The main types of phytocenoses. Description of forest phytocenoses. Quantitative ratios between species

Phytocenosis is characterized by:

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

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

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 composition of the phytocenosis throughout the area occupied by it depends on the conditions of existence (habitat conditions) of the phytocenosis and the history of its development. At the same time, the size of the area occupied by the phytocenosis is also of considerable importance. The number of species registered on the accounting site, established 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. It is characterized by the relative homogeneity of the species composition, a certain structure and system of relationships between plants with each other and with the external environment. Phytocenoses are the object of study of the science of phytocenology (geobotany).

Phytocenosis is a part of 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 circulation of matter and energy. Soil properties, microclimate, composition of the animal world, such characteristics of biogeocenosis as biomass, bioproductivity, etc., depend on vegetation. In turn, the elements of phytocenosis are plant cenopopulations - aggregates 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: tree layer, fern layer and moss layer. Then the Swedish scientist Gult identified 7 tiers in the forests of northern Finland:

1. upper woody,
2. lower arboreal,
3. undergrowth,
4. top herbal,
5. medium herbal,
6. lower herbal,
7. ground.

Vertical structure has two polar variants connected by smooth transitions: tiered and vertical continuum. Thus, layering is not an obligatory characteristic, but uneven height of plants is a widespread phenomenon.

Layering allows coexistence in the community of species of different quality in terms of their ecology, makes the habitat ecologically more capacious, creates a large number of ecological niches, especially in relation to the light regime.

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

Consistent use of the concept of tiering has a number of theoretical difficulties associated with the fact that:

1. not all communities are vertically discrete;
2. it is not clear if the tiers are layers or elements "inserted" into each other;
3. it is not clear where to attribute lianas, epiphytes, undergrowth.

To overcome these difficulties, Yu. P. Byallovich formulated the concept of a biogeocenotic horizon - a vertically isolated and vertically further inseparable structural part of a biogeocenosis. From top to bottom, it is homogeneous in the composition of biogeocenotic components, in their interconnection, the transformations of matter and energy occurring in it, and in the same respects it differs from neighboring, above and below, biogeocenotic horizons.

The vertical parts of plant communities, respectively, form phytocoenotic 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 the vertical structure, there are no controversial issues, including where to attribute lianas, epiphytes, or undergrowth.

horizontal structure

Most plant communities are characterized by heterogeneity of horizontal composition. This phenomenon is called the mosaic of phytocenoses. Mosaic elements are most often called microgroups, although a number of researchers have proposed their own terms - microphytocenoses, cenoquants, cenocells. The notion 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 mosaic according to their origin:

1. Phytogenic mosaicity due to competition, changes in the phytoenvironment or the specifics of plant life forms (the ability to vegetatively reproduce and form clones).
2. Edaphotopic mosaicity associated with the heterogeneity of the edaphotope (roughness of the microrelief, different drainage, heterogeneity of soils and litter, their thickness, humus content, granulometric composition, etc.).
3. Zoogenic mosaicity caused by the influence of animals, both direct and indirect (indirect) - eating, trampling, deposition of excrement, the activity of digging animals.
4. Anthropogenic mosaicism is associated with human activities - trampling due to recreational stress, grazing of farm animals, mowing grass and cutting down forest plant communities, resource harvesting, etc.
5. Exogenous mosaicity due to external abiotic environmental factors - the influence of wind, water, etc.

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

In contrast to mosaic characterizing the intracenotic horizontal heterogeneity, complexity is the horizontal heterogeneity of the vegetation cover at the supraphytocenotic level. It manifests itself in the regular 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 thus differentiates the landscape into habitats with different ecological regimes.

There are complexes and combinations of communities. Complexes are communities that are genetically related to each other, i.e. which are consecutive stages of one successional process.

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

Synusia- these are structural parts of the 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 respect.

Well distinguished in broad-leaved forests is the synusia of spring forest ephemeroids, the "pseudo-meadow" synusia in deserts, or the synusia of annuals in some types of vegetation.

Composition, structure and structure of phytocenoses

Phytocenology (from Phytocenosis and ... Logia - the doctrine of phytocenoses (plant communities); a branch 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 studying their vegetation cover, an idea arose about the regular combinations of co-growing plants - plant communities, the need for their study as a special object was justified, and the tasks of a scientific discipline that studies plant communities were formulated, the name of phytotopography (I. P. Norlin), florology (Polish botanist 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.

The tasks of phytocenoses include the study of the floristic, ecobiomorphic (see Ecobiomorpha) and cenopopulation composition of phytocenoses, the relationships between plants, the structure, ecology, dynamics, distribution, classification, and history of phytocenoses. F.'s development proceeded in several directions. The founder of the geographical direction was A. Humboldt, who established at the beginning of the 19th century. the main patterns of vegetation distribution depending on the climate; the results of research by Humboldt and his followers summarized it. the geographer of plants A. Grisebach, who in 1872 published The Vegetation of the Globe According to Its Climatic Distribution (Russian translation 1874-1877). The development of this direction was greatly influenced by the works of V. V. Dokuchaev. Owl research. geobotanists G. N. Vysotsky, A. Ya. Gordyagin, B. A. Keller, and others went in the direction of studying vegetation, taking into account soil conditions. The greening of the study of vegetation was largely influenced by the "Textbook of the ecological geography of plants" dates. botanist I. Warming (Russian translation in 1901 and 1902). phytocenology phytocenosis science

In the 19th century significant material was accumulated on the structure (layering, mosaicity) of phytocenoses (Austrian botanists I. Lorenz, 1858, and A. Kerner, 1863; Finnish botanist R. Hult, 1881, etc.) and the study of successions, 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, well-delimited units. There was also an idea about the continuity of the vegetation cover, about the absence of sharp boundaries between phytocenoses (if the growing conditions change gradually). The doctrine of the continuity of the vegetation cover and the associated idea of ​​the ecological individuality of plant species were substantiated independently by Ramensky (1910, 1924), Amer. scientist G. Gleason (1926), Italian G. Negri (1914), French. scientist F. Lenoble (1926). This direction at first did not receive recognition, but starting from the 40s. began to develop successfully in the USA (J. Curtis, R. Whittaker, and others), and then in other countries. Supporters of the continuity of the vegetation cover substantiated the methods of ordination - the allocation of types of phytocenoses based on their placement in a coordinate system that characterizes changes in certain environmental conditions (moisture, soil fertility, etc.). Ordination is also successfully used by supporters of the 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, an idea arose about the possibility of using vegetation as an indicator of the conditions for plant growth (B. Keller, 1912, F. Clements, 1920). Subsequently, methods were developed for compiling ecological scales and using them to indicate the environment by the composition of vegetation (Ramensky, 1938; Ramensky et al., 1956; G. Ellenberg, 1950, 1952, 1974, and others). It also turned out to be possible to use vegetation as an indicator in geological and hydrogeological studies (Sov. botanist SV Viktorov and others).

The biological direction of the study of phytocenoses was substantiated by Schweitz. botanist O. P. Dekandol (1820, 1832). It was developed after the publication by Charles Darwin of The Origin of Species (1859). The followers of Decandol 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 Rus. 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 relationship of plants in phytocenoses, V. N. Sukachev and A. P. Shennikov used an experiment; then. an experimental F.

From the 40s. 20th century based on the representation of Sukachev and English. botanist A. Tensley about biogeocenoses (ecosystems), a new direction arose in the study of phytocenoses as components of more complex bio-inert systems. Stationary complex studies (in addition to botanists, zoologists, microbiologists, soil scientists, climatologists) began to develop, 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, consortia (See Consortia ), the relationship 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 the changes caused by human activity, find out the conditions that ensure the maximum production of phytocenoses, including the creation of artificial highly productive phytocenoses. Mathematical methods, including mathematical modeling, are increasingly being used in phytocenoses, and the statistical and mathematical study of phytocenoses has arisen.

A great contribution to the development of F. was made by owls. botany. 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 the forest F., B. N. Gorodkov, V. B. Sochava, V. N. Andreev, B. A. Tikhomirov - vegetation of the tundra, L. G. Ramensky and A. P. Shennikov - meadows, V. V. Alekhin, E. M. Lavrenko - steppes, etc.

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

Research on F. is conducted in many countries in botanical, ecological, geographical, and also specialized scientific institutions, in the corresponding 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 Nature Testers. Biological Department (since 1829), Ecology (since 1970), Forest Science (since 1967) and Journal of General Biology (since 1940), and abroad - Journal of Ecology (L. - Camb., since 1913), "Ecology" (N. Y., c 1920), "Ecological Monographs" (c 1931), "Vegetatio" (The Hague, since 1948), "Folia geobotanica et phytotaxonomica" (Prague, since 1966), "Phytocoenologia" (V., since 1973). The USSR also publishes a series of works by the BIN of the Academy of Sciences of the USSR devoted to phytogenesis—Geobotany (since 1932) and Geobotanical Mapping (edited by V. B. Sochava, since 1963). Phytocenosis structure

Depending on the specifics of research in the concept of "biocenosis structure", V.V. Mazing distinguishes three directions developed by him for phytocenoses.

• 1. Structure as a synonym for composition (species, 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 confinement to ecological niches and occupy a certain space. This also applies to other components of biogeocenosis. Between the parts of the spatial division (tiers, synusia, micro-groups, etc.) one can easily and accurately draw boundaries, put them on the plan, calculate the area, and then, for example, calculate the resources of useful plants or animal feed resources. Only on the basis of data on the morphostructure, it is possible to objectively determine the points of setting up certain experiments. When describing and diagnosing communities, a study of the spatial heterogeneity of cenoses is always carried out.
• 3. Structure, as a synonym for sets of connections between elements (functional). Understanding the structure in this sense is based on the study of relationships between species, primarily the study of direct relationships - the biotic connex. This is the study of food chains and cycles that ensure the circulation of substances and reveal the mechanism of trophic (between animals and plants) or topical relationships (between plants - competition for nutrients in the soil, for light in the aboveground sphere, mutual assistance).

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

Phytocenosis consists of a number of structural elements. There are horizontal and vertical structure of phytocenosis. The vertical structure is represented by tiers identified 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, undergrowth layer, etc. The number of layers may vary. The evolution of phytocenoses goes in the direction of increasing the number of layers, as this leads to a weakening of competition between species. Therefore, in the older forests of the temperate zone 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 that is somewhat different from the environment in the inter-canopy space), relief heterogeneities (which cause changes in the groundwater level, different exposure), species characteristics of some plants (reproducing vegetatively and forming monospecies "spots" , changes in the environment by one species and response to this by other species, allelopathic effects on surrounding plants), animal activities (for example, the formation of spots of ruderal vegetation on rodent burrows).

Regularly 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 the forest one, is characterized by a set of features that give a clear idea of ​​its structure and structure. The main features of phytocenosis are species composition, layering, abundance, quantitative and qualitative relationships between species, occurrence, projective cover and vitality. To evaluate these features, there are quantitative indicators.
When describing phytocenoses, a trial area is distinguished in the form of a rectangle or square. The size of the trial area should fully reflect all the features of the phytocenosis. It has been established that for forest communities its minimum size is 400-500 m2.
Geobotany has adopted certain rules for describing phytocenoses. They boil down to the following: all descriptions are numbered, the date of work, the author, the size of the trial plot, the geographical location of the trial plot, the position on the relief are indicated, and the microrelief, moisture conditions, ground (dead) cover, soil type with a description of the soil section and analysis are also characterized. soil samples.
The main component of the forest phytocenosis is the forest stand, which includes certain tree species. On the accounting (trial) area, a complete recount 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. Undergrowth is taken into account. Within each tier, a numerical assessment is given of the ratio of trees of different species in the phytocenosis, either in fractions of a unit, or for 10 trunks, that is, how many trunks out of 10 fall on each species. For example, the form D6V4 means that there are 6 trunks per oak, and 4 trunks per elm. The diameter of the trunks is measured with a taxator's fork at chest height (1.3 m) or with a tailor's meter, the circumference of the trunk is determined at the same height and the resulting value is divided by 3.14. All trees in the trial plot are measured.
The height of a tree is determined using an eclimeter. To do this, depending on the height of the tree, 10, 20 or 30 m are measured from it, and from the point found they sight to the top and find the angle. According to the angle and distance from the trunk, according to the tables, the height of the tree is set.
In the characteristics of the stand, the diameter of the crowns is taken into account by measurements with 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. An average value is taken from the four measurements. At the same time, visually or instrumentally calculate the height of attachment of crowns as the distance from the base of the trunk to the place of attachment of the lower branches of the crown.
In the taxation characteristic of a forest stand, the sum of cross-sectional areas per hectare is important. This indicator is estimated by the Bitterlich full-meter (circular sampling method). A full-meter is a ruler 0.5-1.0 m long with nozzles at the end in the form of a fork with a solution of the latter 1.0-2.0 cm, respectively. Through the slot of the fork, the diameter of the tree is sighted; being at one point and turning 360°, the observer sights all the trees. If during sighting the diameter of the tree is greater than the aperture of the full gauge, then the tree is taken into account; if it is equal to it, then every second tree is taken into account. When overlapping one tree with another, it is necessary to move back 0.5-2 m in order to clearly see the tree being evaluated, and then return to its original place. The number of considered trees is noted separately for each species. The sum of cross-sectional areas in square meters per 1 ha is equal to the number of counted trees. 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 prevailing diameter of the trunks and their number on the trial 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 plots of 2x2 m, 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 trial plot.
Accounting for the undergrowth provides for an assessment of the species composition, crown density, and the nature of distribution over the trial plot. The closeness of the crowns of the undergrowth is determined, as for the main stand, in fractions of a unit or as a percentage.
The total projective cover of the soil with grass-shrub cover is defined as the percentage of the area occupied by the projections of the above-ground parts of plants - grasses and shrubs. Mixed forests are characterized by the highest species saturation, the main components of which are light coniferous and small-leaved tree species. In such forest communities, thanks to the transparent crowns, favorable conditions are created for the development of shrubs and herbaceous vegetation. The aspect of phytocenosis consists of the most striking features of the structure of phytocenosis: the abundance of any species, its density, color, dominance by tiers.
In phytocenoses, there is often no uniformity; mosaicity is noted in the form of individual spots, curtains. This applies to both arboreal and terrestrial herbaceous layers. This phenomenon is synusia- is determined by the conditions of the microrelief, illumination, soil type, hydrological conditions. When describing a phytocenosis, each synusia is evaluated by its size, configuration, and order of placement on the relief.
The species composition of plants is described in the form of Russian and Latin names, here they distinguish ecological and biological groups - one-, two-, perennials, forest, forest-meadow, steppe species, weeds and others, as well as shrubs, semi-shrubs, grasses.
abundance is an estimate of the number of a particular species in a community. In geobotany, the scale of the Danish botanist Drude is usually used, which is based on a visual assessment of the abundance of each species in a phytocenosis. A more accurate, but more time-consuming method for estimating abundance is the method of recalculating individuals of a species per unit area. Abundance can also be estimated by the weight method.
The Drude scale includes six levels of abundance:
Socialis (Soc) - plants are joined by above-ground parts, forming a common background, background plants;
Copiosus3 (Cop3) - plants are very abundant;
Copiosus2 (Cop2) - quite a lot of plants, scattered;
Copiosus1 (Cop1) - plants are rare;
Sparsus (Sp) - few plants;
Solitarius (Sol) - single plants, there are very few of them.
The Drude scale can be associated with the projective cover scale. This indicator of species abundance provides a more objective assessment of the value of the species in the plant community.
The method for recalculating the abundance of a species is based on the allocation of accounting areas, the size of which depends on the nature of the forest phytocenosis. Accounting for trees in a phytocenosis is carried out 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 of 100 m2.
The weight method for accounting for the abundance of species is mainly used in geobotanical studies in herbaceous phytocenoses, but it can also be applied in forest phytocenoses for the herbaceous layer. In this case, 20 plots of 0.1 m2 are selected on the trial plots and the plants are cut at the soil level, then the cut plants are laid out by species and weighed. After the end of the work on all accounting sites, the average indicators of the participation of each species in the formation of the ground mass of the phytocenosis are calculated.
Projective coverage- indicator that characterizes the size of the horizontal projection of the aerial parts of all plants of a given species found on the trial plot, in relation to the size of the trial plot. Express the projective coverage as a percentage. This figure 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 a species in a phytocenosis. The most objective assessment of the viability of a species can be obtained during flowering or fruiting of a tree species. There is a scale of vitality for evaluation: For - “good vitality” - the species steadily blooms, bears fruit, gives a 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, weakly vegetates.
When describing phytocenoses, the phenophases of plants are necessarily noted, which is important for characterizing the seasonal rhythm of phytocenoses in general.
In forest phytocenoses, the following stages of seasonal development, or phenological phases, are usually distinguished: vegetation, budding, flowering, fruiting, vegetation after fruiting, dying off, and dormancy. NOT. Bulygin evaluates the phenological development of woody plants, subdividing them into two stages of ontogeny: the first is juvenile, the second is virginal and subsequent. The second stage, in turn, is divided into observations of generative and generative-growth shoots.
The composition of forest phytocenoses often contains lichens and mosses as an integral part of the ground cover. A general characteristic of these groups of plants is given, 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 is also noted on trunks, stones, deadwood, and the size and configuration of the phytocenosis, its environment, transitions to adjacent phytocenoses and the place of the phytocenosis in ecological series are also estimated.

Bibliography

Voronov A.G. Geobotany. Proc. Allowance for high fur boots and ped. in-comrade. Ed. 2nd. M.: Higher. school, 1973. 384 p.

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

Stepanovskikh A.S. General ecology: A textbook for universities. M.: UNITI, 2001. 510 p.

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

Program and methodology of biogeocenological research / Study of forest biogeocenoses / M.: Nauka, 1974. S. 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 "phytocenosis".

4. The main signs of phytocenosis.

5. The minimum size of the area for detecting phytocenosis.

6. On the boundaries of phytocenosis. The concept of the vegetation continuum.

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

To manage biogeocenotic processes, one must know the patterns 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, on the other hand, synthesizes the results of the listed sciences from a certain angle, focusing on the interactions of the components of biogeocenoses with each other and revealing general patterns that govern these interactions. This field of knowledge studies biogeocenosis as a whole, explores its inherent processes.

1. Identification of the boundaries of biogeocenosis

It is known that only when the exact boundaries of the biogeocenosis are established, it is possible to analyze it. And the more specifically and precisely the biogeocenosis is limited in space, the more objectively it is possible to quantitatively characterize the processes and phenomena occurring in it.

It is well known that it is difficult to accurately establish these boundaries, "... drawing boundaries between them is often conditional, to a certain extent subjective in nature ...". V.N. Sukachev wrote about this: "...Different biogeocenoses, of course, have different vertical thicknesses, for example, forest, steppe, desert, etc. However, as a rule, we can assume that the upper limit 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 he singles out a part of the biosphere, which he called " phytosphere ".

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

1. You need to start with the analysis of the terrain. Although the relief, as you know, is not part of the biogeocenosis components, it is a very important factor in its existence. For the first orientation in forest biogeocenoses during their isolation and differentiation 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 a biogeocenosis is the homogeneity of the soil and vegetation cover. Of these two indicators, it is especially suitable for the identification of biogeocenoses homogeneity vegetation cover due to its visibility. Therefore, when distinguishing biogeocenoses in nature, it is advisable to use phytocenosis. The boundaries of each biogeocenosis separately are determined by the boundaries of the phytocenosis.

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

2. Biogeocenosis-forming role of phytocenosis in the landscape

Phytocenosis is the main component, a nodal 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, internal climate, composition, abundance and distribution of animals, microorganisms, features and intensity of the material and energy exchange of the entire biogeocenosis system.

Phytocenoses serve:

1) main receivers and solar energy transformers,

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, for several decades, effective field research methods and methods of office processing of actual materials have been developed and are being developed.

Based on the foregoing, a detailed study of phytocenosis is an indispensable part of any biogeocenological study. Vegetation always begins the study of any natural system. In our lectures, the main attention will be paid to phytocenosis and methods of its study. Moreover, many of the patterns inherent in phytocenosis also apply to zoocenosis and microorganisms.

In a general form, the study of phytocenoses is reduced to solving the following major issues:

• Determination of the role of phytocenosis in the accumulation of organic matter and energy and the transformation of matter and energy in the general system of biogeocenosis (a key issue!).
• Determination of the role of phytocenosis in the dynamics of biogeocenosis.
• Determination of the nature and degree of impact of phytocenosis on other components of 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 phytocenosis on neighboring biogeocenoses.
• Determination of the form, methods and means of direct and indirect impact on phytocenosis by human economic activity in order to increase the biological productivity of biogeocenosis and enhance its other useful properties.

3. Definition of the concept of "phytocenosis"

The first definition of a plant community was given by G.F. Morozov (1904) for the forest, and then distributed by V.N. Sukachev (1908) to all plant communities. The term "phytocenosis" was applied 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 own hydrological regime, microrelief, microclimate, soils.

V. N. Sukachev (1956) very successfully defines phytocenosis: "... Phytocenosis, or a plant community, is a collection of plants growing together in a homogeneous area, 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 slope north-north-east. exposure (altitude marks 250-300 m a.s.l.; average slope steepness is 15-20).

The tree stand consists of 2 tiers. It is characterized by a very high density of crowns - 0.97. The trees are closed by crowns and twilight reigns under their canopy. The first tier is formed by Mongolian oak, Amur and Manchurian lindens, Manchurian walnut, single old trees of black birch and small-leaved maple.

Most of the lindens are represented by slender full-wood trees with smooth trunks. Average taxation indices of trees of the 1st tier: Dm 18-20 cm, Hm - 17-18 m. In the well-defined second tier, linden predominates - mostly younger than in the upper tier, and stunted trees, small-leaved maple. Insignificant admixture of mountain elm, Amur maakia, heart-leaved hornbeam; dimorphant, false-sibold maple and small-carp are rare. In addition, the crackling, Maksimovich's spindle tree "penetrate" into it, the bulk of the individuals of which are concentrated in the undergrowth.

The further existence of any forest is ensured by the renewal of the species of the parent stand. Undergrowth in the amount of 8.6 thousand specimens/ha is represented by all types of forest stand. Small-leaved maple dominates in its species composition, in self-sowing there are single specimens of a dark coniferous species - whole-leaved fir (Abies holophylla). ).

The undergrowth is dense, it is dominated by Manchurian hazel, mock orange, eleutherococcus are common, currant Maksimovich is less common in large bushes, early-flowering honeysuckle, single large-winged and few-flowered euonymus, green maple. Rarely, viburnum Bureinskaya grows in groups and, as a rule, with it - single shoots of Amur barberry.

Due to the high density of trees and shrubs, the herbage is sparse. In addition to the spring forest poppy, it is dominated by tuberous cornflower, sedges: Ussuriyskaya, returned, long-nosed, Bunge's chickweed, Daurian bedstraw, ferns. As in the forest stand, tiers can be distinguished in the herbage. The upper one, up to 1 m high, is formed by large-grass species growing everywhere: mountain peony, black cohosh, Daurian and Amur angelica, pointed raven, red-flowered sapling, two-row lily; single Volzhanka Asiatic and powerful stalk. Sometimes small densely covered micro-groups form grasses of medium size (forbs), up to 0.5 m high - hairy smilacin, wintering horsetail, deaf nettle, lily of the valley, and small herbs, not more than 0.25 m high: Ussuri skullcap, Franchet buttercup, two-leaved mullet, rooting trigonotis, musk adoxa, meringia lateral, Colin's violets, Siebold's hoof, doubtful jeffersonia, various types of Corydalis.

In addition to plants forming tiers, in the described phytocenosis, so-called extra-tiered plants can also be distinguished, for example, creepers of actinidia, lemongrass, and grapes.

All types of herbs can be divided into groups according to seasonal development (some are spring ephemeroids (anemones, corydalis, adonis, lloydia, etc.), go through a development cycle within a month and are at rest in June. In others (double row lily, sparkling lychnis, powerful stalk, etc.) the culmination of development occurs in July, the third (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 a significant amount that they form a continuous cover, others are rare, and others are single).

Thus, six above-ground tiers can be distinguished in this forest: two arboreal, 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 - in deeper ones. Due to the underground layering, plants use different layers of soil to obtain moisture and nutrients.

Thus, phytocenosis characterized by:

1. a certain species composition of the plants that form it,

2. a certain abundance of them,

3. certain structure and

4. confinement to a certain habitat.

4. The main signs of phytocenosis

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

The creation of a phytoenvironment is the first sign of a phytocenosis in time of appearance, because. the influence of plant organisms on the environment can already be where there is no influence of plants on each other. PHYTOCENOTIC ENVIRONMENT begins to form even at a time when individual plants that have appeared on a previously devoid or not having a coherent vegetation cover of the territory grow scattered, without forming a continuous cover.

Already at the first stages of vegetation development, microclimate conditions change, with dead plants some chemicals are introduced into the soil or soil, while others are extracted by living plants, the nature of the microrelief changes (for example, trails of dusty and sandy particles are formed near the stems of plants), in a word, there is transformation of the environment by plants. In the future, through the interaction of plants, the phytocenosis changes the environment more and more and creates its own phytoenvironment. At the same time, the environmental conditions in different parts of the phytocenosis (on the soil surface, on the trunks and 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 phytocenosis, but INTERACTIONS BETWEEN PLANTS begins somewhat later than the impact of plants on their habitat. It can take place only at a certain density of vegetation cover. However, it is very difficult to notice this moment when the interaction between plants begins, since it does not always involve direct contact between organisms.

Therefore, various stages of development of the vegetation cover should be attributed to phytocenoses, except for the very first moments of plant settlement in a territory devoid of vegetation.

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

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

From this point of view, cultivated vegetation, plant groups that settle 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.

So, it would be impossible to consider as phytocenoses not only secondary birch or aspen forests that appear on the site of the primary ones after they are cut down, but also the primary northern temperate forests that live in areas with shallow groundwater, since these forests do not regenerate after cutting down or burning out. , and the areas of cutting areas and burnt areas become swampy. Shrub communities (forest forests, sea buckthorn forests), which have replaced tall-stemmed phytocenoses (oak forests, cedar-broad-leaved forests), cannot be considered either.

It is unlikely that such a point of view can be recognized as correct. Indeed, in cultural communities, and in primary and secondary forests, and in pioneer plant groups (perhaps, with the exception of the very initial stages of their existence), there are those signs 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 existing phytocenosis:

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

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

In the process of natural selection, the composition of the phytocenosis included such species that are interconnected with each other or depend on each other. It includes not only flowering, gymnosperms, ferns, club 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 on 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 relationship between individual species has not yet been expressed.

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

5. The minimum size of the area for detecting phytocenosis

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

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

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 impact on the habitat, the smaller the size of the territory.

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

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

There can be sharp boundaries between phytocenoses, but more often the transitions are gradual, imperceptible. This causes difficulties in isolating phytocenoses. The gradual transition from one type of phytocenosis to another is a consequence of a gradual change in the environmental conditions of the habitat. If the changing values ​​of any factor (for example, moisture conditions, salinity, etc.) are plotted on a graph, then combinations of plant species that gradually replace each other will also correspond to them. Based on this, L.G. Ramensky developed the doctrine of vegetation continuity(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 downright inexhaustible ...", i.e. the number of associations is unlimited.

Many scientists, following this doctrine, do not recognize the reality of the existence of phytocenoses. 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.

At present, the doctrine of the continuity of vegetation cover has become widespread, especially in the works of American scientists: H. Gleason (Gleason, 1939), D. Curtis (Curtis, 1955, 1958), R. Whittaker (Whittaker, 1953, 1956, 1960) , F. Igler (Egler, 1951, 1954), Polish researcher V. Matuszkiewicz (Matuszkievicz, 1948). The main idea of ​​this doctrine is the impossibility of putting all the variety of combinations of plants with many different transitional groupings 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 essential. L.G. Ramensky, T.A. Rabotnov (1967) and other supporters of the continuum theory believe that the rule is gradual, unclear boundaries, and the exception is sharp ones.

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

In fact, both theories have the 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 abrupt transitions where one powerful edificator is replaced by another (for example, at the boundaries of forest plots formed by various tree species).

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

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

Between the terms "phytocenosis" and "plant community" many scientists for a long time put an equal sign, using them as synonyms. V.N. Sukachev repeatedly pointed out that the term "phytocenosis" (plant community) can be applied both to specific areas of vegetation cover and to designate taxonomic units of various ranks: associations, formations, types of vegetation, etc.

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

Association called the typological unit of phytocenoses. The same meaning is put into this term by S.M. Razumovsky (1981). In his interpretation, an association, an elementary unit of vegetation, unites areas with the same species of each tier and the same succession trend. 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 forest vegetation on this stretch is represented by secondary oak forests. The areas of these forests are very similar to each other. The stand is oak with a single admixture of Daurian birch. The undergrowth is fragmentary, represented by hazel and lespedecia. The ground cover contains forbs and sedges. Nevertheless, despite the very high similarity, it is impossible to find even two sites with exactly the same 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 following 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 caused the need for a special term that could be applied to a taxonomic category of any rank. G. Duriez (Du-Rietz, 1936) suggested "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 a larger and a smaller volume, both a forest in general and a coniferous forest, and subdivisions of the latter, as well as this particular section of it ... ".

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

Phytocenoses belonging to the same association are scattered. Usually they border on phytocenoses belonging to other associations. On the ground, combinations of phytocenoses are usually found, often they are quite noticeably different from each other. This is due to differences in other natural components, and as a result, different biogeocenoses, or so-called natural territorial complexes, are formed. It is with 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 abundance and biomass of all populations included in them;

b) the ratio of ecological groups of plants, which develops over a long time in certain climatic, soil and landscape conditions;

c) spatial mutual arrangement of plants (and their parts) in a 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) growing conditions of plants;

c) exposure to zoocomponents;

d) the form and intensity of human impact;

e) a + b + c;

e) All answers are correct.

3. The structure of phytocenosis gives an idea of:

a) the amount of media used by the community;

b) the features of the contact of its constituent plants with the environment;

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

e) All answers are correct.

4. The structure of phytocenosis depends on:

a) ecobiomorphic composition of the plant community;

b) the number and vital status of individuals of vascular plants belonging to the main forms of growth (trees, shrubs, shrubs, grasses);

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

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

e) all answers are correct

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

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

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

c) homogeneity or heterogeneity of the horizontal division;

e). a + b + c.

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

a) tiered;

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 regime and humidity regime at different levels above the soil surface in the biogeocenosis;

b) tough competitive relations between various plant species and their consorts;

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

d) terrain

8. The 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) index of homogeneity;

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 layer) 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) the ratio of the surface area of ​​the leaves of different plant species.

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. Ceteris paribus, the leaf area index in the 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 the culmination of the development of the herbage;

d) after each mowing and grazing;

e) when increasing the intensity of lighting and applying full mineral fertilizer (NPK)

f) b + c + d + e;

g) b + c + e;

h) a + c + e;

12. For the addition of the underground part of phytocenoses, a decrease in the mass of plant organs from top to bottom is characteristic. This is established for plant communities such as:

a) meadow;

b) steppe;

c) desert;

d) forest;

e) All answers are correct.

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

a) meadow;

b) semi-shrub;

c) tundra;

d) desert;

e) All answers are correct.

14. To the main cenoelements 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, which manifests itself when the community is formed by life forms of plants contrasting in height, is:

a) price element;

b) synusia;

d) cenotype;

e) phytocenotic horizon.

16. 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 regimes;

c) air humidity;

e). a + b + c + d.

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

a) resistant to seasons and years (for example, layers of evergreen trees, shrubs, shrubs, mosses, lichens);

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

c) formed by herbs;

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

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

g). a + b + c + d.

18. Longline arrangement of plants:

a) allows species of different quality in their ecology to coexist in the community;

b) makes the habitat ecologically more capacious;

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

d) reduces competition and ensures the sustainability of the community;

e) All answers are correct.

19. In the series single-tier - two - low-tier - multi-tier - imperfect-tier (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 layers and the number of species that make up the phytocenosis;

d) the absence of a certain pattern.

20. In the forests of the temperate zone, 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) the second - trees of the second size (rowan, apple, pear, bird cherry, etc.);

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

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

e) the fifth tier is composed of low grasses;

f) in the sixth tier - mosses and lichens;

g) All answers are correct.

21. The consistent use of the concept of tiering has a number of theoretical difficulties associated with the fact that:

a) not all phytocenoses are vertically discrete;

b) it is not clear whether the tiers are layers or “inserted” elements into each other;

c) it is not clear where to attribute the undergrowth, creepers, epiphytes;

e) All answers are correct.

22. There is no division into tiers in such types of phytocenoses as:

a) most herbal;

b) tropical rainforests;

c) certain types of deciduous forests;

d) a + b + c.

23. The absence (or weak expression) of layering 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 ecological characteristics.

24. There is no underground tiering:

a) in spruce forests;

b) in meadow phytocenoses;

c) on solonchaks and solonetzes;

d) in steppe and desert communities;

e) a + b + d;

g) All answers are correct.

25. Phytocoenotic horizon is:

a) a vertically isolated and vertically further 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 (unlike tiered division 26. In the forests of the temperate zone, the following phytocenotic horizons are usually distinguished, formed:

a) crowns of trees;

b) the undercrown part of the trunks of tall trees, as well as trees of a 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 grasses, which, in addition to grasses and shrubs, include the lower parts of tree trunks and shrubs with their characteristic epiphytes;

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

e) All answers are correct.

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

a) how many tiers this or that phytocenosis includes;

b) at what closeness of the aboveground organs of the corresponding plant species should the layer be considered expressed or unexpressed;

c) where to place creepers, 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 parts of trees and shrubs belong, serving as their support;

29. Each phytocenotic horizon is characterized by:

a) a certain floristic composition;

b) the composition of the organs of these plants;

c) the degree of occupancy of the space by these organs;

e) All answers are correct.

30. A section of vegetation cover, within which it is impossible to draw boundaries according to given characteristics and thresholds adopted to determine the boundary, is called:

a) parcel;

b) price cell;

c) microgrouping;

d) price quant;

e) price element.

a) one life form;

b) united by individual topical and trophic competitive relations;

c) one type;

d) different tiers.

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

a) the age of the stand;

b) group placement of trees and stands;

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

d) plant vitality.

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) cenopopulation;

b) cenotype;

c) synusia;

d) price quant.

34. As sinusia can be considered:

a) each well-limited layer of forest phytocenoses;

b) a collection of epiphytes, creepers, epiphytic lichens;

c) spring forest ephemeroids;

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

e) All answers are correct.

35. Among temporary synusias there are:

a) seasonal;

b) daily allowance;

c) fluctuation;

d) demutational;

e) a + c + d;

f) 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 synusia are close together, closed in underground or aboveground parts;

c) ecological similarity of plants included in one synusia;

d) morphological isolation, spatial expression;

e) certain interactions between plants, their impact on the environment and, as a result, 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 + e + e;

h) All answers are correct.

37. Synusia are:

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

b) blueberry or heather cover;

c) a spot 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, ash;

f) a 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. Synusia are characterized by the following functional features:

a) the plants that make up the synusia have a similarity in needs, coenotypic kinship, similarity in the transformation of the environment in a direction favorable for themselves and their partners;

b) in synusia there is a single coenotic process;

c) coenotic and ecological selections take place in the synusia;

d) all answers are correct.

39. An example of fluctuation sinusia can be:

a) a group of spring ephemeroids, well limited in time from synusia of herbs of summer vegetation, which differ from spring ones in their species composition, structure, ecologically and coenotypically.

b) thickets of willow-herb on burned areas and clearings, existing for a short time;

c) a group of annual grasses that occur in some deserts in years with a large amount of precipitation;

d) synusia of creeping ranunculus in water meadows with prolonged stagnation of spring floods.

40. Synusial analysis of phytocenoses is reduced to:

a) the establishment of synusia that make up the phytocenosis;

b) study of their species composition and structure;

c) study of the relationship between them and the environment;

e) a + b + c.

41. Synusial analysis of plant communities helps to determine:

a) environmental conditions of the habitat;

b) the completeness of the use of environmental resources by the phytocenosis;

c) the ecological niche occupied by each particular synusia;

d) a + b + c.

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

a) discontinuity;

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;

e) 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) the quantitative ratio of different species;

c) closeness;

d) productivity and other features and properties;

e) All answers are correct.

45. There are the following variants of mosaicity of phytocenoses (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;

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

G) allelopathic mosaics due to the release of some plant species of strongly smelling aromatic substances;

e) zoogenic mosaics are formed as a result of the impact of animals;

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

46. ​​Irregularity in the distribution of plant species within a plant community and the resulting mosaic pattern is due to a number of reasons. By origin, the following types of mosaics are distinguished:

a) phytogenic, due to competition, changes in the phytoenvironment or characteristics of life forms of plants;

b) edaphotopic associated with the heterogeneity of the edaphotope (roughness of the microrelief, different drainage, heterogeneity of soils, etc.);

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

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

e) exogenous, due to the action of abiotic environmental factors - the influence of wind, water, etc.

f) a + b + d;

g) All answers are correct.

47. Mosaic in the forest is least pronounced where:

a) the tree layer is formed by one species;

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

c) different ecobiomorphs (coniferous and softwood tree species) are represented in the tree layer;

d) shrubs are absent and poorly developed;

e) growing conditions for most species are unfavorable;

f) a + c + e;

g) a + b + d + e;

h) All answers are correct.

48. Mosaic is most pronounced:

a) in floodplain meadows;

b) in mixed coniferous-deciduous forests;

c) on raised bogs;

e) in coniferous forests.

49. The causes of phytogenic mosaicity in coniferous-deciduous forests, represented mainly by spruce and linden, can be the following:

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

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

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

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

e) a + b + e;

e). a + b + c + d.

50. Characteristic signs of mosaicity of many types of phytocenosis are:

a) stability in time and space;

b) dynamism;

c) change in time of some microgroups by others;

d) change due to the passage of the life cycle of plants;

e) b + c + d.

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

a) pioneer

b) invasive;

c) construction phase;

d) maturity;

e) degeneration;

f) a + c + d + e;

g) a + b + d + e.

52. There are the following types of horizontal addition of phytocenoses (according to A. P. Shennikov):

a) separate;

b) separate-group;

c) closed-group;

d) diffuse;

e) mosaic;

c) a + b + c + e;

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

53. Mosaic phytocenosis, with all the diversity of composition and division into fragments, is combined:

a) the dominance of one from the tiers;

b) the absence of the dominance of any tier;

c) small sizes of mosaic elements mutually influencing each other;

d) significant sizes of mosaic elements.

54. In contrast to mosaic characterizing the intracenotic horizontal heterogeneity, complexity is the horizontal heterogeneity of the vegetation cover at the supraphytocenotic level. The complex is formed not from fragments, but from different phytocenoses, which:

a) occupy large areas;

b) are highly dependent on each other;

c) are less dependent on each other;

d) are not connected by a common tier;

e) mosaically alternate in space;

f) a + c + d + e;

g) a + b + d + e.

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

a) ecoid;

b) ecoclin;

c) ecotone;

d) ecotope.

56. Ecotone can be:

a) narrow or wide;

b) sharp or absent;

c) diffuse or bordered;

d) mosaic-island;

e) All answers are correct.

57. The absence of a pronounced transitional band 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 arose at a clearing site);

c) environmental impact of dominant species in one of the adjacent phytocenoses (for example, spruce, sphagnum mosses, etc.);

e) a + b + c.

CHAPTER 5

Dynamics of phytocenoses.

1. Under the dynamics of phytocenoses and vegetation in general (syndynamics) is understood:

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

b) changes in phytocenoses with an increase in the age of edificators;

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;

e) All answers are correct.

2. The main forms of vegetation dynamics are:

a) violations of phytocenoses;

b) succession of phytocenoses;

c) evolution of phytocenoses;

d) a + b + c.

3. There are the following types of variability of phytocenoses:

a) daily;

b) seasonal;

c) multi-year;

d) age;

e) all answers are correct

4. Unlike shifts, the variability of phytocenoses is characterized by 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 non-directional;

f) a + d + e;

g) b + c + e.

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

a) vegetation;

b) the beginning of flowering;

c) flowering;

d) formation of seeds and fruits;

e) 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) excretion of metabolites, which, in turn, leads to fluctuations in the composition of the air within phytocenoses (CO 2 content, specific emissions, etc.);

e) All answers are correct.

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

a) light and temperature regimes;

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) features of the biotope (phytoenvironment);

b) the intensity of growth and reproduction of plants;

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

d) features of the structure 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) change in the participation of certain species in phytocenoses during the season or year;

c) composition of life forms;

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

e) the timing of the onset and duration of individual phases of vegetation;

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 occurring in phytocenoses over years or periods of years, associated with unequal meteorological and hydrological conditions of individual years, are called:

a) succession;

b) transformation;

c) fluctuation;

d) demutation.

11. In accordance with the causes of occurrence, the following types of fluctuations are distinguished:

a) ecotopic, associated with differences in weather, hydro and other conditions of ecotopes from year to year;

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

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

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

e) 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) cyclic;

d) digression-demutation;

e) all answers are correct

15. Latent fluctuations occur:

a) in monodominant grass cenoses;

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

c) in complex floristically rich multi-tiered 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 year-to-year changes at the level of subdominants;

d) seasonal dynamics of productivity

18. Digression-demutation fluctuations are characterized by:

a) the change of 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) a strong violation of phytocenoses with their subsequent demutation - a return and a state close to the original, as soon as the cause that caused the change ceased to operate;

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

19. Factors causing digression of phytocenoses can be:

a) severe prolonged drought;

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

c) the formation of a powerful ice crust;

d) severe winter with little snow;

e) mass reproduction of phytophages;

e) All answers are correct.

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

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

d) lead to disruption of vegetative reproduction of plants of the lower tiers.

21. The duration of the demutation period is determined by:

a) the intensity of community disturbance;

b) the degree of conservation of plants that dominated before the disturbance;

c) growth conditions during the demutation period;

d) all answers are correct.

22. Examples of digression-demutation fluctuations can be:

a) the replacement of grass stands by creeping grass stands under the influence of spring stagnation of hollow waters, followed by the return of the predominance of grasses;

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 go into a dormant state, and after the cessation of the drought - the possibility of a quick return of phytocenoses to their original state;

e) All answers are correct.

23. The practical significance of studying fluctuations in forage phytocenoses (meadow, steppe, etc.), aimed at their effective use and improvement, is determined by the fact that over the years:

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

b) the terms and even the possibility or expediency of using fodder lands change;

c) the effectiveness of methods for improving fodder lands is changing

(irrigation, fertilization, overseeding, etc.);

d) all answers are correct.

24. The 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;

e) All answers are correct.

26. Biomass is:

a) expressed in mass, the amount of living matter per unit area or volume of habitat (g / m 2, kg / ha, g / m 3, 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 / m 2, g / m 3)

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

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

b) predominantly animals and microorganisms;

c) more than 95% by plants.

28. The highest functional activity, i.e. the rate of increase in biomass per unit of 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) remaining in plants after using part of it for respiration;

b) created by plants in 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 elements of mineral nutrition;

c) the absence of limiting factors, such as 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 in temperature during the growing season;

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

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

a) in the course of evolution, the composition and structure of phytocenoses remain practically unchanged (the composition can 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) the irreversibility of the changes;

b) continuity of succession;

c) direction of changes;

e) All answers are correct.

34. By origin, two main types of successions are distinguished:

a) permanent;

b) temporary;

c) primary;

d) fluctuation;

e) secondary.

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

a) rocks;

c) deposits of water streams;

d) cooled lava after a volcanic eruption;

e) glades in the forest;

f) a + c + d;

g) All answers are correct.

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

a) the formation of a substrate;

b) plant migration, their engraftment and aggregation;

c) interaction of plants;

d) change by plants of the environment;

e) change of phytocenoses;

f) a + b + d + e;

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;

e) All answers are correct.

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

a) they find themselves in favorable ecotopic conditions;

b) seedlings develop with the homeostatic 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 successions to the achievement of a stable state of phytocenoses varies depending on:

a) climate;

b) initial substrate;

c) opportunities for diasporas to enter;

e) a + b + c.

40. Primary successions proceed faster:

a) warm, humid climates

b) in cold dry climatic regions;

c) on rocky ground;

d) on fine-grained substrates

41. Available data on primary succession rates suggest that (tick the correct answer):

a) in the Alps they pass in 100 years, in Japan - in 700 years, in the Arctic - in more than 7000 years, on poor quartz sand 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 coast of Michigan) - 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 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;

e) All answers are correct.

43. Secondary successions:

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

b) pass much more slowly than the primary ones;

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

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

a) syngenetic (syngenesis);

b) autochthonous;

c) endoecogenetic (autogenous, or endodynamic);

d) exoecogenetic (allogenic, or exodynamic);

g) all answers are correct

45. Syngenesis is a process:

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

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