A method for repairing a moderately degraded alpine meadow

Abstract

The present application belongs to the technical field of ecological restoration, and particularly relates to a method for restoring moderately degraded alpine meadow. The method comprises the following steps: step 1, determining the type of the alpine meadow to be restored; and step 2, planting a specific combination of Poaceae species according to the type of the alpine meadow to be restored. When the type of the alpine meadow to be restored is Kobresia pygmaea type, the combination of Poaceae species is Poa crymophila and Poa pratensis. When the type of the alpine meadow to be restored is Carex atrata type, the combination of Poaceae species is Poa compressa and Elymus nutans. When the type of the alpine meadow to be restored is Elymus nutans type, the combination of Poaceae species is Elymus nutans and Festuca sinensis. The present application can effectively promote the restoration of moderately degraded alpine meadow, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of ecological restoration technology, specifically relating to a method for restoring moderately degraded alpine grassland. Background Technology

[0002] The Qinghai-Tibet Plateau is the world's highest (average elevation > 4000m) and largest plateau in terms of area (2572.4 × 10⁻⁶ m). 3 km 2 Alpine grasslands are the dominant vegetation type on the Qinghai-Tibet Plateau, covering 70% of its total area. They play a vital role in maintaining pastoral development, protecting biodiversity, mitigating global climate change, and conserving water resources. The alpine grasslands of the Qinghai-Tibet Plateau are one of the world's most renowned grazing ecosystems. However, due to climate change and human activities, one-third of these grasslands have degraded. Therefore, the restoration of these degraded alpine grasslands has attracted widespread attention. Degraded alpine grasslands on the Qinghai-Tibet Plateau are classified into four levels: slightly degraded, moderately degraded, severely degraded, and extremely degraded. Slightly degraded grasslands can be restored through fencing, while severely and extremely degraded grasslands are mostly restored through artificial grassland construction. Moderately degraded grasslands are considered to be recoverable through fencing, rotational grazing, and reseeding.

[0003] According to the "Research on the Degradation and Restoration of Natural Grasslands in Qinghai Province," the total area of ​​moderately degraded grassland in Qinghai Province is 802.36 × 10⁻⁶. 4 hm 2 This accounts for 19.14% of the province's usable grassland area and 25.63% of the province's total degraded grassland area. Quantitative indicators for moderately degraded alpine grasslands include: total vegetation cover of 41%–70%, 8–14 grassland plant species, a high-quality forage yield of 30%–50%, and a proportion of poisonous, harmful, and non-vegetarian grasses of 33%–67%. The diversity index of moderately degraded grasslands is reduced, the growth of native dominant species is declining, and they appear sparse and short in the grassland community structure. In terms of total biomass, the yield of miscellaneous grasses, non-vegetarian grasses, and poisonous grasses increases, while the yield of high-quality forage grasses such as legumes, sedges, and grasses decreases significantly. Furthermore, the soil in moderately degraded grasslands is dry, soil nutrients are declining, there is freeze-thaw erosion on the surface, and there are freeze-thaw erosion gullies and a small amount of bare land.

[0004] Currently, restoration measures for moderately degraded alpine grasslands mainly include enclosure, rotational grazing, and reseeding. However, there are some drawbacks. For example, enclosure protects degraded grasslands, preventing their use and giving pastures a chance to rest, mature, fall, and reproduce. However, restoration takes a long time and is difficult to achieve the desired ecological restoration goals. Rotational grazing requires dividing the grassland into zones and fencing it, followed by regular grazing. Zoned rotational grazing requires meticulous management, but herders' management is often extensive, making it difficult to meet the requirements. Reseeding involves sowing high-quality pastures such as crested wheatgrass, old awned wheatgrass, and Chinese fescue in degraded grasslands without damaging or minimizing the original vegetation, thereby restoring the degraded grasslands.

[0005] However, existing research on reseeding moderately degraded grasslands is still insufficient, especially regarding fertilizer combinations, grass seed combinations, and technical measures, which affects the restoration effect of reseeding moderately degraded alpine grasslands. Summary of the Invention

[0006] To address the problems of existing technologies, this invention provides a method for restoring moderately degraded alpine grasslands. The aim is to improve the effectiveness of reseeding and restoring moderately degraded alpine grasslands by optimizing factors such as grass species matching.

[0007] A method for restoring moderately degraded alpine grassland includes the following steps:

[0008] Step 1: Identify the type of alpine grassland to be restored;

[0009] Step 2: Plant the appropriate combination of grass species according to the type of alpine grassland to be restored;

[0010] When the type of alpine grassland to be restored is Kobresia alpineensis, the combination of grass species is Kentucky bluegrass and Kentucky bluegrass.

[0011] When the type of alpine grassland to be restored is *Caragana sinica*, the combination of grass species is *Poa flattened-stem* and *Eragrostis pilosa*.

[0012] When the type of alpine grassland to be restored is *Leymus chinensis*, the combination of grass species is *Leymus chinensis* and *Festuca sinensis*.

[0013] Preferably, the moderately degraded alpine grassland has a community coverage of 41%-70%, a high-quality forage grass ratio of 30%-50%, and is an alpine grassland at an altitude greater than 3000m.

[0014] Preferably, in step 2, the seeding amount of the grass species combination is:

[0015] When the type of alpine grassland to be restored is Kobresia alpineensis, the sowing rate of the grass species combination is 10-15 kg / ha;

[0016] When the type of alpine grassland to be restored is *Caragana sinica*, the sowing rate of the grass species combination is 10–15 kg / ha;

[0017] When the alpine grassland to be restored is of the type of *Leymus chinensis*, the sowing rate of the grass species combination is 5–10 kg / ha.

[0018] Preferably, in step 2, the proportion of the grass species combination is:

[0019] When the type of alpine grassland to be restored is Kobresia alpineensis, the seed mass ratio of Kentucky bluegrass to Kentucky bluegrass is 1:(0.5-1.5);

[0020] When the type of alpine grassland to be restored is *Carex brevicornu*, the seed mass ratio of *Poa flattenedis* and *Eragrostis pilosa* is 1:(0.5-1.5).

[0021] When the alpine grassland to be restored is of the type of *Leymus chinensis*, the seed mass ratio of *Leymus chinensis* to *Festuca sinensis* is 1:(0.5-1.5).

[0022] Preferably, step 2, the process of planting a specific combination of grass species, specifically includes the following steps:

[0023] Step 2.1, the first year of greening, clear away dead grass from the ground surface;

[0024] Step 2.2: Soak the seeds of the gramineous species combination in microbial fertilizer;

[0025] Step 2.3: After tilling the land, spray the microbial fertilizer used for soaking onto the degraded patches to be repaired and then sow the seeds.

[0026] Step 2.4: Apply a nitrogen-phosphorus mixed fertilizer to the degraded patches to be repaired;

[0027] Step 2.5: Till the land again in a direction perpendicular to the direction of tillage in Step 2.3;

[0028] Step 2.6, press with a ballast;

[0029] Step 2.7: During the growing season, fence off the area and strictly prohibit grazing;

[0030] Step 2.8: Graze the animals appropriately after the soil freezes;

[0031] Step 2.9, during the second year's greening period, apply microbial fertilizer and nitrogen-phosphorus mixed fertilizer to the degraded patches to be repaired again;

[0032] Step 2.10: During the growing season, fence off the area and strictly prohibit grazing;

[0033] Step 2.11: Graze the animals appropriately after the soil freezes;

[0034] Step 2.12, repeat steps 2.9 to 2.11 in the third year.

[0035] Preferably, the annual usage of the microbial fertilizer is 10-15 kg / ha, and the effective live bacteria count of the microbial fertilizer stock solution is ≥10. 8 CFU / g, used after dilution, with a dilution ratio of 10 to 20 times.

[0036] Preferably, the microbial fertilizer is a Bacillus-like microbial agent.

[0037] Preferably, the mass ratio of nitrogen fertilizer to phosphorus fertilizer in the nitrogen-phosphorus compound fertilizer is (9-10):1, calculated as N:P mass.

[0038] And / or, the nitrogen fertilizer is in the form of urea, and the phosphorus fertilizer is in the form of superphosphate.

[0039] Preferably, the annual usage of the nitrogen-phosphorus compound fertilizer is: 45-90 kg / ha of nitrogen fertilizer (N by mass) and 5-10 kg / ha of phosphorus fertilizer (P by mass).

[0040] Preferably, when the type of alpine grassland to be restored is alpine Kobresia, the annual usage of the nitrogen-phosphorus compound fertilizer is: 45 kg / ha of nitrogen fertilizer (N mass) and 5 kg / ha of phosphorus fertilizer (P mass).

[0041] When the type of alpine grassland to be restored is *Caragana sinica*, the annual application rate of the nitrogen-phosphorus compound fertilizer is: 75 kg / ha of nitrogen fertilizer (N by mass) and 7.5 kg / ha of phosphorus fertilizer (P by mass).

[0042] When the type of alpine grassland to be restored is *Leymus chinensis*, the annual application rate of the nitrogen-phosphorus compound fertilizer is: 90 kg / ha of nitrogen fertilizer (N by mass) and 10 kg / ha of phosphorus fertilizer (P by mass).

[0043] This invention provides specific reseeding plant combinations for different types of alpine grasslands. These plant combinations ensure both the adaptability (suitability for growth) of species in their respective habitats and the consistency of the integrated landscape (preventing any negative impact on the landscape effect after restoration). Existing technologies lack attention to landscape consistency in grassland restoration, while this invention integrates landscape consistency into the restoration of degraded grasslands, further expanding and elevating the Natural Business Base (NBS) theory, enriching its connotation, and possessing unprecedented advantages in theoretical innovation. Through comparison of native controls and experimental groups of different grassland types, embodiments of this invention reveal that, under different grassland types, the experimental group not only increased biomass but also improved the stability of primary productivity in the ecosystem. Therefore, the reseeding plant combinations of this invention can rapidly improve the restoration of moderately degraded alpine grasslands.

[0044] Simultaneously, the optimized scheme, supplemented by fertilizer combination optimization, fencing and enclosure, grazing ban during the growing season, grazing during the freezing season, continuous topdressing in the second and third years, and management, effectively promotes the restoration of moderately degraded alpine grasslands. Within 3-4 years, they can be made reusable.

[0045] Therefore, this invention has great application prospects in the restoration of moderately degraded alpine grasslands.

[0046] 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.

[0047] 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

[0048] Figure 1 Photographs of experimental plots for fertilizer combinations in moderately degraded alpine grasslands;

[0049] Figure 2 Photographs of experimental plots for the restoration of moderately degraded alpine Kobresia-type alpine grassland;

[0050] Figure 3 The effect of the restoration treatment in Example 1 on the plant community structure of moderately degraded alpine Kobresia type alpine grassland;

[0051] Figure 4 The impact of restoration treatment in Example 1 on the diversity of moderately degraded alpine Kobresia-type alpine grassland;

[0052] Figure 5The effect of the restoration treatment in Example 1 on the aboveground biomass of moderately degraded alpine Kobresia type alpine grassland;

[0053] Figure 6 The effect of the restoration combination treatment in Example 1 on the stability of net primary productivity of moderately degraded alpine Kobresia type alpine grassland;

[0054] Figure 7 This is a comparison of plant growth before and after restoration of moderately degraded black-brown sedge-type alpine grassland in Example 2;

[0055] Figure 8 The effect of the restoration treatment in Example 2 on the plant community structure of moderately degraded *Caragana nigra* type alpine grassland;

[0056] Figure 9 The impact of restoration treatment in Example 2 on the diversity of moderately degraded *Caragana nigra* type alpine grassland;

[0057] Figure 10 The effect of the remediation treatment in Example 2 on the aboveground biomass of moderately degraded *Caragana nigra* type alpine grassland;

[0058] Figure 11 The effect of the remediation treatment in Example 2 on the stability of net primary productivity of moderately degraded *Caragana korshinskii* type alpine grassland;

[0059] Figure 12 Photographs of experimental plots for fertilizer combinations in moderately degraded drooping elytra type alpine grassland;

[0060] Figure 13 The effect of the restoration treatment in Example 3 on the plant community structure of moderately degraded Leymus chinensis type alpine grassland;

[0061] Figure 14 The impact of the restoration treatment in Example 3 on the diversity of moderately degraded Leymus chinensis type alpine grassland;

[0062] Figure 15 The effect of the restoration treatment in Example 3 on the aboveground biomass of moderately degraded Leymus chinensis type alpine grassland;

[0063] Figure 16 The effect of the restoration treatment in Example 3 on the stability of net primary productivity of moderately degraded Leymus chinensis type alpine grassland. Detailed Implementation

[0064] The following embodiments and experimental examples were specifically implemented in Maqin County, Sanjiangyuan Region, with the experimental plots as follows: Figure 1 As shown.

[0065] Example 1: Restoration Method for Moderately Degraded Alpine Grasslands of the Kobresia Type

[0066] When the moderately degraded alpine grassland is of the Kobresia type, the grassland cover is approximately 55-70%, with small bare patches, the average bare patch area being 0.15-0.45 m². 2 A small number of low-growing weeds, such as Lagotis brachystachya, Phlomoides rotata, and Knorringia sibirica, remain in the bare patches, and the plant cover inside the bare patches is less than 5%.

[0067] The restoration methods for moderately degraded alpine grasslands of the Kobresia type are as follows:

[0068] 1) During the greening period of alpine grasslands, clear away dead grass from the ground surface;

[0069] 2) Weigh out the forage seeds according to the sowing amount and ratio of grass species, mix them, and obtain mixed seeds;

[0070] 3) Weigh out the micronutrients according to their type and proportion; the micronutrient used in this example is Bacillus subtilis;

[0071] 4) Soak the seeds described in 2) in the micro-fertilizer described in 3) for 6 hours, then remove them, drain the water, and collect the excess bacterial solution;

[0072] 5) Weigh out the nitrogen and phosphorus fertilizers according to the above-mentioned types and proportions, mix them, and obtain a mixed nitrogen and phosphorus fertilizer;

[0073] 6) Use a disc harrow to sequentially break up the turf. When the degraded patches are large, a rotary tiller can be used to sequentially till the turf to a depth of more than 2 cm.

[0074] 7) Spray the micro-fertilizer described in step 3) evenly on the recovery area, and sow the seeds described in step 4) evenly on the recovery area;

[0075] 8) Use a disc rake to sequentially break up the turf in a direction perpendicular to step 6). When the degraded patches have a large exposed area, a rotary tiller can be used for sequential rotary tilling.

[0076] 9) Evenly spread the nitrogen and phosphorus mixed fertilizer obtained in step 5) over the recovery area;

[0077] 10) Press the restored area with a presser;

[0078] 11) After step 10) is completed, strict fencing and grazing are required until the growing season;

[0079] 12) Grazing should be carried out appropriately after the soil freezes in the same year;

[0080] 13) During the second year's greening period, prepare fertilizer according to steps 3) and 5);

[0081] 14) Spray the micro-fertilizer obtained in step 13) evenly onto the original restored area;

[0082] 15) Evenly spread the nitrogen and phosphorus fertilizers obtained in step 13) over the original restored area;

[0083] 16) During the second growing season, strict fencing and grazing are required.

[0084] 17) Grazing should be moderate after the soil freezes in the second year;

[0085] 18) Repeat steps 13), 14), 15), 16), and 17 in the third year.

[0086] The selection and parameters of seeds and fertilizers used in the three experimental groups are as follows:

[0087] Fertilizer treatment 1:

[0088] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0089] Nitrogen and phosphorus fertilizer application rate: 45 kg N / ha, 5 kg P / ha;

[0090] Nitrogen-phosphorus fertilizer ratio: N:P = 9:1;

[0091] Poaceae species assemblage: Kentucky bluegrass and Kentucky bluegrass;

[0092] Seed mass ratio of species: 1:1;

[0093] Sowing rate: 12.5 kg / ha;

[0094] Seed quality: 100% purity, germination rate >95%;

[0095] Sowing depth: 2-3 cm;

[0096] Micronutrient fertilizer: 10 kg / ha;

[0097] Micronutrient solution dilution ratio: 20 times.

[0098] Fertilizer treatment 2:

[0099] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0100] Nitrogen and phosphorus fertilizer application rate: 75 kg N / ha, 7.5 kg P / ha;

[0101] Nitrogen-phosphorus fertilizer ratio: N:P = 10:1;

[0102] Poaceae species assemblage: Kentucky bluegrass and Kentucky bluegrass;

[0103] Seed mass ratio of species: 1:1;

[0104] Sowing rate: 12.5 kg / ha;

[0105] Seed quality: 100% purity, germination rate >95%;

[0106] Sowing depth: 2-3 cm;

[0107] Micronutrient fertilizer: 10 kg / ha;

[0108] Micronutrient solution dilution ratio: 20 times.

[0109] Fertilizer treatment 3:

[0110] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0111] Nitrogen and phosphorus fertilizer application rate: 90 kg N / ha, 10 kg P / ha;

[0112] Nitrogen-phosphorus fertilizer ratio: N:P = 9:1;

[0113] Poaceae species assemblage: Kentucky bluegrass and Kentucky bluegrass;

[0114] Seed mass ratio of species: 1:1;

[0115] Sowing rate: 12.5 kg / ha;

[0116] Seed quality: 100% purity, germination rate >95%;

[0117] Sowing depth: 2-3 cm;

[0118] Micronutrient fertilizer: 10 kg / ha;

[0119] Micronutrient solution dilution ratio: 20 times.

[0120] Two years after the experimental treatment, the results of the plant community structure of the moderately degraded "Kobresia type" alpine grassland showed that after restoration according to the method of this embodiment, the average coverage of the plant community of the moderately degraded "Kobresia type" alpine grassland reached 85%, which was significantly higher than that of the control treatment (P<0.05). Moreover, there was no significant difference in community coverage among different fertilization treatments compared with the control. Figure 3 A). The height of the restored community was also significantly higher than that of the control treatment (P<0.05). Figure 3 B), and compared with the control, there was no significant difference in the average height of the community among the different fertilization treatments. Figure 3B). The plant community diversity results showed that the plant community diversity indices of the moderately degraded "Kobresia type" alpine grassland after restoration, including species richness, Shannon-Wynn index, Simpson index, and Pielou evenness index, did not change significantly compared with the control treatment (P>0.05). This means that the selected fertilization treatments for the moderately degraded "Kobresia type" alpine grassland did not have a serious negative effect on plant diversity. Figure 4 The long-term evolutionary adaptation of Kobresia alpine to the cold environment has led to a significant increase in its plant characteristics, including height and canopy, but it has not had a disruptive impact on the light exposure of the lower-layer species. Therefore, the plant community diversity did not change significantly after fertilization treatment. Aboveground biomass results showed that the aboveground biomass of moderately degraded Kobresia alpine grassland after restoration was significantly higher than that of the control treatment, with an increase of more than 20% (P<0.05), and there was no significant difference between different fertilization treatments. Figure 5 Net primary productivity stability is the most important indicator for measuring the primary productivity function of an ecosystem, and it is also one of the main purposes of adding microbial fertilizer in this invention. By combining pre-experiment biomass data with biomass data from a total of three years, the stability of net primary productivity of moderately degraded "Kobresia type" alpine grassland plants under different experimental treatments was calculated. The results showed that the stability of fertilization treatment 1 was significantly higher than that of the control, and it showed a decreasing trend with increasing fertilization gradient. Figure 6 Based on experimental data from a moderately degraded "alpine Kobresia type" alpine grassland experiment, fertilization treatment 1 is recommended as an effective restoration method for this type of degraded grassland.

[0121] Example 2: Restoration Method for Moderately Degraded Alpine Grasslands of the Black-brown Caragana Type

[0122] When the moderately degraded alpine grassland is of the *Caragana sinica* type, the grassland cover is approximately 50–60%, and the bare patch area is approximately 0.10–0.25 m². 2 The bare spots are relatively evenly distributed and mostly located in areas with severe water erosion. Small amounts of species from the genera *Potentilla* and *Viola* are commonly found within the bare spots.

[0123] The restoration method for moderately degraded alpine grassland of the *Caragana nigra* type follows the same steps as in Example 1, except for the selection and parameters of the seeds and fertilizers used for sowing.

[0124] The fertilization parameters for the three experimental groups are as follows:

[0125] Fertilizer treatment 1:

[0126] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0127] Nitrogen and phosphorus fertilizer application rate: 45 kg N / ha, 5 kg P / ha;

[0128] Nitrogen-phosphorus fertilizer ratio: N:P = 9:1;

[0129] Poaceae species assemblage: Kentucky bluegrass and small-flowered alkali grass;

[0130] Seed mass ratio of species: 1:1;

[0131] Seeding rate: 10 kg / ha;

[0132] Seed quality: 100% purity, germination rate >95%;

[0133] Sowing depth: 2-3 cm;

[0134] Micronutrient fertilizer: 12.5 kg / ha;

[0135] Micronutrient solution dilution ratio: 10 times.

[0136] Fertilizer treatment 2:

[0137] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0138] Nitrogen and phosphorus fertilizer application rate: 75 kg N / ha, 7.5 kg P / ha;

[0139] Nitrogen-phosphorus fertilizer ratio: N:P = 10:1;

[0140] Poaceae species assemblage: Kentucky bluegrass and small-flowered alkali grass;

[0141] Seed mass ratio of species: 1:1;

[0142] Seeding rate: 10 kg / ha;

[0143] Seed quality: 100% purity, germination rate >95%;

[0144] Sowing depth: 2-3 cm;

[0145] Micronutrient fertilizer: 12.5 kg / ha;

[0146] Micronutrient solution dilution ratio: 10 times.

[0147] Fertilizer treatment 3:

[0148] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0149] Nitrogen and phosphorus fertilizer application rate: 90 kg N / ha, 10 kg P / ha;

[0150] Nitrogen-phosphorus fertilizer ratio: N:P = 9:1;

[0151] Poaceae species assemblage: Kentucky bluegrass and small-flowered alkali grass;

[0152] Seed mass ratio of species: 1:1;

[0153] Seeding rate: 10 kg / ha;

[0154] Seed quality: 100% purity, germination rate >95%;

[0155] Sowing depth: 2-3 cm;

[0156] Micronutrient fertilizer: 12.5 kg / ha;

[0157] Micronutrient solution dilution ratio: 10 times.

[0158] Two years after restoration, the plant community structure of the moderately degraded "Black Brown Caragana type" alpine grassland showed that the average cover of the restored plant community was close to 90%, significantly higher than the control (P<0.05), an increase of approximately 1.5 times. The average community cover showed an increasing trend with increasing fertilization gradient, reaching its highest value at fertilization treatments 2 and 3, with no significant difference between treatments 2 and 3. Figure 8 A). The height of the restored community was also significantly higher than that of the control treatment (P<0.05). Figure 7 ), and the trend of change is completely consistent with the community coverage. Figure 8 B). Plant community diversity results showed that the species richness index of the moderately degraded "Black Brown Caragana type" alpine grassland plant community after restoration did not change significantly compared with the control treatment (P>0.05). Figure 9 A). The Shannon-Wynar index, Simpson index, and Pielou evenness index showed significant differences compared to the control (P<0.05). The most significant feature was that the Shannon-Wynar index, Simpson index, and Pielou evenness index were significantly reduced under high fertilization levels (fertilization treatment 3). Figure 9 B, C, D). This result implies that fertilization treatment 3 in moderately degraded "black-brown sedge-type" alpine grasslands would have a serious negative effect on plant diversity. Figure 9This result is mainly due to the alteration of species dominance in the community caused by high fertilization levels (fertilization treatment 3). While fertilization treatments 1 and 2 also altered the community structure, this variable was insufficient to have a disruptive impact on species such as *Carex spp.* and *Lysimachia nummularia* distributed in the understory of moderately degraded "Carex spp. type" alpine grassland communities. This is one of the important reasons why plant community diversity did not show a significant negative response pattern to fertilization treatments 1 and 2. Aboveground biomass results showed that the aboveground biomass of the moderately degraded "Carex spp. type" alpine grassland after remediation was significantly higher than the control treatment (P<0.05), and there was no significant difference between fertilization treatments 1 and 2. The biomass of fertilization treatment 3 showed a decreasing trend. This strong response of aboveground biomass to fertilization treatment is related to the plant plasticity of *Carex spp.* and its tolerance to high levels of fertilization. Figure 10 By combining pre-experiment biomass data with biomass data from a total of 3 years, the stability of net primary productivity of moderately degraded "Black Brown Caragana type" alpine grassland under different experimental treatments was calculated. The results showed that the stability of fertilization treatment 2 was significantly higher than that of the control and other fertilization treatments. Figure 11 Based on the experimental data of moderately degraded "black-brown sedge type" alpine grassland, fertilization treatment 2 is recommended as an effective restoration method for this type of degraded grassland.

[0159] Example 3: Restoration Method for Moderately Degraded Alpine Grassland of the Leymus chinensis Type

[0160] When the moderately degraded alpine grassland is of the *Leymus chinensis* type, the grassland cover is approximately 40–50%, and the bare patch area is approximately 0.30–0.55 m². 2 The soil nutrient conditions inside the bare spots are poor.

[0161] The restoration method for moderately degraded alpine grassland of the *Leymus chinensis* type follows the same steps as in Example 1, except for the selection and parameters of the seeds and fertilizers used for sowing.

[0162] The fertilization parameters for the three experimental groups are as follows:

[0163] Fertilizer treatment 1:

[0164] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0165] Nitrogen and phosphorus fertilizer application rate: 45 kg N / ha, 5 kg P / ha;

[0166] Nitrogen-phosphorus fertilizer ratio: N:P = 9:1;

[0167] The species assemblage of the Poaceae family consists of flat-stemmed Kentucky bluegrass and small-flowered alkali grass;

[0168] Seed mass ratio of species: 1:1;

[0169] Seeding rate: 5 kg / ha;

[0170] Seed quality: 100% purity, germination rate >95%;

[0171] Sowing depth: 2-3 cm;

[0172] Micronutrient fertilizer: 15 kg / ha;

[0173] Micronutrient solution dilution ratio: 20 times.

[0174] Fertilizer treatment 2:

[0175] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0176] Nitrogen and phosphorus fertilizer application rate: 75 kg N / ha, 7.5 kg P / ha;

[0177] Nitrogen-phosphorus fertilizer ratio: N:P = 10:1;

[0178] The species assemblage of the Poaceae family consists of flat-stemmed Kentucky bluegrass and small-flowered alkali grass;

[0179] Seed mass ratio of species: 1:1;

[0180] Seeding rate: 5 kg / ha;

[0181] Seed quality: 100% purity, germination rate >95%;

[0182] Sowing depth: 2-3 cm;

[0183] Micronutrient fertilizer: 15 kg / ha;

[0184] Micronutrient solution dilution ratio: 20 times.

[0185] Fertilizer treatment 3:

[0186] Forms of nitrogen and phosphorus fertilizers: Nitrogen fertilizer (urea), Phosphorus fertilizer (superphosphate);

[0187] Nitrogen and phosphorus fertilizer application rate: 90 kg N / ha, 10 kg P / ha;

[0188] Nitrogen-phosphorus fertilizer ratio: N:P = 9:1;

[0189] The species assemblage of the Poaceae family consists of flat-stemmed Kentucky bluegrass and small-flowered alkali grass;

[0190] Seed mass ratio of species: 1:1;

[0191] Seeding rate: 5 kg / ha;

[0192] Seed quality: 100% purity, germination rate >95%;

[0193] Sowing depth: 2-3 cm;

[0194] Micronutrient fertilizer: 15 kg / ha;

[0195] Micronutrient solution dilution ratio: 20 times.

[0196] Two years after the fertilizer combination experiment, the plant community structure of the moderately degraded "Leymus chinensis type" alpine grassland showed that the average plant community size of the moderately degraded "Leymus chinensis type" alpine grassland after restoration showed a significant increasing trend with the increase of fertilization gradient (P<0.05), reaching the maximum in fertilization treatment 3, with an increase of about 1.5 times, which was significantly higher than other fertilization treatments. Figure 13 A). The community height after fertilization was also significantly higher than that of the control treatment (P<0.05), with an average height of 45cm, among which the height of *Leymus chinensis* approached 70cm. It showed a very strong positive response to fertilization treatment, reaching the highest level in fertilization treatment 3. Figure 13 B). Plant community diversity results showed that, overall, the plant community diversity indices of moderately degraded "Leymus chinensis type" alpine grassland after restoration, including species richness, Shannon-Wynn index, and Pielou evenness index, all showed a significant decreasing trend compared with the control treatment (P<0.05), indicating that the moderately degraded "Leymus chinensis type" alpine grassland exhibited a significant negative effect under the fertilization treatment. Figure 14 The results indicate that the negative effect of fertilization on the plant community diversity of moderately degraded *Leymus chinensis*-type alpine grasslands is caused by a sharp increase in the dominance of some species. Figure 14 *Leymus chinensis* exhibits a strong response to fertilization treatments. After remediation, its dominance rapidly increases, thus exerting a strong restrictive effect on other species in terms of resources and space. Aboveground biomass results indicate that remediation significantly increased the aboveground biomass of moderately degraded *Leymus chinensis*-type alpine grasslands. Figure 15 Among them, fertilization treatment 3 showed the highest biomass, rapidly improving the productive function of this degraded grassland type. Given the strong response of *Leymus chinensis* to fertilization, it can be inferred that a negative effect of fertilization on the plant community diversity of *Leymus chinensis*-type alpine grassland is unavoidable. By combining pre-experiment biomass data with biomass data from three years prior, the stability of net primary productivity (NPMP) of moderately degraded *Leymus chinensis*-type alpine grassland under different treatments was calculated. The results showed that the stability of NMPMP of this grassland type tended to increase with increasing fertilization levels, but there was no significant difference between different treatments. Figure 16 Based on the experimental data of moderately degraded "black-brown sedge type" alpine grassland, and especially considering the rapid improvement of its production function, fertilization treatment 3 is recommended as an effective restoration method for this type of degraded grassland.

[0197] As can be seen from the above embodiments and experimental examples, the present invention comprehensively and effectively promotes the restoration of moderately degraded alpine grasslands by optimizing the replanting plant combination and further supplementing it with fertilizer combination optimization, fencing and enclosure, grazing ban during the growing season, grazing during the freezing season, continuous topdressing in the second and third years, and management and maintenance, and has a very good application prospect.

Claims

1. A method of rehabilitating a moderately degraded alpine meadow, characterized in that, The method comprises the following steps: Step 1, determining the type of the alpine meadow to be repaired; Step 2, according to the type of the alpine meadow to be repaired, planting a corresponding Poaceae species combination: When the type of the alpine meadow to be repaired is Kobresia pygmaea type, the Poaceae species combination is Poa crymophila and Poa pratensis; When the type of the alpine meadow to be repaired is Carex atrofuscata type, the Poaceae species combination is Poa compressa and Elymus nutans; When the type of the alpine meadow to be repaired is Elymus nutans type, the Poaceae species combination is Elymus nutans and Festuca sinensis; In step 2, the process of planting the specific Poaceae species combination comprises the following steps: Step 2.1, in the first year of the growing season, clearing the surface of dead grass; Step 2.2, soaking the seeds of the Poaceae species combination with microbial fertilizer; Step 2.3, after ploughing, spraying the microbial fertilizer used for soaking on the degraded patch to be repaired and sowing; Step 2.4, applying nitrogen and phosphorus mixed fertilizer to the degraded patch to be repaired; Step 2.5, ploughing again in a direction perpendicular to the ploughing in step 2.3; Step 2.6, compacting with a compactor; Step 2.7, fence enclosure in the growing season, and strictly prohibiting grazing; Step 2.8, after the soil freezes, moderately grazing; Step 2.9, in the second year of the growing season, applying microbial fertilizer and nitrogen and phosphorus mixed fertilizer to the degraded patch to be repaired again; Step 2.10, fence enclosure in the growing season, and strictly prohibiting grazing; Step 2.11, after the soil freezes, moderately grazing; Step 2.12, repeating steps 2.9 to 2.11 in the third year; The microbial fertilizer is used in an amount of 10-15 kg / ha per year, and the effective viable cell number of the microbial fertilizer stock solution is ≥10 8 CFU / g, which is used after dilution with a dilution multiple of 10-20 times. The microbial fertilizer is Bacillus-like microbial agent; The mass ratio of nitrogen fertilizer to phosphorus fertilizer in the nitrogen and phosphorus mixed fertilizer is (9-10):1, the form of the nitrogen fertilizer is urea, and the form of the phosphorus fertilizer is superphosphate.

2. The repair method according to claim 1, characterized in that: The moderately degraded alpine meadow has a community coverage of 41%-70% and a proportion of excellent forage grasses of 30%-50%, and is an alpine meadow with an altitude of more than 3,000 m.

3. The repair method according to claim 1, characterized in that: In step 2, the sowing amount of the Poaceae species combination is: When the type of the alpine meadow to be repaired is Kobresia pygmaea type, the sowing amount of the Poaceae species combination is 10-15 kg / ha; When the type of the alpine meadow to be repaired is Carex atrofuscata type, the sowing amount of the Poaceae species combination is 10-15 kg / ha; When the type of the alpine meadow to be repaired is Elymus nutans type, the sowing amount of the Poaceae species combination is 5-10 kg / ha.

4. The repair method of claim 1, wherein: In step 2, the proportion of the Poaceae species combination is: When the type of the alpine meadow to be repaired is Kobresia pygmaea type, the mass ratio of the seeds of Poa crymophila to Poa pratensis is 1:(0.5-1.5); When the type of the alpine meadow to be repaired is Carex atrofuscata type, the mass ratio of the seeds of Poa compressa to Elymus nutans is 1:(0.5-1.5); When the type of the alpine meadow to be repaired is Elymus nutans type, the mass ratio of the seeds of Elymus nutans to Festuca sinensis is 1:(0.5-1.5).

5. The repair method according to claim 1, characterized in that: The nitrogen and phosphorus mixed fertilizer is used in an amount of 45-90 kg / ha of N and 5-10 kg / ha of P per year.

6. The repair method according to claim 5, characterized in that: When the type of the high-cold grassland to be repaired is Kobresia pygmaea type, the nitrogen and phosphorus mixed fertilizer is used in an amount of 45 kg / ha of N and 5 kg / ha of P per year; When the type of the high-cold grassland to be repaired is Kobresia pygmaea type, the nitrogen and phosphorus mixed fertilizer is used in an amount of 45 kg / ha of N and 5 kg / ha of P per year; When the type of the high-cold grassland to be repaired is Kobresia pygmaea type, the nitrogen and phosphorus mixed fertilizer is used in an amount of 45 kg / ha of N and 5 kg / ha of P per year.

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