Ecological factors and their classification.
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 acting on 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 - various forms of activity human society, which lead to a change in nature as the habitat of 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 valency, 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 effect 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, that is, those that are most distant from the optimum, especially make it difficult for the species to exist in 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.
Identification of limiting factors is very important in practice Agriculture to establish ecological valency, especially in the most vulnerable (critical) periods of animal and plant ontogeny.
Environmental factors
The interaction of man and his environment has been the object of study of medicine at all times. To assess the effects of various environmental conditions, the term "environmental factor" was proposed, which is widely used in environmental medicine.
Factor (from the Latin factor - making, producing) - the reason, the driving force of any process, phenomenon, which determines its nature or certain features.
An environmental factor is any environmental impact that can have a direct or indirect effect on living organisms. An environmental factor is an environmental condition to which a living organism reacts with adaptive reactions.
Environmental factors determine the conditions for the existence of organisms. The conditions for the existence of organisms and populations can be considered as regulatory environmental factors.
Not all environmental factors (for example, light, temperature, humidity, presence of salts, availability of nutrients, etc.) are equally important for the successful survival of an organism. The relationship of the organism with the environment is a complex process in which the weakest, "vulnerable" links can be distinguished. Those factors that are critical or limiting for the life of an organism are of greatest interest, primarily from a practical point of view.
The idea that the endurance of an organism is determined by the weakest link among
of all his needs, was first expressed by K. Liebig in 1840. He formulated the principle, which is known as Liebig's law of the minimum: "The crop is controlled by a substance that is at a minimum, and the magnitude and stability of the latter in time is determined."
The modern formulation of J. Liebig's law is as follows: "The life possibilities of an ecosystem are limited by those of the ecological environmental factors, the quantity and quality of which are close to the minimum required by the ecosystem, their reduction leads to the death of the organism or the destruction of the ecosystem."
The principle, originally formulated by K. Liebig, is currently extended to any environmental factors, but it is supplemented by two restrictions:
Applies only to systems that are in a stationary state;
It refers not only to one factor, but also to a complex of factors that are different in nature and interact in their influence on organisms and populations.
According to the prevailing ideas, the limiting factor is considered to be such a factor, according to which, in order to achieve a given (sufficiently small) relative change in the response, a minimum relative change in this factor is required.
Along with the influence of a lack, a "minimum" of environmental factors, the influence of an excess, that is, a maximum of factors such as heat, light, moisture, can also be negative. The concept of the limiting influence of the maximum, along with the minimum, was introduced by W. Shelford in 1913, who formulated this principle as the "law of tolerance": The limiting factor for the prosperity of an organism (species) can be both a minimum and a maximum of environmental impact, the range between which determines the value of endurance ( tolerance) of the body in relation to this factor.
The law of tolerance, formulated by W. Shelford, was supplemented with a number of provisions:
Organisms may have a wide tolerance range for one factor and a narrow tolerance for another;
The most widespread are organisms with a large range of tolerance;
The range of tolerance for one environmental factor may depend on other environmental factors;
If the conditions for one ecological factor are not optimal for the species, then this also affects the range of tolerance for other environmental factors;
The limits of tolerance significantly depend on the state of the organism; thus, the limits of tolerance for organisms during the breeding season or at an early stage of development are usually narrower than for adults;
The range between the minimum and maximum of environmental factors is commonly called the limits or range of tolerance. To indicate the limits of tolerance to environmental conditions, the terms "eurybiontic" - an organism with a wide tolerance limit - and "stenobiont" - with a narrow one are used.
At the level of communities and even species, the phenomenon of factor compensation is known, which is understood as the ability to adapt (adapt) to environmental conditions in such a way as to weaken the limiting influence of temperature, light, water and other physical factors. Species with a wide geographical distribution almost always form populations adapted to local conditions - ecotypes. In relation to people, there is the term ecological portrait.
It is known that not all natural environmental factors are equally important for human life. So, the most significant consider the intensity of solar radiation, air temperature and humidity, the concentration of oxygen and carbon dioxide in the surface layer of air, the chemical composition of soil and water. The most important environmental factor is food. To maintain life, for the growth and development, reproduction and preservation of the human population, energy is needed, which is obtained from the environment in the form of food.
There are several approaches to the classification of environmental factors.
In relation to the body, environmental factors are divided into: external (exogenous) and internal (endogenous). It is believed that external factors acting organism, they themselves are not subject or almost not subject to its influence. These include environmental factors.
External environmental factors in relation to the ecosystem and to living organisms are the impact. The response of an ecosystem, biocenosis, populations and individual organisms to these impacts is called a response. The nature of the response to the impact depends on the ability of the body to adapt to environmental conditions, adapt and acquire resistance to the influence of various environmental factors, including adverse effects.
There is also such a thing as a lethal factor (from Latin - letalis - deadly). This is an environmental factor, the action of which leads to the death of living organisms.
When certain concentrations are reached, many chemical and physical pollutants can act as lethal factors.
Internal factors correlate with the properties of the organism itself and form it, i.e. are included in its composition. Internal factors are the number and biomass of populations, the amount of various chemicals, the characteristics of the water or soil mass, etc.
According to the criterion of "life" environmental factors are divided into biotic and abiotic.
The latter include non-living components of the ecosystem and its external environment.
Abiotic environmental factors - components and phenomena of inanimate, inorganic nature, directly or indirectly affecting living organisms: climatic, soil and hydrographic factors. The main abiotic environmental factors are temperature, light, water, salinity, oxygen, electromagnetic characteristics, and soil.
Abiotic factors are divided into:
Physical
Chemical
Biotic factors (from the Greek biotikos - life) - factors of the living environment that affect the vital activity of organisms.
Biotic factors are divided into:
Phytogenic;
microbiogenic;
Zoogenic:
Anthropogenic (socio-cultural).
The action of biotic factors is expressed in the form of mutual influences of some organisms on the vital activity of other organisms and all together on the environment. Distinguish between direct and indirect relationships between organisms.
In recent decades, the term anthropogenic factors has been increasingly used, i.e. caused by man. Anthropogenic factors are opposed to natural, or natural factors.
The anthropogenic factor is a set of environmental factors and impacts caused by human activity in ecosystems and the biosphere as a whole. The anthropogenic factor is the direct impact of a person on organisms or the impact on organisms through a change by a person in their habitat.
Environmental factors are also divided into:
1. Physical
Natural
Anthropogenic
2. Chemical
Natural
Anthropogenic
3. Biological
Natural
Anthropogenic
4. Social (socio-psychological)
5. Informational.
Environmental factors are also divided into climatic-geographical, biogeographical, biological, as well as soil, water, atmospheric, etc.
physical factors.
Physical natural factors include:
Climatic, including the microclimate of the area;
geomagnetic activity;
Natural radiation background;
Cosmic radiation;
Terrain;
Physical factors are divided into:
Mechanical;
vibration;
Acoustic;
EM radiation.
Physical anthropogenic factors:
Microclimate of settlements and premises;
Pollution of the environment by electromagnetic radiation (ionizing and non-ionizing);
Noise pollution of the environment;
Thermal pollution of the environment;
Deformation of the visible environment (changes in the terrain and colors in populated areas).
chemical factors.
Natural chemicals include:
Chemical composition of the lithosphere:
Chemical composition of the hydrosphere;
Chemical atmospheric composition,
The chemical composition of food.
The chemical composition of the lithosphere, atmosphere and hydrosphere depends on the natural composition + the release of chemicals as a result of geological processes (for example, hydrogen sulfide impurities as a result of a volan eruption) and the vital activity of living organisms (for example, impurities in the air of phytoncides, terpenes).
Anthropogenic chemical factors:
household waste,
Industrial waste,
Synthetic materials used in everyday life, agriculture and industrial production,
pharmaceutical industry products,
Food additives.
The effect of chemical factors on the human body can be due to:
Excess or deficiency of natural chemical elements in
environment (natural microelementoses);
Excess content of natural chemical elements in the environment
environment associated with human activities (anthropogenic pollution),
The presence in the environment of unusual chemical elements
(xenobiotics) due to anthropogenic pollution.
Biological factors
Biological, or biotic (from the Greek biotikos - life) environmental factors - factors of the living environment that affect the vital activity of organisms. The action of biotic factors is expressed in the form of mutual influences of some organisms on the vital activity of others, as well as their joint influence on the environment.
Biological factors:
bacteria;
Plants;
Protozoa;
Insects;
Invertebrates (including helminths);
Vertebrates.
Social environment
Human health is not completely determined by the biological and psychological properties acquired in ontogenesis. Man is a social being. He lives in a society governed by state laws, on the one hand, and on the other, by the so-called generally accepted laws, moral principles, rules of conduct, including those involving various restrictions, etc.
Every year society becomes more and more complex and has an increasing impact on the health of the individual, population, and society. For enjoying the benefits of a civilized society, a person must live in rigid dependence on the way of life accepted in society. For these benefits, often very dubious, the person pays with part of his freedom, or completely with all his freedom. And a person who is not free, dependent cannot be completely healthy and happy. Some part of human freedom, given to a technocritical society in exchange for the advantages of a civilized life, constantly keeps him in a state of neuropsychic tension. Constant neuro-psychic overstrain and overstrain leads to a decrease in mental stability due to a decrease in the reserve capabilities of the nervous system. In addition, there are many social factors that can lead to the disruption of a person's adaptive capabilities and the development of various diseases. These include social disorder, uncertainty about the future, moral oppression, which are regarded as the leading risk factors.
Social factors
Social factors are divided into:
1. social system;
2. production sphere (industry, agriculture);
3. household sphere;
4. education and culture;
5. population;
6. zo and medicine;
7. other spheres.
There is also the following grouping of social factors:
1. Social politics, forming a sociotype;
2. Social security, which has a direct impact on the formation of health;
3. Environmental policy that forms the ecotype.
Sociotype is an indirect characteristic of the integral social burden in terms of the totality of factors of the social environment.
Sociotype includes:
2. working conditions, rest and life.
Any environmental factor in relation to a person can be: a) favorable - contributing to his health, development and realization; b) unfavorable, leading to his illness and degradation, c) influencing both. It is no less obvious that in reality most influences are of the latter type, having both positive and negative aspects.
In ecology, there is a law of optimum, according to which any ecological
the factor has certain limits of positive influence on living organisms. The optimal factor is the intensity of the environmental factor that is most favorable for the organism.
The impacts can also differ in scale: some affect the entire population of the country as a whole, others affect the inhabitants of a particular region, others affect groups identified by demographic characteristics, and others affect an individual citizen.
Interaction of factors - simultaneous or sequential total impact on organisms of various natural and anthropogenic factors, leading to a weakening, strengthening or modification of the action of a single factor.
Synergism is the combined effect of two or more factors, characterized by the fact that their combined biological effect significantly exceeds the effect of each component and their sum.
It should be understood and remembered that the main harm to health is caused not by individual environmental factors, but by the total integral environmental load on the body. It consists of an ecological burden and a social burden.
Environmental burden is a combination of factors and conditions of the natural and man-made environment that are unfavorable for human health. An ecotype is an indirect characteristic of an integral ecological load based on a combination of factors of the natural and man-caused environment.
Ecotype assessments require hygiene data on:
The quality of housing
drinking water,
air,
Soil, food,
Medicines, etc.
Social burden is a set of factors and conditions of social life unfavorable for human health.
Environmental factors that shape the health of the population
1. Climatic-geographical characteristics.
2. Socio-economic characteristics of the place of residence (city, village).
3. Sanitary and hygienic characteristics of the environment (air, water, soil).
4. Features of nutrition of the population.
5. Feature labor activity:
Profession,
Sanitary and hygienic working conditions,
The presence of occupational hazards,
Psychological microclimate at work,
6. Family and household factors:
family composition,
The nature of the housing
Average income for 1 family member,
Organization of family life.
Distribution of non-working time,
Psychological climate in the family.
Indicators that characterize the attitude to the state of health and determine the activity to maintain it:
1. Subjective assessment of one's own health (healthy, sick).
2. Determining the place of personal health and the health of family members in the system of individual values (hierarchy of values).
3. Awareness about the factors contributing to the preservation and promotion of health.
4. Availability bad habits and dependencies.
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. V 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) factors in last years allocate in independent group factors among biotic, 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 the 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. Greenhouse effect contributes to the retention of 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 appear 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 zone, 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 conditions mineral nutrition. 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), they 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 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 conventionally 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 mode of humidification, gas composition of air, etc.
For example, with rise 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 that 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. First, 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. For example, shells of mollusks, edible mussel (Mytilus edulis) and Lamarck's heartworm (Cerastoderma lamarcki), which live in bays Baltic Sea at a salinity of 2-6% o, 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 shapes interactions 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 animals. 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. It can cause a person mental disorders and nervous breakdowns.
Intraspecific competition.
Between individuals of the same species there is always a kind of competition in obtaining better conditions existence. 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 on a relatively a 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 |
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|
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.
Eat. 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 Volokhatensky nechuiweter displaces other annual plants and forms continuous single-species thickets over large areas. In fields, wheatgrass and other weeds crowd out or overwhelm crop plants. 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 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 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.
Any properties or components of the environment that affect organisms are called environmental factors. Light, heat, the concentration of salts in water or soil, wind, hail, enemies and pathogens - all these are environmental factors, the list of which can be very long.
Among them are distinguished abiotic related to inanimate nature, and biotic associated with the influence of organisms on each other.
Environmental factors are extremely diverse, and each species, experiencing their influence, responds to it in a different way. However, there are some general laws that govern the responses of organisms to any environmental factor.
Chief among them - law of optimum. It reflects how living organisms tolerate different strengths of environmental factors. The strength of each of them is constantly changing. We live in a world with variable conditions, and only in certain places on the planet are the values of some factors more or less constant (in the depths of caves, at the bottom of the oceans).
The law of optimum is expressed in the fact that any environmental factor has certain limits of positive impact on living organisms.
When deviating from these limits, the sign of the impact changes to the opposite. For example, animals and plants do not tolerate extreme heat and extreme cold; average temperatures are optimal. In the same way, both drought and constant heavy rains are equally unfavorable for the crop. The law of optimum indicates the measure of each factor for the viability of organisms. On the graph, it is expressed as a symmetrical curve showing how the life activity of the species changes with a gradual increase in the impact of the factor (Fig. 13).
Figure 13. Scheme of the action of environmental factors on living organisms. 1,2 - critical points
(click on image to enlarge image)
In the center under the curve - optimum zone. At optimal values of the factor, organisms actively grow, feed, and multiply. The more the value of the factor deviates to the right or to the left, i.e., in the direction of decreasing or increasing the strength of action, the less favorable it is for organisms. The curve reflecting vital activity drops sharply down on both sides of the optimum. Here are two pessimum zones. At the intersection of a curve with a horizontal axis, there are two critical points. These are the values of the factor that organisms can no longer withstand, beyond which death occurs. The distance between the critical points shows the degree of endurance of organisms to a change in the factor. Conditions close to critical points are especially hard to survive. Such conditions are called extreme.
If you draw curves for the optimum of a factor, such as temperature, for different species, then they will not coincide. Often what is optimal for one species is pessimistic for another, or even outside the critical points. Camels and jerboas could not live in the tundra, and reindeer and lemmings could not live in the hot southern deserts.
The ecological diversity of species is also manifested in the position of critical points: in some they are close, in others they are widely spaced. This means that a number of species can live only in very stable conditions, with a slight change in environmental factors, while others withstand wide fluctuations. For example, a touchy plant withers if the air is not saturated with water vapor, and feather grass tolerates changes in humidity well and does not die even in drought.
Thus, the law of optimum shows us that each species has its own measure of the influence of each factor. Both a decrease and an increase in exposure beyond this measure lead to the death of organisms.
To understand the relationship of species with the environment, it is equally important limiting factor law.
In nature, organisms are simultaneously affected by a whole complex of environmental factors in different combinations and with different strengths. It is not easy to isolate the role of each of them. Which one means more than the other? What we know about the law of the optimum allows us to understand that there are no entirely positive or negative, important or secondary factors, but everything depends on the strength of the influence of each.
The law of the limiting factor states that the most significant factor is the one that deviates the most from the optimal values for the organism.
It is on him that the survival of individuals depends in this particular period. In other periods of time, other factors may become limiting, and during the course of life, organisms encounter a variety of restrictions on their vital activity.
The practice of agriculture is constantly confronted with the laws of the optimum and the limiting factor. For example, the growth and development of wheat, and consequently, the harvest is constantly limited either by critical temperatures, or by a lack or excess of moisture, or by a lack of mineral fertilizers, and sometimes by such catastrophic effects as hail and storms. It takes a lot of effort and money to maintain optimal conditions for crops, and at the same time, in the first place, to compensate or mitigate the effect of precisely the limiting factors.
living conditions various kinds amazingly varied. Some of them, for example, some small mites or insects, spend their whole lives inside the leaf of a plant, which for them is the whole world, others master vast and diverse spaces, such as reindeer, whales in the ocean, migratory birds.
Depending on where representatives of different species live, they are affected by different sets of environmental factors. On our planet, there are several basic living environments, greatly differing in the conditions of existence: water, ground-air, soil. The organisms themselves, in which others live, also serve as habitats.
Aquatic life environment. All aquatic inhabitants, despite differences in lifestyle, must be adapted to the main features of their environment. These features are determined, first of all, by the physical properties of water: its density, thermal conductivity, and the ability to dissolve salts and gases.
Density water determines its significant buoyant force. This means that the weight of organisms is lightened in water and it becomes possible to lead a permanent life in the water column without sinking to the bottom. Many species, mostly small ones, incapable of fast active swimming, seem to hover in the water, being in it in a suspended state. The collection of such small aquatic inhabitants is called plankton. The composition of plankton includes microscopic algae, small crustaceans, fish eggs and larvae, jellyfish and many other species. Planktonic organisms are carried by the currents, unable to resist them. The presence of plankton in the water makes possible the filtration type of nutrition, i.e., straining, with the help of various devices, of small organisms and food particles suspended in water. It is developed in both swimming and sedentary bottom animals, such as sea lilies, mussels, oysters and others. A sedentary lifestyle would be impossible for aquatic inhabitants if there were no plankton, and it, in turn, is possible only in an environment with sufficient density.
The density of water makes it difficult to actively move in it, so fast swimming animals, such as fish, dolphins, squids, must have strong muscles and a streamlined body shape. Due to the high density of water, pressure increases strongly with depth. Deep-sea inhabitants are able to endure pressure, which is thousands of times higher than on the land surface.
Light penetrates into the water only to a shallow depth, so plant organisms can exist only in the upper horizons of the water column. Even in the cleanest seas, photosynthesis is possible only to depths of 100-200 m. There are no plants at great depths, and deep-sea animals live in complete darkness.
Temperature regime in water bodies is softer than on land. Due to the high heat capacity of water, temperature fluctuations in it are smoothed out, and aquatic inhabitants do not face the need to adapt to severe frosts or forty-degree heat. Only in hot springs can the water temperature approach the boiling point.
One of the difficulties of the life of aquatic inhabitants is limited amount of oxygen. Its solubility is not very high and, moreover, it greatly decreases when the water is contaminated or heated. Therefore, in reservoirs there are sometimes freezes- mass death of inhabitants due to lack of oxygen, which occurs for various reasons.
Salt composition environment is also very important for aquatic organisms. Marine species cannot live in fresh waters, and freshwater - in the seas due to disruption of the cells.
Ground-air environment of life. This environment has a different set of features. It is generally more complex and diverse than water. It has a lot of oxygen, a lot of light, sharper temperature changes in time and space, much weaker pressure drops, and often there is a moisture deficit. Although many species can fly, and small insects, spiders, microorganisms, seeds and plant spores are carried by air currents, organisms feed and reproduce on the surface of the earth or plants. In such a low-density medium as air, organisms need support. Therefore, mechanical tissues are developed in terrestrial plants, and in terrestrial animals, the internal or external skeleton is more pronounced than in aquatic ones. The low air density makes it easier to move around in it.
M. S. Gilyarov (1912-1985), a prominent zoologist, ecologist, academician, founder of extensive research into the world of soil animals, passive flight was mastered by about two-thirds of the inhabitants of the land. Most of them are insects and birds.
Air is a poor conductor of heat. This facilitates the possibility of conserving the heat generated inside the organisms and maintaining a constant temperature in warm-blooded animals. The very development of warm-bloodedness became possible in the terrestrial environment. The ancestors of modern aquatic mammals - whales, dolphins, walruses, seals - once lived on land.
Land dwellers have very diverse adaptations associated with providing themselves with water, especially in arid conditions. In plants, this is a powerful root system, a waterproof layer on the surface of leaves and stems, and the ability to regulate the evaporation of water through stomata. In animals, these are also various features of the structure of the body and integument, but, in addition, the appropriate behavior also contributes to maintaining the water balance. They may, for example, migrate to watering places or actively avoid particularly dry conditions. Some animals can live their entire lives on dry food, such as jerboas or the well-known clothes moth. In this case, the water needed by the body arises due to the oxidation of the constituent parts of food.
In the life of terrestrial organisms, many other environmental factors also play an important role, for example, the composition of the air, winds, and the topography of the earth's surface. Weather and climate are of particular importance. The inhabitants of the ground-air environment must be adapted to the climate of the part of the Earth where they live, and endure the variability of weather conditions.
Soil as a living environment. The soil is a thin layer of the land surface, processed by the activities of living beings. Solid particles are permeated in the soil with pores and cavities filled partly with water and partly with air, so small aquatic organisms can also inhabit the soil. The volume of small cavities in the soil is a very important characteristic of it. In loose soils, it can be up to 70%, and in dense soils - about 20%. In these pores and cavities, or on the surface of solid particles, a huge variety of microscopic creatures live: bacteria, fungi, protozoa, roundworms, arthropods. Larger animals make their own passages in the soil. The entire soil is permeated with plant roots. Soil depth is determined by the depth of root penetration and the activity of burrowing animals. It is no more than 1.5-2 m.
The air in soil cavities is always saturated with water vapor, and its composition is enriched with carbon dioxide and depleted with oxygen. In this way, the conditions of life in the soil resemble an aquatic environment. On the other hand, the ratio of water and air in soils is constantly changing depending on weather conditions. Temperature fluctuations are very sharp near the surface, but quickly smooth out with depth.
The main feature of the soil environment is a constant supply organic matter mainly due to dying plant roots and falling leaves. It is a valuable source of energy for bacteria, fungi and many animals, so the soil is the busiest environment. Her hidden world is very rich and diverse.
By the appearance of different species of animals and plants, one can understand not only in what environment they live, but also what kind of life they lead in it.
If we have a quadrupedal animal with highly developed thigh muscles on the hind limbs and much weaker on the forelimbs, which are also shortened, with a relatively short neck and a long tail, then we can say with confidence that this is a ground jumper capable of to fast and maneuverable movements, an inhabitant of open spaces. This is how the famous Australian kangaroos, and desert Asian jerboas, and African jumpers, and many other jumping mammals look like - representatives of various orders living on different continents. They live in the steppes, prairies, savannas - where rapid movement on the ground is the main means of escape from predators. The long tail serves as a balancer during fast turns, otherwise the animals would lose their balance.
The hips are strongly developed on the hind limbs and in jumping insects - locusts, grasshoppers, fleas, psyllid beetles.
A compact body with a short tail and short limbs, of which the front ones are very powerful and look like a shovel or rake, blind eyes, a short neck and short, as if trimmed, fur tell us that we have an underground animal digging holes and galleries . This may be a forest mole, and a steppe mole rat, and an Australian marsupial mole, and many other mammals leading a similar lifestyle.
Burrowing insects - bears also have a compact, stocky body and powerful forelimbs, similar to a reduced bulldozer bucket. In appearance, they resemble a small mole.
All flying species have developed wide planes - wings in birds, bats, insects or straightening folds of skin on the sides of the body, like in gliding flying squirrels or lizards.
Organisms settling by passive flight, with air currents, are characterized by small sizes and very diverse shapes. However, they all have one thing in common - strong development surface area compared to body weight. This is achieved in different ways: due to long hairs, bristles, various outgrowths of the body, its lengthening or flattening, and lightening the specific gravity. This is how small insects and flying fruits of plants look.
The external similarity that occurs in representatives of different unrelated groups and species as a result of a similar lifestyle is called convergence.
It affects mainly those organs that directly interact with the external environment, and is much less pronounced in the structure of internal systems - the digestive, excretory, and nervous systems.
The shape of a plant determines the characteristics of its relationship with the external environment, for example, the way it endures the cold season. Trees and tall shrubs have the tallest branches.
The form of a creeper - with a weak trunk wrapping around other plants, can be in both woody and herbaceous species. These include grapes, hops, meadow dodder, tropical creepers. Wrapping around the trunks and stems of upright species, liana-like plants carry their leaves and flowers to the light.
In similar climatic conditions on different continents, a similar external appearance of vegetation arises, which consists of various, often completely unrelated species.
The external form, which reflects the way of interaction with the environment, is called the life form of the species. Different types may have a similar life form if they lead a close lifestyle.
The life form is developed during the secular evolution of species. Those species that develop with metamorphosis naturally change their life form during the life cycle. Compare, for example, a caterpillar and an adult butterfly, or a frog and its tadpole. Some plants can take on different life forms depending on growing conditions. For example, linden or bird cherry can be both an upright tree and a bush.
Communities of plants and animals are more stable and complete if they include representatives of different life forms. This means that such a community uses the resources of the environment more fully and has more diverse internal connections.
The composition of the life forms of organisms in communities serves as an indicator of the characteristics of their environment and the changes taking place in it.
Aircraft engineers carefully study the different life forms of flying insects. Models of machines with flapping flight were created, according to the principle of movement in the air of Diptera and Hymenoptera. IN modern technology walking machines have been designed, as well as robots with lever and hydraulic movement, like animals of different life forms. Such machines are able to move on steep slopes and off-road.
Life on Earth developed under conditions of a regular change of day and night and alternation of seasons due to the rotation of the planet around its axis and around the Sun. The rhythm of the external environment creates periodicity, that is, the repetition of conditions in the life of most species. Both critical, difficult to survive periods, and favorable ones are regularly repeated.
Adaptation to periodic changes in the external environment is expressed in living beings not only by a direct reaction to changing factors, but also in hereditarily fixed internal rhythms.
daily rhythms. Daily rhythms adapt organisms to the change of day and night. In plants, intensive growth, blooming of flowers is timed to a certain time of day. Animals during the day greatly change activity. On this basis, diurnal and nocturnal species are distinguished.
The daily rhythm of organisms is not only a reflection of changes in external conditions. If you place a person, or animals, or plants in a constant, stable environment without a change of day and night, then the rhythm of life processes is preserved, close to the daily one. The body, as it were, lives according to its internal clock, counting the time.
The daily rhythm can capture many processes in the body. In humans, about 100 physiological characteristics are subject to the daily cycle: heart rate, breathing rhythm, hormone secretion, secretion of digestive glands, blood pressure, body temperature, and many others. Therefore, when a person is awake instead of sleeping, the body is still tuned to the night state and sleepless nights are bad for health.
However, diurnal rhythms do not appear in all species, but only in those in whose life the change of day and night plays an important ecological role. The inhabitants of caves or deep waters, where there is no such change, live according to other rhythms. And among the terrestrial inhabitants, the daily periodicity is not detected in everyone.
In experiments under strictly constant conditions, Drosophila fruit flies maintain a daily rhythm for tens of generations. This periodicity is inherited in them, as in many other species. So deep are the adaptive reactions associated with the daily cycle of the external environment.
Violations of the circadian rhythm of the body during night work, space flights, scuba diving, etc., represent a serious medical problem.
annual rhythms. Annual rhythms adapt organisms to seasonal changes in conditions. In the life of species, periods of growth, reproduction, molts, migrations, deep dormancy naturally alternate and repeat in such a way that organisms meet the critical season in the most stable state. The most vulnerable process - reproduction and rearing of young animals - falls on the most favorable season. This periodicity of changes in the physiological state during the year is largely innate, that is, it manifests itself as an internal annual rhythm. If, for example, Australian ostriches or the wild dingo dog are placed in a zoo in the Northern Hemisphere, their breeding season will begin in the fall, when it is spring in Australia. The restructuring of internal annual rhythms occurs with great difficulty, through a number of generations.
Preparation for reproduction or overwintering is a long process that begins in organisms long before the onset of critical periods.
Sharp short-term weather changes (summer frosts, winter thaws) usually do not disturb the annual rhythms of plants and animals. The main environmental factor to which organisms respond in their annual cycles is not random weather changes, but photoperiod- changes in the ratio of day and night.
The length of the daylight hours naturally changes throughout the year, and it is these changes that serve as an accurate signal of the approach of spring, summer, autumn or winter.
The ability of organisms to respond to changes in day length is called photoperiodism.
If the day is shortened, the species begin to prepare for winter, if it lengthens, to active growth and reproduction. In this case, for the life of organisms, it is not the factor of change in the length of day and night that is important, but its alarm value, indicating the forthcoming profound changes in nature.
As you know, the length of the day strongly depends on the geographical latitude. In the northern hemisphere in the south, the summer day is much shorter than in the north. Therefore, the southern and northern species react differently to the same amount of day change: the southern ones start breeding at a shorter day than the northern ones.
ENVIRONMENTAL FACTORS
Ivanova T.V., Kalinova G.S., Myagkova A.N. "General Biology". Moscow, "Enlightenment", 2000
- Topic 18. "Habitat. Ecological factors." Chapter 1; pp. 10-58
- Topic 19. "Populations. Types of relationships between organisms." chapter 2 §8-14; pp. 60-99; chapter 5 § 30-33
- Topic 20. "Ecosystems." chapter 2 §15-22; pp. 106-137
- Topic 21. "Biosphere. Cycles of substances." chapter 6 §34-42; pp. 217-290
A person has a conscious, purposeful impact on the environment (of course, not always reasonable). F. Engels wrote: “The animal only uses external nature and makes changes in it simply by virtue of its presence; man, by the changes he makes, forces it to serve its purposes, dominates it.
· Anthropogenic factor in terms of strength, intensity and global impact currently has no equal in nature. People have expanded the range of available energy sources up to the use of nuclear and thermonuclear reactions.
· Man creates artificial habitats, can stay in outer space and under water for a long time, influencing nature.
Today, the human environment is practically artificial, man-made ecosystems or natural ecosystems, modified to one degree or another by human activity. There are no absolutely unchanged ecosystems on the planet!
All ecosystems, depending on the degree of anthropogenic impact on them, are divided into natural cenoses, agrocenoses and urban cenoses.
natural cenoses characterized by a wide variety of wild plant and animal species. They correspond to different landscape zones: tundra, forest-tundra, taiga, mixed and broad-leaved forests, steppes, deserts, subtropics and tropics.
Environmental characteristic:
A wide variety of species composition of plants and animals.
· Ecological homeostasis is maintained by self-regulation.
· Natural circulation of substances and use of solar energy.
People get into natural cenoses when studying natural conditions, resources, engineering and geological conditions in the area being developed. At this stage of development of nature, people are at risk of infection with natural focal diseases, suffer from the attack of midges, ticks and adverse weather conditions, which leads to respiratory diseases, adaptive syndromes from the cardiovascular system, neurosis, and an increase in injuries.
Examples: the change of forest landscape to meadow-field landscape in central Russia led to a change in the composition of mouse-like rodents and the emergence of new natural foci of tularemia. The development of the taiga regions of Siberia and the Far East was accompanied by the appearance of human cases of taiga encephalitis.
Agrocenoses. Under the influence of agricultural production, artificial ecological systems arise - agrocenoses (fields, hayfields, pastures, gardens, parks, forest plantations).
Ecological characteristic :
· The number of species of animals and plants is limited, but their numbers are sometimes enormous. Usually these are just a few crops, weeds and pests of agricultural plants, a small number of domestic animal species. They are under the control of artificial selection.
· Unlike natural biogeocenoses, for normal functioning, artificial ecological systems need a person to maintain their homeostasis, i.e. managed them (destruction of harmful and protection of beneficial species).
· The cycle of substances is distorted, because a person withdraws certain substances, makes fertilizers.
· To save agrocenoses, additional energy costs are needed: equipment and physical strength.
About 60% of agricultural land is used extensively with the involvement of the muscular strength of humans and animals. Only 40% of cultivated lands are intensively cultivated agrocenoses, in which the yield of agricultural plants reaches a biologically possible maximum.
Biomedical characteristic:
In agrocenoses, the loss of agricultural land is progressively increasing due to the washing out of the fertile humus layer, wind erosion of soils, and an increase in the length of ravines and shifting sands. The soil is saturated with pesticides and mineral fertilizers, water bodies are polluted with domestic sewage.
Urban cenoses- anthropoecosystems of cities and towns. The first cities appeared in the 3rd millennium BC. At the beginning of the 19th century, 3% of the population lived in them, in 1900 - 13%, in 1995 - 71% in the USA, 91% in Great Britain, in Russia - 74%, and at the beginning of the 21st century in Russia this number will reach 80-90%.
The construction of cities is a progressive phenomenon. Industrial enterprises are concentrated in them, the problems of employment, food supply, medical care are more easily solved, there are various educational, scientific and cultural institutions. In cities there are all conditions for production activities and the organization of people's lives.
But, on the other hand, cities are characterized by the most pronounced changes. natural environment, many of which are negative.
Environmental characteristic:
· Poor species composition of fauna and flora.
Large crowds of people.
· Predominance of synanthropic animal species.
· Non-closed circulation of substances, which involves metals, plastics, not destroyed by natural decomposers.
· Artificial maintenance of homeostasis, which is aimed at preserving the human population.
Use of additional energy sources.
Biomedical characteristic:
During the construction of cities, there is a complete or partial destruction of ecological systems at the site of the construction of the city, the geological environment changes: the natural microrelief disappears, the state and properties of rocks change, the level of groundwater changes, an irreversible intake of water and oxygen is observed, technogenic deposits are created.
The climate is changing: in cities, the intensity of solar radiation is decreasing, mean annual temperature by 1-2°, a temperature amplitude appears - in the city center the temperature is 2-8° higher than in the periphery, the amount of fogs and precipitation increases, the wind regime changes significantly.
The air environment changes: the chemical composition of atmospheric air, its optical properties, thermal characteristics. Air pollution is associated with emissions of gaseous substances and particulate matter. Dust and smoky air in cities reduce the amount of ultraviolet rays reaching the earth's surface by 30% in winter. The duration of sunlight is reduced by 5-15%. Climate change combined with air pollution lead to the formation of smog over cities, which includes carbon monoxide, nitrogen oxide, sulfur oxides and many other compounds dangerous to people. People affected by smog develop respiratory diseases. The number of microorganisms in the air is increasing (200 times compared to rural areas), and the incidence of infectious diseases among people is increasing.
In cities, surface waters change runoff, chemical composition and temperature regime. The groundwater level rises or falls. Water consumption is 150-200 l/day per city dweller. Water may contain organic, inorganic, synthetic and radioactive substances.
There is a mineralization of soils, tamping and removal of the fertile layer, pollution with liquid and solid waste, salts of heavy metals. The natural process of destruction of various substances is disturbed.
The vegetation cover of cities is depleted, large single-species groupings of plants appear, in the fruits and leaves of which toxic substances accumulate.
Overcrowding, noise, physical inactivity and a busy pace of life create conditions for the development of diseases of the nervous system, circulatory organs, and upper respiratory tract. Changes in atmospheric pressure lead to headaches, weakness and rapid fatigue of people. Metabolism is disturbed, obesity develops. The level of these diseases is 1.5-2 times higher than in rural areas. Traffic injuries are also on the rise in cities.
