The cycle of chemical elements in nature. The cycle of the most important chemical elements in nature
Between the lithosphere, hydrosphere, atmosphere and living organisms of the Earth, an exchange of chemical elements constantly occurs. This process has a cyclical nature: moving from one sphere to another, the elements again return to their original state. The cycle 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 relates to dissolved gases - carbon dioxide, oxygen, nitrogen. Cold water at high latitudes dissolves atmospheric gases. When entering the tropical zone with ocean currents, it releases them, since the solubility of gases decreases upon heating. The absorption and evolution of gases also occurs when warm and cold seasons change.
The appearance of life on the planet had a huge impact on the natural cycles of some elements. This primarily refers to the cycle 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 affect the cycle of many metal elements. Despite the fact that the total mass of living organisms of the Earth is millions of times less than the mass of the earth's crust, plants and animals play a crucial role in the movement of chemical elements.
The processes of photosynthesis of organic matter from inorganic components lasts millions of years, and during this time, the chemical elements had to move from one form to another. However, this does not happen due to their cycle in the biosphere. Annually, photosynthetic organisms absorb 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 (calculated on dry weight).
Vast quantities of water pass through plants and algae in the process of ensuring transport function 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 the rest of the ocean in about a year. All atmospheric carbon dioxide 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 number 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 streams of water into the oceans, where they form marine strata and only partially return to land with precipitation . Geotectonic changes, the processes of lowering the continents and raising the seabed, the movement of the seas and oceans for a long time lead to the fact that these strata return to land and the process begins again.
The small cycle (part of the large) takes place at the ecosystem level and consists in the fact that nutrients, water and carbon are accumulated in the plant matter, are spent on building the body and vital processes of both these plants and other organisms (usually animals), who eat these plants (consumers). The decomposition products of organic matter under the action of destructors and microorganisms (bacteria, fungi, worms) decompose again to mineral components that are accessible to plants and involved in the flow of matter.
In all natural waters, dissolved gases contain various gases, mainly nitrogen, oxygen and carbon dioxide. The amount of gas that sea water can dissolve depends on its salinity, hydrostatic pressure, but mainly on temperature. The higher the salinity and the higher the temperature, the less gas 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 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 discharged into the oceans by rivers. Since little nitrogen is deposited in sedimentary rocks, it can be considered that denitrification in the oceans in the course of natural processes balances the fixation of nitrogen and its transport to land. In connection with the use of fertilizers, its quantity entering water bodies sharply increased, worsening the quality of water.
Phosphorus is the most important biogenic element, most often limiting the development of the productivity of water bodies. Therefore, the excess of phosphorus compounds from the catchment with surface runoff from the fields, with drains from farms, with untreated domestic wastewater, and also with some industrial waste leads to a sharp uncontrolled increase in the plant biomass of the water body (this is especially true for non-flowing and low-flowing water bodies). Human activity disrupted the natural cycle of phosphorus. Phosphorus compounds are used to produce fertilizers and detergents. This leads to pollution of water bodies with phosphorus compounds. Under such conditions, phosphorus ceases to be an element limiting the growth of the mass of living things, especially algae and other aquatic plants.
Sulfur is contained in the atmosphere in small quantities, mainly in the form of hydrogen sulfide and sulfur dioxide. Quite a lot of this element (in the form of sulfate ions) is in the hydrosphere. In the lithosphere, sulfur is found in the form of a simple substance (native sulfur) and in the composition of numerous minerals - metal sulfides and sulfates. In addition, sulfur compounds are found in coal, oil shale, oil, and natural gas. Sulfur is part of many proteins, so it is always found in animals and plants. Human activity has significantly changed the sulfur cycle between the atmosphere, oceans and the land surface. These changes are stronger than human exposure to the carbon cycle. As in the case of the global carbon cycle, technogenic emissions of sulfur into the environment have little effect on the distribution of masses of this element on the Earth's surface. However, the increased sulfur content in industrial and household waste creates a danger to life in large areas. The massive release of sulfur dioxide into the atmosphere generates acid rain, which can fall far beyond the boundaries of industrial areas. Pollution of natural waters with soluble sulfur compounds poses a threat to living organisms of inland waters and coastal areas of the seas.
Carbon is the main element of life. It is contained 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 interrelated inorganic particles: bicarbonate - ion, carbonate ion and dissolved carbon dioxide. The bulk is accumulated in carbonates at the bottom of the ocean (1016 tons), in crystalline rocks (1016 tons), coal and oil (1016 tons) and participates in a large cycle of the cycle. In the last century, human activity has made significant changes to the carbon cycle. The burning of fossil fuels — coal, oil, and gas — has led to an increase in carbon dioxide emissions. This does not greatly affect the distribution of carbon masses between the Earth’s shells, but can have serious consequences due to an increase in the greenhouse effect.
Silicon is the second most abundant (after oxygen) chemical element in the earth's crust. Its clarks in the earth's crust - 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 account for 87% of the lithosphere), the biogeochemical cycles of silicon (especially on land) have not yet been studied. Manganese and iron are constant components of natural fresh water, and their content often exceeds the levels of basic macronutrients.
Introduction
1 The cycle of the most important chemical elements in nature
1.1 The water cycle.
1.2. Carbon cycle.
1.3. Nitrogen cycle
1.4. The sulfur cycle.
1.5. Phosphorus cycle
3 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 optimum
4.2. The concept of tolerance
4.3. Liebig's law, or the "law of the minimum", or the law of the limiting factor
4.5. Rule of advance V.V. Alekhine
4.6. The principle of static fidelity G.Ya. Bay Bienko
4.7. The rule of zonal tiers 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 of the 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 part of organic compounds, the cycles of these elements are closely related. The main source of nitrogen is atmospheric air. Thanks to fixation by living organisms, nitrogen enters from the air into the soil and water. Blue-green bind about 25 kg / ha of nitrogen annually. Effectively fix nitrogen and nodule bacteria.
Plants absorb nitrogen compounds from the soil and synthesize organic matter. Organics spreads along food chains up to reducers, which break down proteins with the release of ammonia, which is further converted by other bacteria to nitrites and nitrates. A similar nitrogen circulation occurs between benthos and plankton organisms. Denitrifying bacteria reduce nitrogen to free molecules that return to the atmosphere. A small amount of nitrogen is fixed in the form of oxides by lightning discharges and enters the soil with precipitation, and also comes from volcanic activity, compensating for the decrease in deep-sea deposits. Nitrogen also enters the soil in the form of fertilizers after industrial fixation from the atmosphere.
The nitrogen cycle is a more closed cycle than the carbon cycle. Only a small amount is washed away by rivers or 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 cycle mainly in the form of sulfides from the weathering products of land and seabed rocks. A number of microorganisms (for example, chemosynthetic bacteria) are able to convert sulfides into a form accessible to plants - sulfates. Plants and animals die off, the mineralization of their residues by reducers returns sulfur compounds to the soil. So, sulfur bacteria bacteria oxidize to sulfates hydrogen sulfide formed during the decomposition of proteins. Sulfates facilitate the conversion of sparingly soluble phosphorus compounds to soluble ones. The amount of mineral compounds available to plants is increasing, the conditions for their nutrition are improving.
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, is already worrying scientists. The amount of sulfur in the atmosphere increases significantly when burning fossil fuels.
1.5. The phosphorus cycle.
This element is contained in a number of vital molecules. Its cycle begins by leaching of phosphorus-containing compounds from rocks and their entry into the soil. Part of the phosphorus is carried to rivers and seas, the other is absorbed by plants. The biogenic cycle of phosphorus occurs according to the general scheme: reducers. ® consumables ® producers
Significant amounts of phosphorus are applied to the fertilizer fields. About 60 thousand tons of phosphorus annually returns to the mainland with fish catch. In the human protein diet, fish make 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, humanity will probably have to solve the problem of the return of phosphorus to the biogenic cycle.
Organisms in the ecosystem are connected 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 the job. Nutrients originally originate from the abiotic component of the system, into which they eventually return either as waste products, or after the death and destruction of organisms. Thus, in the ecosystem there is a constant cycle of nutrients, in which both the 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 deeper into the Earth, metamorphic rocks can melt and form magma. Earth's internal energy (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 crust in the form of intrusions. The processes of mountain building 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 movable zones of the earth's crust and, when bent, again fall to great depths (over 10 km).
The processes of metamorphism, crossing, crystallization begin again, and the chemical elements return to the surface of the Earth. Such a “route” of chemical elements is called a large geological cycle. The geological cycle is not closed, because part of the chemical elements goes out of the cycle: carried away into space, fixed by strong bonds on the earth's surface, and part comes from outside, from space, with meteorites.
The geological cycle is a global journey 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 the soil, water air. But at the same time they are returned. Chemical elements are washed out of plants by rainwater, released into the atmosphere when breathing, and deposited in the soil after the death of organisms. Returned chemical elements are again and again involved in living matter in "travel". All together, it makes up the biological, or small, cycle of chemical elements. He is not closed either.
Some of the “travelers” elements are carried out beyond its borders with surface and ground waters, some at different times “turn off” from the cycle and linger in trees, soil, and peat.
Another route of chemical elements runs from top to bottom from peaks and watersheds to valleys and riverbeds, hollows, and depressions. Chemical elements enter the watersheds only with atmospheric precipitation, and are carried down with water and under the influence of gravity. The consumption of the substance prevails over the intake, as evidenced by the very name of the landscapes of the watershed eluvial.
On the slopes, the life of chemical elements is changing. The speed of their movement increases sharply, and they "pass" the slopes, like passengers comfortably settled in the train compartment. The landscapes of the slopes are called transit.
Chemical elements are able to "rest" from the road only in accumulative (accumulating) landscapes located in depressions. In these places, they often remain, creating good nutritional conditions for vegetation. In some cases, vegetation has to deal with an excess of chemical elements.
Many years ago, man intervened in the distribution of chemical elements. Since the beginning of the twentieth century, human activity has become the main way of their journey. During mining, a huge amount of substances is removed from the earth's crust. Their industrial processing is accompanied by emissions of chemical elements with industrial wastes into the atmosphere, water, and soil. This pollutes the living environment of living organisms. On the earth, new areas with a high concentration of chemical elements appear man-made geochemical anomalies. They are common around mines of non-ferrous metals (copper, lead). These sites sometimes resemble lunar landscapes, because they are practically deprived 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 environmental pollution, which cannot be crossed, beyond which human diseases and even the extinction of civilization are inevitable.
By creating biogeochemical "dumps", nature, perhaps, wanted to warn a person from ill-conceived, immoral activities, to show him with a good example what the violation of the distribution of chemical elements in the earth's crust and on its surface leads to.
The possibility of our life, its conditions are dependent on natural resources. Biological and especially food resources serve as the material basis of life. Mineral and energy resources, including in production, serve as the basis for a stable standard of living.
Intensively consuming natural resources, a person needs to maintain a natural balance. The balance of resources in the cycle of matter determines the stability of the biosphere.
2 Environmental factors and their description.
2.1. Habitat and classification of environmental factors.
Under habitat they understand the totality of external environmental conditions and phenomena in which living organisms are immersed, and with which these organisms are in constant interaction.
In bioecology, it is usually a natural environment that has not been altered by humans. Applied (social) ecology speaks of the environment, one way or another mediated by man.
Individual elements of the environment to which organisms respond with adaptive reactions (adaptations) are called environmental factors or environmental factors. Among environmental factors, usually three groups of factors are distinguished: abiotic, biotic and anthropogenic.
1. Abiotic environmental factors called conditions that are not directly related to the vital activity of organisms. The most important abiotic factors include temperature, light, water, composition of atmospheric gases, soil structure, composition of nutrients in it, topography, etc. These factors can affect organisms either directly, for example, light or heat, or indirectly, for example, the terrain, which determines the effect of direct factors, light, wind, moisture, etc. Perhaps, among the abiotic factors there are also those that we still don’t even we guess. So, for example, we recently discovered the influence of changes in solar activity on processes in the biosphere.
2. Biotic environmental factors called the totality of the effects of some organisms on others. Living creatures can serve as a source of food for other organisms, be their habitat, contribute to their reproduction, etc. The effect of biotic factors can be not only direct, but also indirect, expressed in the correction of abiotic factors, for example, changes in soil composition, microclimate under the forest canopy, etc.
|
ABIOTIC |
Biotic |
|
Physicalclimatic - moisture, light, temperature, wind, pressure, currents, day length |
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 permeability of the soil |
The influence of animals on each other and on other organisms in the biocenosis |
|
Chemical- composition of air, content of nutrients in soil or water, salinity of air and water, pH reaction |
Anthropic factors - all types of human activity |
3. Anthropogenic environmental factorscalled 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 impact 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 establishes a rigid framework for its existence.
Direct or scattered solar radiation is not required only for a small group of living creatures - some species of mushrooms, 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 incident on the Earth is used for photosynthesis);
2. Transpiration (about 75% - for transpiration, which provides cooling of plants and the movement of aqueous solutions of mineral substances along them);
3. Photoperiodism (provides synchronization of vital processes in living organisms to 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 of central Russia, as well as 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 connection, special adaptive reactions were developed in the form of a layer, leaf mosaic, phenological differences, etc. According to the requirements of the lighting conditions, the plants are divided into light or light-loving (sunflower, plantain, tomato, acacia, melon), shadow or non-loving (forest herbs, mosses) and shade-tolerant (sorrel, heather, rhubarb, raspberry, blackberry).
Plants form the living conditions of other species of living creatures. That is why their reaction to broadcast conditions is so important. Environmental pollution leads to a change in exposure: a decrease in the level of solar insolation, a decrease in the amount of photosynthetically active radiation (the PAR component of solar radiation with a wavelength of 380 to 710 nm), and a change in the spectral composition of light. As a result, it 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. The activity of populations depends on the time of year and time of day, because 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 vital processes up to suspended animation. This primarily concerns plants, microorganisms, fungi and poikilothermic (cold-blooded) animals. Activity is maintained only by homo-thermal (warm-blooded) species. Heterothermic organisms, being in an inactive state, have a body temperature not much higher than the temperature of the environment; in the active state - fairly high (bears, hedgehogs, bats, gophers).
Thermoregulation of homoyothermal animals is ensured by a special type of metabolism, which occurs with the release of animal heat in the body, the presence of heat-insulating integument, size, physiology, etc.
As for the plants, they developed a number of properties in the process of evolution:
1. Cold resistance - the ability to tolerate low positive temperatures (from ° C to + 5 ° C) for a long time;
2. Winter hardiness - the ability of perennial species to tolerate a set of winter adverse conditions;
3. Frost resistance - the ability to tolerate negative temperatures for a long time;
4. Anabiosis - the ability to tolerate a period of prolonged lack of environmental factors in a state of sharp decline in metabolism;
5. Heat resistance - the ability to tolerate high (St. + 38 ° ... + 40 ° C) temperatures without significant metabolic disorders;
6. Ephemerality - a reduction in ontogenesis (up to 2-6 months) in species growing under conditions of 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 give full-fledged offspring, some do not have time to prepare for a period of adverse conditions and die. Global warming at + 0.5..1.5 ° C, according to most experts, will lead to disastrous consequences for the biosphere.
3.3 Humidity
Moisture conditions in our zone are favorable enough for the existence of organisms. Most living creatures are 70-95% water. Water is needed for all biochemical and physiological processes. Therefore, it is so important for 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 creatures are distinguished:
1. Hydrobionts - inhabitants of ecosystems, whose entire life cycle takes place in water;
2. Hygrophytes - plants of wet habitats (Kaluga marsh, European swimsuit, broadleaf cattail);
3. Hygrophils - animals that live in very moist parts of ecosystems (mollusks, amphibians, mosquitoes, wood lice);
4. Mesophytes - plants of moderately moistened habitats;
5. Xerophytes - plants of dry habitats (feather grass, wormwood, astrogale);
6. Xerophiles - inhabitants of arid territories that cannot tolerate increased moisture (some species of reptiles, insects, desert rodents and mammals).
7. Succulents - plants of the most arid habitats that can accumulate significant moisture reserves inside the stem or leaves (cacti, aloe, agave);
8. Sclerophytes - plants of very arid territories that can withstand severe dehydration (camel spine, Saksaul, Saksagyz);
9. Ephemeras and ephemeroids - annual and perennial herbaceous species having a shortened cycle coinciding with a period of sufficient moisture.
Moisture consumption of plants can be characterized by the following indicators:
1. Drought tolerance - the ability to tolerate reduced atmospheric and (or) soil drought;
2. Moisture resistance - the ability to tolerate waterlogging;
3. The transpiration coefficient is the amount of water spent on the formation of a unit of dry mass (for white cabbage 500-550, for pumpkin-800);
4. The 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 water is dangerous, and in some cases fatal to cenoses. A change in the water cycle in the biosphere can lead to unpredictable consequences for all living organisms.
3.4. Air-gas mode
The atmosphere of the Earth has a fairly stable composition. 21% of oxygen in the surface air layer provides full breathing to all organisms in natural ecosystems. 0.03% carbon dioxide is enough for photosynthetic plant reactions. The horizontal and vertical movement of air masses creates the necessary air exchange for all the inhabitants of the ecosystem - from soil microorganisms to insects and birds.
The air-gas regime can be violated in natural conditions very rarely (for example, during an eruption of a volcano), in anthropic ones - quite often. The main air pollutants in our environment are carbon monoxide, sulfur dioxide, nitrogen dioxide, formaldehyde, dust. Difficult photosynthesis, respiration, many other physiological processes, and in some cases modifying them, atmospheric pollution stops 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 life are within the ability of the biosphere to self-purify and self-repair.
General laws of the combined action of factors on organisms
4.1. The concept of optimum
Each organism, each ecosystem develops with 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), in the framework of which the vital activity of objects occurs.
In the process of evolution, organisms formed certain requirements for environmental conditions. Doses of factors at which the organism, population or biocenosis achieve the best development and maximum productivity corresponds to the optimum conditions. With a change in this dose in the direction of decrease or increase, the body is suppressed and the stronger the deviation of the factor value from the optimum, the greater the decrease in viability, up to the death of the body or destruction of the biocenosis. The conditions under which vital activity is maximally depressed, but the body 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 forests of Kayander larch forbs grow in floodplains - there is a favorable hydrothermal regime and soils during floods are regularly replenished with nutrients. The lowest productivity forests are from the same larch, but with a cover of sphagnum mosses, formed on the northern slopes of the mountains under conditions of constant overmoistening and cold soil. The permafrost level under the moss cover does not fall below 30 cm. In Southern Primorye, optimal forest growing conditions are characteristic of the northern slopes in their middle part, and pessimal to dry southern slopes with a convex surface.
Many examples can be given of optimums and pessimums in plants, animals, and their communities with respect to light, moisture, heat supply, soil salinity, and other factors.
4.2. The concept of tolerance
For different types of plants and animals, the limits of the conditions in which they feel good vary. For example, some plants prefer very high humidity, while others prefer arid habitats. Some species of birds fly to warmer climes, others - crossbills, pine trees and chicks hatched in winter. The wider the quantitative limits of environmental conditions under which an 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 environmental valency of the species is judged by the amplitude of the natural fluctuations of the factor transferred by the populations.
Species with narrow ecological plasticity, i.e. able to exist in conditions of a small deviation from its optimum, highly specialized, are called stenobiontic (stenos - narrow), species widely adapted, able to exist with significant fluctuations of factors - eurybiontic (eurys - wide) The boundaries beyond which existence is impossible are called the lower and upper limits of endurance, or ecological valency.
EXAMPLE. Fish of salt and fresh water bodies - stenobionts. Three-spined stickleback and salmon are eurybionts. Stenobionts-plants: Chosenia, Korean poplar - floodplain plants, hygrophytic plants (marsh marigold, cattail), Primorye xerophytes - densely flowered pine, Manchurian apricot, woodpecker, etc. Almost all mammals, including humans, can be referred to stenobionts. A small deviation of air temperature (22-26 ° C) and water (28-38 ° C) from the “normal” value, a low oxygen content and a high content of harmful substances (chlorine, mercury vapor, ammonia, etc.) in the air is enough to cause a sharp deterioration in his condition.
In relation to one factor, the type of m. stenobiont, in relation to another - eurybiont. Depending on this, directly opposite pairs of species are distinguished: stenothermal - eurythermic (with respect to heat), stenohydric - euryhydric (with respect to moisture), stenohalic - eurythalic (with respect to salinity), wall - euriphotic (with respect to light), etc.
There are other terms that characterize the relationship of species to environmental factors. Adding the ending “phyl” (phyleo (Greek) - I love) means that the species has adapted to high doses of the factor (thermophile, hygrophil, oxyphil, gallophil, chionophile), and adding “phob”, on the contrary, to low (gallophob, chionophobe) . Instead of a “thermophobe”, a “cryophile” is usually used; instead of a “hyphrophobe”, a “xerophile” is used.
Typical euribionts are simple organisms, fungi. Among higher plants, species of temperate latitudes can be attributed to eurybionts: common pine, Daurian larch, Mongolian oak, Schwerin willow, lingonberry, and most species of heather.
Stenobiontism is produced in species that develop for a long time in 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.
In nature, there is no place where one factor acts on the body. All factors act simultaneously and the totality of these actions is called constellation. The values \u200b\u200bof the factors are not always equivalent. They may all be insufficient, and then there is general inhibition of biota (poor development of vegetation cover, decreased productivity, changes in the fractional structure of biomass, changes in other ecosystem indicators), but more often some of them are in abundance, even in the optimum, and others are in deficit. Moreover, the constellation is not a simple sum of the influence of factors, because 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 moisture demand and an increased need for nutrients. Moreover, this is observed in plants and animals. In plants with a lack of heat and waterlogging of the soil, nutrient elements become physiologically inaccessible, and increased soil fertility is required to ensure tolerance. Also in animals - to enhance the protective functions of the body in the cold, you need to eat well. So, always before laying down 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 reaction 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 \u200b\u200bbelow and above these limits - they hide.
However, the compensatory possibilities of the factors are limited. No factor can be completely replaced by another, and if the value of at least one of the factors goes beyond the upper or lower endurance limits of the biota component, the existence of the latter becomes impossible, no matter how favorable the other factors are.
EXAMPLE. The normal survival of the sika deer in Primorye takes place only in oak trees on the southern slopes, as here, the snow power is insignificant and provides the deer with sufficient food supply for the winter period. The limiting factor for deer is deep snow. The lack of heat limits the spread to the north of most species and formations of the Manchu flora: pine from densely flowered pine, whole-leaf fir and its formations are common only in Southern Primorye. And in the permafrost distribution zone, larch prevails everywhere. For cedar dwarf elder and Kamchatka alder, the decisive propagation factors are high air humidity and overwintering conditions. They tolerate frosty winters only if there is a thick snow cover that 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 Sea of \u200b\u200bOkhotsk and the Bering Sea, and in the continental districts - in the subalpine belt at an altitude of at least 1000 m / n. In the early stages of development, the limiting factor in conifers may be excess light. All of them, even the grave pine, require shading in the first years of life.
In the mid-19th century (1846), the German agricultural chemist Liebig deduced the "law of the minimum." In an experiment with mineral fertilizers, he found that those factors that are at a minimum in a given habitat have the greatest impact on plant endurance. He wrote in 1955: "Elements that are completely absent or not in the right amount prevent other nutrient compounds from producing an effect or reduce their nutritional effect." This is true not only for batteries, but also for other vital factors. Liebig's law is applicable only in the stationary state of the ecosystem, i.e. when the influx of matter and energy into the system is balanced by their outflow.
A factor whose level is close to the endurance limits of a particular organism, species, and other components of a biota is called limiting. And it is to this factor that the body adapts (produces 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, goes beyond the upper endurance limit of the organism (ecosystem).
Under pessimal conditions, there are several limiting factors, and their general inhibitory effect may be higher than the total inhibitory effect of individual factors.
EXAMPLE with southern slopes - insolation increases the dryness of the environment, prevents the increase in soil fertility.
Often the limiting factor is at one of the stages of development of the species. As you know, juvenile individuals are the most vulnerable and for them limiting factors may some. In different geographical zones, the limiting factors are different: in the Far North - more often it is warm, in the southern regions - moisture. Different species respond differently to the same factor. By the reaction of their adult individuals to a particular factor, it is possible to construct an ecological series (in descending order or increase in the action of the factor).
An EXAMPLE of the ecological range of tree species in terms of shade tolerance: larch - white birch - aspen - willow - linden - oak - daur birch - ash - maples - alder - elm - hornbeam - spruce - cedar - fir. The ecological series of forest types (by heat supply): larch (L.) grassy - L. green moss - L. lingonberry - L. sphagnum (Fig. 3). The ecological series of forest types (by moisture): elmovnik (or ashberry), large grass and fern - oak wood (D.) with motley birch - D. sedge - D. rhododendron sedge - D. mariannik-sedge - D. sedge rare-cover (Fig. 4 )
Within the population, it is also possible to distinguish individuals who are the most and least sensitive to the same factor. This is due to a combination of hereditary (genetic) and acquired (phenotypic) traits of organisms. Due to the environmental identity in populations, there are individuals with different viability. The most resilient survive periods of adverse conditions, contributing to the conservation of the species in extreme conditions.
4.5. Rule of advance V.V. Alekhine
Set nerd you. You. Alekhine (1951). The same communities are zonal in one zone and extrazonal in others. In the second case, outside the northern borders of the range, they occupy the most favorable habitats for themselves, outside the southern borders - 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 thickets with sphagnum cover grow, and on the warm southern slopes, larch moss-lichen woodlands (Chukotka) and stony-birch forbs (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 with densely flowered (grave) and apricot trees, which on the outskirts turn into forest-steppe communities.
The revealed pattern is of great importance, because allows you to accurately describe the vegetation of unexplored territories and reconstruct its former appearance in the places where it was destroyed.
Station - the habitat of a population of a species that is inherent in environmental conditions that meet the requirements of the species. Each species has its own set of stations. Within the same zone and time period, the species occupies one station. With the transition to another zone or with the transition to a different age stage, the species may change stations. The rule of zonal habitat change was established by entomologist Grieg. Yakovl. Bey-Bienko (1966). In the northern regions, many species of insects usually behave like hygrophobes, occupying drier, thinner areas, while in the southern regions they are hyphrophytes, settle in moist, shady places, with dense vegetation cover (migratory locust). Another example is lasia ants (Lasius niger, L. flavus) in humid meadows populate hummocks, and in dry meadows in the steppes, they prefer wetter habitats. A zonal change of habitat is also characteristic of plants.
So, the cedar dwarf tree in Southern Primorye grows only in the subalpine zone at an altitude of 1000-1100 m to 1400-1600 m above sea level, with a move to the north it goes down and forms a dense undergrowth in valley larch forests. North 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 cedar dwarf elf.
4.7. The rule of zonal tiers M.S. Gilyarova
In different zones, the same species occupy different tiers. When moving north, they naturally move from the upper tiers to the lower, warmer, and some to the soil. This set the soil. Zoologist Mercur. Serg. Gilyarov.
EXAMPLE. Larvae of the stag beetle (Lucanus cervus) in the forest zone develop in decaying dead wood and stumps, and in the steppe they live in rotten roots to a depth of 1 m.
In addition to the zonal (spatial) change of habitats, temporary shifts occur: seasonal (during the month and even one day during microclimate fluctuations - during periods of drought or typhoons, insects and rodents either hide under the protection of crowns of shrubs and trees, or are selected in open places) and annual (in case of deviation of weather conditions from the average annual norms). Due to the change of habitats, species retain their ecological status in constantly changing conditions. At the same time, upon successful resettlement, 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 in evolution.
The principle of static fidelity and the principle of zonal and vertical change of habitats, opposite to it, indicate the complex connection of organisms with the environment. Studying them is very important for understanding the ecology of species, as the basis for the protection of rare and useful species and the fight against harmful species.
5. The environmental significance of abiotic factors
Under different environmental conditions, biological processes occur at different speeds. For example, the growth of many plants depends on the concentration of various substances (water, carbon dioxide, nitrogen, hydrogen ions).
The temperature example shows that this factor is carried 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 the temperature is close to these extremes, 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 Greek tolerance - patience) is 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.
Under different environmental conditions, biological processes in organisms occur at different speeds. 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 tolerance that will save nature from too unreasonable human exposure. In addition, there are still places on Earth relatively little affected by human influence. Therefore, by the time a person creates unbearable conditions for himself, some life will remain and continue evolution, if only a person does not tear the planet to shreds as a result of an atomic catastrophe. There are also plants that produce substances that lead to their own death.
Organisms with a wide range of tolerance are denoted by the prefix "heuris". Eurybiont is an organism that can live under various environmental conditions. For example: eurythermic is an organism that suffers wide temperature fluctuations. Organisms with a narrow tolerance range are denoted by the prefix "wall-". Stenobiont - an organism that requires strictly defined environmental conditions. For example: trout is a stenothermal species, and perch is eurythermic. Trout does not tolerate large temperature fluctuations, if all the trees along the banks of the mountain stream disappear, this will lead to a temperature increase of several degrees, as a result of which the trout will die, and the perch will survive.
When placing the body in new conditions, after a while it gets used to, 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: a crop may die in both arid and too rainy summers.
The law of the minimum.
The intensity of certain biological processes is often sensitive to two or more environmental factors. In this case, the decisive factor will belong to such a factor, which is available in a minimum quantity, in terms of the needs of the organism. This rule was formulated by the founder of the science of mineral fertilizers Justus Liebig (1803-1873) and was called the law of the minimum. Yu. Liebig discovered that plant yields can be limited by any of the main 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 others. If there is a lot of nitrogen, potassium and other nutrients in the soil, but there is not enough phosphorus (or vice versa), the plants will develop normally only until they absorb all the phosphorus.
Factors that restrain the development of organisms due to a shortage or excess compared to needs are called limiting.
The provision on limiting factors greatly facilitates the study of complex situations. Despite the complexity of the relationship between organisms and their environment, not all factors have the same environmental significance. For example, oxygen is a physiological factor for all animals, but from an environmental point of view, it becomes limited only in certain habitats. If a fish dies in a river, then the oxygen concentration in the water should be measured first, since it is highly variable, oxygen reserves are easily depleted, and often it is 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 from the point of view of the requirements of terrestrial organisms.
6. Adaptation of living organisms to environmental conditions.
According to the theory of C. Darwin, organisms are volatile. 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 the chromosomes that occur under the influence of environmental or internal factors. These changes in the signs of the body are spasmodic and inherited. The vast majority of these mutations are usually unfavorable, so almost all of them are recessive, that is, their manifestations disappear after a certain number of generations. However, all this set of changes is a reserve of heredity, the gene pool of a species or population, which can be mobilized through natural selection when changing the conditions of existence of populations.
If the 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 that lead to less variability of traits, as well as mutations that contribute to energy saving due to getting rid of functions that have become “superfluous” under constant conditions. This contributes to 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 significance. So the whales lost their hind limbs, the lancelet does not have its own digestive organs, etc. In exchange for the lost, new organs may be acquired.
When environmental conditions change, environmental pressure on the population forms, and the carriers of such mutations that “guessed” those changes that are more favorable for new environmental conditions than the initial forms are most likely to survive. They give the greatest offspring, in which there is an even greater refinement of forms that satisfy the new state of the environment. As a result, with each new generation, forms gradually change. This natural selection is called driving.
Minor evolutionary changes that contribute to better adaptation to certain environmental conditions are called ideal adaptation. These are various private devices: protective coloration, flat shape of bottom fish, adaptation of seeds to dispersal, leaf degeneration in thorns to reduce transpiration, etc. Ideoadaptation usually results in small systematic groups: species, genera, and 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 a major revolutionary change in the structure of the biosphere, apparently caused by global changes in the environment.
Arguing 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 act on the cells of our organisms as a supersystem, forcing them to adapt to external conditions for them in those 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 tissues, adapting to new conditions, begin to grow and become stronger in response to these loads. Exposure can occur along a more complex chain, for example, in case of fright, adrenaline is released into our bloodstream, 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 of influence on internal subsystems by changing environmental factors for these subsystems is, apparently, a fairly universal mechanism of influence of any supersystem on its internal organization.
Most likely, the intracellular level is no exception. If the cell of our body falls into altered conditions, and these changes are either fixed or periodically repeated, then the cell tries to adapt to new conditions by 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 external conditions for them. It is possible that, with some effects on the body, almost the entire genetic apparatus in all cells undergoes a certain effect, which leads to completely 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 be random at all, but quite directed. Then the theory of natural selection acquires a slight adjustment: Among the mutations present in the population at a specific change in environmental conditions, those that are directly initiated by this change predominate. That is, the mutations themselves are, apparently, directed and designed to find new forms that meet the requirements of a changing environment. And since the answer 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 particular mutation of any trait is of a chain nature. That is, having arisen once in the offspring of one pair, a successful mutation is “contagious” for other pairs of parents giving their offspring, but with the same successful mutations. As a result, for one generation within the framework of the species, different parents can have children with the same characteristics that differ from the characteristics of the 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, almost at the same time, and immediately turns out to be represented by a large enough number of individuals for stable reproduction. True, so far this is only a hypothesis.
Such processes appear, apparently, in those very periods of serious environmental changes that threaten the extinction of this species. It was then that the “whorl” was formed, that is, a huge number of mutations appeared, the purpose of which was: to find the right solution, a new form. And this solution will certainly be found, because, as we have already said, for this, life involves the “technique of trial grope”, which is “a specific and irresistible weapon of any expanding multitude” (Teilhard de Chardin's terminology). Mutations fill the entire possible space of variants of new forms, and then the environment itself determines which of these forms will become fixed in life and which will disappear without passing the test of natural selection. Sometimes such a whorl generates a whole bunch of new phyla, that is, evolutionary branches, which are different answers to the same change in the environment.
Adaptation of organisms to environmental factors is caused not only by evolutionary rearrangements occurring in the biosphere. Often organisms 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. Due to the interaction between organisms and natural selection, the entire community becomes programmed for various kinds of natural rhythms. In these cases, environmental factors act as a kind of synchronizer 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) repeated without strict periodicity (floods, hurricanes, earthquakes, etc.);
3) unidirectional factors (climate change, waterlogging, etc.);
4) random and uncertain factors, the most dangerous for the body, as they are often found 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 interpretation. That is, the requirement of a supersystem in this case is quite understandable.
A special case of such adaptations to repetitive factors is, for example, photoperiodism - this is the reaction of the body to the length of daylight in the temperate and polar zones, which is perceived as a signal for changing phases of development or behavior of organisms. Examples of photoperiodism are phenomena such as leaf fall, molting of animals, bird flights, etc. In relation to plants, usually short-day plants are distinguished that exist in the southern latitudes, where during the long growing season the day is relatively short, and long-day plants characteristic of the northern latitudes, where during the short growing season the day is longer.
Another example of adaptation to the periodicity of natural phenomena is daily rhythm. For example, in animals, when day and night change, respiratory rate, heart rate, etc., change. For example, gray rats are more labile in their daily rhythm than black ones, therefore they are easier to master new territories, having already populated almost the entire globe.
Another example is seasonal activity. This is not necessarily a change of seasons, but also a change, for example, of the doge season and drought, etc.
Adaptations to tidal rhythm, which is associated with both solar and lunar days (24 hours 50 minutes), are also interesting. Daily ebbs and flows are shifted by 50 minutes. The strength of the tides changes during the lunar month (29.5 days). With the new moon and full moon, the tides reach a maximum. All these features leave an imprint on the behavior of the littoral organisms (tidal zone). For example, individual fish lay eggs at the boundary of the maximum tide. The release of fry from eggs is confined 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 body may be disrupted. For example, ostriches in Ukraine can lay eggs directly in the snow.
Mechanisms of adaptation to the periodicity of processes may 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 dormant eggs appear, giving larvae only next spring, no matter how favorable food and other conditions are. Thus, population growth is constrained even before food stocks become a limiting factor.
Adaptation to factors recurring without strict periodicity is much more complex. Nevertheless, the more characteristic this factor is for nature (for example, fires, severe storms, earthquakes), the more specific adaptation mechanisms life finds for them. For example, in contrast to the length of the day, the amount of precipitation in the desert is completely unpredictable, however, some annual desert plants usually use this fact as a regulator. Their seeds contain a germination inhibitor (an inhibitor is 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 this plant from seed germination to the maturation of new seeds.
In relation to forest fires, plants also developed special adaptations. Many plant species invest more energy in underground storage organs and less in reproductive organs. These are the so-called “recovering” species. Species “dying in maturity," on the contrary, produce numerous seeds, ready to germinate immediately after a fire. Some of these seeds have been lying in forest litter for decades without sprouting or losing germination.
The most dangerous for living organisms are factors of indeterminate action. 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 enhances the sustainability of existence. But subtle chronic disturbances, especially characteristic of anthropogenic impact on nature, give weak reactions, therefore 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 effects of chronic stress beyond the limits after which the ecosystem is destroyed. Industrial waste containing new chemicals that nature has not yet encountered is especially dangerous. One of the most dangerous stressors is thermal pollution of the environment. A moderate increase in temperature can have a positive effect on life, but after a certain limit, stress effects begin to appear. This is especially noticeable in water bodies directly related to thermal power plants.
Ecological valency, the degree of adaptability of a living organism to changes in environmental conditions. Ecological valency is a species property. Quantitatively, it is expressed by the range of environmental changes within which this species maintains normal life. Ecological valency 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, species that undergo wide changes in the strength of the influencing factor are indicated by the term consisting of the name of this factor with the prefix “evry” (heurythermic in relation to the influence of temperature, euryhaline in relation to salinity, eurybate in relation to depth, etc.); species adapted only to small changes in this factor are denoted by a similar term with the prefix “wall” (stenothermal, stenohaline, etc.). Species with a wide ecological valency with respect to a complex of factors are called eurybionts, as opposed to stenobionts, which have little adaptability. Since eurybiontism makes it possible to populate a variety of habitats, and stenobiontism sharply narrows the range of suitable stations for the species, these two groups are often called respectively euryly or stenotopic.
Human 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. The general pattern of action of biotic factors
An important role in the life of each community is played by the living conditions of organisms. Any element of the environment that has a direct effect 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, light, soil properties, water composition.
Food is considered an important environmental factor for animal populations. The quantity and quality of food affect 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 a variable body temperature. For example, titmouse blue tit, with a body weight of 11 g, needs to consume food at a rate of 30% of its weight annually, singing thrush with a mass of 90 g - 10%, and buzzard with a mass of 900 g - only 4.5%.
Biotic factors include various relationships between organisms in the natural community. Distinguish the relationship of individuals of one species and individuals of different species. The relationships of individuals of one species are of great importance for its survival. Many species can breed normally only when they live in a fairly large group. So, cormorant normally lives and breeds, if in its colony there are at least 10 thousand individuals. The principle of minimum population size explains why rare species are difficult to save from extinction. For the survival of African elephants in the herd must be at least 25 individuals, and reindeer - 300-400 goals. Living together facilitates the search for food and the fight against enemies. So, only a pack of wolves can catch large-sized prey, and a herd of horses and bison can successfully defend themselves from predators.
At the same time, an excessive increase in the number of individuals of one species leads to overpopulation of the community, increased competition for territory, food, and leadership in the group.
The study of the relationship of individuals of one species in the community is engaged in population ecology. The main task of population ecology is to study the number of populations, its dynamics, causes and consequences of changes in numbers.
Populations of different species, living together for a long time in a certain territory, form communities, or biocenoses. The community of different populations interacts with environmental environmental factors, together with which it forms a biogeocenosis.
A limiting or limiting environmental factor, i.e., a lack of one or another resource, has a great impact on the existence of individuals of one and different species in a biogeocenosis. For individuals of all species, the limiting factor may 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 by high air temperatures. The study of the limiting factors involved in applied ecology.
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 established that the limiting factor for the larvae of the nutcracker is very low or very high soil moisture. Therefore, to combat this pest of agricultural plants, drainage or strong moistening of the soil is carried out, which leads to the death of larvae.
Ecology studies the interaction of organisms, populations, communities among themselves, the impact on them of environmental factors. Autecology studies the relationships of individuals with the environment, and synecology studies the relationships of populations, communities, and habitats. Distinguish between abiotic and biotic environmental factors. For the existence of individuals, populations, limiting factors are important. Greatly developed population and applied ecology. Ecological advances are used to develop conservation measures for species and communities in agricultural practice.
Classification of biotic interactions:
1. Neutralism - no population affects 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 is small, then intraspecific competition is weak and resources are abundant.
With a high population density, intense intraspecific competition reduces the availability of resources to a level that restrains further growth, thereby regulating the population size. Interspecific competition is the interaction between populations that adversely affects their growth and survival. When the Caroline squirrel was imported from North America to Britain, the number of ordinary squirrel decreased, because
caroline protein was more competitive. Competition is direct and indirect. Direct - this 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 grass plants in California.
1. Biosphere: the functions of living matter.
Composition of living matter is the totality of living organisms living in the biosphere. Living matter has biomass, has productivity and has properties that are special compared to inert matter. These properties provide the most important functions of living matter.
1. Energy function. It is determined by the properties of the photosensitive substance chlorophyll of green plants, with the help of which plants capture, accumulate solar energy, and convert it into the energy of chemical bonds of 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. The nutritional interactions of living matter lead to the displacement of huge masses of chemical elements and substances against gravity and in the horizontal direction. This movement is the transport function of living matter.
3. Destructive function. The mineralization of organic substances, the decomposition of dead organics into simple inorganic compounds, determines the destructive function of living matter. This function is mainly performed by fungi, bacteria.
4. Concentration function there is an accumulation of certain substances in living things. Shells of mollusks, shells of diatoms, animal skeletons are all examples of the manifestation of the concentration function of living matter.
5. Living matter transforms the physicochemical parameters of the medium. This is another major function of living matter - environmentdeveloping. For example, forests regulate surface runoff, increase air humidity, and enrich the atmosphere with oxygen.
8.2. Biosphere: global biogeochemical circulation of substances, energy flows.
Life has existed for billions of years. Inorganic matter is constantly consumed from the environment. During this time, it could be used up, because the amount of matter on Earth is finite. The final amount of matter in the biosphere acquired the property of infinity through the cycle of matter. The nutrition, respiration and reproduction of organisms and the processes of creation and accumulation of decay of organic matter associated with them provide a constant circulation of matter and energy.
The biogeochemical circulation of substances is a repeating interconnected physical, chemical and biological processes of transformation and movement of matter in nature.
The driving forces of the biogeochemical cycle are the energy flows of the sun and the activity of living matter. As a result of the biogeochemical cycle, huge masses of chemical elements are moved, and the energy accumulated during photosynthesis is concentrated and redistributed.
The biogeochemical cycle 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 whole 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 reducers. In this case, the corresponding trophic levels are formed.
With each subsequent 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 greater the amount of energy available.
Thus, life on our planet is carried out as a constant cycle of matter, supported by the flow of solar energy.
The biosphere is closely related to the space environment. Every second, more than 1000 charged particles fly into the area of \u200b\u200b1 m² across the boundary of the Earth’s atmosphere from space in the direction of the Earth’s surface. Cosmic radiation could in a short time decompose all the air in the atmosphere into ions and electrons. Life on Earth would be impossible. However, this does not happen, since the Earth is protected from cosmic rays by a magnetic field. The lines of the earth's magnetic field reflect cosmic rays with low energy, and they, as a rule, cannot penetrate into the lower layers of the atmosphere. Only cosmic rays with very high energy are capable of breaking through the Earth’s magnetic field and reaching the surface of the Earth, regardless of geographic latitude.
In the magnetosphere, charged particles are mainly held by magnetic field lines. When the next portion of particles arrives, some of them “shake” 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 - a blue gas with a pungent odor. Its height 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 decay into free atoms, which can attach to its other molecules. Another reaction is also possible - free oxygen atoms can attach to ozone molecules with the formation of two oxygen molecules. In the stratosphere, ozone absorbs ultraviolet rays of solar radiation, thereby protecting all life. In recent years, the ozone layer has been depleted. The main reason for the depletion is the use of chlorofluorocarbons - freons, which are widely used in production and everyday life as refrigerants, blowing agents, solvents, aerosols. Freons catalyze the decomposition of ozone, upsetting the balance between it and oxygen towards a decrease in ozone concentration.
8.4. Biosphere: biological diversity.
Life as a stable planetary phenomenon is possible only when it is of different quality.
The biological diversity of the biosphere includes the diversity of all types of living creatures that inhabit the biosphere, the diversity of genes that form the gene pool of any population of each species, as well as the diversity of ecosystems of the biosphere in various natural zones.
The amazing diversity 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, large biomass and productivity. Such species are called dominant. Rare or small species have low abundance and biomass. As a rule, dominant species are responsible for the main energy flow and are the main environment-forming agents that strongly influence the living conditions of other species. Small species make up a reserve and, if various external conditions change, they can fall into the dominant species or take their place. Rare species mainly create species diversity.
In 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 unit area. For example, in two communities, under equal conditions, 100 individuals live. But in the first, these 100 individuals are distributed between ten species, and in the second - between three species. In the given example, the first community has a richer species diversity than the second.
Suppose that in the first and second communities there are 100 individuals and 10 species. But in the first community, individuals between species are distributed by 10 in each, and in the second - one species has 82 individuals, and the rest 2.
As in the first example, the first community will have a more even distribution of individuals than the second.
The conservation of biological diversity is an indispensable condition for the conservation and development of natural ecosystems, the existence of life as a whole.
8.5. Biosphere: mechanisms of sustainability.
The biosphere is an open system that exchanges matter and energy with the environment. This is possible because in the ecosystem there are 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 is a property of the ecosystem, which is manifested in the maintenance of its composition, structure and functions, as well as in the ability to recover if they are violated. The stability of the biosphere is determined by:
- the exceptional diversity 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 informational, material and energy connections between living and inert matter, as well as the relationship of the biosphere with space, geospheres, and the processes of the global biogeochemical cycle.
The existence of each species depends on many other species, the destruction of one of the species may lead to the disappearance of other species associated with it. Individuals of one species and their metabolic products, as well as their dead bodies, are food for other species, which ensures self-cleaning of ecosystems.
The socio-economic development of society has come and a clear contradiction with the limited resource-reproducing and life-supporting capabilities of the biosphere. The depletion of the natural resources of land and the ocean, the irretrievable loss of plant and animal species, environmental pollution, the simplification and degradation of ecosystems. Therefore, humanity is looking for ways of sustainable development of society and nature.
8.6. Biosphere: the danger of depleting the biological diversity of species and ecosystems
Biological diversity - genetic, species, ecosystem - is the root cause of the sustainability of both the biosphere as a whole and each individual ecosystem. Life as a stable planetary phenomenon is possible only when it is represented by diverse species and ecosystems.
But in modern conditions, the scale of human economic activity has grown so much that there is a danger of loss of biological diversity. Different types of human activity 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 building deprive wild animals of their habitats. Irrigated land cultivation reduces yields due to erosion and depletion of soil fertility. Abundant field irrigation can lead to salinization, i.e., to an increase in the concentration of salts in the soil to a level not tolerated by plants. As a result, typical plants of these places disappear. Deforestation in large areas in the absence of reforestation leads to the destruction of habitats of wild animals, change of vegetation, and reduction of its diversity. Many species disappear due to their extermination, as well as due to environmental pollution. Most species disappear due to the destruction of natural habitats, the destruction of natural ecosystems. This is one of the main reasons for the depletion of biological diversity.
Under the biological diversity of the biosphere, we understand the diversity of all types of living organisms that make up the biosphere, as well as the whole variety of genes that form the gene pool of any population of each species, as well as the diversity of ecosystems of the biosphere in various natural zones. Unfortunately, at present, all kinds of human activities lead to a decrease in biological diversity. The biosphere is losing biodiversity. This is one of the environmental dangers.
Humanity still does not know much about biological diversity, for example, there is still no exact data on the number of species in the biosphere. Specialists still cannot always determine which territories require special protection measures and the organization of nature reserves on them. A huge number of poorly studied species, for example in tropical forests.
To preserve biodiversity, it is necessary to invest in its study; improve environmental management, trying to make it rational; solve global environmental problems at the international level.
UNESCO adopted the World Heritage Convention, which combines natural and cultural monuments. The Convention calls for the care of objects that are of value to all of humanity. The conservation of biodiversity depends on the leaders of countries, and on the behavior of each inhabitant of the planet.
9 Sustainability of the environment (ecosystems) in Russia.
Sustainability is one of the most important parameters of any systems, including environmental ones. It determines the ability of the system to maintain itself when environmental changes. In the context of this definition, sustainability can be considered synonymous with the term vitality. The theoretical foundations of a qualitative and semi-quantitative assessment of the stability of complex systems are described in the Web atlas “Russia as a system”. In the most general form, this work shows that the viability of systems is determined by three groups of its parameters - volume (mass of the substance of the system), productivity (speed of self-reproduction of the substance of the system) and structural harmony. As applied to ecological systems, the quantitative measurement of the first two groups of parameters is well established by classical biogeography. Methods for calculating the structural harmony of ecosystems (the third component) were developed by us and are presented in the “Atlas of biological diversity of European Russia and adjacent territories” (M., PAIMS, 1996).
The level of potential sustainability of the indigenous ecosystems of Russia, that is, the level of sustainability of ecosystems before they are transformed by humans, is shown on the following map
The maximum stability falls on the forest-steppe of European Russia, the Cis-Urals and the middle taiga of Siberia, and the stability of systems decreases to the north and south. The minimum in Russia is observed in the Arctic deserts. Since only the very edge of the Turanian deserts enters Russia, their level of stability is still quite high.
The European forest-steppe - a combination of oak forests and meadow steppes - is undoubtedly the optimal zone of life within Russia. As for Siberia, the retreat here of maximum stability to the north, of course, is associated with the general ecological youth of the local forest-steppe. Recall that while in the European forest-steppe the main forest-forming species is oak - the climacteric species - the final stage of ecological succession, in Siberia it is replaced by birch - the pioneer species, the first settling in non-forest areas.
The high stability potential of indigenous ecosystems in the 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 sustainability 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 its area, indigenous ecosystems of stable types continue to ensure the invariability of the regime of natural cycles, biomass production, and utilization of substances harmful to living organisms. This feature is associated with the original role of soils — reservoirs of the “memory” of an ecosystem — 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 sustainability of Russia's ecosystems is almost everywhere reduced to some extent due to the replacement of indigenous ecosystem types, less stable anthropogenic derivatives (agrocenoses or secondary forests) or complete destruction during development and urbanization. Moreover, the maximum impact area is characteristic precisely for areas with the most stable natural complexes. In Russia they say: - “Those who are lucky will be brought down on him.” Stable ecosystems of the southern taiga and forest-steppe of Russia retained the possibility of a fairly autonomous development of industrial civilization of the last century and a half, without any external support, despite the maximum loss of natural complexes.
The steppes of the European part of Russia were secondarily (after casting during a period of serious threat from the steppe nomads in the 13th-17th centuries) mastered in the 18th-19th centuries, that is, against the background of a fairly highly developed agriculture. On the other hand, having the highest and most stable productivity, these steppes during the socialist period experienced the most severe consequences of the pursuit of the growth of arable wedges, “the struggle against the grass field system”, etc. At the same time, the ecosystem’s sustainability reserve provided economic development opportunities with radical modernization and an increase in the human energy capacity. It is characteristic that regions with a high stability of natural conditions correlate to a large extent with areas of high stability (viability) of society. On the contrary, in the more southern steppes and semi-deserts (Caspian littoral) and in the north - in the tundra, natural conditions, due to biota's own instability, significantly limit human arbitrariness in choosing options and the intensity of economic activity. Accordingly, the socium of these regions is much less stable. It is with this that the preferential preservation of traditional forms of environmental 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 areas. These enclaves look like a foreign body within a region and most destructively affect its nature.
Despite the high level of sustainability of the ecosystems of the southern taiga and forest-steppe of European Russia, the threat of loss of natural balance and unpredictable destruction of all forms of management (especially agriculture) of these areas were recognized back in the Stalin period. At the end of the 40s. The plan for the massive creation of forest belts and artificial reservoirs was adopted. The implementation of the plan was to significantly increase the sustainability of ecosystems in the steppes of southern Russia. Unfortunately, the plan was not fully implemented. But even in its realized part, it did not completely achieve the desired results, since part of the forest belts was planted by the “nesting method” of TD Lysenko and died almost immediately, sufficient funds were not allocated from the very beginning for the creation of ponds, and for the most part were broken by the first high flood. As the plan was forgotten, and the shortage of bread in the country increased, mass reduction of forest belts began - large tractors are more convenient to process large tracts of forest and forest belts prevented.
The last map shows an indicator reflecting the current level of ecosystem sustainability, taking into account both the loss of area of \u200b\u200bindigenous natural complexes and the decrease in the viability of anthropogenic ecosystems (agrocenoses, secondary forests, etc.). The map shows that in the regions with the most favorable (comfortable) living conditions of a person and economic development, the possibilities of development due to the resources of the natural environment are practically exhausted. This cannot but cause serious concerns - the main region is the donor population of the country and one of the three main centers of stability of its society is in the zone of maximum decrease in the sustainability of ecosystems. A decrease in stability increases its vulnerability to anthropogenic transformation, which is extremely dangerous for maintaining the health of not only the population of the Black Earth Region, but also Russia as a whole.
In this regard, of the three main centers of increased vitality of society, the North Caucasus 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 most close. Perhaps it is precisely the higher preservation of the sustainability of its ecosystems that contributes to the success of its struggle with the actual Russian centers.
Conclusion
For an ecosystem consisting of many species of different evolutionary levels, the influence of the whole complex of biotic factors always represents a complex system of interactions, in which, for example, the microclimate on the soil surface largely depends on the species composition and degree of development of the upper layers of vegetation, burrowing animals change conditions of aeration and drainage of the soil and affect the conditions of existence of vegetation.
A complete account of all the interactions of abiotic and biotic factors in natural ecosystems is almost impossible, so in real conditions it is necessary to confine oneself to analysis of only the most important factors that determine not specific features, but only the type of ecosystem.
This allows us 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 activity. The specific course of such changes should always be monitored in real time by a monitoring system of the natural environment - regular monitoring of ecosystem parameters.
The main task of creating this work was to familiarize ourselves with the concept of ecosystems in ecology, the factors influencing them and the problems of their relationship with humans. Having done this work, I tried to convey the importance and relevance of the problems associated with ecosystems, gave examples and solutions to these problems. The basic laws of ecology have also been described, examining in detail the factors affecting the human environment. The relevance of my work is clear! Each person needs to know the basic laws, processes, features, occurring and characteristic of ecosystems, and ecology as a whole. All this is necessary 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
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- Ecology. Tutorial. M: Knowledge 1997
- Gorelov A.A. Ecology: a training manual. - M .: Center. 1999.
- Gulyaev S.A., Zhukovsky V.M., Komov S.V. Fundamentals of natural science. / Tutorial. - Yekaterinburg .: UralEcoCenter, 2001 .-- 560 p.
- Moiseev N.N. Man and the biosphere. - M .: Young Guard, 1995 .-- 302 p.
- Nikolaykin N.N., Nokolaykina N.E., Melekhova O.P. Ecology. - M.: Bustard, 2004.
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Annex 1
Appendix 2
The effect of the temperature factor on living organisms
The cycle of substances in nature.
1. Biochemical cycle.
2. The cycle in the biosphere.
3. The carbon cycle.
4. The 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.
In contrast to the energy that is used by the body, it is converted into heat and lost to the ecosystem, substances circulate in the biosphere, this is called biochemical cycles. Of the 90-odd elements 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 for respiration. Nitrogen is drawn from the atmosphere due to the activity of nitrogen-fixing bacteria and returned to it by other bacteria.
The circulation of elements and substances is carried out due to self-regulating processes in which all composite ecosystems take part. These processes are hopeless. There is nothing in vain or harmful in nature, even there is a benefit from volcanic eruptions, since with the volcanic gases necessary elements, for example, nitrogen, enter the air. There is a law of global closure of the biochemical circuit in the biosphere, acting at all stages of its development, as well as the rule of increasing the closure of the biochemical circuit in the gait of succession. In the process of evolution of the biosphere, the role of biological components in the closure of the biochemical circuit increases. A person plays an even greater role in the biochemical circuit. But her role is carried out in the opposite direction. Man strengthens the circulation of substances that has already taken shape, and this is reflected in his geological power, which is destructive in relation to the biosphere today.
When 2 billion years ago life appeared on Earth, 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 the products on average exceeded respiration, over the geological time, oxygen was accumulated in the atmosphere and the content of carbon dioxide decreased. Today, the carbon dioxide content in the atmosphere is increasing as a result of burning large quantities of fossil fuels and reducing the absorptive capacity of the "green belt". The latter is the result of a decrease in the number of greenest plants, and is 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 isolation of biochemical circuits decreases. Although it is quite high (for various elements and substances it is not the same), but nonetheless not absolute, which shows an example of the appearance of an oxygen atmosphere. Otherwise, evolution would have been impossible (the highest degree of isolation of biochemical circuits is observed in tropical ecosystems - the oldest and most conservative).
Thus, one should speak not of a person changing what should not be changing, but rather of a person’s influence on the speed and direction of changes and on the spread of their boundaries, which raises the rule of nature’s transformation measure. The latter is formulated in this way: during the operation of natural systems, certain boundaries that allow these systems to maintain equilibrium cannot be exceeded.
2) Cycles of matter in the biosphere.
The processes of photosynthesis of organic matter from inorganic components last millions of years and during this time the chemical elements had to move from one form to another. However, this does not happen due to their circuit in the biosphere. Annually, photosynthetic organisms metabolize 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 (calculated on dry weight).
Huge amounts of water pass through plants and algae in the process of ensuring transport function 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 of the ocean - approximately than a year. All atmospheric carbon dioxide 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 number of other elements (potassium, sodium, calcium, magnesium, sulfur, iron, etc.) are included in the circuit by photosynthesis. The existence of these circuits gives ecosystems a certain duration.
There are two main circuits: large (geological) and small (biological).
A large circuit, lasting millions of years, consists in the fact that rocks are subject to destruction, and weathering products (including water-soluble nutrients) are carried by streams of water to the World Ocean, where they form marine strata and only partially return to land with precipitation . Geotectonic changes, the processes of lowering the continents and raising the seabed, the movement of the 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) takes place at the ecosystem level and consists in the fact that nutrients, water and carbon are accumulated in the plant matter, are spent on building the body and life processes of both these plants and other organisms (usually animals), who eat 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 that they are drawn into the flow of matter. The circulation of chemicals from an inorganic medium through plant and animal organisms back to the inorganic medium using solar energy and the energy of chemical reactions is called the biochemical cycle. Almost all chemical elements are drawn into such cycles, and especially those that take part in the construction of a living cell. Thus, 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) Carbon cycle.
4)The water cycle
Water is in constant motion. Evaporating 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 the oceans, rivers, lakes, etc. Thus, the amount of water on Earth does not change, it only changes its shape - this is the water cycle in nature. Of all the precipitation, 80% goes directly to the ocean. For us, the remaining 20%, falling on land, is of most interest, since most of the human sources of water are replenished precisely due to this type of precipitation. Simply put, there are two ways to water that falls on land. Or it, gathering in streams, rivulets and rivers, ends up in lakes and reservoirs - the so-called open (or surface) sources of water intake. Or water, seeping through the soil and subsoil layers, replenishes groundwater reserves. Surface and groundwater are the two main sources of water supply. Both of these water resources are interrelated and have both their advantages and disadvantages as a source of drinking water.
The water cycle is one of the grandiose processes on the surface of the globe. It plays a major role in linking geological and biotic cycles. In the biosphere, water, continuously passing from one state to another, performs small and large cycles. Evaporation of water from the surface of the ocean, condensation of water vapor in the atmosphere and precipitation on the surface of the ocean form a small cycle. If water vapor is carried by air currents to land, the cycle becomes much more complicated.
In this case, part of the precipitation evaporates and enters the atmosphere, the other feeds rivers and water bodies, but eventually returns to the ocean by river and underground flow, 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, groundwater, and atmospheric moisture. Water is the most important component of all living things. Ground water, penetrating plant tissue during transpiration, brings in mineral salts necessary for the vital activity of the plants themselves.
The most slowed-down part of the water cycle is the activity of polar glaciers, which reflects the slow movement and early melting of glacial masses. The highest exchange activity after atmospheric moisture is characterized by river waters, which change on average every 11 days. The extremely fast renewability of the main sources of fresh water and desalination during the cycle are a reflection of the global process of water dynamics on the globe.
5) Carbon cycle
Carbon in the biosphere is often represented by the most mobile form - carbon dioxide. The source of 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 biosphere of the Earth 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, rock schists, dispersed organic matter, and sedimentary rocks. So, in the distant geological epochs hundreds of millions of years ago, a significant part of photosynthesized organic matter was not used either by consumers or reducers, but was accumulated and gradually buried under various mineral deposits. Being 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, which in particular - depended on the source material, duration and conditions of stay in the rocks. Now we are extracting this fossil fuel in huge quantities to meet energy needs, and burning it, in a sense, completes the carbon cycle. If this process in the history of the planet were not likely, humanity would now have completely different sources of energy, and maybe a completely different direction of the development of civilization.
In the second way, carbon migration is carried out by creating a carbonate system in various water bodies, where CO2 passes into H2CO3, HCO31-, CO32-. Then, using calcium dissolved in water (less often magnesium), CaCO3 carbonates are precipitated by biogenic and abiogenic pathways. Thick strata of limestone appear. Along with this large carbon cycle, there are a number of small carbon cycles on the surface of the land and in the ocean.
Within the land, where there is vegetation, atmospheric carbon dioxide is absorbed during photosynthesis in the daytime. At night, part of it is secreted by plants into the external environment. With the death of plants and animals on the surface, oxidation of organic substances occurs with the formation of CO2. A special place in the current cycle of substances is occupied by the massive burning of organic substances and the gradual increase in the carbon dioxide content in the atmosphere, associated with the growth of industrial production and transport.
6) Oxygen cycle
Oxygen is the most active gas. Within the biosphere, there is a rapid exchange of oxygen in the environment with living organisms or their residues after death.
In the composition of the Earth's atmosphere, oxygen takes second place after nitrogen. The dominant form of oxygen in the atmosphere is the O2 molecule. The oxygen cycle in the biosphere is very complex, because it enters into many chemical compounds of the mineral and organic worlds.
The free oxygen of the modern Earth’s atmosphere is a by-product of the photosynthesis 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. The time has come in the history of the Earth’s biosphere when the amount of free oxygen has reached a certain level and has been balanced in such a way that the amount of oxygen released becomes equal to the amount of oxygen absorbed.
7) Nitrogen cycle
When organic substances rot, a significant part of the nitrogen they contain is converted to ammonia, which, under the influence of nitrifying bacteria living in the soil, is then oxidized to nitric acid. The latter, reacting with carbonates located in the soil, for example, calcium carbonate CaCO3, forms nitrates:
2HN0s + CaCO3 \u003d Ca (NO3) 2 + COC + H0H
Some part of nitrogen is always released during decay in free form into the atmosphere. Free nitrogen is also released during the burning of organic substances, during the burning of firewood, 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 accessible to green plants (nitrates) goes into the inaccessible (free nitrogen). Thus, far from all of the nitrogen that was part of the dead plants returns back to the soil; part of it is gradually allocated in a free form.
A continuous decrease in mineral nitrogen compounds would long ago have led to the complete cessation of life on Earth, if processes that compensated for the loss of nitrogen did not exist in nature. Such processes include, first of all, electric discharges occurring in the atmosphere, during which a certain amount of nitrogen oxides is always formed; the latter give nitric acid with water, which turns into nitrates in the soil. Another source of replenishment of nitrogen compounds in the soil is the vital activity of the so-called nitrogen bacteria, which can absorb atmospheric nitrogen. Some of these bacteria settle on the roots of plants from the legume family, causing the formation of characteristic swelling - "nodules", which is why they are called nodule bacteria. By assimilating atmospheric nitrogen, nodule bacteria process it into nitrogen compounds, and plants, in turn, turn the latter into proteins and other complex substances.
Thus, a continuous nitrogen cycle takes place in nature. However, annually with the harvest, the most protein-rich parts of plants, for example grain, are removed from the fields. Therefore, fertilizers must be applied to the soil to compensate for the loss of the most important plant nutrition elements in it.
8) Phosphorus cycle
Phosphorus is part of genes and molecules that carry energy inside cells. In various minerals, phosphorus is contained in the form of an inorganic phosphation (PO43-). Phosphates are soluble in water, but not volatile. Plants absorb PO43- from an aqueous solution and incorporate phosphorus into various organic compounds, where it appears in the form of so-called organic phosphate. In food chains, phosphorus passes from plants to all other organisms in the ecosystem. At each transition, it is likely that the phosphorus-containing compound is oxidized in the process of cellular respiration to produce energy by the body. When this happens, the phosphate in the composition of urine or its analogue again enters the environment, after which it can again be absorbed by plants and begin a new cycle.
Unlike, for example, carbon dioxide, which, wherever it is released into the atmosphere, is freely transported in it by air currents until it is again absorbed by plants, phosphorus does not have a gas phase and, therefore, there is no “free return” to the atmosphere. Once in water, 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 amount, which also turns out to be near the coast. Oceanic deposits of phosphate rise over time as a result of geological processes, but this has been happening for millions of years.
Consequently, phosphate and other mineral soil biogens circulate in the ecosystem only if the waste products containing them are deposited at the absorption sites of this element. In natural ecosystems, this basically happens. When a person intervenes in their functioning, he breaks the natural cycle, transporting, for example, the crop, along with biogenes accumulated from the soil, over long distances to consumers.
9) 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 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 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, and in fossil coals - in the form of impurities of sulfur pyrites and less often in the form of sulfates. Sulfur in the soil is mainly in the form of sulfates; its organic compounds are found in oil.
Due to the oxidation of sulfide minerals in the process of weathering, sulfur in the form of sulfation is transferred by natural waters to the oceans. Sulfur is absorbed by marine organisms, which are richer in its inorganic compounds than freshwater and terrestrial.
Grade 9Ticket number 26
1. The cycles of chemical elements in nature (for example, carbon, oxygen and nitrogen). The role of living beings in the cycle of chemical elements.
The cycles of chemical elements on Earth are repeating processes of transformation and movement of substances in nature, which are more or less cyclical in nature. The total cycle of substances consists of separate processes (the cycle of water, gases, chemical elements), which are not completely reversible, because there is a dispersion of the substance, a change in its composition, etc.
With the advent of life on Earth, living organisms play a huge role in the cycle of substances (the cycle of oxygen, carbon, hydrogen, nitrogen, calcium and other biogenic elements). Global influence on the cycle of substances and chem. human activities have elements, as a result of which new and existing ways of migration of substances change in nature, new substances appear, etc.
A thorough study of the transformations of substances and energy in nature and taking into account the consequences of human activity is a necessary condition for preserving the environment.
Consider the cycles of some chemical elements
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 by fuel combustion, breathing, and rotting. Simpler substances are formed from them, including carbon dioxide. Carbon dioxide is released during the decomposition of certain inorganic substances, for example, during calcination of limestone. However, its amount in the atmosphere increases slowly. This is due to the fact that carbon monoxide (IV) is involved in photosynthesis and carbon atoms again become part of the organic substances of plants. Many of them are eaten by animals and humans. So there is a continuous carbon cycle in nature.
Minerals and rocks
(oil, natural gas, coal, graphite - burning,
limestone, dolomites - calcination), volcanic gases
carbon dioxide
plants
absorb carbon dioxide during photosynthesis,
carbon element goes into organic matter
animals
organic substances of plants are part of 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 as a result of oxidation reactions)
Oxygen cycle
The composition of the atmosphere over the past centuries has changed slightly. The composition of the air includes: 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 small changes in composition negatively affect living organisms.
Oxygen is consumed in huge quantities for many chemical reactions: respiration of living organisms, rotting processes; human activities: fuel combustion, smelting, cutting and welding of metals, many industries (drugs, nitric and sulfuric acids, fertilizers, synthetic fibers, explosives, plastics, etc.).
But still, the total mass of oxygen in the air does not noticeably change. This is due to the process of photosynthesis occurring in green plants in the light. As a result of photosynthesis, plants absorb carbon dioxide and produce oxygen. As a result of this process, the mass of oxygen in the air is replenished.
Atmospheric oxygen
plants, animals, people
absorb oxygen while breathing, and emit carbon dioxide
carbon dioxide
plants absorb carbon dioxide and produce oxygen,
this process is called photosynthesis
atmospheric oxygen
plants produce oxygen during photosynthesis
Nitrogen cycle
The chemical element nitrogen in the form of a simple substance makes up the majority of the atmosphere, which contains 78% by volume, is a part of organic substances, in particular, a part of proteins, of which living organisms are composed. In the soil, nitrogen is contained in the form of ammonium ions NH4 + and nitrate ions NO3-.
Green plants need nitrogen, it is the main nutrient along with phosphorus and potassium. Nitrogen affects the growth of green mass of plants, with a lack of nitrogen slows down and stops their growth. When growing plants, the soil is gradually depleted of nitrogen, and can become barren.
When rotting and burning organic matter, part of the bound nitrogen is released and goes into the atmosphere. However, under natural conditions, the content of bound nitrogen in the soil does not decrease; the mass of free nitrogen in the atmosphere also does not increase. How can this be explained?
It turns out that there are bacteria, both living freely in the soil and settling on the roots of legumes, which assimilate atmospheric nitrogen, converting it into organic compounds. Small amounts of nitrogen bind during lightning discharges: in this case, nitrogen oxides are formed, nitric oxide (IV), when combined with water, turns into nitric acid, which turns into nitrates in the soil.
As a result of these processes, the cycle of chemical elements in nature occurs. When harvesting, a significant part of nitrogen is removed from the fields, therefore, nitrogen fertilizers must be applied to the soil to make up for this decrease.
Atmospheric nitrogen
(nitrogen content in the atmosphere is constant, 78% by volume)
Nitrogen-fixing bacteria absorb nitrogen
turn it into nitrate and ammonium form and organic matter
Plants
(in plants, nitrogen is in the form of organic substances - proteins, plant protein serves as food for animals and humans)
Animals and man
Rotting, metabolic products, burning organic matter
Atmospheric nitrogen
So, having examined the cycles of some chemical elements, we were convinced that they are characterized by cyclicality, various links of animate and inanimate nature are involved in the cycle. As a result of the circulation of substances, a constant composition of the atmosphere, soil, and hydrosphere is maintained.
A large role in the circulation of substances is played by living organisms: plants, animals and humans. In green plants, inorganic substances turn into organic in the process of photosynthesis, in the animal body the proteins necessary for human life are created (animal proteins contain all amino acids). A person affects the circulation of substances by his economic activity, very often his influence harms nature.
Any unreasonable human intervention causes a violation of 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
Chemical elements travel like humans. However, the chemical elements have more vehicles because they use vehicles created by both nature and man. In nature, chemical elements move in the earth's crust together with magmatic melts, on the earth - in the form of fragments of rocks, with deep and surface waters, with living organisms.
Chemical elements are helped by people traveling by sending them with food (grain, fruits, vegetables), and raw materials for industry (iron ore, wood, coal) by rail, by plane and by sea.
Obstacles may arise in the way of chemical elements - geochemical barriers that cause them to accumulate in the earth's crust, soils, silts and living organisms. Chemical elements always travel together.
The nitrogen cycle in nature
During the decay of organic substances, a significant part of the nitrogen contained in them is converted to ammonia, which is then oxidized to nitric acid under the influence of living in the soil and trificating bacteria. The latter, reacting with carbonates in the soil, for example, calcium carbonate CaCO3, forms nitrates
2НNОз + СаСОз \u003d Са (NОз) 2 + СО 2 + Н 2 О
Some part of nitrogen is always released during decay in free form into the atmosphere. Free nitrogen is also released during the burning of organic substances, during the burning of firewood, 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 accessible to green plants (nitrates) goes into the inaccessible (free nitrogen). Thus, not all nitrogen that was part of the dead plants returns back to the soil, part of it is gradually released in its free form.
A continuous decrease in mineral nitrogen compounds would long ago have led to the complete cessation of life on Earth, if processes that compensated for the loss of nitrogen did not exist in nature. Such processes include, first of all, electric discharges occurring in the atmosphere, in which a certain amount of nitrogen oxides is always formed; the latter give nitric acid with water, which turns into nitrates in the soil. Another source of replenishment of nitrogen compounds in the soil is the vital activity of the so-called nitrogen bacteria, which can absorb atmospheric nitrogen. Some of these bacteria settle on the roots of plants from the legume family, causing the formation of characteristic swelling - "nodules", which is why they are called nodule bacteria. By assimilating atmospheric nitrogen, nodule bacteria process it into nitrogen compounds, and plants, in turn, turn the latter into proteins and other complex substances.
Thus, a continuous nitrogen cycle takes place in nature. However, annually with the harvest, the most protein-rich parts of plants, for example, grain, are removed from the fields. Therefore, fertilizers must be applied to the soil to compensate for the loss of the most important plant nutrition elements in it.
On the surface of the globe, oxidation processes constantly occur (respiration of plant and animal organisms, rotting), as a result of which free oxygen binds to other elements that make up organic substances and forms a variety of compounds, such as 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 the nature of the processes opposite to oxidation, as a result of which free oxygen is formed. Indeed, as shown by 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 formed organic matter and oxygen O 2 released into the atmosphere.
The released oxygen is consumed again during the oxidation of organic substances. The water and carbon dioxide formed during this oxidation are again transformed in green leaves in sunlight into organic substances and free oxygen, etc. This is how the oxygen cycle occurs in nature, i.e., its alternating entry into and release from compounds.
Phosphorus cycle
Plants can grow if the soil contains phosphates. But these salts, even in the most fertile soils, are few. Where a person does not interfere in the life of nature, phosphorus extracted by plants from the soil again returns to the soil when the remains of plants and animals rot. So the phosphorus cycle is carried out in nature.
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 into the composition of plant organic matter. A lot of carbon that has become part of plants is absorbed by animal and human organisms with plant foods. Part of plant-assimilated carbon 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 carbonates of the earth's crust, which in this case turn into bicarbonates.
Along with the processes of carbon dioxide binding, there are processes of its release into the atmosphere. A huge amount of carbon dioxide is formed 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 due to the activity of volcanoes, the release of gases from earth cracks and water sources. So in nature there is a continuous carbon cycle.
