Abiotic factors of land-air habitat. Ground-air environment of life

And directly or indirectly affects its vital activity, growth, development, reproduction.

Each organism lives in a specific habitat. Elements or properties of the environment are called environmental factors. There are four environments of life on our planet: ground-air, water, soil, and other organisms. Living organisms are adapted to exist in certain living conditions and in a certain environment.

Some organisms live on land, others in soil, and others in water. Some chose the bodies of other organisms as their place of residence. Thus, four living environments are distinguished: ground-air, water, soil, other organism (Fig. 3). Each living environment is characterized by certain properties to which the organisms living in it are adapted.

Ground-air environment

The land-air environment is characterized by low air density, abundance of light, rapid temperature changes, and variable humidity. Therefore, organisms that live in the ground-air environment have well-developed supporting structures - the external or internal skeleton in animals, special structures in plants.

Many animals have organs of movement on the ground - limbs or wings for flight. Thanks to their developed visual organs, they see well. Land organisms have adaptations that protect them from fluctuations in temperature and humidity (for example, special body coverings, construction of nests, burrows). The plants have well-developed roots, stems, and leaves.

Water environment

The aquatic environment is characterized by a higher density compared to air, so water has a buoyant force. Many organisms “float” in the water column - small animals, bacteria, protists. Others are actively moving. To do this, they have locomotion organs in the form of fins or flippers (fish, whales, seals). Active swimmers, as a rule, have a streamlined body shape.

Many aquatic organisms (coastal plants, algae, coral polyps) lead an attached lifestyle, others are sedentary (some mollusks, starfish).

Water accumulates and retains heat, so there are no such sharp temperature fluctuations in water as on land. The amount of light in reservoirs varies depending on the depth. Therefore, autotrophs populate only that part of the reservoir where light penetrates. Heterotrophic organisms have mastered the entire water column.

Soil environment

There is no light in the soil environment, no sudden temperature changes, and high density. The soil is inhabited by bacteria, protists, fungi, and some animals (insects and their larvae, worms, moles, shrews). Soil animals have a compact body. Some of them have digging limbs, absent or underdeveloped organs of vision (mole).

The totality of environmental elements necessary for an organism, without which it cannot exist, is called the conditions of existence or living conditions.

On this page there is material on the following topics:

organisms of other organisms
habitat terrestrial aerial examples
examples of organisms bodies of living organisms
how does the environment affect the body?
characteristics of animals living in the body

Questions for this article:

What is habitat and living conditions?
What are called environmental factors?
What groups of environmental factors are distinguished?
What properties are characteristic of the ground-air environment?
Why is it believed that the land-air environment of life is more complex than the water or soil environment?
What are the characteristics of organisms living inside other organisms?

Lecture 3 HABITAT AND THEIR CHARACTERISTICS (2 hours)

1.Aquatic habitat

2. Ground-air habitat

3. Soil as a habitat

4.Organism 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 - ground-air - plants and animals arose on land and in the atmosphere and rapidly adapted to new conditions. Gradually transforming the upper layer of land - the lithosphere, they created a third habitat - soil, and themselves became the fourth habitat.

Aquatic habitat - hydrosphere

Ecological groups of hydrobionts. The warm seas and oceans (40,000 species of animals) in the equator and tropics are characterized by the greatest diversity of life; to the north and south, the flora and fauna of the seas are hundreds of times depleted. As for the distribution of organisms directly in the sea, the bulk of them are concentrated in the surface layers (epipelagic) and in the sublittoral zone. Depending on the method of movement and stay in certain layers, marine inhabitants are 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 includes amphibians and many insects.

Plankton(planktos - wandering, soaring) - a collection of plants (phytoplankton: diatoms, green and blue-green (fresh water bodies only) algae, plant flagellates, peridineans, etc.) and small animal organisms (zooplankton: small crustaceans, of the larger ones - pteropods mollusks, jellyfish, ctenophores, some worms) living at different depths, but not capable of active movement and resistance to currents. 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, move into the lower layers of the pelagel. Above the neuston there is a pleiston - these are organisms in which the upper part of the body grows above water, and the lower part in water (duckweed - Lemma, siphonophores, etc.). Plankton plays an important role in the trophic relationships of the biosphere, because is food for many aquatic inhabitants, including the main food for baleen whales (Myatcoceti).

Benthos(benthos – depth) – bottom hydrobionts. It is represented mainly by attached or slowly moving animals (zoobenthos: foraminephores, fish, sponges, coelenterates, worms, brachiopods, ascidians, etc.), more numerous in shallow water. In shallow water, benthos also includes plants (phytobenthos: diatoms, green, brown, red algae, bacteria). At depths where there is no light, phytobenthos is absent. Along the coasts there are flowering plants of zoster, rupiah. Rocky 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 lakes is formed by free-floating diatoms, green and blue-green algae; brown and red algae are absent.

Taking root coastal plants in lakes form clearly defined zones, the species composition and appearance of which are consistent with the environmental conditions in the land-water boundary zone. Hydrophytes grow in the water near the shore - plants semi-submerged in water (arrowhead, whitewing, reeds, cattails, sedges, trichaetes, reeds). They are replaced by hydatophytes - plants immersed in water, but with floating leaves (lotus, duckweed, egg capsules, chilim, takla) and - further - completely submerged (pondweed, 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 changes in life-supporting factors. Some of them are the same as on land - heat, light, others are specific: water pressure (increases with depth by 1 atm for every 10 m), oxygen content, salt composition, acidity. Due to the high density of the environment, the values of heat and light change much faster with an altitude gradient than on land.

Thermal mode. The aquatic environment is characterized by less heat gain, because a significant part of it is reflected, and an equally significant part is spent on evaporation. Consistent with the dynamics of land temperatures, water temperatures exhibit smaller fluctuations in daily and seasonal temperatures. Moreover, reservoirs significantly equalize the temperature in the atmosphere of coastal areas. In the absence of an ice shell, the seas have a warming effect on the adjacent land areas in the cold season, and a cooling and moistening effect in the summer.

The range of water temperatures in the World Ocean is 38° (from -2 to +36°C), in fresh water bodies – 26° (from -0.9 to +25°C). With depth, the water temperature drops sharply. Up to 50 m there are daily temperature fluctuations, up to 400 – seasonal, deeper it becomes constant, dropping to +1-3°C (in the Arctic it is close to 0°C). Since the temperature regime in reservoirs is relatively stable, their inhabitants are characterized by stenothermism. 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 decrease in the level of the Caspian Sea - the proliferation of lotus thickets (Nelumba kaspium), in southern Primorye - the overgrowth of whitefly in oxbow rivers (Komarovka, Ilistaya, etc.) along the banks of which woody vegetation was cut down and burned.

Due to varying degrees of heating of the upper and lower layers throughout the year, ebbs and flows, currents, and storms, constant mixing of water layers occurs. The role of water mixing for aquatic inhabitants (aquatic organisms) is extremely important, because at the same time, the distribution of oxygen and nutrients within reservoirs is equalized, ensuring metabolic processes between organisms and the environment.

In stagnant reservoirs (lakes) of temperate latitudes, vertical mixing takes place in spring and autumn, and during these seasons the temperature throughout the reservoir becomes uniform, i.e. comes homothermy. In summer and winter, as a result of a sharp increase in heating or cooling of the upper layers, the mixing of water stops. This phenomenon is called temperature dichotomy, and the period of temporary stagnation is called stagnation (summer or winter). In summer, lighter warm layers remain on the surface, located above heavy cold ones (Fig. 3). In winter, on the contrary, there is warmer water in the bottom layer, since directly under the ice the temperature of surface waters is less than +4°C and, due to the physicochemical properties of water, they become lighter than water with a temperature above +4°C.

During periods of stagnation, three layers are clearly distinguished: the upper (epilimnion) with the sharpest seasonal fluctuations in water temperature, the middle (metalimnion or thermocline), in which a sharp jump in temperature occurs, and the bottom (hypolimnion), in which the temperature changes little throughout the year. During periods of stagnation, oxygen deficiency occurs in the water column - in the bottom part in summer, and in the upper part in winter, as a result of which fish kills often occur in winter.

Light mode. The intensity of light in water is greatly weakened 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 even in winter, after the establishment of ice cover and covering it with snow on top.

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 penetrates. Rays from 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 first becomes green, then blue, indigo and finally blue-violet, turning into complete darkness. Hydrobionts also change color accordingly, 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). At great depths, phytobenthos is absent.

Plants have adapted to the lack of light by developing large chromatophores, which provide a low point of compensation for photosynthesis, as well as by increasing the area of assimilating organs (leaf surface index). For deep-sea algae, strongly dissected leaves are typical, the leaf blades are thin and translucent. Semi-submerged and floating plants are characterized by heterophylly - the leaves above the water are the same as those of land plants, they have a solid blade, the stomatal apparatus is developed, and in the water the leaves are very thin, consisting of narrow thread-like lobes.

Heterophylly: egg capsules, water lilies, arrow leaf, chilim (water chestnut).

The characteristic properties of the aquatic environment, different from land, are high density, mobility, acidity, and 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 developed later than the aquatic environment. Its peculiarity is that it is gaseous, therefore it is characterized by low humidity, density and pressure, and 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), and plants take root in the soil. In this regard, animals developed lungs and trachea, and plants developed a stomatal apparatus, i.e. organs with which the land inhabitants of the planet absorb oxygen directly from the air. Skeletal organs have developed strongly, ensuring autonomy of movement on land and supporting the body with all its organs in conditions of insignificant environmental density, thousands of times less than water. Ecological factors in the ground-air environment differ from other habitats in the high intensity of light, significant fluctuations in temperature and air humidity, the correlation of all factors with geographic location, changing seasons and time of day. Their effects on organisms are inextricably linked with air movement and position relative to the seas and oceans and are very different from the effects in the aquatic environment (Table 1).

Habitat conditions for air and water organisms

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

air environment

aquatic environment

Humidity	Very important (often in short supply)	Does not have (always in excess)
Density	Minor (except for soil)	Large compared to its role for the inhabitants of the air
Pressure	Almost none	Large (can reach 1000 atmospheres)
Temperature	Significant (varies within very wide limits - from -80 to +1ОО°С and more)	Less than the value for the inhabitants of the air (varies much less, usually from -2 to +40°C)
Oxygen	Non-essential (mostly in excess)	Essential (often in short supply)
Suspended solids	Unimportant; not used for food (mainly minerals)	Important (food source, especially organic matter)
Dissolved substances in the environment	To some extent (only relevant in soil solutions)	Important (certain quantities required)

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

Many of the adaptations were discussed above as examples in characterizing abiotic environmental factors. Therefore, there is no point in repeating ourselves now, since we will return to them in practical classes.

Lecture 2. HABITAT AND THEIR CHARACTERISTICS

Aquatic habitat

Water covers 71% of the earth's area. The bulk of water is concentrated in the seas and oceans - 94-98%, polar ice contains about 1.2% of water and a very small proportion - less than 0.5%, in fresh waters of rivers, lakes and swamps.

About 150,000 species of animals and 10,000 plants live in aquatic environments, representing only 7 and 8% of the total number of species on Earth, respectively.

In the seas-oceans, as in the mountains, vertical zoning is expressed. The pelagic - the entire water column - and the benthic - the bottom - differ especially greatly in ecology. The water column, the pelagic zone, is vertically divided into several zones: epipeligal, bathypeligal, abyssopeligal and ultraabyssopeligal(Fig. 2).

Depending on the steepness of the descent and the depth at the bottom, several zones are also distinguished, which correspond to the indicated pelagic zones:

Littoral - the edge of the coast that is flooded during high tides.

Supralittoral - the part of the coast above the upper tidal line where surf splashes reach.

Sublittoral - a gradual decrease in land up to 200m.

Bathial - a steep depression of land (continental slope),

Abyssal - a gradual decrease in the bottom of the ocean floor; the depth of both zones together reaches 3-6 km.

Ultra-abyssal - deep-sea depressions from 6 to 10 km.

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

Plankton (planktos - wandering, soaring) - a collection of plants (phytoplankton: diatoms, green and blue-green (fresh water bodies only) algae, plant flagellates, peridineans, etc.) and small animal organisms (zooplankton: small crustaceans, of the larger ones - pteropods mollusks, jellyfish, ctenophores, some worms) living at different depths, but not capable of active movement and resistance to currents. 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, move into the lower layers of the pelagel. Above the neuston is located plaiston - these are organisms in which the upper part of the body grows above water, and the lower part in water (duckweed - Lemma, siphonophores, etc.). Plankton plays an important role in the trophic relationships of the biosphere, because is food for many aquatic inhabitants, including the main food for baleen whales (Myatcoceti).

Benthos (benthos – depth) – bottom hydrobionts. It is represented mainly by attached or slowly moving animals (zoobenthos: foraminephores, fish, sponges, coelenterates, worms, mollusks, ascidians, etc.), more numerous in shallow water. In shallow water, benthos also includes plants (phytobenthos: diatoms, green, brown, red algae, bacteria). At depths where there is no light, phytobenthos is absent. Rocky areas of the bottom are richest in phytobenthos.

Thermal mode. The aquatic environment is characterized by less heat gain, because a significant part of it is reflected, and an equally significant part is spent on evaporation. Consistent with the dynamics of land temperatures, water temperatures exhibit smaller fluctuations in daily and seasonal temperatures. Moreover, reservoirs significantly equalize the temperature in the atmosphere of coastal areas. In the absence of an ice shell, the seas have a warming effect on the adjacent land areas in the cold season, and a cooling and moistening effect in the summer.

The range of water temperatures in the World Ocean is 38° (from -2 to +36°C), in fresh water bodies – 26° (from -0.9 to +25°C). With depth, the water temperature drops sharply. Up to 50 m there are daily temperature fluctuations, up to 400 – seasonal, deeper it becomes constant, dropping to +1-3°C. Since the temperature regime in reservoirs is relatively stable, their inhabitants tend to stenothermicity.

Due to varying degrees of heating of the upper and lower layers throughout the year, ebbs and flows, currents, and storms, constant mixing of water layers occurs. The role of water mixing for aquatic inhabitants is extremely important, because at the same time, the distribution of oxygen and nutrients within reservoirs is equalized, ensuring metabolic processes between organisms and the environment.

In stagnant reservoirs (lakes) of temperate latitudes, vertical mixing takes place in spring and autumn, and during these seasons the temperature throughout the reservoir becomes uniform, i.e. comes homothermy. In summer and winter, as a result of a sharp increase in heating or cooling of the upper layers, the mixing of water stops. This phenomenon is called temperature dichotomy, and the period of temporary stagnation is stagnation(summer or winter). In summer, lighter warm layers remain on the surface, located above heavy cold ones (Fig. 3). In winter, on the contrary, there is warmer water in the bottom layer, since directly under the ice the temperature of surface waters is less than +4°C and, due to the physicochemical properties of water, they become lighter than water with a temperature above +4°C.

During periods of stagnation, three layers are clearly distinguished: the upper (epilimnion) with the most dramatic seasonal fluctuations in water temperature, the middle (metalimnion or thermocline), in which there is a sharp jump in temperature, and bottom ( hypolimnion), in which the temperature varies little throughout the year. During periods of stagnation, oxygen deficiency occurs in the water column - in the bottom part in summer, and in the upper part in winter, as a result of which fish kills often occur in winter.

The absorption of light is stronger, the lower the transparency of the water, which depends on the number of particles suspended in it (mineral suspensions, plankton). It decreases with the rapid development of small organisms in summer, and in temperate and northern latitudes even in winter, after the establishment of ice cover and covering it with snow on top.

Transparency is characterized by the maximum depth at which a specially lowered white disk with a diameter of about 20 cm (Secchi disk) is still visible. The clearest waters are in the Sargasso Sea: the disk is visible to a depth of 66.5 m. In the Pacific Ocean, the Secchi disk is visible up to 59 m, in the Indian Ocean - up to 50, in shallow seas - up to 5-15 m. The transparency of rivers is on average 1-1.5 m, and in the muddiest rivers only a few centimeters.

Plants adapted to the lack of light by developing large chromatophores, as well as increasing the area of assimilating organs (leaf surface index). For deep-sea algae, strongly dissected leaves are typical, the leaf blades are thin and translucent. Semi-submerged and floating plants are characterized by heterophylly - the leaves above the water are the same as those of land plants, they have a solid blade, the stomatal apparatus is developed, and in the water the leaves are very thin, consisting of narrow thread-like lobes.

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) they are painted in colors with a red tint - it is more convenient to hide from enemies. Deep-sea species lack pigments. In the dark depths of the ocean, organisms use light emitted by living beings as a source of visual information. bioluminescence.

High density(1 g/cm3, which is 800 times the density of air) and water viscosity ( 55 times higher than that of air) led to the development of special adaptations of aquatic organisms :

1) Plants have very poorly developed or completely absent mechanical tissues - they are supported by water itself. Most are characterized by buoyancy due to air-carrying intercellular cavities. Characterized by active vegetative reproduction, the development of hydrochory - the removal of flower stalks above the water and the distribution of pollen, seeds and spores by surface currents.

2) In animals living in the water column and actively swimming, the body has a streamlined shape and is lubricated with mucus, which reduces friction when moving. Developed devices to increase buoyancy: accumulations of fat in tissues, swim bladders in fish, air cavities in siphonophores. In passively swimming animals, the specific surface area of the body increases due to outgrowths, spines, and appendages; the body is flattened, and skeletal organs are reduced. Different methods of locomotion: bending of the body, with the help of flagella, cilia, jet mode of locomotion (cephalopods).

In benthic animals, the skeleton disappears or is poorly developed, body size increases, vision reduction is common, and tactile organs develop.

Currents. A characteristic feature of the aquatic environment is mobility. It is caused by ebbs and flows, sea currents, storms, and different levels of elevations of river beds. Adaptations of hydrobionts:

1) In flowing reservoirs, plants are firmly attached to stationary underwater objects. The bottom surface is primarily a substrate for them. These are green and diatom algae, water mosses. Mosses even form a dense cover on fast riffles of rivers. In the tidal zone of the seas, many animals have devices for attaching to the bottom (gastropods, barnacles), or hide in crevices.

2) In fish of running waters, the body is round in diameter, and in fish that live near the bottom, as in benthic invertebrate animals, the body is flat. Many have attachment organs to underwater objects on the ventral side.

Salinity of water.

Natural bodies of water have a certain chemical composition. Carbonates, sulfates, and chlorides predominate. In fresh water bodies, the salt concentration is no more than 0.5 ‰ (and about 80% are carbonates), in the seas - from 12 to 35 ‰ (mainly chlorides and sulfates). When the salinity is more than 40 ppm, the water body is called hypersaline or oversaline.

1) In fresh water (hypotonic environment), osmoregulation processes are well expressed. Hydrobionts are forced to constantly remove water penetrating into them; they are homoyosmotic (ciliates “pump” through themselves an amount of water equal to its weight every 2-3 minutes). In salt water (isotonic environment), the concentration of salts in the bodies and tissues of hydrobionts is the same (isotonic) with the concentration of salts dissolved in water - they are poikiloosmotic. Therefore, the inhabitants of salt water bodies do not have developed osmoregulatory functions, and they were unable to populate fresh water bodies.

2) Aquatic plants are able to absorb water and nutrients from water - “broth”, with their entire surface, therefore their leaves are strongly dissected and conductive tissues and roots are poorly developed. The roots serve mainly for attachment to the underwater substrate. Most freshwater plants have roots.

Typically marine and typically freshwater species, stenohaline, do not tolerate significant changes in water salinity. There are few euryhaline species. They are common in brackish waters (freshwater pike perch, pike, bream, mullet, coastal salmon).

Composition of gases in water.

In water, oxygen is the most important environmental factor. In oxygen-saturated water, its content does not exceed 10 ml per 1 liter, which is 21 times lower than in the atmosphere. When water is mixed, especially in flowing reservoirs, and as the temperature decreases, the oxygen content increases. Some fish are very sensitive to oxygen deficiency (trout, minnow, grayling) and therefore prefer cold mountain rivers and streams. Other fish (crucian carp, carp, roach) are unpretentious to oxygen content and can live at the bottom of deep reservoirs. Many aquatic insects, mosquito larvae, and pulmonate molluscs are also tolerant of the oxygen content in water, because they rise to the surface from time to time and swallow fresh air.

There is enough carbon dioxide in water (40-50 cm 3 /l - almost 150 times more than in air. It is used in photosynthesis of plants and goes to the formation of calcareous skeletal formations of animals (mollusk shells, crustacean integuments, radiolarian frames, etc.) .

Acidity. In freshwater bodies of water, the acidity of water, or the concentration of hydrogen ions, varies much more than in sea waters - from pH = 3.7-4.7 (acidic) to pH = 7.8 (alkaline). The acidity of water is largely determined by the species composition of aquatic plants. In the acidic waters of swamps, sphagnum mosses grow and shell rhizomes live in abundance, but there are no toothless mollusks (Unio), and other mollusks are rarely found. Many types of pondweed and elodea develop in an alkaline environment. Most freshwater fish live in a pH range of 5 to 9 and die off in large numbers outside these values. The most productive waters are with a pH of 6.5-8.5.

The acidity of sea water decreases with depth.

Acidity can serve as an indicator of the overall metabolic rate of a community. Waters with low pH contain few nutrients, so productivity is extremely low.

Hydrostatic pressure in the ocean is of great importance. With immersion in water of 10 m, the pressure increases by 1 atmosphere. In the deepest part of the ocean, pressure reaches 1000 atmospheres. Many animals are able to tolerate sudden fluctuations in pressure, especially if they do not have free air in their bodies. Otherwise, gas embolism may develop. High pressures, characteristic of great depths, as a rule, inhibit vital processes.

Based on the amount of organic matter available to hydrobionts, water bodies can be divided into: - oligotrophic (blue and transparent) – not rich in food, deep, cold; - eutrophic (green) – rich in food, warm; dystrophic (brown) - poor in food, acidic due to the presence of large amounts of humic acids in the soil.

Eutrophication– enrichment of reservoirs with organic nutrients under the influence of anthropogenic factors (for example, wastewater discharge).

Ecological plasticity of hydrobionts. Freshwater plants and animals are ecologically more plastic (eurythermal, euryhaline) than marine ones; inhabitants of coastal zones are more plastic (eurythermal) than deep-sea ones. There are species that have narrow ecological plasticity in relation to one factor (lotus is a stenothermic species, brine shrimp (Artimia solina) is stenothermic) and broad – in relation to others. Organisms are more plastic in relation to those factors that are more variable. And they are the ones that are more widespread (elodea, rhizomes of Cyphoderia ampulla). Plasticity also depends on age and phase of development.

Sound travels faster in water than in air. Sound orientation is generally better developed in aquatic organisms than visual orientation. A number of species even detect very low frequency vibrations (infrasounds) that occur when the rhythm of the waves changes. A number of aquatic organisms search for food and orient themselves using echolocation—the perception of reflected sound waves (cetaceans). Many perceive reflected electrical impulses, producing discharges of different frequencies while swimming.

The most ancient method of orientation, characteristic of all aquatic animals, is the perception of the chemistry of the environment. The chemoreceptors of many aquatic organisms are extremely sensitive.

Ground-air habitat

In the course of evolution, this environment was developed later than the aquatic environment. Ecological factors in the ground-air environment differ from other habitats in the high intensity of light, significant fluctuations in temperature and air humidity, the correlation of all factors with geographic location, changing seasons and time of day. The environment is gaseous, therefore it is characterized by low humidity, density and pressure, and high oxygen content.

Characteristics of abiotic environmental factors: light, temperature, humidity - see 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.

Currently, 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 quantities. Of particular importance for biota is the relative content of oxygen and carbon dioxide.

The high oxygen content contributed to an increase in metabolism in terrestrial organisms compared to primary aquatic ones. It was in a terrestrial environment, based on the high efficiency of oxidative processes in the body, that animal homeothermy 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 deficiency created, for example in accumulations of decomposing plant residues, reserves of grain, flour, etc.

The carbon dioxide content can vary in certain areas of the surface layer of air within fairly significant limits. For example, in the absence of wind in the center of large cities, its concentration increases tens of times. There are regular daily changes in the carbon dioxide content in the surface layers, associated with the rhythm of plant photosynthesis, and seasonal changes, caused by changes in the respiration rate of living organisms, mainly the microscopic population of soils. Increased saturation of air with carbon dioxide occurs in areas of volcanic activity, near thermal springs and other underground outlets of this gas. Low carbon dioxide content inhibits the process of photosynthesis. In closed ground conditions, it is possible to increase the rate of photosynthesis by increasing the concentration of carbon dioxide; This is used in the practice of greenhouse and greenhouse farming.

Air nitrogen is an inert gas for most inhabitants of the terrestrial environment, but 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 pollutants entering the air can also significantly affect living organisms. This especially applies to toxic gaseous substances - methane, sulfur oxide (IV), carbon monoxide (II), nitrogen oxide (IV), hydrogen sulfide, chlorine compounds, as well as dust particles, soot, etc., clogging 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. Sulfur oxide (SO 2), for example, is toxic to plants even in concentrations from one fifty-thousandth to one millionth of the volume of air. Some plant species are particularly sensitive to S0 2 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 support. Inhabitants of the air environment must have their own support system that supports the body: plants - with various mechanical tissues, animals - with a solid or, much less often, hydrostatic skeleton. In addition, all inhabitants of the air are closely connected with the surface of the earth, which serves them for attachment and support. 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 - reproduction - is carried out on the surface of the earth. For most of them, staying in the air is associated only with settling or searching for prey.

Wind has a limiting effect on the activity and even distribution of organisms. The wind can even change the appearance of plants, especially in those habitats, for example in alpine zones, where other factors have a limiting effect. In open mountain habitats, wind limits plant growth and causes plants to bend on the windward side. In addition, wind increases evapotranspiration in low humidity conditions. Are of great importance storms, although their effect is purely local. Hurricanes, and even ordinary winds, can transport animals and plants over long distances and thereby change the composition of communities.

Pressure, apparently, is not a direct limiting factor, but it is directly related to weather and climate, which have a direct limiting effect. Low air density causes relatively low pressure on land. Normally it is 760 mmHg. 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 respiration rate. The limits of advancement of higher plants into the mountains are approximately the same. Somewhat more hardy are arthropods (springtails, mites, spiders), which can be found on glaciers above the vegetation line.

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

Ground-air habitat

BASIC LIVING ENVIRONMENTS

WATER ENVIRONMENT

The aquatic environment of life (hydrosphere) occupies 71% of the globe's area. More than 98% of the water is concentrated in the seas and oceans, 1.24% is the ice of the polar regions, 0.45% is the fresh water of rivers, lakes, and swamps.

There are two ecological areas in the world's oceans:

water column - pelagic, and the bottom - benthal.

The aquatic environment is home to approximately 150,000 species of animals, or about 7% of their total number, and 10,000 species of plants – 8%. The following are distinguished: ecological groups of aquatic organisms. Pelagial - inhabited by organisms divided into nekton and plankton.

Nekton (nektos - floating) - This is a collection of pelagic actively moving animals that do not have a direct connection with the bottom. These are mainly large animals that can overcome long distances and strong water currents. They are characterized by a streamlined body shape and well-developed organs of movement (fish, squid, pinnipeds, whales). In fresh waters, in addition to fish, nekton includes amphibians and actively moving insects.

Plankton (wandering, floating) - This is a set of pelagic organisms that do not have the ability for rapid active movements. They are divided into phyto- and zooplankton (small crustaceans, protozoa - foraminifera, radiolarians; jellyfish, pteropods). Phytoplankton – diatoms and green algae.

Neuston– a set of organisms that inhabit the surface film of water at the border with the air. These are the larvae of decapods, barnacles, copepods, gastropods and bivalves, echinoderms, and fish. Passing through the larval stage, they leave the surface layer, which served them as a refuge, and move to live on the bottom or pelagic zone.

Plaiston – this is a collection of organisms, part of the body of which is above the surface of the water, and the other in the water - duckweed, siphonophores.

Benthos (depth) - a collection of organisms that live at the bottom of water bodies. It is divided into phytobenthos and zoobenthos. Phytobenthos - algae - diatoms, green, brown, red and bacteria; along the coasts there are flowering plants - zoster, ruppia. Zoobenthos – foraminifera, sponges, coelenterates, worms, mollusks, fish.

In the life of aquatic organisms, an important role is played by the vertical movement of water, density, temperature, light, salt, gas (oxygen and carbon dioxide content) regimes, and the concentration of hydrogen ions (pH).

Temperature: It differs in water, firstly, by less heat influx, and secondly, by greater stability than on land. Part of the thermal energy arriving at the surface of the water is reflected, while part is spent on evaporation. The evaporation of water from the surface of reservoirs, which consumes about 2263.8 J/g, prevents overheating of the lower layers, and the formation of ice, which releases the heat of fusion (333.48 J/g), slows down their cooling. Temperature changes in flowing waters follow its changes in the surrounding air, differing in smaller amplitude.

In lakes and ponds of temperate latitudes, the thermal regime is determined by a well-known physical phenomenon - water has a maximum density at 4 o C. The water in them is clearly divided into three layers:

1. epilimnion- the upper layer whose temperature experiences sharp seasonal fluctuations;

2. metalimnion– transitional layer of temperature jump, there is a sharp temperature difference;

3. hypolimnion- a deep-sea layer reaching to the very bottom, where the temperature changes slightly throughout the year.

In summer, the warmest layers of water are located at the surface, and the coldest ones are located at the bottom. This type of layer-by-layer temperature distribution in a reservoir is called direct stratification. In winter, as the temperature drops, reverse stratification: the surface layer has a temperature close to 0 C, at the bottom the temperature is about 4 C, which corresponds to its maximum density. Thus, the temperature increases with depth. This phenomenon is called temperature dichotomy, observed in most lakes in the temperate zone in summer and winter. As a result of temperature dichotomy, vertical circulation is disrupted - a period of temporary stagnation begins - stagnation.

In spring, surface water, due to heating to 4C, becomes denser and sinks deeper, and warmer water rises from the depths to take its place. As a result of such vertical circulation, homothermy occurs in the reservoir, i.e. for some time the temperature of the entire water mass equalizes. With a further increase in temperature, the upper layers become less and less dense and no longer sink down - summer stagnation. In autumn, the surface layer cools, becomes denser and sinks deeper, displacing warmer water to the surface. This occurs before the onset of autumn homothermy. When surface waters cool below 4C, they become less dense and again remain on the surface. As a result, water circulation stops and winter stagnation occurs.

Water is characterized by significant density(800 times) superior to air) and viscosity. IN On average, in the water column, for every 10 m of depth, pressure increases by 1 atm. These features affect plants in the fact that their mechanical tissue develops very weakly or not at all, so their stems are very elastic and bend easily. Most aquatic plants are characterized by buoyancy and the ability to be suspended in the water column; in many aquatic animals, the integument is lubricated with mucus, which reduces friction when moving, and the body takes on a streamlined shape. Many inhabitants are relatively stenobatic and confined to certain depths.

Transparency and light mode. This especially affects the distribution of plants: in muddy water bodies they live only in the surface layer. The light regime is also determined by the natural decrease in light with depth due to the fact that water absorbs sunlight. At the same time, rays with different wavelengths are absorbed differently: red ones are absorbed most quickly, while blue-green ones penetrate to significant depths. The color of the environment changes, gradually moving from greenish to green, blue, indigo, blue-violet, replaced by constant darkness. Accordingly, with depth, green algae are replaced by brown and red ones, the pigments of which are adapted to capture solar rays of different wavelengths. The color of animals also naturally changes with depth. Brightly and variously colored animals live in the surface layers of water, while deep-sea species are devoid of pigments. The twilight habitat is inhabited by animals painted in colors with a reddish tint, which helps them hide from enemies, since the red color in blue-violet rays is perceived as black.

The absorption of light in water is stronger, the lower its transparency. Transparency is characterized by extreme depth, where a specially lowered Secchi disk (a white disk with a diameter of 20 cm) is still visible. Hence, the boundaries of photosynthesis zones vary greatly in different bodies of water. In the cleanest waters, the photosynthetic zone reaches a depth of 200 m.

Salinity of water. Water is an excellent solvent for many mineral compounds. As a result, natural reservoirs have a certain chemical composition. The most important are sulfates, carbonates, and chlorides. The amount of dissolved salts per 1 liter of water in fresh water bodies does not exceed 0.5 g, in seas and oceans - 35 g. Freshwater plants and animals live in a hypotonic environment, i.e. an environment in which the concentration of dissolved substances is lower than in body fluids and tissues. Due to the difference in osmotic pressure outside and inside the body, water constantly penetrates into the body, and freshwater hydrobionts are forced to intensively remove it. In this regard, their osmoregulation processes are well expressed. In protozoa this is achieved by the work of excretory vacuoles, in multicellular organisms - by removing water through the excretory system. Typically marine and typically freshwater species do not tolerate significant changes in water salinity - stenohaline organisms. Eurygalline - freshwater pike perch, bream, pike, from the sea - the mullet family.

Gas mode The main gases in the aquatic environment are oxygen and carbon dioxide.

Oxygen- the most important environmental factor. It enters water from the air and is released by plants during photosynthesis. Its content in water is inversely proportional to temperature; with decreasing temperature, the solubility of oxygen in water (as well as other gases) increases. In layers heavily populated by animals and bacteria, oxygen deficiency may occur due to increased oxygen consumption. Thus, in the world’s oceans, life-rich depths from 50 to 1000 m are characterized by a sharp deterioration in aeration. It is 7-10 times lower than in surface waters inhabited by phytoplankton. Conditions near the bottom of reservoirs can be close to anaerobic.

Carbon dioxide - dissolves in water about 35 times better than oxygen and its concentration in water is 700 times higher than in the atmosphere. Provides photosynthesis of aquatic plants and participates in the formation of calcareous skeletal formations of invertebrate animals.

Hydrogen ion concentration (pH)– freshwater pools with pH = 3.7-4.7 are considered acidic, 6.95-7.3 – neutral, with pH 7.8 – alkaline. In fresh water bodies, pH even experiences daily fluctuations. Sea water is more alkaline and its pH changes much less than fresh water. pH decreases with depth. The concentration of hydrogen ions plays a large role in the distribution of aquatic organisms.

Ground-air habitat

A feature of the land-air environment of life is that the organisms living here are surrounded by a gaseous environment characterized by low humidity, density and pressure, and high oxygen content. Typically, animals in this environment move on the soil (hard substrate) and plants take root in it.

In the ground-air environment, the operating environmental factors have a number of characteristic features: higher light intensity compared to other environments, significant temperature fluctuations, changes in humidity depending on the geographical location, season and time of day. The impact of the factors listed above is inextricably linked with the movement of air masses - wind.

In the process of evolution, living organisms of the land-air environment have developed characteristic anatomical, morphological, physiological adaptations.

Let us consider the features of the impact of basic environmental factors on plants and animals in the ground-air environment.

Air. Air as an environmental factor is characterized by a constant composition - oxygen in it is usually about 21%, carbon dioxide 0.03%.

Low air density determines its low lifting force and insignificant support. All inhabitants of the air are closely connected with the surface of the earth, which serves them for attachment and support. The density of the air environment does not provide high resistance to organisms when they move along the surface of the earth, but it makes it difficult to move vertically. For most organisms, staying in the air is associated only with settling or searching for prey.

The low lifting force of air determines the maximum mass and size of terrestrial organisms. The largest animals living on the surface of the earth are smaller than the giants of the aquatic environment. Large mammals (the size and mass of a modern whale) could not live on land, as they would be crushed by their own weight.

Low air density creates little resistance to movement. The ecological benefits of this property of the air environment were used by many land animals during evolution, acquiring the ability to fly. 75% of the species of all terrestrial animals are capable of active flight, mainly insects and birds, but flyers are also found among mammals and reptiles.

Thanks to the mobility of air and the vertical and horizontal movements of air masses existing in the lower layers of the atmosphere, passive flight of a number of organisms is possible. Many species have developed anemochory - dispersal with the help of air currents. Anemochory is characteristic of spores, seeds and fruits of plants, protozoan cysts, small insects, spiders, etc. Organisms passively transported by air currents are collectively called aeroplankton by analogy with planktonic inhabitants of the aquatic environment.

The main ecological role of horizontal air movements (winds) is indirect in enhancing and weakening the impact on terrestrial organisms of such important environmental factors as temperature and humidity. Winds increase the release of moisture and heat from animals and plants.

Gas composition of air in the ground layer the air is quite homogeneous (oxygen - 20.9%, nitrogen - 78.1%, inert gases - 1%, carbon dioxide - 0.03% by volume) due to its high diffusivity and constant mixing by convection and wind flows. However, various impurities of gaseous, droplet-liquid and solid (dust) particles entering the atmosphere from local sources can have significant environmental significance.

The high oxygen content contributed to an increase in metabolism in terrestrial organisms, and animal homeothermy arose on the basis of the high efficiency of oxidative processes. 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 deficiency created, for example in accumulations of decomposing plant residues, reserves of grain, flour, etc.

Edaphic factors. Soil properties and terrain also affect the living conditions of terrestrial organisms, primarily plants. The properties of the earth's surface that have an ecological impact on its inhabitants are called edaphic environmental factors.

The nature of the plant root system depends on the hydrothermal regime, aeration, composition, composition and structure of the soil. For example, the root systems of tree species (birch, larch) in areas with permafrost are located at shallow depths and spread out wide. Where there is no permafrost, the root systems of these same plants are less widespread and penetrate deeper. In many steppe plants, the roots can reach water from great depths; at the same time, they also have many surface roots in the humus-rich soil horizon, from where the plants absorb elements of mineral nutrition.

The terrain and the nature of the soil affect the specific movement of animals. For example, ungulates, ostriches, and bustards living in open spaces need hard ground to enhance repulsion when running fast. In lizards that live on shifting sands, the toes are edged with a fringe of horny scales, which increases the surface of support. For terrestrial inhabitants that dig holes, dense soils are unfavorable. The nature of the soil in some cases influences the distribution of terrestrial animals that dig burrows, burrow into the soil to escape heat or predators, or lay eggs in the soil, etc.

Weather and climatic features. Living conditions in the ground-air environment are also complicated by weather changes. Weather is the continuously changing state of the atmosphere at the earth's surface, up to an altitude of approximately 20 km (the boundary of the troposphere). Weather variability is manifested in a constant variation in the combination of environmental factors such as air temperature and humidity, cloudiness, precipitation, wind strength and direction, etc. Weather changes, along with their regular alternation in the annual cycle, are characterized by non-periodic fluctuations, which significantly complicates the conditions for the existence of terrestrial organisms. The weather affects the life of aquatic inhabitants to a much lesser extent and only on the population of the surface layers.

Climate of the area. The long-term weather regime characterizes the climate of the area. The concept of climate includes not only the average values of meteorological phenomena, but also their annual and daily cycle, deviations from it and their frequency. The climate is determined by the geographical conditions of the area.

The zonal diversity of climates is complicated by the action of monsoon winds, the distribution of cyclones and anticyclones, the influence of mountain ranges on the movement of air masses, the degree of distance from the ocean and many other local factors.

For most terrestrial organisms, especially small ones, it is not so much the climate of the area that is important as the conditions of their immediate habitat. Very often, local environmental elements (relief, vegetation, etc.) change the regime of temperature, humidity, light, air movement in a particular area in such a way that it differs significantly from the climatic conditions of the area. Such local climate modifications that develop in the surface layer of air are called microclimate. Each zone has very diverse microclimates. Microclimates of arbitrarily small areas can be identified. For example, a special regime is created in the corollas of flowers, which is used by the inhabitants living there. A special stable microclimate occurs in burrows, nests, hollows, caves and other closed places.

Precipitation. In addition to providing water and creating moisture reserves, they can play other ecological roles. Thus, heavy rainfall or hail sometimes have a mechanical effect on plants or animals.

The ecological role of snow cover is especially diverse. Daily temperature fluctuations penetrate into the snow depth only up to 25 cm; deeper the temperature remains almost unchanged. With frosts of -20-30 C under a layer of snow of 30-40 cm, the temperature is only slightly below zero. Deep snow cover protects renewal buds and protects green parts of plants from freezing; many species go under the snow without shedding their foliage, for example, hairy grass, Veronica officinalis, etc.

Small land animals lead an active lifestyle in winter, making entire galleries of tunnels under the snow and in its thickness. A number of species that feed on snow-covered vegetation are even characterized by winter reproduction, which is noted, for example, in lemmings, wood and yellow-throated mice, a number of voles, water rats, etc. Grouse birds - hazel grouse, black grouse, tundra partridge - burrow in the snow for the night.

Winter snow cover makes it difficult for large animals to obtain food. Many ungulates (reindeer, wild boars, musk oxen) feed exclusively on snow-covered vegetation in winter, and deep snow cover, and especially the hard crust on its surface that occurs during icy conditions, doom them to starvation. Snow depth may limit the geographic distribution of species. For example, real deer do not penetrate north into those areas where the snow thickness in winter is more than 40-50 cm.

Light mode. The amount of radiation reaching the Earth's surface is determined by the geographic latitude of the area, the length of the day, the transparency of the atmosphere and the angle of incidence of the sun's rays. Under different weather conditions, 42-70% of the solar constant reaches the Earth's surface. Illumination on the Earth's surface varies widely. It all depends on the height of the Sun above the horizon or the angle of incidence of the sun's rays, the length of the day and weather conditions, and the transparency of the atmosphere. Light intensity also fluctuates depending on the season and time of day. In certain regions of the Earth, the quality of light is also unequal, for example, the ratio of long-wave (red) and short-wave (blue and ultraviolet) rays. Short-wave rays are known to be absorbed and scattered by the atmosphere more than long-wave rays.

A NEW LOOK Adaptations of organisms to living in the ground-air environmentLiving organisms in ground-air environment surrounded by air. Air has low density and, as a result, 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 just as quickly. The speed of this process is inversely related to the amount of water vapor contained in it.

Light air masses have greater mobility, both horizontally and vertically. This helps maintain a constant 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 terrestrial habitats, due to the high transparency of the atmosphere, does not act as a limiting factor, unlike the aquatic environment.

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

Moisture on land acts as a limiting factor.

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

Low air resistance contributed to the progressive evolution of locomotion systems of terrestrial animals. Thus, mammals acquired the highest speed of movement on land, and birds mastered the air environment, developing the ability to fly.

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

The adaptations of terrestrial organisms to conserve moisture are also diverse. In insects, the body is reliably protected from drying out by a multilayered chitinized cuticle, the outer layer of which contains fats and wax-like substances. Similar water-saving devices 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 etc. - the soil is more or less permeated with cavities filled with a mixture of gases and aqueous solutions. In the soil, compared to the ground 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 underneath contains washed out from the top layer and transformed substances. The bottom layer is represented maternal breed.

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

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

organs with which the land inhabitants of the planet absorb oxygen directly from the air. Skeletal organs have developed strongly, ensuring autonomy of movement on land and supporting the body with all its organs in conditions of insignificant environmental density, thousands of times less than water.

Ecological factors in the ground-air environment differ from other habitats in the high intensity of light, significant fluctuations in temperature and air humidity, the correlation of all factors with geographic location, changing seasons and time of day.

Their effects on organisms are inextricably linked with air movement and position relative to the seas and oceans and are very different from the effects in the aquatic environment (Table

Table 5

Habitat conditions for air and water organisms

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

air environment

aquatic environment

Humidity	Very important (often in short supply)	Does not have (always in excess)
Density	Minor (except for soil)	Large compared to its role for the inhabitants of the air
Pressure	Almost none	Large (can reach 1000 atmospheres)
Temperature	Significant (varies within very wide limits - from -80 to +1ОО°С and more)	Less than the value for the inhabitants of the air (varies much less, usually from -2 to +40°C)
Oxygen	Non-essential (mostly in excess)	Essential (often in short supply)
Suspended solids	Unimportant; not used for food (mainly minerals)	Important (food source, especially organic matter)
Dissolved substances in the environment	To some extent (only relevant in soil solutions)	Important (certain quantities required)

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

Many of the adaptations were discussed above as examples in characterizing abiotic environmental factors.

Therefore, there is no point in repeating ourselves now, since we will return to them in practical classes.

Soil as a habitat

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

This shell was formed in historically foreseeable time - it is the same age as land life on the planet. For the first time, M.V. answered the question about the origin of soil. Lomonosov (“On the Layers of the Earth”): “...soil originated from the decay of animal and plant bodies...through 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 total, mutual activity of the climate of a given area, its plant and animal organisms, topography and age of the country..., finally, subsoil, i.e.

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

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

Kaczynski (“Soil, its properties and life”, 1975) gives the following definition of soil: “Soil must be understood as all surface layers of rocks, processed and changed by the joint influence of climate (light, heat, air, water), plant and animal organisms” .

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

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

Skeletal particle sizes range from boulders and stones to tiny grains of sand and mud particles. The physicochemical properties of soils are determined mainly by the composition of soil-forming 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 and the size of the fragments.

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

In this case, the soils are not at risk of either waterlogging or drying out. Both are equally destructive for 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.

Simpler elements formed as a result of the decomposition of organic matter are again absorbed 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 filling of pores 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, and the decomposition of organic matter is slow. Gradually accumulating, they form peat. Large reserves of peat are typical for swamps, swampy forests, and tundra communities. Peat accumulation is especially pronounced in the northern regions, where coldness and waterlogging of soils are interdependent and complement each other.

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

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

Easily absorbed by plants.

Hygroscopic or related– adsorbs 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 temperatures (102-105°C). It is inaccessible to plants and does not evaporate. In clay soils there is up to 15% of such water, in sandy soils – 5%.

Capillary– held around soil particles by surface tension.

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

Plants easily absorb it.

Vaporous– occupies all water-free pores. It 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 a terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homeothermy 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 deficiency created, for example in accumulations of decomposing plant residues, reserves of grain, flour, etc.

For example, in the absence of wind in the center of large cities, its concentration increases tens of times. There are regular daily changes in the carbon dioxide content in the ground layers, associated with the rhythm of plant photosynthesis, and seasonal changes, caused by changes in the respiration rate of living organisms, mainly the microscopic population of soils. Increased saturation of air with carbon dioxide occurs in areas of volcanic activity, near thermal springs and other underground outlets of this gas.

Low air density determines its low lifting force and insignificant support.

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

Wind

storms

Pressure

Low air density causes relatively low pressure on land. Normally it is 760 mmHg. 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 respiration rate.

The limits of advancement of higher plants into the mountains are approximately the same. Somewhat more hardy are arthropods (springtails, mites, spiders), which can be found on glaciers above the vegetation line.

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

Ground-air habitat

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

Characteristics of abiotic environmental factors: light, temperature, humidity - see previous lecture.

Currently, 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 quantities. Of particular importance for biota is the relative content of oxygen and carbon dioxide.

Only in places, under specific conditions, is a temporary deficiency created, for example in accumulations of decomposing plant residues, reserves of grain, flour, etc.

The carbon dioxide content can vary in certain areas of the surface layer of air within quite significant limits. For example, in the absence of wind in the center of large cities, its concentration increases tens of times. There are regular daily changes in the carbon dioxide content in the ground layers, associated with the rhythm of plant photosynthesis, and seasonal changes, caused by changes in the respiration rate of living organisms, mainly the microscopic population of soils.

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

In closed ground conditions, it is possible to increase the rate of photosynthesis by increasing the concentration of carbon dioxide; this is used in the practice of greenhouse and greenhouse farming.

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

This especially applies to 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 in concentrations from one fifty-thousandth to one millionth of the volume of air. Some plant species are especially sensitive to S02 and serve as a sensitive indicator of its accumulation in the air (for example , lichens.

In addition, all inhabitants of the air 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, staying in the air is associated only with settling or searching for prey.

In addition, wind increases evapotranspiration in low humidity conditions. Are of great importance storms, although their effect is purely local. Hurricanes, and even ordinary winds, can transport animals and plants over long distances and thereby change the composition of communities.

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

Low air density causes relatively low pressure on land. Normally it is 760 mmHg. 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 respiration rate. The limits of advancement of higher plants into the mountains are approximately the same. Somewhat more hardy are arthropods (springtails, mites, spiders), which can be found on glaciers above the vegetation line.

Abiotic factors of land-air habitat. Ground-air environment of life

Ground-air environment

Water environment

Soil environment

organisms of other organisms

habitat terrestrial aerial examples

examples of organisms bodies of living organisms

how does the environment affect the body?

characteristics of animals living in the body

What is habitat and living conditions?

What are called environmental factors?

What groups of environmental factors are distinguished?

What properties are characteristic of the ground-air environment?

Why is it believed that the land-air environment of life is more complex than the water or soil environment?

What are the characteristics of organisms living inside other organisms?

2. Ground-air habitat

Ground-air habitat

Ground-air habitat