The simplest methods of geobotanical description of phytocenoses. Composition, structure and structure of phytocenoses Structure of phytocenosis
Phytocenosis- any specific grouping of plants, throughout the space it occupies, is relatively homogeneous in appearance, floristic composition, structure, and conditions of existence and is characterized by a relatively identical system of relationships between plants and habitat.
The main signs of phytocenoses:
1. Species composition of phytocenosis is determined by climate, edaphic (soil) conditions, dissected relief, the impact of biogenic and anthropogenic factors, and the biological characteristics of species. The totality of individuals of a species within a plant community forms a coenotic population, or cenopopulation. Cenopopulations include plants of different ages, as well as dormant stages, for example, seeds or modified underground shoots of flowering plants.
2. Quantitative ratios of species in the community determine its appearance and reflect the coenotic processes in it. The quantitative relationship between plants in a phytocenosis is expressed by such an indicator as the abundance of a species. It is expressed as the number of individuals per unit area. On the basis of quantity, they distinguish dominants species that dominate the community. Dominance is determined by the projective cover of the species, the number of individuals, their weight or volume. Dominants are the most productive types of phytocenosis. In the event that two or more species simultaneously prevail in the phytocenosis, they are called codominants. anthropophytes– species are random in the phytocenosis, their stay in this community can be short-term. The ratios between the species of phytocenosis are determined by the adaptability of these species to living together and environmental conditions.
Quality Role different populations within the community is also not the same. edificators are the creator species, the builders of the plant community, which determine the main features of its phytogenic environment. Edificators have a maximum environmental role, they affect the water, temperature regime of the environment, the course of the soil-forming process. In this regard, edificators largely determine the species composition and structure of the phytocenosis. Assectaroths- species that have little effect on the creation of a phytogenic environment, these are secondary species that are part of different tiers. satellites- species that are always found only singly.
3. The next sign of phytocenosis is layering – placement of plant organs of various species at different heights above the soil surface and at different depths in the soil. Each tier has its own microenvironment and is, to some extent, an independent formation. At the same time, the tier is part of a single whole - phytocenosis. The number of community tiers is determined by many factors, including climate, soil conditions, and biological and ecological features of the species. Layering ensures the existence of a large number of individuals in a limited area and a more complete use of environmental factors (illumination, water, mineral resources) by plants. The greatest number of tiers is observed in favorable conditions. The tiered arrangement of plants reduces competition and ensures the stability of communities.
4. Mosaic - horizontal dismemberment within the phytocenosis. Mosaic patches are called microgroupings. Usually microgroups are small (up to several meters in diameter). The presence of mosaicity is a consequence of the heterogeneity of microconditions in the phytocenosis: microrelief, differences in the mechanical and chemical composition of soils, and litter thickness. At the same time, the formation of mosaicity is associated with the mutual influence of plants on each other (the creation of shading, the specifics of the litter that affects the soil-forming process,
5. The next feature is synusiality . Synusia- structural parts of a phytocenosis, characterized by a certain species composition, a certain ecological character of the species and spatial isolation. Synusia can be both a tier (if the species that make it up belong to the same life form), and a microgroup (in homogeneous phytocenoses).
Along with spatial synusia, seasonal synusia are also distinguished, represented by species of the same seasonal development. They are characterized by ecological isolation and a certain phytocenotic role in the community.
6. Physiognomy - the appearance of the phytocenosis, which is determined by the life forms that make up the phytocenosis.
7. Periodicity Phytocenoses are characterized by seasonal changes in all vital processes of plants.
8. Nature of the habitat - a set of ecological features of a given area, which determine the possibility of the existence of a biocenosis. A habitat is understood not only as a place where a phytocenosis grows, but also as a qualitative characteristic of a given area. The quality of a habitat is determined primarily by climate, altitude, surface shape, rocks and their influence on soil-forming processes, physicochemical and biological characteristics of soils, groundwater regime, and the possibility of flooding the area.
In order to understand the diversity of phytocenoses that make up the vegetation cover of a certain region, they are systematized using the classification of subordinate units. Of the classification units, one has to deal with the association (the main lower taxonomic unit) and the type of vegetation (the highest taxon). Other classification units (group of associations, formation, group of formations, class of formations) are used to some extent only when constructing a legend for the profile.
There are a large number of definitions of association - short and lengthy. The main thing is that phytocenoses that are similar in species composition, structure, and habitat conditions belong to the same association.
Basic methods of selection (delimitation) of associations
In our country, most researchers, when classifying phytocenoses as a certain association, use dominant species (dominants) as the main, main criterion - species that clearly prevail in phytocenosis over other species, i.e. the same association includes phytocenoses with the same dominants, but which may differ in the composition of species with a small abundance.
To get a fairly complete picture of the association, it is necessary to describe and analyze the species composition and structure of several specific similar phytocenoses.
The dominant principle of identifying associations is the most accessible and acceptable for short-term reconnaissance studies.
However, in polydominant communities (with a large number of dominant species, for example, in meadow and steppe communities), it can be very difficult to distinguish between dominants. In addition, dominants can change dramatically during the growing season or from year to year, and then the same phytocenosis, depending on when the description is made, can be attributed to completely different associations.
At present, geobotanists also have other more objective and universal methods for identifying associations. The most promising methodological technique is the use as the main criterion for identifying an association - groups of species that indicate the ecological community of phytocenoses combined into the same association. Only limited time does not usually allow the use of other methods of identifying associations, since they require not only a certain skill, but also a long and laborious processing of field descriptions of phytocenoses.
Methodology of geobotanical research Compilation of flora
Before starting a comprehensive geobotanical study, a reconnaissance study of the flora is carried out - a list of plants growing in a given area is compiled according to the main types of biotopes (landscape sections). This is done, on the one hand, in order to compile a general idea of the vegetation of the study area, on the other hand, for educational and training purposes. When conducting "in-line" geobotanical surveys, this stage of geobotanical research can be omitted.
Compilation of a list of plant species is best done on a pre-planned route, covering diverse and contrasting habitats, typical and atypical for a given area.
It is better to lay the route using a topographic map, a forest inventory map, or using other information about the landscape structure of the area. In any case, the floristic route should pass through the main structural units of the landscape (“from bottom to top”: riverside part of the river, floodplain, terraces, slope of the bedrock bank, bedrock bank of the valley, watershed), as well as various types of plant communities (forests, meadows, swamps, agricultural landscape, settlements, etc.).
In each biotope, work is carried out in the following order;
1) the number of the point is indicated in the field diary;
2) describe the physical features of the habitat and features of the plant community (position in the relief, surroundings of the point).
3) a list of all plant species growing at a given point is recorded.
If it is impossible to identify plant species in the field, they should be herbarized.
Establishment of trial plots and sites
Descriptions of phytocenoses are made on trial plots, the sizes of which are not the same for different communities. However, in any case, they should not be less than the area of detection of phytocenosis - the smallest area on which all the main signs of phytocenosis appear.
In the study of temperate forests, it is customary to establish trial plots of 400 square meters in size. m (20 x 20 meters), and grassy vegetation - 100 sq. m (10 x 10 meters).
It is desirable to lay the trial area in the form of a square.
If the phytocenosis is small, less than the detection area, then such areas of vegetation are called association fragments. Such areas are described within the natural boundaries with an indication of their size.
Sample plots should be laid out in the most typical places within the characterized phytocenoses, i.e. it is not recommended to establish a trial plot near the border with another phytocenosis, near roads or other anthropogenic disturbances (quarries, places of fires, peat extraction, etc.).
Trial plots (or accounting plots) should be distinguished from trial plots, which may have different, but always small sizes (from 0.1 - 0.25 to 1 - 4 sq. m). They count shoots and undergrowth of tree species, take into account the absolute number of herbaceous plants, take cuttings to determine the yield of herbage, determine the occurrence of plant species, etc.
The number of trial plots may be different depending on the objectives of the study, on the given accuracy of accounting, as well as on the characteristics of the phytocenosis itself. However, they cannot replace trial plots; serve only as an addition and refinement to the analysis that is carried out on trial plots.
Description of phytocenoses
The description of the phytocenosis is carried out in a certain sequence on special forms. Depending on the tasks assigned to the researcher, the description can be made with varying degrees of detail. Most often, one type form is used to describe both forest and herbaceous phytocenoses (Fig. 1). When characterizing the latter, the columns relating to the tree and shrub layers are not filled in.
Before entering the descriptions, you should prepare a sufficient number of forms by replicating the insert on pages 10-13 of this manual in the form of an A5 brochure (half-folded standard A4 sheet - 297 x 210 mm).
Filling in the form is one of the crucial stages of geobotanical exploration of a territory, and a formal attitude to this operation drastically reduces the quality of the material or makes it completely unusable. Below is a description of those items of the form that require additional explanation or are of particular methodological importance.
Association name
The name of the association is given according to the dominant species.
The name of forest associations is compiled according to the dominants of each tier, starting with the tree. If there are several dominants in the tier, then in the name of the association they are connected by a hyphen and the prevailing one is placed in the last place.
For example, an association with the dominance of oak in the forest stand and a slightly less abundance of linden, with the dominance of common hazel in the undergrowth and in the grass cover - hairy sedge and yellow greenfinch with a predominance of sedge - can be called: linden-oak hazel greenfin-hairy-sedge.
In the names of herbaceous associations, with this method of naming, the belonging of dominants to a certain tier is usually not taken into account. Dominant species are joined by a hyphen in the order in which the dominant with the greatest abundance is placed last. For example, a meadow association with dominant pike, caustic buttercup and hare sedge with a clear predominance of pike can be called: sedge-buttercup-pike.
If one grass prevails in the herbage, for example, meadow bluegrass, there are no sedges, there are few representatives of legumes, and there are no dominant species among forb species, but together they play a significant role in the phytocenosis, then such a phytocenosis should be attributed to the forb-grass bluegrass association.
Another way to compose the name of the association is to list the dominants of each tier, starting from the top, separated by a dash.
If the tier is formed by several dominants, then they are interconnected by a plus sign, and in this case the predominant dominant is put in first place: pedunculate oak + common linden - common hazel - hairy sedge + yellow greenfinch.
When compiling the names of polydominant associations, one should still strive to ensure that the names are not too cumbersome. The name of the association should be given after the completion of the description of the phytocenosis, i.e. already after a detailed analysis of the floristic composition and structure of this phytocenosis with the final clarification of the name during the office processing of the forms.
Tiers
Tiers are the largest structural parts of the vertical structure of the phytocenosis.
When identifying and describing tiers, one should learn pw of the main provisions:
1 Longline (vertical) division of phytocenoses is determined by the fact that each phytocenosis is formed by plants of different heights and belonging to different biomorphs (life forms) - trees, shrubs, shrubs, grasses, mosses, etc.
2. The tiers are counted from above, i.e. the tallest plants belong to the first tier.
3 One tier should include all above-ground parts of the plants included in it, i.e. the tiers in the phytocenosis are not located in separate layers or floors one under the other, but, as it were, nested one into the other.
4. The tiers should be well delimited from each other, and the plants included in them should form fairly close formations. If this is not the case, then we should talk about tiered inexpressibility. For example, in a forest community, singly growing shrubs or small scattered patches of mosses do not form, respectively, either an undergrowth layer or a moss cover layer.
5. Each tier occupies a certain ecological niche. In the same tier there are plants that are close in ecology.
Thanks to layering, a large number of plant species coexist in the phytocenosis, which most fully use the habitat.
There are different principles for interpreting the allocation of tiers.
The simplest, albeit more formal, approach is to delimit the tiers according to the height of the crowns and leafy parts of plants. With this approach, the same species can be included in different tiers.
In forest phytocenoses, tiers are more often distinguished according to life forms, when the entire community is divided into tree, shrub, grass-shrub and moss-lichen tiers. It is also possible to single out several tiers of woody, shrubby, herbaceous or within woody, shrubby, etc. allocate sub-tiers (i.e., floors that differ in composition and height within a tier).
However, the tier is not only a morphological concept, but an ecological and phytocenotic one (Sukachev, 1972). According to this understanding of the tier, the same species cannot be included in different tiers. If in the forest trees of the same species have different heights due to their youth or their oppression, then individuals that are lower in height (compared to the maximum height of trees) are isolated in different canopies.
For herbaceous phytocenoses, it is usually difficult to establish a layered structure (especially during a single visit), since most of the plants during the growing season are part of different canopies, the height of which changes all the time. In such cases, the actual height distribution of plants should be taken into account.
For herbaceous plants, the height of the tiers is determined by the maximum height of the plants included in it, regardless of whether they are represented by vegetative or generative shoots.
When the layering is not clearly expressed and it is difficult to distinguish individual layers, then it is enough to note the upper level of that part of the herbage, above which the density of the herbage drops sharply. The latter is especially important in the economic evaluation of hayfields and pastures (Yaroshenko, 1969).
Tiers are designated by Roman numerals. The height of trees and shrubs is given in meters, herbaceous plants and shrubs - in centimeters.
Mosaic.
The horizontal structure of the phytocenosis is called mosaic. It characterizes spotting, variegation of phytocenosis. The main structural units of mosaicity are microphytocenoses and microgroups.
Microphytocenoses are structural units of the horizontal division of the entire phytocenosis, including all tiers.
Microgroups are structural units within one tier.
Species lists
A very important stage is the identification of the floristic composition of the tiers, i.e. compiling a list of species for each tier. Species composition is the main sign of phytocenosis, and its identification is the basis of any geobotanical research.
Doubtful species and those plants for which it is impossible to establish species in the field should be included in the description form under serial numbers and collected in the herbarium under the corresponding numbers to determine and clarify their names in office conditions. For plants that are difficult to identify and visually difficult to distinguish in the field (such as mosses, lichens or plant seedlings), it is desirable to compile special collections of the most typical and frequently occurring species of these groups in the study area.
Compiling a species list of the forest stand and shrub layer does not cause much difficulty, since trees and shrubs are represented by a small number of species that are easily distinguished and therefore well remembered. Trees and shrubs are ranked first in the list of the degree of their participation by species with a high abundance (for the characteristics of abundance, see below).
Herbaceous plants are usually found in the trial plot in greater numbers than trees and shrubs, so for the herbaceous layer, the list is most often compiled in the order in which the species come across when walking around it.
In order not to miss the species growing on the trial plot, it is desirable to enter the plants in the description form in the following way. First, include all species occurring at some point near the boundary of the trial plot. Then, moving along the boundaries of the trial plot, gradually replenish the list with new species, after which the trial plot intersects diagonally in order to include plant species that have not yet been included in the list.
This method of compiling a floristic list makes it possible to make it as complete as possible and save the site from trampling for further vegetation characterization (especially in the group description of a trial plot).
In meadow phytocenoses, you can enter a list of agrobotanical groups, separately highlighting cereals, sedges, legumes, herbs.
cenotic groups.
Different species in a phytocenosis play an unequal role or otherwise have different cenotic significance. This is the basis for the division of plant species into certain groups, the name of which and the number are different for different authors.
In the simplest classification, there are three main groups:
Edificators are species that can stably dominate and have a significant impact on the formation of the phytoenvironment of the community, i.e. these are the builders of this phytocenosis.
Dominants - dominant species, but characterized by a weak environment-forming ability in the phytocenosis.
Assectators are species that are unable to dominate, although in aggregate their role in the formation of the phytoenvironment in some phytocenoses can be tangible.
abundance
To assess the coenotic role of a species in a phytocenosis, it is of great importance to determine its abundance, i.e. its quantity on the trial plot. Abundance is determined by various indicators. The most available are eye-measuring methods of accounting, they express points; less commonly used numerical methods of individuals of each species.
When describing forest stands, to assess the role of each tree species in the forest phytocenosis, the composition of the forest stand is determined. Under the composition of the forest stand, it is customary to understand the degree of participation of each species in the forest stand of a given phytocenosis. The composition of the forest stand is determined by the method of relative accounting, i.e. when the ratio between the number of different breeds is estimated; for a stand, it is expressed as a formula on a 10-point scale. The total number of trunks on the trial plot is taken as 10 units (which corresponds to 100%), the participation of each species in mixed plantations is estimated in fractions of 10. Tree species are indicated in the formula by the first letters of their name (E - spruce, S - pine, Lp - linden , D - oak, Ol - alder, etc.). The coefficients in front of the name of tree species show their relative participation in the forest stand.
Examples: formula 6F4B means that the stand of the plantation is 60% spruce and 40% birch; formula 10E means that the plantation is clean, consists of one tree species - spruce. If the participation of any species in the plantation is less than one (ie, less than 10%), then the presence of this species in the formula for the composition of the stand is marked with a plus sign. So, for example, the formula 10E + B means that in addition to spruce, there is an insignificant admixture of birch in the forest stand. Counting the trunks takes a little time, especially when each counted tree is numbered in chalk to avoid errors.
The most accurate data for assessing the abundance of tree species can only be obtained by determining the mass or volume of each species, which is most often unacceptable under the conditions of reconnaissance studies. However, in some cases it is necessary to resort to an eye assessment of the mass, for example, when the number of oak trunks in the forest community is small, but it has a significant height and large diameter, and birch is represented by a large number, but thin trunks. If, in this case, the participation of species is taken into account only by the number of their trunks, then an incorrect idea of this phytocenosis will be formed. The role of edificator and dominant here is played by oak, it predominates in mass and the forest should be called birch-oak, not oak-birch, despite the predominance of birch trunks.
The abundance of plant species of all other tiers of forest phytocenoses is determined by the methods of absolute accounting, when the number of individuals of a given species is taken into account regardless of the number of individuals of other species. Eye-measuring methods of accounting are used, since numerical methods are laborious and are usually used in stationary studies.
Visual quantitative assessment of abundance is carried out using various scales, where points indicate different degrees of abundance.
TABLE 1. Abundance scale according to Drude (with additions by A.A. Uranova)
TABLE 2. Drude scale scores
|
The name of the graduations of the scale |
The number of individuals per 1 m 2 (lower left part of the table) or per 100 m 2 (upper right part of the table, highlighted in color) with an average coverage of one specimen |
Share of coverage by all plants of a given species (%) |
|||||
|
latin |
up to 16 cm 2 (4 x 4 cm) |
Up to 80 cm2 (9 x 9 cm) |
up to 4 dm 2 (20 x 20 cm) |
up to 20 dm 2 (45 x 45 cm) |
up to 1 m 2 (100 x 100 cm) |
||
|
singly | |||||||
|
absently | |||||||
|
quite abundant | |||||||
|
very abundant |
over 20.0 |
||||||
The most widely used for assessing the abundance of herbaceous plants was the Drude scale in the interpretation of A.A. Uralov (Table 1). A.A. Uralov, based on the position that the more individuals of a species are found on the area, the (on average) the distance between them should be smaller, made an attempt to characterize the scores in the Drude scale by the average values of the smallest distances between plants of a given species. Some authors believe that when using scale estimates of abundance, one inevitably has to combine the idea of the number of specimens of each species (estimated by a certain scale score) with the idea of its coverage (Yaroshenko, 1969).
However, the abundance and projective cover characterize different properties of phytocenoses, so the correlation of the ratios of these categories does not always give correct results. Thus, plants with prostrate numerous densely leafy branches with a small abundance will have a significant projective cover, and, on the contrary, small, low-leaved plants, occurring in a large abundance, will be characterized by a small projective cover. For such species, both abundance and projective cover should be indicated.
In addition to the listed abundance levels, the im (unicum) level is sometimes used for species found in a single copy throughout the entire described area. Sometimes combined estimates of abundance are used, for example, sol-sp, sp-cop. Such estimates show that the abundance fluctuates between two steps.
Of the methods of indirect absolute accounting of abundance (when it is not the abundance of a species that is taken into account, but some of its features expressed quantitatively), the definition of the projective cover of individual species is very widely used for herbaceous plants. For a more precise definition, a scale fork is used. However, this method requires the development of a certain skill in order to obtain sufficiently accurate results.
Despite fair criticisms of the Drude scale (its subjectivity and approximateness of quantitative assessment), the speed and very low labor intensity of its use make this scale convenient for conducting route studies. In addition, replacing the abundance (even if visually determined) with only the projective cover for each species is not always justified, since the projective cover is less constant than the abundance.
When characterizing tree layers (growing stands), one should have an idea of the content of the following paragraphs of the description form (see also the methodological manual of this series "The simplest method of geobotanical forest description").
crown density
Closeness - the area occupied by the projections of tree crowns without taking into account the gaps inside the crowns. The degree of crown closure is determined visually in tenths of a unit or as a percentage. Thus, the degree of crown closure, equal to 0.6, means that the share of the projection of the crowns is 0.6, and the share of gaps is 0.4 of the entire area.
tree height
Measured with an eclimeter, altimeter or by eye.
Trunk diameter
The measurement is made using a measuring fork at a height of 1.3 m from the base of the trunk. In the absence of a measuring fork, the diameter of the trunk is determined according to the circumference. For this purpose, using a soft centimeter tape, measure the circumference of the trunk and divide the resulting value by 3.1 (Pi number).
Tree age
Age is determined by counting annual rings (layers) of wood.
To determine the age of standing trees, there is a special Pressler drill. Unfortunately, it is very difficult to get it.
Age can also be determined from fresh stumps or felled trees. However, this is not always possible to use.
As a result, determining the age of trees is always fraught with great difficulties. You can use forest inventory data for the study area.
Bonitet
Bonitet (from lat. Bonitas - quality factor) - an indicator of the performance of these habitat conditions. The better the soil and climatic conditions, the more wood the plantation produces and the higher its yield. Bonitet is established based on the age and height of trees, according to tables or graphs.
Renewal of the forest stand
Includes seedlings and undergrowth. Seedlings are considered to be one-two-year-old trees. Arborists conditionally refer to all trees up to 10 cm high as shoots, and higher ones as undergrowth, but not higher than 1/4 or 1/2 of the height of adult trees. Neither shoots nor undergrowth can be considered independent tiers, since this is a young generation of trees; many of them will die in the struggle for existence, and the stronger ones will eventually reach the height of the upper tier of the plantation, take the place of the old stand.
The significance of the study of sprouts and undergrowth is great, since it allows one to judge the degree of availability of natural renewal, the stability of a given phytocenosis, the possibility of changing tree species, etc.
When characterizing the grass cover, you should pay attention to the following points of the form.
Total projective cover
This is the area occupied by the projections of the aerial parts of plants, expressed as a percentage.
When determining the projective cover, the observer looks down and takes into account the ratio of the projection of the aerial parts of all plants to the total area on which the projective cover is determined. For a more accurate definition, a Ramensky grid is used, divided into 10 square cells, usually with a side of 1 cm.
True coverage (turf)
This is the covering of the soil surface with the bases of plant stems. It is always less than the total projective cover and, if the latter is the same, it can vary.
Aspect
Aspect is the appearance (physionomy) of a phytocenosis. The community aspect changes repeatedly throughout the growing season and depends on the phenological state of the dominant plant species. This sign of phytocenosis is expressed exclusively by verbal descriptions. The names of the aspects are given by the color of the aspective species. Recording example: aspect yellow, caused by the mass flowering of buttercup caustic. For open phytocenoses, the aspect can serve as a sign of distinguishing one phytocenosis from another.
Phenological state of plants
The plants that make up the herbage of each community are in different phases of development (phenophases) at the moment of description. Comparison of the phenological phases of the same plant species under different habitat conditions allows us to draw some conclusions about how favorable these conditions are for a particular plant species, what conditions accelerate or delay its development. The following notation is used to designate phenophases.
TABLE 3. Phenophase designation system according to V.V. Alekhine (with additions)
|
Phenophase |
Characteristic |
Letter designation |
Symbol |
|
Vegetation to flowering |
The plant only vegetates, is in the rosette stage, begins to give a stem | ||
|
Budding (in cereals and sedges - heading) |
The plant has thrown out a stem or arrow and has buds | ||
|
Beginning of flowering (sporulation) |
The plant is in the flowering phase, the first flowers appear | ||
|
Full bloom (sporulation) |
plant in full bloom | ||
|
Flowering (end of sporulation) |
Plant in flowering phase | ||
|
Seed and spore maturation (fruiting) |
The plant has faded, but the seeds have not yet ripened and did not get enough sleep | ||
|
Shedding of seeds (fruits) |
Seeds (fruits) are ripe and spill out | ||
|
Secondary vegetation |
The plant vegetates after flowering and rash of seeds (fruits) | ||
|
dying off |
Above-ground shoots (for annuals - the whole plant) die off | ||
|
dead shoots |
Aboveground shoots or entire plant dead |
The nature of the placement of plants
To indicate the uneven distribution of plants, the following icons are most often used: gr (gregaria) - the plant occurs in rare (cloudy) clusters, among which there is an admixture of individuals of other species.
These designations are placed in the form in a special column "Nature of placement" or are attached to the abundance sign according to Drude, for example, sp gr, copj cum, etc.
In the last column of the form - "General remarks for the entire phytocenosis" it is desirable to draw a conclusion about the phytocenosis under study, to note its specifics, the main features of the species composition and structure. So, for derived forest cenoses, it is important to indicate how great the degree of disturbance is and how it manifests itself, whether there is a tendency for the restoration of bedrock. When describing meadow phytocenoses, it should be noted
fodder qualities of the herbage and the impact of human economic activity. Finishing the characterization of bog communities, it is necessary to emphasize what type of bog this phytocenosis belongs to.
This assignment is based on theA.S. Bogolyubov and A.B. Pankov.
Such works are based on the methods of description and observation, they are not very difficult, can be carried out by a group of schoolchildren, and give interesting and useful results.
In geobotanical research, the main object of study is phytocenosis.
In the domestic geobotanical literature, the definition given by V.N. Sukachev is most widely used: "A phytocenosis (plant community) should be understood as any set of plants in a given area of the territory that is in a state of interdependence and is characterized both by a certain composition and structure, and by a certain relationship with the environment ...".
Phytocenosis- this is not a random collection of plant species, but a natural set of species that have adapted in the course of evolution to coexistence in certain environmental conditions. The totality of all phytocenoses of a certain territory is called vegetation, or the vegetation cover of this territory.
To describe phytocenoses, the following main features are used:
1) species (floristic) composition;
2) quantitative and qualitative relationships between plants - the abundance of different species and their different significance in the phytocenosis;
3) structure - vertical and horizontal division of the phytocenosis;
4) the nature of the habitat - the habitat of the phytocenosis.
Geobotanical research is the main form of work of field botanists. Such work includes a comprehensive study of both the plants themselves and their habitat.
The existence and development of phytocenoses directly depends on a complex of physical and geographical factors, primarily on the features of the relief, soils and parent rocks of a given territory. In turn, plants and the phytocenoses formed by them change their habitat and therefore can be used as indicators (especially species and phytocenoses with a narrow ecological amplitude) of various features of natural conditions.
This technique is proposed for use for educational purposes with young geobotanists.
Materials and equipment
When conducting a simple geobotanical description, you will need:
Description form (see sample at the end);
- a simple pencil or pen; it is preferable to use a simple pencil, because. the text written in pencil is not washed out by water, which is important in the field;
- knife - to sharpen a pencil if necessary;
- tape measure or centimeter - for measuring the diameters of tree trunks.
You may also need a plastic bag or herbarium folder to collect unknown plants and paper bags (envelopes) to collect mosses.
If a trial area is to be laid for complex or long-term studies, you will also need a compass or a compass, a tape measure (or a 10 m long rope) for marking, an ax for making and driving marker stakes, a shovel - if marker holes break out and paint - if the site will be marked for multi-year monitoring purposes.
Geobotanical description technique
Task 1. Establishment and marking of a trial plot.
For the geobotanical description, a more or less homogeneous area of 20x20 meters in size (in the forest) is chosen (classic version).
There are many ways to mark out a trial plot, depending on the terrain and possibilities. We can suggest the following markup. In one (arbitrary) corner of the future trial plot, a wooden stake 3-7 cm in diameter and 2 m high is driven in. Near it, from the outside, there is a marker pit about 30 cm deep and wide. Its purpose is to serve as an additional landmark over the next at least 10-15 years. A tree can be used in place of a stake if it grows in a suitable location.
From the stake, using a tape measure or a pre-marked rope, 10 m is measured to the second corner, where a stake is also placed and a marker hole is pulled out. It is somewhat more difficult with the third and fourth corners - you need to repeat the same operation, but keep a right angle between the sides of the square (usually this is done using a compass or compass). On one or several stakes (or a tree), a notch is made, on which the number of the trial plot is written, as well as the dates of its laying and regular visits. Inscriptions can be done with a pencil, pen, marker or felt-tip pen. It is advisable to mark each stake (tree) with bright paint to make it easier to find the site on subsequent visits.
After marking the trial plot, a standard description is carried out on it using the form and methodology, which will be described below.
To simplify the description and unification of the described parameters of the physical environment and the phytocenosis itself, a form has been developed for describing the vegetation cover area (see the sample at the end of the text), i.e. a table with pre-lined graphs for each environment description parameter. Forms are filled directly in the field - at the site of the description. Before going out into the forest, you should prepare the forms in the required quantity, and only fill them out during work.
PROCEDURE FOR FILLING OUT THE FORM DESCRIPTION OF PHYTOCENOSIS.
Filling out the form header
First, you need to enter in the form general data about the description and the place of its holding: date, author, number of the description.
It is recommended to describe in detail the geographical and local position - region (region, territory, republic), district, nearest settlements. If possible, the local situation is described in detail - i.e. how to directly find the place of description (this is especially important if monitoring of these sites is planned in the future). For example: 0.4 km north of the village of Nikitina, on a hill, near the corner of the forest; or 0.85 km on the road to the highway from the village of Luzhki, then - 80m to the southeast, near a large boulder.
Position in the relief - an arbitrary description of the location of the point (areas) of the study: on level ground; on a slope to a stream or ravine; on the terrace of the river; in a depression, a ravine, on a hillock, on a river bank, on the edge of a cliff, etc.;
Environment - describes the characteristic features of the area surrounding the work site - a swamp, meadow, field, any forest, river or stream bank, the presence of a road or other anthropogenic object, etc.;
Described area (MxM) - the size of the site laid down or the described biotope For the forest, the size of the sites is usually suggested to be 20 m x 20 m. For greater accuracy of the description, several sites should be laid on different, but similar in conditions, forest areas.
Note. If you select sites with different levels of anthropogenic load and carry out descriptions, then you will simultaneously receive work on ecology - an assessment of the level of anthropogenic impact.
Task 2. How to correctly name the described phytocenosis.
The technique assumes that the participants of the work already know the plant species growing in the selected phytocenosis. However, if not all of them are known to you, then you first need to identify plants to a species using determinants or consult a teacher in order to further identify each species without problems.
The name of the community is formed from the names of the dominant species (or ecological groups) of plants in each of the phytocenosis tiers. In this case, the names of species within each tier are listed in ascending order of their relative abundance.
The full name of the forest phytocenosis includes four main components of the vegetation cover - tree layer, shrub layer, grass-shrub layer and moss-lichen layer.
In the name of the phytocenosis, they are listed in the same order. Depending on the purpose of the description, one can limit oneself to a simplified name of the forest type, listing the main ecological groups of plants that form the phytocenosis, for example: birch-pine green moss-forb forest. This means that in such a forest, pine and birch prevail in the stand, in the moss-lichen cover - the ecological group of green mosses (various species), and in the grass-shrub cover - grasses and meadow plants of rich soils.
Forests with a developed moss-lichen cover are usually divided into three types, corresponding to the predominant ecological groups of this tier: white moss (with a cover of lichens), long moss (with a cover of sphagnum and polytrichums) and green moss.
Task 3. Description of the tree and shrub layers of the forest.
After filling in the header of the form (general information about the biotope), it is necessary to describe the tree and shrub layers.
According to this method, when filling out the vegetation description form, it is proposed to determine the indicators of crown density and forest stand formulas separately for each of the high-altitude forest canopies - for a ripe and maturing forest stand - separately, for undergrowth (an independent canopy as part of a tree layer) - separately and for undergrowth (independent tier) - separately. This is due to the practical convenience of such a division and the relative simplicity of the procedure for accounting for the abundance of trees and shrubs. But, if it seems complicated to you, then the description can be simplified.
Determination of crown density
The description should begin with an assessment of crown density. Density refers to the proportion of the earth's surface area occupied by crown projections. It is also possible to characterize closeness as that part of the sky that is covered by crowns - in other words, to evaluate the relationship between the "open sky" and crowns.
The density of crowns is usually expressed in fractions of a unit - from 0.1 to 1, i.e. the absence of crowns is taken as zero, and the complete closure of crowns is taken as 1. In this case, the gaps between the branches are not taken into account - the “crown” is the space outlined mentally along the extreme branches (perimeter) of the crown. To assess the crown density of the tree layer, it is best to lie down on the ground, look up and assess how much the sky is covered with branches and leaves. Of course, the assessment is given approximately, "by eye". Therefore, several people can do this, and then you need to calculate the average value.
After assessing the species composition and canopy density of the tree layer, it is necessary to evaluate these indicators for undergrowth and undergrowth.
Pay attention to the meaning of these terms: young trees of the main forest-forming species of this forest are called undergrowth up to 1/4 of the main canopy (ripe and ripening forest stand).
Undergrowth stands out as an independent tree layer canopy.
Undergrowth is woody and shrubby plants that will never be able to form a stand.
A typical example of undergrowth in a pine-spruce forest can be young spruces, pines, birches, and undergrowth - willows, mountain ash, buckthorn, raspberries, etc.
Determining the "closeness" of undergrowth crowns and undergrowth is a little more difficult - they cannot be "looked into the light" from the bottom up. Therefore, to determine the abundance (relative abundance) of herbaceous and shrubby plants in geobotany, another indicator is used - projective cover. It is expressed as a percentage - less than 10% - single plants, 100% - complete "closeness" of plants.
Determination of the stand formula.
Having assessed the density of crowns, they proceed to compiling a forest formula - an assessment of what proportion each individual species makes up in the tree and shrub layers.
The share of species in the forest formula is usually expressed in points - from 1 to 10. The total crown volume of all plants is taken as 10 and it is estimated what part each species makes up. Separate plants, which, according to their representation in the forest, do not reach 10% (less than 1 point), are marked in the formula with the "+" sign, and single plants (1-2 in the study area) with the "unit" sign.
The names of species in the forest formula are reduced to one or two letters, for example: birch - B, oak - D, pine - C, spruce - E, aspen -Os, gray alder - Ol.s., black alder - Ol.h., linden - Lp, larch - Lts, buckthorn - Kr, raspberries - Ml, etc.
See examples of formulas for a mature stand canopy:
1) Formula 6E4B means that a mature stand is 60% spruce and 40% birch.
2) Formula 10E means that the plantation is clean, consists of one tree species - spruce.
3) The formula 10F+B means that in the stand, apart from spruce, there is an insignificant admixture of birch.
The difference between the forest stand formula and the density indicator is that the formula includes all types of woody and shrubby plants without exception, even rare and singly occurring ones. And when assessing the closeness, these species are not taken into account at all, as insignificant in the total space of crowns (because it is practically impossible to quantify the closeness of the crowns of trees or single specimens that are far from each other).
The table below shows a sample entry. It means: in the described forest there is a dense, closed canopy of ripe and ripening trees. 80% of the space in the upper part of the forest is occupied by crowns. At the same time, spruce predominates; pine and birch occur less and in equal numbers. There is a fairly dense undergrowth of spruce in the forest (intensive renewal is underway). The undergrowth is sparse and consists of buckthorn and hazel in approximately equal proportions with individual inclusions of raspberries.
Using such formulas, you can immediately imagine what the forest looks like.
Evaluate these indicators on trial sites and fill in a similar table.
If you have the time and desire, then you can conduct additional research for a more detailed description of the phytocenosis (see information below).
Task 4. Determining the diameter of the trunks, the height of the stand and the age of the plants.
The description of the tree and shrub layers also includes such important information about their structure as the diameter of the trunks (D 1.3), the height of the stand (Hd) and the age of the plants.
The diameter of the trunks is measured in several trees typical for the given forest at breast height (~1.3 m) and then the average value is calculated. If necessary, you can also mark the minimum and maximum values for each canopy. Measurements are carried out either with a special fork (large caliper), or through the circumference. To do this, the circumference of the trunk is measured on several trees, then the average value is used to determine the diameter according to the formula D \u003d L / p, where D is the diameter, L is the circumference, and p is a constant number "Pi" equal to approximately 3.14 ( in the field, the circumference is simply divided by three).
On the image the device of such a measuring plug is shown, you can make it yourself.
Stand height (Hd) - the minimum, maximum and average values of the height of trees of each species separately.
Height measurement is usually carried out in one of four ways: 1) by eye (which requires a lot of experience), 2) by measuring one of the fallen trees of a given canopy with a tape measure or meter, 3) by counting "little men" and 4) by measuring the shadow.
In the third way, the measurement is carried out together. One person stands next to the tree, and the other, with a good eye, moving a certain distance to cover the whole tree from the butt to the top, "lays" by eye how many people of this height "fit" along the entire length of the trunk. At the same time, it is more rational to postpone the distance each time, twice as much as the previous one, i.e. mentally put off first the height of the two "little men", then add two more to them, then four more, then eight more, etc. (i.e. according to the scheme 1-2-4-8 -16). From the point of view of the human eye, this is simpler and more accurate. Knowing the height of the "little man" you can calculate the height of the tree.
The fourth method - the most accurate of the indirect methods - is used in sunny weather. The shadow of a standing person whose height is known is accurately measured. Next, the shadow from the tree under study is measured. In a dense forest, when the shadow of a particular tree and, especially, its tops are difficult to find, the following method can be recommended. Move away from the tree in such a way that the person’s gaze (head), the top of the tree and the sun lie on the same line, and then find the shadow from your own head on the ground - this will be the shadow from the top of the tree. It remains only to measure the distance between this point and the base of the tree and determine the height of the tree according to the proportion: the length of the shadow of a person / his height - the length of the shadow of the tree / his height.
There are more accurate methods for measuring heights using an eclimeter or altimeter. Detailed characteristics of the design of these devices and measurements with their help can be obtained in the manuals attached to individual models.
The average rock height in a particular phytocenosis is defined as the arithmetic average of several trunks with an average diameter.
It is most reliable to determine the age of plants by the annual rings of cut down trees, which, if desired, can be found in almost any forest. Rings should be counted as close to the base of the tree as possible. You can also use a fresh stump, if there are any in the forest. In no case (even for the sake of science) should you cut down a tree yourself. Try to find stumps of the appropriate diameter. If the forest was planted, then you can find out when this happened and determine the approximate age of the trees.
The age of undergrowth, especially spruce and pine, can be determined by whorls. In these plants, at a young age (up to 30-40 years), dead (in the lower part of the crown) or living (in the upper part) branches remain along the entire length of the trunk, which grow in bunches - whorls, several branches at the same level around the circumference of the trunk. The number of such whorls - from the base of the trunk to its top, approximately corresponds to the age of the tree, because. in one growing season, the tree grows by one whorl. Three years should be added to the number of years obtained from the whorl count to account for the period of establishment and start of growth.
Task 5. Description of the grass-shrub and moss-lichen layers in the forest or grass layer in the meadow.
The form for describing the area of vegetation cover provides for the presence on the described area of various forms of microrelief - tussocks (in other words, elevated microsites) and interhummocks (i.e. depressions), which usually differ in species composition and distribution of plants. If there are no such forms of microrelief in the described area, then the entire description of the herb-shrub and moss-lichen layers can be written in one column, and the subheadings "tussocks" and "interstitials" can simply be deleted.
The size of test plots in phytocenoses with herbaceous vegetation is usually 10 m x 10 m, and sometimes only a few m2 in raised bogs.
The characterization of the grass-shrub layer in the forest and in the swamp or grass layer in the meadow also begins with the determination of the total projective cover. In this case, the ratio of plant projections (minus the gaps between leaves and branches) to the total area, taken as 100%, is visually taken into account. The accuracy of accounting for the projective coverage can be significantly increased by splitting the sample area into smaller areas: in each resulting square, the coverage is taken into account separately, and then the average value is determined.
For the same purpose, geobotanists use the Ramensky grid, which is a small plate in which a rectangular hole measuring 2 x 5 or 3 x 7.5 cm is cut. The hole is divided with a white thread or thin wire into 10 square cells (cells), 1 or 1 each, 5 cm2 each. Considering the herbage through such a mesh hole, it is determined how many cells (i.e., tenths of the hole) fall on the vegetation projection and how many on the uncovered soil surface through the herbage. Projections or empty gaps are mentally crowded to one end of the mesh. Repeated surveys of the coverage in different places of the trial plot make it possible to obtain the average value of this indicator with a fairly high accuracy. The developed standards of projective coverage gradations help in this.
Standards of gradation of the projective cover (in %) of the herbage considered in the Ramensky grid
When filling out the form in the column "grass-shrub layer", the names of plants are written in one column, or in several, if the entire list does not fit in one column. At the same time, it is desirable to indicate shrubs (blueberries, lingonberries, etc.) first in the list, and then herbaceous plants in descending order of their number (projective cover). Rare plants with a projective cover of less than 5% are combined with a curly bracket, opposite which is placed the total value of their projective cover. Single plants, as well as in the case of the tree-shrub layer, are marked with the "unit" icon.
In the same way as the grass-shrub layer, the moss-lichen layer is then described, also indicating the names of the mosses and lichens encountered (if they are present on the soil and their identification is possible) and the projective cover of each of the species.
Unknown plant species encountered during the description are selected for the herbarium and taken with them for further identification. At the same time, they are given a specific number (index) in the description form, which, after the determination is made, is replaced by the species name.
After completing the general characteristics of the grass cover of the phytocenosis, they proceed to identifying the floristic composition of the trial area and characterizing each plant species. It is best to start listing species from one corner of the site, first writing down all the plants that fall into the field of view. Further, slowly moving along the sides of the square, the list is supplemented with new species and only after that they cross the trial plot diagonally. You should look at the herbage very carefully, since not all plants can be seen from the height of human growth. Many of them, smaller ones, are well hidden under the leaves and stems of large herbs and can be found only when pushing the herbage apart with your hands and examining the most hidden corners.
After the compilation of the list of species as a whole is completed, one can start assigning them to one or another substage. In some cases, the identification of the tiered structure of the herbaceous cover is a rather difficult task, and then one can confine oneself to indicating the height of the plants and the upper level of the most dense phytomass. In cases where individual tiers are well differentiated from each other, they are numbered from highest to lowest, and for each, the dominant species and heights of development are indicated.
The degree of participation of individual species in the herbage is determined by the methods of accounting for their relative abundance. The most common of these methods is the use of the Drude scale (Table 1), in which different degrees of abundance are indicated by points based on the values of the smallest distances between individuals of a species and their occurrence.
TABLE 1. Abundance scale according to Drude (with additions by A.A. Uranov)
Abundance designation according to Drude Abundance characteristic Average smallest distance between individuals (counting units) of a species, cm
Points Sor (copiosae) at the same time, abundant plants are designated, the average smallest distance between individuals is no more than 100 cm. As a result, plants also have a high occurrence - not less than 75%. In this case, plants of large and medium sizes usually play a significant role in the general appearance of a phytocenosis or a separate layer, becoming fully or partially background. Within this score, three steps are distinguished:
sor3 - very abundant, the average smallest distance is no more than 20 cm. The occurrence is therefore, as a rule, 100%. Such plants usually (with the exception of very small plants) form the main background of vegetation or a separate layer;
cop2 - plentiful, the average smallest distance is from 20 to 40 cm. The occurrence sometimes (with a somewhat uneven distribution) is slightly below 100%. Such plants often, especially in the absence of others, more or equally abundant, but larger, play the main or at least a significant role in the physiognomy of the site of the association, creating a solid background;
cop1 - quite abundant, the average smallest distance is from 40 to 100 cm. The occurrence usually does not fall below 75%. The role of such plants in the appearance of the site is smaller, they do not constitute a background, but they can significantly affect the appearance of vegetation, representing numerous inclusions in the herbage mass, especially noticeable with a specific form of growth or large sizes of individuals.
Ballom Sp scattered plants are noted, the average smallest distance between which is 1–1.5 m. They are found almost at every 1–2 steps, but, as a rule, they do not form a background (with the exception of very large plants) and have physiognomic significance in the herbage only in case of marked contrast with others.
Single plants are designated by the Sol score. They are far apart from each other - the smallest distance is always more than 1.5 m. The occurrence is low, not higher than 40%. These plants do not have a background value, although sometimes, differing in their growth form, bright color and size, they are quite noticeable among the rest.
In the case of fluctuations in abundance between two steps, combined estimates are sometimes used, for example, sol–sp, sp–cop1, etc.
The Drude scale is extremely simple and easy to use. But this method is suitable only for a schematic, largely subjective, determination of the relationship between species and the selection of the main species from the total mass. An idea of how the results obtained using the Drude scale correlate with those using other, more accurate methods can be obtained by considering Table. 2.
TABLE 2. Drude scale scores
Task 6. Determination of plant phenophases.
The phenophase or phenological state of a plant refers to one or another phase of its development. To designate them in the description of phytocenosis, the system proposed by V.V. Alekhin (1925) - tab. 3.
TABLE 3. Phenophase designation system according to V.V. Alekhine (with additions)
If you conduct such a study several times over the summer, you will get a graph of the change in plant phenophases. If the species diversity is high, select a few species that are most interesting to you. You can also note the air temperature on the days of observation. As a result, if you monitor for several years, you can find out what affects the development of plants more - day length or temperature. But this is a topic for a separate work.
When characterizing moss-lichen cover the percentage of soil coverage with mosses is noted - total and by species. It is also very important to show the nature of the distribution of mosses and lichens, which depends on the microrelief, the influence of crowns of trees and shrubs, fallen trunks, etc., as well as the substrate on which they grow.
Task 7. Filling in the phytocenosis description form.
Land cover description form
Description No.:
The date:
Geographical and local location:
Position in relief:
Environment:
Described area (m x m):
Name of the community (according to the dominants of the main tiers):
D (1.3) - the average diameter of the trunks at chest height (1.3 meters) in cm; H(d) - the average height of the forest stand in meters.
Herb-shrub layer
bumps:
Interstitial:
moss layer
bumps:
Interstitial:
We wish everyone to combine business with pleasure - to walk through beautiful forests and meadows and at the same time do research work.
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 signs 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, ecological and biological groups are also distinguished here - 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 cover- indicator characterizing the size 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 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.
1. Characteristics of phytocenoses
1 Forest phytocenosis
2 Meadow phytocenosis
3 Ruderal phytocenosis
4 Coastal-aquatic phytocenosis
Geobotanical description of phytocenosis
1. Characteristics of phytocenoses
1.1 Forest phytocenosis
Forest phytocenosis - a forest community, a community of woody and non-woody vegetation, united by the history of formation, common development conditions and growing area, the unity of the circulation of substances. The forest community reaches its maximum degree of homogeneity within the geographic facies, where various plant species are in complex relationships with each other and with the ecotope. Depending on the ecotope, composition, ecology of tree species, stage of development, simple (single-tier) and complex (multi-tier) forest communities are distinguished.
The forest is a complex complex. Parts of this complex are in continuous interactions between themselves and the environment. In the forest there are a variety of tree and shrub species, their combinations, a variety of tree ages, their growth rate, ground cover, etc.
Thus, the main component of the forest as a whole - woody vegetation, in addition to a separate forest cenosis, receives a more definite shape. A relatively homogeneous set of trees within these boundaries is called a forest stand. Young woody plants included in the forest phytocenosis, depending on their age and development, are usually called self-seeding or undergrowth in a natural forest. The youngest generation - seedlings.
In a forest plantation, along with woody vegetation, there may also be shrubs. Forest phytocenosis is also characterized by ground cover. Therefore, the Plantation is a forest area that is homogeneous in terms of tree, shrub vegetation and living ground cover.
1.2 Meadow phytocenosis
Meadow - in a broad sense - a type of zonal and intrazonal vegetation, characterized by the dominance of perennial herbaceous plants, mainly grasses and sedges, under conditions of sufficient or excessive moisture. A property common to all meadows is the presence of herbage and sod, due to which the upper layer of the meadow soil is densely penetrated by the roots and rhizomes of herbaceous vegetation.
An external manifestation of the structure of meadow phytocenoses is the features of vertical and horizontal placement in space and time of aboveground and underground plant organs. In the existing phytocenoses, the structure took shape as a result of a long-term selection of plants that have adapted to growing together in these conditions. It depends on the composition and quantitative ratio of the phytocenosis components, the conditions of their growth, the form and intensity of human impact.
Each stage of phytocenosis development corresponds to a special type of their structure, which is associated with the most important property of phytocenoses - their productivity. Separate types of phytocenoses differ greatly from each other in terms of the volume of the aboveground environment used by their components. The height of low-grass stands is not more than 10-15 cm, tall-grass - 150-200 cm. Low-grass stands are typical mainly for pastures. The vertical profile of the herbage varies seasonally from spring to summer and autumn.
Different types of meadows are characterized by a different distribution of phytomass within the volume of the medium used. The most obvious manifestation of the vertical structure is the distribution of mass in layers (along the horizons) from 0 and further along the height.
Usually the first tier is made up of cereals and the tallest species of herbs, the second tier is dominated by low species of legumes and herbs, the third tier is represented by a group of small herb and rosette species. Low-lying (waterlogged) and floodplain meadows often have a layer of ground mosses and lichens.
In anthropogenically disturbed grass stands, the typically formed layered structure is also disturbed.
In meadow communities, especially multispecies and polydominant ones, there is always a more or less pronounced horizontal heterogeneity of the herbage (spots of clover, strawberry, golden cinquefoil, etc.). In geobotany, this phenomenon is called mosaic or microgrouping.
Mosaic in meadow phytocenoses arises as a result of an uneven distribution of individuals of individual species. And each species, even its age groups, is specific in the vertical and horizontal placement of its aboveground and underground organs. The uneven distribution of species within the phytocenosis is also due to the randomness in the dispersal of seeds (bulbs, rhizomes), the survival of seedlings, the heterogeneity of the ecotope, the influence of plants on each other, the peculiarities of vegetative propagation, the impact of animals and humans.
The boundaries between individual types of mosaicity cannot always be clearly drawn. Often, the horizontal division of phytocenoses is determined not by one, but by several reasons. Episodic mosaicity, along with phytogenic, is the most common. It is especially pronounced in the distribution of some species (angelica, cow parsnip) in places of their mass seeding (under shocks, near generative individuals), spots appear with a predominance of these species. Their power and participation in the creation of phytomass initially increases, and then decreases due to the mass extinction of individuals as a result of the completion of the life cycle.
In the meadows (unlike forests), small-contour mosaics are common. Meadows are also characterized by the movement of microgroups in space: disappearance in some places and appearance in others. Mosaic is widespread, represented by various stages of vegetation restoration after disturbances caused by deviations from average weather conditions, animals, human activities, etc.
1.3 Ruderal phytocenosis
Ruderal plants are plants that grow near buildings, in wastelands, dumps, in forest belts, along communication lines, and in other secondary habitats. As a rule, ruderal plants are nitrophils (plants that grow abundantly and well only on soils sufficiently rich in assimilable nitrogen compounds). Often they have various devices that protect them from destruction by animals and humans (thorns, burning hairs, poisonous substances, etc.). Among the ruderal plants there are many valuable medicinal plants (dandelion officinalis, common tansy, motherwort, large plantain, horse sorrel, etc.), melliferous (medicinal and white melilot, narrow-leaved Ivan tea, etc.) and fodder (awnless bonfire, creeping clover, wheatgrass creeping, etc.) plants. Communities (ruderal vegetation) formed by ruderal plant species, often developing in places completely devoid of ground cover, give rise to restorative successions.
1.4 Coastal-aquatic phytocenosis
forest ruderal phytocenosis vegetation
The floristic composition of coastal aquatic vegetation depends on various environmental conditions of water bodies: the chemical composition of water, the characteristics of the soil that makes up the bottom and banks, the presence and speed of the current, pollution of water bodies with organic and toxic substances.
The origin of the reservoir is of great importance, which determines the composition of phytocenoses. Thus, lake-type floodplain water bodies, located in similar natural conditions and characterized by similar hydrological characteristics, have macrophyte flora similar in composition.
The species composition of plants inhabiting the coastal zone of reservoirs and the aquatic environment is quite diverse. In connection with the aquatic environment and lifestyle, three groups of plants are distinguished: real aquatic plants, or hydrophytes (floating and submerged); air-water plants (helophytes); coastal aquatic plants (hygrophytes).
2. Geobotanical description of phytocenosis
Site №1
5 * 5 meters.
June 2013
Habitat:
Ufa, park of foresters of Bashkiria
Phytocenosis type: Forest
The projective soil cover is 60%.
Crown density 95%.
Layered:
tier Linden heart-shaped lat. Tilia cordatafamily Tiliaceae;
2 tier Norway maple Acer platanoidesSapindaceae ;
tier Rough Elm Ulmus glabraUlmaceae;
Mountain ash Sorbus aucuparia Rosaceae;
tier Euonymus warty Euonymus verrucosa Celasfraceae;
Norway maple Acer platanoides Sapindaceae.
Grass layer.
Chin forest Lathyrus sylvestris Fabacea;
Dandelion officinalis Taraxacum officinale.
Site №2
Plot 5 * 5 meters.
June 2013
Habitat:
Phytocenosis type: Forest.
The projective soil cover is 80%.
Crown density 60%.
Layered:
tier Rough Elm Ulmus glabraUlmaceae;
2 tier Norway maple Acer platanoidesSapindaceae;
3 tier Rowan ordinary Sorbus aucuparia Rosaceae;
Pedunculate oak Quercus robur Fagaceae.
Grass layer.
Thistle is common Cirsium vulgare Asteraceae;
Monetary loosestrife Lysimachia nummularia Primulaceae
Stinging nettle Urtica dioica Urticaceae;
Chin forest Lathyrus sylvestris Fabacea;
Fragrant bedstraw Galium odoratum Rubiaceae;
sedge Carex vesicaria Cyperaceae;
City gravel Gé um urbá Rosaceae;
Dandelion officinalis Taraxacum officinale Asteraceae;
Site number 3.
Plot 2 * 2 meters.
June 2013
Habitat:
Ufa, park of foresters of Bashkiria.
Phytocenosis type: meadow
grass tier:
· Mouse peas Ví cia crá cca Legumes Fabaceae;
· Cumin ordinary Carum carvi Apiaceae;
· buttercup caustic Ranunculus acrisRanunculaceae;
· Veronica oak Veronica chamaedrys Plantaginaceae;
· Chickweed hard-leaved Stellaria holostea L.Caryophyllaceae;
· Common cuff Alchemilla vulgaris Rosaceae;
· Bluegrass meadow Poa praté nsis Poaceae;
· Awnless bonfire Bromus inermisPoaceae;
· meadow foxtail Alopecurus pratensis Poaceae;
· red clover Trifolium praté nse Fabaceae;
· creeping clover Trifolium repens Moths;
· Strawberry green Fragá ria virí dis Pink.
Site №4
Plot 2 * 2 meters.
June 2013
Habitat:
Ufa, park of foresters of Bashkiria.
Phytocenosis type: spruce forest
The projective soil cover is 2%.
Layered:
tier Norway spruce Pí cea á bees Pinaceae;
tier Norway maple Acer platanoides L.Sapindaceae;
3 tier Norway maple Acer platanoides L.Sapindaceae.
Grass layer.
Common stork Er ó dium cicut á rium Geraniá ceae;
Dandelion officinalis Taraxacum officinale Asteraceae.
Site №5
Plot 2 * 2 meters.
June 2013
Habitat:
The projective soil cover is 100%.
· Smolyovka white Silé ne latifó liaCaryophyllaceae;
· Timothy grass Phleum pratensePoaceae;
· hawk umbrella Hieracium umbellatum L Asteraceae;
· Wormwood high Artemisia vulgaris L. Asteraceae;
· Daisy Leucanthemum vulgare Asteraceae;
· wild lettuce Lactura scariola Asteraceae;
· Bedstraw soft Galium mollugo Rubiaceae;
· Potentilla erectus Potentilla erecta Rosaceae;
· field bindweed Convolvulus arvensis L. Convolvulaceae;
· Mayweed Tripleurospermum inodorum Asteraceae;
· Yarutka field Thlaspi arvense Brassicaceae;
· Violet tricolor Viola tricolor Violacea;
· Common bruise Echium vulgareBoraginaceae;
· common flax Linaria vulgaris Crophulariaceae;
· Hiccup gray-green Berteroa incana Brassicaceae;
· Plantain lanceolate Plantago lanceolata Plantaginaceae;
· Velcro splayed Lappula squarrosa, Boraginaceae;
· Wormwood Artemisia vulgaris Asteraceae;
· Bodjak variegated Cirsium heterophyllum Asteraceae.
Site №6
Plot 2 * 2 meters.
June 2013
Habitat:
Ufa, Kirovsky district, slope base, monument to Salavat Yulaev.
Phytocenosis type: ruderal community
The projective soil cover is 100%.
· Timothy grass Phleum pratense Poaceae;
· Wormwood Artemisia vulgaris L. Asteraceae;
· Wild lettuce Lactura scariola Asteraceae;
· Bedstraw soft Galium mollugo Rubiaceae;
· Potentilla erectus Potentilla erecta Rosaceae;
· Meadow goat grass Tragopogon pratensis Asteraceae;
· Elm variegated Coronilla varia Fabaceae;
· meadowsweet Filipendula ulmaria Rosaceae;
· Burnet officinalis Sanguisórba officinalis Rosaceae;
· Common bruise Echium vulgare Boraginaceae;
· Hiccup gray-green Berteroa incana Brassicaceae;
· Wormwood Artemisia vulgaris Asteraceae;
· Thistle is a variegated Cirsium heterophyllum Asteraceae.
Summary table of species and families
Families No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 forestsluglesrude. T ilia cordata 3Sapindaceae Norway maple Acer platanoides 52 Ulmaceae Ulmus glabra 5Rosaceae Sanguisorba officinalis + Meadowsweet Filip endula ulmaria 2 Cinquefoil erect Potent illa erecta 14Sorbus S orbus aucuparia + Common cuff Alchemilla vulgaris1 Green strawberry Fragaria viridis +Gravilat urban G eum urbanum 1CelasfraceaeEuonymus verrucosa + AsteraceaeViolet Cirsium heterophyllum + Wormwood Artem isia vulgaris 1 Odorless chamomile Tripleurospermum inodorum 1 Meadow goat grass Tragopogon pratensis + Wild lettuce Lactura scariola + Dandelion officinalis Taraxacum officinale +2++1 Leucanthemum vulgare 1 High wormwood Artemisia vulgaris 2 Umbelliferous hawk Hieracium umbellatum + Cirsium vulgare + Urticaceae Stinging nettle Urtica dioica +Fabacea Elm Coronilla varia 1Mouse Polka Dot V icia cracca 1Red clover Trifolium pratense Mouse peas. V icia cracca 1 Creeping clover Trifolium repens 1 Forest sedge Lathyrus sylvestris + 11 Rubiaceae Soft bedstraw Galium mollugo 4 Fragrant bedstraw Galium odoratum 2 Cyperaceae Bubble sedge Carex vesicaria 1 Apiaceae Common cumin Carum carvi 4RanunculaceaeRanunculaceae Ranunculus acris 3Plantaginaceae Plant ago lanceolata 1 Veronica oak Veronica chamaedrys1 Caryophyllaceae Smolyovka white Sil ene latifolia 1 Stellaria holostea 1 Poaceae Meadow grass Poa pratensis 4 Timothy grass Phleum pratense 12 Awnless brome Bromus inermis 4 Meadow foxtail Alopecurus pratensis + Pinaceae Norway spruce Picea abies 5Geraniaceae Common stork Erodium cicutarium +Primulaceae Monetary loosestrife Lysimachia nummularia +ConvolvulaceaeField bindweed Convolvulus arvensis 1Brassicaceae Bert gray-green hiccup eroa incana 1 field yarutka Thlaspi arvense +Violacea Violet tricolor V iola tricolor 11BoraginaceaeCommon bruise Echium vulgare + Velcro Lappula squarrosa 1CrophulariaceaeCommon flax Linaria vulgaris 1FagaceaePedunculate oak Quércus róbur 2
conclusions
We have discovered and analyzed 52 species from 24 families. The average number of species in families is 3. Thus, the following families are distinguished as leading ones:
Bodjak variegated Cirsium heterophyllum, wormwood Artemisia vulgaris, odorless chamomile Tripleurospermum inodorum, meadow goat's beard Tragopogon pratensis, wild lettuce Lactura scariola, dandelion officinalis Taraxacum officinale, common daisy Leucanthemum vulgare, sagebrush high Artemisia vulgaris, hawkweed Hieracium umbellatum, common waterpipe Cirsium vulgare.
Burnet officinalis Sanguisorba officinalis, meadowsweet Filipendula ulmaria, erect cinquefoil Potentilla erecta, mountain ash Sorbus aucuparia, ordinary cuff Alchemilla vulgaris, green strawberry Fragaria viridis, urban gravel Geum urbanum.
Vyazel multi-colored Coronilla varia, red clover Trifolium pratense, mouse peas Vicia cracca, creeping clover Trifolium repens, forest rank Lathyrus sylvestris.
Bluegrass meadow Poa pratensis, meadow timothy Phleum pratense, awnless fire Bromus inermis, meadow foxtail Alopecurus pratensis.
Conclusions on phytocenoses.
In the forest phytocenosis No. 1, the dominant species were the heart-shaped linden lat. Tilia cordataand Norway maple Acer platanoides.
In the forest phytocenosis No. 2 rough elm Ulmus glabraand Norway maple Acer platanoides.
In the meadow phytocenosis, the dominant species were caraway Carum carvi, meadow bluegrass Poa pratensis, awnless fire Bromus inermis, ranunculus caustic Ranunculus acris.
In the spruce forest, the dominant species was the species Norway spruce Picea abies. Grass cover was sparse, with less than 5% soil coverage.
General conclusion.
In forest communities, the vegetation was represented more by woody forms, such as the heart-shaped linden. Tilia cordata, Norway maple Acer platanoides, rough elm Ulmus glabra , mountain ash S orbus aucuparia , pedunculate oak Quercus robur . The variety of herbaceous vegetation was not as great as that of the meadows.
In meadow communities, the dominant families were Poaceae and Fabacea.
In ruderal communities, the dominant family was Asteraceae,represented by species: varicose-leaved Cirsium heterophyllum, wormwood Artemisia vulgaris, odorless chamomile Tripleurospermum inodorum, meadow goat's beard Tragopogon pratensis, wild lettuce Lactura scariola, medicinal dandelion Taraxacum officinale, common daisy Leucanthemum vulgare, sagebrush high Artemisia vulgaris, hawkweed Hieracium umbellatum.
Thus, it can be concluded that certain families are characteristic of each phytocenosis. There are also species whose presence is characteristic of all studied phytocenoses, for example, the species Dandelion officinalis Taraxacum officinale.
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