A method for detecting forest combustibles and calculating their load

Abstract

The present invention discloses a method for detecting an index of forest combustibles and calculating its load, which relates to the technical field of combustible load determination, and comprises the following steps: S1: determining a sample plot and collecting samples, and then determining the physical and chemical properties and stand unit volume of the samples according to the samples; S2: collecting existing survey data, completing data collation, and obtaining the tree species biomass root-to-shoot ratio parameter R; S3: using the "forest stock-biomass expansion equation" to calculate the sample biomass of a small class, see formula (1): B=aV+b(1) In the formula, S3: calculating the aboveground biomass according to the sample biomass B calculated by formula (1) and the tree species biomass root-to-shoot ratio parameter R, that is, obtaining the combustible load per unit area P, and the calculation formula is: P=B / (1+R). The invention can calculate the forest combustible load by using the "one map" data of forest resource management, the "forest stock-biomass expansion equation" and the "biomass root-to-shoot ratio".

Description

Technical Field

[0001] The present invention relates to the technical field of combustible load measurement, and in particular to a method for detecting forest combustible indexes and calculating their load. Background Art

[0002] Forest ecosystems cover approximately 30% of the world's land area and are crucial for ensuring the stability of both humans and ecosystems. Forest fires are caused by many factors, the three main ones being meteorological factors, forest fuels, and ignition sources. Forest fuels are the material basis for forest combustion and a crucial component of fire management planning and fire risk assessment. They are also the easiest of the three main fire-causing factors to manage and adjust. Jiangxi Province has a forest coverage rate of 63.9%, ranking second nationwide. Its forest cover is generally increasing, making it a high-incidence area for forest fires. According to statistics, 6,239 forest fires occurred in Jiangxi Province between 1998 and 2017, with the incidence trending initially upward and then downward. However, due to the frequent occurrence of extreme weather events caused by global warming and the impact of human activities, forest fire prevention will remain a critical task in the future.

[0003] The combustibility of forest fuels depends on their physical and chemical properties. Moisture content, flash point, and calorific value are key factors in forest fire prediction and forecasting. The amount of fuel load directly influences fire behavior, including intensity, flame height, and spread rate. Currently, most forest fuel surveys rely on quadrat harvesting, which requires highly specialized personnel. This is labor-intensive, time-consuming, and labor-intensive, and the samples collected are susceptible to geographical and weather factors.

[0004] Fuel load refers to the oven-dry weight of fuel per unit area, including all dead and living organic matter. Domestic scholars Deng Xiangwen (2002) and others used the stepwise regression method, with the stand factor as the a model, and adopted the multi-model optimization method to predict the combustible material load of leaves, branches, dead branches, trunks, etc. in the southern fir plantation. Hu Haiqing (2005) and others proposed a multivariate and neural network regression model based on the study of different types of fuel load and stand factors in Maoer Mountain. Liu Zhaodong (2019) used the multivariate stepwise regression method to study the relationship between the ground fuel load of different forest types and stand and site factors. In particular, the study results showed the best modeling method for the surface fuel load and influencing factors of different forest types in Beijing. However, the accumulation of surface fuel load is a complex and comprehensive natural process, and the fitted model will also become more complex and comprehensive, which still requires further exploration and research. Ning Jibin et al. (2018) constructed a linear regression model for surface fuel load using the height of surface fuel as a variable. However, due to the differences in latitude, altitude, community density, and composition of different fuel types, a universal fuel load estimation model could not be established. However, the experimental method used can be extended to forest fuel surveys of other types and regions for fuel load estimation. Wu Qingyun et al. (2022) used field measurements of dead fuel material on the surface of forests in southern Jiangxi to establish a relationship between dead fuel load and environmental factors such as topography and vegetation, primarily analyzing the impact of topography and vegetation on fuel load. To more accurately assess fuel load, it is necessary to quantify the direct and indirect influences of factors such as climate, vegetation, topography, and human activities on forest fuel load at a larger scale. With the development of science and technology, combining manual measurement with advanced technologies will undoubtedly improve the accuracy of rapid fuel measurement, thereby helping forest fire commanders accurately analyze potential fire behavior and having practical significance for effectively controlling fire behavior.

[0005] However, the existing technology for calculating forest fuel load has the following problems:

[0006] (1) The traditional method of collecting and calculating the total forest fuel load is highly professional and is restricted by geographical factors, resulting in a large workload for field collection, low manual operation efficiency, and large sampling errors.

[0007] (2) Small plots used in field surveys are greatly affected by boundary effects, which can result in excessively high biomass statistics. Summary of the Invention

[0008] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a method for detecting forest combustible indexes and calculating their load.

[0009] The technical solutions of the present invention are as follows:

[0010] A method for detecting forest combustibles and calculating their load includes the following steps:

[0011] S1: Determine the sample plot and collect samples, then measure the physical and chemical properties and stand unit volume of the samples;

[0012] S2: Collect existing survey data, complete data collation, and obtain the root-to-shoot ratio parameter R of tree species biomass;

[0013] S3: Use the “forest volume-biomass expansion equation” to calculate the sample biomass of the small group, see formula (1):

[0014] B=aV+b (1)

[0015] Where, B(t / hm 2 ) represents the biomass of sample per unit area; V (m 3 / hm 2 ) represents the stand unit volume; a and b are parameters;

[0016] S3: Calculate the aboveground biomass based on the sample biomass B calculated by formula (1) and the root-to-stem ratio parameter R of the tree species biomass, that is, obtain the fuel load per unit area P, and the calculation formula is: P = B / (1 + R).

[0017] As a preferred embodiment of the present invention, the determination of the stand unit volume: determination and calculation of the volume of wood at each density level:

[0018]

[0019] Where:

[0020] V represents the volume of each tree in the plot (m 3 );D 2 dc,1 ...D 2 dc,l ...represents the central diameter (cm) of each 1m segment of dead wood of a certain density level; D i 2 、l i Indicates the bottom diameter and length (cm, m) remaining after dividing into whole meters.

[0021] As a preferred solution of the present invention, the existing survey data include the "one map" data of forest resource management collected uniformly across the province, forest resource inventory results, the third national land survey data and the integrated and optimized vector database of nature reserves.

[0022] As a preferred embodiment of the present invention, in step S1, the physical and chemical properties include equilibrium moisture content, flash point, and calorific value.

[0023] As a preferred embodiment of the present invention, the equilibrium moisture content test method is as follows: the sample is saturated with water and placed in a drain basket, and then placed in a constant temperature and humidity chamber respectively. The sample mass is weighed and recorded every 1-3 hours until the difference in moisture content calculated from the two weighing results is less than 1%, and the experiment is stopped.

[0024] As a preferred embodiment of the present invention, the method for testing the ignition point is as follows: the sample is crushed, ground with agate, and then crushed, weighed and placed in a test tube, and then placed in a ignition point instrument, the sample is burned, and the ignition point of the sample is measured.

[0025] As a preferred embodiment of the present invention, the calorific value testing method is as follows: the sample is crushed, weighed and the mass is recorded, and the sample is placed in a calorimeter to measure the calorific value.

[0026] The beneficial effects of the present invention are:

[0027] (1) Compared with the traditional forest fuel load calculation method, this invention uses the dominant tree species and hectare accumulation data in the "one map" of forest resource management, without the need to use the traditional sample plot survey method, which can save a lot of manpower and material resources.

[0028] (2) The forest fuel load can be calculated by using the "forest volume-biomass expansion equation" and the "biomass root-to-shoot ratio" data from the "one map" of forest resource management. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Flowchart of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0030] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0031] Reference Figure 1 The technical solution of the present invention is further described below with reference to specific embodiments:

[0032] 1. Selection of standard sites and collection of samples

[0033] 1) Test materials

[0034] Using a GPS with RTK functionality, the desired sample plot was located and the coordinates of the southwest corner stake point were measured, using the 2000 China Geodetic Coordinate System (CGCS2000) and the 1985 National Height Datum. After determining the southwest corner, the sample plot boundary was measured clockwise to a square with a side length of 28.28 meters and an area of 1.2 mu. Four sample plots were set 2 meters east, south, west, and north of the four vertices of the standard tree plot, and samples were collected. A 5m x 5m shrub plot was arranged at the center of the longest central axis of the shrub plot, and a 1m x 1m plot was set at the southwest corner of each shrub plot. The collected samples were placed in sample bags, numbered, and brought back to the laboratory for physical and chemical property determination. For specific sampling methods, please refer to the Technical Specifications for the First National Natural Disaster Comprehensive Risk Survey (FXPC / LC F-01) and the Technical Procedures for Forest Fuel Standard Site Surveys.

[0035] 2) Determination of sample physical and chemical properties and stand unit volume

[0036] Determination of equilibrium moisture content: Soak the sample in water until it is saturated and place it in a plastic basket with mesh holes on the sides and bottom, and then place it in a constant temperature and humidity chamber. Set the temperature to 25°C and the humidity to 30%. Weigh the sample every 2 hours and record the weight. Stop the experiment until the difference in moisture content calculated from the two weighing results is less than 1%.

[0037] In terms of measuring moisture content, increasing the oven temperature can shorten the drying time and save testing time.

[0038] Flash point test: Grind the crushed sample with agate and then crush it. Weigh 3-5g and place it in a test tube. Then put it into the flash point instrument to burn the sample and measure the flash point of the sample.

[0039] Calorific value test: Weigh 3-5g of the crushed sample, record the mass, place it in a calorimeter, and measure the calorific value.

[0040] Determination of stand unit volume: Determination and calculation of wood volume at each density level:

[0041]

[0042] Where: V represents the volume of each tree in the plot (m 3 );D 2 dc,1 ...D 2 dc,l ...represents the central diameter (cm) of each 1m segment of dead wood of a certain density level; D i 2 、l i Indicates the bottom diameter and length (cm, m) remaining after dividing into whole meters.

[0043] After calculation, the physical and chemical properties and stand unit volume test results of different tree species samples are shown in Table 1.

[0044] Table 1 Physical and chemical properties and stand unit volume of different tree species

[0045]

[0046] 2. Survey data collection and collation

[0047] The data of the 2019 forest resource management "one map" collected uniformly across Jiangxi Province, the latest forest resource inventory results, the third national land survey data, and the nature reserve integrated optimization vector database and other existing relevant survey data were collected, and the data processing and collation were completed to obtain the data in Tables 2 and 3.

[0048] 3. Use the “forest volume-biomass expansion equation” to calculate the sample biomass of the small class, see formula (1):

[0049] B=aV+b (1)

[0050] Where: B(t / hm 2 ) represents the biomass per unit area (including aboveground and underground parts); V (m 3 / hm 2 ) represents the stand unit volume; a and b are parameters. Refer to Table 2 for detailed parameters.

[0051] Table 2 Parameters of forest stock-biomass expansion equation for each tree species

[0052]

[0053]

[0054] For tree species not listed above, they can be categorized as a specific species based on their species code or characteristics for calculation. For example, if Pinus taiwanensis and Pinus truncatula are missing from the table above, they can be categorized as "Other Pines" and the "Forest Stock-Biomass Expansion Equation" parameters for "Other Pines" can be used for calculation.

[0055] 4. Determination of biomass root-to-shoot ratio.

[0056] The aboveground biomass can be calculated using B calculated using formula (1) and the root-to-stem ratio R of the tree species, and the fuel load (aboveground part) of the tree species can be obtained, as shown in formula (2):

[0057] P=B / (1+R) (2)

[0058] Where P(t / hm 2 ) represents the fuel load per unit area, and R represents the root-to-shoot ratio parameter of the tree species biomass. The R table is selected from Table 3.

[0059] Table 3 Parameters of root-to-shoot ratio of biomass of various tree species R

[0060]

[0061]

[0062]

[0063] Mean is the average value; SD is the standard deviation. When using this method, search for the root-to-shoot ratio R (mean value) corresponding to each tree species by age group. If no data is available, use the value in "All." According to the above formula, the load (capacity) is calculated. Compared with traditional forest fuel load calculation methods, this invention uses data on dominant tree species and hectares of stock from the "One Map" of forest resource management, eliminating the need for traditional sample plot surveys and saving significant manpower and material resources. Furthermore, the forest fuel load can be calculated using the "forest stock-biomass expansion equation" and the "biomass-to-shoot ratio" using data from the "One Map" of forest resource management.

[0064] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0065] The above descriptions are merely preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the scope of protection of the present invention.

Claims

1. A method for detecting forest combustible indexes and calculating their load, characterized in that: The following steps are involved: S1: Determine the sample plot and collect samples, then measure the physical and chemical properties and stand unit volume of the samples; S2: Collect existing survey data, complete data collation, and obtain the root-to-shoot ratio parameter R of tree species biomass; S3: Use the "forest volume-biomass expansion equation" to calculate the sample biomass of the small class, see formula (1): B=aV+b (1) Where, B is in t / hm 2 , represents the sample biomass per unit area; V, unit is m 3 / hm 2 , represents the stand unit volume; a and b are parameters; S3: Calculate the aboveground biomass based on the sample biomass B calculated by formula (1) and the root-to-stem ratio parameter R of the tree species biomass, that is, the fuel load per unit area P is obtained, and the calculation formula is: P = B / (1 + R); Determination of unit volume of the stand: Determination and calculation of volume of wood at each density level: ； Where: V represents the volume of each tree in the plot, m 3 ;D 2 dc,1 ...D 2 dc,l ...represents the central diameter of each 1m segment of dead wood of a certain density level, in cm; D i 2 、l i Indicates the bottom diameter and length left after dividing into whole meters, in units of cm and m respectively.

2. A method for detecting forest combustibles and calculating their load according to claim 1, characterized in that: The existing survey data include the "one map" data of forest resource management collected uniformly across the province, the results of the forest resource inventory, the third national land survey data and the integrated and optimized vector database of nature reserves.

3. The method for detecting forest combustibles and calculating their load according to claim 1, wherein: In step S1, the physical and chemical properties include equilibrium moisture content, flash point, and calorific value.

4. A method for detecting forest combustibles and calculating their load according to claim 3, characterized in that: The test method for the equilibrium moisture content is as follows: after the sample is saturated with water, it is placed in a drain basket and then in a constant temperature and humidity chamber. The sample mass is weighed and recorded every 1-3 hours until the difference in moisture content calculated from the two weighing results is less than 1%, and the experiment is stopped.

5. The method for detecting forest combustibles and calculating their load according to claim 3, characterized in that: The test method of the ignition point is as follows: the sample is crushed, ground with agate, and then crushed, weighed and placed in a test tube, and then placed in a ignition point instrument, the sample is burned, and the ignition point of the sample is measured.

6. A method for detecting forest combustibles and calculating their load according to claim 3, characterized in that: The calorific value testing method is as follows: the sample is crushed, the mass is weighed and recorded, and the sample is placed in a calorimeter to measure the calorific value.

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