There are many kinds of trees in our country, about 7,000 kinds, among which nearly 1,000 kinds have excellent materials and relatively high economic value. Due to different tree species, the wood structure is different, and its materials are also inconsistent. Some materials are good and some are poor.
1.Methods and steps for wood identification
⑴Methods for wood identification
The identification of wood species is mainly based on the characteristics of the wood. In addition to having common characteristics, various woods also have characteristics that are different from other woods. The former is called universality or commonality, and the latter is called particularity or individuality. For example, jujube and soapberry are both ring-porous materials, and flat materials have multiple rows of tube holes. This is their common feature. However, the color of Ziziphus wood is reddish, the difference between the heart and sapwood is obvious, and the axial parenchyma is paratubular. The color of Soapberry wood is yellow, the heart and sapwood area is not obvious, and the axial parenchyma is ring-shaped and wing-shaped. and wing-like. In this way, the color of wood, the presence of heartwood and sapwood, and the type of axial parenchyma become the characteristics that distinguish them. Therefore, only by mastering the commonalities and individualities of various types of wood can we distinguish the species of wood.
Due to different application scopes, the specific content of the particularity and universality of wood characteristics also changes. For example, the tube pores are distributed in annular or semi-annular pores, which is a common feature of many woods. It is universal in this range, but in the entire broadleaf tree, there are many more species than this. The distribution of tube holes is scattered, so the characteristics of ring holes or semi-ring holes can only be regarded as special features. This is what is called universality in particularity, and commonality in individuality. Therefore, when we identify wood species, we must first be proficient in the various characteristics of wood and understand their relationships. Secondly, we must be good at observation and analysis, grasp its main characteristics, and then look at the general, analyze and compare, so as to find out Regular characteristics, and possible variations. For example, camphor has a strong camphor smell, which is not found in other tree species. The smell can be used as an important feature to identify camphor.
Things change. When the tree species are different, the situation is different, and the main characteristics and secondary characteristics of the wood will also change accordingly, so specific problems must be analyzed in detail. For example, smell is an auxiliary feature for wood identification, but for some tree species, it plays a dominant role. The camphor mentioned above is an example.
Identifying wood species is a relatively practical task. In addition to having a relatively good understanding of the various characteristics of wood, you also need to practice repeatedly with real objects and compare them repeatedly to gradually become proficient in them. When you encounter unfamiliar tree species, you can also quickly identify them. and accurately identify it. To identify wood species quickly and accurately, we must do the “three mores” of seeing more (physical objects), comparing more, and remembering more.
⑵Steps of wood identification
The steps to identify wood species are generally to first classify whether the wood is coniferous or broad-leaved based on whether it has pores or not. If it is determined to be coniferous wood, observe whether it has resin channels. Those with resin belong to Korean pine, larch, tabby pine, masson pine, Yunnan pine, spruce, etc.; those without resin channels belong to fir and Chinese fir. , cypress…etc. After distinguishing which category it belongs to, determine which coniferous tree it belongs to based on the size of the resin channel, the change from early wood to late wood, the obvious difference between heartwood and sapwood, and the color, smell, hardness of the wood, etc. If you begin to determine that it is actually broad-leaved tree wood, observe the distribution of its ducts to determine whether it is ring-porous wood, diffuse-porous wood, or semi-ring (diffuse)-porous wood. Then, based on the arrangement of tube holes, the type of axial parenchyma, the width of the wood rays and the patterns presented on the wood surface, whether the difference between heart and sapwood is obvious, and the color, smell, weight, hardness, etc. of the wood, determine whether it belongs to Which type of broadleaf tree. At present, my country’s timber supply is still dominated by logs, so it is important to master the identification of log species. The identification method of log tree species is generally from the outside to the inside (from bark to xylem), from simple to complex (from naked eye observation to using a magnifying glass), and gradually deepens. Specifically, for logs with bark, start from the bark to the surface of the wood (surface of the body), and then to the end surfaces (sections at both ends). For logs without bark, measure from surface to end.
2.Taking broad-leaved trees as an example, the specific steps for log identification are as follows:
① Observe whether there are any cracks on the outside of the bark and its cracking conditions, attachments, cork layer, stone cell type, whether the bast fibers are developed or not, patterns on the cross section, whether there are grooves on the bottom of the bark, and others;
②Observe the patterns and attachments displayed by the rays on the material surface;
③Observe the distribution, combination, arrangement and inclusion of tube holes in the cross section of the wood, as well as the type of axial parenchyma;
④Observe the growth theory, heartwood, texture, structure, weight, softness and hardness, and smell its smell, etc.
For example, the observation results are: the leather surface has deep cross-cut longitudinal cracks; the wooden pegs are particularly developed (more than 10 mm thick) and are elastic when pressed by hand; the bottom grooves of the leather are sharply serrated. The rays appear as grooves on the surface of the wood and are separated; the heartwood and sapwood areas are slightly obvious; the growth rings are obvious and slightly wavy; the pith is small; the ring-porous wood has one to two rows of tube holes in the flat wood, and the diameter of the latewood tube is in rows; There are two kinds of broad rays and extremely narrow rays. The ray width is greater than the chordwise diameter of the tube hole (referred to as the aperture); the parenchyma is an off-tube type scattered-aggregated; it has ring tracheids; the material is heavy; the texture is straight and the structure is thick. This is consistent with the characteristics of the cork oak. Then check with the wood specimens of the cork oak. If there is no mistake, it can be determined to be the cork oak.
For some tree species with special characteristics, it is not necessary to follow the above steps. However, wood species cannot be determined by one characteristic alone. Especially for the identification of broad-leaved trees, the tube hole parenchyma wood rays must be fully considered.
3.Things to note when identifying wood
When observing the color and cracking of bark, pay attention to the age of the tree and the upper and lower parts of the trunk. Because the color and cracking of the bark of some tree species often vary depending on the age of the tree and the upper and lower parts of the trunk. For example, the bark of the trunk of an old neem tree is rough, dark, and cracked; the bark of the trunk of a young tree or the branches of an old tree is smooth and lighter in color.
Pay attention to whether the wood being identified is in normal condition. Because after the trees are harvested, the length of time they are stored, the degree of dryness and humidity, and whether they are decayed or not, can cause some changes in the appearance or weight of the wood, which can easily lead to misunderstandings. For example, the wood of ebony is always reddish white when it is fresh, but it will fade after being stored for a long time. Another example is that the sapwood of masson pine often turns blue due to erosion by color-changing bacteria. Therefore, when we identify wood species, we cannot judge wood that has changed color as normal.
The size of the pith is not completely consistent in various parts of the trunk. The pith near the ground is the smallest, becomes larger as it goes upwards, and gradually becomes smaller as it reaches the crown.
Observe carefully to avoid mistakes. Don’t mistake the ribbon-like parenchyma of banyan and cypress wood for growth rings, and the pseudo-alder vessels appear as linear patterns on the surface of the wood.
Correctly grasp and apply the grading of features at all levels. Due to differences in people’s sensory organs and variations in wood characteristics, when identifying wood, there may be differences in grading between people, so a one-level difference is generally allowed. For example, in some books or records of a certain kind of wood: the rays are spotted on the surface of the wood, the tube holes are small, and the wood is very heavy; secondly, what we observe on the specimens is: fine yarn patterns, the tube holes are medium-large, and the wood is heavy; At this time, we cannot easily deny that it is not this kind of wood, we must also look at other characteristics. If what we are observing is the lampshade pattern, the tube holes are large, and the wood is of medium weight, this can rule out the possibility of this kind of wood. In other words, a difference of one grade is allowed, but a difference of two grades is not allowed.