(Chang Kun)
According to the correlation between trunk volume and its three elements (DBH, tree height and trunk shape), the tree volume table is compiled. It can be used to measure the standing timber volume. Longquan courtyard price, 17, which was created in China in the 1940s, is the earliest volume table that can be tested. Its expression with eyebrow height and eyebrow circumference as independent variables is similar to the volume table with breast height and breast diameter as independent variables. /kloc-at the beginning of the 9th century, the German forester H.V.Cotta put forward the theory that the volume of trees depends on DBH, height and shape, and published the first volume table of zhangli trees.
Tree volume table type
According to the scope of data collection and the applicable area of the table, it is divided into local volume table and general (standard) volume table; According to the suitable tree species, it can be divided into three types: tree species, tree species group and non-tree species. According to the different parts representing the volume of trees, it can be divided into trunk, branch, tree (including trunk and branch), wood (pruning, the volume above a certain small head diameter), root, bark and other volume tables, among which the most commonly used volume table is the trunk volume table, which generally refers to the trunk volume table with bark without special instructions; According to the different influencing factors, the volume table can be divided into one-dimensional, two-dimensional and three-dimensional volume tables. Different classification methods are closely related to phenotype. For example, local volume tables are mostly unitary tables compiled by different tree species; The general volume table is mostly a binary table compiled by tree species and tree species groups in Dalin District or provincial administrative divisions.
Ternary volume table
According to DBH and tree height, taking some indexes of trunk shape as grading factors, the standing volume table is compiled. The trunk shape index usually adopts the ratio of breast height (q2), which is expressed by the ratio of the diameter of tree center to the diameter of breast height. In addition, it is also expressed by the ratio of the diameter of the center above the breast height to the diameter of the breast height, the height under the branches, and the difference between the diameter of the breast height and a certain diameter at the upper part. In order to adapt to the diversity of subtropical broad-leaved tree species, China adopted V = 0.534D2 1.748 based on the trunk volume formula of Schustoff (бащустов).
Formally, the ternary volume table also determines the volume through DBH and tree height, but it needs to determine an upper diameter to determine the shape class. This method is accurate in theory, but the determination process is complicated. The Nair-Schwerbach volume table in Gron, Germany is compiled according to tree species and age groups respectively. It achieves the purpose of indirectly distinguishing the dry forms of different ages, so it also has the nature of ternary table. Each tree species in this table consists of eight categories: wood (volume with small head diameter above 7 cm), branches, bark, taper, forest fractal number, tree species and tree height.
Binary volume table
Volume table based on DBH and tree height. Because the trunk shape of trees is closely related to DBH and tree height, if the trunk shape factor is not directly compiled as an independent variable, the theoretical error will not increase excessively, and it is difficult to determine the trunk shape factor and ensure its accuracy. Therefore, the binary volume table has developed rapidly and become the basic volume table in most countries. In 19 10 ~ 1920, terasaki, Japan, compiled binary volume tables of many tree species with its own derived dry curve equation and shape number method. Kazuo Yamamoto (19 18) and Sehumah-Hall (1933) put forward the formula V=aDbHc (where D is aDbHch and tree height; A, b, c are parameters), which contributes to the popularization of binary volume table. Due to the development of electronic computing technology, many more complex and accurate binary volume formulas have appeared.
In 1950s, China compiled nearly 80 advanced volume tables of more than 20 main tree species in main forest areas, namely, the standing volume tables compiled according to different DBH wood classes. These tables belong to binary volume tables in nature, but they are equivalent to unitary volume tables in the form of table lookup. In 1975, in order to further standardize the volume table, using the data of nearly 200,000 sample trees of 180 tree species collected in various forest areas in recent 30 years, 56 binary tables suitable for most tree species in various forest areas were compiled through dry shape analysis. There are 35 species of conifers and 2 1 species of broadleaf trees. The mathematical model is V=aDbHc. This series of volume tables were published in 1978 as the standard of the Ministry of Agriculture and Forestry (LY208-77).
Unary volume table
Tree volume table based on DBH and DBH coefficients. 1878 was put forward by French A.Gurnaud, and then developed and applied by Swiss H.Biolley. It was originally called "Tarif table", in order to avoid repeated height measurement every time. The word "Tarif" comes from Arabic, and its meaning is similar to that of China. In China, the unitary volume table was used in forest areas in the 1940s, and the advanced volume table was used after 1950s. By the end of 1970s, in order to unify the tables used in the continuous inventory of forest resources in China, the univariate volume table of each tree species (or tree groups) was derived from the standard binary volume table issued by the Ministry. Up to 1982, there are nearly 600 one-dimensional volume tables of various tree species in various forest areas in China.
Although the one-dimensional volume table is convenient to use, its accuracy is difficult to guarantee because it does not consider the changes of tree height and trunk shape. It is a local volume table. In order to improve the accuracy of the unary table, a variety of unary tables have been developed in practice, that is, the changes of tree height and trunk shape are controlled by the high level, status level, age group and forest type of the tree, and unary volume tables are compiled according to different levels (classes). This table can give several volume curves, which improves the flexibility of using the same average volume curve in a certain area for a single table, thus improving the accuracy of the table (close to the binary table). The French Volume Table of Alganta Reef (published in1986) has a DBH of 5 cm and consists of 20 volume series (standing volume curves). The Russian temporary volume table, which has been used for more than 40 years, is a table that divides trees of the same diameter class into 3-4 wood classes according to the difference of tree height in the early days, and establishes the viewpoint of compiling volume tables according to wood classes, which became the basis for compiling the volume tables of forest industry in the whole Soviet Union. Tareef, a multi-purpose stumpage volume table edited by K.J.Turnbull and G.E.Hoyer in England from 65438 to 0965, is an innovative stumpage volume table. The first part of the table is the intersection table of tree height and DBH, which is equivalent to the high-level table of the tree and is used to determine the table number (also called the Tareef number). The second part is a series of volume tables corresponding to each table number, arranged in diameter order: the total volume of trunk including roots and shoots; Total trunk volume excluding root cutting; Peeling volume and board ruler volume of wood sections from root cutting to 4 inches and 6 inches; So as to provide a growth multiply for volume growth calculated by diameter growth; Provide the ratio of volume for point sampling to cross-sectional area at breast height, etc. 1959, China compiled a unitary list of five tree species (groups) such as spruce and oak in Shennongjia forest area according to forest types. In the early 1980s, in order to combine status evaluation with volume calculation, a volume table of Chinese fir classified by status index was compiled.
Compilation of stumpage volume table
The content includes the collection of basic data and the selection of appropriate methods.
Basic data collection
Basic data should be representative, accurate and unified. The compilation of general stumpage volume table only needs the measured data of all related factors of a single tree; The volume table of forest grade, status grade and forest type should be compiled, and at the same time, the related factors of the stand and the measured data of the sample trees of the corresponding stand are needed. Collect samples in the whole tabulation area by random sampling or conditional sampling. All diameter classes and tree height groups should have sample trees, and the number of sample trees should meet the requirements of large samples, so as to ensure the representativeness of samples and avoid unreasonably extending the volume regression curve when compiling tables. Generally speaking, random sampling is reasonable and representative, but in practice, due to the limitation of geographical scope and complex terrain, conditional sampling method is often used in various places. Because of the different forestry knowledge and experience of measuring trees, this method is obviously different in representativeness, and it is generally easy to produce a slightly larger volume error. In the past, China adopted conditional sampling method to select sample plots and mechanical sampling method to collect sample data. In recent years, the deviation was analyzed, and combined with the continuous forest resources inventory, the DBH, height and volume table of sample trees were measured in the sample plots laid out in the system to test and correct the volume table.
Table compiling method
There are two main methods to compile the standing volume table: graphical method and numerical method. (1) Graphical method: A method of compiling volume tables by drawing curves or straight lines related to volume and independent variables. The program of compiling binary table by graphic method is as follows: the measured data of sample trees are grouped and classified according to DBH 2cm and tree height 1 m, and the actual average DBH, average tree height and average volume are calculated; According to the actual average value of each group, the correlation curves between volume and DBH are drawn for the tree height group respectively, and the average volume of each diameter class and tree height group is read on the smooth curve; Using the read volume values of each group, the correlation curves between volume and tree height are drawn according to diameter steps, and the average volume of each tree height group and diameter steps is read on the smooth curve; Using the volume values read by each tree height group for the second time, draw the correlation curve between volume and DBH, trim evenly, find out the individual volume of each diameter class and tree height group, and list the related tables (volume tables). ② Mathematical method: the method of calculating and compiling tables by using volume regression equation (mathematical model). On the premise that the basic data is representative, accurate and unified, choosing the most suitable mathematical model is the key to ensure the accuracy of the table. Commonly used mathematical models are as follows:
Unary table
V=b0Db 1
V=b0+b 1Db2
Binary table
V=b0Db 1Hb2
V=b0+b 1D2 +b2H+b3D2H
v = B0+b 1 D2+b2D2H+B3 H2+b4H2D
Ternary table
V=b0Db 1Hb2Fb3
short form
V=b0+b 1FD2H
Shape and number formula
f=b0+b 1/H+b2/D-b3B-b4K
Where b is the thickness of bark; K is the branching rate; M is a constant; H is the tree height; H 1 is the chest height; B0, b 1, b2, b3 and b4 are all parameters; E is the base of natural logarithm; F stands for dry shape index (shape number, shape ratio, diameter difference, diameter ratio, etc.). ).
Modern electronic computers provide extremely convenient conditions for solving multivariate regression and polynomial regression, selecting and testing multivariate volume regression equations. The method of compiling tables has changed from graphic method to numerical method.
Use of stumpage volume table
The main purpose of measuring forest volume with standing volume table is to calculate the total forest volume in a certain area. A series of data in the table reflect the average volume of many standing trees under corresponding conditions, and there are different sizes of errors for a standing tree. The more stumps and forest areas are measured, the higher the accuracy. When using, first measure the corresponding factor value according to the requirements of the used volume table, and then look up the table.
One-dimensional volume table has strong regionality and low accuracy. Only when the tree height curve of the investigated tree is similar to the sample wood used in compiling the volume table can a certain accuracy be guaranteed. Therefore, it is often used to calculate the large-area forest stock under various site conditions. Unary table is still used frequently in many countries because of its simple use. In the continuous inventory of forest resources in China, the unitary table is mainly used to check the stock and estimate the net growth. The unary table compiled according to a certain stand factor classification (class) has high accuracy. When using, first determine the grade (category) of the stand, and then check the timber volume with the corresponding volume table to calculate the stand volume.
The binary volume table can be used to measure the forest volume in a large area or a small area with high accuracy, and it is necessary to measure the DBH and height of trees when using it. DBH is obtained by measuring each tree in the investigated stand. There are three main methods to measure the height of trees: ① Measure the height of each tree. ② Determine the average height of each diameter class by drawing the tree height curve. (3) Calculate the average height of each diameter class according to the standard tree height curve value table compiled in advance according to tree species, age (or forest type) and tree height group. The average height of each diameter class can be converted in the table only by measuring the average height of the stand. China often uses the second method. The procedure for calculating the stand volume is as follows: (1) Count the number of stumps at each diameter class of the stand; (2) Measure the diameter-class tree heights of several sample trees, draw the tree height curve and read the diameter-class average tree height; (3) Find out the average individual volume of diameter steps from the volume table, and calculate the total volume and stand volume of each diameter step.
It is necessary to measure the DBH, tree height and trunk index of the ternary volume table to calculate the stand volume. Among them, the measurement of dry shape value is troublesome, and how to measure it is also controversial. Generally, the diameter step average method and the standing tree average method can be used. The former method is to draw the correlation curve between the dry shape index value and DBH or tree height, and get the average dry shape index of diameter class or tree height group. The latter method is to determine the dry shape index of several trees with average cross-sectional area in the stand, then determine the dry shape grade of the stand according to its average value, and then calculate the stand volume according to the same procedure as using the binary table.
philology
Boyi Sun Yat-sen: Determination of Forest Volume, Jinyuan Publishing Co., Ltd., Tokyo, 1962.