What are the organisms that inhabit the terrestrial air environment called? What animals live in the air? Test questions and assignments
Ground-air environment- this is the entire surface of the planet, which is limited by a solid surface. Animals, plants, mushrooms, etc. live in the ground-air environment.
General characteristics. In the course of evolution, the land-air environment was mastered much later than the aquatic environment. Life on land required adaptations that became possible only with a relatively high level of organization in 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, and high oxygen content. Typically, animals in this environment move on the soil (hard substrate) and plants take root in it.
In the ground-air environment, the operating environmental factors have a number of characteristic features: higher light intensity compared to other environments, significant temperature fluctuations, changes in humidity depending on geographical location, season and time of day. The impact of the above factors is inextricably linked with the movement of air masses - wind. In the process of evolution, living organisms of the land-air environment have developed characteristic anatomical, morphological, physiological, behavioral and other adaptations. For example, organs have appeared that provide direct absorption of atmospheric oxygen during respiration (the lungs and trachea of animals, the stomata of plants). Skeletal formations have received strong development (animal skeleton, mechanical and supporting tissues of plants), which support the body in conditions of low environmental density. Adaptations have been developed to protect against unfavorable factors, such as the periodicity and rhythm of life cycles, the complex structure of the integument, mechanisms of thermoregulation, etc. A close connection with the soil has formed (animal limbs, plant roots), the mobility of animals in search of food has developed, and air currents have appeared. seeds, fruits and pollen of plants, flying animals.
Air density- mass of gas in the Earth’s atmosphere per unit volume or specific gravity of air under natural conditions. The value of air density is a function of the height of the measurements taken, its temperature and humidity. Typically, the standard value is 1.225 kg⁄m3, which corresponds to the density of dry air at 15°C at sea level.
Gas composition of air, as already discussed earlier, in the surface layer of the atmosphere is quite homogeneous (oxygen - 20.9%, nitrogen - 78.1%, m.g. gases - 1%, carbon dioxide- 0.03% by volume) due to its high diffusion ability and constant mixing by convection and wind flows. 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 metabolism in terrestrial organisms, and animal homeothermy arose on the basis of the high efficiency of oxidative processes. Only in places, under specific conditions, is a temporary oxygen deficiency created, for example, in decomposing plant debris, grain reserves, flour, etc.
In certain areas of the surface air layer, the carbon dioxide content can vary within fairly significant limits. Thus, in the absence of wind in large industrial centers and cities, its concentration can increase tenfold.
There are regular daily changes in the content of carbon dioxide in the ground layers, determined by the rhythm of plant photosynthesis.
Compiled from: A.S. Stepanovskikh. Decree. op. P. 176.
Large fluctuations in temperature in time and space, as well as a good supply of oxygen, led to the emergence of organisms with a constant body temperature (warm-blooded). To maintain the stability of the internal environment of warm-blooded organisms inhabiting the ground-air environment ( terrestrial organisms), increased energy costs are required.
Life in a terrestrial environment is possible only with a high level of organization of plants and animals, adapted to the specific influences of the most important environmental factors of this environment.
In the ground-air environment, the operating environmental factors have a number of characteristic features: higher light intensity compared to other environments, significant fluctuations in temperature and humidity depending on the geographical location, season and time of day.
Let's consider general characteristics ground-air habitat.
For gaseous habitat characterized by low values of humidity, density and pressure, high oxygen content, which determines the characteristics of respiration, water exchange, movement and lifestyle of organisms. The properties of the air environment affect the structure of the bodies of terrestrial animals and plants, their physiological and behavioral characteristics, and also strengthen or weaken the effect of other environmental factors.
The gas composition of the air is relatively constant (oxygen - 21%, nitrogen - 78%, carbon dioxide - 0.03%) both throughout the day and in different periods year. This is due to intense mixing of atmospheric layers.
Absorption of oxygen by organisms from external environment occurs over the entire surface of the body (in protozoa, worms) or special respiratory organs - trachea (in insects), lungs (in vertebrates). Organisms living in conditions of constant lack of oxygen have appropriate adaptations: increased oxygen capacity of the blood, more frequent and deeper respiratory movements, large lung capacity (in the inhabitants of high mountains, birds).
One of the most important and predominant forms of the primary biogenic element carbon in nature is carbon dioxide (carbon dioxide). The near-soil layers of the atmosphere are usually richer in carbon dioxide than its layers at the level of tree crowns, and this to some extent compensates for the lack of light for small plants living under the forest canopy.
Carbon dioxide enters the atmosphere mainly as a result of natural processes (respiration of animals and plants. Combustion processes, volcanic eruptions, activity of soil microorganisms and fungi) and human economic activity (combustion of combustible substances in the field of heat and power engineering, in industrial enterprises and in transport). The amount of carbon dioxide in the atmosphere varies throughout the day and by season. Daily changes are associated with the rhythm of plant photosynthesis, and seasonal changes are associated with the intensity of respiration of organisms, mainly soil microorganisms.
Low air density causes low lifting force, and therefore terrestrial organisms have limited size and mass and have their own support system that supports the body. In plants these are various mechanical tissues, and in animals they are a solid or (less often) hydrostatic skeleton. Many species of terrestrial organisms (insects and birds) have adapted to flight. However, for the vast majority of organisms (with the exception of microorganisms), staying in the air is associated only with settling or searching for food.
Air density is also associated with relatively low pressure on land. The ground-air environment has low atmospheric pressure and low air density, so most actively flying insects and birds occupy the lower zone - 0...1000 m. However, individual inhabitants of the air environment can permanently live at altitudes of 4000...5000 m (eagles , condors).
The mobility of air masses contributes to the rapid mixing of the atmosphere and the uniform distribution of various gases, such as oxygen and carbon dioxide, along the Earth's surface. In the lower layers of the atmosphere, vertical (ascending and descending) and horizontal movement of air masses of varying strength and direction. Thanks to this air mobility, passive flight of a number of organisms is possible: spores, pollen, seeds and fruits of plants, small insects, spiders, etc.
Light mode created by total solar radiation reaching earth's surface. The morphological, physiological and other characteristics of terrestrial organisms depend on the light conditions of a particular habitat.
Light conditions almost everywhere in the ground-air environment are favorable for organisms. The main role is played not by lighting itself, but by the total value solar radiation. In the tropical zone, the total radiation throughout the year is constant, but in temperate latitudes length daylight hours and the intensity of solar radiation depend on the time of year. The transparency of the atmosphere and the angle of incidence are also of great importance. sun rays. Of the incoming photosynthetically active radiation, 6-10% is reflected from the surface of various plantings (Fig. 9.1). The numbers in the figure indicate the relative value of solar radiation as a percentage of the total value at the upper boundary of the plant community. Under different weather conditions, 40...70% of solar radiation reaching the upper boundary of the atmosphere reaches the Earth's surface. Trees, shrubs, and crops shade the area and create a special microclimate, weakening solar radiation.
Rice. 9.1. Attenuation of solar radiation (%):
a - in a rare pine forest; b - in corn crops
Plants have a direct dependence on the intensity of the light regime: they grow where climatic and soil conditions allow, adapting to the light conditions of a given habitat. All plants, in relation to the level of illumination, are divided into three groups: light-loving, shade-loving and shade-tolerant. Light-loving and shade-loving plants differ in the value of the ecological optimum of illumination (Fig. 9.2).
Light-loving plants- plants of open, constantly illuminated habitats, the optimum life activity of which is observed in conditions of full sunlight (steppe and meadow grasses, tundra and highland plants, coastal plants, most open ground cultivated plants, many weeds).
Rice. 9.2. Ecological optimums of the attitude to light of plants of three types: 1-shade-loving; 2 - photophilous; 3 - shade-tolerant
Shade-loving plants- plants that grow only in conditions of strong shading, which do not grow in conditions of strong light. In the process of evolution, this group of plants adapted to the conditions characteristic of the lower shaded tiers of complex plant communities- dark coniferous and deciduous forests, tropical rainforests, etc. The shade-loving nature of these plants is usually combined with a high water requirement.
Shade-tolerant plants They grow and develop better in full light, but are able to adapt to conditions of different levels of darkness.
Representatives of the animal world do not have a direct dependence on the light factor, which is observed in plants. Nevertheless, light in the life of animals plays an important role in visual orientation in space.
A powerful factor regulating the life cycle of a number of animals is the length of daylight hours (photoperiod). The photoperiod response synchronizes the activity of organisms with the seasons. For example, many mammals begin to prepare for hibernation long before the onset of cold weather, and migratory birds fly south already at the end of summer.
Temperature plays a much greater role in the lives of land dwellers than in the lives of hydrosphere dwellers, since a distinctive feature of the land-air environment is a large range temperature fluctuations. The temperature regime is characterized by significant fluctuations in time and space and determines the activity of biochemical processes. Biochemical and morphophysiological adaptations of plants and animals are designed to protect organisms from the adverse effects of temperature fluctuations.
Each species has its own range of the most favorable temperature values for it, which is called temperature optimum of the species. The difference in the ranges of preferred temperature values among different species is very large. Terrestrial organisms live in a wider temperature range than the inhabitants of the hydrosphere. Often habitats eurythermic species extend from south to north across several climate zones. For example, the gray toad inhabits the space from North Africa to Northern Europe. Eurythermal animals include many insects, amphibians, and mammals - fox, wolf, puma, etc.
Long-term dormant ( latent) forms of organisms, such as the spores of some bacteria, spores and plant seeds, are able to withstand significantly different temperatures. Once in favorable conditions and sufficient nutritional environment, these cells can become active again and begin to multiply. The suspension of all vital processes of the body is called suspended animation. From a state of suspended animation, organisms can return to normal activity if the structure of macromolecules in their cells is not disturbed.
Temperature directly affects the growth and development of plants. Being immobile organisms, plants must exist at the temperature regime that is created in the places where they grow. According to the degree of adaptation to temperature conditions, all types of plants can be divided into the following groups:
- frost-resistant- plants growing in areas with a seasonal climate, with cold winters. During severe frosts, the above-ground parts of trees and shrubs freeze, but remain viable, accumulating in their cells and tissues substances that bind water (various sugars, alcohols, some amino acids);
- non-frost-resistant- plants that tolerate low temperatures, but die as soon as ice begins to form in the tissues (some evergreen subtropical species);
- non-cold-resistant- plants that are severely damaged or killed at temperatures above the freezing point of water (tropical rainforest plants);
- thermophilic- plants of dry habitats with strong insolation (solar radiation), which tolerate half-hour heating up to +60 ° C (plants of steppes, savannas, dry subtropics);
- pyrophytes- plants that are resistant to fires when the temperature briefly rises to hundreds of degrees Celsius. These are plants of savannas, dry hard-leaved forests. They have a thick bark, impregnated with fire-resistant substances, which reliably protects the internal tissues. The fruits and seeds of pyrophytes have thick, woody integuments that crack when exposed to fire, which helps the seeds penetrate the soil.
Compared to plants, animals have a more varied ability to regulate (permanently or temporarily) their own body temperature. One of the important adaptations of animals (mammals and birds) to temperature fluctuations is the ability to thermoregulate the body, their warm-bloodedness, due to which higher animals are relatively independent of temperature conditions environment.
In the animal world, there is a connection between the size and proportion of the body of organisms and the climatic conditions of their habitat. Within a species or homogeneous group of closely related species, animals with larger body sizes are common in colder areas. The larger the animal, the easier it is for it to maintain a constant temperature. Thus, among the representatives of penguins, the smallest penguin - the Galapagos penguin - lives in the equatorial regions, and the largest - the emperor penguin - in the mainland zone of Antarctica.
Humidity becomes an important limiting factor on land, since moisture deficiency is one of the most significant features of the land-air environment. Terrestrial organisms are constantly faced with the problem of water loss and require periodic supply. During the evolution of terrestrial organisms, characteristic adaptations for obtaining and preserving moisture were developed.
The humidity regime is characterized by precipitation, soil and air humidity. Moisture deficiency is one of the most significant features of the land-air environment of life. From an ecological point of view, water serves as a limiting factor in terrestrial habitats, since its quantity is subject to strong fluctuations. Humidity regimes on land are varied: from complete and constant saturation of the air with water vapor (tropical zone) to the almost complete absence of moisture in the dry air of deserts.
The main source of water for plant organisms is soil.
In addition to absorbing soil moisture by roots, plants are also capable of absorbing water that falls in the form of light rains, fogs, and vaporous moisture in the air.
Plant organisms lose most of the absorbed water as a result of transpiration, i.e., evaporation of water from the surface of plants. Plants protect themselves from dehydration by either storing water and preventing evaporation (cacti), or by increasing the proportion of underground parts (root systems) in the total volume of the plant organism. According to the degree of adaptation to certain humidity conditions, all plants are divided into groups:
- hydrophytes- terrestrial-aquatic plants growing and freely floating in the aquatic environment (reed along the banks of reservoirs, marsh marigold and other plants in swamps);
- hygrophytes- terrestrial plants in areas with constantly high humidity (inhabitants of tropical forests - epiphytic ferns, orchids, etc.)
- xerophytes- terrestrial plants that have adapted to significant seasonal fluctuations in moisture content in the soil and air (inhabitants of steppes, semi-deserts and deserts - saxaul, camel thorn);
- mesophytes- plants occupying an intermediate position between hygrophytes and xerophytes. Mesophytes are most common in moderately humid zones (birch, rowan, many meadow and forest grasses, etc.).
Weather and climate features characterized by daily, seasonal and long-term fluctuations in temperature, air humidity, cloudiness, precipitation, wind strength and direction, etc. which determines the diversity of living conditions of the inhabitants of the terrestrial environment. Climatic features depend on the geographical conditions of the area, but the microclimate of the immediate habitat of the organisms is often more important.
In the ground-air environment, living conditions are complicated by the existence weather changes. Weather is the continuously changing state of the lower atmosphere up to approximately 20 km altitude (the boundary of the troposphere). Weather variability is a constant change in environmental factors such as air temperature and humidity, cloudiness, precipitation, wind strength and direction, etc.
The long-term weather regime characterizes climate of the area. The concept of climate includes not only the average monthly and average annual values of meteorological parameters (air temperature, humidity, total solar radiation, etc.), but also the patterns of their daily, monthly and annual changes, as well as their frequency. The main climatic factors are temperature and humidity. It should be noted that vegetation has a significant impact on the level of climatic factors. Thus, under the forest canopy, air humidity is always higher, and temperature fluctuations are less than in open areas. The light regime of these places also differs.
Soil serves as a solid support for organisms, which air cannot provide them with. In addition, the root system supplies plants with aqueous solutions of essential mineral compounds from the soil. The chemical and physical properties of soil are important for organisms.
Terrain creates a variety of living conditions for terrestrial organisms, determining the microclimate and limiting the free movement of organisms.
The influence of soil climatic conditions on organisms led to the formation of characteristic natural zones - biomes. This is the name given to the largest terrestrial ecosystems corresponding to the main climatic zones of the Earth. The characteristics of large biomes are determined primarily by the grouping of plant organisms included in them. Each of the physical-geographical zones is characterized by certain ratios of heat and moisture, water and light conditions, type of soil, groups of animals (fauna) and plants (flora). The geographical distribution of biomes is latitudinal in nature and is associated with changes in climatic factors (temperature and humidity) from the equator to the poles. At the same time, a certain symmetry is observed in the distribution of various biomes of both hemispheres. Major biomes of the Earth: tropical forest, tropical savanna, desert, temperate steppe, temperate deciduous forest, coniferous forest(taiga), tundra, arctic desert.
Soil living environment. Among the four living environments we are considering, soil stands out for its close connection between the living and nonliving components of the biosphere. Soil is not only the habitat of organisms, but also a product of their vital activity. It can be considered that the soil arose as a result of the combined action of climatic factors and organisms, especially plants, on the parent rock, that is, on the mineral substances of the upper layer of the earth's crust (sand, clay, stones, etc.).
So, soil is a layer of substance lying on top of rocks, consisting of a source material - an underlying mineral substrate - and an organic additive in which organisms and their metabolic products are mixed with small particles of modified source material. Soil structure and porosity largely determine the availability of nutrients to plants and soil animals.
Soil contains four important structural components:
Mineral base (50...60% of the total soil composition);
Organic matter (up to 10%);
Air (15...25%);
Water (25...35%).
Soil organic matter that is formed by the decomposition of dead organisms or their parts (such as fallen leaves) is called humus, which forms the top fertile layer of soil. The most important property of soil - fertility - depends on the thickness of the humus layer.
Each type of soil corresponds to a certain animal world and certain vegetation. The combination of soil organisms ensures the continuous circulation of substances in the soil, including the formation of humus.
The soil habitat has properties that bring it closer to the aquatic and land-air environments. As in the aquatic environment, temperature fluctuations in soils are small. The amplitudes of its values quickly decay with increasing depth. With excess moisture or carbon dioxide, the likelihood of oxygen deficiency increases. The similarity with the ground-air habitat is manifested through the presence of pores filled with air. Specific properties inherent only to soil include high density. Organisms and their metabolic products play a major role in soil formation. Soil is the most saturated part of the biosphere with living organisms.
In the soil environment, the limiting factors are usually a lack of heat and a lack or excess of moisture. Limiting factors can also be a lack of oxygen or an excess of carbon dioxide. The life of many soil organisms is closely related to their size. Some move freely in the soil, while others need to loosen it to move and search for food.
Test questions and assignments
1.What is the peculiarity of the ground-air environment as an ecological space?
2. What adaptations do organisms have for life on land?
3. Name the environmental factors that are most significant for
terrestrial organisms.
4. Describe the features of the soil habitat.
St. 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
O group Pyatochenko N. L.
Checked by: associate professor of the department
Vakhmistrova S. F.
Saint Petersburg
Introduction
Living conditions (conditions of existence) are a set of elements necessary for an organism, with which it is inextricably linked and without which it cannot exist.
Adaptations of an organism to its environment are called adaptation. The ability to adapt is one of the main properties of life in general, ensuring 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.
Individual properties or elements of the environment that affect organisms are called environmental factors. Environmental factors are varied. They have different natures and specific actions. Environmental factors are divided into two large groups: abiotic and biotic.
Abiotic factors is a set of conditions in the inorganic environment that affect living organisms directly or indirectly: 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 classified as a separate group along with biotic and abiotic factors, emphasizing the extreme effect of the anthropogenic factor.
Anthropogenic factors are all forms of activity of human society that lead to changes in nature as the habitat of 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)regularly constant, changing the strength of the impact due to the time of day, 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, showers, 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 environmental factors can have various effects on living organisms:
1) as irritants, causing adaptive changes in physiological and biochemical functions;
2) as limiters that make it impossible to exist in the data
conditions;
3) as modifiers that cause anatomical and morphological changes in organisms;
4) as signals indicating changes in other factors.
Despite the wide variety of environmental factors, a number of general patterns can be identified in the nature of their interaction with organisms and in the responses of living beings.
The intensity of the environmental factor that is most favorable for the life of the organism is optimal, and the one that gives the worst effect is pessimum, i.e. conditions under which the vital activity of an organism is maximally inhibited, but it can still exist. Thus, 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 it (i.e., the minimum and maximum) temperatures suitable for life is the stability limit. Between the optimum zone and the limit of stability, as it approaches the latter, the plant experiences increasing stress, i.e. we are talking about stress zones, or zones of oppression, within the range of resistance
Dependence of the action of an environmental factor on its intensity (according to V.A. Radkevich, 1977)
As you move up and down the scale, not only does stress increase, but ultimately, when the limits of the body’s resistance are reached, its death occurs. Similar experiments can be carried out to test the influence of other factors. The results will graphically correspond to a similar type of curve
Ground-air environment of life, its characteristics and forms of adaptation to it.
Life on land required adaptations that turned out to be possible only in highly organized living organisms. The ground-air environment is more difficult for life; it is characterized by a high oxygen content, low amount of water vapor, low density, etc. This greatly changed the conditions of breathing, water exchange and movement of living beings.
Low air density determines its low lifting force and insignificant support. Organisms of the air environment must have their own support system that supports the body: plants - various mechanical tissues, animals - a solid or hydrostatic skeleton. In addition, all inhabitants of the air are closely connected with the surface of the earth, which serves them for attachment and support.
Low air density provides low resistance to movement. Therefore, many land animals acquired the ability to fly. 75% of all terrestrial animals, mainly insects and birds, have adapted to active flight.
Thanks to the mobility of air and 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 - dispersal 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 relatively low pressure, due to low air density. Normally it is 760 mmHg. 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 respiration rate. Higher plants have approximately the same limits of advancement in the mountains. Somewhat more hardy are arthropods that can be found on glaciers above the vegetation line.
Gas composition of air. In addition to the physical properties of the air, 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 uniform 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 metabolism in terrestrial organisms compared to primary aquatic organisms. It was in a terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homeothermy arose. Oxygen, due to its constant high content in the air, is not a limiting factor for life in the terrestrial environment.
The carbon dioxide content can vary in certain areas of the surface layer of air within quite significant limits. Increased air saturation with CO? occurs in areas 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 inhibits the process of photosynthesis. In closed soil conditions, you can increase the rate of photosynthesis by increasing the concentration of carbon dioxide. This is used in the practice of greenhouse and greenhouse farming.
Air nitrogen is an inert gas for most inhabitants of the terrestrial environment, but certain 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 land-air environment of life. The entire evolution of terrestrial organisms was under the sign of adaptation to obtaining and preserving moisture. Humidity regimes on land are very diverse - from complete and constant saturation of the air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. There is also significant daily and seasonal variability in the content of water vapor in the atmosphere. The water supply of terrestrial organisms also depends on the precipitation regime, the presence of reservoirs, soil moisture reserves, the proximity of pound waters, etc.
This led to the development of adaptation in terrestrial organisms to various water supply regimes.
Temperature conditions. The next distinguishing feature air-ground environment there are significant temperature fluctuations. In most land areas, daily and annual temperature ranges are tens of degrees. Resistance to temperature changes in the environment among terrestrial inhabitants is very different, depending on the specific habitat in which their life takes place. However, in general, terrestrial organisms are much more eurythermic compared to aquatic organisms.
Living conditions in the ground-air environment are further complicated by the existence of weather changes. Weather - continuously changing conditions of the atmosphere at the surface, up to an altitude of approximately 20 km (the boundary of the troposphere). Weather variability is manifested in a constant variation in the combination of environmental factors such 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 cycle, 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 air with water vapor.
For most terrestrial organisms, especially small ones, the climate of the area is not so important as the conditions of their immediate habitat. Very often, local environmental elements (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 climate modifications that develop in the surface layer of air are called microclimate. In each zone the microclimate is very diverse. Microclimates of very small areas can be identified.
The light regime of the ground-air environment also has some peculiarities. The intensity and amount of light here are greatest and practically do not limit the life of green plants, as in water or soil. On land, extremely light-loving species may exist. For the vast majority of terrestrial animals with daytime and even nighttime activity, vision is one of the main methods of orientation. In terrestrial animals, vision is important for searching for prey; many species even have color vision. In this regard, victims develop such adaptive features as a defensive reaction, camouflage and warning coloration, mimicry, etc.
In aquatic inhabitants, such adaptations are much less developed. The appearance of brightly colored flowers of higher plants is also associated with the characteristics of the pollinator apparatus and, ultimately, with the light regime of the environment.
The terrain and soil properties are also the living conditions for terrestrial organisms and, first of all, plants. Properties of the earth's surface that have environmental impact on its inhabitants, unite " edaphic factors environment" (from the Greek "edaphos" - "soil").
In relation to different properties soils, a number of ecological groups of plants can be distinguished. Thus, according to the reaction to soil acidity, they are distinguished:
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) basophilaceae grow at a pH of more than 7.0 (Echinops, wood anemone);
4) indifferent ones can grow on soils with different meaning pH (lily of the valley).
Plants also differ in relation to soil moisture. Certain species are confined to different substrates, for example, petrophytes grow on rocky soils, pasmophytes populate loose sand.
The terrain and the nature of the soil influence the specific movement of animals: for example, ungulates, ostriches, bustards living in open spaces, hard ground, to enhance repulsion when running. In lizards that live in shifting sands, the toes are fringed with a fringe of horny scales that increase support. For terrestrial inhabitants that dig holes, dense soil is unfavorable. The nature of the soil in certain cases influences the distribution of terrestrial animals that dig holes or burrow into the soil, or lay eggs in the soil, etc.
About the composition of air.
The gas composition of the air we breathe looks like this: 78% is nitrogen, 21% is oxygen and 1% is other gases. But in the atmosphere of large industrial cities this ratio is often violated. A significant proportion are harmful impurities caused by emissions from enterprises and vehicles. Motor transport introduces 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. The composition of atmospheric air changes little with altitude. However, starting from an altitude 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 altitude; 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 (while at 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; 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 changes in 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 not constant. All gases that make up air are colorless and odorless. The weight of air changes 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 humid 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 | % 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 under pressure change.
For example: oxygen under pressure of more than 2 atmospheres has a toxic effect on the body.
Nitrogen under pressure above 5 atmospheres has a narcotic effect (nitrogen intoxication). A rapid rise from the depths 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 makes up 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 most appropriate term is “spurt” (throw), used in high-speed sports. Perhaps the starting pistol was fired by two articles published in the early 1970s. They discussed the possible destruction of stratospheric ozone by nitrogen oxides - NO and NO2. The first belonged to the future Nobel laureate, and then to an employee of Stockholm University P. Crutzen, who considered the likely source of nitrogen oxides in the stratosphere to be decaying under the influence of sunlight nitrous oxide N2O natural origin. The author of the second article, 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, during emissions of combustion products from jet engines of high-altitude aircraft.
Of course, the above hypotheses did not arise out of nowhere. The ratio of at least the main components in atmospheric air - molecules of nitrogen, oxygen, water vapor, etc. - was known much earlier. Already in the second half of the 19th century. In Europe, measurements of ozone concentrations 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 50s, measurements using weather rockets showed that there was much less ozone in the stratosphere than there 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 70s, knowledge in the field of atmospheric chemistry was mainly obtained through the efforts of individual scientists, whose research was not united by any socially significant concept and was most often of a purely academic nature. Johnston's work is a different matter: according to his calculations, 500 planes, flying 7 hours a day, could reduce the amount of stratospheric ozone by no less than 10%! And if these assessments were fair, then the problem would immediately become socio-economic, since in this case all programs for the development of supersonic transport aviation and associated infrastructure would have to undergo significant adjustments, 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 operational verification.
Let us recall that the essence of the above hypothesis was that nitrogen 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 lost forever. In this case, such a pair of reactions, constituting the nitrogen catalytic cycle of ozone destruction, is repeated until any chemical or physical processes will not lead to the removal of nitrogen oxides from the atmosphere. For example, NO2 is oxidized to nitric acid HNO3, which is highly soluble in water, and is therefore removed from the atmosphere by clouds and precipitation. The nitrogen catalytic cycle is very effective: one molecule of NO during its stay in the atmosphere manages to destroy tens of thousands of ozone molecules.
But, as you know, trouble does not come alone. Soon, experts from US universities - Michigan (R. Stolarski and R. Cicerone) and Harvard (S. Wofsey and M. McElroy) - discovered that ozone may have an even more merciless enemy - chlorine compounds. The chlorine catalytic cycle of ozone destruction (reactions Cl + O3 ® ClO + O2 and ClO + O ® Cl + O2), according to their estimates, was several times more efficient than the nitrogen one. The only cause 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 the 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 established that the source of chlorine in the stratosphere are chlorofluorocarbon compounds (CFCs), widely used in refrigeration units, aerosol packaging, etc. Being non-flammable, non-toxic and chemically passive, these substances are slowly transported by rising air currents from the earth's surface into the stratosphere, where their molecules are destroyed by sunlight, resulting in the release of free chlorine atoms. Industrial production of CFCs, which began in the 30s, and their emissions into the atmosphere have 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 validity of the hypotheses put forward, it was necessary to perform many tasks.
Firstly, expand laboratory studies, during which it would be possible to determine or clarify the rate of photo flow chemical reactions between different components of atmospheric air. It must be said that the very meager data on these speeds that existed at that time also had a fair amount of error (up to several hundred percent). In addition, the conditions under which the measurements were made, as a rule, had little correspondence with the realities of the atmosphere, which seriously aggravated the error, since the intensity of most reactions depended on temperature and sometimes on pressure or density of atmospheric air.
Secondly, intensively study the radiation-optical properties of a number of small atmospheric gases in laboratory conditions. Molecules of a significant number of components of atmospheric air are destroyed by ultraviolet radiation from the Sun (in photolysis reactions), among them 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 as necessary and important for the correct reproduction of atmospheric chemical processes as the rates of reactions between different molecules.
Thirdly, it was necessary to create mathematical models capable of describing as fully as possible the mutual chemical transformations of atmospheric air components. As already mentioned, the productivity of ozone destruction in catalytic cycles is determined by how long the catalyst (NO, Cl or some other) remains in the atmosphere. It is clear that such a catalyst, generally speaking, could react with any of the dozens of components of atmospheric air, quickly collapsing 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 likely to identify other mechanisms 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 the atmospheric air, and also allow one to calculate the concentrations of gases that cannot be measured.
And finally, it was necessary to organize a wide network for measuring the content of various gases in the air, including compounds of nitrogen, chlorine, etc., using for this purpose ground stations, launches of weather balloons and weather rockets, and aircraft flights. Of course, creating a database was the most expensive task, which could not be solved in short time. However, only measurements could provide a starting point for theoretical research, being at the same time a touchstone for the truth of the hypotheses expressed.
Since the early 70s, special, constantly updated collections have been published at least once every three years, containing information about all significant atmospheric reactions, including photolysis reactions. Moreover, the error in determining the parameters of reactions between gas components of air today is, as a rule, 10-20%.
The second half of this decade saw rapid development of models describing chemical transformations in the atmosphere. The largest number of them were created in the USA, but they appeared in Europe and the USSR. At first these were box (zero-dimensional) models, and then one-dimensional models. The first 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 part of it 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, and for assessing the sensitivity of the gas composition of the atmosphere to inaccuracies in determining reaction rates. With their help, researchers could, by setting atmospheric parameters in the box (in particular, temperature and air density) corresponding to the altitude of aviation flights, and estimate in a rough approximation how the concentrations of atmospheric impurities would change as a result of emissions of combustion products from 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 to 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 specified here rather roughly, 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 are largely based on the rough work done in those years using one-dimensional and box models. It made it possible to determine the mechanisms of formation of the gas composition of the atmosphere, assess the intensity of chemical sources and sinks of individual gases. An important feature of this stage in the development of atmospheric chemistry is that the new ideas that emerged were tested on models and widely discussed among specialists. The results obtained were often compared with estimates from other scientific groups, since field measurements were clearly insufficient, and their accuracy was very low. In addition, to confirm the correctness of the modeling of certain chemical interactions, it was necessary to carry out complex measurements, when the concentrations of all participating reagents were simultaneously determined, 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 went 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 modeling studies and only then was discovered in the atmosphere. Even comparing the available measurements with model estimates was difficult, since the one-dimensional model could not take into account horizontal air movements, which is why the atmosphere was assumed to be horizontally homogeneous, and the obtained model results corresponded to some average global state. 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 field observation largely depend on the location and time of the measurements and, of course, do not correspond exactly to the global average value.
To eliminate this gap in modeling, in the 80s, researchers created two-dimensional models in which, along with vertical transport, air transport along the meridian was also taken into account (along the circle of latitude the atmosphere was still considered homogeneous). The creation of such models at first was fraught with significant difficulties.
Firstly, the number of external model parameters sharply increased: at each grid node it was necessary to set the rates of vertical and interlatitudinal transport, temperature and air density, etc. Many parameters (primarily the above-mentioned speeds) were not reliably determined in experiments and were therefore selected for qualitative reasons.
Secondly, The state of computer technology at that time significantly hampered the full development of two-dimensional models. Unlike economical one-dimensional and especially boxed models, two-dimensional models required significantly more memory and computer time. And as a result, their creators were forced to significantly simplify the schemes for accounting for chemical transformations in the atmosphere. However, the complex atmospheric research, 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 ascent into the stratosphere appears to have negative effects on the ozonosphere. The opinion of most experts about the role of CFCs was almost unanimous: the hypothesis of Rowland and Molina 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 they persist for a long time, chlorofluorocarbons can reach any, even the most remote point in the atmosphere, and, therefore, this is a threat on a global scale. The time has come for agreed political decisions.
In 1985, with the participation of 44 countries, a convention for the protection of the ozone layer was developed and adopted in Vienna, which stimulated its comprehensive study. However, the question of what to do with CFCs still remained open. It was impossible to let the matter take its course according to the principle “it will resolve itself,” but it is also impossible to ban the production of these substances overnight without enormous damage to the economy. It would seem that there is a simple solution: it is necessary to replace CFCs with other substances that can perform the same functions (for example, in refrigeration units) and at the same time are harmless or at least less dangerous for ozone. But implementing simple solutions is often very difficult. Not only did the creation of such substances and the establishment of their production require enormous capital investments and time, criteria were needed for assessing the impact of any of them on the atmosphere and climate.
Theorists are back in the spotlight. D. Webbles from the Livermore National Laboratory proposed using the ozone depletion potential for this purpose, which showed how much stronger (or weaker) a molecule of a substitute substance affects atmospheric ozone than a molecule of CFCl3 (Freon-11). At that time, it was also well known that the temperature of the surface layer of air significantly depends on the concentration of certain gas impurities (they were called greenhouse gases), primarily carbon dioxide CO2, water vapor H2O, ozone, etc. CFCs and many their potential substitutes. Measurements have shown that during the industrial revolution, the average annual global temperature of the surface layer of air has increased and continues to increase, 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 a substance, its global warming potential was also considered. This index indicated how much stronger or weaker the studied compound affects air temperature than the same amount of carbon dioxide. Calculations showed that CFCs and alternative substances had very high global warming potentials, but because their atmospheric concentrations 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 ozone depletion potentials and global warming potentials of chlorofluorocarbons and their possible substitutes formed the basis for international decisions to reduce and subsequently ban the production and use of many CFCs (the 1987 Montreal Protocol and its later amendments). Perhaps the experts gathered in Montreal would not have been so unanimous (after all, the articles of the Protocol were based on the “fabrications” of theorists not confirmed by natural experiments), but another interested “person” spoke in favor of signing this document - the atmosphere itself.
The announcement that English scientists discovered an “ozone hole” over Antarctica at the end of 1985 became, not without the participation of journalists, the sensation of the year, and the world community’s reaction to this announcement can most easily be described in one short word - shock. It is one thing when the threat of destruction of the ozone layer exists only in the distant future, but another when we are all faced with a fait accompli. Neither ordinary people, nor politicians, nor theorists were ready for this.
It quickly became clear that none of the existing models could reproduce such a significant reduction in ozone levels. This means that some important natural phenomena were either not taken into account or underestimated. Soon, field studies carried out within the framework 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 peculiarities of the transport of atmospheric air in the Antarctic stratosphere (its almost complete isolation in winter from the rest of the atmosphere), as well as at that time little studied heterogeneous reactions (reactions on the surface of atmospheric aerosols - dust particles, soot, ice floes, water droplets, etc.). Only taking into account the above-mentioned factors made it possible to achieve satisfactory agreement between model results and observational data. And the lessons taught by the Antarctic “ozone hole” have seriously affected further development atmospheric chemistry.
Firstly, a sharp impetus was given to a detailed study of heterogeneous processes occurring according to laws different from those that determine gas-phase processes. Secondly, there was a clear understanding that in a complex system such as 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, radiation heating and cooling, which form the temperature field of stratospheric air, depend on the concentration and distribution in space greenhouse gases, and therefore from atmospheric dynamic processes. Finally, non-uniform radiation heating different belts globe and parts of the atmosphere generates atmospheric air movements and controls their intensity. Thus, failure to take into account any feedback in models can be fraught with large errors in the results obtained (although, let us note in passing, excessively complicating the model without an urgent need is 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 80s, then the use of three-dimensional models of general atmospheric circulation to describe the distribution of atmospheric impurities became possible thanks to the computer boom only in the 90s. The first such general circulation models were used to describe the spatial distribution of chemically passive substances - tracers. Later due to insufficient RAM In computers, chemical processes were specified by only one parameter - the residence time of the impurity in the atmosphere, and only relatively recently did blocks of chemical transformations become full-fledged parts of three-dimensional models. Although there are still difficulties in representing atmospheric chemical processes in detail in 3D models, 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, the widespread use of modern models does not at all call into question 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, and assess the impact of certain phenomena on the final result (and therefore the advisability of taking them into account in the model) . And here, simpler models serve as an ideal testing ground; they make it possible to obtain preliminary estimates that are later used in three-dimensional models, to study new natural phenomena before their inclusion in more complex ones, etc.
Rapid scientific and technological progress has given rise to several more 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, there was a need to improve methods for their processing. This includes data filtering (separation of signal and measurement errors), and restoration of vertical profiles of impurity concentrations based on 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 aircraft expeditions that are planned to solve various problems, for example, in the tropical Pacific Ocean, the North Atlantic and even in the summer stratosphere of the Arctic.
An important part of modern research is the assimilation (assimilation) of these databases into models of varying complexity. In this case, the parameters are selected based on the condition of closest proximity between the measured and model values of impurity content at points (regions). In this way, the quality of the models is checked, as well as the extrapolation of measured values beyond the regions and periods of measurements.
Estimation of concentrations of short-lived atmospheric pollutants. 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 greatest 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 relationships between the 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 radical concentrations based on them, while improving models and expanding information about the gas composition of the atmosphere.
Reconstruction of the gas composition of the atmosphere in the pre-industrial period and earlier eras of the Earth. Thanks to measurements in Antarctic and Greenland ice cores, the age of which 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, have become known. A model reconstruction of the state of the atmosphere in those eras and its comparison with the present 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 sources of the most important air components. Systematic measurements of the content of gases in the surface air, such as methane, carbon monoxide, and nitrogen oxides, became the basis for solving the inverse problem: estimating the amount of emissions of gases from ground sources into the atmosphere based on their known concentrations. Unfortunately, only an inventory of the culprits of the universal commotion - CFCs - is a relatively simple task, since almost all of these substances do not have natural sources and their total amount entering the atmosphere is limited by the volume of their production. The remaining gases have different 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 other organic compounds. Direct measurements of emissions of these gases are difficult, but techniques have been developed to provide estimates of global sources of polluting gases, the uncertainty of which has been significantly reduced in recent years, although it remains large.
Forecasting changes in the composition of the Earth's atmosphere and climate Considering trends - trends in the content of atmospheric gases, assessments 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, possible changes in gas composition, temperature and atmospheric circulation are predicted using models. In this way, it is possible to detect unfavorable trends in the state of the atmosphere in advance and you can 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 clearly 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, having replaced ordinary glass with quartz glass in a laboratory model of a greenhouse and without detecting 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, but the role of glass in this In this case, it 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 ability to transmit solar radiation, but retain terrestrial radiation, promoting the accumulation of heat by the earth. The earth's atmosphere transmits short-wave solar radiation relatively well, which is almost completely absorbed by the earth's surface. Heating due to the absorption of solar radiation, the earth's surface becomes a source of terrestrial, mainly long-wave, radiation, part of which goes into outer space.
Effect of increasing CO2 concentration
Scientists and researchers continue to argue about the composition of so-called greenhouse gases. The greatest interest in this regard is the effect of increasing concentrations of carbon dioxide (CO2) on the greenhouse effect of the atmosphere. It is suggested that the well-known scheme: “an increase in carbon dioxide concentration enhances the greenhouse effect, which leads to 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, there are reservations that the concentration of water vapor in the atmosphere is determined only by the parameters of the climate system, today no longer stands up to criticism, since the anthropogenic impact on the global water cycle has been convincingly proven.
As scientific hypotheses, we point out the following consequences of the upcoming 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 o C. At the same time, warming is expected to result in drier summers 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 Antarctic ice sheet, its destruction is not inevitable, since melting requires more high temperatures. In any case, the process of melting Antarctic ice will take a very long time.
Thirdly, Atmospheric CO2 concentrations can have very beneficial effects on crop yields. The results of the experiments suggest that, under conditions of a progressive increase in 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 of fruits and the number of seeds will increase, the ripening of grains will accelerate, and their yield will increase.
Fourthly, At high latitudes, natural forests, especially boreal forests, can be very sensitive to temperature changes. Warming could lead to a sharp reduction in the area of boreal forests, as well as to a shift of their border to the north; forests of the tropics and subtropics will probably be more sensitive to changes in precipitation rather than temperature.
Light energy from the sun penetrates the atmosphere, is absorbed by the surface of the earth and heats it. In this case, light energy turns into heat, 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 itself and heats the atmosphere. This means that the more carbon dioxide in the atmosphere, the more strongly it affects 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 could lead to global warming of the planet.
Conclusion
Changing your attitude towards nature does not mean that you should abandon technological progress. Stopping it will not solve the problem, but can only delay its solution. It is necessary to persistently and patiently strive to reduce emissions through the introduction of new environmental technologies for saving raw materials, energy consumption and increasing the number of plantings and carrying out educational activities regarding the ecological worldview of the population.
For example, in the USA, one of the enterprises for the production of synthetic rubber is located next to residential areas, and this does not cause protest from residents, because environmentally friendly technological schemes operate, which in the past, with old technologies, were not very clean.
This means that we need a strict selection of technologies that meet the most stringent criteria; modern promising technologies will allow us to achieve a high level of environmentally friendly production in all sectors of industry and transport, as well as increase the number of green spaces planted 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 classical, respectable sciences. But there are still areas where theoretical research remains a priority: for example, only model experiments are able to predict changes in the composition of the atmosphere or assess the effectiveness of restrictive measures implemented under the Montreal Protocol. Starting from the solution of an important, but private problem, today atmospheric chemistry, in collaboration with related disciplines, covers the entire complex range of problems in the study and protection of the environment. Perhaps we can say that the first years of the development of atmospheric chemistry passed under the motto: “Don’t be late!” The starting rush is over, the run continues.
The land-air environment is characterized by a huge variety of living conditions, ecological niches and organisms inhabiting them. It should be noted that organisms play a primary role in shaping the conditions of the land-air environment of life, and above all, the gas composition of the atmosphere. Almost all the oxygen in the earth's atmosphere is of biogenic origin.
The main features of the ground-air environment are the large amplitude of changes in environmental factors, the heterogeneity of the environment, the action of gravitational forces, and low air density. A complex of physical-geographical and climatic factors characteristic of a certain natural zone leads to the evolutionary formation of morphophysiological adaptations of organisms to life in these conditions and the diversity of life forms.
Atmospheric air is characterized by low and variable humidity. This circumstance largely limited (limited) the possibilities of mastering the ground-air environment, and also directed the evolution of water-salt metabolism and the structure of the respiratory organs.
Air composition. One of the main abiotic factors of the terrestrial (air) habitat is the composition of the air, a natural mixture of gases that developed during the evolution of the Earth. The composition of air in the modern atmosphere is in a state of dynamic equilibrium, depending on the vital activity of living organisms and geochemical phenomena on a global scale.
Air, devoid of moisture and suspended particles, has almost the same composition at sea level in all areas of the globe, as well as throughout the day and at different periods of the year. However, in different eras of the planet’s existence, the composition of the air was different. It is believed that the content of carbon dioxide and oxygen changed the most (Fig. 3.7). The role of oxygen and carbon dioxide is shown in detail in Sect. 2.2.
Nitrogen, present in the atmospheric air in the greatest quantity, in a gaseous state, is neutral for the vast majority of organisms, especially animals. Only for a number of microorganisms (nodule bacteria, azotobacter, blue-green algae, etc.) does air nitrogen serve as a vital activity factor. These microorganisms assimilate molecular nitrogen, and after dying and mineralization, supply higher plants with accessible forms of this chemical element.
The presence in the air of other gaseous substances or aerosols (solid or liquid particles suspended in the air) in any noticeable quantities changes the usual environmental conditions and affects living organisms.
2.2. Adaptations of terrestrial organisms to the environment
Aeroplankton (anemochory).
Plants: wind pollination, stem structure, shapes of leaf blades, types of inflorescences, color, size.
Formation of flag forms of trees. Root system.
Animals: breathing, body shape, integument, behavioral reactions.
Soil as a medium
Soil is the result of the activity of living organisms. The organisms that populated the ground-air environment led to the emergence of soil as a unique habitat. The soil is complex system, including the solid phase (mineral particles), the liquid phase (soil moisture) and the gaseous phase. The relationship between these three phases determines the characteristics of the soil as a living environment.
An important feature of the soil is also the presence of a certain amount of organic matter. It is formed as a result of the death of organisms and is part of their excreta (secretions).
The conditions of the soil habitat determine such properties of the soil as its aeration (that is, air saturation), humidity (presence of moisture), heat capacity and thermal regime (daily, seasonal, annual temperature variations). The thermal regime, compared to the ground-air environment, is more conservative, especially at great depths. In general, the soil has fairly stable living conditions.
Vertical differences are also characteristic of other soil properties, for example, light penetration naturally depends on depth.
Many authors note the intermediate position of the soil environment of life between the aquatic and land-air environments. Soil can harbor organisms that have both aquatic and airborne respiration. The vertical gradient of light penetration in soil is even more pronounced than in water. Microorganisms are found throughout the entire thickness of the soil, and plants (primarily root systems) are associated with external horizons.
Soil organisms are characterized by specific organs and types of movement (burrowing limbs in mammals; the ability to change body thickness; the presence of specialized head capsules in some species); body shape (round, volcanic, worm-shaped); durable and flexible covers; reduction of eyes and disappearance of pigments. Among soil inhabitants, saprophagy is widely developed - eating the corpses of other animals, rotting remains, etc.
Soil composition. Soil is a layer of substances lying on the surface of the earth's crust. It is a product of the physical, chemical and biological transformation of rocks (Fig. 3.8) and is a three-phase medium, including solid, liquid and gaseous components in the following ratios (in%):
mineral base is usually 50-60% of the total composition
organic matter......................... up to 10
water................................................. ..... 25-35
air................................................. .15-25
In this case, soil is considered among other abiotic factors, although in fact it is the most important link connecting abiotic and biotic factors of the environment.
Mineral inorganic composition p.o. Rock under the influence of chemical and physical factors natural environment is gradually destroyed. The resulting parts vary in size - from boulders and stones to large grains of sand and tiny particles of clay. The mechanical and chemical properties of soil mainly depend on fine soil (particles less than 2 mm), which is usually divided depending on size 8 (in microns) into the following systems:
sand........................................ 5 = 60-2000
silt (sometimes called "dust") 5 = 2-60
clay.. ".............................................. 8 less than 2
The structure of the soil is determined by the relative content of sand, silt, and clay in it and is usually illustrated by a diagram - the “soil structure triangle” (Fig. 3.9).
The importance of soil structure becomes clear when comparing the properties of pure sand and clay. An “ideal” soil is considered to be one containing equal amounts of clay and sand combined with particles of intermediate sizes. In this case, a porous, grainy structure is formed. The corresponding soils are called loams. They have the advantages of the two extreme types of soil without their disadvantages. Most of the mineral components are represented in the soil by crystalline structures. Sand and silt are composed primarily of an inert mineral, quartz (SiO2), called silica.
Clay minerals are mostly found in the form of tiny flat crystals, often hexagonal in shape, consisting of layers of aluminum hydroxide or alumina (Al 2 O 3) and layers of silicates (compounds of silicate ions SiO^" with cations, for example, aluminum Al 3+ or iron Fe 3+, Fe 2+). The specific surface of the crystals is very large and amounts to 5-800 m 2 per 1 g of clay, which helps retain water and nutrients in the soil.
In general, it is believed that over 50% mineral composition soil consists of silica (SiO 2), 1-25% - alumina (A1 2 O 3), 1-10% - iron oxides (Fe 3 O 4), 0.1-5% - oxides of magnesium, potassium, phosphorus, calcium (MgO, K 2 O, P 2 O 3, CaO). IN agriculture soils are divided into heavy (clay) and light (sand), which reflects the amount of effort required to cultivate the soil with agricultural implements. A number of additional characteristics of the mineral composition of the soil will be presented in Section. 7.2.4.
The total amount of water that can be retained by the soil is made up of gravitational, physically bound, capillary, chemically bound and vapor water (Figure 3.10).
Gravity water can freely seep down through the soil, reaching the level groundwater, which leads to the leaching of various nutrients.
Physically bound (hygroscopic) water adsorbed on soil particles in the form of a thin, tightly bound film. Its amount depends on the content of solid particles. In clay soils there is much more such water (about 15% of the soil weight) than in sandy soils (about 0.5%). Hygroscopic water is the least accessible to plants. Capillary water held around soil particles by surface tension forces. In the presence of narrow pores or channels, capillary water can rise upward from the groundwater level, playing a central role in the regular supply of moisture to plants. Clays retain more capillary water than sands.
Chemically bound water and vaporous practically inaccessible to the plant root system.
Compared to the composition of atmospheric air, due to the respiration of organisms with depth, the oxygen content decreases (up to 10%) and the concentration of carbon dioxide increases (reaching 19%). Over the course of a year and a day, the composition of soil air changes greatly. Nevertheless, soil air is constantly renewed and replenished by atmospheric air.
Waterlogging causes air to be displaced by water and conditions become anaerobic. Since microorganisms and plant roots continue to release CO 2, which forms H 2 CO 3 with water, the renewal of humus slows down and humic acids accumulate. All this increases the acidity of the soil, which, along with the depletion of oxygen reserves, adversely affects soil microorganisms. Prolonged anaerobic conditions lead to plant death.
The gray tint characteristic of wetland soils is given by the reduced form of iron (Fe 2+), while the oxidized form (Fe 3+) colors the soil yellow, red and brown.
Soil biota.
Based on the degree of connection with the soil as a habitat, animals are grouped into ecological groups:
Geobionts- inhabitants of the soil, which are divided into:
rhizobionts – animals associated with roots;
saprobionts – inhabitants of decaying organic matter;
coprobionts – invertebrates – inhabitants of manure;
bothrobionts – burrow inhabitants;
planophiles are animals that move frequently.
Geophiles- animals, part of the development cycle necessarily takes place in the soil. (locusts, mosquitoes, a number of beetles, hymenoptera)
Geoxenes– Animals visiting soil for temporary shelter, shelter.
Animals that live in soil use it in different ways. Small ones - protozoa, rotifers, gastrociliformes - live in a film of water that envelops soil particles. This geohydrobionts. They are small, flattened or elongated. They breathe oxygen dissolved in water; with a lack of moisture, they are characterized by torpor, encystment, and the formation of cocoons. The remaining inhabitants breathe oxygen from the air - this is geoatmobionts.
Soil animals are divided into groups according to size:
nannofauna – animals up to 0.2 mm in size; microfauna - animals 0.1-1.0 mm in size, soil microorganisms, bacteria, fungi, protozoa (micro-reservoirs)
mesofauna - larger than 1.0 mm; ; nematodes, small insect larvae, mites, springtails.
Macrofauna – from 2 to 20 mm insect larvae, centipedes, enchytraeids, earthworms.
megafauna – vertebrates: shrews.
Animals burrows.
The most typical inhabitants of the soil are: protozoa, nematodes, earthworms, enchytraeids, naked slugs and other gastropods, mites and spiders, millipedes (bipopods and labiopods), insects - adults and their larvae (orders springtails, two-tailed, bristletails, dipterans, coleopterans , Hymenoptera, etc.). Pedobionts have developed various adaptations to living in the soil, both externally and internally.
Movement. Geohydrobionts have the same adaptations for movement as aquatic inhabitants. Geoatmobionts move along natural wells and make passages themselves. The movement of small animals in boreholes does not differ from movement on the surface of the substrate. The disadvantage of the borewell lifestyle is their high sensitivity to drying out of the substrate and dependence on the physical properties of the soil. In dense and rocky soils their numbers are small. This method of movement is typical for small arthropods. The passages are made by animals either by pushing apart soil particles (worms, dipteran larvae) or by grinding the soil (typical of the larvae of many insect species). Animals of the second group often have devices for scraping soil.
Morphophysiological adaptations to living in soil are: loss of pigment and vision in deep-soil inhabitants; absence of epicuticle or its presence in certain areas of the body; for many (earthworms, enchytraeids) an uneconomical system for removing metabolic products from the body; various options for external-internal fertilization in a number of inhabitants; for worms - breathing through the entire surface of the body.
Ecological adaptations are manifested in the selection of the most suitable living conditions. The choice of habitats is carried out through vertical migrations along the soil profile, changing habitats.
General characteristics. In the course of evolution, the land-air environment was mastered much later than the aquatic environment. Life on land required adaptations that became possible only with a relatively high level of organization in 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, and high oxygen content. Typically, animals in this environment move on the soil (hard substrate) and plants take root in it.
In the ground-air environment, the operating environmental factors have a number of characteristic features: higher light intensity compared to other environments, significant temperature fluctuations, changes in humidity depending on the geographical location, season and time of day (Table 5.3).
Table 5.3
Habitat conditions for air and water organisms
(according to D.F. Mordukhai-Boltovsky, 1974)
|
Terms habitat |
The importance of conditions for organisms |
|
|
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 |
Almost none |
Large (can reach 1000 atmospheres) |
|
Temperature |
Significant (varies within very wide limits (from -80 to +100 °C and more) |
Less than the value for the inhabitants of the air (varies much less, usually from -2 to +40°C) |
|
Oxygen |
Non-essential (mostly in excess) |
Essential (often in short supply) |
|
Weighted substances |
Unimportant; not used for food (mainly minerals) |
Important (food source, especially organic matter) |
|
Dissolved substances in the environment |
To some extent (only relevant in soil solutions) |
Important (certain quantities required) |
The impact of the above factors is inextricably linked with the movement of air masses - wind. In the process of evolution, living organisms of the land-air environment have developed characteristic anatomical, morphological, physiological, behavioral and other adaptations. For example, organs have appeared that provide direct absorption of atmospheric oxygen during respiration (the lungs and trachea of animals, the stomata of plants). Skeletal formations have received strong development (animal skeleton, mechanical and supporting tissues of plants), which support the body in conditions of low environmental density. Adaptations have been developed to protect against unfavorable factors, such as the periodicity and rhythm of life cycles, the complex structure of the integument, mechanisms of thermoregulation, etc. A close connection with the soil has formed (animal limbs, plant roots), the mobility of animals in search of food has developed, and air currents have appeared. seeds, fruits and pollen of plants, flying animals.
Let us consider the features of the impact of basic environmental factors on plants and animals in the ground-air environment of life.
Low air density determines its low lifting force and insignificant controversy. All inhabitants of the air 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 moving along the surface of the earth, but it makes it difficult to move vertically. For most organisms, staying in the air is associated only with settling or searching for prey.
The low lifting force of air determines the maximum 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 mass of a modern whale) could not live on land, as they would be crushed by their own weight. Giant Mesozoic dinosaurs led a semi-aquatic lifestyle. Another example: tall, erect redwood plants (Sequoja sempervirens), reaching 100 m, have 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 little resistance to movement. The ecological benefits of this property of the air environment were used by many land animals during evolution, acquiring the ability to fly. 75% of all species of land animals 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 efforts. Some animals can glide using air currents.
Due to the mobility of air, which exists in the lower layers of the atmosphere, vertical and horizontal movement of air masses, passive flight of certain types of organisms is possible, developed anemochory - dispersal by air currents. Organisms passively transported by air currents are collectively called aeroplankton, by analogy with planktonic inhabitants of the aquatic environment. For passive flight along N.M. Chernova, A.M. Bylova (1988) organisms have special adaptations - small body size, an increase in its area due to outgrowths, strong dismemberment, a large relative surface of the wings, the use of a web, etc.
Anemochorous seeds and fruits of plants also have very small sizes (for example, fireweed seeds) or various wing-shaped (maple Acer pseudoplatanum) and parachute-shaped (dandelion Taraxacum officinale) appendages
Wind-pollinated plants have a number of adaptations that improve the aerodynamic properties of pollen. Their floral integument is usually reduced and the anthers are not protected from the wind in any way.
In the dispersal of plants, animals and microorganisms, the main role is played by vertical conventional air flows and weak winds. Storms and hurricanes also have a significant environmental impact on terrestrial organisms. Quite often, strong winds, especially blowing in one direction, bend tree branches and trunks to the leeward side and cause the formation of flag-shaped crowns.
In areas where strong winds constantly blow, the species composition of small flying animals is usually poor, since they are not able to resist powerful air currents. Thus, a honey bee flies only when the wind force is up to 7 - 8 m/s, and aphids fly only when the wind is very weak, not exceeding 2.2 m/s. Animals in these areas develop dense integuments that protect the body from cooling and loss of moisture. On oceanic islands with constant strong winds, birds and especially insects predominate, having lost the ability to fly, they lack wings, since those who are able to rise into the air are blown out to sea by the wind and die.
The wind causes a change in the intensity of transpiration in plants and is especially pronounced during dry winds, which dry out the air and can lead to the death of plants. The main ecological role of horizontal air movements (winds) is indirect and consists in enhancing or weakening the impact on terrestrial organisms of such important environmental factors as temperature and humidity. Winds increase the release of moisture and heat from animals and plants.
When there is wind, heat is easier to bear and frost is more difficult, and organisms become desiccated and cooled faster.
Terrestrial organisms exist in conditions of relatively low pressure, which is caused by low air density. In general, terrestrial organisms are more stenobatic than aquatic ones, because normal pressure fluctuations in their environment amount to fractions of the atmosphere, and for those that rise to high altitudes, for example, birds, do not exceed 1/3 of normal.
Gas composition of air, as already discussed earlier, in the ground layer of the atmosphere it is quite homogeneous (oxygen - 20.9%, nitrogen - 78.1%, m.g. gases - 1%, carbon dioxide - 0.03% by volume) due to its high diffusion ability 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 metabolism in terrestrial organisms, and animal homeothermy arose on the basis of the high efficiency of oxidative processes. Only in places, under specific conditions, is a temporary oxygen deficiency created, for example, in decomposing plant debris, grain reserves, flour, etc.
In certain areas of the surface air layer, the carbon dioxide content can vary within fairly significant limits. Thus, in the absence of wind in large industrial centers and cities, its concentration can increase tenfold.
There are regular daily changes in the content of carbon dioxide in the ground layers, determined by the rhythm of plant photosynthesis (Fig. 5.17).
Rice. 5.17. Daily changes in the vertical profile
CO 2 concentrations 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 during the day, at the level of tree crowns, carbon dioxide is spent on photosynthesis, and in the absence of wind, a zone poor in CO 2 (305 ppm) is formed here, into which CO comes from the atmosphere and soil (soil respiration). At night, a stable air stratification is established with an increased concentration of CO 2 in the soil layer. Seasonal fluctuations in carbon dioxide are associated with changes in the respiration rate of living organisms, mostly soil microorganisms.
In high concentrations, carbon dioxide is toxic, but such concentrations are rare in nature. Low CO 2 content inhibits the process of photosynthesis. To increase the rate of photosynthesis in the practice of greenhouses and hothouses (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 toxic to plants in concentrations from one fifty-thousandth to one millionth of the volume of air. Lichens die when there are traces of sulfur dioxide in the environment. Therefore, plants that are particularly sensitive to SO 2 are often used as indicators of its content in the air. Common spruce and pine, maple, linden, and 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 quantity, but also in composition. Short-wave radiation is absorbed by the ozone shield and oxygen in the air. Infrared rays are absorbed in the atmosphere by water vapor and carbon dioxide. The rest reaches the Earth's surface in the form of direct or diffuse radiation.
The totality of direct and diffuse solar radiation ranges from 7 to 7„ of the total radiation, whereas in cloudy days scattered radiation is 100%. At high latitudes, diffuse radiation predominates, while in the tropics, direct radiation predominates. Scattered radiation contains up to 80% of yellow-red rays at noon, direct radiation - from 30 to 40%. On clear sunny days, 45% of solar radiation reaching the Earth's surface consists of visible light(380 - 720 nm) and 45% from infrared radiation. Only 10% comes from ultraviolet radiation. The radiation regime is significantly influenced by atmospheric dust. Due to its pollution, in some cities the illumination may be 15% or less of 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. 5.18).
Rice. 5.18. Distribution of solar radiation depending on
height of the Sun above the horizon (A 1 - high, A 2 - low)
Depending on the season and time of day, the light intensity also fluctuates. In certain regions 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. Short-wave rays are known to be absorbed and scattered by the atmosphere more than long-wave rays. In mountainous areas there is therefore always more short-wave solar radiation.
Trees, shrubs, and plant crops shade the area and create a special microclimate, weakening radiation (Fig. 5.19).
Rice. 5.19. Radiation attenuation:
A - in a rare pine forest; B - in corn crops Of the incoming photosynthetically active radiation, 6-12% is reflected (R) from the surface of the planting
Thus, not only the intensity of radiation varies in different habitats, but also its spectral composition, duration of illumination of plants, spatial and temporal distribution of light of different intensities, etc. Accordingly, the adaptations of organisms to life in a terrestrial environment under one or another light regime are also varied. As we noted earlier, in relation to light there are three main groups of plants: light-loving(heliophytes), shade-loving(sciophytes) and shade-tolerant. Light-loving and shade-loving plants differ in the position of their ecological optimum.
In light-loving plants it is located in the area of full sunlight. Strong shading has a depressing effect on them. These are plants of open land or well-lit steppe and meadow grasses (the upper tier of the grass stand), 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 the area of low light and cannot tolerate strong light. These are mainly the lower shaded layers of complex plant communities, where shading is the result of “interception” of light by taller plants and co-inhabitants. This includes many indoor and greenhouse plants. For the most part, these come from the herbaceous cover or epiphyte flora of tropical forests.
The ecological curve of the relationship to light in shade-tolerant plants is somewhat asymmetrical, since they grow and develop better in full light, but adapt well to low light. They are a common and highly flexible group of plants in terrestrial environments.
Plants in the terrestrial-air environment have developed adaptations to various light conditions: anatomical-morphological, physiological, etc.
A clear example of anatomical and morphological adaptations is a 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 (meadow bell - Campanula patula and forest - C. trachelium, field violet - Viola arvensis, growing in fields, meadows, forest edges, and forest violets - V. mirabilis), fig. 5.20.
Rice. 5.20. Distribution of leaf sizes depending on conditions
plant habitats: from wet to dry and from shaded to sunny
Note. The shaded area corresponds to conditions prevailing in nature
Under conditions of excess and lack of light, the spatial arrangement of leaf blades in plants varies significantly. In heliophyte plants, the leaves are oriented to reduce the influx of radiation during the most “dangerous” daytime hours. The leaf blades are located vertically or at a large angle to the horizontal plane, so during the day the leaves receive mostly sliding rays (Fig. 5.21).
This is especially pronounced in many steppe plants. An interesting adaptation to the weakening of the received radiation is 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. 5.21. Receipt of direct (S) and diffuse (D) solar radiation to plants with horizontal (A), vertical (B) and differently oriented (C) leaves (according to I. A. Shulgin, 1967)
1,2 - leaves with different angles of inclination; S 1, S 2 - direct radiation reaching them; Stot - its total intake to the plant
Often, shade-tolerant plants are capable of protective movements: changing the position of leaf blades when exposed to strong light. Areas of grass cover with folded oxalis leaves coincide relatively precisely with the location of large sun flares. 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 helps to reflect sunlight (shiny - in laurel, covered with a light hairy coating - in cactus, euphorbia) or weaken their effect (thick cuticle, dense pubescence). The internal structure of the leaf is characterized by the powerful development of palisade tissue and the presence of a large number of small and light chloroplasts (Fig. 5.22).
One of the protective reactions of chloroplasts to excess light is their ability to change orientation and move within the cell, which is clearly expressed in light plants.
In bright light, chloroplasts occupy a wall position in the cell and become an “edge” to the direction of the rays. In low light, they are distributed diffusely in the cell or accumulate in its lower part.
Rice. 5.22. Different sizes of chloroplasts in shade-tolerant plants
(A) and light-loving (B) plants:
1 - yew; 2- larch; 3 - hoof; 4 - spring clearweed (According to T.K. Goryshina, E.G. Spring, 1978)
Physiological adaptations plants to the light conditions of the ground-air environment cover various vital functions. It has been established that in light-loving plants, growth processes react more sensitively to a lack of light compared to shady plants. As a result, there is an increased elongation of stems, which helps plants break through to the light and into the upper tiers of plant communities.
The main physiological adaptations to light lie in the area of photosynthesis. In general terms, the change in photosynthesis depending on light intensity is expressed by the “photosynthesis light curve.” Its following parameters are of ecological importance (Fig. 5.23).
1. The point of intersection of the curve with the ordinate axis (Fig. 5.23, A) corresponds to the magnitude and direction of gas exchange in plants in complete darkness: photosynthesis is absent, respiration takes place (not absorption, but release of CO 2), therefore point a lies below the x-axis.
2. The point of intersection of the light curve with the abscissa axis (Fig. 5.23, b) characterizes the “compensation point,” i.e., the light intensity at which photosynthesis (CO 2 absorption) balances respiration (CO 2 release).
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. 5.23. Photosynthesis light curves:
A - general diagram; B - curves for light-loving (1) and shade-tolerant (2) plants
In Fig. 5.23 the inflection area is conventionally designated by a smooth curve, the break of which corresponds to a point V. The projection of point c onto the x-axis (point d) characterizes the “saturated” light intensity, i.e., the value above which light no longer increases the intensity of photosynthesis. Projection onto the ordinate axis (point d) 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 exhibit seasonal dynamics in their response to light. Thus, in the hairy sedge (Carex pilosa), in early spring in the forest, newly emerged leaves have a plateau of light saturation of photosynthesis at 20 - 25 thousand lux; with summer shading in these same species, the curves of the dependence of photosynthesis on light become corresponding to the “shadow” parameters, t That is, 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 display the “light” features of photosynthesis.
A peculiar form of physiological adaptation during a sharp lack of light is the loss of the plant’s ability to photosynthesize and 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), orchids (Monotropa hypopitys). They live off dead organic matter obtained from trees 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 methods of orientation and is important for searching for prey. Many animal species also have color vision. In this regard, animals, especially victims, developed adaptive features. These include protective, camouflage and warning coloring, protective similarity, 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 mode. Moisture deficiency is one of the most significant features of the land-air environment of life. The evolution of terrestrial organisms took place through adaptation to obtaining and preserving moisture. The humidity regimes of the environment on land are varied - from complete and constant saturation of the air with water vapor, where several thousand millimeters of precipitation falls per year (regions of equatorial and monsoon-tropical climates) to their almost complete absence in the dry air of deserts. Thus, in tropical deserts the average annual precipitation is less than 100 mm per year, and at the same time, rain does not fall every year.
The annual amount of precipitation does not always make it possible to assess the water supply of organisms, since the same amount can characterize a desert climate (in the subtropics) and a very humid one (in the Arctic). An important role is played by the ratio of precipitation and evaporation (total annual evaporation from the free water surface), which also varies in different regions of the globe. Areas where this value exceeds the annual precipitation amount are called arid(dry, arid). Here, for example, plants lack moisture during most of the growing season. Areas in which plants are provided with moisture are called humid, or wet. Transition zones are often identified - semi-arid(semiarid).
The dependence of vegetation on average annual precipitation and temperature is shown in Fig. 5.24.
Rice. 5.24. Dependence of vegetation on the average annual
precipitation and temperature:
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 precipitation regime, the presence of reservoirs, soil moisture reserves, the proximity of groundwater, etc. This has contributed to the development of many adaptations to various water supply regimes in terrestrial organisms.
In Fig. Figure 5.25 from left to right shows the transition from lower algae living in water with cells without vacuoles to primary poikilohydric terrestrial algae, the formation of vacuoles in aquatic green and charophytes, the transition from thallophytes with vacuoles to homoyohydric cormophytes (the distribution of mosses - hydrophytes is still limited to habitats with high air humidity , in dry habitats mosses become secondary poikilohydric); among ferns and angiosperms (but not among gymnosperms) there are also secondary poikilohydric forms. Most leafy plants are homoyohydric due to the presence of cuticular protection against transpiration and strong vacuolation of their cells. It should be noted that xerophilicity of animals and plants is characteristic only of the ground-air environment.
Rice. 5.25. Adaptation of plant water metabolism to terrestrial
way of life (from V. Larcher, 1978)
Precipitation (rain, hail, snow), in addition to providing water and creating moisture reserves, often plays another role ecological role. For example, during heavy rains, the soil does not have time to absorb moisture, the water quickly flows in strong streams and often carries weakly rooted plants, small animals and fertile soil into lakes and rivers. In floodplains, rain can cause floods and thus have adverse effects on the plants and animals living there. In periodically flooded places, unique floodplain fauna and flora are formed.
Hail also has a negative effect on plants and animals. Agricultural crops in individual fields are sometimes completely destroyed by this natural disaster.
The ecological role of snow cover is diverse. For plants whose renewal buds are located in the soil or near its surface, and for many small animals, snow plays the role of a heat-insulating cover, protecting them from low winter temperatures. When frosts are above -14°C under a 20 cm layer of snow, the soil temperature does not drop below 0.2°C. Deep snow cover protects the green parts of plants from freezing, such as Veronica officinalis, hoofed grass, etc., which go under the snow without shedding their leaves. Small land animals lead an active lifestyle in winter, creating numerous galleries of passages under the snow and in its thickness. In the presence of fortified food, rodents (wood and yellow-throated mice, a number of voles, water rats, etc.) can breed there in snowy winters. During severe frosts, hazel grouse, partridges, and black grouse hide under the snow.
Winter snow cover often prevents large animals from obtaining food and moving, 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 inaccessible to smaller animals. Often during snowy winters, the death of roe deer and wild boars is observed.
Large amounts of snow also have a negative impact on plants. In addition to mechanical damage in the form of snow chips or snow blowers, a thick layer of snow can lead to damping off of plants, and when the snow melts, especially in a long spring, to soaking of plants.
From low temperatures When strong winds occur in winters with little snow, plants and animals suffer. Thus, in years when there is little snow, mouse-like rodents, moles and other small animals die. At the same time, in latitudes where precipitation falls in the form of snow in winter, plants and animals have historically adapted to life in snow or on its surface, developing various anatomical, morphological, physiological, behavioral and other characteristics. For example, in some animals the supporting surface of their legs increases in winter by overgrowing them with coarse hair (Fig. 5.26), feathers, and horny scutes.
Others migrate or fall into an inactive state - sleep, hibernation, diapause. A number of animals switch to feeding on certain types of feed.
The whiteness of the snow cover reveals dark animals. The seasonal change in color in the ptarmigan and tundra partridge, ermine (Fig. 5.27), mountain hare, weasel, and arctic fox is undoubtedly associated with selection for camouflage to match the background color.
Precipitation, in addition to its direct impact on organisms, determines one or another air humidity, which, as already noted, plays an important role in the life of plants and animals, as it affects the intensity of their water metabolism. Evaporation from the surface of the body of animals and transpiration in plants are more intense, the less the air is saturated with water vapor.
Absorption by the above-ground parts of droplet-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 over the entire surface of the leaves and aerial roots. The branches of some shrubs and trees, for example saxaul - Halaxylon persicum, H. aphyllum, can absorb vaporous moisture from the air. In higher spore plants and especially lower plants, the absorption of moisture by above-ground parts is a common method of water nutrition (mosses, lichens, etc.). With a lack of moisture, mosses and 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 parts, acquire softness, restore turgor, and resume the processes of photosynthesis and growth.
In plants in highly humid terrestrial habitats, there is often a 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 guttation - this is the release of water through special excretory cells located along the edge or at the tip of the leaf (Fig. 5.28).
Rice. 5.28. Types of guttation in different plants
(according to A.M. Grodzinsky, 1965):
1 - for cereals, 2 - for strawberries, 3 - for tulips, 4 - for milkweeds,
5 - in Bellevalia Sarmatian, 6 - in clover
Not only hygrophytes, but also many mesophytes are capable of guttation. For example, in the Ukrainian steppes, guttation was found in more than half of all plant species. Many meadow grasses humidify so much that they wet the soil surface. This is how animals and plants adapt to the seasonal distribution of precipitation, its quantity and nature. This determines the composition of plants and animals, the timing of certain phases in their development cycle.
Humidity is also affected by the condensation of water vapor, which often occurs in the surface layer of air when the temperature changes. Dew appears when the temperature drops in the evening. Often dew falls in such quantities that it abundantly wets plants, 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 deposition 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 plant habitat based on the water factor, indicators are used that reflect the content and distribution of moisture not only in the air, but also in the soil. Soil water, or soil moisture, is one of the main sources of moisture for plants. Water in the soil is in a fragmented state, interspersed with pores of different 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 the water contained in the soil can be used by plants. Based on its 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 water-free pores. This is almost always (except desert soils) saturated water vapor. When the temperature drops below 0°C, soil moisture turns into ice (initially free water, and with further cooling - and part of the bound).
The total amount of water that can be held by soil (determined by adding excess water and then waiting until it stops dripping out) is called field moisture capacity.
Consequently, the total amount of water in the soil cannot characterize the degree of moisture supply to plants. To determine it, it is necessary to subtract the wilting coefficient from the total amount of water. However, physically accessible 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 wilting of plants. The development of not only the above-ground 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 and more powerful than on wet soils (Fig. 5.29).
Rice. 5.29. Root system of winter wheat
(according to V.G. Khrzhanovsky et al., 1994):
1 - with a lot of precipitation; 2 - at average;
3 - at low
One of the sources of soil moisture is groundwater. When their level is low, 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 humidity, which often negatively affects plants. Too high a groundwater level is also harmful, because it leads to waterlogging of the soil, depletion of oxygen and enrichment in mineral salts. Constant soil moisture, regardless of the vagaries of the weather, ensures an optimal groundwater level.
Temperature conditions. A distinctive feature of the land-air environment is the large range of temperature fluctuations. In most land areas, daily and annual temperature ranges are tens of degrees. Changes in air temperature are especially significant in deserts and subpolar continental regions. For example, the seasonal temperature range in the deserts of Central Asia is 68-77°C, and the daily temperature range is 25-38°C. In the vicinity of Yakutsk, the average January 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 variation in air temperature is sharp and is combined with great 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. Maximum positive temperatures are 38-41°C.
Temperature fluctuations at 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. A special thermal regime is created on this surface: during the day there is strong heating due to the absorption of heat rays, at night there is strong cooling due to radiation. From here, the ground layer of air experiences the sharpest daily temperature fluctuations, which are most pronounced over bare soil.
The thermal regime of plant habitats, for example, is characterized based on temperature measurements directly in the vegetation cover. In herbaceous communities, measurements are taken inside and on the surface of the grass stand, 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 varies and depends on the specific habitat where their life takes place. Thus, terrestrial leafy plants for the most part grow in a wide temperature range, that is, they are eurythermic. Their life span in the active state extends, as a rule, from 5 to 55°C, while these plants are productive between 5 and 40°C. 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 in the temperate zone - with a temperature difference of 5-10 ° C, and tropical plants with an even smaller amplitude - about 3 ° C (Fig. 5.30).
Rice. 5.30. Areas of optimal temperatures for growth and
development of various plants (after Went, 1957)
In poikilothermic organisms, with increasing 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 reach a certain stage of development (for example, in insects - from an egg), i.e. pupation, the imaginal stage, always requires a certain amount of temperature. The product of effective temperature (temperature above the zero point of development, i.e. T-To) by the duration of development (t) gives a species-specific thermal constant development c=t(T-To). Using this equation, you can calculate the time of onset of a certain stage of development, for example, of a plant pest, at which its control is effective.
Plants, as poikilothermic organisms, do not have their own stable body temperature. Their temperature is determined by the thermal balance, i.e., the ratio of energy absorption and release. 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 location of the leaves, etc.). The primary role is played by the cooling effect of transpiration, which prevents severe overheating of plants in hot habitats. As a result of the above reasons, the temperature of plants usually differs (often quite significantly) from the ambient temperature. There are three possible situations here: the plant temperature is higher than the ambient temperature, lower than it, equal to or very close to it. The excess of plant temperature over air temperature occurs not only in highly heated, 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 help reduce transpiration. Arctic plants can warm up quite noticeably (Fig. 5.31).
Another example is the dwarf willow - Salix arctica in Alaska, whose leaves are 2-11 °C warmer than the air during the day and even at night during the polar “24-hour day” - by 1-3 °C.
For early spring ephemeroids, the so-called “snowdrops,” heating of the leaves provides the opportunity for 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 thereby become independent, to a certain extent, from the surrounding thermal background.
Rice. 5.31. Temperature distribution in a rosette plant of the Arctic tundra (Novosieversia glacialis) on a sunny June morning at an air temperature of 11.7 ° C (according to B. A. Tikhomirov, 1963)
On the right is the intensity of life processes in the biosphere: 1 - the coldest layer of air; 2 - upper limit of shoot growth; 3, 4, 5 - zone of greatest activity of life processes and maximum accumulation of organic matter; 6 - permafrost level and lower rooting limit; 7 - area of lowest soil temperatures
A decrease in the temperature of plants compared to the surrounding air is most often observed in highly illuminated and heated areas of the terrestrial sphere (desert, steppe), where the leaf surface of plants is greatly reduced, and increased transpiration helps remove excess heat and prevents overheating. In general terms, we can say that in hot habitats the temperature of the above-ground parts of plants is lower, and in cold habitats it is higher than the air temperature. The coincidence of plant temperature with the ambient air temperature is less common - in conditions that exclude a strong influx of radiation and intense transpiration, for example, in herbaceous plants under the forest canopy, and in open areas - in cloudy weather or during rain.
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 at the earth's surface, up to approximately 20 km altitude (the boundary of the troposphere). Weather variability is manifested in the constant variation of the combination of environmental factors such as temperature and humidity, cloudiness, precipitation, wind strength and direction, etc. (Fig. 5.32).
Rice. 5.32. Atmospheric fronts over the territory of Russia
Weather changes, along with their regular alternation in the annual cycle, are characterized by non-periodic fluctuations, which significantly complicate the conditions for the existence of terrestrial organisms. In Fig. Figure 5.33 uses the example of the codling moth caterpillar Carpocapsa pomonella to show the dependence of mortality on temperature and relative humidity.
Rice. 5.33. Mortality of codling moth caterpillars Carpocapsa
pomonella depending on temperature and humidity (according to R. Dazho, 1975)
It follows from this that equal mortality curves have a concentric shape and that the optimal zone is limited by relative humidity of 55 and 95% and temperature of 21 and 28 ° C.
Light, temperature and air humidity usually determine not the maximum, but the average degree of opening of stomata in plants, since the coincidence of all conditions conducive to their opening rarely happens.
The long-term weather regime characterizes climate of the area. The concept of climate includes not only the average values of meteorological phenomena, but also their annual and daily variations, deviations from them, and their frequency. The climate is determined by the geographical conditions of the area.
The main climatic factors are temperature and humidity, measured by precipitation and water vapor saturation in the air. Thus, in countries remote from the sea, there is a gradual transition from a humid climate through a semiarid intermediate zone with occasional or periodic dry periods to an arid territory, which is characterized by prolonged drought, salinization of soil and water (Fig. 5.34).
Rice. 5.34. Scheme of changes in climate, vegetation and soils along the profile through the main landscapes of the European part of Russia from northwest to southeast to the Caspian lowland (according to V.N. Sukachev, 1934)
Note: Where the precipitation curve intersects the ascending evapotranspiration line, the boundary between humid (left) and arid (right) climates is located. The humus horizon is shown in black, the illuvial horizon is shown in shading.
Each habitat is characterized by a certain ecological climate, i.e., the climate of the ground layer of air, or ecoclimate.
Vegetation has a great influence on climatic factors. Thus, under the forest canopy, air humidity is always higher, and temperature fluctuations are less than in the clearings. The light regime of these places is also different. Different plant associations develop their own regime of light, temperature, humidity, i.e., a unique phytoclimate.
Ecoclimate or phytoclimate data are not always sufficient to fully characterize the climatic conditions of a particular habitat. Local environmental elements (relief, exposure, vegetation, etc.) very often change the regime of light, temperature, humidity, 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 develop in the surface layer of air 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 the 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, tree hollows, and caves inhabited by animals have a stable microclimate. There are no clear differences between ecoclimate and microclimate. It is believed that ecoclimate is the climate of large areas, and microclimate is the climate of individual small areas. Microclimate influences living organisms of a particular territory or locality (Fig. 5.35).
Rice. 5.35. The influence of microclimate on vegetation in the tundra
(according to Yu. I. Chernov, 1979):
at the top is a well-warmed slope of southern exposure;
below - a horizontal section of the plakor (the floristic composition in both sections is the same)
The presence of many microclimates in one area 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 geographic zones and zones. The belts have a latitudinal strike, which, naturally, is primarily due to radiation boundaries and the nature of atmospheric circulation. There are 13 geographic zones on the surface of the globe, spread across continents and oceans (Fig. 5.36).
Rice. 5.36. The ratio of land areas occupied by different
physical-geographical zones, in% (according to N.F. Reimers, 1990)
These are like arctic, antarctic, subarctic, subantarctic, north and south moderate, north and south subarctic, north and south tropical, north and south subequatorial And equatorial. Inside the belts there are geographical zones, where, along with radiation conditions, the moisture of the earth's surface and the ratio of heat and moisture characteristic of a given zone are taken into account. Unlike the ocean, where the supply of moisture is complete, on the continents the ratio of heat and moisture can have significant differences. From here, geographic zones extend to continents and oceans, and geographic zones extend only to continents. Distinguish latitudinal And meridial or longitudinal natural zones. The former stretch from west to east, the latter - from north to south. In the longitudinal direction, latitudinal zones are divided into subzones, and in the latitude - on provinces.
The founder of the doctrine of natural zoning is V.V. Dokuchaev (1846-1903), who substantiated zonality as a universal law of nature. All phenomena within the biosphere are subject to this law. The main reasons for zonation are the shape of the Earth and its position relative to the sun. In addition to latitude, the distribution of heat on Earth is influenced by the nature of the relief and the height of the area above sea level, the ratio of land and sea, sea currents, etc.
Subsequently, the radiation foundations for the formation of the zonality of the globe were developed by A. A. Grigoriev and M. I. Budyko. To establish a quantitative characteristic of the relationship between heat and moisture for various geographical zones, they determined some coefficients. The ratio of heat and moisture is expressed by the ratio of the surface radiation balance to the latent heat of evaporation and the amount of precipitation (radiation dryness index). 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 repeated periodically.
Each zone is confined to a certain range of indicator values: a special nature of geomorphological processes, a special type of climate, vegetation, soil and animal life. The following geographical zones were noted on the territory of the former USSR: icy, tundra, forest-tundra, taiga, mixed forests. Russian plain, monsoon mixed forests of the Far East, forest-steppes, steppes, semi-deserts, temperate deserts, subtropical deserts, 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 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.) chemical compounds, which are associated with certain biological reactions on the part of local flora and fauna.
Along with horizontal zoning in the terrestrial environment, high-rise or vertical zonality.
The vegetation of mountainous countries is richer than on the adjacent plains, and is characterized by an increased distribution of endemic forms. Thus, according to O. E. Agakhanyants (1986), the flora of the Caucasus includes 6,350 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 into the mountains, the same change of zones is repeated as from the equator to the poles. At the foot there are usually deserts, then steppes, deciduous forests, coniferous forests, tundra and, finally, ice. However, there is still no complete analogy. As you climb the mountains, the air temperature decreases (the average air temperature gradient is 0.6 °C per 100 m), evaporation decreases, ultraviolet radiation and illumination increase, etc. All this forces plants to adapt to dry or wet conditions. The dominant plants here are cushion-shaped life forms and perennials, which have developed adaptation to strong ultraviolet radiation and reduced transpiration.
The fauna of the high mountain regions is also unique. Low air pressure, significant solar radiation, sharp fluctuations in day and night temperatures, and changes in air humidity with altitude contributed to the development of specific physiological adaptations in the body 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. Rocky soil complicates or almost eliminates the burrowing activity of animals. Many small animals (small rodents, pikas, lizards, etc.) find refuge in rock crevices and caves. Among the birds typical for mountainous regions are mountain turkeys (sulars), mountain finches, larks, and large birds - bearded vultures, vultures, and condors. In the mountains of large mammals inhabited by rams, goats (including snow goats), chamois, yaks, etc. Predators are represented by such species as wolves, foxes, bears, lynxes, snow leopards (irbis), etc.
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