These are factors that directly or indirectly affect the body inanimate nature- light, temperature, humidity, chemical composition of the air, water and soil environment, etc. (i.e., properties of the environment, the occurrence and impact of which do not directly depend on the activity 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 the vital needs of organisms.
The biological effect of sunlight is determined by its spectral composition [show] ,
The spectral composition of sunlight is divided into
- infrared rays (wavelength more than 0.75 microns)
- visible rays (0.40-0.75 µm) and
- ultra-violet rays(less than 0.40 microns)
Different parts of the solar spectrum have unequal biological effects.
Infrared, or thermal, rays carry the bulk of thermal energy. They account for about 49% of the radiant energy that is perceived by living organisms. Thermal radiation is well absorbed by water, the amount of which in organisms is quite large. This leads to heating of the entire body, which is of particular importance for cold-blooded animals (insects, reptiles, etc.). In plants, the most important function of infrared rays is to carry out transpiration, through which excess heat is removed from the leaves by water vapor, as well as to create optimal conditions for the entry of carbon dioxide through the stomata.
Visible spectrum make up about 50% of the radiant energy reaching the Earth. This energy needed by plants for photosynthesis. However, only 1% of it is used for this, the rest is reflected or dissipated in the form of heat. This part of the spectrum has led to the appearance of many important adaptations in plant and animal organisms. In green plants, in addition to the formation of a light-absorbing pigment complex, with the help of which the process of photosynthesis is carried out, bright colors of flowers have appeared, which helps attract pollinators.
For animals, light mainly plays an informational role and is involved in the regulation of many physiological and biochemical processes. Already the simplest have photosensitive organelles (the light-sensitive ocellus in green euglena), and the reaction to light is expressed in the form of phototaxis - movement towards the highest or lowest illumination. Starting with the coelenterates, almost all animals develop light-sensitive organs of various structures. There are nocturnal and crepuscular animals (owls, the bats etc.), as well as animals living in constant darkness (mole cricket, roundworm, mole, etc.).
Ultraviolet part characterized by the highest quantum energy and high photochemical activity. With the help of ultraviolet rays with a wavelength of 0.29-0.40 microns, the biosynthesis of vitamin D, retinal pigments, and skin is carried out in the body of animals. These rays are best perceived by the visual organs of many insects; in plants they have a formative effect and contribute to the synthesis of some biologically active compounds (vitamins, pigments). Rays with a wavelength of less than 0.29 microns have a detrimental effect on living things.
Intensity [show] ,
Plants, whose life activity is entirely dependent on light, develop various morphostructural and functional adaptations to the light regime of their habitats. Based on their requirements for lighting conditions, plants are divided into the following environmental groups:
- Light-loving (heliophytes) plants open habitats, growing successfully only in conditions of full sunlight. They are characterized by a high intensity of photosynthesis. These are early spring plants of steppes and semi-deserts (goose onions, tulips), plants of treeless slopes (sage, mint, thyme), cereals, plantain, water lily, acacia, etc.
- Shade-tolerant plants characterized by a wide ecological amplitude to the light factor. They grow best in high light conditions, but are able to adapt to varying levels of shade. These are woody (birch, oak, pine) and herbaceous (wild strawberry, violet, St. John's wort, etc.) plants.
- Shade-loving plants (sciophytes) They do not tolerate strong lighting, they grow only in shaded areas (under the forest canopy), and never grow in open areas. In clearings with strong lighting, their growth slows down and sometimes they die. Such plants include forest grasses - ferns, mosses, wood sorrel, etc. Adaptation to shading is usually combined with the need for a good water supply.
Daily and seasonal frequency [show] .
Daily periodicity determines the processes of growth and development of plants and animals, which depend on the length of daylight hours.
The factor that regulates and controls the rhythm of the daily life of organisms is called photoperiodism. It is the most important signaling factor allowing plants and animals to “measure time” - the ratio between the duration of the period of illumination and darkness during the day, and determine the quantitative parameters of illumination. In other words, photoperiodism is the reaction of organisms to the change of day and night, which manifests itself in fluctuations in the intensity of physiological processes - growth and development. It is the length of day and night that changes very precisely and naturally throughout the year, regardless of random factors, invariably repeating from year to year, therefore organisms in the process of evolution coordinated all stages of their development with the rhythm of these time intervals.
In the temperate zone, the property of photoperiodism serves as a functional climatic factor that determines the life cycle of most species. In plants, the photoperiodic effect manifests itself in the coordination of the period of flowering and fruit ripening with the period of most active photosynthesis, in animals - in the coincidence of the time of reproduction with the period of abundance of food, in insects - in the onset of diapause and exit from it.
Biological phenomena caused by photoperiodism also include seasonal migrations (flights) of birds, the manifestation of their nesting instincts and reproduction, change of fur in mammals, etc.
According to the required length of the photoperiod, plants are divided into
- long-day plants, which require more than 12 hours of light time for normal growth and development (flax, onions, carrots, oats, henbane, dope, young, potatoes, belladonna, etc.);
- short-day plants - they need at least 12 hours of continuous darkness to bloom (dahlias, cabbage, chrysanthemums, amaranth, tobacco, corn, tomatoes, etc.);
- neutral plants in which the development of generative organs occurs both with long and short days (marigolds, grapes, phlox, lilac, buckwheat, peas, knotweed, etc.)
Long-day plants come mainly from northern latitudes, while short-day plants come from southern latitudes. In the tropical zone, where the length of day and night varies little throughout the year, photoperiod cannot serve as a guide to periodicity. biological processes. It is replaced by alternating dry and wet seasons. Long-day species manage to produce a harvest even in the short northern summer. The formation of a large mass of organic substances occurs in the summer during a fairly long daylight hours, which at the latitude of Moscow can reach 17 hours, and at the latitude of Arkhangelsk - more than 20 hours a day.
The length of the day also significantly affects the behavior of animals. With the onset of spring days, the duration of which progressively increases, birds develop nesting instincts, they return from warm regions (although the air temperature may still be unfavorable), and begin laying eggs; Warm-blooded animals shed.
The reduction in day length in autumn causes opposite seasonal phenomena: birds fly away, some animals hibernate, others grow dense fur, and wintering stages of insects form (despite the still favorable temperature and abundance of food). In this case, a decrease in day length signals living organisms about the imminent onset of the winter period, and they can prepare for it in advance.
In animals, especially arthropods, growth and development also depend on the length of daylight hours. For example, cabbage whites and birch moths develop normally only with long daylight hours, while silkworms, various types of locusts, and moths develop normally only with short daylight hours. Photoperiodism also affects the timing of the onset and termination of the mating season in birds, mammals and other animals; on reproduction, embryonic development of amphibians, reptiles, birds and mammals;
Seasonal and daily changes in illumination are the most accurate clocks, the course of which is clearly regular and has remained virtually unchanged during the last period of evolution.
Thanks to this, it became possible to artificially regulate the development of animals and plants. For example, providing plants in greenhouses, greenhouses or hotbeds with 12-15 hours of daylight allows them to grow vegetables and ornamental plants even in winter, and to accelerate the growth and development of seedlings. Conversely, shading plants in the summer speeds up the appearance of flowers or seeds on late-blooming fall plants.
By extending the day due to artificial lighting in winter, you can increase the egg-laying period of chickens, geese, and ducks, and regulate the reproduction of fur-bearing animals on fur farms. The light factor also plays a huge role in other life processes of animals. First of all, it is a necessary condition for vision, their visual orientation in space as a result of the perception by the organs of vision of direct, scattered or reflected light rays from surrounding objects. Polarized light, the ability to distinguish colors, navigate by astronomical light sources, the autumn and spring migrations of birds, and the navigation abilities of other animals are highly informative for most animals.
Based on photoperiodism, plants and animals in the process of evolution have developed specific annual cycles of periods of growth, reproduction, and preparation for winter, which are called annual or seasonal rhythms. These rhythms manifest themselves in changes in the intensity of the nature of biological processes and are repeated at annual intervals. The coincidence of the periods of the life cycle with the corresponding time of year is of great importance for the existence of the species. Seasonal rhythms provide plants and animals with the most favorable conditions for growth and development.
Moreover, the physiological processes of plants and animals are strictly dependent on the daily rhythm, which is expressed by certain biological rhythms. Consequently, biological rhythms are periodically repeating changes in the intensity and nature of biological processes and phenomena. In plants, biological rhythms are manifested in the daily movement of leaves, petals, changes in photosynthesis, in animals - in temperature fluctuations, changes in the secretion of hormones, the rate of cell division, etc. In humans, daily fluctuations in respiratory rate, pulse, blood pressure, wakefulness and sleep, etc. Biological rhythms are hereditarily fixed reactions, therefore knowledge of their mechanisms is important in organizing human work and rest.
Temperature
One of the most important abiotic factors on which the existence, development and distribution of organisms on Earth largely depends [show] .
The upper temperature limit of life on Earth is probably 50-60°C. At such temperatures, loss of enzyme activity and protein coagulation occurs. However, the general temperature range of active life on the planet is much wider and is limited to the following limits (Table 1)
Table 1. Temperature range of active life on the planet, °C
Among the organisms that can exist at very high temperatures, thermophilic algae are known, which can live in hot springs at 70-80°C. Cruciform lichens, seeds and vegetative organs of desert plants (saxaul, camel thorn, tulips) located in the top layer of hot soil successfully tolerate very high temperatures (65-80°C).
There are many species of animals and plants that can withstand high subzero temperatures. Trees and shrubs in Yakutia do not freeze at minus 68°C. Penguins live in Antarctica at minus 70°C, and polar bears, arctic foxes, and polar owls live in the Arctic. Polar waters with temperatures from 0 to -2°C are inhabited by a variety of flora and fauna - microalgae, invertebrates, fish, whose life cycle constantly occurs in such temperature conditions.
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.
Adaptation methods
- Migration is relocation to more favorable conditions. Whales, many species of birds, fish, insects and other animals migrate regularly throughout the year.
- Numbness is a state of complete immobility, a sharp decrease in vital activity, and cessation of nutrition. It is observed in insects, fish, amphibians, and mammals when the environmental temperature decreases in autumn, winter (hibernation) or when it increases in the summer in deserts (summer hibernation).
- Anabiosis is a state of sharp inhibition of life processes, when visible manifestations of life temporarily cease. This phenomenon is reversible. It is observed in microbes, plants, and lower animals. The seeds of some plants can remain in suspended animation for up to 50 years. Microbes in a state of suspended animation form spores, protozoa form cysts.
Many plants and animals, with appropriate preparation, successfully tolerate extremely low temperatures in a state of deep dormancy or suspended animation. In laboratory experiments, seeds, pollen, plant spores, nematodes, rotifers, cysts of protozoa and other organisms, sperm after dehydration or placement in solutions of special protective substances - cryoprotectants - tolerate temperatures close to absolute zero.
Currently, progress has been made in the practical use of substances with cryoprotective properties (glycerin, polyethylene oxide, dimethyl sulfoxide, sucrose, mannitol, etc.) in biology, agriculture, medicine. In solutions of cryoprotectors it is carried out long-term storage preserved blood, sperm for artificial insemination of farm animals, some organs and tissues for transplantation; protection of plants from winter frosts, early spring frosts, etc. These problems fall within the competence of cryobiology and cryomedicine and are solved by many scientific institutions.
- Thermoregulation. In the process of evolution, plants and animals have developed various mechanisms of thermoregulation:
- in plants
- physiological - the accumulation of sugar in cells, due to which the concentration of cell sap increases and the water content of cells decreases, which contributes to the frost resistance of plants. For example, in dwarf birch and juniper, the upper branches die at excessively low temperatures, while the creeping ones overwinter under the snow and do not die.
- physical
- stomatal transpiration - removing excess heat and preventing burns by removing water (evaporation) from the plant body
- morphological - aimed at preventing overheating: thick pubescence of the leaves to disperse sunlight, a glossy surface to reflect them, reducing the surface absorbing rays - rolling the leaf blade into a tube (feather grass, fescue), placing the leaf edge-on to the sun's rays (eucalyptus), reducing foliage ( saxaul, cactus); aimed at preventing freezing: special forms growth - dwarfism, the formation of creeping forms (wintering under the snow), dark coloring (helps to better absorb heat rays and warm up under the snow)
- in animals
- cold-blooded (poikilothermic, ectothermic) [invertebrates, fish, amphibians and reptiles] - regulation of body temperature is carried out passively by increasing muscle work, the structure and color of the integument, finding places where intense absorption of sunlight is possible, etc., etc. .To. they cannot maintain the temperature regime of metabolic processes and their activity depends mainly on heat coming from outside, and body temperature - on the values of ambient temperature and energy balance (the ratio of absorption and release of radiant energy).
- warm-blooded (homeothermic, endothermic) [birds and mammals] - capable of maintaining a constant body temperature regardless of the temperature of the environment. This property allows many species of animals to live and reproduce at temperatures below zero (reindeer, polar bear, pinnipeds, penguins). In the process of evolution, they have developed two thermoregulation mechanisms, with the help of which they maintain a constant body temperature: chemical and physical. [show]
.
- The chemical mechanism of thermoregulation is ensured by the speed and intensity of redox reactions and is controlled reflexively by the central nervous system. An important role in increasing the efficiency of the chemical mechanism of thermoregulation was played by such aromorphoses as the appearance of a four-chambered heart and the improvement of the respiratory system in birds and mammals.
- The physical mechanism of thermoregulation is ensured by the appearance of heat-insulating covers (feathers, fur, subcutaneous fat), sweat glands, respiratory organs, as well as the development of nervous mechanisms for regulating blood circulation.
A special case of homeothermy is heterothermy - different levels of body temperature depending on the functional activity of the body. Heterothermy is characteristic of animals that fall into hibernation or temporary torpor during unfavorable periods of the year. At the same time, their high body temperature is noticeably reduced due to slow metabolism (gophers, hedgehogs, bats, swift chicks, etc.).
Endurance limits large values of the temperature factor are different in both poikilothermic and homeothermic organisms.
Eurythermic species are able to tolerate temperature fluctuations over a wide range.
Stenothermic organisms live in conditions of narrow temperature limits, being divided into heat-loving stenothermic species (orchids, tea bush, coffee, corals, jellyfish, etc.) and cold-loving ones (elfin cedar, pre-glacial and tundra vegetation, fish of the polar basins, abyssal animals - the areas of greatest ocean depths, etc.).
For each organism or group of individuals there is an optimal temperature zone within which activity is particularly well expressed. Above this zone is a zone of temporary thermal torpor, and even higher is a zone of prolonged inactivity or summer hibernation, bordering on a zone of high lethal temperature. When the latter decreases below the optimum, there is a zone of cold torpor, hibernation and lethal low temperature.
The distribution of individuals in the population, depending on changes in the temperature factor throughout the territory, generally obeys the same pattern. The optimal temperature zone corresponds to the highest population density, and on both sides of it there is a decrease in density up to the boundary of the range, where it is lowest.
The temperature factor over a large area of the Earth is subject to pronounced daily and seasonal fluctuations, which in turn determines the corresponding rhythm of biological phenomena in nature. Depending on the provision of thermal energy in symmetrical areas of both hemispheres of the globe, starting from the equator, the following climatic zones are distinguished:
- tropical zone. The minimum average annual temperature exceeds 16° C, on the coolest days it does not fall below 0° C. Temperature fluctuations over time are insignificant, the amplitude does not exceed 5° C. Vegetation is year-round.
- Subtropical zone. The average temperature of the coldest month is not lower than 4° C, and the warmest is above 20° C. Sub-zero temperatures are rare. There is no stable snow cover in winter. The growing season lasts 9-11 months.
- Temperate zone. The summer growing season and the winter dormant period of plants are well defined. In the main part of the zone there is stable snow cover. Frosts are typical in spring and autumn. Sometimes this zone is divided into two: moderately warm and moderately cold, which are characterized by four seasons.
- Cold zone. The average annual temperature is below O° C, frosts are possible even during a short (2-3 months) growing season. The annual temperature fluctuation is very large.
The pattern of vertical distribution of vegetation, soils, and fauna in mountainous areas is also mainly determined by the temperature factor. In the mountains of the Caucasus, India, and Africa, four or five plant belts can be distinguished, the sequence of which from bottom to top corresponds to the sequence of latitudinal zones from the equator to the pole at the same altitude.
Humidity
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.
Moisture is a necessary condition for the existence of all living organisms on Earth. Life originated in the aquatic environment. Land dwellers are still dependent on water. For many species of animals and plants, water continues to be a habitat. The importance of water in life processes is determined by the fact that it is the main environment in the cell where metabolic processes take place and is the most important initial, intermediate and final product of biochemical transformations. The importance of water is also determined by its quantitative content. Living organisms consist of at least 3/4 water.
In relation to water higher plants are divided into
- hydrophytes - aquatic plants(water lily, arrow leaf, duckweed);
- hygrophytes - inhabitants of excessively moist places (calamus, watch);
- mesophytes - plants normal conditions moisture (lily of the valley, valerian, lupine);
- xerophytes - plants living in conditions of constant or seasonal moisture deficiency (saxaul, camel thorn, ephedra) and their varieties - succulents (cacti, euphorbia).
Adaptations to living in dehydrated environments and environments with periodic lack of moisture An important feature of the main climatic factors (light, temperature, humidity) is their natural variability during the annual cycle and even daily, as well as depending on geographic zonation. In this regard, the adaptations of living organisms also have a regular and seasonal nature. Adaptation of organisms to environmental conditions can be rapid and reversible or quite slow, depending on the depth of exposure to the factor. As a result of their vital activity, organisms are able to change abiotic living conditions. For example, plants of the lower tier find themselves in conditions of less light; the processes of decomposition of organic substances that occur in bodies of water often cause oxygen deficiency for other organisms. Due to the activity of aquatic organisms, temperature and water regimes, the amount of oxygen, carbon dioxide, pH of the environment, the spectral composition of light, etc. change. Air environment and its gas composition
The development of the air environment by organisms began after they reached land. Life in the air required specific adaptations and a high level of organization of plants and animals. Low density and water content, high oxygen content, ease of movement of air masses, sudden changes in temperature, etc. significantly affected the breathing process, water exchange and movement of living beings. The vast majority of terrestrial animals have acquired the ability to fly during evolution (75% of all species of terrestrial animals). Many species are characterized by ansmochoria - dispersal with the help of air currents (spores, seeds, fruits, protozoan cysts, insects, spiders, etc.). Some plants have become wind pollinated. For the successful existence of organisms, not only physical but also Chemical properties air, its content of gas components necessary for life. Oxygen. For the vast majority of living organisms, oxygen is vital. In an oxygen-free environment, only anaerobic bacteria can grow. Oxygen ensures the implementation of exothermic reactions, during which the energy necessary for the life of organisms is released. It is the final electron acceptor, which is split off from the hydrogen atom in the process of energy exchange. Chemically bound state oxygen is part of many very important organic and mineral compounds of living organisms. Its role as an oxidizing agent in the cycle of individual elements of the biosphere is enormous. The only producers of free oxygen on Earth are green plants, which form it during photosynthesis. A certain amount of oxygen is formed as a result of photolysis of water vapor by ultraviolet rays outside the ozone layer. The absorption of oxygen by organisms from the external environment occurs over the entire surface of the body (protozoa, worms) or through special respiratory organs: trachea (insects), gills (fish), lungs (vertebrates).
Oxygen is chemically bound and transported throughout the body by special blood pigments: hemoglobin (vertebrates), hemocyapin (molluscs, crustaceans). Organisms living in conditions of constant lack of oxygen have developed appropriate adaptations: increased oxygen capacity of the blood, more frequent and deeper respiratory movements, large lung volume (in highland dwellers, birds) or a decrease in the use of oxygen by tissues due to an increase in the amount of myoglobin - an oxygen accumulator in the tissues (in inhabitants of the aquatic environment). Due to the high solubility of CO 2 and O 2 in water, their relative content here is higher (2-3 times) than in the air (Fig. 1). This circumstance is very important for hydrobionics, which use either dissolved oxygen for respiration or CO 2 for photosynthesis (aquatic phototrophs). Carbon dioxide. The normal amount of this gas in the air is small - 0.03% (by volume) or 0.57 mg/l. As a result, even small fluctuations in the CO 2 content are significantly reflected in the process of photosynthesis, which directly depends on it. The main sources of CO 2 entering the atmosphere are the respiration of animals and plants, combustion processes, volcanic eruptions, the activity of soil microorganisms and fungi, industrial enterprises and transport. Having the property of absorption in the infrared region of the spectrum, carbon dioxide affects the optical parameters and temperature regime atmosphere, causing the well-known "greenhouse effect". An important environmental aspect is the increase in solubility of oxygen and carbon dioxide in water as its temperature decreases. That is why the fauna of water basins of polar and subpolar latitudes is very abundant and diverse, mainly due to the increased concentration in cold water oxygen. The dissolution of oxygen in water, like any other gas, obeys Henry's law: it is inversely proportional to temperature and stops when the boiling point is reached. IN warm waters In tropical pools, a low concentration of dissolved oxygen limits respiration and, consequently, the vital activity and number of aquatic animals. IN Lately There is a noticeable deterioration in the oxygen regime of many water bodies, caused by an increase in the amount of organic pollutants, the destruction of which requires large amounts of oxygen. Zoning of distribution of living organisms
Geographical (latitudinal) zoning In the latitudinal direction from north to south, the following natural zones are successively located on the territory of the Russian Federation: tundra, taiga, deciduous forest, steppe, desert. Among the climate elements that determine the zonality of the distribution and distribution of organisms, the leading role is played by abiotic factors - temperature, humidity, light conditions. The most noticeable zonal changes are manifested in the nature of vegetation - the leading component of the biocenosis. This, in turn, is accompanied by changes in the composition of animals - consumers and destructors of organic residues in food chains. Tundra- a cold, treeless plain of the northern hemisphere. Its climatic conditions are unsuitable for plant growth and decomposition of organic residues (permafrost, relatively low temperatures even in summer, short periods of above-zero temperatures). Here, unique biocenoses, small in species composition (mosses, lichens), were formed. In this regard, the productivity of the tundra biocenosis is low: 5-15 c/ha of organic matter per year. Zone taiga characterized by relatively favorable soil and climatic conditions, especially for coniferous species. Rich and highly productive biocenoses have formed here. The annual formation of organic matter is 15-50 c/ha. Temperate zone conditions led to the formation of complex biocenoses deciduous forests with the highest biological productivity in the Russian Federation (up to 60 c/ha per year). Varieties of deciduous forests are oak forests, beech-maple forests, mixed forests, etc. Such forests are characterized by well-developed shrub and herbaceous undergrowth, which facilitates the placement of fauna of various types and numbers. Steppes- a natural zone of the temperate zone of the Earth’s hemispheres, which is characterized by insufficient water supply, so herbaceous, mainly cereal vegetation (feather grass, fescue, etc.) predominates here. Animal world diverse and rich (fox, hare, hamster, mice, many birds, especially migratory ones). The steppe zone contains the most important areas for grain production, industrial crops, vegetable crops and livestock. The biological productivity of this natural zone is relatively high (up to 50 c/ha per year). Deserts predominate in Central Asia. Due to low precipitation and high temperatures in summer, vegetation occupies less than half of the territory of this zone and has specific adaptations to dry conditions. The fauna is diverse, its biological features have been discussed before. The annual formation of organic matter in the desert zone does not exceed 5 c/ha (Fig. 107). Salinity of the environment Salinity of the aquatic environment characterized by the content of soluble salts in it. Fresh water contains 0.5-1.0 g/l, and sea water contains 10-50 g/l of salts. The salinity of the aquatic environment is important for its inhabitants. There are animals adapted to live only in fresh water (cyprinids) or only in sea water (herrings). In some fish, individual stages of individual development take place at different water salinities, for example, the common eel lives in fresh water bodies and migrates to the Sargasso Sea to spawn. Such aquatic inhabitants require appropriate regulation of the salt balance in the body.
Mechanisms of regulation of the ionic composition of organisms. Land animals are forced to regulate the salt composition of their liquid tissues to maintain the internal environment in a constant or almost constant chemically unchanged ionic state. The main way to maintain salt balance in aquatic organisms and land plants is to avoid habitats with unsuitable salinity. Such mechanisms must work especially intensely and accurately in migratory fish (salmon, chum salmon, pink salmon, eel, sturgeon), which periodically move from sea water to fresh water or vice versa. Osmotic regulation occurs most simply in fresh water. It is known that in the latter the concentration of ions is much lower than in liquid tissues. According to the laws of osmosis, the external environment enters the cells along a concentration gradient through semi-permeable membranes, and a kind of “dilution” of the internal contents occurs. If such a process were not controlled, the body could swell and die. However, freshwater organisms have organs that remove excess water. The preservation of ions necessary for life is facilitated by the fact that the urine of such organisms is quite dilute (Fig. 2, a). Separation of such a dilute solution from internal fluids probably requires active chemical work specialized cells or organs (kidneys) and their consumption of a significant proportion of the total basal metabolic energy. On the contrary, marine animals and fish drink and absorb only sea water, thereby replenishing its constant release from the body into the external environment, which is characterized by a high osmotic potential. In this case, monovalent ions of salt water are actively removed outward by the gills, and divalent ions by the kidneys (Fig. 2, b). Cells spend quite a lot of energy pumping out excess water, so when salinity increases and water in the body decreases, organisms usually switch to an inactive state - salt anabiosis. This is typical for species that live in periodically drying puddles sea water, estuaries, in the littoral zone (rotifers, amphipods, flagellates, etc.) Salinity of the upper layer earth's crust is determined by the content of potassium and sodium ions in it, and, like the salinity of the aquatic environment, is important for its inhabitants and, first of all, plants that have appropriate adaptation to it. This factor is not accidental for plants; it accompanies them during the evolutionary process. The so-called saline vegetation (solyanka, licorice, etc.) is confined to soils with a high content of potassium and sodium. The top layer of the earth's crust is soil. In addition to soil salinity, other indicators are distinguished: acidity, hydrothermal regime, soil aeration, etc. Together with the relief, these properties earth's surface, called edaphic environmental factors, have an ecological impact on its inhabitants. Edaphic environmental factors Properties of the earth's surface that have an environmental impact on its inhabitants.
Depending on edaphic factors, a number of ecological groups of plants can be distinguished. Based on the reaction to the acidity of the soil solution, they are distinguished:
In relation to the chemical composition of the soil, plants are divided into
In relation to individual batteries
In relation to the mechanical composition
The terrain and the nature of the soil significantly influence the specific movement of animals and the distribution of species whose life activities are temporarily or permanently associated with the soil. The nature of the root system (deep, surface) and the lifestyle of the soil fauna depend on the hydrothermal regime of soils, their aeration, mechanical and chemical composition. The chemical composition of the soil and the diversity of its inhabitants affect its fertility. The most fertile are chernozem soils rich in humus. As an abiotic factor, relief influences the distribution of climatic factors and, thus, the formation of the corresponding flora and fauna. For example, on the southern slopes of hills or mountains there is always a higher temperature, better illumination and, accordingly, less humidity. | |||
Introduction……………………………………………………………………………………….3
Abiotic factors…………………………………………………………………………………4
Biotic factors……………………………………………………………………...... 8
Anthropogenic factors………………………………………………………………………. 9
Laws of the influence of environmental factors on living organisms……………………….11
Conclusion………………………………………………………………………………….. 13
References………………………………………………………………………………………14
Introduction
Despite the variety of environmental factors and the different nature of their origin, there are some general rules and patterns of their impact on living organisms.
For organisms to live, a certain combination of conditions is necessary. If all environmental conditions are favorable, with the exception of one, then this condition becomes decisive for the life of the organism in question. It limits (limites) the development of the organism, therefore it is called limiting factor . Initially, it was found that the development of living organisms is limited by the lack of any component, for example, mineral salts, moisture, light, etc. In the middle of the 19th century, the German organic chemist J. Liebig was the first to experimentally prove that plant growth depends on the nutrient element that is present in relatively minimal quantities. He called this phenomenon the law of the minimum (Liebig's law).
In its modern formulation, the law of the minimum sounds like this: the endurance of an organism is determined by the weakest link in the chain of its environmental needs. However, as it turned out later, not only a deficiency, but also an excess of a factor can be limiting, for example, crop loss due to rain, oversaturation of the soil with fertilizers, etc. The concept that, along with a minimum, a maximum can also be a limiting factor was introduced 70 years after Liebig by the American zoologist W. Shelford, who formulated law of tolerance . According to the law of tolerance, the limiting factor in the prosperity of a population (organism) can be either a minimum or maximum environmental impact, and the range between them determines the amount of endurance (tolerance limit) or the ecological valence of the organism to a given factor.
The favorable range of action of an environmental factor is called the zone of optimum (normal life activity). The more significant the deviation of a factor’s action from the optimum, the more this factor inhibits the vital activity of the population. This range is called the inhibition zone. The maximum and minimum transferable values of a factor are critical points beyond which the existence of an organism or population is no longer possible.
The principle of limiting factors is valid for all types of living organisms - plants, animals, microorganisms and applies to both abiotic and biotic factors.
In accordance with the law of tolerance, any excess of matter or energy turns out to be a pollutant.
The body's tolerance limit changes during the transition from one stage of development to another. Often young organisms turn out to be more vulnerable and more demanding of environmental conditions than adult individuals. The most critical period from the point of view of the influence of various factors is the breeding period: during this period, many factors become limiting. The ecological valency for reproducing individuals, seeds, embryos, larvae, eggs is usually narrower than for adult non-reproducing plants or animals of the same species.
Until now we have been talking about the limit of tolerance of a living organism in relation to one factor, but in nature all environmental factors act together.
The optimal zone and limits of the body's endurance in relation to any environmental factor can shift depending on the combination in which other factors act simultaneously. This pattern is called interactions of environmental factors .
However, mutual compensation has certain limits and it is impossible to completely replace one of the factors with another. It follows from this that all environmental conditions necessary to support life play an equal role and any factor can limit the possibility of existence of organisms - this the law of equivalence of all living conditions .
Abiotic factors
Abiotic factors are components and phenomena of inanimate, inorganic nature that directly or indirectly affect living organisms.
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).
4. Chemical (gas composition of air, salt composition of water, acidity).
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 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 are entirely dependent on the temperature of the environment, while homeothermic animals are able to maintain a constant body temperature regardless of changes in environmental 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 types- rarely above 40-45 oC. Some cyanobacteria and bacteria live at temperatures of 70-90 °C; some mollusks (up to 53 °C) can also live in hot springs. For most terrestrial animals and plants, the optimum temperature conditions fluctuate within rather narrow limits (15-30 °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 oC.
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 oC, 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 oC or more due to increased muscle work. Social insects, especially bees, have developed an effective way of maintaining temperature through collective thermoregulation (the hive can maintain a temperature of 34-35 oC, 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. Most birds have a body temperature slightly above 40 oC, while mammals have a slightly lower body temperature. 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 unevenly on the earth's surface 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 are plants that are only partially submerged 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 are those that 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.
Biotic factors
Biotic factors are the totality of influences of the life activity of some organisms on the life activity of others (intraspecific and interspecific interactions), as well as on the inanimate environment.
A functional system that includes a community of living beings and their habitat is called an ecological system (or ecosystem). In such a system, connections between its components arise primarily on a food basis and on the basis of methods of obtaining energy. According to the method of nutrition, obtaining and using energy, all organisms are divided into autotrophic and heterotrophic. Some ecosystems (for example, soil) often include anaerobic microorganisms. During the feeding process, aerobic heterotrophs decompose organic matter into carbon dioxide, water and mineral salts, which in turn can be reused by autotrophs. In nature, a continuous cycle of nutrients is formed: autotrophs extract the chemicals necessary for life from the environment and, through a series of heterotrophs, return to it again. All processes are carried out due to the influx of energy from the outside - the radiant energy of the Sun is the source of this energy. Therefore, systems that receive energy from the Sun are called open. The cycle of substances arose in the process of evolution, which is an indispensable condition existence of life. The light energy of the Sun is transformed by organisms into other forms: chemical, mechanical and, finally, thermal. In accordance with the laws of thermodynamics, such transformations are always accompanied by the dissipation of part of the energy in the form of heat.
Food chains and trophic levels
In ecological systems, in the process of evolution, chains of interconnected species have developed that successively extract materials and energy from the original food substance. This sequence is called a food chain, and each link is a trophic level. The first trophic level is occupied by autotrophic organisms, or so-called primary producers. Organisms of the second trophic level are called primary consumers, the third - secondary consumers, etc. The last level is usually occupied by decomposers or detritivores. Decomposers are saprophytic organisms that decompose complex organic compounds into relatively simple inorganic substances. Pieces of partially decomposed material are called detritus, and small animals that feed on them are called detritivores (for example: earthworm, woodlice, carrion fly larva, etc.). Below is a description of each link in the food chain, and their sequence is shown in the figure.
In the food chain, green plants are those organisms that create the initial organic matter using the energy of the Sun. Only about 1% of the energy falling on plants is converted into potential energy of chemical bonds of synthesized organic substances and can be used in the future when feeding heterotrophic organisms. When animal organisms consume this food, only 5-20% of the energy of the food goes into the newly built body of the animal, the rest of the energy contained in the green plant is spent on various life processes of the animal, turning into heat and dissipating. When a herbivore is eaten by a predator, part of the accumulated energy is also consumed. Due to the loss of useful energy, food chains cannot be very long; more often than not, such a chain consists of 3-5 links (trophic levels). Therefore, at each subsequent trophic level, the amount of organic matter produced decreases sharply due to energy loss. In typical carnivore food chains, carnivores are larger at each successive trophic level.
Plant material (e.g. nectar) ¨ fly ¨ spider ¨ shrew ¨ owl
There are two types of food chains - grazing and detrital. Above we have given examples of grazing food chains. Another type of food chain is the chain starting with detritus:
Detritus ¨ detritivore ¨ predator
Leaf litter ¨ Earthworm ¨ Blackbird ¨ Sparrowhawk
Ecological pyramids
A simple calculation can be made: if we take as a basis (rounded) that an average of 10% of the energy of the food eaten is transferred into the substance of an animal’s body, then 1 ton of plant mass can produce 100 kg of the mass of a predator. In reality, these figures may be different, since the energy utilization rate varies among different species. A clear pattern emerges, called the rule of the ecological pyramid: the amount of plant matter is several times greater than the total mass of herbivorous animals, and the mass of each subsequent link in the food chain also progressively decreases.
1. The pyramid of numbers reflects the number of individuals at each level of the food chain;
2. Biomass pyramid - the amount of organic matter (biomass) at each level;
3. Energy pyramid - the amount of energy in food.
All these categories, differing in absolute values, have the same focus. Food connections in an ecosystem are not straightforward, since the components of the ecosystem are in complex interactions with each other.
Anthropogenic factors
Anthropogenic factors are a set of environmental factors caused by accidental or intentional human activity during the period of its existence.
Anthropogenic environmental factors, changes introduced into nature by human activity that affect the organic world (see Ecology). By remaking nature and adapting it to his needs, man changes the habitat of animals and plants, thereby influencing their lives. The impact can be indirect and direct. Indirect impact is carried out through changes in landscapes - climate, physical condition and chemistry of the atmosphere and water bodies, the structure of the earth's surface, soils, vegetation and animal population. The increase in radioactivity as a result of the development of the nuclear industry and especially the testing of atomic weapons is of great importance. Man consciously and unconsciously exterminates or displaces some species of plants and animals, spreads others or creates favorable conditions for them. Man has created a largely new environment for cultivated plants and domestic animals, greatly increasing the productivity of developed lands. But this excluded the possibility of the existence of many wild species. The increase in the Earth's population and the development of science and technology have led to the fact that in modern conditions it is very difficult to find areas not affected by human activity (primitive forests, meadows, steppes, etc.). Improper plowing of land and excessive grazing of livestock not only led to the death of natural communities, but also increased water and wind erosion of soils and shallowing of rivers. At the same time, the emergence of villages and cities created favorable conditions for the existence of many species of animals and plants (see Synanthropic organisms). The development of industry did not necessarily lead to the impoverishment of living nature, but often contributed to the emergence of new forms of animals and plants. The development of transport and other means of communication contributed to the spread of both beneficial and many harmful species of plants and animals (see Anthropochory). Direct effects are aimed directly at living organisms. For example, unsustainable fishing and hunting have sharply reduced the numbers of a number of species. The growing force and accelerating pace of changes in nature by man necessitate its protection (see Nature Conservation). Purposeful, conscious transformation of nature by man with penetration into the microcosm and space marks, according to V.I. Vernadsky (1944), the formation of the “noosphere” - the shell of the Earth changed by man.
Laws of the influence of environmental factors on living organisms
Bibliography
1.Blagosklonov K.N., Inozemtsov A.A., Tikhomirov V.N., “Nature Conservation”, M., 1967.
Abiotic environmental factors include the substrate and its composition, humidity, temperature, light and other types of radiation in nature, and 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 ultraviolet rays, and 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 is realized on the surface of the Earth, which has 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 solar radiation, the associated level of temperature and humidity exposure 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.
Review the information about different types of climate from the 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 of a summer cottage, in certain parts of it, different conditions for plant growth may arise due to different lighting conditions.
Environments are determined by climatic conditions, as well as soil and water conditions.
Classification
There are several classifications of abiotic factors. One of the most popular divides them into the following components:
- physical factors (barometric pressure, humidity);
- chemical factors (atmospheric composition, mineral and organic matter in the soil, pH level in the soil and others)
- mechanical factors (wind, landslides, water and soil movements, terrain, etc.)
Abiotic environmental factors significantly influence the distribution of species and determine their range, i.e. a geographical area that is the habitat of certain organisms.
Temperature
Particular importance is given to temperature, as it is the most important indicator. Depending on temperature, abiotic environmental factors differ in thermal zones with which the life of organisms in nature is associated. These are cold, temperate, tropical, and the temperature that is favorable for the life of organisms is called optimal. Almost all organisms are able to live in the range of 0°-50°C.
Depending on their ability to exist in different temperature conditions, they are classified as:
- eurythermic organisms adapted to conditions of sharp temperature fluctuations;
- stenothermic organisms that exist in a narrow temperature range.
Eurythermal organisms are considered to be organisms that live primarily in areas where a continental climate predominates. These organisms are able to withstand severe temperature fluctuations (diptera larvae, bacteria, algae, helminths). Some eurythermal organisms can enter a state of hibernation if the temperature factor “tightens”. Metabolism in this state is significantly reduced (badgers, bears, etc.).
Stenothermic organisms can be found among both plants and animals. For example, most marine animals survive at temperatures up to 30°C.
Animals are divided according to their ability to maintain their own thermoregulation, i.e. constant body temperature, in the so-called poikilothermic and homeothermic. The former can change their temperature, while for the latter it is always constant. All mammals and a number of birds are homeothermic animals. Poikilothermic organisms include all organisms, except some species of birds and mammals. Their body temperature is close to the ambient temperature. During the course of evolution, animals classified as homeothermic have adapted to protect themselves from the cold (hibernation, migration, fur, etc.).
Light
Abiotic environmental factors are light and its intensity. Its importance is especially great for photosynthetic plants. The level of photosynthesis is affected by the intensity, qualitative composition of light, and the distribution of light over time. However, bacteria and fungi are known that can multiply for a long time in complete darkness. Plants are divided into light-loving, heat-tolerant and heat-loving.
For many animals, the length of daylight is important, which affects sexual function, increasing it during long daylight hours and inhibiting it during short ones (autumn or winter).
Humidity
Humidity is a complex factor and represents the amount of water vapor in the air and water in the soil. The lifespan of cells, and, accordingly, the entire organism, depends on the level of humidity. Soil moisture is affected by the amount of precipitation, the depth of water in the soil and other conditions. Moisture is necessary to dissolve minerals.
Abiotic factors of the aquatic environment
Chemical factors are not inferior in importance to physical factors. A large role belongs to the gas and composition of the aquatic environment. Almost all organisms require oxygen, and a number of organisms require nitrogen, hydrogen sulfide or methane.
Physical abiotic environmental factors are gas composition, which is extremely important for those living beings that live in the aquatic environment. The waters of the Black Sea, for example, contain a lot of hydrogen sulfide, which is why this basin is considered not very favorable for many organisms. Salinity is an important component of the aquatic environment. Most aquatic animals live in salt waters, fewer live in fresh waters, and even fewer live in slightly brackish waters. The distribution and reproduction of aquatic animals is influenced by the ability to maintain the salt composition of the internal environment.
According to the latest data, mountainous areas with different morphometric characteristics and specific climates occupy about 36% area of the Earth. Mountainous terrain occupies significant areas in our country.
The influence of relief on climate is great and extremely varied. It has two characteristic features:
1) under the influence of relief features, specific climate features are created within mountainous countries;
2) mountain systems, disrupting the processes of advection of air masses and atmospheric circulation, have a significant impact on the climate and weather of the surrounding areas.
This largely depends on the shape and compositional structure of individual valleys and ridges within the mountains, as well as on the position (meridional or latitudinal) and scale of the mountain system as a whole.
M.A. Petrosyants divides orographic influences on atmospheric processes into three classes:
1) large-scale influences of orography on the formation of the general climatic distribution of air currents and planetary circulation systems;
2) the influence of orography on mesoscale processes, i.e. on the emergence, development, movement of cyclones and anticyclones, aggravation and erosion of atmospheric fronts near mountains (the so-called orographic cyclogenesis and frontogenesis);
3) local orographic influences that determine the appearance of various features in the course of meteorological values associated with specific forms of relief of short extent (valley, slope, pass, etc.).
As a result of these influences, in mountainous areas, great unevenness (spotting) is created in the spatial distribution of clouds, wind, especially precipitation and dangerous weather phenomena. The scale of the impact of relief on atmospheric weather-forming processes is different. Thus, the horizontal influence of mountains, depending on their height and extent, can manifest itself at a distance of up to 500 km or more. For example, the mid-mountain system of the Ukrainian Carpathians has a noticeable impact on the distribution of precipitation in adjacent areas (from 100 to 300 km depending on the direction of the moisture-carrying flow). The vertical influence of large mountain systems (Caucasus, Pamir, Himalayas, etc.) on air flows and the thermal regime of the troposphere can extend up to a height of 10–12 km. As shown by the theoretical studies of Academician A.A. Dorodnitsyn, even relatively small elevations (Donetskaya, Srednerusskaya, etc., 200–400 m above sea level), located among the plain and having a significant horizontal extent, can have an impact on weather-forming processes, which can be traced up to a height of 4 km.
In the mountains The main climate-forming factors, in addition to geographic latitude and atmospheric circulation, are the following relief features:
- altitude above sea level;
- shape (type) of relief;
- exposition;
- steepness of slopes.
Although absolute height is the main one, the various influences of relief forms, slope exposure and the degree of protection of the place sometimes turn out to be so significant that they completely neutralize its role. Due to various influences of the indicated relief factors on atmospheric and radiation processes is formed special type climate, called mountain climate. Even in fairly close areas, local climate variations (microclimates) can be created, manifested in its extreme diversity, as well as vertical zoning.