The basis of wood identification is the wood specimens and slices of the name, the necessary knowledge of wood construction; the method of identification is to comprehensively observe from three aspects, to treat the main and minor features, and to consider the variability of wood; the object of identification is logs; Plate, square material; isolated fiber; recognition methods and methods are macro, micro and sub-micro; experience method, bisection method, punch card method, physical chemistry method, computer-aided identification method, wood slice direct identification method. Due to the variety of trees, if the experience alone is likely to lead to the wrong name, it is necessary to summarize the experience on the basis of summarizing the experience and theoretically summarizing a set of methods for scientifically identifying wood.
First, the purpose of identifying wood
The purpose of identifying wood is to determine the name of the tree species, which can be solved: determining the species name, identifying the authenticity of the tree species; helping to find alternative materials; providing clues for the public security department to solve the case and providing assistance for archaeological geology and plant classification. The tools used are magnifiers, knives, microscopes, search tables, microcomputers, and specimens with positive names. The materials identified may be wood, logs and isolated wood molecules. The classification of the recognition features is called macroscopic (macroscopic, macroscopic structure) under the naked eye magnifying glass; the structure under the optical microscope is called microscopic structure and the structure under the electron microscope is called ultramicrostructure (submicroscopic structure).
Second, the identification step
Production → observation → record characteristics → check the search form → check with the correct sample.
Third, the precautions when identifying
1. It is necessary to find out the purpose and requirements of the inspection: usually requires the name to be fixed, and some requirements to prove whether it is a certain tree species, and some require that the two pieces of wood be the same tree species.
2. Find out the source or origin: the geographical distribution of trees has reference value for identifying tree species (Pannan and Phoebe are difficult to distinguish, but the former is produced in the southwest, the latter is produced in South China, Huazhong area. Red pine and Huashan pine are difficult to divide, but The former is produced in the northeast).
3. According to the needs of the materials, some of them, such as ancient wood, decaying materials, also need special treatment such as embedding. Some, such as fossils, need to be ground and some need only use a sharp blade to scrape the sheet for identification. Some need to be identified by the separation method.
4. The search characteristics should be on the transverse and chord cut surfaces (especially the cross-section), and the observation should be very careful (especially when applying the dichotomous search method). The variation can be caused by the different site conditions and the location of the material, and the trees are also in evolution. In the process, stability and variability are relatively existable, so the variation may only be the change of anatomical molecular weight and not the qualitative difference. This has empirical problems. Broad-leaved trees generally focus on the growth wheel type (ring hole material, semi-ring hole material, Diffuse wood), axial thin-walled tissue and wood rays, as these features are the most visible and stable.
5. It is necessary to dialectically look at the main features and secondary features. When identifying wood, it is undoubtedly the first thing to grasp the main features, because these features are generally stable, but sometimes the so-called secondary features play a decisive role. If there are clusters in the coniferous tree, Can be considered as ginkgo. If it is observed that there is a phloem, it is known that the wood is a species such as scutellaria, lobular wood, and white wood.
6. It is necessary to dialectically look at macro and micro features. In general, it is easier and more accurate to identify wood with microstructural features. However, some objective features, such as camphor odor, consider the wood of the genus. Another example is that the wood of the genus Birch is indistinguishable under the microscope, but the bark can be distinguished: white birch (white bark, not recurved); red birch (red bark, often recurved); Echinochloa birch (bark dark black, slightly recurved).
7. It is necessary to pay attention to the relationship between the local and the whole. It is necessary to look at the wood structural molecules as a whole, and only through repeated observations of the transverse, radial and chord shapes can be determined. For example, the type of ray tissue can only compare the length of the tail and the complex part of a single column in the chord section. Whether it is a square, an erect cell or a horizontal cell can be confirmed on the radial section, and the condition of the two sections can be determined. Homogeneous or profiled ray tissue. For example, if the axial thin-walled structure is not confirmed on the transverse section, it is necessary to observe the thin-walled tissue (string) on ​​the longitudinal section.
8. The identification of wood by microscopy (plus better macroscopic features) is more correct. According to the commonality and individuality of the wood, it is identified to the genus to the genus. Because the identification characteristics of the wood are too few, it can only be identified to the genus.
9. There are a large number of wood specimens and sections with positive names. Because the trees are mutated due to site conditions, etc., more specimens are needed for comparative study. Because the specimen that is being identified is the final standard for checking the wood to be inspected.
10. It is necessary to accumulate experience, correctly identify features and link these characteristics to specific tree species. An experienced person is very different from a beginner, so it is necessary to practice repeatedly.
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