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Phytocenosis. Composition of phytocenosis: participation of species and its assessment (abundance, cover, phytomass). Vertical and horizontal composition of phytocenosis. Composition, structure and structure of phytocenoses Types of phytocenoses

Development of views on the nature of phytocenosis

At the dawn of the development of geobotany, the idea of a phytocenosis as a really existing discrete unit of vegetation cover took shape, which at that time seemed quite appropriate, since the identification of individual phytocenoses significantly facilitated the task of studying vegetation as a whole. However, at the beginning of the 20th century, a diametrically opposite point of view was expressed, according to which the vegetation cover was considered continuous, and its division into individual elements - phytocenoses - was artificial. The absence of sharp boundaries between plant communities and the presence of transition zones between them contributed to the emergence of the doctrine of continuity of vegetation cover, based on individualistic concept:

Each type of plant is individual in its requirements for conditions. external environment and has characteristic environmental amplitudes for each environmental factor
Environmental factors change gradually, both in space and time
The transition from one combination of cenopopulations to another occurs continuously: some species gradually decrease their abundance and disappear, others appear and increase.

Extreme supporters of the concept of continuity of vegetation cover considered not a phytocenosis, due to its artificiality, but an individual plant as an object of study of geobotany. Extreme supporters of the idea of discreteness postulated a clear distinction and delineation of individual phytocenoses.

Based on the synthesis of both concepts, the idea of a combination of both discreteness and continuity in the nature of vegetation was put forward. This was presented as one of the manifestations of inconsistency inherent in the material world as a whole. According to this idea, the vegetation cover has the property of continuity, but it is not absolute, but relative. At the same time, it also has the property of discreteness, but this is not absolute, but relative. These properties are organically combined, not excluding, but complementing each other.

Formation of phytocenosis

Primary free area earth's surface after a volcanic eruption

The formation of phytocenoses can be considered both in a dynamic aspect (change of communities) and in terms of their formation on free areas of the earth's surface.

Distinguish primarily vacant areas, which in the past were not populated by plants and do not contain their rudiments. Phytocenoses can form on them only when diaspores are introduced from the outside. Such areas include rocky outcrops, fresh river and sea sediments, the exposed bottom of reservoirs, areas freed from glaciers, lava fields, etc. In general, they occupy insignificant areas on Earth.

Secondary vacant areas are formed in places where vegetation previously existed, but was destroyed due to the influence of some unfavorable factor. Examples include burnt areas, scree, unseeded arable land, areas of phytocenoses eaten away by pests or livestock. In most cases, soil and diasporas are preserved on them, and the formation of phytocenoses occurs much faster than in initially free areas.

The formation of a phytocenosis is a continuous process, but can be conditionally divided into stages:

Pioneer group- coenopopulations are small in number, there are no relationships between them
Group-thicket community- coenopopulations are distributed in clumps in which interaction between plants occurs
Diffuse community- coenopopulations mix, a system of interspecific interactions is developed

Migration- introduction of diasporas
Ecesis- consolidation of the first settlers
Aggregation- formation of groups of offspring around mother plants
Invasion- mixing of coenopopulations
Competition- development of competitive relations due to a sharp increase in crowd density
Stabilization- formation of a sustainable closed community

E.P. Prokopiev, summing up the various division schemes of the process of formation of a phytocenosis, proposes to distinguish three stages in it:

Receipt of primordia into a free area. The species composition of the emerging phytocenosis will depend on the species composition of plants in the surrounding area and the nature of the distribution of their diaspores, and the main role will be played by the rudiments of allochoric species, mainly anemochores.
Ecotopic (abiotic) selection. Not all diasporas that land on a free plot will take root on it: some will not germinate, and some of those that have sprouted will die in their young state due to an unfavorable combination of abiotic factors. Established plants will be pioneers for this territory.
Phytocenotic selection. Due to the reproduction and settlement of pioneer species throughout the site, they will begin to influence each other and change the ecotope, forming a biotope (habitat). The primary abiotic environment of the ecotope turns into a secondary biotic - phytoenvironment. Under the influence of the phytoenvironment and the mutual influence of plants, some pioneer species that are not adapted to it fall out. This may occur, for example, due to shading or allelopathy. At the same time, new species, already adapted to the given phytoenvironment, are established on the site.

Factors of phytocenosis organization

Factors in the organization of a plant community can be divided into four groups: characteristics of the environment (ecotope), the relationship between plants, the influence of heterotrophic components (animals, fungi, bacteria) on vegetation and disturbances. These groups of factors determine the combination and characteristics of cenopopulations of species in a phytocenosis.

Ecotop is the main factor in the organization of phytocenosis, although it can be significantly transformed by the biotic influences of plants or disturbances. Abiotic factors influencing community organization include:

climatic (light, heat, water regimes, etc.)
edaphic (particle-size and chemical composition, humidity, porosity, water regime and other properties of soils and soils)
topographic (relief characteristics)

Plant relationships are divided into contact And mediated : transabiotic- through abiotic environmental factors and transbiotic- through third organisms.

Violations, both anthropogenic and natural origin can completely transform the phytocenosis. This occurs during fires, felling, livestock grazing, recreational load, etc. In these cases, derivative phytocenoses are formed, which gradually change towards the restoration of the original one if the impact of the disturbing agent has ceased. If the impact is long-term (for example, during recreation), communities are formed that are adapted to existence at a given level of stress. Human activity has led to the formation of phytocenoses that did not previously exist in nature (for example, communities on toxic industrial waste dumps).

Interactions of organisms in phytocenoses

The presence of a system of relationships between plants is one of the main signs of the existing phytocenosis. Studying them, due to the large overlap and strong influence of abiotic factors, is a difficult task and can be implemented either in the form of an experiment, during which the relationships of two specific species are studied, or by isolating such relationships from a complex of others using methods of mathematical analysis.

Direct (contact) mutual influences

In ecological terms, the relationship between epiphytes and phorophytes is usually represented by commensalism, but elements of competition may also appear:

epiphytes partially intercept light and moisture from phorophytes
by retaining moisture, they contribute to the decay of the phorophyte
By shading the phorophyte, epiphytes reduce its effective photosynthetic surface
growing profusely, can cause deformation or breakage of phorophytes

Transabiotic interactions

The influence of plants on each other, mediated by abiotic environmental factors. They arise due to the overlap of phytogenic fields of neighboring plants. Divided into competition And allelopathy.

Competition develops either due to the initial limitation of habitat resources, or as a result of a decrease in their share per plant due to overpopulation. Competition leads to a decrease in resource consumption by the plant and, as a consequence, a decrease in the rate of growth and storage of substances, and this, in turn, leads to a decrease in the quantity and quality of diaspores. Distinguish inside- And interspecific competition.

Intraspecific competition affects fertility and mortality rates in a coenopopulation, determining the tendency to maintain its numbers at a certain level, when both values balance each other. This number is called maximum density and depends on the amount of habitat resources. Intraspecific competition is asymmetrical - it affects different individuals differently. The total phytomass of the cenopopulation remains constant in a fairly large range of density values, while the average mass of one plant begins to steadily decrease when thickened - law of constant harvest(C=dw, where C is the yield, d is the coenopopulation density and w is the average weight of one plant).

Interspecific competition is also widespread in nature, since the vast majority of phytocenoses (except for some agrocenoses) are multispecies. The multi-species composition is ensured by the fact that each species has an ecological niche characteristic only of it, which it occupies in the community. Moreover, the niche that a species could occupy in the absence of interspecific competition is fundamental, tapers to size implemented. In a phytocenosis, differentiation of ecological niches occurs due to:

different plant heights
different depths of penetration of the root system
contagious distribution of individuals in the population (in separate groups/spots)
different periods of growing season, flowering and fruiting
unequal efficiency of plants' use of habitat resources

With weak overlap of ecological niches, coexistence of two cenopopulations can be observed, while with strong overlap, the more competitive species displaces the less competitive species from the habitat. The coexistence of two highly competitive species is also possible due to the dynamism of the environment, when one species or another gains a temporary advantage.

Allelopathy- the influence of plants on each other and on other organisms through the release of active metabolites into the environment both during the life of the plant and during the decomposition of its remains. Allelopathic activity of one type or another is determined by a certain set of chemical substances of different nature, the qualitative and quantitative composition of which significantly depends on external conditions. Allelopathically active substances are released both aboveground organs (mainly leaves) and underground, mainly in three ways:

active secretion through glands or hydathodes
washout by precipitation
excretion through decomposition of litter by microorganisms

The sum of secretions of various plants in a phytocenosis is its biochemical environment. Since the composition of secretions is not constant, we can talk about the existence of an allelopathic regime of phytocenosis, along with water, air, etc.

Transbiotic interactions

Influence of phytocenosis on the environment

Structure of phytocenosis

Depending on the specifics of the research in the concept of “biocenosis structure”, V.V. Masing identifies three directions that he developed for phytocenoses.

1. Structure, as a synonym for composition (specific, constitutional). In this sense, they talk about species, population, biomorphological (composition of life forms) and other structures of the cenosis, meaning only one side of the cenosis - composition in the broad sense. In each case, a qualitative and quantitative analysis of the composition is carried out.

2. Structure, as a synonym for structure (spatial, or morphostructure). In any phytocenosis, plants are characterized by a certain affinity to ecological niches and occupy a certain space. This also applies to other components of the biogeocenosis. Between the parts of the spatial division (tiers, sinusia, microgroupings, etc.) you can quite easily and accurately draw boundaries, you can plot them on the plan, calculate the area, and then, for example, calculate resources useful plants or animal feed resources. Only on the basis of data on the morphostructure can one objectively determine the points at which certain experiments were performed. When describing and diagnosing communities, the spatial heterogeneity of cenoses is always studied.

3. Structure, as a synonym for sets of connections between elements (functional). The basis for understanding structure in this sense is the study of relationships between species, primarily the study of direct connections - the biotic connex. This is the study of chains and nutrition cycles that ensure the circulation of substances and reveal the mechanism of trophic (between animals and plants) or topical (between plants - competition for nutrients in the soil, for light in the above-ground sphere, mutual assistance).

All three aspects of the structure biological systems are closely interconnected at the coenotic level: the species composition, configuration and placement of structural elements in space are a condition for their functioning, that is, life activity and production plant mass, and the latter, in turn, largely determines the morphology of cenoses. And all of these aspects reflect the environmental conditions in which the biogeocenosis is formed.

The phytocenosis consists of a number of structural elements. There are horizontal and vertical structure of phytocenosis. The vertical structure is represented by tiers, distinguished by visually determined horizons of phytomass concentration. The tiers consist of plants of “different heights”. Examples of layers are 1st tree layer, 2nd tree layer, ground cover, moss-lichen layer, understory layer, etc. The number of layers may vary. The evolution of phytocenoses is moving in the direction of increasing the number of tiers, as this leads to a weakening of competition between species. Therefore, in the older temperate forests of North America, the number of layers (8-12) is greater than in similar younger forests of Eurasia (4-8).

The horizontal structure of the phytocenosis is formed due to the presence of tree canopies (under which an environment is formed, somewhat different from the environment in the inter-canopy space), terrain heterogeneities (which cause changes in groundwater levels, different exposures), and the species characteristics of some plants (reproducing vegetatively and forming monospecies “spots” , changes in the environment of one species and the response of other species to this, allelopathic effects on surrounding plants), animal activities (for example, the formation of patches of ruderal vegetation on rodents).

Naturally repeating spots (mosaics) in a phytocenosis, differing in the composition of species or their quantitative ratio, are called microgroups, and such a phytocenosis is mosaic.

Heterogeneity may also be random. In this case it is called variegation.

Dynamics of phytocenoses

dynamic processes: reversible (daily, seasonal, fluctuations) and irreversible (succession, evolution of communities, disturbances of communities). Fluctuations are year-to-year changes associated with unequal conditions for the existence of plants in different years. the composition does not change, the size and age composition of the population may change. Succession is a gradual change in phytocenoses that is irreversible and directional. caused by internal or external reasons, in relation to phytocenoses, reasons. primary and secondary successions are distinguished. Primary successions begin on lifeless substrates, while secondary successions begin on substrates on which the vegetation has been disturbed.

Classification of phytocenoses

When classifying phytocenoses, similar communities are combined into groups - classification units.

The lowest unit of classification is association (a set of homogeneous phytocenoses that have more or less the same appearance, similar floristic composition and the same dominant species in tiers). The names of the associations are given by listing the Russian names of the dominant plants of each tier of the phytocenosis, starting from the uppermost tier (Scots pine + Norway spruce - lingonberry + blueberry - pleurocium moss) or the Latin generic and species names of the dominants (Pinus sylvestris + Picea abies - Vaccinium vitis-idaea + Vaccinium myrtillus - Pleurozium schreberi) with the addition of suffixes to the base

Each phytocenosis, including forest, is characterized by a set of characteristics that give a clear idea of its structure and structure. The main features of a phytocenosis are species composition, layering, abundance, quantitative and qualitative relationships between species, occurrence, projective cover and vitality. There are quantitative indicators to assess these characteristics.
When describing phytocenoses, a test area in the shape of a rectangle or square is allocated. The size of the trial plot should fully reflect all the features of the phytocenosis. It has been established that for forest communities its minimum size is 400-500 m2.
In geobotany, certain rules have been adopted for describing phytocenoses. They boil down to the following: all descriptions are numbered, the date of work, the author, the size of the trial area are indicated, geographical position sample area, position on the relief, and also characterizes the microrelief, moisture conditions, ground (dead) cover, soil type with a description of the soil section and analysis of soil samples.
The main component of the forest phytocenosis is the tree stand, which includes certain tree species. On the registration (test) area, a complete count of the trunks of each species is carried out (only mature trees are taken into account). Mature trees of the first size form the first tier, and mature trees of the second size form the second. Teenagers are especially taken into account. Within each tier, a numerical estimate is given of the ratio of trees of different species in the phytocenosis, either in fractions of a unit, or for 10 trunks, i.e., how many trunks out of 10 are for each species. For example, the recording form D6B4 means that there are 6 trunks per oak, and 4 trunks per elm. The diameter of the trunks is measured with a taxator fork at chest height (1.3 m) or with a tailor's meter, at the same height the circumference of the trunk is determined and the resulting value is divided by 3.14. All trees in the trial plot are measured.
The height of the tree is determined using an eclimeter. To do this, depending on the height of the tree, measure 10, 20 or 30 m from it and from the found point sight the top and find the angle. The height of the tree is determined based on the angle and distance from the trunk using tables.
When characterizing a tree stand, the diameter of the crowns is taken into account as measured by a tape measure stretched along the ground from the base of the trunk to the edge of the crown projection in the direction from north to south and from west to east. The average value is derived from the four measurements. At the same time, the height of crown attachment is calculated by eye or instrumentally as the distance from the base of the trunk to the place of attachment of the lower branches of the crown.
In the taxation characteristics of a forest stand, the sum of cross-sectional areas per hectare is important. This indicator is assessed with a Bitterlich full-meter (circular sampling method). A full gauge is a ruler 0.5-1.0 m long with attachments at the end in the form of a fork with a solution of the last 1.0-2.0 cm, respectively. Through the slot of the fork, the diameter of the tree is visible; being at one point and turning 360°, the observer sights all the trees. If, when sighting, the diameter of the tree is greater than the diameter of the full diameter, then the tree is taken into account; if it is equal to it, then every second tree is taken into account. When one tree is covered by another, you need to move 0.5-2 m away in order to clearly see the tree being assessed, and then return to its original place. The number of trees taken into account is noted separately for each species. The sum of cross-sectional areas in square meters per 1 hectare is equal to the number of trees counted. For example, 15 trees are taken into account, therefore, the cross-sectional area is 15 m2/ha. The sum of cross-sectional areas can be determined by the predominant diameter of trunks and their number in the sample plot for each tree species.
The state of seedlings and undergrowth, their number per unit area is the most important indicator of phytocenosis.
The regeneration of the forest stand is assessed on five 2x2 m plots, located in an envelope in the corners and in the center of the trial plot. For each breed, the number of specimens of undergrowth and seedlings of different ages is determined separately. Then the average is calculated. Undergrowth with a height of more than 1.5 m is taken into account throughout the entire sample area.
Accounting for undergrowth involves assessing the species composition, crown density, and the nature of distribution over the sample plot. The crown density of the undergrowth is determined, as for the main tree stand, in fractions of one or as a percentage.
The total projective cover of soil with grass and shrubs is determined as the percentage of the area occupied by projections of above-ground parts of plants - grasses and shrubs. Mixed forests are characterized by the greatest species richness, the main components of which are light coniferous and small-leaved tree species. In such forest communities, thanks to the see-through crowns, favorable conditions are created for the development of shrub and herbaceous vegetation. The aspect of a phytocenosis consists of the most striking features of the structure of a phytocenosis: the abundance of a species, its density, color, dominance in tiers.
In phytocenoses there is often no homogeneity; there is a mosaic pattern in the form of individual spots and clumps. This applies to both the arboreal and terrestrial herbaceous layers. This phenomenon is sinusia- determined by microrelief conditions, lighting, soil type, hydrological conditions. When describing a phytocenosis, each synusia is assessed by size, configuration, and order of placement on the terrain.
The species composition of plants is described in the form of Russian and Latin names, and ecological and biological groups are distinguished here - one-, two-, perennial, forest, forest-meadow, steppe species, weeds and others, as well as shrubs, subshrubs, herbs.
Abundance is an estimate of the number of wasp species in a community. In geobotany, they usually use the scale of the Danish botanist Dru-de, based on an eye assessment of the abundance of each species in the phytocenosis. A more accurate, but more labor-intensive method for assessing abundance is the method of counting individuals of a species per unit area. An estimate of abundance can also be given by the weight method.
The Drude scale includes six levels of abundance:
Socialis (Soc) - plants close together with above-ground parts, forming a general background, background plants;
Copiosus3 (Cop3) - plants are found very abundantly;
Copiosus2 (Cop2) - quite a lot of plants, scattered;
Copiosus1 (Cop1) - plants are found occasionally;
Sparsus (Sp) - few plants;
Solitarius (Sol) - solitary plants, there are very few of them.
The Drude scale can be combined with the projective coverage scale. This indicator of species abundance provides a more objective assessment of the importance of the species in the plant community.
The method for recalculating the abundance of a species is based on the allocation of census plots, the size of which depends on the nature of the forest phytocenosis. The trees in the phytocenosis are counted on an area of 1,000 m2 (10x100), 1,600 m2 (20x80) or 2,000 m2 (20x100), shrubs and herbaceous vegetation are analyzed on areas measuring 100 m2.
The weight method of accounting for the abundance of species is mainly used in geobotanical studies in herbaceous phytocenoses, but it can also be used in forest phytocenoses for the herbaceous layer. In this case, 20 plots of 0.1 m2 each are allocated on trial plots and the plants are cut at soil level, then the cut plants are laid out by type and weighed. After completing the work, the average indicators of participation of each species in the formation of the ground mass of the phytocenosis are calculated for all recording sites.
Projective coverage- an indicator characterizing the magnitude of the horizontal projection of the above-ground parts of all plants of a given species found on the trial plot, in relation to the size of the trial plot. Express projective coverage as a percentage. This indicator is highly variable both by year and by season.
An important characteristic of species in phytocenoses is their vitality, which is assessed by the degree of development or suppression of the species in the phytocenosis. The most objective assessment of the vitality of a species can be obtained during flowering or fruiting of a tree species. There is a vitality scale for assessment: For - “good vitality” - the species blooms steadily, bears fruit, and produces normal annual growth; 36 - the same, but the species does not reach normal growth sizes; 2 - “satisfactory vitality” - the vegetative part of the species is well developed, but it does not bear fruit; 1 - “poor vitality” - the species does not bloom, does not bear fruit, and vegetates poorly.
When describing phytocenoses, the phenophases of plants must be noted, which is important for characterizing the seasonal rhythm of phytocenoses as a whole.
In forest phytocenoses, the following stages of seasonal development, or phenological phases, are usually distinguished: vegetation, budding, flowering, fruiting, vegetation after fruiting, dying, dormancy. NOT. Bulygin evaluates the phenological development of woody plants, dividing them into two stages of ontogenesis: the first is juvenile, the second is virginal and subsequent ones. The second stage, in turn, is divided into observations of generative and generative-growth shoots.
Forest phytocenoses often contain lichens and mosses, such as component ground cover. Given general characteristics of these groups of plants, their abundance and projective cover are indicated. Here without detailed characteristics The presence of algae and fungi is noted.
In the descriptions of forest phytocenoses, epiphytic vegetation on trunks, stones, and dead wood is also noted, and the size and configuration of the phytocenosis, its environment, transitions to adjacent phytocenoses, and the place of the phytocenosis in the ecological series are also assessed.

Tundra vegetation. The tundra is distributed mainly in the northern hemisphere. It occupies large areas on the northern edge of the continents of Eurasia and North America, and is also found on the Antarctic islands of the southern hemisphere. In the USSR, the area occupied by tundra is 14.7% of the entire territory of the country.

The ecological conditions of the tundra are extremely unique and cause the appearance of a certain adaptability of plants.

In arctic and subarctic climates, a characteristic feature of the tundra is the absence of woody vegetation. Of the existing environmental factors, the thermal and chemical characteristics of tundra soils are of greatest importance, explaining the reasons for its treelessness. Many hypotheses have been put forward on the issue of treeless tundras. One of the main reasons should be considered the phenomenon of “physiological dryness”, which is created in supercooled thawed soil when tree roots, due to low temperatures, cannot “use” soil water (B.N. Gorodkov). According to some scientists, the ecological conditions for the germination of tree seeds in the tundra are deteriorating due to climate change (V.B. Sochava).

The flora of the tundra is distinguished by a certain originality. Its species composition is poor and numbers no more than 500 species. higher plants. In the process of adaptation to the conditions of existence in the tundra, certain phytocenoses. A particularly important role in them is played by green mosses and lichens, as well as perennial plants adapted for development in conditions of a short growing season.

The herbaceous vegetation of the tundra is low-growing (5-15 cm), forms many shoots, due to which it often takes a semi-oval shape in the form of “pillows” (for example, semolina, saxifrage plants). Due to the abundance of light in summer time tundra plants have large and bright flowers (poppy, forget-me-not, tar, etc.).

Also common in the tundra are shrub plants with a characteristic woody stem and dull leathery leaves that have a waxy coating and pubescence (blueberry, cranberry, bearberry, dreadberry, etc.).

Among the shrubs common in the tundra, only dwarf birch and different kinds Iv. These low-growing shrubs have small, pubescent leaves, reclining trunks, often hidden in the moss cover. Among the coniferous shrubs, juniper is found at the southern border of the tundra, and dwarf cedar is found in Eastern Siberia.

Distributed across three continents, the tundras do not remain homogeneous. Within their boundaries, from north to south, one can outline a natural change in certain types of tundra(formations).

Arctic tundra is common on the coast of the Arctic Ocean. Its vegetation cover is characterized by sparseness (coverage area no more than 60%). Of the shrubs, only the Dread is found here. Herbaceous species are represented by sedge, cotton grass, polar poppy, etc. The moss cover is formed by polytrichous and green mosses. Lichens are characterized by scale forms. Areas not occupied by vegetation are rocky placers, areas complicated by stone polygons and polygons.

Moss-lichen tundra is characterized by a complex vegetation cover. On clay soils, a moss cover of green mosses is developed. The upper tier of this formation includes willows, blueberries, and dreadas; of herbs - sedge, arctic bluegrass.

Lichen associations are common on sandy soils. The following geographical pattern can be outlined in their distribution. In the western Arctic (up to the Yenisei River), in the presence of deep snow cover Resin tundras are widespread (lichen predominates - moss), which provide valuable pastures for reindeer herding. In the eastern part of the Taimyr Peninsula, in conditions of little snow in winter, bushy lichens (Allectoria, Cetraria) are common.

Moss-lichen tundras are characterized by significant swampiness (up to 30%). The swamps are predominantly lowland moss and sedge with a characteristic hilly topography (Fig. 64).

Shrub tundra is a formation that replaces the moss-lichen tundra to the south. In the western sector of the Arctic

shrubs are represented by dwarf birch (erniki). East of the river Lena is dominated by various types of willows and alders. The wide development of shrub plants is characteristic. Very large areas (up to 50%) are occupied by swamps.

In the south, the tundra is limited by forest-tundra. In this subzone there is an alternation of open forest and tundra areas. Thus, in the European and North American forest-tundra, birch and spruce woodlands are common, in the Asian forest - larch. In the forest-tundra, trees are far apart from each other, their height is no more than 6-8 m, have thin curved trunks. The ground cover is dominated by lichens, green mosses and grasses (Fig. 65).

Forest-tundra should be considered as a transition zone to the forest zone. Its border is very tortuous. On flat interfluves, the tundra moves south. On the contrary, along river valleys and mountain slopes of southern exposure, the forest moves north. The sparseness of the forest-tundra tree stand is a consequence of unfavorable climatic conditions associated with low rainfall.

It should be noted that the boundary between tundra and forest does not remain constant and is subject to certain dynamics. Facts such as the overgrowth of the tundra of the Far Northeast and North America larch forest, the overgrowth of patchy and polygonal areas of the Arctic tundra indicate that the forest boundary tends to shift in a northerly direction.

Taiga vegetation.This type of vegetation is widespread in the area temperate climate northern hemisphere - Eurasia and North America. Within the USSR, taiga occupies more than 11 million hectares. km 2.

Vegetation of the taiga type is mesophilic and is represented by such life forms as coniferous trees, shrubs, grasses, etc. This type of phytocenosis is distinguished by its complex structure and great diversity. Further characteristics coniferous forests will be given using the example of the taiga of the USSR.

Forest classification is carried out taking into account forest-forming species, i.e. those tree species that predominate in the forest. On this basis, coniferous forests are divided into dark coniferous(spruce, fir, cedar) and light coniferous(pine, larch).

The distribution of coniferous forests is largely determined by the distribution area of their forest-forming species (see Fig. 62). At the same time, in order to make the characteristics of forests more specific and show all the diversity, they use the concept of types of forest. Forest types are distinguished on the basis of the general physiognomic characteristics of the phytocenosis, its floristic composition and habitat conditions. In taxonomic meaning, the forest type approaches the concept of association.

Let us consider a brief description of the main formations of coniferous forests.

Spruce forests. This formation is most common among dark coniferous forests of the European part of the USSR and Western Siberia. The forest-forming species is spruce. In the USSR, spruce has up to 10 species, of which the most common are common spruce (European part of the USSR) and Siberian spruce (northeast of the European part of the USSR and Western Siberia).

Spruce is one of the shade-tolerant species, so spruce forests are dense and shaded. The undergrowth in the spruce forest does not develop widely. In the undergrowth there are shrubs: buckthorn, honeysuckle, juniper. The herbaceous cover is characterized by shrubs (lingonberries and blueberries), ferns, mosses, wood sorrel, wintergreen, etc. Green mosses and bearded lichen are abundant in the spruce forest.

Spruce forests form a large number of associations. Currently, to identify them, as well as determine patterns of distribution, ecological series method, developed by acad. V. N. Sukachev. Ecological series make it possible to identify the sequence of arrangement of plant associations in connection with changes in environmental conditions (Fig. 66).

If we consider the change in types of spruce forest depending on environmental conditions, the following pattern can be outlined. Optimal growing conditions (point ABOUT) corresponds to the association spruce-sorrel forest. With increasing dryness and decreasing soil fertility (a number of A) association is replaced spruce-lingonberry. In conditions of increased dryness it grows spruce-lichen forest. In moist areas with signs of stagnation

waterlogging (number IN) develops spruce-blueberry. A typical spruce forest association is spruce forest, which grows in low areas of excessive moisture. In swampy conditions it is replaced by sphagnum spruce forest- an association where spruce is heavily oppressed, and sphagnum moss forms a continuous cover (the final member of the series IN). Under conditions of flow humidification (row D) an association is formed along the stream valleys marsh-grass spruce forest(stream) with developed undergrowth. The association is also peculiar oak spruce forest, which is confined to the most fertile soils of the forest zone (a number WITH). Spruce usually contains an admixture of broad-leaved species (oak, linden), hazel in the undergrowth, and a cover where oak broad-grass predominates is also developed.

The given spruce forest associations do not exhaust all the diversity. The considered ecological series show how the composition of associations changes with changes in environmental conditions and position in the relief (Fig. 67). Thus, ecological series can be considered as one of the methods for studying plant associations with frequent changes in space.

A certain pattern is emerging in the distribution of dark coniferous forests on the territory of the USSR. Within the European part of the USSR, spruce forests predominate, which occupy wide and flat watersheds. In the West Siberian Lowland, forests of this type gravitate toward river valleys, as areas that are more drained. In southern Siberia they are found in the mountains, where the participation of fir and cedar increases (Tian Shan).

Fir forests are similar in characteristics to spruce forests. Their predominant associations belong to the “greenwashers” group.

Fir forests have a more limited distribution. They avoid both dry and wet places. Mixed fir forests with an admixture of Siberian spruce and cedar are often found (West Siberian Lowland, Ural, Altai, Sayan Mountains, etc.).

Larch forests occupy a large area in the USSR. The distribution area of larch is in Eastern Siberia (north of 48° N), where Dahurian larch is widespread. This species, having a shallow root system, is well adapted to growing in conditions of a sharply continental climate on swampy soils with close permafrost. Siberian larch is common in the mountains of southern Siberia.

A characteristic feature of larch forests is that they form pure stands of trees. Since the density of crowns in the forest is small, the larch forest has a park-like appearance. In the upper tier, larch reaches 30-35 m height. The ground cover is dominated by pine grasses and shrubs (reed grass, lingonberries), and in some places sphagnum mosses. Larch forests have a large supply valuable wood industrial importance, and are also valuable hunting grounds.

Pine forests. This is the most widespread type of coniferous forest in the temperate zone. The main forest-forming species is Scots pine. Other types of pine (Crimean, Pitsunda, etc.) have a very limited range.

Compared to other tree species, pine has a large ecological range. It is most widespread on sandy plains and river terraces. At the same time, it forms peculiar associations in peat bogs. Pine forests penetrate into the forest-steppe zone and are found in the mountains.

Pine forests, like larch forests, often have pure stands of one or two-tier structure. The grass cover in them is poor and is mainly characterized by the predominance of shrubs (heather, blueberries, lingonberries, etc.). In pine forests of dry habitats, a cover of lichens or green mosses is developed (Fig. 68, 1).

The main associations of a pine forest and the patterns of their change can be expressed by a system of ecological series, similar to spruce forests, which include associations of certain environmental conditions (lichen pine forest, green moss pine forest, sphagnum pine forest, etc.).

In terms of the composition of their associations, cedar forests are close to pine forests. Their distribution area is confined to the northeast of the European part of the USSR and Western Siberia. Cedar forests, like pine forests, are found in sphagnum bogs. In the mountains of Siberia cedar forests mixed type - cedar-larch (Altai, Sayan, etc.).

The geographical patterns of distribution of coniferous (taiga) forests in the northern hemisphere are quite complex. Distributed in the temperate climate zone, coniferous forests vary noticeably in composition both from north to south and from west to east.

Currently, geobotanists divide taiga-type forests into three groups of formations: northern taiga, middle and southern taiga, which are characterized by the predominance of certain forest types. Geographically, they represent wide stripes (subzones), which are clearly visible on the plains (Russian Plain, West Siberian Lowland). Thus, the northern taiga of the European part of the USSR, located south of the forest-tundra, is distinguished by the dominance of species of Siberian origin (spruce, cedar, larch). The predominant forest type here is a green moss spruce forest. The middle taiga is characterized by spruce (spruce-blueberry) and spruce-fir forests; southern taiga - spruce forests with an admixture of broad-leaved species (oak, elm, linden, maple). The northern and middle taiga are very swampy, and sphagnum pine forests are common in the raised bogs.

The taiga in the Asian part of the USSR retains the same division. Its distinctive feature is the large swampiness of forests (up to 50%).

In the northern taiga of the West Siberian Lowland ( southern border coincides with the latitudinal segment of the river. Ob) cedar, spruce-larch, and pine forests are widespread. East of the river In the Yenisei region, larch forests predominate in the area of permafrost development.

The middle taiga in Western Siberia is characterized by the dominance of dark coniferous fir-spruce forests (“urmans”) and cedar forests. In Central Siberia and Yakutia they are replaced by larch-pine forests (Dahurian larch).

The southern taiga is characterized by a predominance of pine and birch forests, and in lower areas - spruce-fir (Western Siberia), cedar-fir (Central Siberia) and larch open forests (Transbaikalia). A special variety is represented by swampy larch forests “Mari”, widespread in Central and Eastern Siberia and the southern regions of Transbaikalia. The forests consist of Daurian larch, have an undergrowth of birch (birch) and a continuous sphagnum cover. This type of forest is confined to river valleys, where peat-bog soils are formed.

Coniferous forests of Western Europe do not form marked subzones and grow only in the mountains (Alps, Pyrenees, Carpathians, etc.). In addition to ordinary pine and spruce, there are European larch and fir, which form a special forest belt.

Coniferous forests in North America occupy large areas (Labrador, Alaska, the mountains of the Pacific coast, the Atlantic plains). Unlike European coniferous forests of the American type, there is a wide variety of species of pine, spruce, fir, and larch. Specific species are also found in forests, especially on the west coast of the mainland, such as Douglas fir, tsuga, thuja, in the Sierra Nevada mountains - gigantic sequoia(mammoth tree). The named tree species are distinguished by their gigantic height (up to 80-100 m). The main reason for the species richness of the American taiga is the favorable conditions for species migration during the Ice Age.

Summer green deciduous forests. Deciduous forests in temperate latitudes become widespread in marine climates. In Eurasia, these forests are typical of Western Europe, the south of the Russian Plain, the Caucasus and the Carpathians. Further to the east they are replaced by coniferous forests. The habitat of deciduous forests is represented in the Far East of the USSR, in eastern China and on the Japanese Islands. Deciduous forests are found in North and South America (Patagonia).

Deciduous forests are divided into broad-leaved and small-leaved.

The broad-leaved forest-forming species are oak, beech, linden, maple, elm and ash. These forests have a well-developed crown, and the upper layer in them is usually composed of one forest-forming species. Since the forests are shady, the undergrowth and grass cover are poorly expressed. The predominant herbaceous species are ephemeroids, which develop intensively in spring and autumn. Typical broadleaf forest formations are as follows.

Beech forests are most widespread in Western Europe. Near the northern border of their range, they are distributed on the plains, in southern Europe - in the mountains, where they form a forest belt. Within the USSR, beech forests are found in western Ukraine, Moldova, as well as in the Carpathians, Crimea and the Caucasus, where they form a special belt.

The beech forests of Europe are of the same type. The forest-forming species in them is beech. Due to the large shade, undergrowth and summer grasses are usually absent. In the mountains, beech's companions are fir and yew.

Beech forests in North America (eastern USA, Canada) differ from European ones. The forests have a wide variety of species, but are dominated by American beech and sugar maple. Vines made from wild grapes are characteristic.

Oak forests are the more common type of broadleaf forest. In the USSR, oak forests are common in the European part, where they form a subzone of broad-leaved forests. In oak groves, the main forest-forming species is pedunculate oak, to which maple, ash, linden, and elm are mixed. The oak groves are multi-tiered. They contain an undergrowth of hazel and euonymus. The grass cover includes plants - oak forest broad grass (sniffle, lungwort, hoofed grass etc.), the aspect of ephemeroids with subsnow development is also characteristic in spring (see Fig. 68, 1, 2). Compared to beech forests, oak forests have a wider range and are found in other subzones, for example, forest-steppe, where they form gulley forests. The forest-forming species in the oak forests of Western Europe are holm and downy oak, which are combined with evergreen rhododendron and yew (Ireland). In North America, oak forests are common in the continental west bordering the prairies. Unlike European ones, there is a large presence of broad-leaved species: several types of oak, maple, walnut, plane tree, etc. Oak forests are also characterized by lianas.

Small-leaved forests (birch, aspen, alder) Along with conifers and broad-leaved trees, they are especially widespread. By origin these forests are secondary which became widespread after the cutting down of broad-leaved coniferous forests. However, examples of primary birch forests are known in the West Siberian forest-steppe (pegs) and in Kamchatka.

There is also a mixed type of forests - coniferous-broad-leaved, in which small-leaved species occupy a significant place. These forests are mainly distributed on the border of coniferous and broad-leaved forests. Depending on changing environmental conditions, there is an alternation various types coniferous and broad-leaved forests: oak forests are confined to the slopes of the southern exposure of river valleys; they are common on terraces pine forests, on flattened watersheds there are spruce forests. Mixed forests are especially typical for the European part of the USSR, where they form an entire subzone.

Steppe vegetation.Steppes are a herbaceous type of xerophytic vegetation with a closed grass stand, developing in a temperate climate with a lack of summer precipitation. The steppes occupy the largest areas in the USSR, stretching across a wide strip in the European and Asian parts. Steppe areas (Pashto) found within the Danube Lowland. In North America, steppes are called prairies.

Vast expanses of steppes (pampas) in subtropical parts of South America, Africa and Australia.

We will consider the main features of steppe vegetation using the example of the steppes of the USSR. In terms of physiognomic characteristics, steppe vegetation differs sharply from other herbaceous types (for example, meadows, swamps), since it expresses xerophytic features. To withstand summer droughts, plants have developed adaptations such as a waxy coating on the leaves, their pubescence, and in some cases, reduction of the leaf blade. All above-ground vegetative parts of plants have a dull green tint, which creates a certain steppe background.

Steppe vegetation is characterized by the predominance of special floristic groups. Are being widely developed turf grasses, having narrow rolled leaves and turf deep in the soil (feather grass, fescue, tonkonog). Also presented sedge, legumes, forbs, ephemerals.

Most distinctive feature the steppe is hers dynamism. The flora of the steppe consists of plants that do not coincide in their phenological phases. Therefore, the appearance of the steppe and its color background changes in different periods. So, in early spring the appearance of the steppe is determined by the flowering of yellow tulips, blue hyacinths, golden goose onions and white crocuses. The silvery color of steph in May is due to feather grass. June marks the flowering of tumbleweed plants. The golden-green background of the steppe in July is associated with the flowering of feather grass. In August, wormwood and steppe asters begin to bloom.

During the entire flowering period in the steppe, there are up to 12 colorful phases (Streletskaya steppe). The noted change in aspects in the steppe should be considered as the adaptation of vegetation to certain environmental conditions.

V.V. Alekhine divided the steppes of the USSR into types: northern (meadow) steppes and southern steppes located on the border with semi-deserts.

The northern steppes are characterized by the development of colorful forbs. The participation of feather grasses is insignificant (common and angustifolia feather grass). The predominant cereals are loose turf (brome, wild oats, bentgrass, etc.). The maximum species richness was noted when the number of species per 1 m 2 reaches 80, and their number is up to 2000. Steppe phytocenoses have a complex layering.

The southern steppes are distinguished by the predominance of feather grasses, forming the aspect: feather feather grass (fescue) and feather grass “tyrsa”. There are very few forbs in the grass cover. Only the phase of spring ephemeroids (tulips) is clearly expressed and the number of tumbleweed plants is increased. In the southern steppes, the grass cover is very sparse and is generally characterized by low species richness compared to the northern steppes: by 1 m 2 area there are no more than 12 species.

The northern and southern steppes in the European part of the USSR are completely plowed. The remaining virgin areas have been declared nature reserves.

The Siberian steppes have many common features with the European ones. However, in conditions of a peculiar rugged topography (Barabinskaya steppe), they are combined with grass swamps and salt marshes. In the steppes of Western Siberia, feather grasses are prevalent. Near the border of the birch forest-steppe there are forest and swamp species, as well as saltwort plants.

The North American prairies are close in floristic composition to the European steppes. Three types of grasses are dominant in the American prairies: feather grass, wheatgrass and grama (the latter is not found in the European steppes). A feature of the prairies is the distribution of deep-rooting species, whose roots go to a depth of 1.6-2 m. At the same time, cereals are distinguished by their high height (80-120 cm).

The types of steppes in North America are extremely diverse. The tallgrass prairies of the Great Plains are close to the “northern” type steppes. Cereal formations are dominated by grasses such as bearded grass, Indian grass, feather grass, and wheatgrass. In spring there is an abundance of flowering herbs.

In the drier conditions of the Prairie Plateau, short-grass steppes are common, where dense-grass grasses (gram grass, endemic buffalo grass) predominate.

The “Pampas” of South America occupy vast plains in the south and east of the mainland (Argentina, Uruguay). The vegetation has all the features of xerophytes and is characterized by clearly defined changing aspects. The main elements of the steppes are perennial grasses of the genus feather grass, bearded grass, and millet. A variety of herbs.

Desert vegetation. The desert type of vegetation is characterized by a predominance of subshrubs and shrubs. The factors determining the development of deserts are essentially climatic, since they are formed in an arid climate with a high moisture deficit in extratropical and tropical regions of the globe (deserts of the USSR, central Asia, the Sahara, Colorado, South America, Australia, etc.) - Unfavorable in Deserts also have edaphic conditions: the soils are depleted in humus and saline, groundwater is located at great depths. Compared to steppe vegetation, desert vegetation is characterized by a sharp increase in drought-resistant species. In the process of plants adapting to unfavorable climate conditions, a number of life forms. Among them, the plants most adapted to tolerate dryness are xerophytes, having a developed taproot and superficial lateral roots, a rigid stem, and reduced leaves. Most typical representatives are semi-shrub plants, such as camel thorn, black and white saxaul, etc. (Fig. 69).

The other predominant life form is ephemeroids. These tuberous and bulbous perennial plants finish

growing season for 1-2 months before the onset of the dry period (bluegrass, tulips, onions). At this time, the deserts are covered with a continuous carpet of flowering plants.

A number of desert plants have the ability to accumulate water reserves in the hairs covering the leaves (for example, the kokpek subshrub) or in the tissues of the leaves and stem (plants succulents). The latter are very characteristic of many deserts around the world. Their main representatives are cacti, euphorbia, etc. The amount of water they accumulate can be 96% of their weight. The named life forms form a complex complex with saltwort plants.

According to the nature of environmental conditions and, first of all, according to the precipitation regime, the nature of the substrate, the deserts of the globe can be divided into a number of types: clayey, sandy, rocky, saline. Let us consider their main features using the example of the deserts of the USSR.

The deserts of Central Asia occupy more than 2 million hectares. km 2(10% of the area). By climatic conditions they can be divided into northern and southern.

Northern deserts are formed in a temperate continental climate with uniform distribution precipitation throughout the year. These are predominantly clay deserts (Ustyurt, Bet-Pak-Dala, etc.).

A common feature of their vegetation cover is the predominance of xerophyte shrubs in combination with saltworts. Depending on the soil, a number of typical phytocenoses are formed. The most common are wormwood deserts (clayey ones), which are characterized by the predominance of various types of wormwood and saltwort. The vegetation cover is monotonous and very sparse (cover does not exceed 40%).

In areas with highly saline soil, saltwort deserts are widespread, represented by a group of associations dominated by the low subshrub Kokpek and the cushion-shaped subshrub Biyurgun.

The named types of deserts do not occupy large areas. In conditions of complex microrelief, depending on the degree of soil salinity, they form complexes. For example, at the bottom of basins and saucer-shaped depressions there is a kokpek desert, on their slopes - a solyanka desert, and in higher areas - wormwood deserts (Fig. 70). This complexity of vegetation cover is reflected in the legends of geobotanical maps.

In climatic terms, the southern deserts are quite different in temperature conditions and a pronounced spring-autumn maximum precipitation. This explains their significant difference and the wide variety of types.

Clay deserts of the southern variant are formed on piedmont loess plains (Kopet-Dag, Pamir-Alai, Tien Shan). Their vegetation cover is mesophytic in nature. In spring, a continuous turf of grass forms, which can be compared to a meadow. The most typical plants are bulbous ephemera: sedge, bulbous bluegrass, which form a dense, albeit low (20 cm) turf. Projective coverage reaches 80-100%. In spring, the ephemeral desert is used as pasture. In summer, all ephemerals die off and the soil surface becomes very dry.

Sandy deserts (Karakum, Kyzylkum, Muyunkum, Balkhash sands, etc.) have the greatest diversity of plant associations. There is a wide variety of life forms here, including ephemerals, shrubs and trees.

This is largely explained by the properties of sands, in which a favorable water regime is created (permeability, poor capillarity, ability to condense moisture). In the sandy desert at a depth of 100-150 cm There is a constant moisture horizon, which in spring is supplemented by a “hanging horizon.” Among the unfavorable environmental factors on sands is their mobility. Plants, as an adaptation for growing on moving sands, form deep-reaching adventitious roots.

The distribution of plant associations depends on the degree of sand fixation. Tall grass dominates on mobile dunes and dune chains Celine(up to 1 m), juzgun, sand acacia- low trees (up to 6 feet) with a characteristic “weeping” shape (Fig. 71).

In areas where ridged and hummocky sands develop, gnarled bushes are widespread white saxaul(up to 2-3 m). His distinctive feature is the summer shedding of branches. Other shrubs include juzgun and tree-like solyanka. Under the canopy of white saxaul, a grass cover of ephemerals and ephemeroids develops.

Saline deserts are usually confined to river terraces (Amu Darya, Ili, etc. rivers), sea coasts And deep depressions where highly saline soils are developed. They are characterized by a peculiar solyanka (halophytic) vegetation, among which succulent plants predominate. The most typical plants are: sarsazan – semi-shrub with a fleshy stem (sparse thickets of sarsazan occupy large areas on the coast of the Caspian Sea), succulent solyanka(tamarix) - plants whose leaves are covered with a salt crust, and sulfur wormwood.

On slightly saline soils, associations are common black saxaul- leafless tree-like solyanka, reaching a height of 5-9 m. Dense thickets of black saxaul are common in the Balkhash region, in the lower reaches of the Amu Darya, etc. Saxaul is a good fuel, which is slightly inferior in calorific value to some types of coal.

The desert type of vegetation on the globe occupies significant areas. In Eurasia, outside the USSR, there are vast deserts that form in subtropical and tropical climates (Tar, Registan, Rub El Khali, Syrian, Gobi Desert, Alashan, etc.). These are predominantly mountainous deserts, which are characterized by the development of thorny cushion-shaped shrubs (astragalus), succulents, and wormwood.

Large areas (up to 40%) are occupied by desert in Africa (Sahara, Kalahari, etc.). The vegetation of the Sahara approaches to some extent the deserts of Central Asia. In sandy areas, shrubs (camel thorn, acacia) and grasses (related to seline) are common. Significant areas are also occupied by rocky desert (“gammada”), which is characterized by lichens that form a continuous crust on the stones and rare subshrubs. The deserts of South Africa are characterized by the dominance of succulents, which are distinguished by an abundance of species: aloe, milkweed (Karoo Desert).

In the sandy Kalahari Desert, cereals predominate, and acacia is the dominant tree species.

The Namib Desert (the Orange River basin) is most distinctive, where special forms of succulents dominate, which look like stones - "plant-stones" A very peculiar endemic relict plant Velvichia(obviously a representative of the Mesozoic flora). The lifespan of Velvichia is more than 100 years. Its woody stem is up to 1.5 in diameter m rises to a height of no more than 20 cm(Fig. 72).

The deserts of North America are unique: along with the indicated types (saltwort, black wormwood, etc.)

spreading creosote bush desert (Colorado plateau, California coast). Mexican highland deserts at altitudes 1000-2250 m above sea level are the center of education cactus flora. This area contains up to 500 species of cacti, Opuntia, agaves, and tree-like yuccas (Fig. 73). Giant cacti in the desert are combined with thorny bushes (mimosa, creosote bush, etc.). The vegetation cover of the Mexican desert is very sparse.

The deserts of South America and Central Australia are saline plains and plateaus, abundant in sand and salt marshes. The plant background in them is formed by halophytic shrubs, succulents and herbs. Specifically Australian are shrub deserts with a predominance acacia and shrubby eucalyptus trees Vast sandy spaces are occupied by the formation of hard and prickly grasses (spinifex), growing on loose sand and stones (Western Australia).

Subtropical shrub-woody vegetation.Moistureny sub rainforests typical for areas of subtropical climate. This type of forest is common in eastern Asia, Central and South America and other areas and is represented by evergreen trees and shrubs. The dominant species in hard-leaved forests are laurel, plane tree, oak, boxwood. Ferns and mosses are abundant, often growing as epiphytes. The forests of Florida, Chile and Patagonia are dominated by evergreen beech.

A variety of this formation are evergreen hard-leaved forests and shrubs, typical for the countries

The Mediterranean, as well as California, southwestern Australia, South Africa (Cape Region), South America (Patagonia). The life forms of hard-leaved forests are very unique. Plants have xerophilic adaptations: hard leaves twig-like stems covered with resinous secretions. The dominant species in Mediterranean forests are stone And cork oak. The forests have an undergrowth of evergreen shrubs, such as myrtle And heather.

In Southern Europe, North Africa and the countries of Asia Minor, evergreen forests are beginning to be dominated by groves of pine pine and Lebanese cedar.

Hard-leaved forests of the subtropical zone are everywhere combined with thickets of various tall shrubs, which in the Mediterranean are called maquis. The maquis formation is characterized by strawberry tree, myrtle, and tree-like heather. In thickets of low evergreen shrubs called gariga, Shrubby oak, thyme, rosemary, gorse, etc. predominate (southern France). In North Africa and southern Spain, the gariga is represented by a dwarf palm. The hard-leaved eucalyptus forests of southern Australia are very distinctive, with evergreen undergrowth and bush thickets (scrab) of various types of acacias, bushy eucalyptus, etc.

Moist tropical (rain) forests. This type of forest formations is becoming widespread in the area equatorial climate. Forests occupy vast areas in Africa (the Congo and Niger river basins), Central and South America (the Amazon river basin) South-East Asia. Tropical rainforests stand out among all other forest formations with a wide variety of species. The trees are dominated by tree ferns, different types of ficus palm trees(coconut, oilseed, wine) rubber plants(Hevea brasiliensis).

The structure of tropical forests is the most complex. The number of tiers in them reaches 4-5. Tall trees (up to 60 m and above), with characteristic plank-shaped roots. The shade of the forest is maximum and only 1/150 of the incoming light reaches the soil surface. It should also be noted that there is less diversity in the types of grass cover, where spore-bearing plants predominate: ferns, mosses. Another characteristic feature tropical forests are abundant lianas and epiphytes(Fig. 74). The distribution of such life forms is explained by the large shade of the tropical forest. The most common: palm vines (up to 300 m), vines from the family Philodendron, pepper, vanilla, etc. Epiphytes are herbaceous species from the fern and orchid families, as well as mosses and algae.

A very characteristic formation of tropical rainforests is mangrove vegetation, widespread in the tidal zone of bays and lagoons of the northern and eastern coasts of South America, western Africa, Hindustan, etc. Mangrove vegetation consists of thickets of evergreen shrubs. The participation of trees in them is small. In terms of species, this formation is extremely monotonous (rhizophora and some palm species predominate). This is explained by the specific environmental conditions, since the crowns of trees rise out of the water during high tide, and during low tide the trunks, stilted and breathing roots are exposed. This root system is a kind of adaptation for transmitting oxygen during coastal flooding. Mangrove plants also have features characteristic of halophytic plants (Fig. 75).

In the region of the equatorial monsoon climate, a special type of deciduous (winter-green) tropical rainforests develops (Indochina, Hindustan, Sunda Islands). The forests are similar to tropical ones, but during periods of drought the trees shed their leaves. These forests differ in the nature of the tree stand. Included mixed forests Forest-forming species are valuable tree species (sandalwood, rosewood), bamboo, palm trees. There are many flowering shrubs and herbs in the forests. Also characteristic are lianas and epiphytes that lose their foliage during dry periods.

With increasing dryness in the tropical zone, winter-green tropical rainforests are replaced by dry xerophilous forests and thorny bushes. This formation occupies large areas in Africa (Rhodesia, Angola, Somalia),

Argentina, northern Australia. Xerophilous forests are stunted and sparse. They are dominated by leafless trees and shrubs such as acacia, palms, intertwined with vines. The undergrowth is dominated by thorny bushes. The xerophilous forests of Brazil are unique "caatinga" with many specific species: cacti, including tree-like ones, trees from the bombasaceae family, which have swollen barrel-shaped trunks with a diameter of several meters (Fig. 76). The distribution of these formations can be seen on the map of the world's vegetation.

This is a woody-herbaceous type of vegetation, which is transitional from tropical forests to tropical deserts. Savannahs are becoming widespread in the southern and central Africa(basins of the Niger and Upper Nile rivers), South America (Brazil, Orinoco river basin) Australia.

In conditions of severe aridity of the tropical climate, evergreen trees in savannas have hard, pubescent leaves that are shed during the dry season. Another feature is the umbrella shape of the crown as a device for strong winds Trees in the savanna are scattered in small groups. The main representatives are umbrella-shaped acacia And baobab - giant tree reaching a height of up to 25 m and having a diameter of up to 9 m(can reach an age of 5000 years) (Fig. 77). In Australian savannas, trees are dominated by eucalyptus trees, in the savannas of South America, “llanos” are varieties of palm trees. The grass cover of savannas is dominated by tall xerophytic, rigid-stemmed grasses (such as bearded grass).

Swamp vegetation. Swamps develop in different climatic zones - from equatorial to subarctic. They are especially characteristic of the forest zone of temperate climates.

Swamps are characterized by hygrophilic plants growing in conditions of excessive moisture and experiencing the influence of “physiological dryness”. When plants die, peat accumulates.

Modern classification of swamps is based on the identification types(formations) by the following signs: 1) position in the relief, 2) moisture and nutrition conditions, 3) prevailing plant associations.

The most common type is lowland swamps. They form on the bottoms of valleys of streams, ravines, gullies and are characteristic of all natural zones. The moistening of the swamps is associated with the close occurrence of mineralized groundwater. The grass cover of lowland bogs is dominated by green mosses, various sedges and grasses. In older bogs, birch, alder and willows appear. This type of bog is characterized by weak peat (the thickness of the peat layer does not exceed 1-1.5 m).

A variety of grass and hypno-grass swamps are tall-grass swamps with thickets of reeds, reeds, cattails, widespread in floodplains and lake basins in the forest, forest-steppe and steppe subzones of the European part of the USSR, Siberia and the Far East.

Raised bogs have specific features. They form on flat watersheds and occupy vast areas of the forest zone (for example, the West Siberian and Pechora lowlands, Polesie). Moistening of raised bogs is associated exclusively with precipitation and in conditions of flattened relief

becomes excessively stagnant. The surface of the bog acquires a convex profile due to the uneven growth of peat. The excess of the central part of the swamp over the periphery reaches 3-4 m. During the development of the swamp, a complex microrelief is formed on its surface, represented by a combination of small ridges and depressions (see Fig. 82).

The ecological conditions of the raised bog are very unique. Plants adapt to growing in an environment depleted in mineral nutrition, especially nitrogen compounds. Common in high bogs sphagnum mosses and associated marsh species: cotton grass, wild rosemary, Cassandra, heather, cranberry etc. The peculiarity of their life forms is that they have adventitious roots and a moving growth point. The vegetation of the raised bog (Fig. 78) is also adapted to tolerate “physiological dryness”.

The shrub plants of the raised bog have narrow leathery leaves with a waxy coating and a woody stem. Sedges, cotton grass, etc., having narrow, hard leaves, also acquired a specific appearance. The most common tree species found in raised bogs is pine And birch, less commonly cedar and larch. The trees in the swamp are severely depressed and stunted.

The named plant dominants for raised bogs (trees, shrubs, mosses, etc.) form certain associations, depending on environmental conditions. The following pattern emerges in their distribution: in the central part of the raised bog, pine-sphagnum association, towards the periphery of the flywheel in places where the ridge-hollow complex develops, it is replaced by pine-shrub, on the edge of the swamp

is spreading pine-cotton grass association (the nature of the distribution of associations in the raised bog and their location in plan, see Fig. 79).

Raised bogs have a large practical significance. Their peat layer often reaches a thickness of 6-10 m. Peat is used as a fuel raw material, fertilizer and for the production of a number of chemicals.

Raised bogs are common in North America (mainly in the northeast). Here the swamps are similar in nature to European ones, but larch predominates among the tree species. In South America, sphagnum bogs are found in the Andes and on the island of Tierra del Fuego.

Transitional swamps are mixed in nature and form on terraces or concave slopes of interfluves. The vegetation cover of such bogs combines the features of lowland and raised bogs and is characterized by a predominant distribution sphagnum-cotton grass-sedge associations.

The process of development of wetlands is very complex. The death and accumulation of plant debris in the swamp is essentially related to its water regime, since the growth of the peat layer reduces the influx of groundwater. This, in turn, entails a change in ecology and corresponding marsh associations. The types of swamps mentioned above can be considered as certain stages this development. Lowland sedge-grass bogs of ground moisture are replaced by transitional sphagnum-sedge bogs of mixed nutrition. Raised bogs of exclusively atmospheric nutrition represent the final stage of bog development, at which the tendency for peat to grow in height appears.

The outlined diagram gives the most general idea of the development of swamps. At the same time, the reasons causing waterlogging are extremely diverse. During the development of spruce and pine formations, waterlogging is facilitated by the development of moss cover from cuckoo flax and sphagnum. Forest burnt areas and clearings often become swamped. And finally, swamps arise on the site of lakes and river oxbows, which are populated by wetland vegetation. Let's look at this process in general terms.

Lake waterlogging most often occurs through overgrowth. With gentle banks and a gradual increase in depth, aquatic vegetation is located in the form belts in the following sequence: 1) in the deepest places a belt of green algae stands out (at a depth of more than 6 m); 2) a belt of flowering plants immersed in water (hornwort, pondweed); 3) a belt of broad-leaved pondweeds with wide floating leaves and inflorescences on the surface of the water (at a depth of 4- 5 m); 4) belt of water lilies at a depth of 2-3 m(water lily); 5) belt of reeds up to 2 m(reed, reed, horsetail); 6) belt of large sedges at a depth of up to 0.7 m; 7) belt of small sedges (Fig. 80).

Each of the marked belts is not durable and is replaced by the neighboring one - less deep-sea. This is explained by the fact that deposited plant residues contribute to the shallowing of the reservoir. This is how associations consistently shift from the periphery to the center. Its last stage is the transformation of the lake into sedge bog.

Of all the listed marsh associations, the most widespread on the globe are reed swamps with a predominance of high reed thickets (up to 6-10 m). In African tropical swamps along the banks of rivers and lakes there are thickets of papyrus, reeds and reeds; in Indian swamps there are thickets of bamboo.

Meadow vegetation.Meadows are a herbaceous type of mesophilic vegetation that grows in conditions of moderate moisture in various natural zones of the globe (tundra, forest zone, tropical, etc.).

Based on their location, meadows can be divided into floodplain (flood) and watershed (dry) meadows. Floodplain meadows are of greatest interest as a type of plant formation. Their vegetation is formed on fertile soils under the influence of a long-term flood regime and the deposition of loose river sediments.

Floodplain meadows are characterized by a number of floristic features: predominance loose turf cereals(timothy grass, fescue, bluegrass, awnless bromegrass), legumes(clover, alfalfa, mouse peas) and forbs(meadow geranium, meadow cornflower, common cornflower and a number of others). The grassland of the meadows is of high quality and represents valuable hayfields!

On the floodplains of large rivers, which are distinguished by complex microrelief and varying moisture levels, a variety of environmental conditions are created. When crossing the floodplain from the river bed towards the slope, a complex ecological series.

In the elevated riverbed part of the floodplain, composed of sandy alluvium, the driest conditions are created. Here, the sparse grass cover is dominated by long-rhizome grasses (creeping wheatgrass, awnless bromegrass), and some steppe species are also found.

The central part of the floodplain is composed of clayey alluvium and has a high groundwater table. Loose turf grasses, legumes and flowering herbs with a closed herbage dominate here.

The character of the meadow changes dramatically in the near-terrace part of the floodplain. This low area of the floodplain at the foot of the slope turns out to be the most moist due to the stagnation of hollow waters and the release of springs. The near-terrace floodplain is often forested. The indigenous type of forest is alder with an undergrowth of black currant.

In wet meadows, turf grasses (for example, pike) and sedges predominate.

In the forest zone there are also dry meadows that form on watersheds. Unlike floodplains, dry lands are of secondary origin, as they arise on the site of cut down or burned forests. Therefore, in their herbage, in addition to purely meadow mesophytes, there are elements of forest herbs and a well-developed moss cover. The productivity of such meadows is low.

In the steppe zone, watershed meadows form in depressions (estuaries, valleys, floods, etc.).

The vegetation of meadows is influenced by the type of vegetation (steppe, desert, etc.) among which it is formed. So, on the floodplain of the river. On the Oka River, which crosses the subzone of broad-leaved forests, there are steppe species; on the floodplain of the river. Teberdy - subalpine species. On the floodplains of the steppe rivers Sal and Manych, saltwort plants, characteristic of semi-deserts, predominate.

Alpine vegetation represents a special type of high-mountain low-grass meadows that are located above the upper border of the forest. The altitude position of alpine meadows varies depending on the geographical latitude of the mountains, the exposure of the slopes, and the degree of continental climate. For example, in the Alps and the western Caucasus, alpine meadows are located at altitudes of 2200-3000 m above sea level.

Alpine vegetation is similar to tundra vegetation in a number of ways: the predominance of perennial shrubs, cushion plants, etc. All this is an adaptation of alpine vegetation to the conditions of a short growing season with sharp temperature contrasts during the day. Under conditions of high light intensity, alpine plants acquire a short, squat shape and brightly colored flowers.

Alpine vegetation is divided into two altitudinal zones: the lower - subalpine, the upper - alpine meadows.

Subalpine meadows are most widespread in the mountains of Central Asia and the Caucasus. Their vegetation is distinguished by its extraordinary diversity and brightness. The grass cover is dominated by grasses and flowering herbs (geraniums, scabiosa, bluebells, alpine poppies, forget-me-nots, anemones, asters and many others). This type of herbal phytocenosis is characterized by complex tiers and high species richness. The subalpine meadows of the western Caucasus are characterized by the development tall grass, reaching a height of up to 2 m and more (bellflower, hogweed, elecampane, columbine). There are also thickets of Caucasian rhododendron, juniper, and willow.

Alpine meadows replaced by subalpine ones at altitudes above 3000 m. The grass cover of the Tien Shan meadows is dominated by mesophytic plants. Its important element is turf sedges(cobresia) with a very large and bright flower. The size and brightness of the colors of the flowers are a characteristic feature of alpine vegetation. Flowering herbs are similar to the subalpine belt, but appearance The vegetation of alpine meadows is distinguished by low grass stand. The leaves of herbs are arranged in the form of a rosette, often without a stem (chickweed, forget-me-nots, buttercups, alpine poppies and many others). There are many bulbous plants in the alpine meadow: tulips, hyacinths, mountain lilies etc. The alpine meadows of the Alps are distinguished by the nature of their vegetation by the abundance of species of tundra flora (for example, dryad); there are endemic species, such as edelweiss, primrose.

- Source-

Bogomolov, L.A. General Geography / L.A. Bogomolov [and others]. – M.: Nedra, 1971.- 232 p.

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1. Characteristics of phytocenoses

1.1 Forest phytocenosis

1.2 Meadow phytocenosis

1.3 Ruderal phytocenosis

1.4 Coastal aquatic phytocenosis

2. Geobotanical description of phytocenosis

1. Characteristics of phytocenoses

1.1 Forest phytocenosis

Forest phytocenosis is a forest community, a community of woody and non-woody vegetation, united by the history of formation, common development conditions and growing territory, and the unity of the circulation of substances. The forest community reaches its maximum degree of homogeneity within the geographic facies, where different plant species are in complex relationships with each other and with the ecotope. Depending on the ecotope, composition, ecology of tree species, and stage of development, simple (single-tier) and complex (multi-tiered) forest communities are distinguished.

The forest is a complex complex. The parts of this complex are in continuous interaction with each other and the environment. In the forest there is a variety of tree and shrub species, their combinations, a variety of ages of trees, the speed of their growth, ground cover, etc.

Thus, the main component of the forest as a whole - woody vegetation, when applied to a separate forest cenosis, receives more defined outlines. A relatively homogeneous collection of trees within these boundaries is called a forest stand. Young woody plants included in the forest phytocenosis, depending on their age and development, are usually called self-seeding or undergrowth in a natural forest. The youngest generation is the seedlings.

In a forest plantation, along with woody vegetation, there may also be shrubs. Forest phytocenosis is also characterized by ground cover. Consequently, a stand is a forest area that is homogeneous in terms of tree and shrub vegetation and living ground cover.

1.2 Meadow phytocenosis

Meadow - in a broad sense - is a type of zonal and intrazonal vegetation, characterized by the dominance of perennial herbaceous plants, mainly cereals and sedges, in conditions of sufficient or excessive moisture. A property common to all meadows is the presence of grass and turf, due to which the top layer of meadow soil is densely penetrated by the roots and rhizomes of herbaceous vegetation.

The external manifestation of the structure of meadow phytocenoses is the features of the vertical and horizontal placement in space and time of above-ground and underground plant organs. In the existing phytocenoses, the structure took shape as a result of a long selection of plants that have adapted to growing together in these conditions. It depends on the composition and quantitative ratio of the components of the phytocenosis, their growing conditions, the form and intensity of human impact.

Each stage of development of a phytocenosis corresponds to a special type of their structure, which is associated with the most important property of phytocenoses - their productivity. Individual types of phytocenoses differ greatly from each other in the volume of above-ground environment used by their components. The height of short grass stands is no more than 10-15 cm, tall grass stands are 150-200 cm. Short grass stands are typical mainly for pastures. The vertical profile of the grass stand varies seasonally from spring to summer and autumn.

Different types of meadows are characterized by different distribution of phytomass within the used volume of the environment. The most obvious manifestation of the vertical structure is the distribution of mass in layers (along the horizons) from 0 and further in height.

Typically, the first tier consists of grasses and the tallest species of forbs, the second tier is dominated by low species of legumes and forbs, the third tier is represented by a group of small herb species and rosettes. In lowland (waterlogged) and floodplain meadows, a layer of ground mosses and lichens is often pronounced.

In anthropogenically disturbed grass stands, the typically formed layered structure is also disrupted.

In meadow communities, especially multispecies and polydominant ones, more or less pronounced horizontal heterogeneity of the grass stand is always observed (patches of clover, strawberries, golden cinquefoil, etc.). In geobotany, this phenomenon is called mosaic or microgrouping.

Mosaicism in meadow phytocenoses arises as a result of the uneven distribution of individuals of certain species. And each species, even its age groups, are specific in the vertical and horizontal placement of their aboveground and underground organs. The uneven distribution of species within a phytocenosis is also due to randomness in the dispersion of seeds (bulbs, rhizomes), the establishment of seedlings, the heterogeneity of the ecotope, the influence of plants on each other, the characteristics of vegetative propagation, and the influence of animals and humans.

The boundaries between individual types of mosaics cannot always be clearly drawn. Often, the horizontal division of phytocenoses is determined not by one, but by several reasons. Episodic mosaic, along with phytogenic, is the most common. It is especially clearly manifested in the distribution of some species (angelica, hogweed) in places where they are massively seeded (under haystacks, near generative individuals), spots with a predominance of these species appear. Their power and participation in the creation of phytomass initially increases and then decreases due to the massive death of individuals as a result of the completion of the life cycle.

In meadows (as opposed to forests), fine-contour mosaic patterns are common. Meadows are also characterized by the movement of microgroups in space: disappearance in some places and appearance in others. Mosaic patterns are widespread, represented by various stages of vegetation restoration after disturbances caused by deviations from average weather conditions, animals, human activities, etc.

1.3 Ruderal phytocenosis

Ruderal plants are plants growing near buildings, in wastelands, landfills, in forest belts, along transportation routes, and in other secondary habitats. As a rule, ruderal plants are nitrophils (plants that grow abundantly and well only on soils sufficiently rich in assimilable nitrogen compounds). They often have various devices that protect them from destruction by animals and humans (thorns, burning hairs, toxic substances, etc.). Among the ruderal plants there are many valuable medicinal (dandelion, common tansy, motherwort, great plantain, horse sorrel, etc.), melliferous (medicinal and white sweet clover, narrow-leaved fireweed, etc.) and forage (awnless brome, creeping clover, wheatgrass creeping, etc.) plants. Communities (ruderal vegetation) formed by species of ruderal plants, often developing in places completely devoid of ground cover, give rise to restorative successions.

1.4 Coastal aquatic phytocenosis

forest ruderal phytocenosis vegetation

The floristic composition of coastal aquatic vegetation depends on the different environmental conditions of water bodies: the chemical composition of water, the characteristics of the soil composing the bottom and banks, the presence and speed of currents, and pollution of water bodies with organic and toxic substances.

The origin of the reservoir is important in determining the composition of phytocenoses. Thus, floodplain lake-type reservoirs, located in similar natural conditions and characterized by similar hydrological characteristics, have a macrophyte flora similar in composition.

The species composition of plants inhabiting the coastal zone of reservoirs and the aquatic environment is quite diverse. Based on their connection with the aquatic environment and way of life, three groups of plants are distinguished: true aquatic plants, or hydrophytes (floating and submerged); air-water plants (helophytes); coastal aquatic plants (hygrophytes).

2. Geobotanical description of phytocenosis

Area№ 1

5 * 5 meters.

June 11, 2013

Habitat:

Ufa, Foresters Park of Bashkiria

Type of phytocenosis: Forest

Projective soil cover 60%.

Crown density 95%.

Tiering:

1st tier Heart-shaped linden lat. Tnlia cordbta family Tiliaceae;

2nd tier Norway maple Acer platanoides Sapindбceae ;

3rd tier Rough elm Ъlmus glbbra Ulmaceae;

Mountain ash Surbus aucupbria Rosaceae;

4th tier Warty euonymus Euonymus verrucosa Celasfraceae;

Norway maple Acer platanoides Sapindбceae.

Herbaceous layer.

Forest chin Lathyrus sylvestris Fabacea;

Dandelion officinalis Tarbxacum officinble.

Area№ 2

Plot 5 * 5 meters.

June 11, 2013

Habitat:

Type of phytocenosis: Forest.

Projective soil cover 80%.

Crown density 60%.

Tiering:

1 tier Rough elm Ъlmus glbbra Ulmaceae;

2nd tier Norway maple Acer platanoides Sapindбceae;

3rd tier Rowan Surbus aucupbria Rosaceae;

English oak Quйrcus rubur Fagaceae.

Herbaceous layer.

Common thistle Cirsium vulgare Asteraceae;

Primulbceae

Stinging nettle Urtнca diуica Urticaceae;

Forest chin Lathyrus sylvestris Fabacea;

Fragrant bedstraw Galium odoratum Rubiaceae;

Bladder sedge Carex vesicaria Cyperaceae;

Urban gravilate Gthum urbbnum Rosaceae;

Dandelion officinalis Tarbxacum officinble Asteraceae;

Site No. 3.

Plot 2*2 meters.

June 11, 2013

Habitat:

Ufa, Foresters Park of Bashkiria.

Type of phytocenosis: meadow

Grass layer:

· Mouse peas Vncia crbcca LegumesFabaceae;

· Cumin Cbrum cbrvi Apiaceae;

· Buttercup acrid Ranúnculus bcris Ranunculaceae;

· Veronica dubravnaya Veronica chamaedrys Plantaginaceae;

· Chickweed Stellaria Holostea L. Caryophyllbceae;

· Ordinary cuff Alchemilla vulgaris Rosaceae;

Meadow bluegrass Poa pratthnsis Poaceae;

· Bonfire without bones Bromus inermis Pobceae;

· Meadow foxtail Alopecurus pratensis Poaceae;

· Clover Trifolium pratthnse Fabaceae;

· Creeping clover Trifolium repensMoths;

· Green strawberries Fragbria virndis Pink.

Site No. 4

Plot 2*2 meters.

Habitat:

Ufa, Foresters Park of Bashkiria.

Type of phytocenosis: spruce forest

Projective soil cover 2%.

Tiering:

1st tier Norway spruce Pnceabbies Pinaceae;

2nd tier Norway maple Acer platanoides L Sapindбceae;

3rd tier Norway maple Acer platanoides L Sapindбceae.

Herbaceous layer.

Geranibceae;

Dandelion officinalis Tarbxacum officinble Asteraceae.

Site No. 5

Plot 2*2 meters.

Habitat:

Projective soil coverage 100%.

White tar Silthne latifatlia Caryophyllbceae;

Timofey grass Phleum pratense Pobceae;

· Umbrella hawkweed Hieracium umbellatum L Asteraceae;

· High wormwood Artemisia vulgaris L. Asteraceae;

· Common cornflower Leucanthemum vulgare Asteraceae;

· Wild lettuce Lactura scariolaAsteraceae;

Soft bedstraw Galium mollugo Rubiaceae;

· Potentilla erecta Potentnlla erecta Rosaceae;

Field bindweed Convolvulus arvensis L. Convolvulaceae;

· Chamomile, odorless Tripleurospermum inodorum Asteræceae;

Field jarutka Thlbspi arvеnse Brassicaceae;

Violet tricolor Vnola trncolor Violbcea;

· Common bruise Ychium vulgbre Boraginaceae;

Common toadflax Linaria vulgaris Crophulariaceae;

· Ikotnik gray-green Bertеroa incбna Brassicaceae;

· Plantain lanceolate Plantbgo lanceolbta Plantaginaceae;

Velcro spread out Lappula squarrosa, Boraginaceae;

· Wormwood Artemnsia vulgbris Asteraceae;

· Thistle leaves Cirsium heterophyllum Asteraceae.

Site No. 6

Plot 2*2 meters.

Habitat:

Ufa, Kirov district, base of the slope, monument to Salavat Yulaev.

Type of phytocenosis: ruderal community

Projective soil coverage 100%.

Timothy grass Phleum pratense Pobceae;

· Artemisia vulgaris L. Asteraceae;

· Wild lettuce Lactura scariola Asteraceae;

· Soft bedstraw Galium mollugo Rubiaceae;

· Potentilla erecta Rosaceae;

· Salsify Tragopogon pratensis Asteraceae;

· Elm variegated Coronilla varia Fabaceae ;

· Meadowsweet Filipеndula ulmbria Rosaceae;

· Burnet Sanguisurba officinblis Rosaceae;

· Common bruise Chium vulgbre Boraginaceae;

· Gray-green hickory Bertеroa incбna Brassicaceae;

· Artemisia vulgbris Asteraceae;

· Thistle Cirsium heterophyllum Asteraceae.

Summary table of species and families

Families


Linden cordate lat. Tnlia cordbta

Norway maple Acer platanoides

Rough elm blmus glbbra

Burnet Sanguisurba officinblis
Meadowsweet Filipundula ulmbria
Potentilla erecta erecta
Common mountain ash Surbus aucupbria
Common cuff Alchemilla vulgaris
Green strawberry Fragbria virнdis
City gravilate Gйum urbbnum

Euonymus verrucosa

Cirsium heterophyllum
Common wormwood Artemnsia vulgbris
Chamomile Tripleurospermum inodorum
Meadow salsify Tragopogon pratensis
Wild lettuce Lactura scariola
Dandelion Tarabxacum officinble
Common cornflower Leucanthemum vulgare
Artemisia vulgaris
Umbrella hawkweed Hieracium umbellatum
Common thistle Cirsium vulgare

Stinging nettle Urtнca diуica

Variegated Elm Coronilla varia
Mouse peas Vнcia crбcca
Red clover Trifolium pratіnse
Mouse peas. Vнcia crбcca
Creeping clover Trifolium repens
Forest chin Lathyrus sylvestris

Soft bedstraw Galium mollugo
Fragrant bedstraw Galium odoratum

Bladder sedge Carex vesicaria

Caraway seeds Cbrum cbrvi

Ranunculus bcris

Lanceolate plantain Plantbgo lanceolbta
Veronica chamaedrys
Caryophyllbceae
White tar Silеne latiуlia
Starwort Stellaria holostea

Meadow bluegrass Poa pratіnsis
Timothy grass Phleum pratense
Bromus inermis
Meadow foxtail Alopecurus pratensis

Norway spruce Pнcea bbies

Common stork Erudium cicutbrium

Loosestrife Lysimachia nummularia

Field bindweed Convolvulus arvensis

Ikotnik gray-green Bertеroa incбna
Field lily Thlbspi arvеnse

Tricolor violet Vнola trнcolor

Common bruise Jchium vulgbre
Velcro splayed Lappula squarrosa

Common toadflax Linaria vulgaris

English oak Quйrcus rubur

conclusions

We discovered and analyzed 52 species from 24 families. The average number of species in families is 3. Thus, the following families are classified as leading:

Asteraceae

Thistle leaves Cirsium heterophyllum, wormwood Artemnsia vulgbris, odorless chamomile Tripleurospermum inodorum, meadow salsify Tragopogon pratensis, wild lettuce Lactura scariola, dandelion officinalis Tarbxacum officinble, common cornflower Leucanthemum vulgare, high wormwood Artemisia vulgaris, Umbrella hawksbill Hieracium umbellatum, common thistle Cirsium vulgare.

Rosaceae

Burnet plant Sanguisurba officinblis, meadowsweet Filipеndula ulmbria, Potentilla erecta Potentnlla erecta, mountain ash Surbus aucupria, ordinary cuff Alchemilla vulgaris, green strawberries Fragbria virнdis, urban gravity Gйum urbbnum.

Fabacea

Vyazel multi-colored Coronilla varia, red clover Trifolium pratіnse, mouse peas Vнcia crбcca, creeping clover Trifolium repens, forest rank Lathyrus sylvestris.

Poaceae

Meadow bluegrass Poa pratеnsis, timothy grass Phleum pratense, the fire is boneless Bromus inermis, meadow foxtail Alopecurus pratensis.

Conclusions on phytocenoses.

In forest phytocenosis No. 1, the dominant species were cordate linden. Tnlia cordbta and Norway maple Acer platanoides.

In forest phytocenosis No. 2, rough elm Ъlmus glbbra and Norway maple Acer platanoides.

In the meadow phytocenosis, the dominant species were caraway seeds Cbrum cbrvi, meadow bluegrass Poa pratеnsis, the fire is boneless Bromus inermis, acrid buttercup Ranúnculus bcris.

In the spruce forest, the dominant species was the common spruce Pнcea bbies. Grass cover was sparse, with percentage soil cover less than 5%.

General conclusion.

In forest communities, vegetation was represented more by woody forms, such as heart-shaped linden Tnlia cordbta, Norway maple Acer platanoides, rough elm Ъlmus glbbra, common mountain ash Sуrbus aucupрia, pedunculate oak Quйrcus rуbur. The diversity of herbaceous vegetation was not so great compared to the vegetation of meadows.

In meadow communities, the dominant families were Poaceae And Fabacea.

In ruderal communities, the dominant family was Asteraceae, represented by species: thistle Cirsium heterophyllum, wormwood Artemnsia vulgbris, odorless chamomile Tripleurospermum inodorum, meadow salsify Tragopogon pratensis, wild lettuce Lactura scariola, dandelion officinalis Tarbxacum officinble, common cornflower Leucanthemum vulgare, high wormwood Artemisia vulgaris, Umbrella hawksbill Hieracium umbellatum.

Thus, we can conclude that each phytocenosis is characterized by certain families. There are also species whose presence is typical for all studied phytocenoses, for example the species Dandelion officinalis Tarbxacum officinble.

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