We begin our acquaintance with ecology, perhaps, with one of the most developed and studied sections - autecology. The attention of autecology focuses on the interaction of individuals or groups of individuals with the conditions of their environment. Therefore, the key concept of autecology is the ecological factor, that is, the environmental factor that affects the body.
No environmental protection measures are possible without studying the optimum effect of one or another factor on a given biological species. In fact, how to protect this or that species, if you do not know what living conditions he prefers. Even the "protection" of such a species as a reasonable person requires knowledge of sanitary and hygienic standards, which are nothing more than the optimum of various environmental factors in relation to a person.
The influence of the environment on the body is called the environmental factor. The exact scientific definition is:
ECOLOGICAL FACTOR - any environmental condition to which the living reacts with adaptive reactions.
An environmental factor is any element of the environment that has a direct or indirect effect on living organisms at least during one of the phases of their development.
By their nature, environmental factors are divided into at least three groups:
abiotic factors - the influence of inanimate nature;
biotic factors - the influence of wildlife.
anthropogenic factors - influences caused by reasonable and unreasonable human activity ("anthropos" - a person).
Man modifies animate and inanimate nature, and in a certain sense takes on a geochemical role (for example, releasing carbon immured in the form of coal and oil for many millions of years and releasing it into the air with carbon dioxide). Therefore, anthropogenic factors in terms of scope and global impact are approaching geological forces.
Not infrequently, environmental factors are also subjected to a more detailed classification, when it is necessary to point to a particular group of factors. For example, there are climatic (relating to climate), edaphic (soil) environmental factors.
As a textbook example of the indirect action of environmental factors, the so-called bird colonies, which are huge concentrations of birds, are cited. The high density of birds is explained by a whole chain of cause and effect relationships. Bird droppings enter the water, organic substances in the water are mineralized by bacteria, an increased concentration of minerals leads to an increase in the number of algae, and after them - zooplankton. The lower crustaceans included in the zooplankton are fed by fish, and the birds inhabiting the bird rookery feed on fish. The chain closes. Bird droppings act as an environmental factor that indirectly increases the number of bird colonies.
How to compare the action of factors so different in nature? Despite the huge number of factors, from the very definition of the environmental factor as an element of the environment that affects the body, something in common follows. Namely: the action of environmental factors is always expressed in a change in the vital activity of organisms, and in the end, it leads to a change in the size of the population. This makes it possible to compare the effect of various environmental factors.
Needless to say, the effect of a factor on an individual is determined not by the nature of the factor, but by its dose. In the light of the above, and even simple life experience, it becomes obvious that the effect is determined precisely by the dose of the factor. Indeed, what is the factor "temperature"? This is quite an abstraction, but if you say that the temperature is -40 Celsius - there is no time for abstractions, it would be better to wrap yourself in everything warm! On the other hand, +50 degrees will not seem much better to us.
Thus, the factor affects the body with a certain dose, and among these doses, one can distinguish the minimum, maximum and optimal doses, as well as those values at which the life of an individual stops (they are called lethal, or lethal).
The effect of various doses on the population as a whole is very clearly described graphically:
The ordinate axis plots the population size depending on the dose of one or another factor (abscissa axis). The optimal doses of the factor and the doses of the action of the factor are distinguished, at which the inhibition of the vital activity of the given organism occurs. On the graph, this corresponds to 5 zones:
optimum zone
to the right and left of it are the pessimum zones (from the border of the optimum zone to max or min)
lethal zones (beyond max and min) where the population is 0.
The range of values of the factor, beyond which the normal life of individuals becomes impossible, is called the limits of endurance.
In the next lesson, we will look at how organisms differ in relation to various environmental factors. In other words, the next lesson will focus on the ecological groups of organisms, as well as the Liebig barrel and how all this is related to the definition of MPC.
Glossary
FACTOR ABIOTIC - a condition or set of conditions of the inorganic world; ecological factor of inanimate nature.
ANTHROPOGENIC FACTOR - an environmental factor that owes its origin to human activity.
PLANKTON - a set of organisms that live in the water column and are unable to actively resist the transfer of currents, that is, "floating" in the water.
BIRD MARKET - a colonial settlement of birds associated with the aquatic environment (guillemots, gulls).
What ecological factors out of all their variety does the researcher pay attention to first of all? Not infrequently, a researcher is faced with the task of identifying those environmental factors that inhibit the vital activity of representatives of a given population, limit growth and development. For example, it is necessary to find out the reasons for the decline in the yield or the reasons for the extinction of the natural population.
With all the variety of environmental factors and the difficulties that arise when trying to assess their joint (complex) impact, it is important that the factors that make up the natural complex are of unequal importance. Back in the 19th century, Liebig (Liebig, 1840), studying the effect of various microelements on plant growth, established that plant growth is limited by the element whose concentration is at a minimum. The deficient factor was called the limiting factor. Figuratively, this position helps to present the so-called "Liebig's barrel".
Liebig barrel
Imagine a barrel with wooden slats on the sides of different heights, as shown in the picture. It is clear, no matter how high the other slats are, but you can pour water into the barrel exactly as much as the length of the shortest slat (in this case, 4 dies).
It remains only to "replace" some terms: let the height of the poured water be some biological or ecological function (for example, productivity), and the height of the rails will indicate the degree of deviation of the dose of one or another factor from the optimum.
At present Liebig's law of the minimum is interpreted more widely. A limiting factor can be a factor that is not only in short supply, but also in excess.
The environmental factor plays the role of a LIMITING FACTOR if this factor is below the critical level or exceeds the maximum tolerable level.
The limiting factor determines the distribution area of the species or (under less severe conditions) affects the general level of metabolism. For example, the content of phosphates in sea water is a limiting factor that determines the development of plankton and the overall productivity of communities.
The concept of "limiting factor" applies not only to various elements, but to all environmental factors. Competitive relations often act as a limiting factor.
Each organism has its own limits of endurance in relation to various environmental factors. Depending on how wide or narrow these limits are, eurybiont and stenobiont organisms are distinguished. Eurybionts are able to endure a wide range of intensity of various environmental factors. For example, the habitat of a fox is from the forest-tundra to the steppes. Stenobionts, on the contrary, endure only very narrow fluctuations in the intensity of the environmental factor. For example, almost all tropical rainforest plants are stenobionts.
It is not uncommon to indicate which factor is meant. So, we can talk about eurythermal (tolerating large temperature fluctuations) organisms (many insects) and stenothermal (for tropical forest plants, temperature fluctuations within +5 ... +8 degrees C can be fatal); eury / stenohaline (tolerating / not tolerating fluctuations in water salinity); evry / stenobats (living in wide / narrow limits of the depth of the reservoir) and so on.
The emergence of stenobiont species in the process of biological evolution can be considered as a form of specialization in which greater efficiency is achieved at the expense of adaptability.
Interaction of factors. MPC.
With the independent action of environmental factors, it is sufficient to operate with the concept of "limiting factor" in order to determine the combined effect of a complex of environmental factors on a given organism. However, in real conditions, environmental factors can enhance or weaken each other. For example, frost in the Kirov region is easier to bear than in St. Petersburg, since the latter has higher humidity.
Accounting for the interaction of environmental factors is an important scientific problem. There are three main types of interaction factors:
additive - the interaction of factors is a simple algebraic sum of the effects of each of the factors with an independent action;
synergistic - the joint action of factors enhances the effect (that is, the effect of their joint action is greater than the simple sum of the effects of each factor with independent action);
antagonistic - the joint action of factors weakens the effect (that is, the effect of their joint action is less than the simple sum of the effects of each factor).
Why is it important to know about the interaction of environmental factors? The theoretical substantiation of the value of maximum permissible concentrations (MPC) of pollutants or maximum permissible levels (MPL) of the impact of polluting agents (for example, noise, radiation) is based on the law of the limiting factor. MPC is set experimentally at a level at which pathological changes do not yet occur in the body. At the same time, there are difficulties (for example, most often it is necessary to extrapolate data obtained on animals to humans). However, this is not about them.
It is not uncommon to hear how environmental authorities happily report that the level of most pollutants in the city's atmosphere is within the MPC. At the same time, the State Sanitary and Epidemiological Supervision authorities state an increased level of respiratory diseases in children. The explanation could be like this. It is no secret that many air pollutants have a similar effect: they irritate the mucous membranes of the upper respiratory tract, provoke respiratory diseases, etc. And the joint action of these pollutants gives an additive (or synergistic) effect.
Therefore, ideally, when developing MPC standards and assessing the existing environmental situation, the interaction of factors should be taken into account. Unfortunately, in practice this can be very difficult to do: it is difficult to plan such an experiment, it is difficult to evaluate the interaction, plus the tightening of MPCs has negative economic effects.
Glossary
MICROELEMENTS - chemical elements necessary for organisms in negligible quantities, but determining the success of their development. M. in the form of microfertilizers is used to increase the yield of plants.
LIMITING FACTOR - a factor that sets the framework (determining) for the course of some process or for the existence of an organism (species, community).
AREAL - the area of distribution of any systematic group of organisms (species, genus, family) or a certain type of community of organisms (for example, the area of lichen pine forests).
METABOLISM - (in relation to the body) consistent consumption, transformation, use, accumulation and loss of substances and energy in living organisms. Life is possible only through metabolism.
eurybiont - an organism that lives in various environmental conditions
STENOBIONT - an organism that requires strictly defined conditions of existence.
XENOBIOTIC - a chemical substance alien to the body, naturally not included in the biotic cycle. As a rule, a xenobiotic is of anthropogenic origin.
Ecosystem
URBAN AND INDUSTRIAL ECOSYSTEMS
General characteristics of urban ecosystems.
Urban ecosystems are heterotrophic, the share of solar energy fixed by urban plants or solar panels located on the roofs of houses is insignificant. The main sources of energy for the enterprises of the city, heating and lighting of the apartments of the townspeople are located outside the city. These are deposits of oil, gas, coal, hydro and nuclear power plants.
The city consumes a huge amount of water, only a small part of which a person uses for direct consumption. The main part of the water is spent on production processes and domestic needs. Personal water consumption in cities ranges from 150 to 500 liters per day, and taking into account industry, one citizen accounts for up to 1000 liters per day. Water used by cities returns to nature in a polluted state - it is saturated with heavy metals, oil residues, complex organic substances like phenol, etc. It may contain pathogens. The city emits toxic gases and dust into the atmosphere, concentrates toxic waste in landfills, which, with spring water flows, enter aquatic ecosystems. Plants, as part of urban ecosystems, grow in parks, gardens, and lawns, their main purpose is to regulate the gas composition of the atmosphere. They release oxygen, absorb carbon dioxide and purify the atmosphere from harmful gases and dust that enter it during the operation of industrial enterprises and transport. Plants are also of great aesthetic and decorative value.
Animals in the city are represented not only by species common in natural ecosystems (birds live in parks: redstart, nightingale, wagtail; mammals: voles, squirrels and representatives of other groups of animals), but also by a special group of urban animals - human companions. It includes birds (sparrows, starlings, pigeons), rodents (rats and mice), and insects (cockroaches, bedbugs, moths). Many animals associated with humans feed on garbage in garbage dumps (jackdaws, sparrows). These are the city nurses. The decomposition of organic waste is accelerated by fly larvae and other animals and microorganisms.
The main feature of the ecosystems of modern cities is that the ecological balance is disturbed in them. All processes of regulating the flow of matter and energy a person has to take over. A person must regulate both the consumption of energy and resources by the city - raw materials for industry and food for people, and the amount of toxic waste entering the atmosphere, water and soil as a result of industry and transport. Finally, it also determines the size of these ecosystems, which in developed countries, and in recent years in Russia, are rapidly “spreading” due to suburban cottage construction. Low-rise areas reduce the area of forests and agricultural land, their "spreading" requires the construction of new highways, which reduces the proportion of ecosystems capable of producing food and cycling oxygen.
Industrial pollution of the environment.
In urban ecosystems, industrial pollution is the most dangerous for nature.
Chemical pollution of the atmosphere. This factor is one of the most dangerous for human life. The most common contaminants
Sulfur dioxide, nitrogen oxides, carbon monoxide, chlorine, etc. In some cases, two or relatively several relatively harmless substances released into the atmosphere can form toxic compounds under the influence of sunlight. Ecologists number about 2,000 air pollutants.
The main sources of pollution are thermal power plants. Boiler houses, oil refineries and vehicles also heavily pollute the atmosphere.
Chemical pollution of water bodies. Enterprises dump oil products, nitrogen compounds, phenol and many other industrial wastes into water bodies. During oil production, water bodies are polluted with saline species, oil and oil products are also spilled during transportation. In Russia, the lakes of the North of Western Siberia suffer the most from oil pollution. In recent years, the danger to aquatic ecosystems of domestic wastewater from urban sewers has increased. In these effluents, the concentration of detergents has increased, which microorganisms decompose with difficulty.
As long as the amount of pollutants emitted into the atmosphere or discharged into rivers is small, ecosystems themselves are able to cope with them. With moderate pollution, the water in the river becomes almost clean after 3-10 km from the source of pollution. If there are too many pollutants, ecosystems cannot cope with them and irreversible consequences begin.
The water becomes undrinkable and dangerous to humans. Polluted water is not suitable for many industries.
Pollution of the soil surface with solid waste. City dumps of industrial and household waste occupy large areas. Garbage may contain toxic substances such as mercury or other heavy metals, chemical compounds that dissolve in rain and snow water and then enter water bodies and groundwater. Can get into garbage and devices containing radioactive substances.
The surface of the soil can be polluted by ash deposited from the smoke of coal-fired thermal power plants, cement factories, refractory bricks, etc. To prevent this contamination, special dust collectors are installed on the pipes.
Chemical pollution of groundwater. Groundwater currents transport industrial pollution over long distances, and it is not always possible to determine their source. The cause of pollution may be the washing out of toxic substances by rain and snow water from industrial landfills. Groundwater pollution also occurs during oil production using modern methods, when, in order to increase the return of oil reservoirs, salt water is re-injected into the wells, which has risen to the surface along with the oil during its pumping.
Salt water enters the aquifers, the water in the wells becomes bitter and undrinkable.
Noise pollution. The source of noise pollution can be an industrial enterprise or transport. Especially heavy dump trucks and trams produce a lot of noise. Noise affects the human nervous system, and therefore noise protection measures are taken in cities and enterprises.
Railway and tram lines and roads along which freight transport passes should be moved from the central parts of cities to sparsely populated areas and green spaces should be created around them that absorb noise well.
Planes should not fly over cities.
Noise is measured in decibels. Clock ticking - 10 dB, whisper - 25, noise from a busy highway - 80, aircraft takeoff noise - 130 dB. The pain threshold of noise is 140 dB. On the territory of residential development during the day, the noise should not exceed 50-66 dB.
Also, pollutants include: contamination of the soil surface with overburden and ash dumps, biological pollution, thermal pollution, radiation pollution, electromagnetic pollution.
Air pollution. If air pollution over the ocean is taken as a unit, then over villages it is 10 times higher, over small towns - 35 times, and over large cities - 150 times. The thickness of the layer of polluted air over the city is 1.5 - 2 km.
The most dangerous pollutants are benz-a-pyrene, nitrogen dioxide, formaldehyde, and dust. In the European part of Russia and the Urals, on average, during the year per 1 sq. km. km, more than 450 kg of atmospheric pollutants fell.
Compared to 1980, the amount of sulfur dioxide emissions increased by 1.5 times; 19 million tons of atmospheric pollutants were thrown into the atmosphere by road transport.
Wastewater discharge into rivers amounted to 68.2 cubic meters. km with a post-consumption of 105.8 cubic meters. km. Water consumption by industry is 46%. The share of untreated wastewater has been decreasing since 1989 and amounts to 28%.
Due to the predominance of westerly winds, Russia receives 8-10 times more air pollutants from its western neighbors than it sends to them.
Acid rains have negatively affected half of the forests of Europe, and the process of drying out of forests has begun in Russia as well. In Scandinavia, 20,000 lakes have already died due to acid rain coming from the UK and Germany. Under the influence of acid rain, architectural monuments are dying.
Harmful substances coming out of a chimney 100 m high are dispersed within a radius of 20 km, 250 m high - up to 75 km. The champion pipe was built at a copper-nickel plant in Sudbury (Canada) and has a height of more than 400 m.
Ozone-depleting chlorofluorocarbons (CFCs) enter the atmosphere from cooling system gases (in the US - 48%, and in other countries - 20%), from the use of aerosol cans (in the USA - 2%, and a few years ago their sale was banned; in other countries - 35%), solvents used in dry cleaning (20%) and in the production of foams, including styroform (25-
The main source of freons that destroy the ozone layer are industrial refrigerators - refrigerators. In an ordinary household refrigerator, 350 g of freon, and in industrial refrigerators - tens of kilograms. Refrigeration only in
Moscow annually uses 120 tons of freon. A significant part of it, due to the imperfection of the equipment, ends up in the atmosphere.
Pollution of freshwater ecosystems. In 1989, 1.8 tons of phenols, 69.7 tons of sulfates, 116.7 tons of synthetic surface-active substances (surfactants) were discharged into Lake Ladoga - a reservoir of drinking water for the six millionth St. Petersburg - in 1989.
Pollutes aquatic ecosystems and river transport. On Lake Baikal, for example, 400 ships of various sizes float, they dump about 8 tons of oil products into the water per year.
At most Russian enterprises, toxic production wastes are either dumped into water bodies, poisoning them, or accumulated without processing, often in huge quantities. These accumulations of deadly waste can be called "environmental mines"; when dams break, they can end up in water bodies. An example of such an "environmental mine" is the Cherepovets chemical plant "Ammophos". Its septic tank covers an area of 200 hectares and contains 15 million tons of waste. The dam that encloses the sump is raised annually by
4 m. Unfortunately, the "Cherepovets mine" is not the only one.
In developing countries, 9 million people die every year. By the year 2000, more than 1 billion people will lack drinking water.
Pollution of marine ecosystems. About 20 billion tons of garbage have been dumped into the World Ocean - from domestic sewage to radioactive waste. Every year for every 1 sq. km of the water surface add another 17 tons of garbage.
More than 10 million tons of oil is poured into the ocean every year, which forms a film covering 10-15% of its surface; and 5 g of petroleum products is enough to tighten the film 50 square meters. m of water surface. This film not only reduces the evaporation and absorption of carbon dioxide, but also causes oxygen starvation and the death of eggs and young fish.
Radiation pollution. It is assumed that by the year 2000 the world will have accumulated
1 million cubic meters m of high-level radioactive waste.
The natural radioactive background affects every person, even those who do not come into contact with nuclear power plants or nuclear weapons. We all receive a certain dose of radiation in our lifetime, 73% of which comes from the radiation of natural bodies (for example, granite in monuments, house cladding, etc.), 14% from medical procedures (primarily from visiting an X-ray room) and 14% - on cosmic rays. Over a lifetime (70 years), a person can, without much risk, gain radiation of 35 rem (7 rem from natural sources, 3 rem from space sources and x-ray machines). In the zone of the Chernobyl nuclear power plant in the most polluted areas, you can get up to 1 rem per hour. The radiation power on the roof during the period of extinguishing a fire at a nuclear power plant reached 30,000 roentgens per hour, and therefore, without radiation protection (a lead suit), a lethal dose of radiation could be obtained in 1 minute.
The hourly dose of radiation, lethal to 50% of organisms, is 400 rem for humans, 1000-2000 rem for fish and birds, from 1000 to 150,000 for plants, and 100,000 rem for insects. Thus, the strongest pollution is not a hindrance to the mass reproduction of insects. Of the plants, trees are the least resistant to radiation and grasses are the most resistant.
Pollution with household waste. The amount of accumulated garbage is constantly growing. Now it is from 150 to 600 kg per year for every city dweller. Most of the garbage is produced in the USA (520 kg per year per inhabitant), in Norway, Spain, Sweden, the Netherlands - 200-300 kg, and in Moscow - 300-320 kg.
In order for paper to decompose in the natural environment, it takes from 2 to 10 years, a tin can - more than 90 years, a cigarette filter - 100 years, a plastic bag - more than 200 years, plastic - 500 years, glass - more than 1000 years.
Ways to reduce harm from chemical pollution
The most common pollution - chemical. There are three main ways to reduce the harm from them.
Dilution. Even treated effluents must be diluted 10 times (and untreated - 100-200 times). High chimneys are built at enterprises so that the emitted gases and dust are dispersed evenly. Dilution is an ineffective way to reduce the harm from pollution, acceptable only as a temporary measure.
Cleaning. This is the main way to reduce emissions of harmful substances into the environment in Russia today. However, as a result of treatment, a lot of concentrated liquid and solid wastes are generated, which also have to be stored.
Replacing old technologies with new low-waste technologies. Due to deeper processing, it is possible to reduce the amount of harmful emissions by dozens of times. Waste from one industry becomes raw material for another.
Figurative names for these three ways to reduce environmental pollution were given by German ecologists: “lengthen the pipe” (dilution by dispersion), “plug the pipe” (cleaning) and “tie the pipe in a knot” (low-waste technologies). The Germans restored the ecosystem of the Rhine, which for many years was a sewer where the waste of industrial giants was dumped. This was done only in the 80s, when, finally, "the pipe was tied in a knot."
The level of environmental pollution in Russia is still very high, and an ecologically unfavorable situation dangerous for the health of the population has developed in almost 100 cities of the country.
Some improvement in the environmental situation in Russia has been achieved due to improved operation of treatment facilities and a drop in production.
Further reduction of emissions of toxic substances into the environment can be achieved if less hazardous low-waste technologies are introduced. However, in order to “tie the pipe in a knot”, it is necessary to upgrade equipment at enterprises, which requires very large investments and therefore will be carried out gradually.
Cities and industrial facilities (oil fields, quarries for the development of coal and ore, chemical and metallurgical plants) operate on the energy that comes from other industrial ecosystems (energy complex), and their products are not plant and animal biomass, but steel, cast iron and aluminum, various machines and devices, building materials, plastics and much more that is not found in nature.
The problems of urban ecology are, first of all, the problems of reducing emissions of various pollutants into the environment and protecting water, atmosphere, and soil from cities. They are solved by creating new low-waste technologies and production processes and efficient treatment facilities.
Plants play an important role in mitigating the impact of urban environmental factors on humans. Green spaces improve the microclimate, trap dust and gases, and have a beneficial effect on the mental state of citizens.
Literature:
Mirkin B.M., Naumova L.G. Ecology of Russia. A textbook from the federal set for grades 9-11 of a comprehensive school. Ed. 2nd, revised.
And extra. - M.: AO MDS, 1996. - 272 with ill.
State educational institution
Higher professional education.
"SAINT PETERSBURG STATE UNIVERSITY
SERVICE AND ECONOMY»
Discipline: Ecology
Institute (Faculty): (IREU) "Institute of Regional Economics and Management"
Specialty: 080507 "Management of organizations"
On the topic: Environmental factors and their classification.
Performed:
Valkova Violetta Sergeevna
1st year student
Correspondence form of education
Supervisor:
Ovchinnikova Raisa Andreevna
2008 - 2009
INTRODUCTION ……………………………………………………………………………………………..3
ENVIRONMENTAL FACTORS. ENVIRONMENTAL CONDITIONS … …………………………………...3
abiotic
Biotic
Anthropogenic
BIOTIC RELATIONSHIPS OF ORGANISMS ……………… ……………….6
GENERAL PATTERNS OF THE INFLUENCE OF ENVIRONMENTAL FACTORS ON ORGANISMS ……………………………………………………………………………………….7
CONCLUSION ……………………………………………………………………………………………9
LIST OF USED LITERATURE ………… ………………………………………..10
INTRODUCTION
Let us imagine any one kind of plant or animal and in it one individual mentally isolating it from the rest of the world of wildlife. This individual, under the influence environmental factors will be influenced by them. The main of them will be the factors determined by the climate. Everyone is well aware, for example, that representatives of one or another species of plants and animals are not found everywhere. Some plants live only along the banks of water bodies, others - under the canopy of the forest. In the Arctic, you can not meet a lion, in the Gobi desert - a polar bear. We are aware that climatic factors (temperature, humidity, illumination, etc.) are of the greatest importance in the distribution of species. For land animals, especially soil inhabitants, and plants, the physical and chemical properties of the soil play an important role. For aquatic organisms, the properties of water as the only habitat are of particular importance. The study of the action of various natural factors on individual organisms is the first and simplest subdivision of ecology.
ENVIRONMENTAL FACTORS. ENVIRONMENTAL CONDITIONS
variety of environmental factors. Environmental factors are any external factors that have a direct or indirect impact on the number (abundance) and geographical distribution of animals and plants.
Environmental factors are very diverse both in nature and in their impact on living organisms. Conventionally, all environmental factors are divided into three large groups - abiotic, biotic and anthropogenic.
Abiotic factors - these are factors of inanimate nature, primarily climatic (sunlight, temperature, air humidity), and local (relief, soil properties, salinity, currents, wind, radiation, etc.). These factors can affect the body directly(directly) as light and heat, or indirectly, such as the terrain, which determines the action of direct factors (illumination, moisture, wind, etc.).
Anthropogenic factors - These are those forms of human activity that, influencing the environment, change the conditions of living organisms or directly affect individual species of plants and animals. One of the most important anthropogenic factors is pollution.
environment conditions. Environmental conditions, or ecological conditions, are called abiotic environmental factors that change in time and space, to which organisms react differently depending on their strength. Environmental conditions impose certain restrictions on organisms. The amount of light penetrating through the water column limits the life of green plants in water bodies. The abundance of oxygen limits the number of air-breathing animals. Temperature determines the activity and controls the reproduction of many organisms.
The most important factors that determine the conditions for the existence of organisms in almost all living environments include temperature, humidity and light. Let's consider the effect of these factors in more detail.
Temperature. Any organism is able to live only within a certain temperature range: individuals of the species die at too high or too low temperatures. Somewhere within this interval, the temperature conditions are most favorable for the existence of a given organism, its vital functions are carried out most actively. As the temperature approaches the boundaries of the interval, the speed of life processes slows down, and finally, they stop altogether - the organism dies.
The limits of thermal endurance in different organisms are different. There are species that can tolerate temperature fluctuations over a wide range. For example, lichens and many bacteria are able to live at very different temperatures. Among animals, warm-blooded animals are characterized by the largest range of temperature endurance. The tiger, for example, tolerates both the Siberian cold and the heat of the tropical regions of India or the Malay Archipelago equally well. But there are also species that can only live within more or less narrow temperature limits. This includes many tropical plants, such as orchids. In the temperate zone, they can only grow in greenhouses and require careful care. Some reef-forming corals can only live in seas where the water temperature is at least 21°C. However, corals also die off when the water is too hot.
In the land-air environment and even in many parts of the aquatic environment, the temperature does not remain constant and can vary greatly depending on the season of the year or on the time of day. In tropical areas, annual temperature fluctuations can be even less noticeable than daily ones. And vice versa, in temperate regions, the temperature varies significantly in different seasons. Animals and plants are forced to adapt to the unfavorable winter season, during which an active life is difficult or simply impossible. In tropical areas, such adaptations are less pronounced. In a cold period with unfavorable temperature conditions, a pause seems to occur in the life of many organisms: hibernation in mammals, leaf shedding in plants, etc. Some animals make long migrations to places with a more suitable climate.
Humidity. Throughout most of its history, wildlife has been represented by exceptional aquatic forms of organisms. Having conquered the land, they nevertheless did not lose their dependence on water. Water is an integral part of the vast majority of living beings: it is necessary for their normal functioning. A normally developing organism constantly loses water and therefore cannot live in absolutely dry air. Sooner or later, such losses can lead to the death of the organism.
In physics, humidity is measured by the amount of water vapor in the air. However, the simplest and most convenient indicator characterizing the humidity of a particular area is the amount of precipitation that falls here for a year or another period of time.
Plants extract water from the soil using their roots. Lichens can capture water vapor from the air. Plants have a number of adaptations that ensure minimal water loss. All terrestrial animals need a periodic supply to compensate for the inevitable loss of water due to evaporation or excretion. Many animals drink water; others, such as amphibians, some insects and mites, absorb it through the integument of the body in a liquid or vapor state. Most desert animals never drink. They meet their needs with water from food. Finally, there are animals that obtain water in an even more complex way - in the process of fat oxidation. Examples are the camel and certain types of insects, such as rice and barn weevil, clothes moths that feed on fat. Animals, like plants, have many adaptations to conserve water.
Light. For animals, light, as an ecological factor, is incomparably less important than temperature and humidity. But light is absolutely necessary for living nature, since it is practically the only source of energy for it.
For a long time, light-loving plants, which are able to develop only under the sun's rays, and shade-tolerant plants, which can grow well under the forest canopy, have been distinguished for a long time. Most of the undergrowth in the beech forest, which is particularly shady, is formed by shade-tolerant plants. This is of great practical importance for the natural regeneration of the forest stand: the young shoots of many tree species are able to develop under the cover of large trees.
In many animals, normal light conditions manifest themselves in a positive or negative reaction to light. Everyone knows how nocturnal insects flock to the light or how cockroaches scatter in search of shelter, if only a light is turned on in a dark room.
However, light has the greatest ecological significance in the change of day and night. Many animals are exclusively diurnal (most passerines), others are exclusively nocturnal (many small rodents, bats). Small crustaceans hovering in the water column stay at night in surface waters, and during the day they sink to the depths, avoiding too bright light.
Compared to temperature or humidity, light has almost no direct effect on animals. It serves only as a signal for the restructuring of the processes occurring in the body, which allows them to respond in the best possible way to the ongoing changes in external conditions.
The factors listed above do not exhaust the set of ecological conditions that determine the life and distribution of organisms. The so-called secondary climatic factors e.g. wind, barometric pressure, altitude. The wind has an indirect effect: by increasing evaporation, it increases dryness. Strong wind helps to cool. This action is important in cold places, in the highlands or in the polar regions.
anthropogenic factors. contaminants. Anthropogenic factors are very diverse in their composition. Man influences living nature by laying roads, building cities, farming, blocking rivers, etc. Modern human activity is increasingly manifested in environmental pollution by by-products, often poisonous products. Sulfur dioxide emitted from the pipes of factories and thermal power plants, metal compounds (copper, zinc, lead) discharged near mines or formed in vehicle exhaust gases, oil residues discharged into water bodies during the washing of oil tankers - these are just some of the pollutants that limit the spread organisms (especially plants).
In industrial areas, the concepts of pollutants sometimes reach the threshold, i.e. lethal for many organisms, values. However, in spite of everything, there will almost always be at least a few individuals of several species that can survive in such conditions. The reason is that even in natural populations, resistant individuals occasionally come across. As pollution levels rise, resistant individuals may be the only survivors. Moreover, they can become the founders of a stable population, inheriting immunity to this type of pollution. For this reason, pollution makes it possible for us, as it were, to observe evolution in action. Of course, not every population is endowed with the ability to resist pollution, even if in the face of single individuals.
Thus, the effect of any pollutant is twofold. If this substance appeared recently or is contained in very high concentrations, then each species previously found in a contaminated site is usually represented by only a few specimens - precisely those that, due to natural variability, had initial stability or their nearest flows.
Subsequently, the contaminated area turns out to be populated much more densely, but as a rule, by a much smaller number of species than if there was no pollution. Such newly emerged communities with a depleted species composition have already become an integral part of the human environment.
BIOTIC RELATIONSHIPS OF ORGANISMS
Two types of any organisms living in the same territory and in contact with each other enter into different relationships with each other. The position of the species in different forms of relationships is indicated by conventional signs. The minus sign (-) indicates an adverse effect (individuals of the species experience oppression or harm). The plus sign (+) denotes a beneficial effect (individuals of the species benefit). The zero sign (0) indicates that the relationship is indifferent (no influence).
Thus, all biotic relationships can be divided into 6 groups: none of the populations affects the other (00); mutually beneficial useful connections (+ +); relationships harmful to both species (––); one of the species benefits, the other experiences oppression (+ -); one species benefits, the other does not experience harm (+ 0); one species is oppressed, the other does not benefit (-0).
For one of the cohabiting species, the influence of the other is negative (it experiences oppression), while the oppressor receives neither harm nor benefit - this amensalism(-0). An example of amensalism is light-loving grasses growing under a spruce, suffering from strong shading, while this is indifferent to the tree itself.
A form of relationship in which one species gains some advantage without harming or benefiting the other is called commensalism(+0). For example, large mammals (dogs, deer) serve as carriers of fruits and seeds with hooks (like burdock), without receiving any harm or benefit from this.
Commensalism is the unilateral use of one species by another without harming it. The manifestations of commensalism are diverse, therefore, a number of variants are distinguished in it.
"Freeloading" is the consumption of the host's leftover food.
“Companionship” is the consumption of different substances or parts of the same food.
"Housing" - the use by one species of others (their bodies, their dwellings (as a shelter or dwelling.
In nature, mutually beneficial relationships between species are often found, with some organisms receiving mutual benefits from these relationships. This group of mutually beneficial biological connections includes diverse symbiotic relationships between organisms. An example of symbiosis is lichens, which are a close mutually beneficial cohabitation of fungi and algae. A well-known example of symbiosis is the cohabitation of green plants (primarily trees) and fungi.
One of the types of mutually beneficial relationships is proto-operation(primary collaboration) (+ +). At the same time, joint, although not mandatory, existence is beneficial for both species, but is not an indispensable condition for survival. An example of protocooperation is the spread of seeds of some forest plants by ants, pollination by bees of various meadow plants.
If two or more species have similar ecological requirements and live together, a relationship of a negative type can develop between them, which is called competition(rivalry, competition) (- -). For example, all plants compete for light, moisture, soil nutrients and, therefore, for the expansion of their territory. Animals compete for food resources, shelter, and also for territory.
Predation(+ -) - this type of interaction between organisms, in which representatives of one species kill and eat representatives of another.
These are the main types of biotic interactions in nature. It should be remembered that the type of relationship of a particular pair of species may vary depending on external conditions or the stage of life of the interacting organisms. In addition, in nature, not a couple of species, but a much larger number of them, are simultaneously involved in biotic relationships.
GENERAL REGULARITIES OF THE INFLUENCE OF ENVIRONMENTAL FACTORS ON ORGANISMS
The example of temperature shows that this factor is tolerated by the body only within certain limits. The organism dies if the environment temperature is too low or too high. In an environment where the temperature is close to these extreme values, living inhabitants are rare. However, their number increases as the temperature approaches the average value, which is the best (optimum) for this species.
This pattern can be transferred to any other factor that determines the speed of certain life processes (humidity, wind strength, current speed, etc.).
If we draw a curve on the graph that characterizes the intensity of a particular process (respiration, movement, nutrition, etc.) depending on one of the environmental factors (of course, provided that this factor has an impact on the main life processes), then this curve will almost always be bell-shaped.
These curves are called curves tolerance(from Greek. tolerance- patience, perseverance). The position of the top of the curve indicates such conditions that are optimal for a given process.
Some individuals and species are characterized by curves with very sharp peaks. This means that the range of conditions under which the activity of the organism reaches its maximum is very narrow. Flat curves correspond to a wide tolerance range.
Organisms with wide limits of resistance, of course, have a chance for a wider distribution. However, wide limits of endurance for one factor do not mean wide limits for all factors. The plant can be tolerant of large temperature fluctuations, but have narrow tolerances to water. An animal like a trout can be very demanding in terms of temperature, but eat a variety of foods.
Sometimes, during the life of an individual, its tolerance may change (correspondingly, the position of the curve will also change), if the individual falls into other external conditions. Once in such conditions, the body after a while, as it were, gets used, adapts to them. The consequence of this is a change in the physiological optimum, or shifts in the dome of the tolerance curve. Such a phenomenon is called adaptation, or acclimatization.
In species with a wide geographical distribution, the inhabitants of geographic or climatic zones often turn out to be best adapted to precisely those conditions that are characteristic of a given area. This is due to the ability of some organisms to form local (local) forms, or ecotypes, characterized by different limits of resistance to temperature, light, or other factors.
Consider, as an example, the ecotypes of one of the species of jellyfish. Jellyfish move through the water with rhythmic muscle contractions that push water out of the central cavity of the body, similar to the movement of a rocket. The optimal frequency of such a pulsation is 15-20 contractions per minute. Individuals living in the seas of northern latitudes move at the same speed as jellyfish of the same species in the seas of southern latitudes, although the water temperature in the north can be 20 ° C lower. Consequently, both forms of organisms of the same species were able to best adapt to local conditions.
The law of the minimum. The intensity of certain biological processes is often sensitive to two or more environmental factors. In this case, the decisive factor will belong to such a factor, which is available in the minimum, from the point of view of the needs of the organism, quantity. This rule was formulated by the founder of the science of mineral fertilizers Justus Liebig(1803-1873) and was named Law of the minimum. J. Liebig discovered that the yield of plants can be limited by any of the main nutrients, if only this element is in short supply.
It is known that different environmental factors can interact, that is, the lack of one substance can lead to a deficiency of other substances. Therefore, in general, the law of the minimum can be formulated as follows: the successful survival of living organisms depends on a set of conditions; a limiting or limiting factor is any state of the environment that approaches or goes beyond the resistance limit for organisms of a given species.
The provision on limiting factors greatly facilitates the study of complex situations. Despite the complexity of the relationship between organisms and their environment, not all factors have the same ecological significance. For example, oxygen is a factor of physiological necessity for all animals, but from an ecological point of view, it becomes limiting only in certain habitats. If fish die in a river, the first thing to be measured is the oxygen concentration in the water, as it is highly variable, oxygen reserves are easily depleted and often lacking. If the death of birds is observed in nature, it is necessary to look for another reason, since the oxygen content in the air is relatively constant and sufficient from the point of view of the requirements of terrestrial organisms.
CONCLUSION
Ecology is a vital science for man, studying his immediate natural environment. Man, observing nature and its inherent harmony, involuntarily sought to bring this harmony into his life. This desire became especially acute only relatively recently, after the consequences of unreasonable economic activity, leading to the destruction of the natural environment, became very noticeable. And this ultimately had an adverse effect on the person himself.
It should be remembered that ecology is a fundamental scientific discipline, the ideas of which are very important. And if we recognize the importance of this science, we need to learn how to correctly use its laws, concepts, terms. After all, they help people determine their place in their environment, correctly and rationally use natural resources. It has been proved that the use of natural resources by a person with complete ignorance of the laws of nature often leads to severe, irreparable consequences.
The basics of ecology as a science about our common home - the Earth, should be known to every person on the planet. Knowledge of the basics of ecology will help to reasonably build your life for both society and the individual; they will help everyone to feel like a part of the great Nature, to achieve harmony and comfort where previously there was an unreasonable struggle with natural forces.
LIST OF USED LITERATURE environmental factors (Biotic factors; Biotic ecological factors; Biotic factors; ... .5 Question No. 67 Natural resources, them classification. Resource cycle NATURAL RESOURCES (natural...
These are any environmental factors to which the body reacts with adaptive reactions.
Environment is one of the basic ecological concepts, which means a complex of environmental conditions that affect the life of organisms. In a broad sense, the environment is understood as the totality of material bodies, phenomena and energy that affect the body. A more concrete, spatial understanding of the environment as the immediate environment of the organism is also possible - its habitat. Habitat is all that among which an organism lives, it is a part of nature that surrounds living organisms and has a direct or indirect effect on them. Those. elements of the environment, which are not indifferent to a given organism or species and in one way or another influence it, are factors in relation to it.
The components of the environment are diverse and changeable, therefore living organisms constantly adapt and regulate their vital activity in accordance with the ongoing variations in the parameters of the external environment. Such adaptations of organisms are called adaptations and allow them to survive and reproduce.
All environmental factors are divided into
- Abiotic factors - factors of inanimate nature directly or indirectly affecting the body - light, temperature, humidity, chemical composition of the air, water and soil environment, etc. (i.e., the properties of the environment, the occurrence and impact of which does not directly depend on the activity of living organisms) .
- Biotic factors - all forms of influence on the body from the surrounding living beings (microorganisms, the influence of animals on plants and vice versa).
- Anthropogenic factors are various forms of activity of human society that lead to a change in nature as a habitat for other species or directly affect their lives.
Environmental factors affect living organisms
- as irritants causing adaptive changes in physiological and biochemical functions;
- as limiters, making it impossible to exist in these conditions;
- as modifiers that cause structural and functional changes in organisms, and as signals indicating changes in other environmental factors.
In this case, it is possible to establish the general nature of the impact of environmental factors on a living organism.
Any organism has a specific set of adaptations to environmental factors and successfully exists only within certain limits of their variability. The most favorable level of the factor for life activity is called optimal.
With small values or with excessive influence of the factor, the vital activity of organisms drops sharply (it is noticeably inhibited). The range of action of the ecological factor (the area of tolerance) is limited by the minimum and maximum points corresponding to the extreme values of this factor, at which the existence of the organism is possible.
The upper level of the factor, beyond which the vital activity of organisms becomes impossible, is called the maximum, and the lower level is called the minimum (Fig.). Naturally, each organism has its own maximums, optimums and minimums of environmental factors. For example, a housefly can withstand temperature fluctuations from 7 to 50 ° C, and a human roundworm lives only at human body temperature.
The points of optimum, minimum and maximum are three cardinal points that determine the possibilities of the organism's reaction to this factor. The extreme points of the curve, expressing the state of oppression with a lack or excess of a factor, are called pessimum areas; they correspond to the pessimal values of the factor. Near the critical points are the sublethal values of the factor, and outside the tolerance zone are the lethal zones of the factor.
The environmental conditions under which any factor or their combination goes beyond the comfort zone and has a depressing effect are often called extreme, boundary (extreme, difficult) in ecology. They characterize not only ecological situations (temperature, salinity), but also such habitats where conditions are close to the limits of the possibility of existence for plants and animals.
Any living organism is simultaneously affected by a complex of factors, but only one of them is limiting. The factor that sets the framework for the existence of an organism, species or community is called limiting (limiting). For example, the distribution of many animals and plants to the north is limited by a lack of heat, while in the south, the limiting factor for the same species may be a lack of moisture or necessary food. However, the limits of the organism's endurance in relation to the limiting factor depend on the level of other factors.
Some organisms require conditions within narrow limits for life, i.e. the optimum range is not constant for the species. The optimum effect of the factor is also different in different species. The span of the curve, i.e., the distance between the threshold points, shows the zone of action of the environmental factor on the organism (Fig. 104). Under conditions close to the threshold action of the factor, organisms feel oppressed; they may exist but do not reach full development. Plants usually do not bear fruit. In animals, on the contrary, puberty accelerates.
The magnitude of the range of the factor, and especially the zone of optimum, makes it possible to judge the endurance of organisms in relation to a given element of the environment, and indicates their ecological amplitude. In this regard, organisms that can live in quite a variety of environmental conditions are called svrybiont (from the Greek "evros" - wide). For example, a brown bear lives in cold and warm climates, in dry and humid areas, and eats a variety of plant and animal foods.
In relation to private environmental factors, a term is used that begins with the same prefix. For example, animals that can exist in a wide range of temperatures are called eurythermal, and organisms that can live only in narrow temperature ranges are called stenothermic. According to the same principle, an organism can be euryhydride or stenohydride, depending on its response to humidity fluctuations; euryhaline or stenohaline - depending on the ability to tolerate different salinity values, etc.
There are also concepts of ecological valence, which is the ability of an organism to inhabit a variety of environments, and ecological amplitude, which reflects the width of the factor range or the width of the optimum zone.
Quantitative regularities of the reaction of organisms to the action of the environmental factor differ in accordance with the conditions of their habitat. Stenobiontness or eurybiontness does not characterize the specificity of a species in relation to any ecological factor. For example, some animals are confined to a narrow temperature range (i.e., stenothermal) and can simultaneously exist in a wide range of environmental salinity (euryhaline).
Environmental factors affect a living organism simultaneously and jointly, and the action of one of them depends to a certain extent on the quantitative expression of other factors - light, humidity, temperature, surrounding organisms, etc. This pattern is called the interaction of factors. Sometimes the lack of one factor is partially compensated by the strengthening of the activity of another; there is a partial substitution of the action of environmental factors. At the same time, none of the factors necessary for the body can be completely replaced by another. Phototrophic plants cannot grow without light under the most optimal conditions of temperature or nutrition. Therefore, if the value of at least one of the necessary factors goes beyond the tolerance range (below the minimum or above the maximum), then the existence of the organism becomes impossible.
Environmental factors that have a pessimal value under specific conditions, i.e., those that are the most distant from the optimum, make it especially difficult for a species to exist under these conditions, despite the optimal combination of other conditions. This dependence is called the law of limiting factors. Such factors deviating from the optimum acquire paramount importance in the life of a species or individual individuals, determining their geographical range.
The identification of limiting factors is very important in agricultural practice to establish ecological valence, especially in the most vulnerable (critical) periods of animal and plant ontogeny.
Environmental factors is a set of environmental conditions that affect living organisms. Distinguish inanimate factors- abiotic (climatic, edaphic, orographic, hydrographic, chemical, pyrogenic), wildlife factors— biotic (phytogenic and zoogenic) and anthropogenic factors (impact of human activity). Limiting factors include any factors that limit the growth and development of organisms. The adaptation of an organism to its environment is called adaptation. The appearance of an organism, reflecting its adaptability to environmental conditions, is called a life form.
The concept of environmental environmental factors, their classification
Individual components of the environment that affect living organisms, to which they react with adaptive reactions (adaptations), are called environmental factors, or ecological factors. In other words, the complex of environmental conditions that affect the life of organisms is called ecological factors of the environment.
All environmental factors are divided into groups:
1. include components and phenomena of inanimate nature that directly or indirectly affect living organisms. Among the many abiotic factors, the main role is played by:
- climatic(solar radiation, light and light regime, temperature, humidity, precipitation, wind, atmospheric pressure, etc.);
- edaphic(mechanical structure and chemical composition of the soil, moisture capacity, water, air and thermal conditions of the soil, acidity, humidity, gas composition, groundwater level, etc.);
- orographic(relief, slope exposure, slope steepness, elevation difference, height above sea level);
- hydrographic(transparency of water, fluidity, flow, temperature, acidity, gas composition, content of mineral and organic substances, etc.);
- chemical(gas composition of the atmosphere, salt composition of water);
- pyrogenic(effect of fire).
2. - a set of relationships between living organisms, as well as their mutual influences on the environment. The action of biotic factors can be not only direct, but also indirect, expressed in the adjustment of abiotic factors (for example, changes in the composition of the soil, microclimate under the forest canopy, etc.). Biotic factors include:
- phytogenic(the influence of plants on each other and on the environment);
- zoogenic(the influence of animals on each other and on the environment).
3. reflect the intense impact of a person (directly) or human activity (indirectly) on the environment and living organisms. These factors include all forms of human activity and human society that lead to a change in nature as a habitat and other species and directly affect their lives. Each living organism is influenced by inanimate nature, organisms of other species, including humans, and in turn affects each of these components.
The influence of anthropogenic factors in nature can be both conscious and accidental, or unconscious. Man, plowing up virgin and fallow lands, creates agricultural land, breeds highly productive and disease-resistant forms, settles some species and destroys others. These impacts (conscious) are often negative in nature, for example, the rash resettlement of many animals, plants, microorganisms, the predatory destruction of a number of species, environmental pollution, etc.
Biotic factors of the environment are manifested through the relationship of organisms that are part of the same community. In nature, many species are closely interrelated, their relationships with each other as components of the environment can be extremely complex. As for the connections between the community and the surrounding inorganic environment, they are always bilateral, mutual. Thus, the nature of the forest depends on the corresponding type of soil, but the soil itself is largely formed under the influence of the forest. Similarly, the temperature, humidity and light in the forest are determined by vegetation, but the climatic conditions that have developed in turn affect the community of organisms living in the forest.
The impact of environmental factors on the body
The impact of the environment is perceived by organisms through environmental factors called ecological. It should be noted that the environmental factor is only a changing element of the environment, causing in organisms, when it changes again, response adaptive ecological and physiological reactions, which are hereditarily fixed in the process of evolution. They are divided into abiotic, biotic and anthropogenic (Fig. 1).
They name the whole set of factors of the inorganic environment that affect the life and distribution of animals and plants. Among them are distinguished: physical, chemical and edaphic.
Physical factors - those whose source is a physical state or phenomenon (mechanical, wave, etc.). For example, temperature.
Chemical Factors- those that come from the chemical composition of the environment. For example, water salinity, oxygen content, etc.
Edaphic (or soil) factors are a combination of chemical, physical and mechanical properties of soils and rocks that affect both the organisms for which they are the habitat and the root system of plants. For example, the influence of nutrients, moisture, soil structure, humus content, etc. on the growth and development of plants.
Rice. 1. Scheme of the impact of the environment (environment) on the body
- factors of human activity affecting the natural environment (and hydrospheres, soil erosion, deforestation, etc.).
Limiting (limiting) environmental factors called such factors that limit the development of organisms due to a lack or excess of nutrients compared to the need (optimal content).
So, when growing plants at different temperatures, the point at which maximum growth is observed will be optimum. The entire range of temperatures, from minimum to maximum, at which growth is still possible, is called range of stability (endurance), or tolerance. Its limiting points, i.e. maximum and minimum habitable temperatures, - stability limits. Between the optimum zone and the limits of stability, as the latter is approached, the plant experiences increasing stress, i.e. we are talking about stress zones, or zones of oppression, within the stability range (Fig. 2). As the distance from the optimum goes down and up on the scale, not only does stress increase, but when the limits of the organism's resistance are reached, its death occurs.
Rice. 2. Dependence of the action of the environmental factor on its intensity
Thus, for each species of plants or animals, there are optimum, stress zones and limits of stability (or endurance) in relation to each environmental factor. When the value of the factor is close to the limits of endurance, the organism can usually exist only for a short time. In a narrower range of conditions, long-term existence and growth of individuals is possible. In an even narrower range, reproduction occurs, and the species can exist indefinitely. Usually, somewhere in the middle part of the stability range, there are conditions that are most favorable for life, growth and reproduction. These conditions are called optimal, in which individuals of a given species are the most adapted, i.e. leaving the largest number of offspring. In practice, it is difficult to identify such conditions, so the optimum is usually determined by individual indicators of vital activity (growth rate, survival rate, etc.).
Adaptation is the adaptation of the organism to the conditions of the environment.
The ability to adapt is one of the basic properties of life in general, providing the possibility of its existence, the ability of organisms to survive and reproduce. Adaptations are manifested at different levels - from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. All adaptations of organisms to existence in various conditions have developed historically. As a result, groupings of plants and animals specific to each geographical area were formed.
Adaptations can be morphological, when the structure of an organism changes up to the formation of a new species, and physiological, when changes occur in the functioning of the body. Morphological adaptations are closely related to the adaptive coloration of animals, the ability to change it depending on the illumination (flounder, chameleon, etc.).
Widely known examples of physiological adaptation are hibernation of animals, seasonal flights of birds.
Very important for organisms are behavioral adaptations. For example, instinctive behavior determines the action of insects and lower vertebrates: fish, amphibians, reptiles, birds, etc. Such behavior is genetically programmed and inherited (innate behavior). This includes: the method of building a nest in birds, mating, raising offspring, etc.
There is also an acquired command received by the individual in the course of his life. Education(or learning) - the main mode of transmission of acquired behavior from one generation to another.
The ability of an individual to control his cognitive abilities in order to survive unexpected environmental changes is intellect. The role of learning and intelligence in behavior increases with the improvement of the nervous system - an increase in the cerebral cortex. For man, this is the determining mechanism of evolution. The ability of species to adapt to a particular range of environmental factors is denoted by the concept ecological mysticism of the species.
The combined effect of environmental factors on the body
Environmental factors usually act not one by one, but in a complex way. The effect of any one factor depends on the strength of the influence of others. The combination of different factors has a significant impact on the optimal conditions for the life of the organism (see Fig. 2). The action of one factor does not replace the action of another. However, under the complex influence of the environment, one can often observe the “substitution effect”, which manifests itself in the similarity of the results of the influence of different factors. Thus, light cannot be replaced by an excess of heat or an abundance of carbon dioxide, but by acting on changes in temperature, it is possible to stop, for example, the photosynthesis of plants.
In the complex influence of the environment, the impact of various factors for organisms is unequal. They can be divided into main, accompanying and secondary. The leading factors are different for different organisms, even if they live in the same place. The role of the leading factor at different stages of the life of the organism can be either one or the other elements of the environment. For example, in the life of many cultivated plants, such as cereals, temperature is the leading factor during germination, soil moisture during heading and flowering, and the amount of nutrients and air humidity during ripening. The role of the leading factor may change at different times of the year.
The leading factor may not be the same in the same species living in different physical and geographical conditions.
The concept of leading factors should not be confused with the concept of. A factor whose level in qualitative or quantitative terms (lack or excess) turns out to be close to the endurance limits of a given organism, is called limiting. The action of the limiting factor will also manifest itself in the case when other environmental factors are favorable or even optimal. Both leading and secondary environmental factors can act as limiting ones.
The concept of limiting factors was introduced in 1840 by the chemist 10. Liebig. Studying the influence of the content of various chemical elements in the soil on plant growth, he formulated the principle: “The minimum substance controls the crop and determines the magnitude and stability of the latter in time.” This principle is known as Liebig's Law of the Minimum.
The limiting factor can be not only a lack, as Liebig pointed out, but also an excess of such factors as, for example, heat, light and water. As noted earlier, organisms are characterized by ecological minimum and maximum. The range between these two values is usually called the limits of stability, or tolerance.
In general, the complexity of the influence of environmental factors on the body is reflected in the law of tolerance by W. Shelford: the absence or impossibility of prosperity is determined by the lack or, conversely, the excess of any of a number of factors, the level of which may be close to the limits tolerated by the given organism (1913). These two limits are called tolerance limits.
Numerous studies have been carried out on the "ecology of tolerance", thanks to which the limits of the existence of many plants and animals have become known. One such example is the effect of an air pollutant on the human body (Fig. 3).
Rice. 3. Effect of air pollutant on the human body. Max - maximum vital activity; Dop - allowable vital activity; Opt - optimal (not affecting vital activity) concentration of a harmful substance; MPC - the maximum allowable concentration of a substance that does not significantly change vital activity; Years - lethal concentration
The concentration of the influencing factor (harmful substance) in fig. 5.2 is marked with the symbol C. At concentration values C = C years, a person will die, but irreversible changes in his body will occur at much lower values C = C pdc. Therefore, the range of tolerance is limited precisely by the value C pdc = C lim. Hence, C MPC must be determined experimentally for each polluting or any harmful chemical compound and not allowed to exceed its C plc in a particular habitat (living environment).
In environmental protection, it is important upper limits of organism resistance to harmful substances.
Thus, the actual concentration of the pollutant C actual should not exceed C MPC (C actual ≤ C MPC = C lim).
The value of the concept of limiting factors (Clim) lies in the fact that it gives the ecologist a starting point in the study of complex situations. If an organism is characterized by a wide range of tolerance to a factor that is relatively constant, and it is present in the environment in moderate amounts, then this factor is unlikely to be limiting. On the contrary, if it is known that one or another organism has a narrow range of tolerance to some variable factor, then this factor deserves careful study, since it can be limiting.
The environment that surrounds living beings consists of many elements. They affect the life of organisms in different ways. The latter react differently to various environmental factors. Separate elements of the environment interacting with organisms are called environmental factors. The conditions of existence are a set of vital environmental factors, without which living organisms cannot exist. With regard to organisms, they act as environmental factors.
Classification of environmental factors.
All environmental factors accepted classify(distributed) into the following main groups: abiotic, biotic and anthropic. in Abiotic (abiogenic) factors are physical and chemical factors of inanimate nature. biotic, or biogenic, factors are the direct or indirect influence of living organisms both on each other and on the environment. Antropical (anthropogenic) In recent years, factors have been singled out as an independent group of factors among biotic ones, due to their great importance. These are factors of direct or indirect impact of man and his economic activity on living organisms and the environment.
abiotic factors.
Abiotic factors include elements of inanimate nature that act on a living organism. Types of abiotic factors are presented in Table. 1.2.2.
Table 1.2.2. Main types of abiotic factors
climatic factors.
All abiotic factors manifest themselves and operate within the three geological shells of the Earth: atmosphere, hydrosphere and lithosphere. Factors that manifest themselves (act) in the atmosphere and during the interaction of the latter with the hydrosphere or with the lithosphere are called climatic. their manifestation depends on the physical and chemical properties of the geological shells of the Earth, on the amount and distribution of solar energy that penetrates and enters them.
Solar radiation.
Solar radiation is of the greatest importance among the variety of environmental factors. (solar radiation). This is a continuous flow of elementary particles (velocity 300-1500 km/s) and electromagnetic waves (velocity 300 thousand km/s), which carries a huge amount of energy to the Earth. Solar radiation is the main source of life on our planet. Under the continuous flow of solar radiation, life originated on Earth, has passed a long way of its evolution and continues to exist and depend on solar energy. The main properties of the radiant energy of the Sun as an environmental factor is determined by the wavelength. Waves passing through the atmosphere and reaching the Earth are measured in the range from 0.3 to 10 microns.
According to the nature of the impact on living organisms, this spectrum of solar radiation is divided into three parts: ultraviolet radiation, visible light and infrared radiation.
shortwave ultraviolet rays almost completely absorbed by the atmosphere, namely its ozone layer. A small amount of ultraviolet rays penetrates the earth's surface. The length of their waves lies in the range of 0.3-0.4 microns. They account for 7% of the energy of solar radiation. Shortwave rays have a detrimental effect on living organisms. They can cause changes in hereditary material - mutations. Therefore, in the process of evolution, organisms that are under the influence of solar radiation for a long time have developed adaptations to protect themselves from ultraviolet rays. In many of them, an additional amount of black pigment, melanin, is produced in the integument, which protects against the penetration of unwanted rays. That is why people get tanned by being outdoors for a long time. In many industrial regions there is a so-called industrial melanism- darkening of the color of animals. But this does not happen under the influence of ultraviolet radiation, but due to pollution with soot, environmental dust, the elements of which usually become darker. Against such a dark background, darker forms of organisms survive (well masked).
visible light manifests itself within the wavelength range from 0.4 to 0.7 microns. It accounts for 48% of the energy of solar radiation.
It also adversely affects living cells and their functions in general: it changes the viscosity of the protoplasm, the magnitude of the electrical charge of the cytoplasm, disrupts the permeability of membranes and changes the movement of the cytoplasm. Light affects the state of protein colloids and the flow of energy processes in cells. But despite this, visible light was, is and will continue to be one of the most important sources of energy for all living things. Its energy is used in the process photosynthesis and accumulates in the form of chemical bonds in the products of photosynthesis, and then is transmitted as food to all other living organisms. In general, we can say that all living things in the biosphere, and even humans, depend on solar energy, on photosynthesis.
Light for animals is a necessary condition for the perception of information about the environment and its elements, vision, visual orientation in space. Depending on the conditions of existence, animals have adapted to varying degrees of illumination. Some animal species are diurnal, while others are most active at dusk or at night. Most mammals and birds lead a twilight lifestyle, do not distinguish colors well and see everything in black and white (dogs, cats, hamsters, owls, nightjars, etc.). Life in twilight or in low light often leads to hypertrophy of the eyes. Relatively huge eyes, capable of capturing an insignificant fraction of light, characteristic of nocturnal animals or those that live in complete darkness and are guided by the organs of luminescence of other organisms (lemurs, monkeys, owls, deep-sea fish, etc.). If, in conditions of complete darkness (in caves, underground in burrows), there are no other sources of light, then the animals living there, as a rule, lose their organs of vision (European proteus, mole rat, etc.).
Temperature.
The sources of the creation of the temperature factor on Earth are solar radiation and geothermal processes. Although the core of our planet is characterized by an extremely high temperature, its influence on the surface of the planet is insignificant, except for the zones of volcanic activity and the release of geothermal waters (geysers, fumaroles). Consequently, solar radiation, namely, infrared rays, can be considered the main source of heat within the biosphere. Those rays that reach the Earth's surface are absorbed by the lithosphere and hydrosphere. The lithosphere, as a solid body, heats up faster and cools just as quickly. The hydrosphere is more heat-capacious than the lithosphere: it heats up slowly and cools slowly, and therefore retains heat for a long time. The surface layers of the troposphere are heated due to the radiation of heat from the hydrosphere and the surface of the lithosphere. The earth absorbs solar radiation and radiates energy back into the airless space. Nevertheless, the Earth's atmosphere contributes to the retention of heat in the surface layers of the troposphere. Due to its properties, the atmosphere transmits short-wave infrared rays and delays long-wave infrared rays emitted by the heated surface of the Earth. This atmospheric phenomenon is called greenhouse effect. It was thanks to him that life on Earth became possible. The greenhouse effect helps to retain heat in the surface layers of the atmosphere (most organisms are concentrated here) and smooths out temperature fluctuations during the day and night. On the Moon, for example, which is located in almost the same space conditions as the Earth, and on which there is no atmosphere, daily temperature fluctuations at its equator are manifested in the range from 160 ° C to + 120 ° C.
The range of temperatures available in the environment reaches thousands of degrees (hot volcanic magma and the lowest temperatures of Antarctica). The limits within which life known to us can exist are quite narrow and equal to approximately 300 ° C, from -200 ° C (freezing in liquefied gases) to + 100 ° C (boiling point of water). In fact, most species and much of their activity is tied to an even narrower range of temperatures. The general temperature range of active life on Earth is limited by the following temperatures (Table 1.2.3):
Table 1.2.3 Temperature range of life on Earth
Plants adapt to different temperatures and even extreme ones. Those that tolerate high temperatures are called fertile plants. They are able to tolerate overheating up to 55-65 ° C (some cacti). Species growing at high temperatures tolerate them more easily due to a significant shortening of the size of the leaves, the development of a felt (pubescent) or, conversely, wax coating, etc. Plants without prejudice to their development are able to withstand prolonged exposure to low temperatures (from 0 to -10 ° C) are called cold-resistant.
Although temperature is an important environmental factor affecting living organisms, its effect is highly dependent on the combination with other abiotic factors.
Humidity.
Humidity is an important abiotic factor that is predetermined by the presence of water or water vapor in the atmosphere or lithosphere. Water itself is a necessary inorganic compound for the life of living organisms.
Water is always present in the atmosphere in the form water couples. The actual mass of water per unit volume of air is called absolute humidity, and the percentage of vapor relative to the maximum amount that air can contain, - relative humidity. Temperature is the main factor affecting the ability of air to hold water vapor. For example, at a temperature of +27°C, the air can contain twice as much moisture as at a temperature of +16°C. This means that the absolute humidity at 27°C is 2 times greater than at 16°C, while the relative humidity in both cases will be 100%.
Water as an ecological factor is extremely necessary for living organisms, because without it metabolism and many other related processes cannot be carried out. The metabolic processes of organisms take place in the presence of water (in aqueous solutions). All living organisms are open systems, so they are constantly losing water and there is always a need to replenish its reserves. For a normal existence, plants and animals must maintain a certain balance between the intake of water in the body and its loss. Large loss of body water (dehydration) lead to a decrease in its vital activity, and in the future - to death. Plants satisfy their water needs through precipitation, air humidity, and animals also through food. The resistance of organisms to the presence or absence of moisture in the environment is different and depends on the adaptability of the species. In this regard, all terrestrial organisms are divided into three groups: hygrophilic(or moisture-loving), mesophilic(or moderately moisture-loving) and xerophilic(or dry-loving). Regarding plants and animals separately, this section will look like this:
1) hygrophilic organisms:
- hygrophytes(plants);
- hygrophiles(animal);
2) mesophilic organisms:
- mesophytes(plants);
- mesophiles(animal);
3) xerophilic organisms:
- xerophytes(plants);
- xerophiles, or hygrophobia(animals).
Need the most moisture hygrophilous organisms. Among plants, these will be those that live on excessively moist soils with high air humidity (hygrophytes). In the conditions of the middle belt, they include among herbaceous plants that grow in shaded forests (sour, ferns, violets, gap-grass, etc.) and in open places (marigold, sundew, etc.).
Hygrophilous animals (hygrophiles) include those ecologically associated with the aquatic environment or with waterlogged areas. They need a constant presence of a large amount of moisture in the environment. These are animals of tropical rainforests, swamps, wet meadows.
mesophilic organisms require moderate amounts of moisture and are usually associated with moderate warm conditions and good mineral nutrition conditions. It can be forest plants and plants of open places. Among them there are trees (linden, birch), shrubs (hazel, buckthorn) and even more herbs (clover, timothy, fescue, lily of the valley, hoof, etc.). In general, mesophytes are a broad ecological group of plants. To mesophilic animals (mesophiles) belongs to the majority of organisms that live in temperate and subarctic conditions or in certain mountainous land regions.
xerophilic organisms - This is a fairly diverse ecological group of plants and animals that have adapted to arid conditions of existence with the help of such means: limiting evaporation, increasing the extraction of water and creating water reserves for a long period of lack of water supply.
Plants living in arid conditions overcome them in different ways. Some do not have structural adaptations to carry the lack of moisture. their existence is possible in arid conditions only due to the fact that at a critical moment they are at rest in the form of seeds (ephemeris) or bulbs, rhizomes, tubers (ephemeroids), very easily and quickly switch to active life and in a short period of time completely pass annual cycle of development. Efemeri mainly distributed in deserts, semi-deserts and steppes (stonefly, spring ragwort, turnip "box, etc.). Ephemeroids(from Greek. ephemeri and to look like)- these are perennial herbaceous, mainly spring, plants (sedges, grasses, tulips, etc.).
A very peculiar category of plants that have adapted to endure drought conditions is succulents and sclerophytes. Succulents (from the Greek. juicy) are able to accumulate a large amount of water in themselves and gradually use it. For example, some cacti of the North American deserts can contain from 1000 to 3000 liters of water. Water accumulates in leaves (aloe, stonecrop, agave, young) or stems (cacti and cactus-like spurges).
Animals obtain water in three main ways: directly by drinking or absorbing through the integument, along with food and as a result of metabolism.
Many species of animals drink water and in large enough quantities. For example, caterpillars of the Chinese oak silkworm can drink up to 500 ml of water. Some species of animals and birds require regular water consumption. Therefore, they choose certain springs and regularly visit them as watering places. Desert bird species fly daily to the oases, drink water there and bring water to their chicks.
Some animal species do not consume water by direct drinking, but can consume it by absorbing it with the entire surface of the skin. In insects and larvae that live in soil moistened with tree dust, their integuments are permeable to water. The Australian Moloch lizard absorbs rainfall moisture with its skin, which is extremely hygroscopic. Many animals get moisture from succulent food. Such succulent foods can be grass, succulent fruits, berries, bulbs and tubers of plants. The steppe tortoise living in the Central Asian steppes consumes water only from succulent food. In these regions, in places where vegetables are planted or on melons, turtles cause great damage by eating melons, watermelons, and cucumbers. Some predatory animals also get water by eating their prey. This is typical, for example, of the African fennec fox.
Species that feed exclusively on dry food and do not have the opportunity to consume water get it through metabolism, that is, chemically during the digestion of food. Metabolic water can be formed in the body due to the oxidation of fats and starch. This is an important way of obtaining water, especially for animals that inhabit hot deserts. For example, the red-tailed gerbil sometimes feeds only on dry seeds. Experiments are known when, in captivity, the North American deer mouse lived for about three years, eating only dry grains of barley.
food factors.
The surface of the Earth's lithosphere constitutes a separate living environment, which is characterized by its own set of environmental factors. This group of factors is called edaphic(from Greek. edafos- soil). Soils have their own structure, composition and properties.
Soils are characterized by a certain moisture content, mechanical composition, content of organic, inorganic and organo-mineral compounds, a certain acidity. Many properties of the soil itself and the distribution of living organisms in it depend on the indicators.
For example, certain types of plants and animals love soils with a certain acidity, namely: sphagnum mosses, wild currants, alders grow on acidic soils, and green forest mosses grow on neutral ones.
Beetle larvae, terrestrial mollusks and many other organisms also react to a certain acidity of the soil.
The chemical composition of the soil is very important for all living organisms. For plants, the most important are not only those chemical elements that they use in large quantities (nitrogen, phosphorus, potassium and calcium), but also those that are rare (trace elements). Some of the plants selectively accumulate certain rare elements. Cruciferous and umbrella plants, for example, accumulate 5-10 times more sulfur in their body than other plants.
Excess content of certain chemical elements in the soil can negatively (pathologically) affect animals. For example, in one of the valleys of Tuva (Russia), it was noticed that sheep were suffering from some specific disease, which manifested itself in hair loss, deformation of hooves, etc. Later it turned out that in this valley in the soil, water and some plants there was high selenium content. Getting into the body of sheep in excess, this element caused chronic selenium toxicosis.
The soil has its own thermal regime. Together with moisture, it affects soil formation, various processes taking place in the soil (physico-chemical, chemical, biochemical and biological).
Due to their low thermal conductivity, soils are able to smooth out temperature fluctuations with depth. At a depth of just over 1 m, daily temperature fluctuations are almost imperceptible. For example, in the Karakum Desert, which is characterized by a sharply continental climate, in summer, when the soil surface temperature reaches +59°C, in the burrows of gerbil rodents at a distance of 70 cm from the entrance, the temperature was 31°C lower and amounted to +28°C. In winter, during a frosty night, the temperature in the burrows of gerbils was +19°C.
The soil is a unique combination of physical and chemical properties of the surface of the lithosphere and the living organisms that inhabit it. The soil cannot be imagined without living organisms. No wonder the famous geochemist V.I. Vernadsky called the soil bio-inert body.
Orographic factors (relief).
The relief does not refer to such directly acting environmental factors as water, light, heat, soil. However, the nature of the relief in the life of many organisms has an indirect effect.
Depending on the size of the forms, the relief of several orders is rather conditionally distinguished: macrorelief (mountains, lowlands, intermountain depressions), mesorelief (hills, ravines, ridges, etc.) and microrelief (small depressions, irregularities, etc.). Each of them plays a certain role in the formation of a complex of environmental factors for organisms. In particular, relief affects the redistribution of factors such as moisture and heat. So, even slight depressions, a few tens of centimeters, create conditions of high humidity. From elevated areas, water flows into lower areas, where favorable conditions are created for moisture-loving organisms. The northern and southern slopes have different lighting and thermal conditions. In mountainous conditions, significant amplitudes of heights are created in relatively small areas, which leads to the formation of various climatic complexes. In particular, their typical features are low temperatures, strong winds, changes in the humidification regime, the gas composition of the air, etc.
For example, with rising above sea level, the air temperature drops by 6 ° C for every 1000 m. Although this is a characteristic of the troposphere, but due to the relief (highlands, mountains, mountain plateaus, etc.), terrestrial organisms may find themselves in conditions that are not similar to those in neighboring regions. For example, the mountainous volcanic massif of Kilimanjaro in Africa at the foot is surrounded by savannas, and higher up the slopes are plantations of coffee, bananas, forests and alpine meadows. The peaks of Kilimanjaro are covered with eternal snow and glaciers. If the air temperature at sea level is +30°C, then negative temperatures will already appear at an altitude of 5000 m. In temperate zones, a decrease in temperature for every 6°C corresponds to a movement of 800 km towards high latitudes.
Pressure.
Pressure is manifested in both air and water environments. In atmospheric air, the pressure varies seasonally, depending on the state of the weather and the height above sea level. Of particular interest are the adaptations of organisms that live in conditions of low pressure, rarefied air in the highlands.
The pressure in the aquatic environment varies depending on the depth: it grows by about 1 atm for every 10 m. For many organisms, there are limits to the change in pressure (depth) to which they have adapted. For example, abyssal fish (fish of the deep world) are able to endure great pressure, but they never rise to the surface of the sea, because for them it is fatal. Conversely, not all marine organisms are capable of diving to great depths. The sperm whale, for example, can dive to a depth of 1 km, and seabirds - up to 15-20 m, where they get their food.
Living organisms on land and aquatic environment clearly respond to pressure changes. At one time it was noted that fish can perceive even slight changes in pressure. their behavior changes when atmospheric pressure changes (eg, before a thunderstorm). In Japan, some fish are specially kept in aquariums and the change in their behavior is used to judge possible changes in the weather.
Terrestrial animals, perceiving slight changes in pressure, can predict changes in the state of the weather with their behavior.
Pressure unevenness, which is the result of uneven heating by the Sun and heat distribution both in water and in atmospheric air, creates conditions for mixing water and air masses, i.e. the formation of currents. Under certain conditions, the flow is a powerful environmental factor.
hydrological factors.
Water as an integral part of the atmosphere and lithosphere (including soil) plays an important role in the life of organisms as one of the environmental factors, which is called humidity. At the same time, water in the liquid state can be a factor that forms its own environment - water. Due to its properties, which distinguish water from all other chemical compounds, it in a liquid and free state creates a set of conditions for the aquatic environment, the so-called hydrological factors.
Such characteristics of water as thermal conductivity, fluidity, transparency, salinity manifest themselves in different ways in water bodies and are environmental factors, which in this case are called hydrological. For example, aquatic organisms have adapted differently to varying degrees of water salinity. Distinguish between freshwater and marine organisms. Freshwater organisms do not amaze with their species diversity. Firstly, life on Earth originated in sea waters, and secondly, fresh water bodies occupy a tiny part of the earth's surface.
Marine organisms are more diverse and quantitatively more numerous. Some of them have adapted to low salinity and live in desalinated areas of the sea and other brackish water bodies. In many species of such reservoirs, a decrease in body size is observed. So, for example, the shells of mollusks, edible mussel (Mytilus edulis) and Lamarck's heartworm (Cerastoderma lamarcki), which live in the bays of the Baltic Sea at a salinity of 2-6% o, are 2-4 times smaller than individuals that live in the same sea, only at a salinity of 15% o. The crab Carcinus moenas is small in the Baltic Sea, while it is much larger in desalinated lagoons and estuaries. Sea urchins grow smaller in lagoons than in the sea. The crustacean Artemia (Artemia salina) at a salinity of 122% o has a size of up to 10 mm, but at 20% o it grows to 24-32 mm. Salinity can also affect life expectancy. The same Lamarck's heartworm in the waters of the North Atlantic lives up to 9 years, and in the less saline waters of the Sea of \u200b\u200bAzov - 5.
The temperature of bodies of water is a more constant indicator than the temperature of land. This is due to the physical properties of water (heat capacity, thermal conductivity). The amplitude of annual temperature fluctuations in the upper layers of the ocean does not exceed 10-15 ° C, and in continental waters - 30-35 ° C. What can we say about the deep layers of water, which are characterized by a constant thermal regime.
biotic factors.
The organisms that live on our planet not only need abiotic conditions for their life, they interact with each other and are often very dependent on each other. The totality of factors of the organic world that affect organisms directly or indirectly is called biotic factors.
Biotic factors are very diverse, but despite this, they also have their own classification. According to the simplest classification, biotic factors are divided into three groups, which are caused by plants, animals and microorganisms.
Clements and Shelford (1939) proposed their own classification, which takes into account the most typical forms of interaction between two organisms - co-actions. All coactions are divided into two large groups, depending on whether organisms of the same species or two different ones interact. The types of interactions of organisms belonging to the same species is homotypic reactions. Heterotypic reactions name the forms of interaction between two organisms of different species.
homotypic reactions.
Among the interaction of organisms of the same species, the following coactions (interactions) can be distinguished: group effect, mass effect and intraspecific competition.
group effect.
Many living organisms that can live alone form groups. Often in nature you can observe how some species grow in groups plants. This gives them the opportunity to accelerate their growth. Animals are also grouped together. Under such conditions, they survive better. With a joint lifestyle, it is easier for animals to defend themselves, get food, protect their offspring, and survive adverse environmental factors. Thus, the group effect has a positive effect on all members of the group.
Groups in which animals are combined can be of different sizes. For example, cormorants, which form huge colonies on the coasts of Peru, can exist only if there are at least 10 thousand birds in the colony, and there are three nests per 1 square meter of territory. It is known that for the survival of African elephants, the herd must consist of at least 25 individuals, and the herd of reindeer - from 300-400 heads. A pack of wolves can number up to a dozen individuals.
Simple aggregations (temporary or permanent) can turn into complex groups consisting of specialized individuals that perform their own function in this group (families of bees, ants or termites).
Mass effect.
A mass effect is a phenomenon that occurs when a living space is overpopulated. Naturally, when united in groups, especially large ones, there is also some overpopulation, but there is a big difference between group and mass effects. The first gives advantages to each member of the association, and the other, on the contrary, suppresses the vital activity of all, that is, it has negative consequences. For example, the mass effect is manifested in the accumulation of vertebrates. If large numbers of experimental rats are kept in one cage, then acts of aggressiveness will appear in their behavior. With prolonged keeping of animals in such conditions, embryos dissolve in pregnant females, aggressiveness increases so much that rats gnaw off each other's tails, ears, and limbs.
The mass effect of highly organized organisms leads to a stressful state. In humans, this can cause mental disorders and nervous breakdowns.
Intraspecific competition.
Between individuals of the same species there is always a kind of competition in obtaining the best living conditions. The greater the population density of a particular group of organisms, the more intense the competition. Such competition of organisms of the same species among themselves for certain conditions of existence is called intraspecific competition.
Mass effect and intraspecific competition are not identical concepts. If the first phenomenon occurs for a relatively short time and subsequently ends with a rarefaction of the group (mortality, cannibalism, reduced fertility, etc.), then intraspecific competition exists constantly and ultimately leads to a wider adaptation of the species to environmental conditions. The species becomes more ecologically adapted. As a result of intraspecific competition, the species itself is preserved and does not destroy itself as a result of such a struggle.
Intraspecific competition can manifest itself in anything that organisms of the same species can claim. In plants that grow densely, competition may occur for light, mineral nutrition, etc. For example, an oak tree, when it grows alone, has a spherical crown, it is quite spreading, since the lower side branches receive a sufficient amount of light. In oak plantations in the forest, the lower branches are shaded by the upper ones. Branches that receive insufficient light die off. As the oak grows in height, the lower branches quickly fall off, and the tree takes on a forest shape - a long cylindrical trunk and a crown of branches at the top of the tree.
In animals, competition arises for a certain territory, food, nesting sites, etc. It is easier for mobile animals to avoid tough competition, but it still affects them. As a rule, those that avoid competition often find themselves in unfavorable conditions, they are forced, like plants (or attached animal species), to adapt to the conditions with which they have to be content.
heterotypic reactions.
Table 1.2.4. Forms of interspecies interactions
|
Species occupy |
Species occupy |
|||
|
Form of interaction (co-shares) |
same territory (living together) |
different territories (live separately) |
||
|
View A |
View B |
View A |
View B |
|
|
Neutralism |
||||
|
Comensalism (type A - comensal) |
||||
|
Protocooperation |
||||
|
Mutualism |
||||
|
Amensalism (type A - amensal, type B - inhibitor) |
||||
|
Predation (type A - predator, type B - prey) |
||||
|
Competition |
||||
0 - interaction between species does not benefit and does not harm either side;
Interactions between species produce positive consequences; -interaction between species has negative consequences.
Neutralism.
The most common form of interaction occurs when organisms of different species, occupying the same territory, do not affect each other in any way. A large number of species live in the forest, and many of them maintain neutral relationships. For example, a squirrel and a hedgehog inhabit the same forest, but they have a neutral relationship, like many other organisms. However, these organisms are part of the same ecosystem. They are elements of one whole, and therefore, with a detailed study, one can still find not direct, but indirect, rather subtle and imperceptible connections at first glance.
There is. Doom, in his Popular Ecology, gives a playful but very apt example of such connections. He writes that in England old single women support the power of the royal guards. And the connection between guardsmen and women is quite simple. Single women, as a rule, breed cats, while cats hunt mice. The more cats, the less mice in the fields. Mice are enemies of bumblebees, because they destroy their holes where they live. The fewer mice, the more bumblebees. Bumblebees are not known to be the only pollinators of clover. More bumblebees in the fields - more clover harvest. Horses graze on clover, and the guardsmen like to eat horse meat. Behind such an example in nature, one can find many hidden connections between various organisms. Although in nature, as can be seen from the example, cats have a neutral relationship with horses or jmels, they are indirectly related to them.
Commensalism.
Many types of organisms enter into relationships that benefit only one side, while the other does not suffer from this and nothing is useful. This form of interaction between organisms is called commensalism. Commensalism often manifests itself in the form of coexistence of various organisms. So, insects often live in the burrows of mammals or in the nests of birds.
Often one can also observe such a joint settlement, when sparrows nest in the nests of large birds of prey or storks. For birds of prey, the neighborhood of sparrows does not interfere, but for the sparrows themselves, this is a reliable protection of their nests.
In nature, there is even a species that is named like that - the commensal crab. This small, graceful crab readily settles in the mantle cavity of oysters. By this, he does not interfere with the mollusk, but he himself receives a shelter, fresh portions of water and nutrient particles that get to him with water.
Protocooperation.
The next step in the joint positive co-action of two organisms of different species is protocooperation, in which both species benefit from interaction. Naturally, these species can exist separately without any losses. This form of interaction is also called primary cooperation, or cooperation.
In the sea, such a mutually beneficial, but not obligatory, form of interaction arises when crabs and intestinales are combined. Anemones, for example, often take up residence on the dorsal side of crabs, camouflaging and protecting them with their stinging tentacles. In turn, the sea anemones receive from the crabs the bits of food left over from their meal, and use the crabs as a vehicle. Both crabs and sea anemones are able to freely and independently exist in the reservoir, but when they are nearby, the crab, even with its claws, transplants the sea anemones onto itself.
The joint nesting of birds of different species in the same colony (herons and cormorants, waders and terns of different species, etc.) is also an example of cooperation in which both parties benefit, for example, in protection from predators.
Mutualism.
Mutualism (or obligate symbiosis) is the next stage of mutually beneficial adaptation of different species to each other. It differs from protocooperation in its dependency. If, under protocooperation, the organisms that enter into a relationship can exist separately and independently of each other, then under mutualism, the existence of these organisms separately is impossible.
This type of coaction often occurs in quite different organisms, systematically remote, with different needs. An example of this would be the relationship between nitrogen-fixing bacteria (bubble bacteria) and legumes. Substances secreted by the root system of legumes stimulate the growth of bubble bacteria, and the waste products of bacteria lead to deformation of the root hairs, which begins the formation of bubbles. Bacteria have the ability to assimilate atmospheric nitrogen, which is deficient in the soil but an essential macronutrient for plants, which in this case is of great benefit to leguminous plants.
In nature, the relationship between fungi and plant roots is quite common, called mycorrhiza. The fungus, interacting with the tissues of the root, forms a kind of organ that helps the plant more effectively absorb minerals from the soil. Mushrooms from this interaction receive the products of photosynthesis of the plant. Many types of trees cannot grow without mycorrhiza, and certain types of fungi form mycorrhiza with the roots of certain types of trees (oak and porcini, birch and boletus, etc.).
A classic example of mutualism is lichens, which combine the symbiotic relationship of fungi and algae. The functional and physiological connections between them are so close that they are considered as a separate group organisms. The fungus in this system provides the algae with water and mineral salts, and the algae, in turn, gives the fungus organic substances that it synthesizes itself.
Amensalism.
In the natural environment, not all organisms positively influence each other. There are many cases when one species harms another in order to ensure its life. This form of coaction, in which one type of organism suppresses the growth and reproduction of an organism of another species without losing anything, is called amensalism (antibiosis). The suppressed species in a pair that interacts is called amensalom, and the one who suppresses - inhibitor.
Amensalism is best studied in plants. In the process of life, plants release chemicals into the environment, which are factors influencing other organisms. Regarding plants, amensalism has its own name - allelopathy. It is known that, due to the excretion of toxic substances by the roots, the Volokhatenky Nechuiweter displaces other annual plants and forms continuous single-species thickets over large areas. In fields, wheatgrass and other weeds crowd out or overwhelm crops. Walnut and oak oppress grassy vegetation under their crowns.
Plants can secrete allelopathic substances not only by their roots, but also by the aerial part of their body. Volatile allelopathic substances released by plants into the air are called phytoncides. Basically, they have a destructive effect on microorganisms. Everyone is well aware of the antimicrobial preventive effect of garlic, onion, horseradish. Many phytoncides are produced by coniferous trees. One hectare of common juniper plantations produces more than 30 kg of phytoncides per year. Often conifers are used in settlements to create sanitary protection belts around various industries, which helps to purify the air.
Phytoncides negatively affect not only microorganisms, but also animals. In everyday life, various plants have long been used to fight insects. So, baglitsa and lavender are a good way to fight moths.
Antibiosis is also known in microorganisms. Its first time was opened By. Babesh (1885) and rediscovered by A. Fleming (1929). Penicillu fungi have been shown to secrete a substance (penicillin) that inhibits bacterial growth. It is widely known that some lactic acid bacteria acidify their environment so that putrefactive bacteria that need an alkaline or neutral environment cannot exist in it. The allelopathic chemicals of microorganisms are known as antibiotics. More than 4 thousand antibiotics have already been described, but only about 60 of their varieties are widely used in medical practice.
Protection of animals from enemies can also be carried out by isolating substances that have an unpleasant odor (for example, among reptiles - vulture turtles, snakes; birds - hoopoe chicks; mammals - skunks, ferrets).
Predation.
Theft in the broad sense of the word is considered to be a way of obtaining food and feeding animals (sometimes plants), in which they catch, kill and eat other animals. Sometimes this term is understood as any eating of some organisms by others, i.e. relationships between organisms in which one uses the other as food. With this understanding, the hare is a predator in relation to the grass that it consumes. But we will use a narrower understanding of predation, in which one organism feeds on another, which is close to the first in a systematic way (for example, insects that feed on insects; fish that feed on fish; birds that feed on reptiles, birds and mammals; mammals, that feed on birds and mammals). An extreme case of predation, in which a species feeds on organisms of its own species, is called cannibalism.
Sometimes a predator selects a prey in such quantity that it does not negatively affect the size of its population. By this, the predator contributes to a better state of the prey population, which, moreover, has already adapted to the pressure of the predator. The birth rate in the populations of the prey is higher than is required for the usual maintenance of its numbers. Figuratively speaking, the prey population takes into account what the predator must select.
Interspecies competition.
Between organisms of different species, as well as between organisms of the same species, interactions arise due to which they try to get the same resource. Such co-actions between different species are called interspecific competition. In other words, we can say that interspecific competition is any interaction between populations of different species that adversely affects their growth and survival.
The consequences of such competition may be the displacement of one organism by another from a certain ecological system (the principle of competitive exclusion). At the same time, competition promotes the emergence of many adaptations through the process of selection, which leads to the diversity of species that exist in a particular community or region.
Competitive interaction may involve space, food or nutrients, light, and many other factors. Interspecific competition, depending on what it is based on, can lead either to the establishment of an equilibrium between two species, or, with more intense competition, to the replacement of a population of one species by a population of another. Also, the result of competition may be such that one species will displace the other in a different place or force it to move to other resources.
