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Wood is one of those building materials that have been known to mankind since ancient times. The volume of its consumption is growing every year, and therefore many species are on the verge of extinction.
The latter also includes the cork tree, which has been used by man for thousands of years.
It belongs to the genus of oaks. The difference from relatives is that by about five years of age, its branches and trunk are covered with thick bark with unique properties. But you can only take it off by the age of 20. Note that you can do this up to the age (tree, of course) of 200 years!
After the first collection, at least 8-9 years are required, during which the bark is restored. A tree aged 170-200 years produces approximately 200 kg of high quality raw material.
The peculiarity of this oak is also that it belongs to the evergreen species. The leaves resemble those of Russian oaks, but are covered with a significant layer of down below. The cork tree itself is quite large: the height can reach 20 meters, and the diameter of the trunk is a meter.
Latin name - Quercus suber. It grows at an altitude of no higher than 500 meters above sea level. Most of the oaks of this species are found in Portugal, which is why the country's budget receives considerable cash injections from the export of cork, which annually increases its value.
Since ancient times, man has known that the cork tree provides this most valuable raw material, and therefore it has long been cultivated culturally. Note that there is a false representative of this genus, Q. crenata, which is quite widespread in southern Europe. Its cork layer is so small that the tree is bred exclusively for decorative purposes.
Only in Portugal by plantations oak Quercus suber, more than 2 million hectares are occupied! In addition, approximately the same number of territories are used for this in all of Southern Europe.
During the year, all plantations produce more than 350 thousand tons of bark, but this amount has long been insufficient to meet demand. That is why the wild cork tree was almost completely destroyed.
By the way, what is the uniqueness of cork as a material? The fact is that it is the structure of which resembles a honeycomb in a beehive.
Each cubic centimeter of this material can contain up to 40 million of these honeycombs, which are separated from each other by partitions of the cellulose component.
Simply put, each capsule is filled with air, so that even a small piece of cork is very elastic. This property gives the material complete water resistance and the ability to restore its original state even after strong pressure.
That is why the cork tree (whose photo is in the article) has received such wide appreciation from furniture makers.
In addition, the bark contains suberin (a mixture of fatty acids, waxes and alcohols). It is unique in that it gives the tree refractory and anti-rotten qualities. Cases are known when forest fires the cork oaks remained completely intact, except for the scorched bark and the leaves dried from the heat.
Thus, the bark of the cork tree is a unique material given to man by nature.
I intend to show how information borrowed from encyclopedic sources and implemented in literally, for example, to obtain cork products, can lead to the death of plants. After analyzing the above terms, I offer the appropriate clarifications. I express the hope that this work will be useful for the same specialists; for entrepreneurs who want to resume the cork processing industry in Russia using domestic raw materials; for forest growers who have decided to resume the cultivation of the domestic cork tree and to promote, by multiplying the cork resource base, the implementation of the true rules of biological construction; for consumers of cork products in various industries - from space technology to winemaking, sports, etc.; for readers who want to broaden their horizons.
It is appropriate to recall that ninety years ago, our society, which refused to study the so-called dead languages (Latin and Ancient Greek) in the system of secondary education, made a giant leap ... back in the process of familiarizing with the universal culture. It should be recognized: the language of the nation promotes communication and unity of a certain group of people, and dead languages \u200b\u200bare the nourishing root system giant tree Indo-European languages.
Amur velvet cut
It is difficult to imagine the realities of those distant years, but their negative consequences are manifested even today. Surely anyone can independently answer the question: what level of knowledge did university graduates of those times have, if we recall that most of the youth "mastered" the program high school for 3 years (for 4 - on the job) and without exams enrolled in any institution? But among the Rabfakovites there were also those who had passed the educational program (courses for the elimination of illiteracy). What kind of Greek, especially ancient, are we talking about here?
But the vast majority of proletarian peers of the beginning of the last century - our grandfathers and fathers - passed through the system of workers' faculties (1919 - 1939). old world turned out to be destroyed to the ground, and whoever was a nobody ... However, the result of the activities of the former worker former head of our state, the current president of Russia is defined as "stinking Khrushchev". That is why now a full-fledged Russian specialist, who has an impeccable command of terminology, and it is based mainly on dead languages, is more likely to be understood in Europe and overseas than in his own country. And it's sad to admit it. Based on the foregoing, I apologize to botanists and dendrologists for the fact that, for the sake of clarity, special terms will be omitted: periderm, phellogen, phelloderm, epiderm, meristem, xylem, phloem, tracheids, sclereids, etc.
As a final preface, a household anecdote. One corresponding member of the Russian Academy of Agricultural Sciences on a bet (100 US dollars) was going to show a dictionary interpretation of the concept of cork noses, but, to his great surprise, he could not find this word even among 160 thousand units of the Russian Spelling Dictionary (Moscow, 1999).
Cork oak bark at the border of cyclic removal
True, the second debater did not risk anything, since his previews of dictionaries of botanical terms in the library of the Botanical Institute of the Russian Academy of Sciences (St. Petersburg) for more than a hundred years (from Petunnikov A., 1898) did not reveal either the word or its semantics used in the scientific literature at least since the end of the 20s of the last century (Kern E.E., 1929) for many decades (Krechetova N.V., 1986) without comment. Only one author dared to give an unstandardized definition: "cork-bearing plants are those that produce raw materials consisting of cork tissue and are used mainly as a sealing and insulating material" (Nikitin A.A., 1950). Obviously, the author borrowed an analogy in the definition of industrial crops that are raw materials for industry: rubber, medicinal, oil-bearing, melliferous, spinning, ether-bearing, sugar-bearing, etc. Perhaps this borrowing came from a desire to simplify the situation.
The absence of the normative concept of cork noses in dictionaries, in my opinion, can be easily explained if you get acquainted with the dominant word cork. According to encyclopedic data, cork is a secondary integumentary tissue of plants, consisting of polygonal microcells that are tightly adjacent to each other (without intercellular spaces) and die off when ripe.
The process of death is accompanied by corking, that is, cell membranes are impregnated with a wax-fat-like substance (suberin), which makes them impervious to gas and water vapor. The shells of cork cells typically consist of several layers: the median lamina (a layer of intercellular substance), the cork (suberin) lamina, and the cellulose layer adjacent to it from the inside of the cell, often lignified. The qualities of suberin, unique in no substance, have been known since 1815.
Actually, the phenomenon of cork formation in nature is very common, even more common than we imagine. Cork can occur in both woody and herbaceous plants. Moreover, the cork is formed on various organs: in woody plants, as well as in most perennial herbaceous plants - on stems and roots; in annuals - in the hypocotyl knee and on the roots.
The same sample from the side of the previous removal
The role of cork in the life of plants is great and diverse: it protects against excessive evaporation of water, from damage by bacteria, fungi and insects, from mechanical damage, as well as from the effects of temperature - overheating and hypothermia. One of the special functions of cork is the healing of various damage to plant tissues, the so-called wound plug. The latter can be observed with the naked eye, for example, on a cut potato tuber. It is curious that the same cork is the cause of leaf fall. Under certain conditions, at the point of attachment of the leaf stem to the branch, an intensive accumulation of cork occurs, metabolism decreases, mechanical bonds weaken and the leaf can come off due to its weight. One scientist even made calculations showing that about 33,000 kg of leaves are annually dumped on the ground per hectare of a forty-year-old birch forest (Kern E.E., 1929).
There is very little left: to find out the proportion of cork in this solid mass and how to extract it from there ...
Thus, the presence of cork in a plant does not allow it to be mechanically attributed to industrial crops, and therefore the use of the non-standardized concept of cork-bearing plants should be recognized as incorrect.
Let's understand the term cork products. How were they obtained, how did the cork get into them? The apparent answer is given by the extensive reference literature. I will quote only a few sources, arranging them in chronological order to illustrate the process of clarifying the concept.
The "Explanatory Dictionary of the Great Russian Language" contains the following notes: "cork, made of cork, bottle cork, cork oak bark, Quercus suber, cork stopper" (Dal V.I., 1866).
"Cork-bearing plants of the USSR": "the main cork-producing plants are cork oak, western or Portuguese oak (Q. occidentalis), false cork oak (Q. pseudosuber), variable oak (Q. variabilis), Amur cork tree (Phellodendron amurense Rupr.), Japanese velvet tree (Ph. Japonicum).The formation of cork layers is also noted: in cork birch bark (Ulmus suberosa), leafy elm (U. foliaceae), rough elm (U. scarba) (Nikitin A.A., 1950 ).
View from the side of the subsequent removal (after 9 years)
"Big soviet encyclopedia", v. 34: "cork products are products made mainly from the bark of a cork oak and partly from the bark of a velvet tree" (Moscow, 1955).
The "Historical and Etymological Dictionary of the Modern Russian Language" explains: "Cork - 1. Bushing, plug (in the neck of a bottle or in the hole of some other vessel, apparatus) ... 2. Material obtained from the bark of a cork oak."
“In Russian, the word cork has been known since the beginning of the 18th century in the meaning of “a plug on the hole of a tool” in the form of probes. In modern meanings, it has been noted in dictionaries since 1782 (Chernykh P.Ya., 1994).
"Modern dictionary Russian language" gives, in my opinion, a more approximate interpretation: "Cork, 1. The outer layer of the bark of some woody plants (mainly cork oak. Light and soft porous material obtained from such bark" (Kuznetsov S.A., 2004).
I note the commonality of all sources: to produce a cork product, raw materials are required, which are obtained by “peeling off” the bark (Nikitin A.A., 1950), containing cork, from a certain tree. The search for a milder treatment of the plant led to the replacement of "stripping" with "barking" ("Russian Spelling Dictionary", 1999). Unfortunately, with close acquaintance, this term did not satisfy my topic; wood debarking - cleaning wood from bark. Barking is subjected to the so-called. pulpwood, as well as mine racks and ridges for the match industry "(TSB, vol. 30, 1954). Therefore, I had to turn to the scientific and technical literature for clarification in order to understand the technology for removing the bark or part of it and why few are able to endure this operation trees are almost painless.For clarity of presentation, I suggest sections of cork oak (Fig. 1) and Amur velvet (Fig. 2).
From the works (Ioelson M.D., 1894; Kern E.E., 1928; Yakimov Yu.K., 1934; Popov V.V., 1935; Tsimek A.A., Emashev S.D., 1952) follows that the trunk of a tree (cork oak or Amur velvet) consists of wood and bark. The bark, in turn, contains two clearly separated layers: the inner one, bast, adjacent to the wood, and the outer one, cork, cut through with cracks. The bast (mother) layer up to 15 mm thick for velvet and up to 50 mm for cork oak consists of long fibers and serves to conduct nutrients from the branches down the trunk. Outer cork layer(crust - according to the definition of the "Small Biological Encyclopedia" edited by Prof. P.Yu. Schmidt, 1924) consists of dead cells and can be up to 70 mm thick or more (Fig. 3). The purpose of the peel is to protect the tree from frost, overheating and other external influences.
A significant difference from known plants, in the bark of which cork is present (except for mistletoe and the cactus Cornegio), but is inaccessible to humans, is that only cork oaks and Amur velvet have a thick crust and a fairly thick bast layer. At the boundary of these layers, mechanical bonds are very weak (!!!). It is precisely because of this that these trees allow at a certain time through certain cycles to remove the corked part of the bark (crust) from themselves to the bast (mother layer). The bast for the first time after removing the peel protects the tree from the sun, withering winds, temperature changes, etc .; in place of the removed plug, a new one quickly grows, which, in terms of consumer properties, improves from removal to removal (Fig. 4).
It is known from practice that it is the insignificant thickness of the bast layer that also determines its lower regenerative functions. Therefore, if you remove the bark from a plant without even hitting the bast, then, as a rule, it will die. The consequences of collecting cork outgrowths from elms according to the methods described by A.A. Nikitin (1950); cutting branches and beating them with mallets, manually breaking off the bark with outgrowths, manually breaking off outgrowths and cutting off outgrowths with a knife. "And although the latter method, according to the author, turned out to be the most effective: up to 2 kg of cork can be collected per day, all these methods must be classified as barbaric, and it is obvious that a reasonable person should not act in such a way.
Question: 2 CLASS: I WILL DO THE BEST AND PUT 2 STARS. TASK #1 READ THE FIRST SENTENCE. GIVE IT A CHARACTERISTIC FOR THE PURPOSE OF THE STATEMENT AND INTONATION. TASKS №2 FIND IN THE TEXT WORDS WITH A SEPARATORY SOFT SIGN. WRITE THEM DIVISION INTO SYLLABLES FOR TRANSFER. TASKS №3 FIND IN THE TEXT WORDS WITH COMBINATIONS ZHI-SHI. THINK 2 MORE WORDS. ASSIGNMENT №4 WHAT DOES THE AUTHOR COMPARE TO THE CORK LAYER OF TREES? TASKS №5 IS IT POSSIBLE TO TRAMP SNOW AROUND TREES?
2 CLASS: I WILL MAKE THE BEST AND PUT 2 STARS. TASK #1 READ THE FIRST SENTENCE. GIVE IT A CHARACTERISTIC FOR THE PURPOSE OF THE STATEMENT AND INTONATION. TASKS №2 FIND IN THE TEXT WORDS WITH A SEPARATORY SOFT SIGN. WRITE THEM DIVISION INTO SYLLABLES FOR TRANSFER. TASKS №3 FIND IN THE TEXT WORDS WITH COMBINATIONS ZHI-SHI. THINK 2 MORE WORDS. ASSIGNMENT №4 WHAT DOES THE AUTHOR COMPARE TO THE CORK LAYER OF TREES? TASKS №5 IS IT POSSIBLE TO TRAMP SNOW AROUND TREES?
Answers:
1. According to the purpose of the statement, interrogative, because ends with a question mark. Intonation: non-exclamatory. Because there is no exclamation here. 2. Leaves, trees / 3. From the text: Life, skin, living, fluffy. His own words: Dwelling, tire. 4. Dead layer. 5. No, because The best protection for trees is a fluffy snow blanket.
- Write down a two-digit number, when multiplying the units of which by 6, the equality 4 * 6 \u003d 24 is applied. Write down a two-digit number, when dividing the units by 6, the equality 24:6=4 is applied.
- Help me please! What is the sign of the product of six factors if all factors are positive?
- Make two sentences in which the participle with dependent words will stand after the word being defined. Explain punctuation marks. Make sentences with two phrases Stored in sheds and plucked from flower beds and write everything down as part of participial turnover.
- Mark schats woont in krasnojarsk.er ist 11.er spielt elektrogitarre.das macht er nicht schlecht.oft kocht er mit den eltern.er experimentiert gern. in saratow wohnt katjia gromowa.sie isn 11.sie tanzt gern und mag schwarzweibfotos.sie hat schon viele fotoalben.was fotografiert sie?Alles!sie sieht auch gern ferm aber nicht den ganzen tag
- There were as many pencils in the box as there were felt-tip pens. Vanya took 6 pencils and 4 felt-tip pens from the box. What was left in the box more: pencils or felt-tip pens? How much more?
- Complete the sentences. 1) keep it mind that ... 2) It never came to my mind t hat ... 3) my best friend and I are of the same mind about ... 4) the word "birthday" often calls to mind . .. 5) people must be out of their minds if they think that ... 6) I`ve never been in two minds about ... 7) I don`t think I`ll ever change my mind about ...
- Establish a correspondence between each of the four given substances and the formulas of substances with which it can interact: H2 H2O HCl NaOH 1) S CuO N2 2) Fe CuO NH3 3) Ca SO2 Na2O 4) Cu N2 H2SO4 5) CuCl2 NH4Cl SiO2
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The materials were sent by Glebov A.A. teacher of technology and labor training, MOU "Veselolopan secondary school"
Target: to acquaint students with the importance of wood as a structural material in national economy country, its breeds, structure, main types of vices and application, teach to determine by appearance samples tree species and types of defects.
Tools and equipment: sets of samples of wood lumber, veneer, plywood, samples of wood with defects, instructional and technological cards.
During the classes:
I. Introduction.
1. Consolidation of the material covered.
Questions:
1. The wedge should protrude above the table top to a height less than the height. (blanks)
2. What is the name of the discipline we are studying? (Technology)
3. The base of the workbench is (underbench)
4.It can be cutting and measuring. (Tool)
5. The profession of a worker engaged in manual processing of wood. (Joiner)
6. Serves for fixing workpieces. (Clamp)
7.Wooden blocks designed to stop blanks (Wedges)
2. Communication of the purpose of the lesson
II. Presentation of the program material.
Forests cover an area of over 700 million hectares in our country. Despite such huge forest wealth, everyone should take good care of the forest, as it significantly affects the climate, vegetation and animal world In addition, the forest is of great economic importance. Its main product - wood - is used in construction, furniture, match production, chemical industry, etc. Forest resources in our country are protected by law.
o Let's compare the properties of wood and materials such as metal and stone.
We come to the conclusion that wood is a light, durable material that is well processed by a cutting tool and has a beautiful appearance.
At the same time, we also reveal its negative qualities: easy flammability, warping during drying, decay.
o What tree species do you know and what types are they divided into? Deciduous and coniferous.
Trees that have foliage are called deciduous, and those that have needles are called conifers. To hardwood include birch, aspen, oak, alder, linden, etc.; to conifers - pine, spruce, cedar, fir, etc.
o What is a tree made of?
From a trunk, root, branches, leaves or needles Wood as a natural structural material is obtained from tree trunks when sawing them into pieces Fig.3
The tree trunk has a thicker part at the base and a thinner one at the top. The surface of the trunk (Fig. 3) is covered with bark (7). The bark - "clothing" for a tree, consists of an outer cork layer and an inner one - bast. The cork layer of the bark is dead. The bast layer (6) is a conductor of juices that feed the tree. The wood of the trunk consists of many layers, which are visible in the section as growth rings (4).
o What can you learn from them?
You can determine the age of a tree. The loose and soft center of the tree is the core (1). Heart-shaped rays extend from the core to the bark in the form of light shiny lines (2). They serve to conduct water, air and nutrients inside the Cambium tree (5) - a thin layer of living cells located between the bark and wood. Only as a result of the activity of the cambium does the formation of new cells occur. " Cambium"- from Latin" exchange"(nutrient).
To study the structure of wood, three main sections of the trunk are distinguished (Fig. 4). The section (1), passing perpendicular to the core of the trunk, is called the end. It is perpendicular to annual rings and fibers. The cut (2) passing through the core of the trunk is called radial. It is parallel to the annual layers and fibers. tangential cut(3) runs parallel to the core of the barrel and some distance away from it.
Wood species determined by their following characteristic features: texture, smell, hardness, color. (Show how to identify wood species from the poster.)
The disadvantages of wood are also defects: knotty(Fig. 5p), wormholes(Figure 5.6). They limit the use of wood in industrial production, but can be valuable in the manufacture of decorative items.
We turn to the consideration of lumber and wood-based materials.
When sawing tree trunks longitudinally on sawmill frames, various lumber is obtained (Fig. 6): beams (a, b), bars (c), boards (d, e), plates (e), quarters (g) and slabs (h)
Lumber has the following elements: face, edge, butt, edge. (Indicate on the poster. Plywood is widely used as a structural material.)
o How is it obtained?
By sticking three or more thin sheets of wood on top of each other - veneer. Veneer in translation from German - " sliver"The veneer is cut (peeled) with a sharp knife of a special peeling machine while rotating a log about 2.0 m long (Fig. 7). In this case, the log, like a roll, is rolled into a veneer tape. The veneer tape is cut into square sheets, which are dried in dryers, smeared with glue and stacked on top of each other so that the direction of the fibers in them was perpendicular to each other.The sheets are glued together under pressure.This is how plywood is obtained.
Plywood is stronger than wood, almost does not dry out and does not crack, bends well and is processed.
o Where is it used?
In construction, in the manufacture of furniture, in mechanical engineering, aircraft construction.
o You have probably heard the word chipboard, what does it mean?
Wood chipboards. They are obtained by pressing and gluing chopped wood in the form of shavings, sawdust, wood dust. Plates are made with a thickness of about 10-26 mm. They are durable, almost do not warp, are well processed by cutting tools.
o What are they made of?
Furniture, doors, partitions, walls, floors. However, over time, they release substances harmful to health, so it is undesirable to use them in residential premises.
o What is DVP?
Wood fiber boards. They are pressed in the form of sheets from steamed and crushed to individual fibers of wood pulp. They have a pleasant gray color, smooth surfaces, bend like plywood. They are used for interior decoration of premises: facing walls, ceilings, floors, in the manufacture of furniture, doors.
o What is the common disadvantage of plywood, chipboard and fiberboard?
They are afraid of dampness.
Sh. Practical part
1. Students cut a block of soft wood (pine, linden) along and across the fibers with an ordinary knife. As a result of this operation, they come to the conclusion that the wood is easily split along the fibers with little effort, and across it is impossible, even with great effort.
2. Students try to identify wood species from samples, consider samples of lumber, plywood, chipboard and fiberboard.
They check whether the samples are easily processed with any tool (file, hacksaw, etc.).
IV. Final part.
Summarize the lesson, mark the most active students during the discussion of the material.
Clean up the workshop.
Lesson number 7-8. Species of wood, parts of a tree. Types of lumber.
Liked? Please thank us! It's free for you, and it's a big help to us! Add our site to your social network:Anyone who works with wood, it is important to know what properties this material has. The concept of wood properties is closely related to its structure. A person with knowledge in this area will most efficiently and meaningfully carry out the process of processing wood, the process of storage, restoration of products from it. In particular, the master building must necessarily understand this. This article discusses the connection structure and physical and mechanical properties of wood.
Main cuts
The main sections are shown in the figure below. They have different properties and structures.
Main sections of a tree trunk:
1 - transverse (end), 2 - radial, 3 - tangential
cross section
The cut, perpendicular to the axis of the trunk and the direction of the fibers, forms the end, or, as it is called, the transverse secant plane of the trunk. In this section, it is clearly visible wood structure, namely concentric annual rings, core, core rays, section of the bark and bast. The cross section is shown in the figure:
Radial cut
The cut passing through the middle of the trunk along the direction of the wood fibers forms a radial secant plane. With such a cut growth rings are also visible, but not in the form of concentric rings, but in the form of parallel stripes.
tangential cut
The tangential cut, like the radial one, is directed along the fibers, but does not pass through the stem axis, but at some distance from it. In other words, this section is built along the chord of the cross section. In a tangential section, the annual rings look like parabolas elongated upwards, since the trunk with annual rings narrows upwards.
Structure elements
Let's take a closer look at each element in the cross section.
Cross section of the trunk: 1 - core, 2 - core rays, 3 - core, 4 - cork layer, 5 - bast layer, 6 - sapwood, 7 - cambium, 8 - annual layers
Nucleus
Nucleus wood- the central area in the trunk of a tree. In some breeds, this area is expressed implicitly. The core has a higher density compared to sapwood, since this layer does not take part in metabolic processes and does not perform transport functions. The most common core wood noticeable in cross section and has a darker color than sapwood. But there are exceptions, when the layers of wood are weakly exposed to any chemical changes for several years. However, in many trees the color of the core changes with age. Some species do not have a core at all and consist of only sapwood: birch, aspen.
Different wood species have different core colors. Here are some examples:
In the process of turning sapwood into a kernel in chemical composition wood some changes are taking place. Some substances disappear from the wood, and some are energetically deposited in the structure. For example, compounds of phosphoric acid and potassium, which are important for chemical processes, disappear, and starch also disappears. But, despite this, inorganic and organic substances are formed in the structure. For example, in the core of some species (elm, beech, beech), significant amounts of calcium carbonate are formed. In other rocks, amorphous silica is deposited in the core. Organic substances are also often found: resins, gums, tannins and dyes. Here are some examples of organic dyes obtained from one or another breed:
It can be concluded that wood core has properties that differ from those of sapwood: high strength and density, as well as other physical, mechanical and chemical properties breed dependent.
Sapwood
Sapwood, also known as sapwood or underbark, includes the outer young layers of wood that are physiologically active. Sapwood performs the function of transporting water and storing spare substances. In comparison with the core, sapwood has low strength, density, and is more easily attacked by insects and fungi. In industrial terms, sapwood contains a very useful material - a resinous thick mass "Sap".
Core
The core is wood, consisting of a loose, soft tissue. The core is located in the central part of the trunk. On a transverse section, it looks like a light or light brown spot of a rounded or star-shaped shape. Together with the primary wood, the core forms the core tube. Often, the beginnings of small knots depart from the core tube, which negatively affects the physical and mechanical properties.
core rays
Core rays - directed from the core to the cortex along the radii of the line. All breeds have such lines, but in some they are wide, and therefore noticeable to the naked eye. In a growing tree, heart-shaped rays serve as a means of transporting moisture in a horizontal direction. There are primary and secondary core rays. Primary divide the xylem part of the stem and root into radial sectors. Secondary ones do not reach the middle of the stem, that is, they arise in the growth rings of subsequent years.
Bark
The bark is divided into two layers: the bast layer and the cork layer.
The cork layer is the top layer of the cortex, which is an accumulation of dead cells. It is the most dense layer and performs a protective function. There were cases when it was the cork layer that protected the tree from the effects of the flame! It protects the tree from impact. adverse factors(decay, insects, etc.) In particular cases, the cork layer is a valuable material: cork oak bark has an amazing structure, the main property of which is the absence of intercellular space. This layer is periodically removed from the trunks, and after such a procedure, the tree does not die, but forms a new cork layer.
The bast layer is the inner layer of the bark, which performs the functions of both protecting and transporting the juices that feed the tree. By juice is meant a liquid with organic substances produced in the leaves. The bast layer is also used in the household, for example, the linden bast layer is used for weaving various things.
During construction, care should be taken when debarking and planing logs.
Cambium
Cambium is a layer between the bast layer and sapwood. Cambium gives rise to secondary conductive tissues and carries educational function, ensuring the growth of these tissues in width. The activity of the cambium, depending on the season, affects the formation of annual rings.
growth rings
growth rings(annual layers) - areas of cyclic tissue growth in trees. emergence annual rings It is caused by the uneven development of the organism, in combination with the influence of external factors. Each ring consists of two parts - light and dark. The number of rings on a saw cut indicates the age of the tree and its rate of growth, depending on the height at which the cross section was made. Tropical plants do not form growth rings because, due to climatic conditions, grow all year round.
