Patterns of interaction of the organism with the environment. Patterns of interaction between organisms and the environment
Description.
1. Organism and habitat
2. Human health and environmental safety
3. Food quality
4. Environmental aspects of the demographic situation in Russia
5. Man and space
Conclusions and results
Bibliography
Extract from work.
FEDERAL AGENCY FOR EDUCATION
Saint Petersburg State University
service and economy
NOVGOROD BRANCH
Department of "Mathematical and natural sciences"
TEST
Discipline "Ecology"
Theme "Regularities of the relationship between organisms and the environment"
Completed:
Student of the 1st year of the 58th group of the specialty 080109
Blinova Olga Ivanovna FULL NAME. student
Record book number:___________
Checked:
____________________________
FULL NAME. teacher
Velikiy Novgorod
2009
- Organism and habitat……………………….….3
- Human health and environmental safety….3
- Food quality…………………………6
4) Environmental aspects of the demographic situation in Russia…………………………………………………….…6
5) Man and space…………………………………………8
Conclusions and results………………………………………….10
References…………………………………….11
1. Organism and habitat
One of the main conclusions of the teachings of V.I. Vernadsky about the biosphere was the idea of the relationship of all living organisms with each other and with the environment. The elementary unit of evolution - the population - is in dynamic equilibrium with other populations and with the environment. Such dynamic equilibria are called population waves. In no case should a person interfere with natural population waves (the 4th law of B. Commoner - nature knows best). Population size is the result of a dynamic balance between its biological potential and environmental resistance. When the resistance of the environment weakens, the population increases explosively.
The human population, like any other, is subject to the same laws. But, unlike other living organisms, man has sharply reduced the resistance of the environment, practically breaking the natural balances, overcoming the action of limiting factors. As already mentioned, man won in the competition with other species by learning to produce food in abundance, irrigate the fields and improve his dwellings, and also by creating means of combating disease-causing microbes and, thereby, cutting himself off from natural selection. With the help of technology, in order to meet their needs, humanity began to exploit natural resources, bringing them to almost complete depletion, which led to the disappearance of entire ecosystems (for example, deforestation of the planet), i.e. to a large extent, we support our own existence by depleting resources and decimating other populations.
However, having developed production excessively, man not only won, but also lost, since the factors listed above for his “victory” over nature hit the human population hard and painfully. An ecological danger looming over mankind, threatening, first of all, its health.
2. Human health and environmental safety
Health is a state of complete physical, mental and social well-being, and not just the absence of disease (WHO definition - World Health Organization).
Let us consider in more detail how pollution of the atmosphere, hydrosphere and soil affects the health of every person, nations and all mankind.
Air pollution. Potentially the most dangerous for human health are nuclear facilities, chemical industry facilities, oil refining, metallurgy, pipelines, and transport. In large cities, however, the leading source of air pollution is not industry, but motor vehicles. Car emissions contain toxic carbon monoxide and lead compounds, as well as soot, hydrocarbons, nitrogen oxides, etc. (more than 200 components in total). Since all these emissions are heavier than air and accumulate mainly near the surface of the earth, children with whom their parents walk along large highways are poisoned more than the adults accompanying them. The result is a dramatic increase in respiratory disease in today's children (even compared to the previous generation).
From the poisoning of the air along the highways, the leaves turn yellow and crumble from the trees. Bushes, leaves and grasses along the roads accumulate significant amounts of heavy metals, so picking mushrooms, berries, medicinal herbs, hay is not allowed in these places, since the meat and milk of domestic animals fed with such hay contain toxins that are dangerous to human health. Heavy metals are concentrated in the soil and root crops, mushrooms and berries, which not only reduces yields, but also poses a threat to health.
The hydrosphere is poisoned by the discharge of industrial wastewater. They currently pollute over a third of the world's river flow. In addition to oil and oil products, heavy metals, toxic pesticides, dioxins and radioactive waste, thermal water pollution is very dangerous, as a result of which water bodies “die”. Heat is one type of pollution. Warm sewage heats the reservoir, the solubility of oxygen in water decreases (which is so poorly soluble in it), the fish kill begins, the silting of the reservoir increases sharply, which eventually leads to its swamping.
According to Russian environmental authorities, the number of water bodies with a high level of water pollution is growing every year, the maximum allowable concentrations (MPC) of a number of harmful substances in these reservoirs are exceeded by 10 or more times (the definition of MPC and other environmental quality criteria will be discussed in topic 3). The most polluted sea areas of the Russian Federation include the Azov-Black Sea basin, the Northern Caspian, the Gulf of Finland of the Baltic Sea, the Gulf of Peter the Great of the Sea of Japan, the Barents Sea in the area of the Novaya Zemlya archipelago.
Not only the seas suffer, but also large and small rivers of Russia, in many of them, due to excessive pollution, swimming and fishing are unacceptable.
One of the most polluted places in Russia and, as some environmentalists believe, on the entire planet, turned out to be the town of Karabash in Chelyabinsk region, where a copper and sulfur plant operates, draining its raw sewage into a local river and lake. This village recorded the highest death rate per thousand inhabitants in the country, which is the result of many times exceeding environmental standards in the area.
Freshwater objects are also sources of drinking water, the quality of which has fallen catastrophically in Russia over the past decade. Raw water "from the tap" is now impossible to drink in any of the settlements of the Russian Federation.
Environmental safety is a state of protection of the vital interests of the individual, society, nature and the state from real and potential threats created by anthropogenic or natural impact on the environment. Environmental safety is the most important natural human need along with his need for food, water, clothing, housing. All human life is aimed at meeting the physical, spiritual and social needs, including ensuring environmental safety. The Ministry of Natural Resources of the Russian Federation in 1993 developed the program "Ecological Security of Russia", the Security Council of the Russian Federation in the same year discussed the issue of the state of health of the population of Russia (including in connection with the environmental situation in the country).
Russia, like the entire planet, is in an ecological crisis, to which, at the end of the last century, due to the transition period, economic and technological crises were added. As far back as the 70s of the last century, scientists have repeatedly warned about the detrimental impact of technogenic pollution on human health. At the beginning of this century, warnings about the possibility of man-made disasters have already begun to come from politicians. The possibility of such disasters arises due to the wear and tear of equipment that has been continuously operating at some industrial facilities for more than 60 years (accidents in mines, falling planes and helicopters, etc.).
At the same time, “silent” catastrophes occur every day, since discharges and emissions of pollution have the insidious property of accumulating, accumulating in the biosphere, and the catastrophe is approaching without explosions and firing, imperceptibly, but inevitably. At the same time, the adult population suffers from diseases of the liver, kidneys, and lungs caused by lead emissions; poor-quality water is the cause of diseases of the digestive system and excretory system. The main causes of childhood disability in areas of ecological trouble are damage to the respiratory organs, the central nervous system and the brain.
All of the above indicates that in the Russian Federation, environmental danger threatens the country's gene pool and hinders Russia's exit from the socio-economic crisis.
3. Food quality
One of the types of environmental security is food security, since it is one of the main factors determining the health of the country's population. The situation in this area in the Russian Federation deteriorated greatly in the early 90s of the last century due to the flow of uncontrolled deliveries of low-quality food from abroad, the weakening of control over the production and sale of food products. All this led to mass food poisoning, primarily low-quality alcoholic beverages.
One of the reasons for this deterioration was the poor technical equipment of many domestic enterprises. Food Industry and trade (most production capacities in this area have not been updated for 30 to 50 years!), low level of sanitary culture, use of low-quality raw materials, lack of production control due to the elimination of laboratory services in this industry.
The situation began to gradually improve at the beginning of the 21st century. in connection with the introduction of strict control over food quality, the elimination of numerous "points" that do not have licenses for the manufacture and trade of food products, the technical renovation of production facilities in the food industry.
4. Environmental aspects of the demographic situation in Russia
The demographic situation in Russia is closely related to environmental safety. In terms of the number of inhabitants, the Russian Federation ranks seventh in the world after China, India, the USA, Indonesia, Brazil and Pakistan. By the beginning of the XXI century. Russia came up with one of the highest rates of population loss (depopulation). The reasons for this are:
low birth rate, mass distribution of a one-child family that does not ensure the reproduction of the population;
high mortality, the level of which is one of the highest in Europe (16.3 people per thousand inhabitants);
huge losses of able-bodied men from accidents, poisoning and injuries (about 30% according to 2002 data), which is largely due to the growth of alcoholism and the low quality of alcoholic beverages;
family crisis, high divorce rate;
significant volumes of forced (often illegal) migration, including those due to environmental reasons (the problem of environmental refugees).
As can be seen, the causes of the demographic crisis in Russia lie not only in the social sphere, but in many respects are of an environmental nature. At the beginning of 2003, 143.1 million people lived in Russia. Demographers' forecasts are disappointing: by 2010 the population in the Russian Federation will be approximately 138-139 million people, and Russia will move from seventh to ninth place in the world in terms of population. Long-term forecasts indicate that if current trends continue, then in 5-6 decades, in the second half of the 21st century, the population of Russia will be reduced by about half.
To overcome negative demographic trends in Russia, it is necessary to:
improving the health status of the population, which will help reduce preventable mortality, especially for men of working age;
stimulation of the birth rate and strengthening of the family on the basis of improving the quality of living standards and material incentives for the birth of children;
the formation of certain social and spiritual and moral attitudes in society.
In 2005, there was a certain demographic turning point: the birth rate increased compared to previous years. This is probably due to some stabilization of the standard of living of the population and the manifestation of social optimism. The Presidential Program, adopted in 2006, is also aimed at correcting the depopulation situation in Russia, providing both stimulation of the birth rate in the country (material and social assistance to mothers) and reduction of mortality (support for pensioners and the disabled). If this program is carried out and the trend towards an increase in the birth rate continues and intensifies, then the gloomy forecasts of domestic and foreign demographers may not come true.
5. Man and Space
So far, we have been talking about the influence (mostly negative) of man on nature. But it is obvious that there is also an opposite influence: natural factors (and in this part we will talk about cosmic factors) undoubtedly affect the physiology and behavior of a person.
A few decades ago, it almost never occurred to anyone to connect their performance, well-being and emotional state with the activity of the Sun, the phases of the Moon, magnetic storms and other cosmic phenomena. The pioneer in this field was the Russian scientist Alexander Leonidovich Chizhevsky, who created heliobiology, a branch of biology that studies the influence of the Sun on the physiological and behavioral mechanisms of man. The fact that the Sun largely determines the functioning of plants and animals has been known to people since ancient times (flowering and fruiting in plants, mating seasons in animals, etc.). Rhythm inherent in cosmic bodies - the movement of the Earth, Sun, Moon and stars - is also an integral property of living organisms, a universal quality of all living things, the general principle of the organization of the universe. This property is manifested at all biological levels: cellular, tissue, organismal, ecosystem and biospheric.
Habitat- this is that part of nature that surrounds a living organism and with which it directly interacts. The components and properties of the environment are diverse and changeable. Any living being lives in a complex changing world, constantly adapting to it and regulating its life activity in accordance with its changes.
Organisms' adaptations to their environment are called adaptations. The ability to adapt is one of the main properties of life in general, as it provides the very possibility of its existence, the ability of organisms to survive and reproduce. Adaptations manifest themselves at different levels: from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. Adaptations arise and change during the evolution of species. Separate properties or elements of the environment that affect organisms are called environmental factors. Environmental factors are diverse. They may be necessary or, conversely, harmful to living beings, promote or hinder survival and reproduction. Environmental factors have a different nature and specificity of action. Environmental factors are divided into abiotic and biotic, anthropogenic.
In the complex of action of factors, it is possible to single out some patterns that are largely universal (general) in relation to organisms. These patterns include the rule of optimum, the rule of interaction of factors, the rule of limiting factors, and some others.
Optimum rule. In accordance with this rule, for an organism or a certain stage of its development, there is a range of the most favorable (optimal) value of the factor. The more significant the deviation of the action of the factor from the optimum, the more this factor inhibits the vital activity of the organism. This range is called the zone of oppression. The maximum and minimum tolerated values of the factor are critical points beyond which the existence of an organism is no longer possible.
The maximum population density is usually confined to the optimum zone. Zones of optimum for different organisms are not the same. The wider the amplitude of fluctuations of the factor, at which the organism can remain viable, the higher its stability, i.e. tolerance to this or that factor (from lat. tolerance - patience). Organisms with a wide amplitude of resistance belong to the group of eurybionts (Greek euri - wide, bios - life). Organisms with a narrow range of adaptation to factors are called stenobionts(Greek stenos - narrow). It is important to emphasize that the zones of optimum in relation to various factors differ, and therefore organisms fully show their potential capabilities if they exist under conditions of the entire spectrum of factors with optimal values.
Rule of interaction of factors. Its essence lies in the fact that some factors can enhance or mitigate the force of other factors. For example, an excess of heat can be somewhat mitigated by low air humidity, a lack of light for plant photosynthesis can be compensated by an increased content of carbon dioxide in the air, etc. It does not, however, follow that the factors can be interchanged. They are not interchangeable.
Rule of limiting factors. The essence of this rule lies in the fact that a factor that is in deficiency or excess (near critical points) negatively affects organisms and, in addition, limits the possibility of manifestation of the strength of other factors, including those at the optimum. Limiting factors usually determine the boundaries of the distribution of species, their ranges. The productivity of organisms depends on them.
A person by his activity often violates almost all of the listed patterns of factors. This is especially true for limiting factors (destruction of habitats, disruption of water and mineral nutrition, etc.).
It sounds trite, but the most important and important regularity in the "environment-organism" system is the inseparable connection and mutual influence of the environment and the organism. As an organism experiences the impact of the environment (the action of a complex of environmental factors), so the environment undergoes changes as a result of the impact of living organisms. We have already discussed that the appearance of the Earth would be completely different if there were no life on the planet (there would be no oxygen in the atmosphere, there would be no such thing as soil, and so on). We will consider these issues in more detail in the lessons on global (biospheric) ecology.
The above main regularity of the "environment-organism" system was formulated by V. I. Vernadsky and was called the law of unity of the organism and its habitat:
Life develops as a result of a constant exchange of matter and information based on the flow of energy in the total unity of the environment and the organisms inhabiting it. A.A. Gorelov. "Structure and Function of Ecosystems". Ecology. 1998 with - 117.
Despite some complexity of Vernadsky's language, the meaning of this regularity is obvious: in the total unity of the environment and the organisms inhabiting it (on a global scale - in the biosphere), there is a constant exchange of matter and information, which makes life possible.
A simple evolutionary-ecological principle follows from this: a species of organisms can exist as long as and insofar as its environment corresponds to the genetic possibilities of adapting this species to its fluctuations and changes. We have repeatedly spoken about the manifestation of this pattern when we pointed to a complex of specific adaptations to certain environmental conditions (see the two previous lessons).
The impact of a species on the environment is an important ecological regularity. Vernadsky noted that such an impact is evolutionarily increasing. This pattern was formulated in the form of the law of maximum biogenic energy (entropy) of Vernadsky-Bauer:
Any biological system, being in a mobile equilibrium with its natural environment and developing evolutionarily, increases its impact on the environment. The pressure on the environment grows until it is strictly limited by external factors: supersystems or other competitive systems.
In the effect of environmental factors on the body, we noted as the main regularity the possibility of distinguishing optimal and pessimal (critical) doses of the factor. However, such a concept as the "optimum factor" cannot be approached from a mechanistic position, in nature everything is much more complicated. This found expression in the law of ambiguity of the effect of a factor on an organism: any environmental factor affects the functions of the organism differently; The optimum factor for some physiological processes may differ from that for other processes. Thus, any specialist in plant physiology will tell you that the optimum temperature for photosynthesis and respiration is different in many cases.
What we said in the previous lesson about the interaction of environmental factors must be supplemented with the idea of relative compensation (interchangeability) of factors. The lack of some environmental factors can be compensated by another factor. For example, some lack of light can be compensated for by an abundance of carbon dioxide for plants. However, such compensation is possible only within certain limits. No matter how much carbon dioxide there is, but in complete darkness, photosynthesis will still not work.
The existence of limiting factors, described by Liebig, is reflected in Blackman's law of limiting factors and Shelford's law of tolerance. Environmental factors that have a pessimal significance under specific conditions make it especially difficult (limit) the possibility of the existence of a species under given conditions, despite and despite the optimal combination of other individual factors. The main difference between Blackman's and Shelford's laws and Liebig's rules is that these scientists have shown that not only a lack (minimum) of a factor, but also its excess (maximum) can hinder (limit) the development of an organism.
And in conclusion, I would like to point out one more regularity of the action of environmental factors on the body, which is of great practical importance. As we noted in one of the previous lessons, the theoretical basis for calculating MPC is the concept of limiting factors. An important problem is not only the need to take into account the interaction of factors, their synergistic (mutually reinforcing) action. It is necessary to determine the concept of the threshold of harmful action, that is, starting from what doses of the factor, we can talk about its harmful effects on health.
In this regard, the following regularities should be kept in mind. The rule of phase reactions ("benefit-harm") states that small concentrations of a toxicant act on the body in the direction of strengthening its functions (stimulation). This has given rise to claims about the usefulness of certain factors in small doses (such as radiation). However, this is a rather controversial statement. Thus, Nikolai Fedorovich Reimers points out that bringing biological systems out of equilibrium with the help of weak doses of toxicants cannot benefit them. For example, ethologists know that an increase in fertility can be a signal of biological distress. Physiologists have a notion of the "price of adaptation"; if we consider the stimulation of body functions with small doses of toxicants as an adaptation to toxic effects, then it is necessary to take into account the price of such adaptation: wear of adaptive mechanisms, accelerated aging, etc. Gorelov A.A. "Nature Management", M. 1999, C-76.
At the same time, the phase reaction rule finds its application in medicine; in fact, many drug treatments are based on the stimulating effect of various substances and agents. Therefore, the law of phase reactions should be taken into account and used for treatment when there is no other more optimal way out.
It must also be borne in mind that the phase reaction rule is valid for many, but not all, toxic substances. For example, in the action of cyanide, which blocks the respiratory chains and leads to almost instantaneous death, such phases can hardly be distinguished. The favorable effect of small doses of radiation, and, accordingly, the threshold and non-threshold concepts arising from its recognition / non-recognition are especially debatable. Radiobiologists are still fighting to the death, defending this or that concept.
Thus, some scientists argue about the favorable effect of small doses of radiation on certain functions (for example, an increase in the fertility of mice was observed when irradiated with 0.1-1.5 Gy). Accordingly, these scientists are supporters of the threshold concept: it is possible to determine the threshold of the harmful effects of radiation. Other scientists take the opposite point of view and point out that any, even insignificant, additional exposure to the background leads to additional mutations and carcinogenesis. From this they derive a non-threshold concept: no threshold can be set, and any additional (to the background) exposure should be recognized as harmful. A certain difficulty is the fact that people are genetically of different quality, and those doses that for the vast majority may be sub-threshold, for individual individuals may cause different effects Stadnitsky GV, Rodionov AI Ecology. C - 76.
Reimers writes that the arguments between the supporters of the concept of threshold and non-threshold are meaningless, since everything depends on the initial conditions and individual reactions. Reassuring statistics for the afflicted with the disease and his loved ones are of little comfort. It is difficult to disagree with this, although it is also difficult to deny the presence of a certain (including political) meaning in the dispute between threshold and non-threshold concepts. We will talk more about this complex social and biological problem in one of the special issues on social ecology.
Biotic factors of the terrestrial and aquatic environment of soils Biologically active substances of living organisms Anthropogenic factors General patterns of interaction between organisms and environmental factors The concept of a limiting factor. Liebig's minimum law Shelford's law Specificity of the impact of anthropogenic factors on the body Classification of organisms in relation to environmental factors 1. The conditions of feather grass steppes represent completely different regimes of abiotic factors.
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Lecture #7
- Biotic factors
- Concept, types of biotic factors.
- Biotic factors of the terrestrial and aquatic environment, soils
- Anthropogenic factors
- General patterns of interaction between organisms and environmental factors
- The concept of a limiting factor. Liebig's law of the minimum, Shelford's law
1. Biotic factors
Indirect interactions lie in the fact that some organisms are environment-forming in relation to others, and the priority here belongs, of course, to photosynthetic plants. For example, the local and global environment-forming function of forests is well known, including their role in soil and field protection and water protection. Directly in the conditions of the forest, a peculiar microclimate is created, which depends on the morphological features of the trees and allows specific forest animals, herbaceous plants, mosses, etc. to live here. The conditions of the feather grass steppes represent completely different regimes of abiotic factors. In reservoirs and streams, plants are the main source of such an important abiotic component of the environment as oxygen.
At the same time, plants serve as a direct habitat for other organisms. For example, in the tissues of a tree (in wood, bast, bark) many fungi develop, the fruiting bodies of which (tinder fungi) can be seen on the surface of the trunk; inside the leaves, fruits, stems of herbaceous and woody plants, many insects and other invertebrates live, and the hollows of trees are the usual habitat for a number of mammals and birds. For many species of secretly living animals, the feeding place is combined with the habitat.
Interactions between living organisms in terrestrial and aquatic environment
Interactions between living organisms (mainly animals) are classified in terms of their mutual reactions.
There are homotypic (from the Greek. homos - identical) reactions, i.e. interactions between individuals and groups of individuals of the same species, and heterotypic (from the Greek. heteros - different, different) - interactions between representatives different types. Among animals, there are species that can feed on only one type of food (monophages), on a more or less limited range of food sources (narrow or wide oligophages), or on many species, using not only plant, but also animal tissues (polyphages) for food. The latter include, for example, many birds that can eat both insects and plant seeds, or such a well-known species as a bear is a predator by nature, but willingly eats berries and honey.
The most common type of heterotypic interactions between animals is predation, that is, the direct pursuit and eating of some species by others, for example, insects by birds, herbivorous ungulates by carnivorous predators, small fish by larger ones, etc. Predation is widespread among invertebrates - insects, arachnids, worms, etc.
Other forms of interactions between organisms include the well-known pollination of plants by animals (insects); phoresia, i.e. transfer of one species to another (for example, plant seeds by birds and mammals); commensalism (community), when some organisms feed on the remains of food or the secretions of others, an example of which are hyenas and vultures that devour the remains of food from lions; synoikiu (cohabitation), for example, the use by some animals of habitats (burrows, nests) of other animals; neutralism, i.e., the mutual independence of different species living in a common territory.
One of the important types of interaction between organisms is competition, which is defined as the desire of two species (or individuals of the same species) to possess the same resource. Thus, intraspecific and interspecific competition are distinguished. Interspecific competition is considered, in addition, as the desire of one species to displace another species (competitor) from a given habitat.
However, real evidence of competition in natural (rather than experimental) conditions is difficult to find. Of course, two different individuals of the same species may try to take away pieces of meat or other food from each other, but such phenomena are explained by the different quality of the individuals themselves, their different adaptability to the same environmental factors. Any kind of organism is adapted not to any one factor, but to their complex, and the requirements of two different (even close) species do not coincide. Therefore, one of the two will be forced out in the natural environment not due to the competitive aspirations of the other, but simply because it is worse adapted to other factors. A typical example is the “competition” for light between coniferous and deciduous tree species in young stands.
Deciduous trees (aspen, birch) are ahead of pine or spruce in growth, but this cannot be considered competition between them: the former are simply better adapted to the conditions of clearings and burnt areas than the latter. Long-term work on the destruction of deciduous "weeds" with the help of herbicides and arboricides (chemical preparations for the destruction of herbaceous and shrubby plants), as a rule, did not lead to the "victory" of conifers, since not only light allowance, but also many other factors (such as biotic , and abiotic) did not meet their requirements.
All these circumstances a person must take into account when managing wildlife, when exploiting animals and plants, that is, when fishing or carrying out such economic activities as protecting plants in agriculture.
Soil biotic factors
As mentioned above, the soil is a bioinert body. Living organisms play an important role in the processes of its formation and functioning. These include, first of all, green plants that extract nutrients from the soil and return them back along with dying tissues.
But in the processes of soil formation, the decisive role is played by the living organisms inhabiting the soil (pedobionts): microbes, invertebrates, etc. Microorganisms play a leading role in the transformation of chemical compounds, the migration of chemical elements, and plant nutrition.
The primary destruction of dead organic matter is carried out by invertebrates (worms, molluscs, insects, etc.) in the process of feeding and excreting digestive products into the soil. Photosynthetic carbon fixation in the soil is carried out in some soil types by microscopic green and blue-green algae.
Soil microorganisms carry out the main destruction of minerals and lead to the formation of organic and mineral acids, alkalis, secrete enzymes synthesized by them, polysaccharides, phenolic compounds.
The most important link in the biogeochemical cycle of nitrogen is nitrogen fixation, which is carried out by nitrogen-fixing bacteria. It is known that the total production of nitrogen fixation by microbes is 160-170 million tons/year. It should also be mentioned that nitrogen fixation, as a rule, is symbiotic (together with plants) carried out by nodule bacteria located on plant roots.
Biologically active substances of living organisms
Among the environmental factors of a biotic nature are chemical compounds that are actively produced by living organisms. These are, in particular, phytoncides predominantly volatile substances formed by organisms by plants that kill microorganisms or inhibit their growth. These include glycosides, terpenoids, phenols, tannins and many other substances. For example, 1 hectare of deciduous forest emits about 2 kg of volatile substances per day, coniferous - up to 5 kg, juniper - about 30 kg. Therefore, the air of forest ecosystems has the most important sanitary and hygienic value, killing microorganisms that cause dangerous human diseases. For a plant, phytoncides perform the function of protection against bacterial, fungal infections, and protozoa. Plants are able to produce protective substances in response to their infection with pathogenic fungi.
Volatile substances of some plants can serve as a means of displacing other plants. The mutual influence of plants by releasing physiologically active substances into the environment is called allelopathy (from the Greek. allelon - mutually, pathos - suffering).
Organic substances formed by microorganisms and having the ability to kill microbes (or prevent their growth) are called antibiotics; a typical example is penicillin. Antibiotics also include antibacterial substances contained in plant and animal cells.
Dangerous alkaloids that have a toxic and psychotropic effect are found in many mushrooms, higher plants. Strongest headache, nausea up to loss of consciousness can occur as a result of a person’s long stay in the wild rosemary swamp.
Vertebrates and invertebrates have the ability to produce and secrete frightening, attracting, signaling, and killing substances. Among them are many arachnids (scorpion, karakurt, tarantula, etc.), reptiles. Man widely uses the poisons of animals and plants for medicinal purposes.
The joint evolution of animals and plants has developed in them the most complex information-chemical relationships. Let us give just one example: many insects distinguish their food species by smell, bark beetles, in particular, fly only to a dying tree, recognizing it by the composition of volatile resin terpenes.
Anthropogenic environmental factors
The entire history of scientific and technological progress is a combination of man's transformation of natural environmental factors for his own purposes and the creation of new ones that did not previously exist in nature.
The smelting of metals from ores and the production of equipment are impossible without the creation high temperatures, pressure, powerful electromagnetic fields. Obtaining and maintaining high yields of agricultural crops requires the production of fertilizers and means of chemical plant protection against pests and pathogens. Modern healthcare is unthinkable without chemo- and physiotherapy. These examples can be multiplied.
The achievements of scientific and technological progress began to be used for political and economic purposes, which was extremely manifested in the creation of special environmental factors affecting a person and his property: from firearms to means of mass physical, chemical and biological impact. In this case, we can directly speak about the totality of anthropotropic (ie, directed at the human body) and, in particular, anthropocidal environmental factors that cause environmental pollution.
On the other hand, in addition to such purposeful factors, in the process of exploitation and processing of natural resources, side chemical compounds and zones of high levels of physical factors are inevitably formed. In some cases, these processes can be of a spasmodic nature (in conditions of accidents and catastrophes) with severe environmental and material consequences. Hence, it was necessary to create methods and means of protecting a person from dangerous and harmful factors, which has now been realized in the system mentioned above - life safety.
In a simplified form, an indicative classification of anthropogenic environmental factors is presented in fig. one.
Rice. 1. Classification of anthropogenic environmental factors
2. General patterns of interaction between organisms and environmental factors
Any environmental factor is dynamic, changeable in time and space.
The warm season with the correct periodicity is replaced by the cold; more or less wide fluctuations in temperature, illumination, humidity, wind strength, etc. are observed during the day. All these are natural, fluctuations in environmental factors, but a person is also capable of influencing them. The impact of anthropogenic activity on the environment is manifested in the general case in a change in the regimes (absolute values and dynamics) of environmental factors, as well as in the composition of factors, for example, when xenobiotics are introduced into natural systems during production or special events, such as plant protection using pesticides or the application of organic and mineral fertilizers to the soil.
However, each living organism requires strictly defined levels, quantities (doses) of environmental factors, as well as certain limits of their fluctuations. If the regimes of all environmental factors correspond to the hereditarily fixed requirements of the organism (i.e., its genotype), then it is able to survive and produce viable offspring. The requirements and resistance of one or another type of organism to environmental factors determine the boundaries of the geographical zone within which it can live, i.e., its range. Environmental factors also determine the amplitude of fluctuations in the number of a particular species in time and space, which never remains constant, but varies more or less widely.
Law of the limiting factor
living organism in natural conditions simultaneously exposed to not one, but many environmental factors - both biotic and abiotic, and each factor is required by the body in certain quantities or doses. Plants need significant amounts of moisture, nutrients (nitrogen, phosphorus, potassium), but other substances, such as boron or molybdenum, are required in negligible amounts. Nevertheless, the lack or absence of any substance (both macro and microelements) adversely affects the state of the body, even if all the others are present in the required quantities. One of the founders of agricultural chemistry, the German scientist Justus Liebig (1803-1873), formulated the theory of mineral nutrition for plants. He found that the development of a plant or its condition does not depend on those chemical elements (or substances), that is, factors that are present in the soil in sufficient quantities, but on those that are not enough. For example, the content of nitrogen or phosphorus sufficient for a plant in the soil cannot compensate for the lack of iron, boron or potassium. If any (at least one) of the nutrients in the soil is less than required by a given plant, then it will develop abnormally, slowly, or have pathological deviations. Yu. Liebig formulated the results of his research in the form of a fundamentalthe law of the minimum.
The substance present in the minimum controls the yield, determines its size and stability over time.
Of course, the law of the minimum is valid not only for plants, but also for all living organisms, including humans. It is known that in some cases the lack of any elements in the body has to be compensated by the use of mineral water or vitamins.
Some scientists derive an additional consequence from the law of the minimum, according to which the organism is able to a certain extent to replace one deficient substance with another, that is, to compensate for the lack of one factor by the presence of another - functionally or physically close. However, these possibilities are extremely limited.
It is known, for example, that mother's milk for infants can be replaced with artificial mixtures, but artificial children who did not receive in the first hours of life mother's milk, as a rule, suffer from diathesis, manifested in a tendency to skin rashes, inflammation of the respiratory tract, etc.
Liebig's law is one of the fundamental laws of ecology.
However, at the beginning of the XX century, an American scientist Shelford showed that a substance (or any other factor) present not only in a minimum, but also in excess compared to the level required by the body, can lead to undesirable consequences for the body.
For example, even a slight deviation of the content of mercury in the body (in principle, a harmless element) from a certain norm leads to severe functional disorders (the well-known "Minamata disease"). The lack of moisture in the soil makes the nutrients present in it useless for the plant, but excessive moisture leads to similar consequences for reasons, for example, "suffocation" of the roots, acidification of the soil, and the occurrence of anaerobic processes. Many microorganisms, including those used in biological wastewater treatment plants, are very sensitive to the limits of the content of free hydrogen ions, i.e. to the acidity of the medium (pH).
Let us analyze what happens to the organism under the conditions of the dynamics of the regime of one or another ecological factor. If you place any animal or plant in an experimental chamber and change the air temperature in it, then the state (all life processes) of the organism will change. In this case, some best (optimal) level of this factor (Topt) for the organism will be revealed. at which its activity (A) will be maximum (Fig. 2.). But if the factor regimes deviate from the optimum in one or another (larger or smaller) side, then the activity will decrease. Upon reaching a certain maximum or minimum value, the factor will become incompatible with life processes. Changes will occur in the body that cause its death. These levels will thus prove fatal or lethal (Smolder and Tyr).
Theoretically, similar, although not absolutely similar, results can be obtained in experiments with a change in other factors: air humidity, the content of various salts in water, the acidity of the environment, etc. (see Fig. 2, b). The wider the amplitude of the fluctuations of the factor, at which the organism can remain viable, the higher its stability, i.e. tolerance to one or another factor (from lat. tolerance patience).
Rice. 2. The impact of the environmental factor on the body
Hence the word "tolerant" is translated as stable, tolerant, and tolerance can be defined as the ability of an organism to withstand deviations of environmental factors from the values that are optimal for its life activity.
From all of the above it followsW. Shelford's law, or the so-calledlaw of tolerance.
Any living organism has certain, evolutionarily inherited upper and lower limits of resistance (tolerance) to any environmental factor.
In this formulation, the law can be illustrated by a modified curve (Fig. 2, b), where the horizontal axis plots not temperature, but various other factors, both physical and chemical. For an organism, not only the range of the factor change is important, but also the speed with which the factor changes. Experiments are known when, with a sharp decrease in air temperature from +15 to -20 ° C, the caterpillars of some butterflies died, and with slow, gradual cooling, they were able to return to life after much lower temperatures. The law is formulated in such a way that it is valid for any environmental factor. In general, this is true. But exceptions are also possible, when there may not be an upper or lower limit of stability. We will consider a specific example of such an exception below.
However, the law of tolerance has another interpretation. The law of tolerance is associated with widespread ideas in ecology about limiting factors. There is no single interpretation of this concept, and different ecologists put completely different meanings into it.
It is believed, for example, that the environmental factor plays the role of a limiting factor if it is absent or is above or below the critical level (Dajo, 1975, p. 22); another interpretation is that a limiting factor is one that sets the framework for any process, phenomenon or existence of an organism (Reimers, 1990, p. 544); the same concept is used in connection with resources that limit population growth and can create a basis for competition (Riklefs, 1979, p. 255). According to Odum (1975, p. 145), any condition that approaches or goes beyond the limits of tolerance is a limiting factor. So, for anaerobic organisms, oxygen is considered a limiting factor, for phytoplankton in water - phosphorus, etc.
What is actually meant by this phrase? The answer to this question is extremely important in terms of applications and is associated with environmental pollution. Let's return to fig. 2, a. As you can see, the range between Tlet and Tlet represents the limits of survival, after which death occurs. At the same time, the actual range of organism resistance is much narrower. If in the experiment the mode of the factor is deviated from Topt, then the vital state of the organism (A) will decrease, and at certain upper or lower values of the factor, irreversible pathological changes will occur in the experimental organism. The body will go into a depressed, pessimal state. Even if you stop the experiment and return the factor to the optimum, the body will not be able to fully restore its state (health), although this does not mean that it will definitely die. Similar situations are well known in medicine: when people are exposed to harmful chemicals, noise, vibrations, etc. during their work experience, they develop occupational diseases. Thus, before the factor has a lethal effect on the organism, it may be limiting its vital state.
Any environmental factor dynamic in time and space (physical, chemical, biological) can be both lethal and limiting, depending on its magnitude. This gives grounds to formulate the following postulate, which has the significance of a law.
Any element of the environment can act as a limiting environmental factor if its level causes irreversible pathological changes in the organism and transfers it (the organism) to an irreversibly pessimal state, from which the organism is not able to exit, even if the level of this factor returns to the optimum.
This postulate is directly related to the sanitary protection of the environment and to the sanitary and hygienic regulation of chemical compounds in the air, soil, water, and food products.
On fig. 2, and the values of the factor, above which it will become limiting, are denoted by Tlim and Tlim.
In fact, the law of the limiting factor can be considered as a special case of a more general law - the law of tolerance, and it can be given the following applied formulation.
Any living organism has upper and lower thresholds (limits) of resistance to any environmental factor, beyond which this factor causes irreversible, persistent functional deviations in the body in certain organs and physiological (biochemical) processes, without directly leading to death.
The regularities considered and illustrated in Figure 2 a, b represent a general theory. But the data obtained in a real experiment, as a rule, do not allow one to construct such ideally symmetrical curves: the actual rates of deterioration in the vital state of an organism when the level of the factor deviates from the optimum in one direction or another are not the same.
The body may be more resistant to, for example, low temperatures or levels of other factors, but less resistant to high ones, as shown in Fig. 3. Accordingly, the pessimal parts of the tolerance curves will be more or less "steep". So, for heat-loving organisms, even a slight decrease in the temperature of the environment can have adverse (and irreversible) consequences for their condition, while an increase in temperature will give a slow, gradual effect.
The foregoing applies not only to environmental temperature, but also to other factors, such as the content of certain chemicals in water, pressure, humidity, etc. Moreover, in species that develop with transformation (many amphibians, arthropods), tolerance to the same factors on different stages ontogenesis may be different.
In all such situations, we are talking primarily about natural factors, i.e., those whose dynamics in time and space determined evolution, selection, and the development of adaptation.
The specifics of the impact of anthropogenic factors on the body
Some anthropogenic factors of purposeful action (see the classification in Fig. 1) are intended to overcome the resistance of the organism, to exclude its survival or the development of adaptation.
These are, for example, pesticides (toxic chemicals) used to destroy plant pests or weeds, antibiotics, synthetic poisons for domestic use - to combat synanthropic insects and rodents. The specificity of such substances is that they were not factors of evolution and natural selection: they simply did not exist in the environment, or their levels were imperceptible. There was no need for organisms to develop adaptive reactions in relation to them.
The latter also applies to abiotic factors of non-directional (side) effects. Thus, the levels of noise, vibration, temperature, etc. under production conditions go far beyond the limits of the body's tolerance, but in this case, these factors are ecologically significant only when their parameters exceed the upper limits of the body's resistance, i.e., the factors become limiting or lethal.
The same should be said about the main subject of environmental protection - pollutants dispersed in air, water, soil. The absence, for example, SO2 or asbestos dust in the air does not have any harmful effect on the body. And their presence can cause Negative consequences. Therefore, shown in Fig. 2, b, the general scheme of the impact of environmental factors on the body (hereinafter, we will only talk about the human body) can be presented in a different form (Fig. 2, c).
The concentration of the pollutant in the environment (C) is plotted along the horizontal axis, and the absence of this substance (C = 0) is optimal for the organism, and the optimum of its vital activity is located on the y-axis. Let us see what can happen when this substance appears in the environment. Depending on the individual characteristics of the organism (morphological, physiological), even a slight presence of a harmful substance (C\u003e 0) can cause a decrease in vital activity, although no irreversible changes will occur in the body. Thus, the inhabitants of many large industrial centers, of course, experience some discomfort, and perhaps malaise, in the presence of certain pollutants in the air or water. It is clear that as the content of these substances increases (C>>0), the condition of people will worsen, i.e., vital activity will decrease. But at the same time, the concentration of a pollutant can reach such a value at which irreversible pathological changes can occur in the body, which can be detected by the methods of modern medicine. This means that the body has a certain threshold of resistance (tolerance) to a particular substance; the factor, the level of which exceeds this threshold, can be considered as limiting from the point of view of ecology.
With these deviations from the normal state of life (optimal), the body can live for many years, but it can no longer be considered healthy. Recall the well-known concept Occupational Illness". In Fig. 2, the corresponding point is indicated by two symbols: in the language of ecology as C lim , and in the language of toxicology - as C since (threshold concentration).
A further increase in the concentration of a substance in the environment can lead to death (C years ).
Thus, if, due to objective circumstances, it is unrealistic to ensure the zero content of certain impurities, their concentrations should be limited to those values that do not exceed C since , experimentally established in experiments on animals or any other tests. Hence, the established threshold value of the substance content will have the meaning of the maximum permissible concentration (MAC). It is clear that in relation to the experimentally established value of C since the maximum allowable concentration is accepted with a certain "margin", i.e. it is usually lower than C since .
This issue is considered in more detail in the lecture “Rationing of anthropogenic impact on the environment”. Here, all these explanations were required only to demonstrate the connection between ecology and sanitary protection of the environment. As we can see, the latter is based on the ecological law of the limiting factor.
The law of the limiting factor is also at the basis of a set of measures for life safety. The anthropogenic environmental factors discussed above are dangerous because their regimes and levels go beyond the tolerance of the human body and become limiting.
From all of the above follows the first rule of environmental protection, expressed in the language of ecology.
To protect the environment means to ensure the composition and regimes of environmental factors within the limits of the inherited tolerance of a living (primarily human) organism, i.e. manage it in such a way that no factor is limiting in relation to it.
Classification of organisms in relation to environmental factors
The requirements for the amplitudes of fluctuations of factors (tolerance limit) are different for different organisms: for some, these limits are wider, for others, they are narrower. For example, carp can only live in fresh water, and the well-known common stickleback tolerates some salinity. Plants can be hygrophilic (demanding to water), mesophilic (preferring moderate humidity), xerophilic (dry-loving). Birch grows well on both relatively dry and moderately moist soils, while spruce prefers moderate flowing moisture. Thus, each species has certain limits of tolerance to various environmental factors that determine its distribution, abundance and change in numbers over time and space.
Figure 3 shows the limits of tolerance for various kinds: one of these species has wide limits of stability - eurythermal (from the Greek evry wide, different) and can live in conditions of a large amplitude of temperature changes ( II ); the other two - stenothermal (from the Greek stenos - narrow) - have much narrower stability limits, one of them in the range of relatively low, and the other - relatively high temperatures. However, the view I , adapted to low temperatures, is cryophilic (from the Greek krios - cold), and III - thermophilic. As we can see, the eurythermal species is able to develop and maintain activity with wide fluctuations of the factor, while the stenothermic ones reduce their activity even with slight deviations from the optimum.
Rice. 3. Limits of resistance (tolerance) of organisms to environmental factors on the example of temperature and classification of resistance of organisms
Similar patterns apply to other factors as well. For example, we have already mentioned hygrophiles and xerophiles. In relation to the content of salts in the habitat, euryhals and stenohals are distinguished (from the Greek hals - salt), in relation to the illumination - euryphotes and stenophots, in relation to the acidity of the environment - eurionic and stenoionic species.
It is quite clear that there are also limits to the resistance of organisms to pollutants: some plants or animals are more resistant to the presence of impurities in the air or water than others.
Using the terms already familiar to us, assessing the adaptability of organisms to living in conditions of wide and narrow amplitudes of changes in factors, we can talk about species that can live in a variety of habitats (eurytopic) and those whose distribution is limited by a narrow exactingness to environmental factors (stenotopic).
In conditions of constant adaptation to changing environmental factors, organisms in the process of evolution and natural selection develop hereditarily fixed features that ensure normal life in various environmental conditions, called adaptations . Individuals that for some reason have lost the ability to adapt to changes in the regimes of environmental factors are doomed to extinction.
The most typical examples of adaptation are morphological adaptations, for example, adaptation to fast swimming in aquatic animals, to survival in conditions of high temperatures and moisture deficiency in cacti and other succulents.
Behavioral (otological) adaptations are manifested, for example, in seasonal migrations of birds, hibernation of some animals, etc.
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Any environmental factor is dynamic, changeable in time and space.
The warm season with the correct periodicity is replaced by the cold; more or less wide fluctuations in temperature, illumination, humidity, wind strength, etc. are observed during the day. All these are natural, fluctuations in environmental factors, but a person is also capable of influencing them. The impact of anthropogenic activity on the environment is manifested in the general case in a change in the regimes (absolute values and dynamics) of environmental factors, as well as in the composition of factors, for example, when xenobiotics are introduced into natural systems during production or special events, such as plant protection using pesticides or the application of organic and mineral fertilizers to the soil.
However, each living organism requires strictly defined levels, quantities (doses) of environmental factors, as well as certain limits of their fluctuations. If the regimes of all environmental factors correspond to the hereditarily fixed requirements of the organism (i.e., its genotype), then it is able to survive and produce viable offspring. The requirements and resistance of one or another type of organism to environmental factors determine the boundaries of the geographical zone within which it can live, i.e., its range. Environmental factors also determine the amplitude of fluctuations in the number of a particular species in time and space, which never remains constant, but varies more or less widely.
Law of the limiting factor
A living organism under natural conditions is simultaneously exposed to not one, but many environmental factors - both biotic and abiotic, and each factor is required by the body in certain quantities or doses. Plants need significant amounts of moisture, nutrients (nitrogen, phosphorus, potassium), but other substances, such as boron or molybdenum, are required in negligible amounts. Nevertheless, the lack or absence of any substance (both macro and microelements) adversely affects the state of the body, even if all the others are present in the required quantities. One of the founders of agricultural chemistry, the German scientist Justus Liebig (1803-1873), formulated the theory of mineral nutrition for plants. He found that the development of a plant or its condition does not depend on those chemical elements (or substances), that is, factors that are present in the soil in sufficient quantities, but on those that are not enough. For example, the content of nitrogen or phosphorus sufficient for a plant in the soil cannot compensate for the lack of iron, boron or potassium. If any (at least one) of the nutrients in the soil is less than required by a given plant, then it will develop abnormally, slowly, or have pathological deviations. Yu. Liebig formulated the results of his research in the form of a fundamental the law of the minimum.