Environmental factors and their classification. The most important abiotic factors and adaptation of living organisms to them

The following groups of abiotic factors (factors of inanimate nature) are distinguished: climatic, edaphogenic (soil), orographic and chemical.

I) Climatic factors: these include solar radiation, temperature, pressure, wind and some other environmental influences.

1) Solar radiation is a powerful environmental factor. It propagates in space in the form of electromagnetic waves, of which 48% are in the visible part of the spectrum, 45% in infrared radiation (long wavelength) and about 7% in short-wave ultraviolet radiation. Solar radiation is the primary source of energy, without which life on Earth is impossible. But in other way, direct impact sunlight (especially its ultraviolet component) is harmful to living cells. The evolution of the biosphere was aimed at reducing the intensity of the ultraviolet part of the spectrum and protecting against excess solar radiation. This was facilitated by the formation of ozone (ozone layer) from oxygen released by the first photosynthetic organisms.

The total amount of solar energy reaching the Earth is approximately constant. But different points on the earth’s surface receive different amounts of energy (due to differences in the time of illumination, different angles of incidence, degree of reflection, transparency of the atmosphere, etc.)

A close connection has been revealed between solar activity and the rhythm of biological processes. The more solar activity (more sunspots), the more disturbances in the atmosphere, magnetic storms affecting living organisms. An important role is also played by the change in solar activity during the day, which determines the circadian rhythms of the body. In humans, more than 100 physiological characteristics are subject to the daily cycle (hormone secretion, respiratory rate, functioning of various glands, etc.)

Solar radiation largely determines other climatic factors.

2) Ambient temperature is related to the intensity of solar radiation, especially the infrared part of the spectrum. The life activity of most organisms proceeds normally in the temperature range from +5 to 40 0 ​​C. Above +50 0 − +60 0, irreversible destruction of the protein that is part of living tissues begins. At high pressures the upper temperature limit can be much higher (up to +150−200 0 C). The lower temperature limit is often less critical. Some living organisms are able to withstand very low temperatures (up to −200 0 C) in a state of suspended animation. Many organisms in the Arctic and Antarctic constantly live at subzero temperatures. In some arctic fish normal temperature body is −1.7 0 C. At the same time, the water in their narrow capillaries does not freeze.

The dependence of the intensity of vital activity of most living organisms on temperature has the following form:

Fig. 12. Dependence of vital activity of organisms on temperature

As can be seen from the figure, as the temperature rises, biological processes accelerate (the rate of reproduction and development, the amount of food consumed). For example, the development of cabbage butterfly caterpillars at +10 0 C requires 100 days, and at +26 0 C - only 10 days. But a further increase in temperature leads to sharp decline vital parameters and death of the organism.

In water, the range of temperature fluctuations is smaller than on land. Therefore, aquatic organisms are less adapted to temperature changes than terrestrial ones.

Temperature often determines zonality in terrestrial and aquatic biogeocenoses.

3) Ambient humidity is an important environmental factor. Most living organisms consist of 70–80% water, a substance necessary for the existence of protoplasm. The humidity of the area is determined by the humidity of the atmospheric air, the amount of precipitation, and the area of ​​water reserves.

Air humidity depends on temperature: the higher it is, the more water is usually contained in the air. The lower layers of the atmosphere are richest in moisture. Precipitation is the result of condensation of water vapor. In the temperate climate zone, the distribution of precipitation by season is more or less uniform, in the tropics and subtropics it is uneven. The available supply of surface water depends on underground sources and rainfall.

The interaction of temperature and humidity creates two climates: maritime and continental.

4) Pressure is another climatic factor that is important for all living organisms. There are areas on Earth with permanently high or low pressure. Pressure drops are associated with unequal heating of the earth's surface.

5) Wind is the directional movement of air masses resulting from pressure differences. The wind flow is directed from an area with high pressure to an area with lower pressure. It affects temperature, humidity and the movement of impurities in the air.

6) Lunar rhythms determine the ebb and flow of tides, to which marine animals are adapted. They use the ebb and flow of tides for many life processes: movement, reproduction, etc.

ii) Edaphogenic factors determine various soil characteristics. Soil plays an important role in terrestrial ecosystems - the role of a reservoir and reserve of resources. The composition and properties of soils are strongly influenced by climate, vegetation and microorganisms. Steppe soils are more fertile than forest soils, since grasses are short-lived and each year a large amount of organic matter enters the soil, which quickly decomposes. Ecosystems without soil are usually very unstable. The following main characteristics of soils are distinguished: mechanical composition, moisture capacity, density and air permeability.

The mechanical composition of soils is determined by the content of particles of different sizes in it. There are four types of soils, depending on their mechanical composition: sand, sandy loam, loam, clay. The mechanical composition directly affects plants, underground organisms, and through them, other organisms. The moisture capacity (the ability to retain moisture), their density and air permeability of soils depend on the mechanical composition.

III) Orographic factors. These include the height of the area above sea level, its relief and location relative to the cardinal points. Orographic factors largely determine the climate of a given area, as well as other biotic and abiotic factors.

IV) Chemical factors. These include the chemical composition of the atmosphere (gas composition of the air), lithosphere, and hydrosphere. For living organisms, the content of macro- and microelements in the environment is of great importance.

Macroelements are elements required by the body in relatively large quantities. For most living organisms these are phosphorus, nitrogen, potassium, calcium, sulfur, magnesium.

Microelements are elements required by the body in extremely small quantities, but are part of vital enzymes. Microelements are necessary for the normal functioning of the body. The most common microelements are metals, silicon, boron, chlorine.

There is no clear boundary between macroelements and microelements: what is a microelement for some organisms is a macroelement for another.

Light is one of the main environmental factors. Without light, the photosynthetic activity of plants is impossible, and without the latter, life in general is unthinkable, since green plants have the ability to produce the oxygen necessary for all living beings. In addition, light is the only source of heat on planet Earth. It has a direct effect on chemical and physical processes, occurring in organisms, affects metabolism.

Many morphological and behavioral characteristics of various organisms are associated with their exposure to light. The activity of some internal organs of animals is also closely related to lighting. Animal behavior, such as seasonal migration, egg laying, courtship, and spring rutting, is associated with the length of daylight hours.

In ecology, the term “light” refers to the entire range of solar radiation reaching the earth’s surface. The distribution spectrum of solar radiation energy outside the Earth's atmosphere shows that about half of the solar energy is emitted in the infrared region, 40% in the visible and 10% in the ultraviolet and x-ray regions.

For living matter, the qualitative characteristics of light are important - wavelength, intensity and duration of exposure. There are near ultraviolet radiation (400-200 nm) and far, or vacuum (200-10 nm). Sources of ultraviolet radiation are high-temperature plasma, accelerated electrons, some lasers, the Sun, stars, etc. The biological effect of ultraviolet radiation is caused by chemical changes in the molecules of living cells that absorb them, mainly molecules of nucleic acids (DNA and RNA) and proteins, and is expressed in division disorders , the occurrence of mutations and cell death.

Some of the sun's rays, having traveled a huge distance, reach the surface of the Earth, illuminate and heat it. It is estimated that our planet receives about one two-billionth of solar energy, and of this amount, only 0.1-0.2% is used by green plants to create organic matter. Each square meter of the planet receives an average of 1.3 kW of solar energy. It would be enough to operate an electric kettle or iron.

Lighting conditions play an exceptional role in the life of plants: their productivity and productivity depend on the intensity of sunlight. However, the light regime on Earth is quite diverse. It is different in the forest than in the meadow. Lighting in deciduous and dark coniferous spruce forests is noticeably different.

Light controls the growth of plants: they grow in the direction of greater light. Their sensitivity to light is so great that the shoots of some plants, kept in darkness during the day, react to a flash of light that lasts only two thousandths of a second.

All plants in relation to light can be divided into three groups: heliophytes, sciophytes, facultative heliophytes.

Heliophytes(from the Greek helios - sun and phyton - plant), or light-loving plants, either do not tolerate at all or do not tolerate even slight shading. This group includes steppe and meadow grasses, tundra plants, early spring plants, most open ground cultivated plants, and many weeds. Among the species of this group we can find common plantain, fireweed, reed grass, etc.

Sciophytes(from the Greek scia - shadow), or shade plants, do not tolerate strong light and live in constant shade under the forest canopy. These are mainly forest herbs. With a sharp lightening of the forest canopy, they become depressed and often die, but many rebuild their photosynthetic apparatus and adapt to life in new conditions.

Facultative heliophytes, or shade-tolerant plants, are able to develop in both very high and low amounts of light. As an example, we can name some trees - common spruce, Norway maple, common hornbeam; shrubs - hazel, hawthorn; herbs - strawberries, field geranium; many indoor plants.

An important abiotic factor is temperature. Any organism is capable of living within a certain temperature range. The distribution area of ​​living things is mainly limited to the area from just below 0 °C to 50 °C.

The main source of heat, as well as light, is solar radiation. An organism can survive only under conditions to which its metabolism is adapted. If the temperature of a living cell drops below freezing, the cell is usually physically damaged and dies as a result of the formation of ice crystals. If the temperature is too high, protein denaturation occurs. This is exactly what happens when you boil a chicken egg.

Most organisms are able to control their body temperature to some extent through various responses. In the vast majority of living beings, body temperature can vary depending on the ambient temperature. Such organisms are unable to regulate their temperature and are called cold-blooded (poikilothermic). Their activity mainly depends on heat coming from outside. The body temperature of poikilothermic organisms is related to the ambient temperature values. Cold-bloodedness is characteristic of such groups of organisms as plants, microorganisms, invertebrates, fish, reptiles, etc.

A significantly smaller number of living beings are capable of actively regulating body temperature. These are representatives of the two highest classes of vertebrates - birds and mammals. The heat they generate is a product of biochemical reactions and serves as a significant source of increased body temperature. This temperature is maintained at a constant level regardless of the ambient temperature. Organisms that are able to maintain a constant optimal body temperature regardless of the ambient temperature are called warm-blooded (homeothermic). Due to this property, many species of animals can live and reproduce at temperatures below zero (reindeer, polar bear, pinnipeds, penguin). Maintaining a constant body temperature is ensured by good thermal insulation created by fur, dense plumage, subcutaneous air cavities, a thick layer of adipose tissue, etc.

A special case of homeothermy is heterothermy (from the Greek heteros - different). Different level body temperature in heterothermic organisms depends on their functional activity. During the period of activity they have constant temperature body, and during the period of rest or hibernation the temperature drops significantly. Heterothermy is characteristic of gophers, marmots, badgers, bats, hedgehogs, bears, hummingbirds, etc.

Humidification conditions play a special role in the life of living organisms.

Water- the basis of living matter. For most living organisms, water is one of the main environmental factors. This is the most important condition for the existence of all life on Earth. All life processes in the cells of living organisms take place in an aquatic environment.

Water is not chemically changed by most of the technical compounds it dissolves. This is very important for living organisms, since the nutrients necessary for their tissues are supplied in aqueous solutions in a relatively little changed form. Under natural conditions, water always contains one or another amount of impurities, not only interacting with solid and liquid substances, but also dissolving gases.

The unique properties of water predetermine its special role in the formation of the physical and chemical environment of our planet, as well as in the emergence and maintenance of an amazing phenomenon - life.

The human embryo consists of 97% water, and in newborns its amount is 77% of body weight. By the age of 50, the amount of water in the human body decreases and already accounts for 60% of its mass. The main part of the water (70%) is concentrated inside the cells, and 30% is intercellular water. Human muscles are 75% water, the liver is 70%, the brain is 79%, and the kidneys are 83%.

The body of an animal, as a rule, contains at least 50% water (for example, an elephant - 70%, a caterpillar eating plant leaves - 85-90%, jellyfish - more than 98%).

The elephant needs the most water (based on daily needs) of any land animal - about 90 liters. Elephants are one of the best “hydrogeologists” among animals and birds: they sense bodies of water at a distance of up to 5 km! Only the bison are further away - 7-8 km. In dry times, elephants use their tusks to dig holes in dry river beds to collect water. Buffaloes, rhinoceroses and other African animals readily use elephant wells.

The distribution of life on Earth is directly related to precipitation. Humidity is not the same in different parts of the world. The most precipitation falls in the equatorial zone, especially in the upper reaches of the Amazon River and on the islands of the Malay Archipelago. Their number in some areas reaches 12,000 mm per year. So, on one of the Hawaiian islands it rains from 335 to 350 days a year. This is the wettest place on Earth. The average annual precipitation here reaches 11,455 mm. By comparison, the tundra and deserts receive less than 250 mm of precipitation per year.

Animals relate to moisture differently. Water as a physical and chemical body has a continuous impact on the life of hydrobionts (aquatic organisms). It not only satisfies the physiological needs of organisms, but also delivers oxygen and food, carries away metabolites, and transports sexual products and aquatic organisms themselves. Thanks to the mobility of water in the hydrosphere, the existence of attached animals is possible, which, as is known, do not exist on land.

Edaphic factors

The entire set of physical and chemical properties soils that have an ecological impact on living organisms are classified as edaphic factors (from the Greek edaphos - foundation, earth, soil). The main edaphic factors are the mechanical composition of the soil (size of its particles), relative looseness, structure, water permeability, aeration, chemical composition of the soil and substances circulating in it (gases, water).

The nature of the soil granulometric composition may have ecological significance for animals that, at a certain period of life, live in the soil or lead a burrowing lifestyle. Insect larvae generally cannot live in soil that is too rocky; burrowing Hymenoptera, laying eggs in underground passages, many locusts, burying egg cocoons in the ground, need it to be sufficiently loose.

An important characteristic of soil is its acidity. It is known that the acidity of the medium (pH) characterizes the concentration of hydrogen ions in the solution and is numerically equal to the negative decimal logarithm of this concentration: pH = -log. Aqueous solutions can have a pH from 0 to 14. Neutral solutions have a pH of 7, acidic solutions are characterized by pH values ​​less than 7, and alkaline solutions are characterized by pH values ​​greater than 7. Acidity can serve as an indicator of the rate of general metabolism of a community. If the pH of the soil solution is low, this means that the soil contains few nutrients, so its productivity is extremely low.

In relation to soil fertility, the following ecological groups of plants are distinguished:

• oligotrophs (from the Greek olygos - small, insignificant and trophe - food) - plants of poor, infertile soils (Scots pine);
• mesotrophs (from the Greek mesos - average) - plants with a moderate need for nutrients (most forest plants of temperate latitudes);
• eutrophic(from the Greek she - good) - plants that require a large amount of nutrients in the soil (oak, hazel, gooseberry).

Orographic factors

The distribution of organisms on the earth's surface is influenced to a certain extent by factors such as features of relief elements, altitude above sea level, exposure and steepness of slopes. They are combined into a group of orographic factors (from the Greek oros - mountain). Their impact can greatly influence local climate and soil development.

One of the main orographic factors is altitude above sea level. With altitude, average temperatures decrease, daily temperature differences increase, precipitation, wind speed and radiation intensity increase, atmospheric pressure and gas concentrations decrease. All these factors influence plants and animals, causing vertical zonation.

A typical example is vertical zoning in the mountains. Here, with every 100 m rise, the air temperature decreases by an average of 0.55 °C. At the same time, humidity changes and the length of the growing season shortens. As the altitude of the habitat increases, the development of plants and animals changes significantly. At the foot of the mountains there may be tropical seas, and at the top arctic winds blow. On one side of the mountains it can be sunny and warm, on the other it can be damp and cold.

Another orographic factor is slope exposure. On the northern slopes the plants form shadow forms, and on the southern slopes they form light forms. The vegetation here is represented mainly by drought-resistant shrubs. South-facing slopes receive more sunlight, so the light intensity and temperature here are higher than on valley floors and northern-facing slopes. This is associated with significant differences in the heating of air and soil, the rate of snow melting, and soil drying.

An important factor is the steepness of the slope. The influence of this indicator on the living conditions of organisms is reflected mainly through the characteristics of the soil environment, water and temperature regimes. Steep slopes are characterized by rapid drainage and soil washing away, so the soils here are thin and drier. If the slope exceeds 35°, slides of loose material are usually created.

Hydrographic factors

Hydrographic factors include such characteristics of the aquatic environment as water density, the speed of horizontal movements (current), the amount of oxygen dissolved in water, the content of suspended particles, flow, temperature and light regimes of water bodies, etc.

Organisms that live in the aquatic environment are called hydrobionts.

Different organisms have adapted to the density of water and certain depths in their own way. Some species can withstand pressures from several to hundreds of atmospheres. Many fish, cephalopods, crustaceans, and starfish live at great depths at a pressure of about 400-500 atm.

The high density of water ensures the existence of many non-skeletal forms in the aquatic environment. These are small crustaceans, jellyfish, unicellular algae, keeled and pteropod mollusks, etc.

The high specific heat capacity and high thermal conductivity of water determine the more stable temperature regime of water bodies compared to land. The amplitude of annual temperature fluctuations does not exceed 10-15 °C. In continental waters it is 30-35 °C. In the reservoirs themselves, the temperature conditions between the upper and lower layers of water differ significantly. In the deep layers of the water column (in the seas and oceans), the temperature regime is stable and constant (3-4 °C).

An important hydrographic factor is the light regime of water bodies. The amount of light quickly decreases with depth, so in the World Ocean algae live only in the illuminated zone (most often at depths from 20 to 40 m). The density of marine organisms (their number per unit area or volume) naturally decreases with depth.

Chemical factors

Action chemical factors manifests itself in the form of penetration into the environment of chemical substances that were not present in it before, which is largely due to modern anthropogenic influence.

A chemical factor such as gas composition is extremely important for organisms living in the aquatic environment. For example, in the waters of the Black Sea there is a lot of hydrogen sulfide, which makes this pool not entirely favorable for the life of some animals in it. The rivers that flow into it carry with them not only pesticides or heavy metals washed off from the fields, but also nitrogen and phosphorus. And this is not only agricultural fertilizer, but also food for marine microorganisms and algae, which, due to an excess of nutrients, begin to develop rapidly (water blooms). When they die, they sink to the bottom and consume a significant amount of oxygen during the process of decay. Over the past 30-40 years, the bloom of the Black Sea has increased significantly. In the lower layer of water, oxygen is replaced by poisonous hydrogen sulfide, so there is practically no life here. The organic world of the sea is relatively poor and monotonous. Its living layer is limited to a narrow surface 150 m thick. As for terrestrial organisms, they are insensitive to the gas composition of the atmosphere, since it is constant.

The group of chemical factors also includes such an indicator as water salinity (the content of soluble salts in natural waters). Based on the amount of dissolved salts, natural waters are divided into the following categories: fresh water- up to 0.54 g/l, brackish - from 1 to 3, slightly salted - from 3 to 10, salty and very salty water - from 10 to 50, brine - more than 50 g/l. Thus, in fresh water bodies on land (streams, rivers, lakes) 1 kg of water contains up to 1 g of soluble salts. Sea water is a complex salt solution, the average salinity of which is 35 g/kg of water, i.e. 3.5%.

Living organisms living in an aquatic environment are adapted to a strictly defined salinity of water. Freshwater forms cannot live in the seas, and marine forms cannot tolerate desalination. If the salinity of the water changes, animals move in search of a favorable environment. For example, when the surface layers of the sea are desalinated after heavy rains, some species of sea crustaceans descend to a depth of up to 10 m.

Oyster larvae live in the brackish waters of small bays and estuaries (semi-enclosed coastal bodies of water that freely communicate with the ocean or sea). The larvae grow especially quickly when the water salinity is 1.5-1.8% (somewhere between fresh and salt water). At a higher salt content, their growth is somewhat suppressed. When the salt content decreases, growth is already noticeably suppressed. At a salinity of 0.25%, the growth of larvae stops and they all die.

Pyrogenic factors

These include fire exposure factors, or fires. Currently, fires are considered to be a very significant and one of the natural abiotic environmental factors. At correct use fire can be a very valuable environmental tool.

At first glance, fires are negative factor. But in reality this is not the case. Without fires, the savannah, for example, would quickly disappear and be covered with dense forest. However, this does not happen, since the tender shoots of the trees die in the fire. Because trees grow slowly, few survive fires and grow tall enough. Grass grows quickly and recovers just as quickly after fires.

It should be noted that, unlike other environmental factors, people can regulate fires, and therefore they can become a certain limiting factor in the spread of plants and animals. Controlled by people fires contribute to the formation of ash rich in useful substances. Mixing with the soil, ash stimulates the growth of plants, the quantity of which determines the life of animals.

In addition, many savanna inhabitants, such as the African stork and the secretary bird, use fires for their own purposes. They visit the boundaries of natural or controlled fires and eat insects and rodents there that escape the fire.

Fires can be caused by both natural factors (lightning strikes) and random and non-random human actions. There are two types of fires. Roof fires are the most difficult to contain and regulate. Most often they are very intense and destroy all vegetation and soil organic matter. Such fires have a limiting effect on many organisms.

Ground fires, on the contrary, have a selective effect: for some organisms they are more destructive, for others - less and, thus, contribute to the development of organisms with high resistance to fires. In addition, small ground fires complement the action of bacteria, decomposing dead plants and accelerating the conversion of mineral nutrients into a form suitable for use by new generations of plants. In habitats with infertile soil, fires contribute to its enrichment with ash elements and nutrients.

When there is sufficient moisture (North American prairies), fires stimulate the growth of grasses at the expense of trees. Fires play a particularly important regulatory role in steppes and savannas. Here, periodic fires reduce the likelihood of desert shrub invasion.

Humans are often the cause of an increase in the frequency of wild fires, although a private individual has no right to intentionally (even accidentally) cause a fire in nature. However, the use of fire by specialists is part of proper land management.

The environment that surrounds living beings consists of many elements. They affect the life of organisms in different ways. The latter react differently to various environmental factors. Individual elements of the environment that interact with organisms are called environmental factors. Conditions of existence are a set of vital environmental factors, without which living organisms cannot exist. In relation to organisms, they act as environmental factors.

Classification of environmental factors.

All environmental factors accepted classify(distribute) into the following main groups: abiotic, biotic And anthropic. V Abiotic (abiogenic) factors are physical and chemical factors of inanimate nature. Biotic, or biogenic, factors are the direct or indirect influence of living organisms both on each other and on the environment. Anthropogenic (anthropogenic) In recent years, factors have been identified as a separate group of biotic factors due to their great importance. These are factors of direct or indirect impact of man and his economic activities on living organisms and the environment.

Abiotic factors.

Abiotic factors include elements of inanimate nature that act on a living organism. Types of abiotic factors are presented in table. 1.2.2.

Table 1.2.2. Main types of abiotic factors

Climatic factors.

All abiotic factors manifest themselves and act within the three geological shells of the Earth: atmosphere, hydrosphere And lithosphere. Factors that manifest themselves (act) in the atmosphere and during the interaction of the latter with the hydrosphere or with the lithosphere are called climatic. their manifestation depends on the physical and chemical properties of the geological shells of the Earth, on the amount and distribution of solar energy penetrating and reaching them.

Solar radiation.

Among the variety of environmental factors, solar radiation is of greatest importance. (solar radiation). This is a continuous stream of elementary particles (speed 300-1500 km/s) and electromagnetic waves (speed 300 thousand km/s), which carries towards the Earth great amount energy. Solar radiation is the main source of life on our planet. Under the continuous flow of solar radiation, life arose on Earth, went through a long path of evolution and continues to exist and depend on solar energy. The main properties of the radiant energy of the Sun as an environmental factor are determined by the wavelength. Waves passing through the atmosphere and reaching the Earth are measured in the range of 0.3 to 10 microns.

Based on the nature of the impact on living organisms, this spectrum of solar radiation is divided into three parts: ultraviolet radiation, visible light And infrared radiation.

Short-wave ultraviolet rays are almost completely absorbed by the atmosphere, namely its ozone screen. A small amount of ultraviolet rays penetrates the surface of the earth. Their wavelength lies in the range of 0.3-0.4 microns. They account for 7% of solar radiation energy. Short-wave rays have a detrimental effect on living organisms. They can cause changes in hereditary material - mutations. Therefore, in the process of evolution, organisms that have been exposed to solar radiation for a long time have developed adaptations to protect against ultraviolet rays. Many of them produce additional amounts of black pigment in their integument - melanin, which protects against the penetration of unwanted rays. This is why people get a tan by being outdoors for a long time. In many industrial regions there is a so-called industrial melanism- darkening of the color of animals. But this does not happen under the influence of ultraviolet radiation, but due to contamination with soot and environmental dust, the elements of which usually become darker. Against such a dark background, darker forms of organisms survive (are well camouflaged).

Visible light appears within wavelengths from 0.4 to 0.7 µm. It accounts for 48% of solar radiation energy.

It also adversely affects living cells and their functions in general: it changes the viscosity of the protoplasm, the magnitude of the electrical charge of the cytoplasm, disrupts the permeability of membranes and changes the movement of the cytoplasm. Light affects the state of protein colloids and the course of energy processes in cells. But despite this, visible light was, is and will continue to be one of the most important sources of energy for all living things. Its energy is used in the process photosynthesis and accumulates in the form of chemical bonds in the products of photosynthesis, and is then transmitted as food to all other living organisms. In general, we can say that all living things in the biosphere, and even humans, depend on solar energy, on photosynthesis.

Light for animals is necessary condition perception of information about the environment and its elements, vision, visual orientation in space. Depending on their living conditions, animals have adapted to varying degrees illumination Some animal species are diurnal, while others are most active at dusk or at night. Most mammals and birds lead a twilight lifestyle, have difficulty distinguishing colors and see everything in black and white (canines, cats, hamsters, owls, nightjars, etc.). Living in twilight or low light conditions often leads to eye hypertrophy. Relatively huge eyes, capable of capturing tiny fractions of light, characteristic of nocturnal animals or those that live in complete darkness and are guided by the luminescent organs of other organisms (lemurs, monkeys, owls, deep-sea fish, etc.). If, in conditions of complete darkness (in caves, underground in burrows) there are no other sources of light, then the animals living there, as a rule, lose their organs of vision (European proteus, mole rat, etc.).

Temperature.

The sources of the temperature factor on Earth are solar radiation and geothermal processes. Although the core of our planet is characterized by extremely high temperatures, its influence on the surface of the planet is insignificant, except for zones of volcanic activity and the release of geothermal waters (geysers, fumaroles). Consequently, the main source of heat within the biosphere can be considered solar radiation, namely infrared rays. Those rays that reach the Earth's surface are absorbed by the lithosphere and hydrosphere. The lithosphere, as a solid body, heats up faster and cools just as quickly. The hydrosphere has a higher heat capacity than the lithosphere: it heats up slowly and cools down slowly, and therefore retains heat for a long time. The surface layers of the troposphere are heated due to the radiation of heat from the hydrosphere and the surface of the lithosphere. The Earth absorbs solar radiation and radiates energy back into airless space. And yet, the Earth's atmosphere helps retain heat in the surface layers of the troposphere. Thanks to its properties, the atmosphere transmits short-wave infrared rays and blocks long-wave infrared rays emitted by the heated surface of the Earth. This atmospheric phenomenon has a name greenhouse effect. It was thanks to him that life became possible on Earth. The greenhouse effect helps retain heat in the surface layers of the atmosphere (where most organisms are concentrated) and smoothes out temperature fluctuations during the day and night. On the Moon, for example, which is located in almost the same space conditions as the Earth, and which has no atmosphere, daily temperature fluctuations at its equator appear in the range from 160 ° C to + 120 ° C.

The range of temperatures available in the environment reaches thousands of degrees (hot magma of volcanoes and the lowest temperatures of Antarctica). The limits within which life known to us can exist are quite narrow and are equal to approximately 300 ° C, from -200 ° C (freezing in liquefied gases) to + 100 ° C (the boiling point of water). In fact, most species and most of their activity are confined to an even narrower range of temperatures. The general temperature range of active life on Earth is limited to the following temperature values ​​(Table 1.2.3):

Table 1.2.3 Temperature range of life on Earth

Plants adapt to different temperatures and even extreme ones. Those that tolerate high temperatures are called heat-stimulating plants. They are able to tolerate overheating up to 55-65° C (some cacti). Species growing in conditions of high temperatures tolerate them more easily due to a significant shortening of the size of the leaves, the development of a tomentose (hairy) or, conversely, waxy coating, etc. Plants can withstand prolonged exposure to low temperatures (from 0 to -10°C) without harming their development C), are called cold-resistant.

Although temperature is an important environmental factor affecting living organisms, its effect is highly dependent on its combination with other abiotic factors.

Humidity.

Humidity is an important abiotic factor, which is determined by the presence of water or water vapor in the atmosphere or lithosphere. Water itself is necessary inorganic compound for the life of living organisms.

Water in the atmosphere is always present in the form water couples. The actual mass of water per unit volume of air is called absolute humidity, and the percentage of vapor relative to the maximum amount that air can contain is relative humidity. Temperature is the main factor affecting the ability of air to hold water vapor. For example, at a temperature of +27°C, air can contain twice as much moisture as at a temperature of +16°C. This means that the absolute humidity at 27°C is 2 times higher than at 16°C, while the relative humidity in both cases will be 100%.

Water as an ecological factor is extremely necessary for living organisms, because without it metabolism and many other processes associated with it cannot take place. Metabolic processes of organisms take place in the presence of water (in aqueous solutions). All living organisms are open systems, so they constantly experience water loss and always have a need to replenish its reserves. For normal existence, plants and animals must maintain a certain balance between the flow of water into the body and its loss. Large loss of water from the body (dehydration) lead to a decrease in his vital activity, and subsequently to death. Plants satisfy their water needs through precipitation and air humidity, and animals also through food. The resistance of organisms to the presence or absence of moisture in the environment varies and depends on the adaptability of the species. In this regard, all terrestrial organisms are divided into three groups: hygrophilic(or moisture-loving), mesophilic(or moderately moisture-loving) and xerophilic(or dry-loving). Regarding plants and animals separately, this section will look like this:

1) hygrophilic organisms:

- hygrophytes(plants);

- hygrophiles(animal);

2) mesophilic organisms:

- mesophytes(plants);

- mesophiles(animal);

3) xerophilic organisms:

- xerophytes(plants);

- xerophiles, or hygrophobias(animals).

Need most moisture hygrophilic organisms. Among plants, these will be those that live on excessively moist soils with high air humidity (hygrophytes). In the conditions of the middle zone, they are among the herbaceous plants that grow in shaded forests (oxalis, ferns, violets, gap-grass, etc.) and in open places (marigold, sundew, etc.).

Hygrophilic animals (hygrophiles) include those ecologically associated with the aquatic environment or with waterlogged areas. They need a constant presence of large amounts of moisture in the environment. These are animals of tropical rainforests, swamps, and wet meadows.

Mesophilic organisms require moderate amounts of moisture and are usually associated with moderately warm conditions and good mineral nutrition. These can be forest plants and plants of open areas. Among them there are trees (linden, birch), shrubs (hazel, buckthorn) and even more herbs (clover, timothy, fescue, lily of the valley, hoofed grass, etc.). In general, mesophytes are a broad ecological group of plants. To mesophilic animals (mesophiles) belongs to the majority of organisms that live in temperate and subarctic conditions or in certain mountainous regions of land.

Xerophilic organisms - this is a fairly diverse ecological group of plants and animals that have adapted to arid living conditions through the following means: limiting evaporation, increasing water production and creating water reserves for a long period lack of water supply.

Plants that live in dry conditions cope with them in different ways. Some do not have the structural arrangements to cope with the lack of moisture. their existence is possible in arid conditions only due to the fact that at a critical moment they are in a state of rest in the form of seeds (ephemeri) or bulbs, rhizomes, tubers (ephemeroids), very easily and quickly switch to active life and completely disappear in a short period of time annual development cycle. Ephemery mainly distributed in deserts, semi-deserts and steppes (stonefly, spring ragwort, turnip, etc.). Ephemeroids(from Greek ephemeral And to look like)- these are perennial herbaceous, mainly spring, plants (sedges, cereals, tulip, etc.).

Very unique categories of plants that have adapted to tolerate drought conditions are succulents And sclerophytes. Succulents (from Greek. juicy) are able to accumulate large amounts of water and gradually waste it. For example, some cacti of North American deserts can contain from 1000 to 3000 liters of water. Water accumulates in the leaves (aloe, sedum, agave, young) or stems (cacti and cactus-like milkweeds).

Animals obtain water in three main ways: directly by drinking or absorbing through the integument, with food, and as a result of metabolism.

Many species of animals drink water and in fairly large quantities. For example, Chinese oak silkworm caterpillars can drink up to 500 ml of water. Certain species of animals and birds require regular consumption of water. Therefore, they choose certain springs and regularly visit them as watering places. Desert bird species fly daily to oases, drink water there and bring water to their chicks.

Some animal species that do not consume water by direct drinking can consume it by absorbing it through the entire surface of the skin. Insects and larvae that live in soil moistened with tree dust have their integuments permeable to water. The Australian moloch lizard absorbs moisture from precipitation through its skin, which is extremely hygroscopic. Many animals get moisture from succulent food. Such succulent food can be grass, juicy fruits, berries, bulbs and plant tubers. The steppe tortoise, which lives in the Central Asian steppes, consumes water only from succulent food. In these regions, in areas where vegetables are planted or in melon fields, turtles cause great damage by feeding on melons, watermelons, and cucumbers. Some predatory animals also obtain water by eating their prey. This is typical, for example, of the African fennec fox.

Species that feed exclusively on dry food and do not have the opportunity to consume water obtain it through metabolism, that is, chemically during the digestion of food. Metabolic water can be formed in the body due to the oxidation of fats and starch. This important way obtaining water especially for animals that inhabit hot deserts. Thus, the red-tailed gerbil sometimes feeds only on dry seeds. There are known experiments where, in captivity, a North American deer mouse lived for about three years, eating only dry barley grains.

Food factors.

The surface of the Earth's lithosphere constitutes a separate living environment, which is characterized by its own set of environmental factors. This group of factors is called edaphic(from Greek edaphos- soil). Soils have their own structure, composition and properties.

Soils are characterized by a certain moisture content, mechanical composition, content of organic, inorganic and organomineral compounds, and a certain acidity. Many properties of the soil itself and the distribution of living organisms in it depend on the indicators.

For example, certain species of plants and animals love soils with a certain acidity, namely: sphagnum mosses, wild currants, and alder grow on acidic soils, and green forest mosses grow on neutral ones.

Beetle larvae, terrestrial mollusks and many other organisms also react to a certain acidity of the soil.

The chemical composition of the soil is very important for all living organisms. For plants, the most important are not only those chemical elements that they use in large quantities (nitrogen, phosphorus, potassium and calcium), but also those that are rare (microelements). Some of the plants selectively accumulate certain rare elements. Cruciferous and umbelliferous plants, for example, accumulate sulfur in their bodies 5-10 times more than other plants.

Excessive content of some chemical elements in the soil can negatively (pathologically) affect animals. For example, in one of the valleys of Tuva (Russia) it was noticed that sheep were suffering from some kind of illness specific disease, which manifested itself in hair loss, hoof deformation, etc. Later it turned out that in this valley there was an increased content of selenium in the soil, water and some plants. When this element entered the body of sheep in excess, it caused chronic selenium toxicosis.

The soil has its own thermal regime. Together with moisture, it affects soil formation and various processes occurring in the soil (physicochemical, chemical, biochemical and biological).

Due to their low thermal conductivity, soils are able to smooth out temperature fluctuations with depth. At a depth of just over 1 m, daily temperature fluctuations are almost imperceptible. For example, in the Karakum Desert, which is characterized by a sharply continental climate, in the summer, when the soil surface temperature reaches +59°C, in the burrows of gerbil rodents at a distance of 70 cm from the entrance the temperature was 31°C lower and amounted to +28°C. In winter, during a frosty night, the temperature in the gerbils’ burrows was +19°C.

Soil is a unique combination of physical and chemical properties of the surface of the lithosphere and the living organisms that inhabit it. It is impossible to imagine soil without living organisms. No wonder the famous geochemist V.I. Vernadsky called soils bioinert body.

Orographic factors (relief).

Relief does not relate to such directly acting environmental factors as water, light, heat, soil. However, the nature of the relief in the life of many organisms has an indirect effect.

c Depending on the size of the forms, the relief of several orders is quite conventionally distinguished: macrorelief (mountains, lowlands, intermountain depressions), mesorelief (hills, ravines, ridges, etc.) and microrelief (small depressions, unevenness, etc.). Each of them plays a certain role in the formation of a complex of environmental factors for organisms. In particular, relief affects the redistribution of factors such as moisture and heat. Thus, even minor drops of several tens of centimeters create conditions of high humidity. Water flows from elevated areas to lower ones, where favorable conditions are created for moisture-loving organisms. The northern and southern slopes have different lighting and thermal conditions. In mountainous conditions, significant altitude amplitudes are created in relatively small areas, which leads to the formation of various climatic complexes. In particular, their typical features are low temperatures, strong winds, changes in humidification, gas composition of the air, etc.

For example, with a rise above sea level, the air temperature decreases by 6 ° C for every 1000 m. Although this is a characteristic of the troposphere, due to the relief (hills, mountains, mountain plateaus, etc.), terrestrial organisms may find themselves in conditions not similar to those in neighboring regions. For example, the Kilimanjaro volcanic mountain range in Africa is surrounded by savannas at the foot, and higher up the slopes there are plantations of coffee, bananas, forests and alpine meadows. The peaks of Kilimanjaro are covered with eternal snow and glaciers. If the air temperature at sea level is +30° C, then negative temperatures will appear already at an altitude of 5000 m. In temperate zones, a decrease in temperature for every 6° C corresponds to a movement of 800 km towards high latitudes.

Pressure.

Pressure manifests itself in both air and water environments. In atmospheric air, pressure changes seasonally, depending on weather conditions and altitude. Of particular interest are the adaptations of organisms that live in conditions of low pressure and rarefied air in the highlands.

The pressure in the aquatic environment changes depending on the depth: it increases by approximately 1 atm for every 10 m. For many organisms, there are limits to the change in pressure (depth) to which they have adapted. For example, abyssal fish (fish from the depths of the world) are able to withstand great pressure, but they never rise to the surface of the sea, because for them this is fatal. Conversely, not all marine organisms are capable of diving to great depths. The sperm whale, for example, can dive to a depth of up to 1 km, and seabirds - up to 15-20 m, where they get their food.

Living organisms on land and in the aquatic environment clearly respond to changes in pressure. At one time it was noted that fish can perceive even minor changes in pressure. their behavior changes when they change atmospheric pressure(eg before a thunderstorm). In Japan, some fish are specially kept in aquariums and changes in their behavior are used to judge possible changes in the weather.

Terrestrial animals, perceiving minor changes in pressure, can predict changes in weather conditions through their behavior.

Uneven pressure, which is the result of uneven heating by the Sun and heat distribution both in water and in atmospheric air, creates conditions for mixing water and air masses, i.e. formation of currents. Under certain conditions, flow is a powerful environmental factor.

Hydrological factors.

Water, as a component of the atmosphere and lithosphere (including soils), plays an important role in the life of organisms as one of the environmental factors called humidity. At the same time, water in a liquid state can be a factor that forms its own environment - aqueous. Due to its properties that distinguish water from all others chemical compounds, it in a liquid and free state creates a complex of conditions in the aquatic environment, the so-called hydrological factors.

Such characteristics of water as thermal conductivity, fluidity, transparency, salinity, manifest themselves differently in reservoirs and are environmental factors, which in this case are called hydrological. For example, aquatic organisms have adapted differently to varying degrees of water salinity. There are freshwater and marine organisms. Freshwater organisms do not amaze with their species diversity. First, life on Earth originated in sea ​​waters, and secondly, fresh water bodies occupy a tiny part of the earth's surface.

Marine organisms are more diverse and numerically more numerous. Some of them have adapted to low salinity and live in desalinated areas of the sea and other brackish water bodies. In many species of such reservoirs, a decrease in body size is observed. For example, the valves of mollusks, the edible mussel (Mytilus edulis) and the Lamarck's mussel (Cerastoderma lamarcki), which live in the bays of the Baltic Sea at a salinity of 2-6%o, are 2-4 times smaller than the individuals that live in the same sea, only at a salinity of 15% o. The crab Carcinus moenas in the Baltic Sea is small in size, whereas in desalinated lagoons and estuaries it is much larger. Sea urchins in lagoons they grow smaller than in the sea. The brine shrimp (Artemia salina) at a salinity of 122%o has dimensions of up to 10 mm, but at 20%o it grows to 24-32 mm. Salinity can also affect life expectancy. The same Lamarck's heartfish lives up to 9 years in the waters of the North Atlantic, and 5 in the less salty waters of the Sea of ​​Azov.

The temperature of water bodies is a more constant indicator than the temperature of land. This is due to the physical properties of water (heat capacity, thermal conductivity). The amplitude of annual temperature fluctuations in the upper layers of the ocean does not exceed 10-15° C, and in continental reservoirs - 30-35° C. What can we say about the deep layers of water, which are characterized by a constant thermal regime.

Biotic factors.

Organisms that live on our planet require not only abiotic conditions for their life, they interact with each other and are often very dependent on each other. The set of factors in the organic world that influence organisms directly or indirectly are called biotic factors.

Biotic factors are very diverse, but despite this, they also have their own classification. According to simplest classification biotic factors are divided into three groups, which are caused by: plants, animals and microorganisms.

Clements and Shelford (1939) proposed their classification, which takes into account the most typical forms of interaction between two organisms - co-actions. All coalitions are divided into two large groups, depending on whether organisms of the same species or two different ones interact. Types of interactions between organisms belonging to the same species are homotypic reactions. Heterotypic reactions call the forms of interaction between two organisms of different species.

Homotypic reactions.

Among the interactions of organisms of the same species, the following coactions (interactions) can be distinguished: group effect, mass effect And intraspecific competition.

Group effect.

Many living organisms that can live alone form groups. Often in nature you can observe how some species grow in groups plants. This gives them the opportunity to accelerate their growth. Animals also form groups. Under such conditions they survive better. When living together, it is easier for animals to defend themselves, obtain food, protect their offspring, and survive adverse environmental factors. Thus, the group effect has a positive impact for all group members.

The groups into which animals are united can vary in size. For example, cormorants, which form huge colonies on the coasts of Peru, can exist only if there are at least 10 thousand birds in the colony, and there are three nests per 1 square meter of territory. It is known that for the survival of African elephants, a herd must consist of at least 25 individuals, and a herd of reindeer - from 300-400 animals. A pack of wolves can number up to a dozen individuals.

Simple aggregations (temporary or permanent) can develop into complex groups consisting of specialized individuals that perform their inherent function in that group (families of bees, ants or termites).

Mass effect.

A mass effect is a phenomenon that occurs when a living space is overpopulated. Naturally, when combining into groups, especially large ones, some overpopulation also occurs, but there is a big difference between group and mass effects. The first gives advantages to each member of the association, while the other, on the contrary, suppresses the life activity of everyone, that is, it has negative consequences. For example, the mass effect occurs when vertebrate animals gather together. If a large number of experimental rats are kept in one cage, then their behavior will manifest acts of aggressiveness. When animals are kept in such conditions for a long time, the embryos of pregnant females dissolve, aggressiveness increases so much that the rats gnaw off each other's tails, ears, and limbs.

The mass effect of highly organized organisms leads to a stressful state. In humans, this can cause mental disorders and nervous breakdowns.

Intraspecific competition.

There is always a kind of competition between individuals of the same species to obtain the best living conditions. The greater the population density of a particular group of organisms, the more intense the competition. Such competition between organisms of the same species for certain conditions of existence is called intraspecific competition.

Mass effect and intraspecific competition are not identical concepts. If the first phenomenon occurs for a relatively short time and subsequently ends with a rarefaction of the group (mortality, cannibalism, decreased fertility, etc.), then intraspecific competition exists constantly and ultimately leads to a wider adaptation of the species to environmental conditions. The species becomes more ecologically adapted. As a result of intraspecific competition, the species itself is preserved and does not destroy itself as a result of such struggle.

Intraspecific competition can manifest itself in anything that organisms of the same species can claim. In plants that grow densely, competition may occur for light, mineral nutrition, etc. For example, an oak tree, when it grows separately, has a spherical crown; it is quite spreading, since the lower side branches receive a sufficient amount of light. In oak plantings in the forest, the lower branches are shaded by the upper ones. Branches that do not receive enough light die. As the oak grows in height, the lower branches quickly fall off, and the tree takes on a forest shape - a long cylindrical trunk and a crown of branches at the top of the tree.

In animals, competition arises for a certain territory, food, nesting sites, etc. It is easier for active animals to avoid tough competition, but it still affects them. As a rule, those that avoid competition often find themselves in unfavorable conditions; they are also forced, like plants (or attached species of animals), to adapt to the conditions with which they have to be content.

Heterotypic reactions.

Table 1.2.4. Forms of interspecific interactions

	Species occupy		Species occupy
Form of interaction (coactions)	one territory (live together)		different territories (live separately)
	View A	View B	View A	View B
Neutralism
Comensalism (type A - commensal)
Protocooperation
Mutualism
Amensalism (type A - amensal, type B - inhibitor)
Predation (species A - predator, species B - prey)
Competition

0 - interaction between species does not produce gains and does not cause damage to either side;

Interactions between species produce positive consequences; --interaction between species produces negative consequences.

Neutralism.

The most common form of interaction occurs when organisms of different species, occupying the same territory, do not affect each other in any way. The forest is home to a large number of species and many of them maintain neutral relationships. For example, a squirrel and a hedgehog inhabit the same forest, but they have a neutral relationship, like many other organisms. However, these organisms are part of the same ecosystem. They are elements of one whole, and therefore, upon detailed study, one can still find not direct, but indirect, rather subtle and at first glance, invisible connections.

Eat. Doom, in his “Popular Ecology,” gives a humorous but very apt example of such connections. He writes that in England, old single women support the power of the king's guards. And the connection between guardsmen and women is quite simple. Single women, as a rule, breed cats, and cats hunt mice. The more cats, the fewer mice in the fields. Mice are the enemies of bumblebees because they destroy their holes where they live. The fewer mice, the more bumblebees. Bumblebees, as you know, are not the only pollinators of clover. More bumblebees in the fields means a larger clover harvest. Horses are grazed on clover, and the guards like to eat horse meat. Behind this example in nature you can find many hidden connections between different organisms. Although in nature, as can be seen from the example, cats have a neutral relationship with horses or dzhmels, they are indirectly related to them.

Comensalism.

Many types of organisms enter into relationships that benefit only one party, while the other does not suffer from this and nothing is useful. This form of interaction between organisms is called commensalism. Comensalism often manifests itself as the coexistence of different organisms. Thus, insects often live in mammal burrows or bird nests.

You can often observe such a joint settlement when sparrows build nests in the nests of large birds of prey or storks. For birds of prey, the proximity of sparrows does not interfere, but for the sparrows themselves it is reliable protection of their nests.

In nature, there is even a species called the commensal crab. This small, graceful crab willingly settles in the mantle cavity of oysters. By doing this, he does not disturb the mollusk, but he himself receives shelter, fresh portions of water and nutrient particles that reach him with the water.

Protocooperation.

The next step in the joint positive coaction of two organisms of different species is proto-cooperation, in which both species benefit from interaction. Naturally, these species can exist separately without any losses. This form of interaction is also called primary cooperation, or cooperation.

In the sea, this mutually beneficial, but not obligatory, form of interaction arises when crabs and gutters come together. Anemones, for example, often settle on the dorsal side of crabs, camouflaging and protecting them with their stinging tentacles. In turn, the sea anemones receive pieces of food from the crabs that are left over from their meal, and use the crabs as a means of transport. Both crabs and sea anemones are able to exist freely and independently in a reservoir, but when they are nearby, the crab even uses its claw to transplant the sea anemone onto itself.

Joint nesting of birds of different species in the same colony (herons and cormorants, waders and terns of different species, etc.) is also an example of cooperation in which both parties benefit, for example, in protection from predators.

Mutualism.

Mutualism (or obligate symbiosis) is the next stage of mutually beneficial adaptation of different species to each other. It differs from protocooperation in its dependence. If in protocooperation the organisms that enter into communication can exist separately and independently of each other, then in mutualism the existence of these organisms separately is impossible.

This type of coaction often occurs in quite different organisms, systematically distant, with different needs. An example of this is the relationship between nitrogen-fixing bacteria (vesicle bacteria) and leguminous plants. Substances secreted by the root system of legumes stimulate the growth of vesicular bacteria, and waste products of bacteria lead to deformation of root hairs, which begins the formation of vesicles. Bacteria have the ability to assimilate atmospheric nitrogen, which is a deficiency in the soil, but an essential macronutrient for plants, which in this case gives great benefit legume plants.

In nature, the relationship between fungi and plant roots is quite common, called mycorrhiza. The mycelium, interacting with the root tissues, forms a kind of organ that helps the plant more efficiently absorb minerals from the soil. From this interaction, fungi obtain the products of plant photosynthesis. Many types of trees cannot grow without mycorrhiza, and certain types of fungi form mycorrhiza with the roots of certain types of trees (oak and porcini mushroom, birch and boletus, etc.).

A classic example of mutualism is lichens, which combine a symbiotic relationship between fungi and algae. The functional and physiological connections between them are so close that they are considered as separate group organisms. The fungus in this system provides the algae with water and mineral salts, and the algae, in turn, provides the fungus with organic substances that it itself synthesizes.

Amensalism.

IN natural environment Not all organisms have a positive effect on each other. There are many cases when, in order to ensure their livelihoods, one species harms another. This form of co-action, in which one type of organism suppresses the growth and reproduction of an organism of another species without losing anything, is called amensalism (antibiosis). A depressed look in a couple that interacts is called amensalom, and the one who suppresses - inhibitor.

Amensalism is best studied in plants. During their life, plants release into the environment chemical substances, which are factors influencing other organisms. Regarding plants, amensalism has its own name - allelopathy. It is known that due to the release of toxic substances by its roots, Nechuyviter volokhatenki displaces other annual plants and forms continuous single-species thickets over large areas. In fields, wheatgrass and other weeds crowd out or suppress cultivated plants. Walnut and oak suppress herbaceous vegetation under their crowns.

Plants can secrete alelopathic substances not only from their roots, but also from the aboveground part of their body. Volatile alelopathic substances released into the air by plants are called phytoncides. Basically, they have a destructive effect on microorganisms. Everyone is well aware of the antimicrobial preventive effect of garlic, onions, and horseradish. Coniferous trees produce a lot of phytoncides. One hectare of common juniper plantings produces more than 30 kg of phytoncides per year. Coniferous species are often used in populated areas to create sanitary protective strips around various industries, which helps clean the air.

Phytoncides negatively affect not only microorganisms, but also animals. Various plants have long been used in everyday life to control insects. So, baglitsa and lavender are good remedy to fight moths.

Antibiosis is also known in microorganisms. It was first discovered. Babesh (1885) and rediscovered by A. Fleming (1929). Penicillin mushrooms have been shown to secrete a substance (penicillin) that inhibits the growth of bacteria. It is widely known that some lactic acid bacteria acidify their environment so that putrefactive bacteria, which require an alkaline or neutral environment, cannot exist in it. Alelopathic chemicals from microorganisms are known as antibiotics. Over 4 thousand antibiotics have already been described, but only about 60 of their varieties are widely used in medical practice.

Animals can also be protected from enemies by secreting substances that have bad smell(for example, among reptiles - vulture turtles, snakes; birds - hoopoe chicks; mammals - skunks, ferrets).

Predation.

Theft in the broad sense of the word is considered a way of obtaining food and feeding animals (sometimes plants), in which they catch, kill and eat other animals. Sometimes this term is understood as any consumption of some organisms by others, i.e. such relationships between organisms in which some use others as food. With this understanding, the hare is a predator in relation to the grass it consumes. But we will use a narrower understanding of predation, in which one organism feeds on another, which is close to the first in systematic terms (for example, insects that feed on insects; fish that feed on fish; birds that feed on reptiles, birds and mammals; mammals that that feed on birds and mammals). The extreme case of predation, in which a species feeds on organisms of its own species, is called cannibalism.

Sometimes a predator selects prey in such numbers that it does not negatively affect its population size. By doing this, the predator contributes to the better condition of the prey population, which has also already adapted to the pressure of the predator. The birth rate in prey populations is higher than that required to normally maintain its population. Figuratively speaking, the prey population takes into account what the predator should select.

Interspecific competition.

Between organisms of different species, as well as between organisms of the same species, interactions arise through which they try to obtain the same resource. Such cooperation between various types are called interspecific competition. In other words, we can say that interspecific competition is any interaction between populations of different species that adversely affects their growth and survival.

The consequences of such competition may be the displacement of one organism by another from a certain ecological system (the principle of competitive exclusion). At the same time, competition promotes the emergence of many adaptations through the process of selection, which leads to the diversity of species that exist in a particular community or region.

Competitive interaction may concern space, food or nutrients, light and many other factors. Interspecific competition, depending on what it is based on, can lead either to the establishment of equilibrium between two species, or, with more severe competition, to the replacement of a population of one species by a population of another. Also, the result of competition may be that one species displaces another to another place or forces it to switch to other resources.

3.1. Abiotic factors

Abiotic (from Greek - lifeless) factors are components and phenomena of inanimate, inorganic nature that directly or indirectly affect living organisms. In accordance with the existing classification, the following abiotic factors are distinguished: climatic, edaphic (soil), orographic or topographical, hydrographic (water environment), chemical (Table 1). Some of the most important abiotic factors are light, temperature, and humidity.

Table 1 – Classification of environmental environmental factors

Abiotic factors	Biotic	Anthropogenic
Climatic: solar radiation, light and light conditions, temperature, humidity, precipitation, wind, pressure, etc. Edaphic: mechanical and chemical composition of the soil, moisture capacity, water, air and thermal conditions of the soil, groundwater level, etc. Orographic (topographic): relief (refers to indirectly acting environmental factors, since it does not directly affect the life of organisms); exposure (location of relief elements in relation to the cardinal points and prevailing winds bringing moisture); height above sea level. Hydrographic: factors of the aquatic environment. Chemical: gas composition of the atmosphere, salt composition of water.	Phytogenic (influence of plants) Zoogenic (influence animals) biotic factors are divided into: competition, predation,	with human activity

Light. Solar radiation serves as the main source of energy for all processes occurring on Earth. In the spectrum of solar radiation, areas differing in biological action are distinguished: ultraviolet, visible and infrared. Ultraviolet rays with a wavelength of less than 0.290 microns are destructive to all living things. This radiation is delayed by the ozone layer of the atmosphere, and only a portion of ultraviolet rays (0.300–0.400 microns) reaches the Earth’s surface, which in small doses has a beneficial effect on organisms.

Visible rays have a wavelength of 0.400–0.750 microns and account for most of the solar radiation energy reaching the earth's surface. These rays are especially important for life on Earth. Green plants synthesize organic substances using the energy of this particular part of the solar spectrum. Infrared rays with a wavelength greater than 0.750 microns are not perceived by the human eye, but are perceived as heat and are an important source of internal energy. Light, therefore, has an ambiguous effect on organisms. On the one hand, it is the primary source of energy, without which life on Earth is impossible, on the other hand, it can have a negative effect on organisms.

Light mode . When passing through atmospheric air sunlight(Figure 3.1) is reflected, scattered and absorbed. Each habitat is characterized by a certain light regime. It is established by the ratio of intensity (strength), quantity and quality of light. Indicators of the light regime are very variable and depend on the geographical location, terrain, altitude, atmospheric conditions, time of year and day, type of vegetation and other factors. Intensity, or luminous strength, is measured by the number of joules per 1 cm 2 of horizontal surface per minute. This indicator is most significantly influenced by the features of the relief: on the southern slopes the light intensity is greater than on the northern ones. Direct light is the most intense, but plants use diffused light more fully. The amount of light is an indicator that is determined by the total radiation. To determine the light regime, the amount of reflected light, the so-called albedo, is also taken into account. It is expressed as a percentage of total radiation. For example, the albedo of green maple leaves is 10%, and the albedo of yellowed autumn leaves is 28%. It should be emphasized that plants reflect mainly physiologically inactive rays.

In relation to light, the following ecological groups of plants are distinguished: light-loving(light), shade-loving(shadow), shade-tolerant. Light-loving species live in the forest zone in open places and are rare. They form a sparse and low vegetation cover so as not to shade each other. Shade-loving plants do not tolerate strong light and live under the forest canopy in constant shade. These are mainly forest herbs. Shade-tolerant plants can live in good light, but can easily tolerate some shading. These include most forest plants. Due to this specific habitat, these groups of plants are characterized by certain adaptive features. In the forest, shade-tolerant plants form densely closed stands. Shade-tolerant trees and shrubs can grow under their canopy, and even more shade-tolerant and shade-loving shrubs and herbs can grow below them.

Figure 3.1 – Balance of solar radiation on the surface

Earth in the daytime (according to N. I. Nikolaikin, 2004)

Light is a condition for the orientation of animals. Animals are divided into diurnal, nocturnal and crepuscular species. The light regime also affects the geographical distribution of animals. Thus, certain species of birds and mammals settle in high latitudes with long polar days in the summer, and in the fall, when the days shorten, they migrate or migrate south.

One of the most important environmental factors, an irreplaceable and universal factor, is temperature . It determines the level of activity of organisms, affects metabolic processes, reproduction, development, and other aspects of their life. The distribution of organisms depends on it. It should be noted that depending on body temperature, poikilothermic and homeothermic organisms are distinguished. Poikilothermic organisms (from the Greek - various and heat) are cold-blooded animals with an unstable internal body temperature, varying depending on the ambient temperature. These include all invertebrates, and vertebrates include fish, amphibians and reptiles. Their body temperature, as a rule, is 1–2° C higher than the external temperature or equal to it. When the environmental temperature increases or decreases beyond optimal values, these organisms fall into torpor or die. The absence of perfect thermoregulatory mechanisms in poikilothermic animals is due to the relatively weak development nervous system and a low metabolic rate compared to homeothermic organisms. Homeothermic organisms are warm-blooded animals whose temperature is more or less constant and, as a rule, does not depend on the ambient temperature. These include mammals and birds, in which the constancy of temperature is associated with a higher level of metabolism compared to poikilothermic organisms. In addition, they have a thermal insulating layer (feather, fur, fat layer). Their temperature is relatively high: in mammals it is 36–37° C, and in birds at rest – up to 40–41° C.

Thermal mode . As noted, temperature is an important environmental factor that affects the existence, development and distribution of organisms. At the same time, not only the absolute amount of heat matters, but also its distribution over time, that is, the thermal regime. The thermal regime of plants consists of temperature conditions, which are characterized by one or another duration and change in a certain sequence in combination with other factors. In animals, it also, in combination with a number of other factors, determines their daily and seasonal activity. The thermal regime is relatively constant throughout the year only in tropical zones. To the north and south, daily and seasonal temperature variations increase with distance from the equator. Plants and animals, adapting to them, show different needs for heat in different periods. For example, seed germination occurs at lower temperatures than their subsequent growth; the flowering period requires more heat than the period of fruit ripening. In different organisms, biological processes at optimal temperatures obey van't Hoff's rule, according to which the rate of chemical reactions increases 2–3 times with every 10° C increase in temperature. For plants, like animals, the total amount of heat that they can receive from the environment is important. Temperatures that lie above the lower threshold of development and do not go beyond the upper threshold are called effective temperatures. The amount of heat required for development is determined by the sum of effective temperatures, or sum of heat. The effective temperature can be easily determined by knowing the lower development threshold and the observed temperature. For example, if the lower threshold for the development of an organism is 10 ° C, and the temperature is this moment 25° C, then effective temperature will be equal to 15° C (25–10° C). The sum of effective temperatures for each species of plants and poikilothermic animals is a relatively constant value.

Plants have various anatomical, morphological and physiological adaptations that smooth out the harmful effects of high and low temperatures: the intensity of transpiration (as the temperature decreases, the evaporation of water through the stomata occurs less intensely and, as a result, heat transfer decreases and, vice versa); accumulation of salts in cells that change the temperature of plasma coagulation, the property of chlorophyll to prevent the penetration of the hottest sunlight. The accumulation of sugar and other substances in the cells of frost-resistant plants that increase the concentration of cell sap makes the plant more resilient and is of great importance for their thermoregulation. The influence of thermal conditions can also be seen in animals. As we move away from the poles to the equator, the sizes of systematically similar animals with unstable body temperatures increase, and with constant ones they decrease. This provision reflects Bergman's rule. One of the reasons for this phenomenon is an increase in temperature in the tropics and subtropics. In small forms, the relative surface area of ​​the body increases and heat transfer increases, which has a negative effect in temperate and high latitudes, primarily on animals with unstable body temperature. The body temperature of organisms has a significant shape-forming effect. Under the influence of the thermal factor they form such morphological characteristics as a reflective surface; fat deposits, down, feathers and fur in birds and mammals. In the Arctic, high in the mountains, most insects are dark in color, which enhances the absorption of sunlight. 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, since they release the greatest amount of heat into the environment (Figure 3.2). In mammals, at low temperatures, the size of the tail, limbs, and ears is relatively reduced, and hair develops better. Thus, the size of the ears of the arctic fox (an inhabitant of the tundra) is small; they increase in the fox, typical of temperate latitudes, and become quite large in the fennec fox (an inhabitant of the deserts of Africa). In general, in relation to temperature, anatomical and morphological changes in both plants and animals are primarily aimed at regulating the level of heat loss. In the course of long historical development, adapting to periodic changes in temperature conditions, organisms, including those living in forests, have developed different needs for heat at different periods of life.

Figure 3.2 – Differences in ear length among three species of foxes,

living in different geographical areas

(according to A. S. Stepanovskikh, 2003)

Thermal conditions also affect the distribution of plants and animals around the globe. They are historically adapted to certain thermal conditions. Therefore, the temperature factor is directly related to the distribution of plants and animals. To one degree or another, it determines the population of different natural zones by organisms. In 1918, A. Holkins formulated bioclimatic law. He established that there is a natural, rather close connection between the development of phenological phenomena and latitude, longitude and altitude. The essence of this law is that as you move north, east and into the mountains, the time of onset of periodic phenomena (such as flowering, fruiting, shedding of leaves) in the life activity of organisms is delayed by 4 days for each degree of latitude, 5 degrees of longitude and approximately 100 m height. There is a connection between the boundaries of distribution of plants and animals with the number of days per year with a certain average temperature. For example, isolines with average daily temperatures above 7° C for more than 225 days a year coincide with the distribution limit of beech in Europe. However, it is not the average daily temperatures that are of great importance, but their fluctuations in combination with other environmental factors, ecoclimatic and microclimatic conditions.

Heat distribution is related to various factors: the presence of bodies of water (near them the amplitude of temperature fluctuations is smaller); features of the relief, topography of the area. Thus, on the northern and southern slopes of hills and ravines, quite large temperature differences are observed. The terrain, determining the exposure of the slopes, affects the degree of their heating. This leads to the formation of slightly different plant associations and animal groups on the southern and northern slopes. In the south of the tundra, forest vegetation is found on slopes in river valleys, in floodplains or on hills in the middle of the plain, since these are the places that warm up the most.

As the air temperature changes, the soil temperature also changes. Different soils warm up differently depending on color, structure, moisture, and exposure. Heating, as well as cooling, of the soil surface is prevented by vegetation cover. During the day, the air temperature under the forest canopy is always lower than in open spaces, and at night it is warmer in the forest than in the field. This affects the species composition of animals: even in the same area they are often different.

Important environmental factors include humidity (water) . Water is necessary for any protoplasm. All physiological processes occur with the participation of water. Living organisms use aqueous solutions (such as blood and digestive juices) to maintain their physiological processes. It limits the growth and development of plants more often than other environmental factors. From an ecological point of view, water serves as a limiting factor both in terrestrial habitats and in aquatic ones, where its quantity is subject to strong fluctuations. It should be noted that terrestrial organisms constantly lose water and need regular replenishment. In the process of evolution, they have developed numerous adaptations that regulate water metabolism. Plant water needs in different periods development varies, especially among different species. It varies depending on climate and soil type. For each phase of growth and stage of development of any type of plant, a critical period is distinguished when the lack of water has a particularly negative effect on its life. Almost everywhere, except in the humid tropics, terrestrial plants experience drought, a temporary lack of water. Moisture deficiency reduces plant growth and causes short stature and infertility due to underdevelopment of generative organs. Atmospheric drought is strongly manifested at high summer temperatures, soil drought - with a decrease in soil moisture. At the same time, there are plants that are sensitive to one or another deficiency. Beech can live in relatively dry soil, but is very sensitive to air humidity. Forest plants require a high content of water vapor in the air. Air humidity determines the frequency of active life of organisms, the seasonal dynamics of life cycles, and affects the duration of their development, fertility, and mortality.

As you can see, each of these factors plays a major role in the life of organisms. But the combined action of light, temperature, and humidity is also important for them. Atmospheric gases (oxygen, carbon dioxide, hydrogen), nutrients (phosphorus, nitrogen), calcium, sulfur, magnesium, copper, cobalt, iron, zinc, boron, silicon; currents and pressure, salinity, and other environmental abiotic factors influence organisms. Summarized data on the main abiotic environmental factors, rhythm and scope of their action are presented in Table 2.

Previous

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.