Measurement and accounting of felled trees
Each tree can be divided into three parts: trunk, branches and roots. The ratio of these parts to each other in terms of mass varies depending on the breed, age and growing conditions.
Rice. 6. Shape of trees (I) and cross-section of the trunk (II): 1 - tree grown in a dense forest; 2 - in a forest of medium density; 3 - in a sparse forest; AB - largest diameter; CD - smallest
But, as a rule, the stem part makes up the main woody mass, which increases with age.
Numerous observations have shown that in mature, closed stands the mass of stem wood is 60-85%, branches 5-25 and roots 5-30% of the total mass of the tree.
Table 1
The density of the tree stand has a very large influence on this ratio. The trunks in dense stands are taller and in shape in the first half of the tree they are close to a cylinder, in rare ones they are stunted and have a more conical shape, and the crowns are usually large and spreading (Fig. 6). For example, in oak trees grown in the wild in the form of lighthouses, the mass of branches at the age of 50-60 years reaches 50% or more. The trunk has the best development coniferous species: spruce, fir, larch and pine.
Taxation characteristics of a tree trunk.
At the bottom the trunk resembles a cylinder, at the top it resembles a cone. To determine the volume of a cylinder and cone, you need to know their height and base area, which can be calculated from its diameter. To determine the volume of a trunk, you need to know its shape, height (length) and thickness (diameter). These elements are the main taxation characteristics of the trunk, and all the others are derived from them. In cross-section, a tree never gives a circle, but only approaches it, but for practical purposes it is accepted as a circle without any special errors. It must be remembered that the diameter of the tree must always be measured very carefully, taking it as the average of two mutually perpendicular diameters or from the largest and smallest (see Fig. 6). When determining the height of a felled trunk, it is practically not the length of its axis that is measured, but the curve forming the trunk, since the resulting error is extremely negligible.
Determination of trunk volume.
A felled tree, cleared of twigs and branches, forms a whip or trunk. The volume of a trunk is always less than the volume of a cylinder and greater than the volume of a cone of the same height and base area. By gradually reducing the diameter of the cylinder, you can find one at which its volume is equal to the volume of a tree trunk of the same height. Numerous studies have established that this diameter is approximately the diameter of the middle of the trunk. Therefore, to determine the volume of the trunk, you need to measure its length with a tape measure or other measuring instrument and the diameter in the middle with a measuring fork, then use the measured diameter to calculate the area of the circle and multiply it by the length of the barrel. As a result, we obtain the volume of the measured trunk.
In table 1 shows data for determining the volume of the trunk based on the measured median diameter and height (length). In table 1 shows the most common heights and median diameters of trunks. It can be extended both in length and in diameter. This kind of table is often called cylinder volume tables. Using the table is very simple.
Example. It is required to determine the volume of two trunks with a length of 21 and 11 m with a median diameter of 17 and 12 cm, respectively. To determine the volume of the first trunk according to the table. 1 we find in the first column on the left the number 21 m and on this line a column with a diameter of 17 cm; where they intersect is the number 0.4767. This means that the required volume is 0.4767 m3. The volume of the second trunk is found at the intersection of line 11 and column 12 cm; it is equal to 0.1244 m3.
-It should be noted that when determining the volume by the median diameter, significant errors are possible and in most cases towards underestimation of the actual volume (sometimes over 10%), but the calculations are made easily and quickly and are quite acceptable for practical purposes. If the volume of the trunk needs to be calculated with greater accuracy, then it is divided into parts and for each of them the volume is determined by the median diameter and length. The shorter these parts are and the more they are cut out of the trunk, the more accurate the result can be obtained based on the total volume. Usually the trunk is divided into 2 sections (Fig. 7). The work is performed as follows. The trunk is marked using a tape measure on the 2nd segments with small notches in their middles, then in the places of the notches, the diameters are measured with a measuring fork and using the table. 1 and 2 find the volumes of all parts, the sum of which gives the volume of the trunk, excluding the top.
Rice. 7. Splitting the tree into 2nd sections
In table Figure 2 shows the volumes of the 2nd segments along the median diameter. The volume of a peak less than 2 m long is usually so small that it is practically not taken into account. The volume of the vertex is calculated using the formula for the volume of a cone - multiplying the area of the base by */3 of the height, i.e. the area of the base should be multiplied by the length and the resulting product divided by three. In table Figure 3 shows data for determining the required volume based on the measured diameter of the base of the apex and its length.
Example. You need to find the volume of a trunk 22 m long. The median diameters of the 2 segments are equal: the first (1 m from the bottom segment) 41; second (3 m) 37; third (5 m) 34; fourth (7 m) 31; fifth (9 m) 29; sixth (11 m) 27; the seventh (13 mU 24; the eighth (15 m) 21; the ninth (17 m) 17 and the tenth (19 m) 12 cm. The diameter of the base of the top (2 m long) is 8 cm.
It varies widely even for one type of wood. The values of the density (specific gravity) of wood are generalized figures. The practical value of wood density differs from the average given table value and this is not an error.
Table of density (specific gravity) of wood
depending on the type of wood
| "Handbook of masses of aviation materials" ed. "Mechanical Engineering" Moscow 1975 | Kolominova M.V., Guidelines for students of specialty 250401 “Forest Engineering”, Ukhta USTU 2010 | |||
| Wood species | Density wood, (kg/m3) |
Limit density wood, (kg/m3) |
Density wood, (kg/m3) |
Limit density wood, (kg/m3) |
| Ebony (black) |
1260 | 1260 | --- | --- |
| Backout (iron) |
1250 | 1170-1390 | 1300 | --- |
| Oak | 810 | 690-1030 | 655 | 570-690 |
| Mahogany | 800 | 560-1060 | --- | --- |
| Ash | 750 | 520-950 | 650 | 560-680 |
| Rowan (tree) | 730 | 690-890 | --- | --- |
| Apple | 720 | 660-840 | --- | --- |
| Beech | 680 | 620-820 | 650 | 560-680 |
| Acacia | 670 | 580-850 | 770 | 650-800 |
| Elm | 660 | 560-820 | 620 | 535-650 |
| Hornbeam | --- | --- | 760 | 740-795 |
| Larch | 635 | 540-665 | 635 | 540-665 |
| Maple | 650 | 530-810 | 655 | 570-690 |
| Birch | 650 | 510-770 | 620 | 520-640 |
| Pear | 650 | 610-730 | 670 | 585-710 |
| Chestnut | 650 | 600-720 | --- | --- |
| Cedar | 570 | 560-580 | 405 | 360-435 |
| Pine | 520 | 310-760 | 480 | 415-505 |
| Linden | 510 | 440-800 | 470 | 410-495 |
| Alder | 500 | 470-580 | 495 | 430-525 |
| Aspen | 470 | 460-550 | 465 | 400-495 |
| Willow | 490 | 460-590 | 425 | 380-455 |
| Spruce | 450 | 370-750 | 420 | 365-445 |
| Willow | 450 | 420-500 | --- | --- |
| Hazelnut | 430 | 420-450 | --- | --- |
| Walnut | --- | --- | 560 | 490-590 |
| Fir | 410 | 350-600 | 350 | 310-375 |
| Bamboo | 400 | 395-405 | --- | --- |
| Poplar | 400 | 390-590 | 425 | 375-455 |
- The table shows the density of wood at a humidity of 12%.
- The table indicators are taken from the “Handbook of Masses of Aviation Materials” ed. "Mechanical Engineering" Moscow 1975
- Corrected on March 31, 2014, according to the method:
Kolominova M.V., Physical properties wood: guidelines for students of specialty 250401 “Forest Engineering”, Ukhta: USTU, 2010
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It is generally accepted to indicate the density (specific gravity) of wood depending on the type of wood. The indicator is taken to be the average value of the specific gravity, obtained by summarizing the results of repeated practical measurements. In fact, two wood density tables are published here, taken from completely different sources. A small difference in the indicators clearly indicates the variability of the density (specific gravity) of wood. When analyzing the wood density values from the table above, it is worth paying attention to the differences between the indicators in the aviation reference book and the university manual. For objectivity, the wood density value from both documents is given. With the right for the reader to choose the priority of the importance of the original source.
Particularly surprising is the tabular density value larches- 540-665 kg/m3. Some online sources indicate the density of larch as 1450 kg/m3. It is not clear who to believe, which once again proves the uncertainty and unknown nature of the topic being raised. Larch is a fairly heavy material, but not so heavy as to sink like a stone in water.
The influence of humidity on the specific gravity of wood
Specific gravity of driftwood
It is noteworthy that with an increase in wood moisture content, the dependence of the specific gravity of this material on the type of wood decreases. The specific gravity of driftwood (humidity 75-85%) practically does not depend on the type of wood and is approximately 920-970 kg/m3. This phenomenon is explained quite simply. The voids and pores in the wood are filled with water, the density ( specific gravity) which is much higher than the density of the displaced air. In terms of its value, the density of water approaches the density of , the specific gravity of which practically does not depend on the type of wood. Thus, the specific gravity of pieces of wood soggy in water is less dependent on its species than in the case of dry samples. At this point it is worth remembering that for wood there is a division of classical physical concepts. (cm. )
Wood Density Groups
Conventionally, all tree species are divided into three groups
(according to the density of its wood, at a humidity of 12%):
- Low density rocks(up to 540 kg/m3) - spruce, pine, fir, cedar, juniper, poplar, linden, willow, aspen, black and white alder, chestnut, white, gray and Manchurian walnut, Amur velvet;
- Medium density rocks(550-740 kg/m3) - larch, yew, silver birch, downy, black and yellow, eastern and European beech, elm, pear, summer oak, eastern, swamp, Mongolian, elm, elm, maple, hazel, walnut , plane tree, rowan, persimmon, apple tree, common ash and Manchurian;
- High Density Rocks(750 kg/m3 and above) - white and sand acacia, iron birch, Caspian honey locust, white hickory, hornbeam, chestnut-leaved and Araxinian oak, ironwood, boxwood, pistachio, hop hornbeam.
Density of wood and its calorific value
The density (specific gravity) of wood is the main indicator of its heating properties. energy value- . The dependence here is direct. The higher the density of the wood structure of a tree species, the more combustible wood substance it contains and the hotter such trees are.
When starting to build a house or make renovations, sometimes you have to face questions that seem simple at first glance, but you can’t immediately answer them. It seems awkward to address such a question to specialists, but you need to know for sure. For those who can turn to the Internet, it’s easier - type in a search engine “How much does a cube of wood weigh” and in half a minute received a comprehensive result. By the way, really, how much?
The effect of humidity on the weight of wood
The weight of wood does not always have the same value. What does it depend on? First of all, from the moisture content of the wood. If we compare, for example, oak and birch, it turns out that a cubic meter of oak weighs 700 kg, and a birch weighs 600 kg. But it could be different. Weighing a cubic meter of birch, we get 900 kg, and oak will show the same 700. Or in both cases it will be 700 kg. Why do we get such different numbers? In this case, the moisture content of the wood plays a role.
There are four degrees of humidity: dry (10-18%), air-dry (19-23%), damp (24-45%) and wet (above 45%). Thus, it turns out that different rocks with the same humidity have different weights, as in the first example above. If the humidity is not the same, then the weight may fluctuate in one direction or another. The standard humidity is 12%.
Different density - different weight
Another factor that affects the weight of wood is its density. The highest density is found in iron and ebony wood - from 1100 to 1330 kg/m3. Boxwood and bog oak are close to them - 950-1100. For ordinary oak, beech, acacia, pear, and hornbeam, the density is about 700 kg/m3. It is even lower for pine, alder, and bamboo - 500 kg/m3. And the lowest is for cork wood, only 140 kg/m3.
Why do you need to know the weight of a cubic meter of wood?
Having knowledge in this area is sometimes very important. By purchasing building material, its quantity is impossible for a non-specialist to determine by eye. Knowing the dimensions of the timber or lining, the material from which they are made and its moisture content, simple calculations allow you to determine the weight of the purchased product. How much does a cube of wood weigh? In this case, the answer to this question will help you figure out whether the seller sent you the goods correctly.
Heat transfer from wood
In addition, there is another indicator - heat transfer. It will come to the aid of those who use wood as firewood for heating. The higher the hardness, i.e. The density of the wood species, the higher its calorific value. Of course, no one will heat a room with boxwood, but when choosing between linden and pine or birch and acacia, you can get much more heat if you know which of these species is the hardest. Information about the density of each tree can be gleaned from the tables, since all this information is systematized for ease of use.
Weight of a dense cubic meter, kg
| Breed | Humidity, % | |||||||||||
| 10 | 15 | 20 | 25 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 | |
| Beech | 670 | 680 | 690 | 710 | 720 | 780 | 830 | 890 | 950 | 1000 | 1060 | 1110 |
| Spruce | 440 | 450 | 460 | 470 | 490 | 520 | 560 | 600 | 640 | 670 | 710 | 750 |
| Larch | 660 | 670 | 690 | 700 | 710 | 770 | 820 | 880 | 930 | 990 | 1040 | 1100 |
| Aspen | 490 | 500 | 510 | 530 | 540 | 580 | 620 | 660 | 710 | 750 | 790 | 830 |
| Birch: | ||||||||||||
| - fluffy | 630 | 640 | 650 | 670 | 680 | 730 | 790 | 840 | 890 | 940 | 1000 | 1050 |
| - ribbed | 680 | 690 | 700 | 720 | 730 | 790 | 850 | 900 | 960 | 1020 | 1070 | 1130 |
| - Daurian | 720 | 730 | 740 | 760 | 780 | 840 | 900 | 960 | 1020 | 1080 | 1140 | 1190 |
| - iron | 960 | 980 | 1000 | 1020 | 1040 | 1120 | 1200 | 1280 | — | — | — | — |
| Oak: | ||||||||||||
| - petiolate | 680 | 700 | 720 | 740 | 760 | 820 | 870 | 930 | 990 | 1050 | 1110 | 1160 |
| - eastern | 690 | 710 | 730 | 750 | 770 | 830 | 880 | 940 | 1000 | 1060 | 1120 | 1180 |
| — Georgian | 770 | 790 | 810 | 830 | 850 | 920 | 980 | 1050 | 1120 | 1180 | 1250 | 1310 |
| - Araksinian | 790 | 810 | 830 | 850 | 870 | 940 | 1010 | 1080 | 1150 | 1210 | 1280 | 1350 |
| Pine: | ||||||||||||
| - cedar | 430 | 440 | 450 | 460 | 480 | 410 | 550 | 580 | 620 | 660 | 700 | 730 |
| - Siberian | 430 | 440 | 450 | 460 | 480 | 410 | 550 | 580 | 620 | 660 | 700 | 730 |
| - ordinary | 500 | 510 | 520 | 540 | 550 | 590 | 640 | 680 | 720 | 760 | 810 | 850 |
| Fir: | ||||||||||||
| - Siberian | 370 | 380 | 390 | 400 | 410 | 440 | 470 | 510 | 540 | 570 | 600 | 630 |
| - white-haired | 390 | 400 | 410 | 420 | 430 | 470 | 500 | 530 | 570 | 600 | 630 | 660 |
| - whole leaf | 390 | 400 | 410 | 420 | 430 | 470 | 500 | 530 | 570 | 600 | 630 | 660 |
| - white | 420 | 430 | 440 | 450 | 460 | 500 | 540 | 570 | 610 | 640 | 680 | 710 |
| - Caucasian | 430 | 440 | 450 | 460 | 480 | 510 | 550 | 580 | 620 | 660 | 700 | 730 |
| Ash: | ||||||||||||
| - Manchurian | 640 | 660 | 680 | 690 | 710 | 770 | 820 | 880 | 930 | 990 | 1040 | 1100 |
| - ordinary | 670 | 690 | 710 | 730 | 740 | 800 | 860 | 920 | 980 | 1030 | 1090 | 1150 |
| - acute-fruited | 790 | 810 | 830 | 850 | 870 | 940 | 1010 | 1080 | 1150 | 1210 | 1280 | 1350 |
The table shows average mass values. Possible maximum and minimum mass values are 1.3 and 0.7, respectively, from its average value
WEIGHT OF 1 CUBIC METER (VOLUMERIUM WEIGHT) OF BEAM, BOARDS AND LOODS
The weight of lumber (timbers, boards, logs), moldings (linings, platbands, baseboards, etc.) and other wood products depends mainly on the moisture content of the wood and its species.The table shows the weight of 1 cubic meter of wood (volume weight) depending on the type of wood and its moisture content.
Weight table 1 cu. m (volume weight) timber, boards, linings made of wood of various species and humidity
Depending on the moisture content, measured as a percentage of the mass of water contained in the wood to the mass of dry wood, wood is divided into the following moisture categories:
Dry wood (humidity 10-18%) is wood that has undergone technological drying or has been stored for a long time in a warm, dry room;
Air-dry wood (humidity 19-23%) is wood with equilibrium moisture content, when the moisture content of the wood itself is balanced with the humidity of the surrounding air. This level of humidity is achieved at long-term storage wood in natural conditions, i.e. without the use of special drying technologies;
Green wood (humidity 24-45%) is wood that is in the process of drying from a freshly cut state to equilibrium;
Freshly cut and wet wood (moisture content greater than 45%) is wood that has been recently cut or has been in water for a long time.
WEIGHT OF ONE BEAM, ONE EDGED AND FLOORBOARD, LINING
The weight of one beam, board or any molded product also depends on the moisture content of the wood from which they are made and its species. The table shows data for the wood most used in construction - pine with damp moisture for timber and edged boards and air-dry humidity for floorboards and linings.Weight table for one beam, one board and lining
NUMBER OF BOOTS, BOARDS AND LINING IN 1 CUBIC. M
The number of pieces of any lumber or molded product in 1 cubic meter depends on its dimensions: width, thickness and length. Data on the quantity of lumber in 1 kb. m are presented in the table.When organizing timber transportation, the density of the tree is an important indicator when selecting a timber truck and calculating the cost of transportation. This will help avoid overloading, which will consequently prevent you from being fined.
The density of the material has a special significance on the weight of m3 of wood; accordingly, in order to correctly solve the questions posed, it is necessary to determine the value of the density. There are two types of density: volumetric weight(density of the structured physical body) and specific gravity(density of wood substance).
Volumetric weight of wood
The weight of a cubic meter of wood depends on the type of wood and humidity.Calculator for calculating the volumetric weight of wood.
Tree White Acacia Birch Beech Elm Oak Hornbeam Spruce Maple Linden Larch Alder Walnut Aspen Siberian Fir Caucasian Fir Scots Pine Cedar Pine Poplar Common Ash
Volume, m 3:
Specific gravity of wood
Wood substance is a mass of solid wood materials without natural voids. This type of density is measured in laboratory conditions, as it requires additional measurements that are impossible under normal conditions. For each wood of all types and species of trees, this value is constant and amounts to 1540 kg/m3. However, wood has a multicellular fibrous structure of a complex type. Walls made of wood substance play the role of a frame in the structure of wood. Accordingly, for each tree species and species, the cellular structures, shapes and sizes of cells vary, as a result of which the specific gravity of the tree will be different, as well as the different weight of m3 of the tree.
Also, humidity plays a big role in changing the specific gravity of wood. Due to the structure of this material, with increasing humidity, the density of wood also increases. However, this rule does not apply to the density of wood substances.
| № | Wood species | Humidity percentage, % | ||||||||||
| 15 | 20 | 25 | 30 | 40 | 50 | 60 | 70 | 80 | 100 | Fresh* | ||
| 1 | Larch | 670 | 690 | 700 | 710 | 770 | 820 | 880 | 930 | 990 | 1100 | 940 |
| 2 | Poplar | 460 | 470 | 480 | 500 | 540 | 570 | 610 | 650 | 690 | 760 | 700 |
| 3 | Beech | 680 | 690 | 710 | 720 | 780 | 830 | 890 | 950 | 1000 | 1110 | 960 |
| 4 | Elm | 660 | 680 | 690 | 710 | 770 | 820 | 880 | 930 | 990 | 1100 | 940 |
| 5 | Oak | 700 | 720 | 740 | 760 | 820 | 870 | 930 | 990 | 1050 | 1160 | 990 |
| 6 | Hornbeam | 810 | 830 | 840 | 860 | 930 | 990 | 1060 | 1130 | 1190 | 1330 | 1060 |
| 7 | Norway spruce | 450 | 460 | 470 | 490 | 520 | 560 | 600 | 640 | 670 | 750 | 740 |
| 8 | Walnut | 600 | 610 | 630 | 650 | 700 | 750 | 800 | 850 | 900 | 1000 | 910 |
| 9 | Linden | 500 | 530 | 540 | 540 | 580 | 620 | 660 | 710 | 750 | 830 | 760 |
| 10 | White acacia | 810 | 830 | 840 | 860 | 930 | 990 | 1060 | 1190 | 1300 | 1330 | 1030 |
| 11 | Alder | 530 | 540 | 560 | 570 | 620 | 660 | 700 | 750 | 790 | 880 | 810 |
| 12 | Maple | 700 | 720 | 740 | 760 | 820 | 870 | 930 | 990 | 1050 | 1160 | 870 |
| 13 | Common ash | 690 | 710 | 730 | 740 | 800 | 860 | 920 | 930 | 1030 | 1150 | 960 |
| 14 | Siberian fir | 380 | 390 | 400 | 410 | 440 | 470 | 510 | 540 | 570 | 630 | 680 |
| 15 | Scots pine | 510 | 520 | 540 | 550 | 590 | 640 | 680 | 720 | 760 | 850 | 820 |
| 16 | Caucasian fir | 440 | 450 | 460 | 480 | 510 | 550 | 580 | 620 | 660 | 730 | 720 |
| 17 | Cedar pine | 440 | 450 | 460 | 480 | 510 | 550 | 580 | 620 | 660 | 730 | 760 |
| 18 | Birch | 640 | 650 | 670 | 680 | 730 | 790 | 840 | 890 | 940 | 1050 | 870 |
| 19 | Aspen | 500 | 510 | 530 | 540 | 580 | 620 | 660 | 710 | 750 | 830 | 760 |
* Fresh. - Freshly cut tree