The vegetation of steppe landscapes has three main features.
Firstly, steppe ecosystems are characterized by low grass cover with a predominance of narrow-leaved (less commonly broad-leaved) turf grasses that can tolerate periodic drought. Secondly, under the steppe vegetation a powerful root mass develops, tens of times greater than the green ground mass. It is no coincidence that the botanist I. Pachosky wittily called the steppe “a forest upside down.” Thirdly, steppes have the ability to undergo rapid transformations: accumulation or decomposition to mineral components.
The natural vegetation cover of the steppes is characterized by a richness of species and very high species saturation. In terms of the number of species growing per 1 m2, the steppe flora has no equal among all other types of vegetation temperate zone. Thus, on the standard meter plots of the Kursk and Voronezh steppes, V.V. Alekhin (1934) counted from 37 to 56 plant species, and in the meadow steppes near Kursk up to 80 species were noted. For comparison, we can say that the richest oak forests middle zone Russia has the same number of species on an area 100 times larger - 100 m2.
In the virgin steppes of Eurasia, turf grasses predominate: feather grass, fescue, tonkonog, oats, bluegrass, as well as onions and turf sedge species. IN North America, except for the feather grass species endemic to the mainland, common different kinds bearded vulture - also a turf grass. The steppes are characterized by many species of monocots and dicotyledonous plants, constituting forbs, as well as wormwood subshrubs and shrubs of the caragana (or chiliga) genera: spirea, bean. Important features of steppe vegetation are its pronounced phenological variability during the warm period of the year, as well as instability due to the alternation of dry and more precipitation-rich years. Significant changes in the vegetation of the steppes are caused by rodents, which in some years almost completely destroy the grass stand, as well as by grazing of wild and especially domestic ungulates.
In the steppes various types communities are formed from several ecologically similar life forms (Gorshkova, 1966). For northern steppes Communities of perennial grasses with a predominance of forbs are characteristic; in the southern steppes communities of grasses (feather grass and fescue) predominate; in the steppes of the semi-desert zone the role of subshrubs increases.
With a single general character steppe zone the appearance of steppe vegetation is sensitive to changes natural conditions. The vast majority of steppe plants are xerophytes; they have developed universal adaptations to life in dry habitats and successfully tolerate overheating and dehydration (Bush, 1936).
The development of perennial xerophytic grasses, well adapted to dry climates, - most important feature vegetation cover steppes. Among them it is necessary to mention, first of all, such turf grasses as feather grass, fescue, tonkonogo, and wheatgrass. They form dense turfs 10 cm or more in diameter. The turf contains a lot of dead remains of old stems and leaves and has the remarkable property of intensively absorbing melt and rain moisture and retaining it for a long time. Among the typical steppe grasses there are almost no rhizomatous plants.
The leaves of steppe grasses are very narrow, no wider than 1.5-2 mm. In dry weather, they fold lengthwise, and their evaporating surface becomes even smaller. Adaptations for reducing evaporation are, to one degree or another, characteristic of most steppe plants: in some (bedstraw, kachim, thyme, chickweed, solyanka, etc.) the leaf blades are very small, in others (gill, adonis, trinia, etc.) they are divided into thinnest lobules or segments.
A whole group of steppe plants creates a special “microclimate” for themselves due to abundant pubescence. Many species of astragalus, hairy breastwort, gray speedwell, Marshall cornflower, some types of sage and many other shaggy steppe plants use pubescence to protect themselves from sun rays and thus fight drought. Another way steppe plants adapt to drought is a layer of wax or other waterproof substance secreted by the skin. This property is distinguished by plants with a smooth shiny surface: milkweed, gillyweed, Russian cornflower, etc. To avoid overheating, some steppe grasses (capulata, serpukha, chondrillas) place their leaves with their edges facing the sun. And such a steppe weed as wild lettuce generally orients its leaves in the north-south plane, representing a kind of living compass.
Among the summer steppe grasses there are few bright green plants: the leaves and stems of most of them are colored in dull, faded tones. This is another device that helps protect against excessive lighting and overheating. Let us add that all inhabitants of the steppe - both cereals and representatives of herbs - have highly developed root systems. This is also a sign of drought resistance.
Powerful root system, 10-20 times greater in mass than above-ground organs, is a universal adaptation of steppe plants, and especially turf grasses, to life in a steppe climate. Steppe plants are 90-95% located in the top half-meter layer of soil. This horizon in the steppe ecosystem is the most unstable in terms of both moisture conditions and thermal regime. But this is also a natural moisture accumulator and the warmest place.
The upper half-meter horizon of steppe ecosystems is the place of accumulation and consumption of humus; it is rich in elements mineral nutrition plants. That is why steppe plants, By figuratively V.G. Mordkovich, sank “neck-deep” into the soil, concentrating most of their mass there (1982).
The root systems of steppe plants are very mobile organs. In dry years, they capture moisture through the development of small sucking hairs. In wet years, many steppe plants grow large roots, which store nutrients for the “hungry” time. After burning, burning, trampling or biting, the underground part of the plant seems to retain the memory of the above-ground part and it grows again when favorable conditions.
A large group of steppe plants, the so-called ephemeroids, develop in the spring, when the soil is sufficiently moist. Thus, they have time to bloom and bear fruit before the onset of the dry period. Typical steppe ephemeroids are tulips, irises, crocuses, goose bows, adonis, as well as open lumbago, some types of astragalus, etc.
In an open landscape and steppe climate with constant winds Steppe plants have developed unique adaptations for the distribution of fruits and seeds. Particularly interesting in this regard are the so-called “tumbleweeds”. They can live almost exclusively in the steppes with their wide open spaces.
The “tumbleweed” group is formed by the Tatarian katran, the common toadstool, the common cutter, the common eryngium, the paniculata, the sandy horned grass, the Tatarian gonioliomon, the prickly zopnik, the Ukrainian catnip, the splayed cornflower, the plague solyanka, the Tatarian kermek, the Sarmatian belvalia and many other plants.
Our planet is amazing organism, the balance and versatility of which can amaze even skeptics. Every plant that grows on Earth has evolved and changed over many centuries to become what it is today. And the process of evolution has made many plant crops very interesting in their ability to survive in harsh conditions and the ability to adapt to a changing climate and environment.
It would seem that a steppe zone with open treeless spaces can hardly arouse interest in the diversity of plant cover and richness of flora. This is not Crimea or the Caucasus! But still, this is not the Sahara! There are interesting plants that show off under the scorching sun here too. To survive in such conditions they had to adapt. They may not all be handsome in appearance, but most importantly they are not uninteresting! Therefore, let's talk now about what herbaceous plants exist interesting plants steppes, and what is their uniqueness?
cornflower
This plant is widespread in many parts of our homeland. The most amazing feature of this crop is that its seeds are capable of crawling. Yes, yes, they spread across the surface of the earth, as if alive. A cornflower seed is similar in shape to a rye seed. At the top of the smooth and especially shiny achene there is a tiny pappus consisting of white hairs. This crest is precisely the main organ for the movement of seeds. When wet, it seems to shorten, and when dry, it lengthens again. All the hairs have notches on them, which are directed in one direction; it is with them that the tuft rests on various uneven ground conditions. Contraction or lengthening of the hairs leads to movement of the achene.
If you inhale the smoke from a burnt cornflower, you will feel fear. Our ancestors believed that this plant was able to attract love and eliminate or prevent damage and attacks of evil spirits.
Squirting cucumber
This plant belongs to the pumpkin family. He can be found on the banks of the Cherny or Mediterranean Sea. This name this culture received thanks to its unique and spectacular ability to disperse seeds. Even with minimal touch, the ripe fruit of the mad cucumber flies away from the stalk, resulting in a hole being formed at the site of separation. From it, in turn, a stream of bitter mucus containing seeds is released. Such a mass can fly twelve meters from the mother plant.
Also interesting is the fact that a mad cucumber is capable of walking very far large area, so one plant, clinging to other herbaceous crops, can cover seven square meters.
Methods for adapting plants to steppe conditions
As is known, on the territory of the steppes for the most part The climate is dry. Rainfall is rare here, so plants have had to create opportunities for themselves to survive for many centuries. Thus, many plant crops of the steppe have narrow leaves, thanks to which they lose the minimum possible amount of moisture. Examples include fescue and feather grass. In addition, there is another evolutionary solution for survival - fleshy leaves in which water accumulates. Sedum and also youngsters have such leaves.
Some plants have foliage and stems covered with small hairs. This feature significantly reduces the amount of evaporated moisture; it is characteristic of sage and bruise. Certain crops are characterized by leaves covered with a specific waxy coating, thanks to which moisture is consumed extremely sparingly. Such foliage is observed in fescue and wheatgrass.
A separate group is occupied by various bulbous plants - tulips, irises and meadowsweet. Such crops store nutrients inside the bulbs.
Most steppe plants have particularly long and branched roots, thanks to which they can extract life-giving moisture even from very deep layers of soil. For example, wormwood and feather grass.
Tumbleweed
This is a whole group of herbaceous plants that grow in the steppe or desert. After such crops die, they leave behind round-shaped formations. Such formations consist of dried parts of the plant and can be quite large in size. Tumbleweeds are driven along the ground by the wind and disperse seeds. This formation begins with a dead stem, which the wind tears off from the ground and carries across meadows and fields; as it moves, the stem takes other plants with it, rolling into a large lump.
Among the plant representatives that can form tumbleweeds are: herbaceous plants steppes like kachim, chistets, kermek, staghorn, eryngium, cutter, etc.
In order not to spill all the seeds at once, we pump paniculata, which has also adapted. The teeth of its capsules are always bent inward. The seeds from it spill out through a narrow gap only with a strong push, and then only if they are successfully positioned to pass between the teeth.
Fraxinella
This is an amazing steppe plant that has the ability to escape the heat with the help of its own resources, namely, by isolating essential oil. Such separated substances are characterized by special volatility, thanks to which the ash tree can protect itself from high temperatures and not dry out, since their release comes with the release of energy. If you bring a match to such a plant on a hot day, the vapors of the oils near it will flare up, but the crop itself will remain unharmed. A similar experiment with this plant was carried out by the daughter of the famous naturalist Linnaeus at the Uppsala Botanical Garden in Sweden.
Feather grass
This is a fairly common steppe plant that has a very interesting ability reproduction. On each feather grass seed there is a thin silver hair, which plays the role of a parachute to move such planting material in space. After the seed falls on the soil, such a hair in the evening, under the influence of air moisture, seems to be screwed into the soil. Tiny notches prevent him from twisting back. As a result, the seed eventually falls underground, where it can overwinter and then germinate. What a plant! But that's not all that's interesting. The same twisting occurs when a seed lands on an animal's fur. The shepherds said that they had heard from their grandfathers about cases when, from a lot of embedded grains, the animal got sick, and sometimes died after that.
sedum
Purple sedum is a leafy succulent that can store water in its leaves and then slowly use it up. People knew about this for a long time and even in ancient times they called sedum “living water.” Its young shoots and leaves are used in soups and salads, as they have a pleasant sour taste. They are even fermented and salted for the winter.
Rejuvenated
The rosette of the plant consists of succulent thick leaves. There are from 30 to 80 of them. Moisture accumulates in them. Moreover, some species of juveniles have leaves with a hairy “fringe” on which drops of fog from the air condense. In addition, the leaves of all juveniles are covered with a strong skin with virtually no stomata, which also helps retain moisture.
Even though I am quite a few years old, last summer I visited the Russian steppe for the first time. At school, I imagined this area as just a treeless area, but in reality it is a harsh place - the air is dry, there is nowhere to hide from the hot sun, the wind manages to bring a column of dust from somewhere. How does something grow and live in such conditions?
Plants of the steppe and their adaptability to the conditions of the zone
As I already indicated above, there are practically no trees. Shrubs are rare. The flora is represented by herbs, mainly cereals and bulbous plants. Examples:
- feather grass;
- wheatgrass;
- fescue;
- anemone;
- reed grass;
- tulip;
- bluegrass;
- steppe poppy
And a great many more. But what helps plants survive? The most unpleasant moment for plants in the steppe is dryness. Consequently, all adaptations come down to the ability to survive in conditions of lack of moisture. Adaptation is carried out through roots (fibrous system for rapid absorption, long rod system for absorbing water from great depth(more than 10 m) and modification of roots into bulbs, tubers, rhizomes), leaves (covered with villi or wax, small, narrow, dismembered) and trunks (accumulate water).
Animals of the steppe and their adaptation methods
I remember reading that the forest is good for animals because there is somewhere to hide. In the steppe this is obviously difficult. Their adaptations to survive in this zone are focused on shelter or camouflage and, like plants, surviving the lack of water. I'll start with the first one. The fauna is represented by ungulates and rodents. All of them are brown, gray or beige in color - to match the color of the soil and dry grass. If rodents, for their safety, dig holes where they hide from predators and heat, then larger animals (herbivorous ungulates) have to gather in herds.
Mammals endure the lack of water on their feet, i.e., in search of life-giving moisture, they cover considerable distances. Rodents quench their thirst with succulent herbs.
Regarding the birds, I can say that they were not confused and adapted to making nests on the ground. And the owl and hoopoe, if necessary, hide in other people's holes.
How did animals adapt to life in the steppe? The answer to this question is not simple, because it is quite difficult to survive in the conditions of the steppe.
How do animals adapt to life in the steppe?
Animals of the steppe have adapted to life in conditions open area, arid climate, periods of lack of food, lack of water.
The need for reliable shelter– this is what all animals have in common. The steppe zones are clearly visible, and small animals would not be able to escape from predators without good shelter. Most steppe animals use burrows as shelters, in which they spend most of their time. Burrows not only protect fauna from danger, but also help to escape from unfavorable conditions. weather conditions, serve as a temporary shelter for animals hibernation. It is there that mammals raise their offspring, protecting them from any external dangers. Digging holes is best suited to rodents: mice, hamsters, voles. They can easily make holes even in dry, hard soil. In addition to rodents, large animals also need reliable shelter in flat areas. Foxes and badgers also dig holes, and those representatives of the fauna that cannot dig a hole on their own try to take over someone else's. The habitat of foxes often becomes, for example, prey for wolves, and small predators - stoats and ferrets, as well as snakes - settle in the large burrows of gophers. Even some birds, such as hoopoe and owl, hide in burrows from danger.
Each animal of the steppe adapts in its own way to the constant threat from predators. Some representatives of the fauna able to run fast. These include the saiga, brown hare, and jerboa.
Painting is also a method of protection. Many animals are colored like dry grass. This helps them hide from enemies, as well as sneak up on their prey unnoticed.
The inhabitants of the steppe zone are characterized by gregariousness. Hoofed mammals graze under the watchful eye of their leader, who, in case of danger, will immediately give a signal and the herd will take off. Gophers, for example, are unusually careful. They look around every now and then, monitoring what is happening around them. Having heard something suspicious, the gopher immediately notifies its relatives about it, and they instantly hide in holes. Speed and instant reaction allow many animals to be invulnerable even in open space.
Animals have also adapted to temperature changes during the day. These fluctuations determine the activity of mammals in different time. The most favorable hours for birds are the early morning hours; mammals emerge from their burrows in the morning and evening. Most animals seek refuge from the scorching rays of the daytime sun in burrows. The only exception is reptiles that like to lie on hot stones.
As winter approaches, life in the steppe comes to a standstill. Most animals hibernate throughout cold period while in their holes. This is how gophers, hedgehogs, jerboas, reptiles and insects wait for spring. Birds and the bats go to winter for warmer climes. Those rodents that will spend the winter staying awake stock up on food. Hamsters manage to bring up to several kilograms of grain into their hole.
Animals and plants of the steppe are forced to adapt to a constant lack of water. Each individual copes with this task differently. Hoofed mammals and birds are able to travel long distances in search of water. Gerbils, jerboas, gophers and some other rodents eat succulent grass, replenishing their need for water. Predators living in the steppe also do without water, as they get the required amount from the animals they eat.
Animals also adapted to the lack of food. Among the inhabitants of the steppe expanses there are many who can consume both animal and plant foods. Omnivorous animals of the steppe are foxes, hedgehogs, some species of reptiles and birds that eat berries along with insects.
Due to the lack of trees, steppe birds make their nests on the ground (larks, bustards, quail, steppe eagles, short-eared owls).
The steppes have two characteristics, which determine specific ways of plant adaptation. Firstly, the lack of moisture affects the steppes, especially in the summer, because the amount of precipitation there is not large, and the evaporation rate is high. And secondly, hot daytime temperatures do not create the most favorable conditions for plants. However, nature has many ways of adapting living organisms. And two of them were also useful for steppe plants.
And to understand how plants adapted in the steppe, we should consider both of these methods. The first is preserving moisture and reducing its consumption. It is realized due to the special shape or coating of the leaves. Usually in steppe plants they are very narrow, or densely pubescent, or covered with a cuticle (a special waxy substance called cutin). The second method of adaptation is the use of a powerful, highly developed root system.
Steppe plants, like most other species, reproduce sexually. This means that the steppe climate does not create any peculiarities in how fertilization occurs in plants. But some species have quite original ways spreading their seeds. For example, the well-known Tumbleweed grows and blooms very quickly in favorable conditions, and when moisture becomes scarce, it quickly dries into an openwork ball and is easily lifted off the ground by the wind. Then the plant begins to roll, covering vast distances and scattering its seeds along the way.
Steppe plants usually shed their leaves during dry periods to reduce their need for moisture. It not only changes appearance steppe, but also demonstrates how plants influence the soil, enriching it. In addition, the powerful root system of steppe plants, growing deeply into the soil, increases the porosity of the soil and its water permeability. Also, plants influence the soil, redistributing moisture and changing the composition of the soil in the process of life.
Because of climatic features, annual ephemerals are most typical for steppes. They have a very high development speed and a short growing season, after which the plant dies completely or its above-ground parts die off. This information explains how a plant develops from a seed in the steppe. And this happens very quickly as soon as the humidity rises, that is, suitable conditions for growth appear.
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