Adaptability of various plants to living together. Change of plant communities. Forests: characteristics and types What are the living conditions in the first tier of the forest

The life of forest plants has its own characteristics. The trees that form a forest grow more or less close together, influencing each other and the rest of the forest vegetation. Plants in the forest are arranged in tiers, which can be compared to floors. The upper, first tier is represented by the main trees of the first degree of importance (spruce, pine, oak). The second tier is formed by trees of the second size (bird cherry, rowan, apple tree). The third tier consists of shrubs, for example, rose hips, hazel, viburnum, and euonymus. The fourth tier is herbaceous cover, and the fifth is mosses and lichens. Access to light for plants different tiers not the same. The crowns of the trees of the first tier are better illuminated. From the upper to the lower tiers, the illumination decreases, since the plants of the upper tiers retain their share sun rays. Mosses and lichens occupying the fifth tier receive very little light. These are the most shade-tolerant plants forests.

Different forests have different numbers of layers. For example, in a dark spruce forest, only two or three tiers are visible. The first tier contains the main trees (spruces), the second - a small number herbaceous plants, and the third is formed by mosses. Other tree and shrub plants do not grow in the second tier of the spruce forest, as they do not tolerate strong shading. Also, grass cover is not observed in the spruce forest.

Tiered arrangement is typical not only for aboveground parts plants, but also for their underground organs - roots. Tall trees have roots that go deep into the ground, while root system trees of the second tier are shorter and form a conditionally second tier of roots. The roots of other forest plants are even shorter and are located in the upper layers of the soil. Thus, plants in the forest absorb nutrients from different layers of the soil.

Trees of the first size (oak, pine, spruce) close their crowns and form a forest canopy, under which a small proportion of sunlight penetrates. Therefore, herbaceous plants of the forest, as a rule, are shade-tolerant and have wide leaf blades. Many of them cannot withstand exposure to direct sunlight and may die in open space. A feature of broad-leaved forest grasses is that they bloom in early spring, when there is no foliage on the trees. With the help of wide leaves, forest plants accumulate organic substances in low light and deposit them in underground organs, for example, lungwort - in rhizomes. In the gloomy spruce thickets, the flowers of herbaceous plants have corollas white so that they are visible to pollinating insects from afar. For example, such flowers are found in lily of the valley, wintergreen, sedmichnik, snyti, and mynika flowers. But despite these adaptations, the flowers of forest grasses are often not pollinated and do not form seeds. Therefore, the propagation of many herbaceous plants is carried out by dividing the rhizomes, for example, wood sorrel, lily of the valley, kupena, sedmichnik, and mynika. This explains the placement of these herbs in groups in the forest.

The forest litter covering the soil consists of fallen leaves or needles, respectively, in deciduous or coniferous forests, as well as from the bark and branches of trees, dead areas of grass, and mosses. Loose forest litter is moist, which is favorable for the development of molds and cap fungi. Myceliums of various mushrooms densely penetrate the litter, gradually transforming organic matter into humus and mineral salts to feed the green plants of the forest.

The house is open on all sides,

It is covered with a carved roof.

Come to the green house

You will see miracles in it. (Forest)
Forest- this is the most beautiful thing, it is a home for plants and animals. Think about the last time you were in the forest. How did you feel? What surrounded you? Share your impressions.

Children paint the leaves of the main tree-forming species (birch, aspen, rowan, willow) of forest phytoncenoses of the Khanty-Mansi Autonomous Okrug in the colors of their mood and explain their answers.

What are "forest tiers"?

Available for coloring following colors: red – I’m ready to act, active;

yellow - I’m ready to play, cheerful;

green - I am ready to work independently, calm;

brown - I don’t want to work, I’m sad.
Forest type is a set of forest phytoncenoses growing in similar soil and hydrological conditions and having a similar species composition of layers and a similar community structure.

Work from illustrations various types forests (Demo material).

Forests are deciduous, coniferous and mixed. The district is dominated by coniferous forests: pine, cedar, spruce-fir and larch. Birch forests predominate among deciduous forests.
Instruction card

in the ecosystems of Khanty-Mansi Autonomous Okrug. Nature conservation” I year of study.

Determine which tree the leaf is from.

Name the type of forest in which these trees grow.

Crossword "Herringbone"

Whoever solves the crossword puzzle will find out the name of the forest guard.

1. What is the home of spruce? (Forest.)
2. I am the sister of the Christmas tree, but my needles are longer. (Pine.)
3. I'm a big liar, I'll outsmart you all:
   And I’m not a Christmas tree, I’m not a pine tree, but I live with needles. (Larch.)
4. Which tree has its stems trembling at the slightest breeze? (Aspen.)

While working with herbarium material, children are asked to identify 2 tree species and answer the following questions:

• What kind of tree is this?
• Is it deciduous or coniferous? How did you determine this?
• In what type of forests can it grow?

(For example: Siberian spruce; coniferous tree, identified by needles, needles; grows in coniferous or mixed forest.)
Every biocenosis has its own structure. It is determined by the location of individuals of different species in relation to each other, both in the vertical and horizontal directions. This is a spatial structure.

Tiering– vertical distribution of organisms in communities. In plants, layering is caused by competition for light and water, and in animals - for food.

Tier- this is a structural part of a phytocenosis, combining plant species of approximately equal height with similar demands on the light regime in adulthood. Forest phytoncenoses have a complex layered structure. In the forest zone of Khanty-Mansi Autonomous Okrug, 4 tiers can be distinguished: 1 tier made up of trees 2nd tier- bushes, 3rd tier– shrubs and herbaceous plants, 4th tier– mosses and lichens. The layer of mosses and lichens is usually located at the soil level, and partly on tree trunks. The layer of herbaceous vegetation is different heights(in the Siberian taiga - up to two meters). The next tier in the forest is shrub. It reaches eight meters in height. The last forest layer is arboreal and consists of tall trees. In accordance with the tiered arrangement of plants, animals are distributed in the forest. Everything that grows on earth is subject to law in order to survive. above-ground tiers. All living things on earth are subject to this law. All living things underground, both plants and animals, are subject to the same law, and this is the law underground tiers. Tiering also exists in the soil. It is determined by the nature of the root system of various plants.

Diagram of the tiered arrangement of plants in a forest phytoncenosis.

I – tree layer, consisting of two canopies, II – shrub layer, III – herbaceous-shrub layer, IV – moss-lichen layer.
Instruction card

program "Plants, Animals and Humans"

I year of study.

Distribute the proposed plants into tiers, entering their names in the appropriate box, write the name of the tier:

1st tier -

2nd tier -

3rd tier -

4th tier -

Birch, rowan, Scots pine, rose hip, lingonberry, cuckoo flax, fireweed, lily of the valley, aspen, raspberry, Siberian cedar pine, blueberry, moss, kupena, blueberry, moss moss.

(1st tier - woody: birch, Scots pine, aspen, Siberian pine; 2nd tier - shrub: rowan, rosehip, raspberry; 3rd tier - herbaceous shrubs: lingonberry, fireweed, lily of the valley, blueberry, rose hips, blueberry; 4th tier - moss-lichen: cuckoo flax, reindeer moss, moss).

Life form– a plant form that has arisen as a result of long-term adaptation to local environmental conditions (low air and soil temperatures, excess humidity, short growing season, etc.), expressed in morphophysiological characteristics. The main life forms of plants in our district are trees, shrubs, shrubs and herbs.

Trees- a life form of plants with a perennial lignified main stem (trunk) and branches that form the crown that persist throughout their lives. The main tree-forming species of the taiga forests of the Khanty-Mansi Autonomous Okrug are Scots pine, Siberian cedar, Siberian spruce, Siberian fir, Siberian larch - conifers; among deciduous trees there are birch, aspen, and to a lesser extent willows and poplars.

Shrubs- perennial woody plants, branching at the very surface of the soil and not having a main trunk in adulthood, up to 6 m high, life expectancy from 10 to 20 years. Shrubs include Siberian mountain ash, willow spirea (meadowsweet), common juniper, different kinds willow (basket, gray, eared, Lapp, blueberry), bird cherry.

shrub– low growing shrub(up to 60 cm high). There are evergreens (lingonberries, swamp cranberries, marsh rosemary) and deciduous (blueberries, blueberries, bearberries).

Herbs- these are plants that do not have woody shoots. Herbaceous plants are divided into annual and perennial. The main representatives of herbaceous plants of the Khanty-Mansi Autonomous Okrug are common sorrel, crow's eye, sedmichnik, northern linnaea, wintergreen, bifolia, fireweed, etc.
Plants

The name of coniferous and deciduous forests depends on the species that predominates on its territory. This type is called dominant. Dominants– species of organisms that predominate in an ecosystem. As a rule, dominants stand out among plants (oak, birch, pine, etc. in forests)

If the forest phytoncenosis is dominated by Scots pine, then it is a pine forest, and birch is a birch forest.

Instruction card

program "Plants, Animals and Humans"

in the ecosystems of Khanty-Mansi Autonomous Okrug.

Protection of Nature"

I year of study.

Choose a name for the forest phytoncenosis depending on the dominant species:

• Siberian cedar pine – (Kedrach).
• Aspen – (Osinnik).
• Common willow – (Ivnyak).
• Siberian spruce – (Yelnik).
• Birch - (Bereznyak).

Each team in turn is asked to complete three tasks, correct execution tasks, points are awarded, the team with the most points is declared the winner and receives the title “ The best expert forests of Khanty-Mansi Autonomous Okrug".

Exercise 1:

Instruction card

program "Plants, Animals and Humans"

in the ecosystems of Khanty-Mansi Autonomous Okrug. Protection of Nature"

I year of study.

Give full description 5 plants according to the scheme:

1. Name of the plant.
2. Tree, bush, shrub, grass.
3. Which tier does it belong to?
4. What kind of forest does it grow in: coniferous, deciduous, mixed.

(For example: Common mountain ash; shrub; 2nd layer; grows in deciduous or mixed forest.)
Task 2:

Here are illustrations of plants and animals of one forest phytoncinosis. Draw a diagram of the tiered distribution of plants in this phytoncinosis and name it.

(For example: Coniferous forest. Siberian spruce, Siberian fir, bileaf, common juniper, wild rosemary, rosemary, sphagnum, cuckoo flax, squirrel, crossbill, marten, bear, capercaillie.)
For a correctly completed task, the team receives 5 points. Time to complete: 3 minutes.
Task 3:

Identify the plants from the herbarium /5 plants are offered/.

(For example: Siberian spruce, rosehip, blueberry, cuckoo flax, rosehip).
For a correctly completed task, the team receives 5 points. Time to complete: 3 minutes.
What new did you learn during the lesson?

Layering, what is it, why do plants need it?

Is this the dominant species?

Children paint the leaves of the main tree-forming species (birch, aspen, rowan, willow) of forest phytoncenoses of the Khanty-Mansi Autonomous Okrug in the colors of their mood and explain their answers. The following colors are offered for coloring: red - I liked the lesson, I learned a lot of new things;

yellow - I liked playing, I had fun with my friends;

green - I learned a lot of interesting things for myself, I felt comfortable;

brown - I didn’t like the lesson, I didn’t learn anything.

Main article: Flowering plants

Flowering plants occupy a dominant position in modern flora. Thanks to various adaptations to conditions environment they live almost everywhere on globe, forming forests, meadows, covering mountains and hills. Many flowering plants have adapted to life in bodies of water, while others live in swamps.

Forest

Tiers of the forest

There are many species of plants that live in forests and freshwater bodies.

In the forest, plants are arranged in tiers. This allows different plants optimal use of light for photosynthesis.

Upper tier of the forest (first)

The upper (first) tier of the forest is formed by the most light-loving plants - birch and maple. linden, aspen, etc.

Second tier of the forest

The second tier is formed by willow. rowan, bird cherry, apple trees.

Third tier of the forest

The third tier is occupied by shrubs - viburnum, buckthorn, hazel, etc.

The fourth tier of the forest

In the fourth tier there are shrubs - blueberries, lingonberries, bilberries, as well as herbaceous plants - kupyr, maryannik, gooseberry, china (Fig. 175), etc.

Lower tier of the forest

The lower tier consists of shade-tolerant plants. Of the angiosperms, these are sorrel, hoofed grass, etc.

Meadows

Meadow tiers

Meadows, unlike forests, are formed by herbaceous plants. In the herbage of meadow communities, depending on the dominance of plants different sizes Up to four tiers can be distinguished: tall grass, short grass, short grass and near-surface plants.

High grass

Escapes tall grasses reach 80-100 cm or more. This group includes awnless brome, meadowsweet, yellow cornflower (Fig. 176), large sedges and many others.

small grass

Small grasses have shoots from 15-20 to 30-40 cm. This group includes meadow bluegrass, red fescue, some types of clover, etc.

low grass

Low grasses are small plants less than 15-20 cm high (white grass, annual bluegrass, low-growing sedges, horned grass, creeping clover, arable clover, grass carnation, speedwell, mantle) (see Fig. 176).

Surface plants

Small flowering plants grow in the surface layer, often with recumbent or creeping shoots (loosestrife, sedum, Veronica officinalis, creeping thyme).

Swamp

In the swamp, the flowering plants found are marsh cinquefoil (Fig. 177). marsh whitewing, watchwort, cotton grass, cloudberry, as well as the already familiar insectivorous plant, round-leaved sundew. Common shrubs here are blueberries, cranberries, sometimes lingonberries, and wild rosemary shrubs (see Fig. 177). Trees include low-growing birches and willows. Material from the site http://wiki-med.com

Freshwater bodies

Quite a lot of flowering plants live in or near fresh water bodies. Typical coastal plants of water bodies are reeds, calamus, hogweed, arrowhead, cattail, umbrella su-sak (Fig. 178).

Among aquatic plants There are those whose roots are attached to the ground, and the leaves float on the surface. These are water lilies, egg capsules, pondweeds, and water lilies (see Fig. 178). Hornwort and Canadian elodea grow in the water column. Duckweed floats on the surface of the water in stagnant reservoirs and quiet river backwaters, sometimes forming entire bright green carpets.

On this page there is material on the following topics:

• lower tier of meadow

• in connection with which tiering arises

• excursion meadow description tiers of plants

• the lower tier is formed

• tier: willow

Questions for this article:

• What causes the tiered arrangement of plants in the forest and meadow?

Material from the site http://Wiki-Med.com

★ Home Nature Forest Part 1

Part 1. Basic concepts

Forest — component nature.

Forest- an ecological system in which trees are the main life form.

Forest-forming species- tree species that forms the forest canopy - the upper, main tier of the tree stand. In the forest they distinguish tiers:

1. Tree stand. Forest canopy- a set of crowns of closed trees. Temperate forests can have up to two forest canopies, while tropical forests can have up to five tree layers.
2. Undergrowth- a group of plants in a forest growing in the shade of trees that form a tree canopy. Consists of shrubs and low trees that never grow to the height of the main tree stand.
3. Herbal or herbaceous-shrub.
4. Mokhovaya or moss-lichen.
5. forest floor- a layer of organic residues on the soil surface in a forest.
   Forest litter consists of fallen leaves, branches, flowers, fruits, bark and other plant remains, feces and animal corpses, shells of pupae and larvae.
6. Underground tier Forests consist of the root systems of plants, forest soils and their many inhabitants, including fauna, fungi and microorganisms.

Forest edge- this is the edge of the forest up to 150 m wide.

Glade- an open area in the forest.
The main vegetation is grasses and small shrubs.

Lumberjack- a forest area set aside
for felling mature and overmature plantings.

Spruce stand.
Tree stand- a set of main tree species forming a forest.

Swampy birch forest.

Forest protection strips.

Undergrowth in a pine forest.
Flora and fauna. Forest and its inhabitants. 2008

Couldn't have said it better:

Since ancient times, humanity owes its existence to the green kingdom of plants, which absorb and convert sunlight into organic matter. Plants account for approximately 95% of the planet's total biomass, and 66% of it is produced by forests. It is forests, the green treasure of the Earth, that determine the biological productivity of the planet. They most directly have a beneficial effect on the climate, atmosphere, hydrological regime of rivers and other water bodies, protect the soil from wind and water erosion, and are regulators of atmospheric and soil moisture exchange. Therefore, forests are not only a unique part of nature, but also perform very diverse ecological and socio-economic functions.

Trees

Trees by type of leaves are divided into coniferous and deciduous.

1. Conifers They are usually distinguished by hard evergreen (rarely summergreen) needle-shaped or scaly leaves, called needles, or needles, forming cones or juniper berries. This group includes, for example, pine trees, spruce trees, fir trees, larches, cypress trees, and sequoia trees.
2. Broadleaf trees have wide and flat leaves - which are significantly thicker less length and widths, usually falling once a year. Broad-leaved (or simply deciduous) trees usually flower and bear fruit. This group includes maples, beeches, ash trees, eucalyptus trees and others.

   Characterize the plants of the forest of different tiers and determine their life form

Trees are divided according to leaf lifespan- deciduous and evergreen.

1. Deciduous trees have a clear change in leaf cover: all the leaves on the tree lose their green color and fall off, for some time (in winter) the tree stands without leaves, then (in spring) new leaves grow from the buds.
2. Evergreens trees do not have a clear change of leaf cover: foliage is on the tree at any time of the year, and the change of leaves occurs gradually, throughout the life of the tree.

In the tree they distinguish three main parts: root, trunk and crown.

1. Tree root- this is usually underground part plants. Main functions - holding the tree in vertical position, suction nutrients from the soil and transferring them to the trunk. The roots have a large extent: they can go to a depth of up to 30 meters and to the sides for a distance of up to 100 meters. Some trees have aerial roots, which are located above the surface of the earth, and their function is similar to the function of leaves.
2. Tree trunk serves as a support for the crown, and also transfers substances between the roots and the crown. In winter, it acts as a storage facility for moisture and nutrients. The tree trunk consists of a pith, wood, which grows from the cambium inward, forming annual rings - dark and light areas visible on the cross section of the tree. The number of annual rings in temperate forests corresponds to the age of the tree, and their thickness corresponds to the living conditions of the tree in each particular year. In dry areas, trees may develop false rings after precipitation. The outside of the trunk is covered with bark. During its life, a tree usually has a single trunk. If the main trunk is damaged (cut down), sister trunks may develop from dormant buds in some trees. The part of the trunk from the base to the first branches is called the trunk.
3. Tree crown- a collection of branches and leaves in the upper part of a plant, continuing the trunk from the first branch to the top of the tree or shrub with all lateral branches and foliage. There are such characteristics as the shape of the crown - from columnar to spreading and the density of the crown - from dense to sparse, openwork. Under the influence of light in the leaves, as a result of photosynthesis, the synthesis of necessary substances occurs.

• Sequoia trees reach the greatest height; in Redwood National Park their height reaches 115.55 m.
• The thickest tree in the world is the baobab, 15.9 m in diameter.
• The oldest tree in the world is considered to be spruce, growing in the mountains in western Sweden, probably from ice age. Its age is about 9550 years.

Layering of plants in phytocinoses

The main factor determining the vertical distribution of plants among ground tiers is the amount of light.

Thus, plants in the upper tiers are more light-loving than those in the lower ones, and are better adapted to fluctuations in temperature and air humidity.

Layering is especially well expressed in temperate forests. They can be divided into 5-6 tiers:

* the first (upper) tier is formed by trees of the first magnitude ( spruce, pine, oak, birch, aspen);

* the second tier is formed by trees of the second size ( rowan, bird cherry, wild apple and pear);

* the third tier is the undergrowth formed by shrubs ( common hazel, buckthorn, European euonymus, rose hips);

* the fourth tier consists of large grasses ( wild rosemary, blueberry, bilberry, heather, wild rosemary, nettle, fireweed);

* the fifth tier is composed of lower grasses ( crowberry, cranberry, sorrel, sedge);

* in the sixth tier are located mosses and lichens.

Low-tiered communities are meadow, steppe, and swamp, which have 2-3 tiers.

The underground layering is a kind of mirror image of the aboveground one: the roots of the tallest trees penetrate to a greater depth than the roots of shrubs, the roots of small herbaceous plants are located closer to the surface, and mosses are located directly on it. Moreover, there are significantly more roots in the surface layers of the soil than in the deep ones.

Thus, the tiers determine the composition and structure of the phytocenosis: if there are few tiers, then the plant community is called simple, if there are many, then it is complex.

Plants of each tier and the microclimate determined by them create a specific environment for specific animals:

* in the soil layer of the forest, which is filled with plant roots, soil animals live (various microorganisms, bacteria, insects, worms);

* insects, ticks, spiders, and numerous microorganisms live in the forest floor;

* higher tiers are occupied by herbivorous insects, birds, mammals and other animals;

* different species of birds build nests and feed in different tiers - on the ground (pheasants, grouse, wagtails, pipits, buntings), in bushes (thrushes, warblers, bullfinches), in the crowns of trees (finches, goldfinches, kinglets, large predators).

It should be noted that the same species in the same community, due to age differences between individuals or partial oppression, can be found very briefly in different tiers.

For example, spruce seedlings, while they are small, are located in the lower tiers of the forest. But as it grows, under favorable conditions, the spruce will take its place in the upper tier.

In addition, there are extra-tiered organisms.

Extra-tiered organisms make it difficult to clearly distinguish layers, which is especially pronounced in tropical rainforests, the structure of which is extremely complex.

Species of animals and plants of different tiers in the biocenosis are in close relationship and interdependence.

* the strong growth of the upper tiers of the community accordingly reduces the density of the lower ones, often up to the complete disappearance of the plants composing them, along with which the animal population disappears;

* on the other hand, thinning the upper tier for one reason or another contributes to the enhanced development of plants in the lower tiers due to improved light, moisture, heat, as well as increased content minerals in the soil. The growth of the lower tiers has a positive effect on the animal population, both quantitatively and qualitatively.

Thus, a tier can be considered as a structural unit of a biocenosis, which is characterized by certain environmental conditions, a corresponding set of plants, animals and microorganisms, between which their own system of relationships develops.

The vertical distribution of organisms in a biocenosis also determines a certain structure in horizontal direction.

The heterogeneity of the distribution of organisms in the horizontal direction is called mosaic.

Mosaicism is characteristic of almost all phytocenoses.

Mosaicity is expressed by the presence in the biocenosis of various microgroups that differ in species composition, quantitative ratio different types, productivity and other properties.

The unevenness in the horizontal distribution of living organisms in the biocenosis and the associated mosaic pattern is due to a number of reasons:

* heterogeneity of soil conditions (presence of depressions and elevations);

* environment-forming influence of plants and their biological characteristics;

* the result of animal activity (formation of anthills, trampling of grass by ungulates, etc.) or human activity (deforestation, plowing of steppes, fire pits, etc.).

The mosaic pattern is quite important for the life of the community, as it allows the most complete use of the resources of various types of habitats. This leads to an increase in the number and diversity of species in the community, and helps to increase the sustainability of the entire community.

Not only tiered placement allows different plants to coexist freely with each other.

By carefully observing the life of plants in a plant community, it is possible to identify other features of their adaptability to living together.

One of these devices is development at different times.

IN middle lane, for example, hazel grows - hazel. It blooms when tall trees have not yet covered with leaves and the wind freely transfers pollen from staminate flowers to pistillate flowers. Early flowering hazel - adaptation to life in the forest with other plants.

Trees whose crowns are located above all other plants in the forest are most often pollinated by the wind. They bloom before the leaves bloom. And most shrubs are pollinated by insects, since under the forest canopy (Forest canopy is a set of crowns of closed trees located in one or several tiers. Wikipedia) There is almost no wind. The green canopy of the forest does not allow the wind to penetrate to the plants in the tiers. Therefore, the fruits ripened on the bushes are not distributed by the wind, like most trees of the first tier, but by birds living in the forest. Berries and others juicy fruits, for example honeysuckle, raspberry, buckthorn, rosehip, euonymus, become tasty food for many birds in the fall.

An interesting adaptation of herbaceous plants to life in the plant community of broad-leaved forest is the early flowering you know of some herbaceous plants called snowdrops.

Snowdrops are light-loving plants. They bloom in the spring, when the leafless branches of trees and shrubs of the forest freely transmit the rays of the sun. Early flowering of snowdrops is possible primarily because the soil of a broad-leaved forest freezes less in winter than in open places. Deep, loose snow cover and forest litter made of fallen leaves, dead parts of herbaceous plants, rotting dry branches and bark protect the soil from freezing. Under the snow in such a forest, the soil temperature is often around 0°C, never falling below minus 1-2°C. Due to the stored nutrients, snowdrops develop under the snow.

Adaptation to life under trees with a lack of light is the color of the petals of flowers of herbaceous plants. Thus, in herbaceous plants of coniferous, dark forests, the white color of the corollas of flowers predominates, which are clearly visible to pollinating insects.

Only plants that bloom before the leaves of trees and shrubs bloom or grow in forest clearings and edges have flowers with brightly colored petals, like those of the swimsuit, lungwort, corydalis, buttercups and others.

Studying the life of plants, one can notice that some plant communities are gradually replaced by others. For example, in a forest, living conditions are favorable for shade-tolerant grasses, ferns and other plants growing under the canopy of trees.

If you cut down the trees that make up the upper layers of the forest, then many shade loving plants the lower tiers (oxalis, lily of the valley, lily of the valley, wintergreen and others) will die, their place will be taken by other, more light-loving plants and a different plant community will gradually emerge. A change in the sun exposure of plants is one of the reasons for the change in the forest plant community.

The plant community of a forest can also change when a sphagnum moss cover develops in the forest, which will lead to waterlogging and cause the death of plants. The forest is gradually being replaced by swamp vegetation. One plant community will be replaced by another.

Change plant communities may be caused by various reasons. Often these are fluctuations in climate, weather, soil changes, changes caused by plant life processes in the communities themselves.

In the existing plant community, due to these reasons, other species may appear, previously living ones may die off and die.

Thus, in aging birch forests, one can observe the displacement of light-loving birch by spruce, as a result of which, in a few years, instead of a light birch forest, a plant community of shady spruce forest appears.

The replacement of one plant community by another has a significant influence economic activity person.

Man cuts down forests and replaces them with arable land; drains swamps, plows up steppes; fixes the moving sands in the desert, turns the desert into blooming gardens.

Along with this, timely human intervention can extend the life of the plant community.

So, for example, an old, mossy meadow with compacted soil can be rejuvenated and turned into a meadow that again grows mainly cereals. To rejuvenate such meadows, special measures have been developed and applied: harrowing the meadow, sowing cereals and legumes, etc.

From a geography course, you know that in a forest, plants of different sizes are located on top of each other, forming tiers. This can be seen even on a small site.

The first tier includes the tallest trees: oak, ash, maple, birch, elm, poplar, beech.

Write down the characteristics of the tree layers. In it, indicate: name of tree species, height, diameter, age.

The height of a tree can be determined using an eclimeter - an instrument for measuring vertical angles on the ground.

Make an eclimeter in advance. Cut a rectangular board measuring 20X15 cm and nail a student protractor to it. Hang a small weight on a strong thread in the center of the semicircle of the protractor.

It is best to measure the height of a tree with two people. Stand at some distance from the tree and sight along the upper edge of the eclimeter towards the top of the tree. Then move back or forward until the plumb line reaches the 45 degree mark. From here, use a tape measure to measure the distance to the tree and add the amount of your height to your eyes. This will be the height of the tree.

The diameter of the tree can be determined as follows. Using a tape measure, measure the circumference of the tree at a height of approximately 140 cm and divide the resulting figure by 3.14.

It remains to determine the age of the tree of the first tier. You already know that the age coniferous trees can be determined by whorls of branches. TO deciduous trees this method is not applicable. Therefore, age is best determined by the growth rings on a fresh stump.

The second tier consists of trees slightly inferior in height to the main species. This is the undergrowth from shade-tolerant trees- rowan, bird cherry, wild apple and pear.

Describe the trees of the second tier in the same form as you described the first tier. To determine height and thickness, select the tallest tree of each species.

In addition to trees, various shrubs grow in the forest. They belong to the third tier. The shrub layer in a forest is also called the understory.

In terms of rock composition, it is the most diverse. These include hawthorn, buckthorn, hazel, elderberry, euonymus, honeysuckle, viburnum, and rose hips.

You may have noticed that in some places the bushes form such dense thickets that it is difficult to get through them.

Describe the shrubs that grow in the sample plot. Make records of the shrub layer in the following form: name of the shrub species, how many shrubs grow in the sample plot, average height, state.

See if there are any heavily oppressed trees in the third tier. Some trees, falling into favorable conditions, during their long life they cannot rise above the bush.

Try to determine the cause of the depressed state of the tree.

Place all herbs in the fourth tier. These are plants whose above-ground stems die off during the winter; only the roots and rhizomes of perennial plants remain alive.

In botany lessons you taught that herbs have their own biological features very diverse. Most cereals, sedges, etc. are perennial; to two-year-olds - umbelliferous, many cruciferous. There are also annuals.

Using reference literature, identify all types of grasses found on the sample site and write in the column: “Name of species.” In the second column, write down which plant species is quantitatively dominant and which species are rare.

In the third column, indicate the phenological phase. The phases for flowering plants are as follows: vegetative - the plant has not yet bloomed, flowering, fruiting, seeding - the plants are seeded or have already been seeded, dying - above-ground shoots have dried up and died.

Pay attention to how the plants are arranged species composition regarding light, moisture and other conditions.

When studying the woody and herbaceous vegetation on the test site, you will certainly notice small trees - undergrowth. Determine: where are the shoots from seeds, and where are the shoots from old roots and stumps. Observe the struggle that young seedlings of trees with grass cover endure. Note in the log whether there are any cases of seedling death.

Determine which origin of the undergrowth develops better: seedlings or shoots. Explain the reasons for their unequal growth.

And to which tier do mushrooms belong? These plants, as well as microscopic algae and bacteria, belong to the fifth tier.

When studying the vegetation of the fifth tier, describe only the mushrooms. If you have literature with pictures and descriptions of mushrooms, try to determine their names.

From observations you know that each type of plant develops in certain conditions. Obviously, plants of different tiers also make different demands on living conditions - light, heat, soil.

Don't forget to collect plants for your botanical collection - herbarium. For large plants - trees and shrubs - take two copies of each species, for small ones - several.

A herbaceous plant, if it fits in a herbarium folder, dig it up by the roots. Shake off the soil from the roots, and if it doesn’t come off well, wash it off.

Place each type of plant in a herbarium folder with a label. In it write the serial number, date, location, name of the plant and number of the tier.

After finishing work on the test site, continue the specified route. When you come across other plant species, stop and explore the new plant community.

When studying a plant community, it is important not only to determine the type of plant and describe its characteristics, but to study the patterns of plant development.

Tree trunks are often inhabited by insects: longhorned beetles, borers, horntails, bark beetles, sapwood, pine beetles and others, which can not only accelerate the death of trees, but also damage the wood.

Some species (dormouse, weasel, squirrel, marten, chipmunk and others) descend from trees to the ground. Others, on the contrary, spend most of their time on the ground, but can climb trees and move around them (grouse grouse, forest cat, ermine, lynx, sable and others).

It is difficult to imagine a forest without the animals that live in the lower tier of the forest. In dense thickets of undergrowth closer to the soil and on the soil, where there is significantly less light due to the fact that

The tree crowns absorb it, and there is more moisture in the air and there is no wind, it nests a large number of birds. In the gloomy thickets, egg laying and chicks are safer. Elk - this forest giant, feeds only on plant foods: branches, shoots, tree bark, moss, lichen and mushrooms. He also likes berries. Moose likes to gnaw on the bark of aspen trees, and sometimes even spruce trees. The marks of his teeth are clearly visible on the trunks; they are located quite high above the ground.

Mammals - predators - live in the lower tier of the forest.

The brown bear is an example of an omnivore. He loves to eat large quantities of unripe spikelets of cereals, eats berries, roots, fruits, eggs and meat, and loves honey.

When hunting a large animal and killing the animal, the bear leaves the carcass to decompose for several days, then returns and eats the prey. Hedgehogs settle under tree roots, in dense bushes, under stones, and dig holes. They are predominantly omnivorous, but prefer animal food: invertebrates, amphibians, reptiles (hedgehogs are famous for their resistance to snake venom), carrion.

Vipers feed mainly on mouse-like rodents, amphibians and lizards, and destroy bird nests located on the ground.

There are animals whose life passes both above the ground and in the soil, for example, the red wood ant, the shrew, and mouse-like rodents.

Ants play a big role in spreading forest plants, as they serve as carriers of their seeds.

Mouse-like rodents feed on seeds and roots of forest plants, but they themselves are food for larger animals. Some animals live only in the soil.

Life in the soil is associated with the lack of light, difficulties of movement, high humidity or lack of water, a large number of dying plant roots and plant debris on its surface.

These are, first of all, earthworms. Total weight of earthworms

Earthworms By processing dead organic residues, they increase soil fertility, loosen and “ventilate” it, which creates favorable conditions for plants, microorganisms and other animals living in the soil.

Mole crickets can feed on both dead organic matter and living plant roots, causing damage to seedlings in nurseries and forest crops.

The mole, constantly loosening the soil, helps to increase its fertility. It destroys insects “harmful” to the forest, such as May beetle larvae.

Lesson on the topic: “Life conditions of plants. Forest as a plant community"

Goal: to continue acquaintance with plant communities, to highlight the distinctive features of the forest as a plant community

educational - to continue the formation of a caring attitude towards nature;

educational - repeat material on life forms of plants, plant communities,

become familiar with the concepts: layering, light-loving, shady, shade-tolerant, cold-resistant, heat-loving, xerophytic, mesophytic, hydrophytic plants,

learn to distinguish tiers in the forest and distribute plants into groups in relation to water, light, temperature;

developing - continue to get acquainted with the plants of your region.

Forms of work: teacher's story, discussion, heuristic conversation.

Equipment: table “Oakwood”, “Tiering”.

Lesson terms: layering, environmental factors, light-loving, shade-loving, shade-tolerant, heat-loving, cold-resistant, xerophytes, mesophytes, hydrophytes, life forms, plant community.

During the classes.

I. Organizational moment.

II. Test on the topic of lichens.

III. Learning new material

IV. Consolidation of material: working with terms at the end of § 62

V. Homework: § 62, be able to answer questions at the end of the paragraph, write down plants of coniferous and deciduous forests in a notebook.