AU2020100643A4 - Method for ecologically restoring degraded alpine grassland by resowing - Google Patents

Abstract

The present invention discloses a method for ecologically restoring a degraded alpine grassland by resowing, which includes the steps of enclosing, seed proportioning, seed treatment, sowing, field management and the like. The plots need to be treated after enclosure, and the treatment method is spreading an organic fertilizer first, and then gently raking the grassland with a raking depth of 3-5 cm; seed proportioning is mixing fast-establishment and slow-establishment grass seeds according to a certain proportion to achieve the purpose of improving biodiversity of the grassland; seed treatment is mixing the grass seeds that have been soaked in warm water with a seed-dressing agent to make the seeds have a higher germination rate; sowing is carried out in a manner of seeder dibbling or manual sowing; and in addition to topdressing of fertilizers, field management also requires spraying a herbicide while deploying a poison bait, which is beneficial for ensuring the normal growth of forage. By adopting the method of the present invention, the soil environment of the alpine grassland can be obviously improved, such that the alpine grassland is beneficial for the free growth of forage and can effectively solve the technical problem of difficult restoration of the degraded alpine grassland. Control Resowing cn 200 Control Resowing -0 Control Resowing

Description

METHOD FOR ECOLOGICALLY RESTORING DEGRADED ALPINE GRASSLAND BY RESOWING

TECHNICAL FIELD

The present invention belongs to the technical field of grassland restoration, and particularly relates to a method for ecologically restoring a degraded alpine grassland by resowing.

BACKGROUND

For thousands of years, animal husbandry based on grasslands has been the main economic source of Tibetan farmers and herdsmen, and is also the most important economic pillar for Tibet. It is closely related to the production, life and culture of the Tibetan, plays an important role in the development and prosperity of economy, and has an important strategic position in the national ecological security of China. With the continuous increase of population, an increasing number of livestock, as well as unreasonable utilization and management modes, the alpine grasslands in Tibet are increasingly degraded, the ecological environment becomes worse, and there are less fine forage, more weeds, and low plant height and cover. In addition, there are serious grassland rodent and insect pests. The productivity is increasingly decreased, and sandification and desertification are intensified. The ecological service functions of the grasslands are weakened, and the system coordination is destroyed. All these problems eventually cause the alpine grassland ecosystem to lose the potential of sustainable development. The economic benefit of the animal husbandry is decreasing, which leads to a series of ecological, economic and social problems, directly affecting the ecological security of the Qinghai-Tibet Plateau and the whole country of China.

At present, the total area of degraded grasslands in Tibet reaches 353 million mu, which is increased by 96.03% over the 181 million mu in the data provided by the grassland survey in 1988, showing a trend of accelerated degradation. Resowing of natural grasslands is an effective measure to improve degraded natural grasslands. Resowing is an important way to increase an exogenous seed bank of grassland community. The proportion of fine forage in the grassland community can be increased by adding exogenous fine forage seeds. Under the situation that the natural grasslands in Tibet are degraded generally, improving the degraded grasslands by resowing has more important practical significance. According to the characteristics of alpine grasslands, people have tried some resowing techniques in order to restore vegetation productivity. For example, Wei Xuehong et al. and Zhang Yongchao et al. have studied the resowing techniques for alpine grasslands, but the seeding is single and have not achieved restoration ideally. At present, no relatively mature technology of restoring by resowing has been applied in alpine grasslands. It is urgent to develop a cost-saving method that can increase forage yield of a grassland.

2020100643 28 Apr 2020

SUMMARY

With respect to the prior art, the present invention provides a method for ecologically restoring a degraded alpine grassland by resowing, so as to solve the technical problem that it is difficult to restore the degraded alpine grassland.

In order to achieve the aforementioned objective, the technical solution adopted by the present invention is to provide a method for ecologically restoring a degraded alpine grassland by resowing, which includes the following steps:

(1) enclosing: enclosing the grassland to be restored with 15-20 mesh iron gauzes, then spreading an organic fertilizer according to a dosage of 500-1000 kg/mu, and then gently raking the grassland with a raking depth of 3-5 cm;

(2) seed proportioning: selecting fast-establishment and slow-establishment grass seeds each with a purity greater than 95%, and uniformly mixing them according to a mass ratio of

3- 4:1;

(3) seed treatment: soaking the proportioned seeds in warm water at 25-35°C for 2-3 h, and then uniformly mixing them with a seed-dressing agent according to the mass ratio of 1:1-2, wherein the seed-dressing agent includes the following components in parts by weight:

4- 5 parts of a type C or D kreotoxin, 5-10 parts of indoleacetic acid, 1-3 parts of a pesticide, 3-5 parts of a germicide and 4-5 parts of sandy soil;

(4) sowing: sowing in late May by seeder dibbling or manual sowing at a sowing density of 5-10 kg/mu; after sowing, spreading calcium superphosphate according to a dosage of 20-25 kg/mu, then covering the sowed area with soil by a disc harrow or by raking manually, and then conducting compressing treatment on the sowed area;

(5) field management: after the grass seeds emerge, spreading a nitrogen fertilizer before rainfall at a dosage of 20-25 kg/mu; in July to August spraying a potash fertilizer with a concentration of 0.3-0.5 wt% once every 15-20 days, in total for three consecutive times, and in September spraying a herbicide with a concentration of 0.3-0.5 wt% while deploying poison baits, wherein the herbicide includes the following components in parts by mass: 2-4 parts of 2,4-D butyl ester, 5-8 parts of glyphosate and 3-5 parts of metsulfuron-methyl; and (6) conducting fencing enclosure for 2-3 years.

The present invention proposes a novel resowing scheme for a degraded alpine grassland based on existing resowing technology of degraded grasslands. The scheme sows of a combination of a variety of grass seeds, which not only can increase the biomass of the grassland, but also ensures the continuity and protectiveness of emergence due to the different emergence speeds of grass seeds. Specifically, the scheme includes the following steps.

Firstly, a degraded alpine grassland to be restored is delineated and enclosed with 15-20

2020100643 28 Apr 2020 mesh iron gauzes. The iron gauzes not only can prevent livestocks from entering the grassland, but also can prevent rodents from entering the grassland due to the small aperture of the iron gauzes, thereby reducing the number of rodents to a certain extent and playing a positive role in grassland protection. After the grassland is enclosed, an organic fertilizer is firstly spread and then the grassland is raked such that the organic fertilizer and the soil clods are fully mixed. As the organic fertilizer contains various nutrients and flora, the soil quality can be obviously improved and the soil fertility can be maintained. Conducting grass seed sowing on this basis not only can reduce the dosage of compound fertilizer and reduce the ecological damage to alpine regions, but also can adequately ensure the stable growth of grass seedlings. As compared with the raking depth of less than 2 cm in the prior art, during raking the raking depth is 3-5 cm, which can ensure that the root systems of the grass seeds can grow to a deeper stratum after rooting, the grass plants can better resist alpine weather and strong winds, and thus is of great significance to the restoration of the alpine grassland.

In the present invention, during sowing, a variety of grass seeds are sowed in combination, and the combined seeds include fast-establishment and slow-establishment grass seeds. The combination of the seeds with the two characteristics ensures the continuity of grass seed emergence. That is, there are grass seed emergences in each of different time periods, and seedlings can be sufficiently supplemented even in an environment with severe climate. Moreover, the plants of the grass seeds that emerge first can protect the seedlings of the grass seeds that emerge later, and thus the survival rate of the grass seeds that emerge later is greatly improved. Furthermore, the combined seeds are mixed with a seed-dressing agent before sowing. The seed-dressing agent in the present invention includes the type C or D kreotoxin, indoleacetic acid, the pesticide, the germicide and sandy soil. The kreotoxin can reduce the number of rodents in the grassland. The pesticide and germicide can prevent the seeds from being destroyed by pests or harmful fungi and bacteria before germination, so that the germination rate is fully ensured. The indoleacetic acid can promote the rooting and germination of the grass seeds. The sandy soil can prevent the seeds from being agglomerated, such that the seeds are dispersed more uniformly during sowing, and the subsequent growth potential of plants is more uniform.

According to the present invention, during the field management, the herbicide is sprayed in addition to the potash fertilizer for promoting the growth of leaves. The herbicide in the present invention has strong specificity. That is, the herbicide only acts on weeds with growth advantages in the degraded grassland, such as ajuga lupulina, oxytropis, Lagotis brachystachya, Pedicularis kansuensis and the like, so that the types and quantities of weeds can be reduced, and the growth competitive pressure of the forage can be reduced. Moreover,

2020100643 28 Apr 2020 the poisonous bait is also deployed, which can effectively control the number of rodents and avoid excessive tearing of vegetation.

On the basis of the above technical solution, the present invention can also make the following improvements.

Further, the organic fertilizer is a product of mixed fermentation of sheep manure and withered grass according to a mass ratio of 2-3:1. The withered grass is obtained by drying weeds growing in the degraded grassland in the sun.

According to the present invention, the weeds are harvested and dried in the sun to serve as fermentation raw materials of the organic fertilizer, which not only can facilitate the growth of the resowed forage, but also can facilitate the grassland after the sowing to form communities specific in alpine regions in a short time since the fermented organic fertilizer contains more beneficial flora. Therefore, its grassland restoration effect is better.

Furthermore, the nitrogen fertilizer is also added into the fermentation materials at a dosage accounting for 0.05-0.1% of the total mass, and the fermentation lasts for 5-7 days.

Adding the nitrogen fertilizer into the fermentation materials can adjust the C/N ratio of the organic fertilizer to be maintained at 25-30:1, so as to promote the rapid growth of the forage.

Further, the fast-establishment grass seeds are Elymus nutans and/or Elymus sibiricus, and the slow-establishment grass seed is Poa crymophila Keng.

In the present invention, Elymus nutans and Elymus sibiricus are selected as the fast-establishment grass seeds, and Poa crymophila Keng is selected as the slow-establishment grass seed. This is not only because of their different seedling emergence speeds, but also because Elymus nutans and Elymus sibiricus belong to species of top grasses and have higher plant heights, Poa crymophila Keng belongs to species of bottom grasses and has a shorter plant height, and the two grass seeds cooperate with each other to form a plant community with distinct high and low levels, which ensures that the community structure is reasonable after the vegetation is built, has higher stability, and prevents weeds from invading.

Further, the pesticide is imidacloprid, and the germicide is triadimefon.

Further, the poison bait is prepared by the following steps:

A. soaking a bait in warm water for 1-3 h, taking the bait out and filtering to dryness, and then uniformly mixing it with essence at a mass ratio of 10: 1-2;

B. dissolving the type C kreotoxin in water to prepare a solution of the type C kreotoxin with a final concentration of 0.1%-0.2%; and

C. spreading the bait treated in the step A on gauze, and spraying the solution obtained in

2020100643 28 Apr 2020 the step B onto the bait until the surface of the bait is fully wetted, so as to obtain the poison bait.

Further, the bait is oat, highland barley or wheat; and the essence is oily essence.

Furthermore, the method for deploying the poison bait is as follows: dividing the grassland into small blocks of 4 m*4 m, and using the center of each of the small blocks as deployment points, with 10-20 g of the poison bait being deployed at each deployment point.

By dividing the grassland into small blocks and deploying the poison bait into the small blocks, the deployment density of the poison bait can be controlled, so as to prevent the deployment density from being too low to achieve the purpose of eliminating rodents, or prevent the deployment density from being too high, which otherwise will cause the destruction of the biological chain due to the number of rodents being too low.

The present invention has the following beneficial effects: with respect to the characteristics of thin soil layer, capricious climate, poor soil nutrients, more bare soil in the degraded grassland and the like of the alpine pastoral areas in Tibet, the present technology provides a method for restoring moderately and severely degraded natural grasslands by resowing, which can generate a high density of seedlings on the bare land, ensures that the number of seedlings can be renewed after overwintering and ensures the survival rate of seedlings in drought years while ensuring that sufficient nutrients are supplied to the soil, seed and nutrient conditions are provided for vegetation restoration of the degraded grasslands, and ensuring sufficient vegetation restoration within 2-3 years. The present invention has the following features:

(1) the pre-treatment of forage seeds and high density application of the seeds ensure high seedling production rate and sufficient seedling supplement sources under high altitude conditions and harsh climate environments;

(2) the combination of the fast-establishment forage seeds (Elymus nutans and Elymus sibiricus) and slow-establishment forage seeds (Poa crymophila Keng) ensures the continuity and protectiveness of seedling emergence, and the fast-emerging plants provide protection for the slow-emerging species;

(3) the combination of seeds of top grass species (Elymus nutans and Elymus sibiricus) and bottom grass species (Poa crymophila Keng) ensures that the community structure is reasonable after the vegetation is built, has higher stability, and prevents weeds from invading;

(4) sufficient organic fertilizers provide sufficient carbon and nitrogen sources for soil microorganism metabolism to provide nutrients for plants, and the fertilizer with a higher C:N ratio can improve the utilization rate of the nitrogen fertilizer;

2020100643 28 Apr 2020 (5) the implementation of the compressing technology provides the possibility of preventing the loss of seed materials caused by strong winds and the occurrence of high water evaporation rate under extreme altitude conditions in Tibet; and (6) top dressing before rainfall ensures that water is fully utilized in the critical period of plant growth.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a comparison of plant height between a degraded natural grassland on the third year of resowing and a degraded natural grassland without resowing;

FIG. 2 shows a comparison of aboveground biomass between the degraded natural grassland on the third year of resowing and the degraded natural grassland without resowing; and

FIG. 3 shows a comparison of vegetation community coverage degree between the degraded natural grassland on the third year of resowing and the degraded natural grassland without resowing.

DETAILED DESCRIPTION

The Detailed Description of the present invention will be further described in detail with reference to the embodiments.

The present invention provides a novel solution in terms of the increasingly severe alpine grassland degradation problem, namely, on the basis of referring to the existing resowing technology, a scheme of combining fast-establishment + slow-establishment and species of top grasses + species of bottom grasses is proposed, which can effectively solve the problems of slow grassland restoration and poor restoration effect. The method in the present invention is mainly used for repairing moderately and severely degraded grasslands. When the grasslands are moderately and severely degraded, the proportions of plants of cyperaceae and gramineae in the degraded grasslands are greatly reduced, the proportion of weeds (such as ajuga lupulina, oxytropis, Lagotis brachystachya, Pedicularis kansuensis and the like) is increased, the vegetation coverage degree is reduced, the grassland pests begin to destroy turf, more and more bare land is found, and rodents excessively bite and destroy vegetation, so that the amount of bare land is obviously increased, and the grassland is no longer suitable for grazing.

By analyzing the characteristics of moderately and severely grasslands, the present invention formulates a restoration scheme matched with it. The restoration scheme specifically includes the following steps.

(1) Enclosing: the grassland to be restored is delineated by setting cement piles or wooden piles with a height of about 2 m at an interval of 5-10 m around the grassland, and

2020100643 28 Apr 2020 then the grassland is enclosed with 15-20 mesh iron gauzes. During enclosing, entrance and exit doors for people to enter and exit are set. After enclosing, an organic fertilizer is spread according to a dosage of 500-1000 kg/mu. The organic fertilizer used in the present invention preferentially adopts the product obtained after fermentation of sheep manure and withered grass. The withered grass is obtained after weeds growing in the degraded grassland are dried in the sun. The weeds are mowed before seed setting to prevent the weed seeds from entering the grassland along with the organic fertilizer and growing continually. The fermentation method is: the withered grass is crushed, and uniformly mixed with sheep manure according to a mass ratio of 1: 2-3, the mixed materials are stacked into a cone with a height of about 1 m and a bottom diameter of about 2 m, and fermented freely; after 2-3 days of fermentation, when the temperature reaches about 65°C, turning over and mixing are conducted at this high temperature, free fermentation is conducted continually, and the fermentation can be completed within one week; in order to adjust the C/N ratio of the organic fertilizer, a nitrogen fertilizer can be added into the fermentation materials during fermentation, and the added nitrogen fertilizer accounts for 0.05-0.1% of the total mass of the fermentation materials; and after the organic fertilizer is spread, the grassland is gently raked by a disc harrow or by raking manually at a raking depth of 3-5 cm, such that the organic fertilizer is uniformly mixed with the soil clods.

(2) Seed proportioning: in order to ensure the continuity of emergence and meanwhile increase the community structure of vegetation, a variety of grass seeds need to be selected for seed proportioning in the present invention. The seed proportioning principle is: the rapid and slow emergence speeds of the grass seeds are combined, and the plants have distinct high and short levels. Based on this, the seeds to be sowed should include not only the fast-establishment grass seeds (with a fast emergence speed), but also slow-establishment grass seeds (with a slow emergence speed), and the grass seeds should have different plant heights. After the common forage in alpine regions are investigated, the fast-establishment grass seeds used in the present invention can be selected from varieties such as Elymus nutans or Elymus sibiricus, or can be a mixture of multiple varieties. These varieties not only have fast emergence, but also have higher plant height. The slow-establishment grass seeds can be selected from varieties such as Poa crymophila Keng. The seed proportioning is conducted at an optimal mass ratio of fast-establishment:slow-establishment = 3-4:1, and the purity of each variety of the seeds used in seed proportioning is more than 95%.

(3) Seed treatment: the proportioned seeds are soaked in warm water at 25-35°C for 2-3 h, and during soaking, the seeds shall be submerged by water. After the soaking is completed, the seeds are taken out and filtered to dryness, then mixed with a seed-dressing agent

2020100643 28 Apr 2020 according to a mass ratio of 1:1-2, and stirred uniformly to facilitate the seed-dressing agent to penetrate into the swollen seeds. The seed-dressing agent includes rodent-killing drugs such as a type C or D kreotoxin, and also includes insecticidal and bactericidal drugs such as imidacloprid and triadimefon. At the same time, in order to promote seed germination, the seed-dressing agent also includes auxin, such as indoleacetic acid, etc. Furthermore, in order to prevent seed agglomeration, the seed-dressing agent may also include flour or sandy soil. In the present invention, the optimal composition of the seed-dressing agent is: 4-5 parts of the type C or D kreotoxin, 5-10 parts of indoleacetic acid, 1-3 parts of the pesticide, 3-5 parts of the bactericide and 4-5 parts of the sandy soil.

(4) Sowing: sowing is conducted in late May in a manner of seeder dibbling or manual sowing. When sowing is conducted by a seeder, the plant spacing is 10-15 cm and the sowing density is 5-10 kg/mu. After sowing, calcium superphosphate is spread according to a dosage of 20-25 kg/mu, then the sowed area is covered by a disc harrow or by raking manually, and then a compressing treatment is conducted on the sowed area, so that the seeds sink into the soil for about 3 cm;

(5) field management: after the grass seeds emerge, a nitrogen fertilizer is spread before rainfall at a dosage of 20-25 kg/mu. In July to August, a potash fertilizer with a concentration of 0.3-0.5 wt% is sprayed once every 15-20 days, in total for three consecutive times, and in September a herbicide with a concentration of 0.3-0.5 wt% is sprayed while deploying poison baits. The herbicide includes components with specific actions on weeds such as ajuga lupulina, oxytropis, Lagotis brachystachya, Pedicularis kansuensis and the like, such as 2,4-D butyl ester, glyphosate, metsulfuron-methyl, starane, tribenuron-methyl, etc. In the present invention, the optimal composition of the herbicide is: 2-4 parts of 2,4-D butyl ester, 5-8 parts of glyphosate and 3-5 parts of metsulfuron-methyl. Furthermore, during deployment of the poison bait, the grassland is divided into small blocks of 4 * 4 m, and the center of each of the small blocks is taken as a deployment point, with 10-20 g of the poison bait being deployed at each deployment point. The poison bait is prepared by the following steps:

A. soaking a bait such as oat, highland barley or wheat in warm water at 25-35°C for 1-3 h, taking the bait out and filtering to dryness, and then uniformly mixing it with oily essence at a mass ratio of 10:1-2;

B. dissolving the type C kreotoxin in water to prepare a solution of the type C kreotoxin with a final concentration (mass concentration) of 0.1%-0.2%; and

C. spreading the bait treated in the step A on gauze, and spraying the solution obtained in the step B onto the bait until the surface of the bait is fully wetted, so as to obtain the poison bait.

2020100643 28 Apr 2020 (6) conducting fencing enclosure for 2-3 years.

The method for ecologically restoration of degraded alpine grassland according to the present invention will be described in detail through specific examples hereafter.

In Guo Qing Village of Dangxiong County, 1,000 mu of moderately degraded forbidden grassland with bare soil or sandstone landscape occupying less than 20% of the grassland area and a proportion of weeds (weight ratio) not more than 40% was selected, and was divided into 4 plots with the same area, which were respectively enclosed and labeled at the same time. Restoration by resowing was conducted in the plots Nos. 1-3 according to the methods in Examples 1 to 3 respectively, and no treatment was conducted in the plot No. 4 for serving as a control plot.

Example 1 (1) Enclosing: the grassland to be restored was enclosed with 15-mesh iron gauzes, then an organic fertilizer was spread according to a dosage of 1000 kg/mu, and then the grassland is gently raked with a raking depth of 3 cm.

(2) Seed proportioning: seed proportioning was conducted with the dosage of 5 kg/mu of Elymus nutans, 2.5 kg/mu of Elymus sibiricus and 2.5 kg/mu of Poa crymophila Keng, and all of the seeds were uniformly mixed.

(3) Seed treatment: the proportioned seeds were soaked in warm water at 25°C for 3 h, and then uniformly mixed with a seed-dressing agent according to the mass ratio of 1:1, wherein the seed-dressing agent included the following components in parts by weight: 5 parts of a type C or D kreotoxin, 5 parts of indoleacetic acid, 1 part of a pesticide, 4 parts of a germicide and 4 parts of sandy soil.

(4) Sowing: sowing was conducted in late May in a manner manual sowing and at a sowing density of 10 kg/mu; after sowing, calcium superphosphate was spread according to a dosage of 25 kg/mu, then the sowed area was covered with soil by a disc harrow or by raking manually, and then compressing treatment was conducted on the sowed area.

(5) field management: after the grass seeds emerged, a nitrogen fertilizer was spread before rainfall at a dosage of 25 kg/mu; in July to August a potash fertilizer with a concentration of 0.5 wt% was sprayed once every 20 days, in total for three consecutive times, and in September a herbicide with a concentration of 0.5 wt% was sprayed while deploying poison baits, wherein the herbicide included the following components in parts by mass: 3 parts of 2,4-D butyl ester, 5 parts of glyphosate and 5 parts of metsulfuron-methyl.

(6) Fencing enclosure was conducted for 2-3 years.

Example 2 (1) Enclosing: the grassland to be restored was enclosed with 20-mesh iron gauzes, then ίο

2020100643 28 Apr 2020 an organic fertilizer was spread according to a dosage of 500 kg/mu, and then the grassland is gently raked with a raking depth of 5 cm.

(2) Seed proportioning: seed proportioning was conducted with the dosage of 8 kg/mu of Elymus nutans and 2 kg/mu of Poa crymophila Keng, and all of the seeds were uniformly mixed.

(3) Seed treatment: the proportioned seeds were soaked in warm water at 35 °C for 2 h, and then uniformly mixed with a seed-dressing agent according to the mass ratio of 1:2, wherein the seed-dressing agent included the following components in parts by weight: 4 parts of a type C or D kreotoxin, 8 parts of indoleacetic acid, 2 parts of a pesticide, 3 parts of a germicide and 5 parts of sandy soil.

(4) Sowing: sowing was conducted in late May in a manner manual sowing and at a sowing density of 5 kg/mu; after sowing, calcium superphosphate was spread according to a dosage of 20 kg/mu, then the sowed area was covered with soil by a disc harrow or by raking manually, and then compressing treatment was conducted on the sowed area.

(5) Field management: after the grass seeds emerged, a nitrogen fertilizer was spread before rainfall at a dosage of 20 kg/mu; in July to August a potash fertilizer with a concentration of 0.3 wt% was sprayed once every 15 days, in total for three consecutive times, and in September a herbicide with a concentration of 0.3 wt% was sprayed while deploying poison baits, wherein the herbicide included the following components in parts by mass: 2 parts of 2,4-D butyl ester, 8 parts of glyphosate and 4 parts of metsulfuron-methyl.

(6) Fencing enclosure was conducted for 2-3 years.

Example 3 (1) Enclosing: the grassland to be restored was enclosed with 20-mesh iron gauzes, then an organic fertilizer was spread according to a dosage of 800 kg/mu, and then the grassland is gently raked with a raking depth of 3 cm.

(2) Seed proportioning: seed proportioning was conducted with the dosage of 9 kg/mu of Elymus nutans and 3 kg/mu of Poa crymophila Keng, and all of the seeds were uniformly mixed.

(3) Seed treatment: the proportioned seeds were soaked in warm water at 30°C for 3 h, and then uniformly mixed with a seed-dressing agent according to the mass ratio of 1:1, wherein the seed-dressing agent included the following components in parts by weight: 5 parts of a type C or D kreotoxin, 10 parts of indoleacetic acid, 1 part of a pesticide, 5 parts of a germicide and 5 parts of sandy soil.

(4) Sowing: sowing was conducted in late May in a manner manual sowing and at a sowing density of 8 kg/mu; after sowing, calcium superphosphate was spread according to a

2020100643 28 Apr 2020 dosage of 25 kg/mu, then the sowed area was covered with soil by a disc harrow or by raking manually, and then compressing treatment was conducted on the sowed area.

(5) Field management: after the grass seeds emerged, a nitrogen fertilizer was spread before rainfall at a dosage of 25 kg/mu; in July to August a potash fertilizer with a concentration of 0.5 wt% was sprayed once every 15 days, in total for three consecutive times, and in September a herbicide with a concentration of 0.5 wt% was sprayed while deploying poison baits, wherein the herbicide included the following components in parts by mass: 4 parts of 2,4-D butyl ester, 5 parts of glyphosate and 3 parts of metsulfuron-methyl.

(6) Fencing enclosure was conducted for 2-3 years.

Result analysis

Taking Example 1 as an example, in the third year after sowing, 5 sample transects with an area of 50 m * 100 m were randomly arranged in the sample plot in June, July, August, September and early October. 10 small quadrats each of 50 cm x 50 cm were randomly set up in each sample transect, and the plant species in each quadrat were recorded. Then the community coverage degree and height were respectively measured by employing a quadrat sampling method (consisting of 100 grids each with an area of 5 cm x 5 cm). The aboveground parts of the plants in the quadrats were mowed flush with ground, and weighed. The statistical results of data are shown in Table 1. The results show that the coverage degree of vegetation community in the degraded grassland is increased by 80.64% (July) compared with the control plot, and the aboveground biomass of vegetation in the grassland improved by resowing is increased by 66.00% (August) compared with the control plot.

Table 1 Effects of Resowing on Height, Coverage Degree and Aboveground Biomass of

Degraded Natural Grassland at the 3rd Year of Resowing

Indicators	Treatment	Month of the Year
June	July	August	September	October
Cover Degree (%)	Control	16.33	34.14	48.66	50.24	41
Resowing	21.05	61.67	81.67	76.89	61.53
Improvement%	28.90	80.64	67.84	53.05	50.07
Height (cm)	Control	1.97	3.85	4.16	3.67	2.47
Resowing	2.32	5.16	6.07	5	3.08
Improvement%	17.77	34.03	45.91	36.24	24.70
Biomass (g/m2)	Control	98.24	172.73	201.37	154.02	121

2020100643 28 Apr 2020

	Resowing	137.31	269.54	334.27	228.27	174.43
Improvement%	39.77	56.05	66.00	48.21	44.16

Table 2 lists the changes of soil nutrients in the grassland after 3 years of sowing, from which it can be seen that in a short term (3 years) after resowing, in the degraded grassland, the soil environment has been greatly improved, the content of available nutrients is significantly increased, and is more suitable for the free growth of herbaceous plants.

Table 2 Effects of Resowing on Soil Nutrients in Degraded Natural Grassland

Treatment	Soil Layer (cm)	The third year of resowing
Total organic carbon (g/kg)	Rapidly-available Nitrogen (mg/kg)	Rapidly-available Phosphorus (mg/kg)	Rapidly-available Potassium (mg/kg)
Control	0-10	54.37	122.34	6.07	353.00
Resowing	0-10	63.21	111.36	5.35	317.00
Control	10-20	34.58	100.16	3.51	229.08
Resowing	10-20	42.35	98.12	4.22	242.44

FIG. 1 shows a comparison of plant height between a degraded natural grassland on the third year of resowing and a degraded natural grassland without resowing; FIG. 2 shows a comparison of aboveground biomass between the degraded natural grassland on the third year of resowing and the degraded natural grassland without resowing; and FIG. 3 shows a comparison of vegetation community coverage degree between the degraded natural grassland on the third year of resowing and the degraded natural grassland without resowing. It can be seen that the restoration effect of resowing is very significant.

Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, they should not be construed as limiting the claimed scope of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative labor are still within the claimed scope of this patent.

Claims (5)

What is claimed is:
1. (1) enclosing: enclosing the grassland to be restored with 15-20 mesh iron gauzes, then spreading an organic fertilizer according to a dosage of 500-1000 kg/mu, and then gently raking the grassland with a raking depth of 3-5 cm;

   1. A method for ecologically restoring a degraded alpine grassland by resowing, comprising the following steps:
2. 2. The method for ecologically restoring a degraded alpine grassland by resowing according to claim 1, wherein the organic fertilizer is a product of mixed fermentation of sheep manure and withered grass according to a mass ratio of 2-3:1; and the withered grass is obtained by drying weeds growing in the degraded grassland in the sun, further, wherein the nitrogen fertilizer is also added into the fermentation materials at a dosage accounting for 0.05-0.1% of the total mass, and the fermentation lasts for 5-7 days;

   wherein the fast-establishment grass seeds are Elymus nutans and/or Elymus sibiricus, and the slow-establishment grass seed is Poa crymophila Keng;

   wherein the pesticide is imidacloprid, and the germicide is triadimefon.

   (2) breeding: selecting fast-establishment and slow-establishment grass seeds each with a purity greater than 95%, and uniformly mixing them according to a mass ratio of 3-4:1;
3. 3. The method for ecologically restoring a degraded alpine grassland by resowing

   2020100643 28 Apr 2020 according to claim 1, wherein the poison bait is prepared by the following steps:

   A. soaking a bait in warm water for 1-3 h, taking the bait out and filtering to dryness, and then uniformly mixing it with essence at a mass ratio of 10:1-2;

   B. dissolving the type C kreotoxin in water to prepare a solution of the type C kreotoxin with a final concentration of 0.1%-0.2%; and

   C. spreading the bait treated in the step A on gauze, and spraying the solution obtained in the step B onto the bait until the surface of the bait is fully wetted, so as to obtain the poison bait.

   (3) seed treatment: soaking the proportioned seeds in warm water at 25-35°C for 2-3 h, and then uniformly mixing them with a seed-dressing agent according to the mass ratio of 1:1-2, wherein the seed-dressing agent comprises the following components in parts by weight: 4-5 parts of a type C or D kreotoxin, 5-10 parts of indoleacetic acid, 1-3 parts of a pesticide, 3-5 parts of a germicide and 4-5 parts of sandy soil;
4. 4. The method for ecologically restoring a degraded alpine grassland by resowing according to claim 3, wherein the bait is oat, highland barley or wheat; and the essence is oily essence.

   (4) sowing: sowing in late May by seeder dibbling or manual sowing at a sowing density of 5-10 kg/mu; after sowing, spreading calcium superphosphate according to a dosage of 20-25 kg/mu, then covering the sowed area with soil by a disc harrow or by raking manually, and then conducting compressing treatment on the sowed area;

   (5) field management: after the grass seeds emerge, spreading a nitrogen fertilizer before rainfall at a dosage of 20-25 kg/mu; in July to August spraying a potash fertilizer with a concentration of 0.3-0.5 wt% once every 15-20 days, in total for three consecutive times, and in September spraying a herbicide with a concentration of 0.3-0.5 wt% while deploying poison baits, wherein the herbicide comprises the following components in parts by mass: 2-4 parts of 2,4-D butyl ester, 5-8 parts of glyphosate and 3-5 parts of metsulfuron-methyl; and (6) conducting fencing enclosure for 2-3 years.
5. 5. The method for ecologically restoring a degraded alpine grassland by resowing according to claim 1, wherein the method for deploying the poison bait is as follows: dividing the grassland into small blocks of 4 m*4 m, and using the center of each of the small blocks as deployment points, with 10-20 g of the poison bait being deployed at each deployment point.