What animals are terrestrial air. Ground-air environment of life, its characteristics and forms of adaptation to it

A distinctive feature of the ground-air environment is the presence of air (a mixture of various gases) in it.

Air has a low density, so it cannot act as a support for organisms (with the exception of flying ones). It is the low density of air that determines its insignificant resistance when organisms move along the soil surface. At the same time, it makes it difficult to move them in the vertical direction. The low air density also determines the low pressure on land (760 mm Hg = 1 atm). Air, smaller than water, blocks the penetration of sunlight. It has a higher transparency than water.

The gas composition of the air is constant (you know about this from the geography course). Oxygen and carbon dioxide, as a rule, are not limiting factors. Water vapor and various pollutants are present as impurities in the air.

Over the past century, as a result of human activities in the atmosphere, the content of various pollutants has sharply increased. Among them, the most dangerous are: nitrogen and sulfur oxides, ammonia, formaldehyde, heavy metals, hydrocarbons, etc. Living organisms are practically not adapted to them. For this reason, air pollution is a serious global environmental problem. Its solution requires the implementation of environmental measures at the level of all states of the Earth.

Air masses move in horizontal and vertical directions. This leads to the emergence of such an environmental factor as wind. Wind can cause shifting of sands in deserts (sandstorms). It is able to blow out soil particles on any terrain, reducing land fertility (wind erosion). Wind has a mechanical effect on plants. It is capable of causing windblows (reversing of trees with roots), windbreaks (fractures of tree trunks), deformation of the tree crown. The movement of air masses significantly affects the distribution of precipitation and temperature regime in the ground-air environment.

Water regime of the ground-air environment

From the course of geography, you know that the ground-air environment can be both extremely saturated with moisture (tropics) and very poor in it (deserts). Precipitation is unevenly distributed both seasonally and geographically. Humidity in the environment fluctuates over a wide range. It is the main limiting factor for living organisms.

Temperature regime of the ground-air environment

The temperature in the ground-air environment has a daily and seasonal periodicity. Organisms have adapted to it since the emergence of life on land. Therefore, temperature is less likely than humidity to act as a limiting factor.

Adaptations of plants and animals to life in the ground-air environment

With the release of plants on land, they developed tissues. You studied the structure of plant tissues in the 7th grade biology course. Due to the fact that air cannot serve as a reliable support, mechanical tissues (wood and bast fibers) arose in plants. A wide range of changes in climatic factors caused the formation of dense integumentary tissues - periderm, crust. Due to the mobility of air (wind), plants have developed adaptations for pollination, the spread of spores, fruits and seeds.

The life of animals in suspension in the air is impossible due to its low density. Many of the species (insects, birds) have adapted to active flight and can stay in the air for a long time. But their reproduction occurs on the surface of the soil.

The movement of air masses in horizontal and vertical directions is used by some small organisms for passive settlement. In this way, protists, spiders, and insects settle. The low air density caused the improvement in animals in the process of evolution of the external (arthropods) and internal (vertebral) skeletons. For the same reason, there is a limitation of the maximum mass and size of the body of terrestrial animals. The largest land animal, the elephant (weight up to 5 tons), is much smaller than the sea giant, the blue whale (up to 150 tons). Thanks to the emergence different types limbs, mammals were able to populate areas of land that are diverse in nature.

General characteristics of the soil as a living environment

The soil - upper layer the earth's crust, possessing fertility. It was formed as a result of the interaction of climatic and biological factors with the underlying rock (sand, clay, etc.). The soil is in contact with air environment and acts as a support for terrestrial organisms. It is also a source of mineral nutrition for plants. At the same time, soil is a living environment for many types of organisms. The soil is characterized by the following properties: density, humidity, temperature, aeration (air supply), environmental reaction (pH), salinity.

Soil density increases with depth. Humidity, temperature and soil aeration are closely interconnected and interdependent. Temperature fluctuations in the soil are smoothed compared to the surface air and are no longer traced at a depth of 1-1.5 m. Well-moistened soils warm up slowly and cool down slowly. An increase in soil moisture and temperature worsens its aeration, and vice versa. The hydrothermal regime of the soil and its aeration depend on the structure of the soil. Clay soils are more water-retaining than sandy soils. But they are less aerated and warm up worse. According to the reaction of the environment, soils are divided into three types: acidic (pH< 7,0), нейтральные (рН ≈ 7,0) и щелочные (рН > 7,0).

Adaptations of plants and animals to life in the soil

The soil in the life of plants performs the functions of fixing, water supply, and a source of mineral nutrition. The concentration of nutrients in the soil has led to the development of root systems and conductive tissues in plants.

Animals living in the soil have a number of adaptations. They are characterized different ways movement in the soil. It can be digging moves and holes, like a bear and a mole. Earthworms can push apart soil particles and make passages. Insect larvae are able to crawl among soil particles. In this regard, in the process of evolution, appropriate adaptations have been developed. Digging organisms developed digging limbs. Annelids have a hydrostatic skeleton, while insects and centipedes have claws.

Soil animals have a short compact body with non-wetting covers (mammals) or covered with mucus. Life in the soil as a habitat has led to atrophy or underdevelopment of the organs of vision. The mole has tiny, underdeveloped eyes often hidden under a fold of skin. To facilitate movement in narrow soil passages, mole wool acquired the ability to fit in two directions.

In the ground-air environment, organisms are surrounded by air. It has low humidity, density and pressure, high transparency and oxygen content. Humidity is the main limiting factor. The soil as a living environment is characterized by high density, a certain hydrothermal regime, and aeration. Plants and animals have developed a variety of adaptations to life in the ground-air and soil environments.

Any habitat is a complex system that is distinguished by its unique set of abiotic and biotic factors, which, in fact, form this environment. Evolutionarily, the ground-air environment arose later than the water one, which is associated with chemical transformations of the composition atmospheric air. Most of the organisms with a nucleus live in the terrestrial environment, which is associated with a wide variety of natural zones, physical, anthropogenic, geographical and other determining factors.

Characteristics of the ground-air environment

This environment is made up of upper layers soil ( up to 2 km deep) and lower atmosphere ( up to 10 km). The environment is very diverse different forms life. Among the invertebrates, one can note: insects, a few species of worms and mollusks, of course, vertebrates predominate. The high oxygen content in the air led to an evolutionary change in the respiratory system and the presence of a more intense metabolism.

The atmosphere has insufficient and often variable humidity, which often limits the spread of living organisms. In regions with high temperatures and low humidity, eukaryotes develop various idioadaptations, the purpose of which is to maintain the vital water level (transformation of plant leaves into needles, accumulation of fat in camel humps).

Terrestrial animals are characterized by the phenomenon photoperiodism thus most animals are only active during the day or only at night. Also, the terrestrial environment is characterized by a significant amplitude of fluctuations in temperature, humidity and light intensity. The change in these factors is associated with geographical location, change of seasons, time of day. Due to the low density and pressure of the atmosphere, muscle and bone tissue has developed and become more complex.

Vertebrates have developed complex limbs adapted to support the body and move along a solid substrate in conditions of low atmospheric density. Plants have a progressive root system, which allows them to fix themselves in the soil and transport substances to a considerable height. Also, terrestrial plants have developed mechanical, basic tissues, phloem and xylem. Most plants have adaptations that protect them from excessive transpiration.

The soil

Although the soil is classified as a terrestrial-air habitat, it is very different from the atmosphere in its physical properties:

• High density and pressure.
• Insufficient amount of oxygen.
• Low amplitude of temperature fluctuations.
• Low light intensity.

In this regard, the underground inhabitants have their own adaptations, distinguishable from terrestrial animals.

aquatic habitat

An environment that includes the entire hydrosphere, both saline and fresh water bodies. This environment is characterized by less variety of life and its own special conditions. It is inhabited by small invertebrates that form plankton, cartilaginous and bony fish, worms, mollusks, and a few species of mammals.

Oxygen concentration is highly dependent on depth. In places where the atmosphere and hydrosphere come into contact, there is much more oxygen and light than at depth. High pressure, which at great depths is 1000 times higher than atmospheric pressure, determines the shape of the body of most underwater inhabitants. The amplitude of temperature change is small, since the heat transfer of water is much lower than that of the earth's surface.

Differences between the water and ground-air environment

As already mentioned, the main distinguishing features of different habitats are determined by abiotic factors. The land-air environment is characterized by high biological diversity, high oxygen concentration, variable temperature and humidity, which are the main limiting factors for the settlement of animals and plants. Biological rhythms depend on the length of daylight hours, the season and the natural-climatic zone. In the aquatic environment, most nutrient organic substances are located in the water column or on its surface, only a small proportion is located at the bottom; in the terrestrial-air environment, all organic substances are located on the surface.

Land dwellers are different the best development sensor systems and nervous system in general, the musculoskeletal, circulatory and respiratory system. The skin covers are very different, because they are functionally different. Under water, lower plants (algae) are common, which in most cases do not have real organs, for example, rhizoids serve as attachment organs. The spread of aquatic inhabitants is often associated with warm undercurrents. Along with the differences between these habitats, there are animals that have adapted to live in both. These animals include Amphibians.

In the course of its historical development 4 habitats were mastered by living beings: water, ground-air, soil and other organisms. Each of them has characteristics, and it is impossible to say which is more important. Let's get acquainted with the features of the ground-air habitat.

Definition

The land-air habitat is the biological habitat of organisms located on the land surface and in low atmospheric layers.

It cannot be called the first of those mastered by living organisms, since life originated in the sea. In the course of evolutionary development, creatures developed certain adaptations that made it possible for them to move to land and into the atmosphere.

Peculiarities

The most important of ecological niches is the ground-air environment. The features of the environment are:

• gaseousness;
• high oxygen content;
• low humidity;
• pressure and density.

This forms the conditions in which organisms are forced to live. Also, the essential features of the ground-air habitat are the change of seasons and seasons, temperature fluctuations, the specifics of daylight hours, and the wind. To live here, living organisms had to change their anatomy, physiology and behavior, which helped them to adapt. The most important (essential) environmental factors include:

• humidity;
• temperature.

Other factors have a much lesser effect on living organisms. These are pressure and density.

How have the animals adapted?

Many of the animal species known to science live precisely in the ground-air environment. Features of the environment forced them to develop several types of adaptation:

• Having lungs gives them the ability to breathe air.
• To move on land, the skeleton was developed.

In order to exist normally in the conditions of the ground-air environment that are familiar to us, representatives of the fauna had to go through a long evolution and develop a wide range of adaptive mechanisms.

How have plants adapted?

Most plants grow in the ground-air environment. Features of the environment led to the emergence of the following adaptation mechanisms:

• The presence of roots, thanks to which plants receive minerals and moisture from the soil.
• Thanks to stomata, representatives of the flora were able to absorb oxygen directly from the air.

Often, plants have to survive in conditions of insufficient moisture, so the flora of deserts and savannahs has developed its own methods of adaptation: a long main root grows deep into the soil, extracting moisture from underground sources. Small hard leaves reduce evaporation.

What other features of plant adaptation to the ground-air environment are distinguished by researchers?

Grow in the tundra dwarf trees and shrubs, the height of which rarely exceeds human height. The conditions here are very severe: a long winter (frosts for more than 7 months a year), a short cool summer. Strong winds and soil that is so frozen that it does not have time to thaw in summer - these are the features of the environment. And plants have learned to survive in them. Some species can survive snowfall in the flowering state, others are distinguished by small leaves, which avoids evaporation of moisture.

The influence of environmental factors on the characteristics of the inhabitants

So, the essential features of the ground-air environment had an impact on the structure and appearance inhabitants. Information on how this or that factor affected the flora and fauna is presented in the table.

Interaction of living organisms and the environment

	Effect on plants	Impact on animals
Air density	Appearance of roots and mechanical tissues	The formation of a dense skeleton and the development of muscles, the ability of many species to fly
	Complication of metabolic processes	Ability to use the lungs and trachea
edaphic environmental factors (relief and soil composition)	The root system depends on the characteristics of the soil	The shape of the hooves depends on whether the animal is running or jumping.
	Trees shed their leaves for the winter	Animals have become warm-blooded, in the northern regions they have thick fur, molt in spring

As you can see, there are a lot of environmental factors that have a significant impact on the life of its inhabitants. Therefore, a considerable number of adaptation mechanisms have been developed.

Edaphic factors

Consider how other plant and animal organisms have adapted to the characteristics of the soil and relief. First of all, the root system of many plants has changed:

• Trees growing in permafrost have a branched root system that does not go deep. These are larch, birch, spruce. If these same species are in a milder climate, then their roots penetrate deeper into the soil.
• Representatives of the flora growing in arid conditions have a long root that can get moisture from the depths.
• If the soil is excessively wet, then the plants form pneumatophores - respiratory roots.

The soil may have different composition, therefore, specific species are able to grow on one or another type of soil:

• Nitrogen-rich soils prefer nitrophils, such as shepherd's purse, nettle, wheatgrass quinoa, henbane.
• Salty soils like halophytes (twisted quinoa, beets, wormwood).
• Petrophytes (lithophytes) grow on rocky areas. These are saxifrages, junipers, pines, bluebells.
• Loose sands are fertile soil for psammophytes: saxauls, sandy acacias, willows.

So, the composition of the soil affects the plants. For animals, the nature of the soil and relief are most important. So, for ungulates, solid ground is needed, allowing them to push off while running and jumping. However, dense ground is inconvenient for burrowing animals, as it prevents them from building shelters.

Animals also adapted well to the edaphic factors of the ground-air environment. First of all, in those species that have to run a lot, powerful light limbs have developed, in others developed hind legs and short front legs make it possible to jump, such are hares and kangaroos.

Flight adaptation

Birds are one of the main inhabitants of the ground-air environment. Features of the environment led to the emergence of the following forms of adaptation:

• streamlined body shape;
• hollow bones help reduce the weight of the "flyer";
• wings help to stay in the air;
• not only birds, but also some animals have the ability to fly thanks to special membranes.

All these features help the representatives of the fauna to take off and stay in the air.

Adaptation of organisms to changing environmental factors

The main features of the ground-air environment may change. So, in the middle lane, snow falls in winter, and heat is in summer. That is why living organisms often have to adapt to changing living conditions. Such adaptation mechanisms have also developed in the process of evolution.

So, plants can develop only in favorable conditions, with sufficient light and moisture. That is why their growing season is spring and summer. In winter, there is a period of rest. The nutrients necessary for survival are accumulated in the roots over the summer, and the leaves of the trees are shed, since the reduction of daylight hours leads to the impossibility of the formation of nutrients in the leaves.

Animals have also developed many ways to adapt to changing environmental conditions:

• Some fall into hibernation, having previously accumulated the necessary supply of nutrients (bears).
• With the onset of cold weather, migratory birds go to hot countries in order to return to their nests in the spring and start hatching chicks.
• By winter, many inhabitants of the northern latitudes form a dense undercoat, thanks to which the animal can easily endure severe frosts. In the spring the animal molts.

Thanks to such mechanisms, it becomes clear how representatives of the plant and animal world adapt to the ground-air environment of life. The features of the environment are subject to change, so both the appearance and the behavior of its inhabitants change. All these mechanisms are the result of a long evolutionary development.

We have considered the essential features of one of the main habitats - ground-air. All living organisms that live on the surface of the soil or in the lower layers of the atmosphere have learned to adapt to the changing features of the environment.

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 the 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)

Living conditions (factors)		Significance 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			Has almost no	Large (can reach 1000 atmospheres)
Temperature			Significant (fluctuates within very wide limits - from -80 to + 100 ° С and more)	Less than the value for the inhabitants of the air (fluctuates much less, usually from -2 to + 40 ° C)
Oxygen			Minor (mostly in excess)	Essential (often in short supply)
suspended solids			unimportant; not used for food (mainly mineral)	Important (food source, especially organic matter)
Solutes in the environment			To some extent (only relevant in soil solutions)	Important (in a certain amount needed)

Land animals and plants have developed their own, no less original adaptations to adverse environmental factors: the complex structure of the body and its integument, the frequency and rhythm of life cycles, thermoregulation mechanisms, etc. Purposeful 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, parent) rock as a result of its weathering. Sizes of skeletal particles: from boulders and stones to the smallest grains of sand and silt particles. The physicochemical properties of soils are mainly determined by the composition of parent rocks.

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

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

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

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

Gravity- mobile water, occupy wide gaps between soil particles, seeps down under its own weight to the level ground water. 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 held 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, and 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 it is obvious closest connection climate, soil, animal and plant organisms ... ". 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.



In the ground-air environment, especially big influence temperature affects organisms. Therefore, the inhabitants of the cold and hot regions of the Earth have developed various adaptations to conserve heat or, conversely, to release its excess.

Give some examples.

The temperature of the plant due to heating by the sun's rays may be higher than the temperature of the surrounding air and soil. With strong evaporation, the temperature of the plant becomes lower than the air temperature. Evaporation through stomata is a process regulated by the plant. With an increase in air temperature, it increases if it is possible to quickly supply the required amount of water to the leaves. This saves the plant from overheating, lowering its temperature by 4-6, and sometimes by 10-15 ° C.

During muscle contraction, much more thermal energy is released than during the functioning of any other organs and tissues. The more powerful and active the musculature, the more heat the animal can generate. Compared with plants, animals have more diverse possibilities to regulate, permanently or temporarily, their own body temperature.

By changing the posture, the animal can increase or decrease the heating of the body due to solar radiation. For example, desert locust in cool morning hours exposes the wide lateral surface of the body to the sun's rays, and at noon - the narrow dorsal surface. In extreme heat, animals hide in the shade, hide in burrows. In the desert during the day, for example, some species of lizards and snakes climb the bushes, avoiding contact with the hot surface of the soil. By winter, many animals seek refuge, where the course of temperatures is smoother compared to open places habitat. The forms of behavior of social insects are even more complex: bees, ants, termites, which build nests with a well-regulated temperature inside them, almost constant during the period of insect activity.

The thick fur of mammals, feathers and especially the down cover of birds make it possible to keep a layer of air around the body with a temperature close to that of the animal's body, and thereby reduce heat radiation to the external environment. Heat transfer is regulated by the slope of the hair and feathers, the seasonal change of fur and plumage. The exceptionally warm winter fur of animals from the Arctic allows them to do without an increase in metabolism in cold weather and reduces the need for food.

Name the inhabitants of the desert known to you.

In the deserts of Central Asia, a small shrub is a saxaul. In America - cacti, in Africa - euphorbia. The animal world is not rich. Reptiles predominate - snakes, monitor lizards. There are scorpions, few mammals (camel).

1. Continue filling out the table "Habitats of living organisms" (see homework for § 42).