Soil as a habitat for living organisms. Features of the soil habitat. General characteristics of the soil

10.03.2020

The soil is the result of the activities of living organisms. The organisms inhabiting the ground-air environment led to the emergence of soil as a unique habitat. Soil is a complex system that includes a solid phase (mineral particles), a liquid phase (soil moisture) and a gaseous phase. The ratio of these three phases determines the characteristics of the soil as a living environment.

An important feature of the soil is also the presence of a certain amount of organic matter. It is formed as a result of the death of organisms and is part of their excretions (excretions).

The conditions of the soil habitat determine such properties of the soil as its aeration (i.e., air saturation), humidity (the presence of moisture), heat capacity and thermal regime (daily, seasonal, year-round temperature variation). The thermal regime, in comparison with the ground-air environment, is more conservative, especially at great depths. In general, the soil is characterized by fairly stable living conditions.

Vertical differences are also characteristic of other soil properties, for example, the penetration of light naturally depends on depth.

Many authors note the intermediate position of the soil environment of life between the aquatic and terrestrial-air environments. In the soil, organisms with both water and air type of respiration are possible. The vertical gradient of light penetration in soil is even more pronounced than in water. Microorganisms are found throughout the entire thickness of the soil, and plants (primarily root systems) are associated with outer horizons.

Soil organisms are characterized by specific organs and types of movement (burrowing limbs in mammals; the ability to change body thickness; the presence of specialized head capsules in some species); body shapes (rounded, wolf-shaped, worm-shaped); durable and flexible covers; reduction of eyes and disappearance of pigments. Among the soil inhabitants is widely developed

saprophagia - eating the corpses of other animals, rotting remains, etc.

THE ORGANISM AS A HABITAT

GLOSSARY

NICHE ECOLOGICAL - the position of a species in nature, which includes not only the place of the species in space, but also its functional role in the natural community, the position regarding abiotic conditions of existence, the place of individual phases of the life cycle of representatives of the species in time (for example, early spring plant species occupy a completely independent ecological niche).

EVOLUTION - irreversible historical development of wildlife, accompanied by a change in the genetic composition of populations, the formation and extinction of species, the transformation of ecosystems and the biosphere as a whole.

INTERNAL ENVIRONMENT OF THE ORGANISM- an environment characterized by a relative constancy of composition and properties, which ensures the flow of vital processes in the body. For a person, the internal environment of the body is the system of blood, lymph and tissue fluid.

ECHOLOCATION, LOCATION- determination of the position in space of an object by emitted or reflected signals (in the case of echolocation - the perception of sound signals). The ability to echolocation is possessed by guinea pigs, dolphins, bats. Radar and electrolocation - the perception of reflected radio signals and electric field signals. The ability for this type of location is possessed by some fish - the Nile long-nosed, gimarchus.

THE SOIL - a special natural formation resulting from the transformation of the surface layers of the lithosphere under the influence of living organisms, water, air, and climatic factors.

EXCRETS- end products of metabolism excreted by the body to the outside.

SYMBIOSIS- a form of interspecific relations, consisting in the joint existence of organisms of different systematic groups (symbionts), mutually beneficial, often obligatory cohabitation of individuals of two or more species. A classic (although not indisputable) example of symbiosis is the cohabitation of algae, fungus and microorganisms in the body of lichens.

EXERCISE

The dark green color of the leaves of shade-loving plants is associated with a high content of chlorophyll, which is important in conditions of insufficient lighting, when it is necessary to assimilate the available light to the fullest extent.

1. Try to identify limiting factors(that is, factors hindering the development of organisms) aquatic habitats and adaptation to them.

2. As we have already said, practically the only source of energy for all living organisms is solar energy, assimilated by plants and other photosynthetic organisms. How then do deep-sea ecosystems exist where sunlight does not reach?

NATURAL ENVIRONMENT

Characterizing the natural environment of the Earth from an ecological point of view, an ecologist can always put in the first place the coverage of the types and features of the relationships existing in it between all natural processes and phenomena (of a given object, area, landscape or region), as well as the nature of the influence of human activity on such processes. . At the same time, it is very important to use modern methods for studying the relationship between the population, the economy and the environment, to pay special attention to the causes and consequences of the emergence of so-called chain reactions in nature. It is also important to adhere to a new principle - a comprehensive assessment of environmental situations based on the construction of chains of causal relationships at different stages of the forecast with the involvement of representatives of different fields of knowledge in solving the problem, primarily geographers, geologists, biologists, economists, physicians, lawyers.

Therefore, when studying the features of the main components of the natural environment, it is necessary to remember that they are all closely interconnected, depend one on one and sensitively react to any changes, and the environment is a strong, complex, multifunctional, eternally balanced single system that is alive and constantly self-healing due to its special laws of metabolism and energy. This system has been developing and functioning for a million years, but at the present stage, man, by his activity, has so unbalanced the natural connections of the entire global ecosystem that it began to actively degrade, losing the ability to self-repair.

Thus, the natural environment is a mega-exosphere of constant interactions and interpenetration of elements and processes of its four constituent exospheres (surface shells): atmosphere, lithosphere, hydrosphere and biosphere - under the influence of exogenous (in particular space) and endogenous factors and human activities. Each of the exospheres has its own constituent elements, structure and features. Three of them - the atmosphere, lithosphere and hydrosphere - formed by lifeless substances are the area of functioning of living matter - biota - the main component of the fourth component environment - the biosphere.

ATMOSPHERE

The atmosphere is the outer gaseous shell of the Earth, which reaches from its surface into outer space for approximately 3000 km. The history of the origin and development of the atmosphere is quite complex and long, it has about 3 billion years. During this period, the composition and properties of the atmosphere have repeatedly changed, but over the past 50 million years, according to scientists, they have stabilized.

The mass of the modern atmosphere is approximately one millionth of the mass of the Earth. With height, the density and pressure of the atmosphere sharply decrease, and the temperature changes unevenly and complexly. The change in temperature within the boundaries of the atmosphere at different heights is explained by the unequal absorption of solar energy by gases. The most intensive thermal processes occur in the troposphere, and the atmosphere is heated from below, from the surface of the ocean and land.

It should be noted that the atmosphere is of great ecological importance. It protects all living organisms of the Earth from the destructive influence of cosmic radiation and meteorite impacts, regulates seasonal temperature fluctuations, balances and evens out daily ones. If the atmosphere did not exist, then the fluctuation of the daily temperature on Earth would reach ±200 °C. The atmosphere is not only a life-giving "buffer" between space and the surface of our planet, a carrier of heat and moisture, but photosynthesis and energy exchange also occur through it - the main processes of the biosphere. The atmosphere affects the nature and dynamics of all exogenous processes that occur in the lithosphere (physical and chemical weathering, wind activity, natural waters, permafrost, glaciers).

The development of the hydrosphere also largely depended on the atmosphere due to the fact that the water balance and the regime of surface and underground basins and water areas were formed under the influence of precipitation and evaporation. The processes of the hydrosphere and atmosphere are closely related to each other.

One of the most important components of the atmosphere is water vapor, which has a large spatio-temporal variability and is concentrated mainly in the troposphere. An important variable component of the atmosphere is also carbon dioxide, the variability of the content of which is associated with the vital activity of plants, its solubility in sea water and human activities (industrial and transport emissions). Recently, aerosol dusty particles, products of human activity, which can be found not only in the troposphere, but also at high altitudes (albeit in meager concentrations), will play an increasingly important role in the atmosphere. The physical processes that occur in the troposphere have a great influence on the climatic conditions of different regions of the Earth.

LITHOSPHERE

The lithosphere is the outer solid shell of the Earth, which includes the entire earth's crust with part of the Earth's upper mantle and consists of sedimentary, igneous and metamorphic rocks. The lower boundary of the lithosphere is fuzzy and is determined by a sharp decrease in rock viscosity, a change in the propagation velocity of seismic waves, and an increase in the electrical conductivity of rocks. The thickness of the lithosphere on the continents and under the oceans varies and averages 25-200 and 5-100 km, respectively.

Consider in general terms the geological structure of the Earth. The third planet farthest from the Sun - the Earth has a radius of 6370 km, an average density of 5.5 g / cm3 and consists of three shells - the crust, mantle and core. The mantle and core are divided into inner and outer parts.

The Earth's crust is a thin upper shell of the Earth, which has a thickness of 40-80 km on the continents, 5-10 km under the oceans and makes up only about 1% of the Earth's mass. Eight elements - oxygen, silicon, hydrogen, aluminum, iron, magnesium, calcium, sodium - form 99.5% of the earth's crust. On the continents, the crust is three-layered: sedimentary rocks cover granitic rocks, and granitic rocks lie on basalt rocks. Under the oceans, the crust is of an "oceanic", two-layer type; sedimentary rocks lie simply on basalts, there is no granite layer. There is also a transitional type of the earth's crust (island-arc zones on the margins of the oceans and some areas on the continents, such as the Black Sea). The earth's crust has the greatest thickness in mountainous regions (under the Himalayas - over 75 km), the average - in the areas of platforms (under the West Siberian lowland - 35-40, within the Russian platform - 30-35), and the smallest - in the central regions of the oceans (5 -7 km). The predominant part of the earth's surface is the plains of the continents and the ocean floor. The continents are surrounded by a shelf - a shallow-water strip up to 200 g deep and an average width of about 80 km, which, after a sharp abrupt bend of the bottom, passes into the continental slope (the slope varies from 15-17 to 20-30 °). The slopes gradually level off and turn into abyssal plains (depths 3.7-6.0 km). The greatest depths (9-11 km) have oceanic trenches, the vast majority of which are located on the northern and western margins of the Pacific Ocean.

The main part of the lithosphere consists of igneous igneous rocks (95%), among which granites and granitoids predominate on the continents, and basalts in the oceans.

The relevance of the ecological study of the lithosphere due to the fact that the lithosphere is the environment of all mineral resources, one of the main objects of anthropogenic activity (components of the natural environment), through significant changes in which the global ecological crisis develops. In the upper part of the continental crust, soils are developed, the importance of which for humans can hardly be overestimated. Soils - an organomineral product of many years (hundreds and thousands of years) of the general activity of living organisms, water, air, solar heat and light are one of the most important natural resources. Depending on climatic and geological and geographical conditions, soils have a thickness

from 15-25 cm to 2-3 m.

Soils arose together with living matter and developed under the influence of the activities of plants, animals and microorganisms until they became a very valuable fertile substrate for humans. The bulk of organisms and microorganisms of the lithosphere is concentrated in soils, at a depth of no more than a few meters. Modern soils are a three-phase system (different-grained solid particles, water and gases dissolved in water and pores), which consists of a mixture of mineral particles (rock destruction products), organic substances (biota waste products of its microorganisms and fungi). Soils play a huge role in the circulation of water, substances and carbon dioxide.

Various minerals are associated with different rocks of the earth's crust, as well as with its tectonic structures: combustible, metal, construction, as well as those that are raw materials for the chemical and food industries.

Terrible ecological processes (shifts, mudflows, landslides, erosion) periodically occurred and continue to occur within the boundaries of the lithosphere, which are of great importance for the formation of ecological situations in a certain region of the planet, and sometimes lead to global ecological disasters.

The deep layers of the lithosphere, which are explored by geophysical methods, have a rather complex and still insufficiently studied structure, just like the mantle and core of the Earth. But it is already known that the density of rocks increases with depth, and if on the surface it averages 2.3-2.7 g / cm3, then at a depth of close to 400 km - 3.5 g / cm3, and at a depth of 2900 km ( boundary of the mantle and the outer core) - 5.6 g/cm3. In the center of the core, where the pressure reaches 3.5 thousand tons/cm2, it increases to 13-17 g/cm3. The nature of the increase in the deep temperature of the Earth has also been established. At a depth of 100 km, it is approximately 1300 K, at a depth of close to 3000 km -4800, and in the center of the earth's core - 6900 K.

The predominant part of the Earth's matter is in a solid state, but on the border of the earth's crust and upper mantle (depths of 100-150 km) lies a stratum of softened, pasty rocks. This thickness (100-150 km) is called the asthenosphere. Geophysicists believe that other parts of the Earth can also be in a rarefied state (due to decompaction, active radio decay of rocks, etc.), in particular, the zone of the outer core. The inner core is in the metallic phase, but today there is no consensus on its material composition.

HYDROSPHERE

The hydrosphere is the water sphere of our planet, the totality of oceans, seas, waters of continents, ice sheets. The total volume of natural waters is close to 1.39 billion km3 (1/780 of the planet's volume). Water covers 71% of the planet's surface (361 million km 2).

Water performs four very important ecological functions:
a) is the most important mineral raw material, the main natural resource of consumption (mankind uses it a thousand times more than coal or oil);
b) is the main mechanism for the implementation of the interconnections of all processes in ecosystems (metabolism, heat, biomass growth);
c) is the main agent-carrier of global bioenergetic ecological cycles;
d) is the main component of all living organisms.

For a huge number of living organisms, especially in the early stages of the development of the biosphere, water was the medium of origin and development.

Water will play a huge role in the formation of the Earth's surface, its landscapes, in the development of exogenous processes (karst), the transfer of chemicals to the depths of the Earth and on its surface, and the transportation of environmental pollutants.

Water vapor in the atmosphere acts as a powerful filter of solar radiation, and on Earth - a neutralizer of extreme temperatures, a climate regulator.

The bulk of the water on the planet is made up of the salty waters of the oceans. The average salinity of these waters is 35% (that is, 35 g of salts are placed in 1 liter of ocean water). The most salty water in the Dead Sea is 260% in (in the Black Sea - 18%).

Baltic - 7%).

The chemical composition of oceanic waters, according to experts, is very similar to the composition of human blood - almost all chemical elements known to us are placed in them, but, of course, in different proportions. A particle of oxygen, hydrogen, chlorine and sodium is 95.5%.

The chemical composition of groundwater is very diverse. Depending on the composition of the rocks and the depth of occurrence, they change from bicarbonate-calcium to sulfate, sulfate-sodium and chloride-sodium, mineralization from fresh to brine with a concentration of 600%, often with the presence of a gas component. Mineral and thermal underground waters are of great balneological importance, they are one of the recreational elements of the natural environment.

Of the gases discovered in the waters of the World Ocean, oxygen and carbon dioxide are the most important for biota. The total mass of carbon dioxide in ocean waters exceeds its mass in the atmosphere by about 60 times.

It should be noted that carbon dioxide from oceanic waters is consumed by plants during photosynthesis. Part of it, which entered the circulation of organic matter, is spent on the construction of limestone skeletons of corals and shells. After the death of organisms, carbon dioxide returns to the ocean water due to the dissolution of the remains of skeletons, shells, and shells. Some of it remains in carbonate sediments at the bottom of the oceans.

Of great importance for the formation of climate and other environmental factors is the dynamics of a huge mass of ocean waters, which are constantly in motion under the influence of unequal intensity of solar heating of the surface at different latitudes.

Ocean waters will play a major role in the water cycle on the planet. It is estimated that in about 2 million years all the water on the planet passes through living organisms, the average duration of the total exchange cycle of water involved in the biological cycle is 300-400 years. Approximately 37 times a year (that is, every ten days) all the moisture in the atmosphere changes.

NATURAL RESOURCES

Natural resources- this is a special component of the natural environment, they should be given special attention, since their presence, type, quantity and quality largely determine the relationship of man to nature, the nature and extent of anthropogenic changes in the environment.

Natural resources are understood as everything that a person uses to ensure his existence - food, minerals, energy, space for life, air space, water, objects to meet aesthetic needs.

For several more decades, therefore, if the attitude of all peoples to nature was determined by only one motto: to subdue, to take the most, without giving anything away, since humanity took, destroyed, burned, cut down, destroyed, destroyed, consumed, not counting the riches of the Earth. Now other times have come, because, having calculated, they came to their senses. It turns out that there are no practically inexhaustible resources in nature at all. Conditionally, it is still possible to refer to the inexhaustible total reserves of water on the planet and oxygen in the atmosphere. But due to their uneven distribution, even today in certain areas and regions of the Earth there is an acute shortage of them. All mineral resources belong to the non-renewable and the most important of them are now exhausted or are on the verge of destruction (coal, iron, manganese, oil, polymetals). Due to the rapid degradation of a number of biosphere ecosystems in recent years, the resources of living matter - biomass - have also ceased to be restored, as well as fresh drinking water supplies.

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soil habitat

Introduction

1. Soil as a habitat

2. Living organisms in the soil

3. Importance of soil

4. Soil structure

5. Organic part of the soil

Conclusion

Introduction

At present, the problem of the interaction of human society with nature has become particularly acute.

It becomes indisputable that the solution to the problem of preserving the quality of human life is unthinkable without a certain understanding of modern environmental problems: the preservation of the evolution of living, hereditary substances (the gene pool of flora and fauna), the preservation of the purity and productivity of natural environments (atmosphere, hydrosphere, soil, forests, etc. ), ecological regulation of the anthropogenic pressure on natural ecosystems within their buffer capacity, the preservation of the ozone layer, trophic chains in nature, the biocirculation of substances, and others.

The soil cover of the Earth is the most important component of the Earth's biosphere. It is the soil shell that determines many processes occurring in the biosphere.

The most important significance of soils is the accumulation of organic matter, various chemical elements, and energy. The soil cover functions as a biological absorber, destroyer and neutralizer of various contaminants. If this link of the biosphere is destroyed, then the existing functioning of the biosphere will be irreversibly disrupted. That is why it is extremely important to study the global biochemical significance of the soil cover, its current state and changes under the influence of anthropogenic activity.

1. Soil as a habitat

An important stage in the development of the biosphere was the emergence of such a part of it as the soil cover. With the formation of a sufficiently developed soil cover, the biosphere becomes an integral complete system, all parts of which are closely interconnected and dependent on each other.

The main structural elements of the soil are: the mineral base, organic matter, air and water. The mineral base (skeleton) (50-60% of the total soil) is an inorganic substance formed as a result of the underlying mountain (parent, soil-forming) rock as a result of its weathering. 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.

Organic matter - up to 10% of the soil, is formed from dead biomass crushed and processed into soil humus by microorganisms, fungi and other saprophages. Organic substances formed as a result of the decomposition of organic matter are again absorbed by plants and are involved in the biological cycle.

2. Living organisms in the soil

In nature, there are practically no situations where any single soil with properties that are unchanged in space extends for many kilometers. At the same time, differences in soils are due to differences in the factors of soil formation.

The regular spatial distribution of soils in small areas is called the soil cover structure (SCC). The initial unit of SPP is the elementary soil area (EPA) - a soil formation within which there are no soil-geographical boundaries. ESAs alternating in space and to some extent genetically related form soil combinations.

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

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

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

Geoxens are animals that occasionally visit the soil as cover or shelter. These include all mammals living in burrows, many insects (cockroaches (Blattodea), hemipterans (Hemiptera), some species of beetles).

A special group is psammophytes and psammophiles (marble beetles, ant lions); adapted to loose sands in deserts. Adaptations to life in a mobile, dry environment in plants (saxaul, sandy acacia, sandy fescue, etc.): adventitious roots, dormant buds on the roots. The former begin to grow when falling asleep with sand, the latter when blowing sand. They are saved from sand drift by rapid growth, reduction of leaves. Fruits are characterized by volatility, springiness. Sandy covers on the roots, corking of the bark, and strongly developed roots protect from drought. Adaptations to life in a mobile, dry environment in animals (indicated above, where thermal and humid conditions were considered): they mine the sands - they push them apart with their bodies. In burrowing animals, paws-skis - with growths, with hair. Soil is an intermediate medium between water (temperature conditions, low oxygen content, saturation with water vapor, the presence of water and salts in it) and air (air cavities, sudden changes in humidity and temperature in the upper layers). For many arthropods, soil was the medium through which they were able to move from an aquatic to a terrestrial lifestyle. The main indicators of soil properties, reflecting its ability to be a habitat for living organisms, are the hydrothermal regime and aeration. Or humidity, temperature and soil structure. All three indicators are closely related. With an increase in humidity, thermal conductivity increases and soil aeration worsens. The higher the temperature, the more evaporation occurs. The concepts of physical and physiological dryness of soils are directly related to these indicators.

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

In Primorye, such periods are typical for late spring and are especially pronounced on the slopes of southern exposures. Moreover, with the same position in the relief and other similar growth conditions, the better the vegetation cover is developed, the faster the state of physical dryness sets in.

Physiological dryness is a more complex phenomenon, it is due to adverse environmental conditions. It consists in the physiological inaccessibility of water with a sufficient, and even excessive amount of it in the soil. As a rule, water becomes physiologically inaccessible at low temperatures, high salinity or acidity of soils, the presence of toxic substances, and a lack of oxygen. At the same time, water-soluble nutrients such as phosphorus, sulfur, calcium, potassium, etc., become inaccessible.

Due to the coldness of soils, and the waterlogging and high acidity caused by it, large reserves of water and mineral salts in many ecosystems of the tundra and northern taiga forests are physiologically inaccessible to own-rooted plants. This explains the strong suppression of higher plants in them and the wide distribution of lichens and mosses, especially sphagnum.

One of the important adaptations to the harsh conditions in the edasphere is mycorrhizal nutrition. Almost all trees are associated with mycorrhizal fungi. Each type of tree has its own mycorrhiza-forming type of fungus. Due to mycorrhiza, the active surface of root systems increases, and the secretions of the fungus by the roots of higher plants are easily absorbed. As V.V. Dokuchaev "... Soil zones are also natural historical zones: here the closest connection between climate, soil, animal and plant organisms is obvious ...". This is clearly seen in the example of the soil cover in forest areas in the north and south of the Far East.

A characteristic feature of the soils of the Far East, which are formed under monsoonal, i.e. very humid climate, is a strong leaching of elements from the eluvial horizon. But in the northern and southern regions of the region, this process is not the same due to the different heat supply of habitats. Soil formation in the Far North takes place under conditions of a short growing season (no more than 120 days), and widespread permafrost. The lack of heat is often accompanied by waterlogging of soils, low chemical activity of weathering of soil-forming rocks and slow decomposition of organic matter. The vital activity of soil microorganisms is strongly suppressed, and the assimilation of nutrients by plant roots is inhibited. As a result, the northern cenoses are characterized by low productivity - wood reserves in the main types of larch woodlands do not exceed 150 m 2 /ha. At the same time, the accumulation of dead organic matter prevails over its decomposition, as a result of which powerful peaty and humus horizons are formed, and the humus content is high in the profile. Thus, in northern larch forests, the thickness of the forest litter reaches ?10-12 cm, and the reserves of undifferentiated mass in the soil are up to 53% of the total biomass reserve of the stand. At the same time, elements are carried out of the profile, and when the permafrost is close, they accumulate in the illuvial horizon. In soil formation, as in all cold regions of the northern hemisphere, the leading process is podzol formation. Zonal soils on the northern coast of the Sea of Okhotsk are Al-Fe-humus podzols, and in continental regions - podburs. Peat soils with permafrost in the profile are common in all regions of the Northeast. Zonal soils are characterized by a sharp differentiation of horizons by color.

3. Importance of soil

The soil cover is the most important natural formation. Its role in the life of society is determined by the fact that the soil is the main source of food, providing 95-97% of the food resources for the world's population. The land area of the world is 129 million km 2 or 86.5% of the land area. Arable land and perennial plantations as part of agricultural land occupy about 15 million km 2 (10% of land), hayfields and pastures - 37.4 million km 2 (25% of land). The general arable suitability of lands is estimated by various researchers in different ways: from 25 to 32 million km 2.

The concept of soil as an independent natural body with special properties appeared only at the end of the 19th century, thanks to V.V. Dokuchaev, the founder of modern soil science. He created the doctrine of the zones of nature, soil zones, factors of soil formation.

4. Soil structure

Soil is a special natural formation that has a number of properties inherent in animate and inanimate nature. Soil is the environment where most of the elements of the biosphere interact: water, air, living organisms. The soil can be defined as a product of weathering, reorganization and formation of the upper layers of the earth's crust under the influence of living organisms, the atmosphere and metabolic processes. The soil consists of several horizons (layers with the same features), resulting from the complex interaction of parent rocks, climate, plant and animal organisms (especially bacteria), and terrain. All soils are characterized by a decrease in the content of organic matter and living organisms from the upper soil horizons to the lower ones.

The Al horizon is dark-colored, contains humus, is enriched in minerals and is of the greatest importance for biogenic processes.

Horizon A 2 - eluvial layer, usually has an ash, light gray or yellowish gray color.

Horizon B is an eluvial layer, usually dense, brown or brown in color, enriched in colloidal dispersed minerals.

Horizon C - parent rock altered by soil-forming processes.

Horizon B is the parent rock.

The surface horizon consists of vegetation residues that form the basis of humus, the excess or deficiency of which determines the fertility of the soil.

Humus is the organic matter most resistant to decomposition and therefore persists after the main decomposition process has already been completed. Gradually, humus also mineralizes to inorganic matter. Mixing humus with soil gives it structure. The layer enriched with humus is called arable, and the underlying layer is called subarable. The main functions of humus are reduced to a series of complex metabolic processes, which involve not only nitrogen, oxygen, carbon and water, but also various mineral salts present in the soil. Under the humus horizon there is a subsoil layer corresponding to the leached part of the soil, and a horizon corresponding to the parent rock.

The soil consists of three phases: solid, liquid and gaseous. The solid phase is dominated by mineral formations and various organic substances, including humus, or humus, as well as soil colloids of organic, mineral or organomineral origin. The liquid phase of the soil, or soil solution, is water with organic and mineral compounds dissolved in it, as well as gases. The gas phase of the soil is "soil air", which includes gases that fill the water-free pores.

An important component of the soil, contributing to the change in its physical and chemical properties, is its biomass, which includes, in addition to microorganisms (bacteria, algae, fungi, unicellular organisms), also worms and arthropods.

Soil formation has been occurring on Earth since the beginning of life and depends on many factors:

The substrate on which soils form. The physical properties of soils (porosity, water-holding capacity, friability, etc.) depend on the nature of the parent rocks. They determine the water and thermal regime, the intensity of mixing of substances, the mineralogical and chemical compositions, the initial content of nutrients, and the type of soil.

Vegetation - green plants (the main creators of primary organic substances). Absorbing carbon dioxide from the atmosphere, water and minerals from the soil, using light energy, they create organic compounds suitable for animal nutrition.

With the help of animals, bacteria, physical and chemical influences, organic matter decomposes, turning into soil humus. Ash substances fill the mineral part of the soil. Undecomposed plant material creates favorable conditions for the action of soil fauna and microorganisms (sustained gas exchange, thermal conditions, humidity).

Animal organisms that perform the function of converting organic matter into the soil. Saprophages (earthworms, etc.), feeding on dead organic matter, affect the humus content, the thickness of this horizon, and the structure of the soil. From the terrestrial animal world, soil formation is most intensively influenced by all types of rodents and herbivores.

Microorganisms (bacteria, unicellular algae, viruses) that decompose complex organic and mineral substances into simpler ones, which can later be used by the microorganisms themselves and higher plants.

Some groups of microorganisms are involved in the transformation of carbohydrates and fats, others - nitrogenous compounds. Bacteria that absorb molecular nitrogen from the air are called nitrogen-fixing bacteria. Thanks to their activities, atmospheric nitrogen can be used (in the form of nitrates) by other living organisms. Soil microorganisms take part in the destruction of toxic metabolic products of higher plants, animals and microorganisms themselves in the synthesis of vitamins necessary for plants and soil animals.

The climate, which affects the thermal and water regimes of the soil, and hence the biological and physico-chemical soil processes.

A relief that redistributes heat and moisture on the earth's surface.

Human economic activity is currently becoming the dominant factor in the destruction of soils, the decrease and increase in their fertility. Under the influence of man, the parameters and factors of soil formation change - reliefs, microclimate, reservoirs are created, melioration is carried out.

The main property of the soil is fertility. It has to do with soil quality.

In the destruction of soils and a decrease in their fertility, the following processes are distinguished:

Aridization of land is a complex of processes for reducing the humidity of vast territories and the resulting reduction in the biological productivity of ecological systems. Under the influence of primitive agriculture, the irrational use of pastures, and the indiscriminate use of technology on the lands, the soils turn into deserts.

Soil erosion, destruction of soils under the influence of wind, water, machinery and irrigation. The most dangerous is water erosion - soil flushing by melt, rain and storm water. Water erosion is noted at a steepness of already 1-2 °. Water erosion contributes to the destruction of forests, plowing on the slope. soil habitat humus microorganism

Wind erosion is characterized by the removal of the smallest parts by the wind. Wind erosion contributes to the destruction of vegetation in areas with insufficient moisture, strong winds, continuous grazing.

Technical erosion is associated with the destruction of soil under the influence of transport, earthmoving machines and equipment.

Irrigation erosion develops as a result of violation of irrigation rules in irrigated agriculture. Soil salinization is mainly associated with these disturbances. Currently, at least 50% of the area of irrigated land is saline, and millions of previously fertile lands have been lost. A special place among the soils is occupied by arable land, i.e. lands that provide human food. According to the conclusion of scientists and experts, at least 0.1 ha of soil should be cultivated to feed one person. The growth in the number of inhabitants of the Earth is directly related to the area of arable land, which is steadily declining. So in the Russian Federation over the past 27 years, the area of agricultural land has decreased by 12.9 million hectares, of which arable land - by 2.3 million hectares, hayfields - by 10.6 million hectares. The reasons for this are the violation and degradation of the soil cover, the allocation of land for the development of cities, towns and industrial enterprises.

Over large areas, there is a decrease in soil productivity due to a decrease in the content of humus, the reserves of which have decreased by 25-30% in the Russian Federation over the past 20 years, and the annual loss is 81.4 million tons. Today, the earth can feed 15 billion people. Careful and competent handling of land today has become the most urgent problem.

From what has been said, it follows that the soil includes mineral particles, detritus, and many living organisms, i.e. Soil is a complex ecosystem that supports plant growth. Soils are a slowly renewable resource.

Soil formation processes proceed very slowly, at a rate of 0.5 to 2 cm per 100 years. The thickness of the soil is small: from 30 cm in the tundra to 160 cm in the western chernozems. One of the features of the soil - natural fertility - is formed for a very long time, and the destruction of fertility occurs in just 5-10 years. It follows from the above that the soil is less mobile than other abiotic components of the biosphere. Human economic activity is currently becoming the dominant factor in the destruction of soils, the decrease and increase in their fertility.

5. Organic part of the soil

The soil contains some organic matter. In organogenic (peat) soils, it can predominate, but in most mineral soils, its amount does not exceed a few percent in the upper horizons.

The composition of the organic matter of the soil includes both plant and animal remains that have not lost the features of the anatomical structure, as well as individual chemical compounds called humus. The latter contains both non-specific substances of a known structure (lipids, carbohydrates, lignin, flavonoids, pigments, waxes, resins, etc.), which make up up to 10-15% of the total humus, and specific humic acids formed from them in the soil.

Humic acids do not have a specific formula and represent a whole class of macromolecular compounds. In Soviet and Russian soil science, they are traditionally divided into humic and fulvic acids.

Elemental composition of humic acids (by mass): 46-62% C, 3-6% N, 3-5% H, 32-38% O. Composition of fulvic acids: 36-44% C, 3-4.5% N, 3-5% H, 45-50% O. Both compounds also contain sulfur (from 0.1 to 1.2%), phosphorus (hundredths and tenths of a%). Molecular weights for humic acids are 20-80 kDa (minimum 5 kDa, maximum 650 kDa), for fulvic acids 4-15 kDa. Fulvic acids are more mobile, soluble in the entire pH range (humic acids precipitate in an acidic environment). The carbon ratio of humic and fulvic acids (Cha/Cfa) is an important indicator of the humus status of soils.

In the molecule of humic acids, a core is isolated, consisting of aromatic rings, including nitrogen-containing heterocycles. The rings are connected by "bridges" with double bonds, creating extended conjugation chains, causing the dark color of the substance. The core is surrounded by peripheral aliphatic chains, including hydrocarbon and polypeptide types. The chains carry various functional groups (hydroxyl, carbonyl, carboxyl, amino groups, etc.), which is the reason for the high absorption capacity - 180-500 meq/100 g.

Much less is known about the structure of fulvic acids. They have the same composition of functional groups, but a higher absorption capacity - up to 670 meq/100 g.

The mechanism of formation of humic acids (humification) is not fully understood. According to the condensation hypothesis (M.M. Kononova, A.G. Trusov), these substances are synthesized from low molecular weight organic compounds. According to L.N. Alexandric humic acids are formed by the interaction of macromolecular compounds (proteins, biopolymers), then gradually oxidized and split. According to both hypotheses, enzymes formed mainly by microorganisms take part in these processes. There is an assumption about a purely biogenic origin of humic acids. In many properties, they resemble the dark-colored pigments of fungi.

Conclusion

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

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

And the great Russian scientist V.V. Dokuchaev (1899) was the first to call soil an independent natural body and proved that soil is "... the same independent natural-historical body as any plant, any animal, any mineral ... it is the result, a function of the cumulative, mutual activity of the climate of a given area, its plant and animal organisms, the topography and age of the country..., finally, the subsoil, i.e. soil parent rocks... All these soil-forming agents, in essence, are completely equivalent in magnitude and take an equal part in the formation of normal soil... ".

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Environmental factors

In the environment, any living organism is inevitably affected by a number of conditions. They are called environmental factors. Among them, a special group is made up of components of inanimate nature. These are abiotic factors. These include indicators of water and air temperature, pressure, chemical composition of the atmosphere, soil type.

Biotic factors combine different forms of relationships between organisms. They can be neutral, mutually beneficial or antagonistic. At the present stage, anthropogenic factors have acquired special significance. These are all forms of human economic activity.

Habitats of organisms

Each species is adapted to certain conditions of existence. Their combination is called habitat. There are four in total. These are ground-air, water, soil and other organisms. Each of them has its own characteristics. For example, high specific heat capacity, slight temperature fluctuations are characteristics of the aquatic environment. For soil, completely different indicators are characteristic.

What is soil?

Let's start with the definition of the concept. The soil is called the upper loose fertile. Its structure is represented by clay particles, grains of sand and organic matter - humus. Between them are cavities that are filled with water or air. The depth of the soil habitat, the characteristics of which we are considering, is several meters.

Characteristics of the soil habitat: table

As you can see, the soil is a fairly dynamic system. Over time, the layers mutually transform and replace each other.

Soil habitat: characteristics

The upper layer of the lithosphere has a number of unique features. The soil habitat, the nature of the conditions of which is relatively constant, has the following features:

High density, which makes it difficult for organisms to move.
The presence of light only in the upper layers, which makes it possible for some species of algae to exist there.
Minor temperature fluctuations.
Increased content of carbon dioxide, which is a product of the respiration of the roots of plants, fungi and animals.
The constant availability of water, the level of which is determined by climatic conditions and the number of inhabitants.
Presence of multispecies communities of organisms and their remains.

locals

Who can live in such conditions? Root systems and plants are located in the top layer of the soil. There are lichens, cyanobacteria, green and diatoms. Especially a lot of them on the soil surface, where the most favorable conditions for photosynthesis.

But fungi and bacteria inhabit the entire thickness of the soil. Among animals there are protozoa, annelids and roundworms, gastropods. Soil vertebrates are mole rats, moles, shrews.

Some animals spend only a certain stage of their lives in this habitat. For example, beetles lay their larvae in the soil. And as they develop, they move to the ground-air environment. Rodents endure adverse conditions here - drought or cold.

Ways of adaptation

The characteristics of the soil habitat also include the characteristics of the organisms that inhabit it. Each species has adapted to it in its own way. Since movement in the soil is difficult, its inhabitants have a worm-like or rounded body shape. There are two ways to move in the soil. So, earthworms pass it through the digestive tube. But mammals have limbs of a burrowing type. In mole rats and moles, the organs of vision are underdeveloped, and in some species they are completely overgrown. In their many moves, such animals navigate with the help of other senses - touch and smell.

Since animals are constantly exposed to friction against solid particles during movement, their covers are durable and flexible. At the same time, water evaporates through the cuticle of soil insects, which is very important in conditions of high humidity. Oxygen molecules are located between solid particles, so most soil animals breathe through the entire surface of the body.

So, the characteristics of the soil habitat are briefly represented by the following features:

It is the upper layer of the lithosphere, which has fertility.
It consists of solid particles and humus, between which there are water and air molecules.
Differs in constancy of conditions.
The main abiotic factors for this environment are the lack of light, high carbon dioxide content, and high density.

Soil - loose surface layer of the earth's crust, transformed in the process of weathering and inhabited by living organisms. As a fertile layer, the soil provides the existence of plants. Plants get water and nutrients from the soil. Leaves and branches, dying, “return” to the soil, where they decompose, releasing the minerals contained in them.

The soil consists of solid, liquid, gaseous and living parts. The solid part makes up 80-98% of the soil mass: sand, clay, silt particles left from the parent rock as a result of the soil-forming process (their ratio characterizes the mechanical composition of the soil).

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

The living part of the soil consists of soil microorganisms, representatives of invertebrates (protozoa, worms, mollusks, insects and their larvae), burrowing vertebrates. They live mainly in the upper layers of the soil, near the roots of plants, where they get their food. Some soil organisms can only live on roots. Many destructive organisms live in the surface layers of the soil - bacteria and fungi, the smallest arthropods and worms, termites and centipedes. There are about 5 tons of fungi and bacteria per 1 ha of fertile soil layer (15 cm thick).

The body as a habitat

Under the microscope, he discovered that on a flea,

The biting flea lives on a flea;

On that flea is a tiny flea,

Angrily sticks a tooth into a flea

Flea ... and so on without end

This environment has properties that bring it closer to the water and ground-air environments. Many small organisms live here as hydrobionts in pore accumulations of free water. As in the aquatic environment, soil temperature fluctuations are great. Their amplitudes rapidly decay with depth. The probability of oxygen deficiency is significant, especially with an excess of moisture or carbon dioxide. The similarity with the ground-air environment is manifested through the presence of pores filled with air.

To specific properties, inherent only in the soil, is a dense addition (solid part or skeleton). In soils, it is usually isolated three phase(parts): solid, liquid and gaseous. IN AND. Vernadsky attributed the soil to bio-bone bodies, thus emphasizing the great role in its formation and the life of organisms and their metabolic products. The soil- the most saturated part of the biosphere with living organisms (soil film of life). Therefore, a fourth phase is sometimes distinguished in it - the living one.

As limiting factors in the soil, most often there is a lack of heat (especially in permafrost), as well as a lack (dry conditions) or excess (bogs) of moisture. Less often limiting are lack of oxygen or excess of carbon dioxide.

The life of many soil organisms is closely related to pores and their size. Some organisms move freely in pores. Other (larger organisms), when moving in the pores, change the shape of the body according to the principle of overflow, for example, an earthworm, or compact the walls of the pores. Still others - they can only move by loosening the soil or throwing forming material (diggers) to the surface. Due to the lack of light, many soil organisms are deprived of organs of vision. Orientation is carried out using the sense of smell or other receptors.

Plants, animals and microorganisms living in the soil are in constant interaction with each other and with the environment. Due to these relationships and as a result of fundamental changes in the physical, chemical and biochemical properties of the rock, soil-forming processes are constantly taking place in nature.

On average, the soil contains 2-3 kg/m2 of living plants and animals, or 20-30 t/ha. According to the degree of connection with the soil as a habitat, animals are combined into three environmental groups: geobionts, geophiles and geoxennes.

Geobionts- permanent inhabitants of the soil. The entire cycle of their development takes place in the soil environment. These are such as earthworms, many primary wingless insects.

Geophiles- animals, part of the development cycle of which necessarily occurs in the soil. Most insects belong to this group: locusts, a number of beetles, weevil mosquitoes. Their larvae develop in the soil. In adulthood, these are typical terrestrial inhabitants. Geophiles also include insects that are in the soil in the pupal phase.

geoxenes- animals that occasionally visit the soil for temporary shelter or refuge. These include insects - cockroaches, many hemipterans, rodents, mammals living in holes.

soil inhabitants depending on their size and degree of mobility can be divided into several groups:

Microbiota, microbiotype- these are soil microorganisms that make up the main link in the detrital food chain, they are, as it were, an intermediate link between plant residues and soil animals. These are green and blue-green algae, bacteria, fungi and protozoa. They live in soil pores filled with gravitational or capillary water.

Mesobiota, mesobiotype- this is a collection of small, easily extracted from the soil, mobile animals. These include soil nematodes, mites, small insect larvae, springtails, etc.

Macrobiota, macrobiotype- These are large soil animals with body sizes from 2 to 20 mm. This group includes insect larvae, centipedes, enchytreids, earthworms, etc.

Megabiota, megabiotype- these are large shrews: golden moles in Africa, moles in Eurasia, marsupial moles in Australia, mole rats, slerushonki, zokors. This also includes the inhabitants of holes (badgers, marmots, ground squirrels, jerboas, etc.).

A special group includes the inhabitants of free-flowing mobile sands - psammophytes(thick-toed ground squirrel, comb-toed jerboa, runners, grouse, marbled beetles, horses, etc.). Animals that have adapted to life on saline soils are called halophiles.

The most important property of the soil is its fertility, which is determined by the content of humus, macro-microelements. Plants that grow predominantly in fertile soils are called eutrophic or eutrophic, content with a small amount of nutrients - oligotrophic.

Between them there is an intermediate group mesotrophic types.

Plants that are especially demanding on the increased content of nitrogen in the soil are called nitrophils(raspberries, hops, nettles, amaranth), adapted to growing on soils with a high salt content - halyphites, on non-salted - glycophytes. A special group is represented by plants adapted to loose sands - psammophytes(white saxaul, kandam, sand locust); plants growing on peat (peat bogs) are called oxylophytes(ledum, sundew). lithophytes called plants that live on stones, rocks, scree - these are autotrophic algae, scale lichens, leaf lichens, etc.

Soil as a habitat for living organisms. Features of the soil habitat. General characteristics of the soil

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3. Importance of soil

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Environmental factors

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locals

Ways of adaptation

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