In-situ construction method of degraded alpine grassland soil seed bank

Abstract

The present application relates to the field of plant ecological restoration, in particular to a method for constructing in-situ soil seed bank of degraded alpine grassland, comprising the following steps: selecting a target area in the degraded alpine grassland and its surrounding range, marking the position with a quadrat frame, digging a pit, crushing and removing impurities from the soil, backfilling the pit with the soil, laying a nylon net on the bottom of the pit, inserting an acrylic plate into the walls of the pit, covering the acrylic plate with a nylon net, and building an "arch" support covered with a nylon net around the pit; after adjusting the humidity of the backfilled soil, counting the data of the soil seed bank. The method takes into account the controllability and ecological authenticity, thereby ensuring that the obtained soil seed bank data has scientificity, reliability and practical reference value.

Description

Technical Field

[0001] This invention relates to the field of plant ecological restoration, and in particular to an in-situ method for constructing a soil seed bank in degraded alpine grassland. Background Technology

[0002] A soil seed bank refers to the total number of viable seeds present in the topsoil and deeper layers of soil. This includes seeds produced by the current vegetation as well as seeds remaining dormant or viable from previous periods. As a memory bank of vegetation dynamics, the soil seed bank not only records historical succession information but also holds multiple crucial significances in ecological research: First, it is a potential source of propagules, providing germplasm resources for vegetation restoration after disturbances such as fires, grazing, or cultivation, and serving as an important basis for predicting the direction of community succession and restoration potential. Second, it is a key ecological factor limiting the effectiveness of degraded grassland restoration, directly affecting the composition and species diversity of the restored plant community, and is also a crucial reference for species pattern configuration or species matching before degraded grassland restoration. Therefore, revealing scientifically accurate soil seed bank data is of great importance for understanding community succession mechanisms, assessing biodiversity maintenance strategies, and solving the widespread problem of degraded grassland restoration worldwide.

[0003] Currently, while soil seed bank research has established a relatively mature and standardized operating procedure, existing methods still have three significant shortcomings. First, under non-in-situ culture conditions, the difference between the field and indoor environments can easily lead to biases or even distortions in germination data, increasing the uncertainty in designing species configuration schemes before degraded grassland restoration. Second, limited by the small sample size of the pot method, researchers often underestimate the actual contribution of native soil seed banks, resulting in inappropriate matching decisions and resource waste. Third, traditional methods rely on regular manual management, significantly increasing labor costs and research burden. These problems, combined, not only weaken the reliability of seed bank data but also limit their guiding effectiveness in degraded grassland restoration practices, urgently requiring solutions through methodological optimization.

[0004] Wolfgang Siewert et al.<Dispersal-Dormancy Relationships in AnnualPlants: Putting Model Predictions to the Test> A method for constructing in-situ soil seed banks was proposed. The core idea is to use herbicides to remove existing annual plants in the study area to cut off local reproductive input, and then cover the area with a fine, permeable synthetic mesh to prevent external seed diffusion, ensuring that the germinating seedlings the following year originate entirely from the dormant seeds already present in the soil. While this method theoretically reflects the germination potential of the seed bank well, significant environmental interference exists in practice: herbicide application may alter soil microbial activity and chemical properties, while synthetic mesh mulching introduces shading and moisture retention effects. Both contribute to a deviation of the soil microenvironment from its natural state, affecting seed germination and survival rates, making it difficult to accurately represent the original state of the seed bank. This interference is particularly pronounced in environmentally sensitive and ecologically fragile alpine grasslands, potentially severely weakening the scientific validity and reference value of the data. Therefore, it is urgent to explore a new method for constructing soil seed banks suitable for the habitat characteristics of degraded alpine grasslands to ensure that the obtained data are scientifically sound, authentic, and provide practical guidance. Summary of the Invention

[0005] To address the above problems, this invention provides an in-situ construction method for a seed bank of degraded alpine grassland soil, characterized by the following steps: 1) In the degraded alpine grassland and its surrounding area, avoiding rodent burrows and vegetation areas, select areas with a slope of ≤20° as the target area for constructing a soil seed bank; 2) In the target area determined in step 1), mark the position with a quadrat frame, dig a pit to collect soil, break the soil, and sieve it to remove impurities to obtain the soil body; 3) At the bottom of the pit obtained in step 2), lay a layer of nylon netting with the same area as the pit bottom. Then, insert acrylic sheets vertically into the pit bottom, close to the four walls of the pit, to form a square frame. Finally, backfill the pit with the soil obtained in step 2) and spread it flat. 4) Cover the square frame obtained in step 3) with nylon netting and fix it to the upper edge of the frame with tape. Then, build an "arch"-shaped support 15-25cm away from the edge of the frame so that the support covers the entire frame area.

[0006] 5) Cover and fix the nylon netting onto the "bow" shaped support obtained in step 4). After standing, adjust the humidity of the backfilled soil so that the difference between its moisture content and the humidity of the surrounding original degraded alpine grassland is controlled within 15%. 6) Continuously observe the backfilled soil for which moisture content has been regulated in step 5), and record the number and composition of species regularly until both no longer change. The number and composition of species at this point are the data of the degraded alpine grassland soil seed bank.

[0007] Furthermore, the degraded alpine grassland mentioned in step 1) includes degraded alpine steppe and degraded alpine meadow.

[0008] Furthermore, within the degraded alpine grassland and its surrounding 100m radius, the vegetation area to be avoided is the reed mound; the slope of the selected area is ≤20°.

[0009] Furthermore, within the degraded alpine meadow and its surrounding 50-100m range, the vegetation areas to be avoided are patchy grass carpet areas, and areas within 20m of the river valley should also be avoided; the slope of the selected area should be ≤10-15°.

[0010] Furthermore, in step 2), the dimensions of the sample frame include 1×1 m, and the soil is beaten with a rubber hammer until completely broken.

[0011] Further, the specifications of the pit in step 3) include a length of 1 m, a width of 1 m, and a depth of 10-15 cm, preferably 12-15 cm; the specifications of the nylon mesh are 150-200 mesh.

[0012] Further, the acrylic sheet in step 3) has the following specifications: 100cm in length, 25-30cm in height, and 0.2-0.5cm in thickness; it is inserted into the acrylic sheet so that it is buried 15cm underground and protrudes 10-15cm above the ground, preferably 12-15cm above the ground.

[0013] Furthermore, the thickness of the backfilled soil in step 3) is 10.0~12.0cm for degraded alpine grassland and 8.0cm~12.0cm for degraded alpine meadow.

[0014] Furthermore, the thickness of the backfilled soil is 10.0 cm for degraded alpine grassland and 10.0 cm for degraded alpine meadow.

[0015] Furthermore, the nylon mesh described in step 4) has a mesh size of 20-40. The "bow" support uses PVC flexible tubing with a diameter of 1.0~2.0cm and a wall thickness of 0.1~0.3cm, and is erected 20cm away from the edge of the square frame; the top of the bow is 100~150cm from the ground.

[0016] Further, in step 5), the nylon net is a transparent nylon net with a mesh size of 1.0~5.0 cm; it is left to stand for 48 hours; the difference between the moisture content of the backfill soil and the humidity of the surrounding original degraded alpine meadow is controlled within 15%; the difference between the moisture content of the backfill soil and the humidity of the surrounding original degraded alpine meadow is controlled within 10%.

[0017] The degraded alpine grassland described in this invention is a degraded ecosystem type relative to the native alpine grassland. The native alpine grassland is distributed in areas above 3200 m altitude, with cold-resistant xerophytic perennial herbs or small semi-shrubs as the dominant species, and has a zonal distribution pattern. When it is subjected to unreasonable human interference or natural factors, the vegetation cover decreases, the dominant species degrade, the soil quality declines, and the community undergoes reverse succession that is opposite to the direction of evolution, thus forming a degraded alpine grassland.

[0018] The degraded alpine meadow described in this invention is a degraded ecosystem type relative to the native alpine meadow. The native alpine meadow is distributed in areas above 3000 m in altitude, dominated by cold-climate perennial herbaceous plants, especially plants of the genus Kobresia in the family Cyperaceae. Under continuous disturbance by human or natural factors, its community structure and ecological function undergo reverse succession, manifested as vegetation degradation and soil quality decline. In severe cases, it may even form "black soil type" secondary bare land, at which point a degraded alpine meadow is formed.

[0019] Compared with traditional soil seed bank research methods, this invention has the following advantages: (1) The in-situ research method of soil seed bank significantly reduces the dependence on long-term artificial management and fixed experimental sites; the research is based entirely on the natural environment in the field, and the data obtained are closer to the real state of soil seed bank, which has higher reference value for the restoration of degraded grassland.

[0020] (2) The in-situ research method of soil seed bank breaks through the limitations of traditional potted plant method in terms of container capacity, and the research results are more applicable to the restoration of large-scale degraded grasslands. At the same time, the method is simple to operate and has a clear process, making it more user-friendly for actual staff.

[0021] (3) During the in-situ study of the soil seed bank, specific target areas were selected, a specific framework and support were constructed, and nylon nets of different specifications were laid in different parts of the device. This effectively blocked the invasion of underground rhizomes of potential wandering plants and the mixing of exogenous seeds, while ensuring the normal exchange of substances and energy such as water, heat, gas, and nutrients in the soil. The method of this invention takes into account both operational controllability and ecological authenticity, thereby ensuring that the obtained soil seed bank data has scientific validity, reliability, and practical reference value.

[0022] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0023] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0024] Figure 1 Schematic diagram of the core device for in-situ research of soil seed bank (A: without top layer nylon netting; B: with top layer nylon netting); Figure 2 A schematic diagram of the PVC "bow"-shaped structure above the core device for in-situ soil seed bank research, covered with a 3.0-mesh nylon mesh (A: without top nylon mesh; B: with top nylon mesh). Figure 3 Comparative analysis of research results on different soil backfill thicknesses; Figure 4 Figure showing the change in species abundance in the soil seed bank of severely degraded alpine steppes and meadows over observation time; Figure 5 Comparative analysis of species numbers in soil seed banks of severely degraded alpine grasslands and alpine meadows; Figure 6 Comparative analysis of the number of functional groups in the seed bank of soils from severely degraded alpine grasslands and alpine meadows. Detailed Implementation

[0025] Example 1: In-situ construction method of seed bank of degraded alpine steppe soil 1) Within a 100 m radius of the degraded alpine grassland and its surrounding area, avoiding rodent burrows and reed mounds, select an area with a slope of ≤20° as the target area for constructing a soil seed bank; 2) After marking the target area determined in step 1) with a 1×1 m square, excavate a pit 1 m long, 1 m wide and 15 cm deep. Then, use a rubber hammer to beat the excavated soil until it is completely broken. After sieving to remove impurities, the soil body is obtained. 3) At the bottom of the pit obtained in step 2), lay a layer of 150-mesh nylon netting with the same area as the pit bottom. Then, insert a transparent acrylic sheet with a length of 100cm, a height of 30cm, and a thickness of 0.5cm vertically into the pit, close to the four walls of the pit, so that the sheet is buried 15cm underground and protrudes 15cm above the ground, forming a square frame. Finally, backfill the pit with the soil obtained in step 2) and spread it to a thickness of 12.0cm. Then, gently smooth the surface of the soil with only the weight of the shovel, without applying any additional pressure during the process. 4) Cover the square frame obtained in step 3) with 20-mesh nylon netting and fix it to the upper edge of the frame with tape. Then, at a distance of 20cm from the edge of the frame, build an "arch"-shaped support using PVC hose with a diameter of 1.0cm and a wall thickness of 0.1cm, so that the support covers the entire frame area and the top of the arch is 150cm above the ground.

[0026] 5) Cover and fix the "bow" shaped support obtained in step 4) with a transparent nylon net with a mesh size of 1.0 cm. After standing for 48 hours, use a handheld soil moisture meter to measure the moisture content of the backfilled soil and the surrounding original degraded alpine grassland soil. If the difference between the two is within 15%, there is no need to add water to the backfilled soil. On the contrary, if the difference exceeds 15%, the backfilled soil needs to be watered until the moisture difference between the two is controlled within 15%. 6) Continuously observe the backfilled soil for which moisture content has been regulated in step 5), and record the number and composition of species regularly until both no longer change. The number and composition of species at this point are the data of the degraded alpine grassland soil seed bank.

[0027] Example 2: In-situ construction method of seed bank of degraded alpine grassland soil 1) Within a 100 m radius of the degraded alpine grassland and its surrounding area, avoiding rodent burrows and reed mounds, select an area with a slope of ≤20° as the target area for constructing a soil seed bank; 2) After marking the target area determined in step 1) with a 1×1 m square frame, excavate a pit 1 m long, 1 m wide and 12 cm deep. Then, use a rubber hammer to beat the excavated soil until it is completely broken. After sieving to remove impurities, the soil body is obtained. 3) At the bottom of the pit obtained in step 2), lay a layer of 200-mesh nylon netting with the same area as the pit bottom. Then, insert a transparent acrylic sheet with a length of 100cm, a height of 27cm, and a thickness of 0.2cm vertically into the pit, close to the four walls of the pit, so that the sheet is buried 15cm underground and 12cm above the ground, forming a square frame. Finally, backfill the pit with the soil obtained in step 2) and spread it to a thickness of 10.0cm. Then, gently smooth the surface of the soil with only the weight of the shovel, without applying any additional pressure during the process. 4) Cover the square frame obtained in step 3) with 40-mesh nylon netting and fix it to the upper edge of the frame with tape. Then, at a distance of 20cm from the edge of the frame, build an "arch"-shaped support using PVC hose with a diameter of 2.0cm and a wall thickness of 0.3cm, so that the support covers the entire frame area and the top of the arch is 100cm above the ground.

[0028] 5) Cover and fix the "bow" shaped support obtained in step 4) with a transparent nylon net with a mesh size of 5.0 cm. After standing for 48 hours, use a handheld soil moisture meter to measure the moisture content of the backfilled soil and the surrounding original degraded alpine grassland soil. If the difference between the two is within 15%, there is no need to add water to the backfilled soil. On the contrary, if the difference exceeds 15%, the backfilled soil needs to be watered until the moisture difference between the two is controlled within 15%. 6) Continuously observe the backfilled soil for which moisture content has been regulated in step 5), and record the number and composition of species regularly until both no longer change. The number and composition of species at this point are the data of the degraded alpine grassland soil seed bank.

[0029] Example 3: In-situ construction method of seed bank in degraded alpine meadow soil 1) Within a 50 m radius of the degraded alpine meadow and its surrounding area, avoiding areas with rodent burrows, patchy grass carpets, and valleys within a 20 m radius, select areas with a slope of ≤10° as the target area for constructing a soil seed bank. 2) After marking the target area determined in step 1) with a 1×1 m square, excavate a pit 1 m long, 1 m wide and 15 cm deep. Then, use a rubber hammer to beat the excavated soil until it is completely broken. After sieving to remove impurities, the soil body is obtained. 3) At the bottom of the pit obtained in step 2), lay a layer of 200-mesh nylon netting with the same area as the pit bottom. Then, insert a transparent acrylic sheet with a length of 100cm, a height of 30cm, and a thickness of 0.2cm vertically into the pit bottom, close to the four walls of the pit, so that the sheet is buried 15cm underground and 15cm above the ground, forming a square frame. Finally, backfill the pit with the soil obtained in step 2) and spread it to a thickness of 12cm. Then, gently smooth the surface of the soil with only the weight of the shovel, without applying any additional pressure during the process. 4) Cover the square frame obtained in step 3) with 40-mesh nylon netting and fix it to the upper edge of the frame with tape. Then, at a distance of 20cm from the edge of the frame, build an "arch"-shaped support using PVC hose with a diameter of 2.0cm and a wall thickness of 0.3cm, so that the support covers the entire frame area and the top of the arch is 100cm above the ground.

[0030] 5) Cover and fix the "bow" shaped support obtained in step 4) with a transparent nylon net with a mesh size of 5.0 cm. After standing for 48 hours, use a handheld soil moisture meter to measure the moisture content of the backfilled soil and the surrounding original degraded alpine meadow soil. If the difference between the two is within 10%, there is no need to add water to the backfilled soil. On the contrary, if the difference exceeds 10%, the backfilled soil needs to be watered until the moisture difference between the two is controlled within 10%. 6) Continuously observe the backfilled soil for which moisture content has been regulated in step 5), and record its species quantity and composition regularly until both no longer change. The species quantity and composition at this point are the data of the degraded alpine meadow soil seed bank.

[0031] Example 4: In-situ construction method of seed bank of degraded alpine meadow soil 1) Within a 100 m radius of the degraded alpine meadow and its surrounding area, avoiding areas with rodent burrows, patchy grass carpets, and valleys within a 50 m radius, select areas with a slope of ≤15° as the target area for constructing a soil seed bank. 2) After marking the target area determined in step 1) with a 1×1 m square, excavate a pit 1 m long, 1 m wide and 10 cm deep. Then, use a rubber hammer to beat the excavated soil until it is completely broken. After sieving to remove impurities, the soil body is obtained. 3) At the bottom of the pit obtained in step 2), lay a layer of 150-mesh nylon netting with the same area as the pit bottom. Then, insert a transparent acrylic sheet with a length of 100cm, a height of 25cm, and a thickness of 0.5cm vertically into the pit bottom, close to the four walls of the pit, so that the sheet is buried 15cm underground and 10cm above the ground, forming a square frame. Finally, backfill the pit with the soil obtained in step 2) and spread it to a thickness of 8.0cm. Then, gently smooth the surface of the soil with only the weight of the shovel, without applying any additional pressure during the process. 4) Cover the square frame obtained in step 3) with 20-mesh nylon netting and fix it to the upper edge of the frame with tape. Then, at a distance of 20cm from the edge of the frame, build an "arch"-shaped support using PVC hose with a diameter of 1.0cm and a wall thickness of 0.1cm, so that the support covers the entire frame area and the top of the arch is 150cm above the ground.

[0032] 5) Cover and fix the "bow" shaped support obtained in step 4) with a transparent nylon net with a mesh size of 5.0 cm. After standing for 48 hours, use a handheld soil moisture meter to measure the moisture content of the backfilled soil and the surrounding original degraded alpine meadow soil. If the difference between the two is within 10%, there is no need to add water to the backfilled soil. On the contrary, if the difference exceeds 10%, the backfilled soil needs to be watered until the moisture difference between the two is controlled within 10%. 6) Continuously observe the backfilled soil for which moisture content has been regulated in step 5), and record its species quantity and composition regularly until both no longer change. The species quantity and composition at this point are the data of the degraded alpine meadow soil seed bank.

[0033] The following experimental examples further illustrate the beneficial effects of the present invention. Experimental Example 1: In-situ Study of Seed Bank in Degraded Alpine Grassland Soil 1. Study Area The First and First Teams of the Sanjiaocheng Sheep Breeding and Promotion Service Center in Gangcha County, Haibei Tibetan Autonomous Prefecture, Qinghai Province, and the Jun Ranch in Dawu Town, Maqin County, Guoluo Tibetan Autonomous Prefecture, Qinghai Province.

[0034] 2. Experiment start time Early May 2025.

[0035] 3. Natural Overview of the Study Area The study area is a severely degraded alpine grassland belonging to the First Brigade and First Squad of the Sanjiaocheng Sheep Breeding and Extension Service Center in Gangcha County, Haibei Tibetan Autonomous Prefecture, Qinghai Province. The slope is 2°, and the altitude is 3280m. The study area has a plateau continental climate with a multi-year average temperature of 0.08℃ and an average annual precipitation of 387mm. The average annual temperature is 0–0.5℃, and the soil is frozen from mid-November to mid-March of the following year. There are no obvious rodent burrows in the study area, but there are a few small mounds of reeds. The native grassland coverage is less than 30%, and the vegetation consists mainly of *Altaiculatus edulis* (Altaiculatus edulis). Heteropappus altaicus ), lanceolate cassia ( Thermopsis lanceolata ), Three-pronged Bupleurum ( Bupleurum triradiatum The main species are Stipa purpurea, etc., with a very small amount of Stipa purpurea ( Stipa purpurea ) and Kentucky bluegrass ( Poa pratensis ).

[0036] The "black soil beach" formed by severely degraded alpine meadow in Junchang Pasture, Dawu Town, Maqin County, Golog Tibetan Autonomous Prefecture, Qinghai Province, has a slope of 5° and an average altitude of 4100 m, with degraded patches accounting for more than 50%. The study area has a typical plateau continental climate. The average annual temperature is -3.8℃ to 3.5℃, with large diurnal temperature range and small annual temperature range. Solar radiation is strong, with annual sunshine hours ranging from 2313 to 2607 hours. There is no absolute frost-free period. Annual precipitation is 420–560 mm, mostly concentrated from May to October. The study area has obvious rodent burrows, with a density of approximately 1200 burrows per hectare. The experimental area is 53 m away from the nearest rodent burrow. The native grassland coverage is less than 40%, and the vegetation composition is mainly Potentilla chinensis (…). Potentilla anserina ), Fine-leaved daisy ( Ajania tenuifolia ), Siberian Polygonum ( Knorringia sibirica The vegetation is mainly composed of weeds such as _____.

[0037] 4. Material Preparation Sixty sets of transparent acrylic sheets, and 30 sets each of severely degraded alpine grassland and severely degraded alpine meadow. In each grassland type, 5 sets were used to determine in-situ soil seed bank research data, and the remaining 25 sets were used to auxiliaryly determine the optimal soil backfill thickness (sheet specifications: length 100cm, height 30cm, thickness 0.5cm, 4 sheets per set), 90m of 150-mesh nylon mesh (1.2m wide), 90m of 40-mesh nylon mesh (1.2m wide), transparent nylon mesh with 3.0cm mesh openings, 240m of PVC flexible tubing (diameter 2.0cm, wall thickness 0.2cm), one 1×1m sample frame, one measuring tape, one flat-head shovel, 12 pairs of scissors, one rubber mallet, one set of 5mm aperture metal sieves, several pairs of work gloves, and several plastic fixing straps.

[0038] 5. Research Methods ① Use a 1×1m quadrature frame to mark the target area.

[0039] ② After marking the target area, use a shovel to move 5-15cm thick soil from the marked target area into the plastic sheet prepared in advance around the target area. Then, use a rubber hammer to manually break up the removed soil and mix it evenly to obtain the soil body.

[0040] ③ Pass the uniformly mixed soil through a 5mm mesh metal sieve to remove gravel, plant debris, and potential plant buds. Because the soil of severely degraded alpine meadows has a high moisture content, it is sieved after drying. The sieved, uniform soil is set aside for re-laying the following day.

[0041] ④ Select 150-mesh nylon mesh, cut it to the same size as the bottom of the pit after the soil has been removed from the designated target area, and lay it flat on the bottom of the pit. Then, insert the acrylic sheet along the four sides of the pit bottom, ensuring the sheet is flush against the four walls. The sheet should be 15cm below the ground and 15cm above the ground. Figure 1 A).

[0042] ⑤ The prepared soil was evenly spread into the pit, with thicknesses set at 4.0 cm, 6.0 cm, 8.0 cm, 10.0 cm, 12.0 cm, and 14.0 cm. For each thickness treatment, five target areas were set as a replicate (n=5 per group), forming a total of six experimental groups. The spread soil was then gently compacted; compaction was performed using a shovel, relying on the weight of the shovel to further flatten the soil. Subsequently, a 40-mesh nylon mesh was used to cover the square frame formed by the acrylic sheet and secured with tape. Figure 1 B).

[0043] ⑥ After completing step ⑤, set up two fixed "bows" at the four corners, 20cm away from the square experimental area, to form a support structure. The top of the bows should be 100cm above the ground. The support structure formed by the "bows" is made of PVC flexible tubing with a diameter of 1.0~2.0cm and a wall thickness of 0.1~0.3cm. Figure 2 A).

[0044] ⑦ After completing step ⑥, cover the cross-shaped support structure at the top of the bow with a transparent nylon mesh with a mesh size of 3.0 cm to block large foreign objects brought by strong winds from affecting the experimental device. Figure 2 B).

[0045] ⑧ 48 hours after the soil backfilling was completed, the moisture content of the backfilled soil was measured using a handheld soil moisture meter. If the difference between the soil moisture content of each experimental group and the surrounding original soil moisture content was within 15% (alpine grassland) or within 10% (alpine meadow), no additional water replenishment was required.

[0046] ⑨ Record seedling emergence at 60, 80, 100 and 120 days after the start of the experiment.

[0047] 6. Experimental Results 6.1 Comparison of species numbers in the soil seed bank under different soil backfill thicknesses Soil backfill thickness significantly affected the species abundance in the soil seed bank of both degraded alpine steppe and alpine meadow. Species abundance initially increased and then decreased with increasing backfill thickness. In degraded alpine steppe, the optimal backfill thickness was 10.0–12.0 cm; in degraded alpine meadow, it was 8.0–12.0 cm. Considering both degraded habitats, a backfill thickness of 10.0 cm resulted in the richest species abundance and can be considered the optimal backfill thickness. Figure 3 ).

[0048] 6.2 Statistical Analysis Results of Species Information under Optimal Soil Spread Thickness In an environment with a soil backfill thickness of 10.0 cm, the number of species in the soil seed bank of severely degraded alpine steppe and alpine meadow gradually increased with the extension of backfill time, and the number of species in the soil seed bank of severely degraded alpine steppe remained unchanged after 80 days of in-situ experiment. In contrast, the number of species in the soil seed bank of severely degraded alpine meadow tended to stabilize after 100 days of in-situ experiment. Figure 4 ).

[0049] In 1×1m 2 Within the target area, the number of species in the in-situ experiment of the seed bank of severely degraded alpine meadow soil was significantly higher than that of severely degraded alpine steppe. The average number of species in the alpine meadow soil seed bank was 9, while the average number of species in the alpine steppe soil seed bank was 4. Figure 5 The number of functional groups of species in the seed bank of severely degraded alpine meadow soils tended to be higher than that in severely degraded alpine steppes, but there was no statistically significant difference between the two. Figure 6 ).

[0050] Table 1 shows the total list of species, total number of species, number of functional groups, number of families, and number of genera that appeared after in situ culture of soil seed banks in severely degraded alpine grasslands and severely degraded alpine meadows.

[0051] Table 1. Summary of species, families, and genera from the seed bank of soils from severely degraded alpine grasslands and meadows. As shown in Table 1, the seed bank of soil from severely degraded alpine steppe is relatively simple, containing only 6 species belonging to 5 families and 5 genera. Except for *Poa annua*, the remaining species are common weeds found in natural alpine steppes. The seed bank of soil from severely degraded alpine meadow is much richer, containing 13 species belonging to 10 families and 11 genera. Except for *Leymus chinensis*, the remaining species are common weeds found in natural alpine meadows. The soil seed bank data maintains ecological authenticity.

[0052] In summary, this invention, during in-situ soil seed bank research, effectively blocks the invasion of potential wandering plant roots and rhizomes and the mixing of exogenous seeds by selecting specific target areas, constructing specific frameworks and supports, and laying nylon nets of different specifications at different parts of the device, while ensuring the normal exchange of water, heat, gases, nutrients, and other substances and energy in the soil. This method balances operational controllability and ecological authenticity, thus ensuring that the obtained soil seed bank data possesses scientific validity, reliability, and practical reference value.

Claims

1. A method for in-situ construction of a seed bank of degraded alpine grassland soil, characterized in that: Includes the following steps: 1) In degraded alpine grasslands and their surrounding areas, avoiding rodent burrows and vegetation zones, select areas with a slope of ≤20° as the target area for constructing soil seed banks; 2) In the target area determined in step 1), mark the position with a quadrat frame, dig a pit to collect soil, break the soil, and sieve it to remove impurities to obtain the soil body; 3) At the bottom of the pit obtained in step 2), lay a layer of nylon netting with the same area as the pit bottom. Then, insert acrylic sheets vertically into the pit bottom, close to the four walls of the pit, to form a square frame. Finally, backfill the pit with the soil obtained in step 2) and spread it flat. 4) Cover the square frame obtained in step 3) with nylon netting and fix it to the upper edge of the frame with tape. Then, build an "arch"-shaped support 15-25cm away from the edge of the frame so that the support covers the entire frame area. 5) Cover and fix the nylon netting onto the "bow" shaped support obtained in step 4). After standing, adjust the humidity of the backfilled soil so that the difference between its moisture content and the humidity of the surrounding original degraded alpine grassland is controlled within 15%. 6) Continuously observe the backfilled soil for which moisture content has been regulated in step 5), and record the number and composition of species regularly until both no longer change. The number and composition of species at this point are the data of the degraded alpine grassland soil seed bank.

2. The in-situ construction method according to claim 1, characterized in that: Step 1) The degraded alpine grasslands include degraded alpine steppes and degraded alpine meadows.

3. The in-situ construction method according to claim 2, characterized in that: Within a 100m radius of the degraded alpine grassland, the vegetation area to be avoided is the reed mound; the slope of the selected area should be ≤20°.

4. The in-situ construction method according to claim 2, characterized in that: Within a degraded alpine meadow and its surrounding area of ​​50-100m, the vegetation areas to be avoided are patchy grass carpet areas, and areas within 20m of river valleys should also be avoided; the slope of the selected area should be ≤10-15°.

5. The in-situ construction method according to claim 1, characterized in that: Step 2) The dimensions of the sample frame include 1×1 m, and the soil is beaten with a rubber hammer until it is completely broken.

6. The in-situ construction method according to claim 1, characterized in that: Step 3) The specifications of the pit include a length of 1m, a width of 1m, and a depth of 10~15cm; the specifications of the nylon mesh are 150~200 mesh.

7. The in-situ construction method according to claim 1, characterized in that: Step 3) The acrylic sheet has the following specifications: 100cm in length, 25-30cm in height, and 0.2-0.5cm in thickness; it is inserted into the acrylic sheet so that it is buried 15cm underground and protrudes 10-15cm above the ground.

8. The in-situ construction method according to claim 1, characterized in that: The thickness of the backfill soil in step 3) is 10.0~12.0cm for degraded alpine grassland and 8.0cm~12.0cm for degraded alpine meadow.

9. The in-situ construction method according to claim 1, characterized in that: Step 4) The nylon mesh used in this step has a mesh size of 20-40. The "bow" support uses PVC flexible tubing with a diameter of 1.0~2.0cm and a wall thickness of 0.1~0.3cm, and is erected 20cm away from the edge of the square frame; the top of the bow is 100~150cm from the ground.

10. The in-situ construction method according to claim 1, characterized in that: Step 5) The nylon netting is a transparent nylon netting with a mesh size of 1.0~5.0 cm; let it stand for 48 hours; the difference between the moisture content of the backfill soil and the humidity of the surrounding original degraded alpine meadow is controlled within 15%; the difference between the moisture content of the backfill soil and the humidity of the surrounding original degraded alpine meadow is controlled within 10%.

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