The cycle of chemical elements in nature. The cycle of the most important chemical elements in nature

Chemical elements are constantly exchanged between the lithosphere, hydrosphere, atmosphere and living organisms of the Earth. This process is cyclical: having moved from one sphere to another, the elements again return to their original state. The turnover of elements took place throughout the entire history of the Earth, numbering 4.5 billion years.

Huge masses of chemicals are carried by the waters of the oceans. This primarily applies to dissolved gases - carbon dioxide, oxygen, nitrogen. Cold water at high latitudes dissolves gases in the atmosphere. Coming with ocean currents into the tropical belt, it releases them, since the solubility of gases decreases when heated. The absorption and release of gases also occurs during the alternation of warm and cold seasons.

The emergence of life on the planet had a huge impact on the natural cycles of some elements. This, first of all, refers to the circulation of the main elements of organic matter - carbon, hydrogen and oxygen, as well as such vital elements as nitrogen, sulfur and phosphorus. Living organisms also influence the circulation of many metallic elements. Despite the fact that the total mass of living organisms on the Earth is millions of times less than the mass of the earth's crust, plants and animals play an important role in the movement of chemical elements.

The processes of photosynthesis of organic matter from inorganic components lasts for millions of years, and during this time, chemical elements had to pass from one form to another. However, this does not happen due to their circulation in the biosphere. Photosynthetic organisms annually assimilate about 350 billion tons of carbon dioxide, release about 250 billion tons of oxygen into the atmosphere and break down 140 billion tons of water, forming more than 230 billion tons of organic matter (in terms of dry weight).

Enormous amounts of water pass through plants and algae during transport and evaporation. This leads to the fact that the water of the surface layer of the ocean is filtered by plankton in 40 days, and all the rest of the ocean water - in about a year. The whole carbon dioxide the atmosphere is renewed in several hundred years, and oxygen in several thousand years. Every year, 6 billion tons of nitrogen, 210 billion tons of phosphorus and a large amount of other elements (potassium, sodium, calcium, magnesium, sulfur, iron, etc.) are included in the cycle by photosynthesis. the existence of these cycles gives the ecosystem a certain stability.

There are two main cycles: large (geological) and small (biotic).

The great cycle, lasting millions of years, is that rocks are destroyed, and weathering products (including water-soluble nutrients) are carried by water flows into the World Ocean, where they form marine strata and only partially return to land with precipitation ... Geotectonic changes, the processes of subsidence of the continents and the raising of the seabed, the movement of seas and oceans for a long time lead to the fact that these strata return to land and the process begins again.

A small cycle (part of a large one) occurs at the level of the ecosystem and consists in the fact that nutrients, water and carbon are accumulated in plant matter, spent on building a body and on life processes of both these plants themselves and other organisms (usually animals), which these plants eat (consumers). The decomposition products of organic matter under the action of destructors and microorganisms (bacteria, fungi, worms) decompose again to mineral components available to plants and entrained by them in the flows of matter.

In all natural waters ah in the dissolved state contains various gases, mainly nitrogen, oxygen and carbon dioxide. The amount of gases that seawater can dissolve depends on its salinity, hydrostatic pressure, but mainly on temperature. The higher the salinity and the higher the temperature, the less gases the sea water can dissolve, and vice versa.

Sea water is involved in many chemical and biochemical transformations of substances that are in it in a dissolved, colloidal and suspended form, in a free state and in various compounds. The hydrosphere as a whole serves as a medium and a powerful vehicle in the complex changes and movements of chemical elements occurring in the biosphere and lithosphere.

About 10 million tons of nitrogen in ionic form and about 20 million tons in the form of organic compounds are annually carried out into the oceans by rivers. Since little nitrogen is released into sedimentary rocks, it can be assumed that, in the course of natural processes, denitrification in the World Ocean balances the fixation of nitrogen and its removal to land. In connection with the use of fertilizers, its quantity entering the water bodies has increased sharply, deteriorating the quality of water.

Phosphorus is the most important biogenic element, most often limiting the development of the productivity of water bodies. Therefore, the supply of excess phosphorus compounds from the catchment with surface runoff from fields, with runoff from farms, with untreated domestic wastewater, as well as with some industrial waste, leads to a sharp uncontrolled increase in plant biomass water body(this is especially typical for stagnant and low-flowing reservoirs). Human activities have disrupted the natural cycle of phosphorus. Phosphorus compounds are used for the production of fertilizers and detergents... This leads to the pollution of water bodies with phosphorus compounds. Under such conditions, phosphorus ceases to be an element that limits the growth of the mass of living beings, especially algae and other aquatic plants.

Sulfur is contained in the atmosphere in not large quantities ah, mainly in the form of hydrogen sulfide and sulfur dioxide. Quite a lot of this element (in the form of sulfate ions) is found in the hydrosphere. In the lithosphere, sulfur occurs in the form simple substance(native sulfur) and in the composition of numerous minerals - sulfides and sulfates of metals. In addition, sulfur compounds are found in coal, shale, oil, and natural gas. Sulfur is a part of many proteins, so it is always found in the organisms of animals and plants. Human activities have significantly altered the sulfur cycle between the atmosphere, oceans and land surfaces. These changes are stronger than the human impact on the carbon cycle. As in the case of the global carbon cycle, man-made emissions of sulfur into the environment have little effect on the mass distribution of this element on the Earth's surface. However, the increased sulfur content in industrial and domestic waste poses a threat to life in large areas. The massive release of sulfur dioxide into the atmosphere generates acid rain, which can fall far beyond industrial areas. The pollution of natural waters with soluble sulfur compounds threatens the living organisms of inland water bodies and coastal areas of the seas.

Carbon is the main element of life. It is found in the atmosphere in the form of carbon dioxide. In the ocean and fresh waters of the Earth, carbon is in two main forms: in the composition of organic matter and in the composition of interconnected inorganic particles: bicarbonate - ion, carbonate ion and dissolved carbon dioxide. The bulk is accumulated in carbonates on the ocean floor (1016 tons), in crystalline rocks (1016 tons), coal and oil (1016 tons) and participates in a large cycle of circulation. In the last century, significant changes have been made in the carbon cycle by human economic activity. The burning of fossil fuels - coal, oil and gas - has increased the release of carbon dioxide into the atmosphere. This does not greatly affect the distribution of carbon masses between the shells of the Earth, but it can have serious consequences due to the intensification of the greenhouse effect.

Silicon is the second most abundant chemical element (after oxygen) in the earth's crust. Its clarke in the earth's crust is 29.5, in the soil - 33, in the ocean - 5x10 -5. However, despite the enormous prevalence of silicon and its compounds in nature (quartz and silicates make up 87% of the lithosphere), the biogeochemical cycles of silicon (especially on land) have not yet been sufficiently studied. Manganese and iron are permanent constituents of natural fresh waters, and their content often exceeds the levels of the main macronutrients.



Introduction

1 The cycle of the most important chemical elements in nature

1.1 The water cycle.

1.2. The carbon cycle.

1.3. The nitrogen cycle

1.4. The sulfur cycle.

1.5. Phosphorus cycle

3 The ecological role of the main abiotic factors

3.1. Solar radiation

3.2. Temperature.

3.3 Humidity.

3.4. Air-gas mode

4 Basic laws of action of abiotic factors

4.1. The concept of the optimum

4.2. The concept of tolerance

4.3. Liebig's law, or "law of minimum", or the law of the limiting factor

4.5. Preceding rule V.V. Alekhina

4.6. The principle of stationary fidelity G.Ya. Bey-Bienko

4.7. The rule of zonal change of longlines M.S. Gilyarova

5 Ecological significance of abiotic factors

6 Adaptation of living organisms to environmental conditions.

7 Biotic factors and their description.

8 Biosphere

8.1. Biosphere: functions of living matter.

8.3. Biosphere: protective screens

9. Sustainability natural environment(ecosystems) in Russia.

Conclusion.

Bibliography

Annex 1

The value of nitrogen for living organisms is determined mainly by its content in proteins and nucleic acids. Nitrogen, like carbon, is a part of organic compounds; the cycles of these elements are closely related. The main source of nitrogen is atmospheric air. Due to fixation by living organisms, nitrogen flows from the air into the soil and water. Blue-greens bind about 25 kg / ha of nitrogen annually. They effectively fix nitrogen and nodule bacteria.

Plants absorb nitrogen compounds from the soil and synthesize organic matter. Organic matter spreads along food chains up to decomposers, decomposing proteins with the release of ammonia, which is further converted by other bacteria to nitrites and nitrates. A similar circulation of nitrogen occurs between the organisms of benthos and plankton. Denitrifying bacteria reduce nitrogen to free molecules that are returned to the atmosphere. A small amount of nitrogen is fixed in the form of oxides by lightning discharges and enters the soil with atmospheric precipitation, and also comes from volcanic activity, compensating for the loss into deep-sea sediments. Nitrogen also enters the soil in the form of fertilizers after industrial fixation from the air of the atmosphere.

The nitrogen cycle is a more closed cycle than the carbon cycle. Only a small amount of it is washed out by rivers or escapes into the atmosphere, leaving the boundaries of ecosystems.

1.4. The sulfur cycle.

Sulfur is part of a number of amino acids and proteins. Sulfur compounds enter the circulation mainly in the form of sulphides from the weathering products of land and seabed rocks. A number of microorganisms (for example, chemosynthetic bacteria) are capable of converting sulfides into a form accessible to plants - sulfates. Plants and animals die, the mineralization of their remains by decomposers returns sulfur compounds to the soil. So, sulfur bacteria oxidize hydrogen sulfide formed during the decomposition of proteins to sulfates. Sulfates contribute to the conversion of sparingly soluble phosphorus compounds into soluble ones. The amount of mineral compounds available to plants increases, and the conditions for their nutrition are improved.

The resources of sulfur-containing minerals are very significant, and the excess of this element in the atmosphere, leading to acid rain and disrupting the processes of photosynthesis near industrial enterprises already worries scientists. The amount of sulfur in the atmosphere increases significantly when fossil fuels are burned.

1.5. The phosphorus cycle.

This element is found in a number of vital molecules. Its cycle begins with the leaching of phosphorus-containing compounds from rocks and their entry into the soil. Part of the phosphorus is carried away to rivers and seas, while the other part is absorbed by plants. The biogenic turnover of phosphorus occurs according to the general scheme: reducers .®consumables®producers

Significant amounts of phosphorus are applied to the fields with fertilizers. About 60 thousand tons of phosphorus is annually returned to the mainland with fish catch. In the human protein diet, fish makes up from 20% to 80%, some low-value fish varieties are processed into fertilizers rich in useful elements, including phosphorus.

The annual production of phosphorus-containing rocks is 1-2 million tons. The resources of phosphorus-containing rocks are still large, but in the future, mankind will probably have to solve the problem of returning phosphorus to the biogenic cycle.

Organisms in an ecosystem are linked by a commonality of energy and nutrients, and it is necessary to clearly distinguish between these two concepts. The entire ecosystem can be likened to a single mechanism that consumes energy and nutrients to do work. Nutrients initially originate from the abiotic component of the system, to which they eventually return either as waste products or after the death and destruction of organisms. Thus, a constant cycle of nutrients occurs in the ecosystem, in which both living and non-living components participate. Such cycles are called biogeochemical cycles.

At a depth of tens of kilometers, rocks and minerals are exposed to high pressures and temperatures. As a result, metamorphism (change) of their structure, mineral, and sometimes chemical composition occurs, which leads to the formation of metamorphic rocks.

Sinking even further into the depths of the Earth, metamorphic rocks can melt and form magma. The internal energy of the Earth (i.e., endogenous forces) raises magma to the surface. With molten rocks, i.e. magma, chemical elements are carried to the surface of the Earth during volcanic eruptions, freeze in the thickness of the earth's crust in the form of intrusions. Mountain building processes raise deep rocks and minerals to the surface of the Earth. Here rocks are exposed to the sun, water, animals and plants, i.e. are destroyed, transported and deposited in the form of precipitation in a new place. As a result, sedimentary rocks are formed. They accumulate in the mobile zones of the earth's crust and, when bending down, again sink to great depths (over 10 km).

The processes of metamorphism, transfer, crystallization begin again, and chemical elements return to the surface of the Earth. This "route" of chemical elements is called the great geological cycle. The geological circulation is not closed, because some of the chemical elements come out of the cycle: they are carried away into space, are fixed with strong bonds on the earth's surface, and some come from outside, from space, with meteorites.

The geological cycle is the global travel of chemical elements within the planet. They make shorter trips on the Earth within its individual sections. The main initiator is living matter. Organisms intensively absorb chemical elements from soil, air and water. But at the same time they return them. Chemical elements are washed out of plants by rainwater, released into the atmosphere during respiration, and deposited in the soil after the death of organisms. The returned chemical elements are again and again involved in "travel" by living matter. All together and constitutes the biological, or small, cycle of chemical elements. He, too, is not closed.

Some of the elements - "travelers" are carried away from it with surface and ground waters, some for different times "turn off" from the cycle and stay in trees, soil, peat.

Another route of chemical elements runs from top to bottom from tops and watersheds to valleys and river beds, depressions, depressions. Chemical elements enter the watersheds only with atmospheric precipitation, and are carried down both with water and under the influence of gravity. Consumption of matter prevails over input, as evidenced by the very name of the watershed landscapes eluvial.

On the slopes, the life of chemical elements changes. Their speed of movement increases dramatically, and they "pass" the slopes, like passengers comfortably settled in a train compartment. Slope landscapes are called transit.

Chemical elements manage to "take a break" from the road only in accumulative (accumulating) landscapes located in relief depressions. They often remain in these places, creating good nutritional conditions for vegetation. In some cases, vegetation has to deal with an excess of chemical elements.

Man intervened in the distribution of chemical elements many years ago. Since the beginning of the twentieth century, human activities have become the main way of their travel. When minerals are mined, a huge amount of substances are removed from the earth's crust. Their industrial processing is accompanied by the release of chemical elements with production wastes into the atmosphere, water, and soil. This pollutes the habitat of living organisms. New areas with a high concentration of chemical elements, man-made geochemical anomalies, appear on the ground. They are common around the mines of non-ferrous metals (copper, lead). These areas sometimes resemble lunar landscapes, because they are practically devoid of life due to the high content of harmful elements in soils and waters. It is impossible to stop scientific and technological progress, but a person must remember that there is a threshold in the pollution of the natural environment, which cannot be crossed, beyond which human diseases and even the extinction of civilization are inevitable.

Having created biogeochemical "dumps", nature, perhaps, wanted to warn a person against ill-considered, immoral activities, to show him by an illustrative example, which leads to a violation of the distribution of chemical elements in the earth's crust and on its surface.

The possibility of our life, its conditions depend on natural resources. Biological and especially food resources serve as the material basis of life. Mineral and energy resources, included in production, serve as the basis for a stable standard of living.

Consuming natural resources intensively, a person needs to maintain natural balance. The balance of resources in the circulation of substances determines the stability of the biosphere.

2 Environmental factors and their description.

2.1. Habitat and classification of environmental factors.

Under habitat understand the totality of external natural conditions and phenomena in which living organisms are immersed, and with which these organisms are in constant interaction.

In bioecology, we are usually talking about a natural environment that has not been changed by humans. In applied (social) ecology, one speaks of the environment, one way or another mediated by man.

Individual elements of the habitat, to which organisms react with adaptive reactions (adaptations), are called ecological factors or environmental factors. Among environmental factors, there are usually three groups of factors: abiotic, biotic and anthropogenic.

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

2. Biotic environmental factors is called the totality of the influences of some organisms on others. Living things can serve as a source of food for other organisms, be their habitat, promote their reproduction, etc. The action of biotic factors can be not only direct, but also indirect, expressed in the correction of abiotic factors, for example, changes in the composition of the soil, microclimate under the forest canopy, etc.

ABIOTIC	BIOTIC
Physical climatic - moisture, light, temperature, wind, pressure, currents, duration of the day	The influence of plants on each other and on other organisms in the biocenosis (directly or indirectly)
Physical edaphic- moisture capacity, heat supply, mechanical composition and soil permeability	The influence of animals on each other and on other organisms in the biocenosis
Chemical- air composition, content of nutrients in soil or water, salinity of air and water, pH reaction	Anthropic Factors - All Human Activities

3. Anthropogenic environmental factors is called the totality of human influences on living organisms. This influence can also be direct, for example, when a person cuts down a forest or shoots animals, or indirect, manifested in a person's influence on abiotic and biotic environmental factors, for example, a change in the composition of the atmosphere, soil, hydrosphere, or a change in the structure of ecosystems.

3.1. Solar radiation

Solar radiation is the main source of energy for the ecosystem. It is a great blessing for all living things and at the same time a factor that sets a rigid framework for its existence.

Direct or scattered solar radiation is not required only for a small group of living creatures - some types of fungi, deep-water fish, soil microorganisms, etc.

The most important physiological and biochemical processes carried out in a living organism due to the presence of light include the following (according to N. Green et al., 1990):

1. Photosynthesis (1-2% of the solar energy falling on the Earth is used for photosynthesis);

2. Transpiration (about 75% - for transpiration, which provides cooling of plants and movement of aqueous solutions of mineral substances along them);

3. Photoperiodism (provides synchronization of life processes in living organisms with periodically changing environmental conditions);

4. Movement (phototropism in plants and phototaxis in animals and microorganisms);

5. Vision (one of the main analyzing functions of animals);

6. Other processes (synthesis of vitamin D in humans in the light, pigmentation, etc.).

The basis of biocenoses in central Russia, like most terrestrial ecosystems, are producers. Their use of sunlight is limited by a number of natural factors and, first of all, by temperature conditions. In this regard, special adaptive reactions were developed in the form of layering, mosaicism of leaves, phenological differences, etc. According to the requirements for lighting conditions, plants are divided into light or light-loving (sunflower, plantain, tomato, acacia, melon), shade or non-light-loving (forest grasses, mosses) and shade-tolerant (sorrel, heather, rhubarb, raspberry, blackberry).

Plants form the conditions for the existence of other types of living creatures. That is why their reaction to lighting conditions is so important. Environmental pollution leads to a change in illumination: a decrease in the level of solar insolation, a decrease in the amount of photosynthetically active radiation (PAR-part of solar radiation with a wavelength of 380 to 710 nm), a change in the spectral composition of light. As a result, this destroys cenoses based on the arrival of solar radiation in certain parameters.

3.2. Temperature.

For the natural ecosystems of our zone, the temperature factor, along with light supply, is decisive for all life processes. Population activity depends on the time of year and time of day. each of these periods has its own temperature conditions.

Individuals of many species are not able to maintain a constant body temperature and in the cold season or day they reduce the level of life processes up to suspended animation. This primarily concerns plants, microorganisms, fungi and poikilothermic (cold-blooded) animals. Only homeothermic (warm-blooded) species remain active. Heterothermic organisms, being in an inactive state, have a body temperature not much higher than the temperature of the external environment; in the active state it is rather high (bears, hedgehogs, bats, ground squirrels).

Thermoregulation of homeothermic animals is provided by a special type of metabolism, which occurs with the release of heat in the body of animals, the presence of heat-insulating covers, size, physiology, etc.

As for plants, they have developed a number of properties in the process of evolution:

1. Cold resistance - the ability to withstand low positive temperatures for a long time (from OoC to + 5oC);

2. Winter hardiness - the ability of perennial species to endure a complex of unfavorable winter conditions;

3. Frost resistance - the ability to withstand negative temperatures for a long time;

4. Anabiosis - the ability to endure a period of long-term lack of environmental factors in a state of a sharp decrease in metabolism;

5. Heat resistance - the ability to withstand high (over + 38o ... + 40oC) temperatures without significant metabolic disorders;

6. Ephemerality - reduction of ontogenesis (up to 2-6 months) in species growing in a short period of favorable temperature conditions.

7. Resistance to changes in temperature conditions.

Thermal pollution of the environment leads to a shift in the phenological phases of the development of living organisms or to abnormal changes at certain stages of ontogenesis. As a result, a number of populations do not have time or cannot produce full-fledged offspring, some do not have time to prepare for a period of unfavorable conditions and die. Global warming of the climate by + 0.5 ... 1.5оС, in the opinion of most experts, will lead to catastrophic consequences for the biosphere.

3.3 Humidity.

The conditions of moisture supply in our zone are quite favorable for the existence of organisms. Most of living things are 70-95% water. Water is needed for all biochemical and physiological processes. Therefore, it is so important for the biocenoses of all ecosystems.

The availability of moisture in different periods of the year and day is different. In the process of evolution, living organisms have adapted to regulate the level of water consumption and maintain the optimal composition of the internal environment.

In relation to the water regime, the following ecological groups of living beings are distinguished:

1. Hydrobionts - inhabitants of ecosystems, the entire life cycle of which takes place in water;

2. Hygrophytes - plants of humid habitats (marsh marigold, European swimsuit, broad-leaved cattail);

3. Hygrophiles - animals that live in very damp parts of ecosystems (molluscs, amphibians, mosquitoes, wood lice);

4. Mesophytes - plants of moderately humid habitats;

5. Xerophytes - plants of dry habitats (feather grass, wormwood, astrogals);

6. Xerophiles - inhabitants of arid areas that do not tolerate increased moisture (some species of reptiles, insects, desert rodents and mammals).

7. Succulents - plants of the most arid habitats, capable of accumulating significant reserves of moisture inside the stem or leaves (cacti, aloe, agave);

8. Sclerophytes - plants in very arid areas that can withstand severe dehydration (common camel thorn, saxaul, saxagyz);

9. Ephemeres and ephemeroids are annual and perennial herbaceous species with a shortened cycle that coincides with a period of sufficient moisture.

The moisture consumption of plants can be characterized by the following indicators:

1. Drought resistance - the ability to withstand reduced atmospheric and (or) soil drought;

2. Moisture resistance - the ability to withstand waterlogging;

3. Coefficient of transpiration - the amount of water consumed for the formation of a unit of dry weight (for white cabbage 500-550, for pumpkin-800);

4. Coefficient of total water consumption - the amount of water consumed by the plant and soil to create a unit of biomass (for meadow grasses - 350-400 m3 of water per ton of biomass);

Violation of the water regime, pollution of surface waters is dangerous, and in some cases destructive for cenoses. Changes in the water cycle in the biosphere can lead to unpredictable consequences for all living organisms.

3.4. Air-gas mode

The Earth's atmosphere has a fairly stable composition. 21% of oxygen in the surface air layer provides full respiration for all organisms in natural ecosystems. 0.03% carbon dioxide is enough for the photosynthetic reactions of plants. The horizontal and vertical movement of air masses creates the necessary air exchange for all inhabitants of the ecosystem - from soil microorganisms to insects and birds.

The air-gas regime can be disturbed in natural conditions very rarely (for example, during a volcanic eruption), in anthropic conditions - quite often. The main air pollutants in our conditions are carbon monoxide, sulfur dioxide, nitrogen dioxide, formaldehyde, dust. Hindering photosynthesis, respiration, and many other physiological processes, and in some cases modifying them, atmospheric pollution suspends or stops the growth and development of living organisms, leading in some cases to their death.

Abiotic environmental factors will only fully play their ecological role when the consequences of human activity are within the biosphere's ability to self-purify and self-heal.

General patterns of joint action of factors on organisms

4.1. The concept of the optimum

Each organism, each ecosystem develops under a certain combination of factors: moisture, light, heat, availability and composition of nutrient resources. All factors act on the body at the same time. For each organism, population, ecosystem, there is a range of environmental conditions - a range of stability (Fig. 1), within which the vital activity of objects occurs.

In the process of evolution, organisms have formed certain requirements for environmental conditions. Doses of factors at which an organism, population or biocenosis achieve the best development and maximum productivity correspond to the optimum conditions. With a change in this dose towards a decrease or increase, the organism is suppressed, and the stronger the deviation of the values ​​of the factors from the optimum, the greater the decrease in viability, up to the death of the organism or destruction of the biocenosis. Conditions under which vital activity is maximally depressed, but the organism and biocenosis still exist, are called pessimal.

EXAMPLE. In the north, the limiting factor is heat, in the south - moisture availability. In the Far North, the most productive Cajander larch forests grow in the floodplains of rivers - a favorable hydrothermal regime develops here and soils are regularly replenished with nutrients during floods. The most low-productive forests - from the same larch, but with a cover of sphagnum mosses, are formed on the northern slopes of the mountains in conditions of constant waterlogging and cold soils. The level of permafrost under the moss cover does not drop below 30 cm. In South Primorye, optimal forest growing conditions are characteristic of the northern slopes in their middle part, and pessimal ones are characteristic of dry southern slopes with a convex surface.

There are many examples of optima and pessimums in plants, animals and their communities in relation to light, moisture, heat supply, soil salinity, and other factors.

4.2. The concept of tolerance

For different species of plants and animals, the limits of the conditions in which they feel good are not the same. For example, some plants prefer very high humidity, while others prefer arid habitats. Some species of birds fly away to warmer climes, others - crossbills, nutcrackers and chicks hatch in winter. The wider the quantitative limits of environmental conditions under which this or that organism, species and ecosystem can exist, the higher the degree of their endurance, or tolerance. The property of species to adapt to environmental conditions is called environmental plasticity(Fig. 2), and the ecological valence of the species is judged by the amplitude of the natural fluctuations of the factor carried by the populations.

Species with narrow ecological plasticity, i.e. able to exist in conditions of a slight deviation from their optimum, highly specialized, are called stenobiontic(stenos - narrow), species are widely adapted, able to exist with significant fluctuations in factors - eurybiontic(eurys - wide) The boundaries beyond which existence is impossible are called the lower and upper limits of endurance, or ecological valence.

EXAMPLE. Fish of salt and fresh water bodies are stenobionts. Three-spined stickleback and salmon are eurybionts. Stenobionts-plants: chozenia, Korean poplar - floodplain plants, hygrophytic plants (marsh marigold, cattail,), xerophytes of Primorye - dense-flowered pine, Manchurian apricot, Lespedeza, etc. Almost all mammals, including humans, can be attributed to stenobionts. A small deviation of the temperature of air (22-26 ° C) and water (28-38 ° C) from the "normal" value, a reduced oxygen content and an increased content harmful substances(chlorine, mercury vapor, ammonia, etc.) in the air to cause a sharp deterioration in its condition.

In relation to one factor, the species may be. stenobiont, in relation to the other - eurybiont. Depending on this, directly opposite pairs of species are distinguished: stenothermal - eurythermal (in relation to heat), stenohydric - euryhydric (to moisture), stenohydric - euryhalenic (to salinity), steno- eurythotic (to light), etc.

There are other terms that describe the relationship of species to environmental factors. The addition of the ending "phyle" (phyleo (Greek) - love) means that the species has adapted to high doses of the factor (thermophil, hygrophil, oxyphil, gallophil, chionophil), and the addition of "phob", on the contrary, to low doses (gallophobe, chionophobe) ... Instead of "thermophobe", "cryophile" is usually used, instead of "hygrophobe" - "xerophile".

Typical eurybionts are protozoa, fungi. From higher plants species of temperate latitudes can be attributed to eurybionts: Scots pine, Daurian larch, Mongolian oak, Schwerin's willow, lingonberry and most of the heather species.

Stenobionism is developed in species that develop for a long time under relatively stable conditions. The more pronounced it is, the smaller the range of the species, or its community. The most common species have a wide range of tolerance to all factors. They are called cosmopolitans. But there are few such species.

There is no such place in nature where one factor acts on the organism. All factors act simultaneously and the combination of these actions is called a constellation. The values ​​of the factors are not always equal. They may all be insufficient, and then a general suppression of the biota is observed (weak development of vegetation cover, a decrease in productivity, a change in the fractional structure of biomass, a change in other indicators of ecosystems), but more often some of them are in abundance, even at the optimum, while others are in short supply. In this case, the constellation is not a simple sum of the influence of factors, since the degree of influence of some factors on organisms and populations depends on the degree of influence of other factors.

EXAMPLE. With optimal heat supply, the tolerance of plants and animals to a lack of moisture and nutrition increases, and a lack of heat is accompanied by a decrease in the need for moisture and an increased need for nutrients. Moreover, this is observed in both plants and animals. In plants with a lack of heat and waterlogged soil, nutrients become physiologically inaccessible, and to ensure tolerance, it is required increased fertility soil. Also in animals - in order to strengthen the protective functions of the body in the cold, you need to eat well. So, always before lying in a den, a bear accumulates subcutaneous fat. Gas exchange reactions in fish are not the same in water of different salinity. In beetles of the genus Blastophagus, the response to light depends on temperature. At a temperature of 25 ° C, they creep into the light (positive phototropism), when it decreases to 20 ° C or increases to 30 ° C, the reaction is neutral, and at values ​​below and above these limits, they hide.

However, the compensatory capabilities of the factors are limited. It is impossible to completely replace one factor with another, and if the value of at least one of the factors goes beyond the upper or lower limits of the endurance of the biota component, the existence of the latter becomes impossible, no matter how favorable the other factors are.

EXAMPLE. Normal survival of sika deer in Primorye takes place only in oak forests on the southern slopes, because here the thickness of the snow is insignificant and provides the deer with a sufficient food supply for the winter. The limiting factor for the deer is deep snow. The lack of heat limits the distribution to the north of most species and formations of the Manchurian flora: pine forests of dense-flowered pine, whole-leaved fir and its formations are common only in southern Primorye. Larch dominates everywhere in the permafrost zone. For dwarf pine and Kamchatka alder, the decisive factors of distribution are high humidity air and winter conditions. They tolerate frosty winters well only in the presence of a powerful snow cover, which protects the shoots from drying out and frostbite by the winter monsoons of the Far East. These species form thickets only in the coastal regions of the Okhotsk and Bering Seas, and in the continental regions - in the subalpine belt at an altitude of at least 1000 m / a.m. In the early stages of development, excess light may be the limiting factor in conifers. All of them, even the grave pine, require shading in the first years of life.

In the middle of the 19th century (1846), the German agrochemist Liebig deduced the "law of minimum". In an experiment with mineral fertilizers, he found that the factors that are at a minimum in a given habitat have the greatest influence on the endurance of plants. He wrote in 1955: "Elements that are completely absent or not in the right amount prevent other nutrient compounds from exerting their effect or reduce their nutritional effect." This is true not only for food elements, but also for other vital factors. Liebig's law is applicable only under conditions of a stationary state of the ecosystem, i.e. when the inflow of matter and energy into the system is balanced by their outflow.

The factor, the level of which is close to the endurance limits of a particular organism, species and other components of the biota, is called limiting. And it is to this factor that the body adapts (develops adaptations) in the first place. The law of limiting, or limiting, factors applies not only to the situation when these factors are at the "minimum", but also at the "maximum", that is, they go beyond the upper limit of the organism's (ecosystem) endurance.

Under pessimal conditions, there are several limiting factors and their general suppressive effect may be higher than the total suppressive effect of individual factors.

EXAMPLE with southern slopes - insolation increases the dryness of the environment, prevents an increase in soil fertility.

Often the limiting factor is at one of the stages of development of the species. As you know, juveniles are the most vulnerable and for them the limiting factors may be. several. In different geographic zones, the limiting factors are different: in the Far North, it is often warm, in the southern regions, moisture. Different species react differently to the same factor. According to the reaction of their adults to a particular factor, it is possible to construct an ecological series (in decreasing or increasing order of the effect of the factor).

EXAMPLE of an ecological range of tree species in terms of shade tolerance: larch - white birch - aspen - willows - linden - oak - Daurian birch - ash - maples - alder - elm - hornbeam - spruce - cedar - fir. The ecological range of forest types (in terms of heat supply): larch (L.) herbaceous - L. green moss - L. cowberry - L. sphagnum (Fig. 3). The ecological range of forest types (in terms of moisture): elm (or ash) large-herb-fern - oak forest (D.) with birch forbs - D. sedge - D. rhododendron sedge - D. mariannikov-sedge - D. sedge rare-cover (Fig. 4 ).

Within the population, it is also possible to identify individuals most and least sensitive to the same factor. This is due to a combination of hereditary (genetic) and acquired (phenotypic) characteristics of organisms. Due to ecological individuality in populations there are individuals of different viability. The most viable ones survive periods of unfavorable conditions, contributing to the preservation of the species in extreme conditions.

4.5. Preceding rule V.V. Alekhina

The botanist has installed you. You. Alekhine (1951). The same communities are zonal in one zone, and extrazonal in others. In the second case, outside the northern boundaries of the range, they occupy the most favorable habitats for themselves, outside the southern boundaries - the least favorable. This is especially evident on the northern and southern slopes of the forest zone. On the cold northern slopes in the Magadan region, larch openings with a sphagnum cover grow, and on the warm southern slopes - larch moss-lichen sparse forests (Chukotka) and birch forb forests (Northern Okhotsk Sea). In the southwestern regions of Primorye, the northern slopes are occupied by moist coniferous-deciduous forests, and the southern slopes are occupied by dry oak forests with rare interspersed pine forests from dense-flowered (burial) pine and apricots, on the very outskirts - turning into forest-steppe communities.

The revealed regularity is of great importance, since makes it possible to accurately describe the vegetation of areas not yet studied and to reconstruct its former appearance in places where it was destroyed.

Station - the habitat of a population of a species, which is characterized by ecological conditions that meet the requirements of the species. Each species has its own set of stations. Within one zone and time period, the species occupies one station. With the transition to another zone or with the transition to another age stage, the species can change stations. The rule of zonal change of habitats was established by the entomologist Grieg. Yakovl. Bey-Bienko (1966). In the northern regions, many species of insects usually behave like hygrophobes, occupying drier areas with a thinner cover, and in the southern regions they are also hygrophytes, settling in humid, shady places with dense vegetation (migratory locust). Another example - lazy ants (Lasius niger, L. flavus) in wet meadows inhabit hummocks, and in dry meadows - in the steppe, prefer more humid habitats. Zonal change of habitats is also typical for plants.

So, dwarf cedar in South Primorye grows only in the subalpine zone at an altitude of 1000-1100 m to 1400-1600 m above sea level, moving to the north, it goes down and forms a dense undergrowth in valley larch forests. North of 60 ° N. - on South Chukotka and the Okhotsk coast, the eastern and southeastern slopes and foothills of mountains and hills are occupied by continuous thickets of dwarf cedar.

4.7. The rule of zonal change of longlines M.S. Gilyarova

In different zones, the same species occupy different tiers. When moving to the north, they naturally move from the upper tiers to the lower, warmer ones, and some also to the soil. This set the soil. zoologist Merkur. Serg. Gilyarov.

EXAMPLE. The larvae of the stag beetle (Lucanus cervus) in the forest zone develop in decaying wood waste and stumps, and in the steppe, they live in rotten roots at a depth of 1 m.

In addition to the zonal (spatial) change of habitats, there are also temporary changes: seasonal (during the month and even one day with fluctuations in the microclimate - during periods of droughts or typhoons, insects and rodents either hide under the protection of crowns of shrubs and trees, then get out to open places) and annual (if weather conditions deviate from the average annual norms). Due to the change of habitats, the species retain their ecological status in constantly changing conditions. At the same time, with successful dispersal, they occupy new habitats, and even change them. As a result, the ecology and physiology of individuals and populations begins to change. In such cases, the change of stations becomes one of the leading factors of evolution.

The principle of stationary fidelity and the opposite principle of zonal and vertical change of habitats indicate the complex relationships of organisms with the environment. Their study is very important for understanding the ecology of species, as the basis for the protection of rare and useful and the fight against harmful species.

5. The ecological significance of abiotic factors

In different environmental conditions, biological processes proceed at different rates. For example, the growth of many plants depends on the concentration of various substances (water, carbon dioxide, nitrogen, hydrogen ions).

The example of temperature shows that this factor is tolerated by the body only within certain limits. The body dies if the temperature of the environment is too low or too high. In an environment where temperatures are close to these extreme values, living inhabitants are rare. However, their number increases as the temperature approaches the average value, which is the best (optimal) for a given species.

Tolerance (from the Greek for tolerance - patience) the ability of organisms to withstand changes in living conditions (fluctuations in temperature, humidity, light). For example: some die at a temperature of 50 °, while others withstand boiling.

In different environmental conditions, biological processes in organisms proceed at different rates. For example, the growth of many plants depends on the concentration of various substances (water, carbon dioxide, nitrogen, hydrogen ions).

It is possible that it is precisely in tolerance that the salvation of nature from too unreasonable human influence will consist. In addition, there are still places on Earth that are relatively little influenced by humans. Therefore, by the time a person creates unbearable conditions for himself, some kind of life will remain and continue evolution, unless a person blows the planet to shreds as a result of an atomic catastrophe. There are also plants that produce substances that cause their own death.

Organisms with a wide range of tolerance are denoted by the prefix "eury-". Eurybiont is an organism that can live under various environmental conditions. For example: eurythermal is an organism that tolerates wide temperature fluctuations. Organisms with a narrow tolerance range are denoted by the prefix "steno-". Stenobiont is an organism that requires strictly defined environmental conditions. For example: trout is a stenothermic species, and perch is an eurythermal species. Trout cannot tolerate large fluctuations in temperature, if all the trees along the banks of a mountain stream disappear, this will lead to a temperature rise of several degrees, as a result of which the trout will die, and the perch will survive.

When the body is placed in new conditions, after a while it gets used to it, adapts. This leads to a shift in the tolerance curve and is called adaptation or acclimatization. For the normal development of organisms, the presence of various factors of a strictly defined quality is necessary, each of them must be in a certain amount. In accordance with the law of tolerance, an excess of a substance can be as harmful as a deficiency, that is, everything is good in moderation. For example: the crop can die in both dry and too rainy summers.

Minimum law.

The intensity of certain biological processes is often sensitive to two or more environmental factors. In this case, the decisive importance will belong to such a factor, which is available in the minimum, from the point of view of the needs of the organism, quantity. This rule was formulated by the founder of the science of mineral fertilizers Justus Liebig (1803-1873) and received the name of the law of minimum. J. Liebig discovered that the yield of plants can be limited by any of the basic nutrients, if only this element is in short supply.

Moreover, according to the law of minimum, the deficiency of any one substance is not compensated by the excess of all the others. If the soil contains a lot of nitrogen, potassium and other nutrients, but not enough phosphorus (or vice versa), the plants will develop normally only until they have absorbed all the phosphorus.

The factors that restrain the development of organisms due to lack or excess in comparison with the needs are called limiting.

The provision on limiting factors greatly facilitates the study of complex situations. For all the complexity of the relationship between organisms and their habitat, not all factors have the same ecological significance. For example, oxygen is a factor of physiological necessity for all animals, but from an ecological point of view, it becomes limiting only in certain habitats. If a fish dies in the river, then the oxygen concentration in the water should be measured first, since it is highly variable, oxygen reserves are easily depleted, and it is often not enough. If the death of birds is observed in nature, it is necessary to look for another reason, since the oxygen content in the air is relatively constant and sufficient in terms of the requirements of terrestrial organisms.

6. Adaptation of living organisms to environmental conditions.

According to Charles Darwin's theory, organisms are changeable. It is impossible to find two absolutely identical individuals of the same species. These differences are partly inherited. All this is easily explained from the point of view of genetics. Each species and each population is saturated with various mutations, that is, changes in the structure of organisms caused by corresponding changes in chromosomes that occur under the influence of factors of the external or internal environment. These changes in the characteristics of the organism are of a spasmodic nature and are inherited. In the overwhelming majority, these mutations are, as a rule, unfavorable, therefore, almost all of them are recessive, that is, their manifestations disappear after a certain number of generations. However, this entire set of changes is a reserve of heredity, the gene pool of a species or population, which can be mobilized through natural selection when the conditions of existence of populations change.

If a population lives in relatively constant conditions, then almost all mutations are cut off by natural selection, which in this case is called stabilizing... Only mutations are fixed, leading to less variability of traits, as well as mutations that contribute to saving energy by getting rid of functions that have become "superfluous" under unchanged conditions. This promotes the formation of stenobionts. Often, stabilizing selection leads to degeneration, that is, evolutionary changes associated with a simplification of the form of organization, usually accompanied by the disappearance of some organs that have lost their meaning. So the whales lost their hind limbs, the lancelet does not have its own digestive organs, etc. In exchange for the lost, new organs can be acquired.

When environmental conditions change, environmental pressure is formed on the population, while the greatest chances of survival are received by carriers of such mutations who “guessed” such changes that are more favorable for new environmental conditions than the original forms. It is they that give the greatest offspring, in which there is an even greater refinement of the forms that satisfy the new state of the environment. As a result, with each new generation, the forms gradually change. This natural selection is called driving.

Minor evolutionary changes that contribute to better adaptation to certain environmental conditions are called ideoadaptation. These are various kinds of particular adaptations: protective coloration, flat shape of benthic fish, adaptation of seeds to dispersal, degeneration of leaves into spines to reduce transpiration, etc. By ideoadaptation, usually small systematic groups arise: species, genus, families.

More significant evolutionary changes that are not adaptations to individual environmental factors, leading to significant changes in life forms, giving rise to new orders, classes, types, etc., are called aromorphosis. An example of aromorphosis is the emergence of ancient fish on land and the formation of a class of amphibians. The consequences of aromorphosis are also the emergence of such qualities of living beings as the psyche and consciousness. Aromorphosis marks major revolutionary changes in the structure of the biosphere, apparently caused by global changes in the environment.

Reasoning by the principle of analogy, we can assume that just as the environment affects us, forcing us to look for ways to adapt to it, we can also affect the cells of our organisms, as a supersystem, forcing them to adapt to external conditions for them in the same ways, which we expect from them and which for some reason we need. For example, we begin to regularly load our muscles, and our muscle tissue adapting to new conditions, in response to these loads, they begin to grow and get stronger. The impact can also occur along a more complex chain, for example, in the event of a fright, adrenaline is released into our blood, forcing all cells to go into a stressful, that is, more active, state, using their reserves for this, which gives the whole body additional strength to overcome external danger ... Thus, the mechanism for influencing internal subsystems by changing environmental factors for these subsystems is, apparently, a fairly universal mechanism for influencing any supersystem on its internal organization.

Most likely, the intracellular level is no exception. If a cell of our body gets into altered conditions, and these changes are either fixed or periodically repeated, then the cell tries to adapt to new conditions, changing its structure accordingly, that is, changing the intracellular environment, thereby affecting the organelles inhabiting it, including and on chromosomes, which are also probably forced to adapt to conditions external to them. It is possible that under certain influences on the body, almost the entire genetic apparatus in all cells is exposed to a certain effect, which leads to quite unambiguous changes in the structure of chromosomes. It means that the external environment can directly affect our genetic apparatus.

That is, the mutations that we talked about may not turn out to be random at all, but completely directed. Then the theory of natural selection takes on a slight adjustment: among the mutations present in the population under a specific change in environmental conditions, those that are directly initiated by this particular change prevail... That is, the mutations themselves are, apparently, directed and designed to find new forms that meet the requirements of the changed environment. And since the response of life to external changes, as we have already said, obeying the principle of optimality, turns out to be quite unambiguous, it is possible that a specific mutation of any sign is of a chain nature. That is, having once emerged in the offspring of one pair, a successful mutation turns out to be “infectious” for other pairs of parents giving their offspring, but with the same successful mutations. As a result, within a single generation within the framework of a species, different parents may have children with the same traits that differ from the traits of their parents, thereby forming a completely new subspecies. And then it is already useless to look for some intermediate links. A new subspecies (and subsequently a new species) appears immediately, practically at the same time, and immediately turns out to be represented by a sufficiently large number of individuals for sustainable reproduction. True, so far this is only a hypothesis.

Such processes appear, apparently, in the very periods of serious environmental changes that threaten the extinction of this species. It is then that a "whorl" is formed, that is, a huge number of mutations are born, the purpose of which is to find the right solution, a new form. And this solution will surely be found, because, as we have already said, for this life uses the “technique of probing,” which is “a specific and irresistible weapon of any expanding multitude” (Teilhard de Chardin's terminology). Mutations fill all possible space of variants of new forms, and then the environment itself determines which of these forms will be fixed in life and which will disappear without passing the test of natural selection. Sometimes such a whorl gives rise to a whole bunch of new phyla, that is, evolutionary branches that are different responses to the same environmental change.

The adaptation of organisms to environmental factors is caused not only by evolutionary rearrangements taking place in the biosphere. Organisms often use the natural orientation and frequency of these factors to distribute their functions over time and program their life cycles in order to make the best use of favorable conditions. Through the interaction between organisms and natural selection, the entire community becomes programmed for all sorts of natural rhythms. In these cases, environmental factors act as a kind of synchronizers of processes in the biosphere.

According to the degree of direction of action, environmental factors can be classified as follows:

1) periodic factors (daily, annual, etc.);

2) recurring without strict periodicity (floods, hurricanes, earthquakes, etc.);

3) factors of unidirectional action (climate change, waterlogging, etc.);

4) random and uncertain factors, the most dangerous for the body, as they often occur for the first time.

In the best way, living organisms manage to adapt to periodic and unidirectional factors, characterized by certainty of actions, therefore, amenable to unambiguous decoding. That is, the requirement of the supersystem in this case is quite understandable.

A particular case of such adaptations to repetitive factors is, for example, photoperiodism - this is the body's response to the length of daylight hours in the temperate and polar zones, which is perceived as a signal for a change in the phases of development or behavior of organisms. Examples of photoperiodism are such phenomena as leaf fall, animal molt, bird migration, etc. With regard to plants, usually short-day plants that exist in southern latitudes, where with a long growing season, the day is relatively short, and long-day plants typical for northern latitudes, where the day is longer with a short growing season, are distinguished.

Diurnal rhythm is another example of adaptation to the periodicity of natural phenomena. For example, in animals, with the change of day and night, the respiration intensity, heart rate, etc. change. For example, gray rats are more labile in their diurnal rhythm than black rats, so they more easily explore new territories, having populated almost the entire globe.

Seasonal activity is another example. This is not necessarily a change of seasons, but also a change, for example, of the doge and drought season, etc.

Also interesting are adaptations to the tidal rhythm, which is associated with both solar and lunar days (24 hours 50 minutes). Daily ebb and flow are shifted by 50 minutes. The strength of the tides changes during the lunar month (29.5 days). During the new and full moon, the tides reach their maximum. All these features leave an imprint on the behavior of organisms in the littoral (intertidal zone). For example, some fish lay eggs at the border of the maximum tide. The release of fry from eggs is dated to the same period.

Many rhythmic adaptations are inherited even when animals move from one zone to another. In such cases, the entire life cycle of the organism can be disrupted. For example, ostriches in Ukraine can lay their eggs right on the snow.

The mechanisms for adapting to the periodicity of processes can be the most unexpected. For example, in some insects, a kind of birth control is based on photoperiodism. Long days in late spring and early summer cause the formation of a neurohormone in the ganglion of the nerve chain, under the influence of which resting eggs appear, giving larvae only next spring, no matter how favorable the feeding and other conditions are. Thus, population growth is inhibited even before food supplies become the limiting factor.

Adaptation to factors that are repeated without strict periodicity is much more difficult. Nevertheless, the more characteristic this factor is for nature (for example, fires, strong storms, earthquakes), the more specific adaptation mechanisms find life for them. For example, unlike the length of the day, the amount of precipitation in the desert is completely unpredictable, nevertheless, some annual plants deserts usually use this fact as a regulator. Their seeds contain an inhibitor of germination (inhibitor - a substance that inhibits processes), which is washed out only by a certain amount of precipitation, which will be enough for the full life cycle of a given plant from germination of a seed to the maturation of new seeds.

Plants have also developed special adaptations to forest fires. Many plant species put more energy into underground storage organs and less energy into reproductive organs. These are the so-called “recovering” species. Species “dying at maturity,” on the other hand, produce numerous seeds that are ready to germinate immediately after a fire. Some of these seeds lie in the forest floor for decades without germinating or losing germination.

Factors of undetermined action are the most dangerous for living organisms. Natural systems have the ability to recover well from acute stresses such as fires and storms. Moreover, many plants even need random stresses to maintain a “vitality” that increases the stability of existence. But subtle chronic disorders, especially characteristic of anthropogenic influence on nature, give weak reactions, so they are difficult to track, and most importantly, it is difficult to assess their consequences. Therefore, adaptations to them are formed extremely slowly, sometimes much slower than the accumulation time of the consequences of chronic stress beyond the limits, after which the ecosystem collapses. Especially dangerous industrial waste containing new chemical substances that nature has not yet encountered. Thermal pollution of the environment is one of the most dangerous stressors. A moderate rise in temperature can have a positive effect on life, but after a certain limit, stressful effects begin to manifest. This is especially noticeable in reservoirs directly related to thermal power plants.

Ecological valence, the degree of adaptability of a living organism to changes in environmental conditions. Ecological valence is a specific property. Quantitatively, it is expressed by the range of changes in the environment, within which given view maintains normal vital activity. Ecological valence can be considered both in relation to the reaction of a species to individual environmental factors, and in relation to a complex of factors. In the first case, the species that endure wide changes in the strength of the influencing factor are designated by the term consisting of the name of this factor with the prefix "eury" (eurythermal - in relation to the effect of temperature, euryhaline - to salinity, eurybate - to depth, etc.); species adapted to only small changes in this factor are designated by a similar term with the prefix "steno" (stenothermic, stenohaline, etc.). Species that have a wide ecological valence in relation to a complex of factors are called eurybionts, in contrast to stenobionts, which have little adaptability. Since eurybionticity makes it possible to settle in various habitats, and stenobionticity sharply narrows the range of sites suitable for the species, these two groups are often called eury or stenotopic, respectively.

Man's pressure on the environment already exceeds all conceivable limits. But it also grows every year.

7. Biotic factors and their description.

The most important biotic factors include food availability, food competitors, and predators.

1. General pattern of action of biotic factors

The living conditions of organisms play an important role in the life of each community. Any element of the environment providing direct impact on a living organism is called an environmental factor (for example, climatic factors).

Distinguish between abiotic and biotic environmental factors. Abiotic factors include solar radiation, temperature, humidity, illumination, soil properties, and water composition.

Food is considered an important ecological factor for animal populations. The quantity and quality of food affects the fertility of organisms (their growth and development), life expectancy. It has been established that small organisms need more food per unit mass than large ones; warm-blooded - more than organisms with variable body temperature. For example, the blue tit with a body weight of 11 g needs to consume food annually in the amount of 30% of its mass, a songbird with a weight of 90 g - 10%, and a buzzard with a weight of 900 g - only 4.5%.

Biotic factors include various relationships between organisms in a natural community. There are relationships between individuals of the same species and individuals of different species. The relationship between individuals of the same species is of great importance for its survival. Many species can reproduce normally only when they live in a fairly large group. So, a cormorant lives and reproduces normally if there are at least 10 thousand individuals in its colony. The principle of minimum population size explains why rare species are difficult to save from extinction. For the survival of African elephants, the herd must be at least 25 individuals, and the reindeer must be 300-400 heads. Living together makes it easier to find food and fight enemies. So, only a pack of wolves can catch large prey, and a herd of horses and bison can successfully defend against predators.

At the same time, an excessive increase in the number of individuals of one species leads to overpopulation of the community, aggravation of competition for territory, food, and leadership in a group.

Population ecology studies the relationships between individuals of the same species in a community. The main task of population ecology is to study the number of populations, its dynamics, the causes and consequences of changes in numbers.

Populations of different species, living together for a long time in a certain area, form communities, or biocenoses. A community of different populations interacts with environmental factors, together with which it forms a biogeocenosis.

The limiting, or limiting, environmental factor, that is, the lack of one or another resource, has a great influence on the existence of individuals of the same and different species in the biogeocenosis. For individuals of all species, the limiting factor can be low or high temperature, for the inhabitants of aquatic biogeocenoses - water salinity, oxygen content. For example, the spread of organisms in the desert is limited high temperature air. Applied ecology studies the limiting factors.

For human economic activity, it is important to know the limiting factors that lead to a decrease in the productivity of agricultural plants and animals, to the destruction of insect pests. So, scientists have found that the limiting factor for the larvae of the click beetle is very low or very high soil moisture. Therefore, to combat this pest of agricultural plants, drainage or strong soil moistening is carried out, which leads to the death of the larvae.

Ecology studies the interaction of organisms, populations, communities with each other, the impact of environmental factors on them. Autecology studies the relationship of individuals with the environment, and synecology - the relationship of populations, communities and habitat. Distinguish between abiotic and biotic environmental factors. Limiting factors are important for the existence of individuals and populations. Population and applied ecology has developed greatly. Achievements of ecology are used to develop measures for the protection of species and communities in agricultural practice.

Classification of biotic interactions:

1. Neutralism - no one population influences another.

2. Competition is the use of resources (food, water, light, space) by one organism, which thereby reduces the availability of this resource for another organism.

Competition is intraspecific and interspecific.

If the population size is small, then intraspecific competition is weakly expressed and resources are abundant.

With a high population density, intense intraspecific competition reduces the availability of resources to a level that inhibits further growth, thereby regulating the population size. Interspecies competition is the interaction between populations that adversely affects their growth and survival. When the Caroline squirrel was imported to Britain from North America, the abundance of the common squirrel decreased, because

Caroline protein was found to be more competitive. Competition is direct and indirect. Direct is intraspecific competition associated with the struggle for habitat, in particular, the protection of individual sites in birds or animals, expressed in direct collisions.

With a lack of resources, it is possible to eat animals of their own species (wolves, lynxes, predatory bugs, spiders, rats, pike, perch, etc.) Indirect - between shrubs and herbaceous plants in California.

1. Biosphere: functions of living matter.

Compositionally, living matter is the entire totality of living organisms that live in the biosphere. Living matter has biomass, is productive and has properties that are special in comparison with inert matter. These properties provide the most important functions of living matter.

1. Energy function. It is determined by the properties of the light-sensitive substance chlorophyll of green plants, with the help of which plants capture, accumulate solar energy, convert it into energy chemical bonds molecules of organic substances. Organic substances created by green plants serve as a source of energy for representatives of other kingdoms of living beings.

2. Transport function. Food interactions of living matter lead to the movement of huge masses of chemical elements and substances against gravity and in a horizontal direction. This movement is the transport function of living matter.

3. Destructive function. Mineralization of organic substances, decomposition of dead organic matter to simple inorganic compounds determines the destructive function of living matter. This function is mainly performed by fungi and bacteria.

4. Concentration function there is an accumulation of certain substances in living things. Shells of mollusks, shells of diatoms, skeletons of animals - all these are examples of the manifestation of the concentration function of living matter.

5. Living matter transforms the physical and chemical parameters of the environment. This is another main function of living matter - environmentdestructive... For example, forests regulate surface runoff, increase air humidity, enrich the atmosphere with oxygen.

8.2. Biosphere: global biogeochemical circulation of substances, energy flows.

Life has been around for billions of years. Inorganic matter is constantly consumed from the environment. During this time, it could have been consumed, because the amount of matter on Earth is finite. A finite amount of matter in the biosphere has acquired the property of infinity through the circulation of substances. Nutrition, respiration and reproduction of organisms and the associated processes of creation, accumulation of decay of organic matter provide a constant circulation of matter and energy.

Biogeochemical circulation of substances is repeated interconnected physical, chemical and biological processes of transformation and movement of matter in nature.

The driving forces of the biogeochemical circulation are the flows of the Sun's energy and the activity of living matter. As a result of the biogeochemical circulation, huge masses of chemical elements move, the energy accumulated in the process of photosynthesis is concentrated and redistributed.

The biogeochemical circulation in the biosphere is not completely closed, an insignificant part of the substance is “buried”. This led to the accumulation of biogenic oxygen in the atmosphere, and various chemical elements and compounds in the earth's crust.

The entire living world receives the necessary energy from organic substances created by photosynthetic plants or chemosynthetic microorganisms. The main channel of energy transfer is the food chain from the food source of plants, or producers, to consumers and decomposers. In this case, the corresponding trophic levels are formed.

With each next transfer from one trophic level to another, most of the energy (up to 90%) is lost in the form of heat. This limits the number of links - the shorter the chain, the more energy available.

Thus, life on our planet is carried out as a constant circulation of substances, supported by the flow of solar energy.

The biosphere is closely related to the space environment. Every second, over 1000 charged particles fly into an area of ​​1 m² across the boundary of the earth's atmosphere from space in the direction of the earth's surface. Cosmic radiation would be able to decompose the entire air of the atmosphere into ions and electrons in a short time. Life on Earth would become impossible. However, this does not happen, since the Earth is protected from cosmic rays by a magnetic field. Earth's magnetic field lines reflect low-energy cosmic rays, and they, as a rule, cannot penetrate into the lower atmosphere. Only cosmic rays with very high energy are able to penetrate the earth's magnetic field and fly to the surface of the earth, regardless of latitude.

In the magnetosphere, charged particles are mostly held together by magnetic field lines. When the next portion of particles arrives, some of them seem to be "shaken off" into the atmosphere. This creates electric currents and is the cause of geomagnetic storms.

Another protective shield of the Earth is ozone screen... The ozonosphere (ozone screen) consists of ozone - gas of blue color with a pungent odor. The height of its location is from 10 to 15 km, the maximum is 20-25 km. Ozone is formed in the stratosphere when, under the influence of ultraviolet rays, oxygen molecules break down into free atoms that can attach to other oxygen molecules. Another reaction is also possible - free oxygen atoms can attach to ozone molecules to form two oxygen molecules. In the stratosphere, ozone absorbs the ultraviolet rays of solar radiation, thereby protecting all life. In recent years, the ozone layer has been depleted. The main reason for depletion is the use of chlorofluorocarbons - freons, widely used in production and everyday life as refrigerants, foaming agents, solvents, aerosols. Freons catalyze the decomposition of ozone, upsetting the equilibrium between it and oxygen in the direction of decreasing ozone concentration.

8.4. Biosphere: biological diversity.

Life as a stable planetary phenomenon is possible only if it is of different quality.

Biological diversity of the biosphere includes the diversity of all species of living beings inhabiting the biosphere, the diversity of genes that form the gene pool of any population of each species, as well as the diversity of biosphere ecosystems in different natural areas.

The amazing variety of life on Earth is not just the result of the adaptation of each species to specific environmental conditions, but also the most important mechanism for ensuring the stability of the biosphere.

Only a few species in the ecosystem have significant numbers, high biomass and productivity. Such species are called dominant. Rare or scarce species have low numbers and biomass. As a rule, dominant species are responsible for the main flow of energy and are the main environment-formers, strongly influencing the living conditions of other species. Small species constitute, as it were, a reserve, and when various external conditions change, they can become part of the dominant species or take their place. Rare species mainly create species diversity.

When characterizing diversity, indicators such as species richness andevenness of distribution of individuals.

Species richness is expressed by the ratio of the total number of species to the total number of individuals or to a unit area. For example, 100 individuals live in two communities under equal conditions. But in the first, these 100 individuals are distributed among ten species, and in the second, among three species. In the given example, the first community has a richer species diversity than the second.

Suppose that both the first and the second community have 100 individuals and 10 species. But in the first community, individuals between the species are distributed by 10 in each, and in the second - one species has 82 individuals, and the rest by 2.

As in the first example, the first community will have a more even distribution of individuals than the second.

Conservation of biological diversity is an indispensable condition for the preservation and development of natural ecosystems, for the existence of all life in general.

8.5. Biosphere: Mechanisms of Resilience.

The biosphere is open system, which exchanges matter and energy with the environment. This is possible because the ecosystem contains not only autotrophs - producers of organic matter, but also heterotrophs - consumers and destroyers of organic matter. A relative equilibrium is established between the processes of creating organic matter and its transformation and destruction, and the ecosystem remains stable. Sustainability - this property of the ecosystem, which manifests itself in the maintenance of its composition, structure and functions, as well as in the ability to recover if they are disturbed. The stability of the biosphere is determined by:

- an exceptional variety of living matter;

- the interchangeability of its constituent ecosystems;

- duplication of links of biogeochemical cycles;

- the vital activity of living matter.

Biological diversity provides a wealth of information, material and energy connections of living and inert matter, as well as the relationship of the biosphere with space, geospheres, the processes of the global biogeochemical circulation.

The existence of each species depends on many other species, the destruction of one of the species can lead to the extinction of other species associated with it. Individuals of one species and products of their vital activity, as well as their dead bodies, are food for other species, which provides self-purification of ecosystems.

The socio-economic development of society has come and an obvious contradiction with the limited resources reproducing and life-sustaining capabilities of the biosphere. There is a depletion of natural resources of the land and ocean, irreversible loss of plant and animal species, pollution, simplification and degradation of ecosystems. Therefore, humanity is looking for ways of sustainable development of society and nature.

8.6. Biosphere: danger of depletion of biological diversity of species and ecosystems

Biological diversity - genetic, species, ecosystem - is the primary reason for the stability of both the biosphere as a whole and each individual ecosystem. Life as a stable planetary phenomenon is possible only if it is represented by a variety of species and ecosystems.

But in modern conditions, the scale of human economic activity has increased so much that there is a danger of loss of biological diversity. Different types of human activities lead to the direct or indirect destruction of various species and ecosystems of the biosphere.

There are several main types of environmental degradation that are currently the most dangerous for biological diversity. For example, flooding or siltation of productive lands, their concreting, asphalting or construction deprives wild animals of their habitats. Cultivation of land by unsustainable methods reduces yields due to erosion and depletion of soil fertility. Abundant irrigation of fields can lead to salinization, that is, to an increase in the concentration of salts in the soil to a level that cannot be tolerated by plants. As a result, typical plants of these places disappear. Deforestation in large areas in the absence of restoration plantings leads to the destruction of habitats of wild animals, a change in vegetation, and a reduction in its diversity. Many species are disappearing due to their extermination, as well as due to environmental pollution. Most of the species are disappearing due to the destruction of natural habitats, destruction of natural ecosystems. This is one of the main reasons for the depletion of biological diversity.

The biological diversity of the biosphere is understood as the diversity of all types of living organisms that make up the biosphere, as well as all the diversity of genes that form the gene pool of any population of each species, as well as the diversity of biosphere ecosystems in various natural zones. Unfortunately, at present, all kinds of human economic activities lead to a decrease in biological diversity. The biosphere is losing biodiversity. This is one of the environmental dangers.

Humanity still knows little about biological diversity, for example, there is still no exact data on the number of species in the biosphere. Experts are not always able to determine which territories require special protection measures and the organization of reserves on them. There are a huge number of poorly studied species, for example, in tropical forests.

To conserve biodiversity, it is necessary to invest in its study; improve nature management, trying to make it rational; solve global environmental problems at the international level.

UNESCO adopted the World Heritage Convention, which brings together natural and cultural monuments... The convention calls for taking care of objects that are of value to all of humanity. Biodiversity conservation depends both on the leaders of countries and on the behavior of every inhabitant of the planet.

9 Sustainability of the natural environment (ecosystems) in Russia.

Sustainability is one of critical parameters any systems, including ecological ones. It determines the ability of the system to preserve itself when the environment changes. In the context of this definition, sustainability can be considered synonymous with the term vitality. Theoretical basis qualitative and semi-quantitative assessments of the stability of complex systems are presented in the Web-atlas “Russia as a system”. In its most general form, this work shows that the viability of systems is determined by three groups of its parameters - the volume (mass of the system's substance), productivity (the rate of self-reproduction of the system's substance) and structural harmony. With regard to ecological systems, the quantitative measurement of the first two groups of parameters is well developed by classical biogeography. Methods for calculating the structural harmony of ecosystems (the third component) were developed by us and presented in the “Atlas of biological diversity of European Russia and adjacent territories” (M., PAIMS, 1996).

The level of potential resilience of indigenous ecosystems in Russia, that is, the level of resilience of ecosystems before their transformation by humans, is shown in the following map

The maximum stability occurs in the forest-steppe of European Russia, the Urals and the middle taiga of Siberia; to the north and south, the stability of the systems decreases. The minimum in Russia is observed in the arctic deserts. Since only the very edge of the Turanian deserts enters Russia, the level of their stability is still quite high.

The European forest-steppe - a combination of oak forests and meadow steppes - is undoubtedly the optimal life zone within Russia. As for Siberia, the retreat of maximum stability to the north here is undoubtedly associated with the general ecological youth of the local forest-steppe. Let us recall that if in the European forest-steppe the main forest-forming species is oak - a species of climax - the final stage of ecological succession, in Siberia it is replaced by birch - a pioneer species, the first to settle in non-forest areas.

The high potential for the stability of indigenous ecosystems in its most general form determines the ability of the natural environment to return to its original state in cases of both natural (for example, climatic) and anthropogenic impacts. In this capacity, it is the stability of ecosystems that sets the width of the “corridor of opportunities” for the economic development of human civilization, all forms of which are capable of changing nature. Even having lost a significant part of their area, indigenous ecosystems of resistant types continue to ensure the invariability of the regime of natural cycles, the production of biomass, and the utilization of substances harmful to living organisms. This feature is associated with the original role of soils - reservoirs of ecosystem “memory” - preserving many of the initial qualities of ecosystems even after anthropogenic transformation of the territory. Such capabilities of sustainable ecosystems are well illustrated by the map of disturbance of natural ecosystems.

The map shows that the potential stability of ecosystems in Russia is almost everywhere reduced to one degree or another due to the replacement of indigenous types of ecosystems with less stable anthropogenic derivatives (agrocenoses or secondary forests) or complete destruction during construction and urbanization. At the same time, the maximum impacts in terms of area are characteristic precisely for areas with the most stable natural complexes. In Russia they say: - "Whoever is lucky, they blame him." Sustainable ecosystems of the southern taiga and forest-steppe of Russia retained the possibility of a fairly autonomous development of the industrial civilization of the last century and a half, without external support, despite the maximum loss of natural complexes.

The steppes of the European part of Russia were a second time (after being abandoned during a period of serious threat from the steppe nomads in the 13th - 17th centuries) they were mastered in the 18th - 19th centuries, that is, against the background of a rather highly developed Agriculture... On the other hand, having the highest and most stable yield, these steppes experienced during the socialist period the most severe consequences of the pursuit of the growth of the arable wedge, “the fight against the grass-field system,” etc. At the same time, the stability reserve of ecosystems provided opportunities for economic development with a radical modernization and an increase in the power supply of a person. It is characteristic that areas with high stability of natural conditions largely correlate with areas of high stability (viability) of society. On the contrary, in the more southern steppes and semi-deserts (Caspian region) and in the North - in the tundra natural conditions due to their own instability, biota significantly limit human arbitrariness in the choice of options and the intensity of economic activity. Accordingly, the society of these regions is much less stable. It is precisely with this that the preservation of traditional forms of nature management in dry steppes, semi-deserts, tundra and northern taiga is associated. Industrial civilization is usually present here in the form of enclaves, the existence of which is possible only with constant support (resources, people, energy) from more stable regions. These enclaves look like a foreign body within the region and are the most destructive of its nature.

In spite of high level the stability of the ecosystems of the southern taiga and forest-steppe of European Russia, the threat of the loss of the natural balance and the unpredictable destruction of all forms of management (especially agriculture) in these areas were realized even in the Stalinist period. In the late 40s. a plan was adopted for the massive creation of forest belts and artificial reservoirs. The implementation of the plan was supposed to significantly increase the stability of the ecosystems of the steppes of southern Russia. Unfortunately, the plan was not fully implemented. But even in its implemented part, it did not fully achieve the desired results, since part of the forest belts was planted by the “nesting method” by TD Lysenko and died almost immediately, but from the very beginning, sufficient funds were not allocated for the creation of ponds, and they for the most part were broken through by the first high flood. As the plan was forgotten, and the shortage of grain in the country increased, a massive reduction of forest belts began - large tractors are more convenient to handle large tracts and forest belts interfered.

The last map shows an indicator reflecting the current level of ecosystem stability, taking into account both the loss of the area of ​​indigenous natural complexes and the decrease in the viability of anthropogenic ecosystems (agrocenoses, secondary forests, etc.). The map shows that in regions with the most favorable (comfortable) conditions for human life and economic development, the possibilities for development at the expense of the resources of the natural environment are practically exhausted. This cannot but cause serious concern - the main donor region of the country's population and one of the three main centers of sustainability of its society is in the zone of maximum decrease in the sustainability of ecosystems. Decreased stability increases its vulnerability to anthropogenic transformation, which is extremely dangerous for maintaining the health of not only the population of the Chernozem region, but also Russia as a whole.

In this respect, of the three main centers of increased vitality of society, the North Caucasian is in the most favorable position. Since in Russia it is the most archaic (with an ethnic level of social memory) center, its ties with the environment are the closest. Perhaps, it is precisely the higher preservation of the stability of its ecosystems that contributes to the success of its struggle with the Russian centers proper.

Conclusion.

For an ecosystem consisting of many species of different evolutionary levels, the influence of the entire complex of biotic factors is always a complex system of interactions, in which, for example, the microclimate on the soil surface largely depends on the species composition and the degree of development of the upper layers of vegetation, burrows of burrowing animals change the conditions of aeration and drainage of the soil and affect the conditions for the existence of vegetation.

A complete accounting of all the mutual influences of abiotic and biotic factors in natural ecosystems turns out to be almost impossible, therefore, in real conditions, one has to confine oneself to the analysis of only the most important factors that determine not specific features, but only the type of ecosystem.

This makes it possible to determine more or less reliably only the direction of changes in the ecosystem as its possible reaction to certain changes in abiotic conditions, in particular, caused by human activities... The specific course of such changes should always be monitored in real time by the environmental monitoring system - the regular monitoring of ecosystem parameters.

The main task of creating this work was to get acquainted with the concept of ecosystems in ecology, the factors affecting them and the problems of their relationship with humans. Having done this work, I tried to convey all the importance and relevance of the problems associated with ecosystems, gave examples and solutions to these problems. The basic laws of ecology were also described, considering in detail the factors affecting the human environment. The relevance of my work is unambiguous! Each person needs to know the basic laws, processes, features that occur and are characteristic of ecosystems, and ecology in general. All this you need to know in order to try to minimize the negative impact of human activity on the surrounding nature, since there will be no nature, there will be no life on earth ....

Bibliography

1. Environmental Chemistry / Ed. J. OM Bokris-M: Chemistry 1982;
2. Shustov S.B., Shustova L.V. Chemical foundations of ecology. M: Education, 1995;
3. Ecology. Tutorial. M: Knowledge 1997
4. A.A. Gorelov Ecology: textbook. - M .: Center. 1999.
5. Gulyaev S.A., Zhukovsky V.M., Komov S.V. Fundamentals of Natural Science. / Tutorial. - Yekaterinburg .: UralEkoCenter, 2001 .-- 560 p.
6. Moiseev N.N. Man and the biosphere. - M .: Molodaya gvardiya, 1995 .-- 302 p.
7. Nikolaykin N.N., Nokolaikina N.E., Melekhova O.P. Ecology. - M .: Bustard, 2004.
8. Petrov V.V. Environmental law of Russia. - M .: Publishing house BEK. 1995.

9.www.postupim.ru/9/himiya/853.shtml

10. www.krugosvet.ru

11. www.naveki.ru

Annex 1

Appendix 2

The effect of the temperature factor on living organisms

The cycle of substances in nature.

1. Biochemical circulation.

2. Cycle in the biosphere.

3. The carbon cycle.

4. Water cycle.

5. The carbon cycle

6. The oxygen cycle

7. The nitrogen cycle

8. The phosphorus cycle

9. The sulfur cycle.

1)Biogeochemical cycles.

Unlike the energy that is used by the body, turns into heat and is lost for the ecosystem, substances circulate in the biosphere, this is called biochemical cycles. Of the 90-odd elements that are found in nature, only 40 are needed by living organisms. The most important for them and needed in large quantities: carbon, hydrogen, oxygen, nitrogen. Oxygen enters the atmosphere as a result of photosynthesis and is used by organisms during respiration. Nitrogen is drawn out of the atmosphere by the activity of nitrogen-fixing bacteria and returned to it by other bacteria.

The circulation of elements and substances is carried out through self-regulating processes in which all the constituent ecosystems take part. These processes are hopeless. In nature, there is nothing in vain or harmful, even from volcanic eruptions there is a benefit, since the necessary elements, for example, nitrogen, enter the air with volcanic gases. There is a law of the global closure of the biochemical circulation in the biosphere, acting at all stages of its development, as well as the rule of increasing the closure of the biochemical circulation in the succession gait. In the course of the evolution of the biosphere, the role of biological components in closing the biochemical circulation increases. Man plays an even greater role in the biochemical cycle. But its role is carried out in the opposite direction. Man strengthens the circulation of substances, which has already taken shape, and this is reflected in his geological power, destructive in relation to the biosphere today.

When life appeared on Earth 2 billion years ago, the atmosphere consisted of volcanic gases. It had a lot of carbon dioxide and little oxygen (if any), and the first organisms were anaerobic. Since production exceeded respiration on average, oxygen accumulated in the atmosphere over geological time, and the content of carbon dioxide decreased. Today, the content of carbon dioxide in the atmosphere is increasing as a result of the burning of large amounts of fossil fuels and a decrease in the absorbing capacity of the "green belt". The latter is the result of a decrease in the number of the greenest plants, and also due to the fact that dust and other polluting particles in the atmosphere beat off those rays that enter the atmosphere. As a result of anthropogenic activity, the degree of closeness of biochemical circuits decreases. Although it is quite high (it is not the same for various elements and substances), it is nevertheless not absolute, which is shown by the example of the emergence of an oxygen atmosphere. Otherwise, evolution would be impossible (the highest degree of closedness of biochemical circuits is observed in tropical ecosystems - the most ancient and conservative ones).

Thus, one should speak not about the change by a person of what should not change, but rather about the influence of man on the speed and direction of changes and on the spread of their boundaries, which raises the rule of the measure of the transformation of nature. The latter is formulated as follows: during the operation of natural systems, it is impossible to exceed certain boundaries that allow these systems to maintain equilibrium.

2) Cycles of matter in the biosphere.

The processes of photosynthesis of organic matter from inorganic components last for millions of years, and during this time, chemical elements had to go from one form to another. However, this does not happen due to their circulation in the biosphere. Photosynthetic organisms annually assimilate almost 350 billion tons of carbon dioxide, release about 250 billion tons of oxygen into the atmosphere and break down 140 billion tons of water, forming over 230 billion tons of organic matter (in terms of dry weight).

Vast quantities of water pass through plants and algae during transport and evaporation. This leads to the fact that the water of the surface layer of the ocean is filtered by plankton in 40 days, and all other water in the ocean - approximately in less than a year. All carbon dioxide in the atmosphere is renewed in a few hundred years, and oxygen in a few thousand years. Every year, 6 billion tons of nitrogen, 210 billion tons of phosphorus and a large amount of other elements (potassium, sodium, calcium, magnesium, sulfur, iron, etc.) are included in the circulation by photosynthesis. The existence of these circuits gives ecosystems a certain duration.

There are two main circuits: large (geological) and small (biological).

A large circulation lasts for millions of years and consists in the fact that rocks are subject to destruction, and weathering products (including water-soluble nutrients) are carried by water flows into the World Ocean, where they form marine strata and only partially return to land with precipitation ... Geotectonic changes, the processes of subsidence of the continents and the raising of the seabed, the movement of seas and oceans for a long time lead to the fact that these strata return to land and the process begins again.

A small circuit (part of a large one) occurs at the ecosystem level and consists in the fact that nutrients, water and carbon are accumulated in plant matter, spent on building the body and on the life processes of both these plants themselves and other organisms (usually animals), which are eaten by these plants (consumers). The decomposition products of organic matter under the action of destructors and microorganisms (bacteria, fungi, worms) decompose again to the mineral components available to plants and which are drawn into the streams of matter. The cycle of chemicals from the inorganic environment through plant and animal organisms back to the inorganic environment using solar energy and the energy of chemical reactions is called the biochemical cycle. Almost all chemical elements are involved in such cycles, and above all those that take part in the construction of a living cell. So, the human body consists of oxygen (62.8%), carbon (19.37%), hydrogen (9.31%), nitrogen (5.14%), calcium (1.38%), phosphorus (0.64%) and about 30 more elements.

3) The carbon cycle.

4)The water cycle

The water is in constant motion. Evaporation from the surface of water bodies, soil, plants, water accumulates in the atmosphere and, sooner or later, falls out in the form of precipitation, replenishing reserves in oceans, rivers, lakes, etc. Thus, the amount of water on Earth does not change, it only changes its forms - this is the water cycle in nature. 80% of all precipitation falls directly into the ocean. For us, the most interesting are the remaining 20% ​​falling on land, since most of the water sources used by humans are replenished precisely due to this type of precipitation. To put it simply, water dropped on land has two paths. Or it, gathering in streams, rivulets and rivers, ends up in lakes and reservoirs - the so-called open (or surface) water intake sources. Or water, seeping through the soil and subsoil layers, replenishes stocks groundwater... Surface and groundwater are the two main sources of water supply. Both of these water resources are interconnected and have both advantages and disadvantages as a source of drinking water.

The water cycle is one of the greatest processes on the surface of the globe. It plays a major role in linking the geological and biotic cycles. In the biosphere, water, continuously passing from one state to another, makes small and large cycles. Evaporation of water from the ocean surface, condensation of water vapor in the atmosphere, and precipitation on the ocean surface form a small cycle. If water vapor is carried by air currents to land, the cycle becomes much more difficult.

In this case, part of the precipitation evaporates and flows back into the atmosphere, while the other part feeds rivers and water bodies, but eventually returns to the ocean by river and underground runoff, thereby completing the large cycle. An important property of the water cycle is that, interacting with the lithosphere, atmosphere and living matter, it binds together all parts of the hydrosphere: the ocean, rivers, soil moisture, The groundwater and atmospheric moisture. Water is the most important component of all living things. Ground water, penetrating through plant tissues in the process of transpiration, brings in mineral salts necessary for the life of the plants themselves.

The slowest part of the water cycle is the activity of the polar glaciers, reflecting the slow movement and rapid melting of glacial masses. River waters are characterized by the highest exchange activity after atmospheric moisture, which change on average every 11 days. The extremely fast renewability of the main freshwater sources and the desalination of water in the cycle are a reflection of the global process of water dynamics on the globe.

5)The carbon cycle

Carbon in the biosphere is often represented by the most mobile form - carbon dioxide. The source of the primary carbon dioxide of the biosphere is volcanic activity associated with the secular degassing of the mantle and lower horizons of the earth's crust.

The migration of carbon dioxide in the Earth's biosphere proceeds in two ways. The first way is to absorb it in the process of photosynthesis with the formation of organic substances and their subsequent burial in the lithosphere in the form of peat, coal, shale, scattered organic matter, sedimentary rocks. So, in distant geological epochs hundreds of millions of years ago, a significant part of the photosynthesized organic matter was not used either by consumers or decomposers, but was accumulated and gradually buried under various mineral sediments. Having been in the rocks for millions of years, this detritus under the influence of high temperatures and pressure (the process of metamorphization) turned into oil, natural gas and coal, what exactly - depended on the source material, duration and conditions of stay in the rocks. Now we are mining this fossil fuel in huge quantities to meet our energy needs, and by burning it, in a sense, we complete the carbon cycle. If not for this process in the history of the planet, mankind would probably have now completely different sources of energy, and maybe a completely different direction of development of civilization.

In the second way, carbon migration is carried out by creating a carbonate system in various water bodies, where CO2 is converted into H2CO3, HCO31-, CO32-. Then, with the help of calcium (less often magnesium) dissolved in water, CaCO3 carbonates are precipitated by biogenic and abiogenic pathways. Thick strata of limestone appear. Along with this large carbon cycle, there are also a number of small carbon cycles on the land surface and in the ocean.

Within the land, where there is vegetation, atmospheric carbon dioxide is absorbed by the process of photosynthesis during the daytime. At night, some of it is released by plants into the external environment. With the death of plants and animals on the surface, organic matter is oxidized to form CO2. A special place in the modern circulation of substances is occupied by the massive combustion of organic substances and a gradual increase in the content of carbon dioxide in the atmosphere, associated with the growth of industrial production and transport.

6) Oxygen cycle

Oxygen is the most reactive gas. Within the biosphere, there is a rapid exchange of environmental oxygen with living organisms or their remnants after death.

In the composition of the earth's atmosphere, oxygen ranks second after nitrogen. The dominant form of oxygen in the atmosphere is the O2 molecule. The oxygen cycle in the biosphere is very complicated, since it enters into many chemical compounds of the mineral and organic worlds.

Free oxygen of the modern earth's atmosphere is a by-product of the photosynthesis process of green plants and its total amount reflects the balance between the production of oxygen and the processes of oxidation and decay of various substances. In the history of the Earth's biosphere, a time has come when the amount of free oxygen reached a certain level and was balanced in such a way that the amount of oxygen released became equal to the amount of oxygen absorbed.

7) The nitrogen cycle

When organic matter decays, a significant part of the nitrogen contained in them is converted into ammonia, which, under the influence of nitrifying bacteria living in the soil, is then oxidized into nitric acid. The latter, reacting with carbonates in the soil, for example with calcium carbonate CaCO3, forms nitrates:

2HN03 + CaCO3 = Ca (NO3) 2 + COC + HOH

Some of the nitrogen is always released during rotting in a free form into the atmosphere. Free nitrogen is also released during the combustion of organic substances, when burning wood, coal, peat. In addition, there are bacteria that, with insufficient air access, can take oxygen from nitrates, destroying them with the release of free nitrogen. The activity of these nitrifying bacteria leads to the fact that part of the nitrogen from the form available to green plants (nitrates) goes into the inaccessible form (free nitrogen). Thus, not all of the nitrogen that was part of the dead plants is returned back to the soil; part of it gradually stands out in a free form.

The continuous loss of mineral nitrogen compounds should have long ago led to the complete cessation of life on Earth, if there were no processes in nature that compensate for the loss of nitrogen. These processes include, first of all, electrical discharges occurring in the atmosphere, in which a certain amount of nitrogen oxides is always formed; the last with water give nitric acid which turns into nitrates in the soil. Another source of replenishment of nitrogen compounds of the soil is the vital activity of the so-called azotobacteria, which are able to assimilate atmospheric nitrogen. Some of these bacteria settle on the roots of leguminous plants, causing the formation of characteristic swellings - "nodules", which is why they are called nodule bacteria. Assimilating atmospheric nitrogen, nodule bacteria process it into nitrogen compounds, and plants, in turn, convert the latter into proteins and other complex substances.

Thus, in nature, there is a continuous cycle of nitrogen. However, every year the fields are harvested with the most protein-rich parts of plants, such as grain. Therefore, it is necessary to apply fertilizers to the soil to compensate for the loss in it. essential elements plant nutrition.

8) Phosphorus cycle

Phosphorus is part of genes and molecules that carry energy into cells. In various minerals, phosphorus is contained in the form of inorganic phosphation (PO43-). Phosphates are water soluble but not volatile. Plants absorb PO43- from aqueous solution and incorporate phosphorus into various organic compounds, where it appears in the form of so-called organic phosphate. Phosphorus travels along food chains from plants to all other organisms in the ecosystem. At each transition, there is a high probability of oxidation of the phosphorus-containing compound during cellular respiration to provide the body with energy. When this happens, the phosphate in urine or its analogue re-enters the environment, after which it can be absorbed by plants again and start a new cycle.

Unlike, for example, carbon dioxide, which, wherever it is released into the atmosphere, is freely carried in it by air currents until it is absorbed by plants again, phosphorus does not have a gas phase and, therefore, there is no "free return" to the atmosphere. Getting into water bodies, phosphorus saturates and sometimes oversaturated ecosystems. There is essentially no way back. Something can return to land with the help of fish-eating birds, but this is a very small part of the total, which also ends up near the coast. Oceanic phosphate deposits rise above the surface of the water over time as a result of geological processes, but this happens over millions of years.

Consequently, phosphate and other mineral soil biogens circulate in the ecosystem only if the "waste" of vital activity containing them is deposited at the sites of absorption of this element. In natural ecosystems, this is basically what happens. When a person interferes with their functioning, he disrupts the natural cycle, transporting, for example, the crop along with the nutrients accumulated from the soil over long distances to consumers.

9)The sulfur cycle

Sulfur is an important component of living matter. Most of it in living organisms is in the form of organic compounds. In addition, sulfur is a part of some biologically active substances: vitamins, as well as a number of substances that act as catalysts for redox processes in the body and activate some enzymes.

Sulfur is an extremely active chemical element of the biosphere and migrates in different valence states depending on the redox conditions of the environment. The average sulfur content in the earth's crust is estimated at 0.047%. In nature, this element forms over 420 minerals.

In igneous rocks, sulfur is found mainly in the form of sulfide minerals: pyrite, pyrronite, chalcopyrite, in sedimentary rocks it is contained in clays in the form of gypsum, in fossil coals - in the form of sulfur pyrite impurities, and less often in the form of sulfates. Sulfur in the soil is mainly in the form of sulfates; organic compounds are found in oil.

In connection with the oxidation of sulfide minerals in the process of weathering, sulfur in the form of sulfation is transferred by natural waters to the World Ocean. Sulfur is absorbed by marine organisms, which are richer in inorganic compounds than freshwater and terrestrial ones.

Grade 9

Ticket number 26

1. Cycles of chemical elements in nature (for example, carbon, oxygen and nitrogen). The role of living beings in the cycle of chemical elements.

Cycles of chemical elements on Earth are repetitive processes of transformation and movement of substances in nature, which are more or less cyclical. The general circulation of substances consists of individual processes (circulation of water, gases, chemical elements), which are not completely reversible, because there is a dispersion of matter, a change in its composition, etc.

With the advent of life on Earth, living organisms (the circulation of oxygen, carbon, hydrogen, nitrogen, calcium, and other biogenic elements) play a huge role in the circulation of substances. Global impact on the circulation of substances and chemicals. elements have a human activity, as a result of which new routes of migration of substances emerge and changes in nature, new substances appear, etc.

A deep study of the transformations of substances and energy in nature and taking into account the consequences of human activity - necessary condition preservation of the environment.

Consider the cycles of some chemical elements
The carbon cycle
In nature, there is a continuous process of destruction of some carbon-containing substances and the formation of others. Organic matter is destroyed during fuel combustion, breathing, and decay. Simpler substances, including carbon dioxide, are formed from them. Carbon dioxide is released during the decomposition of some inorganic substances, for example, during the burning of limestone. However, its amount in the atmosphere is increasing slowly. This is due to the fact that carbon monoxide (IV) is involved in photosynthesis and carbon atoms are again transferred to the organic matter of plants. Many of them are eaten by animals and humans. This is the continuous circulation of carbon in nature.

Minerals and rocks
(oil, natural gas, coal, graphite - combustion,
limestone, dolomites - calcination), volcanic gases

carbon dioxide

plants
absorb carbon dioxide during photosynthesis,
element carbon goes into organic matter

animals
organic matter of plants is included in food
for animals and humans

carbon dioxide
processes of respiration, fermentation, decay
accompanied by the formation of carbon dioxide
(organic matter is converted to carbon dioxide by oxidation reactions)

Oxygen cycle

The composition of the atmosphere has changed slightly over the past centuries. The air contains: nitrogen (78%), oxygen (21%), carbon dioxide (0.03%) and inert gases (about 1%). Living organisms during evolution have adapted to a certain composition of the atmosphere, and even minor changes composition adversely affect living organisms.

Oxygen is consumed in huge quantities for many chemical reactions: respiration of living organisms, decay processes; human economic activity: fuel combustion, smelting, cutting and welding of metals, many industries (medicinal substances, nitric and sulfuric acids, fertilizers, synthetic fibers, explosives, plastics, etc.).

But still, the total mass of oxygen in the air does not change noticeably. This is due to the process of photosynthesis taking place in green plants in the light. As a result of photosynthesis, plants absorb carbon dioxide and release oxygen. As a result of this process, the mass of oxygen in the air is replenished.

Oxygen of the atmosphere

plants, animals, people
absorb oxygen when breathing, and emit carbon dioxide

carbon dioxide
plants absorb carbon dioxide and release oxygen,
this process is called photosynthesis

atmospheric oxygen
plants release oxygen during photosynthesis

The nitrogen cycle

The chemical element nitrogen in the form of a simple substance makes up most of the atmosphere, which contains 78% by volume, is a part of organic substances, in particular, the composition of proteins that make up living organisms. In the soil, nitrogen is contained in the form of ammonium ions NH4 + and nitrate ions NO3-.

Green plants need nitrogen, which is the main nutrient along with phosphorus and potassium. Nitrogen affects the growth of the green mass of plants, with a lack of nitrogen, their growth slows down and stops. When growing plants, the soil is gradually depleted in nitrogen and can become sterile.
When organic matter decays and burns, part of the bound nitrogen is released and escapes into the atmosphere. However, under natural conditions, the content of bound nitrogen in the soil does not decrease, and the mass of free nitrogen in the atmosphere does not increase either. How can this be explained?

It turns out that there are bacteria, both freely living in the soil and settling on the roots of leguminous plants, which assimilate atmospheric nitrogen, converting it into organic compounds. Small amounts of nitrogen bind when lightning discharges: in this case, nitrogen oxides are formed, nitric oxide (IV), combining with water, turns into nitric acid, which turns into nitrates in the soil.

As a result of these processes, there is a cycle of chemical elements in nature. During harvesting, a significant part of nitrogen is removed from the fields, therefore it is necessary to apply nitrogen fertilizers to the soil in order to make up for this loss.

Nitrogen of the atmosphere
(the nitrogen content in the atmosphere is constant, 78% by volume)

Nitrogen is assimilated by nitrogen-fixing bacteria
convert it into nitrate and ammonium forms and organic substances

Plants
(in plants, nitrogen is in the form of organic substances - proteins, vegetable protein serves as food for animals and humans)

Animals and man
Decay, metabolic products, combustion of organic matter

Nitrogen of the atmosphere

So, having examined the cycles of some chemical elements, we became convinced that they are characterized by cyclicity, various links of animate and inanimate nature participate in the cycle. As a result of the circulation of substances, a constant composition of the atmosphere, soil, and hydrosphere is maintained.

Living organisms play an important role in the circulation of substances: plants, animals and humans. In green plants inorganic substances are converted into organic in the process of photosynthesis, proteins necessary for human life are created in the body of animals (animal proteins contain all amino acids). A person influences the circulation of substances by his economic activities, very often his influence is harmful to nature.

Any unreasonable human intervention causes a violation of the natural balance, therefore, it is necessary to study all sides and links of the cycle of substances and take into account their features, in order not to disturb the natural balance in nature.

Cycles of chemical elements

Chemicals travel like humans. However, chemical elements have more means of transportation, because they use vehicles created by both nature and man. In nature, chemical elements move in the earth's crust together with magmatic melts, along the earth - in the form of fragments of rocks, with deep and surface waters, with living organisms.

People help to travel chemical elements, sending them with food (grain, fruits, vegetables), with raw materials for industry (iron ore, timber, coal) by railways, airplanes and ships.

On the way of chemical elements, obstacles can arise - geochemical barriers, forcing them to accumulate in the earth's crust, soils, silts and living organisms. Chemical elements always travel together.

The nitrogen cycle in nature

When organic matter decays, a significant part of the nitrogen contained in them is converted into ammonia, which, under the influence of the bacteria that live in the soil, is oxidized to nitric acid. The latter, reacting with carbonates in the soil, for example, calcium carbonate CaCO3, forms nitrates

2НNО3 + CaCO3 = Ca (NO3) 2 + СО 2 + Н 2 О

Some of the nitrogen is always released during rotting in a free form into the atmosphere. Free nitrogen is also released during the combustion of organic substances, when burning wood, coal, peat. In addition, there are bacteria that, with insufficient air access, can take oxygen from nitrates, destroying them with the release of free nitrogen. The activity of these denitrifying bacteria leads to the fact that part of the nitrogen from the form available to green plants (nitrates) is transferred to the inaccessible form (free nitrogen). Thus, not all of the nitrogen that was part of the dead plants returns back to the soil, some of it is gradually released in free form.

The continuous loss of mineral nitrogen compounds should have long ago led to the complete cessation of life on Earth, if there were no processes in nature that compensate for the loss of nitrogen. These processes include, first of all, electrical discharges occurring in the atmosphere, in which a certain amount of nitrogen oxides is always formed; the latter with water give nitric acid, which is converted into nitrates in the soil. Another source of replenishment of nitrogen compounds of the soil is the vital activity of the so-called azotobacteria, which are able to assimilate atmospheric nitrogen. Some of these bacteria settle on the roots of leguminous plants, causing the formation of characteristic swellings - "nodules", which is why they are called nodule bacteria. Assimilating atmospheric nitrogen, nodule bacteria process it into nitrogen compounds, and plants, in turn, convert the latter into proteins and other complex substances.

Thus, in nature, there is a continuous cycle of nitrogen. However, every year the fields are harvested with the most protein-rich parts of plants, such as grain. Therefore, it is necessary to apply fertilizers to the soil to compensate for the loss of the most important plant nutrients in it.

Oxidation processes constantly occur on the surface of the globe (respiration of plant and animal organisms, decay), as a result of which free oxygen binds with other elements that make up organic substances and forms various compounds, for example, carbon dioxide CO 2, water H 2 O.

The oxygen cycle in nature

But the amount of free oxygen in the atmosphere remains unchanged. This is because nature is undergoing processes opposite to oxidation, as a result of which free oxygen is formed. Indeed, as the Russian scientist K.A. Timiryazev, in the green leaves of plants under the influence of sunlight and chlorophyll from water and carbon dioxide CO 2, organic matter and oxygen O 2 are formed, which is released into the atmosphere.

The liberated oxygen is again consumed in the oxidation of organic matter. The water and carbon dioxide formed during this oxidation are again converted in green leaves in the sunlight into organic substances and free oxygen, etc. This is how oxygen is circulated in nature, that is, its alternating entry into compounds and release from them.

Phosphorus cycle

Plants can grow if the soil contains phosphates. But these salts are not enough even in the most fertile soils. Where man does not interfere with the life of nature, phosphorus extracted from the soil by plants returns to the soil when the remains of plants and animals decay. This is how the cycle of phosphorus is carried out in nature.

The carbon cycle

In detail to other elements, carbon atoms in nature are not constantly in the same compounds, but pass from one substance to another.

Up to 17 billion tons of carbon dioxide annually passes from the atmosphere to the composition of organic matter in plants. A lot of carbon that has passed into the composition of plants is assimilated by organisms of animals and humans with plant food. Some of the carbon assimilated by plants is deposited in the ground in the form of peat, coal and shale.

In addition to the absorption of carbon dioxide by plants, a lot of it also binds as a result of interaction with the carbonates of the earth's crust, which in this case pass into bicarbonates.

Along with the processes of binding carbon dioxide, there are processes of its release into the atmosphere. Carbon dioxide is produced in huge quantities during the respiration of animals, humans and plants. The release of carbon dioxide into the atmosphere also occurs when various types of fuel are burned. Finally, the atmosphere is replenished with carbon dioxide from volcanic activity, the release of gases from cracks in the earth and water sources. This is how the continuous cycle of carbon occurs in nature.