CHAPTER 5. GROUP OF ABIOTIC FACTORS

General information

The influence of climatic factors (temperature, air humidity, precipitation, wind, etc.) on the body is always cumulative. However, studying the impact of each individual climatic factor allows us to better understand its role in the life of certain species or crops and serves as a necessary prerequisite for studying the impact of the entire complex of climatic factors. When assessing climatic factors, one cannot attach exclusive importance to just one of them. Any of the above-mentioned climate components in specific conditions can be represented in different ways: not only quantitatively, but also qualitatively. For example, the amount of annual precipitation for a certain area may be quite high, but its distribution throughout the year is unfavorable. Therefore, in certain periods of the year (during growing seasons), moisture can act as a minimum factor and inhibit the growth and development of plants.

Light

In crops that are especially light-demanding, such as rice, development is delayed when there is insufficient light. The formation of highly productive forest stands of many forest-forming species and fruit plantations is also largely determined by the intensity of solar energy. The sugar content of beets directly depends on the intensity of the sun's radiant energy during the growing season. It is known that flax (Linum usitatissimum) and hemp sativa (Cannabis sativa) under short daylight conditions, a significant amount of oil is synthesized in the tissues, and under long daylight conditions, the formation of bast fibers accelerates. The response of plants to the length of day and night is manifested in acceleration or delay of development. Consequently, the effect of light on a plant is selective and ambiguous. The importance of illumination as an environmental factor for the body is determined by the duration, intensity and wavelength of the light flux.

At the boundary of the earth's atmosphere with space, radiation ranges from 1.98 to 2 cal/cm 2 per minute; This value is called the solar constant. Under different weather conditions, 42...70% of the solar constant reaches the Earth's surface. Solar radiation, passing through the atmosphere, undergoes a number of changes not only in quantity, but also in composition. Short-wave radiation is absorbed by the ozone shield, located at an altitude of about 25 km, and by oxygen in the air. Infrared rays are absorbed in the atmosphere by water vapor and carbon dioxide. As a result, the air heats up. The rest of the radiant energy reaches the Earth's surface in the form of direct or diffuse radiation (Fig. 10). The combination of direct and diffuse solar radiation constitutes the total radiation. On clear days, diffuse radiation makes up 1/3 to 1/8 of the total radiation, while on cloudy days, diffuse radiation makes up 100%. At high latitudes, diffuse radiation predominates, while under the tropics, direct radiation predominates. Scattered radiation contains up to 60% of yellow-red rays at noon, direct radiation - 30...40%.

The amount of radiation reaching the Earth's surface is determined by the geographic latitude of the area, the length of the day, the transparency of the atmosphere and the angle of incidence of the sun's rays. On clear sunny days, the radiant energy reaching the Earth's surface consists of 45% visible light (380...720 nm) and 45% infrared radiation, only 10% is ultraviolet radiation. The dustiness of the atmosphere has a significant impact on the radiation regime. In some cities, due to its pollution, the illumination may be 15% or less of the illumination outside the city.

Illumination on the Earth's surface varies widely. It all depends on the height of the sun above the horizon, i.e. the angle of incidence of the sun's rays, the length of the day and weather conditions, and the transparency of the atmosphere. Light intensity also fluctuates depending on the season and time of day. The quality of light is also unequal in certain regions of the Earth, for example, the ratio of long-wave (red) and short-wave (blue and ultraviolet) rays. As is known, short-wave rays are absorbed and scattered by the atmosphere more than long-wave rays. Therefore, in mountainous areas there is always more short-wave solar radiation.

Rice. 10. The intensity of solar radiation falling on the Earth’s surface, according to W. Larcher

Since photosynthetically active radiation (PAR) is represented by a portion of the spectrum between wavelengths of 380 and 710 nm and is maximum in the region of orange-red rays (600...680 nm), it is natural that the coefficient of use of scattered radiation by plants is higher. Due to the increase in day length, light, even in high northern latitudes, does not limit the life activity of plants. L. Ivanov calculated that even on Spitsbergen there is enough solar radiation (20,000 kJ per 1 ha) to obtain some yield of dry plant mass.

Different types of plants and plant groups have different needs for light, in other words, for normal vegetation they also need different light supply (£,), i.e., the percentage of total PAR. This allows us to distinguish three ecological groups of plants in relation to the need for light:

· light plants, or heliophytes (from the Greek helios - sun + phyton), - L opt= 100%, £ min = 70%, these are plants of open spaces, for example feather grass (Stipa), most cultivated plants (sugar beets, potatoes, etc.);

· shade-tolerant plants, or hemiscyophytes, can grow at L = 100%, but also tolerate large shade; cocksfoot (Dactylis glomerata), for example, it is capable of vegetating in a range L from 100 to 2.5%;

· shade plants, or sciophytes (from the Greek skia - shadow), do not tolerate full light, their L max is always less than 100%, this is common oxalis (Oxalis acetosella), European seven-year-old (Trientalis europaea) and etc.; Due to the special structure of the leaves, sciophytes at low light intensity are able to assimilate carbon dioxide no less effectively than heliophyte leaves at L= 100 %.

Moscow plant grower A. Doyarenko found that for most agricultural herbaceous plants the coefficient of light use for photosynthesis is 2...2.5%, but there are exceptions:

· fodder beet - 1.91

· vika - 1.98

· clover - 2.18

· rye - 2.42

· potatoes - 2.48

· wheat - 2.68

· oats - 2.74

flax - 3.61

· lupine - 4.79

Of the plant communities, forest communities most actively transform the composition of sunlight, and a very small part of the initial solar radiation reaches the soil surface. It is known that the leaf surface of a tree stand absorbs about 80% of incident PAR, another 10% is reflected and only 10% penetrates under the forest canopy. Consequently, total radiation and radiation penetrating through the canopy of woody plants differs not only quantitatively, but also qualitatively.

Sciophytes and heliocyophytes, living under the canopy of other plants, are content with only a fraction of full illumination. Thus, if in wood sorrel the maximum intensity of photosynthesis is achieved at 1/10 of full daylight, then in light-loving species it occurs at approximately 1/2 of this illumination. Light plants are less adapted to exist in low light than shady and shade-tolerant plants. The lower limit at which forest green mosses can grow is 1/90 full daylight. In tropical rainforests there are even more sciophylic species that grow at 1/120 of full light. Some mosses are surprising in this regard: Schistostega pinnate (Schistostega pennaia) and others are plants of dark caves, vegetating at 1/2000 full illumination.

Each geographical area is characterized by a certain light regime. The most important elements of the light regime that determine the direction of plant adaptation are the intensity of radiation, the spectral composition of light, and the duration of illumination (length of day and night). The length of a solar day is constant only at the equator. Here day, like night, lasts 12 hours. The duration of a solar day during the summer period increases from the equator towards both poles; At the pole, as is known, the polar day lasts the whole summer, and the polar night lasts in winter. The plant's response to seasonal changes in the length of day and night is called photoperiodism.

Plant growers have long noticed that agricultural plants of different origins respond differently to daylength. Depending on this reaction, some species were identified as long-day plants, others as short-day plants, and others as not noticeably responding to day length. It is well known that in long day conditions a high yield of wheat, rye, and oats is formed (Avena sativa) and a number of fodder cereals; Long-day plants also include potatoes, citrus fruits and a number of other vegetable and fruit crops. Prolonged illumination of these plants causes a faster passage of the development phases of fruits and seeds. On the other hand, short-day plants such as millet (Panicum miliaceum), sorghum (Sorghum segpiit), rice, the speed of development stages slows down with prolonged illumination. Reducing development periods is achieved by shortening the lighting time.

These features must be taken into account when introducing agricultural plants. Low latitude species (southern plants) are often short-day plants. When introduced to high latitudes, i.e., under long-day conditions, they develop slowly, often do not ripen, and sometimes do not even bloom, like hemp, for example. Jerusalem artichoke can also be included in this group. (Helianthus tuberosus). Thus, the length of day and night can determine the boundaries of distribution and possible introduction of certain species: “southern” - to the north, “northern” - to the south. Neutral with respect to day length include tomato, grapes, buckwheat (Fagopyrum esculentum) and etc.

In the course of studying photoperiodism and photochemical reactions, it was found that the growth of long-day plants in the spring-summer period, when long daylight hours are observed in nature, clearly accelerates. However, in the second half of summer, when the sunny day decreases, growth processes clearly slow down. As a result, in cold climates, long-day plants do not always have time to form a complex of integumentary tissues, the periderm, before the onset of frost. Therefore, long-day perennial crops cultivated at high latitudes may lose winter hardiness, which must be kept in mind when selecting a range of plants for cultivation in these areas. In long-day conditions, it is preferable to introduce annual crops that do not require overwintering. The northward movement of some other crops, such as clovers, is hampered not by winter frosts, but by the nature of photoperiodic reactions. It is their character that can explain the paradoxical fact that the frost resistance of clovers and alfalfa is higher in the central zone of the European part of Russia than in the northern part.

Light has a formative effect on plants, which is manifested in the size, shape and structure (macro- and microscopic) of light and shadow leaves (Fig. 11), as well as in growth processes. The dependence of leaf (shoot) structure on light is not always direct; leaves (shoots) developing in the spring are formed in accordance with the lighting not of the current year, but of the past, i.e., when the buds were laid. I. Serebryakov (1962) believed that the light structure of a leaf is already determined in the bud. The leaves retain this structure quite stably even when the light shoots are transferred to shading. Great height, columnar shape of trunks, high arrangement of crowns (cleared of dry branches) characterize light-loving plants.

Rice. 11. Cross sections of lilac leaves (genus Syringa): a- light; b- shadow

One of the reactions of light-loving plants is to inhibit the growth of above-ground shoots, which in some cases leads to strong branching, in others to rosette. The plants of the mentioned group are also distinguished by a number of other structural changes: small leaves, increased thickness of the outer wall of the epidermis and its outgrowths (trichomes and emergents), cuticular layer, etc. (Fig. 12).

Rice. 12. Cross section of a leaf of the light-loving oleander plant (Nerium oleander):
1 - two-layer epidermis with cuticle; 2 - hypodermis; 3 - isopalisade mesophyll; 4 - depressions on the underside of the leaf (crypts) with stomata and hairs

One example of plant adaptation to light is the orientation of the leaf blade in relation to the sun's rays. There are three orientation methods:

· the leaf blade is oriented horizontally, i.e. perpendicular to the sun's rays; in this case, the rays are captured as much as possible when the sun is at its zenith;

· the leaf blade is oriented parallel to the sun's rays, that is, it is located more or less vertically, as a result the plant better absorbs the sun's rays in the morning and early evening;

· leaf blades are distributed diffusely along the shoot, like in corn - sometimes vertically, sometimes horizontally, so solar radiation is captured quite fully throughout the daylight hours.

Available scientific data suggest that plants at high latitudes, where low solstice prevails, more often have vertical leaf orientation. When organizing mixed crops, such as forage grasses, it is necessary to take into account the structure of the shoots of the crop components. A successful combination of forage grasses with different leaf orientations will provide a greater yield of phytomass.

As already noted, depending on the lack or excess of light, many plants are able to place leaves in planes perpendicular and parallel to the direction of the sun’s rays, forming a so-called leaf mosaic. A leaf mosaic is formed as a result of the rational placement of not only leaf blades of unequal size, but also petioles. A typical leaf mosaic can be observed in phytocenoses with the participation of Norway maple and small-leaved linden (Tilia cordata), smooth elm (Ulmus laevis), mountain elm (Ulmus glabra) and other tree species. The leaf mosaic is clearly visible in many plants with horizontal branches, for example in common ivy (Hedera helix) and many herbaceous plants (Fig. 13).

Rice. 13. Leaf mosaic near ivy (Hedera helix)

Compass plants clearly avoid strong light. Their leaf blade is not perpendicular to the sun's rays, like rosette plants, but parallel, like eucalyptus or wild lettuce (Lactuca serrtola), which protects the leaves from overheating in conditions of excess solar radiation. This ensures favorable photosynthesis and transpiration.

There are a number of other adaptive adaptations, both structural and physiological. Sometimes such adaptations are clearly seasonal in nature, which is well illustrated, for example, by the common duckweed (Aegopodium podagrata). In a typical habitat (oak forests), two “generations” of leaves are formed on the plant during the growing season. In the spring, when the tree buds have not yet blossomed and the forest canopy lets in a lot of light, a leaf rosette is formed, its leaves are clearly luminous in structure (micro- and macroscopic).

Later, when a dense forest canopy develops and only 3...4% of radiant energy reaches the soil surface, a second “generation” of leaves appears, clearly shady. It is often possible to observe both light and shadow leaves on one individual plant. Leaves of the lower tiers of the black mulberry crown (Morus nigra) large, lobed, while the upper tiers of the crown bear light leaves - smaller, devoid of blades. In forest-forming species, the periphery of the crown is formed in a similar way: in the upper tiers there are light leaves, inside the crown there are shadow leaves.

Temperature

Life activity of any species occurs in certain temperature ranges. At the same time, zones of optimum, minimum and maximum are traced. In the zone of minimum or maximum, the body’s activity attenuates. In the first case, low temperatures (cold), and in the second, high temperatures (heat) lead to disruption of its life processes. Beyond extreme temperatures lies the lethal zone, in which the irreversible process of plant death occurs. Therefore, temperatures determine the boundaries of life.

Due to their sedentary lifestyle, higher plants have developed greater tolerance to daily and seasonal (annual) temperature fluctuations. Many forest-forming species of our taiga - Siberian pine, Daurian larch (Larix dahurica) and others - can withstand temperature drops down to - 50 °C and below and summer heat up to 25 °C and above. The annual amplitude reaches 75 °C, and sometimes 85...90 °C. Plant species that can withstand large temperature changes are called eurythermic (from the Greek eurys + therme - heat) in contrast to stenothermic ones.

Heat differentiation on our planet is the basis of latitudinal zonality and altitudinal zonation of vegetation and soils. Due to the decrease in the height of the solstice and the angle of incidence of the rays from the equator to the poles, the amount of heat changes. Thus, the average annual temperature near the equator is 26.2 °C, near 30 °C. w. it is already equal to 20.3 ° C, and at 60 ° C. w. decreases to - 1 °C.

In addition to the average annual temperature of a given area, the highest and lowest temperatures (absolute maximum and absolute minimum) observed in a given climatic zone, as well as the average temperature of the warmest and coldest months, are important in the life of organisms. Thus, the duration of the growing season in the tundra (i.e. above 70° N) is only one and a half to two and a half months at an average temperature of 10...12 °C.

Taiga, otherwise the zone of coniferous forests, has a growing season of three to five months, an average temperature of 14.. L6 °C. In the southern part of the zone, where coniferous-deciduous forests predominate, the growing season lasts four to five months, the average temperature is 15... 16 °C. In the zone of broad-leaved forests (40...50° N), the growing season is five to six months, the average temperature is 16...18 °C. A sharp contrast to the described zones is the zone of tropical rainforests (0...15° N and S). The growing season here is year-round with an average temperature of 25...28 °C and is often not differentiated by seasons. An extremely important feature of tropical regions is that the difference between the average temperatures of the warmest and coldest months is less contrasting than the daily fluctuations.

Plant growth is directly related to temperature. The dependence of individual species on temperature varies widely. There is a clear distinction between thermophilic (from the Greek therme + philia - love) plants and their antipodes - cold-tolerant, or cryophilic (from the Greek kryos - cold). A. Decandolle (1885) distinguished groups of hekistothermic, microthermic, mesothermic and megathermic plants (from the Greek gekisto - cold, mikros - small, mesos - medium, megas - large).

The listed groups of plants in relation to temperature are complex; when identifying them, the relationship of plants to moisture is also taken into account. An addition to this classification can be considered the identification of cryophyte and psychrophyte plants (from the Greek psychros - cold + phyton) - hekistotherms and partially microtherms, requiring different moisture regimes. Cryophytes grow in cold, dry conditions, while psychrophytes are cold-tolerant plants in moist soils.

The influence of temperatures on the distribution of individual plant species and their groups is no less clear. The connection between the geographic distribution of individual species and isotherms has long been established. As you know, grapes ripen within an isotherm with an average temperature for six months (April - September) of 15 ° C. The distribution of English oak to the north is limited by the annual isotherm of 3 °C; The northern limit of date palm fruiting coincides with the annual isotherm of 18...19 °C.

In a number of cases, the distribution of plants is determined not only by temperatures. Thus, the 10 °C isotherm passes from west to east through Ireland, Germany (Karlsruhe), Austria (Vienna), Ukraine (Odessa). The named areas have a fairly different species composition of natural vegetation cover and provide the opportunity for the introduction and cultivation of a diverse set of crops. In Ireland, crops often fail to ripen. In Germany and Ireland, many pumpkins (watermelons - Citrullus vulgaris, melons), although camellias grow in open ground (Camella) and palm trees. In Karlsruhe, ivy and holly grow in open ground ( Ilex), sometimes the grapes also ripen. In the Odessa region, melons and watermelons are cultivated, but ivy and camellias cannot withstand low winter temperatures. Many such examples can be given.

Thus, average temperatures in isolation from other environmental factors cannot serve as a reliable indicator (indicator) of the possibility of introduction and cultivation of the crop of interest to us. The bottom line is that different types of plants are characterized by unequal lengths of the growing season. Therefore, with regard to temperature, it is necessary to take into account both the duration of the period of favorable temperatures for the normal development of plants, and the time of onset and duration of minimum temperatures (the same for maximum temperatures).

In the environmental and plant growing literature, the sum of active temperatures is widely used to estimate the thermal resources of the growing season. It serves as a good indicator for assessing the heat needs of plants and makes it possible to determine the area for cultivating a particular crop. The sum of active temperatures consists of the sum of positive average daily temperatures for the period when it is above 10 °C. In areas where the sum of active temperatures is 1000...1400 °C, early varieties of potatoes and root crops can be cultivated; where this amount reaches 1400...2200 °C, - cereals, potatoes, flax, etc.; the sum of active temperatures of 2200...3500 °C corresponds to the zone of intensive fruit growing; when the sum of these temperatures exceeds 4000 °C, the cultivation of subtropical perennials is successful.

Organisms whose vital activity and body temperature depend on heat coming from the environment are called poikilothermic (from the Greek poikilos - different). These include all plants, microorganisms, invertebrate animals and some groups of chordates. The body temperature of poikilothermic organisms depends on the external environment. That is why the ecological role of heat in the life of all systematic groups of plants and the named groups of animals is of paramount importance. Highly organized animals (birds and mammals) belong to the group of homeotherms (from the Greek homoios - identical), in which the body temperature is constant, since it is maintained by its own heat.

It is known that the protoplast of cells of living organisms is able to function normally in the temperature range 0...50 °C. Only organisms that have special adaptations can withstand these extreme temperatures for long periods of time. Physiologists have established optimal and critical temperatures for breathing and other functions. It turns out that the lower limit of the breathing temperature of wintering organs (buds, needles) is 20... - 25 °C. As the temperature rises, the breathing rate increases. Temperatures above 50 °C destroy the protein-lipid complex of the surface layer of the cytoplasm, which leads to the loss of osmotic properties by cells.

In some regions of Russia, mass death of plants from too low temperatures is periodically observed. The catastrophic effect of the latter has the greatest impact in winters with little snow, mainly on winter grains. Sudden cold snaps in the spring, when plants begin to grow (late spring frosts), are also destructive. Often, not only introduced evergreen trees, such as citrus fruits, but also deciduous plants die from the cold. N. Maksimov, studying the mechanism of action of low temperatures, came to the conclusion that the cause of plant death is explained by dehydration of the cytoplasm. Crystallization of water occurs in the intercellular spaces of the tissue. Ice crystals draw water from cells and mechanically damage cell organelles. The critical moment comes precisely with the appearance of ice crystals inside the cells.

Natural groups of frost-resistant plants have been identified. These include coniferous evergreen trees and shrubs, as well as lingonberries (Vaccinium vitis-idea), heather, etc. Among herbaceous perennials, many frost-resistant plants have also been identified that can survive harsh winters. During winter dormancy, plants can withstand very low temperatures. So, black currant shoots (Ribes nigrum) with a slow decrease in temperature to - 253 ° C (temperature close to absolute zero) they can remain viable.

Most plant species have individual responses to temperature. Thus, in spring, germination of rye grains begins at 1...2 °C, meadow clover seeds (Trifolium pratense)- at 1 °C, yellow lupine (Lupinus luteus)- at 4...5, rice - at 10...12 °C. The optimal temperatures for ripening the seeds of these crops are 25, 30, 28, 30...32 °C, respectively.

For normal growth and development of plants, an appropriate ambient temperature is required for above-ground and underground organs. For example, flax develops normally at a temperature of the root approximately two times lower (10 °C) than that of the above-ground organs (22 °C). During ontogenesis, the need of plants for heat changes noticeably. The temperature of the plant body organs varies significantly depending on the location (soil, air) and orientation in relation to the sun's rays (Fig. 14). It has been experimentally established that the germination of rapeseed seeds (Brassica napus), rapeseed (V. campestrts), wheat, oats, barley, clover, alfalfa and other plants is observed at a temperature of 0...2 °C, while higher temperatures (3...5 °C) are required for the emergence of seedlings.

Rice. 14. Temperature (°C) of different plant organs: A - new versions (Novosiversia glacialis), according to B. Tikhomirov; B - Siberian scilla (Scilla sibiriati, according to T. Goryshina, A- bedding, b- the soil

Many types of continental plants are favorably affected by daily thermoperiodism, when the amplitude of night and day temperatures is 5... 15 ° C. Its essence lies in the fact that many plants develop more successfully at lower night temperatures. For example, tomatoes develop better if the daytime air temperature reaches 26° C, and the night temperature 17...18° C. Experimental data also indicate that plants in temperate latitudes also require low autumn temperatures - seasonal thermoperiodism - for normal ontogenetic development.

The temperature factor affects plants at all stages of their growth and development. Moreover, at different periods, each type of plant needs certain temperature conditions. For most annual plants, such as barley, oats and others, a general pattern can be traced: in the early stages of development, the temperature should be lower than in later stages.

Megathermal plants of tropical origin, such as sugarcane (Saccharum officinarum), need high temperatures throughout their lives. Plants in hot and dry regions - euxerophytes, as well as many succulents, such as Cactus and Crassulaceae - are characterized by the greatest tolerance to ultra-high temperatures. (Crassulaceae). This is also typical for plants in soils saline, especially with sulfides and chlorides. These species, as shown by X. Ludengaard (1925, 1937), remain viable even at 70 °C. Severely dehydrated seeds and fruits tolerate high temperatures well. It is on this property that the well-known method of combating the pathogen of loose smut of wheat is based. (Ustilago trtttci). When the affected seeds are heat treated, the fungus, being stenothermic, dies, while the grain embryo remains viable.

It is more difficult to resolve the issue of the influence of temperature on changes in the structure of the plant itself, its morphology. Observations in nature and experimental evidence provide various explanations. In fact, such an adaptation as the strong pubescence of the bud scales and leaves seems to be complex; it serves as protection not only from bright light, but also from high temperatures, as well as from excessive evaporation of moisture. The bright shine of glossy leaves, the parallel arrangement of the leaf blade to the sun's rays, felt pubescence - all this undoubtedly prevents overheating of the leaf, as well as excessive transpiration.

The founder of plant ecology, E. Warming (1895), clearly demonstrated the influence of temperature on the formation of squat and rosette forms of plants in the Arctic and in the highlands of the alpine and subnival zones, i.e., at the very border of eternal snow. We are talking not only about herbaceous stemless, rosette plants like elecampane (Inula rhizocephala), but also about woody life forms - dwarf birch, Turkestan juniper (Juniperus turcestanica), dwarf cedar, etc. Creeping and cushion forms of plants, for example arctic minuartia (Minuartia arctica), most adapted to living conditions at the very surface of the soil under the cover of snow cover. When there is no snow, the highest temperature remains in the ground layer of air at a height of up to 15...20 cm and the wind force is minimal. In addition, a special microclimate is created inside the “cushion” formed by the plant, and temperature fluctuations here are much less pronounced than outside it. The temperature factor can affect the development of squat forms both directly and indirectly - due to disruption of water supply and mineral nutrition.

The greatest role is played by the direct influence of temperature in the process of plant geophilization. Geophilization refers to the immersion of the lower (basal) part of the plant in the soil (first the hypocotyl, then the epicotyl, the first internode, etc.). This phenomenon is characteristic mainly of angiosperms. It was during their historical development that geophilization played a prominent role in the transformation of life forms from trees to grasses. As the base of the shoots is immersed in the soil, a system of adventitious roots, rhizomes, stolons and other organs of vegetative propagation intensively develops. Geophilization was a necessary prerequisite for the appearance of various underground plant organs, especially organs of vegetative reproduction. This gave angiosperms great advantages in the struggle for existence and dominance on the continents of the Earth.

In the ontogeny of many angiosperms, geophilization of plants is carried out with the help of special retractile (contractile) roots. Interesting experimental studies on geophilization were carried out by P. Lisitsyn. He found that the retraction of the basal part of the plant into the soil is much more widespread than previously thought (Fig. 15). For winter crops, geophilization improves wintering conditions; for spring crops, such as buckwheat, it improves water supply conditions.

Rice. 15. Geophilization (retraction into the soil) of the subcotyledon of meadow clover (Trifolium pratense), according to P. Lisitsin: A - soil surface; b - retraction depth

Water

All vital processes at the levels of cells, tissues, and organisms are unthinkable without sufficient water supply. Plant organs usually contain 50...90% water, and sometimes more. Water is an essential component of a living cell. Dehydration of the body entails a slowdown and then cessation of the life process. Maximum dehydration while maintaining life and reversibility of normal life processes is observed in spores and seeds. Here the water content drops to 10 and 12%, respectively. The cold resistance, as well as the heat resistance of plants, depends on the amount of water they contain. Soil nutrition of plants (the supply and transportation of nitrogenous and other mineral substances), photosynthesis, and enzymatic processes are also associated with water. Metabolic products are dissolved and transported in the plant body also with the help of water.

Water is one of the necessary conditions for the formation of plant mass. It has been established that 99.5% of the water transported from the root system to the leaves maintains turgor and only 0.5% of it is spent on the synthesis of organic matter. To obtain 1 g of dry plant mass, 250...400 g of water or more is required. The ratio of the above values ​​is the transpiration coefficient. This indicator varies significantly among different species and even varieties of plants. There is a pattern: the value of the transpiration coefficient is directly proportional to the dryness of the climate. Therefore, the same variety may have different transpiration coefficients when grown in different ecological and geographical conditions.

The optimum water regime is observed in cases where the evaporation of water into the atmosphere does not exceed its entry into the plant body from the soil. During ontogenesis, a stage comes when the water supply determines all subsequent plant development and harvest. These developmental phases have been well studied in many cultivated plants. The critical stage of development in cereals is the formation of flowers and inflorescences. Under unfavorable water supply conditions, part of the tubercles of the growth cone degenerates. Since this process is irreversible, shortened, weakly branched inflorescences are formed, containing few flowers, and, consequently, caryopses.

Over millions of years of continuous evolution, organisms have adapted to different living conditions. Plants of arid regions, where the climate is extremely dry, have pronounced xeromorphic (from the Greek xeros - dry, morphe - shape) characteristics. They make it possible to reduce moisture loss, which mainly occurs as a result of transpiration through the stomatal apparatus, as well as through water stomata (the phenomenon of guttation - from the Latin gutta - drop). Significant moisture consumption also occurs through the cells of the epidermis (cuticular evaporation). Guttation is well expressed in seedlings of cereals, potatoes, buckwheat, and in many indoor plants, for example, alocasia (Alocasia macrorhiza) etc. Guttation is most common in plants of the humid tropics and subtropics.

Plants in arid conditions have a variety of adaptations to prevent water loss. In many cereals, the leaves are rolled into a tube, so that the stomata are inside. The leaves of xeromorphic plants often have a thick waxy coating or hairs. The transpiration organs (stomatal apparatus) in such plants are immersed in the mesophyll; their leaves are often reduced to scales or transformed into spines and thorns. With a strong reduction of leaves, the function of photosynthesis is taken over by the stem. Many crops, both herbaceous and woody, respond to a lack of soil moisture and groundwater by rapidly expanding their root systems.

The water balance of a plant is determined by the difference between the absorption and consumption of water by the body. The water balance is influenced by a whole series of environmental conditions: air humidity, the amount and distribution of precipitation, the abundance and height of groundwater, the direction and strength of the wind.

Water consumption by plants is largely determined by the relative humidity of the air. In a more humid climate, other things being equal, plants spend less moisture to form dry matter. In the temperate zone, transpiration productivity is about 3 g of dry matter at a consumption of 1 liter of water. With increasing air humidity, seeds, fruits and other plant organs contain less proteins, carbohydrates and mineral elements. In addition, the synthesis of chlorophyll in leaves and stems decreases, but at the same time growth increases and the aging process is inhibited. When the air is highly saturated with water vapor, bread ripens very slowly, and sometimes does not ripen at all. Air humidity has a great influence on the quantity and quality of crops and the operation of agricultural machines. At high air humidity, crop losses during threshing and harvesting increase, and the processes of post-harvest seed ripening slow down, which ultimately reduces their safety.

Depending on their relationship to moisture, plants are divided into two ecological groups: poikihydride and homohydride. The former do not have special mechanisms for regulating the hydration (water content) of their body; in terms of the nature of moisture loss, they practically do not differ from wet cotton fabric. Poikilohydrides include lower plants, mosses, and many ferns. The vast majority of seed plants are homohydrid and have special mechanisms (stomatal apparatus, trichomes on leaves, etc.) to regulate the internal water regime. Poikihydridity among angiosperms is extremely rare and is most likely of secondary origin, i.e., it is a kind of adaptation to the xeric regime. A rare example of a poikihydrid angiosperm is the desert sedge, or silt. (Carex physoides).

Based on their characteristic water regime, homohydrid plants are divided into hydrophytes, helophytes, hygrophytes, mesophytes, xerophytes, and ultraxerophytes.

Hydrophytes (from the Greek hydor - water + phyton) are aquatic plants that freely float or take root at the bottom of a reservoir or are completely submerged in water (sometimes with leaves floating on the surface or inflorescences exposed above the water). Absorption of water and mineral salts is carried out by the entire surface of the plant. In floating hydrophytes, the root system is greatly reduced and sometimes loses its functions (for example, in duckweeds). The mesophyll of underwater leaves is not differentiated, there is no cuticle and stomata." Examples of hydrophytes are Vallisneria (Vallisneria spiralis), Elodea canadensis (Elodea canadensis), floating pondweed (Potamogeton natans), Aldrovanda vesica (Aldrovanda vesiculosa), white water lily (Nymphaea alba), yellow egg capsule (Nuphar luteum) etc. The listed species are characterized by a strong development of air-bearing tissue - aerenchyma, a large number of stomata in floating leaves, poor development of mechanical tissues, and sometimes diversity of leaves.

Helophytes (from the Greek helos - swamp) are aquatic-terrestrial plants growing both in water in shallow waters and along waterlogged banks of rivers and reservoirs; They can also live on abundantly moist soil away from water bodies. They are found only in conditions of constant and abundant water supply. Helophytes include common reed; plantain chastukha (Alisma plantago-aquaucd), arrowhead arrowhead (Saggitaria sagittifolia), umbrella susak (Butomus umbellatus) etc. Helophytes can withstand a lack of oxygen in the soil.

Hygrophytes (from the Greek hygros - wet) are terrestrial plants growing in conditions of high soil and air humidity. They are characterized by tissue saturation with water up to 80% and higher, and the presence of water stomata. There are two ecological groups of hygrophytes:

· shady, growing under the canopy of damp forests in different climatic zones, they are characterized by water stomata - hydathodes, which allow them to absorb water from the soil and transport mineral elements, even if the air is saturated with water vapor; Impatiens common are classified as shady hygrophytes (Impattens noli-tangere), Circe of Paris (Circaea lutetiana), wood sorrel;

· light, growing in open habitats, where the soil and air are constantly moist; these include papyrus (Cyperus papyrus), sundew rotundifolia (Drosera rotundifolia), marsh bedstraw (Galium palustre), rice, marsh marigold (Caltha palustrts).

Hygrophytes are characterized by poor adaptability to the regulation of tissue water content, therefore, picked plants of this group wither very quickly. Thus, hygrophytes from terrestrial homoihydrid plants are most similar to poikihydrid forms. Hydrophytes, helophytes and hygrophytes have a positive water balance.

Mesophytes (from the Greek mesos - average) are plants adapted to life in conditions of average water supply. They exhibit high viability in moderately warm conditions and average mineral nutrition. They can tolerate short-term, not very severe drought. The vast majority of cultivated crops, as well as plants of forests and meadows, belong to this group. At the same time, mesophytes are so diverse in their morphophysiological organization and adaptability to different habitats that it is difficult to give them a general definition. They constitute a diverse range of intermediate plants between hygrophytes and xerophytes. Depending on their distribution in different climatic zones, A. Shennikov (1950) identified the following five groups of mesophytes: evergreen mesophytes of tropical rainforests - trees and shrubs [*], growing all year round without a pronounced seasonal break; they are characterized by large leaves with hydathodes; often such leaves have a point at the end that drains water; leatheriness, drooping and dismembered leaves ensure their safety during rains (philodendron - Philodendron, ficus - Ficus elastica and etc.); the upper wide and dense leaves of the plants of the group are adapted to bright light, they are characterized by a thick cuticle, well-defined columnar parenchyma, a fairly developed conducting system and mechanical tissues;

winter-green woody mesophytes, or tropophytes (from the Greek tropos - turn), are also predominantly species of tropical and subtropical zones, but common not in rain forests, but in savannas; they shed their leaves and go into a dormant state during the dry summer period; have well-defined integumentary complexes - periderm and crust; a typical representative is the baobab;

summer-green woody mesophytes - plants of temperate climates, trees and shrubs that shed their leaves and go dormant in the cold season; these include most deciduous trees in cold and temperate zones; the fall of leaves in winter serves as an adaptation to reduce evaporation in the cold months, when the absorption of water from the soil is difficult; Integumentary complexes (periderm and crust), as well as devices for protecting the kidneys from water loss, are of great importance for this subgroup of mesophytes; nevertheless, in winter the plants lose a significant amount of moisture; evaporation occurs mainly through weakly protected leaf scars and buds;

summer-green herbaceous perennial mesophytes - plants of temperate climates, the above-ground parts of which usually die off in the winter, with the exception of protected renewal buds; very large group; the most typical representatives are perennial meadow grasses (meadow timothy grass - Phleum pratense, meadow clover, etc.) and forest herbs (fragrant woodruff - Asperula odorata, European hooffoot, etc.); the leaves are characterized by differentiated mesophyll, although in forest plants (sciophytes and hemiscyophytes) the palisade tissue is often not expressed; conductive elements are moderately developed; the epidermis is thin, the cuticle is not always present; mechanical tissues are moderately or poorly developed;

ephemerals and ephemeroids (from the Greek ephemeros - one-day) - annual (ephemeras) and bi- or perennial (ephemeroids) plants that, in dry conditions, grow for a short wet period and go into a dormant state during the dry season; for example, plants of deserts and dry steppes: ephemera - spring stonefly, small alyssum (Alissum minutum) and etc.; ephemeroids - viviparous bluegrass, or curly bluegrass (Poa bulbosa subsp. vMparum) different types of tulips (Tulipa), goose onions (Gagea) irises (Iris), ferul (Ferula) and etc.; characterized by a lack of structural adaptation to lack of moisture, but the seeds are able to tolerate severe drying and high temperatures; Bulbous and corm ephemeroids are characterized by contractile (retracting) roots, which ensure the retraction of the renewal bud under the soil during an unfavorable period.

It should be noted that not all scientists agree with the classification of desert ephemerals and ephemeroids to the group of mesophytes and classify them as xerophytes (understanding the latter term very broadly).

Xerophytes (from the Greek xeros) are plants adapted to life in conditions of low water supply. They tolerate soil and atmospheric drought, as they have various adaptations for living in hot climates with very little precipitation. The most important feature of xerophytes is the formation of morphophysiological adaptation to the destructive effects of atmospheric and soil drought. In most cases, xerophytes have adaptations that limit transpiration: leaflessness, small leaves, summer leaf fall, pubescence. Many of them are able to withstand quite severe dehydration for a long time, maintaining viability. Figure 12 showed a sheet with devices to limit evaporation.

Depending on the structural characteristics of organs and tissues and methods of regulating the water regime, the following three types of xerophytes are distinguished.

The first type is euxerophytes (from the Greek eu - real), or sclerophytes (from the Greek skleros - solid), or xerophytes themselves; In appearance these are dryish, tough plants. Even during the period of full water supply, the water content of their tissues is low. Sclerophytes are highly resistant to wilting - they can lose up to 25% of moisture without noticeable harm to themselves. Their cytoplasm remains alive even with such severe dehydration that would be fatal for other plants. Another feature of euxerophytes is the increased osmotic pressure of cell sap, which makes it possible to significantly increase the sucking force of the roots.

Previously, it was believed that the intensity of transpiration of sclerophytes, like other xerophytes, is very low, but the works of N. Maksimov (1926, 1944) showed that under favorable water supply conditions, these plants transpirate more intensively than mesophytes, especially in terms of unit of surface leaf. I. Kultiasov (1982) emphasized that, apparently, the main feature of xerophytes is their high drought resistance, depending on the properties of the cytoplasm, as well as the ability to effectively use moisture after rain. The characteristic “sclerophytic” morphology (strong development of mechanical and integumentary tissues, small leaves, etc.) has a protective value in case of difficulties in water supply.

The root system of euxerophytes is very branched, but shallow (less than 1 m). The group under consideration includes many plants of our steppes, semi-deserts and deserts: wormwood (white earth Artemisia terrae-albae, Lerha - A lerchlana etc.), gray-haired Veronica (Veronica Incana) and etc.

D. Kolpinov (1957) identified a special group of euxerophytes - stipaxerophytes (from the Latin stipa - feather grass). It includes narrow-leaved grasses such as feather grass, fescue (Festuca valesiaca). Plants of the group are distinguished by a powerful root system that uses the moisture of short-term showers. Stypaxerophytes are sensitive to dehydration and tolerate only short-term lack of moisture.

The second type of xerophytes - hemixerophytes (from the Greek hemi - half) have a deep root system that reaches the groundwater level (up to 10 m or more), i.e. they are phreatophytes (see below).

The third type of xerophytes - succulents (from the Latin succulentus - juicy), unlike the xerophytes of the types described above, have well-developed water-storing parenchyma tissue. Depending on its location, leaf and stem succulents are distinguished. Examples of the former are agaves (Agava) aloe (Aloe), sedums (Sedum) etc. In stem succulents, the leaves are usually reduced, and these species store water in the stems (cacti and cactus-like euphorbias).

The root system of succulents is usually superficial. They are distinguished by their ability to store water when it is in excess in the environment, retain it for a long time and use it economically. Transpiration in succulents is extremely low. To reduce it, plants have a number of adaptive features in their structure, including the originality of the forms of the above-ground parts, demonstrating “knowledge” of the laws of geometry. It is known that spherical bodies (especially the ball) have the smallest surface-to-volume ratio. Thickening the leaves and stems, i.e., bringing them closer to a spherical or cylindrical shape, is a way to reduce the transpiration surface while maintaining the required mass. In many succulents, the epidermis is protected by a cuticle, a waxy coating, and pubescence. The stomata are few and usually closed during the day. The latter circumstance creates difficulties for photosynthesis, since the absorption of carbon dioxide by these plants can occur mainly at night: the access of CO 2 and light does not coincide in time. Therefore, succulents have developed a special path of photosynthesis - the so-called “CAM path”, in which the source of CO 2 is partially the products of respiration.

The response of the root system to water supply has been well studied in cultivated plants. Figure 16 shows the depth of penetration of the root system of winter wheat into the soil at different amounts of precipitation.

Rice. 16. Root system of winter wheat (genus Triticum):
1 - with large amounts of precipitation; 2 - at average; 3 - at low

There is a special classification of ecological groups of plants taking into account their use of ground moisture, i.e., according to the sources of moisture absorption from the substrate. It contains phreatophytes (from the Greek phreatos - well) - plants whose root system is constantly connected to the aquifers of soils and parent soil-forming rocks, ombrophytes (from the Greek ombros - rain) - plants that feed on the moisture of precipitation, and trichohydrophytes (from Greek trichos - hair) - plants associated with the capillary border of groundwater, which are in a state of constant mobility. Among phreatophytes, obligate and facultative ones are distinguished; the latter are quite close to trichohydrophytes. Phreatophytes are characterized by the development of deeply penetrating underground organs; at the camel thorn (Alchagi)- up to 15 m, in tree-like forms of black saxaul (Haloxylon aphyllum)- up to 25, in Central Asian tamarix (Tamarix)- 7, in North African tamarix - up to 30, in alfalfa (Medicago sativa)- up to 15 m. Ombrophytes have a shallow, but highly branched system of underground organs, capable of absorbing atmospheric moisture in a large volume of soil. Typical representatives of the group are ephemerals and desert ephemeroids. Trichohydrophytes are characterized by a root system of a universal type, which combines the features of phreatophytes and ombrophytes. Phreatophytes and trichohygrophytes are often classified as hemixerophytes.

Plants are supplied with water from two sources: precipitation and groundwater. Among atmospheric precipitations, rain and snow play the most important role. Hail, dew, fog, frost, and ice occupy a more modest share in the water balance of plants. Atmospheric precipitation for plants is not only a source of water supply. Solid precipitation, forming a snow cover, protects the soil, and consequently, above-ground and underground plant organs from low temperatures. In ecological terms, snow cover significantly affects the habitat of plants and animals - it creates a supply of soil moisture and significantly reduces the evaporation of moisture by plants. The distribution of precipitation by season, its form, amount and intensity of precipitation are important for agricultural plants, as well as for the productivity of pastures and hayfields.

Rains that produce a large amount of precipitation in a short time (more than 1...2 mm/min) are called torrential, or downpours. Rainfall is usually accompanied by strong winds and has a negative impact on agricultural land. The highest amount of precipitation in the Caucasus and Eastern Europe in general (up to 2500 mm per year) and heavy rainfall in particular occurs on the Black Sea coast of the Caucasus - Adjara and Abkhazia. However, heavy downpours (over 5 mm/min) have also been recorded in Ukraine. In general, as you move northward within the continent, the amount of precipitation first increases, reaching a maximum in the temperate zone, and then decreases (does not extend to coastal areas); There is a pattern in changes in other climatic indicators (Fig. 17).

Large differences (Fig. 18) in the amount of precipitation between individual regions of the Earth, along with the temperature regime, create a diversity of environmental conditions on the planet. The wettest areas are located in the upper reaches of the river. Amazon, on the islands of the Malay Archipelago.

Rice. 17. Schematic profile of the European part of Russia from north to south, according to G. Vysotsky

Rice. 18. Annual distribution of precipitation by continent

In the temperate climate zone, in places where frequent thaws are observed, the death of winter crops from the ice crust can be traced. After thaws, melted snow water accumulated in microdepressions in fields freezes and covers winter crops with an ice crust. In this case, mechanical pressure from ice occurs, which has a particularly detrimental effect on the tillering zones, and at the same time there is a lack of oxygen.

The thickness and density of snow cover are important for agriculture, forestry, and water management. Loose snow better protects plants overwintering in the soil from cooling. The density of snow is lowest when the snow cover is formed, then it constantly increases and becomes greatest during the period of snow melting. Therefore, by spring the protective effect of snow cover decreases. Parts of plants that are not covered with snow, especially in cold and windy winters, quickly lose moisture and die. At an air temperature of -21°C under snow on the soil surface it is only -5°C. If snow falls early and covers the soil in a thick enough layer, it does not freeze, and plants grow and develop normally. There are winters when under the snow cover you can find blooming saffrons (genus Crocus), Lyubka bifolia (Platanthera bifolia) and other plants.

In the harsh winter conditions of high northern latitudes, as well as in the mountains, special trellis and dwarf forms of woody plants are produced. Even large-trunked trees of the forest zone - Siberian spruce, Siberian larch and others - are transformed into creeping forms in the Arctic climate.

Atmospheric air

The ecological significance of atmospheric precipitation in the life of plants is also manifested in its participation as a solvent in feeding the lower tiers of woody and herbaceous plants with mineral substances. During rain, falling drops are saturated with volatile and vaporous substances in the air, the latter, together with the drop, fall on plant organs and the soil surface. Along with substances washed out of tree crowns and absorbed by volatile compounds emitted by plants, volatile and vaporous substances that are formed as a result of anthropogenic activities, as well as waste products of soil microflora, are dissolved and mixed in precipitation.

Herbaceous plants are not typical for these ecosystems, and tropical forest epiphytes belong to the subgroups of xeromesophytes or hygromesophytes. The features of their dislocation in tree crowns are determined by microclimatic conditions.

The thick layer of air (atmosphere) covering the Earth protects living organisms from powerful ultraviolet radiation and cosmic radiation, and prevents sudden temperature fluctuations. Ecologically, the gas composition of the atmosphere and the movement of air masses (wind and convection currents) are no less important.

When characterizing the gas composition of air, its constancy is usually emphasized. In almost all regions of the globe, the dry air of the troposphere (lower layer of the atmosphere) contains about 78.1% nitrogen, 21% oxygen, 0.032 % carbon dioxide, traces of hydrogen, small amounts of inert gases. Along with permanent components, the air contains gaseous components, the content of which varies depending on time and place: various industrial gases, ammonia, gaseous emissions of plants, etc.

The direct environmental impact of free nitrogen prevailing in the atmosphere is small; in this form, the specified chemical element lives up to its name, which translated from Greek means “not life-sustaining.” Fixed nitrogen is an essential and essential component of all biological systems. Free atmospheric oxygen not only supports life (respiration), but also has a biological origin (photosynthesis). Thus, the deterioration of the green world of our planet can significantly affect the reserves of free oxygen in the atmosphere.

About 21% of the oxygen released during photosynthesis and contained in the air is consumed by plants, animals and humans during respiration. An adult tree releases up to 180 liters of oxygen per day. A person consumes about 360 liters of oxygen per day in the absence of physical activity, and up to 900 liters during intensive work. A passenger car consumes the annual norm of oxygen consumed by a person per 1000 km, and a jet airliner consumes 35 tons of oxygen for a flight from Europe to America.

The content of carbon dioxide in the air depends even more on the life activity of various organisms. The most important natural sources of CO 2 are respiration, fermentation and decay - the total share of the listed processes accounts for 5.6.1% of CO 2 entering the atmosphere. About 38% of carbon dioxide enters the air from the soil ("soil respiration"); 0.1% - during volcanic eruptions. Quite a significant source of CO 2 are forest and steppe fires, as well as fuel combustion - up to 0.4%. The latter figure is constantly growing: in 1970, due to anthropogenic activity, 0.032% of the annual CO 2 intake entered the air; according to scientists, by the year 2000 the share of the source in question will increase to 0.038...0.04%.

Human activity also has a significant impact on the rate of carbon dioxide fixation in the biosphere. This is mainly due to excessive deforestation and pollution of the world's oceans. During photosynthesis, plants annually bind 6...7% of CO 2 from the air, and the process is most intense in forest ecosystems. The tropical rainforest records 1...2 kg of carbon dioxide per 1 m2 per year; in the tundra and deserts only 1% of this amount is recorded. In total, terrestrial ecosystems record 20...30 billion tons of CO 2 per year. Approximately the same amount is recorded by the phytoplankton of the World Ocean.

An increase in the content of carbon dioxide in the atmosphere has negative environmental consequences on a planetary scale and manifests itself in the form of the “greenhouse effect”. In general terms, this effect can be characterized as a constant warming of the climate, caused by the fact that, like a film in a greenhouse, accumulated in excessive amounts of CO 2 prevents the outflow of long-wave thermal radiation from the surface of the Earth, while freely transmitting the sun's rays. The specific manifestations of the “greenhouse effect” are different in different regions. In one case, these are unprecedented droughts, in the other, on the contrary, an increase in precipitation, unusually warm winters, etc.

Of the unstable components of atmospheric air, the most environmentally unfavorable for plants (both for humans and animals) are industrial gases - sulfur dioxide, fluorine, hydrogen fluoride, chlorides, nitrogen dioxide, ammonia, etc. The high vulnerability of plant organisms to “air poisons” is explained by the lack of special adaptation to the mentioned, relatively recently emerging factor. The relative resistance of some plants to industrial gases is associated with their pre-adaptation, that is, the presence of certain features that turned out to be useful in new conditions. Thus, deciduous trees tolerate air pollution more easily than coniferous trees, which is explained by the annual deciduous fall of the former, which gives them the opportunity to regularly remove toxic substances with litter. However, even in deciduous plants, when the gas composition of the atmosphere is unfavorable, the rhythm of seasonal development is disrupted: bud opening is delayed, and leaf fall occurs much earlier.

Abiotic factors are properties of inanimate nature that directly or indirectly affect living organisms. In Fig. Table 5 (see appendix) shows the classification of abiotic factors. Let's start our consideration with climatic factors of the external environment.

Temperature is the most important climatic factor. The intensity of metabolism of organisms and their geographical distribution depend on it. Any organism is capable of living within a certain temperature range. And although these intervals are different for different types of organisms (eurythermic and stenothermic), for most of them the zone of optimal temperatures at which vital functions are carried out most actively and efficiently is relatively small. The temperature range in which life can exist is approximately 300 C: from 200 to +100 bC. But most species and most activity are confined to an even narrower range of temperatures. Certain organisms, especially those in the dormant stage, can survive for at least some time at very low temperatures. Certain types of microorganisms, mainly bacteria and algae, are able to live and reproduce at temperatures close to the boiling point. The upper limit for hot spring bacteria is 88 C, for blue-green algae 80 C, and for the most tolerant fish and insects about 50 C. As a rule, the upper limits of the factor are more critical than the lower limits, although many organisms function near the upper limits of the tolerance range more effective.

Aquatic animals tend to have a narrower range of temperature tolerance than terrestrial animals because the temperature range in water is smaller than on land.

Thus, temperature is an important and very often limiting factor. Temperature rhythms largely control the seasonal and daily activity of plants and animals.

Precipitation and humidity are the main quantities measured when studying this factor. The amount of precipitation depends mainly on the paths and nature of large movements of air masses. For example, winds blowing from the ocean leave most of the moisture on the slopes facing the ocean, resulting in a “rain shadow” behind the mountains, which contributes to the formation of the desert. Moving inland, the air accumulates a certain amount of moisture, and the amount of precipitation increases again. Deserts tend to be located behind high mountain ranges or along coastlines where winds blow from vast inland dry areas rather than from the ocean, such as the Nami Desert in South West Africa. The distribution of precipitation by season is an extremely important limiting factor for organisms.

Humidity is a parameter characterizing the content of water vapor in the air. Absolute humidity is the amount of water vapor per unit volume of air. Due to the dependence of the amount of steam retained by air on temperature and pressure, the concept of relative humidity was introduced - this is the ratio of the steam contained in the air to the saturated steam at a given temperature and pressure. Since in nature there is a daily rhythm of humidity, increasing at night and decreasing during the day, and its fluctuations vertically and horizontally, this factor, along with light and temperature, plays an important role in regulating the activity of organisms. The supply of surface water available to living organisms depends on the amount of precipitation in a given area, but these values ​​do not always coincide. Thus, using underground sources, where water comes from other areas, animals and plants can receive more water than from receiving it with precipitation. Conversely, rainwater sometimes immediately becomes inaccessible to organisms.

Radiation from the Sun consists of electromagnetic waves of various lengths. It is absolutely necessary for living nature, as it is the main external source of energy. It must be borne in mind that the spectrum of electromagnetic radiation from the Sun is very wide and its frequency ranges affect living matter in different ways.

For living matter, the important qualitative characteristics of light are wavelength, intensity and duration of exposure.

Ionizing radiation knocks electrons out of atoms and attaches them to other atoms to form pairs of positive and negative ions. Its source is radioactive substances contained in rocks, in addition, it comes from space.

Different types of living organisms differ greatly in their ability to withstand large doses of radiation exposure. Most studies show that rapidly dividing cells are most sensitive to radiation.

In higher plants, sensitivity to ionizing radiation is directly proportional to the size of the cell nucleus, or more precisely to the volume of chromosomes or DNA content.

The gas composition of the atmosphere is also an important climatic factor. About 33.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen. The composition of the atmosphere was largely determined by volcanic gases. Due to the lack of oxygen, there was no ozone screen to block ultraviolet radiation from the Sun. Over time, due to abiotic processes, oxygen began to accumulate in the planet’s atmosphere, and the formation of the ozone layer began.

The wind can even change the appearance of plants, especially in those habitats, for example in alpine zones, where other factors have a limiting effect. It has been experimentally shown that in open mountain habitats the wind limits plant growth: when a wall was built to protect the plants from the wind, the height of the plants increased. Storms are of great importance, although their effect is purely local. Hurricanes and ordinary winds can transport animals and plants over long distances and thereby change the composition of communities.

Atmospheric pressure does not appear to be a direct limiting factor, but it is directly related to weather and climate, which have a direct limiting effect.

Aquatic conditions create a unique habitat for organisms, differing from terrestrial ones primarily in density and viscosity. The density of water is approximately 800 times, and the viscosity is approximately 55 times higher than that of air. Along with density and viscosity, the most important physical and chemical properties of the aquatic environment are: temperature stratification, that is, changes in temperature along the depth of a water body and periodic changes in temperature over time, as well as water transparency, which determines the light regime under its surface: photosynthesis of green and purple algae depends on transparency , phytoplankton, higher plants.

As in the atmosphere, the gas composition of the aquatic environment plays an important role. In aquatic habitats, the amount of oxygen, carbon dioxide and other gases dissolved in water and therefore available to organisms varies greatly over time. In reservoirs with a high content of organic matter, oxygen is a limiting factor of paramount importance.

Acidity, the concentration of hydrogen ions (pH), is closely related to the carbonate system. The pH value varies in the range from 0 pH to 14: at pH = 7 the environment is neutral, at pH<7 кислая, при рН>7 alkaline. If acidity does not approach extreme values, then communities are able to compensate for changes in this factor; community tolerance to the pH range is very significant. Waters with low pH contain few nutrients, so productivity is extremely low.

Salinity content of carbonates, sulfates, chlorides, etc. is another significant abiotic factor in water bodies. There are few salts in fresh waters, of which about 80% are carbonates. The content of minerals in the world's oceans averages 35 g/l. Open ocean organisms are generally stenohaline, whereas coastal brackish water organisms are generally euryhaline. The salt concentration in the body fluids and tissues of most marine organisms is isotonic with the salt concentration in seawater, so there are no problems with osmoregulation.

The current not only greatly influences the concentration of gases and nutrients, but also directly acts as a limiting factor. Many river plants and animals are morphologically and physiologically specially adapted to maintaining their position in the flow: they have well-defined limits of tolerance to the flow factor.

Hydrostatic pressure in the ocean is of great importance. With immersion in water of 10 m, the pressure increases by 1 atm (105 Pa). In the deepest part of the ocean the pressure reaches 1000 atm (108 Pa). Many animals are able to tolerate sudden fluctuations in pressure, especially if they do not have free air in their bodies. Otherwise, gas embolism may develop. High pressures, characteristic of great depths, as a rule, inhibit vital processes.

The soil.

Soil is the layer of substance lying on top of the rocks of the earth's crust. The Russian natural scientist Vasily Vasilyevich Dokuchaev in 1870 was the first to consider soil as a dynamic, rather than inert, medium. He proved that the soil is constantly changing and developing, and chemical, physical and biological processes take place in its active zone. Soil is formed through a complex interaction of climate, plants, animals and microorganisms. Soil composition includes four main structural components: mineral base (usually 50-60% of the total soil composition), organic matter (up to 10%), air (1525%) and water (2530%).

The mineral skeleton of the soil is an inorganic component that is formed from the parent rock as a result of its weathering.

Soil organic matter is formed by the decomposition of dead organisms, their parts and excrement. Organic residues that have not completely decomposed are called litter, and the final product of decomposition, an amorphous substance in which it is no longer possible to recognize the original material, is called humus. Thanks to its physical and chemical properties, humus improves soil structure and aeration, and increases the ability to retain water and nutrients.

The soil is home to many species of plant and animal organisms that influence its physicochemical characteristics: bacteria, algae, fungi or protozoa, worms and arthropods. Their biomass in various soils is equal (kg/ha): bacteria 10007000, microscopic fungi 1001000, algae 100300, arthropods 1000, worms 3501000.

The main topographic factor is altitude above sea level. With altitude, average temperatures decrease, daily temperature differences increase, precipitation, wind speed and radiation intensity increase, atmospheric pressure and gas concentrations decrease. All these factors influence plants and animals, causing vertical zonation.

Mountain ranges can act as climate barriers. Mountains also serve as barriers to the spread and migration of organisms and can play the role of a limiting factor in the processes of speciation.

Another topographic factor is slope exposure. In the northern hemisphere, south-facing slopes receive more sunlight, so the light intensity and temperature here are higher than on valley floors and northern-facing slopes. In the southern hemisphere the opposite situation occurs.

An important relief factor is also the steepness of the slope. Steep slopes are characterized by rapid drainage and soil washing away, so the soils here are thin and drier.

For abiotic conditions, all the considered laws of the influence of environmental factors on living organisms are valid. Knowledge of these laws allows us to answer the question: why did different ecosystems form in different regions of the planet? The main reason is the unique abiotic conditions of each region.

The distribution areas and numbers of organisms of each species are limited not only by the conditions of the external inanimate environment, but also by their relationships with organisms of other species. The immediate living environment of an organism constitutes its biotic environment, and the factors of this environment are called biotic. Representatives of each species are able to exist in an environment where connections with other organisms provide them with normal living conditions.

Let us consider the characteristic features of relationships of various types.

Competition is the most comprehensive type of relationship in nature, in which two populations or two individuals, in the struggle for the conditions necessary for life, influence each other negatively.

Competition can be intraspecific and interspecific.

Intraspecific competition occurs between individuals of the same species, interspecific competition occurs between individuals of different species. Competitive interaction may concern living space, food or nutrients, light, shelter and many other vital factors.

Interspecific competition, regardless of what underlies it, can lead either to the establishment of equilibrium between two species, or to the replacement of the population of one species by the population of another, or to the fact that one species will displace another to another place or force it to move to another place. use of other resources. It has been established that two species identical in ecological terms and needs cannot coexist in one place and sooner or later one competitor displaces the other. This is the so-called exclusion principle or Gause principle.

Since the structure of the ecosystem is dominated by food interactions, the most characteristic form of interaction between species in food chains is predation, in which an individual of one species, called the predator, feeds on organisms (or parts of organisms) of another species, called the prey, and the predator lives separately from the prey. In such cases, the two species are said to be involved in a predator-prey relationship.

Neutrality is a type of relationship in which none of the populations has any influence on the other: it does not in any way affect the growth of its populations, which are in equilibrium, or their density. In reality, however, it is quite difficult to verify, through observations and experiments in natural conditions, that two species are absolutely independent of each other.

Summarizing the consideration of the forms of biotic relationships, we can draw the following conclusions:

1) relationships between living organisms are one of the main regulators of the number and spatial distribution of organisms in nature;

2) negative interactions between organisms appear at the initial stages of community development or in disturbed natural conditions; in recently formed or new associations, the likelihood of strong negative interactions occurring is greater than in old associations;

3) in the process of evolution and development of ecosystems, a tendency is revealed to reduce the role of negative interactions at the expense of positive ones that increase the survival of interacting species.

A person must take into account all these circumstances when carrying out measures to manage ecological systems and individual populations in order to use them in his own interests, as well as anticipate the indirect consequences that may occur.

Abiotic, biotic and anthropogenic environmental factors

The natural environment of a living organism is composed of many inorganic and organic components, including those introduced by humans. Moreover, some of them may be necessary for organisms, while others do not play a significant role in their life. For example, a hare, a wolf, a fox and any other animal in the forest are in relationship with a huge number of elements. They cannot do without such things as air, water, food, a certain temperature. Others, for example, a boulder, a tree trunk, a stump, a hummock, a ditch, are elements of the environment to which they may be indifferent. Animals enter into temporary relationships with them (shelter, crossing), but not obligatory relationships.

The components of the environment that are important for the life of an organism and which it inevitably encounters are called environmental factors.

Environmental factors can be necessary or harmful to living things, promoting or hindering survival and reproduction.

Living conditions are a set of environmental factors that determine the growth, development, survival and reproduction of organisms.

The whole variety of environmental factors is usually divided into three groups: abiotic, biotic and anthropogenic.

Abiotic factors- this is a set of properties of inanimate nature that are important for organisms. These factors, in turn, can be divided for chemical(composition of the atmosphere, water, soil) and physical(temperature, pressure, humidity, currents, etc.). The diversity of relief, geological and climatic conditions also gives rise to a huge variety of abiotic factors.

Of primary importance are climatic(sunlight, temperature, humidity); geographical(length of day and night, terrain); hydrological(gr. hydor-water) - flow, waves, composition and properties of water; edaphic(gr. edaphos - soil) - composition and properties of soils, etc.

All factors can influence organisms directly or indirectly. For example, terrain affects lighting conditions, humidity, wind and microclimate.

Biotic factors- this is the totality of the impacts of the life activity of some organisms on others. For each organism, all the others are important environmental factors; they have no less effect on it than inanimate nature. These factors are also very diverse.

The whole variety of relationships between organisms can be divided into two main types: antagonistic(gr. antagonizsma - fight) and non-antagonistic.

Predation- a form of relationship between organisms of different trophic levels, in which one type of organism lives at the expense of another, eating it (+ -)

(Fig. 5.1). Predators can specialize in one prey (lynx - hare) or be polyphagous (wolf). In any biocenosis, mechanisms have evolved that regulate the numbers of both predator and prey. Unreasonable destruction of predators often leads to a decrease in their viability

Figure 5.1 - Predation

Competition( lat. concurrentia - competition) is a form of relationship in which organisms of the same trophic level compete for food and other conditions of existence, suppressing each other (- -). Competition is clearly evident in plants. Trees in the forest strive to cover as much space as possible with their roots in order to receive water and nutrients. They also reach in height towards the light, trying to overtake their competitors. Weeds clog other plants (Fig. 5.3). There are many examples from the life of animals. Intensified competition explains, for example, the incompatibility of wide-clawed and narrow-clawed crayfish in one reservoir: the narrow-clawed crayfish usually wins, since it is more fertile.

Figure 5.3-Competition

The greater the similarity in the requirements of two species for living conditions, the stronger the competition, which can lead to the extinction of one of them. The type of interactions of particular species may vary depending on conditions or life cycle stages.

Antagonistic relationships are more pronounced in the initial stages of community development. In the process of ecosystem development, a tendency is revealed to replace negative interactions with positive ones that increase the survival of species.

Non-antagonistic relationships can theoretically be expressed in many combinations: neutral (0 0), mutually beneficial (+ +), one-sided (0 +), etc. The main forms of these interactions are as follows: symbiosis, mutualism and commensalism.

Symbiosis(gr. symbiosis - cohabitation) is a mutually beneficial, but not obligatory relationship between different types of organisms (+ +). An example of symbiosis is the cohabitation of a hermit crab and an anemone: the anemone moves, attaching to the back of the crab, and with the help of the anemone it receives richer food and protection (Fig. 5.4).

Figure 5.4- Symbiosis

Sometimes the term "symbiosis" is used in a broader sense - "living together."

Mutualism(Latin mutuus - mutual) - mutually beneficial and obligatory for the growth and survival of relationships between organisms of different species (+ +). Lichens are a good example of the positive relationship between algae and fungi. When insects spread plant pollen, both species develop specific adaptations: color and smell in plants, proboscis in insects, etc.

Figure 5.5 - Mutualism

Commensalism(Latin commensa/is - dining companion) - a relationship in which one of the partners benefits, but the other is indifferent (+ 0). Commensalism is often observed in the sea: in almost every mollusk shell and sponge body there are “uninvited guests” who use them as shelters. Birds and animals that feed on the leftover food of predators are examples of commensals (Fig. 5.6).

Figure 5.6- Commensalism

Despite competition and other types of antagonistic relationships, in in nature, many species can coexist peacefully(Fig. 5.7). In such cases, each species is said to have own ecological niche(French niche - nest). The term was proposed in 1910 by R. Johnson.

Closely related organisms that have similar environmental requirements do not, as a rule, live in the same conditions. If they live in the same place, they either use different resources or have other differences in function.

For example, different types of woodpeckers. Although they all feed on insects in the same way and nest in tree hollows, they seem to have different specializations. The Great Spotted Woodpecker forages for food in tree trunks, the Medium Spotted Woodpecker in large upper branches, the Lesser Spotted Woodpecker in thin twigs, the Green Woodpecker hunts ants on the ground, and the Three-toed Woodpecker looks for dead and burnt tree trunks, i.e., different species of woodpeckers have different ecological niches.

An ecological niche is a set of territorial and functional characteristics of the habitat that meet the requirements of a given species: food, breeding conditions, relationships with competitors, etc.

Some authors use the terms “habitat” or “habitat” instead of the term “ecological niche.” The latter include only habitat space, and the ecological niche, in addition, determines the function that the species performs. P. Agess (1982) gives the following definitions of niche and environment: environment is the address where the organism lives, and niche is its profession(Fig. 5.7).

Figure 5.7- Peaceful coexistence of different organisms

Figure 5.8-Ecological niches

Anthropogenic factors- is a combination of various human impacts on inanimate and living nature. With the historical development of mankind, nature has been enriched with qualitatively new phenomena. Only by their physical existence do people have a noticeable impact on the environment: in the process of breathing, they annually release into the atmosphere 1*10 12 kg CO 2, and consumed with food about 5*10 15 kcal. To a much greater extent, the biosphere is influenced by human production activities. As a result, the relief and composition of the earth's surface, the chemical composition of the atmosphere, climate change, fresh water is redistributed, natural ecosystems disappear and artificial agro- and techno-ecosystems are created, cultivated plants are cultivated, animals are domesticated, etc.

Human impact can be direct and indirect. For example, cutting down and uprooting forests has not only a direct effect (destruction of trees and bushes), but also an indirect effect - the living conditions of birds and animals change. It is estimated that since 1600, humans have destroyed 162 species of birds and over 100 species of mammals in one way or another. But, on the other hand, it creates new varieties of plants and breeds of animals, constantly increasing their yield and productivity. The artificial relocation of plants and animals also has a great impact on the life of ecosystems. Thus, rabbits brought to Australia multiplied there so much that they caused enormous damage to agriculture.

Rapid urbanization (Latin urbanus - urban) - the growth of cities in the last half century - has changed the face of the Earth more than many other activities in the history of mankind. The most obvious manifestation of anthropogenic influence on the biosphere is environmental pollution.

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Environments, components and phenomena of inanimate, inorganic nature (climate, light, chemical elements and substances, temperature, pressure and movement of the environment, soil, etc.), directly or indirectly affecting organisms. Ecological encyclopedic... ... Ecological dictionary

abiotic factors- abiotiniai veiksniai statusas T sritis ekologija ir aplinkotyra apibrėžtis Fiziniai (temperatūra, aplinkos slėgis, klampumas, šviesos, jonizuojančioji spinduliuotė, grunto granulometrinės savybės) ir cheminiai (atmosferos, vanden s, grunto cheminė… Ekologijos terminų aiškinamasis žodynas

Factors of inorganic nature affecting living organisms... Large medical dictionary

Abiotic factors- factors of the inorganic, or nonliving, environment in the group of environmental adaptation factors operating among biological species and their communities, divided into climatic (light, air, water, soil, humidity, wind), soil... ... The beginnings of modern natural science

ABIOTIC FACTORS- Factors of the inorganic environment affecting living organisms. These include: the composition of the atmosphere, sea and fresh waters, soil, climate, as well as zoohygienic conditions of livestock buildings... Terms and definitions used in breeding, genetics and reproduction of farm animals

ABIOTIC FACTORS- (from the Greek a negative prefix and biotikos vital, living), inorganic factors. environments affecting living organisms. K A. f. include the composition of the atmosphere, sea. and fresh water, soil, climate. characteristics (temperature pa, pressure, etc.). The totality... Agricultural Encyclopedic Dictionary

abiotic factors- (from the Greek a negative prefix and biōtikós vital, living), factors of the inorganic environment that affect living organisms. K A. f. include the composition of the atmosphere, sea and fresh waters, soil, climatic characteristics (temperature... Agriculture. Large encyclopedic dictionary

ABIOTIC FACTORS- environment, a set of conditions in the inorganic environment that affect the body. Chemical a.f.: chemical composition of the atmosphere, sea and fresh waters, soil or bottom sediments. Physical a.f.: temperature, light, barometric pressure, wind,... ... Veterinary encyclopedic dictionary

Environments, a set of conditions in the inorganic environment that affect organisms. A.f. are divided into chemical (chemical composition of the atmosphere, sea and fresh water, soil or bottom sediments) and physical, or climatic (temperature, ... ... Great Soviet Encyclopedia

Books

• Ecology. Textbook. RF Ministry of Defense stamp
• Ecology. Textbook. Grif Ministry of Defense of the Russian Federation, Potapov A.D.. The textbook examines the basic principles of ecology as a science about the interaction of living organisms with their habitat. The main principles of geoecology as a science about the main...

Abiotic factors are factors of inanimate nature that directly or indirectly act on an organism - light, temperature, humidity, the chemical composition of the air, water and soil environment, etc. (i.e., properties of the environment, the occurrence and impact of which does not directly depend on the activities of living organisms ).

Light (solar radiation) is an environmental factor characterized by the intensity and quality of the radiant energy of the Sun, which is used by photosynthetic green plants to create plant biomass. Sunlight reaching the Earth's surface is the main source of energy for maintaining the thermal balance of the planet, the water metabolism of organisms, the creation and transformation of organic matter by the autotrophic element of the biosphere, which ultimately makes it possible to form an environment capable of satisfying vital needs

organisms.

Temperature is one of the most important abiotic factors, on which the existence, development and distribution of organisms on Earth largely depends [show]. The importance of temperature lies primarily in its direct influence on the speed and nature of metabolic reactions in organisms. Since daily and seasonal temperature fluctuations increase with distance from the equator, plants and animals, adapting to them, exhibit different needs for heat.

Humidity is an environmental factor characterized by the water content in the air, soil, and living organisms. In nature, there is a daily rhythm of humidity: it increases at night and decreases during the day. Together with temperature and light, humidity plays an important role in regulating the activity of living organisms. The source of water for plants and animals is mainly precipitation and groundwater, as well as dew and fog.

In the abiotic part of the environment (in inanimate nature), all factors can primarily be divided into physical and chemical. However, to understand the essence of the phenomena and processes under consideration, it is convenient to represent abiotic factors as a set of climatic, topographic, cosmic factors, as well as characteristics of the composition of the environment (aquatic, terrestrial or soil).

The main climatic factors include solar energy, temperature, precipitation and humidity, environmental mobility, pressure, and ionizing radiation.

Environmental factors - properties of the environment that have any effect on the body. Indifferent elements of the environment, for example, inert gases, are not environmental factors.

Environmental factors exhibit significant variability in time and space. For example, temperature varies greatly on the surface of land, but is almost constant at the bottom of the ocean or deep in caves.

Classifications of environmental factors

By the nature of the impact

Direct acting - directly affecting the body, mainly on metabolism

Indirectly acting - influencing indirectly, through changes in directly acting factors (relief, exposure, altitude, etc.)

By origin

Abiotic - factors of inanimate nature:

climatic: annual sum of temperatures, average annual temperature, humidity, air pressure

edaphic (edaphogenic): soil mechanical composition, soil air permeability, soil acidity, soil chemical composition

orographic: relief, height above sea level, steepness and aspect of the slope

chemical: gas composition of air, salt composition of water, concentration, acidity

physical: noise, magnetic fields, thermal conductivity and heat capacity, radioactivity, solar radiation intensity

Biotic - related to the activity of living organisms:

phytogenic - influence of plants

mycogenic - influence of fungi

zoogenic - influence of animals

microbiogenic - influence of microorganisms

Anthropogenic (anthropic):

physical: use of nuclear energy, travel on trains and planes, influence of noise and vibration

chemical: the use of mineral fertilizers and pesticides, pollution of the Earth’s shells with industrial and transport waste

biological: food; organisms for which humans can be a habitat or source of food

social - related to relationships between people and life in society

By spending

Resources - elements of the environment that the body consumes, reducing their supply in the environment (water, CO2, O2, light)

Conditions - environmental elements not consumed by the body (temperature, air movement, soil acidity)

By direction

Vectorized - directionally changing factors: waterlogging, soil salinization

Perennial-cyclical - with alternating multi-year periods of strengthening and weakening of a factor, for example climate change in connection with the 11-year solar cycle

Oscillatory (pulse, fluctuation) - fluctuations in both directions from a certain average value (daily fluctuations in air temperature, changes in the average monthly precipitation throughout the year)

Optimum Rule

In accordance with this rule, for an ecosystem, an organism or a certain stage of its development, there is a range of the most favorable (optimal) factor value. Outside the optimum zone there are zones of oppression, turning into critical points beyond which existence is impossible. The maximum population density is usually confined to the optimum zone. Optimum zones for different organisms are not the same. For some, they have a significant range. Such organisms belong to the group of eurybionts. Organisms with a narrow range of adaptation to factors are called stenobionts.

The range of factor values ​​(between critical points) is called environmental valence. A synonym for the term valence is tolerance, or plasticity (variability). These characteristics depend largely on the environment in which the organisms live. If it is relatively stable in its properties (the amplitudes of fluctuations of individual factors are small), it contains more steno-bionts (for example, in an aquatic environment); if it is dynamic, for example, ground-air, eurybionts have a greater chance of survival in it. The optimum zone and ecological valence are usually wider in warm-blooded organisms than in cold-blooded ones. It should also be borne in mind that the ecological valence for the same species does not remain the same in different conditions (for example, in northern and southern regions during certain periods of life, etc.). Young and senile organisms, as a rule, require more conditioned (homogeneous) conditions. Sometimes these requirements are quite ambiguous. For example, with respect to temperature, insect larvae are usually stenobiont (stenothermic), while pupae and adults may be eurybiont (eurythermic).

Related information.