms directly or indirectly, at least during one of the stages of individual development. Environmental factors are manifold. There are several qualifications, depending on the approach. This is based on the effect on the life activity of organisms, the degree of variability over time, and the duration of action. Let's consider the classification of environmental factors based on their origin.

We will consider the influence of the first three abiotic factors environment, since their influence is more significant - temperature, light and humidity.

For example, in the May beetle, the larval stage takes place in the soil. It is influenced by abiotic environmental factors: soil, air, indirectly humidity, chemical composition of the soil - it is not affected by light at all.

For example, bacteria are able to survive in the most extreme conditions - they are found in geysers, hydrogen sulfide springs, very salty water, at the depths of the World Ocean, very deep in the soil, in the ice of Antarctica, on the highest peaks (even Everest 8848 m), in the bodies of living organisms.

TEMPERATURE

Most species of plants and animals are adapted to a fairly narrow range of temperatures. Some organisms, especially in a state of rest or suspended animation, are able to withstand fairly low temperatures. Temperature fluctuations in water are usually less than on land, so the limits of temperature tolerance are aquatic organisms worse than those on land. The intensity of metabolism depends on temperature. Basically, organisms live at temperatures from 0 to +50 on the surface of sand in the desert and up to -70 in some areas Eastern Siberia. The average temperature range is from +50 to –50 in terrestrial habitats and from +2 to +27 in the oceans. For example, microorganisms can withstand cooling down to –200, certain types of bacteria and algae can live and reproduce in hot springs at temperatures of + 80, +88.

Distinguish animal organisms:

with a constant body temperature (warm-blooded);
with unstable body temperature (cold-blooded).

Organisms with unstable body temperature (fish, amphibians, reptiles)

In nature, temperature is not constant. Organisms that live in temperate latitudes and are exposed to temperature fluctuations are less able to tolerate constant temperatures. Sharp fluctuations - heat, frost - are unfavorable for organisms. Animals have developed adaptations to cope with cooling and overheating. For example, with the onset of winter, plants and animals with unstable body temperatures enter a state of winter dormancy. Their metabolic rate decreases sharply. In preparation for winter, a lot of fat and carbohydrates are stored in animal tissues, the amount of water in fiber decreases, sugars and glycerin accumulate, which prevents freezing. This increases the frost resistance of wintering organisms.

In the hot season, on the contrary, physiological mechanisms are activated that protect against overheating. In plants, moisture evaporation through the stomata increases, which leads to a decrease in leaf temperature. In animals, water evaporation increases through the respiratory system and skin.

Organisms with a constant body temperature. (birds, mammals)

These organisms underwent changes in the internal structure of their organs, which contributed to their adaptation to constant body temperature. This, for example, is a 4-chambered heart and the presence of one aortic arch, ensuring complete separation of arterial and venous blood flow, intensive metabolism due to the supply of tissues with arterial blood saturated with oxygen, feathers or hair covering the body, which helps retain heat, well-developed nervous activity) . All this allowed representatives of birds and mammals to remain active during sudden temperature changes and to master all habitats.

In natural conditions, the temperature very rarely remains at a level favorable for life. Therefore, plants and animals develop special adaptations that weaken sudden temperature fluctuations. Animals such as elephants have larger ears than their ancestor, the mammoth, which lived in cold climates. In addition to the hearing organ, the auricle serves as a thermostat. To protect against overheating, plants develop a waxy coating and a thick cuticle.

LIGHT

Light provides all life processes occurring on Earth. For organisms, the wavelength of the perceived radiation, its duration and intensity of exposure are important. For example, in plants, a decrease in day length and light intensity leads to autumn leaf fall.

By plant's relationship to light divided into:

light-loving– have small leaves, highly branched shoots, a lot of pigment – cereals. But increasing the light intensity beyond the optimum suppresses photosynthesis, so it is difficult to obtain good harvests in the tropics.
shade-loving e - have thin leaves, large, arranged horizontally, with fewer stomata.
shade-tolerant– plants capable of living in conditions of good lighting and shading

The duration and intensity of exposure to light plays an important role in regulating the activity of living organisms and their development. – photoperiod. In temperate latitudes, the development cycle of animals and plants is confined to the seasons of the year, and the signal for preparation for temperature changes is the length of daylight hours, which, unlike other factors, always remains constant in a certain place and at a certain time. Photoperiodism is a trigger mechanism that includes physiological processes that lead to plant growth and flowering in the spring, fruiting in the summer, and shedding of leaves in the fall in plants. In animals, the accumulation of fat by autumn, the reproduction of animals, their migration, the migration of birds and the onset of the resting stage in insects. ( Student message).

In addition to seasonal changes, there are also daily changes in lighting conditions; the change of day and night determines the daily rhythm of the physiological activity of organisms. An important adaptation that ensures the survival of an individual is a kind of “biological clock”, the ability to sense time.

Animals, whose activity depends depending on the time of day, come with day, night and twilight lifestyle.

HUMIDITY

Water is a necessary component of the cell, therefore its quantity in certain habitats is a limiting factor for plants and animals and determines the nature of the flora and fauna of a given area.

Excess moisture in the soil leads to waterlogging and the appearance of marsh vegetation. Depending on soil moisture (amount of precipitation), the species composition of vegetation changes. Broadleaf forests are replaced by small-leaved, then forest-steppe vegetation. Next is low grass, and at 250 ml per year - desert. Precipitation may not fall evenly throughout the year; living organisms have to endure long-term droughts. For example, plants and animals of savannas, where the intensity of vegetation cover, as well as the intensive nutrition of ungulates, depends on the rainy season.

In nature, daily fluctuations in air humidity occur, which affect the activity of organisms. There is a close relationship between humidity and temperature. Temperature has a greater effect on the body when humidity is high or low. Plants and animals have developed adaptations to different humidity levels. For example, in plants, a powerful root system is developed, the leaf cuticle is thickened, the leaf blade is reduced or turned into needles and spines. In saxaul, photosynthesis occurs in the green part of the stem. Plant growth stops during drought. Cacti store moisture in the expanded part of the stem; needles instead of leaves reduce evaporation.

Animals have also developed adaptations that allow them to tolerate a lack of moisture. Small animals - rodents, snakes, turtles, arthropods - obtain moisture from food. The source of water can be a fat-like substance, for example in a camel. In hot weather, some animals - rodents, turtles - hibernate, which lasts for several months. By the beginning of summer, after a short flowering, ephemeral plants can shed their leaves, the above-ground parts die off, and thus experience a period of drought. At the same time, the bulbs and rhizomes are preserved until the next season.

By plant's relationship to water divide:

aquatic plants high humidity;
semi-aquatic plants, terrestrial-aquatic;
land plants;
plants of dry and very dry places, live in places with insufficient moisture and can tolerate short-term drought;
succulents– juicy, accumulate water in the tissues of their bodies.

In relation to to water animals divide:

moisture-loving animals;
intermediate group;
dry-loving animals.

Types of adaptations of organisms to fluctuations in temperature, humidity and light:

warm-blooded – maintaining a constant body temperature by the body;
hibernation – prolonged sleep of animals in the winter season;
suspended animation – a temporary state of the body in which life processes are slowed down to a minimum and all visible signs of life are absent (observed in cold-blooded animals and in animals in winter and during hot periods);
frost resistance b – the ability of organisms to tolerate negative temperatures;
state of rest - adaptive property of a perennial plant, which is characterized by the cessation of visible growth and vital activity, the death of ground shoots in herbaceous forms of plants and the fall of leaves in woody forms;
summer peace– an adaptive property of early flowering plants (tulip, saffron) in tropical regions, deserts, semi-deserts.

(Messages from students.)

Let's do it conclusion, for all living organisms, i.e. Plants and animals are affected by abiotic environmental factors (factors of inanimate nature), especially temperature, light and moisture. Depending on the influence of factors of inanimate nature, plants and animals are divided into different groups and they develop adaptations to the influence of these abiotic factors.

Practical tasks in groups:(Appendix 1)

1. TASK: Of the animals listed, name the ones that are cold-blooded (i.e., with an unstable body temperature).

2. TASK: Of the animals listed, name those that are warm-blooded (i.e., with a constant body temperature).

3. TASK: select from the proposed plants those that are light-loving, shade-loving and shade-tolerant and write them down in the table.

4. TASK: select animals that lead a diurnal, nocturnal and twilight lifestyle.

5. TASK: select plants related to different groups in relation to water.

6. TASK: select animals belonging to different groups in relation to water.

Assignments on the topic “abiotic environmental factors”, answers(

The most important abiotic factors and adaptation of living organisms to them

Describe light as an abiotic factor. Give a classification of ecological classes of plants in relation to light.

Describe temperature as an abiotic factor. Explain the ecological meaning of Bergman and Allen's rules (give examples).

What is the difference between poikilothermic and homeothermic organisms?

How is A. Hopkins' bioclimatic law formulated? Give it an ecological explanation.

Describe moisture as an abiotic factor. Give examples of moisture- and dry-loving plants and animals, as well as those that prefer moderate humidity.

Among the main abiotic factors, let us consider light, temperature And humidity.

Light.
At one time, the French astronomer Camille Flammarion (1842-1925) wrote: “We don’t think about it, but everything that walks, moves, lives on our planet is a child of the Sun.” .

Indeed, only under the influence of light is the most important process of photosynthesis carried out in the biosphere, which general view can be represented as follows:

Where A is an electron donor.

In green plants (higher plants and algae), the electron donor is water (oxygen), therefore oxygen is formed as a result of photosynthesis:

In bacteria, the role of electron donor can be performed, for example, by hydrogen sulfide (sulfur) and organic substances. So, in green and purple sulfur bacteria the following process occurs:

With regard to light, organisms face a dilemma: on the one hand, direct exposure to light on a cell can be fatal to the organism, on the other hand, light serves as a primary source of energy, without which life is impossible.

Visible light has a mixed effect on organisms: red rays have a thermal effect; blue and violet rays - change the speed and direction of bio chemical reactions. In general, light affects the rate of growth and development of plants, the intensity of photosynthesis, the activity of animals, causes changes in humidity and temperature of the environment, and is an important factor ensuring daily and seasonal biological cycles. Each habitat is characterized by a certain light regime, determined intensity (strength), quantity and quality of light.

Intensity (strength) light is measured by energy per unit area per unit time: J/m2Hs; J/cm2Hs. This factor is strongly influenced by terrain features. Direct light is the most intense, but plants use diffused light more fully.

Amount of light determined by total radiation. From the poles to the equator the amount of light increases. To determine the light regime, it is necessary to take into account the amount of reflected light, the so-called albedo. Albedo (from Latin albus - white) - the reflectivity of the surfaces of various bodies - is expressed as a percentage of the total radiation and depends on the angle of incidence of the rays and the properties of the reflecting surface. For example, albedo pure snow- 85%, contaminated - 40-50%, chernozem soil - 5-14%, light sand - 35-45%, forest canopy - 10-18%, green maple leaves - 10%, yellowed autumn leaves - 28%.

In relation to light as an environmental factor, the following groups of plants are distinguished: heliophytes (from the Greek helios - sun, phyton - plant), sciophytes (from the Greek skia - shadow) and shade-tolerant plants (facultative heliophytes).

Light plants (heliophytes)- live in open places with good lighting and are rare in the forest zone. The process of photosynthesis begins to dominate over the respiration process only in high light conditions (wheat, pine, larch). The flowers of light-loving plants such as sunflower, salsify, and string turn to follow the sun.

Shade plants (sciophytes)- do not tolerate strong lighting and live under the forest canopy in constant shade (these are mainly forest grasses, ferns, mosses, and oxalis). In clearings under strong light, they show obvious signs of oppression and often die.

Shade-tolerant plants (facultative heliophytes)- can live in good light, but can easily tolerate dark places (most forest plants, meadow plants, forest herbs and shrubs).

Shade-tolerant tree species and shady herbaceous plants are distinguished by a mosaic arrangement of leaves. Eucalyptus leaves have their edges facing the light. In trees, light and shadow leaves (located respectively on the surface and inside the crown) - well-lit and shaded - have anatomical differences. Light leaves are thicker and coarser, and are sometimes shiny, which helps reflect light. Shade leaves are usually matte, hairless, thin, with a very delicate cuticle or without it at all (the cuticle is the outer film covering the epidermis).

In the forest, shade-tolerant trees form densely closed stands. Even more shade-tolerant trees and shrubs grow under their canopy, and below that there are shady shrubs and herbs. The picture shows two pine trees: one of them grew in an open space with good lighting (1), and the other in a dense forest (2).

Light is of greatest importance as a means of orientation in the life of animals. Already in the simplest organisms light-sensitive organelles appear. Thus, green euglena reacts to the degree of illumination in the environment with the help of a light-sensitive “eye”. Starting with the coelenterates, almost all animals develop light-sensitive organs - eyes, which have one or another structure.

Bioluminescence called the ability of living organisms to glow. This occurs as a result of the oxidation of complex organic compounds with the participation of catalysts, usually in response to irritations coming from external environment. Light signals emitted by fish, cephalopods and other aquatic organisms, as well as some organisms of the terrestrial-air environment (for example, beetles of the firefly family), serve to attract individuals of the opposite sex, lure prey or scare away predators, orientate themselves in a school, etc.

An important environmental factor is temperature.

Temperature.
One of the most important factors determining the existence, development and distribution of organisms around the globe is temperature. Not only the absolute amount of heat is important, but also its temporal distribution, i.e. the thermal regime.
Plants do not have their own body temperature: their anatomical, morphological and physiological mechanisms of thermo-
Regulations are aimed at protecting the body from the harmful effects of unfavorable temperatures.

In the zone of high temperatures with low humidity (tropical and subtropical deserts), a unique morphological type of plants with an insignificant leaf surface or with a complete absence of leaves was historically formed. Many desert plants develop whitish pubescence, which helps reflect sunlight and protects them from overheating (sandy acacia, angustifolia oleagin).

Physiological adaptations of plants that mitigate the harmful effects of high temperatures may include: evaporation intensity - transpiration (from Latin trans - through, spiro- I breathe, I exhale), the accumulation of salts in cells that change the temperature of plasma coagulation, the property of chlorophyll to prevent the penetration of sunlight.

In the animal world, certain morphological adaptations are observed that are aimed at protecting organisms from the unfavorable effects of temperatures. This can be evidenced by the well-known Bergman's rule(1847), according to which Within a species or fairly homogeneous group of closely related species, warm-blooded organisms with larger body sizes are common in colder areas.

Let's try to explain this rule from the standpoint of thermodynamics: heat loss is proportional to the surface of the body of the organism, and not to its mass. The larger the animal and the more compact its body, the easier it is to maintain a constant temperature (less specific energy consumption), and vice versa, the smaller the animal, the greater its relative surface area and heat loss and the higher the specific level of its basal metabolism, i.e. the amount of energy expended by the body of an animal (or human) with complete muscle rest at an ambient temperature at which thermoregulation is most pronounced.

In animals with a constant body temperature in cold climatic zones, there is a tendency to reduce the area of protruding parts of the body (Allen's rule, 1877).

Allen's rule is clearly manifested, for example, when comparing the ear sizes of ecologically similar species: the Arctic fox - an inhabitant of the tundra; common fox - typical for temperate latitudes; Fenech - an inhabitant of the deserts of Africa.
The reaction of animals to the thermal regime is also manifested in changes in the proportions of individual organs and the body (the stoat from the northern regions has an enlarged heart, kidneys, liver and adrenal glands compared to the same animals in areas with higher temperatures). There are exceptions to the rules of Bergman and Allen.

fennec

Depending on the type of heat exchange, two ecological types of animals are distinguished: poikilothermic and homeothermic.

Poikilothermic organisms (from Greek poikilos- diverse) - animals with an unstable level of metabolism, inconsistent body temperature and an almost complete absence of thermoregulation mechanisms (cold-blooded). These include invertebrates, fish, reptiles, amphibians, i.e. most animals, with the exception of birds and mammals.

Their body temperature changes with changes in ambient temperature.

Homeothermic organisms (from Greek homoios- identical) - animals with a higher and more stable level of metabolism, during which thermoregulation is carried out and a relatively constant body temperature is ensured (warm-blooded). These include birds and mammals. Body temperature is maintained at a relatively constant level.

In turn, poikilothermic animals can be divided into eurythermic animals, which lead an active lifestyle in a relatively wide temperature range, and stenothermic animals, which cannot tolerate significant temperature fluctuations.

Mechanisms of thermoregulation are chemical and physical.

The chemical mechanism is determined by the intensity of reactions in the body and is carried out by reflex:

The physical mechanism of thermoregulation is provided by heat-insulating covers (fur, feathers, fat layer), the activity of sweat glands, the evaporation of moisture during breathing, and vascular regulation of blood circulation.

In poikilothermic animals, the metabolic rate is directly proportional to the external temperature; in homeothermic animals, on the contrary, when it decreases, heat loss increases and, in response, metabolic processes are activated and heat production increases. The intensity of metabolism (metabolic processes) during homeothermy is inversely proportional to external temperatures. However, this pattern can be traced only within certain limits. An increase or decrease in temperature relative to a threshold value causes overheating or hypothermia of the animal and ultimately its death.

Heterothermic animals occupy an intermediate position between poikilothermic and homeothermic animals. They have active state a relatively high and constant body temperature is maintained, and when inactive, the body temperature differs little from the external one. In these animals, during hibernation or deep sleep Metabolic levels drop and body temperature only slightly exceeds ambient temperature. Typical representatives of heterothermic animals are ground squirrels, hedgehogs, bats, bears, swifts, platypuses, echidnas, and kangaroos.

Let's consider an example with insects, representatives of poikilothermic animals (see figure).

Curve of P. I. Bakhmetyev

At t° +10°C insects become torpid, at t° 0°C - hypothermia. It continues until the water crystallizes, which is accompanied by a temperature jump. After its sharp increase, processes begin that lead to a deterioration in the physiological state of the body. The physiological state of the insect during the cooling process depends on the rate of temperature decrease. With slow cooling, ice crystals form in the cells, which break their shell. With very rapid cooling, crystallization centers do not have time to form, and a glassy structure is formed. As a result, the cytoplasm is not damaged. Thus, deep but very rapid cooling causes a temporary, reversible suspension of all vital processes of the body. A similar condition, called suspended animation, is observed in viruses, bacteria, invertebrates, amphibians, reptiles, lichens, and mosses. The phenomenon of suspended animation was first discovered and described by A. Leeuwenhoek (1701).

The study of suspended animation gave impetus to the development of various cryotechnology(from Greek kryos- cold, frost), for example, cryopreservation. This method is widely used in biology, medicine, agriculture, in practice long-term storage preserved blood, sperm for artificial insemination of farm animals, various tissues and organs for transplantation (from the Latin transplantatio - transplantation), cultures, bacteria, viruses.

The temperature factor is important in the distribution of living organisms on Earth and thereby determines the population of different natural areas. In 1918 A. Hopkins formed regulated the bioclimatic law . He established that there is a natural, close connection between the development of phenological (seasonal) phenomena and the latitude, longitude and altitude of the area above sea level.
He calculated that As you move north, east and into the mountains, the onset of periodic phenomena in the life of organisms is delayed by 4 days for each degree of latitude, 5 degrees of longitude and approximately 100 m of altitude.

One of the important patterns in the distribution of modern organisms is their bipolarity - the geographical distribution of terrestrial and marine flora and fauna, in which the same species lives in cold and temperate latitudes of both hemispheres, but is absent in the tropical zone (toothless whales, eared seals, etc. .).

An equally important environmental factor is humidity.

Humidity.
Water is the most important environmental factor in the life of living organisms and their permanent component. All living things on Earth include water, for example, jellyfish contain 95-99% water, corn 70%, cereals 87%. Even the granary weevil, which feeds on dry grain, contains 46% water. The human embryo contains 97% water, after birth - 64-77%. In men aged 18 to 50 years, the body contains ~61% water, in women it is 54%.

During his life, a person drinks up to 50-77 m3 of water (per day ~ 2.5-3 liters). In general, a person loses 2-2.5 liters of water per day: 800-

1300 ml in urine, about 200 ml in feces and 600 ml from the surface of the body and during breathing. With the loss of 1-1.5 liters of water, a person becomes thirsty; when 6-8% of moisture from body weight is consumed, he falls into a semi-fainting state; with a deficiency of 10-12%, death occurs.

At different periods of development, the need of plants for water is not the same, especially in different types; It also varies depending on climate and soil type. For example, cereals need less moisture during the period of seed germination and ripening than during their intensive growth. For each phase of growth and stage of development of any type of plant, a critical period can be identified when the lack of water has a particularly negative effect on its life. Environmental humidity is often a factor limiting the number and distribution of organisms around the globe. For example, beech can live on relatively dry soil, but it needs fairly high air humidity. In animals, the permeability of the integument and the mechanisms regulating water metabolism play a very important role.

There is a distinction between absolute air humidity, which is the amount of gaseous water (steam) in grams per 1 m3 of air, and relative humidity. Relative humidity characterizes the degree of saturation of air with water vapor at a certain temperature and is expressed as a percentage as the ratio of absolute humidity to maximum humidity (the mass of water vapor in grams capable of creating complete saturation in 1 m3 of air)

where: r - relative humidity, %;
m is the mass of steam actually contained in 1 m3 of air (absolute humidity), g;
msat - mass of 1 m3 of saturated steam at a given temperature, g.

Of great importance for organisms is the deficiency of air saturation with water vapor, i.e. the difference between maximum and absolute humidity at a given temperature:

d = mus - m.

At different temperatures, the deficiency of air saturation with water vapor is not the same at the same humidity. The higher the temperature, the drier the air, and the more intense transpiration occurs in it (evaporation of water from leaves and other parts of plants).

The seasonal distribution of moisture throughout the year, as well as its daily fluctuations, is also extremely important for the life of organisms.

In relation to the water regime, the following are distinguished: environmental groups plants and animals: moisture-loving, dry-loving and preferring moderate humidity. Among the plants there are:

Among terrestrial animals there are:

Hydrophiles - moisture-loving animals (woodlice, springtails, mosquitoes, terrestrial planarians, terrestrial mollusks and amphibians).

Mesophiles - live in areas with moderate humidity (winter armyworm, many insects, birds, mammals).

Xerophiles - these are dry-loving animals that cannot tolerate high humidity (camels, desert rodents and reptiles).

For example, the elephant turtle stores water in the bladder; some mammals avoid moisture deficiency by depositing fats, the oxidation of which produces metabolic water. Many insects, camels, fat-tailed sheep, fat-tailed jerboas, etc. live on metabolic water.

Abiotic environmental factors include the substrate and its composition, humidity, light and other types of radiation in nature, its composition, and microclimate. It should be noted that temperature, air composition, humidity and light can be conditionally classified as “individual”, and substrate, climate, microclimate, etc. - as “complex” factors.

The substrate (literally) is the site of attachment. For example, for woody and herbaceous forms of plants, for soil microorganisms this is soil. In some cases, substrate can be considered synonymous with habitat (for example, soil is an edaphic habitat). The substrate is characterized by a certain chemical composition, which affects organisms. If the substrate is understood as a habitat, then in this case it represents a complex of characteristic biotic and abiotic factors to which this or that organism adapts.

Characteristics of temperature as an abiotic environmental factor

Temperature is an environmental factor associated with the average kinetic energy of particle motion and expressed in degrees on various scales. The most common scale is in degrees Celsius (°C), which is based on the expansion of water (the boiling point of water is 100°C). The SI adopts an absolute temperature scale, for which the boiling point of water is T bp. water = 373 K.

Very often, temperature is the limiting factor that determines the possibility (impossibility) of living of organisms in a particular habitat.

According to the nature of body temperature, all organisms are divided into two groups: poikilothermic (their body temperature depends on the ambient temperature and is almost the same as the ambient temperature) and homeothermic (their body temperature does not depend on the external temperature and is more or less constant: if it fluctuates, it is within small limits - fractions of a degree).

Poikilothermic organisms include plant organisms, bacteria, viruses, fungi, single-celled animals, as well as animals with a relatively low level of organization (fish, arthropods, etc.).

Homeotherms include birds and mammals, including humans. A constant body temperature reduces the dependence of organisms on the temperature of the external environment, making it possible to settle into a larger number of ecological niches, both in latitudinal and vertical distribution across the planet. However, in addition to homeothermy, organisms develop adaptations to overcome the effects of low temperatures.

Based on the nature of their tolerance to low temperatures, plants are divided into heat-loving and cold-resistant. Heat-loving plants include plants of the south (bananas, palm trees, southern varieties of apple trees, pears, peaches, grapes, etc.). Cold-resistant plants include plants of middle and northern latitudes, as well as plants growing high in the mountains (for example, mosses, lichens, pine, spruce, fir, rye, etc.). In central Russia, varieties of frost-resistant fruit trees are grown, which are specially bred by breeders. The first great successes in this area were achieved by I.V. Michurin and other folk breeders.

The norm of the body's reaction to the temperature factor (for individual organisms) is often narrow, i.e. a particular organism can function normally in a fairly narrow temperature range. Thus, marine vertebrates die when the temperature rises to 30-32°C. But for living matter as a whole, the limits of temperature influence at which life is preserved are very wide. Thus, in California, in hot springs there lives a species of fish that normally functions at a temperature of 52 ° C, and heat-resistant bacteria living in geysers can withstand temperatures up to 80 ° C (this is the “normal” temperature for them). Some people live in glaciers at a temperature of -44°C, etc.

The role of temperature as an environmental factor comes down to the fact that it affects metabolism: at low temperatures the rate of bioorganic reactions slows down greatly, and at high temperatures it increases significantly, which leads to an imbalance in the course of biochemical processes, and this causes various diseases, and sometimes and death.

The influence of temperature on plant organisms

Temperature is not only a factor determining the possibility of plants living in a particular area, but for some plants it influences the process of their development. Thus, winter varieties of wheat and rye, which did not undergo the process of “vernalization” (exposure to low temperatures) during germination, do not produce seeds when grown in the most favorable conditions.

To withstand the effects of low temperatures, plants have various adaptations.

1. In winter, the cytoplasm loses water and accumulates substances that have an “antifreeze” effect (monosaccharides, glycerin and other substances) - concentrated solutions of such substances freeze only at low temperatures.

2. The transition of plants to a stage (phase) resistant to low temperatures - the stage of spores, seeds, tubers, bulbs, rhizomes, roots, etc. Woody and shrubby forms of plants shed their leaves, the stems are covered with cork, which has high thermal insulation properties, and antifreeze substances accumulate in living cells.

The effect of temperature on animal organisms

Temperature affects poikilothermic and homeothermic animals differently.

Poikilothermic animals are active only during temperatures that are optimal for their life. During periods of low temperatures, they hibernate (amphibians, reptiles, arthropods, etc.). Some insects overwinter either as eggs or as pupae. The presence of an organism in hibernation is characterized by a state of suspended animation, in which metabolic processes are very inhibited and the body can go without food for a long time. Poikilothermic animals can also hibernate when exposed to high temperatures. Thus, animals in lower latitudes are in burrows during the hottest part of the day, and the period of their active life activity occurs in the early morning or late evening (or they are nocturnal).

Animal organisms hibernate not only due to the influence of temperature, but also due to other factors. Thus, a bear (a homeothermic animal) hibernates in winter due to lack of food.

Homeothermic animals are less dependent on temperature in their life activities, but temperature affects them in terms of the availability (absence) of food supply. These animals have the following adaptations to overcome the effects of low temperatures:

1) animals move from colder areas to warmer ones (bird migrations, mammal migrations);

2) change the nature of the cover (summer fur or plumage is replaced by a thicker winter one; they accumulate a large layer of fat - wild pigs, seals, etc.);

3) hibernate (for example, a bear).

Homeothermic animals have adaptations to reduce the effects of temperatures (both high and low). Thus, a person has sweat glands that change the nature of secretion at elevated temperatures (the amount of secretion increases), the lumen of blood vessels in the skin changes (at low temperatures it decreases, and at high temperatures it increases), etc.

Radiation as an abiotic factor

Both in the life of plants and in the life of animals, various radiations play a huge role, which either enter the planet from the outside (sun rays) or are released from the bowels of the Earth. Here we will mainly consider solar radiation.

Solar radiation is heterogeneous and consists of electromagnetic waves of different lengths, and therefore have different energies. Rays of both the visible and invisible spectrum reach the Earth's surface. Rays of the invisible spectrum include infrared and ultraviolet rays, and rays of the visible spectrum have seven most distinguishable rays (from red to violet). radiation quanta increases from infrared to ultraviolet (that is, ultraviolet rays contain quanta of the shortest waves and the highest energy).

The sun's rays have several environmentally important functions:

1) thanks to the sun's rays, a certain temperature regime is realized on the surface of the Earth, which has a latitudinal and vertical zonal character;

In the absence of human influence, the composition of the air may, however, vary depending on the altitude (with altitude, the content of oxygen and carbon dioxide decreases, since these gases are heavier than nitrogen). The air of coastal areas is enriched with water vapor, which contains sea salts in a dissolved state. The air of the forest differs from the air of the fields in the impurities of compounds released by various plants (for example, the air of a pine forest contains a large amount of resinous substances and esters that kill pathogens, so this air is healing for patients with tuberculosis).

The most important complex abiotic factor is climate.

Climate is a cumulative abiotic factor, including a certain composition and level of solar radiation, the associated level of temperature and humidity influence and a certain wind regime. The climate also depends on the nature of the vegetation growing in a given area and on the terrain.

There is a certain latitudinal and vertical climatic zonation on Earth. There are humid tropical, subtropical, sharply continental and other types of climate.

Review the information about different types of climate from the physical geography textbook. Consider the climate features of the area where you live.

Climate as a cumulative factor shapes one or another type of vegetation (flora) and a closely related type of fauna. Human settlements have a great influence on the climate. The climate of large cities differs from the climate of suburban areas.

Compare the temperature regime of the city in which you live and the temperature regime of the area where the city is located.

As a rule, the temperature within the city (especially in the center) is always higher than in the region.

Microclimate is closely related to climate. The reason for the emergence of microclimate is differences in the relief in a given territory, the presence of reservoirs, which leads to changes in conditions in different territories of a given climatic zone. Even in a relatively small area of a summer cottage, in certain parts of it, different conditions for plant growth may arise due to different lighting conditions.

TO abiotic factors environment includes factors of inanimate nature: light, temperature, humidity, geomagnetic field of the Earth, gravity, composition of the water, air, soil environment.

Light. The radiation of the Sun performs a dual function in relation to living nature. Firstly, it is a source of heat, the amount of which determines the activity of life in a given area; secondly, light serves as a signal that determines the activity of vital processes, as well as a guide when moving in space.

For animals and plants great value have the wavelength of the perceived radiation, its intensity and duration of exposure (the length of the photoperiod of the day, or photoperiod). Visible, or white light, makes up about 45% of the total radiant energy falling on the Earth. Ultraviolet rays make up about 10% of all radiant energy. Invisible to humans, they are perceived by the visual organs of insects and serve them for orientation in cloudy weather. The rays of the ultraviolet part of the spectrum are also necessary for normal human life. Under their influence, vitamin D is formed in the body.

Visible light with a wavelength from 0.4 to 0.75 microns is of greatest importance for organisms. Visible light energy is used for photosynthesis processes in plant cells. In this case, orange-red (0.66-0.68 microns) and blue-violet (0.4-0.5 microns) rays are especially strongly absorbed by the leaves. From 0.1 to 1% of incoming solar energy is consumed for biosynthesis,
sometimes the efficiency of photosynthetic vegetation reaches several percent.

The variety of light conditions under which plants live is very great. In different habitats, the intensity of solar radiation, its spectral composition, duration of illumination, etc. are not the same. In plants, the intensity of photosynthesis increases with increasing illumination to a certain limit, called the level of light saturation or ecological optimum. A further increase in light flux is not accompanied by an increase in photosynthesis, and then leads to its inhibition.

In relation to light, three groups of plants are distinguished: light-loving, shade-loving and shade-tolerant.

Light-loving plants live in open places under conditions of full sunlight (steppe and meadow grasses, open ground cultivated plants and many others). But even in light-loving plants, an increase in illumination above the optimal level suppresses photosynthesis.

Shade-loving plants have an ecological optimum in the area of low light and do not tolerate strong light. These are species that live in the lower, shaded tiers of plant communities - spruce forests, oak forests, etc. Shade-tolerant plants grow well in full light, but also adapt to low light.

Infrared radiation makes up approximately 45% of the total amount of solar energy flowing to the Earth. Infrared rays are absorbed by the tissues of plants and animals, inanimate objects, including water. Any surface that has a temperature above zero emits long-wave infrared (heat) rays. Therefore, plants and animals receive thermal energy not only from the Sun, but also from environmental objects.

From the above it follows that light is one of the most important abiotic factors.

Temperature. The body temperature of most organisms and, consequently, the rate of all chemical reactions that make up metabolism depend on the ambient temperature. The normal structure and functioning of proteins, on which the very existence of life depends, is possible within the range from 0 to 50 °C. Meanwhile, the temperature limits within which life is found are much wider. In the icy deserts of Antarctica, temperatures can drop to -88 °C, and in arid deserts reach 58 °C in the shade. Some types of bacteria and algae live in hot springs at temperatures of 80-88 °C. Thus, the range of temperature fluctuations in different areas of the Earth where life occurs reaches 176 °C. Even in one habitat, the difference between the minimum temperature in winter and the maximum in summer can be more than 80 °C. In some areas, daily temperature fluctuations are also large: for example, in the Sahara Desert, the temperature can change by 50 °C during the day. But not a single living creature in the world is capable of tolerating the entire temperature range in an active state. Therefore, the distribution of any species of animals and plants is limited to the habitat to which the temperature it is adapted.

Humidity. Water is a necessary component of the cell, so its quantity in a particular habitat determines the nature of the vegetation and animal life in that area. To some extent, the amount of water in the environment depends on its content in the body of plants and animals and their resistance to drying out.

In plants of deserts and dry steppes, water makes up 30-65% of the total mass; in forest-steppe oak groves this value increases to 70-85%, in spruce forests it reaches 90%.

The body of animals, as a rule, consists of at least 50% water. The granary weevil, which feeds on very dry food - grain, has even less water in its body - 46%. Caterpillars that eat succulent leaves contain 85-90% water. In general, animals that live on land have less water in their bodies than aquatic animals. Thus, the body of livestock contains 59% moisture, the human body - 64%, mallard ducks - 70%. In fish, the water content in the body reaches 75%, and in jellyfish - more than 99%.

The water balance of an area depends on the amount of precipitation that falls during the year and the value characterizing its evaporation. If the amount of evaporated water exceeds the annual precipitation, such areas are called dry, arid or arid.

Areas sufficiently provided with moisture are called humid (wet). Excess water in the soil leads to the development of swamps inhabited by plant species that are unable to regulate their water regime. These include algae, fungi, lichens, some mosses, elodea, water buttercups, Vallisneria, reeds and many others. Such plants have low osmotic pressure of cell sap and, therefore, little water retention.
ability, high level evaporation through wide open stomata. The root system of flowering marsh plants is poorly developed or completely absent.

The ability to regulate water balance in herbaceous plants of dark coniferous forests is limited. As soil moisture decreases, the species composition of plant communities changes. Broad-leaved forests give way to small-leaved forests, which turn into forest-steppe. With a further decrease in precipitation (and an increase in soil dryness), tall grasses give way to short grasses. When annual precipitation is 250 mm or lower, deserts arise. With uneven distribution of precipitation over the seasons, plants and animals have to endure long droughts.

Plants have developed a number of adaptations to periodic lack of moisture. This is a sharp reduction in the growing season (up to 4-6 weeks) and a long dormant period that plants experience in the form of seeds, bulbs, tubers, etc. (tulips, goose onions, poppies, etc.). Such plants are called ephemerals and ephemeroids. Others, which do not stop growing during the dry period, have a highly developed root system, much larger in mass than the above-ground part.

Reducing evaporation is achieved by reducing the leaf blade, its pubescence, reducing the number of stomata, transforming the leaf into spines, and developing a waterproof waxy coating. Some species, such as saxaul, lose their leaves, and photosynthesis is carried out by green branches. Many plants are capable of storing water in the tissues of the stem or root (cactus, African desert milkweed, steppe meadowsweet).

Survival under dry period conditions is facilitated by both the high osmotic pressure of the cell sap, which prevents evaporation, and the ability to lose a large amount of water (up to 80%) without loss of viability. Desert animals have a special type of metabolism in which water is formed in the body when eating dry food (rodents). Fat, which accumulates in large quantities in some animals (camels, fat-tailed sheep), also serves as a source of water. Ungulates are capable of running vast distances in search of water. Many small animals go into suspended animation during periods of drought.

Salinity. For living organisms, the qualitative and quantitative composition of mineral salts in the environment is of great importance. The air contains few salts, and they do not have a significant effect on living organisms. Salts are always present in water and almost exclusively in solutions. The main components of saline solutions are Na +, K +, Ca 2+ and Mg 2+ ions. Of the anions, the largest specific gravity belongs to chlorine (Cl -), sulfuric acid residues (SO 4 2-), hydrogen carbonate (HCO 3 -) and carbonate (CO 3 2-).

TO important components natural solutions also include ions of di- or trivalent iron and manganese.

In general, we can say that seawater contains the most sodium and chlorine. In fresh waters, calcium, bicarbonate and carbonate ions are predominantly found. In some reservoirs, sulfates predominate (Caspian and Aral seas).

1) fresh water - up to 0.5;

2) brackish waters - from 0.5 to 30;

3) salty - from 30 to 40;

4) brines - over 40.

The concentration and qualitative composition of salts in water bodies have a great influence on the number and distribution of aquatic animals. Freshwater animals generally have a higher osmotic pressure relative to their environment, so water enters their bodies constantly.

To remove excess water, pulsating vacuoles (in protozoa) and excretory organs in multicellular animals are used. Sea life Most are isotonic to seawater, but many species are hypotonic and for them the regulation of the concentration of substances dissolved in body fluids is associated with high energy costs. For example, in ancient cartilaginous fish (sharks, rays), the osmotic pressure inside the body is equal to the pressure in the surrounding sea water. But bony fish, which evolved in fresh water, have low osmotic pressure.

To compensate for the loss of water in their body, they drink sea water, and the excess salts absorbed with it are excreted by the kidneys, as well as through the intestines and gills.

Few species of aquatic animals can live in both fresh and salt water. Thus, the European river eel spawns in the sea. Young eels migrate into rivers and grow in fresh water. To spawn, adult fish migrate to the sea again. On the contrary, salmon and salmon spawn in fresh water and grow in the sea. In the same way, some crabs ascend rivers far into the interior of the mainland, but their larvae develop and reach sexual maturity only in the sea. This is due to the history of the development of species. Thus, the eel has related species - purely marine fish, and species close to salmon and salmon are freshwater. Thus, migrating species in their ontogeny repeat the phylogeny of the corresponding families of fish. Reservoirs very rich in salts are generally unsuitable for animal habitation. The crustacean Artemia, certain species of blue-green algae, flagellates, and bacteria have adapted to exist in such conditions. The acidity and alkalinity of the habitat (pH) of soil and water have a profound effect on organisms. High concentrations of H + or OH - ions (at a pH below 3 or above 9, respectively) are toxic.

In very acidic or alkaline soils, plant root cells are damaged. In addition, at a pH below 4.0, soils contain many aluminum ions, which also have a toxic effect on plants. Under these conditions, iron and manganese ions, which are absolutely necessary for plants in small quantities, reach toxic concentrations. In alkaline soils, the opposite phenomenon is observed - a lack of necessary chemical elements. At high pH values, iron, manganese, phosphates, and a number of microelements are bound in poorly soluble compounds and are inaccessible to plants.

In rivers, ponds and lakes, as water acidity increases, species diversity decreases. Increased acidity affects animals in several ways: disrupting the process of osmoregulation, the work of enzymes, and gas exchange through the respiratory surfaces; increasing the concentration of toxic elements, especially aluminum; reducing the quality and variety of food. For example, at low pH, fungal development is inhibited and aquatic vegetation is less diverse or absent altogether.

Industrial atmospheric pollution (sulfur dioxide, nitrogen oxides) leads to acid rain, the pH of which reaches 3.7-3.3. Such rains cause forests to dry out and fish to disappear from water bodies.

Oxygen. Oxygen is necessary for the functioning of most living organisms. Air contains on average 21% oxygen (by volume), water contains no more than 1%. With increasing altitude above sea level, the oxygen content in the air decreases parallel to the decrease in atmospheric pressure. In high mountain areas, the oxygen content in the air serves as a limit for the distribution of many animal species.

For last decades Oxygen consumption by industry has sharply increased and carbon dioxide emissions into the atmosphere have increased. For example, the combustion of 100 liters of gasoline consumes enough oxygen to breathe for one person for a year. At the same time, in industrial centers the content of CO 2 in the atmosphere on windless days can be tens of times higher than the usual norm (0.03% by volume). The source of replenishment of oxygen in the atmosphere is mainly forests. One hectare of pine forest produces about 30 tons of oxygen per year - as much as is required for the breathing of 19 people throughout the year. One hectare of deciduous forest produces about 16 tons per year, and a hectare of agricultural land produces from 3 to 10 tons per year. It is clear from this that deforestation, along with increasing emissions of CO 2 into the atmosphere, can seriously change the ratio of these gases and affect fauna planets.

Satisfying the need for oxygen in animals living in water is carried out in different ways: some create a constant flow of water over their respiratory surfaces (for example, by movements of the gill covers in fish), others have a very large (relative to volume) body surface or various outgrowths (many aquatic crustaceans), others often return to the surface to take a breath (whales, dolphins, turtles, newts).

The oxygen needs of plant roots are only partially met from the soil. Some of the oxygen diffuses to the roots from the shoots. Plants living in oxygen-poor soils (tropical swamps) form respiratory roots. They rise vertically upward, there are holes on their surface through which air enters the roots, and then into parts of the plant immersed in swampy soil.

Earth's magnetic field. The Earth's magnetic field is an important environmental factor, under the influence of which evolution took place and which has a constant impact on living organisms. Magnetic field strength increases with latitude. When the intensity of particle flows moving from the Sun (“solar wind”) changes, short-term disturbances occur in the Earth’s magnetic field—“magnetic storms.”

The strength of the Earth's magnetic field does not remain constant throughout the day. Sharp fluctuations in the strength of the geomagnetic field disrupt the functioning of the nervous and cardiovascular systems in humans. How deeply the geomagnetic field affects plants, the rate of plant growth depends on the orientation of the seed in relation to the magnetic lines of force.