Method for quantifying density of surface soil habitat soil arthropods based on trap method

Abstract

The invention relates to the technical field of soil ecology, and particularly discloses a method for quantifying the density of topsoil habitat soil arthropods based on a trap method.The method comprises the following steps that S1, trap method sampling is conducted, specifically, when a soil arthropod sample is collected, a soil auger is used for digging out a trap, a trap cup containing preserving fluid is placed in the trap for soil animal investigation, and the soil arthropod sample is collected; the time duration is one week which is used most widely in the literature; s2, sampling by a digging method: when a soil arthropod sample is collected, placing a prepared sampling frame of one square meter on sampling soil, digging and collecting soil animals with the depth of 10cm in the sampling frame, picking large arthropods by using a hand picking method, and separating medium soil animals such as springtails, mites and insects by using a dry funnel method. According to the method for quantifying the density of the surface soil habitat soil arthropods based on the trap method, the actual soil excavation area can be reduced to the maximum extent, the damage to the soil structure of a sampling field is reduced, and the possibility is provided for long-term experiments.

Description

Technical Field

[0001] This invention relates to the field of soil ecology technology, specifically to a method for quantifying the density of soil-dwelling arthropods based on the trapping method. Background Technology

[0002] Topsoil arthropods refer to a group of animals that mainly live in the topsoil and litter layer, including ants, beetles, spiders, centipedes, and isowhoppers. They are highly mobile, sensitive to changes in light, temperature, and humidity, and play a vital role in the soil ecosystem. Topsoil-dwelling animals promote the decomposition of organic matter and nutrient cycling by feeding on litter, microorganisms, or other small animals, while also participating in the formation and improvement of soil structure. Their species composition and abundance variations are often used as important biological indicators for evaluating soil quality and ecological conditions, and are crucial for maintaining ecosystem stability.

[0003] Trapping is a common method for collecting soil animals, primarily used to obtain highly mobile surface and shallow soil animals. Common forms include trap cups or trap bottles, buried flush with the ground surface, filled with preservatives or attractants to prevent animal escape and decay. Animals are collected by falling into the trap through their own movement. This method is simple to operate, low in cost, and allows for long-term continuous monitoring, making it suitable for comparing soil animal community structure across different habitats or time periods. However, due to the varying activity levels of surface-dwelling soil animals, trapping cannot accurately assess their density; the amount obtained from different groups is primarily determined by both their individual density and activity level.

[0004] Therefore, how to use trapping methods to collect soil animals and accurately assess their density is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To solve the above technical problems, the present invention is implemented through the following technical solution: a method for quantifying the density of terrestrial arthropods based on the trapping method, comprising the following steps: S1. Trapping method sampling: When collecting soil arthropod samples, first use a soil drill to dig a trap, place a trap cup containing preservation fluid in the trap to conduct soil animal surveys, and use the most widely used method in the literature, one week, for the duration. S2. Excavation sampling: When collecting soil arthropod samples, place a prepared one-square-meter sampling frame on the soil and excavate the soil animals at a depth of 10cm in the sampling frame. Large arthropods are picked up by hand, while medium-sized soil animals such as springtails, mites and insects are separated by dry funnel method. S3. Classify and identify the soil arthropods collected in S1 and S2, identify them to the species level and count the number of each species. At the same time, classify them into different functional groups according to their body size (large arthropods, medium arthropods) and their respective dominance (dominant species, common species and rare species). S4. Based on the relationship between the actual density and leg length (mobility) of different functional groups of soil arthropods, construct linear conversion coefficients between the capture density and actual density in traps for different functional groups; S5. Based on the vegetation cover of various ecosystems such as grassland, woodland and farmland, optimize the linear relationship between soil arthropod activity capacity and actual density in the formula, and develop a method for assessing the density of surface soil arthropods based on the trapping method.

[0006] Preferably, in step S1, the trap cup has a diameter of 5cm and a height of 15cm to ensure that soil animals cannot escape.

[0007] Preferably, the preservation solution in step S1 is 100% alcohol, which facilitates the morphological and molecular identification of soil animals.

[0008] Preferably, the sampling frame in step S2 is made of stainless steel and has dimensions of 1m x 1m x 30cm to ensure that soil arthropods do not escape.

[0009] Preferably, the terrestrial arthropod groups described in step S3 can be divided into 6 functional groups, namely, dominant species of large arthropods, common species of large arthropods, rare species of large arthropods, dominant species of medium-sized arthropods, common species of medium-sized arthropods, and rare species of medium-sized arthropods.

[0010] Preferably, the conversion coefficient in the calculation formula for different groups in step S4 is the actual density of the excavation method / density in the trap * mobility (leg length).

[0011] Preferably, in step S5, the different plant densities in different ecosystems will affect the movement speed of soil arthropods. Therefore, it is necessary to construct the conversion coefficient of different ecosystems by combining the barrier strength (plant diameter * plant density) of different ecosystems.

[0012] It has the following beneficial effects: This invention employs a trap sampling method, which can minimize the actual soil excavation area, reduce damage to the soil structure at the sampling site, and provide the possibility for long-term experiments.

[0013] The invention combines soil animal mobility, ecosystem barrier index and actual soil animal density to fit a formula, which can derive the density conversion coefficient of surface soil arthropods based on the trap method, and use this to infer the true density of surface soil arthropods in different ecosystems.

[0014] The adoption of this method greatly reduces soil damage and manpower usage, and provides a qualitative and quantitative sample collection method for soil animal surveys. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the first embodiment, the present invention provides a technical solution: a method for quantifying the density of soil-dwelling arthropods based on the trapping method, using farmland within the grounds of the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences as the experimental site, taking dominant taxa as an example, the specific process is as follows: Step 1, Sampling by Trapping Method: In the selected farmland area, first use a soil drill to dig a trap pit (diameter: 5.2cm, depth: 16cm), place the trap cup (diameter: 5cm, depth: 15cm) in the trap pit, add 100% ethanol to the cup to 1 / 3 of the cup's capacity, and leave it for 7 days; Step 2, Excavation sampling: In the selected farmland area, a stainless steel frame measuring 1m x 1m x 30cm was placed on the soil to prevent soil animals from escaping. Soil samples were collected from a depth of 10cm within the sampling frame. First, all the soil was placed in a transparent plastic sheet, and large arthropods were picked out by hand. The remaining soil after the hand-picking method was packaged into self-sealing bags and returned to the laboratory. Medium-sized soil arthropods were separated using the dry funnel method. The third step involves classifying and identifying the soil arthropods collected using the trapping method. Taking the dominant group as an example, the main large soil arthropods are ants. Within 7 days, a total of *Hemiberlesia lataniae* (black house ants) were captured. Lasius niger 24 heads, foot length 2mm; the dominant group of medium-sized soil arthropods is *Gnaphalium affine* (Sandy Ficus pumila). Folsomia arena A total of 55 animals were captured within 7 days, with a foot length of 0.8 mm. The fourth step involves classifying and identifying the soil arthropods collected using the excavation method. Taking the dominant group as an example, the main large soil arthropods are ants, and a total of black ants (*C. spp.*) were captured. Lasius niger 125 individuals, foot length 2 mm; the dominant group of medium-sized soil arthropods is *Gnaphalium affine* (Sandy Ficus pumila). Folsomia arena A total of 189 animals were captured, with a foot length of 0.8 mm. Conversion coefficient calculation: The specific formula is: Trap density * Conversion coefficient K * Mobility (leg length: mm) = Digging density (actual density); Calculation of the conversion coefficient for the large soil arthropod *Ceratophyllum demersum*: Trap method captures 24 individuals, leg length 2 mm; Digging method captures 125 individuals, leg length 2 mm; 24 individuals * Conversion coefficient Klarge * 2 mm = 125 individuals; Conversion coefficient Klarge = 125 individuals / 24 individuals / 2 mm = 2.6 / mm leg length; Calculation of the conversion coefficient for the medium-sized animal *Fleabice*: 55 individuals * Conversion coefficient Kmedium * 0.8 mm = 189 individuals; Conversion coefficient Kmedium = 189 individuals / 55 individuals / 0.8 mm = 4.3 / mm leg length. Common and rare species of large and medium-sized terrestrial soil arthropods can be calculated based on the transformation coefficients Kmax and Krare of large and medium-sized arthropods, which can be used to assess the actual density of dominant, common, and rare species of terrestrial large and medium-sized soil arthropods.

[0017] Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art or related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be applied according to conventional methods in the art.

Claims

1. A method for quantifying the density of terrestrial arthropods based on the trapping method, characterized in that, Includes the following steps: S1. At the sampling site, trap pits were dug, and the trap method was used to collect samples of soil arthropods that live on the surface. S2. Collect topsoil arthropods at locations no more than 5 meters from the trap collection point using the digging method. S3. Classify and identify the terrestrial soil arthropods in S1 and S2, and obtain the names of each species and the number of each species. S4. Classified into 6 functional groups according to body size and abundance; S5. Based on the vegetation cover of various ecosystems such as grassland, woodland and farmland, optimize the linear relationship between soil arthropod activity capacity and actual density in the formula, and develop a method for assessing the density of surface soil arthropods based on the trapping method.

2. The method for quantifying the density of terrestrial arthropods based on the trapping method according to claim 1, characterized in that: In step S1, the trap cup has a diameter of 5cm and a height of 15cm.

3. The method for quantifying the density of terrestrial arthropods based on the trapping method according to claim 1, characterized in that: The preservation solution in step S1 is 100% alcohol.

4. The method for quantifying the density of terrestrial arthropods based on the trapping method according to claim 1, characterized in that: In step S2, the sampling frame is made of stainless steel and has dimensions of 1m x 1m x 30cm.

5. The method for quantifying the density of terrestrial arthropods based on the trapping method according to claim 1, characterized in that: The terrestrial arthropod groups mentioned in step S4 can be divided into 6 functional groups, namely, dominant species of large arthropods, common species of large arthropods, rare species of large arthropods, dominant species of medium-sized arthropods, common species of medium-sized arthropods, and rare species of medium-sized arthropods.

6. The method for quantifying the density of terrestrial arthropods based on the trapping method according to claim 1, characterized in that: The conversion coefficient in the calculation formula for different groups in step S5 is the actual density of the excavation method / the density activity capacity in the trap.

7. The method for quantifying the density of terrestrial arthropods based on the trapping method according to claim 1, characterized in that: In step S5, the conversion coefficients of different ecosystems are constructed by combining the barrier strength of different ecosystems.