Main groups of environmental factors. Main abiotic factors

Introduction

Abiotic environmental factors are components and phenomena of inanimate, inorganic nature that directly or indirectly affect living organisms. Naturally, these factors act simultaneously and this means that all living organisms fall under their influence. The degree of presence or absence of each of them significantly affects the viability of organisms, and varies differently for different species. It should be noted that this greatly affects the entire ecosystem as a whole and its sustainability.

Environmental factors, both individually and in combination, when affecting living organisms, force them to change and adapt to these factors. This ability is called ecological valence or plasticity. The plasticity, or environmental valency, of each species is different and has a different effect on the ability of living organisms to survive under changing environmental factors. If organisms not only adapt to biotic factors, but can also influence them, changing other living organisms, then this is impossible with abiotic environmental factors: the organism can adapt to them, but is not able to have any significant reverse influence on them.

Abiotic environmental factors are conditions that are not directly related to the life activity of organisms. The most important abiotic factors include temperature, light, water, composition of atmospheric gases, soil structure, composition of nutrients in it, terrain, etc. These factors can affect organisms both directly, for example light or heat, and indirectly, for example, terrain, which determines the action of direct factors, light, wind, moisture, etc. More recently, the influence of changes in solar activity on biosphere processes has been discovered.

Basic abiotic factors and their characteristics

Among the abiotic factors are:

1. Climatic (the influence of temperature, light and humidity);

2. Geological (earthquake, volcanic eruption, glacial movement, mudflows and avalanches, etc.);

3. Orographic (features of the terrain where the studied organisms live).

Let us consider the action of the main direct abiotic factors: light, temperature and the presence of water. Temperature, light and humidity are the most important factors external environment. These factors naturally change both throughout the year and day, and in connection with geographic zoning. Organisms exhibit zonal and seasonal adaptation to these factors.

Light as an environmental factor

Solar radiation is the main source of energy for all processes occurring on Earth. In the spectrum of solar radiation, three regions can be distinguished, different in biological action: ultraviolet, visible and infrared. Ultraviolet rays with a wavelength of less than 0.290 microns are destructive to all living things, but they are delayed ozone layer atmosphere. Only reaches the surface of the Earth Not most of longer ultraviolet rays (0.300 - 0.400 microns). They make up about 10% of radiant energy. These rays are highly chemically active; at high doses they can damage living organisms. In small quantities, however, they are necessary, for example, for humans: under the influence of these rays, vitamin D is formed in the human body, and insects visually distinguish these rays, i.e. see in ultraviolet light. They can navigate by polarized light.

Visible rays with a wavelength of 0.400 to 0.750 microns (accounting for most of the energy - 45% - of solar radiation) reaching the Earth's surface have a particularly great importance for organisms. Green plants, due to this radiation, synthesize organic matter (carry out photosynthesis), which is used as food by all other organisms. For most plants and animals, visible light is one of the important factors environments, although there are those for which light is not prerequisite existence (soil, cave and deep-sea types of adaptation to life in the dark). Most animals are able to distinguish the spectral composition of light - have color vision, and plants have brightly colored flowers to attract pollinating insects.

Infrared rays with a wavelength of more than 0.750 microns are not perceived by the human eye, but they are a source of thermal energy (45% of radiant energy). These rays are absorbed by the tissues of animals and plants, causing the tissues to heat up. Many cold-blooded animals (lizards, snakes, insects) use sunlight to increase body temperature (some snakes and lizards are ecologically warm-blooded animals). Light conditions, associated with the rotation of the Earth, have a distinct daily and seasonal periodicity. Almost all physiological processes plants and animals have a daily rhythm with a maximum and minimum at certain hours: for example, at certain hours of the day, a plant flower opens and closes, and animals have developed adaptations to night and day life. Day length (or photoperiod) has great value in the life of plants and animals.

Plants, depending on their living conditions, adapt to the shade - shade-tolerant plants or, on the contrary, to the sun - light-loving plants (for example, cereals). However, strong, bright sun (above optimal brightness) suppresses photosynthesis, making it difficult to produce high yields of protein-rich crops in the tropics. In temperate zones (above and below the equator), the development cycle of plants and animals is confined to the seasons of the year: preparation for changes in temperature conditions is carried out on the basis of a signal - changes in day length, which at a certain time of the year in a given place is always the same. As a result of this signal, physiological processes are turned on, leading to plant growth and flowering in the spring, fruiting in the summer and shedding leaves in the fall; in animals - to molting, fat accumulation, migration, reproduction in birds and mammals, and the onset of the resting stage in insects. Animals perceive changes in day length using their visual organs. And plants - with the help of special pigments located in the leaves of plants. Irritations are perceived through receptors, as a result of which a series of biochemical reactions occur (activation of enzymes or release of hormones), and then physiological or behavioral reactions appear.

The study of photoperiodism in plants and animals has shown that the reaction of organisms to light is based not simply on the amount of light received, but on the alternation of periods of light and darkness of a certain duration during the day. Organisms are able to measure time, i.e. possess “ biological clock” - from single-celled organisms to humans. “Biological clock” is also controlled by seasonal cycles and other biological phenomena. “Biological clocks” determine the daily rhythm of activity of both whole organisms and processes occurring even at the cellular level, in particular cell divisions.

Temperature as an environmental factor

All chemical processes occurring in the body depend on temperature. Changes in thermal conditions, often observed in nature, deeply affect the growth, development and other manifestations of the life of animals and plants. There are organisms with an unstable body temperature - poikilothermic and organisms with a constant body temperature - homeothermic. Poikilothermic animals are entirely dependent on the temperature of the environment, while homeothermic animals are able to maintain a constant body temperature regardless of changes in environmental temperature. The vast majority of terrestrial plants and animals in a state of active life cannot tolerate negative temperatures and die. The upper temperature limit of life is not the same for different types- rarely above 40-45 o C. Some cyanobacteria and bacteria live at temperatures of 70-90 o C; some mollusks can also live in hot springs (up to 53 o C). For most terrestrial animals and plants, the optimum temperature conditions fluctuate within rather narrow limits (15-30 o C). The upper threshold of life temperature is determined by the temperature of protein coagulation, since irreversible protein coagulation (disruption of protein structure) occurs at a temperature of about 60 o C.

In the process of evolution, poikilothermic organisms have developed various adaptations to changing temperature conditions of the environment. The main source of thermal energy in poikilothermic animals is external heat. Poikilothermic organisms have developed various adaptations to low temperatures. Some animals, for example, Arctic fish, which constantly live at a temperature of -1.8 o C, contain substances (glycoproteins) in their tissue fluid that prevent the formation of ice crystals in the body; insects accumulate glycerol for these purposes. Other animals, on the contrary, increase the body's heat production due to active muscle contraction - this way they increase body temperature by several degrees. Still others regulate their heat exchange due to the exchange of heat between vessels circulatory system: the vessels coming from the muscles are in close contact with the vessels coming from the skin and carrying cooled blood (this phenomenon is characteristic of cold-water fish). Adaptive behavior involves many insects, reptiles and amphibians selecting places in the sun to warm themselves or changing different positions to increase the heating surface.

In a number of cold-blooded animals, body temperature can vary depending on the physiological state: for example, in flying insects, the internal body temperature can rise by 10-12 o C or more due to increased muscle work. Social insects, especially bees, have developed an effective way of maintaining temperature through collective thermoregulation (the hive can maintain a temperature of 34-35 o C, necessary for the development of larvae).

Poikilothermic animals are able to adapt to high temperatures. This also happens different ways: heat transfer can occur due to the evaporation of moisture from the surface of the body or from the mucous membrane of the upper respiratory tract, as well as due to subcutaneous vascular regulation (for example, in lizards, the speed of blood flow through the vessels of the skin increases with increasing temperature).

The most perfect thermoregulation is observed in birds and mammals - homeothermic animals. In the process of evolution, they acquired the ability to maintain a constant body temperature due to the presence of a four-chambered heart and one aortic arch, which ensured complete separation of arterial and venous blood flow; high metabolism; feathers or hair; regulation of heat transfer; well developed nervous system acquired the ability to live actively at different temperatures. In most birds, the body temperature is slightly higher than 40 o C, and in mammals it is slightly lower. Very important for animals is not only the ability to thermoregulate, but also adaptive behavior, the construction of special shelters and nests, the choice of a place with a more favorable temperature, etc. They are also able to adapt to low temperatures in several ways: in addition to feathers or hair, warm-blooded animals use trembling (microcontractions of externally motionless muscles) to reduce heat loss; the oxidation of brown adipose tissue in mammals produces additional energy that supports metabolism.

The adaptation of warm-blooded animals to high temperatures is in many ways similar to similar adaptations of cold-blooded animals - sweating and evaporation of water from the mucous membrane of the mouth and upper respiratory tract; in birds - only the latter method, since they do not have sweat glands; extension blood vessels, located close to the surface of the skin, which enhances heat transfer (in birds this process occurs in non-feathered areas of the body, for example through the crest). Temperature, as well as the light regime on which it depends, naturally changes throughout the year and due to geographical latitude. Therefore, all adaptations are more important for living at low temperatures.

Water as an environmental factor

Water plays an exceptional role in the life of any organism, since it is structural component cells (water accounts for 60-80% of the cell mass). The importance of water in the life of a cell is determined by its physical and chemical properties. Due to polarity, a water molecule is able to attract any other molecules, forming hydrates, i.e. is a solvent. Many chemical reactions can only occur in the presence of water. Water is a “thermal buffer” in living systems, absorbing heat during the transition from a liquid to a gaseous state, thereby protecting unstable cell structures from damage during the short-term release of thermal energy. In this regard, it produces a cooling effect when evaporating from the surface and regulates body temperature. The thermal conductivity properties of water determine its leading role as a climate thermoregulator in nature. Water slowly heats up and slowly cools: in summer and during the day, the water of the seas, oceans and lakes heats up, and at night and in winter it also slowly cools. There is a constant exchange between water and air carbon dioxide. In addition, water performs a transport function, moving soil substances from top to bottom and back. The role of humidity for terrestrial organisms is due to the fact that precipitation is distributed over earth's surface unevenly throughout the year. In arid areas (steppes, deserts), plants obtain water with the help of a highly developed root system, sometimes very long roots (for camel thorn - up to 16 m), reaching the wet layer. High osmotic pressure cell sap(up to 60-80 atm), which increases the suction power of the roots and helps retain water in the tissues. In dry weather, plants reduce water evaporation: in desert plants, the integumentary tissues of the leaves thicken, or a waxy layer or dense pubescence develops on the surface of the leaves. A number of plants achieve a decrease in moisture by reducing the leaf blade (leaves turn into spines, often plants completely lose leaves - saxaul, tamarisk, etc.).

Depending on the requirements for the water regime, the following plants are distinguished: environmental groups:

Hydratophytes are plants that constantly live in water;

Hydrophytes - plants that are only partially immersed in water;

Helophytes - marsh plants;

Hygrophytes are terrestrial plants that live in excessively moist places;

Mesophytes - prefer moderate moisture;

Xerophytes are plants adapted to constant lack of moisture; Among xerophytes there are:

Succulents - accumulating water in the tissues of their body (succulent);

Sclerophytes - lose a significant amount of water.

Many desert animals can survive without drinking water; some can run quickly and for a long time, making long migrations to watering places (saiga antelopes, camels, etc.); Some animals obtain water from food (insects, reptiles, rodents). Fat deposits Desert animals can serve as a kind of water reserve in the body: when fats are oxidized, water is formed (fat deposits in the hump of camels or subcutaneous fat deposits in rodents). Low-permeability skin coverings (for example, in reptiles) protect animals from moisture loss. Many animals have switched to a nocturnal lifestyle or hide in burrows, avoiding the drying effects of low humidity and overheating. Under conditions of periodic dryness, a number of plants and animals enter a state of physiological dormancy - plants stop growing and shed their leaves, animals hibernate. These processes are accompanied by reduced metabolism during dry periods.

abiotic nature biosphere solar

Literature

1. http://burenina.narod.ru/3-2.htm

2. http://ru-ecology.info/term/76524/

4. http://www.ecology-education.ru/index.php?action=full&id=257

5. http://bibliofond.ru/view.aspx?id=484744

Introduction

Main abiotic factors and their characteristics

Literature

Introduction

1. Main abiotic factors and their characteristics

Among the abiotic factors are:

Climatic (the influence of temperature, light and humidity);

Geological (earthquake, volcanic eruption, glacial movement, mudflows and avalanches, etc.);

Orographic (features of the terrain where the studied organisms live).

Let us consider the action of the main direct abiotic factors: light, temperature and the presence of water. Temperature, light and humidity are the most important environmental factors. These factors naturally change both throughout the year and day, and in connection with geographic zoning. Organisms exhibit zonal and seasonal adaptation to these factors.

Light as an environmental factor

Solar radiation is the main source of energy for all processes occurring on Earth. In the spectrum of solar radiation, three regions can be distinguished, different in biological action: ultraviolet, visible and infrared. Ultraviolet rays with a wavelength of less than 0.290 microns are destructive to all living things, but they are retained by the ozone layer of the atmosphere. Only a small portion of longer ultraviolet rays (0.300 - 0.400 microns) reaches the Earth's surface. They make up about 10% of radiant energy. These rays are highly chemically active; at high doses they can damage living organisms. In small quantities, however, they are necessary, for example, for humans: under the influence of these rays, vitamin D is formed in the human body, and insects visually distinguish these rays, i.e. see in ultraviolet light. They can navigate by polarized light.

Visible rays with a wavelength of 0.400 to 0.750 microns (they account for most of the energy - 45% - of solar radiation) reaching the Earth's surface are especially important for organisms. Green plants, due to this radiation, synthesize organic matter (carry out photosynthesis), which is used as food by all other organisms. For most plants and animals, visible light is one of the important environmental factors, although there are those for which light is not a prerequisite for existence (soil, cave and deep-sea types of adaptation to life in the dark). Most animals are able to distinguish the spectral composition of light - have color vision, and plants have brightly colored flowers to attract pollinating insects.

Infrared rays with a wavelength of more than 0.750 microns are not perceived by the human eye, but they are a source of thermal energy (45% of radiant energy). These rays are absorbed by the tissues of animals and plants, causing the tissues to heat up. Many cold-blooded animals (lizards, snakes, insects) use sunlight to increase their body temperature (some snakes and lizards are ecologically warm-blooded animals). Light conditions associated with the Earth's rotation have distinct daily and seasonal cycles. Almost all physiological processes in plants and animals have a daily rhythm with a maximum and minimum at certain hours: for example, at certain hours of the day, a plant flower opens and closes, and animals have developed adaptations to night and day life. Day length (or photoperiod) is of great importance in the life of plants and animals.

The study of photoperiodism in plants and animals has shown that the reaction of organisms to light is based not simply on the amount of light received, but on the alternation of periods of light and darkness of a certain duration during the day. Organisms are able to measure time, i.e. have biological clock - from unicellular organisms to humans. The biological clock - are also governed by seasonal cycles and other biological phenomena. The biological clock determine the daily rhythm of activity of both whole organisms and processes occurring even at the cellular level, in particular cell divisions.

Temperature as an environmental factor

All chemical processes occurring in the body depend on temperature. Changes in thermal conditions, often observed in nature, deeply affect the growth, development and other manifestations of the life of animals and plants. There are organisms with an unstable body temperature - poikilothermic and organisms with a constant body temperature - homeothermic. Poikilothermic animals are entirely dependent on the temperature of the environment, while homeothermic animals are able to maintain a constant body temperature regardless of changes in environmental temperature. The vast majority of terrestrial plants and animals in a state of active life cannot tolerate negative temperatures and die. The upper temperature limit of life is not the same for different species - rarely above 40-45 O C. Some cyanobacteria and bacteria live at temperatures of 70-90 O C, some mollusks (up to 53 O WITH). For most terrestrial animals and plants, the optimum temperature conditions fluctuate within rather narrow limits (15-30 O WITH). The upper threshold of life temperature is determined by the temperature of protein coagulation, since irreversible protein coagulation (disturbance of protein structure) occurs at a temperature of about 60 o WITH.

In the process of evolution, poikilothermic organisms have developed various adaptations to changing temperature conditions of the environment. The main source of thermal energy in poikilothermic animals is external heat. Poikilothermic organisms have developed various adaptations to low temperatures. Some animals, for example, Arctic fish, live constantly at a temperature of -1.8 o C, contain substances (glycoproteins) in tissue fluid that prevent the formation of ice crystals in the body; insects accumulate glycerol for these purposes. Other animals, on the contrary, increase the body's heat production due to active muscle contraction - this way they increase body temperature by several degrees. Still others regulate their heat exchange due to the exchange of heat between the vessels of the circulatory system: the vessels coming from the muscles are in close contact with the vessels coming from the skin and carrying cooled blood (this phenomenon is characteristic of cold-water fish). Adaptive behavior involves many insects, reptiles and amphibians selecting places in the sun to warm themselves or changing different positions to increase the heating surface.

In a number of cold-blooded animals, body temperature can vary depending on the physiological state: for example, in flying insects, the internal body temperature can rise by 10-12 o C or more due to increased muscle work. Social insects, especially bees, have developed an effective way of maintaining temperature through collective thermoregulation (a hive can maintain a temperature of 34-35 o C, necessary for the development of larvae).

Poikilothermic animals are able to adapt to high temperatures. This also occurs in different ways: heat transfer can occur due to the evaporation of moisture from the surface of the body or from the mucous membrane of the upper respiratory tract, as well as due to subcutaneous vascular regulation (for example, in lizards, the speed of blood flow through the vessels of the skin increases with increasing temperature).

The most perfect thermoregulation is observed in birds and mammals - homeothermic animals. In the process of evolution, they acquired the ability to maintain a constant body temperature due to the presence of a four-chambered heart and one aortic arch, which ensured complete separation of arterial and venous blood flow; high metabolism; feathers or hair; regulation of heat transfer; a well-developed nervous system acquired the ability to live actively at different temperatures. Most birds have a body temperature slightly above 40 o C, and in mammals it is slightly lower. Very important for animals is not only the ability to thermoregulate, but also adaptive behavior, the construction of special shelters and nests, the choice of a place with a more favorable temperature, etc. They are also able to adapt to low temperatures in several ways: in addition to feathers or hair, warm-blooded animals use trembling (microcontractions of externally motionless muscles) to reduce heat loss; the oxidation of brown adipose tissue in mammals produces additional energy that supports metabolism.

The adaptation of warm-blooded animals to high temperatures is in many ways similar to similar adaptations of cold-blooded animals - sweating and evaporation of water from the mucous membrane of the mouth and upper respiratory tract; in birds - only the latter method, since they do not have sweat glands; dilation of blood vessels located close to the surface of the skin, which increases heat transfer (in birds, this process occurs in non-feathered areas of the body, for example through the crest). Temperature, as well as the light regime on which it depends, naturally changes throughout the year and in connection with geographic latitude. Therefore, all adaptations are more important for living at low temperatures.

Water as an environmental factor

Water plays an exceptional role in the life of any organism, since it is a structural component of the cell (water accounts for 60-80% of the cell’s mass). The importance of water in the life of a cell is determined by its physicochemical properties. Due to polarity, a water molecule is able to attract any other molecules, forming hydrates, i.e. is a solvent. Many chemical reactions can only occur in the presence of water. Water is present in living systems thermal buffer , absorbing heat during the transition from a liquid to a gaseous state, thereby protecting the unstable structures of the cell from damage during the short-term release of thermal energy. In this regard, it produces a cooling effect when evaporating from the surface and regulates body temperature. The thermal conductivity properties of water determine its leading role as a climate thermoregulator in nature. Water slowly heats up and slowly cools: in summer and during the day, the water of the seas, oceans and lakes heats up, and at night and in winter it also slowly cools. There is a constant exchange of carbon dioxide between water and air. In addition, water performs a transport function, moving soil substances from top to bottom and back. The role of humidity for terrestrial organisms is due to the fact that precipitation is distributed unevenly on the earth's surface throughout the year. In arid areas (steppes, deserts), plants obtain water with the help of a highly developed root system, sometimes very long roots (for camel thorn - up to 16 m), reaching the wet layer. The high osmotic pressure of cell sap (up to 60-80 atm), which increases the suction power of the roots, helps retain water in the tissues. In dry weather, plants reduce water evaporation: in desert plants, the integumentary tissues of the leaves thicken, or a waxy layer or dense pubescence develops on the surface of the leaves. A number of plants achieve a decrease in moisture by reducing the leaf blade (leaves turn into spines, often plants completely lose leaves - saxaul, tamarisk, etc.).

Depending on the requirements for the water regime, the following ecological groups are distinguished among plants:

Hydratophytes are plants that constantly live in water;

Hydrophytes - plants that are only partially immersed in water;

Helophytes - marsh plants;

Hygrophytes are terrestrial plants that live in excessively moist places;

Mesophytes - prefer moderate moisture;

Xerophytes are plants adapted to constant lack of moisture; Among xerophytes there are:

Succulents - accumulating water in the tissues of their body (succulent);

Sclerophytes - lose a significant amount of water.

Many desert animals are able to survive without drinking water; some can run quickly and for a long time, making long migrations to watering places (saiga antelopes, camels, etc.); Some animals obtain water from food (insects, reptiles, rodents). Fat deposits of desert animals can serve as a kind of water reserve in the body: when fats are oxidized, water is formed (fat deposits in the hump of camels or subcutaneous fat deposits in rodents). Low-permeability skin coverings (for example, in reptiles) protect animals from moisture loss. Many animals have switched to a nocturnal lifestyle or hide in burrows, avoiding the drying effects of low humidity and overheating. Under conditions of periodic dryness, a number of plants and animals enter a state of physiological dormancy - plants stop growing and shed their leaves, animals hibernate. These processes are accompanied by reduced metabolism during dry periods.

abiotic nature biosphere solar

Literature

1. http://burenina.narod.ru/3-2.htm

Http://ru-ecology.info/term/76524/

Http://www.ecology-education.ru/index.php?action=full&id=257

Http://bibliofond.ru/view.aspx?id=484744

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The impact of environmental factors on living organisms individually and communities as a whole is multifaceted. When assessing the influence of a particular environmental factor, it is important to characterize the intensity of its action on living matter: in favorable conditions they speak of an optimal factor, and in case of excess or deficiency - a limiting factor.

Temperature. Most species are adapted to a fairly narrow temperature range. Some organisms, especially in the resting stage, are able to exist at very low temperatures. For example, microbial spores can withstand cooling down to -200 °C. Certain types of bacteria and algae can live and reproduce in hot springs at temperatures from +80 to -88 ° C. The range of temperature fluctuations in water is much smaller than on land, and accordingly, the limits of resistance to temperature fluctuations in aquatic organisms are narrower than in terrestrial ones. However, for both aquatic and terrestrial inhabitants, the optimal temperature is in the range from +15 to +30 °C.

There are organisms with an unstable body temperature - poikilothermic (from the Greek. poikilos- varied, changeable and thermo- heat) and organisms with a constant body temperature - homeothermic (from the Greek. homoios- similar and thermo- warm). The body temperature of poikilothermic organisms depends on the ambient temperature. Its increase causes them to intensify their life processes and, within certain limits, accelerate their development.

In nature, temperature is not constant. Organisms that are typically exposed to seasonal temperature fluctuations, such as those found in temperate zones, are less able to tolerate constant temperatures. Sharp temperature fluctuations - severe frosts or heat - are also unfavorable for organisms. There are many devices to combat cooling or overheating. With the onset of winter, plants and poikilothermic animals enter a state of winter dormancy. The metabolic rate decreases sharply, and a lot of fats and carbohydrates are stored in the tissues. The amount of water in the cells decreases, sugars and glycerol accumulate, which prevent freezing. In the hot season they turn on physiological mechanisms, protecting against overheating. In plants, water evaporation through the stomata increases, which leads to a decrease in leaf temperature. In animals under these conditions, the evaporation of water through the respiratory system also increases and skin. In addition, poikilothermic animals avoid overheating through adaptive behavior: they choose habitats with the most favorable microclimate, hide in burrows or under stones during hot times of the day, are active at certain times of the day, etc.

Thus, environmental temperature is an important and often limiting factor in life manifestations.

Homeothermic animals - birds and mammals - are much less dependent on environmental temperature conditions. Aromorphic changes in structure allowed these two classes to remain active at very sharp changes temperatures and explore almost all habitats.

The depressing effect of low temperatures on organisms is enhanced by strong winds.

Light. Light in the form of solar radiation powers all life processes on Earth (Fig. 25.4). For organisms, the wavelength of the perceived radiation, its intensity and the duration of exposure (day length, or photoperiod) are important. Ultraviolet rays with a wavelength greater than 0.3 microns account for approximately 40% of the radiant energy reaching the earth's surface. In small doses they are necessary for animals and humans. Under their influence, vitamin D is formed in the body. Insects visually distinguish ultra-violet rays and use this for orientation in cloudy weather. Visible light with a wavelength of 0.4-0.75 microns has the greatest effect on the body. Visible light energy accounts for about 45% of the total radiant energy striking the Earth. Visible light is least attenuated when passing through dense clouds and water. Therefore, photosynthesis can occur in cloudy weather and under a layer of water of a certain thickness. But still, only 0.1 to 1% of incoming solar energy is spent on biomass synthesis.

Rice. 25.4.

Depending on the living conditions, plants adapt to the shade - shade-tolerant plants or, on the contrary, to the bright sun - light-loving plants. The last group includes cereals.

An extremely important role in regulating the activity of living organisms and their development is played by the duration of exposure to light - the photoperiod. In temperate zones, above and below the equator, the development cycle of plants and animals is confined to the seasons of the year and preparation for changing temperature conditions is carried out on the basis of a signal of day length, which, unlike other seasonal factors, is always the same at a certain time of the year in a given place. The photoperiod is like a trigger mechanism that sequentially includes physiological processes leading to growth and flowering of plants in the spring, fruiting in the summer and shedding of leaves in the fall, as well as molting and accumulation of fat, migration and reproduction in birds and mammals, and the onset of the resting stage in insects .

In addition to seasonal changes, the change of day and night determines the daily rhythm of activity of both entire organisms and physiological processes. The ability of organisms to sense time, the presence of a “biological clock” is an important adaptation that ensures the survival of an individual in given environmental conditions.

Infrared radiation accounts for 45% of the total amount of radiant energy falling on the Earth. Infrared rays increase the temperature of plant and animal tissues and are well absorbed by inanimate objects, including water.

For plant productivity, i.e. education organic matter, the most important indicator is the total direct solar radiation received over long periods of time (months, year).

Humidity. Water is a necessary component of the cell, so its quantity in certain habitats serves as a limiting factor for plants and animals and determines the nature of the flora and fauna in a given area. Excess water in the soil leads to the development of marsh vegetation. Depending on soil moisture (and annual precipitation), the species composition of plant communities changes. With annual precipitation of 250 mm or less, a desert landscape develops. The uneven distribution of precipitation across seasons also represents an important limiting factor for organisms. In this case, plants and animals have to endure long droughts. During a short period of high soil moisture, primary production for the community as a whole accumulates. It determines the size of the annual food supply for animals and saprophages (from the Greek. sapros- rotten and phagos - eater) - organisms that decompose organic remains.

In nature, as a rule, there are daily fluctuations in air humidity, which, along with light and temperature, regulate the activity of organisms. Humidity as an environmental factor is important because it modifies the effect of temperature. Temperature has a more pronounced effect on the body if the humidity is very high or low. Likewise, the role of humidity increases if temperatures are close to the species' tolerance limits. Species of plants and animals living in areas with insufficient moisture have, through the process of natural selection, effectively adapted to unfavorable conditions aridity. Such plants have a powerfully developed root system, increased osmotic pressure of cell sap, which promotes water retention in tissues, a thickened leaf cuticle, and a greatly reduced leaf blade or turned into spines. In some plants (saxaul), leaves are lost, and photosynthesis is carried out by green stems. In the absence of water, the growth of desert plants stops, while moisture-loving plants wither and die in such conditions. Cacti are capable of storing a large number of water in tissues and spend it sparingly. A similar adaptation was found in African desert milkweeds, which serves as an example of the parallel evolution of unrelated groups under similar environmental conditions.

Desert animals also have a range of physiological adaptations to cope with water shortages. Small animals - rodents, reptiles, arthropods - extract water from food. Fat, which accumulates in large quantities in some animals (the hump of a camel), also serves as a source of water. During the hot season, many animals (rodents, turtles) hibernate, lasting several months.

Ionizing radiation. Radiation with very high energy, which can lead to the formation of pairs of positive and negative ions, is called ionizing. Its source is radioactive substances contained in rocks; Moreover, it comes from space.

Intensity ionizing radiation V environment has increased significantly as a result of human use atomic energy. Testing of atomic weapons, nuclear power plants, obtaining fuel for them and disposal of waste, medical research and other peaceful uses of nuclear energy create local “hot spots” and generate waste, often released into the environment during transportation or storage.

Of the three types of ionizing radiation that have important environmental significance, two are corpuscular radiation (alpha and beta particles), and the third is electromagnetic (gamma radiation and related x-rays).

Corpuscular radiation consists of a stream of atomic or subatomic particles that transfer their energy to whatever they encounter. Alpha radiation is helium nuclei; they are huge in size compared to other particles. The length of their run in the air is only a few centimeters. Beta radiation is fast electrons. Their dimensions are much smaller, the length of travel in the air is several meters, and in the tissues of an animal or plant organism - several centimeters. Regarding ionizing electromagnetic radiation, then it is similar to light, only its wavelength is much shorter. It travels long distances in the air and easily penetrates matter, releasing its energy along a long trail. Gamma radiation, for example, easily penetrates living tissue; this radiation can pass through the body without having any effect, or it can cause ionization along a large portion of its path. Biologists often refer to radiation substances that emit alpha and beta radiation as “intrinsic emitters,” because they have their greatest effect when they are absorbed, ingested, or otherwise end up inside the body. Radioactive substances that emit predominantly gamma radiation are classified as “external emitters” because this penetrating radiation can have an effect when its source is outside the body.

Cosmic and ionizing radiation emitted by natural radioactive substances contained in water and soil form the so-called background radiation, to which existing animals and plants are adapted. IN different parts The natural background of the biosphere differs by 3-4 times. Its lowest intensity is observed near the surface of the sea, and the highest at high altitudes in mountains formed by granite rocks. The intensity of cosmic radiation increases with altitude, and granite rocks contain more naturally occurring radionuclides than sedimentary rocks.

In general, ionizing radiation affects more highly developed and complex organisms the most destructive effect, and the person is particularly sensitive.

Large doses received by the body in a short time (minutes or hours) are called acute doses, as opposed to chronic doses that the body could withstand throughout its life. life cycle. The effects of low chronic doses are more difficult to measure as they may cause long-term genetic and somatic effects. Any increase in the level of radiation in the environment above the background, or even a high natural background, can increase the frequency of harmful mutations.

In higher plants, sensitivity to ionizing radiation is directly proportional to the size of the cell nucleus. In higher animals no such simple or direct relationship has been found between sensitivity and cell structure; For them, the sensitivity of individual organ systems is more important. Thus, mammals are very sensitive even to low doses due to the fact that rapidly dividing hematopoietic tissue, the bone marrow, is easily damaged by irradiation. Sensitive and digestive tract, and damage to non-fissile nerve cells are observed only when high levels irradiation.

Once in the environment, radionuclides are dispersed and diluted, but they can different ways accumulate in living organisms as they move along the food chain. Radioactive substances can also accumulate in water, soil, sediment, or air if the rate of release exceeds the rate of natural radioactive decay.

Pollutants. Human living conditions and the stability of natural biogeocenoses have been rapidly deteriorating over the past decades due to environmental pollution by substances resulting from human production activities. These substances can be divided into two groups: natural compounds, which are waste products from technological processes, and artificial compounds, which are not found in nature.

The first group includes sulfur dioxide (copper smelting), carbon dioxide (thermal power plants), oxides of nitrogen, carbon, hydrocarbons, compounds of copper, zinc and mercury, etc., mineral fertilizers (mainly nitrates and phosphates).

The second group includes artificial substances, having special properties that satisfy human needs: pesticides (from lat. pestis - infection, destruction and cido - kill), used to control animal pests of agricultural crops, antibiotics used in medicine and veterinary medicine to treat infectious diseases. Pesticides include insecticides (from Lat. insecta- insects and cido- kill) - means to combat harmful insects and herbicides (from lat. herba- grass, plant and cido- kill) - means to control weeds.

All of them have a certain toxicity (poisonous) to humans. At the same time, they serve as anthropogenic abiotic environmental factors that have a significant impact on the species composition of biogeocenoses. This influence is expressed in changes in soil properties (acidification, transition of toxic elements into a soluble state, disruption of the structure, depletion of its species composition); changes in water properties (increased mineralization, increased content of nitrates and phosphates, acidification, saturation with surfactants); changing the ratio of elements in soil and water, which leads to a deterioration in the development conditions of plants and animals.

Such changes serve as selection factors, as a result of which new plant and animal communities with a depleted species composition are formed.

Changes in environmental factors in terms of their effect on organisms can be: 1) regularly periodic, for example due to the time of day, season of the year or the rhythm of ebbs and flows in the ocean; 2) irregular, for example, changes in weather conditions in different years, disasters (storms, showers, landslides, etc.); 3) directed: during cooling or warming of the climate, overgrowing of water bodies, etc. Populations of organisms living in a particular environment adapt to this variability through natural selection. They develop certain morphological and physiological characteristics, allowing one to exist precisely in these and in no other environmental conditions. For each factor influencing the body, there is a favorable force of influence, called the zone of optimum of the environmental factor or simply its optimum. For organisms of this species, deviation from the optimal intensity of the factor (decrease or increase) inhibits vital activity. The boundaries beyond which the death of the organism occurs are called the upper and lower limits of endurance (Fig. 25.5).

Rice. 25.5. Intensity of environmental factors

Anchor points

Most species of organisms are adapted to life in a narrow range of temperatures; optimal values temperatures range from +15 to +30 °C.
Light in the form of solar radiation powers all life processes on Earth.
Cosmic and ionizing radiation emitted by natural radioactive substances form “background” radiation to which existing plants and animals are adapted.
Pollutants having toxic effect on living organisms, deplete the species composition of biocenoses.

Questions and tasks for review

1. What are abiotic environmental factors?
2. What adaptations do plants and animals have to changes in environmental temperature?
3. Indicate which part of the spectrum of visible radiation from the Sun is most actively absorbed by the chlorophyll of green plants?
4. Tell us about the adaptations of living organisms to a lack of water.
5. Describe the impact various types ionizing radiation on animal and plant organisms.
6. What is the influence of pollutants on the state of biogeocenoses?

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.

DURING THE CLASSES

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 impact 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 soil - 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, in the most high 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, can withstand quite low temperatures. Temperature fluctuations in water are usually less than on land, so the limits of temperature tolerance of aquatic organisms are worse than those of terrestrial organisms. 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 of 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, individual species 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 arterial blood, oxygenated, feathers or body hair that 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. Auricle In addition to the organ of hearing, it functions 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:

photophilous– 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, located 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. Broad-leaved forests give way to 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 vital processes are slowed down to a minimum and all visible signs life (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:(Annex 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(

Introduction

Every day, rushing about business, you walk down the street, shivering from the cold or sweating from the heat. And after a working day, you go to the store and buy food. Leaving the store, you hastily stop a passing minibus and helplessly sit down on the nearest free seat. For many, this is a familiar way of life, isn't it? Have you ever thought about how life works from an environmental point of view? The existence of humans, plants and animals is possible only through their interaction. It cannot do without the influence of inanimate nature. Each of these types of impact has its own designation. So, there are only three types of impact on the environment. These are anthropogenic, biotic and abiotic factors. Let's look at each of them and its impact on nature.

1. Anthropogenic factors - influence on the nature of all forms of human activity

When this term is mentioned, not a single positive thought comes to mind. Even when people do something good for animals and plants, it happens because of the consequences of previously doing something bad (for example, poaching).

Anthropogenic factors (examples):

Drying swamps.
Fertilizing fields with pesticides.
Poaching.
Industrial waste (photo).

Conclusion

As you can see, basically humans only cause harm to the environment. And due to the increase in economic and industrial production, even environmental measures established by rare volunteers (the creation of nature reserves, environmental rallies) are no longer helping.

2. Biotic factors - the influence of living nature on various organisms

Simply put, it is the interaction of plants and animals with each other. It can be both positive and negative. There are several types of such interaction:

1. Competition - such relationships between individuals of the same or different species in which the use of a certain resource by one of them reduces its availability for others. In general, in competition, animals or plants fight among themselves for their piece of bread

2. Mutualism is a relationship in which each species receives a certain benefit. Simply put, when plants and/or animals complement each other harmoniously.

3. Commensalism is a form of symbiosis between organisms of different species, in which one of them uses the host’s home or organism as a place of settlement and can feed on food remains or products of its vital activity. At the same time, it brings neither harm nor benefit to the owner. All in all, a small, unnoticeable addition.

Biotic factors (examples):

Coexistence of fish and coral polyps, flagellated protozoans and insects, trees and birds (eg woodpeckers), mynah starlings and rhinoceroses.

Conclusion

Despite the fact that biotic factors can be harmful to animals, plants and humans, they also have great benefits.

3. Abiotic factors - the impact of inanimate nature on a variety of organisms

Yes, and inanimate nature also plays an important role in the life processes of animals, plants and humans. Perhaps the most important abiotic factor is weather.

Abiotic factors: examples

Abiotic factors are temperature, humidity, light, salinity of water and soil, as well as the air and its gas composition.

Conclusion

Abiotic factors can be harmful to animals, plants and humans, but they still generally benefit them

Bottom line

The only factor that does not benefit anyone is anthropogenic. Yes, it also does not bring anything good to a person, although he is sure that he is changing nature for his own good, and does not think about what this “good” will turn into for him and his descendants in ten years. Humans have already completely destroyed many species of animals and plants that had their place in the world ecosystem. The Earth's biosphere is like a film in which there are no minor roles, all of them are the main ones. Now imagine that some of them were removed. What will happen in the film? This is how it is in nature: if the smallest grain of sand disappears, the great building of Life will collapse.