What organisms live in the terrestrial air environment. Ecological features of the ground-air habitat

Ground-air environment - a medium consisting of air, which explains its name. It is usually characterized by the following:

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

In the course of evolution, this environment was developed later than the aquatic one. Its peculiarity is that it gaseous, therefore characterized by low:

• humidity,
• density and pressure,
• high oxygen content.

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

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

• high light intensity,
• significant fluctuations in air temperature and humidity,
• correlation of all factors with geographical location,
• changing seasons of the year and time of day.

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

Adaptations of organisms to life in conditions of different temperatures and humidity. More adaptations of organisms in the land-air environment are associated with air temperature and humidity. Animals of the steppe (scorpion, tarantula and karakurt spiders, gophers, vole mice) hide from the heat in minks. Animals cope with heat by secreting sweat.

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

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

Adaptation of organisms to movement in the land-air environment. For many animals in the land-air environment, movement on the earth's surface or in the air is important. To do this, they have developed certain adaptations, and their limbs have different structures. Some have adapted to running (wolf, horse), others to jumping (kangaroo, jerboa, horse), and others to flying (birds, bats, insects). Snakes and vipers have no limbs at all, so they move by arching their body.

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

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

Walking through a forest or meadow, you hardly think that you are... in ground-air environment. But this is exactly what scientists call the house for living beings, which is formed by the surface of the earth and the air. Swimming in a river, lake or sea, you find yourself in aquatic environment- another richly populated natural home. And when you help adults dig up the soil in the garden, you see the soil environment under your feet. There are also many, many diverse residents here. Yes, there are three wonderful houses around us - three habitat, with which the fate of the majority of organisms inhabiting our planet is inextricably linked.

Life in each environment has its own characteristics. IN ground-air environment there is enough oxygen, but often there is not enough moisture. There is especially little of it in the steppes and deserts. Therefore, plants and animals of arid places have special adaptations for obtaining, storing and economically using water. Just remember a cactus that stores moisture in its body. There are significant temperature changes in the land-air environment, especially in areas with cold winters. In these areas, the entire life of organisms changes noticeably throughout the year. Autumn leaf fall, the departure of migratory birds to warmer regions, the change of fur of animals to thicker and warmer ones - all these are adaptations of living beings to seasonal changes in nature.

For animals living in any environment, movement is an important problem. In the ground-air environment, you can move on the ground and in the air. And animals take advantage of this. The legs of some are adapted for running (ostrich, cheetah, zebra), others - for jumping (kangaroo, jerboa). Of every hundred animal species living in this environment, 75 can fly. These are most insects, birds and some animals (bats).

IN aquatic environment something, and there is always enough water. The temperature here varies less than the air temperature. But oxygen is often not enough. Some organisms, such as trout fish, can only live in oxygen-rich water. Others (carp, crucian carp, tench) can withstand a lack of oxygen. In winter, when many reservoirs are covered with ice, fish may die - mass death from suffocation. To allow oxygen to penetrate the water, holes are cut in the ice.

There is less light in the aquatic environment than in the air-terrestrial environment. In the oceans and seas at a depth below 200 m - the kingdom of twilight, and even lower - eternal darkness. It is clear that aquatic plants are found only where there is enough light. Only animals can live deeper. They feed on the dead remains of various marine inhabitants that “fall” from the upper layers.

The most noticeable feature of many aquatic animals is their swimming adaptations. Fish, dolphins and whales have fins. Walruses and seals have flippers. Beavers, otters, waterfowl, and frogs have membranes between their toes. Swimming beetles have swimming legs that look like oars.

Soil environment- home to many bacteria and protozoa. Mushroom myceliums and plant roots are also located here. The soil was also inhabited by a variety of animals - worms, insects, animals adapted to digging, such as moles. The inhabitants of the soil find in this environment the conditions they need - air, water, mineral salts. True, there is less oxygen and more carbon dioxide here than in the fresh air. And sometimes there is too much water. But the temperature is more even than on the surface. But light does not penetrate deep into the soil. Therefore, the animals inhabiting it usually have very small eyes or no visual organs at all. Their sense of smell and touch helps.

Ground-air environment

Representatives of different habitats “met” in these drawings. In nature, they could not get together, because many of them live far from each other, on different continents, in the seas, in fresh water...

The champion in flight speed among birds is the swift. 120 km per hour is his usual speed.

Hummingbirds flap their wings up to 70 times per second, mosquitoes - up to 600 times per second.

The flight speed of different insects is as follows: for the lacewing - 2 km per hour, for the housefly - 7, for the cockchafer - 11, for the bumblebee - 18, and for the hawk moth - 54 km per hour. Large dragonflies, according to some observations, reach speeds of up to 90 km per hour.

Our bats are small in stature. But their relatives, fruit bats, live in hot countries. They reach a wingspan of 170 cm!

Large kangaroos make jumps of up to 9 and sometimes up to 12 m. (Measure this distance on the floor in the classroom and imagine a kangaroo jump. It’s simply breathtaking!)

The cheetah is the fastest-footed of animals. It reaches speeds of up to 110 km per hour. An ostrich can run at speeds of up to 70 km per hour, taking steps of 4-5 m.

Water environment

Fish and crayfish breathe through gills. These are special organs that extract dissolved oxygen from water. A frog breathes through its skin while underwater. But animals that have mastered the aquatic environment breathe with their lungs, rising to the surface of the water to inhale. Aquatic beetles behave in a similar way. Only they, like other insects, do not have lungs, but special breathing tubes - tracheas.

Soil environment

The body structure of the mole, zokor and mole rat suggests that they are all inhabitants of the soil environment. The front legs of the mole and zokor are the main tool for digging. They are flat, like shovels, with very large claws. But the mole rat has ordinary legs; it bites into the soil with its powerful front teeth (to prevent soil from getting into the mouth, the lips close it behind the teeth!). The body of all these animals is oval and compact. With such a body it is convenient to move through underground passages.

Test your knowledge

1. List the habitats you were introduced to in class.
2. What are the living conditions of organisms in the ground-air environment?
3. Describe the living conditions in the aquatic environment.
4. What are the characteristics of soil as a habitat?
5. Give examples of the adaptation of organisms to life in different environments.

Think!

1. Explain what is shown in the picture. In what environments do you think the animals whose body parts are shown in the picture live? Can you name these animals?
2. Why do only animals live in the ocean at great depths?

There are ground-air, water and soil habitats. Each organism is adapted to life in a certain environment.

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

In the ground-air environment, the operating environmental factors have a number of characteristic features: higher light intensity compared to other environments, significant temperature fluctuations, changes in humidity depending on the geographical location, season and time of day (Table 3).

Table 3

Living conditions for organisms in the air and water environment (according to D.F. Mordukhai-Boltovsky, 1974)

The impact of the above factors is inextricably linked with the movement of air masses - wind. In the process of evolution, living organisms of the land-air environment have developed characteristic anatomical, morphological, physiological, behavioral and other adaptations. For example, organs have appeared that provide direct absorption of atmospheric oxygen during respiration (the lungs and trachea of ​​animals, the stomata of plants). Skeletal formations (animal skeleton, mechanical and supporting tissues of plants) have received strong development, which support the body in conditions of low environmental density. Adaptations have been developed to protect against unfavorable factors, such as the periodicity and rhythm of life cycles, the complex structure of the integument, mechanisms of thermoregulation, etc. A close connection with the soil has formed (animal limbs, plant roots), the mobility of animals in search of food has developed, and air currents have appeared. seeds, fruits and pollen of plants, flying animals.

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

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

The low lifting force of air determines the maximum mass and size of terrestrial organisms. The largest animals on the surface of the earth are smaller than the giants of the aquatic environment. Large mammals (the size and mass of a modern whale) could not live on land, as they would be crushed by their own weight. Giant Mesozoic dinosaurs led a semi-aquatic lifestyle. Another example: tall, erect redwood plants (Sequoja sempervirens), reaching 100 m, have powerful supporting wood, while in the thalli of the giant brown algae Macrocystis, growing up to 50 m, the mechanical elements are only very weakly isolated in the core part of the thallus.

Low air density creates little resistance to movement. The ecological benefits of this property of the air environment were used by many land animals during evolution, acquiring the ability to fly. 75% of all species of land animals are capable of active flight. These are mostly insects and birds, but there are also mammals and reptiles. Land animals fly mainly with the help of muscular efforts. Some animals can glide using air currents.

Due to the mobility of air, which exists in the lower layers of the atmosphere, vertical and horizontal movement of air masses, passive flight of certain types of organisms is possible, developed anemochory -- dispersal by air currents. Organisms passively transported by air currents are collectively called aeroplankton, by analogy with planktonic inhabitants of the aquatic environment. For passive flight along N.M. Chernova, A.M. Bylova (1988) organisms have special adaptations - small body size, an increase in its area due to outgrowths, strong dismemberment, a large relative surface of the wings, the use of a web, etc.

Anemochorous seeds and fruits of plants also have very small sizes (for example, fireweed seeds) or various wing-shaped (maple Acer pseudoplatanum) and parachute-shaped (dandelion Taraxacum officinale) appendages

Wind-pollinated plants have a number of adaptations that improve the aerodynamic properties of pollen. Their floral integument is usually reduced and the anthers are not protected from the wind in any way.

In the dispersal of plants, animals and microorganisms, the main role is played by vertical conventional air flows and weak winds. Storms and hurricanes also have a significant environmental impact on terrestrial organisms. Quite often, strong winds, especially blowing in one direction, bend tree branches and trunks to the leeward side and cause the formation of flag-shaped crowns.

In areas where strong winds constantly blow, the species composition of small flying animals is usually poor, since they are not able to resist powerful air currents. Thus, a honey bee flies only when the wind force is up to 7 - 8 m/s, and aphids fly only when the wind is very weak, not exceeding 2.2 m/s. Animals in these places develop dense integuments that protect the body from cooling and loss of moisture. On oceanic islands with constant strong winds, birds and especially insects predominate, having lost the ability to fly, they lack wings, since those who are able to rise into the air are blown out to sea by the wind and die.

The wind causes a change in the intensity of transpiration in plants and is especially pronounced during dry winds, which dry out the air and can lead to the death of plants. The main ecological role of horizontal air movements (winds) is indirect and consists in strengthening or weakening the impact on terrestrial organisms of such important environmental factors as temperature and humidity. Winds increase the release of moisture and heat from animals and plants.

When there is wind, heat is easier to bear and frost is more difficult, and desiccation and cooling of organisms occurs faster.

Terrestrial organisms exist in conditions of relatively low pressure, which is caused by low air density. In general, terrestrial organisms are more stenobatic than aquatic ones, because normal pressure fluctuations in their environment amount to fractions of the atmosphere, and for those that rise to high altitudes, for example, birds, do not exceed 1/3 of normal.

Gas composition of air, as already discussed earlier, in the ground layer of the atmosphere it is quite homogeneous (oxygen - 20.9%, nitrogen - 78.1%, m.g. gases - 1%, carbon dioxide - 0.03% by volume) due to its high diffusion capacity and constant mixing by convection and wind flows. At the same time, various impurities of gaseous, droplet-liquid, dust (solid) particles entering the atmosphere from local sources often have significant environmental significance.

Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment. The high oxygen content contributed to an increase in metabolism in terrestrial organisms, and animal homeothermy arose on the basis of the high efficiency of oxidative processes. Only in places, under specific conditions, is a temporary oxygen deficiency created, for example, in decomposing plant debris, grain reserves, flour, etc.

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

There are regular daily changes in the content of carbon dioxide in the ground layers, determined by the rhythm of plant photosynthesis (Fig. 17).

Rice. 17. Daily changes in the vertical profile of CO 2 concentration in forest air (from W. Larcher, 1978)

Using the example of daily changes in the vertical profile of CO 2 concentration in forest air, it is shown that during the day, at the level of tree crowns, carbon dioxide is spent on photosynthesis, and in the absence of wind, a zone poor in CO 2 (305 ppm) is formed here, into which CO comes from the atmosphere and soil (soil respiration). At night, a stable air stratification is established with an increased concentration of CO 2 in the soil layer. Seasonal fluctuations in carbon dioxide are associated with changes in the respiration rate of living organisms, mostly soil microorganisms.

In high concentrations, carbon dioxide is toxic, but such concentrations are rare in nature. Low CO 2 content inhibits the process of photosynthesis. To increase the rate of photosynthesis in the practice of greenhouse and greenhouse farming (in closed ground conditions), the concentration of carbon dioxide is often artificially increased.

For most inhabitants of the terrestrial environment, air nitrogen is an inert gas, but microorganisms such as nodule bacteria, azotobacteria, and clostridia have the ability to bind it and involve it in the biological cycle.

The main modern source of physical and chemical pollution of the atmosphere is anthropogenic: industrial and transport enterprises, soil erosion, etc. Thus, sulfur dioxide is toxic to plants in concentrations from one fifty-thousandth to one millionth of the volume of air. Lichens die when there are traces of sulfur dioxide in the environment. Therefore, plants that are particularly sensitive to SO 2 are often used as indicators of its content in the air. Common spruce and pine, maple, linden, and birch are sensitive to smoke.

Light mode. The amount of radiation reaching the Earth's surface is determined by the geographic latitude of the area, the length of the day, the transparency of the atmosphere and the angle of incidence of the sun's rays. Under different weather conditions, 42-70% of the solar constant reaches the Earth's surface. Passing through the atmosphere, solar radiation undergoes a number of changes not only in quantity, but also in composition. Short-wave radiation is absorbed by the ozone shield and oxygen in the air. Infrared rays are absorbed in the atmosphere by water vapor and carbon dioxide. The rest reaches the Earth's surface in the form of direct or diffuse radiation.

The combination of direct and diffuse solar radiation makes up from 7 to 7„ of the total radiation, while on cloudy days the diffuse radiation is 100%. At high latitudes, diffuse radiation predominates, while in the tropics, direct radiation predominates. Scattered radiation contains up to 80% of yellow-red rays at noon, direct radiation - from 30 to 40%. On clear sunny days, solar radiation reaching the Earth's surface consists of 45% visible light (380 - 720 nm) and 45% infrared radiation. Only 10% comes from ultraviolet radiation. The radiation regime is significantly influenced by atmospheric dust. Due to its pollution, in some cities the illumination may be 15% or less of the illumination outside the city.

Illumination on the Earth's surface varies widely. It all depends on the height of the Sun above the horizon or the angle of incidence of the sun’s rays, the length of the day and weather conditions, and the transparency of the atmosphere (Fig. 18).

Rice. 18. Distribution of solar radiation depending on the height of the Sun above the horizon (A 1 - high, A 2 - low)

Depending on the season and time of day, the light intensity also fluctuates. In certain regions of the Earth, the quality of light is also unequal, for example, the ratio of long-wave (red) and short-wave (blue and ultraviolet) rays. Short-wave rays are known to be absorbed and scattered by the atmosphere more than long-wave rays. In mountainous areas there is therefore always more short-wave solar radiation.

Trees, shrubs, and plant crops shade the area and create a special microclimate, weakening radiation (Fig. 19).

Rice. 19.

A - in a rare pine forest; B - in corn crops Of the incoming photosynthetically active radiation, 6-12% is reflected (R) from the surface of the planting

Thus, in different habitats, not only the intensity of radiation differs, but also its spectral composition, the duration of illumination of plants, the spatial and temporal distribution of light of different intensities, etc. Accordingly, the adaptations of organisms to life in a terrestrial environment under one or another light regime are also varied. . As we noted earlier, in relation to light there are three main groups of plants: photophilous(heliophytes), shade-loving(sciophytes) and shade-tolerant. Light-loving and shade-loving plants differ in the position of their ecological optimum.

In light-loving plants it is located in the area of ​​full sunlight. Strong shading has a depressing effect on them. These are plants of open areas of land or well-lit steppe and meadow grasses (the upper tier of the grass stand), rock lichens, early spring herbaceous plants of deciduous forests, most cultivated plants of open ground and weeds, etc. Shade-loving plants have an optimum in the area of ​​low light and cannot tolerate strong light. These are mainly the lower shaded layers of complex plant communities, where shading is the result of the “interception” of light by taller plants and co-inhabitants. This includes many indoor and greenhouse plants. For the most part, these come from the herbaceous cover or epiphyte flora of tropical forests.

The ecological curve of the relationship to light in shade-tolerant plants is somewhat asymmetrical, since they grow and develop better in full light, but adapt well to low light. They are a common and highly flexible group of plants in terrestrial environments.

Plants in the terrestrial-air environment have developed adaptations to various light conditions: anatomical-morphological, physiological, etc.

A clear example of anatomical and morphological adaptations is a change in appearance in different light conditions, for example, the unequal size of leaf blades in plants related in systematic position, but living in different lighting (meadow bell - Campanula patula and forest - C. trachelium, field violet -- Viola arvensis, growing in fields, meadows, forest edges, and forest violets -- V. mirabilis), fig. 20.

Rice. 20. Distribution of leaf sizes depending on plant living conditions: from wet to dry and from shaded to sunny

Note. The shaded area corresponds to conditions prevailing in nature

Under conditions of excess and lack of light, the spatial arrangement of leaf blades in plants varies significantly. In heliophyte plants, the leaves are oriented to reduce the influx of radiation during the most “dangerous” daytime hours. The leaf blades are located vertically or at a large angle to the horizontal plane, so during the day the leaves receive mostly sliding rays (Fig. 21).

This is especially pronounced in many steppe plants. An interesting adaptation to the weakening of the received radiation is in the so-called “compass” plants (wild lettuce - Lactuca serriola, etc.). The leaves of wild lettuce are located in the same plane, oriented from north to south, and at noon the arrival of radiation to the leaf surface is minimal.

In shade-tolerant plants, the leaves are arranged so as to receive the maximum amount of incident radiation.

Rice. 21.

1,2 -- leaves with different angles of inclination; S 1, S 2 - direct radiation reaching them; Stot -- its total intake to the plant

Often, shade-tolerant plants are capable of protective movements: changing the position of leaf blades when exposed to strong light. Areas of grass cover with folded oxalis leaves coincide relatively precisely with the location of large sun flares. A number of adaptive features can be noted in the structure of the leaf as the main receiver of solar radiation. For example, in many heliophytes, the leaf surface helps to reflect sunlight (shiny - in laurel, covered with a light hairy coating - in cactus, euphorbia) or weaken their effect (thick cuticle, dense pubescence). The internal structure of the leaf is characterized by the powerful development of palisade tissue and the presence of a large number of small and light chloroplasts (Fig. 22).

One of the protective reactions of chloroplasts to excess light is their ability to change orientation and move within the cell, which is clearly expressed in light plants.

In bright light, chloroplasts occupy a wall position in the cell and become an “edge” towards the direction of the rays. In low light, they are distributed diffusely in the cell or accumulate in its lower part.

Rice. 22.

1 - yew; 2- larch; 3 - hoof; 4 - spring clearweed (According to T.K. Goryshina, E.G. Spring, 1978)

Physiological adaptations plants to the light conditions of the ground-air environment cover various vital functions. It has been established that in light-loving plants, growth processes react more sensitively to a lack of light compared to shady plants. As a result, there is an increased elongation of stems, which helps plants break through to the light and into the upper tiers of plant communities.

The main physiological adaptations to light lie in the area of ​​photosynthesis. In general terms, the change in photosynthesis depending on light intensity is expressed by the “photosynthesis light curve.” Its following parameters are of ecological significance (Fig. 23).

• 1. The point of intersection of the curve with the ordinate axis (Fig. 23, A) corresponds to the magnitude and direction of gas exchange in plants in complete darkness: photosynthesis is absent, respiration takes place (not absorption, but release of CO 2), therefore point a lies below the x-axis.
• 2. The point of intersection of the light curve with the abscissa axis (Fig. 23, b) characterizes the “compensation point,” i.e., the light intensity at which photosynthesis (CO 2 absorption) balances respiration (CO 2 release).
• 3. The intensity of photosynthesis with increasing light increases only up to a certain limit, then remains constant - the light curve of photosynthesis reaches a “saturation plateau”.

Rice. 23.

A - general diagram; B -- curves for light-loving (1) and shade-tolerant (2) plants

In Fig. 23, the inflection area is conventionally designated by a smooth curve, the break of which corresponds to a point V. The projection of point c onto the x-axis (point d) characterizes the “saturated” light intensity, i.e., the value above which light no longer increases the intensity of photosynthesis. Projection onto the ordinate axis (point d) corresponds to the highest intensity of photosynthesis for a given species in a given ground-air environment.

4. An important characteristic of the light curve is the angle of inclination (a) to the abscissa, which reflects the degree of increase in photosynthesis with increasing radiation (in the region of relatively low light intensity).

Plants exhibit seasonal dynamics in their response to light. Thus, in the hairy sedge (Carex pilosa), in early spring in the forest, newly emerged leaves have a plateau of light saturation of photosynthesis at 20 - 25 thousand lux; with summer shading in these same species, the curves of the dependence of photosynthesis on light become corresponding to the “shadow” parameters, that is, the leaves acquire the ability to use weak light more efficiently; these same leaves, after overwintering under the canopy of a leafless spring forest, again display the “light” features of photosynthesis.

A unique form of physiological adaptation during a sharp lack of light is the loss of the plant’s ability to photosynthesize and the transition to heterotrophic nutrition with ready-made organic substances. Sometimes such a transition became irreversible due to the loss of chlorophyll by plants, for example, orchids of shady spruce forests (Goodyera repens, Weottia nidus avis), orchids (Monotropa hypopitys). They live off dead organic matter obtained from trees and other plants. This method of nutrition is called saprophytic, and plants are called saprophytes.

For the vast majority of terrestrial animals with day and night activity, vision is one of the methods of orientation and is important for searching for prey. Many animal species also have color vision. In this regard, animals, especially victims, developed adaptive features. These include protective, camouflage and warning coloring, protective similarity, mimicry, etc. The appearance of brightly colored flowers of higher plants is also associated with the characteristics of the visual apparatus of pollinators and, ultimately, with the light regime of the environment.

Water mode. Moisture deficiency is one of the most significant features of the ground-air environment of life. The evolution of terrestrial organisms took place through adaptation to obtaining and preserving moisture. The humidity regimes of the environment on land are varied - from complete and constant saturation of the air with water vapor, where several thousand millimeters of precipitation falls per year (regions of equatorial and monsoon-tropical climates) to their almost complete absence in the dry air of deserts. Thus, in tropical deserts the average annual precipitation is less than 100 mm per year, and at the same time, rain does not fall every year.

The annual amount of precipitation does not always make it possible to assess the water supply of organisms, since the same amount can characterize a desert climate (in the subtropics) and a very humid one (in the Arctic). An important role is played by the ratio of precipitation and evaporation (total annual evaporation from the free water surface), which also varies in different regions of the globe. Areas where this value exceeds the annual amount of precipitation are called arid(dry, arid). Here, for example, plants experience lack of moisture during most of the growing season. Areas in which plants are provided with moisture are called humid, or wet. Transition zones are often identified - semi-arid(semiarid).

The dependence of vegetation on average annual precipitation and temperature is shown in Fig. 24.

Rice. 24.

1 -- tropical forest; 2 -- deciduous forest; 3 - steppe; 4 - desert; 5 -- coniferous forest; 6 -- arctic and mountain tundra

The water supply of terrestrial organisms depends on the precipitation regime, the presence of reservoirs, soil moisture reserves, the proximity of groundwater, etc. This has contributed to the development of many adaptations in terrestrial organisms to various water supply regimes.

In Fig. 25 from left to right shows the transition from lower algae living in water with cells without vacuoles to primary poikilohydric terrestrial algae, the formation of vacuoles in aquatic green and charophytes, the transition from thallophytes with vacuoles to homoyohydric cormophytes (the distribution of mosses - hydrophytes is still limited to habitats with high humidity air, in dry habitats mosses become secondary poikilohydric); among ferns and angiosperms (but not among gymnosperms) there are also secondary poikilohydric forms. Most leafy plants are homoyohydric due to the presence of cuticular protection against transpiration and strong vacuolation of their cells. It should be noted that xerophilicity of animals and plants is characteristic only of the ground-air environment.

Rice. 2

Precipitation (rain, hail, snow), in addition to providing water and creating moisture reserves, often plays another environmental role. For example, during heavy rains, the soil does not have time to absorb moisture, the water quickly flows in strong streams and often carries weakly rooted plants, small animals and fertile soil into lakes and rivers. In floodplains, rain can cause floods and thus have adverse effects on the plants and animals living there. In periodically flooded places, unique floodplain fauna and flora are formed.

Hail also has a negative effect on plants and animals. Agricultural crops in individual fields are sometimes completely destroyed by this natural disaster.

The ecological role of snow cover is diverse. For plants whose renewal buds are located in the soil or near its surface, and for many small animals, snow plays the role of a heat-insulating cover, protecting them from low winter temperatures. When frosts are above -14°C under a 20 cm layer of snow, the soil temperature does not fall below 0.2°C. Deep snow cover protects the green parts of plants from freezing, such as Veronica officinalis, hoofed grass, etc., which go under the snow without shedding their leaves. Small land animals lead an active lifestyle in winter, creating numerous galleries of passages under the snow and in its thickness. In the presence of fortified food, rodents (wood and yellow-throated mice, a number of voles, water rats, etc.) can breed there in snowy winters. During severe frosts, hazel grouse, partridges, and black grouse hide under the snow.

Winter snow cover often prevents large animals from obtaining food and moving, especially when an ice crust forms on the surface. Thus, moose (Alces alces) freely overcome a layer of snow up to 50 cm deep, but this is inaccessible to smaller animals. Often during snowy winters, the death of roe deer and wild boars is observed.

Large amounts of snow also have a negative impact on plants. In addition to mechanical damage in the form of snow chips or snow blowers, a thick layer of snow can lead to damping off of plants, and when the snow melts, especially in a long spring, to soaking of plants.

Rice. 26.

Plants and animals suffer from low temperatures and strong winds in winters with little snow. Thus, in years when there is little snow, mouse-like rodents, moles and other small animals die. At the same time, in latitudes where precipitation falls in the form of snow in winter, plants and animals have historically adapted to life in snow or on its surface, developing various anatomical, morphological, physiological, behavioral and other characteristics. For example, in some animals the supporting surface of their legs increases in winter by overgrowing them with coarse hair (Fig. 26), feathers, and horny scutes.

Others migrate or fall into an inactive state - sleep, hibernation, diapause. A number of animals switch to feeding on certain types of feed.

Rice. 5.27.

The whiteness of the snow cover reveals dark animals. The seasonal change in color in the ptarmigan and tundra partridge, ermine (Fig. 27), mountain hare, weasel, and arctic fox is undoubtedly associated with selection for camouflage to match the background color.

Precipitation, in addition to its direct impact on organisms, determines one or another air humidity, which, as already noted, plays an important role in the life of plants and animals, as it affects the intensity of their water metabolism. Evaporation from the surface of the body of animals and transpiration in plants are more intense, the less the air is saturated with water vapor.

Absorption by the above-ground parts of droplet-liquid moisture falling in the form of rain, as well as vaporous moisture from the air, in higher plants is found in epiphytes of tropical forests, which absorb moisture over the entire surface of the leaves and aerial roots. The branches of some shrubs and trees, for example saxauls - Halaxylon persicum, H. aphyllum, can absorb vaporous moisture from the air. In higher spore plants and especially lower plants, the absorption of moisture by above-ground parts is a common method of water nutrition (mosses, lichens, etc.). With a lack of moisture, mosses and lichens are able to survive for a long time in a state close to air-dry, falling into suspended animation. But as soon as it rains, these plants quickly absorb moisture with all ground parts, acquire softness, restore turgor, and resume the processes of photosynthesis and growth.

In plants in highly humid terrestrial habitats, there is often a need to remove excess moisture. As a rule, this happens when the soil is well warmed up and the roots actively absorb water, and there is no transpiration (in the morning or during fog, when the air humidity is 100%).

Excess moisture is removed by guttation -- this is the release of water through special excretory cells located along the edge or at the tip of the leaf (Fig. 28).

Rice. 28.

1 - in cereals, 2 - in strawberries, 3 - in tulips, 4 - in milkweed, 5 - in Sarmatian bellevalia, 6 - in clover

Not only hygrophytes, but also many mesophytes are capable of guttation. For example, in the Ukrainian steppes, guttation was found in more than half of all plant species. Many meadow grasses humidify so much that they wet the soil surface. This is how animals and plants adapt to the seasonal distribution of precipitation, its quantity and nature. This determines the composition of plants and animals, the timing of certain phases in their development cycle.

Humidity is also affected by the condensation of water vapor, which often occurs in the surface layer of air when the temperature changes. Dew appears when the temperature drops in the evening. Often dew falls in such quantities that it abundantly wets plants, flows into the soil, increases air humidity and creates favorable conditions for living organisms, especially when there is little other precipitation. Plants contribute to the deposition of dew. Cooling at night, they condense water vapor on themselves. The humidity regime is significantly affected by fogs, thick clouds and other natural phenomena.

When quantitatively characterizing the plant habitat based on the water factor, indicators are used that reflect the content and distribution of moisture not only in the air, but also in the soil. Soil water, or soil moisture, is one of the main sources of moisture for plants. Water in the soil is in a fragmented state, interspersed with pores of different sizes and shapes, has a large interface with the soil, and contains a number of cations and anions. Hence, soil moisture is heterogeneous in physical and chemical properties. Not all the water contained in the soil can be used by plants. Based on its physical state, mobility, availability and importance for plants, soil water is divided into gravitational, hygroscopic and capillary.

The soil also contains vaporous moisture, which occupies all water-free pores. This is almost always (except in desert soils) saturated water vapor. When the temperature drops below 0°C, soil moisture turns into ice (initially free water, and with further cooling - part of the bound water).

The total amount of water that can be held by soil (determined by adding excess water and then waiting until it stops dripping out) is called field moisture capacity.

Consequently, the total amount of water in the soil cannot characterize the degree of moisture supply to plants. To determine it, it is necessary to subtract the wilting coefficient from the total amount of water. However, physically accessible soil water is not always physiologically available to plants due to low soil temperature, lack of oxygen in soil water and soil air, soil acidity, and high concentration of mineral salts dissolved in soil water. The discrepancy between the absorption of water by the roots and its release by the leaves leads to wilting of plants. The development of not only the above-ground parts, but also the root system of plants depends on the amount of physiologically available water. In plants growing on dry soils, the root system, as a rule, is more branched and more powerful than on wet soils (Fig. 29).

Rice. 29.

1 -- with a lot of precipitation; 2 - at average; 3 -- at low

One of the sources of soil moisture is groundwater. When their level is low, capillary water does not reach the soil and does not affect its water regime. Moistening the soil due to precipitation alone causes strong fluctuations in its humidity, which often negatively affects plants. Too high a groundwater level is also harmful, because it leads to waterlogging of the soil, depletion of oxygen and enrichment in mineral salts. Constant soil moisture, regardless of the vagaries of the weather, ensures an optimal groundwater level.

Temperature conditions. A distinctive feature of the land-air environment is the large range of temperature fluctuations. In most land areas, daily and annual temperature ranges are tens of degrees. Changes in air temperature are especially significant in deserts and subpolar continental regions. For example, the seasonal temperature range in the deserts of Central Asia is 68-77°C, and the daily temperature range is 25-38°C. In the vicinity of Yakutsk, the average January temperature is 43°C, the average July temperature is +19°C, and the annual range is from -64 to +35°C. In the Trans-Urals, the annual variation in air temperature is sharp and is combined with great variability in the temperatures of the winter and spring months in different years. The coldest month is January, the average air temperature ranges from -16 to -19°C, in some years it drops to -50°C, the warmest month is July with temperatures from 17.2 to 19.5°C. Maximum positive temperatures are 38--41°C.

Temperature fluctuations at the soil surface are even more significant.

Terrestrial plants occupy a zone adjacent to the soil surface, i.e., to the “interface”, on which the transition of incident rays from one medium to another occurs, or in another way - from transparent to opaque. A special thermal regime is created on this surface: during the day there is strong heating due to the absorption of heat rays, at night there is strong cooling due to radiation. From here, the ground layer of air experiences the sharpest daily temperature fluctuations, which are most pronounced over bare soil.

The thermal regime of plant habitats, for example, is characterized based on temperature measurements directly in the vegetation cover. In herbaceous communities, measurements are taken inside and on the surface of the grass stand, and in forests, where there is a certain vertical temperature gradient, at a number of points at different heights.

Resistance to temperature changes in the environment in terrestrial organisms varies and depends on the specific habitat where their life takes place. Thus, terrestrial leafy plants for the most part grow in a wide temperature range, i.e. they are eurythermic. Their life span in the active state extends, as a rule, from 5 to 55°C, while these plants are productive between 5 and 40°C. Plants in continental regions, which are characterized by a clear diurnal temperature variation, develop best when the night is 10-15°C colder than the day. This applies to most plants in the temperate zone - with a temperature difference of 5-10 ° C, and tropical plants with an even smaller amplitude - about 3 ° C (Fig. 30).

Rice. thirty.

In poikilothermic organisms, with increasing temperature (T), the duration of development (t) decreases more and more rapidly. The development rate Vt can be expressed by the formula Vt = 100/t.

To achieve a certain stage of development (for example, in insects - from an egg), i.e. pupation, the imaginal stage, always requires a certain amount of temperature. The product of the effective temperature (temperature above the zero point of development, i.e. T - To) by the duration of development (t) gives a species-specific thermal constant development c=t(T--To). Using this equation, you can calculate the time of onset of a certain stage of development, for example, of a plant pest, at which its control is effective.

Plants, as poikilothermic organisms, do not have their own stable body temperature. Their temperature is determined by the thermal balance, i.e., the ratio of energy absorption and release. These values ​​depend on many properties of both the environment (the size of the radiation arrival, the temperature of the surrounding air and its movement) and the plants themselves (the color and other optical properties of the plant, the size and location of the leaves, etc.). The primary role is played by the cooling effect of transpiration, which prevents severe overheating of plants in hot habitats. As a result of the above reasons, the temperature of plants usually differs (often quite significantly) from the ambient temperature. There are three possible situations here: the plant temperature is higher than the ambient temperature, lower than it, equal to or very close to it. The excess of plant temperature over air temperature occurs not only in highly heated, but also in colder habitats. This is facilitated by the dark color or other optical properties of plants, which increase the absorption of solar radiation, as well as anatomical and morphological features that help reduce transpiration. Arctic plants can heat up quite noticeably (Fig. 31).

Another example is the dwarf willow - Salix arctica in Alaska, whose leaves are 2--11 °C warmer than the air during the day and even at night during the polar “24-hour day” - by 1--3 °C.

For early spring ephemeroids, the so-called “snowdrops,” heating of the leaves provides the opportunity for fairly intense photosynthesis on sunny but still cold spring days. For cold habitats or those associated with seasonal temperature fluctuations, an increase in plant temperature is ecologically very important, since physiological processes thereby become independent, to a certain extent, from the surrounding thermal background.

Rice. 31.

On the right is the intensity of life processes in the biosphere: 1 - the coldest layer of air; 2 -- upper limit of shoot growth; 3, 4, 5 - zone of greatest activity of life processes and maximum accumulation of organic matter; 6 -- permafrost level and lower rooting limit; 7 -- area of ​​lowest soil temperatures

A decrease in the temperature of plants compared to the surrounding air is most often observed in highly illuminated and heated areas of the terrestrial sphere (desert, steppe), where the leaf surface of plants is greatly reduced, and increased transpiration helps remove excess heat and prevents overheating. In general terms, we can say that in hot habitats the temperature of the above-ground parts of plants is lower, and in cold habitats it is higher than the air temperature. The coincidence of plant temperature with the ambient air temperature is less common - in conditions that exclude a strong influx of radiation and intense transpiration, for example, in herbaceous plants under the canopy of forests, and in open areas - in cloudy weather or during rain.

In general, terrestrial organisms are more eurythermic than aquatic ones.

In the ground-air environment, living conditions are complicated by the existence weather changes. Weather is the continuously changing state of the atmosphere at the earth's surface, up to approximately an altitude of 20 km (the boundary of the troposphere). Weather variability is manifested in constant variations in the combination of environmental factors such as air temperature and humidity, cloudiness, precipitation, wind strength and direction, etc. (Fig. 32).

Rice. 32.

Weather changes, along with their regular alternation in the annual cycle, are characterized by non-periodic fluctuations, which significantly complicate the conditions for the existence of terrestrial organisms. In Fig. 33, using the example of the codling moth caterpillar Carpocapsa pomonella, shows the dependence of mortality on temperature and relative humidity.

Rice. 33.

It follows from this that equal mortality curves have a concentric shape and that the optimal zone is limited by relative humidity of 55 and 95% and temperature of 21 and 28 ° C.

Light, temperature and air humidity usually determine not the maximum, but the average degree of opening of stomata in plants, since the coincidence of all conditions promoting their opening rarely happens.

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

The main climatic factors are temperature and humidity, measured by the amount of precipitation and the saturation of air with water vapor. Thus, in countries remote from the sea, there is a gradual transition from a humid climate through a semiarid intermediate zone with occasional or periodic dry periods to an arid territory, which is characterized by prolonged drought, salinization of soil and water (Fig. 34).

Rice. 34.

Note: where the precipitation curve intersects the ascending evapotranspiration line, the boundary between humid (left) and arid (right) climates is located. The humus horizon is shown in black, the illuvial horizon is shown in shading.

Each habitat is characterized by a certain ecological climate, i.e., the climate of the ground layer of air, or ecoclimate.

Vegetation has a great influence on climatic factors. Thus, under the forest canopy, air humidity is always higher, and temperature fluctuations are less than in the clearings. The light regime of these places is also different. Different plant associations form their own regime of light, temperature, humidity, i.e. phytoclimate.

Ecoclimate or phytoclimate data are not always sufficient to fully characterize the climatic conditions of a particular habitat. Local environmental elements (relief, exposure, vegetation, etc.) very often change the regime of light, temperature, humidity, air movement in a particular area in such a way that it can differ significantly from the climatic conditions of the area. Local climate modifications that develop in the surface layer of air are called microclimate. For example, the living conditions surrounding insect larvae living under the bark of a tree are different than in the forest where the tree grows. The temperature of the southern side of the trunk can be 10 - 15°C higher than the temperature of its northern side. Burrows, tree hollows, and caves inhabited by animals have a stable microclimate. There are no clear differences between ecoclimate and microclimate. It is believed that ecoclimate is the climate of large areas, and microclimate is the climate of individual small areas. Microclimate influences living organisms of a particular territory or locality (Fig. 35).

Rice. 3

at the top is a well-warmed slope of southern exposure;

below - a horizontal section of the plakor (the floristic composition in both sections is the same)

The presence of many microclimates in one area ensures the coexistence of species with different requirements for the external environment.

Geographical zonality and zonality. The distribution of living organisms on Earth is closely related to geographic zones and zones. The belts have a latitudinal extension, which, naturally, is primarily due to radiation boundaries and the nature of atmospheric circulation. There are 13 geographic zones on the surface of the globe, spread across continents and oceans (Fig. 36).

Rice. 36.

These are like arctic, antarctic, subarctic, subantarctic, north and south moderate, north and south subarctic, north and south tropical, north and south subequatorial And equatorial. Inside the belts there are geographical zones, where, along with radiation conditions, the moisture of the earth's surface and the ratio of heat and moisture characteristic of a given zone are taken into account. Unlike the ocean, where the supply of moisture is complete, on the continents the ratio of heat and moisture can have significant differences. From here, geographic zones extend to continents and oceans, and geographic zones only to continents. Distinguish latitudinal And meridial or longitudinal natural zones. The former stretch from west to east, the latter from north to south. In the longitudinal direction, latitudinal zones are divided into subzones, and in the latitude - on provinces.

The founder of the doctrine of natural zonality is V.V. Dokuchaev (1846-1903), who substantiated zonality as a universal law of nature. All phenomena within the biosphere are subject to this law. The main reasons for zonation are the shape of the Earth and its position relative to the sun. In addition to latitude, the distribution of heat on Earth is influenced by the nature of the relief and the altitude of the area above sea level, the ratio of land and sea, sea currents, etc.

Subsequently, the radiation foundations for the formation of zonality of the globe were developed by A. A. Grigoriev and M. I. Budyko. To establish a quantitative characteristic of the relationship between heat and moisture for various geographical zones, they determined some coefficients. The ratio of heat and moisture is expressed by the ratio of the surface radiation balance to the latent heat of evaporation and the amount of precipitation (radiation dryness index). A law was established, called the law of periodic geographical zoning (A. A. Grigorieva - M. I. Budyko), which states: that with the change of geographical zones, similar geographical(landscape, natural) zones and some of their general properties are repeated periodically.

Each zone is confined to a certain range of indicator values: a special nature of geomorphological processes, a special type of climate, vegetation, soil and animal life. The following geographical zones were noted on the territory of the former USSR: icy, tundra, forest-tundra, taiga, mixed forests. Russian plain, monsoon mixed forests of the Far East, forest-steppes, steppes, semi-deserts, temperate deserts, subtropical deserts, Mediterranean and humid subtropics.

One of the important conditions for the variability of organisms and their zonal distribution on earth is the variability of the chemical composition of the environment. In this regard, the teaching of A.P. Vinogradov about biogeochemical provinces, which are determined by the zonality of the chemical composition of soils, as well as the climatic, phytogeographical and geochemical zonality of the biosphere. Biogeochemical provinces are areas on the Earth's surface that differ in the content (in soils, waters, etc.) of chemical compounds, which are associated with certain biological reactions on the part of the local flora and fauna.

Along with horizontal zoning in the terrestrial environment, high-rise or vertical zonality.

The vegetation of mountainous countries is richer than on the adjacent plains, and is characterized by an increased distribution of endemic forms. Thus, according to O. E. Agakhanyants (1986), the flora of the Caucasus includes 6,350 species, of which 25% are endemic. The flora of the mountains of Central Asia is estimated at 5,500 species, of which 25-30% are endemic, while on the adjacent plains of the southern deserts there are 200 plant species.

When climbing mountains, the same change of zones is repeated as from the equator to the poles. At the foot there are usually deserts, then steppes, deciduous forests, coniferous forests, tundra and, finally, ice. However, there is still no complete analogy. As you climb the mountains, the air temperature decreases (the average air temperature gradient is 0.6 °C per 100 m), evaporation decreases, ultraviolet radiation and illumination increase, etc. All this forces plants to adapt to dry or wet conditions. The dominant plants here are cushion-shaped life forms and perennials, which have developed adaptation to strong ultraviolet radiation and reduced transpiration.

The fauna of the high mountain regions is also unique. Low air pressure, significant solar radiation, sharp fluctuations in day and night temperatures, and changes in air humidity with altitude contributed to the development of specific physiological adaptations in the body of mountain animals. For example, in animals the relative volume of the heart increases, the content of hemoglobin in the blood increases, which allows more intensive absorption of oxygen from the air. Rocky soil complicates or almost eliminates the burrowing activity of animals. Many small animals (small rodents, pikas, lizards, etc.) find refuge in rock crevices and caves. Among the birds typical for mountainous regions are mountain turkeys (sulars), mountain finches, larks, and large birds - bearded vultures, vultures, and condors. Large mammals in the mountains are inhabited by rams, goats (including snowbucks), chamois, yaks, etc. Predators are represented by species such as wolves, foxes, bears, lynxes, snow leopards (irbis), etc.

The land-air environment is characterized by the peculiarities of ecological conditions that have formed specific adaptations in land plants and animals, which is reflected in a variety of morphological, anatomical, physiological, biochemical and behavioral adaptations.

The low density of atmospheric air makes it difficult to maintain body shape, which is why plants and animals have developed a support system. In plants, these are mechanical tissues (bast and wood fibers) that provide resistance to static and dynamic loads: wind, rain, snow cover. The tense state of the cell wall (turgor), caused by the accumulation of fluid with high osmotic pressure in the vacuoles of cells, determines the elasticity of leaves, grass stems, and flowers. In animals, support for the body is provided by the hydroskeleton (in roundworms), the exoskeleton (in insects), and the internal skeleton (in mammals).

The low density of the environment facilitates the movement of animals. Many terrestrial species are capable of flight (active or gliding) - birds and insects, there are also representatives of mammals, amphibians and reptiles. Flight is associated with movement and search for prey. Active flight is possible due to modified forelimbs and developed pectoral muscles. In gliding animals, skin folds have formed between the fore and hind limbs, which stretch and play the role of a parachute.

The high mobility of air masses has formed in plants the most ancient method of pollination of plants by the wind (anemophily), characteristic of many plants in the middle zone and dispersal with the help of the wind. This ecological group of organisms (aeroplankton) adapted due to their large relative surface area due to parachutes, wings, projections and even webs, or due to their very small size.

Low atmospheric pressure, which is normally 760 mmHg (or 101,325 Pa), and small pressure differences have created sensitivity in almost all land dwellers to strong pressure changes. The upper limit of life for most vertebrates is about 6,000 m. A decrease in atmospheric pressure with increasing altitude above sea level reduces the solubility of oxygen in the blood. This increases the breathing rate, and as a result, frequent breathing leads to dehydration. This simple dependence is not typical only for rare species of birds and some invertebrates.

The gas composition of the land-air environment is characterized by a high oxygen content (more than 20 times higher than in the aquatic environment). This allows animals to have a very high metabolic rate. Therefore, only on land could homeothermy (the ability to maintain a constant body temperature, mainly due to internal energy) arise.

The importance of temperature in the life of organisms is determined by its influence on the rate of biochemical reactions. An increase in environmental temperature (up to 60 ° C) causes denaturation of proteins in organisms. A strong decrease in temperature leads to a decrease in the metabolic rate and, as a critical condition, the freezing of water in the cells (ice crystals in the cells violate the integrity of intracellular structures). Basically, on land, living organisms can only exist within the range of 0 ° - +50 °, because these temperatures are compatible with the occurrence of basic life processes. However, each species has its own upper and lower lethal temperature value, temperature suppression value and temperature optimum.

Organisms whose life and activity depend on external heat (microorganisms, fungi, plants, invertebrates, cyclostomes, fish, amphibians, reptiles) are called poikilotherms. Among them are stenotherms (cryophiles - adapted to small differences in low temperatures and thermophiles - adapted to small differences in high temperatures) and eurytherms, which can exist within a large temperature amplitude. Adaptations to endure low temperatures, which allow the regulation of metabolism for a long time, are carried out in organisms in two ways: a) the ability to undergo biochemical and physiological changes - the accumulation of antifreeze, which lowers the freezing point of liquids in cells and tissues and therefore prevents the formation of ice; change in the set, concentration and activity of enzymes, change; b) tolerance to freezing (cold resistance) is a temporary cessation of the active state (hypobiosis or cryptobiosis) or the accumulation of glycerol, sorbitol, mannitol in cells, which prevent the crystallization of liquid.

Eurytherms have a well-developed ability to transition to a latent state when there are significant temperature deviations from the optimal value. After cold suppression, organisms at a certain temperature restore normal metabolism, and this temperature value is called the temperature threshold for development, or the biological zero of development.

The basis of seasonal changes in eurythermic species, which are widespread, is acclimation (a shift in the temperature optimum), when some genes are inactivated and others are turned on, responsible for the replacement of some enzymes by others. This phenomenon is found in different parts of the range.

In plants, metabolic heat is extremely negligible, so their existence is determined by the air temperature within the habitat. Plants adapt to tolerate fairly large temperature fluctuations. The main thing in this case is transpiration, which cools the surface of the leaves when overheated; reduction of the leaf blade, leaf mobility, pubescence, waxy coating. Plants adapt to cold conditions using growth form (dwarfism, cushion growth, trellis), and color. All this relates to physical thermoregulation. Physiological thermoregulation is the fall of leaves, the death of the ground part, the transfer of free water into a bound state, the accumulation of antifreeze, etc.).

Poikilothermic animals have the possibility of evaporative thermoregulation associated with their movement in space (amphibians, reptiles). They choose the most optimal conditions, produce a lot of internal (endogenous) heat in the process of muscle contraction or muscle tremors (they warm up the muscles during movement). Animals have behavioral adaptations (posture, shelters, burrows, nests).

Homeothermic animals (birds and mammals) have a constant body temperature and are little dependent on the ambient temperature. They are characterized by adaptations based on a sharp increase in oxidative processes as a result of the perfection of the nervous, circulatory, respiratory and other organ systems. They have biochemical thermoregulation (when the air temperature drops, lipid metabolism increases; oxidative processes increase, especially in skeletal muscles; there is specialized brown adipose tissue, in which all the released chemical energy goes to the formation of ATP and to warm the body; the volume of food consumed increases) . But such thermoregulation has climatic restrictions (unprofitable in winter, in polar conditions, in summer in tropical and equatorial zones).

Physical thermoregulation is environmentally beneficial (reflex contraction and expansion of blood vessels in the skin, the thermal insulation effect of fur and feathers, countercurrent heat exchange), because carried out by retaining heat in the body (Chernova, Bylova, 2004).

Behavioral thermoregulation of homeotherms is characterized by diversity: changes in posture, searches for shelter, construction of complex burrows, nests, migration, group behavior, etc.

The most important environmental factor for organisms is light. Processes that occur under the influence of light are photosynthesis (1-5% of the incident light is used), transpiration (75% of the incident light is used for the evaporation of water), synchronization of vital functions, movement, vision, synthesis of vitamins.

Plant morphology and the structure of plant communities are organized to most efficiently absorb solar energy. The light-receiving surface of plants on the globe is 4 times larger than the surface of the planet (Akimova, Haskin, 2000). For living organisms, wavelength matters, because rays of different lengths have different biological significance: infrared radiation (780 - 400 nm) acts on the thermal centers of the nervous system, regulating oxidative processes, motor reactions, etc., ultraviolet rays (60 - 390 nm), acting on the integumentary tissues, promote the production of various vitamins, stimulate cell growth and reproduction.

Visible light is of particular importance because... The quality of light is important for plants. In the spectrum of rays, photosynthetic active radiation (PAR) is distinguished. The wavelength of this spectrum lies in the range 380 – 710 (370-720 nm).

The seasonal dynamics of illumination is associated with astronomical patterns, the seasonal climatic rhythm of a given area, and is expressed differently at different latitudes. For the lower tiers, these patterns are also superimposed on the phenological state of vegetation. The daily rhythm of changes in illumination is of great importance. The course of radiation is disrupted by changes in the state of the atmosphere, cloudiness, etc. (Goryshina, 1979).

The plant is an opaque body that partially reflects, absorbs and transmits light. In the cells and tissues of the leaves there are various formations that ensure the absorption and transmission of light. To increase plant productivity, the total area and number of photosynthetic elements are increased, which is achieved by multi-story arrangement of leaves on the plant; layered arrangement of plants in the community.

In relation to the intensity of illumination, three groups are distinguished: light-loving, shade-loving, shade-tolerant, which differ in anatomical and morphological adaptations (in light-loving plants, the leaves are smaller, mobile, pubescent, have a waxy coating, thick cuticle, crystalline inclusions, etc. in shade-loving plants, the leaves are large , chloroplasts are large and numerous); physiological adaptations (different values ​​of light compensation).

The response to day length (duration of illumination) is called photoperiodism. In plants, such important processes as flowering, seed formation, growth, transition to a dormant state, and leaf fall are associated with seasonal changes in day length and temperature. For some plants to bloom, a day length of over 14 hours is needed, for others 7 hours are enough, and others bloom regardless of the day length.

For animals, light has informational value. First of all, according to daily activity, animals are divided into daytime, crepuscular, and nocturnal. The organ that helps to navigate in space is the eyes. Different organisms have different stereoscopic vision - a person has a general vision of 180 ° - stereoscopic-140 °, a rabbit has a general vision of 360 °, stereoscopic 20 °. Binocular vision is mainly characteristic of predatory animals (felines and birds). In addition, the reaction to light determines phototaxis (movement towards light),

reproduction, navigation (orientation to the position of the Sun), bioluminescence. Light is a signal to attract individuals of the opposite sex.

The most important environmental factor in the life of terrestrial organisms is water. It is necessary to maintain the structural integrity of cells, tissues, and the entire organism, because is the main part of the protoplasm of cells, tissues, plant and animal juices. Thanks to water, biochemical reactions, the supply of nutrients, gas exchange, excretion, etc. are carried out. The water content in the body of plants and animals is quite high (in grass leaves - 83-86%, tree leaves - 79-82%, tree trunks 40-55%, in the bodies of insects - 46-92%, amphibians - up to 93%, mammals - 62-83%).

Existence in a land-air environment poses an important problem for organisms to preserve water in the body. Therefore, the form and functions of land plants and animals are adapted to protect against desiccation. In the life of plants, the supply of water, its conduction and transpiration, water balance are important (Walter, 1031, 1937, Shafer, 1956). Changes in water balance are best reflected by the suction power of the roots.

A plant can absorb water from the soil as long as the sucking force of the roots can compete with the sucking force of the soil. A highly branched root system provides a large area of ​​contact between the absorbent part of the root and soil solutions. The total length of the roots can reach 60 km. The sucking power of roots varies depending on the weather and environmental properties. The larger the suction surface of the roots, the more water is absorbed.

According to the regulation of water balance, plants are divided into poikilohydric (algae, mosses, ferns, some flowering plants) and homohydric (most higher plants).

In relation to the water regime, ecological groups of plants are distinguished.

1. Hygrophytes are terrestrial plants that live in humid habitats with high air humidity and soil water supply. Characteristic features of hygrophytes are thick, weakly branched roots, air-bearing cavities in the tissues, and open stomata.

2. Mesophytes - plants of moderately moist habitats. Their ability to tolerate soil and atmospheric drought is limited. Can be found in arid habitats - developing rapidly in a short period. Characterized by a well-developed root system with numerous root hairs and regulation of the intensity of transpiration.

3. Xerophytes - plants of dry habitats. These are drought-resistant plants, dry-bearing plants. Steppe xerophytes can lose up to 25% of water without damage, desert xerophytes - up to 50% of the water contained in them (for comparison, forest mesophytes wither with the loss of 1% of the water contained in the leaves). According to the nature of the anatomical, morphological and physiological adaptations that ensure the active life of these plants under conditions of moisture deficiency, xerophytes are divided into succulents (they have fleshy and succulent leaves and stems, are able to accumulate large amounts of water in their tissues, develop a small sucking force and absorb moisture from precipitation) and sclerophytes (dry-looking plants that intensively evaporate moisture, have narrow and small leaves that sometimes curl into a tube, are able to withstand severe dehydration, the sucking force of the roots can be up to several tens of atmospheres).

In different groups of animals, in the process of adaptation to the conditions of terrestrial existence, the main thing was to prevent water loss. Animals get water in different ways - through drinking, with succulent food, as a result of metabolism (due to the oxidation and breakdown of fats, proteins and carbohydrates). Some animals can absorb water through covers of moist substrate or air. Water loss occurs as a result of evaporation from the integument, evaporation from the mucous membranes of the respiratory tract, excretion of urine and undigested food debris. Animals that receive water through drinking depend on the location of bodies of water (large mammals, many birds).

An important factor for animals is air humidity, because... this indicator determines the amount of evaporation from the surface of the body. That is why the structure of the body’s integument is important for the water balance of the animal’s body. In insects, the reduction in evaporation of water from the body surface is ensured by an almost impenetrable cuticle and specialized excretory organs (Malpighian tubules), which secrete an almost insoluble metabolic product, and spiracles, which reduce water loss through the gas exchange system - through the tracheae and tracheoles.

In amphibians, the bulk of water enters the body through permeable skin. Skin permeability is regulated by a hormone secreted by the posterior pituitary gland. Amphibians excrete very large amounts of dilute urine, which is hypotonic to body fluids. In dry conditions, amphibians can reduce water loss through urine. In addition, these animals can accumulate water in the bladder and subcutaneous lymphatic spaces.

Reptiles have many adaptations at different levels - morphological (the loss of water is prevented by keratinized skin), physiological (lungs located inside the body, which reduces water loss), biochemical (uric acid is formed in the tissues, which is excreted without much loss of moisture, the tissues are able to tolerate increased concentrations salts by 50%).

In birds, the rate of evaporation is low (the skin is relatively impermeable to water, there are no sweat glands or feathers). Birds lose water (up to 35% of body weight per day) when breathing due to high ventilation in the lungs and high body temperature. Birds have a process of reabsorbing water from some of the water in their urine and feces. Some seabirds (penguins, gannets, cormorants, albatrosses), which eat fish and drink sea water, have salt glands located in the eye sockets, with the help of which excess salts are removed from the body.

In mammals, the organs of excretion and osmoregulation are paired, complex kidneys, which are supplied with blood and regulate the composition of the blood. This ensures a constant composition of intracellular and interstitial fluid. Relatively stable osmotic pressure of the blood is maintained due to the balance between the supply of water through drinking and the loss of water through exhaled air, sweat, feces and urine. Responsible for the fine regulation of osmotic pressure is antidiuretic hormone (ADH), which is secreted from the posterior lobe of the pituitary gland.

Among animals, there are groups: hygrophiles, in which the mechanisms for regulating water metabolism are poorly developed or absent altogether (these are moisture-loving animals that require high environmental humidity - springtails, woodlice, mosquitoes, other arthropods, terrestrial mollusks and amphibians); xerophiles, which have well-developed mechanisms for regulating water metabolism and adapting to retaining water in the body, living in arid conditions; mesophiles living in conditions of moderate humidity.

An indirectly acting environmental factor in the ground-air environment is relief. All forms of relief affect the distribution of plants and animals through changes in the hydrothermal regime or soil-ground moisture.

In the mountains at different altitudes above sea level, climatic conditions change, resulting in altitudinal zonation. Geographical isolation in the mountains contributes to the formation of endemics and the preservation of relict species of plants and animals. River floodplains facilitate the northward movement of more southern groups of plants and animals. The exposure of the slopes is of great importance, which creates conditions for the spread of heat-loving communities to the north along the southern slopes, and cold-loving communities to the south along the northern slopes (“preliminary rule”, V.V. Alekhina).

Soil exists only in the ground-air environment and is formed as a result of the interaction of the age of the territory, parent rock, climate, relief, plants and animals, and human activity. The mechanical composition (size of mineral particles), chemical composition (pH of aqueous solution), soil salinity, and soil richness are of ecological importance. Soil characteristics also act on living organisms as indirect factors, changing the thermo-hydrological regime, causing plants (primarily) to adapt to the dynamics of these conditions and influencing the spatial differentiation of organisms.

A feature of the ground-air environment is that the organisms living here are surrounded by air– a gaseous environment characterized by low humidity, density, pressure and high oxygen content.

Most animals move on a solid substrate - soil, and plants take root in it.

The inhabitants of the ground-air environment have developed adaptations:

1) organs that ensure the absorption of atmospheric oxygen (stomata in plants, lungs and trachea in animals);

2) strong development of skeletal formations that support the body in the air (mechanical tissues in plants, skeleton in animals);

3) complex devices for protection from unfavorable factors (periodicity and rhythm of life cycles, thermoregulation mechanisms, etc.);

4) a close connection has been established with the soil (roots in plants and limbs in animals);

5) characterized by high mobility of animals in search of food;

6) flying animals (insects, birds) and wind-borne seeds, fruits, and pollen appeared.

Ecological factors of the ground-air environment are regulated by macroclimate (ecoclimate). Ecoclimate (macroclimate)– the climate of large areas, characterized by certain properties of the ground layer of air. Microclimate– climate of individual habitats (tree trunk, animal burrow, etc.).

41.Ecological factors of the ground-air environment.

1) Air:

It is characterized by a constant composition (21% oxygen, 78% nitrogen, 0.03% CO 2 and inert gases). It is an important environmental factor because Without atmospheric oxygen, the existence of most organisms is impossible; CO 2 is used for photosynthesis.

The movement of organisms in the ground-air environment is carried out mainly horizontally; only some insects, birds and mammals move vertically.

Air has a huge impact on the life of living organisms through wind– movement of air masses due to uneven heating of the atmosphere by the Sun. Wind influence:

1) dries out the air, causing a decrease in the intensity of water metabolism in plants and animals;

2) participates in plant pollination, carries pollen;

3) reduces the diversity of flying animal species (strong wind interferes with flight);

4) causes changes in the structure of the integument (dense integument is formed, protecting plants and animals from hypothermia and loss of moisture);

5) participates in the dispersal of animals and plants (distributes fruits, seeds, small animals).

2) Atmospheric precipitation:

An important environmental factor, because The water regime of the environment depends on the presence of precipitation:

1) precipitation changes air humidity and soil;

2) provide accessible water for water nutrition of plants and animals.

a) Rain:

The most important factors are the timing of loss, frequency of loss, and duration.

Example: the abundance of rain during the cold period does not provide the plants with the necessary moisture.

The nature of the rain:

- stormwater– unfavorable, because plants do not have time to absorb water, and streams also form that wash away the top fertile layer of soil, plants, and small animals.

- drizzling– favorable, because provide soil moisture and nutrition for plants and animals.

- protracted– unfavorable, because cause floods, floods and flooding.

b) Snow:

It has a beneficial effect on organisms in winter, because:

a) creates a favorable temperature regime in the soil, protects organisms from hypothermia.

Example: at an air temperature of -15 0 C, the soil temperature under a 20 cm layer of snow is not lower than +0.2 0 C.

b) creates an environment in winter for the life of organisms (rodents, chicken birds, etc.)

Adaptations animals to winter conditions:

a) the supporting surface of the legs for walking on snow increases;

b) migration and hibernation (anabiosis);

c) switching to eating certain foods;

d) change of covers, etc.

Negative effects of snow:

a) an abundance of snow leads to mechanical damage to plants, damping off of plants and their getting wet when the snow melts in the spring.

b) the formation of crust and ice (impedes the gas exchange of animals and plants under the snow, creates difficulties for obtaining food).

42. Soil moisture.

The main factor for water nutrition of primary producers – green plants.

Types of soil water:

1) Gravity water – occupies wide spaces between soil particles and, under the influence of gravity, goes into deeper layers. Plants easily absorb it when it is in the root system zone. The reserves in the soil are replenished by precipitation.

2) Capillary water – fills the smallest spaces between soil particles (capillaries). Does not move down, is held by the force of adhesion. Due to evaporation from the soil surface, an upward current of water is formed. Well absorbed by plants.

1) and 2) water available for plants.

3) Chemically bound water – water of crystallization (gypsum, clay, etc.). Inaccessible to plants.

4) Physically bound water – also inaccessible to plants.

A) film(loosely connected) – rows of dipoles sequentially enveloping each other. They are held on the surface of soil particles by a force of 1 to 10 atm.

b) hygroscopic(strongly bound) - envelops soil particles with a thin film and is held in place by a force of 10,000 to 20,000 atm.

If there is only inaccessible water in the soil, the plant will wither and die.

For sand KZ = 0.9%, for clay = 16.3%.

Total amount of water – KZ = degree of water supply to the plant.

43.Geographical zonation of the ground-air environment.

The ground-air environment is characterized by vertical and horizontal zoning. Each zone is characterized by a specific ecoclimate, composition of animals and plants, and territory.

Climatic zones → climatic subzones → climatic provinces.

Walter's classification:

1) Equatorial zone – is located between 10 0 north latitude and 10 0 south latitude. It has 2 rainy seasons, corresponding to the position of the Sun at its zenith. Annual precipitation and humidity are high, and monthly temperature variations are small.

2) tropical zone – located north and south of the equatorial, up to 30 0 north and south latitudes. Characterized by summer rainy periods and winter droughts. Precipitation and humidity decrease with distance from the equator.

3) Dry subtropical zone – located up to 35 0 latitude. The amount of precipitation and humidity are insignificant, annual and daily temperature fluctuations are very significant. There are rarely frosts.

4) Transition zone – characterized by winter rainy seasons and hot summers. Frosts occur more often. Mediterranean, California, south and southwest Australia, southwest South America.

5) Temperate zone – characterized by cyclonic precipitation, the amount of which decreases with distance from the ocean. The annual temperature fluctuation is sharp, summers are hot, winters are frosty. Divided into subzones:

A) warm temperate subzone– the winter period practically does not stand out, all seasons are more or less humid. South Africa.

b) typical temperate climate subzone– cold short winter, cool summer. Central Europe.

V) subzone of arid temperate climate of continental type– characterized by sharp temperature contrasts, low precipitation, and low air humidity. Central Asia.

G) subzone of boreal, or cold temperate climate– summers are cool and humid, winter lasts half the year. Northern North America and Northern Eurasia.

6) Arctic (Antarctic) zone – characterized by a small amount of precipitation in the form of snow. Summer (polar day) is short and cold. This zone passes into the polar region, in which the existence of plants is impossible.

Belarus is characterized by a temperate continental climate with additional moisture. Negative aspects of the Belarusian climate:

Unstable weather in spring and autumn;

Mild spring with prolonged thaws;

Rainy summer;

Late spring and early autumn frosts.

Despite this, about 10,000 plant species grow in Belarus, 430 species of vertebrate animals and about 20,000 species of invertebrate animals live.

Vertical zoning– from lowlands and mountain bases to mountain tops. Similar to horizontal with some deviations.

44. Soil as a living environment. General characteristics.