Method for comprehensive evaluation of fire resistance of plant species

Abstract

The application discloses a comprehensive evaluation method for fire resistance of plant species, and solves the limitation of the existing evaluation method for fireproof species, and provides a method for evaluating the fire resistance of the species by comprehensively considering the physical and chemical properties and appearance characteristics of the species, which specifically comprises the following steps: 1) water content determination; 2) ignition point determination; 3) calorific value determination; 4) density determination; 5) image scanning and scoring; and 6) data conversion. The method can solve the limitation of the existing evaluation method for fireproof species, and can evaluate the fire resistance of the species by comprehensively considering the physical and chemical properties and appearance characteristics of the species.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of forestry engineering, in particular to a method for comprehensive evaluation of fire resistance of plant species. BACKGROUND

[0002] In recent years, with the optimization of ecological environment and the increasing of forest resources, the situation of forest fire prevention is becoming more and more tense. In response to the occurrence of forest fires, in addition to human intervention to eliminate fire, building a forest fire belt composed of plant species with outstanding fire resistance is also a method to block the spread of fire. For the safety of the life and property of Chinese people and the safety of natural resources, it is of great significance to identify and evaluate the fire resistance of different plant species and to build a forest fire belt using the characteristics of different fire-resistant plants.

[0003] The traditional evaluation method of species fire resistance focuses on the independent characteristics of the species to be tested, such as ignition point, heat value, etc. In fact, the fire resistance of a species is closely related to its various characteristics, and the relationship between its physicochemical properties and external structure should be comprehensively evaluated when evaluating the fire resistance. Therefore, how to determine the fire resistance of a plant based on its physicochemical properties and external structure is a problem that needs to be considered. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for comprehensive evaluation of the fire resistance of plant species, which solves the limitations of existing fire-resistant species evaluation methods and provides a method for evaluating the fire resistance of a species by comprehensively considering its physicochemical properties and appearance characteristics.

[0005] To solve the above technical problems, the technical solution adopted by the present application is: a method for comprehensive evaluation of the fire resistance of plant species, which evaluates the fire resistance of a species by comprehensively considering its physicochemical properties and appearance characteristics.

[0006] The physicochemical properties include combustion properties, including moisture content, ignition point, heat value and density of the species.

[0007] The appearance characteristic property is a biological characteristic, including crown structure.

[0008] In a preferred embodiment, the comprehensive evaluation method specifically includes the following steps:

[0009] (1) Determining the moisture content of the species

[0010] Measure the fresh weight of the plant sample to be tested, denoted as W1, and place the plant sample after measuring the fresh weight in an oven at 105°C for 24 hours to measure its dry weight, denoted as W2.

[0011] Then calculate the moisture content W of the sample:

[0012]

[0013] (2) Determination of ignition point of species

[0014] Take 0.1 ± 0.01 g of sample powder dried to constant weight and passed through a 60-mesh sieve, place it in a quartz test tube, add 0.075 ± 0.001 g of sodium nitrite to mix with the sample to be tested, and use an SJRDY-5000 microcomputer ignition tester to determine the ignition point of each sample;

[0015] (3) Determination of heat value of species

[0016] Weigh and record the test paper, take 0.5000-0.8000 g of sample powder dried to constant weight and passed through a 60-mesh sieve, and place it in the test paper, then place the sample in the oxygen bomb cylinder, charge oxygen at 2.8-3.0 MP for 20 s, input the sample weight, test paper weight, sample number into the microcomputer automatic heat meter, start the measurement, record the data after the measurement is completed, and repeat the measurement for each sample 3 times;

[0017] (4) Determination of density of species

[0018] Add 500 ml of water to a container with a scale, then immerse the non-dried plant sample in the water, measure the change in water level, record the sample volume V1, and measure the density p

[0019]

[0020] (5) Determination of crown structure score of species

[0021] In the morning or evening without direct sunlight, use a crown scanner to take pictures of the crown of the plant to be tested, place the shooting rod horizontally upwards above the crown to record the A value, and below the crown to record the B value, select 4 different directions of east, west, south, and north for remote shooting, take 3 times for each direction, then use image processing software to process the image, analyze the crown structure, leaf density, leaf layer dryness ratio, and fallen leaves, and determine the crown type of the species (conical, cylindrical, tower, spherical, hemispherical, oval, elliptical, inverted oval, umbrella, weeping), then use the scoring method (5 points) to determine the crown structure score of the tree species to be tested according to the reference materials and expert opinions;

[0022] (6) Combine the characteristics of the plant to be tested measured in the above five steps, divide the above five numerical values into two levels, and convert the data items of different dimensions into the same utility unit, the conversion formula is:

[0023] U = 1-0.9(V max -V) / (V max -V min ) (1)

[0024] U = 1-0.9(V-Vmax ) / (V max -V min ) (2)

[0025] Wherein (1) is an incremental formula, (2) is a decreasing formula.

[0026] In the preferred scheme, in the step 6), the heat value in the index of species evaluation is standardized by a decreasing formula, and the rest indexes are standardized by an increasing formula.

[0027] In the preferred scheme, according to the formula:

[0028]

[0029] The comprehensive evaluation value of each plant species to be tested is calculated, and the fire resistance of each plant species is determined according to the size of the value.

[0030] In the formula, λ refers to the ratio of different characteristics in different levels, wherein:

[0031] In the combustion characteristics, the ratio of moisture content is 0.4030, the ratio of crude fat is 0.0888, the ratio of heat value is 0.1115, and the ratio of ignition point is 0.2267.

[0032] In the biological characteristics, the ratio of crown density is 0.0398, the ratio of leaf texture is 0.0169, the ratio of bark characteristics is 0.0101, the ratio of tree characteristics is 0.0634, and the ratio of natural pruning condition is 0.0398.

[0033] The provided plain type biological barrier construction method comprehensively considers various characteristics of the plant to be tested, and can well estimate the temperature at which the fireproof plant is ignited, the amount of heat released, whether the tree structure is easy to be ignited, and the like when the forest fire occurs, thereby providing a strong basis for forest fire prevention belt construction and tree species selection. BRIEF DESCRIPTION OF DRAWINGS

[0034] The application will be further described below in combination with the drawings and examples:

[0035] Figure 1 The evaluation flowchart of the application. DETAILED DESCRIPTION

[0036] Example 1:

[0037] A plant species fire resistance comprehensive evaluation method is characterized by: the fire resistance of the species is evaluated by comprehensively considering the physicochemical characteristics and appearance characteristic properties of the species.

[0038] The physicochemical characteristics are combustion characteristics, including the moisture content, ignition point, heat value and density of the species.​

[0039] The appearance characteristic property is a biological characteristic, including canopy structure.

[0040] The comprehensive evaluation method of the fire resistance of the plant species specifically comprises the following steps:

[0041] (1) Determining the water content of the species

[0042] The fresh weight of the plant sample to be measured is measured and recorded as W1, and the dried weight of the plant sample after being dried at 105 DEG C for 24 hours is measured and recorded as W2;

[0043] Then the water content W of the sample is calculated:

[0044]

[0045] (2) Determining the ignition point of the species

[0046] 0.1 ± 0.01 g of the sample powder dried to a constant weight and passed through a 60-mesh sieve is weighed and placed in a quartz test tube, 0.075 ± 0.001 g of sodium nitrite is added and mixed uniformly with the sample to be measured, and the ignition point of each sample is determined using a burning point tester;

[0047] (3) Determining the calorific value of the species

[0048] The test paper is weighed and recorded, 0.5000-0.8000 g of the sample powder dried to a constant weight and passed through a 60-mesh sieve is weighed and wrapped in the test paper, the sample is placed in an oxygen bomb cylinder, oxygen is filled for 20 s at 2.8-3.0 MP, the sample weight, the test paper weight, the sample number are input into a microcomputer automatic calorimeter, the determination is started, the data is recorded after the determination is completed, and each sample is determined repeatedly for 3 times;

[0049] (4) Determining the density of the species

[0050] 500 ml of water is added to a container with a scale, and then the plant sample without drying is immersed in the water, the change of the water level is measured, the sample volume V1 is recorded, and the density p is measured

[0051]

[0052] (5) Determining the canopy structure score of the species

[0053] In the morning or evening without direct sunlight, the crown layer scanner is used to take pictures of the plant crown layer. When operating, the shooting rod is placed horizontally upwards above the crown layer to record the A value, and below the crown layer to record the B value. Remote shooting is selected in four different directions, east, west, south and north, and each direction is shot three times. Then the image processing software is used to process the image, analyze the crown structure, leaf density, leaf layer dryness ratio and fallen leaves, and determine the crown type of the species (conical, cylindrical, tower, spherical, hemispherical, oval, elliptical, inverted oval, umbrella, weeping). The scoring method (5 points) is used to determine the crown structure score of the tree species according to the reference materials and expert opinions.

[0054] (6) The characteristics of the plant to be tested measured in the above five steps are integrated, the above five numerical values are divided into two levels, namely combustion characteristics (ignition point, heat value, density, moisture content) and biological characteristics (crown structure), and different dimensional data items are converted into the same utility unit. The conversion formula is:

[0055] U = 1-0.9 (V max -V) / (V max -V min ) (1)

[0056] U = 1-0.9 (V-V max ) / (V max -V min ) (2)

[0057] Wherein (1) is an increasing formula, and (2) is a decreasing formula.

[0058] In the preferred scheme, in the step 6) above, the heat value in the species evaluation index is standardized by the decreasing formula, and the rest of the indexes are standardized by the increasing formula.

[0059] In addition, after the conversion of data items with different dimensions is completed, the comprehensive evaluation value of each plant species to be tested is calculated according to the formula:

[0060]

[0061] The fire resistance of each plant species is determined according to the size of the comprehensive evaluation value.

[0062] In the formula, λ refers to the proportion of different characteristics in different levels, wherein:

[0063] In the combustion characteristics, the moisture content accounts for 0.4030, the crude fat accounts for 0.0888, the heat value accounts for 0.1115, and the ignition point accounts for 0.2267.

[0064] ​Biological characteristics, crown density accounted for 0.0398, leaf texture accounted for 0.0169, bark characteristics accounted for 0.0101, tree characteristics accounted for 0.0634, natural pruning accounted for 0.0398.

[0065] Example 2:

[0066] On the basis of example 1, in the fireproof tree species screening experiment, 10 kinds of arbor fireproof tree species were selected, which were Eriobotrya japonica (Thunb.) Lindl., Citrus reticulata Blanco, Ginkgo biloba L., Myrica rubra (Lour.) S.et Zucc., Koelreuteria paniculata Laxm., Magnolia grandiflora L., Osmanthus sp., Cinnamomum camphora (L.

[0067] presl), Metasequoia glyptostroboides Hu & W.C.Cheng, llex chinensis Sims.

[0068] After the completion of field investigation and sampling, the relevant data obtained by the above five steps are shown in table 1 and table 2:

[0069] Table 1: Determination of sample content and combustion index

[0070]

[0071] Table 2: Sample ecology characteristic scoring table

[0072]

[0073] According to the data obtained from table 1 and 2, according to the formula (1) and formula (2) given in step 6) of example 1, the data items of different dimensions are converted into the same data unit, and table 3 and 4 are obtained:

[0074] Table 3: Comprehensive evaluation value of sample internal fuel and combustion performance

[0075]

[0076] Table 4: Comprehensive evaluation value of biological ecology characteristics

[0077]

[0078] Then according to the comprehensive evaluation value of the biological ecological characteristics and combustion characteristics of different species and their weights, the comprehensive evaluation value of the fire resistance of 10 kinds of arbor tree species can be calculated, and the results are shown in Table 5.

[0079] Table 5 Comprehensive evaluation value of fire resistance of 10 kinds of arbor tree species

[0080]

[0081] From the above table, it can be seen that:

[0082] The tree species with comprehensive evaluation above 0.7 points are Magnolia grandiflora, Michelia, Ilex and Cinnamomum camphora;

[0083] The tree species with comprehensive evaluation between 0.5 and 0.7 points are Myrica rubra, Pyrus, Osmanthus fragrans and Ginkgo;

[0084] The tree species with comprehensive evaluation below 0.4-0.5 points are Metasequoia glyptostrobus, and the tree species with comprehensive evaluation below 0.4 points are Koelreuteria paniculata.

Claims

1. A method for comprehensive evaluation of fire retardant ability of a plant species, characterized in that: The fireproof ability of the species is evaluated by comprehensively evaluating the physicochemical properties and appearance characteristic properties of the species; The physicochemical properties are combustion properties, including water content, ignition point, calorific value and density of the species; The appearance characteristic properties are biological properties, including crown structure; Specifically, the method comprises the following steps: (1) measuring the water content of the species The fresh weight of the plant sample to be tested is measured and recorded as The plant sample after measuring the fresh weight is placed in a 105°C condition for drying for 24 hours, and the dry weight is measured and recorded as ; Then, the water content W of the sample is calculated: (2) measuring the ignition point of the species 0.1±0.01 g of sample powder dried to a constant weight and sieved through a 60-mesh sieve is weighed and placed in a quartz test tube, 0.075±0.001 g of sodium nitrite is added and mixed uniformly with the sample to be tested, and a burning point tester is used to measure the burning point of each sample; (3) measuring the calorific value of the species The test paper is weighed and recorded, 0.5000-0.8000 g of sample powder dried to a constant weight and sieved through a 60-mesh sieve is weighed and wrapped in the test paper, the sample is placed in an oxygen bomb cylinder, oxygen is filled at 2.8-3.0 MPa for 20 s, the sample is placed in a microcomputer automatic calorimeter, the sample weight, test paper weight, sample number are input, and the measurement is started. After the measurement is completed, the data is recorded, and each sample is measured repeatedly for three times; (4) measuring the density of the species Into a graduated vessel, 500 ml of water is added, then the non-dried plant sample is introduced into the water, the water level change is measured, and the sample volume is recorded , the density is measured (g / cm 2 ) (5) measuring the crown structure score of the species The crown layer of the plant to be tested is photographed by using a crown scanning instrument, the crown layer type of the species is determined, and the crown structure score of the plant to be tested is determined by using a scoring method; (6) the properties of the plant to be tested measured in the above five steps are integrated, the five values are divided into two levels, and the data items of different dimensions are converted into the same utility unit, and the conversion formula is: Wherein (1) is an increasing formula, and (2) is a decreasing formula; In the step 6), the calorific value in the evaluation index of the species is standardized by using the decreasing formula, and the remaining indexes are standardized by using the increasing formula; According to the formula: The comprehensive evaluation value of each plant species is calculated, and the fire resistance of each plant species is determined according to the value. The comprehensive evaluation value of each plant species is calculated, and the fire resistance of each plant species is determined according to the value. wherein refers to the ratio of different characteristics in different levels, wherein: In the combustion properties, the water content accounts for 0.4030, the crude fat accounts for 0.0888, the calorific value accounts for 0.1115, and the ignition point accounts for 0.2267; In the biological properties, the crown density accounts for 0.0398, the leaf texture accounts for 0.0169, the bark characteristics accounts for 0.0101, the tree characteristics accounts for 0.0634, and the natural whole branch condition accounts for 0.0398.

2. The method according to claim 1, wherein the method is characterized by: In the step 5), the crown layer picture of the plant to be tested is photographed by using the crown scanning instrument in the weather condition without direct sunlight, the shooting rod is horizontally placed upwards above the crown layer to record the A value, and the B value is recorded below the crown layer. Remote control shooting is performed in four different directions of east, west, south and north, each direction is photographed for three times, then the image is processed by using an image processing software, and the crown structure of the species is analyzed.

3. The method of claim 1, wherein the method further comprises: determining the fire retardant capability of the plant species. In the step 5), the crown structure of the species mainly includes conical shape, cylindrical shape, sharp tower type, spherical shape, hemispherical shape, oval shape, elliptical shape, inverted oval shape, umbrella shape and weeping shape.

Images