Pros and cons of the ground air environment. Ground-air environment of life

Ground-air environment - a medium consisting of air, which explains its name. It is usually characterized as follows:

• The air offers almost no resistance, so the shell of organisms is usually not streamlined.
• High oxygen content in the air.
• There is a climate and seasons.
• Closer to the ground, the air temperature is higher, so most species live on the plains.
• The atmosphere lacks the water necessary for life, so organisms settle closer to rivers and other bodies of water.
• Plants that have roots use the minerals found in the soil and, in part, are found in the soil environment.
• The minimum temperature was recorded in Antarctica, which was - 89 ° C, and the maximum + 59 ° C.
• The biological environment is distributed from 2 km below sea level to 10 km above sea level.

In the course of evolution, this environment was mastered later than the water. Its peculiarity lies in the fact that it gaseous, therefore it is characterized by low:

• humidity
• density and pressure
• high oxygen content.

In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations. Animals in the ground-air environment move on the soil or through the air (birds, insects). As a result, animals have lungs and trachea, i.e., the organs by which the land inhabitants of the planet absorb oxygen directly from the air. received a strong development skeletal organs, providing autonomy of movement on land and supporting the body with all its organs in conditions of low density of the medium, thousands of times less than water.

Environmental factors in the ground-air environment differ from other habitats:

• high light intensity
• significant fluctuations in temperature and humidity,
• correlation of all factors with geographic location,
• change of seasons and time of day.

Their impact on organisms is inextricably linked with the movement of air and the position relative to the seas and oceans and is very different from the impact in the aquatic environment. In the land-air environment, there is enough light and air. However, humidity and temperature are very variable. Marshy areas have an excess amount of moisture, in the steppes it is much less. Daily and seasonal fluctuations in temperature are noticeable.

Adaptations of organisms to life in conditions of different temperature and humidity. More adaptations of organisms of the ground - air environment are associated with air temperature and humidity. Animals of the steppe (scorpion, tarantula and karakurt spiders, ground squirrels, field mice) hide from the heat in minks. In animals, the adaptation from heat is the release of sweat.

With the onset of cold weather, birds fly away to warm lands, so that in the spring they will return to the place where they were born and where they will give birth.

A feature of the ground - air environment in the southern regions is an insufficient amount of moisture. Desert animals must be able to conserve their water in order to survive long periods when food is scarce. Herbivores usually manage to do this by storing all available moisture, which is in the stems and seeds they eat. Carnivores obtain water from the wet flesh of their prey. Both types of animals have very efficient kidneys that conserve every drop of moisture and rarely need to drink. Also, desert animals must be able to protect themselves from the brutal heat during the day and the piercing cold at night. Small animals can do this by hiding in rock crevices or burrowing into the sand. Many animals have evolved an impenetrable outer shell, not for protection, but to reduce moisture loss from their bodies.

Adaptation of organisms to movement in the ground - air environment. For many animals of the ground - air environment, it is important to move on the earth's surface or in the air. To do this, they have developed certain adaptations, and their limbs have a different structure. Some have adapted to running (wolf, horse), the second - to jumping (kangaroo, jerboa, horse), others - to flying (birds, bats, insects). Snakes, vipers do not have limbs at all, so they move by arching their bodies.

Much fewer organisms have adapted to life high in the mountains, since there is little soil, moisture and air, and there are difficulties with movement. However, some animals, such as mountain goats moufflons, are able to move almost vertically up and down if there is even a slight bump. Therefore, they can live high in the mountains.

Adaptation of animals to the factor of illumination of the ground-air environment of life structure and size of the eyes. Most animals of this environment have well-developed organs of vision. So, a hawk from the height of its flight sees a mouse that runs across the field.

Ground-air environment- this is the entire surface of the planet, which is limited by a solid surface. Animals, plants, fungi, etc. live in the ground-air environment.

general characteristics. In the course of evolution, the ground-air environment was mastered much later than the water. Life on land required such adaptations that became possible only with a relatively high level of organization of both plants and animals. A feature of the land-air environment of life is that the organisms that live here are surrounded by air and a gaseous environment characterized by low humidity, density and pressure, and a high oxygen content. As a rule, animals in this environment move along the soil (solid substrate), and plants take root in it.

In the ground-air environment, the operating environmental factors have a number of characteristic features: higher light intensity in comparison with other environments, significant temperature fluctuations, changes in humidity depending on the geographical location, season and time of day. The impact of the above factors is inextricably linked with the movement of air masses - the wind. In the process of evolution, living organisms of the terrestrial-air environment have developed characteristic anatomical, morphological, physiological, behavioral and other adaptations. For example, organs have appeared that provide direct assimilation of atmospheric oxygen in the process of respiration (lungs and tracheae of animals, stomata of plants). Skeletal formations (the skeleton of animals, the mechanical and supporting tissues of plants) that support the body under conditions of low density of the medium have received a strong development. Adaptations have been developed to protect against adverse factors, such as the frequency and rhythm of life cycles, the complex structure of covers, thermoregulation mechanisms, etc. A close relationship with the soil (animal limbs, plant roots) has formed, animal mobility has developed in search of food, airborne seeds, fruits and pollen of plants, flying animals.

Air density- the mass of gas of the Earth's atmosphere per unit volume or the specific mass of air under natural conditions. The value of air density is a function of the height of the measurements, its temperature and humidity. The standard value is generally considered to be 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 it is rather 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 the metabolism of terrestrial organisms, and on the basis of the high efficiency of oxidative processes, homoiothermia of animals arose. Only in places, under specific conditions, a temporary oxygen deficiency is created, for example, in decaying plant residues, stocks of grain, flour, etc.

In some areas of the surface layer of air, the content of carbon dioxide can vary within fairly significant limits. So, in the absence of wind in large industrial centers, cities, its concentration can increase tenfold.

Regular daily changes in the content of carbonic acid in the surface layers, due to the rhythm of plant photosynthesis.

In the course of evolution, this environment was mastered later than the water. Its peculiarity lies in the fact that it is gaseous, therefore it is characterized by low humidity, density and pressure, high oxygen content. In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations. Animals in the ground-air environment move through the soil or through the air (birds, insects), and plants take root in the soil. In this regard, animals have lungs and tracheas, and plants have a stomatal apparatus, i.e. organs by which the land inhabitants of the planet absorb oxygen directly from the air. The skeletal organs, which provide autonomy of movement on land and support the body with all its organs in conditions of low density of the medium, thousands of times less than water, have received a strong development. Environmental factors in the terrestrial-air environment differ from other habitats in high light intensity, significant fluctuations in air temperature and humidity, the correlation of all factors with geographical location, the change of seasons of the year and time of day. Their impact on organisms is inextricably linked with the movement of air and position relative to the seas and oceans and is very different from the impact in the aquatic environment (Table 1).

Table 1. Habitat conditions for air and water organisms (according to D. F. Mordukhai-Boltovsky, 1974)

Land animals and plants have developed their own, no less original adaptations to adverse environmental factors: the complex structure of the body and its integument, the frequency and rhythm of life cycles, thermoregulation mechanisms, etc. Purposeful animal mobility has developed in search of food, wind-borne spores, seeds and pollen of plants, as well as plants and animals, whose life is entirely connected with the air environment. An exceptionally close functional, resource and mechanical relationship with the soil has been formed. Many of the adaptations we have discussed above as examples in the characterization of abiotic environmental factors. Therefore, it makes no sense to repeat now, because we will return to them in practical exercises

Soil as habitat

The Earth is the only one of the planets that has soil (edasphere, pedosphere) - a special, upper shell of land. This shell was formed in a historically foreseeable time - it is the same age as land life on the planet. For the first time, M. V. Lomonosov ("On the Layers of the Earth") answered the question about the origin of the soil: "... the soil originated from the bending of animal and plant bodies ... by the length of time ...". And the great Russian scientist you. You. Dokuchaev (1899: 16) was the first to call soil an independent natural body and proved that soil is "... the same independent natural-historical body as any plant, any animal, any mineral ... it is the result, a function of the cumulative, mutual activity of the climate of a given area, its plant and animal organisms, the relief and age of the country... and finally, the subsoil, i.e., ground parent rocks... All these soil-forming agents, in essence, are completely equivalent in magnitude and take an equal part in the formation of normal soil... ". And the modern well-known soil scientist N. A. Kachinsky ("Soil, its properties and life", 1975) gives the following definition of soil: air, water), plant and animal organisms.

The main structural elements of the soil are: the mineral base, organic matter, air and water.

Mineral base (skeleton)(50-60% of the total soil) is an inorganic substance formed as a result of the underlying mountain (parent, soil-forming) rock as a result of its weathering. Sizes of skeletal particles: from boulders and stones to the smallest grains of sand and silt particles. The physicochemical properties of soils are mainly determined by the composition of parent rocks.

The permeability and porosity of the soil, which ensure the circulation of both water and air, depend on the ratio of clay and sand in the soil, the size of the fragments. In a temperate climate, it is ideal if the soil is formed by equal amounts of clay and sand, that is, it is loam. In this case, the soils are not threatened by either waterlogging or drying out. Both are equally detrimental to both plants and animals.

organic matter- up to 10% of the soil, is formed from dead biomass (plant mass - litter of leaves, branches and roots, dead trunks, grass rags, organisms of dead animals), crushed and processed into soil humus by microorganisms and certain groups of animals and plants. The simpler elements formed as a result of the decomposition of organic matter are again assimilated by plants and are involved in the biological cycle.

Air(15-25%) in the soil is contained in cavities - pores, between organic and mineral particles. In the absence (heavy clay soils) or the filling of pores with water (during flooding, thawing of permafrost), aeration worsens in the soil and anaerobic conditions develop. Under such conditions, the physiological processes of organisms that consume oxygen - aerobes - are inhibited, the decomposition of organic matter is slow. Gradually accumulating, they form peat. Large reserves of peat are characteristic of swamps, swampy forests, and tundra communities. Peat accumulation is especially pronounced in the northern regions, where coldness and waterlogging of soils mutually determine and complement each other.

Water(25-30%) in the soil is represented by 4 types: gravitational, hygroscopic (bound), capillary and vaporous.

Gravity- mobile water, occupying wide gaps between soil particles, seeps down under its own weight to the groundwater level. Easily absorbed by plants.

hygroscopic, or bound– is adsorbed around colloidal particles (clay, quartz) of the soil and is retained in the form of a thin film due to hydrogen bonds. It is released from them at high temperature (102-105°C). It is inaccessible to plants, does not evaporate. In clay soils, such water is up to 15%, in sandy soils - 5%.

capillary- is held around soil particles by the force of surface tension. Through narrow pores and channels - capillaries, it rises from the groundwater level or diverges from cavities with gravitational water. Better retained by clay soils, easily evaporates. Plants easily absorb it.

Vaporous- occupies all pores free from water. Evaporates first.

There is a constant exchange of surface soil and groundwater, as a link in the general water cycle in nature, changing speed and direction depending on the season and weather conditions.

Soil profile structure

Soil structure is heterogeneous both horizontally and vertically. The horizontal heterogeneity of soils reflects the heterogeneity of the distribution of soil-forming rocks, position in the relief, climate features and is consistent with the distribution of vegetation cover over the territory. Each such heterogeneity (soil type) is characterized by its own vertical heterogeneity, or soil profile, which is formed as a result of vertical migration of water, organic and mineral substances. This profile is a collection of layers, or horizons. All processes of soil formation proceed in the profile with the obligatory consideration of its division into horizons.

Regardless of the type of soil, three main horizons are distinguished in its profile, differing in morphological and chemical properties among themselves and between similar horizons in other soils:

1. Humus-accumulative horizon A. It accumulates and transforms organic matter. After transformation, some of the elements from this horizon are taken out with water to the underlying ones.

This horizon is the most complex and important of the entire soil profile in terms of its biological role. It consists of forest litter - A0, formed by ground litter (dead organic matter of a weak degree of decomposition on the soil surface). According to the composition and thickness of the litter, one can judge the ecological functions of the plant community, its origin, and stage of development. Below the litter there is a dark-colored humus horizon - A1, formed by crushed, variously decomposed remains of plant mass and animal mass. Vertebrates (phytophages, saprophages, coprophages, predators, necrophages) participate in the destruction of remains. As the grinding progresses, organic particles enter the next lower horizon - eluvial (A2). In it, the chemical decomposition of humus into simple elements occurs.

2. Illuvial, or washout horizon B. Compounds removed from the A horizon are deposited in it and converted into soil solutions. These are humic acids and their salts that react with the weathering crust and are assimilated by plant roots.

3. Parent (underlying) rock (weathering crust), or horizon C. From this horizon - also after transformation - minerals pass into the soil.

Based on the degree of mobility and size, all soil fauna is grouped into the following three ecological groups:

Microbiotype or microbiota(not to be confused with the endemic of Primorye - a plant with a cross-pair microbiota!): Organisms representing an intermediate link between plant and animal organisms (bacteria, green and blue-green algae, fungi, protozoa). These are aquatic organisms, but smaller than those living in water. They live in the pores of the soil filled with water - micro-reservoirs. The main link in the detrital food chain. They can dry out, and with the resumption of sufficient moisture, they come to life again.

Mesobiotype, or mesobiota- a set of small mobile insects that are easily extracted from the soil (nematodes, mites (Oribatei), small larvae, springtails (Collembola), etc. Very numerous - up to millions of individuals per 1 m 2. They feed on detritus, bacteria. They use natural cavities in the soil, they themselves they do not dig their own passages.When the humidity decreases, they go deeper.Adaptation from drying out: protective scales, a solid thick shell."Floods" the mesobiota waits in the soil air bubbles.

Macrobiotype, or macrobiota- large insects, earthworms, mobile arthropods living between the litter and soil, other animals, up to burrowing mammals (moles, shrews). Earthworms predominate (up to 300 pcs/m2).

Each type of soil and each horizon corresponds to its own complex of living organisms involved in the utilization of organic matter - edaphon. The most numerous and complex composition of living organisms has the upper - organogenic layers-horizons (Fig. 4). The illuvial is inhabited only by bacteria (sulfur bacteria, nitrogen-fixing), which do not need oxygen.

According to the degree of connection with the environment in edaphone, three groups are distinguished:

Geobionts- permanent inhabitants of the soil (earthworms (Lymbricidae), many primary wingless insects (Apterigota)), from mammals, moles, mole rats.

Geophiles- animals in which part of the development cycle takes place in a different environment, and part in the soil. These are the majority of flying insects (locusts, beetles, centipede mosquitoes, bears, many butterflies). Some go through the larval phase in the soil, while others go through the pupal phase.

geoxenes- animals that sometimes visit the soil as a shelter or refuge. These include all mammals living in burrows, many insects (cockroaches (Blattodea), hemipterans (Hemiptera), some species of beetles).

Special group - psammophytes and psammophiles(marble beetles, ant lions); adapted to loose sands in deserts. Adaptations to life in a mobile, dry environment in plants (saxaul, sandy acacia, sandy fescue, etc.): adventitious roots, dormant buds on the roots. The former begin to grow when falling asleep with sand, the latter when blowing sand. They are saved from sand drift by rapid growth, reduction of leaves. Fruits are characterized by volatility, springiness. Sandy covers on the roots, corking of the bark, and strongly developed roots protect against drought. Adaptations to life in a mobile, dry environment in animals (indicated above, where thermal and humid conditions were considered): they mine the sands - they push them apart with their bodies. In burrowing animals, paws-skis - with growths, with hairline.

Soil is an intermediate medium between water (temperature conditions, low oxygen content, saturation with water vapor, the presence of water and salts in it) and air (air cavities, sudden changes in humidity and temperature in the upper layers). For many arthropods, soil was the medium through which they were able to move from an aquatic to a terrestrial lifestyle. The main indicators of soil properties, reflecting its ability to be a habitat for living organisms, are the hydrothermal regime and aeration. Or humidity, temperature and soil structure. All three indicators are closely related. With an increase in humidity, thermal conductivity increases and soil aeration worsens. The higher the temperature, the more evaporation occurs. The concepts of physical and physiological dryness of soils are directly related to these indicators.

Physical dryness is a common occurrence during atmospheric droughts, due to a sharp reduction in water supply due to a long absence of precipitation.

In Primorye, such periods are typical for late spring and are especially pronounced on the slopes of southern exposures. Moreover, with the same position in the relief and other similar growth conditions, the better the vegetation cover is developed, the faster the state of physical dryness sets in. Physiological dryness is a more complex phenomenon, it is due to adverse environmental conditions. It consists in the physiological inaccessibility of water with a sufficient, and even excessive amount of it in the soil. As a rule, water becomes physiologically inaccessible at low temperatures, high salinity or acidity of soils, the presence of toxic substances, and a lack of oxygen. At the same time, water-soluble nutrients such as phosphorus, sulfur, calcium, potassium, etc., become inaccessible. - taiga forests. This explains the strong suppression of higher plants in them and the wide distribution of lichens and mosses, especially sphagnum. One of the important adaptations to the harsh conditions in the edasphere is mycorrhizal nutrition. Almost all trees are associated with mycorrhizal fungi. Each type of tree has its own mycorrhiza-forming type of fungus. Due to mycorrhiza, the active surface of root systems increases, and the secretions of the fungus by the roots of higher plants are easily absorbed.

As V. V. Dokuchaev said, “…Soil zones are also natural-historical zones: here the closest connection between climate, soil, animal and plant organisms is obvious…”. This is clearly seen in the example of soil cover in forest areas in the north and south of the Far East.

A characteristic feature of the soils of the Far East, which are formed under the conditions of a monsoonal, i.e., very humid climate, is the strong washing out of elements from the eluvial horizon. But in the northern and southern regions of the region, this process is not the same due to the different heat supply of habitats. Soil formation in the Far North takes place under conditions of a short growing season (no more than 120 days), and widespread permafrost. The lack of heat is often accompanied by waterlogging of soils, low chemical activity of weathering of soil-forming rocks and slow decomposition of organic matter. The vital activity of soil microorganisms is strongly suppressed, and the assimilation of nutrients by plant roots is inhibited. As a result, the northern cenoses are characterized by low productivity - wood reserves in the main types of larch woodlands do not exceed 150 m2/ha. At the same time, the accumulation of dead organic matter prevails over its decomposition, as a result of which thick peaty and humus horizons are formed, and the humus content is high in the profile. So, in the northern larch forests, the thickness of the forest litter reaches 10-12 cm, and the reserves of undifferentiated mass in the soil are up to 53% of the total biomass reserve of the stand. At the same time, elements are carried out of the profile, and when the permafrost is close, they accumulate in the illuvial horizon. In soil formation, as in all cold regions of the northern hemisphere, the leading process is podzol formation. Zonal soils on the northern coast of the Sea of ​​Okhotsk are Al-Fe-humus podzols, and podburs in the continental regions. Peat soils with permafrost in the profile are common in all regions of the Northeast. Zonal soils are characterized by a sharp differentiation of horizons by color. In the southern regions, the climate has features similar to the climate of the humid subtropics. The leading factors of soil formation in Primorye against the background of high air humidity are temporarily excessive (pulsating) moisture and a long (200 days), very warm growing season. They cause the acceleration of deluvial processes (weathering of primary minerals) and the very rapid decomposition of dead organic matter into simple chemical elements. The latter are not taken out of the system, but are intercepted by plants and soil fauna. In mixed broad-leaved forests in the south of Primorye, up to 70% of the annual litter is “processed” during the summer, and the thickness of the litter does not exceed 1.5-3 cm. The boundaries between the horizons of the soil profile of zonal brown soils are weakly expressed. With a sufficient amount of heat, the hydrological regime plays the main role in soil formation. The well-known Far Eastern soil scientist G.I. Ivanov divided all the landscapes of the Primorsky Territory into landscapes of fast, weakly restrained and difficult water exchange. In landscapes of rapid water exchange, the leading one is burozem formation process. The soils of these landscapes, which are also zonal - brown forest soils under coniferous-broad-leaved and broad-leaved forests, and brown-taiga soils - under coniferous forests, are characterized by very high productivity. Thus, stocks of forest stands in black-fir-broad-leaved forests, occupying the lower and middle parts of the northern slopes on weakly skeletal loam, reach 1000 m 3 /ha. Brown soils are distinguished by weakly expressed differentiation of the genetic profile.

In landscapes with weakly restrained water exchange, burozem formation is accompanied by podzolization. In the soil profile, in addition to the humus and illuvial horizons, a clarified eluvial horizon is distinguished and signs of profile differentiation appear. They are characterized by a weakly acid reaction of the environment and a high content of humus in the upper part of the profile. The productivity of these soils is less - stocks of forest stands on them are reduced to 500 m 3 /ha.

In landscapes with difficult water exchange, due to systematic strong waterlogging, anaerobic conditions are created in the soils, processes of gleying and peating of the humus layer develop. Brown-taiga gley-podzolized, peaty- and peaty-gley soils under fir-spruce taiga peaty and peat-podzolized - under larch forests. Due to weak aeration, biological activity decreases, and the thickness of organogenic horizons increases. The profile is sharply demarcated into humus, eluvial, and illuvial horizons. Since each type of soil, each soil zone has its own characteristics, organisms also differ in their selectivity in relation to these conditions. According to the appearance of the vegetation cover, one can judge moisture, acidity, heat supply, salinity, the composition of the parent rock and other characteristics of the soil cover.

Not only flora and vegetation structure, but also fauna, with the exception of micro- and mesofauna, are specific for different soils. For example, about 20 species of beetles are halophiles that live only in soils with high salinity. Even earthworms reach their greatest abundance in moist, warm soils with a powerful organogenic layer.

A NEW LOOK Adaptations of organisms to living in the ground-air environmentLiving organisms in ground-air environment surrounded by air. The air has a low density and, as a result, a low lifting force, insignificant support and low resistance to the movement of organisms. Terrestrial organisms live in conditions of relatively low and constant atmospheric pressure, also due to low air density.

Air has a low heat capacity, so it heats up quickly and cools down just as quickly. The rate of this process is inversely related to the amount of water vapor it contains.

Light air masses have greater mobility, both horizontally and vertically. This helps to maintain a constant level of the gas composition of the air. The oxygen content in air is much higher than in water, so oxygen on land is not a limiting factor.

Light in conditions of terrestrial habitation, due to the high transparency of the atmosphere, does not act as a limiting factor, in contrast to the aquatic environment.

The ground-air environment has different modes of humidity: from the complete and constant saturation of air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. The variability of air humidity during the day and seasons of the year is also great.

Moisture on land acts as a limiting factor.

Due to the presence of gravity and the lack of buoyancy, the terrestrial inhabitants of the land have well-developed support systems that support their body. In plants, these are various mechanical tissues, especially powerfully developed in trees. Animals have developed both an external (arthropod) and an internal (chordate) skeleton during the evolutionary process. Some groups of animals have a hydroskeleton (roundworms and annelids). Problems in terrestrial organisms with maintaining the body in space and overcoming the forces of gravity have limited their maximum mass and size. The largest land animals are inferior in size and mass to the giants of the aquatic environment (the mass of an elephant reaches 5 tons, and a blue whale - 150 tons).

The low air resistance contributed to the progressive evolution of the locomotion systems of terrestrial animals. So, mammals acquired the highest speed of movement on land, and birds mastered the air environment, having developed the ability to fly.

High mobility of air in vertical and horizontal directions is used by some terrestrial organisms at different stages of their development for settling with the help of air currents (young spiders, insects, spores, seeds, plant fruits, protist cysts). By analogy with aquatic planktonic organisms, as adaptations for passive soaring in the air, insects have developed similar adaptations - small body sizes, various outgrowths that increase the relative surface of the body or some of its parts. Seeds and fruits dispersed by the wind have various pterygoid and paragayate appendages that increase their ability to plan.

The adaptations of terrestrial organisms to the preservation of moisture are also diverse. In insects, the body is reliably protected from drying out by a multilayer chitinized cuticle, the outer layer of which contains fats and wax-like substances. Similar water-saving adaptations are also developed in reptiles. The ability for internal fertilization developed in terrestrial animals made them independent of the presence of an aquatic environment.

The soil is a complex system consisting of solid particles surrounded by air and water.

Depending on the type - clayey, sandy, clayey-sandy and others - the soil is more or less permeated with cavities filled with a mixture of gases and aqueous solutions. In the soil, in comparison with the surface layer of air, temperature fluctuations are smoothed out, and at a depth of 1 m, seasonal temperature changes are also imperceptible.

The uppermost soil horizon contains more or less humus, on which plant productivity depends. The middle layer located under it contains washed out from the top layer and converted substances. The bottom layer is mother breed.

Water in the soil is present in voids, the smallest spaces. The composition of soil air changes dramatically with depth: the oxygen content decreases, and carbon dioxide increases. When the soil is flooded with water or intensive decay of organic residues, anoxic zones appear. Thus, the conditions of existence in the soil are different at its different horizons.

In the course of evolution, this environment was mastered later than the water. Its peculiarity lies in the fact that it is gaseous, therefore it is characterized by low humidity, density and pressure, high oxygen content.

In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations.

Animals in the ground-air environment move through the soil or through the air (birds, insects), and plants take root in the soil. In this regard, animals developed lungs and tracheas, while plants developed a stomatal apparatus, i.e.

organs by which the land inhabitants of the planet absorb oxygen directly from the air. The skeletal organs, which provide autonomy of movement on land and support the body with all its organs in conditions of low density of the medium, thousands of times less than water, have received a strong development.

Environmental factors in the terrestrial-air environment differ from other habitats in high light intensity, significant fluctuations in air temperature and humidity, the correlation of all factors with geographical location, the change of seasons of the year and time of day.

Their impact on organisms is inextricably linked with the movement of air and the position relative to the seas and oceans and is very different from the impact in the aquatic environment (Table 1).

Table 5

Living conditions of air and water organisms

(according to D. F. Mordukhai-Boltovsky, 1974)

Land animals and plants have developed their own, no less original adaptations to adverse environmental factors: the complex structure of the body and its integument, the frequency and rhythm of life cycles, thermoregulation mechanisms, etc.

Purposeful mobility of animals in search of food developed, wind-borne spores, seeds and pollen of plants, as well as plants and animals, whose life is entirely connected with the air, appeared. An exceptionally close functional, resource and mechanical relationship with the soil has been formed.

Many of the adaptations we have discussed above as examples in the characterization of abiotic environmental factors.

Therefore, it makes no sense to repeat now, because we will return to them in practical exercises

Soil as habitat

Earth is the only planet that has soil (edasphere, pedosphere) - a special, upper shell of land.

This shell was formed in a historically foreseeable time - it is the same age as land life on the planet. For the first time, the question of the origin of the soil was answered by M.V. Lomonosov ("On the layers of the earth"): "... the soil came from the bending of animal and plant bodies ... by the length of time ...".

And the great Russian scientist you. You. Dokuchaev (1899: 16) was the first to call soil an independent natural body and proved that soil is "... the same independent natural-historical body as any plant, any animal, any mineral ... it is the result, a function of the cumulative, mutual activity of the climate of a given area, its plant and animal organisms, the relief and age of the country ..., finally, the subsoil, i.e.

ground parent rocks. ... All these soil-forming agents, in essence, are completely equivalent in magnitude and take an equal part in the formation of normal soil ... ".

And the modern well-known soil scientist N.A.

Kachinsky ("Soil, its properties and life", 1975) gives the following definition of soil: "Under the soil should be understood all the surface layers of rocks, processed and changed by the combined influence of climate (light, heat, air, water), plant and animal organisms" .

The main structural elements of the soil are: the mineral base, organic matter, air and water.

Mineral base (skeleton)(50-60% of the total soil) is an inorganic substance formed as a result of the underlying mountain (parent, soil-forming) rock as a result of its weathering.

Sizes of skeletal particles: from boulders and stones to the smallest grains of sand and silt particles. The physicochemical properties of soils are mainly determined by the composition of parent rocks.

The permeability and porosity of the soil, which ensure the circulation of both water and air, depend on the ratio of clay and sand in the soil, the size of the fragments.

In temperate climates, it is ideal if the soil is formed by equal amounts of clay and sand, i.e. represents loam.

In this case, the soils are not threatened by either waterlogging or drying out. Both are equally detrimental to both plants and animals.

organic matter- up to 10% of the soil, is formed from dead biomass (plant mass - litter of leaves, branches and roots, dead trunks, grass rags, organisms of dead animals), crushed and processed into soil humus by microorganisms and certain groups of animals and plants.

The simpler elements formed as a result of the decomposition of organic matter are again assimilated by plants and are involved in the biological cycle.

Air(15-25%) in the soil is contained in cavities - pores, between organic and mineral particles. In the absence (heavy clay soils) or the filling of pores with water (during flooding, thawing of permafrost), aeration worsens in the soil and anaerobic conditions develop.

Under such conditions, the physiological processes of organisms that consume oxygen - aerobes - are inhibited, the decomposition of organic matter is slow. Gradually accumulating, they form peat. Large reserves of peat are characteristic of swamps, swampy forests, and tundra communities. Peat accumulation is especially pronounced in the northern regions, where coldness and waterlogging of soils mutually determine and complement each other.

Water(25-30%) in the soil is represented by 4 types: gravitational, hygroscopic (bound), capillary and vaporous.

Gravity- mobile water, occupying wide gaps between soil particles, seeps down under its own weight to the groundwater level.

Easily absorbed by plants.

hygroscopic, or bound– is adsorbed around colloidal particles (clay, quartz) of the soil and is retained in the form of a thin film due to hydrogen bonds. It is released from them at high temperature (102-105°C). It is inaccessible to plants, does not evaporate. In clay soils, such water is up to 15%, in sandy soils - 5%.

capillary- is held around soil particles by the force of surface tension.

Through narrow pores and channels - capillaries, it rises from the groundwater level or diverges from cavities with gravitational water. Better retained by clay soils, easily evaporates.

Plants easily absorb it.

Vaporous- occupies all pores free from water. Evaporates first.

There is a constant exchange of surface soil and groundwater, as a link in the general water cycle in nature, changing speed and direction depending on the season and weather conditions.

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Gas composition of the atmosphere is also an important climatic factor.

Approximately 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases.

It was in the terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homoiothermia arose. Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment. Only in places, under specific conditions, is a temporary deficit created, for example, in accumulations of decaying plant residues, stocks of grain, flour, etc.

For example, in the absence of wind in the center of large cities, its concentration increases tenfold. Regular daily changes in the carbon dioxide content in the surface layers, associated with the rhythm of plant photosynthesis, and seasonal, due to changes in the intensity of respiration of living organisms, mainly the microscopic population of soils. Increased air saturation with carbon dioxide occurs in zones of volcanic activity, near thermal springs and other underground outlets of this gas.

Low air density determines its low lifting force and insignificant bearing capacity.

The inhabitants of the air must have their own support system that supports the body: plants - a variety of mechanical tissues, animals - a solid or, much less often, a hydrostatic skeleton.

Wind

storms

Pressure

The low density of air causes a relatively low pressure on land. Normally, it is equal to 760 mm Hg, Art. As altitude increases, pressure decreases. At an altitude of 5800 m, it is only half normal. Low pressure may limit the distribution of species in the mountains. For most vertebrates, the upper limit of life is about 6000 m. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiratory rate.

Approximately the same are the limits of advancement to the mountains of higher plants. Somewhat more hardy are arthropods (springtails, mites, spiders) that can be found on glaciers above the vegetation boundary.

In general, all terrestrial organisms are much more stenobatic than aquatic ones.

Ground-Air Habitat

In the course of evolution, this environment was mastered later than the water. Environmental factors in the terrestrial-air environment differ from other habitats in high light intensity, significant fluctuations in air temperature and humidity, the correlation of all factors with geographical location, the change of seasons of the year and time of day.

The environment is gaseous, therefore it is characterized by low humidity, density and pressure, high oxygen content.

Characterization of abiotic environmental factors of light, temperature, humidity - see the previous lecture.

Gas composition of the atmosphere is also an important climatic factor. Approximately 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases.

At present, the atmosphere consists mainly of nitrogen, oxygen, and relatively smaller amounts of argon and carbon dioxide.

All other gases present in the atmosphere are contained only in trace amounts. Of particular importance for the biota is the relative content of oxygen and carbon dioxide.

It was in the terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homoiothermia arose. Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment.

Only in places, under specific conditions, is a temporary deficit created, for example, in accumulations of decaying plant residues, stocks of grain, flour, etc.

The content of carbon dioxide can vary in certain areas of the surface layer of air in a fairly significant range. For example, in the absence of wind in the center of large cities, its concentration increases tenfold. Regular daily changes in the carbon dioxide content in the surface layers, associated with the rhythm of plant photosynthesis, and seasonal, due to changes in the intensity of respiration of living organisms, mainly the microscopic population of soils.

Increased air saturation with carbon dioxide occurs in zones of volcanic activity, near thermal springs and other underground outlets of this gas. The low content of carbon dioxide inhibits the process of photosynthesis.

Under indoor conditions, the rate of photosynthesis can be increased by increasing the concentration of carbon dioxide; this is used in the practice of greenhouse and greenhouse farming.

Air nitrogen for most inhabitants of the terrestrial environment is an inert gas, but a number of microorganisms (nodule bacteria, Azotobacter, clostridia, blue-green algae, etc.) have the ability to bind it and involve it in the biological cycle.

Local impurities entering the air can also significantly affect living organisms.

This is especially true for toxic gaseous substances - methane, sulfur oxide (IV), carbon monoxide (II), nitrogen oxide (IV), hydrogen sulfide, chlorine compounds, as well as particles of dust, soot, etc., polluting the air in industrial areas. The main modern source of chemical and physical pollution of the atmosphere is anthropogenic: the work of various industrial enterprises and transport, soil erosion, etc.

n. Sulfur oxide (SO2), for example, is toxic to plants even at concentrations from one fifty-thousandth to one millionth of the volume of air .. Some plant species are especially sensitive to SO2 and serve as a sensitive indicator of its accumulation in the air (for example , lichens.

Low air density determines its low lifting force and insignificant bearing capacity. The inhabitants of the air must have their own support system that supports the body: plants - a variety of mechanical tissues, animals - a solid or, much less often, a hydrostatic skeleton.

In addition, all the inhabitants of the air environment are closely connected with the surface of the earth, which serves them for attachment and support. Life in a suspended state in the air is impossible. True, many microorganisms and animals, spores, seeds and pollen of plants are regularly present in the air and are carried by air currents (anemochory), many animals are capable of active flight, but in all these species the main function of their life cycle is reproduction. - carried out on the surface of the earth.

For most of them, being in the air is associated only with resettlement or the search for prey.

Wind It has a limiting effect on the activity and even distribution of organisms. Wind can even change the appearance of plants, especially in habitats such as alpine zones where other factors are limiting. In open mountain habitats, wind limits plant growth, causing plants to bend to the windward side.

In addition, wind increases evapotranspiration in low humidity conditions. Of great importance are storms, although their action is purely local. Hurricanes, as well as ordinary winds, are capable of transporting animals and plants over long distances and thereby changing the composition of communities.

Pressure, apparently, is not a limiting factor of direct action, but it is directly related to weather and climate, which have a direct limiting effect.

The low density of air causes a relatively low pressure on land. Normally, it is equal to 760 mm Hg, Art. As altitude increases, pressure decreases. At an altitude of 5800 m, it is only half normal.

Low pressure may limit the distribution of species in the mountains.

For most vertebrates, the upper limit of life is about 6000 m. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiratory rate. Approximately the same are the limits of advancement to the mountains of higher plants. Somewhat more hardy are arthropods (springtails, mites, spiders) that can be found on glaciers above the vegetation boundary.

Lecture 3 HABITAT AND THEIR CHARACTERISTICS (2h)

1. Aquatic habitat

2. Ground-air habitat

3. Soil as a habitat

4. The body as a habitat

In the process of historical development, living organisms have mastered four habitats. The first is water. Life originated and developed in water for many millions of years. The second - land-air - on land and in the atmosphere, plants and animals arose and rapidly adapted to new conditions. Gradually transforming the upper layer of land - the lithosphere, they created a third habitat - the soil, and themselves became the fourth habitat.

Aquatic habitat - hydrosphere

Ecological groups of hydrobionts. The warmest seas and oceans (40,000 species of animals) are distinguished by the greatest diversity of life in the equatorial region and the tropics; to the north and south, the flora and fauna of the seas are depleted hundreds of times. As for the distribution of organisms directly in the sea, their bulk is concentrated in the surface layers (epipelagial) and in the sublittoral zone. Depending on the method of movement and stay in certain layers, marine life is divided into three ecological groups: nekton, plankton and benthos.

Nekton(nektos - floating) - actively moving large animals that can overcome long distances and strong currents: fish, squid, pinnipeds, whales. In fresh water bodies, nekton also includes amphibians and many insects.

Plankton(planktos - wandering, soaring) - a collection of plants (phytoplankton: diatoms, green and blue-green (fresh water only) algae, plant flagellates, peridine, etc.) and small animal organisms (zooplankton: small crustaceans, from larger ones - pteropods mollusks, jellyfish, ctenophores, some worms), living at different depths, but not capable of active movement and resistance to currents. The composition of plankton also includes animal larvae, forming a special group - neuston. This is a passively floating "temporary" population of the uppermost layer of water, represented by various animals (decapods, barnacles and copepods, echinoderms, polychaetes, fish, mollusks, etc.) in the larval stage. The larvae, growing up, pass into the lower layers of the pelagela. Above the neuston is the pleuston - these are organisms in which the upper part of the body grows above the water, and the lower part grows in the water (duckweed - Lemma, siphonophores, etc.). Plankton plays an important role in the trophic relationships of the biosphere, since is food for many aquatic life, including the main food for baleen whales (Myatcoceti).

Benthos(benthos - depth) - bottom hydrobionts. Represented mainly by attached or slowly moving animals (zoobenthos: foraminephores, fish, sponges, coelenterates, worms, brachiopods, ascidians, etc.), more numerous in shallow water. Plants (phytobenthos: diatoms, green, brown, red algae, bacteria) also enter benthos in shallow water. At a depth where there is no light, phytobenthos is absent. Along the coasts there are flowering plants of zoster, rupee. The stony areas of the bottom are richest in phytobenthos.

In lakes, zoobenthos is less abundant and diverse than in the sea. It is formed by protozoa (ciliates, daphnia), leeches, mollusks, insect larvae, etc. The phytobenthos of the lakes is formed by free-swimming diatoms, green and blue-green algae; brown and red algae are absent.

Rooting coastal plants in lakes form distinct belts, the species composition and appearance of which are consistent with environmental conditions in the land-water boundary zone. Hydrophytes grow in the water near the shore - plants semi-submerged in water (arrowhead, calla, reeds, cattail, sedges, trichaetes, reeds). They are replaced by hydatophytes - plants submerged in water, but with floating leaves (lotus, duckweed, egg-pods, chilim, takla) and - further - completely submerged (weeds, elodea, hara). Hydatophytes also include plants floating on the surface (duckweed).

The high density of the aquatic environment determines the special composition and nature of the change in life-supporting factors. Some of them are the same as on land - heat, light, others are specific: water pressure (with depth increases by 1 atm for every 10 m), oxygen content, salt composition, acidity. Due to the high density of the medium, heat and light values ​​change much faster with the height gradient than on land.

Thermal regime. The aquatic environment is characterized by a lower heat input, because a significant part of it is reflected, and an equally significant part is spent on evaporation. Consistent with the dynamics of land temperatures, the water temperature has less fluctuations in daily and seasonal temperatures. Moreover, water bodies significantly equalize the course of temperatures in the atmosphere of coastal areas. In the absence of an ice shell, the sea in the cold season has a warming effect on the adjacent land areas, in summer it has a cooling and moisturizing effect.

The range of water temperatures in the World Ocean is 38° (from -2 to +36°C), in fresh water - 26° (from -0.9 to +25°C). The water temperature drops sharply with depth. Up to 50 m, daily temperature fluctuations are observed, up to 400 - seasonal, deeper it becomes constant, dropping to + 1-3 ° С (in the Arctic it is close to 0 ° С). Since the temperature regime in reservoirs is relatively stable, their inhabitants are characterized by stenothermy. Minor temperature fluctuations in one direction or another are accompanied by significant changes in aquatic ecosystems.

Examples: a “biological explosion” in the Volga delta due to a drop in the level of the Caspian Sea - the growth of lotus thickets (Nelumba kaspium), in southern Primorye - the overgrowth of calla oxbow rivers (Komarovka, Ilistaya, etc.) along the banks of which woody vegetation was cut down and burned.

Due to the different degree of heating of the upper and lower layers during the year, ebbs and flows, currents, storms, there is a constant mixing of the water layers. The role of water mixing for aquatic inhabitants (hydrobionts) is exceptionally great, because at the same time, the distribution of oxygen and nutrients inside the reservoirs is leveled, providing metabolic processes between organisms and the environment.

Light mode. The intensity of light in water is greatly attenuated due to its reflection by the surface and absorption by the water itself. This greatly affects the development of photosynthetic plants. The less transparent the water, the more light is absorbed. Water transparency is limited by mineral suspensions and plankton. It decreases with the rapid development of small organisms in summer, and in temperate and northern latitudes it also decreases in winter, after the establishment of an ice cover and covering it with snow from above.

In the oceans, where the water is very transparent, 1% of light radiation penetrates to a depth of 140 m, and in small lakes at a depth of 2 m, only tenths of a percent penetrate. Rays of different parts of the spectrum are absorbed differently in water, red rays are absorbed first. With depth it becomes darker, and the color of the water becomes green at first, then blue, blue and finally blue-violet, turning into complete darkness. Accordingly, hydrobionts also change color, adapting not only to the composition of light, but also to its lack - chromatic adaptation. In light zones, in shallow waters, green algae (Chlorophyta) predominate, the chlorophyll of which absorbs red rays, with depth they are replaced by brown (Phaephyta) and then red (Rhodophyta). Phytobenthos is absent at great depths.

Plants have adapted to the lack of light by developing large chromatophores, providing a low photosynthesis compensation point, as well as by increasing the area of ​​assimilating organs (leaf surface index). For deep-sea algae, strongly dissected leaves are typical, leaf blades are thin, translucent. For semi-submerged and floating plants, heterophylly is characteristic - the leaves above the water are the same as those of terrestrial plants, they have a whole plate, the stomatal apparatus is developed, and in the water the leaves are very thin, consist of narrow filiform lobes.

Heterophyllia: capsules, water lilies, arrowhead, chilim (water chestnut).

Animals, like plants, naturally change their color with depth. In the upper layers, they are brightly colored in different colors, in the twilight zone (sea bass, corals, crustaceans) are painted in colors with a red tint - it is more convenient to hide from enemies. Deep-sea species are devoid of pigments.

The characteristic properties of the aquatic environment, different from the land, are high density, mobility, acidity, the ability to dissolve gases and salts. For all these conditions, hydrobionts have historically developed appropriate adaptations.

2. Ground-air habitat

In the course of evolution, this environment was mastered later than the water. Its peculiarity lies in the fact that it is gaseous, therefore it is characterized by low humidity, density and pressure, high oxygen content. In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations.

Animals in the ground-air environment move through the soil or through the air (birds, insects), and plants take root in the soil. In this regard, animals developed lungs and tracheas, while plants developed a stomatal apparatus, i.e. organs by which the land inhabitants of the planet absorb oxygen directly from the air. The skeletal organs, which provide autonomy of movement on land and support the body with all its organs in conditions of low density of the medium, thousands of times less than water, have received a strong development. Environmental factors in the terrestrial-air environment differ from other habitats in high light intensity, significant fluctuations in air temperature and humidity, the correlation of all factors with geographical location, the change of seasons of the year and time of day. Their impact on organisms is inextricably linked with the movement of air and position relative to the seas and oceans and is very different from the impact in the aquatic environment (Table 1).

Living conditions of air and water organisms

(according to D. F. Mordukhai-Boltovsky, 1974)

Land animals and plants have developed their own, no less original adaptations to adverse environmental factors: the complex structure of the body and its integument, the frequency and rhythm of life cycles, thermoregulation mechanisms, etc. Purposeful animal mobility has developed in search of food, wind-borne spores, seeds and pollen of plants, as well as plants and animals, whose life is entirely connected with the air environment. An exceptionally close functional, resource and mechanical relationship with the soil has been formed.

Many of the adaptations we have discussed above as examples in the characterization of abiotic environmental factors. Therefore, it makes no sense to repeat now, because we will return to them in practical exercises