A NEW LOOK Adaptations of organisms to living in the ground-air environmentLiving organisms in ground-air environment surrounded by air. The air has a low density and, as a result, a low lifting force, insignificant support and low resistance to the movement of organisms. Terrestrial organisms live in conditions of relatively low and constant atmospheric pressure, also due to low air density.
Air has a low heat capacity, so it heats up quickly and cools down just as quickly. The rate of this process is inversely related to the amount of water vapor it contains.
Light air masses have greater mobility, both horizontally and vertically. This helps to maintain a constant level of the gas composition of the air. The oxygen content in air is much higher than in water, so oxygen on land is not a limiting factor.
Light in conditions of terrestrial habitation, due to the high transparency of the atmosphere, does not act as a limiting factor, in contrast to the aquatic environment.
Ground-air environment has different humidity regimes: from the complete and constant saturation of air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. The variability of air humidity during the day and seasons of the year is also great.
Moisture on land acts as a limiting factor.
Due to the presence of gravity and the lack of buoyancy, the terrestrial inhabitants of the land have well-developed support systems that support their body. In plants, these are various mechanical tissues, especially powerfully developed in trees. Animals have developed both an external (arthropod) and an internal (chordate) skeleton during the evolutionary process. Some groups of animals have a hydroskeleton (roundworms and annelids). Problems in terrestrial organisms with maintaining the body in space and overcoming the forces of gravity have limited their maximum mass and size. The largest land animals are inferior in size and mass to the giants of the aquatic environment (the mass of an elephant reaches 5 tons, and a blue whale - 150 tons).
The low air resistance contributed to the progressive evolution of the locomotion systems of terrestrial animals. So, mammals acquired the highest speed of movement on land, and birds mastered the air environment, having developed the ability to fly.
High mobility of air in vertical and horizontal directions is used by some terrestrial organisms at different stages of their development for settling with the help of air currents (young spiders, insects, spores, seeds, plant fruits, protist cysts). By analogy with aquatic planktonic organisms, as adaptations for passive soaring in the air, insects have developed similar adaptations - small body sizes, various outgrowths that increase the relative surface of the body or some of its parts. Seeds and fruits dispersed by the wind have various pterygoid and paragayate appendages that increase their ability to plan.
The adaptations of terrestrial organisms to the preservation of moisture are also diverse. In insects, the body is reliably protected from drying out by a multilayer chitinized cuticle, the outer layer of which contains fats and wax-like substances. Similar water-saving adaptations are also developed in reptiles. The ability for internal fertilization developed in terrestrial animals made them independent of the presence of an aquatic environment.
The soil is a complex system consisting of solid particles surrounded by air and water.
Depending on the type - clayey, sandy, clayey-sandy and others - the soil is more or less permeated with cavities filled with a mixture of gases and aqueous solutions. In the soil, in comparison with the surface layer of air, temperature fluctuations are smoothed out, and at a depth of 1 m, seasonal temperature changes are also imperceptible.
The uppermost soil horizon contains more or less humus, on which plant productivity depends. The middle layer located under it contains washed out from the top layer and converted substances. The bottom layer is mother breed.
Water in the soil is present in voids, the smallest spaces. The composition of soil air changes dramatically with depth: the oxygen content decreases, and carbon dioxide increases. When the soil is flooded with water or intensive decay of organic residues, anoxic zones appear. Thus, the conditions of existence in the soil are different at its different horizons.
In the course of evolution, this environment was mastered later than the water. Its peculiarity lies in the fact that it is gaseous, therefore it is characterized by low humidity, density and pressure, high oxygen content.
In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations.
Animals in the ground-air environment move through the soil or through the air (birds, insects), and plants take root in the soil. In this regard, animals developed lungs and tracheas, while plants developed a stomatal apparatus, i.e.
organs by which the land inhabitants of the planet absorb oxygen directly from the air. The skeletal organs, which provide autonomy of movement on land and support the body with all its organs in conditions of low density of the medium, thousands of times less than water, have received a strong development.
Ecological factors in the terrestrial-air environment differ from other habitats in high light intensity, significant fluctuations in air temperature and humidity, the correlation of all factors with geographical location, the change of seasons of the year and time of day.
Their impact on organisms is inextricably linked with the movement of air and the position relative to the seas and oceans and is very different from the impact in the aquatic environment (Table 1).
Table 5
Living conditions of air and water organisms
(according to D. F. Mordukhai-Boltovsky, 1974)
| air environment | aquatic environment |
| Humidity | Very important (often in short supply) | Does not have (always in excess) |
| Density | Minor (except for soil) | Large compared to its role for the inhabitants of the air |
| Pressure | Has almost no | Large (can reach 1000 atmospheres) |
| Temperature | Significant (fluctuates within very wide limits - from -80 to + 100 ° С and more) | Less than the value for the inhabitants of the air (fluctuates much less, usually from -2 to + 40 ° C) |
| Oxygen | Minor (mostly in excess) | Essential (often in short supply) |
| suspended solids | unimportant; not used for food (mainly mineral) | Important (food source, especially organic matter) |
| Solutes in the environment | To some extent (only relevant in soil solutions) | Important (in a certain amount needed) |
Land animals and plants have developed their own, no less original adaptations to adverse environmental factors: the complex structure of the body and its integument, the frequency and rhythm of life cycles, thermoregulation mechanisms, etc.
Purposeful mobility of animals in search of food developed, wind-borne spores, seeds and pollen of plants, as well as plants and animals, whose life is entirely connected with the air, appeared. An exceptionally close functional, resource and mechanical relationship with the soil has been formed.
Many of the adaptations we have discussed above as examples in the characterization of abiotic environmental factors.
Therefore, it makes no sense to repeat now, because we will return to them in practical exercises
Soil as habitat
Earth is the only planet that has soil (edasphere, pedosphere) - a special, upper shell of land.
This shell was formed in a historically foreseeable time - it is the same age as land life on the planet. For the first time, the question of the origin of the soil was answered by M.V. Lomonosov ("On the layers of the earth"): "... the soil came from the bending of animal and plant bodies ... by the length of time ...".
And the great Russian scientist you. You. Dokuchaev (1899: 16) was the first to call soil an independent natural body and proved that soil is "... the same independent natural-historical body as any plant, any animal, any mineral ... it is the result, a function of the cumulative, mutual activity of the climate of a given area, its plant and animal organisms, the relief and age of the country ..., finally, the subsoil, i.e.
ground parent rocks. ... All these soil-forming agents, in essence, are completely equivalent in magnitude and take an equal part in the formation of normal soil ... ".
And the modern well-known soil scientist N.A.
Kachinsky ("Soil, its properties and life", 1975) gives the following definition of soil: "Under the soil should be understood all the surface layers of rocks, processed and changed by the combined influence of climate (light, heat, air, water), plant and animal organisms" .
The main structural elements of the soil are: the mineral base, organic matter, air and water.
Mineral base (skeleton)(50-60% of the total soil) is an inorganic substance formed as a result of the underlying mountain (parent, parent) rock as a result of its weathering.
Sizes of skeletal particles: from boulders and stones to the smallest grains of sand and silt particles. The physicochemical properties of soils are mainly determined by the composition of parent rocks.
The permeability and porosity of the soil, which ensure the circulation of both water and air, depend on the ratio of clay and sand in the soil, the size of the fragments.
In temperate climates, it is ideal if the soil is formed by equal amounts of clay and sand, i.e. represents loam.
In this case, the soils are not threatened by either waterlogging or drying out. Both are equally detrimental to both plants and animals.
organic matter- up to 10% of the soil, is formed from dead biomass (plant mass - litter of leaves, branches and roots, dead trunks, grass rags, organisms of dead animals), crushed and processed into soil humus by microorganisms and certain groups of animals and plants.
The simpler elements formed as a result of the decomposition of organic matter are again assimilated by plants and are involved in the biological cycle.
Air(15-25%) in the soil is contained in cavities - pores, between organic and mineral particles. In the absence (heavy clay soils) or when the pores are filled with water (during flooding, thawing of permafrost), aeration in the soil worsens and anaerobic conditions develop.
Under such conditions, the physiological processes of organisms that consume oxygen - aerobes - are inhibited, the decomposition of organic matter is slow. Gradually accumulating, they form peat. Large reserves of peat are characteristic of swamps, swampy forests, and tundra communities. Peat accumulation is especially pronounced in the northern regions, where coldness and waterlogging of soils mutually determine and complement each other.
Water(25-30%) in the soil is represented by 4 types: gravitational, hygroscopic (bound), capillary and vaporous.
Gravity- mobile water, occupying wide gaps between soil particles, seeps down under its own weight to the groundwater level.
Easily absorbed by plants.
hygroscopic, or bound– is adsorbed around colloidal particles (clay, quartz) of the soil and is retained in the form of a thin film due to hydrogen bonds. It is released from them at high temperature (102-105°C). It is inaccessible to plants, does not evaporate. In clay soils, such water is up to 15%, in sandy soils - 5%.
capillary- is held around soil particles by the force of surface tension.
Through narrow pores and channels - capillaries, it rises from the groundwater level or diverges from cavities with gravitational water. Better retained by clay soils, easily evaporates.
Plants easily absorb it.
Vaporous- occupies all pores free from water. Evaporates first.
There is a constant exchange of surface soil and groundwater, as a link in the general water cycle in nature, changing speed and direction depending on the season and weather conditions.
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Gas composition of the atmosphere is also an important climatic factor.
Approximately 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases.
It was in the terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homoiothermia arose. Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment. Only in places, under specific conditions, is a temporary deficit created, for example, in accumulations of decaying plant residues, stocks of grain, flour, etc.
For example, in the absence of wind in the center of large cities, its concentration increases tenfold. Regular daily changes in the carbon dioxide content in the surface layers, associated with the rhythm of plant photosynthesis, and seasonal, due to changes in the intensity of respiration of living organisms, mainly the microscopic population of soils. Increased air saturation with carbon dioxide occurs in zones of volcanic activity, near thermal springs and other underground outlets of this gas.
Low air density determines its low lifting force and insignificant bearing capacity.
The inhabitants of the air must have their own support system that supports the body: plants - a variety of mechanical tissues, animals - a solid or, much less often, a hydrostatic skeleton.
Wind
storms
Pressure
The low density of air causes a relatively low pressure on land. Normally, it is equal to 760 mm Hg, Art. As altitude increases, pressure decreases. At an altitude of 5800 m, it is only half normal. Low pressure may limit the distribution of species in the mountains. For most vertebrates, the upper limit of life is about 6000 m. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiratory rate.
Approximately the same are the limits of advancement to the mountains of higher plants. Somewhat more hardy are arthropods (springtails, mites, spiders) that can be found on glaciers above the vegetation boundary.
In general, all terrestrial organisms are much more stenobatic than aquatic ones.
Ground-Air Habitat
In the course of evolution, this environment was mastered later than the water. Ecological factors in the terrestrial-air environment differ from other habitats in high light intensity, significant fluctuations in air temperature and humidity, the correlation of all factors with geographical location, the change of seasons of the year and time of day.
The environment is gaseous, therefore it is characterized by low humidity, density and pressure, high oxygen content.
Characterization of abiotic environmental factors of light, temperature, humidity - see the previous lecture.
Gas composition of the atmosphere is also an important climatic factor. Approximately 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases.
At present, the atmosphere consists mainly of nitrogen, oxygen, and relatively smaller amounts of argon and carbon dioxide.
All other gases present in the atmosphere are contained only in trace amounts. Of particular importance for the biota is the relative content of oxygen and carbon dioxide.
It was in the terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homoiothermia arose. Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment.
Only in places, under specific conditions, is a temporary deficit created, for example, in accumulations of decaying plant residues, stocks of grain, flour, etc.
The content of carbon dioxide can vary in certain areas of the surface layer of air in a fairly significant range. For example, in the absence of wind in the center of large cities, its concentration increases tenfold. Regular daily changes in the carbon dioxide content in the surface layers, associated with the rhythm of plant photosynthesis, and seasonal, due to changes in the intensity of respiration of living organisms, mainly the microscopic population of soils.
Increased air saturation with carbon dioxide occurs in zones of volcanic activity, near thermal springs and other underground outlets of this gas. The low content of carbon dioxide inhibits the process of photosynthesis.
Under indoor conditions, the rate of photosynthesis can be increased by increasing the concentration of carbon dioxide; this is used in the practice of greenhouse and greenhouse farming.
Air nitrogen for most inhabitants of the terrestrial environment is an inert gas, but a number of microorganisms (nodule bacteria, Azotobacter, clostridia, blue-green algae, etc.) have the ability to bind it and involve it in the biological cycle.
Local impurities entering the air can also significantly affect living organisms.
This is especially true for toxic gaseous substances - methane, sulfur oxide (IV), carbon monoxide (II), nitrogen oxide (IV), hydrogen sulfide, chlorine compounds, as well as particles of dust, soot, etc., polluting the air in industrial areas. The main modern source of chemical and physical pollution of the atmosphere is anthropogenic: the work of various industrial enterprises and transport, soil erosion, etc.
n. Sulfur oxide (SO2), for example, is toxic to plants even at concentrations from one fifty-thousandth to one millionth of the volume of air .. Some plant species are especially sensitive to SO2 and serve as a sensitive indicator of its accumulation in the air (for example , lichens.
Low air density determines its low lifting force and insignificant bearing capacity. The inhabitants of the air must have their own support system that supports the body: plants - a variety of mechanical tissues, animals - a solid or, much less often, a hydrostatic skeleton.
In addition, all the inhabitants of the air environment are closely connected with the surface of the earth, which serves them for attachment and support. Life in a suspended state in the air is impossible. True, many microorganisms and animals, spores, seeds and pollen of plants are regularly present in the air and are carried by air currents (anemochory), many animals are capable of active flight, but in all these species the main function of their life cycle is reproduction. - carried out on the surface of the earth.
For most of them, being in the air is associated only with resettlement or the search for prey.
Wind It has a limiting effect on the activity and even distribution of organisms. Wind can even change the appearance of plants, especially in habitats such as alpine zones where other factors are limiting. In open mountain habitats, wind limits plant growth, causing plants to bend to the windward side.
In addition, wind increases evapotranspiration in low humidity conditions. Of great importance are storms, although their action is purely local. Hurricanes, as well as ordinary winds, are capable of transporting animals and plants over long distances and thereby changing the composition of communities.
Pressure, apparently, is not a limiting factor of direct action, but it is directly related to weather and climate, which have a direct limiting effect.
The low density of air causes a relatively low pressure on land. Normally, it is equal to 760 mm Hg, Art. As altitude increases, pressure decreases. At an altitude of 5800 m, it is only half normal.
Low pressure may limit the distribution of species in the mountains.
For most vertebrates, the upper limit of life is about 6000 m. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiratory rate. Approximately the same are the limits of advancement to the mountains of higher plants. Somewhat more hardy are arthropods (springtails, mites, spiders) that can be found on glaciers above the vegetation boundary.
Saint Petersburg State Academy
Veterinary medicine.
Department of General Biology, Ecology and Histology.
Abstract on ecology on the topic:
Ground-air environment, its factors
and adaptation of organisms to them
Completed by: 1st year student
Oh group Pyatochenko N. L.
Checked by: Associate Professor of the Department
Vakhmistrova S. F.
St. Petersburg
Introduction
The conditions of life (conditions of existence) are a set of elements necessary for the body, with which it is inextricably linked and without which it cannot exist.
The adaptations of an organism to its environment are called adaptations. The ability to adapt is one of the main properties of life in general, providing the possibility of its existence, survival and reproduction. Adaptation manifests itself at different levels - from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecosystems. Adaptations arise and change during the evolution of a species.
Separate properties or elements of the environment that affect organisms are called environmental factors. Environmental factors are varied. They have different nature and specific action. Environmental factors are divided into two large groups: abiotic and biotic.
Abiotic factors- this is a complex of conditions of the inorganic environment that directly or indirectly affect living organisms: temperature, light, radioactive radiation, pressure, air humidity, salt composition of water, etc.
Biotic factors are all forms of influence of living organisms on each other. Each organism constantly experiences the direct or indirect influence of others, entering into communication with representatives of its own and other species.
In some cases, anthropogenic factors are separated into an independent group along with biotic and abiotic factors, emphasizing the extraordinary effect of the anthropogenic factor.
Anthropogenic factors are all forms of activity of human society that lead to a change in nature as a habitat for other species or directly affect their lives. The importance of anthropogenic impact on the entire living world of the Earth continues to grow rapidly.
Changes in environmental factors over time can be:
1) regular-constant, changing the strength of the impact in connection with the time of day, the season of the year or the rhythm of the tides in the ocean;
2) irregular, without a clear periodicity, for example, changes in weather conditions in different years, storms, downpours, mudflows, etc.;
3) directed over certain or long periods of time, for example, cooling or warming of the climate, overgrowing of a reservoir, etc.
Environmental factors can have various effects on living organisms:
1) as irritants, causing adaptive changes in physiological and biochemical functions;
2) as constraints, causing the impossibility of existence in the data
conditions;
3) as modifiers causing anatomical and morphological changes in organisms;
4) as signals indicating a change in other factors.
Despite the great variety environmental factors, in the nature of their interaction with organisms and in the responses of living beings, a number of general patterns can be distinguished.
The intensity of the environmental factor, the most favorable for the life of the organism, is the optimum, and giving the worst effect is the pessimum, i.e. conditions under which the vital activity of the organism is maximally inhibited, but it can still exist. So, when growing plants in different temperature conditions, the point at which maximum growth is observed will be the optimum. In most cases, this is a certain temperature range of several degrees, so here it is better to talk about the optimum zone. The entire temperature range (from minimum to maximum), at which growth is still possible, is called the range of stability (endurance), or tolerance. The point limiting its (i.e. minimum and maximum) habitable temperatures is the limit of stability. Between the optimum zone and the stability limit, as the latter is approached, the plant experiences increasing stress, i.e. we are talking about stress zones, or zones of oppression, within the range of stability
Dependence of the action of the environmental factor on its intensity (according to V.A. Radkevich, 1977)
As the scale moves up and down, not only does stress increase, but ultimately, upon reaching the limits of the organism's resistance, its death occurs. Similar experiments can be carried out to test the influence of other factors. The results will graphically follow a similar type of curve.
Ground-air environment of life, its characteristics and forms of adaptation to it.
Life on land required such adaptations that were possible only in highly organized living organisms. The ground-air environment is more difficult for life, it is characterized by a high oxygen content, a small amount of water vapor, low density, etc. This greatly changed the conditions of respiration, water exchange and movement of living beings.
The low air density determines its low lifting force and insignificant bearing capacity. Air organisms must have their own support system that supports the body: plants - a variety of mechanical tissues, animals - a solid or hydrostatic skeleton. In addition, all the inhabitants of the air environment are closely connected with the surface of the earth, which serves them for attachment and support.
Low air density provides low movement resistance. Therefore, many land animals have acquired the ability to fly. 75% of all terrestrial creatures, mainly insects and birds, have adapted to active flight.
Due to the mobility of air, the vertical and horizontal flows of air masses existing in the lower layers of the atmosphere, passive flight of organisms is possible. In this regard, many species have developed anemochory - resettlement with the help of air currents. Anemochory is characteristic of spores, seeds and fruits of plants, protozoan cysts, small insects, spiders, etc. Organisms passively transported by air currents are collectively called aeroplankton.
Terrestrial organisms exist in conditions of relatively low pressure due to the low density of air. Normally, it is equal to 760 mm Hg. As altitude increases, pressure decreases. Low pressure may limit the distribution of species in the mountains. For vertebrates, the upper limit of life is about 60 mm. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in the respiratory rate. Approximately the same limits of advance in the mountains have higher plants. Somewhat more hardy are the arthropods that can be found on glaciers above the vegetation line.
Gas composition of air. In addition to the physical properties of the air environment, its chemical properties are very important for the existence of terrestrial organisms. The gas composition of air in the surface layer of the atmosphere is quite homogeneous in terms of the content of the main components (nitrogen - 78.1%, oxygen - 21.0%, argon 0.9%, carbon dioxide - 0.003% by volume).
The high oxygen content contributed to an increase in the metabolism of terrestrial organisms compared to primary aquatic ones. It was in the terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homeothermia arose. Oxygen, due to its constant high content in the air, is not a limiting factor for life in the terrestrial environment.
The content of carbon dioxide can vary in certain areas of the surface layer of air within fairly significant limits. Increased air saturation with CO? occurs in zones of volcanic activity, near thermal springs and other underground outlets of this gas. In high concentrations, carbon dioxide is toxic. In nature, such concentrations are rare. Low CO2 content slows down the process of photosynthesis. Under indoor conditions, you can increase the rate of photosynthesis by increasing the concentration of carbon dioxide. This is used in the practice of greenhouses and greenhouses.
Air nitrogen for most inhabitants of the terrestrial environment is an inert gas, but individual microorganisms (nodule bacteria, nitrogen bacteria, blue-green algae, etc.) have the ability to bind it and involve it in the biological cycle of substances.
Moisture deficiency is one of the essential features of the ground-air environment of life. The whole evolution of terrestrial organisms was under the sign of adaptation to the extraction and conservation of moisture. The modes of environmental humidity on land are very diverse - from the complete and constant saturation of air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. The daily and seasonal variability of water vapor content in the atmosphere is also significant. The water supply of terrestrial organisms also depends on the mode of precipitation, the presence of reservoirs, soil moisture reserves, the proximity of groundwater, and so on.
This led to the development of adaptations in terrestrial organisms to various water supply regimes.
Temperature regime. The next distinguishing feature of the air-ground environment is significant temperature fluctuations. In most land areas, daily and annual temperature amplitudes are tens of degrees. The resistance to temperature changes in the environment of terrestrial inhabitants is very different, depending on the particular habitat in which they live. However, in general, terrestrial organisms are much more eurythermic than aquatic organisms.
The conditions of life in the ground-air environment are complicated, in addition, by the existence of weather changes. Weather - continuously changing states of the atmosphere near the borrowed surface, up to a height of about 20 km (troposphere boundary). Weather variability is manifested in the constant variation of the combination of such environmental factors as temperature, air humidity, cloudiness, precipitation, wind strength and direction, etc. The long-term weather regime characterizes the climate of the area. The concept of "Climate" includes not only the average values of meteorological phenomena, but also their annual and daily course, deviation from it and their frequency. The climate is determined by the geographical conditions of the area. The main climatic factors - temperature and humidity - are measured by the amount of precipitation and the saturation of the air with water vapor.
For most terrestrial organisms, especially small ones, the climate of the area is not so much important as the conditions of their immediate habitat. Very often, local elements of the environment (relief, exposure, vegetation, etc.) change the regime of temperatures, humidity, light, air movement in a particular area in such a way that it differs significantly from the climatic conditions of the area. Such modifications of the climate, which take shape in the surface layer of air, are called the microclimate. In each zone, the microclimate is very diverse. Microclimates of very small areas can be distinguished.
The light regime of the ground-air environment also has some features. The intensity and amount of light here are the greatest and practically do not limit the life of green plants, as in water or soil. On land, the existence of extremely photophilous species is possible. For the vast majority of terrestrial animals with diurnal and even nocturnal activity, vision is one of the main ways of orientation. In terrestrial animals, vision is essential for finding prey, and many species even have color vision. In this regard, the victims develop such adaptive features as a defensive reaction, masking and warning coloration, mimicry, etc.
In aquatic life, such adaptations are much less developed. The emergence of brightly colored flowers of higher plants is also associated with the peculiarities of the apparatus of pollinators and, ultimately, with the light regime of the environment.
The relief of the terrain and the properties of the soil are also the conditions for the life of terrestrial organisms and, first of all, plants. The properties of the earth's surface that have an ecological impact on its inhabitants are united by "edaphic environmental factors" (from the Greek "edafos" - "soil").
Towards different properties soils can be distinguished whole line ecological groups of plants. So, according to the reaction to the acidity of the soil, they distinguish:
1) acidophilic species - grow on acidic soils with a pH of at least 6.7 (plants of sphagnum bogs);
2) neutrophils tend to grow on soils with a pH of 6.7–7.0 (most cultivated plants);
3) basiphilic grow at a pH of more than 7.0 (mordovnik, forest anemone);
4) indifferent ones can grow on soils with different pH values (lily of the valley).
Plants also differ in relation to soil moisture. Certain species are confined to different substrates, for example, petrophytes grow on stony soils, and pasmophytes inhabit free-flowing sands.
The terrain and the nature of the soil affect the specifics of the movement of animals: for example, ungulates, ostriches, bustards living in open spaces, hard ground, to enhance repulsion when running. In lizards that live in loose sands, the fingers are fringed with horny scales that increase support. For terrestrial inhabitants digging holes, dense soil is unfavorable. The nature of the soil in certain cases affects the distribution of terrestrial animals that dig holes or burrow into the ground, or lay eggs in the soil, etc.
On the composition of air.
The gas composition of the air we breathe is 78% nitrogen, 21% oxygen and 1% other gases. But in the atmosphere of large industrial cities, this ratio is often violated. A significant proportion is made up of harmful impurities caused by emissions from enterprises and vehicles. Motor transport brings many impurities into the atmosphere: hydrocarbons of unknown composition, benzo (a) pyrene, carbon dioxide, sulfur and nitrogen compounds, lead, carbon monoxide.
The atmosphere consists of a mixture of a number of gases - air, in which colloidal impurities are suspended - dust, droplets, crystals, etc. With height, the composition atmospheric air little changes. However, starting from a height of about 100 km, along with molecular oxygen and nitrogen, atomic oxygen also appears as a result of the dissociation of molecules, and the gravitational separation of gases begins. Above 300 km, atomic oxygen predominates in the atmosphere, above 1000 km - helium and then atomic hydrogen. The pressure and density of the atmosphere decrease with height; about half of the total mass of the atmosphere is concentrated in the lower 5 km, 9/10 - in the lower 20 km and 99.5% - in the lower 80 km. At altitudes of about 750 km, the air density drops to 10-10 g/m3 (whereas near the earth's surface it is about 103 g/m3), but even such a low density is still sufficient for the occurrence of auroras. The atmosphere does not have a sharp upper boundary; the density of its constituent gases
The composition of the atmospheric air that each of us breathes includes several gases, the main of which are: nitrogen (78.09%), oxygen (20.95%), hydrogen (0.01%) carbon dioxide (carbon dioxide) (0.03%) and inert gases (0.93%). In addition, there is always a certain amount of water vapor in the air, the amount of which always changes with temperature: the higher the temperature, the greater the vapor content and vice versa. Due to fluctuations in the amount of water vapor in the air, the percentage of gases in it is also variable. All gases in air are colorless and odorless. The weight of air varies depending not only on temperature, but also on the content of water vapor in it. At the same temperature, the weight of dry air is greater than that of moist air, because water vapor is much lighter than air vapor.
The table shows the gas composition of the atmosphere in volumetric mass ratio, as well as the lifetime of the main components:
| Component | % by volume | % mass |
| N2 | 78,09 | 75,50 |
| O2 | 20,95 | 23,15 |
| Ar | 0,933 | 1,292 |
| CO2 | 0,03 | 0,046 |
| Ne | 1,8 10-3 | 1,4 10-3 |
| He | 4,6 10-4 | 6,4 10-5 |
| CH4 | 1,52 10-4 | 8,4 10-5 |
| kr | 1,14 10-4 | 3 10-4 |
| H2 | 5 10-5 | 8 10-5 |
| N2O | 5 10-5 | 8 10-5 |
| Xe | 8,6 10-6 | 4 10-5 |
| O3 | 3 10-7 - 3 10-6 | 5 10-7 - 5 10-6 |
| Rn | 6 10-18 | 4,5 10-17 |
The properties of the gases that make up atmospheric air change under pressure.
For example: oxygen under pressure of more than 2 atmospheres has a toxic effect on the body.
Nitrogen under pressure over 5 atmospheres has a narcotic effect (nitrogen intoxication). A rapid rise from the depth causes decompression sickness due to the rapid release of nitrogen bubbles from the blood, as if foaming it.
An increase in carbon dioxide of more than 3% in the respiratory mixture causes death.
Each component that is part of the air, with an increase in pressure to certain limits, becomes a poison that can poison the body.
Studies of the gas composition of the atmosphere. atmospheric chemistry
For the history of the rapid development of a relatively young branch of science called atmospheric chemistry, the term “spurt” (throw) used in high-speed sports is most suitable. The shot from the starting pistol, perhaps, was two articles published in the early 1970s. They dealt with the possible destruction of stratospheric ozone by nitrogen oxides - NO and NO2. The first belonged to the future Nobel laureate, and then an employee of the Stockholm University, P. Krutzen, who considered the probable source of nitrogen oxides in the stratosphere to be naturally occurring nitrous oxide N2O that decays under the action of sunlight. The author of the second article, a chemist from the University of California at Berkeley G. Johnston, suggested that nitrogen oxides appear in the stratosphere as a result of human activity, namely, from the emissions of combustion products from jet engines of high-altitude aircraft.
Of course, the above hypotheses did not arise from scratch. The ratio of at least the main components in the atmospheric air - molecules of nitrogen, oxygen, water vapor, etc. - was known much earlier. Already in the second half of the XIX century. in Europe, measurements of ozone concentration in surface air were made. In the 1930s, the English scientist S. Chapman discovered the mechanism of ozone formation in a purely oxygen atmosphere, indicating a set of interactions of oxygen atoms and molecules, as well as ozone in the absence of any other air components. However, in the late 1950s, meteorological rocket measurements showed that there was much less ozone in the stratosphere than it should be according to the Chapman reaction cycle. Although this mechanism remains fundamental to this day, it has become clear that there are some other processes that are also actively involved in the formation of atmospheric ozone.
It is worth mentioning that by the beginning of the 1970s, knowledge in the field of atmospheric chemistry was mainly obtained thanks to the efforts of individual scientists, whose research was not united by any socially significant concept and was most often purely academic. Another thing is the work of Johnston: according to his calculations, 500 aircraft, flying 7 hours a day, could reduce the amount of stratospheric ozone by at least 10%! And if these assessments were fair, then the problem would immediately become a socio-economic one, since in this case all programs for the development of supersonic transport aviation and related infrastructure would have to undergo a significant adjustment, and perhaps even closure. In addition, then for the first time the question really arose that anthropogenic activity could cause not a local, but a global cataclysm. Naturally, in the current situation, the theory needed a very tough and at the same time prompt verification.
Recall that the essence of the above hypothesis was that nitric oxide reacts with ozone NO + O3 ® ® NO2 + O2, then the nitrogen dioxide formed in this reaction reacts with the oxygen atom NO2 + O ® NO + O2, thereby restoring the presence NO in the atmosphere, while the ozone molecule is irretrievably lost. In this case, such a pair of reactions, constituting the nitrogen catalytic cycle of ozone destruction, is repeated until any chemical or physical processes lead to the removal of nitrogen oxides from the atmosphere. So, for example, NO2 is oxidized to nitric acid HNO3, which is highly soluble in water, and therefore is removed from the atmosphere by clouds and precipitation. The nitrogen catalytic cycle is very efficient: one NO molecule manages to destroy tens of thousands of ozone molecules during its stay in the atmosphere.
But, as you know, trouble does not come alone. Soon, specialists from US universities - Michigan (R. Stolyarsky and R. Cicerone) and Harvard (S. Wofsi and M. McElroy) - discovered that ozone could have an even more merciless enemy - chlorine compounds. According to their estimates, the chlorine catalytic cycle of ozone destruction (reactions Cl + O3 ® ClO + O2 and ClO + O ® Cl + O2) was several times more efficient than the nitrogen one. The only reason for cautious optimism was that the amount of naturally occurring chlorine in the atmosphere is relatively small, which means that the overall effect of its impact on ozone may not be too strong. However, the situation changed dramatically when, in 1974, employees of the University of California at Irvine, S. Rowland and M. Molina, found that the source of chlorine in the stratosphere is chlorofluorohydrocarbon compounds (CFCs), which are widely used in refrigeration units, aerosol packages, etc. Being non-flammable, non-toxic and chemically passive, these substances are slowly transported by ascending air currents from the earth's surface to the stratosphere, where their molecules are destroyed by sunlight, resulting in the release of free chlorine atoms. The industrial production of CFCs, which began in the 1930s, and their emissions into the atmosphere steadily increased in all subsequent years, especially in the 70s and 80s. Thus, within a very short period of time, theorists have identified two problems in atmospheric chemistry caused by intense anthropogenic pollution.
However, in order to test the viability of the proposed hypotheses, it was necessary to perform many tasks.
Firstly, expand laboratory studies in which it would be possible to determine or refine photoflow rates chemical reactions between different components of atmospheric air. It must be said that the very meager data on these velocities that existed at that time also had a fair (up to several hundred percent) errors. In addition, the conditions under which the measurements were made, as a rule, did not correspond much to the realities of the atmosphere, which seriously aggravated the error, since the intensity of most reactions depended on temperature, and sometimes on pressure or atmospheric air density.
Secondly, intensively study the radiation-optical properties of a number of small atmospheric gases in laboratory conditions. The molecules of a significant number of atmospheric air components are destroyed by the ultraviolet radiation of the Sun (in photolysis reactions), among them are not only the CFCs mentioned above, but also molecular oxygen, ozone, nitrogen oxides and many others. Therefore, estimates of the parameters of each photolysis reaction were just as necessary and important for the correct reproduction of atmospheric chemical processes as were the rates of reactions between different molecules.
Thirdly, it was necessary to create mathematical models capable of describing the mutual chemical transformations of atmospheric air components as fully as possible. As already mentioned, the productivity of ozone destruction in catalytic cycles is determined by how long the catalyst (NO, Cl, or some other) stays in the atmosphere. It is clear that such a catalyst, generally speaking, could react with any of the dozens of atmospheric air components, quickly degrading in the process, and then the damage to stratospheric ozone would be much less than expected. On the other hand, when many chemical transformations occur in the atmosphere every second, it is quite likely that other mechanisms will be identified that directly or indirectly affect the formation and destruction of ozone. Finally, such models are able to identify and evaluate the significance of individual reactions or their groups in the formation of other gases that make up atmospheric air, as well as allow calculating the concentrations of gases that are inaccessible to measurements.
And finally it was necessary to organize a wide network for measuring the content of various gases in the air, including nitrogen compounds, chlorine, etc., using ground stations, launching weather balloons and meteorological rockets, and aircraft flights for this purpose. Of course, creating a database was the most expensive task, which could not be solved in a short time. However, only measurements could provide a starting point for theoretical research, being at the same time a touchstone of the truth of the hypotheses expressed.
Since the beginning of the 1970s, at least once every three years, special, constantly updated collections containing information on all significant atmospheric reactions, including photolysis reactions, have been published. Moreover, the error in determining the parameters of reactions between the gaseous components of air today is, as a rule, 10-20%.
The second half of this decade witnessed the rapid development of models describing chemical transformations in the atmosphere. Most of them were created in the USA, but they also appeared in Europe and the USSR. At first these were boxed (zero-dimensional), and then one-dimensional models. The former reproduced with varying degrees of reliability the content of the main atmospheric gases in a given volume - a box (hence their name) - as a result of chemical interactions between them. Since the conservation of the total mass of the air mixture was postulated, the removal of any of its fraction from the box, for example, by the wind, was not considered. Box models were convenient for elucidating the role of individual reactions or their groups in the processes of chemical formation and destruction of atmospheric gases, for assessing the sensitivity of the atmospheric gas composition to inaccuracies in determining reaction rates. With their help, the researchers could, by setting atmospheric parameters in the box (in particular, air temperature and density) corresponding to the altitude of aviation flights, estimate in a rough approximation how the concentrations of atmospheric impurities will change as a result of emissions of combustion products by aircraft engines. At the same time, box models were unsuitable for studying the problem of chlorofluorocarbons (CFCs), since they could not describe the process of their movement from the earth's surface into the stratosphere. This is where one-dimensional models came in handy, which combined taking into account a detailed description of chemical interactions in the atmosphere and the transport of impurities in the vertical direction. And although the vertical transfer was set rather roughly here, the use of one-dimensional models was a noticeable step forward, since they made it possible to somehow describe real phenomena.
Looking back, we can say that our modern knowledge is largely based on the rough work carried out in those years with the help of one-dimensional and boxed models. It made it possible to determine the mechanisms of formation of the gaseous composition of the atmosphere, to estimate the intensity of chemical sources and sinks of individual gases. An important feature of this stage in the development of atmospheric chemistry is that new ideas that were born were tested on models and widely discussed among specialists. The results obtained were often compared with the estimates of other scientific groups, since field measurements were clearly not enough, and their accuracy was very low. In addition, to confirm the correctness of modeling certain chemical interactions, it was necessary to carry out complex measurements, when the concentrations of all participating reagents would be determined simultaneously, which at that time, and even now, was practically impossible. (Until now, only a few measurements of the complex of gases from the Shuttle have been carried out over 2–5 days.) Therefore, model studies were ahead of experimental ones, and the theory not so much explained the field observations as contributed to their optimal planning. For example, a compound such as chlorine nitrate ClONO2 first appeared in model studies and only then was discovered in the atmosphere. It was difficult even to compare the available measurements with model estimates, since the one-dimensional model could not take into account horizontal air movements, because of which the atmosphere was assumed to be horizontally homogeneous, and the obtained model results corresponded to some global mean state of it. However, in reality, the composition of the air over the industrial regions of Europe or the United States is very different from its composition over Australia or over the Pacific Ocean. Therefore, the results of any natural observation largely depend on the place and time of measurements and, of course, do not exactly correspond to the global average.
To eliminate this gap in modeling, in the 1980s, researchers created two-dimensional models that, along with vertical transport, also took into account air transport along the meridian (along the circle of latitude, the atmosphere was still considered homogeneous). The creation of such models at first was associated with significant difficulties.
Firstly, the number of external model parameters sharply increased: at each grid node, it was necessary to set the vertical and interlatitudinal transport velocities, air temperature and density, and so on. Many parameters (first of all, the above-mentioned speeds) were not reliably determined in experiments and, therefore, were selected on the basis of qualitative considerations.
Secondly, the state of computer technology of that time significantly hindered the full development of two-dimensional models. Unlike economical one-dimensional and especially boxed models, two-dimensional models required significantly high costs computer memory and time. And as a result, their creators were forced to significantly simplify the schemes for accounting for chemical transformations in the atmosphere. Nevertheless, a complex of atmospheric studies, both model and full-scale using satellites, made it possible to draw a relatively harmonious, although far from complete, picture of the composition of the atmosphere, as well as to establish the main cause-and-effect relationships that cause changes in the content of individual air components. In particular, numerous studies have shown that aircraft flights in the troposphere do not cause any significant harm to tropospheric ozone, but their rise into the stratosphere seems to have negative consequences for the ozonosphere. The opinion of most experts on the role of CFCs was almost unanimous: the hypothesis of Rowland and Molin is confirmed, and these substances really contribute to the destruction of stratospheric ozone, and the regular increase in their industrial production is a time bomb, since the decay of CFCs does not occur immediately, but after tens and hundreds of years , so the effects of pollution will affect the atmosphere for a very long time. Moreover, if stored for a long time, chlorofluorocarbons can reach any, the most remote point of the atmosphere, and, therefore, this is a threat on a global scale. The time has come for coordinated political decisions.
In 1985, with the participation of 44 countries in Vienna, a convention for the protection of the ozone layer was developed and adopted, which stimulated its comprehensive study. However, the question of what to do with CFCs was still open. It was impossible to let things take their course on the principle of “it will resolve itself”, but it was also impossible to ban the production of these substances overnight without huge damage to the economy. It would seem that there is a simple solution: you need to replace CFCs with other substances capable of performing the same functions (for example, in refrigeration units) and at the same time harmless or at least less dangerous for ozone. But bring to life simple solutions is often very difficult. Not only did the creation of such substances and the establishment of their production require huge investments and time, criteria were needed to assess the impact of any of them on the atmosphere and climate.
Theorists are back in the spotlight. D. Webbles from the Livermore National Laboratory suggested using the ozone-depleting potential for this purpose, which showed how much the molecule of the substitute substance is stronger (or weaker) than the CFCl3 (freon-11) molecule affects atmospheric ozone. At that time, it was also well known that the temperature of the surface air layer significantly depends on the concentration of certain gaseous impurities (they were called greenhouse gases), primarily carbon dioxide CO2, water vapor H2O, ozone, etc. CFCs and many others were also included in this category. their potential replacements. Measurements have shown that during the industrial revolution, the average annual global temperature of the surface air layer has grown and continues to grow, and this indicates significant and not always desirable changes in the Earth's climate. In order to bring this situation under control, along with the ozone-depleting potential of the substance, they also began to consider its global warming potential. This index indicated how much stronger or weaker the studied compound affects the air temperature than the same amount of carbon dioxide. The calculations performed showed that CFCs and alternatives had very high global warming potentials, but because their concentrations in the atmosphere were much lower than the concentrations of CO2, H2O or O3, their total contribution to global warming remained negligible. For the time being…
Tables of calculated values for the ozone depletion and global warming potentials of chlorofluorocarbons and their possible substitutes formed the basis of international decisions to reduce and subsequently ban the production and use of many CFCs (the Montreal Protocol of 1987 and its later additions). Perhaps the experts gathered in Montreal would not have been so unanimous (after all, the articles of the Protocol were based on the “thinkings” of theorists not confirmed by field experiments), but another interested “person” spoke out for signing this document - the atmosphere itself.
The message about the discovery by British scientists at the end of 1985 of the "ozone hole" over Antarctica became, not without the participation of journalists, the sensation of the year, and the reaction of the world community to this message can be best described in one short word - shock. It is one thing when the threat of destruction of the ozone layer exists only in the long term, another thing when we are all faced with a fait accompli. Neither the townsfolk, nor politicians, nor specialists-theorists were ready for this.
It quickly became clear that none of the then existing models could reproduce such a significant reduction in ozone. This means that some important natural phenomena were either not taken into account or underestimated. Soon, field studies carried out as part of the program for studying the Antarctic phenomenon established that an important role in the formation of the “ozone hole”, along with ordinary (gas-phase) atmospheric reactions, is played by the features of atmospheric air transport in the Antarctic stratosphere (its almost complete isolation from the rest of the atmosphere in winter), as well as at that time little studied heterogeneous reactions (reactions on the surface of atmospheric aerosols - dust particles, soot, ice floes, water drops, etc.). Only taking into account the above factors made it possible to achieve satisfactory agreement between the model results and observational data. And the lessons taught by the Antarctic “ozone hole” seriously affected the further development of atmospheric chemistry.
First, a sharp impetus was given to a detailed study of heterogeneous processes proceeding according to laws different from those that determine gas-phase processes. Secondly, a clear realization has come that in a complex system, which is the atmosphere, the behavior of its elements depends on a whole complex of internal connections. In other words, the content of gases in the atmosphere is determined not only by the intensity of chemical processes, but also by air temperature, the transfer of air masses, the characteristics of aerosol pollution of various parts of the atmosphere, etc. In turn, radiative heating and cooling, which form the temperature field of stratospheric air, depend on the concentration and spatial distribution of greenhouse gases, and, consequently, from atmospheric dynamic processes. Finally, non-uniform radiative heating of different belts of the globe and parts of the atmosphere generates atmospheric air movements and controls their intensity. Thus, not taking into account any feedback in the models can be fraught with large errors in the results obtained (although, we note in passing, the excessive complication of the model without urgent need is just as inappropriate as firing cannons at known representatives of birds).
If the relationship between air temperature and its gas composition was taken into account in two-dimensional models back in the 1980s, then the use of three-dimensional models of the general circulation of the atmosphere to describe the distribution of atmospheric impurities became possible only in the 1990s due to the computer boom. The first such general circulation models were used to describe the spatial distribution of chemically passive substances - tracers. Later, due to insufficient computer memory, chemical processes were set by only one parameter - the residence time of an impurity in the atmosphere, and only relatively recently, blocks of chemical transformations became full-fledged parts of three-dimensional models. Although the difficulties of representing atmospheric chemical processes in 3D in detail still remain, today they no longer seem insurmountable, and the best 3D models include hundreds of chemical reactions, along with the actual climatic transport of air in the global atmosphere.
At the same time, widespread use modern models does not at all cast doubt on the usefulness of the simpler ones discussed above. It is well known that the more complex the model, the more difficult it is to separate the “signal” from the “model noise”, analyze the results obtained, identify the main cause-and-effect mechanisms, evaluate the impact of certain phenomena on the final result (and, therefore, the expediency of taking them into account in the model) . And here more simple models they serve as an ideal testing ground, they allow you to get preliminary estimates that are further used in three-dimensional models, study new natural phenomena before they are included in more complex ones, etc.
Rapid scientific and technological progress has given rise to several other areas of research, one way or another related to atmospheric chemistry.
Satellite monitoring of the atmosphere. When regular replenishment of the database from satellites was established, for most of the most important components of the atmosphere, covering almost the entire globe, it became necessary to improve the methods of their processing. Here, there is data filtering (separation of the signal and measurement errors), and restoration of vertical profiles of impurity concentrations from their total contents in the atmospheric column, and data interpolation in those areas where direct measurements are impossible for technical reasons. In addition, satellite monitoring is complemented by airborne expeditions that are planned to solve various problems, for example, in the tropical Pacific Ocean, the North Atlantic, and even in the Arctic summer stratosphere.
An important part of modern research is the assimilation (assimilation) of these databases in models of varying complexity. In this case, the parameters are selected from the condition of the closest proximity of the measured and model values of the content of impurities at points (regions). Thus, the quality of the models is checked, as well as the extrapolation of the measured values beyond the regions and periods of measurements.
Estimation of concentrations of short-lived atmospheric impurities. Atmospheric radicals, which play a key role in atmospheric chemistry, such as hydroxyl OH, perhydroxyl HO2, nitric oxide NO, atomic oxygen in the excited state O (1D), etc., have the highest chemical reactivity and, therefore, very small (several seconds or minutes ) “lifetime” in the atmosphere. Therefore, the measurement of such radicals is extremely difficult, and the reconstruction of their content in the air is often carried out using model ratios of chemical sources and sinks of these radicals. For a long time, the intensities of sources and sinks were calculated from model data. With the advent of appropriate measurements, it became possible to reconstruct the concentrations of radicals on their basis, while improving models and expanding information about the gaseous composition of the atmosphere.
Reconstruction of the gas composition of the atmosphere in the pre-industrial period and earlier epochs of the Earth. Thanks to measurements in Antarctic and Greenland ice cores, whose age ranges from hundreds to hundreds of thousands of years, the concentrations of carbon dioxide, nitrous oxide, methane, carbon monoxide, as well as the temperature of those times, became known. Model reconstruction of the state of the atmosphere in those epochs and its comparison with the current one makes it possible to trace the evolution of the earth's atmosphere and assess the degree of human impact on the natural environment.
Assessment of the intensity of the sources of the most important air components. Systematic measurements of the content of gases in the surface air, such as methane, carbon monoxide, nitrogen oxides, became the basis for solving the inverse problem: estimating the amount of emissions of gases from ground sources into the atmosphere, according to their known concentrations. Unfortunately, only inventorying the perpetrators of the global turmoil - CFCs - is a relatively simple task, since almost all of these substances do not have natural sources and their total amount released into the atmosphere is limited by their production volume. The rest of the gases have heterogeneous and comparable power sources. For example, the source of methane is waterlogged areas, swamps, oil wells, coal mines; this compound is secreted by termite colonies and is even a waste product of cattle. Carbon monoxide enters the atmosphere as part of exhaust gases, as a result of fuel combustion, as well as during the oxidation of methane and many organic compounds. It is difficult to directly measure the emissions of these gases, but techniques have been developed to estimate the global sources of pollutant gases, the error of which has been significantly reduced in recent years, although it remains large.
Prediction of changes in the composition of the atmosphere and climate of the Earth Considering trends - trends in the content of atmospheric gases, estimates of their sources, growth rates of the Earth's population, the rate of increase in the production of all types of energy, etc. - special groups of experts create and constantly adjust scenarios for probable atmospheric pollution in the next 10, 30, 100 years. Based on them, with the help of models, possible changes in the gas composition, temperature and atmospheric circulation are predicted. Thus, it is possible to detect unfavorable trends in the state of the atmosphere in advance and try to eliminate them. The Antarctic shock of 1985 must not be repeated.
The phenomenon of the greenhouse effect of the atmosphere
In recent years, it has become clear that the analogy between an ordinary greenhouse and the greenhouse effect of the atmosphere is not entirely correct. At the end of the last century, the famous American physicist Wood, replacing ordinary glass with quartz glass in a laboratory model of a greenhouse and not finding any changes in the functioning of the greenhouse, showed that it was not a matter of delaying the thermal radiation of the soil by glass that transmits solar radiation, the role of glass in this case consists only in “cutting off” the turbulent heat exchange between the soil surface and the atmosphere.
The greenhouse (greenhouse) effect of the atmosphere is its property to let solar radiation through, but to delay terrestrial radiation, contributing to the accumulation of heat by the earth. The earth's atmosphere transmits relatively well short-wave solar radiation, which is almost completely absorbed by the earth's surface. Heating up due to the absorption of solar radiation, the earth's surface becomes a source of terrestrial, mainly long-wave, radiation, some of which goes into outer space.
Effect of Increasing CO2 Concentration
Scientists - researchers continue to argue about the composition of the so-called greenhouse gases. Of greatest interest in this regard is the effect of increasing concentrations of carbon dioxide (CO2) on the greenhouse effect of the atmosphere. An opinion is expressed that the well-known scheme: “an increase in the concentration of carbon dioxide enhances the greenhouse effect, which leads to a warming of the global climate” is extremely simplified and very far from reality, since the most important “greenhouse gas” is not CO2 at all, but water vapor. At the same time, the reservation that the concentration of water vapor in the atmosphere is determined only by the parameters of the climate system itself is no longer tenable today, since the anthropogenic impact on the global water cycle has been convincingly proven.
As scientific hypotheses, we point out the following consequences of the coming greenhouse effect. Firstly, According to the most common estimates, by the end of the 21st century, the content of atmospheric CO2 will double, which will inevitably lead to an increase in the average global surface temperature by 3–5 ° C. At the same time, warming is expected in a drier summer in the temperate latitudes of the Northern Hemisphere.
Secondly, it is assumed that such an increase in the average global surface temperature will lead to an increase in the level of the World Ocean by 20 - 165 centimeters due to the thermal expansion of water. As for the ice sheet of Antarctica, its destruction is not inevitable, since higher temperatures are needed for melting. In any case, the process of melting Antarctic ice will take a very long time.
Thirdly, Atmospheric CO2 concentrations can have a very beneficial effect on crop yields. The results of the experiments carried out allow us to assume that under conditions of a progressive increase in the CO2 content in the air, natural and cultivated vegetation will reach an optimal state; the leaf surface of plants will increase, the specific gravity of the dry matter of the leaves will increase, the average size fruits and the number of seeds, the ripening of cereals will accelerate, and their yield will increase.
Fourth, at high latitudes, natural forests, especially boreal forests, can be very sensitive to temperature changes. Warming can lead to a sharp reduction in the area of boreal forests, as well as to the movement of their border to the north, the forests of the tropics and subtropics will probably be more sensitive to changes in precipitation rather than temperature.
The light energy of the sun penetrates the atmosphere, is absorbed by the earth's surface and heats it. In this case, light energy is converted into thermal energy, which is released in the form of infrared or thermal radiation. This infrared radiation reflected from the surface of the earth is absorbed by carbon dioxide, while it heats up itself and heats the atmosphere. This means that the more carbon dioxide in the atmosphere, the more it captures the climate on the planet. The same thing happens in greenhouses, which is why this phenomenon is called the greenhouse effect.
If the so-called greenhouse gases continue to flow at the current rate, then in the next century the average temperature of the Earth will increase by 4 - 5 o C, which can lead to global warming of the planet.
Conclusion
Changing your attitude to nature does not mean at all that you should abandon technological progress. Stopping it will not solve the problem, but can only delay its solution. We must persistently and patiently strive to reduce emissions through the introduction of new environmental technologies to save raw materials, energy consumption and increase the number of planted plantings, educational activities of the ecological worldview among the population.
For example, in the United States, one of the enterprises for the production of synthetic rubber is located next to residential areas, and this does not cause protests from residents, because environmentally friendly technological schemes are operating, which in the past, with old technologies, were not clean.
This means that a strict selection of technologies that meet the most stringent criteria is needed, modern promising technologies will make it possible to achieve a high level of environmental friendliness in production in all industries and transport, as well as an increase in the number of planted green spaces in industrial zones and cities.
In recent years, experiment has taken the leading position in the development of atmospheric chemistry, and the place of theory is the same as in the classical, respectable sciences. But there are still areas where it is theoretical research that remains a priority: for example, only model experiments are able to predict changes in the composition of the atmosphere or evaluate the effectiveness of restrictive measures implemented under the Montreal Protocol. Starting from the solution of an important, but private problem, today atmospheric chemistry, in cooperation with related disciplines, covers the entire complex of problems of study and protection. environment. Perhaps we can say that the first years of the formation of atmospheric chemistry passed under the motto: “Do not be late!” The starting spurt is over, the run continues.
Habitat is the immediate environment in which a living organism (animal or plant) exists. It can contain both living organisms and objects of inanimate nature and any number of varieties of organisms from several species to several thousand, coexisting in a certain living space. The air-terrestrial habitat includes such areas of the earth's surface as mountains, savannahs, forests, tundra, polar ice and others.
Habitat - planet Earth
Different parts of the planet Earth are home to a huge biological diversity of species of living organisms. There are certain types of animal habitats. Hot, arid regions are often covered by hot deserts. In warm, humid regions, there are humid
There are 10 main types of land habitats on Earth. Each of them has many varieties, depending on where in the world it is located. Animals and plants that are typical of a particular habitat adapt to the conditions in which they live.
African savannas
This tropical grassy air-to-ground community habitat is found in Africa. It is characterized by long dry periods following wet seasons with heavy rainfall. The African savannahs are home to a huge number of herbivores, as well as strong predators that feed on them.
The mountains
It is very cold on the tops of the high mountain ranges and few plants grow there. Animals living in these high places are adapted to cope with low temperatures, lack of food, and steep, rocky terrain.
evergreen forests
Coniferous forests are often found in cool areas of the globe: Canada, Alaska, Scandinavia and regions of Russia. They are dominated by evergreen spruces and these areas are home to animals such as elk, beaver and wolf.
deciduous trees
In cold, humid areas, many trees grow rapidly in summer but lose their leaves in winter. The number of wildlife in these areas varies seasonally as many migrate to other areas or hibernate during the winter.
temperate zone
It is characterized by dry grassy prairies and steppes, grasslands, hot summers and Cold winter. This land-air habitat is home to gregarious herbivores such as antelope and bison.
mediterranean zone
The lands around the Mediterranean Sea have a hot climate, but there is more rainfall here than in desert areas. These areas are home to shrubs and plants that can only survive with access to water and are often infested with many different types of insects.
Tundra
An air-to-land habitat such as the tundra is covered in ice for much of the year. Nature comes alive only in spring and summer. Deer live here and birds nest.
Rainforests
These dense green forests grow near the equator and have the richest biodiversity of living organisms. No other habitat boasts as many inhabitants as an area covered with tropical forests.
polar ice
Cold regions near the North and South Poles are covered with ice and snow. Here you can meet penguins, seals and polar bears, who get their livelihood in the icy waters of the ocean.
Animals of the ground-air habitat
Habitats are scattered over the vast territory of the planet Earth. Each is characterized by a certain biological and plant world, whose representatives unevenly populate our planet. In colder parts of the world, such as the polar regions, there are not many species of fauna that inhabit these areas and are specially adapted to living in low temperatures. Some animals are distributed throughout the world depending on the plants they eat, for example, the giant panda inhabits areas
Air-ground habitat
Every living organism needs a home, shelter or environment that can provide security, ideal temperature, food and reproduction - all that is necessary for survival. One of the important functions of a habitat is to provide the ideal temperature, as extreme changes can destroy an entire ecosystem. An important condition is also the presence of water, air, soil and sunlight.
The temperature on Earth is not the same everywhere, in some parts of the planet (North and South Poles) the thermometer can drop to -88°C. In other places, especially in the tropics, it is very warm and even hot (up to +50°C). The temperature regime plays an important role in the processes of adaptation of the ground-air habitat, for example, animals adapted to low temperatures cannot survive in heat.
Habitat is the natural environment in which an organism lives. Animals require different amounts of space. The habitat can be large and occupy an entire forest or small, like a mink. Some inhabitants have to defend and defend a huge territory, while others need a small patch of space where they can coexist relatively peacefully with neighbors living nearby.
General characteristics. In the course of evolution, the ground-air environment was mastered much later than the water. Life on land required such adaptations that became possible only with a relatively high level of organization of both plants and animals. A feature of the land-air environment of life is that the organisms that live here are surrounded by air and a gaseous environment characterized by low humidity, density and pressure, high oxygen content. As a rule, animals in this environment move along the soil (solid substrate), and plants take root in it.
In the ground-air environment, the operating environmental factors have a number of characteristic features: a higher light intensity in comparison with other media, significant temperature fluctuations, changes in humidity depending on the geographic location, season, and time of day (Table 3).
Table 3
Habitat conditions for air and water organisms (according to D.F. Mordukhai-Boltovsky, 1974)
|
living conditions |
Significance of conditions for organisms |
|
|
air environment |
aquatic environment |
|
|
Humidity |
Very important (often in short supply) |
Does not have (always in excess) |
|
Medium density |
Minor (excluding soil) |
Large compared to its role for the inhabitants of the air |
|
Pressure |
Has almost no |
Large (can reach 1000 atmospheres) |
|
Temperature |
Significant (fluctuates within very wide limits (from -80 to +100 °С and more) |
Less than the value for the inhabitants of the air (fluctuates much less, usually from -2 to + 40 ° C) |
|
Oxygen |
Minor (mostly in excess) |
Essential (often in short supply) |
|
suspended solids |
unimportant; not used for food (mainly mineral) |
Important (food source, especially organic matter) |
|
Solutes in the environment |
To some extent (only relevant in soil solutions) |
Important (in a certain amount needed) |
The impact of the above factors is inextricably linked with the movement of air masses - the wind. In the process of evolution, living organisms of the terrestrial-air environment have developed characteristic anatomical, morphological, physiological, behavioral and other adaptations. For example, organs have appeared that provide direct assimilation of atmospheric oxygen in the process of respiration (lungs and tracheae of animals, stomata of plants). Skeletal formations (the skeleton of animals, the mechanical and supporting tissues of plants) that support the body under conditions of low density of the medium have received a strong development. Adaptations have been developed to protect against adverse factors, such as the frequency and rhythm of life cycles, the complex structure of the integument, the mechanisms of thermoregulation, etc. close connection with the soil (the limbs of animals, the roots of plants), the mobility of animals developed in search of food, seeds, fruits and pollen of plants carried by air currents, flying animals appeared.
Let us consider the features of the impact of the main environmental factors on plants and animals in the ground-air environment of life.
Low air density determines its low lift and negligible disputability. All inhabitants of the air environment are closely connected with the surface of the earth, which serves them for attachment and support. The density of the air environment does not provide high resistance to the body when they move along the surface of the earth, however, it makes it difficult to move vertically. For most organisms, staying in the air is associated only with dispersal or the search for prey.
The small lifting force of air determines the limiting mass and size of terrestrial organisms. The largest animals on the surface of the earth are smaller than the giants of the aquatic environment. Large mammals (the size and weight of a modern whale) could not live on land, as they would be crushed by their own weight. The giant lizards of the Mesozoic led a semi-aquatic lifestyle. Another example: high erect sequoia plants (Sequoja sempervirens), reaching 100 m, have a powerful supporting wood, while in the thalli of the giant brown algae Macrocystis, growing up to 50 m, the mechanical elements are only very weakly isolated in the core part of the thallus.
Low air density creates a slight resistance to movement. The ecological benefits of this property of the air environment were used by many terrestrial animals in the course of evolution, acquiring the ability to fly. 75% of all land animal species are capable of active flight. These are mostly insects and birds, but there are also mammals and reptiles. Land animals fly mainly with the help of muscular effort. Some animals can also glide using air currents.
Due to the mobility of air that exists in the lower layers of the atmosphere, the vertical and horizontal movement of air masses, passive flight of certain types of organisms is possible, developed anemochoria -- settlement by means of air currents. Organisms that are passively carried by air currents are collectively called aeroplankton, by analogy with the planktonic inhabitants of the aquatic environment. For passive flight along N.M. Chernova, A.M. Bylovoy (1988) organisms have special adaptations - small body sizes, an increase in its area due to outgrowths, strong dissection, a large relative surface of the wings, the use of cobwebs, etc.
Anemochore seeds and fruits of plants also have very small sizes (for example, fireweed seeds) or various wing-shaped (Acer pseudoplatanum maple) and parachute-like (Taraxacum officinale dandelion) appendages.
Wind pollinated plants have a number of adaptations that improve the aerodynamic properties of pollen. Their flower covers are usually reduced and the anthers are not protected from the wind.
In the settlement of plants, animals and microorganisms, the main role is played by vertical conventional air currents and weak winds. Storms and hurricanes also have a significant environmental impact on terrestrial organisms. Quite often, strong winds, especially those blowing in one direction, bend the branches of trees, trunks to the leeward side and cause the formation of flag-like crown shapes.
In areas where strong winds are constantly blowing, as a rule, the species composition of small flying animals is poor, since they are not able to resist powerful air currents. So, the honey bee flies only when the wind strength is up to 7 - 8 m/s, and the aphids - when the wind is very weak, not exceeding 2.2 m/s. The animals of these places develop dense covers that protect the body from cooling and moisture loss. On oceanic islands with constant strong winds, birds and especially insects that have lost the ability to fly predominate, they lack wings, because those who are able to fly into the air are blown into the sea by the wind and they die.
The wind causes a change in the intensity of transpiration in plants and is especially pronounced during dry winds that dry up the air, and can lead to the death of plants. The main ecological role of horizontal air movements (winds) is indirect and consists in strengthening or weakening the impact on terrestrial organisms of such important environmental factors as temperature and humidity. Winds increase the return of moisture and heat to animals and plants.
With wind, heat is more easily tolerated and frosts are more difficult, desiccation and cooling of organisms occur faster.
Terrestrial organisms exist under conditions of relatively low pressure, which is due to the low density of air. In general, terrestrial organisms are more stenobatic than aquatic ones, because the usual pressure fluctuations in their environment are fractions of the atmosphere, and for climbing great height, for example, birds, do not exceed 1/3 of normal.
Gas composition of air, as already discussed earlier, in the surface layer of the atmosphere it is rather uniform (oxygen - 20.9%, nitrogen - 78.1%, m.g. gases - 1%, carbon dioxide - 0.03% by volume) due to its high diffusion capacity and constant mixing by convection and wind currents. At the same time, various impurities of gaseous, droplet-liquid, dust (solid) particles entering the atmosphere from local sources often have significant environmental significance.
Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment. The high oxygen content contributed to an increase in the metabolism of terrestrial organisms, and on the basis of the high efficiency of oxidative processes, homoiothermia of animals arose. Only in places, under specific conditions, a temporary oxygen deficiency is created, for example, in decaying plant residues, stocks of grain, flour, etc.
In some areas of the surface layer of air, the content of carbon dioxide can vary within fairly significant limits. So, in the absence of wind in large industrial centers, cities, its concentration can increase tenfold.
Daily changes in the content of carbonic acid in the surface layers are regular, due to the rhythm of plant photosynthesis (Fig. 17).
Rice. 17. Daily changes in the vertical profile of CO 2 concentration in forest air (from W. Larcher, 1978)
Using the example of daily changes in the vertical profile of CO 2 concentration in forest air, it is shown that in the daytime, at the level of tree crowns, carbon dioxide is consumed for photosynthesis, and in the absence of wind, a zone poor in CO 2 (305 ppm) is formed here, into which CO enters from the atmosphere and soil (soil respiration). At night, a stable air stratification is established with an increased concentration of CO 2 in the subsoil layer. Seasonal fluctuations in carbon dioxide are associated with changes in the intensity of respiration of living organisms, mostly soil microorganisms.
Carbon dioxide is toxic in high concentrations, but such concentrations are rare in nature. The low content of CO 2 inhibits the process of photosynthesis. To increase the rate of photosynthesis in the practice of greenhouses and greenhouses (under closed ground conditions), the concentration of carbon dioxide is often artificially increased.
For most inhabitants of the terrestrial environment, air nitrogen is an inert gas, but microorganisms such as nodule bacteria, azotobacteria, and clostridia have the ability to bind it and involve it in the biological cycle.
The main modern source of physical and chemical pollution of the atmosphere is anthropogenic: industrial and transport enterprises, soil erosion, etc. Thus, sulfur dioxide is poisonous to plants in concentrations from one fifty-thousandth to one millionth of the volume of air. Lichens die already at traces of sulfur dioxide in the environment. Therefore, especially sensitive plants to SO 2 are often used as indicators of its content in the air. Common spruce and pine, maple, linden, birch are sensitive to smoke.
Light mode. The amount of radiation reaching the Earth's surface is determined by the geographic latitude of the area, the length of the day, the transparency of the atmosphere and the angle of incidence of the sun's rays. Under different weather conditions, 42-70% of the solar constant reaches the Earth's surface. Passing through the atmosphere, solar radiation undergoes a number of changes not only in quantitative terms, but also in composition. Shortwave radiation is absorbed by the ozone screen and atmospheric oxygen. Infrared rays are absorbed in the atmosphere by water vapor and carbon dioxide. The rest in the form of direct or scattered radiation reaches the Earth's surface.
The total of direct and scattered solar radiation is from 7 to 7n of total radiation, while on cloudy days the scattered radiation is 100%. In high latitudes diffuse radiation prevails, in the tropics - direct radiation. Scattered radiation contains at noon yellow-red rays up to 80%, direct - from 30 to 40%. On clear sunny days, solar radiation reaching the Earth's surface is 45% visible light (380 - 720 nm) and 45% infrared radiation. Only 10% is accounted for by ultraviolet radiation. The dust content of the atmosphere has a significant effect on the radiation regime. Due to its pollution, in some cities the illumination can be 15% or less than the illumination outside the city.
Illumination on the Earth's surface varies widely. It all depends on the height of the Sun above the horizon or the angle of incidence of the sun's rays, the length of the day and weather conditions, and the transparency of the atmosphere (Fig. 18).
Rice. eighteen. Distribution of solar radiation depending on the height of the Sun above the horizon (A 1 - high, A 2 - low)
Light intensity also fluctuates depending on the time of year and time of day. In some areas of the Earth, the quality of light is also unequal, for example, the ratio of long-wave (red) and short-wave (blue and ultraviolet) rays. Shortwave rays, as is known, are more absorbed and scattered by the atmosphere than longwave ones. In mountainous areas, therefore, there is always more short-wave solar radiation.
Trees, shrubs, plant crops shade the area, create a special microclimate, weakening the radiation (Fig. 19).
Rice. 19.
A - in a rare pine forest; B - in corn crops From the incoming photosynthetically active radiation 6--12% is reflected (R) from the planting surface
Thus, in different habitats, not only the intensity of radiation, but also its spectral composition, the duration of illumination of plants, the spatial and temporal distribution of light of different intensities, etc. . As we noted earlier, in relation to light, three main groups of plants are distinguished: light-loving(heliophytes), shade-loving(Sciophytes) and shade-tolerant. Light-loving and shade-loving plants differ in the position of the ecological optimum.
In light-loving plants, it is in the area of full sunlight. Strong shading has a depressing effect on them. These are plants of open areas of land or well-lit steppe and meadow grasses (upper tier of herbage), rock lichens, early spring herbaceous plants of deciduous forests, most cultivated plants of open ground and weeds, etc. Shade-loving plants have an optimum in low light and cannot stand strong light. These are mainly the lower shaded tiers of complex plant communities, where the shading is the result of the “interception” of light by taller plants and cohabitants. This includes many indoor and greenhouse plants. For the most part, these are natives of the herbaceous cover or flora of tropical forest epiphytes.
The ecological curve of relation to light is also somewhat asymmetric in shade-tolerant ones, since they grow and develop better in full light, but they also adapt well to low light. It is a common and highly flexible group of plants in terrestrial environments.
Plants of the ground-air environment have developed adaptations to various conditions of the light regime: anatomical-morphological, physiological, etc.
A good example of anatomical and morphological adaptations is the change in appearance in different light conditions, for example, the unequal size of leaf blades in plants related in systematic position, but living in different lighting conditions (meadow bell - Campanula patula and forest - C. trachelium, field violet -- Viola arvensis, growing in fields, meadows, forest edges, and forest violets -- V. mirabilis), fig. twenty.
Rice. twenty. Distribution of leaf sizes depending on plant habitat conditions: from wet to dry and from shaded to sunny
Note. The shaded area corresponds to the conditions prevailing in nature.
Under conditions of excess and lack of light, the arrangement of leaf blades in plants in space varies significantly. In heliophyte plants, the leaves are oriented towards reducing the arrival of radiation during the most “dangerous” daytime hours. Leaf blades are located vertically or at a large angle to the horizontal plane, so during the day the leaves mostly receive gliding rays (Fig. 21).
This is especially pronounced in many steppe plants. An interesting adaptation to the weakening of the received radiation in the so-called "compass" plants (wild lettuce - Lactuca serriola, etc.). The leaves of wild lettuce are located in the same plane, oriented from north to south, and at noon the arrival of radiation to the leaf surface is minimal.
In shade-tolerant plants, the leaves are arranged so as to receive the maximum amount of incident radiation.
Rice. 21.
1,2 - leaves with different angles of inclination; S 1 , S 2 - the flow of direct radiation to them; S total -- its total intake to the plant
Often shade-tolerant plants are capable of protective movements: changing the position of leaf blades when strong light hits them. Plots of grass cover with folded oxalis leaves relatively exactly coincide with the location of large solar patches of light. A number of adaptive features can be noted in the structure of the leaf as the main receiver of solar radiation. For example, in many heliophytes, the leaf surface contributes to the reflection of sunlight (shiny - in laurel, covered with a light hairy coating - in cactus, milkweed) or weakening their action (thick cuticle, dense pubescence). The internal structure of the leaf is characterized by a powerful development of palisade tissue, the presence of a large number of small and light chloroplasts (Fig. 22).
One of the protective reactions of chloroplasts to excess light is their ability to change orientation and move in the cell, which is pronounced in light plants.
In bright light, chloroplasts occupy a venerable position in the cell and become an "edge" to the direction of the rays. In low light, they are diffusely distributed in the cell or accumulate in its lower part.
Rice. 22.
1 - yew; 2 - larch; 3 - hoof; 4 - spring chistyak (According to T. K. Goryshina, E. G. Springs, 1978)
Physiological adaptations plants to the light conditions of the ground-air environment cover various vital functions. It has been established that growth processes in light-loving plants react more sensitively to a lack of light compared to shade ones. As a result, an increased elongation of the stems is observed, which helps the plants to break through to the light, into the upper tiers of plant communities.
The main physiological adaptations to light lie in the field of photosynthesis. In a general form, the change in photosynthesis depending on the intensity of light is expressed by the "photosynthesis light curve". The following parameters are of ecological importance (Fig. 23).
- 1. The point of intersection of the curve with the y-axis (Fig. 23, a) corresponds to the magnitude and direction of plant gas exchange in complete darkness: there is no photosynthesis, respiration takes place (not absorption, but release of CO 2), therefore point a lies below the abscissa axis.
- 2. The point of intersection of the light curve with the abscissa axis (Fig. 23, b) characterizes the "compensation point", i.e., the intensity of light at which photosynthesis (the absorption of CO 2) balances respiration (the release of CO 2).
- 3. The intensity of photosynthesis with increasing light increases only up to a certain limit, then remains constant - the light curve of photosynthesis reaches a "saturation plateau".
Rice. 23.
A - general scheme; B - curves for light-loving (1) and shade-tolerant (2) plants
On fig. 23, the inflection area is conditionally indicated by a smooth curve, the break of which corresponds to the point in. The projection of the point at on the abscissa axis (point d) characterizes the "saturated" light intensity, i.e., such a value, above which the light no longer increases the intensity of photosynthesis. Projection onto the y-axis (point e) corresponds to the highest intensity of photosynthesis for a given species in a given ground-air environment.
4. An important characteristic of the light curve is the angle of inclination (a) to the abscissa, which reflects the degree of increase in photosynthesis with increasing radiation (in the region of relatively low light intensity).
Plants show seasonal dynamics in their reaction to light. Thus, in the early spring in the forest, newly appeared leaves of the hairy sedge (Carex pilosa) in the forest have a plateau of light saturation of photosynthesis for 20-25 thousand lux, during summer shading in these species, the curves of dependence of photosynthesis on light become i.e., the leaves acquire the ability to use weak light more efficiently; these same leaves, after overwintering under the canopy of a leafless spring forest, again reveal the "light" features of photosynthesis.
A peculiar form of physiological adaptation with a sharp lack of light is the loss of the plant's ability to photosynthesis, the transition to heterotrophic nutrition with ready-made organic substances. Sometimes such a transition became irreversible due to the loss of chlorophyll by plants, for example, orchids of shady spruce forests (Goodyera repens, Weottia nidus avis), aquatic worms (Monotropa hypopitys). They live on dead organic matter obtained from tree species and other plants. This method of nutrition is called saprophytic, and plants are called saprophytes.
For the vast majority of terrestrial animals with day and night activity, vision is one of the ways of orientation, which is important for the search for prey. Many animal species also have color vision. In this regard, the animals, especially the victims, developed adaptive features. These include protective, masking, and warning coloration, protective resemblance, mimicry, etc. The appearance of brightly colored flowers of higher plants is also associated with the characteristics of the visual apparatus of pollinators and, ultimately, with the light regime of the environment.
water regime. Moisture deficiency is one of the most significant features of the ground-air environment of life. The evolution of terrestrial organisms took place by adapting to the extraction and conservation of moisture. The modes of environmental humidity on land are varied - from the complete and constant saturation of air with water vapor, where several thousand millimeters of precipitation falls annually (regions of the equatorial and monsoon-tropical climate) to their almost complete absence in the dry air of deserts. So, in tropical deserts, the average annual rainfall is less than 100 mm per year, and at the same time it does not rain every year.
The annual amount of precipitation does not always make it possible to assess the water availability of organisms, since the same amount of precipitation can characterize a desert climate (in the subtropics) and very humid (in the Arctic). An important role is played by the ratio of precipitation and evaporation (total annual evaporation from the free water surface), which is also not the same in different regions of the globe. Areas where this value exceeds the annual amount of precipitation are called arid(dry, arid). Here, for example, plants experience a lack of moisture during most of the growing season. The areas in which plants are provided with moisture are called humid, or wet. Often there are also transitional zones - semiarid(semiarid).
The dependence of vegetation on the average annual precipitation and temperature is shown in fig. 24.
Rice. 24.
1 - tropical forest; 2 - deciduous forest; 3 - steppe; 4 - desert; 5 - coniferous forest; 6 -- arctic and mountain tundra
The water supply of terrestrial organisms depends on the mode of precipitation, the presence of reservoirs, soil moisture reserves, the proximity of groundwater, etc. This contributed to the development of many adaptations in terrestrial organisms to various water supply regimes.
On fig. 25 from left to right shows the transition from lower algae living in the water with cells without vacuoles to primary poikilohydric terrestrial algae, the formation of vacuoles in aquatic green and charophyte algae, the transition from tallophytes with vacuoles to homoiohydric cormophytes (the distribution of mosses - hydrophytes is still limited to habitats with high humidity air, in dry habitats mosses become secondarily poikilohydric); among ferns and angiosperms (but not among gymnosperms) there are also secondary poikilohydric forms. Most leafy plants are homoiohydric due to the presence of cuticular protection against transpiration and strong vacuolization of their cells. It should be noted that the xerophilicity of animals and plants is characteristic only of the ground-air environment.
Rice. 2
Precipitation (rain, hail, snow), in addition to providing water and creating moisture reserves, often play another ecological role. For example, during heavy rains, the soil does not have time to absorb moisture, water flows quickly in strong streams and often carries weakly rooted plants, small animals and fertile soil into lakes and rivers. In floodplains, rains can cause floods and thus adversely affect the plants and animals that live there. In periodically flooded places, peculiar floodplain fauna and flora are formed.
Hail also has a negative effect on plants and animals. Crops of agricultural crops in some fields are sometimes completely destroyed by this natural disaster.
The ecological role of snow cover is diverse. For plants whose renewal buds are in the soil or near its surface, snow plays the role of a heat-insulating cover for many small animals, protecting them from low winter temperatures. At frosts above -14°C, under a layer of snow of 20 cm, the soil temperature does not fall below 0.2°C. Deep snow cover protects the green parts of plants from freezing, such as Veronica officinalis, wild hoof, etc., which go under the snow without shedding their leaves. Small terrestrial animals lead an active lifestyle in winter, laying numerous galleries of passages under the snow and in its thickness. In the presence of fortified food in snowy winters, rodents (wood and yellow-throated mice, a number of voles, a water rat, etc.) can breed there. Grouse, partridges, black grouse hide under the snow in severe frosts.
For large animals, winter snow cover often prevents them from foraging and moving around, especially when an ice crust forms on the surface. Thus, moose (Alces alces) freely overcome a layer of snow up to 50 cm deep, but this is not available to smaller animals. Often, during snowy winters, the death of roe deer and wild boars is observed.
A large amount of snowfall also has a negative effect on plants. In addition to mechanical damage in the form of snow breaks or snow drifts, a thick layer of snow can lead to dampening of plants, and during snowmelt, especially in a long spring, to wetting of plants.
Rice. 26.
Plants and animals suffer from low temperatures with strong winds in winters with little snow. So, in years when there is little snow, mouse-like rodents, moles and other small animals die. At the same time, in latitudes where precipitation in the form of snow falls in winter, plants and animals have historically adapted to life in snow or on its surface, having developed various anatomical, morphological, physiological, behavioral and other features. For example, in some animals, the supporting surface of the legs increases in winter by fouling them with coarse hair (Fig. 26), feathers, and horny shields.
Others migrate or fall into an inactive state - sleep, hibernation, diapause. A number of animals switch to feeding on certain types of feed.
Rice. 5.27.
The whiteness of the snow cover unmasks dark animals. The seasonal change of color in the white and tundra partridge, ermine (Fig. 27), mountain hare, weasel, arctic fox, is undoubtedly associated with selection for camouflage to match the background color.
Precipitation, in addition to a direct effect on organisms, determines one or another air humidity, which, as already noted, plays an important role in the life of plants and animals, since it affects the intensity of their water exchange. Evaporation from the surface of the body of animals and transpiration in plants are the more intense, the less air is saturated with water vapor.
Absorption by the aerial parts of drop-liquid moisture falling in the form of rain, as well as vaporous moisture from the air, in higher plants is found in epiphytes of tropical forests, which absorb moisture on the entire surface of leaves and aerial roots. Vaporous moisture from the air can absorb the branches of some shrubs and trees, such as saxaul - Halaxylon persicum, H. aphyllum. In higher spore and especially lower plants, the absorption of moisture by the aerial parts is in the usual way water supply (mosses, lichens, etc.). With a lack of moss moisture, lichens are able to survive for a long time in a state close to air-dry, falling into suspended animation. But as soon as it rains, these plants quickly absorb moisture with all ground units, acquire softness, restore turgor, resume the processes of photosynthesis and growth.
Plants in highly humid terrestrial habitats often need to remove excess moisture. As a rule, this happens when the soil is well warmed up and the roots actively absorb water, and there is no transpiration (in the morning or during fog, when the air humidity is 100%).
Excess moisture is removed by guttations -- this is the release of water through special excretory cells located along the edge or on the tip of the leaf (Fig. 28).
Rice. 28.
1 - in cereals, 2 - in strawberries, 3 - in tulips, 4 - in milkweed, 5 - in Sarmatian bellevalia, 6 - in clover
Not only hygrophytes are capable of guttation, but also many mesophytes. For example, guttation was found in more than half of all plant species in the Ukrainian steppes. Many meadow grasses are gutted so strongly that they moisten the surface of the soil. This is how animals and plants adapt to the seasonal distribution of precipitation, to its quantity and nature. This determines the composition of plants and animals, the timing of the flow of certain phases in the cycle of their development.
Humidity is also influenced by the condensation of water vapor, which often occurs in the surface layer of air when the temperature changes. Dew drops appear when the temperature drops in the evening. Often, dew falls in such quantity that it wets plants abundantly, flows into the soil, increases air humidity and creates favorable conditions for living organisms, especially when there is little other precipitation. Plants contribute to the precipitation of dew. Cooling at night, they condense water vapor on themselves. The humidity regime is significantly affected by fogs, thick clouds and other natural phenomena.
When quantitatively characterizing the habitat of plants by the water factor, indicators are used that reflect the content and distribution of moisture not only in the air, but also in the soil. ground water, or soil moisture, is one of the main sources of moisture for plants. Water in the soil is in a fragmented state, interspersed in pores of various sizes and shapes, has a large interface with the soil, and contains a number of cations and anions. Hence, soil moisture is heterogeneous in physical and chemical properties. Not all water contained in the soil can be used by plants. According to the physical state, mobility, availability and importance for plants, soil water is divided into gravitational, hygroscopic and capillary.
The soil also contains vaporous moisture, which occupies all the pores free from water. This is almost always (except for desert soils) saturated water vapor. When the temperature drops below 0 ° C, soil moisture turns into ice (at first, free water, and with further cooling, part of the bound water).
The total amount of water that can be held by the soil (determined by adding excess water and then waiting until it stops dripping) is called field capacity.
Consequently, the total amount of water in the soil cannot characterize the degree of provision of plants with moisture. To determine it, the wilting coefficient must be subtracted from the total amount of water. However, physically available soil water is not always physiologically available to plants due to low soil temperature, lack of oxygen in soil water and soil air, soil acidity, and high concentration of mineral salts dissolved in soil water. The discrepancy between the absorption of water by the roots and its release by the leaves leads to the wilting of plants. The development of not only the aboveground parts, but also the root system of plants depends on the amount of physiologically available water. In plants growing on dry soils, the root system, as a rule, is more branched, more powerful than on wet soils (Fig. 29).
Rice. 29.
1 - with a large amount of precipitation; 2 - with an average; 3 -- with small
One of the sources of soil moisture is groundwater. At their low level, capillary water does not reach the soil and does not affect its water regime. Moistening the soil due to precipitation alone causes strong fluctuations in its moisture content, which often negatively affects plants. A too high level of groundwater also has a harmful effect, because this leads to waterlogging of the soil, depletion of oxygen and enrichment with mineral salts. Constant soil moisture, regardless of the vagaries of the weather, provides an optimal level of groundwater.
Temperature regime. hallmark ground-air environment is a large range of temperature fluctuations. In most land areas, daily and annual temperature amplitudes are tens of degrees. Changes in air temperature are especially significant in deserts and subpolar continental regions. For example, the seasonal range of temperature in the deserts of Central Asia is 68--77°С, and the daily range is 25--38°С. In the vicinity of Yakutsk, the average January air temperature is -43°C, the average July temperature is +19°C, and the annual range is from -64 to +35°C. In the Trans-Urals, the annual course of air temperature is sharp and is combined with a large variability in the temperatures of the winter and spring months in different years. The coldest month is January, the average air temperature ranges from -16 to -19°C, in some years it drops to -50°C, the warmest month is July with temperatures from 17.2 to 19.5°C. The maximum plus temperatures are 38--41°C.
Temperature fluctuations on the soil surface are even more significant.
Terrestrial plants occupy a zone adjacent to the soil surface, i.e., to the “interface”, on which the transition of incident rays from one medium to another or, in another way, from transparent to opaque, takes place. A special thermal regime is created on this surface: during the day - strong heating due to the absorption of heat rays, at night - strong cooling due to radiation. From here, the surface layer of air experiences the sharpest daily temperature fluctuations, which are most pronounced over bare soil.
The thermal regime of a plant habitat, for example, is characterized on the basis of temperature measurements directly in the canopy. In herbaceous communities, measurements are taken inside and on the surface of the herbage, and in forests, where there is a certain vertical temperature gradient, at a number of points at different heights.
Resistance to temperature changes in the environment in terrestrial organisms is different and depends on the specific habitat where they live. Thus, terrestrial leafy plants for the most part grow in a wide temperature range, that is, they are eurythermal. Their life interval in the active state extends, as a rule, from 5 to 55°C, while between 5 and 40°C these plants are productive. Plants of continental regions, which are characterized by a clear diurnal temperature variation, develop best when the night is 10-15°C colder than the day. This applies to most plants of the temperate zone - with a temperature difference of 5--10 ° C, and tropical plants with an even smaller amplitude - about 3 ° C (Fig. 30).
Rice. thirty.
In poikilothermic organisms, with an increase in temperature (T), the duration of development (t) decreases more and more rapidly. The development rate Vt can be expressed by the formula Vt = 100/t.
To achieve a certain stage of development (for example, in insects - from an egg), i.e. pupation, the imaginal stage, always requires a certain sum of temperatures. The product of effective temperature (temperature above the zero point of development, i.e., T--To) and the duration of development (t) gives the species-specific thermal constant development c=t(T-To). Using this equation, it is possible to calculate the time of onset of a certain stage of development, for example, of a plant pest, at which the fight against it is effective.
Plants as poikilothermic organisms do not have their own stable body temperature. Their temperature is determined by the heat balance, i.e., the ratio of absorption and return of energy. These values depend on many properties of both the environment (the size of the radiation arrival, the temperature of the surrounding air and its movement) and the plants themselves (the color and other optical properties of the plant, the size and arrangement of the leaves, etc.). The primary role is played by the cooling effect of transpiration, which prevents strong overheating of plants in hot habitats. As a result of the above reasons, the temperature of plants usually differs (often quite significantly) from the temperature of the surrounding air. Three situations are possible here: the temperature of the plant is above the ambient temperature, below it, equal to or very close to it. The excess of plant temperature over air temperature occurs not only in strongly warmed, but also in colder habitats. This is facilitated by the dark color or other optical properties of plants, which increase the absorption of solar radiation, as well as anatomical and morphological features that reduce transpiration. Arctic plants can heat up quite noticeably (Fig. 31).
Another example is the dwarf willow - Salix arctica in Alaska, in which the leaves are warmer than the air by 2--11 C during the day and even at night hours of the polar "round-the-clock" - by 1--3°C.
For early spring ephemeroids, the so-called "snowdrops", the heating of the leaves provides the possibility of fairly intense photosynthesis on sunny, but still cold spring days. For cold habitats or those associated with seasonal temperature fluctuations, an increase in plant temperature is ecologically very important, since physiological processes become independent, within certain limits, from the surrounding thermal background.
Rice. 31.
On the right - the intensity of life processes in the biosphere: 1 - the coldest layer of air; 2 -- the upper limit of shoot growth; 3, 4, 5 - the zone of the greatest activity of life processes and the maximum accumulation of organic matter; 6 - the level of permafrost and the lower limit of rooting; 7 -- the area of the lowest soil temperatures
A decrease in plant temperature compared to the ambient air is most often observed in strongly illuminated and heated areas of the terrestrial sphere (desert, steppe), where the leaf surface of plants is greatly reduced, and enhanced transpiration helps to remove excess heat and prevents overheating. In general terms, we can say that in hot habitats the temperature of the aboveground parts of plants is lower, and in cold habitats it is higher than the air temperature. The coincidence of plant temperature with the ambient temperature is less common - in conditions that exclude a strong influx of radiation and intensive transpiration, for example, in herbaceous plants under the forest canopy, and on open areas- in cloudy or rainy weather.
In general, terrestrial organisms are more eurythermic than aquatic ones.
In the ground-air environment, living conditions are complicated by the existence weather changes. Weather is the continuously changing state of the atmosphere near the earth's surface, up to about 20 km (the troposphere boundary). Weather variability is manifested in the constant variation of the combination of such environmental factors as air temperature and humidity, cloudiness, precipitation, wind strength and direction, etc. (Fig. 32).
Rice. 32.
Along with their regular alternation in the annual cycle, weather changes are characterized by non-periodic fluctuations, which significantly complicate the conditions for the existence of terrestrial organisms. On fig. 33, using the example of the caterpillar of the codling moth Carpocapsa pomonella, the dependence of mortality on temperature and relative humidity is shown.
Rice. 33.
It follows that the curves of equal mortality are concentric and that the optimal zone is limited by relative humidity of 55 and 95% and temperatures of 21 and 28°C.
Light, temperature, and air humidity in plants usually determine not the maximum, but the average degree of opening of the stomata, since the coincidence of all the conditions conducive to their opening rarely happens.
The long-term weather regime characterizes the climate of the area. The concept of climate includes not only the average values of meteorological phenomena, but also their annual and daily variations, deviation from it, and their frequency. The climate is determined by the geographical conditions of the area.
The main climatic factors are temperature and humidity, measured by the amount of precipitation and the saturation of the air with water vapor. Thus, in countries far from the sea, there is a gradual transition from a humid climate through a semi-arid intermediate zone with occasional or periodic dry periods to an arid territory, which is characterized by prolonged drought, soil and water salinization (Fig. 34).
Rice. 34.
Note: where the precipitation curve crosses the ascending evaporation line, there is a boundary between humid (left) and arid (right) climates. Black shows the humus horizon, hatching shows the illuvial horizon.
Each habitat is characterized by a certain ecological climate, i.e., the climate of the surface layer of air, or ecoclimate.
Vegetation has a great influence on climatic factors. So, under the canopy of the forest, the humidity of the air is always higher, and the temperature fluctuations are less than in the glades. The light regime of these places is also different. In different plant associations, their own regime of light, temperature, humidity is formed, i.e., a kind phytoclimate.
Ecoclimate or phytoclimate data are not always sufficient to fully characterize the climatic conditions of a given habitat. Local elements of the environment (relief, exposure, vegetation, etc.) very often change the regime of light, temperature, humidity, and air movement in a particular area in such a way that it can differ significantly from the climatic conditions of the area. Local climate modifications that take shape in the surface air layer are called microclimate. For example, the living conditions surrounding insect larvae living under the bark of a tree are different than in the forest where this tree grows. The temperature of the southern side of the trunk can be 10-15°C higher than the temperature of its northern side. Burrows inhabited by animals, hollows of trees, caves have a stable microclimate. There are no clear differences between ecoclimate and microclimate. It is believed that the ecoclimate is the climate of large areas, and the microclimate is the climate of individual small areas. The microclimate has an impact on the living organisms of a particular territory, area (Fig. 35).
Rice. 3
above - a well-heated slope of southern exposure;
below - a horizontal section of the plakor (the floristic composition is the same in both sections)
The presence in one locality of many microclimates ensures the coexistence of species with different requirements for the external environment.
Geographical zonality and zonality. The distribution of living organisms on Earth is closely related to geographical zones and zones. The belts have a latitudinal strike, which, of course, is primarily due to radiation barriers and the nature of atmospheric circulation. On the surface of the globe, 13 geographical zones are distinguished, which are distributed on the continents and oceans (Fig. 36).
Rice. 36.
These are like arctic, antarctic, subarctic, subantarctic, northern and southern moderate, northern and southern subarctic, northern and southern tropical, northern and southern subequatorial and equatorial. Inside the belts allocate geographic areas, where, along with radiation conditions, the moistening of the earth's surface and the ratio of heat and moisture characteristic of a given zone are taken into account. In contrast to the ocean, where the moisture supply is complete, on the continents, the ratio of heat and moisture can have significant differences. From here, geographical zones extend to the continents and oceans, and geographical zones - only to the continents. Distinguish latitudinal and meridial or longitude natural zones. The former stretch from west to east, the latter from north to south. Longitudinally, latitudinal zones are subdivided into subzones, and in latitude provinces.
The founder of the doctrine of natural zoning is V. V. Dokuchaev (1846-1903), who substantiated zoning as a universal law of nature. All phenomena within the biosphere are subject to this law. The main reasons for zoning are the shape of the Earth and its position relative to the sun. The distribution of heat on Earth, in addition to latitude, is influenced by the nature of the relief and the height of the terrain above sea level, the ratio of land and sea, sea currents, etc.
Subsequently, the radiation bases for the formation of the zoning of the globe were developed by A. A. Grigoriev and M. I. Budyko. To establish a quantitative characteristic of the ratio of heat and moisture for various geographical zones, they determined some coefficients. The ratio of heat and moisture is expressed as the ratio of the radiation balance of the surface to the latent heat of evaporation and the amount of precipitation (radiation index of dryness). A law was established, called the law of periodic geographical zoning (A. A. Grigorieva - M. I. Budyko), which states, that with the change of geographical zones, similar geographical(landscape, natural) zones and some of their general properties are periodically repeated.
Each zone is confined to a certain range of values-indicators: a special nature of geomorphological processes, a special type of climate, vegetation, soils and wildlife. On the territory of the former USSR, the following geographical zones were noted: ice, tundra, forest-tundra, taiga, mixed forests. Russian Plain, monsoon mixed forests of the Far East, forest-steppes, steppes, semi-deserts, deserts of the temperate zone, deserts of the subtropical zone, the Mediterranean and humid subtropics.
One of the important conditions for the variability of organisms and their zonal distribution on earth is the variability of the chemical composition of the environment. In this regard, the teaching of A.P. Vinogradov about biogeochemical provinces, which are determined by the zonality of the chemical composition of soils, as well as by the climatic, phytogeographical, and geochemical zonality of the biosphere. Biogeochemical provinces are areas on the Earth's surface that differ in content (in soils, waters, etc.) of chemical compounds that are associated with certain biological reactions from local flora and fauna.
Along with horizontal zonality, the terrestrial environment clearly shows high-rise or vertical explanation.
The vegetation of the mountainous countries is richer than on the adjacent plains, and is characterized by an increased distribution of endemic forms. So, according to O. E. Agakhanyants (1986), the flora of the Caucasus includes 6350 species, of which 25% are endemic. The flora of the mountains of Central Asia is estimated at 5,500 species, of which 25-30% are endemic, while on the adjacent plains of the southern deserts there are 200 plant species.
When climbing the mountains, the same change of zones is repeated as from the equator to the poles. Deserts are usually located at the foot, then steppes, broad-leaved forests, coniferous forests, tundra and, finally, ice. However, there is still no complete analogy. When climbing the mountains, the air temperature drops (the average air temperature gradient is 0.6 ° C per 100 m), evaporation decreases, ultraviolet radiation, illumination, etc. increase. All this makes plants adapt to dry or wet harm. Cushion-shaped life forms, perennials, which have developed adaptation to strong ultraviolet radiation and a decrease in transpiration, dominate among plants here.
The fauna of the high mountain regions is also peculiar. Reduced air pressure, significant solar radiation, sharp fluctuations in day and night temperatures, changes in air humidity with altitude contributed to the development of specific physiological adaptations of the organism of mountain animals. For example, in animals, the relative volume of the heart increases, the content of hemoglobin in the blood increases, which allows more intensive absorption of oxygen from the air. Stony soil complicates or almost excludes the burrowing activity of animals. Many small animals (small rodents, pikas, lizards, etc.) find shelter in rock crevices and caves. Mountainous birds are characterized by mountain turkeys (ulars), mountain finches, larks, large birds - bearded vultures, vultures, condors. Large mammals in the mountains are rams, goats (including snow goats), chamois, yaks, etc. Predators are represented by such species as wolves, foxes, bears, lynxes, snow leopards (irbis), etc.
The inanimate and living nature surrounding plants, animals and humans is called the habitat (living environment, external environment). According to the definition of N.P. Naumov (1963), the environment is “everything that surrounds organisms and directly or indirectly affects their state, development, survival and reproduction.” From the habitat, organisms receive everything necessary for life and release the products of their metabolism into it.
Organisms can live in one or more living environments. For example, man, most birds, mammals, seed plants, lichens are inhabitants only of the terrestrial-air environment; most fish live only in the aquatic environment; dragonflies spend one phase in the water, and the other - in the air.
Aquatic life environment
The aquatic environment is characterized by a great originality of the physicochemical properties of organisms favorable for life. Among them: transparency, high thermal conductivity, high density (about 800 times the density of air) and viscosity, expansion upon freezing, the ability to dissolve many mineral and organic compounds, high mobility (fluidity), the absence of sharp temperature fluctuations (both daily and seasonal), the ability to equally easily support organisms that differ significantly in mass.
The unfavorable properties of the aquatic environment are: strong pressure drops, poor aeration (the oxygen content in the aquatic environment is at least 20 times lower than in the atmosphere), lack of light (especially little of it in the depths of water bodies), lack of nitrates and phosphates (necessary for the synthesis of living matter ).
Distinguish between fresh and sea water, which differ both in composition and in the amount of dissolved minerals. Sea water is rich in sodium, magnesium, chloride and sulfate ions, while fresh water is dominated by calcium and carbonate ions.
Organisms living in the aquatic environment of life constitute one biological group - hydrobionts.
In reservoirs, two ecologically special habitats (biotopes) are usually distinguished: the water column (pelagial) and the bottom (benthal). The organisms living there are called pelagos and benthos.
Among the pelagos, the following forms of organisms are distinguished: plankton - passively floating small representatives (phytoplankton and zooplankton); nekton - actively swimming large forms (fish, turtles, cephalopods); neuston - microscopic and small inhabitants of the surface film of water. In fresh water bodies (lakes, ponds, rivers, swamps, etc.), such ecological zoning is not very clearly expressed. The lower limit of life in the pelagial is determined by the depth of penetration of sunlight sufficient for photosynthesis and rarely reaches a depth of more than 2000 m.
In Bentali, special ecological zones of life are also distinguished: a zone of a gradual decrease in land (up to a depth of 200-2200 m); steep slope zone, oceanic bed (with an average depth of 2800-6000 m); depressions of the oceanic bed (up to 10,000 m); the edge of the coast, flooded with tides (littoral). The inhabitants of the littoral live in conditions of abundant sunlight at low pressure, with frequent and significant fluctuations in temperature. The inhabitants of the zone of the oceanic bed, on the contrary, exist in complete darkness, at constantly low temperatures, oxygen deficiency and under enormous pressure, reaching almost a thousand atmospheres.
Ground-air environment of life
The land-air environment of life is the most complex in terms of ecological conditions and has a wide variety of habitats. This led to the greatest diversity of land organisms. The vast majority of animals in this environment move on a solid surface - soil, and plants take root on it. The organisms of this living environment are called aerobionts (terrabionts, from Latin terra - earth).
A characteristic feature of the environment under consideration is that the organisms living here significantly influence the living environment and in many respects create it themselves.
Favorable characteristics of this environment for organisms are the abundance of air with a high content of oxygen and sunlight. Unfavorable features include: sharp fluctuations in temperature, humidity and lighting (depending on the season, time of day and geographical location), constant moisture deficiency and its presence in the form of steam or drops, snow or ice, wind, change of seasons, relief features terrain, etc.
All organisms in the terrestrial-air environment of life are characterized by systems of economical use of water, various mechanisms of thermoregulation, high efficiency of oxidative processes, special organs for the assimilation of atmospheric oxygen, strong skeletal formations that allow the body to be maintained in conditions of low density of the environment, and various adaptations for protection against sudden temperature fluctuations. .
The ground-air environment in terms of its physical and chemical characteristics is considered to be quite severe in relation to all living things. But, despite this, life on land has reached a very high level, both in terms of the total mass of organic matter and in the diversity of forms of living matter.
The soil
The soil environment occupies an intermediate position between the water and ground-air environments. The temperature regime, low oxygen content, moisture saturation, the presence of a significant amount of salts and organic substances bring the soil closer to the aquatic environment. And sharp changes in the temperature regime, desiccation, saturation with air, including oxygen, bring the soil closer to the ground-air environment of life.
Soil is a loose surface layer of land, which is a mixture of mineral substances obtained from the decay of rocks under the influence of physical and chemical agents, and special organic substances resulting from the decomposition of plant and animal remains by biological agents. In the surface layers of the soil, where the freshest dead organic matter enters, many destructive organisms live - bacteria, fungi, worms, the smallest arthropods, etc. Their activity ensures the development of the soil from above, while the physical and chemical destruction of the bedrock contributes to the formation of soil from below.
As a living environment, the soil is distinguished by a number of features: high density, lack of light, reduced amplitude of temperature fluctuations, lack of oxygen, and a relatively high content of carbon dioxide. In addition, the soil is characterized by a loose (porous) structure of the substrate. The existing cavities are filled with a mixture of gases and aqueous solutions, which determines an extremely wide variety of conditions for the life of many organisms. On average, there are more than 100 billion cells of protozoa, millions of rotifers and tardigrades, tens of millions of nematodes, hundreds of thousands of arthropods, tens and hundreds of earthworms, mollusks and other invertebrates, hundreds of millions of bacteria, microscopic fungi (actinomycetes), algae and other microorganisms. The entire population of the soil - edaphobionts (edaphobius, from the Greek edaphos - soil, bios - life) interacts with each other, forming a kind of biocenotic complex, actively participating in the creation of the soil life environment itself and ensuring its fertility. Species inhabiting the soil environment of life are also called pedobionts (from the Greek paidos - a child, i.e., passing through the stage of larvae in their development).
The representatives of edaphobius in the process of evolution developed peculiar anatomical and morphological features. For example, animals have a valky body shape, small size, relatively strong integument, skin respiration, eye reduction, colorless integument, saprophagy (the ability to feed on the remains of other organisms). In addition, along with aerobicity, anaerobicity (the ability to exist in the absence of free oxygen) is widely represented.
The body as a living environment
As a living environment, the organism for its inhabitants is characterized by such positive features as: easily digestible food; constancy of temperature, salt and osmotic regimes; no risk of drying out; protection from enemies. Problems for the inhabitants of organisms are created by factors such as: lack of oxygen and light; limited living space; the need to overcome the protective reactions of the host; spread from one host to other hosts. In addition, this environment is always limited in time by the life of the host.
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