Abiotic factors of the terrestrial environment. §2Abiotic factors

Constantly evolving, humanity does not particularly think about how abiotic factors directly or indirectly affect a person. What are abiotic conditions and why is their seemingly imperceptible influence so important to consider? These are certain physical phenomena that are not related to wildlife, which in one way or another affect the life or environment of a person. Roughly speaking, light, the degree of humidity, the Earth's magnetic field, temperature, the air we breathe - all these parameters are called abiotic. Under this definition does not fall in any way the influence of living organisms, including bacteria, microorganisms and even protozoa.

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Examples and types

We have already found out that this is a set of phenomena of inanimate nature, which can be climatic, water or soil. The classification of abiotic factors is conditionally divided into three types:

1. Chemical,
2. physical,
3. Mechanical.

The chemical influence is exerted by the organic and mineral composition of the soil, atmospheric air, groundwater and other waters. Physical factors include natural light, pressure, temperature and humidity. environment. Accordingly, cyclones, solar activity, soil, air and water movement in nature are considered mechanical factors. The combination of all these parameters has a tremendous impact on the reproduction, distribution and quality of life of all life on our planet. And if a modern person thinks that all these phenomena that literally control the life of his ancient ancestors have now been tamed with the help of advanced technologies, then, unfortunately, this is not at all the case.

One should not lose sight of biotic factors and processes that are inevitably tied to the abiotic influence on all living things. Biotic are the forms of influence of living organisms on each other, almost any of them is caused by abiotic environmental factors and their influence on living organisms.

What influence can the factors of inanimate nature have?

To begin with, it is necessary to indicate what falls under the definition of abiotic environmental factors? Which of the parameters can be attributed here? The abiotic environmental factors include: light, temperature, humidity, and the state of the atmosphere. Let's consider which factor influences how in more detail.

Light

Light is one of the environmental factors that literally every object in geobotany uses. Sunlight is the most important source of thermal energy, responsible in nature for the processes of development, growth, photosynthesis and many, many others.

Light, as an abiotic factor, has a number of specific characteristics: spectral composition, intensity, periodicity. These abiotic conditions are most important for plants whose main life is the process of photosynthesis. Without a high-quality spectrum and good lighting intensity, the plant world will not be able to actively reproduce and grow fully. The duration of light exposure is also important, so, with a short daylight, plant growth is significantly reduced, and reproduction functions are inhibited. Not in vain, for good growth and harvest, in greenhouse (artificial) conditions, they necessarily create the longest possible light period, which is so necessary for plant life. In such cases, natural biological rhythms are drastically and deliberately violated. Lighting is the most important natural factor for our planet.

Temperature

Temperature is also one of the most powerful abiotic factors. Without the right temperature regime, life on Earth is really impossible - and this is not an exaggeration. Moreover, if a person can deliberately maintain the light balance at a certain level, and it is quite simple to do this, then the situation with temperature is much more difficult.

Of course, over the millions of years of existence on the planet, both plants and animals have adapted to the temperature that is uncomfortable for them. The processes of thermoregulation are different here. For example, in plants, two methods are distinguished: physiological, namely, an increase in the concentration of cell sap, due to the intensive accumulation of sugar in cells. Such a process provides the necessary level of frost resistance of plants, at which they can not die even at very low temperatures. The second way is physical, it consists in the special structure of foliage or its reduction, as well as growth methods - squat or creeping along the ground - to avoid freezing in open space.

Among animals, eurytherms are distinguished - those that freely exist with a significant temperature fluctuation, and stenotherms, for whose life a certain temperature range of not too large size is important. Eurythermal organisms exist when the ambient temperature fluctuates within 40-50 degrees, usually these are conditions close to the continental climate. High temperatures in summer, frost in winter.

A striking example of a eurythermic animal can be considered a hare. In the warm season, he feels comfortable in the heat, and in frosts, turning into a hare, he perfectly adapts to the temperature abiotic factors of the environment and their effect on living organisms.

There are also many representatives of the fauna - these are animals, and insects, and mammals that have a different type of thermoregulation - with the help of a state of torpor. In this case, the metabolism slows down, but the body temperature can be kept at the same level. Example: for a brown bear, the abiotic factor is winter air temperature, and its method of adapting to frost is hibernation.

Air

The abiotic environmental factors also include the air environment. In the process of evolution, living organisms had to master the air habitat after leaving the water on land. Some of them, especially this was reflected in insects and birds, in the process of development of land-moving species, adapted to air movement, having mastered the technique of flight.

One should not exclude the process of ansmochory - the migration of plant species with the help of air currents - the vast majority of plants populated the territories in which they now grow in this way, by pollination, seed transfer by birds, insects, and the like.

If you ask yourself what abiotic factors affect the flora and fauna, then the atmosphere, in terms of its degree of influence, will clearly not be in last place - its role in the process of evolution, development and population size cannot be exaggerated.

However, it is not the air itself that is important, as a parameter that affects nature and organisms, but also its quality, namely, chemical composition. What factors are important in this aspect? There are two of them: oxygen and carbon dioxide.

Importance of oxygen

Without oxygen, only anaerobic bacteria can exist; other living organisms need it to an extreme degree. The oxygen component of the air environment refers to those types of products that are only consumed, but only green plants are capable of producing oxygen, by photosynthesis.

Oxygen, entering the body of a mammal, is bound into a chemical compound by hemoglobin in the blood and, in this form, is transferred with the blood to all cells and organs. This process ensures the normal functioning of any living organism. The influence of the air environment on the process of life support is great and continuous throughout life.

Importance of carbon dioxide

Carbon dioxide is a product exhaled by mammals and some plants, it is also formed in the process of combustion and vital activity of soil microorganisms. However, all these natural processes emit such an insignificant amount of carbon dioxide that they cannot even be compared with a real ecosystem disaster that is directly and indirectly related to all natural processes - industrial emissions and waste products. technological processes. And, if some hundred years ago, a similar problem would be mainly observed in a large industrial city, such as, for example, Chelyabinsk, then today, it is spread almost throughout the entire planet. In our time, carbon dioxide, produced everywhere: enterprises, vehicles, various devices, stubbornly expands the group of its impact, including the atmosphere.

Humidity

Humidity, as an abiotic factor, is the water content of whatever it is: plant, air, soil, or living organism. Of the environmental factors, it is humidity that is the first condition necessary for the origin and development of life on Earth.

All living things on the planet need water. The mere fact is that any living cell eighty percent consists of water, speaks for itself. But for many living beings ideal conditions Habitats of the natural environment are precisely bodies of water or humid climate.

Of course, there are also types of areas where the amount of water is minimal or it is present with any periodicity, these are desert, high mountain relief, and the like. This has an obvious effect on nature: the absence or minimum of vegetation, drying up soil, no fruit-bearing plants, only those types of flora and fauna that can adapt to such conditions survive. Fitness, to whatever extent it is expressed, is not lifelong and, in the case when the characteristics of abiotic factors change for some reason, it can also change or disappear altogether.

In terms of the degree of influence on nature, humidity is important to take into account not only as a single parameter, but also in combination with each of the listed factors, since together they form the type of climate. Each specific territory with its own abiotic environmental factors has its own characteristics, its own vegetation, species and population size.

The influence of abiotic factors on humans

Man, as a component of an ecosystem, also applies to objects that are influenced by abiotic factors of inanimate nature. The dependence of human health and behavior on solar activity, the lunar cycle, cyclones and similar influences was noted several centuries ago, thanks to the observation of our ancestors. And in modern society the presence of a group of people is invariably recorded, the changes in mood and well-being of which are indirectly affected by abiotic environmental factors.

For example, studies of solar influence have shown that this star has an eleven-year cycle of periodic activity. On this basis, fluctuations in the electromagnetic field of the Earth occur, which affects the human body. Peaks of solar activity can weaken immune system, and pathogenic microorganisms, on the contrary, to make them more tenacious and adapted to extensive distribution within the community. The sad consequences of such a process are outbreaks of epidemics, the emergence of new mutations and viruses.

Another important example of abiotic influence is ultraviolet. Everyone knows that in certain doses, this type of radiation is even useful. This environmental factor has antibacterial action, slows down the development of spores that cause skin diseases. But in high doses, ultraviolet radiation negatively affects the population, causing such deadly diseases as cancer, leukemia or sarcoma.

The manifestations of the action of abiotic environmental factors on a person directly include temperature, pressure and humidity, in short - climate. An increase in temperature will lead to inhibition of physical activity and the development of problems with the cardiovascular system. Low temperatures are dangerous hypothermia, which means inflammatory processes respiratory organs, joints and extremities. It should be noted here that the humidity parameter further enhances the influence of the temperature regime.

An increase in atmospheric pressure threatens the health of owners of weak joints and fragile blood vessels. Especially dangerous, there are sharp changes in this climatic parameter - sudden hypoxia, blockage of capillaries, fainting and even coma can occur.

Of the environmental factors, one should also note the chemical aspect of the impact on humans. These include all chemical elements contained in water, atmosphere or soil. There is the concept of regional factors - the excess or, conversely, the lack of certain compounds or trace elements in the nature of each individual region. For example, from the listed factors, both a lack of fluorine is harmful - it causes damage to tooth enamel, and its excess - it accelerates the process of ossification of the ligaments, disrupts the functioning of some internal organs. Fluctuations in the content of such chemical elements like chromium, calcium, iodine, zinc, lead.

Of course, many of the abiotic conditions listed above, although they are abiotic factors of the natural environment, are in fact very much dependent on human activity - the development of mines and deposits, changes in riverbeds, the air environment, and similar examples of the intervention of progress in natural phenomena.

Detailed characteristics of abiotic factors

Why is the impact on the population of most abiotic factors so huge? This is logical: after all, to ensure life cycle of any living organism on Earth, the totality of all parameters that affect the quality of life, its duration, which determines the number of ecosystem objects, is important. Lighting, atmospheric composition, humidity, temperature, zonality of distribution of representatives of wildlife, salinity of water and air, its edaphic data are the most important abiotic factors and adaptation of organisms to them is positive or negative, but in any case, it is inevitable. It is easy to verify this: just look around!

Abiotic factors of the aquatic environment provide the origin of life, make up three-quarters of every living cell on Earth. In the forest ecosystem, biotic factors include all the same parameters: humidity, temperature, soil, light - they determine the type of forest, saturation with plants, their adaptability to a particular region.

In addition to the obvious, already listed, important abiotic factors of the natural environment should also be called salinity, soil and the Earth's electromagnetic field. The entire ecosystem has evolved for hundreds of years, the terrain has changed, the degree of adaptation of living organisms to certain living conditions, new species have appeared and entire populations have migrated. However, this natural chain has long been violated by the fruits of human activity on the planet. The work of environmental factors is fundamentally disrupted due to the fact that the impact of abiotic parameters does not occur purposefully, as factors of inanimate nature, but already as harmful effect for the development of organisms.

Unfortunately, the influence of abiotic factors on the quality and life expectancy of a person and humanity as a whole has been and remains enormous and can have both positive and negative consequences for each individual organism for all of humanity as a whole.

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 impact on the chemical and physical processes occurring in organisms, affects the metabolism.

Many morphological and behavioral characteristics of various organisms are related to 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, female courtship, spring rut, is related to the length of daylight hours.

In ecology, the term "light" refers to the entire range of solar radiation reaching the earth's surface. The energy distribution spectrum of the Sun's radiation outside 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, qualitative signs 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 - high-temperature plasma, accelerated electrons, some lasers, the Sun, stars, etc. The biological effect of ultraviolet radiation is due to chemical changes in the molecules of living cells that absorb them, mainly nucleic acid molecules (DNA and RNA) and proteins, and is expressed in division disorders , mutations and cell death.

Part of the sun's rays, having overcome a huge distance, reaches the surface of the Earth, illuminates and heats it. It is estimated that about one two billionth part of solar energy enters our planet, and of this amount, only 0.1-0.2% is used by green plants to create organic matter. Each square meter of the planet gets 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. In the forest it is different than in the meadow. Lighting in deciduous and dark coniferous spruce forests differs markedly.

Light controls the growth of plants: they grow in the direction of more 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 lasting 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 - the sun and phyton - a 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 cultivated plants in open ground, and many weeds. Of the species of this group, you can take revenge on the common plantain, Ivan-tea, reed reed grass, etc.

Sciophytes(from the Greek scia - shadow), or shade plants, cannot stand strong lighting 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 both with very large and with a small amount of light. As an example, we can name some trees - spruce, Norway maple, common hornbeam; shrubs - leshina, hawthorn; herbs - strawberries, field geraniums; many indoor plants.

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

The main source of heat, like light, is solar radiation. An organism can only survive under conditions to which its metabolism (metabolism) is adapted. If the temperature of a living cell drops below the freezing point, 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 not able to regulate their temperature and are called cold-blooded (poikilothermic). Their activity mainly depends on the heat coming from outside. The body temperature of poikilothermic organisms is related to the values ​​of the ambient temperature. Cold-bloodedness is characteristic of such groups of organisms as plants, microorganisms, invertebrates, fish, reptiles, etc.

A much 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 produced by them is a product of biochemical reactions and serves as a significant source of an increase in body temperature. This temperature is maintained at a constant level regardless of the ambient temperature. Organisms that can maintain a constant optimal body temperature regardless of the temperature of the environment are called warm-blooded (homeothermic). Due to this property, many animal species can live and breed 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 homoiothermy is heterothermy (from the Greek heteros - different). Different levels of body temperature in heterothermal organisms depend on their functional activity. During the period of activity, they have a constant body temperature, and during the period of rest or hibernation, the temperature drops significantly. Heterothermia is characteristic of ground squirrels, marmots, badgers, bats, hedgehogs, bears, hummingbirds, etc.

Moisture 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 proceed in aquatic environment.

Water does not change chemically under the influence of most of the technical compounds that it dissolves. This is very important for living organisms, since the nutrients necessary for their tissues are supplied in aqueous solutions in a relatively unaltered form. AT natural conditions water always contains a certain 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 physical and chemical environment our planet, as well as in the emergence and maintenance of an amazing phenomenon - life.

The human embryo is 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 is already 60% of its mass. The main part of water (70%) is concentrated inside the cells, and 30% is intercellular water. Human muscles consist of 75% water, liver - 70%, brain - 79%, kidneys - 83%.

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

The elephant needs the most water (based on the daily requirement) from terrestrial animals - about 90 liters. Elephants are one of the best "hydrogeologists" among animals and birds: they feel water bodies at a distance of up to 5 km! Only the bison are further away - 7-8 km. In dry times, elephants dig holes with their tusks in the beds of dry rivers, where water collects. Buffaloes, rhinoceros and other African animals willingly use elephant wells.

The spread of life on Earth is directly related to rainfall. Humidity is not the same in different parts of the world. 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 rainfall here reaches 11,455 mm. For comparison: in the tundra and deserts, less than 250 mm of precipitation falls per year.

Animals react differently to moisture. 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, transfers reproductive products and hydrobionts themselves. Due 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 whole set of physical and chemical properties of the soil that have an ecological impact on living organisms refers to edaphic factors (from the Greek edaphos - foundation, earth, soil). The main edaphic factors are the mechanical composition of the soil (the size of its particles), relative friability, structure, water permeability, aerability, and the chemical composition of the soil and substances (gases, water) circulating in it.

The nature of the granulometric composition of the soil can be of ecological importance for animals that, at a certain period of life, live in the soil or lead a burrowing lifestyle. Insect larvae, as a rule, cannot live in too stony soil; burrowing hymenoptera that lay their eggs in underground passages, many locusts that bury their 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 = -lg. Aqueous solutions can have a pH of 0 to 14. Neutral solutions have a pH of 7, an acidic environment is characterized by a pH value of less than 7, and an alkaline one is greater than 7. Acidity can serve as an indicator of the rate of the 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 - nutrition) - plants of poor, infertile soils (Scotch pine);
• mesotrophs (from the Greek. mesos - medium) - plants with a moderate need for nutrients (most forest plants of temperate latitudes);
• eutrophic(from Greek to her - good) - plants that require a large amount of nutrients in the soil (oak, hazel, gout).

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, exposure and steepness of slopes. They are combined into a group of orographic factors (from the Greek oros - mountain). Their impact can greatly affect local climate and soil development.

One of the main orographic factors is the height above sea level. With altitude, average temperatures decrease, the diurnal temperature difference increases, the amount of precipitation, wind speed and radiation intensity increase, atmospheric pressure and gas concentrations decrease. All these factors affect plants and animals, causing vertical zonality.

A typical example is vertical zoning in the mountains. Here, for every 100 m rise, the air temperature drops by an average of 0.55 °C. At the same time, humidity changes, the duration of the growing season is reduced. With an increase in the height of the habitat, the development of plants and animals changes significantly. Tropical seas can be found at the foot of the mountains, and arctic winds blow at the top. On one side of the mountains it can be sunny and warm, on the other it can be wet and cold.

Another orographic factor is slope exposure. On the northern slopes, plants form shady forms, on the southern slopes - light. The vegetation here is represented mainly by drought-resistant shrubs. The south-facing slopes receive more sunlight, so the light intensity and temperature are higher here than at the bottom of the valleys and on the slopes of the northern exposure. Associated with this are significant differences in the heating of air and soil, the rate of snow melting, and the drying of the soil.

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

hydrographic factors

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

Organisms that live in the aquatic environment are called hydrobionts.

Different organisms have adapted in their own way to the density of water and certain depths. Some species can tolerate pressure from a few to hundreds of atmospheres. Many fish, cephalopods, crustaceans, 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, keel-legged and pteropod molluscs, etc.

high specific heat and high thermal conductivity of water determine a more stable compared to land temperature regime reservoirs. 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. With depth, the amount of light rapidly decreases, therefore, 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

The action of chemical factors is manifested in the form of penetration into the environment of chemicals that were absent in it before, which is largely due to modern anthropogenic influence.

Such a chemical factor as the gas composition is extremely important for organisms living in the aquatic environment. For example, there is a lot of hydrogen sulfide in the waters of the Black Sea, which makes this pool not entirely favorable for some animals to live in it. The rivers flowing into it carry with them not only pesticides or heavy metals washed off the fields, but also nitrogen and phosphorus. And this is not only agricultural fertilizers, but also food for marine microorganisms and algae, which, due to an excess of nutrients, begin to develop rapidly (water bloom). Dying, they sink to the bottom and in the process of decay consume a significant amount of oxygen. Over the past 30-40 years, the blooming of the Black Sea has increased significantly. In the lower layer of water, oxygen is displaced by poisonous hydrogen sulfide, so there is practically no life here. The organic world of the sea is relatively poor and monotonous. Its life layer is limited by 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). According to 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 saline - from 3 to 10, salty and very salty water - from 10 to 50, brine - more 50 g/l. Thus, in fresh water bodies of land (streams, rivers, lakes), 1 kg of water contains up to 1 g of soluble salts. Sea water is a complex saline solution, the average salinity of which is 35 g/kg of water, i.e. 3.5%.

Living organisms living in the aquatic environment are adapted to a strictly defined water salinity. Freshwater forms cannot live in the seas, marine ones do not tolerate desalination. If the salinity of the water changes, the animals move in search of a favorable environment. For example, during the desalination of the surface layers of the sea after heavy rains, some types of marine crustaceans sink to a depth of up to 10 m.

Oyster larvae live in the brackish waters of small bays and estuaries (semi-enclosed coastal waters that freely communicate with the ocean or sea). The larvae grow especially fast when the salinity of the water is 1.5-1.8% (somewhere between fresh and salt water). At a higher salt content, their growth is somewhat suppressed. With a decrease in the salt content, 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 factors, or fires. At present, fires are considered as a very significant and one of the natural abiotic environmental factors. At correct use fire can become a very valuable environmental tool.

At first glance, fires are a negative factor. But in reality it is not so. Without fires, the savanna, for example, would quickly disappear and become covered with dense forest. However, this does not happen, because the tender shoots of trees die in the fire. Since trees grow slowly, few of them manage to survive fires and grow tall enough. Grass, on the other hand, grows quickly and recovers just as quickly after fires.

It should be avenged 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. Human-controlled fires produce rich, useful ash. Mixing with the soil, the ash stimulates the growth of plants, the number of which depends on the life of animals.

In addition, many inhabitants of the savannas, 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.

Both natural factors (lightning strike) and accidental and non-random human actions can contribute to the occurrence of fires. There are two types of fires. Top fires are the most difficult to contain and control. 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 supplement the action of bacteria by decomposing dead plants and speeding up the transformation 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 (the prairies of North America), fires stimulate the growth of grasses at the expense of trees. Fires play a particularly important regulatory role in the steppes and savannahs. Here, periodic fires reduce the likelihood of desert scrub invasion.

A person is often the cause of an increase in the frequency of wild fires, although a private person does not have the right to intentionally (even accidentally) cause a fire in nature. However, the use of fire by specialists is part of proper land use.

These are factors of inanimate nature that directly or indirectly affect the body - light, temperature, humidity, the chemical composition of the air, water and soil environment, etc. (i.e., the properties of the environment, the occurrence and impact of which does not directly depend on the activity of living organisms).

Light

(solar radiation) - an environmental factor characterized by the intensity and quality of the radiant energy of the Sun, which is used by photosynthetic green plants to create plant biomass. Sunlight reaching the Earth's surface is the main source of energy for maintaining the planet's heat balance, water metabolism of organisms, the creation and transformation of organic matter by the autotrophic link of the biosphere, which ultimately makes it possible to form an environment capable of satisfying the vital needs of organisms.

The biological effect of sunlight is determined by its spectral composition. [show] ,

In the spectral composition of sunlight, there are

• infrared rays (wavelength over 0.75 microns)
• visible rays (0.40-0.75 microns) and
• ultraviolet rays (less than 0.40 microns)

Different parts of the solar spectrum are unequal in biological action.

infrared, or thermal, rays carry the main amount of thermal energy. They account for about 49% of the radiant energy that is perceived by living organisms. Thermal radiation is well absorbed by water, the amount of which in organisms is quite large. This leads to heating of the whole organism, which is of particular importance for cold-blooded animals (insects, reptiles, etc.). In plants, the most important function of infrared rays is to carry out transpiration, with the help of which excess heat is removed from the leaves by water vapor, as well as to create optimal conditions for the entry of carbon dioxide through the stomata.

Visible part of the spectrum make up about 50% of the radiant energy reaching the Earth. This energy is needed by plants for photosynthesis. However, only 1% of it is used for this, the rest is reflected or dissipated in the form of heat. This region of the spectrum has led to the appearance of many important adaptations in plant and animal organisms. In green plants, in addition to the formation of a light-absorbing pigment complex, with the help of which the process of photosynthesis is carried out, a bright color of flowers has arisen, which helps to attract pollinators.

For animals, light mainly plays an informational role and is involved in the regulation of many physiological and biochemical processes. Protozoa already have light-sensitive organelles (a light-sensitive eye in Euglena green), and the reaction to light is expressed in the form of phototaxis - movement towards the highest or lowest illumination. Starting with the coelenterates, practically all animals develop photosensitive organs of various structures. There are nocturnal and crepuscular animals (owls, the bats etc.), as well as animals living in constant darkness (medvedka, roundworm, mole, etc.).

UV part characterized by the highest quantum energy and high photochemical activity. With the help of ultraviolet rays with a wavelength of 0.29-0.40 microns, biosynthesis of vitamin D, retinal pigments, and skin is carried out in animals. These rays are best perceived by the organs of vision of many insects, in plants they have a shaping effect and contribute to the synthesis of certain biologically active compounds (vitamins, pigments). Rays with a wavelength of less than 0.29 microns have a detrimental effect on living things.

intensity [show] ,

Plants, whose life activity is entirely dependent on light, have various morphostructural and functional adaptations to the light regime of habitats. According to the requirements for lighting conditions, plants are divided into the following ecological groups:

1. Light-loving (heliophytes) plants open habitats that thrive only in full sunlight. They are characterized by a high intensity of photosynthesis. These are early spring plants of the steppes and semi-deserts (goose onions, tulips), plants of treeless slopes (sage, mint, thyme), cereals, plantain, water lily, acacia, etc.
2. shade tolerant plants are characterized by a wide ecological amplitude to the light factor. It grows best in high light conditions, but is able to adapt to conditions of different levels of shading. These are woody (birch, oak, pine) and herbaceous (wild strawberry, violet, St. John's wort, etc.) plants.
3. Shade-loving plants (sciophytes) they cannot stand strong lighting, they grow only in shaded places (under the canopy of the forest), and they never grow in open places. In clearings under strong illumination, their growth slows down, and sometimes they die. These plants include forest grasses - ferns, mosses, oxalis, etc. Adaptation to shading is usually combined with the need for good water supply.

Daily and seasonal frequency [show] .

The daily periodicity determines the processes of growth and development of plants and animals, which depend on the length of daylight hours.

The factor that regulates and controls the rhythm of the daily life of organisms is called photoperiodism. It is the most important signal factor that allows plants and animals to "measure time" - the ratio between the duration of the period of illumination and darkness during the day, to determine the quantitative parameters of illumination. In other words, photoperiodism is the reaction of organisms to the change of day and night, which manifests itself in fluctuations in the intensity of physiological processes - growth and development. It is the duration of day and night that changes very accurately and naturally throughout the year, regardless of random factors, invariably repeating from year to year, therefore organisms in the process of evolution coordinated all stages of their development with the rhythm of these time intervals.

In the temperate zone, the property of photoperiodism serves as a functional climatic factor that determines the life cycle of most species. In plants, the photoperiodic effect is manifested in the coordination of the period of flowering and ripening of fruits with the period of the most active photosynthesis, in animals - in the coincidence of the time of reproduction with the period of abundance of food, in insects - in the onset of diapause and exit from it.

The biological phenomena caused by photoperiodism also include seasonal migrations (flights) of birds, the manifestation of their nesting instincts and reproduction, the change of fur coats in mammals, etc.

According to the required duration of the light period, plants are divided into

• long-day ones, which require more than 12 hours of light time for normal growth and development (flax, onions, carrots, oats, henbane, dope, young, potatoes, belladonna, etc.);
• short-day plants - they need at least 12 hours of uninterrupted dark period for flowering (dahlias, cabbage, chrysanthemums, amaranth, tobacco, corn, tomatoes, etc.);
• neutral plants in which the development of generative organs occurs both with long and short days (marigolds, grapes, phloxes, lilacs, buckwheat, peas, knotweed, etc.)

Long-day plants originate mainly from northern latitudes, short-day plants from southern latitudes. In the tropical zone, where the length of day and night varies little throughout the year, the photoperiod cannot serve as an orienting factor in the periodicity of biological processes. It is replaced by alternating dry and wet seasons. Long-day species have time to produce crops even in the conditions of a short northern summer. The formation of a large mass of organic substances occurs in summer during a rather long daylight hours, which at the latitude of Moscow can reach 17 hours, and at the latitude of Arkhangelsk - more than 20 hours per day.

The length of the day significantly affects the behavior of animals. With the onset of spring days, the duration of which progressively increases, nesting instincts appear in birds, they return from warm lands (although the air temperature may still be unfavorable), and begin laying eggs; warm-blooded animals molt.

The shortening of the day in autumn causes opposite seasonal phenomena: birds fly away, some animals hibernate, others grow a dense coat, wintering stages form in insects (despite the still favorable temperature and abundance of food). In this case, a decrease in the length of the day signals to living organisms that the winter period is approaching, and they can prepare for it in advance.

In animals, especially arthropods, growth and development also depend on the length of daylight hours. For example, cabbage whites, birch moths develop normally only with a long daylight hours, while silkworms, different kinds locusts, scoop - with a short. Photoperiodism also affects the time of onset and termination of the mating season in birds, mammals, and other animals; on reproduction, embryonic development of amphibians, reptiles, birds and mammals;

Seasonal and diurnal changes in illumination are the most accurate clocks, the course of which is clearly regular and practically has not changed during the last period of evolution.

Thanks to this, it became possible to artificially regulate the development of animals and plants. For example, the creation of plants in greenhouses, greenhouses or hotbeds of daylight hours lasting 12-15 hours allows you to grow vegetables even in winter, ornamental plants, accelerate the growth and development of seedlings. Conversely, shading the plants in summer accelerates the emergence of flowers or seeds of late-blooming autumn plants.

Continuation of the day due to artificial lighting in winter, it is possible to increase the egg-laying period of chickens, geese, ducks, to regulate the reproduction of fur-bearing animals on fur farms. The light factor also plays an important role in other life processes of animals. First of all, it is a necessary condition for vision, their visual orientation in space as a result of the perception by the organs of vision of direct, scattered or reflected light rays from surrounding objects. The information content for most animals of polarized light, the ability to distinguish colors, to navigate by astronomical light sources in the autumn and spring migrations of birds, and in the navigational abilities of other animals is great.

On the basis of photoperiodism in plants and animals, in the process of evolution, specific annual cycles of periods of growth, reproduction, and preparation for winter have been developed, which are called annual or seasonal rhythms. These rhythms are manifested in a change in the intensity of the nature of biological processes and are repeated at annual intervals. The coincidence of the periods of the life cycle with the corresponding season is of great importance for the existence of the species. Seasonal rhythms provide plants and animals with the most favorable conditions for growth and development.

Moreover, the physiological processes of plants and animals are strictly dependent on the daily rhythm, which is expressed by certain biological rhythms. Consequently, biological rhythms are periodically recurring changes in the intensity and nature of biological processes and phenomena. In plants, biological rhythms are manifested in the daily movement of leaves, petals, changes in photosynthesis, in animals - in temperature fluctuations, changes in hormone secretion, cell division rate, etc. In humans, daily fluctuations in respiratory rate, pulse, blood pressure, wakefulness and sleep, etc. Biological rhythms are hereditarily fixed reactions, therefore, the knowledge of their mechanisms is important in organizing work and rest of a person.

Temperature

One of the most important abiotic factors on which the existence, development and distribution of organisms on Earth largely depends [show] .

The upper temperature limit for life on Earth is probably 50-60°C. At such temperatures, there is a loss of enzyme activity and protein folding. However, the general temperature range of active life on the planet is much wider and is limited by the following limits (Table 1):

Table 1. Temperature range of active life on the planet, °С

Among organisms that can exist at very high temperatures, thermophilic algae are known, which can live in hot springs at 70-80°C. Scale lichens, seeds and vegetative organs of desert plants (saxaul, camel thorn, tulips) located in the upper layer of hot soil successfully tolerate very high temperatures (65-80 ° C).

There are many species of animals and plants that can withstand large values ​​of sub-zero temperatures. Trees and shrubs in Yakutia do not freeze at minus 68°C. In Antarctica, at minus 70 ° C, penguins live, and in the Arctic - polar bears, arctic foxes, polar owls. Polar waters with temperatures ranging from 0 to -2°C are inhabited by various representatives of flora and fauna - microalgae, invertebrates, fish, whose life cycle constantly occurs in such temperature conditions.

The significance of temperature lies primarily in its direct influence on the rate and nature of the course of metabolic reactions in organisms. Since daily and seasonal temperature fluctuations increase with distance from the equator, plants and animals, adapting to them, show different needs for heat.

Adaptation methods

• Migration - resettlement in more favorable conditions. Whales, many species of birds, fish, insects and other animals migrate regularly throughout the year.
• Numbness - a state of complete immobility, a sharp decrease in vital activity, cessation of nutrition. It is observed in insects, fish, amphibians, mammals when the environmental temperature drops in autumn, winter (hibernation) or when it rises in summer in deserts (summer hibernation).
• Anabiosis is a state of sharp suppression of vital processes, when the visible manifestations of life temporarily stop. This phenomenon is reversible. It is noted in microbes, plants, lower animals. Seeds of some plants in suspended animation can be up to 50 years. Microbes in a state of suspended animation form spores, protozoa - cysts.

Many plants and animals, with appropriate training, successfully endure extremely low temperatures in a state of deep dormancy or anabiosis. In laboratory experiments, seeds, pollen, plant spores, nematodes, rotifers, cysts of protozoa and other organisms, spermatozoa, after dehydration or placement in solutions of special protective substances - cryoprotectants - endure temperatures close to absolute zero.

At present, progress has been made in practical use substances with cryoprotective properties (glycerin, polyethylene oxide, dimethyl sulfoxide, sucrose, mannitol, etc.) in biology, agriculture, and medicine. In solutions of cryoprotectants, long-term storage of canned blood, sperm for artificial insemination of farm animals, some organs and tissues for transplantation is carried out; protection of plants from winter frosts, early spring frosts, etc. The above problems are within the competence of cryobiology and cryomedicine and are being solved by many scientific institutions.

• Thermoregulation. Plants and animals in the process of evolution have developed various mechanisms of thermoregulation:

1. in plants
   • physiological - the accumulation of sugar in the cells, due to which the concentration of cell sap increases and the water content of the cells decreases, which contributes to the frost resistance of plants. For example, in dwarf birch, juniper, the upper branches die at extremely low temperatures, and the creeping ones overwinter under the snow and do not die.
   • physical
     1. stomatal transpiration - removal of excess heat and prevention of burns by removing water (evaporation) from the plant body
     2. morphological - aimed at preventing overheating: dense pubescence of the leaves to scatter the sun's rays, a glossy surface to reflect them, a decrease in the absorbing surface of the rays - folding the leaf blade into a tube (feather grass, fescue), positioning the leaf with an edge to the sun's rays (eucalyptus), reduction of foliage ( saxaul, cactus); aimed at preventing freezing: special forms of growth - dwarfing, formation of creeping forms (wintering under snow), dark color (helps to better absorb heat rays and warm up under snow)
2. in animals
   • cold-blooded (poikilothermic, ectothermic) [invertebrates, fish, amphibians and reptiles] - regulation of body temperature is carried out passively by increasing muscle work, features of the structure and color of the integument, finding places where intense absorption of sunlight is possible, etc., t .to. they cannot maintain the temperature regime of metabolic processes and their activity depends mainly on the heat coming from outside, and the body temperature - on the values ​​of the ambient temperature and energy balance (the ratio of absorption and return of radiant energy).
   • warm-blooded (homeothermic, endothermic) [birds and mammals] - able to maintain a constant body temperature regardless of the temperature of the environment. This property makes it possible for many animal species to live and breed at temperatures below zero (reindeer, polar bear, pinnipeds, penguins). In the process of evolution, they have developed two thermoregulatory mechanisms by which they maintain a constant body temperature: chemical and physical. [show] .
     • The chemical mechanism of thermoregulation is provided by the speed and intensity of redox reactions and is controlled reflexively by the central nervous system. An important role in increasing the efficiency of the chemical mechanism of thermoregulation was played by such aromorphoses as the appearance of a four-chambered heart, the improvement of the respiratory organs in birds and mammals.
     • The physical mechanism of thermoregulation is provided by the appearance of heat-insulating covers (feathers, fur, subcutaneous fat), sweat glands, respiratory organs, as well as the development of nervous mechanisms for regulating blood circulation.

     A special case of homoiothermia is heterothermia - a different level of body temperature depending on the functional activity of the organism. Heterothermia is characteristic of animals that fall into hibernation or temporary stupor during an unfavorable period of the year. At the same time, their high body temperature is noticeably reduced due to slow metabolism (ground squirrels, hedgehogs, bats, swift chicks, etc.).

Endurance limits large values temperature factors are different in both poikilothermic and homeothermic organisms.

Eurythermal species are able to tolerate temperature fluctuations over a wide range.

Stenothermic organisms live in conditions of narrow temperature limits, subdivided into heat-loving stenothermic species (orchids, tea bush, coffee, corals, jellyfish, etc.) ocean depths, etc.).

For each organism or group of individuals, there is an optimal temperature zone within which activity is especially well expressed. Above this zone is a zone of temporary thermal stupor, even higher - a zone of prolonged inactivity or summer hibernation, bordering on a zone of high lethal temperature. When the latter falls below the optimum, there is a zone of cold stupor, hibernation and lethal low temperature.

The distribution of individuals in the population, depending on the change in the temperature factor over the territory, generally obeys the same pattern. The zone of optimal temperatures corresponds to the highest population density, and on both sides of it, a decrease in density is observed up to the border of the range, where it is the lowest.

The temperature factor over a large area of ​​the Earth is subject to pronounced daily and seasonal fluctuations, which in turn determines the corresponding rhythm of biological phenomena in nature. Depending on the provision of thermal energy to symmetrical sections of both hemispheres of the globe, starting from the equator, the following climatic zones are distinguished:

1. tropical zone. The minimum average annual temperature exceeds 16° C, on the coolest days it does not fall below 0° C. Temperature fluctuations over time are insignificant, the amplitude does not exceed 5° C. Vegetation is year-round.
2. subtropical zone. The average temperature of the coldest month is not lower than 4° C, and the warmest month is above 20° C. Sub-zero temperatures are rare. There is no stable snow cover in winter. The growing season lasts 9-11 months.
3. temperate zone. Well-defined summer growing season and winter period dormancy of plants. The main part of the zone has stable snow cover. Frosts are typical in spring and autumn. Sometimes this zone is divided into two: moderately warm and moderately cold, which are characterized by four seasons.
4. cold zone. The average annual temperature is below 0 ° C, frosts are possible even during a short (2-3 months) growing season. The annual temperature fluctuation is very large.

The pattern of vertical distribution of vegetation, soils, and wildlife in mountainous areas is also mainly due to the temperature factor. In the mountains of the Caucasus, India, Africa, four or five plant belts can be distinguished, the sequence of which from bottom to top corresponds to the sequence of latitudinal zones from the equator to the pole at the same height.

Humidity

An environmental factor characterized by the water content in the air, soil, living organisms. In nature, there is a daily rhythm of humidity: it rises at night and falls during the day. Together with temperature and light, humidity plays an important role in regulating the activity of living organisms. The main source of water for plants and animals is precipitation and The groundwater as well as dew and fog.

Moisture is a necessary condition for the existence of all living organisms on Earth. Life originated in the aquatic environment. The inhabitants of the land are still dependent on water. For many species of animals and plants, water continues to be a habitat. The importance of water in life processes is determined by the fact that it is the main environment in the cell, where metabolic processes are carried out, it acts as the most important initial, intermediate and final product of biochemical transformations. The importance of water is also determined by its quantitative content. Living organisms consist of at least 3/4 of water.

In relation to water, higher plants are divided into

• hydrophytes - aquatic plants(water lily, arrowhead, duckweed);
• hygrophytes - inhabitants of excessively humid places (calamus, watch);
• mesophytes - plants of normal humidity conditions (lily of the valley, valerian, lupine);
• xerophytes - plants living in conditions of constant or seasonal moisture deficiency (saxaul, camel thorn, ephedra) and their varieties succulents (cacti, euphorbia).

Adaptations for living in a dehydrated environment and an environment with a periodic lack of moisture An important feature of the main climatic factors (light, temperature, humidity) is their regular variability during the annual cycle and even during the day, as well as depending on the geographical zonality. In this regard, the adaptations of living organisms also have a regular and seasonal character. Adaptation of organisms to environmental conditions can be fast and reversible or rather slow, which depends on the depth of the impact of the factor. As a result of vital activity, organisms are able to change the abiotic conditions of life. For example, plants of the lower tier are in conditions of less illumination; the processes of decomposition of organic substances that occur in water bodies often cause oxygen deficiency for other organisms. Due to the activity of aquatic organisms, the temperature and water regimes, the amount of oxygen, carbon dioxide, pH of the environment, the spectral composition of light, etc., change. Air environment and its gas composition The development of the air environment by organisms began after they landed. Life in the air required specific adaptations and a high level of organization of plants and animals. Low density and water content, high oxygen content, ease of movement of air masses, sudden changes in temperature, etc., significantly affected the process of respiration, water exchange and the movement of living beings. The vast majority of terrestrial animals in the course of evolution acquired the ability to fly (75% of all species of terrestrial animals). Many species are characterized by ansmochory - settlement with the help of air currents (spores, seeds, fruits, protozoan cysts, insects, spiders, etc.). Some plants have become wind pollinated. For the successful existence of organisms, not only physical, but also Chemical properties air, the content in it of gas components necessary for life. Oxygen. For the vast majority of living organisms, oxygen is vital. Only anaerobic bacteria can thrive in an anoxic environment. Oxygen ensures the implementation of exothermic reactions, during which the energy necessary for the life of organisms is released. It is the final electron acceptor, which is split off from the hydrogen atom in the process of energy exchange. In a chemically bound state, oxygen is part of many very important organic and mineral compounds of living organisms. Its role as an oxidizing agent in the circulation of individual elements of the biosphere is enormous. The only producers of free oxygen on Earth are green plants, which form it in the process of photosynthesis. A certain amount of oxygen is formed as a result of photolysis of water vapor by ultraviolet rays outside the ozone layer. The absorption of oxygen by organisms from the external environment occurs by the entire surface of the body (protozoa, worms) or by special respiratory organs: tracheae (insects), gills (fish), lungs (vertebrates). Oxygen is chemically bound and transported throughout the body by special blood pigments: hemoglobin (vertebrates), hemocyapin (molluscs, crustaceans). Organisms living in conditions of constant lack of oxygen have developed appropriate adaptations: increased oxygen capacity of the blood, more frequent and deeper respiratory movements, large lung capacity (in highlanders, birds) or a decrease in the use of oxygen by tissues due to an increase in the amount of myoglobin, an oxygen accumulator in tissues (among the inhabitants of the aquatic environment). Due to the high solubility of CO 2 and O 2 in water, their relative content here is higher (2-3 times) than in the air (Fig. 1). This circumstance is very important for aquatic organisms that use either dissolved oxygen for respiration or CO2 for photosynthesis (aquatic phototrophs). Carbon dioxide. The normal amount of this gas in the air is small - 0.03% (by volume) or 0.57 mg / l. As a result, even small fluctuations in the content of CO 2 are significantly reflected in the process of photosynthesis, which directly depends on it. The main sources of CO 2 entering the atmosphere are the respiration of animals and plants, combustion processes, volcanic eruptions, the activity of soil microorganisms and fungi, industrial enterprises and transport. Possessing the property of absorption in the infrared region of the spectrum, carbon dioxide affects the optical parameters and the temperature regime of the atmosphere, causing the well-known "greenhouse effect". An important ecological aspect is the increase in the solubility of oxygen and carbon dioxide in water as its temperature decreases. That is why the fauna of the water basins of the polar and subpolar latitudes is very abundant and diverse, mainly due to the increased concentration in cold water oxygen. The dissolution of oxygen in water, like any other gas, obeys Henry's law: it is inversely proportional to temperature and stops when the boiling point is reached. In the warm waters of tropical basins, a reduced concentration of dissolved oxygen limits respiration, and, consequently, the life and number of aquatic animals. Recently, there has been a noticeable deterioration in the oxygen regime of many water bodies, caused by an increase in the amount of organic pollutants, the destruction of which requires a large amount of oxygen. Zoning of the distribution of living organisms Geographic (latitudinal) zonality In the latitudinal direction from north to south, the following natural zones are successively located on the territory of the Russian Federation: tundra, taiga, deciduous forest, steppe, desert. Among the elements of climate that determine the zonality of the distribution and distribution of organisms, the leading role is played by abiotic factors - temperature, humidity, light regime. The most noticeable zonal changes are manifested in the nature of vegetation - the leading component of the biocenosis. This, in turn, is accompanied by changes in the composition of animals - consumers and destructors of organic residues in the links of food chains. Tundra- a cold, treeless plain of the northern hemisphere. Its climatic conditions are not very suitable for the vegetation of plants and the decomposition of organic residues (permafrost, relatively low temperatures even in summer, a short period of positive temperatures). Here, peculiar small in species composition (mosses, lichens) biocenoses were formed. In this regard, the productivity of the tundra biocenosis is low: 5-15 c/ha of organic matter per year. Zone taiga characterized by relatively favorable soil and climatic conditions, especially for conifers. Rich and highly productive biocenoses have formed here. The annual formation of organic matter is 15-50 c/ha. The conditions of the temperate zone led to the formation of complex biocenoses deciduous forests with the highest biological productivity on the territory of the Russian Federation (up to 60 c/ha per year). Varieties of deciduous forests are oak forests, beech-maple forests, mixed forests, etc. Such forests are characterized by well-developed shrub and grassy undergrowth, which contributes to the placement of fauna diverse in species and quantity. Steppes- a natural zone of the temperate zone of the hemispheres of the Earth, which is characterized by insufficient water supply, therefore herbaceous, mainly cereal vegetation (feather grass, fescue, etc.) prevails here. Animal world diverse and rich (fox, hare, hamster, mice, many birds, especially migratory ones). The steppe zone contains the most important areas for the production of grain, technical, vegetable crops and animal husbandry. The biological productivity of this natural area relatively high (up to 50 c/ha per year). desert prevail in Central Asia. Due to low rainfall and high temperatures in summer, vegetation covers less than half of the territory of this zone and has specific adaptations to dry conditions. The animal world is diverse, its biological features were considered earlier. The annual formation of organic matter in the desert zone does not exceed 5 q/ha (Fig. 107). Salinity of the environment Salinity of the aquatic environment characterized by the content of soluble salts in it. Fresh water contains 0.5-1.0 g / l, and sea water contains 10-50 g / l of salts. The salinity of the aquatic environment is important for its inhabitants. There are animals adapted to live only in fresh water (cyprinids) or only in sea water (herring). In some fish, individual stages of individual development pass at different salinities of the water, for example, the common eel lives in fresh water bodies, and migrates to spawn in the Sargasso Sea. Such aquatic inhabitants need an appropriate regulation of the salt balance in the body. Mechanisms of regulation of the ionic composition of organisms. Land animals are forced to regulate the salt composition of their liquid tissues in order to maintain the internal environment in a constant or almost constant chemically unaltered ionic state. The main way to maintain salt balance in aquatic organisms and terrestrial plants is to avoid habitats with inappropriate salinity. Such mechanisms should work especially intensely and accurately in migratory fish (salmon, chum salmon, pink salmon, eel, sturgeon), which periodically pass from sea water to fresh water or vice versa. The easiest way is osmotic regulation in fresh water. It is known that the concentration of ions in the latter is much lower than in liquid tissues. According to the laws of osmosis, the external environment along the concentration gradient through semi-permeable membranes enters the cells, there is a kind of "breeding" of the internal contents. If such a process were not controlled, the organism could swell and die. However, freshwater organisms have organs that remove excess water to the outside. Preservation of the ions necessary for life is facilitated by the fact that the urine of such organisms is quite dilute (Fig. 2, a). The separation of such a diluted solution from internal fluids probably requires the active chemical work of specialized cells or organs (kidneys) and their consumption of a significant proportion of the total basal metabolic energy. On the contrary, marine animals and fish drink and assimilate only sea water, thereby replenishing its constant output from the body during external environment, which is characterized by a high osmotic potential. At the same time, monovalent ions of salt water are actively excreted by the gills, and divalent ions - by the kidneys (Fig. 2, b). Cells spend quite a lot of energy on pumping out excess water, therefore, with an increase in salinity and a decrease in water in the body, organisms usually switch to an inactive state - salt suspended animation. This is characteristic of species that live in periodically drying puddles. sea ​​water, estuaries, on the littoral (rotifers, bo-coplovs, flagellates, etc.) Salinity of the upper layer of the earth's crust is determined by the content of potassium and sodium ions in it, and, like the salinity of the aquatic environment, is important for its inhabitants and, first of all, plants that have the appropriate adaptation to it. This factor is not accidental for plants; it accompanies them during the evolutionary process. The so-called solonchak vegetation (saltwort, licorice, etc.) is confined to soils with a high content of potassium and sodium. The top layer of the earth's crust is the soil. In addition to soil salinity, its other indicators are distinguished: acidity, hydrothermal regime, soil aeration, etc. Together with the relief, these properties of the earth's surface, called edaphic factors of the environment, have an ecological impact on its inhabitants. Edaphic environmental factors Properties of the earth's surface that have an ecological impact on its inhabitants. borrowed soil profile Soil type is determined by its composition and color. A - Tundra soil has a dark peaty surface. B - Desert soil is light, coarse-grained and poor in organic matter Chestnut soil (C) and chernozem (D) are humus-rich meadow soils typical of the steppes of Eurasia and the prairies of North America. The reddish leached latosol (E) of the tropical savanna has a very thin but humus-rich layer. Podzolic soils are typical of northern latitudes, where there is a large amount of precipitation and very little evaporation. They include organic-rich brown forest podzol (F), grey-brown podzol (H), and grey-stony podzol (I), which bears both coniferous and deciduous trees. All of them are relatively acidic, and in contrast to them, the red-yellow podzol (G) of pine forests is quite strongly leached. Depending on the edaphic factors, a number of environmental groups plants. According to the reaction to the acidity of the soil solution, there are: acidophilic species growing at a pH below 6.5 (plants of peat bogs, horsetail, pine, fir, fern); neutrophilic, preferring soil with a neutral reaction (pH 7) (most cultivated plants); basiphilic - plants that grow best on a substrate that has alkaline reaction(pH over 7) (spruce, hornbeam, thuja) and indifferent - can grow on soils with different pH values. In relation to the chemical composition of the soil, plants are divided into oligotrophic, undemanding to the amount of nutrients; mesotrophic, requiring a moderate amount minerals in the soil (herbaceous perennials, spruce), mesotrophic, needing in large numbers available ash elements (oak, fruit). In relation to individual batteries species, especially demanding high content nitrogen in the soil are called - nitrophils (nettle, barnyard plants); requiring a lot of calcium - calcephiles (beech, larch, cutter, cotton, olive); plants of saline soils are called halophytes (saltwort, sarsazan), some of the halophytes are able to excrete excess salts outside, where these salts, after drying, form solid films or crystalline clusters In relation to the mechanical composition free-flowing sand plants - psammophytes (saxaul, sand acacia) plants of screes, cracks and depressions of rocks and other similar habitats - lithophytes [petrophytes] (juniper, sessile oak) The relief of the terrain and the nature of the soil significantly affect the specifics of the movement of animals, the distribution of species whose vital activity is temporarily or permanently connected with the soil. The nature of the root system (deep, surface) and the way of life of the soil fauna depend on the hydrothermal regime of soils, their aeration, mechanical and chemical composition. The chemical composition of the soil and the variety of inhabitants affect its fertility. The most fertile are chernozem soils rich in humus. As an abiotic factor, relief influences the distribution of climatic factors and, thus, the formation of the corresponding flora and fauna. For example, on the southern slopes of hills or mountains, there is always a higher temperature, better illumination and, accordingly, less humidity.

) and anthropogenic (human activity).

The limiting factor plant development is the element which lies at the minimum. This is determined by a law called the law of the minimum by J. Liebig (1840). Liebig, an organic chemist, one of the founders, put forward the theory of mineral nutrition of plants. The yield of crops is often limited by nutrients that are not present in excess, such as CO 2 and H 2 O, but those that are required in negligible quantities. For example: - necessary element plant nutrition, but it is not found in the soil. When its reserves are exhausted as a result of the cultivation of one crop, then the growth of plants stops, even if other elements are in abundance. Liebig's law is strictly applicable only under steady state conditions. It is necessary to take into account the interaction of factors. So, the high or availability of one or the action of another (not minimal) factor can change the rate of consumption of a battery contained in a minimum amount. Sometimes it is able to replace (partially) a deficient element with another, more accessible and chemically close to it. So, some plants need less if they grow in the light, and mollusks that live in places where there are a lot of them partially replace them when building a shell.

Environmental factors environments can have various kinds of influences on living things:

1) stimuli that cause adaptive changes in physiological and biochemical functions (for example, an increase leads to an increase in sweating in mammals and to body cooling);

2) constraints that make it impossible to exist in these conditions (for example, the lack of moisture in arid regions prevents many from penetrating there);

3) modifiers that cause anatomical and morphological changes (for example, dust in the industrial regions of some countries led to the formation of black moths of birch moths, which retained their light color in rural areas);

4) signals indicating a change in other environmental factors.

A number of general regularities have been revealed in the nature of the impact of environmental factors.

Law of Optimum- the positive or negative influence of the factor on - depends on the strength of its impact. Insufficient or excessive action of the factor equally negatively affects the life of individuals. The favorable force of the impact of the environmental factor is called the optimum zone. Some species endure fluctuations over a wide range, others - within narrow ones. Wide to any factor is indicated by the addition of the particle "evry", narrow - "steno" (eurythermal, stenothermic - in relation to, euryotopic and stenotopic - in relation to habitats).

The ambiguity of the action of the factor on different functions. Each factor has an ambiguous effect on different functions. The optimum for some processes may be unfavorable for others. For example, more than 40 ° C in cold-blooded animals increases the intensity of metabolic processes in, but inhibits motor, which leads to thermal stupor.

Interaction of factors. The optimal zone and limits of endurance in relation to any of the environmental factors may shift depending on the strength and combination of other factors acting simultaneously. So, the heat is easier to bear in a dry, rather than in a wet one. The threat of freezing is higher in frost with strong winds than in calm weather. At the same time, the mutual compensation of the action of environmental factors has certain limits and it is impossible to completely replace one of them with another. The lack of heat in the polar regions cannot be made up for either by an abundance of moisture or by round-the-clock illumination in the summer. Each species of animal requires its own set of environmental factors.

The impact of the chemical component of the abiotic factor on living things. Abiotic factors create living conditions for plants and animals and have a direct or indirect impact on the life of the latter. Abiotic factors include elements of inorganic nature: parent soil, chemical composition and the latter, sunlight, heat, and its chemical composition, its composition and, barometric and water, natural background radiation, etc. Chemical components abiotic factors are nutrient, trace elements, and, poisonous, acidity (pH) of the environment.

Influence of pH on the survival of aquatic organisms. Most people can't stand fluctuations in pH. they function only in an environment with a strictly defined regime of acidity-alkalinity. hydrogen is largely dependent on the carbonate system, which is important for the whole and is described by a complex system that is established when free CO 2 is found in natural freshwater, according to:

CO 2 + H 2 O + H 2 CO 3 + H + + HC.

Table 1.1

pH values ​​for European freshwater fish (according to R. Dajo, 1975)

Influence of the amount dissolved on the species composition and abundance of hydrobionts. The degree of saturation is inversely proportional to its. dissolved O 2 in the surface varies from 0 to 14 mg / l and is subject to significant seasonal and daily fluctuations, which mainly depend on the ratio of the intensity of the processes of its production and consumption. In the case of high intensity, O 2 can be significantly supersaturated (20 mg / l and above). In the aquatic environment is the limiting factor. O 2 is 21% (by volume) and about 35% of all dissolved in. its in the sea is 80% of that in the freshwater. Distribution 2) 5 - 7 mg / l - grayling, gudgeon, chub, burbot;. These species are able to survive by passing to a slow life, to anaerobiosis, or due to the fact that they have d-hemoglobin, which has a high affinity for the environment. waters, this indicator is very variable. Salinity is usually expressed in ppm (‰) and is one of the main characteristics of water masses, the distribution of seas, elements of sea currents, etc. It plays a special role in shaping the biological productivity of the seas and oceans, since many are very susceptible to its minor changes. Many animal species are entirely marine (many species of fish, invertebrates and mammals).

Brackish habitats are species that can tolerate high salinity. In estruaries, where the salinity is below 3‰, the marine fauna is poorer. In the Bali Sea, the salinity of which is 4 ‰, there are balanuses, annelids, as well as rotifers and hydroids.

Aquatic are divided into freshwater and marine according to the degree of salinityin which they live. Relatively few plants and animals can withstand large fluctuations in salinity. Such species usually live in river estruaries or in salt marshes and are called euryhaline. These include many inhabitants of the littoral zone (salinity is about 35 ‰), estruaries of rivers, brackish (5 - 35 ‰) and ultrasaline (50 - 250 ‰), as well as anadromous fish spawning in fresh water (< 5 ‰). Наиболее удивительный пример - рачок Artemia salina, способный существовать при солености от 20 до 250 ‰ и даже переносить полное временное опреснение. Способность существовать в с различной соленостью обеспечивается механизмами осморегуляции, которую поддерживают относительно постоянные осмотически активных в внутренней среды.

In relation to the salinity of the environment, animals are divided into stenohaline and euryhaline. Stenohaline animals are animals that cannot withstand significant changes in the salinity of the environment. This is the overwhelming number of inhabitants of marine and fresh water bodies. Euryhaline animals are able to live in a wide range of salinity fluctuations. For example, the snail Hydrobia ulvae is able to survive NaCl changes from 50 to 1600 mmol/ml. They also include the jellyfish Aurelia aurita, the edible mussel Mutilus edulis, the crab Carcinus maenas, and the appendicularia Oikopleura dioica.

Salinity tolerance varies from . For example, the hydroid Cordylophora caspia tolerates low salinity better at low salinity; decapods turn into low-salted when it gets too high. Species living in brackish areas differ from marine forms in size. Thus, the crab Carcinus maenas in the Baltic Sea is small, while in estuaries and lagoons it is large. The same can be said about the edible mussel Mutilus edulis, which has in the Baltic Sea the average size 4 cm, in the White Sea - 10 - 12 cm, and in the Sea of ​​Japan - 14 - 16 cm in accordance with the increase in salinity. In addition, the structure of euryhaline species also depends on the salinity of the environment. Artemia crustacean at a salinity of 122 ‰ has a size of 10 mm, at 20 ‰ it reaches 24 - 32 mm. At the same time, the shape of the body, appendages and color change.

Experience the cumulative effect of various conditions. Abiotic factors, biotic factors and anthropogenic affect the features of their life and adaptation.

What are environmental factors?

All conditions of inanimate nature are called abiotic factors. This is, for example, the amount of solar radiation or moisture. Biotic factors include all types of interaction between living organisms. In recent years, human activity has an increasing influence on living organisms. This factor is anthropogenic.

Abiotic environmental factors

The action of inanimate factors depends on climatic conditions habitat. One of them is sunlight. The intensity of photosynthesis, and hence the saturation of air with oxygen, depends on its quantity. It is this substance that living organisms need for respiration.

Abiotic factors also include temperature and air humidity. The species diversity and the growing season of plants, the features of the life cycle of animals depend on them. Living organisms adapt to these factors in different ways. For example, most angiosperms shed their leaves for the winter to avoid excessive moisture loss. Desert plants have which reaches considerable depths. This provides them with the necessary amount of moisture. Primroses have time to grow and bloom in a few spring weeks. And the period of dry summer and cold winter with little snow they experience underground in the form of an onion. This underground modification of the shoot accumulates a sufficient amount of water and nutrients.

Abiotic environmental factors also involve the influence of local factors on living organisms. These include the nature of the relief, the chemical composition and saturation of soils with humus, the level of salinity of the water, the nature of ocean currents, the direction and speed of the wind, and the direction of radiation. Their influence manifests itself both directly and indirectly. Thus, the nature of the relief determines the effect of winds, moisture and illumination.

Influence of abiotic factors

Factors of inanimate nature have a different nature of the impact on living organisms. Monodominant is the impact of one predominant influence with a slight manifestation of the rest. For example, if there is not enough nitrogen in the soil, root system develops at an insufficient level and other elements cannot influence its development.

Strengthening the action of several factors at the same time is a manifestation of synergy. So, if there is enough moisture in the soil, plants begin to absorb both nitrogen and solar radiation better. Abiotic factors, biotic factors and anthropogenic factors can be provocative. With an early onset of the thaw, the plants will most likely suffer from frost.

Features of the action of biotic factors

The biotic factors are various forms influence of living organisms on each other. They can also be direct and indirect and appear quite polar. In certain cases organisms have no effect. This is a typical manifestation of neutralism. This rare phenomenon is considered only in the absence of direct interaction of organisms with each other. Living in a common biogeocenosis, squirrels and moose do not interact in any way. However, they are affected by the general quantitative ratio in the biological system.

Examples of biotic factors

Commensalism is also a biotic factor. For example, when deer carry burdock fruits, they do not receive any benefit or harm from this. At the same time, they bring significant benefits, settling many types of plants.

Between organisms often arise and Their examples are mutualism and symbiosis. In the first case, there is a mutually beneficial cohabitation of organisms different types. A typical example of mutualism is the hermit crab and anemone. Its predatory flower is a reliable defense of the arthropod. And the sea anemone shell is used as a dwelling.

A closer mutually beneficial cohabitation is symbiosis. His classic example are lichens. This group of organisms is a collection of filaments of fungi and cells of blue-green algae.

Biotic factors, examples of which we have considered, can be supplemented with predation. In this type of interaction, organisms of one species are food for others. In one case, predators attack, kill and eat their prey. In another, they are engaged in the search for organisms of certain species.

Action of anthropogenic factors

Abiotic factors, biotic factors have long been the only ones that affect living organisms. However, with the development human society its influence on nature increased more and more. The famous scientist V. I. Vernadsky even singled out a separate shell created by human activity, which he called the Noosphere. Deforestation, unlimited plowing of land, the extermination of many species of plants and animals, unreasonable nature management are the main factors that change the environment.

Habitat and its factors

The biotic factors, examples of which have been given, along with other groups and forms of influences, have their own significance in different habitats. Ground-air vital activity of organisms largely depends on fluctuations in air temperature. And in water, the same indicator is not so important. The action of the anthropogenic factor at the moment is of particular importance in all habitats of other living organisms.

and adaptation of organisms

A separate group can be identified factors that limit the vital activity of organisms. They are called limiting or limiting. For deciduous plants, abiotic factors include the amount of solar radiation and moisture. They are limiting. In the aquatic environment, its salinity level and chemical composition are limiting. So global warming leads to the melting of glaciers. In turn, this leads to an increase in the content fresh water and a decrease in its salinity. As a result, plant and animal organisms that cannot adapt to changes in this factor and adapt inevitably die. At the moment, this is a global environmental problem of mankind.

So, abiotic factors, biotic factors and anthropogenic factors together act on different groups living organisms in their habitats, regulating their numbers and life processes, changing the species richness of the planet.