Ash composition of wood of various tree species in the floodplain biotope. Properties of firewood of different species: indicators of wood quality Alternative fuel materials

Firewood- pieces of wood that are intended to be burned in stoves, fireplaces, furnaces or bonfires to produce heat, heat and light.

fireplace wood are mainly harvested and supplied in sawn and chipped form. The moisture content should be as low as possible. The length of the logs is mainly 25 and 33 cm. Such firewood is sold in bulk stock meters or packaged and sold by weight.

Various woods are used for heating purposes. The priority characteristic, according to which one or another firewood for fireplaces and stoves is chosen, is their calorific value, burning duration and comfort when using (flame pattern, smell). For heating purposes, it is desirable that heat release occurs more slowly, but more long time. For heating purposes, all hardwood firewood is best suited.

For furnaces and fireplaces, mainly firewood of such species as oak, ash, birch, hazel, yew, hawthorn is used.

Features of burning firewood of different types of wood:

Firewood from beech, birch, ash, hazel is difficult to melt, but they can burn damp because they have little moisture, and firewood from all these tree species, except beech, easily splits;

Alder and aspen burn without the formation of soot, moreover, they burn it out of the chimney;

Birch firewood is good for heat, but with a lack of air in the furnace, it burns smoky and forms tar (birch resin), which settles on the walls of the pipe;

Stumps and roots give an intricate fire pattern;

Branches of juniper, cherry and apple give a pleasant aroma;

Pine wood burns hotter than spruce wood due to the higher resin content. When burning tarred firewood, a sharp increase in temperature with a crack bursts small cavities in the wood, in which resin accumulates, and sparks fly in all directions;

Oak firewood has the best heat dissipation, their only drawback is that they do not split well, just like firewood from a hornbeam;

Firewood from pear and apple trees splits easily and burns well, emitting a pleasant smell;

Medium hardwood firewood is generally easy to split;

Long smoldering coals give firewood from cedar;

Cherry and elm wood smokes when burned;

Sycamore firewood is easily melted, but it is hard to prick;

Softwood firewood is less suitable for firing because it contributes to the formation of tar deposits in the pipe and has a low calorific value. Pine and spruce firewood is easy to chop and melt, but it smokes and sparks;

Poplar, alder, aspen, linden are also referred to tree species with soft wood. Firewood of these species burns well, poplar firewood sparks strongly and burns out very quickly;

Beech - firewood of this breed is considered classic fireplace wood, as beech has a beautiful flame pattern and good heat development with almost no sparks. To all of the above, it should be added - beech firewood has a very high calorific value. The smell of burning beech firewood is also highly appreciated - therefore, beech firewood is mainly used for smoking products. Beech firewood is versatile in use. Based on the above, the cost of beech firewood is high.

It is necessary to take into account the fact that the calorific value of firewood of different types of wood fluctuates greatly. As a result, we get fluctuations in the density of wood and fluctuations in the conversion factors cubic meter => warehouse meter.

Below is a table with average values of calorific value per firewood storage meter.

Firewood (natural drying)	Calorific value kWh/kg	Calorific value mega Joule/kg	Calorific value Mwh./ warehouse meter	Bulk density in kg/dm³	Density kg/ warehouse meter
Hornbeam firewood	4,2	15	2,1	0,72	495
Beech firewood	4,2	15	2,0	0,69	480
Ash wood	4,2	15	2,0	0,69	480
oak firewood	4,2	15	2,0	0,67	470
birch firewood	4,2	15	1,9	0,65	450
Larch firewood	4,3	15,5	1,8	0,59	420
Pine firewood	4,3	15,5	1,6	0,52	360
Spruce firewood	4,3	15,5	1,4	0,47	330

1 dry wood storage meter deciduous trees replaces about 200 to 210 liters of liquid fuel or 200 to 210 m³ of natural gas.

Tips for choosing wood for a fire.

There will be no fire without firewood. As I said, in order for the fire to burn for a long time, you need to prepare for this. Prepare firewood. The bigger, the better. You don’t need to overdo it, but you need to have a small margin just in case. After spending two or three nights in the forest, you will probably be able to more accurately determine the required supply of firewood for the night. Of course, it is possible to mathematically calculate how much wood is needed to keep a fire burning for a given number of hours. Convert knots of one thickness or another to cubic meters. But in practice, this calculation will not always work. There are a lot of factors that cannot be calculated, and if you try, the spread will be quite large. Only personal practice gives more accurate results.

A strong wind increases the burning rate by 2-3 times. Wet, calm weather, on the contrary, slows down combustion. The fire can burn even during the rain, only for this it is necessary to constantly maintain it. When it rains, do not put thick logs in the fire, they flare up longer and the rain can simply extinguish them. Do not forget, thinner branches flare up quickly, but they also burn out quickly. They need to be used to kindle thicker branches.

Before talking about some of the species properties of wood during burning, I want to remind you once again that if you are not forced to spend the night in the immediate vicinity of the fire, try to burn the fire no closer than 1-1.5 meters from the edge of your bed.

Most often we meet the following tree species: spruce, pine, fir, larch, birch, aspen, alder, oak, bird cherry, willow. So, in order.

Spruce, like all resinous tree species, it burns hot, fast. If the wood is dry, the fire spreads quickly over the surface. If you have no way to somehow divide the trunk of a small tree into relatively small equal parts, and you use the whole tree for a fire, be very careful. Fire, on a tree, can go beyond the border of the fire and cause a lot of trouble. In this case, clear enough space under the fireplace so that the fire cannot spread further. Spruce has the ability to "shoot". During combustion, the resin that is in the wood, under the influence of high temperatures, begins to boil, and finding no way out, it explodes. A piece of burning wood that is upstairs flies away from the fire. Probably many who burned a fire, noticed this phenomenon. To protect yourself from such surprises, it is enough to put the logs end to you. The coals usually fly perpendicular to the barrel.

Pine. Burns hotter and eats faster. It breaks easily if the tree is no more than 5-10 cm thick in diameter. "Shoots." Thin dry branches are well suited as firewood of the second and third plan for kindling a fire.

Fir. Home distinctive feature is that it practically does not "shoot". Dead wood trunks with a diameter of 20-30 cm are very suitable for "nody", a fire for the whole night. Burns hot and evenly. Burning rate between spruce and pine.

Larch. This tree, unlike other trees of resinous species, sheds needles for the winter. The wood is denser and stronger. It burns for a long time, ate longer, evenly. Gives a lot of heat. If you find a piece of dry larch on the river bank, there is a possibility that before this piece hit the shore, it lay in the water for some time. Such a tree will burn much longer than usual, from the forest. A tree, being in water, without access to oxygen, becomes denser and stronger. Of course, it all depends on how long you've been in the water. After lying there for several decades, it will turn into dust.

Properties of wood for the firebox

Wood suitable for firebox is divided into the following main categories:

Coniferous wood	Hardwood *soft rocks*	Hardwood Hard rocks
Pine, spruce, thuja and others	Linden, aspen, poplar and others	Oak, birch, hornbeam and others
They are distinguished by a high content of resin, which does not burn out completely and clogs the chimney and the internal parts of the furnace with its residues. When using such fuel, the formation of soot on the glass of the fireplace, if any, is inevitable. For this type of fuel, a longer drying of firewood is characteristic.	Due to the low density, firewood from such species burns quickly, does not form coal, and has a low specific calorific value.	Firewood from such types of wood provides a stable working temperature in the firebox and high specific calorific value

When choosing a fuel for a fireplace or stove, the moisture content of the wood is of great importance. The calorific value of firewood depends to a greater extent on humidity. It is generally accepted that the best way firewood suitable for firewood with a moisture content of not more than 25%. The calorific value indicators (the amount of heat released during the complete combustion of 1 kg of firewood, depending on humidity) are indicated in the table below:

Firewood for the firebox must be prepared carefully and in advance. good firewood should dry for at least a year. The minimum drying time depends on the month of laying the woodpile (in days):

Another important indicator that characterizes the quality of firewood for a fireplace or stove is the density or hardness of the wood. Hardwood has the highest heat transfer, soft wood has the lowest. Wood density indicators at 12% moisture content are shown in the table below:

Specific calorific value of wood of various species.

The calorific value of a wood substance of any species and any density in an absolutely dry state is determined by the number 4370 kcal / kg. It is also believed that the degree of rotten wood has practically no effect on the calorific value.

There are concepts of volumetric calorific value and mass calorific value. The volumetric calorific value of firewood is a rather unstable value, depending on the density of the wood and, therefore, on the type of wood. After all, each breed has its own density, moreover, the same breed from different areas can vary in density.

It is most convenient to determine the calorific value of firewood by mass calorific value depending on humidity. If the moisture content (W) of the samples is known, then their calorific value (Q) can be determined with a certain degree of error using a simple formula:

Q (kcal / kg) \u003d 4370 - 50 * W

According to moisture content, wood can be divided into three categories:

room-dry wood, humidity from 7% to 20%;
air-dry wood, humidity from 20% to 50%;
driftwood, humidity from 50% to 70%;

Table 1. Volumetric calorific value of firewood depending on humidity.

Breed	Calorific value, kcal / dm 3, with humidity,%			Calorific value, kW h / m 3, with humidity,%
Breed	12%	25%	50%	12%	25%	50%
Oak	3240	2527	1110	3758	2932	1287
Larch	2640	2059	904	3062	2389	1049
Birch	2600	2028	891	3016	2352	1033
Cedar	2280	1778	781	2645	2063	906
Pine	2080	1622	712	2413	1882	826
Aspen	1880	1466	644	2181	1701	747
Spruce	1800	1404	617	2088	1629	715
Fir	1640	1279	562	1902	1484	652
Poplar	1600	1248	548	1856	1448	636

Table 2. Estimated mass calorific value of firewood depending on humidity.

Humidity degree, %	Calorific value, kcal/kg	Calorific value, kWh/kg
7	4020	4.6632
8	3970	4.6052
9	3920	4.5472
10	3870	4.4892
11	3820	4.4312
12	3770	4.3732
13	3720	4.3152
14	3670	4.2572
15	3620	4.1992
16	3570	4.1412
17	3520	4.0832
18	3470	4.0252
19	3420	3.9672
20	3370	3.9092
21	3320	3.8512
22	3270	3.7932
23	3220	3.7352
24	3170	3.6772
25	3120	3.6192
26	3070	3.5612
27	3020	3.5032
28	2970	3.4452
29	2920	3.3872
30	2870	3.3292
31	2820	3.2712
32	2770	3.2132
33	2720	3.1552
34	2670	3.0972
35	2620	3.0392
36	2570	2.9812
37	2520	2.9232
38	2470	2.8652
39	2420	2.8072
40	2370	2.7492
41	2320	2.6912
42	2270	2.6332
43	2220	2.5752
44	2170	2.5172
45	2120	2.4592
46	2070	2.4012
47	2020	2.3432
48	1970	2.2852
49	1920	2.2272
50	1870	2.1692
51	1820	2.1112
52	1770	2.0532
53	1720	1.9952
54	1670	1.9372
55	1620	1.8792
56	1570	1.8212
57	1520	1.7632
58	1470	1.7052
59	1420	1.6472
60	1370	1.5892
61	1320	1.5312
62	1270	1.4732
63	1220	1.4152
64	1170	1.3572
65	1120	1.2992
66	1070	1.2412
67	1020	1.1832
68	970	1.1252
69	920	1.0672
70	870	1.0092

Firewood is the most ancient and traditional source of thermal energy, which belongs to a renewable type of fuel. By definition, firewood is pieces of wood that are proportionate to the hearth and are used to build and maintain a fire in it. In terms of quality, firewood is the most unstable fuel in the world.

However, the weight percentage composition of any wood mass is approximately the same. It includes - up to 60% cellulose, up to 30% lignin, 7...8% associated hydrocarbons. The rest (1...3%) -

State standard for firewood

On the territory of Russia operates
GOST 3243-88 Firewood. Specifications
Download (downloads: 1689)

The standard of the times of the Soviet Union defines:

Assortment of firewood by size
Permissible amount of rotten wood
Assortment of firewood by calorific value
The method of accounting for the amount of firewood
Requirements for transportation and storage
wood fuel

Of all the GOST information, the most valuable is the methods for measuring wood stacks and the coefficients for converting values from a folding measure to a dense measure (from a warehouse meter to a cubic meter). In addition, there is still some interest in the fad on limiting heartwood and sap rot (no more than 65% of the butt area), as well as a ban on external rot. It's just hard to imagine such rotten firewood in our space age of the pursuit of quality.

As regards the calorific value,
then GOST 3243-88 divides all firewood into three groups:

Firewood accounting

To account for any material value, the most important thing is the ways and methods of counting its quantity. The amount of firewood can be taken into account, either in tons and kilograms, or in storage and cubic meters and decimetres. Accordingly - in mass or volume units

Accounting for firewood in mass units
(in tons and kilograms)
This method of accounting for wood fuel is used extremely rarely due to its bulkiness and sluggishness. It is borrowed from builders-woodworkers and is alternative method for those cases when firewood is easier to weigh than to determine their volume. So, for example, sometimes in the case of wholesale deliveries of wood fuel, it is easier to weigh wagons and timber trucks shipped “on top” than to determine the volume of shapeless wood “caps” towering on them.
Advantages

- ease of processing information for further calculation of the total calorific value of the fuel in heat engineering calculations. Because, the calorific value of a weight measure of firewood is calculated according to and is practically unchanged for any type of wood, regardless of its geographical location and degree. Thus, when taking into account firewood in mass units, the net weight of combustible material is taken into account minus the weight of moisture, the amount of which is determined by a moisture meter
Flaws
accounting for firewood in mass units
- the method is absolutely unacceptable for measuring and accounting for batches of firewood in field conditions logging, when the required special equipment (scales and moisture meter) may not be at hand
- the result of measuring humidity soon becomes irrelevant, the firewood quickly becomes damp or dries up in the air
Accounting for firewood in volumetric units of measurement
(in folding and cubic meters and decimeters)
This method of accounting for wood fuel is the most widely used, as the simplest and most fast way accounting for wood fuel mass. Therefore, accounting for firewood is everywhere carried out in volumetric units of measurement - warehouse meters and cubic meters (fold and dense measures)
Advantages
accounting for firewood in volume units
- extreme simplicity in the execution of measurements of wood stacks with a linear meter
- the measurement result is easily controlled, remains unchanged for a long time and does not raise doubts
- the methodology for measuring wood batches and the coefficients for converting values from a folding measure to a dense measure are standardized and set out in
Flaws
accounting for firewood in mass units
- the price for the ease of accounting for firewood in volume units is the complication of further thermotechnical calculations to calculate the total calorific value of wood fuel (you need to take into account the type of wood, its place of growth, the degree of rottenness of firewood, etc.)

Calorific value of firewood

calorific value of firewood
she is the heat of combustion of firewood,
she is the calorific value of firewood

How is the calorific value of firewood different from the calorific value of wood?

The calorific value of wood and the calorific value of firewood are related and close in value quantities identified in Everyday life with the concepts of "theory" and "practice". In theory, we study the calorific value of wood, but in practice we are dealing with the calorific value of firewood. At the same time, real wood logs can have a much wider range of deviations from the norm than laboratory samples.

For example, real firewood has bark, which is not wood in the truest sense of the word, and yet it occupies volume, participates in the process of burning firewood and has its own calorific value. Often, the calorific value of the bark is significantly different from the calorific value of the wood itself. In addition, real firewood can be, have different wood density depending on, have a large percentage, etc.

Thus, for real firewood, the calorific value indicators are generalized and slightly underestimated, since for real firewood, all negative factors that reducetheir calorific value. This explains the difference in the smaller side in magnitude between the theoretically calculated values of the calorific value of wood and the practically applied values of the calorific value of firewood.

In other words, theory and practice are two different things.

The calorific value of firewood is the amount of useful heat generated during their combustion. Useful heat refers to the heat that can be taken away from the hearth without compromising the combustion process. The calorific value of firewood is the most important indicator of the quality of wood fuel. The calorific value of firewood can vary widely and depends, first of all, on two factors - the wood itself and its.

The calorific value of wood depends on the amount of combustible wood substance present in a unit mass or volume of wood. (more details about the calorific value of wood in the article -)
The moisture content of wood depends on the amount of water and other moisture present in a unit of mass or volume of wood. (more details about wood moisture in the article -)

Table of volumetric calorific value of firewood

Gradation of calorific value according to
(at wood moisture content 20%)

wood species	specific calorific value of firewood (kcal / dm 3)
Birch	1389...2240	First group according to GOST 3243-88: birch, beech, ash, hornbeam, elm, elm, maple, oak, larch
beech	1258...2133
ash	1403...2194
hornbeam	1654...2148
elm	not found (analogue - elm)
elm	1282...2341
maple	1503...2277
oak	1538...2429
larch	1084...2207
pine	1282...2130	Second group according to GOST 3243-88: pine, alder
alder	1122...1744	Second group according to GOST 3243-88: pine, alder
spruce	1068...1974	Third group according to GOST 3243-88: spruce, cedar, fir, aspen, linden, poplar, willow
cedar	1312...2237
fir	not found (analogue - spruce)
aspen	1002...1729
Linden	1046...1775
poplar	839...1370
willow	1128...1840

Calorific value of rotten wood

Absolutely true is the statement that rot worsens the quality of firewood and reduces their calorific value. But how much the calorific value of rotten firewood decreases is a question. Soviet GOST 2140-81 and determine the methodology for measuring the size of rot, limit the amount of rot in a log and the number of rotten logs in a batch (no more than 65% of the butt area and no more than 20% of the total mass, respectively). But, at the same time, the standards do not indicate a change in the calorific value of the firewood themselves.

It's obvious that within the requirements of GOSTs there is no significant change in the total calorific value of the wood mass due to rot, therefore, individual rotten logs can be safely neglected.

If there is more rot than is permissible according to the standard, then it is advisable to take into account the calorific value of such firewood in units of measurement. Because, when wood rots, processes occur that destroy the substance and disrupt its cellular structure. At the same time, accordingly, wood decreases, which primarily affects its weight and practically does not affect its volume. Thus, mass units of calorific value will be more objective for taking into account the calorific value of very rotten firewood.

By definition, the mass (weight) calorific value of firewood is practically independent of their volume, wood species and degree of rottenness. And, only the moisture content of wood - has a great influence on the mass (weight) calorific value of firewood

The calorific value of a weight measure of rotten and rotten firewood is almost equal to the calorific value of a weight measure of ordinary firewood and depends only on the moisture content of the wood itself. Because, only the weight of water displaces the weight of combustible wood substance from the weight measure of firewood, plus heat loss for water evaporation and heating of water vapor. Which is exactly what we need.

Calorific value of firewood from different regions

Volumetric calorific value of firewood for the same tree species growing in different regions may differ due to changes in the density of wood depending on the water saturation of the soil in the growing area. Moreover, it does not have to be different regions or regions of the country. Even within small area(10 ... 100 km) of logging, the calorific value of firewood for the same wood species can vary with a difference of 2 ... 5% due to changes in wood. This is explained by the fact that in a dry area (under conditions of lack of moisture) a finer and denser cellular structure of wood grows and forms than in water-rich marshy land. Thus, the total amount of combustible substance per unit volume will be higher for firewood harvested in drier areas, even for the same logging area. Of course, the difference is not so great, about 2...5%. However, with large firewood harvesting, this can have a real economic effect.

The mass calorific value for firewood from the same type of wood growing in different regions will not differ at all, since the calorific value does not depend on the density of the wood, but depends only on its moisture content

Ash | Ash content of firewood

Ash is a mineral substance that is contained in firewood and which remains in the solid residue after the complete combustion of the wood mass. The ash content of firewood is the degree of their mineralization. The ash content of firewood is measured as a percentage of the total mass of wood fuel and indicates the quantitative content of mineral substances in it.

Distinguish between internal and external ash

Inner ash	outer ash
Inner ash is a mineral substance that is found directly in	External ash is mineral substances that have entered the firewood from outside (for example, during harvesting, transportation or storage)
Internal ash is a refractory mass (above 1450 ° C), which is easily removed from the high-temperature fuel combustion zone	External ash is a low-melting mass (less than 1350 ° C), which is sintered into slag, sticking to the lining of the combustion chamber of the heating unit. As a result of such sintering and sticking, external ash is poorly removed from the high-temperature fuel combustion zone.
The internal ash content of the wood substance is in the range from 0.2 to 2.16% of the total wood mass	The content of external ash can reach 20% of the total wood mass
Ash is an undesirable part of the fuel, which reduces its combustible component and makes it difficult to operate heating units.

The moisture content of woody biomass is a quantitative characteristic showing the content of moisture in the biomass. There are absolute and relative humidity of biomass.

Absolute humidity is the ratio of the mass of moisture to the mass of dry wood:

Wa=t~t° 100,

Where Noa - absolute humidity,%; m is the weight of the sample in the wet state, g; m0 is the mass of the same sample dried to a constant value, g.

Relative or working humidity is the ratio of the mass of moisture to the mass of wet wood:

Where Wp - relative, or working, humidity, 10

The conversion of absolute humidity into relative humidity and vice versa is carried out according to the formulas:

Ash is subdivided into internal, contained in the wood substance, and external, which got into the fuel during the harvesting, storage and transportation of biomass. Depending on the type of ash has a different fusibility when heated to high temperature. Low-melting ash is called, having a temperature of the beginning of the liquid-melting state below 1350 °. Medium-melting ash has a temperature of the beginning of the liquid-melting state in the range of 1350-1450 ° C. For refractory ash, this temperature is above 1450 °C.

The inner ash of woody biomass is refractory, while the outer ash is fusible. The ash content in various parts of trees of various species is shown in Table. 4.

Ash content of stem wood. The content of internal ash of stem wood varies from 0.2 to 1.17%. Based on this, in accordance with the recommendations on the normative method of thermal calculation of boiler units in the calculations of combustion devices, the ash content of stemwood of all species should be taken equal to 1% of dry mass

4. Distribution of ash in parts of a tree for various species

	Amount of ash in absolutely dry mass, %

			Branches, branches, roots

Wood. This is justified if the ingress of mineral inclusions into the chopped stem wood is excluded.

Ash content of the bark. The ash content of the bark is greater than the ash content of the stem wood. One of the reasons for this is that the surface of the bark is constantly blown by atmospheric air during the growth of the tree and captures the mineral aerosols contained in it.

According to the observations carried out by TsNIIMOD for driftwood under the conditions of Arkhangelsk sawmills and woodworking enterprises, the ash content of barking waste was

In spruce 5.2, in pine 4.9% - The increase in the ash content of the bark in this case is explained by contamination of the bark during the rafting of whips along the rivers.

The ash content of the bark of various species per dry weight, according to A. I. Pomeransky, is: pine 3.2%, spruce 3.95, birch 2.7, alder 2.4%. According to NPO CKTI im. II Pol - Zunova, the ash content of the bark of various rocks varies from 0.5 to 8%.

Ash content of crown elements. The ash content of crown elements exceeds the ash content of wood and depends on the type of wood and its place of growth. According to V. M. Nikitin, the ash content of the leaves is 3.5%. Branches and branches have an internal ash content of 0.3 to 0.7%. However, depending on the type of technological process of wood harvesting, their ash content changes significantly due to contamination with external mineral inclusions. Pollution of branches and branches in the process of harvesting, skidding and hauling is most intense in wet weather in spring and autumn.

Density. The density of a material is characterized by the ratio of its mass to volume. When studying this property in relation to woody biomass, the following indicators are distinguished: the density of the wood substance, the density of absolutely dry wood, the density of wet wood.

The density of a wood substance is the ratio of the mass of the material that forms the cell walls to the volume it occupies. The density of the wood substance is the same for all types of wood and is equal to 1.53 g/cm3.

The density of absolutely dry wood is the ratio of the mass of this wood to the volume it occupies:

P0 = m0/V0, (2.3)

Where ro is the density of absolutely dry wood; then - the mass of the wood sample at No. p = 0; V0 - the volume of the wood sample at №р=0.

The density of wet wood is the ratio of the mass of a sample at a given moisture content to its volume at the same moisture content:

Р w = mw/Vw, (2.4)

Where mouth is the density of wood at humidity Wp; mw is the mass of the wood sample at moisture content Vw is the volume occupied by the wood sample at moisture content Wр.

Density of stem wood. The value of the density of stem wood depends on its species, humidity and swelling coefficient /Cf. All types of wood in relation to the coefficient of swelling KR are divided into two groups. The first group includes species with a swelling coefficient /Ср = 0.6 (white locust, birch, beech, hornbeam, larch). The second group includes all other breeds in which /<р=0,5.

For the first group for white acacia, birch, beech, hornbeam, larch, the density of stem wood can be calculated using the following formulas:

Pw = 0.957 -------- ------- р12, W< 23%;

100-0.4WP" (2-5)

Loo-UR p12" No. p>23%

For all other species, the density of stem wood is calculated by the formulas:

0* = P-Sh.00-0.5GR L7R<23%; (2.6)

Ріг = °,823 100f°lpp Ri. її">"23%,

Where pig is the density at standard humidity, i.e. at an absolute humidity of 12%.

The density value at standard humidity is determined for various types of wood according to Table. 6.

6. Density of stem wood of various species prn standard moisture n in a completely dry state

	Density, kg/m!		Density, kg/m3
		P0 in absolute			P0 in absolute
	Standard			Standard



Larch			Common ash




			walnut
White acacia

Bark density. The density of the crust has been studied much less. There are only fragmentary data that give a rather mixed picture of this property of the crust. In this work, we will focus on the data of M. N. Simonov and N. L. Leontiev. To calculate the density of the bark, we will use formulas of the same structure as the formulas for calculating the density of stem wood, substituting in them the coefficients of volumetric swelling of the bark. The density of the bark will be calculated according to the following formulas: pine bark

(100-THR)P13 ^p<230/

103.56- 1.332GR "" (2.7)

1.231(1-0.011GR)"^>23%-"

Spruce Bark Pw

W P<23%; W*> 23%;

Gr<23%; Гр>23%.

P w - (100 - WP) p12 102.38 - 1.222 WP

birch bark

1.253(1_0.01WP)

(100-WP)pia 101.19 - 1.111WP

1.277(1 -0.01WP)

The density of the bast is much higher than the density of the crust. This is evidenced by the data of A. B. Bolshakov (Sverd - NIIPdrev) on the density of parts of the crust in an absolutely dry state (Table 8).

Density of rotten wood. The density of rotten wood in the initial stage of decay usually does not decrease, and in some cases even increases. With the further development of the process of decay, the density of rotten wood decreases and in the final stage it becomes much less than the density of healthy wood,

The dependence of the density of rotten wood on the stage of damage by rot is given in Table. 9.

9. Density of wood decay depending on the stage of its damage

Rc(YuO-IGR) 106- 1.46WP

The pis value of rotten wood is: aspen rot pi5 = 280 kg/m3, pine rot pS5=260 kg/m3, birch rot p15 = 300 kg/m3.

Density of tree crown elements. The density of crown elements is practically not studied. In fuel chips from crown elements, the predominant component in terms of volume is chips from twigs and branches, which are close in terms of density to stem wood. Therefore, when carrying out practical calculations, in the first approximation, it is possible to take the density of the elements of the crown equal to the density of the stem wood of the corresponding species.

Table 1 - The content of ash and ash elements in the wood of various tree species

woody plant	Ash,
woody plant	Ash,													Sum
Pine	0,27	1111,8	274,0	53,4	4,08		5,59	1,148	0,648	0,141	0,778	0,610	0,191	1461,3
Spruce	0,35	1399,5	245,8	11,0	9,78	12,54	7,76	1,560	1,491	0,157	0,110	0,091	0,041	1689,8
Fir	0,46	1269,9	1001,9	16,9	16,96	6,85	6,16	1,363	2,228	0,237	0,180	0,098	0,049	2322,8
Larch	0,22	845,4	163,1		23,80	13,34	3,41	1,105	0,790	0,194	0,141	0,069	0,154	1057,4
Oak	0,31	929,7	738,3	14,4	7,88	3,87	1,29	2,074	0,987	0,524	0,103	0,082	0,024	1699,2
Elm	1,15	2282,2	2730,3	19,2	4,06	10,05	4,22	2,881	1,563	0,615	0,116	0,153	0,050	5055,4
Linden	0,52	1860,9	792,6	12,3	9,40	8,25	2,58	1,199	1,563	0,558	0,136	0,102	0,043	2689,6
Birch	0,45	1632,8	541,0	17,8	23,81	4,30	20,12	1,693	1,350	0,373	0,163	0,105	0,081	2243,6
Aspen	0,58	2100,7	781,4	12,4	5,70	9,19	12,99	1,352	1,854	0,215	0,069	0,143	0,469	2926,5
Poplar	1,63	4759,3	1812,0	18,1	8,19	17,18	15,25	1,411	1,737	0,469	0,469	0,273	0,498	6634,8
Alder black	0,50	1212,6	599,6	131,1	15,02	4,10	5,08	2,335	1,596	0,502	0,251	0,147	0,039	1972,4
Alder gray	0,43	1623,5	630,3	30,6	5,80	6,13	9,35	2,059	1,457	0,225	0,198	0,152	0,026	2309,8
bird cherry	0,45	1878,0	555,6		4,56	11,49	4,67	1,599	1,287	0,347	0,264	0,124	0,105	2466,0

According to the content of ash elements in their wood, all tree species are combined into two large clusters (Fig. 1). The first, headed by Scotch pine, includes black alder, aspen and balsam poplar (Berlin), and the second includes all other species, headed by spruce and bird cherry. A separate subcluster is composed of light-loving species: drooping birch and Siberian larch. The smooth elm stands apart from them. The greatest differences between clusters no. 1 (pine) and no. 2 (spruce) are noted in the content of Fe, Pb, Co, and Cd (Fig. 2).

Figure 1 - Dendrogram of the similarity of tree species in terms of the ash composition of their wood, built by the Ward method using a normalized data matrix

Figure 2 - The nature of the difference between woody plants belonging to different clusters, according to the ash composition of their wood

Conclusions.

1. Most of all, the wood of all tree species contains calcium, which is the basis of the cell membrane. It is followed by potassium. An order of magnitude less iron, manganese, strontium and zinc in wood. Ni, Pb, Co, and Cd close the rank series.

3. Tree species growing within the same floodplain biotope differ significantly from each other in terms of the efficiency of their use of nutrients. Siberian larch uses the soil potential most effectively, 1 kg of wood of which contains 7.4 times less ash than poplar wood, the most environmentally wasteful species.

4. The property of high consumption of mineral substances by a number of woody plants can be used in phytomelioration when creating plantations on technogenically or naturally polluted lands.

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