Abiotic. Anthropogenic, biotic and abiotic environmental factors
Introduction
Main abiotic factors and their characteristics
Literature
Introduction
Abiotic environmental factors are components and phenomena of inanimate, inorganic nature that directly or indirectly affect living organisms. Naturally, these factors act simultaneously, which 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 it is not the same for their different types. It should be noted that this greatly affects the entire ecosystem as a whole, its stability.
Environmental factors, both individually and in combination, when exposed to living organisms, force them to change, adapt to these factors. This ability is called ecological valency or plasticity. The plasticity, or ecological valence, of each species is different and affects the ability of living organisms to survive in conditions of changing environmental factors in different ways. If organisms not only adapt to biotic factors, but can also influence them by changing other living organisms, then this is impossible with abiotic environmental factors: the organism can adapt to them, but is not able to exert any significant feedback on them.
Abiotic environmental factors are conditions that are not directly related to the vital activity of organisms. The most important abiotic factors include temperature, light, water, composition of atmospheric gases, soil structure, composition of biogenic elements in it, terrain, etc. These factors can affect organisms both directly, for example, light or heat, and indirectly, for example, the terrain, which determines the action of direct factors, light, wind, moisture, etc. More recently, the influence of changes in solar activity on biospheric processes has been discovered.
1. Main abiotic factors and their characteristics
Abiotic factors include:
Climatic (influence of temperature, light and humidity);
Geological (earthquake, volcanic eruption, movement of glaciers, mudflows and avalanches, etc.);
Orographic (features of the terrain where the studied organisms live).
Let us consider the action of the main direct acting abiotic factors: light, temperature, and the presence of water. Temperature, light and humidity are the most important environmental factors. These factors naturally change both during the year and day, and in connection with geographic zoning. To these factors, organisms show a zonal and seasonal nature of adaptation.
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 detrimental to all living things, but they are delayed by the ozone layer of the atmosphere. Only a small part of the longer ultraviolet rays (0.300 - 0.400 microns) reaches the Earth's surface. They make up about 10% of radiant energy. These rays have a high chemical activity - at a large dose 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% - solar radiation), reaching the Earth's surface, are of particular importance 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 environmental factors, although there are those for which light is not a prerequisite for existence (soil, cave and deep-sea adaptations to life in the dark). Most animals are able to distinguish the spectral composition of light - have color vision, and in plants, flowers have bright colors to attract pollinating insects.
The human eye does not perceive infrared rays with a wavelength of more than 0.750 microns, but they are a source of thermal energy (45% of radiant energy). These rays are absorbed by the tissues of animals and plants, as a result of which the tissues are heated. Many cold-blooded animals (lizards, snakes, insects) use sunlight to raise their body temperature (some snakes and lizards are ecologically warm-blooded animals). Light conditions associated with the rotation of the Earth have a distinct daily and seasonal periodicity. Almost all physiological processes in plants and animals have a daily rhythm with a maximum and minimum at certain hours: for example, at certain hours of the day, a flower in plants opens and closes, and animals have developed adaptations for night and day life. The length of the day (or photoperiod) is of great importance in the life of plants and animals.
Plants, depending on habitat 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 (beyond optimal brightness) suppresses photosynthesis, so it is difficult to get a high yield of crops rich in protein in the tropics. In temperate zones (above and below the equator), the cycle of development of plants and animals is timed to the seasons of the year: preparation for changing temperature conditions is carried out on the basis of a signal - a change in the length of the day, which is always the same at a certain time of the year in a given place. As a result of this signal, physiological processes are turned on, leading to growth, flowering of plants in spring, fruiting in summer and dropping leaves in autumn; in animals - to molting, accumulation of fat, migration, reproduction in birds and mammals, the onset of the dormant stage in insects. Animals perceive changes in the length of the day with the help of their organs of vision. And plants - with the help of special pigments located in the leaves of plants. Irritations are perceived with the help of 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 only 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. possess biological clock - from unicellular to humans. The biological clock - are also governed by seasonal cycles and other biological phenomena. The biological clock determine the daily rhythm of activity of both whole organisms and processes occurring even at the level of cells, 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, are deeply reflected in the growth, development and other manifestations of the vital activity of animals and plants. There are organisms with a variable body temperature - poikilothermic and organisms with a constant body temperature - homeothermic. Poikilothermic animals are completely dependent on the ambient temperature, while homeothermic animals 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 shellfish can live in hot springs (up to 53 O WITH). For most terrestrial animals and plants, the optimum temperature conditions fluctuate within fairly narrow limits (15-30 O WITH). The upper threshold of the temperature of life is determined by the temperature of protein coagulation, since irreversible protein coagulation (violation of protein structure) occurs at a temperature of about 60 o WITH.
Poikilothermic organisms in the process of evolution have developed various adaptations to changing environmental temperature conditions. The main source of thermal energy in poikilothermic animals is external heat. Poikilothermic organisms have developed various adaptations to low temperatures. Some animals, such as Arctic fish, live permanently at -1.8 o C, contain substances (glycoproteins) in the tissue fluid that prevent the formation of ice crystals in the body; insects accumulate glycerol for these purposes. Other animals, on the contrary, increase the heat production of the body due to the active contraction of the muscles - this is how they increase the body temperature by several degrees. Still others regulate their heat exchange by exchanging heat between the vessels of the circulatory system: the vessels leaving 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 is seen in the fact that many insects, reptiles and amphibians choose places in the sun for heating or change 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 an effective way of maintaining temperature through collective thermoregulation (the temperature in the hive can be maintained at 34-35 o C, necessary for the development of larvae).
Poikilothermic animals are able to adapt to high temperatures. This also happens in different ways: heat transfer can occur due to 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 rate of blood flow through the vessels of the skin increases with increasing temperature).
The most perfect thermoregulation is observed in birds and mammals - homoiothermal 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; feather or hairline; 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 o C, while in mammals it is somewhat lower. 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., is of great importance for animals. They are also able to adapt to low temperatures in several ways: in addition to feather or hair, warm-blooded animals reduce heat loss with the help of trembling (microcontractions of apparently immobile muscles); when brown adipose tissue is oxidized in mammals, additional energy is generated that supports metabolism.
The adaptation of warm-blooded animals to high temperatures is in many ways similar to similar adaptations of cold-blooded ones - sweating and evaporation of water from the mucous membrane of the mouth and upper respiratory tract, in birds - only the last way, since they do not have sweat glands; expansion of blood vessels located close to the surface of the skin, which enhances heat transfer (in birds, this process occurs in non-feathered areas of the body, for example, through a comb). 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 mass). The importance of water in the life of a cell is determined by its physicochemical properties. Due to the polarity, the water molecule is able to be attracted to any other molecules, forming hydrates, i.e. is a solvent. Many chemical reactions can only take place in the presence of water. Water is in living systems thermal buffer , absorbing heat during the transition from a liquid to a gaseous state, thereby protecting unstable cell structures from damage during a short-term release of thermal energy. In this regard, it produces a cooling effect when evaporating from the surface and regulates body temperature. The heat-conducting properties of water determine its leading role as a climate thermostat in nature. Water heats up slowly and cools slowly: in summer and daytime, the water of the seas of oceans and lakes heats up, and at night and in winter it also cools slowly. There is a constant exchange of carbon dioxide between water and air. In addition, water performs a transport function, moving soil substances from top to bottom and vice versa. The role of humidity for terrestrial organisms is due to the fact that precipitation is unevenly distributed on the earth's surface during the year. In arid regions (steppes, deserts), plants obtain water for themselves with the help of a highly developed root system, sometimes very long roots (up to 16 m in camel thorn), reaching the wet layer. The high osmotic pressure of cell sap (up to 60-80 atm), which increases the sucking power of the roots, contributes to the retention of water in the tissues. In dry weather, plants reduce water evaporation: in desert plants, the integumentary tissues of the leaf thicken, or a wax 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 their leaves - saxaul, tamarisk, etc.).
Depending on the requirements for the water regime, the following ecological groups are distinguished among plants:
Hydratophytes - plants constantly living in water;
Hydrophytes - plants only partially submerged in water;
Helophytes - swamp plants;
Hygrophytes - terrestrial plants that live in excessively humid places;
Mesophytes - prefer moderate moisture;
Xerophytes - plants adapted to a constant lack of moisture; among xerophytes distinguish:
Succulents - accumulating water in the tissues of their body (succulent);
Sclerophytes - losing a significant amount of water.
Many desert animals are able to do without drinking water; some can run fast and for a long time, making long migrations to a watering place (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). Hardly permeable skin covers (for example, in reptiles) protect animals from moisture loss. Many animals have become nocturnal or hide in burrows to escape the drying effects of low humidity and overheating. Under conditions of periodic dryness, a number of plants and animals go into a state of physiological dormancy - plants stop growing and shed their leaves, animals hibernate. These processes are accompanied by a reduced metabolism during the period of dryness.
abiotic nature biospheric solar
Literature
1. http://burenina.narod.ru/3-2.htm
http://ru-ecology.info/term/76524/
http://www.ecology-education.ru/index.php?action=full&id=257
http://bibliofond.ru/view.aspx?id=484744
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Recall once again that abiotic factors are properties of inanimate nature that directly or indirectly affect living organisms. Slide 3 shows the classification of abiotic factors.
Temperature is the most important climatic factor. It depends on her metabolic rate organisms and their geographical distribution. Any organism is able to live within a certain range of temperatures. And although for different types of organisms ( eurythermal and stenothermal) these intervals are different, for most of them the zone of optimal temperatures at which vital functions are carried out most actively and efficiently is relatively small. The range of temperatures in which life can exist is approximately 300 C: from -200 to +100 C. But most species and most of their activity are confined to an even narrower temperature range. Some organisms, especially in the resting stage, can exist at least for a while, at very low temperatures. Certain types of microorganisms, mainly bacteria and algae, are able to live and multiply at temperatures close to the boiling point. The upper limit for hot spring bacteria is 88 C, for blue-green algae it is 80 C, and for the most resistant fish and insects it is about 50 C. As a rule, the upper limits of the factor are more critical than the lower ones, although many organisms near the upper limits of the tolerance range function more efficiently.
In aquatic animals, the range of temperature tolerance is usually narrower than in terrestrial animals, since the range of temperature fluctuations in water is less than on land.
From the point of view of the impact on living organisms, temperature variability is extremely important. A temperature ranging from 10 to 20 C (averaging 15 C) does not necessarily affect the body in the same way as a constant temperature of 15 C. The vital activity of organisms, which in nature are usually exposed to variable temperatures, is completely or partially suppressed or slowed down by constant temperature. With the help of variable temperature, it was possible to accelerate the development of grasshopper eggs by an average of 38.6% compared to their development at a constant temperature. It is not yet clear whether the accelerating effect is due to temperature fluctuations themselves or to enhanced growth caused by a short-term increase in temperature and an uncompensated slowdown in growth when it is lowered.
Thus, temperature is an important and very often limiting factor. Temperature rhythms largely control the seasonal and diurnal activity of plants and animals. Temperature often creates zonation and stratification in aquatic and terrestrial habitats.
Water physiologically necessary for any protoplasm. From an ecological point of view, it serves as a limiting factor both in terrestrial habitats and in aquatic ones, where its amount is subject to strong fluctuations, or where high salinity contributes to the loss of water by the body through osmosis. All living organisms, depending on their need for water, and, consequently, on differences in habitat, are divided into a number of ecological groups: aquatic or hydrophilic- constantly living in water; hygrophilic- living in very humid habitats; mesophilic- characterized by a moderate need for water and xerophilic- living in dry habitats.
Precipitation and humidity are the main quantities measured in the study of 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, leaving a "rain shadow" behind the mountains, contributing 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 coasts where the winds blow from vast inland dry regions 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. The conditions created by the uniform distribution of precipitation are quite different from those produced by precipitation during one season. In this case, animals and plants have to endure periods of prolonged drought. As a rule, uneven distribution of precipitation over the seasons occurs in the tropics and subtropics, where the wet and dry seasons are often well defined. In the tropical zone, the seasonal rhythm of humidity regulates the seasonal activity of organisms in a similar way to the seasonal rhythm of heat and light in the temperate zone. Dew can be a significant, and in places with little rainfall, a very important contribution to total precipitation.
Humidity - a parameter characterizing the content of water vapor in the air. absolute humidity called the amount of water vapor per unit volume of air. In connection with the dependence of the amount of vapor retained by air on temperature and pressure, the concept relative humidity is the ratio of the vapor contained in the air to the saturating vapor at a given temperature and pressure. Since in nature there is a daily rhythm of humidity - an increase at night and a decrease during the day, and its fluctuation vertically and horizontally, this factor, along with light and temperature, plays an important role in regulating the activity of organisms. Humidity changes the effects of temperature altitude. For example, under conditions of humidity close to critical, temperature has a more important limiting effect. Similarly, humidity plays a more critical role if the temperature is close to the limit values. Large reservoirs significantly soften the land climate, since water is characterized by a large latent heat of vaporization and melting. In fact, there are two main types of climate: continental with extreme temperatures and humidity and nautical, which is characterized by less sharp fluctuations, which is explained by the moderating effect of large reservoirs.
The supply of surface water available to living organisms depends on the amount of precipitation in a given area, but these values \u200b\u200bare not always the same. Thus, using underground sources, where water comes from other areas, animals and plants can receive more water than from its intake with precipitation. Conversely, rainwater sometimes immediately becomes inaccessible to organisms.
Sun radiation is electromagnetic waves of various lengths. It is absolutely necessary for living nature, as it is the main external source of energy. The distribution spectrum of solar radiation energy outside the earth's atmosphere (Fig. 6) shows that about half of the solar energy is emitted in the infrared region, 40% in the visible and 10% in the ultraviolet and X-ray regions.
It must be borne in mind that the spectrum of the electromagnetic radiation of the Sun is very wide (Fig. 7) and its frequency ranges affect living matter in different ways. The Earth's atmosphere, including the ozone layer, selectively, that is, selectively in frequency ranges, absorbs the energy of the electromagnetic radiation of the Sun and mainly radiation with a wavelength of 0.3 to 3 microns reaches the Earth's surface. Longer and shorter wavelength radiation is absorbed by the atmosphere.
With an increase in the zenith distance of the Sun, the relative content of infrared radiation increases (from 50 to 72%).
For living matter, qualitative signs of light are important - wavelength, intensity and duration of exposure.
It is known that animals and plants respond to changes in the wavelength of light. Color vision is spotted in different groups of animals: it is well developed in some species of arthropods, fish, birds and mammals, but in other species of the same groups it may be absent.
The rate of photosynthesis varies with the wavelength of light. For example, when light passes through water, the red and blue parts of the spectrum are filtered out, and the resulting greenish light is weakly absorbed by chlorophyll. However, red algae have additional pigments (phycoerythrins) that allow them to harness this energy and live at greater depths than green algae.
In both terrestrial and aquatic plants, photosynthesis is related to light intensity in a linear relationship up to an optimum level of light saturation, followed in many cases by a decrease in photosynthesis at high direct sunlight intensities. In some plants, such as eucalyptus, photosynthesis is not inhibited by direct sunlight. In this case, compensation of factors takes place, as individual plants and entire communities adapt to different light intensities, becoming adapted to the shade (diatoms, phytoplankton) or to direct sunlight.
The length of the day, or photoperiod, is a "time switch" or trigger mechanism that includes a sequence of physiological processes that lead to growth, flowering of many plants, molting and fat accumulation, migration and reproduction in birds and mammals, and the onset of diapause in insects. Some higher plants bloom with an increase in day length (long day plants), others bloom with a shortening of the day (short day plants). In many photoperiod-sensitive organisms, the biological clock setting can be altered by experimentally changing the photoperiod.
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, in addition, it comes from space.
Different types of living organisms differ greatly in their ability to withstand large doses of radiation exposure. For example, a dose of 2 Sv (Ziver) causes the death of the embryos of some insects at the stage of crushing, a dose of 5 Sv leads to the sterility of some insect species, a dose of 10 Sv is absolutely lethal for mammals. As the data of most studies show, rapidly dividing cells are most sensitive to radiation.
The impact of low doses of radiation is more difficult to assess, as they can cause long-term genetic and somatic consequences. For example, irradiation of pine with a dose of 0.01 Sv per day for 10 years caused a slowdown in growth rate, similar to a single dose of 0.6 Sv. An increase in the level of radiation in the environment above the background one leads to an increase in the frequency of harmful mutations.
In higher plants, sensitivity to ionizing radiation is directly proportional to the size of the cell nucleus, or rather to the volume of chromosomes or the content of DNA.
In higher animals no such simple relationship has been found between sensitivity and cell structure; for them, the sensitivity of individual organ systems is more important. Thus, mammals are very sensitive even to low doses of radiation due to the slight damage caused by irradiation to the rapidly dividing hematopoietic tissue of the bone marrow. Even very low levels of chronically acting ionizing radiation can cause the growth of tumor cells in bones and other sensitive tissues, which may not appear until many years after exposure.
Gas composition atmosphere is also an important climatic factor (Fig. 8). Approximately 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases. Due to the lack of oxygen, there was no ozone screen to block the sun's ultraviolet radiation. Over time, due to abiotic processes, oxygen began to accumulate in the planet's atmosphere, and the formation of the ozone layer began. Approximately in the middle of the Paleozoic, oxygen consumption became equal to its formation, during this period the O2 content in the atmosphere was close to the modern one - about 20%. Further, from the middle of the Devonian, fluctuations in the oxygen content are observed. At the end of the Paleozoic, a noticeable decrease in oxygen content and an increase in carbon dioxide content occurred, to about 5% of the current level, which led to climate change and, apparently, served as an impetus for abundant "autotrophic" blooms, which created reserves of fossil hydrocarbon fuels. This was followed by a gradual return to an atmosphere with a low content of carbon dioxide and a high content of oxygen, after which the O2/CO2 ratio remains in a state of so-called oscillatory stationary equilibrium.
At present, the Earth's atmosphere has the following composition: oxygen ~ 21%, nitrogen ~ 78%, carbon dioxide ~ 0.03%, inert gases and impurities ~ 0.97%. Interestingly, the concentrations of oxygen and carbon dioxide are limiting for many higher plants. In many plants, it is possible to increase the efficiency of photosynthesis by increasing the concentration of carbon dioxide, but it is little known that a decrease in oxygen concentration can also lead to an increase in photosynthesis. In experiments on legumes and many other plants, it was shown that lowering the oxygen content in the air to 5% increases the intensity of photosynthesis by 50%. Nitrogen also plays an important role. This is the most important biogenic element involved in the formation of protein structures of organisms. Wind has a limiting effect on the activity and distribution of organisms.
Wind it 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 the growth of plants: 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 action is purely local. Hurricanes and ordinary winds can carry animals and plants over long distances and thereby change the composition of communities.
Atmosphere pressure , apparently, is not a limiting factor of direct action, but it is directly related to weather and climate, which have a direct limiting effect.
Water conditions create a peculiar habitat for organisms, which differs from the terrestrial one primarily in density and viscosity. Density water about 800 times, and viscosity about 55 times higher than that of air. Together with density And viscosity The most important physical and chemical properties of the aquatic environment are: temperature stratification, that is, temperature change along the depth of the water body and periodic temperature changes over time, and transparency water, 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, an important role is played by gas composition aquatic environment. 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 water bodies with a high content of organic matter, oxygen is the limiting factor of paramount importance. Despite the better solubility of oxygen in water compared to nitrogen, even in the most favorable case, water contains less oxygen than air, about 1% by volume. The solubility is affected by the temperature of the water and the amount of dissolved salts: with a decrease in temperature, the solubility of oxygen increases, with an increase in salinity, it decreases. The supply of oxygen in water is replenished due to diffusion from the air and photosynthesis of aquatic plants. Oxygen diffuses into water very slowly, diffusion is facilitated by wind and water movement. As already mentioned, the most important factor that ensures the photosynthetic production of oxygen is the light penetrating into the water column. Thus, the oxygen content in water varies with time of day, season, and location.
The content of carbon dioxide in water can also vary greatly, but carbon dioxide behaves differently from oxygen, and its ecological role is poorly understood. Carbon dioxide is highly soluble in water, in addition, CO2 enters the water, which is formed during respiration and decomposition, as well as from soil or underground sources. Unlike oxygen, carbon dioxide reacts with water:
with the formation of carbonic acid, which reacts with lime, forming CO22- carbonates and HCO3-hydrocarbonates. These compounds maintain the concentration of hydrogen ions at a level close to neutral. A small amount of carbon dioxide in water increases the intensity of photosynthesis and stimulates the development of many organisms. A high concentration of carbon dioxide is a limiting factor for animals, as it is accompanied by a low oxygen content. For example, if the content of free carbon dioxide in the water is too high, many fish die.
Acidity - the concentration of hydrogen ions (pH) - is closely related to the carbonate system. The pH value changes in the range 0? pH? 14: at pH=7 the medium is neutral, at pH<7 - кислая, при рН>7 - alkaline. If the acidity does not approach extreme values, then the communities are able to compensate for changes in this factor - the tolerance of the community to the pH range is very significant. Acidity can serve as an indicator of the overall metabolic rate of a community. Low pH waters 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, while coastal brackish water organisms are generally euryhaline. The salt concentration in the body fluids and tissues of most marine organisms is isotonic with the salt concentration in sea water, so there are no problems with osmoregulation.
Flow not only greatly affects the concentration of gases and nutrients, but also directly acts as a limiting factor. Many river plants and animals are morphologically and physiologically adapted in a special way to maintaining their position in the stream: they have well-defined limits of tolerance to the flow factor.
hydrostatic pressure in the ocean is of great importance. With immersion in water at 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.
Soil is a layer of matter that lies on top of the rocks of the earth's crust. The Russian scientist - naturalist Vasily Vasilyevich Dokuchaev in 1870 was the first to consider the soil as a dynamic, and not an inert environment. 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 as a result of the complex interaction of climate, plants, animals and microorganisms. The Soviet academician soil scientist Vasily Robertovich Williams gave another definition of soil - it is a loose surface horizon of land capable of producing crops. Plant growth depends on the content of essential nutrients in the soil and on its structure.
The composition of the soil includes four main structural components: the mineral base (usually 50-60% of the total soil composition), organic matter (up to 10%), air (15-25%) and water (25-30%).
The mineral skeleton of the soil - is an inorganic component that was formed from the parent rock as a result of its weathering.
Over 50% of the mineral composition of the soil is silica SiO2, from 1 to 25% is accounted for by alumina Al2O3, from 1 to 10% - by iron oxides Fe2O3, from 0.1 to 5% - by oxides of magnesium, potassium, phosphorus, calcium. The mineral elements that form the substance of the soil skeleton vary in size: from boulders and stones to sand grains - particles with a diameter of 0.02-2 mm, silt - particles with a diameter of 0.002-0.02 mm and the smallest clay particles less than 0.002 mm in diameter. Their ratio determines soil mechanical structure . It is of great importance for agriculture. Clays and loams, containing approximately equal amounts of clay and sand, are usually suitable for plant growth, as they contain sufficient nutrients and are able to retain moisture. Sandy soils drain more quickly and lose nutrients through leaching, but they are more beneficial for early harvests because their surface dries out faster in spring than clay soils, resulting in better warming. As soil becomes more stony, its ability to retain water decreases.
organic matter soil is formed by the decomposition of dead organisms, their parts and excrement. Incompletely decomposed organic remains are called litter, and the end product of decomposition - an amorphous substance in which it is no longer possible to recognize the original material - is called humus. Due to its physical and chemical properties, humus improves soil structure and aeration, as well as increases the ability to retain water and nutrients.
Simultaneously with the process of humification, vital elements pass from organic compounds to inorganic ones, for example: nitrogen - into ammonium ions NH4 +, phosphorus - into orthophosphations H2PO4-, sulfur - into sulfations SO42-. This process is called mineralization.
Soil air, like soil water, is located in the pores between soil particles. Porosity increases from clays to loams and sands. Free gas exchange occurs between the soil and the atmosphere, as a result of which the gas composition of both environments has a similar composition. Usually, soil air, due to the respiration of the organisms inhabiting it, has somewhat less oxygen and more carbon dioxide than atmospheric air. Oxygen is essential for plant roots, soil animals, and decomposer organisms that decompose organic matter into inorganic constituents. If there is a waterlogging process, then the soil air is displaced by water and the conditions become anaerobic. The soil gradually becomes acidic as the anaerobic organisms continue to produce carbon dioxide. The soil, if it is not rich in bases, can become extremely acidic, and this, along with the depletion of oxygen reserves, adversely affects soil microorganisms. Prolonged anaerobic conditions lead to the death of plants.
Soil particles hold a certain amount of water around them, which determines the moisture content of the soil. Part of it, called gravitational water, can freely seep into the depths of the soil. This leads to the leaching of various minerals, including nitrogen, from the soil. Water can also be retained around individual colloidal particles in the form of a thin, strong, cohesive film. This water is called hygroscopic. It is adsorbed on the surface of particles due to hydrogen bonds. This water is the least accessible to plant roots and is the last to be retained in very dry soils. The amount of hygroscopic water depends on the content of colloidal particles in the soil, therefore, in clay soils it is much larger - about 15% of the soil mass, than in sandy soils - about 0.5%. As layers of water accumulate around soil particles, it begins to fill first the narrow pores between these particles, and then spreads into ever wider pores. Hygroscopic water gradually turns into capillary water, which is held around soil particles by surface tension forces. Capillary water can rise through narrow pores and tubules from the groundwater level. Plants easily absorb capillary water, which plays the greatest role in their regular water supply. Unlike hygroscopic moisture, this water evaporates easily. Fine-textured soils, such as clays, retain more capillary water than coarse-textured soils, such as sands.
Water is essential for all soil organisms. It enters living cells by osmosis.
Water is also important as a solvent for nutrients and gases absorbed from the aqueous solution by plant roots. It takes part in the destruction of the parent rock underlying the soil, and in the process of soil formation.
The chemical properties of the soil depend on the content of mineral substances that are in it in the form of dissolved ions. Some ions are poisonous for plants, others are vital. The concentration of hydrogen ions in the soil (acidity) pH> 7, that is, on average, close to neutral. The flora of such soils is especially rich in species. Lime and saline soils have pH = 8...9, and peat soils - up to 4. Specific vegetation develops on these soils.
The soil is inhabited by many types of plant and animal organisms that affect its physicochemical characteristics: bacteria, algae, fungi or protozoa, worms and arthropods. Their biomass in various soils is (kg/ha): bacteria 1000-7000, microscopic fungi - 100-1000, algae 100-300, arthropods - 1000, worms 350-1000.
In the soil, the processes of synthesis, biosynthesis are carried out, various chemical reactions of transformation of substances occur, associated with the vital activity of bacteria. In the absence of specialized groups of bacteria in the soil, their role is played by soil animals, which convert large plant residues into microscopic particles and thus make organic substances available to microorganisms.
Organic substances are produced by plants using mineral salts, solar energy and water. Thus, the soil loses the minerals that the plants have taken from it. In forests, some of the nutrients are returned to the soil through leaf fall. Cultivated plants withdraw significantly more nutrients from the soil over a period of time than they return to it. Usually, nutrient losses are replenished by the application of mineral fertilizers, which, in general, cannot be directly used by plants and must be transformed by microorganisms into a biologically available form. In the absence of such microorganisms, the soil loses its fertility.
The main biochemical processes take place in the upper soil layer up to 40 cm thick, since it is home to the largest number of microorganisms. Some bacteria participate in the cycle of transformation of only one element, others - in the cycles of transformation of many elements. If bacteria mineralize organic matter - decompose organic matter into inorganic compounds, then protozoa destroy an excess amount of bacteria. Earthworms, beetle larvae, mites loosen the soil and thus contribute to its aeration. In addition, they process difficult-to-decompose organic substances.
The abiotic factors of the habitat of living organisms also include relief factors (topography) . The influence of topography is closely related to other abiotic factors, since it can strongly influence the local climate and soil development.
The main topographic factor is the height above sea level. With altitude, average temperatures decrease, the daily temperature difference increases, the amount of precipitation, wind speed and radiation intensity increase, atmospheric pressure and gas concentrations decrease. All these factors affect plants and animals, causing vertical zonality.
mountain ranges can serve 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 topographical factor is slope exposure . In the northern hemisphere, south-facing slopes receive more sunlight, so the light intensity and temperature are higher here than at the bottom of the valleys and on the slopes of the northern exposure. The situation is reversed in the southern hemisphere.
An important relief factor is also slope steepness . Steep slopes are characterized by rapid drainage and soil erosion, so the soils here are thin and drier. If the slope exceeds 35b, soil and vegetation usually do not form, but screes of loose material are created.
Among abiotic factors, special attention should be given to fire or fire . Currently, ecologists have come to the unequivocal opinion that fire should be considered as one of the natural abiotic factors along with climatic, edaphic and other factors.
Fires as an environmental factor are of various types and leave behind various consequences. Mounted or wild fires, that is, very intense and uncontrollable, destroy all vegetation and all soil organic matter, while the consequences of ground fires are completely different. Crown fires have a limiting effect on most organisms - the biotic community has to start all over again with what little is left, and many years must pass before the site becomes productive again. Ground fires, on the contrary, have a selective effect: for some organisms, they turn out to be a more limiting factor, for others, a less limiting factor, and thus contribute to the development of organisms with a high tolerance to fires. In addition, small ground fires supplement the action of bacteria by decomposing dead plants and speeding up the transformation of mineral nutrients into a form suitable for use by new generations of plants.
If ground fires occur regularly every few years, there is little deadwood on the ground, this reduces the likelihood of crown fires. In forests that have not burned for more than 60 years, so much combustible bedding and dead wood accumulate that, if it ignites, a crown fire is almost inevitable.
Plants have developed special adaptations to fire, just as they have done to other abiotic factors. In particular, the buds of cereals and pines are hidden from fire in the depths of bunches of leaves or needles. In periodically burnt habitats, these plant species benefit, as fire contributes to their conservation by selectively promoting their prosperity. Broad-leaved species are deprived of protective devices from fire, it is destructive for them.
Thus, fires maintain the stability of only some ecosystems. For deciduous and humid tropical forests, the balance of which developed without the influence of fire, even a ground fire can cause great damage, destroying the upper horizon of the soil rich in humus, leading to erosion and leaching of nutrients from it.
The question "to burn or not to burn" is unusual for us. The effects of burnout can be very different depending on the time and intensity. Due to their negligence, a person often causes an increase in the frequency of wild fires, so it is necessary to actively fight for fire safety in forests and recreation areas. In no case shall a private person have the right to intentionally or accidentally cause a fire in nature. However, it is necessary to know that the use of fire by specially trained people is part of proper land use.
For abiotic conditions, all considered laws of the impact 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 peculiarity of the abiotic conditions of each region.
Populations are concentrated in a certain area and cannot be distributed everywhere with the same density, since they have a limited range of tolerance in relation to environmental factors. Consequently, each combination of abiotic factors is characterized by its own types of living organisms. Many options for combinations of abiotic factors and species of living organisms adapted to them determine the diversity of ecosystems on the planet.
During the lesson, a computer presentation is used, containing the main provisions of the material presented, tables, examples, illustrations. In advance, individual students are given the task to prepare messages on certain sections of the topic of the lesson. Presentation materials and prepared messages are used in the preparation of tasks for the verification work.
During the classes
Teacher. All living organisms inhabiting the Earth are influenced by environmental factors. Environmental factors are individual properties or elements of the environment that directly or indirectly affect living organisms during at least one of the stages of individual development. Environmental factors are diverse. They can be divided according to the type of influence on organisms, according to the degree of variability over time, according to the duration of action. But usually, environmental factors are divided on the basis of their origin into abiotic, biotic and anthropogenic.
(The screen shows a classification scheme for environmental factors..)
Organisms react differently to the effects of abiotic factors. Some bacteria are able to live in the most extreme conditions - in geysers, hydrogen sulfide springs, in very salty water, at the greatest depths of the oceans, very deep in the soil, in the ice of Antarctica, in the bodies of living organisms. And some planktonic organisms in the ocean die at the slightest change in temperature or salinity of the surrounding water. Various factors are important for organisms. For example, for the larvae of the cockchafer developing in the soil, such an important factor as a whole, as light, is practically of no importance.
From an extensive list of abiotic factors, we will consider temperature, light and humidity - their influence is very important for most living organisms on the planet.
Temperature
Teacher. The temperature on land can vary in different parts of the globe from +50 °C to -50 °C, rarely reaching higher or lower values, for example, during the day in deserts or in winter in some areas of Eastern Siberia, the Arctic and Antarctic. The water temperature in the World Ocean is usually in the range from +2 °С to +27 °С. Accordingly, most plants and animals are able to exist in a rather narrow temperature range. However, certain types of bacteria can live and multiply in hot springs at temperatures above +80 °C. Other organisms are able to survive significant changes in temperature while in a state of rest or suspended animation. For example, spores of microorganisms withstand cooling down to -200 °C.
(The screen shows different groups of animals depending on their relationship to temperature changes.)
Student Message
There are animal organisms with a constant body temperature (warm-blooded - birds and mammals) and with a non-constant body temperature (cold-blooded - fish, amphibians, reptiles, all invertebrate animals).
To protect against hypothermia and overheating, organisms have developed certain adaptations. For example, with the onset of winter, plants go into a state of winter dormancy. Many animals hibernate. Their metabolic rate is sharply reduced. In preparation for winter, a lot of fat and carbohydrates are stored in the tissues of animals, the amount of water in the cells decreases, sugars and glycerin accumulate, which prevents freezing. This increases the frost resistance of wintering organisms.
In the hot season, on the contrary, physiological mechanisms are activated that protect against overheating. In plants, the evaporation of moisture through the stomata increases, which leads to a decrease in leaf temperature. In animals, the evaporation of water through the respiratory system and skin increases.
The ability to maintain a constant body temperature in birds and mammals is associated with an intensive metabolism, which, in turn, is possible due to the four-chambered heart and the complete separation of arterial and venous blood flow, due to the supply of tissues with oxygenated arterial blood. Feather or hair cover protects from heat loss of birds and mammals. Those species that live in a constantly hot climate have special adaptations for heat dissipation. For example, elephants have a large auricle, which acts as a heat exchanger.
Due to the maintenance of a constant body temperature, birds and animals can remain active during sudden changes in temperature and live in almost all regions of the globe.
Light
Teacher. Light and the process of photosynthesis associated with it provide all the life processes that take place on Earth. For photosynthesis, the wavelength of the perceived radiation, its duration and intensity are important.
(The screen shows a diagram of the spectrum of sunlight.)
Plants in relation to light are divided into light-loving, shade-loving and shade-tolerant. Shade-loving plants grow in low light conditions, such as under a forest canopy. Shade-tolerant are able to exist both in conditions of good lighting and in shading.
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Student Message
An important role in the regulation of the activity of living organisms and their development is played by the duration of daylight hours - photoperiod. In temperate latitudes, the cycle of development of animals and plants is timed to the seasons of the year, and the signal for preparing organisms for temperature changes is precisely the length of daylight hours, which, unlike other factors, is always constant for each place and time. Photoperiodism is a trigger mechanism that includes physiological processes that lead to plant growth and flowering in spring, fruiting in summer, and leaf shedding in autumn. In animals, changes in day length are associated with reproduction, seasonal migrations (for example, bird flights), fat accumulation, and preparation for the winter dormancy stage.
In addition to seasonal changes, daily changes in the illumination regime are also important. The change of day and night determines the daily rhythm of the physiological activity of organisms. An important adaptation that ensures the survival of an individual is a kind of "biological clock", the ability to sense time.
Student Message
Plants have a phenomenon called phototropism, is a change in the position of plant parts during the day, depending on the position of the light source. The leaves of plants turn away from excess light, while in shade-tolerant species, on the contrary, they turn towards it. In this way, the assimilating organs try to assume a position in which the plant will receive the optimal amount of light.
In some animals and unicellular organisms, there is also a movement towards the highest or lowest illumination (positive or negative phototaxis) to select the most suitable habitat.
Student Message
For animals, including humans, light is primarily informational. Many mammals and birds receive the vast majority of information through the organs of vision. Most organisms need light to navigate in space. Even the simplest organisms have light-sensitive organelles in their cells. With their dance, the bees show their brothers the way of flight to the source of food. It has been established that the dance figures (figures of eight) are oriented with respect to the sun.
During spring and autumn migrations, birds are guided by the stars and the sun. In habitats where there is very little or no light at all (in caves, in the depths of the ocean), and sometimes during the nocturnal lifestyle, some animals (fish, cephalopods, insects, crustaceans) may have adaptations for bioluminescence- the ability to glow to attract prey, individuals of the opposite sex, scare away enemies, etc.
Humidity
Teacher. Water is a necessary component of the cell, therefore its quantity in certain habitats is a limiting factor for plants and animals and determines the nature of the flora and fauna of a given area.
(Representatives of different groups of plants with different habitats are shown on the screen.)
Depending on soil moisture, the species composition of vegetation changes. As the soil dries out, forests give way to forest-steppe vegetation, then steppe and desert vegetation. Excess moisture in the soil leads to waterlogging and the appearance of marsh vegetation. Precipitation during the year can fall unevenly, living organisms have to endure long droughts. The intensity of the development of the vegetation cover and, accordingly, the intensity of feeding of ungulates depend on the rainy season.
Plants and animals have developed adaptations to live in conditions of water scarcity. For example, plants from dry habitats have developed a powerful root system, thickened leaf cuticle, leaf blades are reduced or turned into needles and spines, which reduces evaporation. Growth stops during dry periods. Cacti and some other plants (succulents) store moisture in their stems. In deserts and semi-deserts, by the beginning of summer, after a short flowering, ephemeral plants shed their leaves, their ground parts die off, and bulbs and rhizomes remain until the next season. So these plants survive a period of drought.
In the deserts and small animals - arthropods, snakes, turtles, rodents can fall into summer hibernation, sometimes turning into winter, until the next season.
Student Message
With all the variety of forms and mechanisms of adaptation of living organisms to the effects of adverse environmental factors, they can be grouped into three main ways: active, passive, and avoidance of adverse effects. All these paths take place in relation to any environmental factor, whether it be light, heat or humidity.
active path- strengthening of resistance, development of regulatory abilities that make it possible to go through the life cycle and give offspring, despite deviations from optimal environmental conditions. This path is characteristic of warm-blooded organisms, but it also manifests itself in a number of higher plants (acceleration of the growth and death of shoots and roots, rapid flowering).
passive way- subordination of the vital functions of the body to external conditions. It consists in the economical use of energy resources with the deterioration of living conditions, increasing the stability of cells and tissues. It manifests itself in a decrease in the intensity of metabolic processes, a slowdown in the rate of growth and development, hibernation, suspended animation of adults or existence in a dormant stage (dehydrated seeds, spores, eggs of some invertebrates that can survive for years under the most unfavorable conditions). It is expressed in plants and cold-blooded animals, in those mammals and birds that are able to hibernate or stupor.
Avoidance of adverse environmental conditions characteristic of all living beings. The passage of life cycles at the most favorable time of the year (active processes - during the growing season, in winter - a state of rest). For plants - the protection of the buds of renewal and young tissues with snow cover, litter; reflection of the sun's rays. For animals - shelters: burrows and nests.
Student Message
Many small plants tolerate low winter temperatures, hibernating under the snow, in the litter layer. With the onset of frost, the branches of the dwarf pine fall to the ground, and in the spring they rise again. The tortuosity of the trunks of stone birches is also interpreted by some researchers as an adaptation of the species to cold. Wriggling, the tree trunk lingers for some time in a warmer surface layer. This takes place both in the European North and in the north of the Far East.
Animals also have several states of rest. Summer hibernation is due to high temperatures and lack of water, winter hibernation is due to cold. Metabolic processes do not always slow down in mammals during winter sleep: in brown and polar bears, cubs are born in winter. Anabiosis is a state of the body in which life processes slow down so much that signs of life may be absent. The body becomes dehydrated and therefore can tolerate very low temperatures. Anabiosis is characteristic of spores, seeds, dried lichens, ants, protozoa.
All animals actively move to places with more favorable temperatures (in the heat - in the shade, on cold days - in the sun), crowd or disperse, during hibernation they curl into a ball, choose or create shelters with a certain microclimate, and are active at certain times of the day.
Teacher. Adapting to abiotic environmental factors, entering into relationships with each other, plants, animals and microorganisms are distributed in space over various environments, forming a wide variety of ecosystems (biogeocenoses), which eventually unite into the Earth's biosphere.
Conclusion: on all living organisms, i.e. plants and animals are affected by abiotic environmental factors (factors of inanimate nature), especially temperature, light and moisture. Depending on the adaptability to the influence of factors of inanimate nature, plants and animals are divided into various ecological groups.
To consolidate the acquired knowledge, a test work is carried out (5–7 minutes).
Each student receives a sheet with test-type tasks based on the material of the lesson. After completing the task, the sheets are collected.
Task options
Exercise 1. From the listed animals, select warm-blooded (that is, with a constant body temperature) and cold-blooded: crocodile, viper, monitor lizard, turtle, carp, hare, titmouse.
Task 2. Choose from the proposed plants light-loving, shade-loving and shade-tolerant.
Chamomile, spruce, medicinal dandelion, cornflower, meadow sage, steppe feather grass, bracken fern.
Additional Information:
1) light-loving - have small leaves, strongly branching shoots, a lot of pigment, such as cereals (an increase in light intensity beyond the optimum inhibits photosynthesis, so it is difficult to get good crops in the tropics);
2) shade-loving - the leaves are thin, large, arranged horizontally, with fewer stomata;
3) shade-tolerant - plants capable of living in conditions of good lighting, and in shading conditions.
Task 3. Select plants related to:
1) aquatic plants;
2) water plants;
3) land plants;
4) plants of dry and very dry places.
Buttercup caustic, cornflower, cactus, white water lily, aloe.
What plants are called succulents?
Task 4. Select animals that are diurnal, nocturnal, and crepuscular.
Owl, lizard, leopard, okapi, polar bear, bat, butterfly.
Task 5. Select animals related to:
1) moisture-loving animals;
2) animals of the intermediate group (aquatic-terrestrial group);
3) dry-loving animals.
Varan, seal, camel, penguins, giraffes, capybara, squirrel, clownfish, beaver.
LITERATURE
Dolnik V.R., Kozlov M.A. Mammals. Atlas. - M .: Education, 2005.
An illustrated encyclopedia of animals. - M .: TERRA - Book Club, 1999.
Kamensky A.A., Kriksunov E.A., Pasechnik V.V. Biology. Introduction to general biology and ecology. – M.: Bustard, 2005.
Fedoros E.I., Nechaeva G.A. Ecology in experiments: a textbook for students in grades 10–11 of educational institutions. – M.: Ventana-Graf, 2007.
Fedoros E.I., Nechaeva G.A. Ecology in experiments: a workshop for students in grades 10–11 of educational institutions. – M.: Ventana-Graf, 2007.
Introduction
Every day you, hurrying about your business, walk down the street, shivering from the cold or sweating from the heat. And after a working day, go to the store, buy food. Leaving the store, hastily stop a passing minibus and powerlessly descend to the nearest empty seat. For many, this is a familiar way of life, isn't it? Have you ever thought about how life goes on in terms of ecology? The existence of man, plants and animals is possible only through their interaction. It does not do without the influence of inanimate nature. Each of these types of influence has its own designation. So, there are only three types of environmental impact. These are anthropogenic, biotic and abiotic factors. Let's look at each of them and its impact on nature.
1. Anthropogenic factors - the impact on the nature of all forms of human activity
When this term is mentioned, not a single positive thought comes to mind. Even when people do something good for animals and plants, it is because of the consequences of previously done bad things (for example, poaching).
Anthropogenic factors (examples):
- Drying out swamps.
- Fertilization of fields with pesticides.
- Poaching.
- Industrial waste (photo).
Conclusion
As you can see, basically a person only harms the environment. And because of the increase in economic and industrial production, even environmental protection measures instituted by rare volunteers (the creation of reserves, environmental rallies) are no longer helping.
2. Biotic factors - the influence of wildlife on a variety of organisms
Simply put, this is the interaction of plants and animals with each other. It can be both positive and negative. There are several types of such interaction:
1. Competition - such relationships between individuals of the same or different species, in which the use of a certain resource by one of them reduces its availability to others. In general, during competition, animals or plants fight among themselves for their piece of bread.
2. Mutualism - such a relationship in which each of the species receives a certain benefit. Simply put, when plants and / or animals harmoniously complement each other.
3. Commensalism is a form of symbiosis between organisms of different species, in which one of them uses the dwelling or the host organism as a place of settlement and can eat the remains of food or products of its vital activity. At the same time, it does not bring any harm or benefit to the owner. In general, a small inconspicuous addition.
Biotic factors (examples):
Coexistence of fish and coral polyps, flagellar protozoa and insects, trees and birds (eg woodpeckers), starlings and rhinos.
Conclusion
Despite the fact that biotic factors can be harmful to animals, plants and humans, there are also very great benefits from them.
3. Abiotic factors - the impact of inanimate nature on a variety of organisms
Yes, and inanimate nature also plays an important role in the life processes of animals, plants and humans. Perhaps the most important abiotic factor is the weather.
Abiotic factors: examples
Abiotic factors are temperature, humidity, illumination, salinity of water and soil, as well as the air environment and its gas composition.
Conclusion
Abiotic factors can harm animals, plants and humans, but still they mostly benefit them.
Outcome
The only factor that does not benefit anyone is anthropogenic. Yes, it also does not bring anything good to a person, although he is sure that he is changing nature for his own good, and does not think about what this “good” will turn into for him and his descendants in ten years. Man has already completely destroyed many species of animals and plants that had their place in the world ecosystem. The biosphere of the Earth is like a movie in which there are no minor roles, they are all the main ones. Now imagine that some of them were removed. What happens in the film? This is how it is in nature: if the smallest grain of sand disappears, the great building of Life will collapse.
Abiotic factors
Abiotic factors - factors of inanimate nature, physical and chemical in nature. These include: light, temperature, humidity, pressure, salinity (especially in the aquatic environment), mineral composition (in the soil, in the soil of reservoirs), the movement of air masses (wind), the movement of water masses (currents), etc. The combination of various abiotic factors determines the distribution of species of organisms in different regions of the globe. Everyone knows that one or another biological species is not found everywhere, but in areas where there are conditions necessary for its existence. This, in particular, explains the geographic confinement of various species on the surface of our planet.
As noted above, the existence of a particular species depends on a combination of many different abiotic factors. Moreover, for each species, the significance of individual factors, as well as their combinations, is very specific.
Light is essential for all living organisms. Firstly, because it is practically the only source of energy for all living things. Autotrophic (photosynthetic) organisms - cyanobacteria, plants, converting the energy of sunlight into the energy of chemical bonds (in the process of synthesis of organic substances from minerals), ensure their existence. But in addition, the organic substances created by them serve (in the form of food) as a source of energy for all heterotrophs. Secondly, light plays an important role as a factor regulating lifestyle, behavior, and physiological processes occurring in organisms. Let us recall such a well-known example as the autumn dropping of leaves from trees. The gradual reduction of daylight hours triggers a complex process of physiological restructuring of plants in anticipation of a long winter period.
Changes in daylight hours during the year are of great importance for animals of the temperate zone. Seasonality determines the reproduction of many of their species, the change of plumage and fur cover, horns in ungulates, metamorphosis in insects, migration of fish and birds.
No less important abiotic factor than light is temperature. Most living beings can only live in the range from -50 to +50 °C. And mainly in the habitats of organisms on Earth, temperatures do not go beyond these limits. However, there are species that have adapted to existence at very high or low temperatures. So, some bacteria, roundworms can live in hot springs with temperatures up to +85 °C. In the conditions of the Arctic and Antarctica, there are different types of warm-blooded animals - polar bears, penguins.
Temperature as an abiotic factor can significantly affect the rate of development, the physiological activity of living organisms, since it is subject to daily and seasonal fluctuations.
Other abiotic factors are no less important, but to varying degrees for different groups of living organisms. So, for all terrestrial species, humidity plays a significant role, and for aquatic species, salinity. The fauna and flora of the islands in the oceans and seas are significantly affected by the wind. For the inhabitants of the soil, its structure is important, that is, the size of the soil particles.
Biotic and anthropogenic factors
Biotic factors(living nature factors) are various forms of interaction between organisms of both the same and different species.
Relationships between organisms of the same species are more likely to be competition and quite sharp. This is due to their identical needs - in food, territorial space, in light (for plants), in nesting places (for birds), etc.
Often in the relationship of individuals of the same species, there is also cooperation. The herd, herd way of life of many animals (ungulates, seals, monkeys) allows them to successfully defend themselves from predators and ensure the survival of their cubs. Wolves are an interesting example. They have a change of competitive relations to cooperative ones during the year. In the spring and summer, wolves live in pairs (male and female), raise offspring. At the same time, each pair occupies a certain hunting territory that provides them with food. There is fierce territorial competition between couples. In winter, wolves gather in packs and hunt together, and a rather complex “social” structure develops in a wolf pack. The transition from competition to cooperation is due here to the fact that in the summer there are many prey (small animals), and in winter only large animals (moose, deer, wild boars) are available. The wolf alone cannot cope with them, so a pack is formed for a successful joint hunt.
The relationship of organisms of different species very varied. In those that have similar needs (for food, nesting sites), there is competition. For example, between gray and black rats, red cockroach and black. Not very often, but between different species it adds up cooperation like a bird market. Numerous birds of small species are the first to notice the danger, the approach of a predator. They raise the alarm, and large, strong species (for example, herring gulls) actively attack the predator (arctic fox) and drive it away, protecting both their nests and nests of small birds.
Widespread in species relationships predation. In this case, the predator kills the prey and eats it entirely. Herbivory is closely related to this method: here, too, individuals of one species eat representatives of another (sometimes, however, not completely eating the plant, but only partially).
At commensalism the symbiont benefits from cohabitation, and the host is not harmed, but it does not receive any benefit. For example, a pilot fish (commensal), living near a large shark (owner), has a reliable protector, and food falls to it “from the table” of the owner. The shark simply does not notice its "freeloader". Commensalism is widely observed in animals leading an attached lifestyle - sponges, coelenterates (Fig. 1).
Rice. 1.Sea anemone on a shell occupied by a hermit crab
The larvae of these animals settle on the shell of crabs, the shell of mollusks, and the developed adult organisms use the host as a "vehicle".
Mutualistic relationships are characterized by mutual benefit for both the mutualist and the owner. Widely known examples of this are intestinal bacteria in humans (“supplying” their host with the necessary vitamins); nodule bacteria - nitrogen fixers - living in the roots of plants, etc.
Finally, two species that exist in the same territory (“neighbors”) may not interact with each other in any way. In this case, one speaks of neutralism no relationship between species.
Anthropogenic factors - factors (affecting living organisms and ecological systems) resulting from human activities.