Abiotic factors are properties of inanimate nature that directly or indirectly affect living organisms. In Fig. Table 5 (see appendix) shows the classification of abiotic factors. Let's start our consideration with climatic factors of the external environment.
Temperature is the most important climatic factor. The intensity of metabolism of organisms and their geographical distribution depend on it. Any organism is capable of living within a certain temperature range. And although these intervals are different for different types of organisms (eurythermic and stenothermic), for most of them the zone of optimal temperatures at which vital functions are carried out most actively and efficiently is relatively small. The temperature range in which life can exist is approximately 300 C: from 200 to +100 bC. But most species and most of activities are confined to an even narrower temperature range. Certain organisms, especially those in the dormant stage, can survive for at least some time at very low temperatures. Certain types of microorganisms, mainly bacteria and algae, are able to live and reproduce at temperatures close to the boiling point. The upper limit for hot spring bacteria is 88 C, for blue-green algae 80 C, and for the most tolerant fish and insects about 50 C. As a rule, the upper limits of the factor are more critical than the lower limits, although many organisms function near the upper limits of the tolerance range more effective.
Aquatic animals tend to have a narrower range of temperature tolerance than terrestrial animals because the temperature range in water is smaller than on land.
Thus, temperature is an important and very often limiting factor. Temperature rhythms largely control the seasonal and daily activity of plants and animals.
Precipitation and humidity are the main quantities measured when studying this factor. The amount of precipitation depends mainly on the paths and nature of large movements of air masses. For example, winds blowing from the ocean leave most of the moisture on the slopes facing the ocean, resulting in a “rain shadow” behind the mountains, which contributes to the formation of the desert. Moving inland, the air accumulates a certain amount of moisture, and the amount of precipitation increases again. Deserts tend to be located behind high mountain ranges or along coastlines where winds blow from vast inland dry areas rather than from the ocean, such as the Nami Desert in South West Africa. The distribution of precipitation by season is an extremely important limiting factor for organisms.
Humidity is a parameter characterizing the content of water vapor in the air. Absolute humidity is the amount of water vapor per unit volume of air. Due to the dependence of the amount of steam retained by air on temperature and pressure, the concept of relative humidity was introduced - this is the ratio of the steam contained in the air to the saturated steam at a given temperature and pressure. Since in nature there is a daily rhythm of humidity, increasing at night and decreasing during the day, and its fluctuations vertically and horizontally, this factor, along with light and temperature, plays important role in regulating the activity of organisms. The supply of surface water available to living organisms depends on the amount of precipitation in a given area, but these values do not always coincide. Thus, using underground sources, where water comes from other areas, animals and plants can receive more water than from receiving it with precipitation. Conversely, rainwater sometimes immediately becomes inaccessible to organisms.
Radiation from the Sun consists of electromagnetic waves of various lengths. It is absolutely necessary for living nature, as it is the main external source of energy. It must be borne in mind that the spectrum of electromagnetic radiation from the Sun is very wide and its frequency ranges affect living matter in different ways.
For living matter, the important qualitative characteristics of light are wavelength, intensity and duration of exposure.
Ionizing radiation knocks electrons out of atoms and attaches them to other atoms to form pairs of positive and negative ions. Its source is radioactive substances contained in rocks Moreover, it comes from space.
Different types of living organisms differ greatly in their ability to withstand large doses of radiation exposure. Most studies show that rapidly dividing cells are most sensitive to radiation.
In higher plants, sensitivity to ionizing radiation is directly proportional to the size of the cell nucleus, or more precisely to the volume of chromosomes or DNA content.
The gas composition of the atmosphere is also an important climatic factor. About 33.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen. The composition of the atmosphere was largely determined by volcanic gases. Due to the lack of oxygen, there was no ozone screen to block ultraviolet radiation from the Sun. Over time, due to abiotic processes, oxygen began to accumulate in the planet’s atmosphere, and the formation of the ozone layer began.
The wind can even change the appearance of plants, especially in those habitats, for example in alpine zones, where other factors have a limiting effect. It has been experimentally shown that in open mountain habitats the wind limits plant growth: when a wall was built to protect the plants from the wind, the height of the plants increased. Storms are of great importance, although their effect is purely local. Hurricanes and ordinary winds can transport animals and plants over long distances and thereby change the composition of communities.
Atmospheric pressure does not appear to be a direct limiting factor, but it is directly related to weather and climate, which have a direct limiting effect.
Aquatic conditions create a unique habitat for organisms, differing from terrestrial ones primarily in density and viscosity. The density of water is approximately 800 times, and the viscosity is approximately 55 times higher than that of air. Together with density and viscosity, the most important physical and chemical properties aquatic environment are: temperature stratification, that is, changes in temperature along the depth of a water body and periodic changes in temperature over time, as well as water transparency, which determines the light regime under its surface: photosynthesis of green and purple algae, phytoplankton, and higher plants depends on transparency.
As in the atmosphere, the gas composition of the aquatic environment plays an important role. In aquatic habitats, the amount of oxygen carbon dioxide and other gases dissolved in water and therefore available to organisms, varies greatly over time. In reservoirs with a high content of organic matter, oxygen is a limiting factor of paramount importance.
Acidity, the concentration of hydrogen ions (pH), is closely related to the carbonate system. The pH value varies in the range from 0 pH to 14: at pH = 7 the environment is neutral, at pH<7 кислая, при рН>7 alkaline. If acidity does not approach extreme values, then communities are able to compensate for changes in this factor; community tolerance to the pH range is very significant. Waters with low pH contain few nutrients, so productivity is extremely low.
Salinity content of carbonates, sulfates, chlorides, etc. is another significant abiotic factor in water bodies. There are few salts in fresh waters, of which about 80% are carbonates. The content of minerals in the world's oceans averages 35 g/l. Open ocean organisms are generally stenohaline, whereas coastal brackish water organisms are generally euryhaline. The concentration of salts in body fluids and tissues of most marine organisms is isotonic with the concentration of salts in sea water, so there are no problems with osmoregulation here.
The current not only greatly influences the concentration of gases and nutrients, but also directly acts as a limiting factor. Many river plants and animals are morphologically and physiologically specially adapted to maintaining their position in the flow: they have well-defined limits of tolerance to the flow factor.
Hydrostatic pressure in the ocean is of great importance. With immersion in water of 10 m, the pressure increases by 1 atm (105 Pa). In the deepest part of the ocean the pressure reaches 1000 atm (108 Pa). Many animals are able to tolerate sudden fluctuations in pressure, especially if they do not have free air in their bodies. Otherwise, gas embolism may develop. High pressures, characteristic of great depths, as a rule, inhibit vital processes.
The soil.
Soil is the layer of material that lies on top of rocks. earth's crust. The Russian natural scientist Vasily Vasilyevich Dokuchaev in 1870 was the first to consider soil as a dynamic, rather than inert, medium. He proved that the soil is constantly changing and developing, and chemical, physical and biological processes take place in its active zone. Soil is formed through a complex interaction of climate, plants, animals and microorganisms. Soil composition includes four main structural components: mineral base (usually 50-60% of the total soil composition), organic matter (up to 10%), air (1525%) and water (2530%).
The mineral skeleton of the soil is an inorganic component that is formed from the parent rock as a result of its weathering.
Soil organic matter is formed by the decomposition of dead organisms, their parts and excrement. Organic residues that are not completely decomposed are called litter, and the final product of decomposition amorphous substance, in which it is no longer possible to recognize the original material, is called humus. Thanks to its physical and chemical properties, humus improves soil structure and aeration, and increases the ability to retain water and nutrients.
The soil is home to many species of plant and animal organisms that influence its physicochemical characteristics: bacteria, algae, fungi or protozoa, worms and arthropods. Their biomass in various soils is equal (kg/ha): bacteria 10007000, microscopic fungi 1001000, algae 100300, arthropods 1000, worms 3501000.
The main topographic factor is altitude above sea level. With altitude, average temperatures decrease, daily temperature differences increase, precipitation, wind speed and radiation intensity increase, atmospheric pressure and gas concentrations decrease. All these factors influence plants and animals, causing vertical zonation.
Mountain ranges can act as climate barriers. Mountains also serve as barriers to the spread and migration of organisms and can play the role of a limiting factor in the processes of speciation.
Another topographic factor is slope exposure. In the northern hemisphere, south-facing slopes receive more sunlight, so the light intensity and temperature here are higher than on valley floors and northern-facing slopes. In the southern hemisphere the opposite situation occurs.
An important relief factor is also the steepness of the slope. Steep slopes are characterized by rapid drainage and soil washing away, so the soils here are thin and drier.
For abiotic conditions, all the considered laws of the influence of environmental factors on living organisms are valid. Knowledge of these laws allows us to answer the question: why did different ecosystems form in different regions of the planet? The main reason is the unique abiotic conditions of each region.
The distribution areas and numbers of organisms of each species are limited not only by the conditions of the external inanimate environment, but also by their relationships with organisms of other species. The immediate living environment of an organism constitutes its biotic environment, and the factors of this environment are called biotic. Representatives of each species are able to exist in an environment where connections with other organisms provide them with normal living conditions.
Let us consider the characteristic features of relationships of various types.
Competition is the most comprehensive type of relationship in nature, in which two populations or two individuals, in the struggle for the conditions necessary for life, influence each other negatively.
Competition can be intraspecific and interspecific.
Intraspecific competition occurs between individuals of the same species, interspecific competition occurs between individuals of different species. Competitive interaction may concern living space, food or nutrients, light, shelter and many other vital factors.
Interspecific competition, regardless of what underlies it, can lead either to the establishment of equilibrium between two species, or to the replacement of the population of one species by the population of another, or to the fact that one species will displace another to another place or force it to move to another place. use of other resources. It has been established that two species identical in ecological terms and needs cannot coexist in one place and sooner or later one competitor displaces the other. This is the so-called exclusion principle or Gause principle.
Since the structure of the ecosystem is dominated by food interactions, the most characteristic form of interaction between species in food chains is predation, in which an individual of one species, called the predator, feeds on organisms (or parts of organisms) of another species, called the prey, and the predator lives separately from the prey. In such cases, the two species are said to be involved in a predator-prey relationship.
Neutrality is a type of relationship in which none of the populations has any influence on the other: it does not in any way affect the growth of its populations, which are in equilibrium, or their density. In reality, however, it is quite difficult to verify, through observations and experiments in natural conditions, that two species are absolutely independent of each other.
Summarizing the consideration of the forms of biotic relationships, we can draw the following conclusions:
1) relationships between living organisms are one of the main regulators of the number and spatial distribution of organisms in nature;
2) negative interactions between organisms appear at the initial stages of community development or in disturbed natural conditions; in recently formed or new associations, the likelihood of strong negative interactions occurring is greater than in old associations;
3) in the process of evolution and development of ecosystems, a tendency is revealed to reduce the role of negative interactions at the expense of positive ones that increase the survival of interacting species.
A person must take into account all these circumstances when carrying out measures to manage ecological systems and individual populations in order to use them in his own interests, as well as anticipate the indirect consequences that may occur.
Abiotic factors are factors of inanimate nature that directly or indirectly act on an organism - light, temperature, humidity, the chemical composition of the air, water and soil environment, etc. (i.e., properties of the environment, the occurrence and impact of which does not directly depend on the activities of living organisms ).
Light (solar radiation) is an environmental factor characterized by the intensity and quality of the radiant energy of the Sun, which is used by photosynthetic green plants to create plant biomass. Sunlight reaching the Earth's surface is the main source of energy for maintaining the thermal balance of the planet, the water metabolism of organisms, the creation and transformation of organic matter by the autotrophic element of the biosphere, which ultimately makes it possible to form an environment capable of satisfying vital needs
organisms.
Temperature is one of the most important abiotic factors, on which the existence, development and distribution of organisms on Earth largely depends [show]. The importance of temperature lies primarily in its direct influence on the speed and nature of metabolic reactions in organisms. Since daily and seasonal temperature fluctuations increase with distance from the equator, plants and animals, adapting to them, exhibit different needs for heat.
Humidity is an environmental factor characterized by the water content in the air, soil, and living organisms. In nature, there is a daily rhythm of humidity: it increases at night and decreases during the day. Together with temperature and light, humidity plays an important role in regulating the activity of living organisms. The source of water for plants and animals is mainly precipitation and The groundwater, as well as dew and fog.
In the abiotic part of the environment (in inanimate nature), all factors can primarily be divided into physical and chemical. However, to understand the essence of the phenomena and processes under consideration, it is convenient to represent abiotic factors as a set of climatic, topographic, cosmic factors, as well as characteristics of the composition of the environment (aquatic, terrestrial or soil).
The main climatic factors include solar energy, temperature, precipitation and humidity, environmental mobility, pressure, and ionizing radiation.
Environmental factors - properties of the environment that have any effect on the body. Indifferent elements of the environment, for example, inert gases, are not environmental factors.
Environmental factors exhibit significant variability in time and space. For example, temperature varies greatly on the surface of land, but is almost constant at the bottom of the ocean or deep in caves.
Classifications of environmental factors
By the nature of the impact
Direct acting - directly affecting the body, mainly on metabolism
Indirectly acting - influencing indirectly, through changes in directly acting factors (relief, exposure, altitude, etc.)
By origin
Abiotic - factors of inanimate nature:
climatic: annual sum of temperatures, average annual temperature, humidity, air pressure
edaphic (edaphogenic): mechanical composition soil, soil breathability, soil acidity, soil chemical composition
orographic: relief, height above sea level, steepness and aspect of the slope
chemical: gas composition air, salt composition of water, concentration, acidity
physical: noise, magnetic fields, thermal conductivity and heat capacity, radioactivity, solar radiation intensity
Biotic - related to the activity of living organisms:
phytogenic - influence of plants
mycogenic - influence of fungi
zoogenic - influence of animals
microbiogenic - influence of microorganisms
Anthropogenic (anthropic):
physical: use of nuclear energy, travel on trains and planes, influence of noise and vibration
chemical: the use of mineral fertilizers and pesticides, pollution of the Earth’s shells with industrial and transport waste
biological: food; organisms for which humans can be a habitat or source of food
social - related to relationships between people and life in society
By spending
Resources - elements of the environment that the body consumes, reducing their supply in the environment (water, CO2, O2, light)
Conditions - environmental elements not consumed by the body (temperature, air movement, soil acidity)
By direction
Vectorized - directionally changing factors: waterlogging, soil salinization
Perennial-cyclical - with alternating multi-year periods of strengthening and weakening of a factor, for example climate change in connection with the 11-year solar cycle
Oscillatory (pulse, fluctuation) - fluctuations in both directions from a certain average value (daily fluctuations in air temperature, changes in the average monthly precipitation throughout the year)
Optimum Rule
In accordance with this rule, for an ecosystem, an organism or a certain stage of its development, there is a range of the most favorable (optimal) factor value. Outside the optimum zone there are zones of oppression, turning into critical points beyond which existence is impossible. The maximum population density is usually confined to the optimum zone. Optimum zones for different organisms are not the same. For some, they have a significant range. Such organisms belong to the group of eurybionts. Organisms with a narrow range of adaptation to factors are called stenobionts.
The range of factor values (between critical points) is called environmental valence. A synonym for the term valence is tolerance, or plasticity (variability). These characteristics depend largely on the environment in which the organisms live. If it is relatively stable in its properties (the amplitudes of fluctuations of individual factors are small), it contains more steno-bionts (for example, in an aquatic environment); if it is dynamic, for example, ground-air, eurybionts have a greater chance of survival in it. The optimum zone and ecological valence are usually wider in warm-blooded organisms than in cold-blooded ones. It should also be borne in mind that the ecological valence for the same species does not remain the same in different conditions (for example, in northern and southern regions during certain periods of life, etc.). Young and senile organisms, as a rule, require more conditioned (homogeneous) conditions. Sometimes these requirements are quite ambiguous. For example, with respect to temperature, insect larvae are usually stenobiont (stenothermic), while pupae and adults may be eurybiont (eurythermic).
Related information.
Introduction
Abiotic environmental factors are components and phenomena of inanimate, inorganic nature that directly or indirectly affect living organisms. Naturally, these factors act simultaneously and this means that all living organisms fall under their influence. The degree of presence or absence of each of them significantly affects the viability of organisms, and varies differently for different species. It should be noted that this greatly affects the entire ecosystem as a whole and its sustainability.
Environmental factors, both individually and in combination, when affecting living organisms, force them to change and adapt to these factors. This ability is called ecological valence or plasticity. The plasticity, or environmental valency, of each species is different and has a different effect on the ability of living organisms to survive under changing environmental factors. If organisms not only adapt to biotic factors, but can also influence them, changing other living organisms, then this is impossible with abiotic environmental factors: the organism can adapt to them, but is not able to have any significant reverse influence on them.
Abiotic environmental factors are conditions that are not directly related to the life activity of organisms. The most important abiotic factors include temperature, light, water, composition of atmospheric gases, soil structure, composition of nutrients in it, terrain, etc. These factors can affect organisms both directly, for example light or heat, and indirectly, for example, terrain, which determines the action of direct factors, light, wind, moisture, etc. More recently, the influence of changes in solar activity on biosphere processes has been discovered.
Main abiotic factors and their characteristics
Among the abiotic factors are:
1. Climatic (the influence of temperature, light and humidity);
2. Geological (earthquake, volcanic eruption, glacial movement, mudflows and avalanches, etc.);
3. Orographic (features of the terrain where the studied organisms live).
Let us consider the action of the main direct abiotic factors: light, temperature and the presence of water. Temperature, light and humidity are the most important environmental factors. These factors naturally change both throughout the year and day, and in connection with geographic zoning. Organisms exhibit zonal and seasonal adaptation to these factors.
Light as an environmental factor
Solar radiation is the main source of energy for all processes occurring on Earth. In the spectrum of solar radiation, three regions can be distinguished, different in biological action: ultraviolet, visible and infrared. Ultraviolet rays with a wavelength of less than 0.290 microns are destructive to all living things, but they are delayed ozone layer atmosphere. Only a small portion of longer ultraviolet rays (0.300 - 0.400 microns) reaches the Earth's surface. They make up about 10% of radiant energy. These rays are highly chemically active; at high doses they can damage living organisms. In small quantities, however, they are necessary, for example, for humans: under the influence of these rays, vitamin D is formed in the human body, and insects visually distinguish these rays, i.e. see in ultraviolet light. They can navigate by polarized light.
Visible rays with a wavelength of 0.400 to 0.750 microns (they account for most of the energy - 45% - of solar radiation) reaching the Earth's surface are especially important for organisms. Green plants, due to this radiation, synthesize organic matter (carry out photosynthesis), which is used as food by all other organisms. For most plants and animals, visible light is one of the important factors environments, although there are those for which light is not a prerequisite for existence (soil, cave and deep-sea types of adaptation to life in the dark). Most animals are able to distinguish the spectral composition of light - have color vision, and plants have flowers bright color to attract pollinating insects.
Infrared rays with a wavelength of more than 0.750 microns are not perceived by the human eye, but they are a source of thermal energy (45% of radiant energy). These rays are absorbed by the tissues of animals and plants, causing the tissues to heat up. Many cold-blooded animals (lizards, snakes, insects) use sunlight to increase their body temperature (some snakes and lizards are ecologically warm-blooded animals). Light conditions associated with the Earth's rotation have distinct daily and seasonal cycles. Almost all physiological processes in plants and animals have a daily rhythm with a maximum and minimum in certain hours: for example, at certain times of the day, flowers in plants open and close, and animals have developed adaptations to night and day life. Day length (or photoperiod) is of great importance in the life of plants and animals.
Plants, depending on their living conditions, adapt to the shade - shade-tolerant plants or, on the contrary, to the sun - light-loving plants (for example, cereals). However, strong, bright sun (above optimal brightness) suppresses photosynthesis, making it difficult to produce high yields of protein-rich crops in the tropics. In temperate zones (above and below the equator), the development cycle of plants and animals is confined to the seasons of the year: preparation for changes in temperature conditions is carried out on the basis of a signal - changes in day length, which at a certain time of the year in a given place is always the same. As a result of this signal, physiological processes are turned on, leading to plant growth and flowering in the spring, fruiting in the summer and shedding leaves in the fall; in animals - to molting, fat accumulation, migration, reproduction in birds and mammals, and the onset of the resting stage in insects. Animals perceive changes in day length using their visual organs. And plants - with the help of special pigments located in the leaves of plants. Irritations are perceived through receptors, as a result of which a series of biochemical reactions occur (activation of enzymes or release of hormones), and then physiological or behavioral reactions appear.
The study of photoperiodism in plants and animals has shown that the reaction of organisms to light is based not simply on the amount of light received, but on the alternation of periods of light and darkness of a certain duration during the day. Organisms are able to measure time, i.e. have a “biological clock” - from single-celled organisms to humans. “Biological clock” is also controlled by seasonal cycles and other biological phenomena. “Biological clocks” determine the daily rhythm of activity of both whole organisms and processes occurring even at the cellular level, in particular cell divisions.
Temperature as an environmental factor
All chemical processes occurring in the body depend on temperature. Changes in thermal conditions, often observed in nature, deeply affect the growth, development and other manifestations of the life of animals and plants. There are organisms with an unstable body temperature - poikilothermic and organisms with a constant body temperature - homeothermic. Poikilothermic animals depend entirely on temperature environment, while homeotherms are able to maintain a constant body temperature regardless of changes in ambient temperature. The vast majority of terrestrial plants and animals in a state of active life cannot tolerate negative temperatures and die. The upper temperature limit of life is not the same for different species - rarely above 40-45 o C. Some cyanobacteria and bacteria live at temperatures of 70-90 o C; some mollusks can also live in hot springs (up to 53 o C). For most terrestrial animals and plants, the optimum temperature conditions fluctuate within rather narrow limits (15-30 o C). The upper threshold of life temperature is determined by the temperature of protein coagulation, since irreversible protein coagulation (disruption of protein structure) occurs at a temperature of about 60 o C.
In the process of evolution, poikilothermic organisms have developed various adaptations to changing temperature conditions of the environment. The main source of thermal energy in poikilothermic animals is external heat. Poikilothermic organisms have developed various adaptations to low temperatures. Some animals, for example, Arctic fish, which constantly live at a temperature of -1.8 o C, contain substances (glycoproteins) in their tissue fluid that prevent the formation of ice crystals in the body; insects accumulate glycerol for these purposes. Other animals, on the contrary, increase heat production in the body due to active contraction of muscles - this way they increase body temperature by several degrees. Still others regulate their heat exchange due to the exchange of heat between the vessels of the circulatory system: the vessels coming from the muscles are in close contact with the vessels coming from the skin and carrying cooled blood (this phenomenon is characteristic of cold-water fish). Adaptive behavior involves many insects, reptiles and amphibians selecting places in the sun to warm themselves or changing different positions to increase the heating surface.
In a number of cold-blooded animals, body temperature can vary depending on the physiological state: for example, in flying insects, the internal body temperature can rise by 10-12 o C or more due to increased muscle work. Social insects, especially bees, have developed effective method maintaining temperature through collective thermoregulation (the hive can maintain a temperature of 34-35 o C, necessary for the development of larvae).
Poikilothermic animals are able to adapt to high temperatures. This also occurs in different ways: heat transfer can occur due to the evaporation of moisture from the surface of the body or from the mucous membrane of the upper respiratory tract, as well as due to subcutaneous vascular regulation (for example, in lizards, the speed of blood flow through the vessels of the skin increases with increasing temperature).
The most perfect thermoregulation is observed in birds and mammals - homeothermic animals. In the process of evolution, they acquired the ability to maintain a constant body temperature due to the presence of a four-chambered heart and one aortic arch, which ensured complete separation of arterial and venous blood flow; high metabolism; feathers or hair; regulation of heat transfer; well developed nervous system acquired the ability to live actively at different temperatures. In most birds, the body temperature is slightly higher than 40 o C, and in mammals it is slightly lower. Very important for animals is not only the ability to thermoregulate, but also adaptive behavior, the construction of special shelters and nests, the choice of a place with a more favorable temperature, etc. They are also able to adapt to low temperatures in several ways: in addition to feathers or hair, warm-blooded animals use trembling (microcontractions of externally motionless muscles) to reduce heat loss; the oxidation of brown adipose tissue in mammals produces additional energy that supports metabolism.
The adaptation of warm-blooded animals to high temperatures is in many ways similar to similar adaptations of cold-blooded animals - sweating and evaporation of water from the mucous membrane of the mouth and upper respiratory tract; in birds - only the latter method, since they do not have sweat glands; dilation of blood vessels located close to the surface of the skin, which increases heat transfer (in birds, this process occurs in non-feathered areas of the body, for example through the crest). Temperature, as well as the light regime on which it depends, naturally changes throughout the year and in connection with geographic latitude. Therefore, all adaptations are more important for living at low temperatures.
Water as an environmental factor
Water plays an exceptional role in the life of any organism, since it is a structural component of the cell (water accounts for 60-80% of the cell's mass). The importance of water in the life of a cell is determined by its physicochemical properties. Due to polarity, a water molecule is able to attract any other molecules, forming hydrates, i.e. is a solvent. Many chemical reactions can only occur in the presence of water. Water is a “thermal buffer” in living systems, absorbing heat during the transition from a liquid to a gaseous state, thereby protecting unstable cell structures from damage during the short-term release of thermal energy. In this regard, it produces a cooling effect when evaporating from the surface and regulates body temperature. The thermal conductivity properties of water determine its leading role as a climate thermoregulator in nature. Water slowly heats up and slowly cools: in summer and during the day, the water of the seas, oceans and lakes heats up, and at night and in winter it also slowly cools. There is a constant exchange of carbon dioxide between water and air. In addition, water performs transport function, moving soil substances from top to bottom and back. The role of humidity for terrestrial organisms is due to the fact that precipitation is distributed over earth's surface unevenly throughout the year. In arid areas (steppes, deserts), plants obtain water with the help of a highly developed root system, sometimes very long roots (for camel thorn - up to 16 m), reaching the wet layer. The high osmotic pressure of cell sap (up to 60-80 atm), which increases the suction power of the roots, helps retain water in the tissues. In dry weather, plants reduce water evaporation: in desert plants, the integumentary tissues of the leaves thicken, or a waxy layer or dense pubescence develops on the surface of the leaves. A number of plants achieve a decrease in moisture by reducing the leaf blade (leaves turn into spines, often plants completely lose leaves - saxaul, tamarisk, etc.).
Depending on the requirements for the water regime, the following ecological groups are distinguished among plants:
Hydratophytes are plants that constantly live in water;
Hydrophytes - plants that are only partially immersed in water;
Helophytes - marsh plants;
Hygrophytes are terrestrial plants that live in excessively moist places;
Mesophytes - prefer moderate moisture;
Xerophytes are plants adapted to constant lack of moisture; Among xerophytes there are:
Succulents - accumulating water in the tissues of their body (succulent);
Sclerophytes - lose a significant amount of water.
Many desert animals can survive without drinking water; some can run quickly and for a long time, making long migrations to watering places (saiga antelopes, camels, etc.); Some animals obtain water from food (insects, reptiles, rodents). Fat deposits of desert animals can serve as a kind of water reserve in the body: when fats are oxidized, water is formed (fat deposits in the hump of camels or subcutaneous fat deposits in rodents). Low-permeability skin coverings (for example, in reptiles) protect animals from moisture loss. Many animals have switched to a nocturnal lifestyle or hide in burrows, avoiding the drying effects of low humidity and overheating. Under conditions of periodic dryness, a number of plants and animals enter a state of physiological dormancy - plants stop growing and shed their leaves, animals hibernate. These processes are accompanied by reduced metabolism during dry periods.
abiotic nature biosphere solar
Literature
1. http://burenina.narod.ru/3-2.htm
2. http://ru-ecology.info/term/76524/
4. http://www.ecology-education.ru/index.php?action=full&id=257
5. http://bibliofond.ru/view.aspx?id=484744
Lecture No. 5
Ecological environmental factors. Abiotic factors
General patterns of distribution of levels and regional regimes of environmental factors
Space factors
Radiant energy from the Sun and its significance for organisms
Abiotic factors of the terrestrial environment (temperature, precipitation, humidity, air movement, pressure, chemical factors, fires)
Abiotic factors of the aquatic environment (temperature stratification, transparency, salinity, dissolved gases, acidity)
Abiotic factors of soil cover (lithosphere composition, concepts of “soil” and “fertility”, composition and structure of soils)
Nutrients as an environmental factor
The concept of environmental factor
Classification
Abiotic factors
1. Environmental factor- this is any element of the environment that can have a direct or indirect effect on a living organism at least at one of the stages of its individual development, or any environmental condition to which the organism responds with adaptive reactions.
In general, a factor is a driving force of a process or a condition affecting the body. The environment is characterized by a huge variety of environmental factors, including those that are not yet known. Every living organism throughout its life is under the influence of many environmental factors that differ in origin, quality, quantity, time of exposure, i.e. regime. Thus, the environment is actually a set of environmental factors affecting the body.
But if the environment, as we have already said, does not have quantitative characteristics, then each individual factor (be it humidity, temperature, pressure, food proteins, the number of predators, a chemical compound in the air, etc.) is characterized by measure and number, i.e. That is, it can be measured in time and space (in dynamics), compared with some standard, subjected to modeling, prediction (forecast) and ultimately changed in a given direction. You can only control what has measure and number.
For an enterprise engineer, economist, sanitary doctor or prosecutor's office investigator, the requirement to “protect the environment” does not make sense. And if the task or condition is expressed in quantitative form, in the form of any quantities or inequalities (for example: C i< ПДК i или M i < ПДВ i то они вполне понятны и в практическом, и в юридическом отношении. Задача предприятия - не "охранять природу", а с помощью инженерных или организационных приемов выполнить названное условие, т. е. именно таким путем управлять качеством окружающей среды, чтобы она не представляла угрозы здоровью людей. Обеспечение выполнения этих условий - задача контролирующих служб, а при невыполнении их предприятие несет ответственность.
2. Classification of environmental factors
Any classification of any set is a method of its cognition or analysis. Objects and phenomena can be classified according to various criteria, based on the assigned tasks. Of the many existing classifications of environmental factors, it is advisable to use the following for the purposes of this course (Fig. 1).
All environmental factors can generally be grouped into two large categories: factors of inanimate, or inert, nature, otherwise called abiotic or abiogenic, and factors of living nature - biotic, or biogenic. But in their origin, both groups can be like natural, so anthropogenic, i.e. related to human influence. Sometimes they distinguish anthropic And anthropogenic factors. The first includes only direct human impacts on nature (pollution, fishing, pest control), and the second includes mainly indirect consequences associated with changes in the quality of the environment.
Rice. 1. Classification of environmental factors
In his activities, man not only changes the regimes of natural environmental factors, but also creates new ones, for example, by synthesizing new chemical compounds - pesticides, fertilizers, medicines, synthetic materials, etc. Among the factors of inanimate nature are physical(space, climatic, orographic, soil) and chemical(components of air, water, acidity and other Chemical properties soils, industrial impurities). Biotic factors include zoogenic(influence of animals), phytogenic(influence of plants), microgenic(influence of microorganisms). In some classifications, biotic factors include all anthropogenic factors, including physical and chemical.
Along with the one considered, there are other classifications of environmental factors. Factors are identified dependent and independent on the number and density of organisms. For example, climatic factors do not depend on the number of animals and plants, and mass diseases caused by pathogenic microorganisms (epidemics) in animals or plants are certainly associated with their numbers: epidemics occur when there is close contact between individuals or when they are generally weakened due to lack of food, when possible rapid transmission of pathogens from one individual to another, and also loss of resistance to the pathogen.
The macroclimate does not depend on the number of animals, but the microclimate can change significantly as a result of their life activity. If, for example, insects, with their high numbers in the forest, destroy most of the needles or foliage of trees, then the wind regime, illumination, temperature, quality and quantity of food will change here, which will affect the condition of subsequent generations of the same or other animals living here. Mass reproduction of insects attracts insect predators and insectivorous birds. Harvests of fruits and seeds influence changes in the population of mouse-like rodents, squirrels and their predators, as well as many seed-eating birds.
All factors can be divided into regulating(managers) and adjustable(controlled), which is also easy to understand in connection with the above examples.
The original classification of environmental factors was proposed by A. S. Monchadsky. He proceeded from the idea that all adaptive reactions of organisms to certain factors are associated with the degree of constancy of their influence, or, in other words, with their periodicity. In particular, he highlighted:
1. primary periodic factors (those that are characterized by the correct periodicity associated with the rotation of the Earth: the change of seasons, daily and seasonal changes in illumination and temperature); these factors were originally inherent in our planet and nascent life had to immediately adapt to them;
2. secondary periodic factors (they are derived from the primary ones); these include all physical and many chemical factors, such as humidity, temperature, precipitation, population dynamics of plants and animals, the content of dissolved gases in water, etc.;
3. non-periodic factors that are not characterized by regular periodicity (cyclicity); These are, for example, factors associated with the soil, or various types of natural phenomena.
Of course, only the soil body itself and the underlying soils are “non-periodic”, and the dynamics of temperature, humidity and many other properties of the soil are also associated with primary periodic factors.
Anthropogenic factors are definitely non-periodic. Among such non-periodic factors, first of all, are pollutants contained in industrial emissions and discharges. In the process of evolution, living organisms are able to develop adaptations to natural periodic and non-periodic factors (for example, hibernation, wintering, etc.), and to changes in the content of impurities in water or air, plants and animals, as a rule, cannot acquire and hereditarily fix the corresponding adaptation. True, some invertebrates, for example, herbivorous mites from the class of arachnids, which have dozens of generations a year in closed ground conditions, are capable of forming races resistant to poison by constantly using the same pesticides against them by selecting individuals that inherit such resistance.
It must be emphasized that the concept of “factor” should be approached in a differentiated manner, taking into account that factors can be of both direct (immediate) and indirect action. The differences between them are that the direct factor can be quantified, while the indirect factors cannot. For example, climate or relief can be designated mainly verbally, but they determine the regimes of direct action factors - humidity, daylight hours, temperature, physicochemical characteristics of the soil, etc.
3. Abiotic factors
3.1. General patterns of distribution of levels and regional regimes of environmental factors
The geographical envelope of the Earth (like the General biosphere) is heterogeneous in space; it is differentiated into territories that differ from each other. It is successively divided into physical-geographical zones, geographic zones, intrazonal mountain and plain regions and subregions and subzones, etc.
Physiographic zone- this is the largest taxonomic unit of the geographical envelope, consisting of a number of geographical zones that are similar in heat balance and moisture regime.
There are, in particular, Arctic and Antarctic, subarctic and subantarctic, northern and southern temperate and subtropical, subequatorial and equatorial belts.
Geographical (also known as natural, landscape) zone is a significant part of the physical-geographical belt with special character geomorphological processes, with special types climate, vegetation, soils, flora and fauna.
For example, within the northern hemisphere, the following zones are distinguished: ice, tundra, forest-tundra, taiga, mixed forests of the Russian Plain, monsoon forests of the Far East, forest-steppe, steppe, desert temperate and subtropical zones, Mediterranean, etc. The zones have predominantly (although not always ) are elongated in broad terms and are characterized by similar natural conditions, a certain sequence depending on the latitudinal position. Thus, latitudinal geographic zoning is a natural change in physical-geographical processes, components and complexes from the equator to the poles. It is clear that we are talking primarily about the combination of factors that form the climate.
Zoning is determined mainly by the nature of the distribution of solar energy across latitudes, i.e., with a decrease in its arrival from the equator to the poles and uneven moisture. The position on the zonality of the geographic envelope (and, consequently, the biosphere) was formulated by the famous Russian soil scientist V.V. Dokuchaev.
Along with the latitudinal one, there is also a vertical (or altitudinal) zonation typical for mountainous regions, i.e. a change in vegetation, fauna, soils, climatic conditions as one rises from sea level, associated mainly with a change in the heat balance: the air temperature difference is 0.6-1.0 °C for every 100 m of height.
Of course, in nature, not everything is so unambiguously natural: vertical zoning can be complicated by slope exposure, and latitudinal zoning can have zones elongated in the submeridional direction, as, for example, in the conditions of mountain ranges.
However, in general, the regimes and dynamics of the most important abiotic factors depend on the heat balance, i.e. climate, soil formation processes, types of vegetation, species composition and population dynamics of the animal world, etc.
Geographical zoning is inherent not only to the continents, but also to the World Ocean, within which different zones differ in the amount of incoming water. solar radiation, balances of evaporation and precipitation, water temperature, features of surface and deep currents, and, consequently, the world of living organisms.
3.2. Space factors
The biosphere, as a habitat for living organisms, is not isolated from complex processes occurring in outer space, which are directly related not only to the Sun. Cosmic dust and meteorite matter fall to Earth. The Earth periodically collides with asteroids and comes close to comets. Materials and waves resulting from supernova explosions pass through the Galaxy. Of course, our planet is most closely connected with the processes occurring on the Sun - with the so-called solar activity. The essence of this phenomenon is the transformation of energy accumulated in the magnetic belts of the Sun into the energy of movement of gas masses, fast particles, and short-wave electromagnetic radiation.
The most intense processes are observed in centers of activity, called active regions, in which an intensification of the magnetic field is observed, areas of increased brightness, as well as so-called sunspots, appear. In active regions, explosive releases of energy can occur, accompanied by plasma emissions, the sudden appearance of solar cosmic rays, and an increase in short-wave and radio emission. Changes in the level of flare activity are known to be cyclical, with a typical cycle of 22 years, although fluctuations with a periodicity of 4.3 to 1850 years are known. Solar activity influences a number of life processes on Earth - from the occurrence of epidemics and surges in birth rates to major climatic changes. This was proven back in 1915 by the Russian scientist A.L. Chizhevsky, the founder of a new science - heliobiology (from the Greek helios - Sun), which examines the impact of changes in the activity of the Sun on the Earth's biosphere.
3.3. Radiant energy from the Sun and its significance for organisms
The energy of solar radiation spreads in space in the form electromagnetic waves. About 99% of it is made up of rays with a wavelength of 170-4000 nm, including 48% in the visible part of the spectrum with a wavelength of 400-760 nm, and 45% in the infrared (wavelength from 750 nm to 10~3 m) , about 7% for ultraviolet (wavelength less than 400 nm). In the processes of photosynthesis, photosynthetically active radiation (380-710 nm) plays the most important role.
The amount of solar radiation energy reaching the Earth (to the upper boundary of the atmosphere) is almost constant and is estimated at 1370 W/m2. This value is called the solar constant. However, the arrival of solar radiation energy to the surface of the Earth itself varies significantly depending on a number of conditions: the height of the Sun above the horizon, latitude, state of the atmosphere, etc. The shape of the Earth (geoid) is close to spherical. Therefore, the greatest amount of solar energy is absorbed in low latitudes (equatorial belt), where the air temperature near the earth's surface is usually higher than in middle and high latitudes. The arrival of solar radiation energy in different regions of the globe and its redistribution determine the climatic conditions of these regions.
Passing through the atmosphere, solar radiation is scattered on gas molecules, suspended impurities (solid and liquid), and absorbed by water vapor, ozone, carbon dioxide, and dust particles. Scattered solar radiation partially reaches the earth's surface. His visible part creates light during the day in the absence of direct sunlight, for example in heavy clouds. The total flow of heat to the Earth's surface depends on the sum of direct and diffuse radiation, which increases from the poles to the equator.
The energy of solar radiation is not only absorbed by the Earth's surface, but is also reflected by it in the form of a stream of long-wave radiation. Lighter colored surfaces reflect light more intensely than darker ones. So, clean snow reflects 80-95%, contaminated snow - 40-50, chernozem soil - 5-14, light sand - 35-45, forest canopy - 10-18%. The ratio of the solar radiation flux reflected by the surface to that received is called albedo. Anthropogenic activity significantly influences climatic factors, changing their regimes. You can learn about global problems caused by human activity in the lecture “Global Problems of Humanity” in this course.
Light is the primary source of energy, without which life on Earth is impossible. It participates in photosynthesis, ensuring the creation of organic compounds from inorganic plants of the Earth, and this is its most important energy function. But only a part of the spectrum in the range from 380 to 760 nm, which is called the region of physiologically active radiation (PAR), is involved in photosynthesis. Within it, for photo synthesis, red-orange rays (600-700 nm) and violet-blue (400-500 nm) are of greatest importance, and yellow-green (500-600 nm) are the least important. The latter are reflected, which gives chlorophyll-bearing plants their green color. However, light is not only an energy resource, but also the most important environmental factor, which has a very significant impact on the biota as a whole and on adaptation processes and phenomena in organisms.
Outside the visible spectrum and PAR are the infrared (IR) and ultraviolet (UV) regions. UV radiation carries a lot of energy and has a photochemical effect - organisms are very sensitive to it. IR radiation has significantly less energy and is easily absorbed by water, but some land organisms use it to raise body temperature above ambient.
Light intensity is important for organisms. Plants in relation to illumination are divided into light-loving (heliophytes), shade-loving (sciophytes) and shade-tolerant.
The first two groups have different tolerance ranges within the ecological light spectrum. Bright sunlight is the optimum for heliophytes (meadow grasses, cereals, weeds, etc.), low light is the optimum for shade-loving plants (plants of taiga spruce forests, forest-steppe oak forests, tropical forests). The former cannot stand shadows, the latter cannot stand bright sunlight.
Shade-tolerant plants have a wide range of light tolerance and can grow in both bright light and shade.
Light has a great signaling value and causes regulatory adaptations in organisms. One of the most reliable signals that regulate the activity of organisms over time is the length of the day - the photoperiod.
Photoperiodism as a phenomenon is the body's response to seasonal changes in day length. The length of the day in a given place, at a given time of year, is always the same, which allows plants and animals to determine the time of year at a given latitude, i.e., the time of the beginning of flowering, ripening, etc. In other words, the photoperiod is a kind of “time relay” ”, or “trigger”, including a sequence of physiological processes in a living organism.
Photoperiodism cannot be identified with ordinary external circadian rhythms, caused simply by the change of day and night. However, the daily cyclicity of life in animals and humans turns into the innate properties of the species, that is, it becomes internal (endogenous) rhythms. But unlike the initially internal rhythms, their duration may not coincide with the exact number - 24 hours - by 15-20 minutes, and in connection with this, such rhythms are called circadian (in translation - close to a day).
These rhythms help the body sense time, an ability called the “biological clock.” They help birds navigate by the sun during migration and generally orient organisms in the more complex rhythms of nature.
Photoperiodism, although hereditarily fixed, manifests itself only in combination with other factors, for example, temperature: if it is cold on day X, then the plant blooms later, or in the case of ripening - if the cold comes earlier than day X, then, say, potatoes produce low harvest, etc. In the subtropical and tropical zones, where the length of the day varies little by season, the photoperiod cannot serve as an important environmental factor - it is replaced by an alternation of dry and rainy seasons, and in the highlands the main signaling factor becomes temperature.
Just as on plants, weather conditions affect poikilothermic animals, and homeothermic animals respond to this with changes in their behavior: the timing of nesting, migration, etc. changes.
Man has learned to use the phenomena described above. The length of daylight hours can be changed artificially, thereby changing the timing of flowering and fruiting of plants (growing seedlings in winter and even fruits in greenhouses), increasing the egg production of chickens, etc.
The development of living nature by season occurs in accordance with the bioclimatic law, which bears the name of Hoyakins: the timing of the onset of various seasonal phenomena (phenodate) depends on the latitude, longitude of the area and its altitude above sea level. This means that the further north, east and higher the terrain, the later spring comes and the earlier autumn comes. For Europe, at each degree of latitude, the timing of seasonal events occurs after three days, in North America - on average, after four days for each degree of latitude, at five degrees of longitude and at 120 m above sea level.
Knowledge of phenodata is of great importance for planning various agricultural work and other economic activities.
3.4. Abiotic factors of the terrestrial environment
The abiotic component of the terrestrial environment (land) includes a set of climatic and soil conditions, i.e., many elements that are dynamic in time and space, connected with each other and influencing living organisms.
The peculiarities of the impact on the biosphere from cosmic factors and manifestations of solar activity are that the surface of our planet (where the “film of life” is concentrated) is, as it were, separated from Space by a thick layer of matter in a gaseous state, i.e., the atmosphere. The abiotic component of the terrestrial environment includes a set of climatic, hydrological, soil and ground conditions, i.e., many elements that are dynamic in time and space, interconnected and influencing living organisms. The atmosphere, as a medium that perceives cosmic and solar-related factors, has the most important climate-forming function.
The effect of temperature on organisms
Temperature is the most important limiting factor. The limits of tolerance for any species are the maximum and minimum lethal temperatures, beyond which the species is fatally affected by heat or cold (Fig. 2.). Apart from some unique exceptions, all living things are capable of living at temperatures between 0 and 50 ° C, which is due to the properties of the protoplasm of cells.
In Fig. 2. The temperature limits of life of a species group or population are shown. In the “optimal interval,” organisms feel comfortable, actively reproduce, and the population grows. Towards the extremes of the temperature limit of life - “reduced vital activity” - organisms feel depressed. With further cooling within the “lower limit of resistance” or an increase in heat within the “upper limit of resistance”, organisms enter the “death zone” and die.
This example illustrates common law biological resistance (according to Lamott), applicable to any of the important limiting factors. The value of the “optimal interval” characterizes the “magnitude” of the resistance of organisms, i.e. the value of its tolerance to this factor, or “ecological valency”.
Adaptation processes in animals in relation to temperature led to the emergence of poikilothermic and homeothermic animals. The vast majority of animals are poikilothermic, i.e., the temperature of their own body changes with changes in the temperature of the environment: amphibians, reptiles, insects, etc. A significantly smaller proportion of animals are homeothermic, i.e., they have a constant body temperature, independent of the temperature of the external environment : mammals (including humans) with a body temperature of 36-37 0 C, and birds with a body temperature of 40 ° C.
Rice. 2. General law of biological resistance (according to M. Lamott)
Only homeothermic animals can lead an active life at temperatures below zero. Although poikilotherms can withstand temperatures well below zero, they lose mobility. A temperature of about 40 °C, i.e. even below the protein coagulation temperature, is the limit for most animals.
Temperature plays no less important role in the life of plants. When the temperature rises by 10 °C, the intensity of photosynthesis doubles, but only up to 30-35 °C, then its intensity drops, and at 40-45 °C photosynthesis stops altogether. At 50 °C, most terrestrial plants die, which is associated with the intensification of plant respiration when the temperature rises, and then its cessation at 50 0 C.
Temperature also affects the course of root nutrition in plants: this process is possible only if the soil temperature in the suction areas is several degrees lower than the temperature of the above-ground part of the plant. Violation of this balance entails inhibition of plant life and even death. Morphological adaptations of plants to low temperatures are known, the so-called life forms of plants, for example, epiphytes, phanerophytes, etc.
Morphological adaptations to the temperature conditions of life, and above all, are also observed in animals. Life farms of animals of the same species, for example, can be formed under the influence of low temperatures, from -20 to -40 0 C, at which they are forced to accumulate nutrients and increase body weight: of all tigers, the largest is the Amur tiger, living in the most northern and harsh conditions. This pattern is called Bergmann's rule: in warm-blooded animals, the body size of individuals is, on average, larger in populations living in colder parts of the species' distribution range.
But in the life of animals, physiological adaptations are much more important, the simplest of which is acclimatization - a physiological adaptation to withstand heat or cold. For example, the fight against overheating by increasing evaporation, the fight against cooling in poikilothermic animals by partial dehydration of their body or the accumulation of special substances that lower the freezing point, in homeothermic animals - by changing metabolism.
There are also more radical forms of protection from the cold - migration to warmer regions (bird migration; high-mountain chamois move to lower altitudes for the winter, etc.), wintering - hibernation for the winter (marmot, squirrel, brown bear, the bats: They are able to lower their body temperature to almost zero, slowing down their metabolism and thus the waste of nutrients).
Abiotic environmental factors include the substrate and its composition, humidity, temperature, light and other types of radiation in nature, its composition, and microclimate. It should be noted that temperature, air composition, humidity and light can be conditionally classified as “individual”, and substrate, climate, microclimate, etc. - as “complex” factors.
The substrate (literally) is the site of attachment. For example, for woody and herbaceous forms of plants, for soil microorganisms this is soil. In some cases, substrate can be considered synonymous with habitat (for example, soil is an edaphic habitat). The substrate is characterized by a certain chemical composition, which affects organisms. If the substrate is understood as a habitat, then in this case it represents a complex of characteristic biotic and abiotic factors to which this or that organism adapts.
Characteristics of temperature as an abiotic environmental factor
The role of temperature as an environmental factor comes down to the fact that it affects metabolism: at low temperatures the rate of bioorganic reactions slows down greatly, and at high temperatures it increases significantly, which leads to an imbalance in the course of biochemical processes, and this causes various diseases, and sometimes death.
The influence of temperature on plant organisms
Temperature is not only a factor determining the possibility of plants living in a particular area, but for some plants it affects the process of their development. Thus, winter varieties of wheat and rye, which during germination did not undergo the process of “vernalization” (exposure to low temperatures), do not produce seeds when grown in the most favorable conditions.
To withstand the effects of low temperatures, plants have various adaptations.
1. In winter, the cytoplasm loses water and accumulates substances that have an “antifreeze” effect (monosaccharides, glycerin and other substances) - concentrated solutions of such substances freeze only at low temperatures.
2. The transition of plants to a stage (phase) resistant to low temperatures - the stage of spores, seeds, tubers, bulbs, rhizomes, roots, etc. Woody and shrubby forms of plants shed their leaves, the stems are covered with cork, which has high thermal insulation properties, and antifreeze substances accumulate in living cells.
The effect of temperature on animal organisms
Temperature affects poikilothermic and homeothermic animals differently.
Poikilothermic animals are active only during temperatures that are optimal for their life. During periods of low temperatures, they hibernate (amphibians, reptiles, arthropods, etc.). Some insects overwinter either as eggs or as pupae. The presence of an organism in hibernation is characterized by a state of suspended animation, in which metabolic processes are very inhibited and the body can go without food for a long time. Poikilothermic animals can also hibernate when exposed to high temperatures. Thus, animals in lower latitudes are in burrows during the hottest part of the day, and the period of their active life activity occurs in the early morning or late evening (or they are nocturnal).
Animal organisms hibernate not only due to the influence of temperature, but also due to other factors. Thus, a bear (a homeothermic animal) hibernates in winter due to lack of food.
Homeothermic animals are less dependent on temperature in their life activities, but temperature affects them in terms of the availability (absence) of food supply. These animals have the following adaptations to overcome the effects of low temperatures:
1) animals move from colder areas to warmer ones (bird migrations, mammal migrations);
2) change the nature of the cover (summer fur or plumage is replaced by a thicker winter one; they accumulate a large layer of fat - wild pigs, seals, etc.);
3) hibernate (for example, a bear).
Homeothermic animals have adaptations to reduce the effects of temperatures (both high and low). Thus, a person has sweat glands that change the nature of secretion at elevated temperatures (the amount of secretion increases), the lumen of blood vessels in the skin changes (at low temperatures it decreases, and at high temperatures it increases), etc.
Radiation as an abiotic factor
Both in the life of plants and in the life of animals, various radiations play a huge role, which either enter the planet from the outside (sun rays) or are released from the bowels of the Earth. Here we will mainly consider solar radiation.
Solar radiation is heterogeneous and consists of electromagnetic waves different lengths, and therefore have different energies. Rays of both the visible and invisible spectrum reach the Earth's surface. Rays of the invisible spectrum include infrared and ultra-violet rays, and the rays of the visible spectrum have seven most distinguishable rays (from red to violet). radiation quanta increases from infrared to ultraviolet (that is, ultraviolet rays contain quanta of the shortest waves and the highest energy).
The sun's rays have several environmentally important functions:
1) thanks to the sun's rays, a certain temperature regime, having a latitudinal and vertical zonal character;
In the absence of human influence, the composition of the air may, however, vary depending on the altitude (with altitude, the content of oxygen and carbon dioxide decreases, since these gases are heavier than nitrogen). The air of coastal areas is enriched with water vapor, which contains sea salts in a dissolved state. The air of the forest differs from the air of the fields in the impurities of compounds released by various plants (for example, the air of a pine forest contains a large amount of resinous substances and esters that kill pathogens, so this air is healing for patients with tuberculosis).
The most important complex abiotic factor is climate.
Climate is a cumulative abiotic factor, including a certain composition and level of solar radiation, the associated level of temperature and humidity influence and a certain wind regime. The climate also depends on the nature of the vegetation growing in a given area and on the terrain.
There is a certain latitudinal and vertical climatic zonation on Earth. There are humid tropical, subtropical, sharply continental and other types of climate.
Repeat information about various types climate from a physical geography textbook. Consider the climate features of the area where you live.
Climate as a cumulative factor shapes one or another type of vegetation (flora) and a closely related type of fauna. Big influence human settlements influence the climate. The climate of large cities differs from the climate of suburban areas.
Compare the temperature regime of the city in which you live and the temperature regime of the area where the city is located.
As a rule, the temperature within the city (especially in the center) is always higher than in the region.
Microclimate is closely related to climate. The reason for the emergence of microclimate is differences in the relief in a given territory, the presence of reservoirs, which leads to changes in conditions in different territories of a given climatic zone. Even in a relatively small area summer cottage on its individual parts may occur various conditions for plant growth due to different lighting conditions.