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Main types of phytocenoses. Description of forest phytocenoses. Quantitative relationships between species

The phytocenosis is characterized by:

certain species composition;
structure, or otherwise, the features of the placement of components in space and time;
conditions of existence.

Species composition of phytocenosis. The established phytocenosis has its own physiognomy and certain characteristics. The most important feature phytocenosisstated floristic composition- a set of plant species included in a phytocenosis. The number of species included in the phytocenosis may vary. Phytocenoses consisting of one plant species are very rare in nature. Single-species phytocenoses formed by lower plants are usually designated by the word “colony”. In the case when one type of higher plant, a “thicket,” takes part in the formation of a phytocenosis, next to the word “thicket” is placed the name of the higher plant that is part of the phytocenosis (nettle thickets, raspberry thickets, etc.).

In nature, there are predominantly complex phytocenoses, which include not only higher plants, but also lower plants. The total number of species found in the phytocenosis over the entire occupied area depends on the conditions of existence (habitat conditions) of the phytocenosis and the history of its development. The size of the area occupied by the phytocenosis is also of considerable importance. The number of species registered on the registration site located within the described phytocenosis gives an idea of its species richness and species diversity.

Phytocenosis (from the Greek φυτóν - “plant” and κοινός - “general”) is a plant community that exists within the same biotope. Characterized by relative homogeneity of species composition, a certain structure and system of relationships between plants and each other external environment. Phytocenoses are the object of study of the science of phytocenology (geobotany).

Phytocenosis is part of the biocenosis along with zoocenosis and microbiocenosis. The biocenosis, in turn, in combination with the conditions of the abiotic environment (ecotope) forms a biogeocenosis. Phytocenosis is the central, leading element of biogeocenosis, as it transforms the primary ecotope into a biotope, creating a habitat for other organisms, and is also the first link in the cycle of substances and energy. The properties of soils, microclimate, the composition of the animal world, such characteristics of biogeocenosis as biomass, bioproductivity, etc., depend on vegetation. In turn, the elements of phytocenosis are cenopopulations of plants - collections of individuals of the same species within the boundaries of phytocenoses.

The layering was first described by the Austrian scientist L. Kerner in 1863. In the spruce forest, he distinguished: the tree layer, the fern layer and the moss layer. Then the Swedish scientist Gult identified 7 tiers in the forests of northern Finland:

top woody,
lower woody,
undergrowth,
top grass,
medium herbal,
lower grass,
ground

Vertical structure has two polar options, connected by smooth transitions: tiered and vertical continuum. Thus, layering is not a mandatory characteristic, but different heights of plants are a widespread phenomenon.

Tiering allows species of different ecological qualities to coexist in a community, makes the habitat more ecologically capacious, and creates a large number of ecological niches, especially in relation to the light regime.

In the series single-tiered - two-tiered - multi-tiered - imperfectly layered (vertical-continuous) communities, an increase in floristic richness is observed.

The consistent use of the concept of tiering has a number of theoretical difficulties due to the fact that:

not all communities are vertically discrete;
it is unclear whether tiers are layers or elements “inserted” into each other;
It is unclear where to include vines, epiphytes, and undergrowth.

To overcome these difficulties, Yu. P. Byalovich formulated the idea of a biogeocenotic horizon - a vertically isolated and vertically indivisible structural part of the biogeocenosis. From top to bottom, it is homogeneous in the composition of biogeocenotic components, in their interrelationships, the transformations of matter and energy occurring in it, and in these same respects it differs from the neighboring, higher and lower located, biogeocenotic horizons.

The vertical parts of plant communities, accordingly, form phytocenotic horizons. Each of them is characterized not only by the composition of autotrophic plant species, but also by a certain composition of the organs of these plants. With this approach to the analysis of vertical structure, controversial issues disappear, including where to classify lianas, epiphytes or undergrowth.

Horizontal structure

Most plant communities are characterized by heterogeneity of horizontal composition. This phenomenon is called mosaic phytocenoses. Mosaic elements are most often called microgroups, although a number of researchers have proposed their own terms - microphytocenoses, coenoquants, coenocells. The concept of a parcel stands apart. - element of horizontal heterogeneity of biogeocenosis.

The uneven distribution of species is due to a number of reasons. There are types of mosaics based on their origin:

Phytogenic mosaic caused by competition, changes in the phytoenvironment or the specific life forms of plants (the ability for vegetative propagation and the formation of clones).
Edaphotopic mosaic associated with the heterogeneity of the edaphotope (irregularities in the microrelief, different drainage, heterogeneity of soils and litter, their thickness, humus content, granulometric composition, etc.).
Zoogenic mosaic caused by the influence of animals, both direct and indirect (mediated) - eating, trampling, laying excrement, and the activity of burrowing animals.
Anthropogenic mosaic is associated with human activity - trampling due to recreational load, grazing of farm animals, mowing of grass and cutting down of forest plant communities, resource harvesting, etc.
Exogenous mosaic, caused by external abiotic environmental factors - the influence of wind, water, etc.

Mosaic - special case horizontal heterogeneity of vegetation cover. When studying the horizontal heterogeneity of vegetation in a region, researchers distinguish between two concepts, two circles of phenomena - mosaic and complexity.

In contrast to mosaicism, which characterizes intracenotic horizontal heterogeneity, complexity is the horizontal heterogeneity of plant cover at the supraphytocenotic level. It manifests itself in the natural alternation of individual phytocenoses or their fragments within the same landscape.

The complexity of the vegetation cover is determined by the micro-or mesorelief, which serves as a kind of redistributor of the load of the main environmental factors and thereby differentiates the landscape into habitats with different ecological regimes.

There are complexes and combinations of communities. Complexes - communities, related friend with a friend genetically, i.e. being successive stages of one succession process.

Sometimes they talk about the sinusial structure of plant communities, thus highlighting the special structural elements of the phytocenosis - synusia.

Sinusia- these are structural parts of a plant community, limited in space or time (i.e., occupying a certain ecological niche) and differing from one another in morphological, floristic, ecological and phytocenotic terms.

The synusia of spring forest ephemeroids, the “pseudo-meadow” synusia in deserts, or the synusia of annuals in some types of vegetation are well distinguished in deciduous forests.

Composition, structure and structure of phytocenoses

Phytocenology (from Phytocenosis and ... Logia - the study of phytocenoses (plant communities); a section of geobotany (See Geobotany) (often identified with geobotany) and biogeocenology (See Biogeocenology). At the end of the 19th century in a number of countries in As a result of the study of their vegetation cover, an idea arose about the regular combinations of plants growing together - plant communities, the need for their study as a special object was substantiated and the tasks of the scientific discipline that studies plant communities, called phytotopography (I.P. Norlin), florology (Polish botanist) were formulated Yu. Pachosky, 1891), later phytosociology (Pachosky, 1896; Soviet botanist P. N. Krylov, 1898), and then F. (German geobotanist H. Gamay, 1918; Soviet botanist L. G. Ramensky, 1924 The latter name has become widespread in the USSR and some European countries; in other countries the terms phytosociology and plant ecology are used.

Phytocenosis's tasks include the study of the floristic, ecobiomorphic (see Ecobiomorph) and cenopopulation composition of phytocenoses, the relationships between plants, the structure, ecology, dynamics, distribution, classification and history of the emergence of phytocenoses. F.'s development went in several directions. The founder of the geographical direction was A. Humboldt, who established at the beginning of the 19th century. basic patterns of vegetation distribution depending on climate; The results of the research of Humboldt and his followers were summarized by him. plant geographer A. Grisebach, who published in 1872 “Vegetation of the Globe according to its climatic distribution” (Russian translation 1874-1877). For the development of this direction big influence contributed by the work of V.V. Dokuchaev. Owl research geobotanists G.N. Vysotsky, A.Ya. Gordyagin, B.A. Keller and others moved in the direction of studying vegetation taking into account soil conditions. The ecologization of the study of vegetation was largely influenced by the “Textbook of Environmental Geography of Plants” dates. botany by I. Warming (Russian translation in 1901 and 1902). phytocenology phytocenosis science

In the 19th century significant material was accumulated on the structure (tiered, mosaic) of phytocenoses (Austrian botany I. Lorenz, 1858, and A. Kerner, 1863; Finnish botanist R. Hult, 1881, etc.) and the study of successions began, the doctrine of which especially developed in the USA (F. Clemente). In the 20th century after the 3rd International Botanical Congress (1910), at which the association was accepted as an elementary taxonomic unit (See Association), schools were formed that differed in the methods of studying phytocenoses and identifying associations. The dominant idea was that the vegetation cover was composed of discrete units well delimited from each other. The idea of continuity of vegetation cover and the absence of sharp boundaries between phytocenoses (if growing conditions change gradually) also emerged. The doctrine of the continuity of vegetation cover and the associated idea of the ecological individuality of plant species were substantiated independently of each other by Ramensky (1910, 1924), Amer. scientist G. Gleason (1926), Italian G. Negri (1914), French. scientist F. Lenoble (1926). This direction did not receive recognition at first, but starting in the 40s. began to develop successfully in the USA (J. Curtis, R. Whittaker, etc.), and then in other countries. Proponents of the continuity of vegetation cover substantiated methods of ordination - identifying types of phytocenoses based on their location in a coordinate system characterizing changes in certain environmental conditions (moisture, soil fertility, etc.). Ordination is also successfully used by supporters of discreteness of phytocenoses, for example V.N. Sukachev, who distributed the groups of forest associations he identified into ecological-phytocenotic series.

Ecological studies of the vegetation of our planet are summarized in the monograph by G. Walter “Vegetation of the Globe. Ecological and physiological characteristics" (Russian translation 1968-1975). In the USSR, and then in the USA, the idea arose of the possibility of using vegetation as an indicator of plant growth conditions (B. Keller, 1912, F. Clements, 1920). Subsequently, methods were developed for compiling environmental scales and using them to indicate the environment based on the composition of vegetation (Ramensky, 1938; Ramensky et al., 1956; G. Ellenberg, 1950, 1952, 1974, etc.). It also turned out to be possible to use vegetation as an indicator in geological and hydrogeological research (Soviet botanist S.V. Viktorov and others).

The biological direction of studying phytocenoses was substantiated by the Swiss. botanist O. P. Decandol (1820, 1832). It was developed after the publication of Charles Darwin’s “The Origin of Species” (1859). The followers of Decandolle and Darwin believed that the composition, structure and change of plant communities are determined not only by climate and soil conditions, but also by the relationships between plants. In the 70-80s. 19th century This direction was developed in the works of Russian. scientists N.F. Levakovsky and S.I. Korzhinsky, and then (in the 20th century) in the works of G.F. Morozov and V.N. Sukachev. To study the relationships between plants in phytocenoses, V.N. Sukachev and A.P. Shennikov used an experiment; That. experimental F. arose.

Since the 40s. 20th century based on the presentation of Sukachev and English. botany A. Tansley on biogeocenoses (ecosystems) a new direction arose in the study of phytocenoses as components of more complex bioinert systems. Stationary complex studies began to develop (with the participation, in addition to botanists, zoologists, microbiologists, soil scientists, climatologists) in which they studied the amount of organic matter and energy produced by a phytocenosis (primary production), the role of phytocenoses in energy flows and the transformation of substances, consortium (See Consortium ), relationships of autotrophic plants with each other and with heterotrophic organisms, etc. As a result of these studies, the species composition of phytocenoses (including vascular plants, mosses, lichens, algae, fungi, bacteria and actinomycetes), the composition of cenopopulations, structure, dynamics, including including changes caused by human activity, determine the conditions that ensure maximum production of phytocenoses, including the creation of artificial highly productive phytocenoses. In F. they are increasingly used mathematical methods, including mathematical modeling, a statistical and mathematical study of phytocenoses arose.

A great contribution to the development of F. was made by the Sovs. botanists. They studied the vegetation of one sixth of the Earth's territory, developed theoretical problems and methods for studying phytocenoses: V. N. Sukachev, G. F. Morozov and A. Kayander - in forest F., B. N. Gorodkov, V. B. Sochava, V. N. Andreev, B. A. Tikhomirov - tundra vegetation, L. G. Ramensky and A. P. Shennikov - meadows, V. V. Alekhin, E. M. Lavrenko - steppes, etc.

F. - the theoretical basis of protection, correct use and increasing the productivity of natural and man-made phytocenoses. The results of phytocenological studies are used for planning and rational use of forest, forage and other lands, in geological and hydrogeological studies, etc.

Research on Physics is carried out in many countries in botanical, ecological, geographical, as well as specialized scientific institutions and relevant universities. F.'s problems are highlighted. in botanical, ecological and general biological journals: in the USSR - in the “Botanical Journal” (since 1916), “Bulletin of the Moscow Society of Naturalists. Department of Biology" (since 1829), "Ecology" (since 1970), "Forest Science" (since 1967) and "Journal of General Biology" (since 1940), and abroad - "Journal of Ecology" (L. - Camb., from 1913), “Ecology” (N.Y., from 1920), “Ecological Monographs” (from 1931), “Vegetatio” (The Hague, from 1948), “Folia geobotanica et phytotaxonomica” (Prague, from 1966), “Phytocoenologia” (V., since 1973). In the USSR, a series of works by the BIN of the USSR Academy of Sciences devoted to geobotany is also published: “Geobotany” (since 1932), “Geobotanical Mapping” (edited by V. B. Sochava, since 1963). 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, microgroups, etc.) you can quite easily and accurately draw boundaries; you can plot them on a plan, calculate the area, and then, for example, calculate the resources of useful plants or food resources of animals. 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 of biological systems are closely interrelated at the coenotic level: species composition, configuration and placement structural elements in space are a condition for their functioning, that is, life activity and production of 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 called mosaic.

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. Characterized by the greatest species saturation mixed forests, 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; ecological and biological groups are also distinguished here - one-, two-, perennials, 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 the 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 as part of the 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 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.

Bibliography

Voronov A.G. Geobotany. Textbook Manual for high fur boots and peds. Inst. Ed. 2nd. M.: Higher. school, 1973. 384 p.

Ipatov V.S., Kirikova L.A. Phytocenology: Textbook. St. Petersburg: Leningrad State University Publishing House, 1997. 316 p.

Stepanovskikh A.S. General ecology: Textbook for universities. M.: UNITY, 2001. 510 p.

Sukachev V.N. Fundamentals of forest typology and biogeocenology. Favorite tr. L.: Nauka, 1972. T. 3. 543 p.

Program and methodology of biogeocenological research / Study of forest biogeocenoses / M.: Nauka, 1974. P. 281-317.

Tsvetkov V.F. Forest biogeocenosis. Arkhangelsk, 2003. 2nd ed. 267 p.

Questions

1. Identification of the boundaries of biogeocenosis.

2. Biogeocenosis-forming role of phytocenosis in the landscape.

3. Definition of the concept of “phytocenosis”.

4. Main signs of phytocenosis.

5. Minimum size of the area for identifying a phytocenosis.

6. About the boundaries of phytocenosis. The concept of the continuum of vegetation cover.

7. Differences in the concepts of “phytocenosis”, “association” and “plant community”.

To control biogeocenotic processes, you need to know the laws to which they are subject. These patterns are studied by a number of sciences: meteorology, climatology, geology, soil science, hydrology, various departments of botany and zoology, microbiology, etc. Biogeocenology synthesizes the results of the listed sciences from a certain angle, paying primary attention to the interactions of the components of biogeocenoses with each other and revealing general patterns , governing these interactions. This area of knowledge studies biogeocenosis as a whole and explores its inherent processes.

1. Identification of the boundaries of biogeocenosis

It is known that only by establishing the exact boundaries of the biogeocenosis is it possible to analyze it. And the more specifically and accurately the biogeocenosis is limited in space, the more objectivity is possible quantitative characteristic processes and phenomena occurring in it.

The difficulty of accurately establishing these boundaries is well known; “... drawing boundaries between them is often conditional, and to a certain extent, subjective in nature...”. V.N. Sukachev wrote about this: “...Different biogeocenoses have, of course, different vertical thickness, for example forest, steppe, desert, etc. However, as a rule, we can assume that the upper boundary of the biogeocenosis is located several meters above the vegetation cover, the lower part lies several meters below the soil surface..." (Fundamentals of forest biogeocenology, 1964: 32.

E. M. Lavrenko (1962) understands the boundaries of biogeocenoses in approximately the same way when identifying a part of the biosphere, which he called " phytosphere ".

The question arises, what criteria are most accessible when identifying biogeocenoses in nature?

1. You need to start with a relief analysis. Although relief, as is known, is not part of the components of biogeocenosis, it is a very important factor in its existence. For the first orientation in forest biogeocenoses during their identification and delimitation in nature, it can play a very important role. The description of biogeocenosis begins with it.

2. Within a homogeneous relief, the most indicative sign of the homogeneity of the biogeocenosis is the homogeneity of the soil and vegetation cover. Of these two indicators, it is especially suitable for identifying biogeocenoses. uniformity vegetation cover, thanks to its visibility. Therefore, when delimiting biogeocenoses in nature, it is advisable to use phytocenosis. The boundaries of each biogeocenosis are individually determined by the boundaries of the phytocenosis.

Visualization is a very important detail, but the main thing is that among the components of biogeocenosis, it is phytocenosis that plays the determining – biogeocenosis-forming, role.

2. Biogeocenosis-forming role of phytocenosis in the landscape

Phytocenosis is the main component, a key subsystem of biogeocenosis in all respects, in which the main processes of formation and transformation of what is the basis of life on the planet—organic matter—take place. It determines the spatial boundaries of the biogeocenosis, its structure and appearance, indoor climate, composition, abundance and distribution of animals, microorganisms, features and intensity of material and energy exchange of the entire biogeocenosis system.

Phytocenoses serve:
1) main receivers and transformers of solar energy,
2) the main suppliers of products in the biogeocenosis,
3) their structure objectively reflects all the processes occurring in the biogeocenosis,
4) at the same time, they are easily accessible for study directly in nature,
5) for them, over the course of several decades, effective field research methods and methods of office processing of factual materials have been developed and are being developed.

Based on the above, a detailed study of phytocenosis is an obligatory part of any biogeocenological study. The study of any natural system always begins with vegetation. Our lectures will focus on phytocenosis and methods for studying it. Moreover, many of the patterns characteristic of phytocenosis also apply to zoocenosis and microorganisms.

IN general form The study of phytocenoses comes down to solving the following most important questions:

Determination of the role of phytocenosis in the accumulation of organic matter and energy and the transformation of matter and energy into common system biogeocenosis (key question!).
Determination of the role of phytocenosis in the dynamics of biogeocenosis.
Determination of the nature and degree of impact of the phytocenosis on the remaining components of the biogeocenosis.
Accordingly, the determination of the influence of other components of the biogeocenosis on the properties, features and efficiency of the “work” of the phytocenosis.
Determination of the nature and degree of impact of the phytocenosis on neighboring biogeocenoses.
Determination of the form, methods and means of direct and indirect influence on the phytocenosis from human economic activity in order to increase the biological productivity of the biogeocenosis and enhance its other beneficial properties.

3. Definition of the concept of “phytocenosis”

The first definition of a plant community was given by G.F. Morozov (1904) for forest, and then extended by V.N. Sukachev (1908) for all plant communities. The term “phytocenosis” was used in 1915 by I.K. Pachosky for “pure thickets” (formed by one plant species), and for all communities – V.N. Sukachev (1917) and G. Gams (Gams, 1918).

Phytocenosis, like biogeocenosis, should be understood as a geographical phenomenon, namely, each terrestrial phytocenosis occupies a certain territory with its characteristic hydrological regime, microrelief, microclimate, and soils.

V.N. Sukachev (1956) very successfully defines phytocenosis: “... Phytocenosis, or plant community, is a collection of plants growing together on a homogeneous territory, characterized by a certain composition, structure, composition and relationships of plants both with each other and with environmental conditions. The nature of these relationships is determined, on the one hand, by the vital, otherwise, ecological properties of plants, on the other hand, by the properties of the habitat, i.e., the nature of the climate, soil and the influence of humans and animals..."

The structure and state of the phytocenosis well reflects both competition and mutual assistance of plants.

EXAMPLE. Broad-leaved linden with liana vegetation, hazel forb phytocenosis in the middle part of the north-north-east slope. exposure (elevations 250-300 m above sea level; slope steepness averages 15-20).
The tree stand consists of 2 tiers. It is characterized by a very high crown density - 0.97. The trees are closed with crowns and twilight reigns under their canopy. The first tier is formed by Mongolian oak, Amur and Manchurian lindens, Manchurian walnut, single old black birch and small-leaved maple trees.
Most linden trees are slender, full-tree trees with smooth trunks. Average taxation indicators of trees of the 1st tier: Dsr 18-20 cm, Nsr - 17-18 m. The well-defined second tier is dominated by linden - mostly younger than in the upper tier, and stunted trees, small-leaved maple. There is a slight admixture of mountain elm, Amur maakia, and heartleaf hornbeam; Dimorphant, pseudosiebold maple and small-carp are rare. In addition, the gadder and Maksimovich's euonymus "penetrate" into it, the bulk of individuals of which are concentrated in the undergrowth.
The continued existence of any forest is ensured by the regeneration of the species of the mother tree stand. Undergrowth in the amount of 8.6 thousand specimens per hectare is represented by all types of trees. Its species composition is dominated by small-leaved maple, in self-seeding there are single individuals of the dark coniferous species - whole-leaved fir (Abies holophylla). The distribution of undergrowth over the area is uniformly grouped (maple, linden, cod) and single individuals (elm, walnut, maakia, etc. ).
The undergrowth is dense, it is dominated by Manchurian hazel, mock orange and eleutherococcus are common, Maksimovich's currant and early-flowering honeysuckle are less common in large bushes, single euonymus large-winged and sparsely flowered, and green-barked maple. Viburnum Bureinskaya rarely grows in groups and, as a rule, along with it - single shoots of Amur barberry.
Due to the high density of tree and shrub layers, the grass stand is sparse. In addition to spring forest poppy, it is dominated by tuberous basilisk, sedges: Ussuri, returning, long-nosed, Bunge chickweed, Daurian bedstraw, and ferns. As in a tree stand, a grass stand can be divided into tiers. The upper one, up to 1 m high, is formed by species of large herbs growing everywhere: mountain peony, black cohosh, Dahurian and Amur angelica, pointed crow, red-flowered undergrowth, two-row lily; Asian Volzhanka and powerful cohosh are rare. Sometimes small, densely covered microgroups form medium-sized grasses (forbs), up to 0.5 m high - hairy smilacina, wintering horsetail, dead nettle, lily of the valley, and small grasses, no more than 0.25 m high: Ussuri skullcap, Franchet buttercup, bifolia, trigonotis rooting, adoxa muskus, meringia sideflower, Colin's violets, Siebold's hooffoot, Jeffersonia dubious, different types of corydalis.
In addition to the plants that form tiers, in the described phytocenosis one can also distinguish the so-called extra-tiered plants, for example actinidia vines, lemongrass, and grapes.
All types of herbs can be divided into groups according to seasonal development (some are spring ephemeroids (anemones, corydalis, adonis, lloidia, etc.), go through a development cycle within a month and are already in a dormant state in June. Others (two-row lily, sparkling lychnis, powerful cohosh, etc.) the culmination of development occurs in July, others (plectranthus, desmodium, saussurea, aconites) bloom and remain green in September), by origin (taiga forests, small-leaved, nemoral, meadow, etc.), by abundance (some of them are found in such significant quantities that they form a continuous cover, others are rare, and others are single).
Thus, in this forest, six aboveground tiers can be distinguished: two woody, one shrub (with undergrowth) and three herbaceous.
Having dug a trench in such a forest, one can also observe underground layering (though less pronounced than aboveground): the roots and rhizomes of grasses are located in shallower soil horizons, the roots of shrubs and trees are located in deeper ones. Thanks to underground layering, plants use different layers of soil to obtain moisture and nutrients.

Thus, the phytocenosis characterized by:

1. a certain species composition of the plants that form it,
2. their certain abundance,
3. a certain structure and
4. confined to a specific habitat.
4. Main signs of phytocenosis

Essential signs of phytocenosis - phytocenotic relationships (relationships between plants) and the presence phytocenotic environment.

The creation of a phytoenvironment is the first sign of a phytocenosis to appear, because the influence of plant organisms on the environment may already exist where there is no influence of plants on each other yet. PHYTOCOENOTIC ENVIRONMENT begins to form even at a time when individual plants, which appeared on an area previously devoid of or without a coherent plant cover, grow separately, without forming a continuous cover.

Already at the first stages of vegetation development, microclimate conditions change; dead plants are introduced into the soil or into the ground. chemical substances, and living plants extract others, the nature of the microrelief changes (for example, plumes of dust and sand particles are formed near plant stems), in a word, the environment is transformed by plants. Subsequently, through the interactions of plants, the phytocenosis increasingly changes the environment and creates its own phytoenvironment. Moreover, environmental conditions in different parts of the phytocenosis (on the soil surface, on the trunks and in the crowns of trees, at different heights above the soil surface, etc.) are not the same.

The presence of phytocenotic relationships is the most significant feature of a phytocenosis, but INTERACTION BETWEEN PLANTS begins somewhat later than the impact of plants on their habitat. It can only occur at a certain density of vegetation cover. However, it is very difficult to notice this moment when interaction between plants begins, since it does not always involve direct contact between organisms.

Therefore, phytocenoses should include various stages of development of vegetation, except for the very first moments of plant settlement in an area devoid of vegetation.

Another question is the degree of expression of the phytocenotic environment and the degree of expression of relationships between plants in phytocenoses. In some deserts and polar tundras, the vegetation cover is so sparse that it cannot be considered formed from phytocenoses. With such sparse cover, it is very difficult to determine the degree of influence of plant root systems on each other, and it is almost impossible with existing research methods to determine the degree of influence on the environment and on others. plant organisms microscopic plants - algae and bacteria, which can be very significant. Under such environmental conditions, probably, each area of long-term and, therefore, adapted to the environment vegetation cover should be divided into phytocenoses.

Since a phytocenosis is not every collection plant species, but only a completely natural combination, formed as a result of a long historical process and in connection with external conditions existence, then V.V. Alekhin and other representatives of the Moscow phytocenological school believe that the “ability to recover” or “the ability to relative recovery” is put forward as one of the obligatory characteristics of a community (Prozorovsky. 1956).

From this point of view, cultivated vegetation, groupings of plants settling in areas devoid of vegetation, as well as all those natural combinations of plants that are not restored after their disturbance or destruction cannot be considered phytocenoses.

Thus, it would be impossible to consider as phytocenoses not only secondary birch or aspen forests that appear in the place of primary ones after they are cut down, but also primary northern forests temperate zone, living in areas with shallow groundwater, since these forests do not renew after being cut down or burned, and the areas of cutting areas and burnt areas become swamped. Shrub communities (forest forests, sea buckthorn forests) that replaced tall-stemmed phytocenoses (oak forests, cedar-broadleaf trees) cannot be considered either.

It is unlikely that such a point of view can be considered correct. Indeed, in cultural communities, and in primary and secondary forests, and in pioneer groupings of plants (perhaps with the exception of the very initial stages of their existence), there are those features that constitute the essential features of a phytocenosis: the creation of a phytoenvironment and the presence of phytocenotic relationships.

There are two types of relationships between plants in the current phytocenosis:

1) competition with each other over the means of life or the struggle for existence in the broad sense as Charles Darwin understood it. On the one hand, this weakens the plants, but on the other hand, it forms the basis natural selection– the most important factor in speciation and, consequently, the process of evolution.

EXAMPLE. Differentiation and self-thinning of the forest stand with age or deterioration of growing conditions - the strongest survive. From tens of thousands of seedlings and self-seeding, less than 1% remains at the age of ripeness.

In the process of natural selection, the phytocenosis included species that are interconnected or dependent on each other. It includes not only flowering, gymnosperm, fern-like plants, mosses, horsetails, mosses, but also lower plant organisms: fungi, algae, bacteria, lichens.

What has been said about the role of natural selection in the formation of communities is true only for undisturbed, established natural phytocenoses. In phytocenoses developing in areas previously devoid of vegetation, at the first stages of development there is no direct influence of individual plants on each other and therefore the relationships between individual species are not yet expressed.

2) mutual assistance– plants in a phytocenosis have a beneficial effect on each other: shade-loving herbs live under the canopy of trees, which cannot grow or grow poorly in open places; tree trunks and bush branches serve as mechanical support for vines, on which epiphytes, not connected to the soil, in turn settle.

5. Minimum size of the area for identifying a phytocenosis

How to determine the minimum size of the area on which a phytocenosis can be distinguished?

Obviously, the smallest territory for identifying a phytocenosis should be of such dimensions that all the signs of the phytocenosis itself (species composition, structure, etc.), as well as all the main features of the soil, microclimate, surface microrelief, in a word, features of the phytoenvironment, can appear.

It goes without saying that for different phytocenoses the size of this smallest territory is not the same: the simpler the structure of the phytocenosis, the less its influence on the habitat, the smaller the size of the territory.

In the temperate zone they are smaller for meadows compared to forests. For temperate forests, they are smaller compared to tropical forests.

6. About the boundaries of phytocenosis. Concept of the land cover continuum

There may be sharp boundaries between phytocenoses, but more often the transitions are gradual and imperceptible. This causes difficulties in identifying phytocenoses. The gradual transition from one type of phytocenosis to another is a consequence of a gradual change in the ecological conditions of the habitat. If the changing values of any factor (for example, conditions of moisture, salinity, etc.) are plotted on a graph, then gradually changing combinations of plant species will correspond to them. Based on this, L.G. Ramensky developed the doctrine of continuity of vegetation cover(Moscow school of geobotany), or, as it is often called, the doctrine of continuum. As L.G. points out. Ramensky (1910, 1925, 1937, 1938), “...the ability of plants to form various combinations is truly inexhaustible...”, i.e. the number of associations is unlimited.

Many scientists, following this teaching, do not recognize the reality of the existence of phytocenoses. The question of identifying (on a graph and on the ground) the boundaries of a particular phytocenosis turns out, according to L.G. Ramensky, to some extent conditional and depends not only on the relationship of this phytocenosis with neighboring ones, but also on the “target setting, work”. In other words, the boundaries between two phytocenoses may be absent and may be drawn differently in different cases or by different researchers.

Currently, the doctrine of the continuity of vegetation cover has become widespread, especially in the works of American scientists: H. Gleason (Gleason, 1939), D. Curtis (1955, 1958), R. Whittaker (1953, 1956, 1960) , F. Egler (Egler, 1951, 1954), Polish researcher W. Matuszkiewicz (Matuszkievicz, 1948). The main idea of this teaching is the impossibility of fitting all the variety of combinations of plants with many different transitional groups into a limited number of associations. Proponents of this concept, as a rule, consider phytocenoses (associations, plant communities) to be conditional, abstract categories that do not exist in nature, although, as some of them believe, they are necessary from a practical or theoretical point of view.

In this regard, the question of the existence of sharp or gradual boundaries between phytocenoses becomes significant. L.G. Ramensky, T.A. Rabotnov (1967) and other continuum theorists believe that gradual, unclear boundaries are the rule, and sharp ones the exception.

Supporters of another doctrine (Leningrad school) - about the discreteness of vegetation cover, for example V.N. Sukachev, G. Durieu, in contrast to the view of L.G. Ramensky, they believe that, as a rule, the boundaries between associations are sharp, but sometimes smooth transitions are possible.

In fact, both theories have a right to exist. The nature of the boundaries between phytocenoses reflects the influence of edificatory plants on the environment. Smooth transitions from one cenosis to another are more often observed where the influence of edificators does not change the environment so much, for example in meadows, and sharp transitions are observed where one powerful edificator is replaced by another (for example, at the boundaries of forest areas formed by different tree species).

As B.A. pointed out. Bykov (1957), edificators, by their influence, largely determine the sharpness of boundaries even with a gradual change in habitat conditions. Therefore, “...the boundaries of plant associations are undoubtedly outlined in nature more sharply than the boundaries of habitats...” (Nitsenko, 1948).

7. Differences between the concepts of “phytocenosis”, “association” and “plant community”

For a long time, many scientists equated the terms “phytocenosis” and “plant community”, using them as synonyms. V.N. Sukachev repeatedly pointed out that the term “phytocenosis” (plant community) can be applied to specific areas of vegetation cover and to designate taxonomic units various ranks: associations, formations, vegetation types, etc.

Recently (Voronov, 1973), the term “phytocenosis” has been applied only to specific areas of vegetation that correspond to the above definition by V.N. Sukachev.

Association called the typological unit of phytocenoses. S.M. puts the same meaning into this term. Razumovsky (1981). In his interpretation, an association is an elementary unit of vegetation cover that unites areas with the same species of each layer and the same successional tendency. Drawing an analogy, we can say that phytocenosis and association relate to each other in the same way as a specific plant and the species of this plant.

EXAMPLE. Driving along the Vladivostok-Ussuriysk highway, we can say that almost all the forest vegetation on this section is represented by secondary oak forests. The areas of these forests are very similar to one another. The tree stand is oak with a single admixture of Dahurian birch. The undergrowth is fragmentary, represented by hazel and lespedeza. The ground cover includes forbs and sedges. However, despite the very high similarity, it is impossible to find even two areas with completely identical phytocenoses.

In other words, all these similar phytocenoses are of the same type, and together they represent one association, or one type of forest - sedge-forb oak forest.

Association is the first step in the system of taxonomic units of vegetation cover of various ranks. The subsequent steps are: group of associations, formation, group of formations, class of formations, type of vegetation; There are also intermediate categories.

Such an abundance of hierarchical levels gave rise to the need for a special term that could be applied to a taxonomic category of any rank; G. Duriez (Du-Rietz, 1936) proposed “plant community” as such a term. This concept is broader than “phytocenosis”. It does not have a specific volume. So, V.V. Alekhine (1950) writes that “... plant community... these are plant associations of both larger and smaller volumes, both forests in general and coniferous forests, and subdivisions of the latter, as well as this specific section of it...”

Thus, a plant community refers to any plant “collective” where plants are in certain relationships, without indicating its size and nature of organization. In this case, the plant community can be considered as a phenomenon of the joint social life of plants. This term was used in such a broad sense by V.V. Alekhine (1935, 1950, 1951)

Phytocenoses belonging to the same association are scattered. They usually border on phytocenoses belonging to other associations. Combinations of phytocenoses are usually found in the area, and they often differ quite noticeably from each other. This is due to differences in other natural ingredients, and as a result, different biogeocenoses, or so-called natural-territorial complexes, are formed. It is precisely such complexes that one usually has to deal with when using plant resources.

1. The structure of phytocenoses should be understood as:

a) the diversity of species in them and the ratio of numbers and biomass of all populations included in them;

b) ratio environmental groups plants that develop over a long period of time in certain climatic, soil and landscape conditions;

c) spatial arrangement of plants (and their parts) in the plant community;

e) a + b + c.

2. The structure of phytocenoses is determined by:

a) the composition and quantitative ratio of the components of plant communities;

b) plant growth conditions;

c) exposure to animal components;

d) the form and intensity of human impact;

e) a + b + c;

f) all answers are correct.

3. The structure of the phytocenosis gives an idea of:

a) the volume of the environment used by the community;

b) the characteristics of the contact of the plants included in its composition with the environment;

c) efficiency and completeness of use by the plant community natural resources;

d) all answers are correct.

4. The structure of the phytocenosis depends on:

a) ecobiomorphic composition of the plant community;

b) the number and vital state of vascular plant individuals belonging to the main growth forms (trees, shrubs, shrubs, herbs);

c) the presence and quantitative participation of mosses and lichens, protists, algae and macromycetes;

d) height and density of aboveground shoots of community components;

d) all answers are correct

5. The most important features of the structure of the phytocenosis are:

a) the degree of closure of the vegetation cover and the features of the vertical distribution of the leaf surface;

b) the presence of sufficiently differentiated tiers or, conversely, their absence;

c) homogeneity or heterogeneity of horizontal division;

d). a + b + c.

6. The vertical structure of phytocenoses has two polar options, connected by smooth transitions:

a) tiering;

b) phytocenotic horizons

c) vertical continuum;

7. The main factor determining the vertical distribution of plants is:

a) the amount of light that determines the temperature and humidity conditions in the different levels above the soil surface in biogeocenosis;

b) strict competitive relationships between different plant species and their consorts;

c) edaphic, or soil-ground, habitat conditions;

d) terrain

8. A universal synthetic characteristic of the vertical structure of any phytocenosis (both with tiers and with a vertical continuum) is:

a) inversion of vertical belts;

b) aggregation index;

c) leaf surface index;

d) homogeneity index;

e) index of phytocenotic plasticity.

a) the ratio of the surface area of the leaves to the surface area of the soil on which they are located;

b) the ratio of the total area of leaves of a phytocenosis (or its tier) to the area of the territory it occupies, expressed in m 2 / m 2, or ha / ha;

c) the ratio of the total area of leaves of plants of different tiers;

d) leaf surface area ratio various types plants.

10. The smallest value of the leaf surface index is typical for:

a) meadow phytocenoses;

b) open desert communities;

c) spruce forests;

d) mixed forests

11. Other things being equal, the leaf surface index in meadows increases:

a) from less acidic to more acidic soils;

b) from more acidic to less acidic soils;

c) from the beginning of the growing season to the period of culmination of grass development;

d) after each mowing and grass removal;

e) with increasing light intensity and applying complete mineral fertilizer (NPK)

f) b + c + d + d;

g) b + c + d;

h) a + c + d;

12. The formation of the underground part of phytocenoses is characterized by a decrease in the mass of plant organs from top to bottom. This has been established for such plant communities as:

a) meadow;

b) steppe;

c) deserted;

d) forest;

d) all answers are correct.

13. The mass of underground organs is usually several times (sometimes 10 or more) greater than the mass of above-ground organs in such communities as:

a) meadow;

b) subshrubs;

c) tundra;

d) desert;

d) all answers are correct.

14. To the main price elements of phytocenoses according to Kh.Kh. Track (1970) include:

b) phytocenotic horizons;

c) price cells;

d) microgroups.

15. An element of the vertical structure of phytocenoses, manifested in the case when the community is formed by life forms of plants contrasting in height, is:

a) price element;

b) sinusia;

d) cenotype;

e) phytocenotic horizon.

16. The tiers differ:

a) environmental conditions in the horizons to which the aboveground organs of the plants that form them are confined;

b) features of light and temperature conditions;

c) air humidity;

d). a + b + c + d.

17. There are several types of tiers (according to T.A. Rabotnov):

a) stable over the seasons and over the years (for example, tiers of evergreen trees, shrubs, shrubs, mosses, lichens);

b) existing all year round, but changing sharply from the growing season to the non-growing season (tiers formed by deciduous trees, shrubs, shrubs);

c) formed by herbs;

d) ephemeral, existing for a short time, formed by herbs (ephemera, ephemeroids), sometimes mosses;

e) are formed only in certain years, for example, a layer of annual grasses in those deserts where sufficient precipitation falls only in some years;

f) re-forming during the growing season due to the alienation of above-ground organs as a result of mowing or grazing;

and). a + b + c + d.

18. Tiered arrangement of plants:

a) allows species of different ecological qualities to coexist in a community;

b) makes the habitat more ecologically capacious;

c) creates a large number of ecological niches, especially in relation to the light regime;

d) reduces competition and ensures community sustainability;

d) all answers are correct.

19. In the row single-tiered – two-tiered – low-tiered – multi-tiered – imperfect-tiered (vertical-continuous) communities the following is observed:

a) increase in floristic richness;

b) decrease in floristic richness;

c) a clear correlation between the number of tiers and the number of species that make up the phytocenosis;

d) absence of a certain pattern.

20. In temperate zone forests, the following tiers are usually distinguished:

a) the first (upper) tier is formed by trees of the first size (pedunculate oak, heart-shaped linden, smooth elm, etc.)

b) second - trees of the second size (rowan, apple, pear, bird cherry, etc.);

c) the third tier is the undergrowth formed by shrubs (common hazel, brittle buckthorn, etc.)

d) the fourth tier consists of tall grasses(nettle, common nettle) and shrubs (bilberry);

e) the fifth tier is made of low grasses;

f) in the sixth tier - mosses and lichens;

g) all answers are correct.

21. Consistent use of the concept of tiering has a number of theoretical difficulties due to the fact that:

a) not all phytocenoses are vertically discrete;

b) it is unclear whether tiers are layers or elements “inserted” into each other;

c) it is unclear where to include undergrowth, vines, and epiphytes;

d) all answers are correct.

22. Division into tiers is absent in such types of phytocenoses as:

a) most herbal;

b) tropical rain forests;

c) certain types deciduous forests;

d) a + b + c.

23. The absence (or weak expression) of layers in herbaceous communities can be explained by:

a) the presence of only one life form;

b) small height of plants;

c) the presence of predominantly perennial grasses;

d) approximately the same illumination of all plant individuals, regardless of their height and environmental characteristics.

24. There is no underground layering:

a) in spruce forests;

b) in meadow phytocenoses;

c) on salt marshes and solonetzes;

d) in steppe and desert communities;

e) a + b + d;

g) all answers are correct.

25. Phytocenotic horizon is:

a) a vertically isolated and vertically undivided structural part of the biogeocenosis;

b) the vertical part of the plant community, characterized by a certain floristic composition and a certain composition of the organs of these plants;

c) artificial morphological division of the vegetation cover, in which (in contrast to tiered division 26. In forests of the temperate zone, the following phytocenotic horizons are usually distinguished, formed:

a) tree crowns;

b) under-crown part of trunks tall trees, as well as trees of smaller height, shrubs and corresponding consorts (for example, plants) are, as it were, cut vertically, forming horizontal layers;

d) all answers are correct.

lichens);

c) shrubs or herbs, which, in addition to herbs and shrubs, includes the lower parts of the trunks of trees and shrubs with their characteristic epiphytes;

d) mosses, lichens, creeping plants, including the lower parts of taller plants and their shoots;

d) all answers are correct.

27. When identifying phytocenotic horizons, such controversial issues that arise when delineating tiers, such as:

a) how many tiers does this or that phytocenosis include;

b) at what closeness of the above-ground organs of the corresponding plant species is the layer considered expressed or not expressed;

c) where to include vines, epiphytes, undergrowth;

d) all answers are correct.

28. Lianas and epiphytes are part of:

a) upper horizons;

b) lower horizons;

c) those horizons to which the parts of trees and shrubs that serve as their support belong;

29. Each phytocenotic horizon is characterized by:

a) a certain floristic composition;

b) the composition of the organs of these plants;

c) the degree to which the space is filled with these organs;

d) all answers are correct.

30. An area of vegetation cover within which boundaries cannot be drawn according to given characteristics and thresholds adopted to determine the boundary is called:

a) parcel;

b) price cell;

c) microgrouping;

d) tsenokvantom;

d) price element.

a) one life form;

b) united by individual topical and trophic competitive relationships;

c) one type;

d) different tiers.

32. The morphological expression of the price cell of woody vegetation is determined by:

a) age of the tree stand;

b) group placement of trees and forest stands;

c) the height of the tree stand and plants forming the undergrowth;

d) the vitality of plants.

33. The structural part of a phytocenosis, limited in space or time (occupying a certain ecological niche) and differing from other similar parts in morphological, floristic, ecological and phytocenotic terms, is called:

a) coenopopulation;

b) cenotype;

c) sinusia;

d) tsenokvantom.

34. The following can be considered as synusia:

a) each well-defined layer of forest phytocenoses;

b) a set of epiphytes, lianas, epiphytic lichens;

c) spring forest ephemeroids;

d) groups of annuals that exist in deserts only in years with abundant precipitation;

f) all answers are correct.

35. Among temporary sinuses there are:

a) seasonal;

b) daily allowance;

c) fluctuation;

d) demutational;

e) a + c + d;

e) a + b + c.

36. The most important signs of sinusia are the following:

a) synusia is formed by plants of one or more closely related life forms;

b) plants in the synusia are close together, closed in underground or aboveground parts;

c) ecological similarity of plants belonging to the same synusia;

d) morphological isolation, spatial expression;

e) certain interactions between plants, their influence on the environment and, as a consequence, the creation of their own eco-environment;

f) relative autonomy, expressed in the fact that synusias of the same type can exist with synusias of other types in different combinations;

g) a + c + d + f;

h) all answers are correct.

37. Synusia are:

a) a forest stand formed by spruce, pine or any other species;

b) cover of blueberry or heather;

c) a patch of hairy sedge in an oak forest;

d) mixed stand of spruce and fir;

e) a tree stand formed by a mixture of oak, maple, and ash;

f) cover of ephemeroids in an oak forest;

g) lichen carpet of bushy forms in a pine forest;

h) a + b + d + g;

i) all answers are correct.

38. Sinusia are characterized by the following functional features:

a) the plants included in the synusia have similarities in needs, cenotypic kinship, similarity in transforming the environment in a way favorable for themselves and their partners;

b) in synusia there is a single coenotic process;

c) coenotic and ecological selections take place in synusia;

d) all answers are correct.

39. An example of fluctuation sinusia is:

a) a group of spring ephemeroids, well limited in time from the synusias of grasses of the summer growing season, which differ from the spring ones in their species composition, structure, ecologically and cenotypically.

b) thickets of fireweed in burnt areas and clearings, existing for a short time;

c) a group of annual grasses that appear in some deserts in the years with big amount atmospheric precipitation;

d) synusia of creeping buttercup in flooded meadows during prolonged stagnation of spring floods.

40. Sinusial analysis of phytocenoses comes down to:

a) establishing the synusia that makes up the phytocenosis;

b) study of their species composition and structure;

c) studying the relationship between them and the environment;

e) a + b + c.

41. Sinusial analysis of plant communities helps to determine:

a) environmental conditions of the habitat;

b) complete use of environmental resources by the phytocenosis;

c) the ecological niche occupied by each specific synusia;

d) a + b + c.

42. Most plant communities are characterized by heterogeneity of horizontal composition; this phenomenon is called:

a) intermittency;

b) mosaic;

c) continuum;

d) emergence.

43. Within phytocenoses, special structural formations can be distinguished, called:

a) microgroups, or microphytocenoses;

b) price elements;

c) price quants;

d) price cells;

e) a + c + d;

f) all answers are correct.

44. The horizontal division of phytocenoses - mosaic - is expressed by the presence in the biocenosis of various microgroups that differ:

a) species composition;

b) quantitative ratio of different species;

c) closeness;

d) productivity and other characteristics and properties;

d) all answers are correct.

45. The following variants of mosaic phytocenoses are distinguished (Rabotnov, 1984; Mirkin, 1985):

A) regeneration mosaics– heterogeneity of phytocenosis associated with the renewal process;

b) clone mosaics– heterogeneity of phytocenosis associated with vegetative propagation of plants;

V) phytoenvironmental mosaics– heterogeneity of the phytocenosis associated with changes in the environment by one of the species and the response of other species to this change;

G) allelopathic mosaics caused by the release of strong-smelling aromatic substances by some plant species;

d) zoogenic mosaics are formed as a result of exposure to animals;

f) a + b + c + d + e.

46. The uneven distribution of plant species within the plant community and the associated patchiness is due to a number of reasons. Based on their origin, the following types of mosaic are distinguished:

A) phytogenic caused by competition, changes in the phytoenvironment or characteristics of plant life forms;

b) edaphotopic, associated with the heterogeneity of the edaphotope (irregularities in the microrelief, different drainage, soil heterogeneity, etc.);

V) zoogenic caused by direct or indirect influence of animals (trampling, eating, laying excrement);

G) anthropogenic, the reason for which is human economic activity (grazing farm animals, selective cutting of trees in the forest, fire pits, etc.)

d) exogenous, caused by the action of abiotic environmental factors - the influence of wind, water, etc.

f) a + b + d;

g) all answers are correct.

47. Mosaicism in the forest is least pronounced where:

a) the tree layer is formed by one species;

b) the tree layer is formed by species that are similar in their influence on the environment;

c) the tree layer contains different ecobiomorphs (coniferous and soft-leaved tree species);

d) there are no and poorly developed shrubs;

e) growing conditions for most species are unfavorable;

f) a + c + d;

g) a + b + d + e;

h) all answers are correct.

48. Mosaic pattern is most pronounced:

a) in floodplain meadows;

b) in mixed coniferous-deciduous forests;

c) in raised bogs;

e) in coniferous forests.

49. The reasons for phytogenic mosaic in coniferous-deciduous forests, represented mainly by spruce and linden, may be the following:

a) lower illumination and temperature under the spruce than under the linden;

b) 2.0 – 2.5 times less precipitation in the form of rain penetrates under the crowns of spruce trees than under the crowns of deciduous trees;

c) rainwater flowing from tree crowns has a more acidic reaction than water flowing under the linden tree;

d) under the spruce a soil is formed with a poorly developed humus horizon and a well-defined podzolic horizon;

e) a + b + d;

e). a + b + c + d.

50. Characteristic features The mosaics of many types of phytocenosis are:

a) stability in time and space;

b) dynamism;

c) replacement of some microgroups by others over time;

d) change due to passage life cycle plants;

e) b + c + d.

51. The English scientist Watt (1947) distinguished the following phases of age-related variability of plants and, accordingly, variability of microgroups:

a) pioneer;

b) invasive;

c) construction phase;

d) maturity;

e) degeneration;

f) a + c + d + d;

g) a + b + d + e.

52. The following types of horizontal composition of phytocenoses are distinguished (according to A. P. Shennikov):

a) separate;

b) separate-group;

c) closed group;

d) diffuse;

e) mosaic;

c) a + b + c + d;

g) a + b + c + d + e.

53. The mosaic phytocenosis, with all the diversity of composition and division into fragments, is united:

a) dominance of one of the tiers;

b) the absence of dominance of any tier;

c) small sizes of mosaic elements that mutually influence each other;

d) significant sizes of mosaic elements.

54. In contrast to mosaicism, which characterizes intracenotic horizontal heterogeneity, complexity is the horizontal heterogeneity of vegetation cover at the supraphytocenotic level. The complex consists not of fragments, but of different phytocenoses, which:

a) occupy large areas;

b) are highly dependent on each other;

c) depend less on each other;

d) not connected by a common tier;

e) alternate mosaically in space;

f) a + c + d + d;

g) a + b + d + e.

55. The transition zone between phytocenoses (contact phytocenosis) is called:

a) ecoid;

b) ecocline;

c) ecotone;

d) ecotope.

56. Ecotone can be:

a) narrow or wide;

b) sharp or absent;

c) diffuse or bordered;

d) mosaic-island;

f) all answers are correct.

57. The absence of a pronounced transition strip between phytocenoses is most often due to:

a) a sharp change in growing conditions (for example, on a steep slope, in a clearly defined depression, etc.);

b) human impact (for example, a meadow clearing in the middle of a forest that appeared at the site of deforestation);

c) the environment-forming influence of dominant species in one of the phytocenoses bordering each other (for example, spruce, sphagnum mosses, etc.);

e) a + b + c.

CHAPTER 5

Dynamics of phytocenoses.

1. The dynamics of phytocenoses and vegetation in general (syndynamics) mean:

a) reversible changes in plant communities within a day, a year and from year to year;

b) changes in phytocenoses with increasing age of edificator individuals;

c) various options for gradual directed changes that can be caused by both internal and external factors and, as a rule, are irreversible;

d) long-term cyclical changes caused, for example, by regularly recurring forest fires;

e) a + b + d;

f) all answers are correct.

2. The main forms of vegetation dynamics are:

a) disturbances of phytocenoses;

b) succession of phytocenoses;

c) evolution of phytocenoses;

d) a + b + c.

3. The following types of variability of phytocenoses are distinguished:

a) daily allowance;

b) seasonal;

c) multi-annual;

d) age;

d) all answers are correct

4. Unlike shifts, the variability of phytocenoses is characterized the following features:

a) variability of floristic composition;

b) it takes place against the background of an unchanged floristic composition;

c) the observed changes are reversible;

d) irreversibility of changes;

e) the observed changes are undirected;

f) a + g + d;

g) b + c + d.

5. Daily variability of phytocenoses appears only during the period:

a) growing season;

b) the beginning of flowering;

c) flowering;

d) formation of seeds and fruits;

d) fruit ripening

6. During the day, such vital functions of plants change as:

a) photosynthesis;

b) intensity of absorption of water and mineral elements;

c) transpiration;

d) release of metabolites, which, in turn, leads to fluctuations in the composition of the air within phytocenoses (CO 2 content, specific secretions, etc.);

d) all answers are correct.

7. Seasonal variability of phytocenoses is due to changes throughout the year:

a) light and temperature conditions;

b) general climate;

c) hydrological regime;

d) phytoclimate;

e) all answers are correct

8. The stages of phenological development of phytocenoses differ from one another:

a) characteristics of the biotope (phytoenvironment);

b) the intensity of plant growth and reproduction;

c) the degree and methods of influence of some components on others;

d) structural features and floristic composition;

e) aspect (appearance) and economic use;

g) all answers are correct

9. Phenological spectra give an idea of:

a) floristic composition of the studied phytocenosis;

b) changes in the participation of individual species in phytocenoses during the season or year;

c) the composition of life forms;

d) the beginning and end of the growing season, as well as the duration of the growing season;

e) timing of the onset and duration of individual phases of the growing season;

f) changes in the rhythm of seasonal vegetation depending on the characteristics of the environment in the studied cenoses;

g) all answers are correct.

10. Changes that occur in phytocenoses by year or period of year, associated with unequal meteorological and hydrological conditions of individual years, are called:

a) succession;

b) transformation;

c) fluctuation;

d) demutation.

11. According to the causes of occurrence, the following types of fluctuations are distinguished:

A) ecotopic, associated with differences in meteo-, hydro- and other conditions of ecotopes from year to year;

b) anthropogenic, caused by differences in the form and intensity of human impact on the phytocenosis;

V) zoogenic, caused by differences in the effects of herbivores and burrowing animals;

G) phytocyclic, associated with the characteristics of the life cycle of certain plant species and (or) with their uneven seed or vegetative propagation over the years;

f) all answers are correct.

12. Ecotopic fluctuations are the least pronounced:

a) in the forests;

b) in the meadows;

c) in the steppes;

d) in sphagnum bogs.

13. The most significant fluctuation changes are observed in adult individuals of herbaceous plants, which are manifested:

a) in the number and power of shoots;

b) in their vitality;

c) in the ratio of individuals in the generative and vegetative state;

d) a + b + c;

14. According to the degree of severity, fluctuations are divided into several types:

a) hidden;

b) oscillatory (oscillations);

c) cyclical;

d) digression-demutation;

e) all answers are correct

15. Hidden fluctuations occur:

a) in monodominant grass cenoses;

b) in phytocenoses formed by species with perennial above-ground organs (woody plants, mosses, lichens);

c) in complex floristically rich multi-layered forest communities

16. Oscillations are described for:

b) coniferous forests;

c) mixed forests;

17. Examples of oscillation can be:

a) change of dominants in some types of meadows in wet and dry years;

b) seasonal changes in the floristic and ecobiomorphic composition of phytocenoses;

c) fluctuations with alternating changes over the years at the level of subdominants;

d) seasonal dynamics of productivity

18. Digression-demutation fluctuations are characterized by:

a) a change in dominants and subdominants in floodplain meadows as a result of a sharp deviation from the average meteorological and hydrological conditions for these biogeocenoses;

b) changes in the ecobiomorphic composition of phytocenoses;

c) severe disturbance of phytocenoses with their subsequent demutation - a return to a state close to the original one, as soon as the reason that caused the change ceased to operate;

G) seasonal changes in the quantitative ratio of the components of phytocenoses

19. Factors causing digression of phytocenoses may be:

a) severe prolonged drought;

b) prolonged stagnation of water on the soil surface in spring;

c) the formation of a thick ice crust;

d) little snow harsh winter;

e) mass reproduction of phytophages;

f) all answers are correct.

20. The most significant disturbances of phytocenoses occur if the adverse effects of meteorological and hydrological conditions, as well as zoo components:

a) is especially pronounced during the growing season of plants;

b) lasts no more than two years (seasons), as a result of which there is no strong oppression or mass extinction of dominant species;

c) continues for several years or several seasons in a row, which leads to mass death or severe suppression of the main components of phytocenoses;

d) lead to a violation vegetative propagation plants of the lower tiers.

21. The duration of the demutation period is determined:

a) the intensity of the community disturbance;

b) the degree of preservation of plants that were dominant before the disturbance;

c) growing conditions during the demutation period;

d) all answers are correct.

22. Examples of digression-demutation fluctuations can be:

a) the replacement of cereal grass stands with creeping grasses, which occurs under the influence of spring stagnation of hollow waters, with the subsequent return of the predominance of cereals;

b) transformation into creeping cenoses with a predominance of various types of cereals;

c) the ability of individuals of many plant species, under the influence of drought, to enter a dormant state, and after the end of the drought, the ability to quickly return phytocenoses to their original state;

d) all answers are correct.

23. The practical significance of studying fluctuations in phytocenoses of forage lands (meadows, steppes, etc.), aimed at their effective use and improvement, is determined by the fact that, year by year:

a) their productivity and the quality of the feed obtained from them fluctuates;

b) the timing and even the possibility or feasibility of using forage lands change;

c) the effectiveness of methods for improving forage areas changes

(irrigation, fertilization, overseeding, etc.);

d) all answers are correct.

24. Primary productivity of biogeocenoses is the creation of organic matter:

a) autotrophic organisms (photosynthetic green plants);

b) heterotrophs (bacteria, fungi, animals);

c) all living organisms of the ecosystem

25. When studying biological products, it is necessary to determine the mass:

a) only living plants;

b) only living plants and litter;

c) living plants, litter, dead trunks of trees and shrubs - waste, as well as dead underground organs;

d) all answers are correct.

26. Biomass is:

a) the amount of living matter expressed in mass per unit area or volume of habitat (g/m2, kg/ha, g/m3, etc.);

b) the increase in primary production per unit of space per unit of time (for example, g/m 2 per day);

c) the total mass of individuals of a species, group of species or community of organisms, expressed in units of mass of dry or wet matter per unit area or volume of habitat (kg/ha, g/m2, g/m3)

27. The biomass of living matter in terrestrial ecosystems is represented by:

a) plants, animals, fungi and bacteria in approximately equal proportions;

b) mainly animals and microorganisms;

c) more than 95% by plants.

28. The highest functional activity, i.e. the rate of increase in biomass per unit time, is characteristic of:

a) marine phytoplankton;

b) a complex of plants of rivers and lakes;

c) vegetation of meadows, steppes, arable land;

d) woody vegetation.

29. Gross primary production (gross production) is the amount of organic matter:

a) retained in plants after part of it is used for respiration;

b) created by plants during the process of photosynthesis;

c) created by all living organisms that are part of a particular biocenosis.

30. Vegetation production is determined by:

a) temperature conditions and humidity;

b) provision of plants with mineral nutrition elements;

c) the absence of limiting factors, for example, salinity;

d) all answers are correct

31. Succession is called:

a) repeated variability of phytocenoses over years or periods of years;

b) seasonal variability of phytocenoses due to sharp fluctuations temperature regime throughout the growing season;

c) irreversible and directional, i.e., a change in vegetation cover occurring in a certain direction, manifested in the replacement of some phytocenoses by others

32. The main difference between the evolution of phytocenoses and their succession is:

a) during evolution, the composition and structure of phytocenoses remain practically unchanged (the composition may even be simplified), and as a result of succession, new phytocenoses always arise;

b) in the course of evolution, new phytocenoses are formed, and in the case of succession, phytocenoses do not arise, but combinations of species that already existed in the area are formed;

c) succession is always a “repetition of the past”, and in the course of evolution new, previously absent combinations of plant populations arise.

33. The main differences between succession and fluctuations are:

a) irreversibility of changes;

b) continuity of succession;

c) direction of changes;

d) all answers are correct.

34. Based on their origin, there are two main types of successions:

a) permanent;

b) temporary;

c) primary;

d) fluctuation;

d) secondary.

35. Primary successions begin with the emergence of phytocenoses on:

a) rocks;

c) sediments of water flows;

d) cooled lava after a volcanic eruption;

e) clearings in the forest;

f) a + c + d;

g) all answers are correct.

36. The following processes occurring in the case of primary succession are distinguished:

a) formation of a substrate;

b) migration of plants, their establishment and aggregation;

c) plant interaction;

d) changes in the environment by plants;

e) change of phytocenoses;

f) a + b + d + d;

g) all answers are correct.

37. Migration (distribution) of plants is carried out by transferring from one place to another:

a) seeds, spores and other germs;

b) whole plants;

c) vegetative organs of plants;

d) all answers are correct.

38. The survival of plants arising from rudiments brought from outside is possible if:

a) they find themselves in favorable ecotopic conditions;

b) seedlings develop with a homeostasis composition of consorts;

c) they have the ability to reproduce by seeds;

d) all answers are correct.

39. The period from the initial phases of succession to the achievement of a stable state of phytocenoses varies depending on:

a) climate;

b) initial substrate;

c) the possibility of diasporas entering;

e) a + b + c.

40. Primary successions proceed faster:

a) in a warm place humid climate;

b) in cold, dry climatic regions;

c) on rocky ground;

d) on fine-grained substrates

41. Available data on the rate of primary succession indicate that (check the correct answer):

a) in the Alps they take 100 years, in Japan - in 700 years, in the Arctic - more than 7000 years, on the poor quartz sands of the dunes along the coast of Lake Michigan (USA) - in about 5000 years;

b) in the Alps - for 100 years, in the USA (oak forests on the dunes of the Michigan coast) - for 700 years, in Japan - for 1000 years, in the Arctic - for more than 5000 years;

c) in the Alps - for 100 years, in Japan - for 700 years, in the USA (on the dunes of the coast of Michigan) - for 1000 years, in the Arctic - for more than 5000 years;

42. Secondary successions differ significantly from primary ones in that they begin in the conditions of already formed soil, which contains:

a) numerous microorganisms (bacteria, protists, fungi);

b) spores and seeds of plants, their resting underground organs;

c) soil mesofauna;

d) mineral and organic substances;

d) all answers are correct.

43. Secondary successions:

a) occur much faster (about 5-10 times) than the primary ones;

b) pass much slower than the primary ones;

c) in terms of speed of origin, they practically do not differ from the primary ones.

44. For reasons of change in biogeocenoses, the following types of successions are distinguished:

a) syngenetic (syngenesis);

b) autochthonous;

c) endoecogenetic (autogenous, or endodynamic);

d) exoecogenetic (allogeneic, or exodynamic);

g) all answers are correct

45. Syngenesis is a process:

a) colonization by plants of places not yet covered with vegetation;

b) the colonization of places by plants after the destruction of previously existing vegetation;

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