Method for guiding light rare earth surface mine degraded plant community recovery through combination of limonium bicolor, mycorrhizal fungi and tolerant wormcast

Abstract

The invention discloses a method for guiding light rare earth surface mine degraded plant community restoration through combination of limonium bicolor, mycorrhizal fungi and tolerant earthworm cast, and the method utilizes a combination mode of limonium bicolor, mycorrhizal fungi and tolerant earthworm cast to guide and construct a plant community-soil fungi-soil ecosystem circulation system. According to the method, the existing plant community of the light rare earth mine is guided to recover by utilizing a combination method of combining dominant plant species with different mycorrhizal fungi and adding tolerance earthworm manure, mycorrhizal fungi and the earthworm manure fertilizer are added in the transplanting process of adult plants, so that the plant survival is promoted, and the stress resistance of light rare earth is enhanced at the same time; plant-mycorrhiza-wormcast fertilizer combinations aiming at different light rare earth elements are screened out, and the whole plant community of the mine is recovered and the content of the light rare earth elements in the soil is reduced through a plant community recovery method.

Description

Technical Field

[0001] The invention belongs to the field of plant and ecological technology, and specifically relates to a method for guiding the restoration of degraded plant communities in light rare earth open-pit mines by using a combination of Limonium bicolor, mycorrhizal fungi and tolerant earthworm castings. Background Art

[0002] Currently, the existing plant communities are affected by conditions such as drought, cold, and light rare earth enrichment. The lack of light rare earth elements in the soil and poor habitat conditions such as low precipitation have led to problems such as lack of microorganisms such as mycorrhizal fungi in the soil, vegetation death, plant community degradation and reverse succession. The survival rate of artificial greening is less than 50%, making it one of the most difficult and complex areas for plant survival and plant community construction.

[0003] The prior art discloses a method for repairing heavy metals using an earthworm microcosm system, application number 20161036510.X. The invention mainly uses earthworms and plant root-mycorrhizae to jointly construct an ecosystem in the soil for the decomposition and absorption of heavy metals.

[0004] The prior art discloses a method for the coordinated restoration of soil heavy metal pollution by plants, mycorrhizae and earthworms, application number 201510335291.4. The invention is to inoculate earthworms during the plant seedling stage to form a plant-mycorrhiza-earthworm system and establish a technology for in-situ fixed-point restoration of soil heavy metals.

[0005] Although the above-mentioned prior art has changed the physical and chemical properties of the soil and reduced the fertility of the soil, it is completely different from the present invention. The present invention utilizes adult plants to increase mycorrhizal agents and earthworm castings fertilizers during the transplanting process to promote plant survival while enhancing their resistance to light rare earths, and screens out combinations of plant-mycorrhizal-earthworm castings fertilizers for different light rare earth elements. The overall plant community of the mine is restored and the light rare earth element content in the soil is reduced by restoring the plant community, thereby guiding the restoration of the plant community from two aspects: the ecological niche and the micro-ecological system, so as to achieve the purpose of preventing the degradation of the existing plant community and guiding the restoration of the existing plant community. Summary of the invention

[0006] The purpose of the present invention is to provide a method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi and tolerant earthworm castings, so as to solve the problems raised in the above-mentioned background technology.

[0007] The purpose of the present invention is achieved through the following technical scheme: a method for guiding the restoration of degraded plant communities in light rare earth open-pit mines by using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm manure, which uses a combination mode of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm manure to guide the construction of a plant community-soil fungi-soil ecosystem circulation system, and uses a combination method of combining dominant plant species with different mycorrhizal fungi and adding tolerant earthworm manure to guide the restoration of existing plant communities in light rare earth mines;

[0008] The specific steps include:

[0009] The first step is to analyze the vegetation diversity of light rare earth open-pit mines;

[0010] The second step is the screening of mycorrhizal fungi and tolerant vermicompost;

[0011] The mycorrhizal fungi of the dominant plant species in the plant community, Glomus aggregatum, Glomus intraradices (Rhizophagus intraradices), Acaulosporalaevis, Rhizophagus fasciculatus, Gigasporamargarita, Funneliformis mosseae (Glomusmosseae), Claroideoglomus claroideum, Scutellospora calospora, Diversisporaspurca, Paraglomusbrasilianum, were collected on site;

[0012] The second step is the preparation of mycorrhizal fungi and tolerant vermicompost;

[0013] The third step is to determine the La and Ce content of the dominant plants in the mine plant community and their rhizosphere soil;

[0014] The fourth step is to use the combination model of bicolor limonium-mycorrhizal fungi-tolerant earthworm manure to guide the recovery of existing plant communities.

[0015] Furthermore, the five shrubs and grasses with high abundance, frequency and importance values ​​are selected as dominant plants, namely, Pinus sylvestris var. mongolica, Stipa breviflora, Artemisia annua, Astragalus erectus, Saussurea argentei and Elymus dactylis.

[0016] Furthermore, the light rare earth open-pit mine vegetation diversity analysis in the first step includes a light rare earth open-pit mine plant diversity survey, which surveys the plant species in the light rare earth open-pit mine;

[0017] It also includes plant diversity analysis of light rare earth open pit mines, comparing the plant community diversity indexes of 9 different sampling points, selecting shrubs and grasses with high abundance, frequency and importance values ​​as dominant plants, and constructing the plant community of light rare earth open pit mines with Limonium bicolor as the dominant plant species and combining with dominant shrubs and grasses;

[0018] Further, the preparation of mycorrhizal fungi and tolerant earthworm castings in the second step is as follows;

[0019] Mycorrhizal fungi were grown in a greenhouse potted culture, with soil samples containing different concentrations of lanthanum (La) and cerium (Ce), tolerant earthworm castings added, and Limonium bicolor and mycorrhiza inoculated;

[0020] Mechanical separation of earthworms and feces, separation by mechanical screening, and then collection of earthworm feces for fermentation in a fermentation tank;

[0021] The greenhouse pot method was used to set up three soil samples with different concentrations of lanthanum (La) and cerium (Ce), namely high concentration (La2031.71mg / kg, Ce4162.03mg / kg), medium concentration (La329.41mg / kg, Ce741.81mg / kg), and low concentration (La107.15mg / kg, Ce362.11mg / kg). 2 The tolerant vermicompost was treated with Limonium bicolor and mycorrhizae, and a blank control (CK) was set up in a group, each treatment was set up with 3 replicates, and a total of 54 pots were randomly arranged;

[0022] Add 2kg sterilized soil and 50g fungicide to each pot, add 50g fungicide to the blank control group, sow 5 strong and plump Limonium bicolor in each pot after germination, and thin out the seedlings one week after germination, leaving 3 plants with similar growth in each pot;

[0023] The experiment was carried out in a laboratory with natural lighting, a temperature of 25°C to 30°C, a relative humidity of 32% to 40%, and watering of plants at regular intervals using the weighing method. Data were measured 90 days after plant emergence.

[0024] Furthermore, the earthworms and feces are separated mechanically, and mechanical screening is used to separate them, and then the earthworm castings are collected;

[0025] The vermicompost uses a fermentation tank that makes full use of solar energy for continuous fermentation. The feces are mixed with fermentation bacteria. The feces in the tank are turned over once a day with a turning machine. Fresh feces are sent in from one side of the tank, and the fermented materials are sent out from the other end of the tank.

[0026] The greenhouse structure fermentation shed fully utilizes solar energy and has a high fermentation temperature. It takes 7 days in summer and about 15 days in winter to ferment and decompose. The fermentation temperature is controlled below 60°C, making it a mature high-quality fertilizer.

[0027] Furthermore, the third step includes measuring the physical and chemical properties of the rhizosphere soil;

[0028] Variance analysis shows that the values ​​of various physical indicators of the soil in the light rare earth open-pit mine do not change much. The soil bulk density, moisture, capillary porosity and non-capillary porosity of different soil layers do not change significantly. The soil moisture content shows a decreasing trend from the surface to the bottom layer.

[0029] Determination of light rare earth elements La and Ce in soil;

[0030] The content of light rare earth La and Ce in the soil of light rare earth open-pit mines was determined and compared at 9 different sampling points for plant community diversity;

[0031] Determination of La and Ce in roots, stems and leaves of Limonium bicolor;

[0032] Determine whether Limonium bicolor is a La and Ce enrichment plant, and use Limonium bicolor as a plant that slows down the migration speed of La and Ce elements in the soil;

[0033] Furthermore, in the fourth step, the combination model of Limonium bicolor-mycorrhizal fungi-tolerant earthworm manure is used to guide the restoration of the existing plant community, including the following steps:

[0034] Guide the restoration of plant communities, with the dominant plant Limonium bicolor as the core, and guide the gradual restoration of shrubs and herbaceous plants in the existing plant communities after improving soil physical and chemical properties and increasing soil fertility by adding different mycorrhizal fungi and tolerant earthworm castings;

[0035] The design of restoration of different plant communities guides the restoration of the "trees + shrubs + herbaceous plants" plant community; guides the restoration of the "shrubs + herbaceous plants" plant community; guides the restoration of the "trees + herbaceous plants" plant community.

[0036] Furthermore, the design of restoration of different plant communities specifically includes the following;

[0037] Guide the restoration of the "trees + shrubs + herbaceous plants" plant community;

[0038] The existing plant community is Populus tomentosa + Robinia pseudoacacia + Sophora japonica + Platycladus orientalis + Prunus persica + Syringa syringae + Pinus sylvestris var. mongolica. Add the combination of Limonium bicolor + Glomus aggregatum + tolerant earthworm manure, and add dominant shrubs and herbaceous plants such as Lespedeza chinensis, Stipa brevisflower, and Artemisia annua that reduce soil pollutants to jointly complete the design of guiding the restoration of the existing plant community.

[0039] Guide the restoration of the "shrubs + herbs" plant community;

[0040] The existing plant community is Xinjiang Populus + Sophora japonica + Populus tomentosa + Prunus persica + Pinus sylvestris. Add the combination of Limonium bicolor + Glomusintraradices + tolerant earthworm manure, and add dominant shrubs + herbaceous plants such as lilac, Lespedeza, Prunus armeniaca, and Saussurea argentea to reduce soil pollutants, and jointly complete the design of guiding the restoration of the existing plant community;

[0041] Guide the restoration of the "tree + herbaceous plant" plant community;

[0042] The existing plant community is Sophora japonica + Populus tomentosa + Prunus persica + Syringa syringae + Syringa sylvestris + Platycladus orientalis + Pinus sylvestris. The combination of Limonium bicolor + Acaulosporalaevis + tolerant earthworm castings is added, and the dominant herb Elymus dahliae that reduces soil pollutants, the perennial herb Lespedeza bicolor with slope protection and soil and water conservation functions, and the perennial herb Polygonum aviculare with sand fixation function are added to complete the design of guiding the restoration of the existing plant community.

[0043] An evaluation method for restoring degraded plant communities in light rare earth open-pit mines guided by a combination of Limonium bicolor, mycorrhizal fungi and tolerant earthworm castings comprises the following steps:

[0044] Survey on the status of plants in rare earth tailings ponds, including survey of plant species in light rare earth open pit mines and statistical analysis of plant species;

[0045] Analysis of the effects of restoration of existing plant communities on soil, including soil physical / chemical properties and changes, soil light rare earth content and changes;

[0046] Screening of light rare earth enriched plants and production of mycorrhizal environmentally friendly pots, including screening of light rare earth enriched plants and cultivation by greenhouse potting method;

[0047] Vegetation community evaluation and plant restoration model optimization, and determining the ecological restoration characteristics of plant communities through hierarchical analysis method.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The restoration method of the present invention is helpful to improve the survival rate of plants in light rare earth mines, and restores the existing plant community in the mine by screening a combination of plant-mycorrhiza-earthworm manure, so as to achieve the purpose of self-recovery and sustainable growth of the plant community. The technology of using the plant community dominant plant of light rare earth native plants, the dichromatic limonium, and the locally collected tolerant mycorrhizal fungi and tolerant earthworm manure to jointly guide the restoration of the existing plant community has the characteristics of improving the plant community recovery rate, being environmentally friendly, having excellent effects, and having simple technical and process operations and easy construction, and being able to reduce the light rare earth content in the soil. Compared with similar restoration methods, the invention has high sustainability, is beautiful and safe, and is easy to promote and apply. The invention has broad application prospects and market demand.

[0050] In the example of the present invention, in the cold and arid light rare earth open-pit mine in the north, two-color blood-replenishing grass is planted in the existing degraded or reverse succession plant community, and mycorrhizal fungi are inoculated, and tolerant earthworm castings are added. This method can improve the survival rate of the existing plant community and rebuild the microecological environment of the community. While increasing the biomass of individual plants in the plant community, it also improves the landscape effect of the plant community. "Two-color blood-replenishing grass-mycorrhizal fungi-tolerant earthworm castings" guides the construction of a good "plant community-soil fungi-soil" ecosystem cycle, which is suitable for the restoration of existing plant communities in northern light rare earth open-pit mines.

[0051] The present invention found that the content of light rare earth elements in the soil of light rare earth open-pit mines is Ce>La>Nd>Pr>Sm>Pm>Eu from high to low, among which La and Ce elements account for about 72% of the total light rare earth content in the mine, and La and Ce element compounds mostly exist in the ecological environment system in soluble states such as sulfate, nitrate, and chloride. Therefore, the basis for the restoration of plant communities in light rare earth open-pit mines is to determine the dominant plants that adapt to the community, increase mycorrhizal fungi and organic fertilizers, and use the "two-color blood-replenishing grass-mycorrhizal fungi-tolerant earthworm manure fertilizer" combination model in light rare earth, cold and arid habitats to guide the self-recovery function of the existing plant community.

[0052] The present invention utilizes adult plants to increase mycorrhizal agents and earthworm castings fertilizers during the transplanting process, promotes plant survival and enhances their resistance to light rare earths, and screens out combinations of plant-mycorrhizal-earthworm castings fertilizers for different light rare earth elements. The overall plant community of the mine is restored by a method of restoring the plant community and the light rare earth element content in the soil is reduced, thereby guiding the restoration of the plant community from two aspects of the ecological niche and the micro-ecological system, so as to achieve the purpose of preventing the degradation of the existing plant community and guiding the restoration of the existing plant community. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a schematic diagram of the change of light rare earth element content in Limonium bicolor after inoculation of mycorrhizae according to the present invention;

[0054] Figure 2 Schematic diagram of the effect of La element stress on the chlorophyll content of Limonium bicolor in the present invention;

[0055] Figure 3 Schematic diagram of the effect of Ce element stress on the chlorophyll content of Limonium bicolor of the present invention;

[0056] Figure 4 This is a schematic diagram of CAT and MDA contents of Limonium bicolor under La element stress of the present invention;

[0057] Figure 5 Schematic diagram of POD and SOD contents of Limonium bicolor under La element stress of the present invention;

[0058] Figure 6 This invention is Ce 3+ Schematic diagram of CAT and MDA contents in Limonium bicolor under stress;

[0059] Figure 7 Schematic diagram of POD and SOD contents of Limonium bicolor under Ce element stress of the present invention;

[0060] Figure 8 It is a schematic diagram of the plant community construction of the present invention;

[0061] Fig. 9 It is a schematic diagram of plant community restoration evaluation of the present invention. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0063] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention. Specific embodiment one:

[0066] like Figure 1-9 As shown, a method for guiding the restoration of degraded plant communities in light rare earth open-pit mines by using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm manure is provided. The method uses a combination model of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm manure to guide the construction of a plant community-soil fungus-soil ecosystem circulation system, and uses a combination method of combining dominant plant species with different mycorrhizal fungi and adding tolerant earthworm manure to guide the restoration of existing plant communities in light rare earth mines.

[0067] The specific steps include:

[0068] The first step is to analyze the vegetation diversity of light rare earth open-pit mines;

[0069] ① Plant diversity survey of light rare earth open-pit mines. The plant species of light rare earth open-pit mines were investigated, with a total of 27 species of 24 genera in 14 families, of which Leguminosae, Asteraceae, Gramineae and Pinaceae were dominant, as shown in Table 1. There are a total of 24 genera of seed plants in the survey area. The plant species were statistically analyzed by genus. There are 3 genera and 6 species with more than 2 species, accounting for 12.50% and 22.22% of the total number of genera and species, respectively. That is, Stipa (2 species), Artemisia (2 species), and Pinus (2 species) are the dominant genera of the seed plant flora in this area. There are 21 genera and 21 species with 1 plant, accounting for 87.50% and 77.77% of the total number of genera and species, respectively, such as Elymus, Achnatherum, Dogtail, Salsola, etc. Therefore, the plant genera in this area are mostly dominated by single plant genera.

[0070] Table 1 List of plant species in light rare earth open-pit mines

[0071]

[0072]

[0073] ② Calculation of plant diversity in light rare earth open-pit mines

[0074] The Margalef index reflects the species richness of the community, the Shannon-Wiener index reflects the diversity of community species based on the number of species, the Simpson index indicates the dominance of species, and the Pielou index indicates the uniformity of species distribution in the community. As shown in Table 2, the plant community diversity indexes of 9 different sampling points were compared. The closer the four different indices were to the mine pit and the spoil dump, the lower the diversity, and the farther the distance was, the higher the diversity was. The distribution characteristics of low soil content in the north and high soil content in the surrounding areas may be due to the fact that the light rare earth open-pit mine is located in a typical grassland with less grassland species composition and the northern grassland is less damaged.

[0075] Table 2 Plant diversity in light rare earth open-pit mines

[0076]

[0077] The plant community is simple, mostly dominated by herbs and shrubs grown in wild vegetation, with a small number of trees, as shown in Table 3. There are 9 plant species, mainly Gramineae, Asteraceae and Leguminosae, and herbaceous plants are the main plant communities in this area. Therefore, the five shrubs and grasses with the highest abundance, frequency and importance values ​​are selected, namely, Pinus sylvestris var. mongolica, Stipa brevisflower, Artemisia annua, Astragalus erectus, Saussurea argentei and Elymus solani as dominant plants, and Limonium bicolor is used as the dominant plant species combined with dominant shrubs and grasses to jointly construct the plant community of the light rare earth open-pit mine.

[0078] Table 3 Plant diversity analysis

[0079]

[0080]

[0081] The second step is the screening of mycorrhizal fungi and tolerant vermicompost;

[0082] Screening of existing mycorrhizal fungi, preparation of bacterial agents of multiple mycorrhizal fungi, and on-site collection of mycorrhizal fungi of the dominant plant species of plant community, including Glomusaggregatum, Glomus intraradices (Rhizophagusintraradices), Acaulospora laevis, Rhizophagus fasciculatus, Gigasporamargarita, Funneliformis mosseae (Glomus mosseae), Claroideoglomus claroideum, Scutellospora calospora, Diversispora spurca, and Paraglomus brasilianum. Among them, Glomusaggregatum: belongs to a type of mycorrhizal fungi, forming a symbiotic relationship with Limonium dicolor, which helps to improve the nutrient absorption and growth and development of plants. Glomusintraradices: also known as Rhizophagusintraradices, is a common mycorrhizal fungus that forms a symbiotic relationship with Limonium dicolor, promoting the root growth and nutrient absorption of plants. Acaulosporalaevis: This is a type of endomycorrhizal fungus that also forms a symbiotic relationship with Limonium bicolor, which helps improve the plant's nutrient absorption and stress resistance. The inoculant was obtained by propagation in the experiment, and the inoculant includes a rhizosphere sand and soil mixture, spores, hyphae and infected plant root segments.

[0083] The mycorrhizal fungi of the dominant plant species in the plant community, Glomus aggregatum, Glomus intraradices (Rhizophagus intraradices), Acaulosporalaevis, Rhizophagus fasciculatus, Gigasporamargarita, Funneliformis mosseae (Glomusmosseae), Claroideoglomus claroideum, Scutellospora calospora, Diversisporaspurca, Paraglomusbrasilianum, were collected on site;

[0084] The second step is the preparation of mycorrhizal fungi and tolerant vermicompost;

[0085] The experiment adopted the greenhouse pot method and set up three soil samples with different concentrations of lanthanum (La) and cerium (Ce), namely high concentration (La 2031.71mg / kg, Ce 4162.03mg / kg), medium concentration (La 329.41mg / kg, Ce 741.81mg / kg), and low concentration (La 107.15mg / kg, Ce 362.11mg / kg); and then added 0.2kg / m 2 Tolerant earthworm castings. The two-color Limonium and mycorrhizal inoculation treatments and the blank control test (CK) were set up in one group, with 3 replicates for each treatment, and a total of 54 pots were randomly arranged. 2kg of sterilized soil and 50g of fungicide were added to each pot, and 50g of fungicide was added to the blank control group. Five strong and full two-color Limonium were sown in each pot after germination. Thinning was carried out one week after emergence, and 3 plants with similar growth were left in each pot. The experiment was carried out in the Key Laboratory of Forest Cultivation Microorganisms of Inner Mongolia Autonomous Region, with natural light, temperature of 25℃~30℃, relative humidity of 32%~40%, and watering of plants at the time of weighing method. Data were measured 90d after the plants emerged.

[0086] The screening of mycorrhizal fungi and the preparation of bacterial agents were carried out with the dominant plant species of the plant community, Limonium bicolor, as the core. The effects of inoculating Glomus aggregatum, Glomus intraradices, and Acaulosporalaevis on the mycorrhizal infection rate and biomass of Limonium bicolor in soils with different concentrations of pollution were shown in Table 4. The uninoculated control group CK had no mycorrhizal infection. The measured data are shown in Table 4. The soil pollution concentration is divided into high pollution area, medium concentration area, and low concentration area. In the high concentration area, 0.2 kg / m 2 The experiment was conducted in soil with tolerant earthworm castings. Limonium bicolor successfully established a symbiotic relationship with the tested mycorrhizae. The mycorrhizal infection rate gradually increased with the decrease of soil pollutant concentrations, and there was no mycorrhizal infection in the blank control group. The mycorrhizal infection rate of Limonium bicolor was 0.51% to 64.81%, among which the infection rate of Glomus aggregatum inoculation was the highest. The biomass of the aboveground organs and roots of Limonium bicolor decreased significantly with the increase of light rare earth concentration. The biomass increased after inoculation of mycorrhizae. The dry weight of the aboveground organs of Limonium bicolor increased by 1.46, 1.67 and 1.88 times, respectively, and the dry weight of the roots increased by 1.73, 1.98 and 2.08 times, respectively.

[0087] Table 4 Statistics of mycorrhizal infection rate and biomass of Limonium bicolor

[0088]

[0089] Depend on Figure 1It can be seen that the contaminated soil was divided into high concentration area, medium concentration matrix and low concentration matrix, and tolerant earthworm manure was added for testing. The two-color limonium grass was inoculated with mycorrhizae Glomusaggregatum, Glomusintraradices, and Acaulosporalaevis, and a blank control group was set up. The detailed results are shown in Table 5. The content of light rare earth elements absorbed by the two-color limonium grass is: high concentration area > medium concentration area > low concentration area; the content of light rare earth elements in the organs of the two-color limonium grass is: root > stem > leaf, the two-color limonium grass inoculated with mycorrhizae > blank control group; the content of pollutants absorbed by the two-color limonium grass after inoculation with three kinds of mycorrhizae is: Glomus aggregatum > Glomusintraradices > Acaulosporalaevis.

[0090] In the soil contaminated by light rare earth elements La and Ce, the two-color blood-replenishing grass and mycorrhiza established a symbiotic relationship, indicating that mycorrhiza can survive and reproduce under certain concentrations of light rare earth pollution in the soil. The infection rates of two-color blood-replenishing grass and mycorrhiza are: Glomusaggregatum infection rate 4.36% to 64.81%, Glomusintraradices infection rate 2.57% to 42.23%, Acaulospora laevis infection rate 0.51% to 39.03%; compared with heavy metal elements, the mycorrhizal infection rate is slightly lower, mainly because the concentration of light rare earth elements in the test soil used is relatively high. In addition, the present invention found that the biomass of the aboveground organs and roots of the two-color blood-replenishing grass decreased significantly with the increase of light rare earth concentration. When the La element concentration increased by about 19 times and the Ce element concentration increased by about 11 times, the dry weight of the aboveground organs of the two-color blood-replenishing grass increased by 31.66% to 47.21%, and the dry weight of the root system increased by 32.61% to 40.06%. The infection rate of Limonium bicolor and mycorrhizae shows a "Homesis" effect, which first increases and then decreases with the increase of light rare earth concentration. Therefore, it is feasible to restore the symbiosis of mycorrhizae and Limonium bicolor in soil contaminated by a certain concentration of light rare earth.

[0091] Table 5 La and Ce contents in Limonium bicolor

[0092]

[0093]

[0094] The third step is to determine the La and Ce content of the dominant plants in the mine plant community and their rhizosphere soil;

[0095] ① Determination of the physical and chemical properties of rhizosphere soil. Variance analysis showed that the values ​​of various physical indicators of soil in light rare earth open-pit mines did not change much. The soil bulk density, moisture, capillary porosity and non-capillary porosity of different soil layers did not change significantly. The soil moisture content showed a decreasing trend from the surface to the bottom layer. The area has strong sunshine and low soil moisture, so drought-resistant plants should be the first choice for plants. The values ​​of various chemical indicators of soil environmental restoration vary greatly; the pH, organic matter content, total nitrogen, total phosphorus, total potassium, available phosphorus, available nitrogen and effective potassium content of soils in different soil layers vary little. The chemical indicators of soils in this area are all low, and artificial plant communities should choose perennial woody plants that increase and fix nutrients.

[0096] Table 6 Soil physical and chemical properties

[0097]

[0098] ② Determination of light rare earth La and Ce elements in soil. Through the determination of the content of light rare earth La and Ce elements in the soil of the light rare earth open-pit mine (see Table 7), it can be seen that the content of each element in the soil is Ce>La from high to low. The 9 sampling points are from high to low in the order of dump 4 south> East Mine south> West Mine south> Main Mine south> Dump 5 south> Dump 3 south> Dump 6 south> Barun Ore Dressing south> East Mine south.

[0099] Table 7 Light rare earth content in soil

[0100]

[0101]

[0102] ③ Determination of La and Ce in roots, stems and leaves of Limonium bicolor

[0103] As shown in Table 8, under different soil concentration stresses, the accumulation of La and Ce elements in Limonium bicolor showed an increasing trend with increasing concentration, indicating that Limonium bicolor has tolerance to rare earth elements; in addition, the Ce content in each organ of Limonium bicolor is higher than the La content, which indicates that Limonium bicolor has a higher tolerance to Ce in the soil. Through the transfer and enrichment coefficients, it was found that the transfer coefficient of Suaeda salsa was 0.32-0.58, and the enrichment coefficient was 0.03-0.11, both of which did not reach 1. It can be preliminarily judged that Limonium bicolor is not an enriched plant for La and Ce elements. The accumulation of underground organs of Limonium bicolor is significantly higher than that of aboveground organs, and the root system has a stronger enrichment ability than stems and leaves. Therefore, Limonium bicolor can be used as a plant to slow down the migration speed of La and Ce elements in the soil.

[0104] Table 8 La and Ce concentrations in the tested soils and their accumulation in the aboveground and underground organs of Limonium dicolor

[0105]

[0106] ④Effects of La or Ce stress on chlorophyll content in Limonium bicolor

[0107] The changes of chlorophyll a / b and chlorophyll (a+b) contents in Limonium bicolor under La stress are shown in Figure 2 As the concentration of La in the soil increases, the chlorophyll content increases first and then decreases. -1 When the concentration of La reached 4117.84 mg·kg -1 When the concentration of chlorophyll (a+b) was 2.5477 g / cm2, the content of chlorophyll (a+b) dropped to the lowest value, which was 56.45% lower than that of the control group. The study found that the two-color Limonium showed white spots, atrophy and other damage symptoms, but it could still survive; La element has a "low promotion and high inhibition" effect on the synthesis of chlorophyll in two-color Limonium, and high concentrations lead to a decrease in chlorophyll, which indirectly affects its photosynthesis.

[0108] The contents of chlorophyll a / b and chlorophyll (a+b) in Limonium bicolor under different concentrations of Ce element stress are shown in Figure 2. Figure 3 As the Ce concentration in the soil increases, it shows a trend of increasing first and then decreasing. When the Ce stress concentration is 3524.76 mg kg -1 When the concentration of Ce element stress was 7826.98 mg·kg -1 The content of chlorophyll (a+b) was the lowest when the Ce element was added, but it was still 13.40% higher than the control group. The experimental results showed that Ce element inhibited the synthesis of chlorophyll b, but did not affect the content of chlorophyll (a+b), which indicated that the synthesis of chlorophyll in Limonium bicolor was less affected and the chloroplasts were not significantly damaged.

[0109] When the concentrations of La and Ce in the soil were lower than 1393.37 mg kg -1 and 3524.76 mg kg -1 When the concentration was increased, the chlorophyll content increased; when the concentration increased further, the chlorophyll content decreased, which may be related to the inhibition of related enzymes, which hindered the activity of chlorophyll in Limonium bicolor, or it may be due to the destruction of the integrity and functionality of the cell membrane, resulting in a decrease in chlorophyll content. In addition, under different concentrations of Ce element stress, the chlorophyll content of Limonium bicolor was higher than that of the control group, which was different from the chlorophyll content characteristics under La element stress, indicating that Limonium bicolor showed a higher tolerance to Ce element stress.

[0110] ⑤Effects of La element stress on antioxidant system indicators of Limonium bicolor

[0111] Under different concentrations of La stress in the soil, the CAT and MDA activities of Limonium bicolor showed a trend of first increasing and then decreasing with the increase of La concentration (see Figure 4 ). When the La element concentration is 640.14 mg kg -1 When the La concentration was 1393.37 mg·kg -1 The maximum CAT activity of Limonium bicolor can reach 30.28 U·mg -1 , which was 87.53% higher than the control group; when the La element concentration was 1393.37-4117.84 mg·kg -1 When the La concentration was 640.14-1857.53 mg·kg -1 When the La concentration was 1857.53 mg·kg -1 The MDA activity of Limonium bicolor can reach a maximum of 12.51 U·mg -1 , 124.79% higher than the control.

[0112] Under different concentrations of La stress in the soil, the changes in the POD and SOD activities of Limonium bicolor increased with the increase of La concentration; the POD activity of Limonium bicolor showed a trend of first increasing and then decreasing, and gradually tending to be stable (see Figure 5 ). When the La element concentration is 2251.33 mg kg -1 The maximum POD activity of Limonium bicolor can reach 1631.21 U·mg -1 , which was 108.30% higher than the control group; the maximum SOD activity of Limonium bicolor could reach 187.69 U·mg -1 , which was 34.72% higher than the control group. -1 When , the SOD activity of Limonium bicolor dropped to the lowest value.

[0113] ⑥Effects of Ce element stress on the content of antioxidant system indexes in Limonium bicolor

[0114] Under the stress of different concentrations of Ce in the soil, the CAT and MDA activities of Limonium bicolor showed a trend of first increasing, then decreasing and then tending to a flattening trend with the increase of solution concentration (see Figure 6 ). When the Ce element concentration is 1196.54 mg kg -1The maximum CAT activity of Limonium bicolor can reach 22.61 U·mg -1 , which was 78.03% higher than the control group; when the Ce element concentration was 7826.98 mg·kg -1 When the concentration of Ce element hydroponic solution was 0~2251.33mg·kg -1 The MDA activity of Limonium bicolor showed an upward trend when the concentration exceeded 2251.33 mg·kg -1 The MDA activity showed a gentle downward trend.

[0115] Under the stress of different concentrations of Ce in the soil, the activity of POD and SOD in Limonium bicolor showed a trend of first increasing and then decreasing (see Figure 7 ). When the Ce element concentration is 1196.54~3524.76mg·kg -1 When the Ce concentration was 3524.76 mg·kg -1 The SOD activity of Limonium bicolor showed an overall downward trend. When the Ce concentration was 7826.98 mg·kg -1 SOD activity is lowest when

[0116] The higher the concentration of La or Ce in the soil, the more serious the toxicity to Limonium bicolor, which will cause damage to the cell tissue of Limonium bicolor, and then trigger a series of physiological and biochemical metabolic disorders. Although the SOD activity of Limonium bicolor decreased, the CAD and POD activities were higher than those of the control group under stress, indicating that Limonium bicolor has a strong detoxification mechanism and can resist the damage caused by oxidative stress.

[0117] The fourth step is to use the combination model of bicolor limonium-mycorrhizal fungi-tolerant earthworm manure to guide the recovery of existing plant communities.

[0118] The five shrubs and grasses with high abundance, frequency and importance values ​​are selected as dominant plants, namely, Pinus sylvestris var. mongolica, Stipa breviflora, Artemisia annua, Astragalus erectus, Saussurea argentei and Elymus dactylis.

[0119] The vegetation diversity analysis of the light rare earth open-pit mine in the first step includes a plant diversity survey of the light rare earth open-pit mine, and an investigation of the plant species in the light rare earth open-pit mine;

[0120] It also includes plant diversity analysis of light rare earth open pit mines, comparing the plant community diversity indexes of 9 different sampling points, selecting shrubs and grasses with high abundance, frequency and importance values ​​as dominant plants, and constructing the plant community of light rare earth open pit mines with Limonium bicolor as the dominant plant species and combining with dominant shrubs and grasses;

[0121] The preparation of mycorrhizal fungi and tolerant earthworm castings in the second step is as follows;

[0122] Mycorrhizal fungi were grown in a greenhouse potted culture, with soil samples containing different concentrations of lanthanum (La) and cerium (Ce), tolerant earthworm castings added, and Limonium bicolor and mycorrhiza inoculated;

[0123] Mechanical separation of earthworms and feces, separation by mechanical screening, and then collection of earthworm feces for fermentation in a fermentation tank;

[0124] The greenhouse pot method was used to set up three soil samples with different concentrations of lanthanum (La) and cerium (Ce), namely high concentration (La2031.71mg / kg, Ce4162.03mg / kg), medium concentration (La329.41mg / kg, Ce741.81mg / kg), and low concentration (La107.15mg / kg, Ce362.11mg / kg). 2 The tolerant vermicompost was treated with Limonium bicolor and mycorrhizae, and a blank control (CK) was set up in a group, each treatment was set up with 3 replicates, and a total of 54 pots were randomly arranged;

[0125] Add 2kg sterilized soil and 50g fungicide to each pot, add 50g fungicide to the blank control group, sow 5 strong and plump Limonium bicolor in each pot after germination, and thin out the seedlings one week after germination, leaving 3 plants with similar growth in each pot;

[0126] The experiment was carried out in a laboratory with natural lighting, a temperature of 25°C to 30°C, a relative humidity of 32% to 40%, and watering of plants at regular intervals using the weighing method. Data were measured 90 days after plant emergence.

[0127] The earthworms and feces are separated mechanically, and the earthworm feces are collected by mechanical screening;

[0128] The vermicompost uses a fermentation tank that makes full use of solar energy for continuous fermentation. The feces are mixed with fermentation bacteria. The feces in the tank are turned over once a day with a turning machine. Fresh feces are sent in from one side of the tank, and the fermented materials are sent out from the other end of the tank.

[0129] The greenhouse structure fermentation shed fully utilizes solar energy and has a high fermentation temperature. It takes 7 days in summer and about 15 days in winter to ferment and decompose. The fermentation temperature is controlled below 60°C, making it a mature high-quality fertilizer.

[0130] The third step includes the determination of physical and chemical properties in the rhizosphere soil;

[0131] Variance analysis shows that the values ​​of various physical indicators of the soil in the light rare earth open-pit mine do not change much. The soil bulk density, moisture, capillary porosity and non-capillary porosity of different soil layers do not change significantly. The soil moisture content shows a decreasing trend from the surface to the bottom layer.

[0132] Determination of light rare earth elements La and Ce in soil;

[0133] The content of light rare earth La and Ce in the soil of light rare earth open-pit mines was determined and compared at 9 different sampling points for plant community diversity;

[0134] Determination of La and Ce in roots, stems and leaves of Limonium bicolor;

[0135] Determine whether Limonium bicolor is a La and Ce enrichment plant, and use Limonium bicolor as a plant that slows down the migration speed of La and Ce elements in the soil;

[0136] The fourth step uses a combination model of Limonium bicolor-mycorrhizal fungi-tolerant earthworm manure to guide the restoration of the existing plant community, including the following steps:

[0137] Guide the restoration of plant communities, with the dominant plant Limonium bicolor as the core, and guide the gradual restoration of shrubs and herbaceous plants in the existing plant communities after improving soil physical and chemical properties and increasing soil fertility by adding different mycorrhizal fungi and tolerant earthworm castings;

[0138] Suggestions on plant community restoration Figure 8 With the dominant plant Limonium bicolor as the core, by adding different mycorrhizal fungi and tolerant earthworm castings, after improving the physical and chemical properties of the soil and increasing soil fertility, the shrubs and herbaceous plants in the existing plant community are guided to gradually recover; after increasing their own biomass, they jointly build an ecosystem nutrient cycle with Limonium bicolor, increasing the ecosystem productivity and stability of the plant community; ectomycorrhizae, tolerant earthworm castings and the recovering plant community jointly improve plant diversity, while also fixing light rare earth elements in the soil and conserving water resources, thereby preliminarily completing the goal of guiding the recovery of the plant community.

[0139] The design of restoration of different plant communities guides the restoration of the "trees + shrubs + herbaceous plants" plant community; guides the restoration of the "shrubs + herbaceous plants" plant community; guides the restoration of the "trees + herbaceous plants" plant community.

[0140] The specific designs for restoration of different plant communities include the following;

[0141] Guide the restoration of the "trees + shrubs + herbaceous plants" plant community;

[0142] The existing plant community is Populus tomentosa + Robinia pseudoacacia + Sophora japonica + Platycladus orientalis + Prunus persica + Syringa syringae + Pinus sylvestris var. mongolica. Add the combination of Limonium bicolor + Glomus aggregatum + tolerant earthworm manure, and add dominant shrubs and herbaceous plants such as Lespedeza chinensis, Stipa brevisflower, and Artemisia annua that reduce soil pollutants to jointly complete the design of guiding the restoration of the existing plant community.

[0143] Guide the restoration of the "shrubs + herbs" plant community;

[0144] The existing plant community is Xinjiang Populus + Sophora japonica + Populus tomentosa + Prunus persica + Pinus sylvestris. Add the combination of Limonium bicolor + Glomusintraradices + tolerant earthworm manure, and add dominant shrubs + herbaceous plants such as lilac, Lespedeza, Prunus armeniaca, and Saussurea argentea to reduce soil pollutants, and jointly complete the design of guiding the restoration of the existing plant community;

[0145] Guide the restoration of the "tree + herbaceous plant" plant community;

[0146] The existing plant community is Sophora japonica + Populus tomentosa + Prunus persica + Syringa syringae + Syringa sylvestris + Platycladus orientalis + Pinus sylvestris. The combination of Limonium bicolor + Acaulosporalaevis + tolerant earthworm castings is added, and the dominant herb Elymus dahliae that reduces soil pollutants, the perennial herb Lespedeza bicolor with slope protection and soil and water conservation functions, and the perennial herb Polygonum aviculare with sand fixation function are added to complete the design of guiding the restoration of the existing plant community.

[0147] In the present invention, after mycorrhizae and dicolor limonium are inoculated, the content of light rare earth La and Ce elements in the plant body increases with the increase of light rare earth element content in the soil. Mycorrhizae inoculation of dicolor limonium can increase the absorption of host plants at a certain concentration of light rare earths. Its absorption mechanism may be to increase the channels for dicolor limonium to absorb nutrients such as N, P, and K through mycorrhizae, and at the same time increase the absorption of light rare earth elements. After inoculation of mycorrhizae, dicolor limonium reduces the transfer coefficient of the host plant body and increases the root retention coefficient. After inoculation of mycorrhizae, mycorrhizal fungi and dicolor limonium can catalyze the synthesis of chelated synthases (PCs), chelate soluble ions of La and Ce elements in the cytoplasm, and transfer La and Ce ions to plant vacuoles, which can effectively improve the tolerance of dicolor limonium. Therefore, in soil contaminated with La and Ce light rare earth elements, mycorrhizae have a negative effect on the transfer of light rare earth elements by dicolor limonium, resulting in a decrease in the transfer ability of tolerant plants, which may be related to the interaction between mycorrhizal fungi, host plants, and light rare earth elements.

[0148] Compared with similar restoration methods, the present invention has high sustainability, beautiful appearance, safety, and is easy to promote and apply. The invention has broad application prospects and market demand. In the cold and arid light rare earth open-pit mines in northern China, the present invention planted two-color blood-replenishing grass in the existing degraded or reverse succession plant community, inoculated mycorrhizal fungi, and then added tolerant earthworm manure. This method can improve the survival rate of the existing plant community, reconstruct the microecological environment of the community, and improve the biomass of individual plants in the plant community while also improving the landscape effect of the plant community. "Two-color blood-replenishing grass-mycorrhizal fungi-tolerant earthworm manure" guides the construction of a good "plant community-soil fungi-soil" ecosystem cycle, which is suitable for the restoration of existing plant communities in northern light rare earth open-pit mines. Specific embodiment 2:

[0150] An evaluation method for restoring degraded plant communities in light rare earth open-pit mines guided by a combination of Limonium bicolor, mycorrhizal fungi and tolerant earthworm castings comprises the following steps:

[0151] Survey on the status of plants in rare earth tailings ponds, including survey of plant species in light rare earth open pit mines and statistical analysis of plant species;

[0152] Analysis of the effects of restoration of existing plant communities on soil, including soil physical / chemical properties and changes, soil light rare earth content and changes;

[0153] Screening of light rare earth enriched plants and production of mycorrhizal environmentally friendly pots, including screening of light rare earth enriched plants and cultivation by greenhouse potting method;

[0154] Vegetation community evaluation and plant restoration model optimization, and determining the ecological restoration characteristics of plant communities through hierarchical analysis method.

[0155] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0156] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings, characterized in that: This method uses the combination model of Limonium bicolor-mycorrhizal fungi-tolerant earthworm manure to guide the construction of a plant community-soil fungi-soil ecosystem circulation system, and uses a combination method of combining dominant plant species with different mycorrhizal fungi and adding tolerant earthworm manure to guide the restoration of existing plant communities in light rare earth mines. The specific steps include: The first step is to analyze the vegetation diversity of light rare earth open-pit mines; The second step is the screening of mycorrhizal fungi and tolerant vermicompost; The second step is the preparation of mycorrhizal fungi and tolerant vermicompost; The third step is to determine the La and Ce content of the dominant plants in the mine plant community and their rhizosphere soil; The fourth step is to use the combination model of bicolor limonium-mycorrhizal fungi-tolerant earthworm manure to guide the recovery of existing plant communities.

2. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings according to claim 1, characterized in that: The five shrubs and grasses with high abundance, frequency and importance values ​​are selected as dominant plants, namely, Pinus sylvestris var. mongolica, Stipa breviflora, Artemisia annua, Astragalus erectus, Saussurea argentei and Elymus dactylis.

3. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi and tolerant earthworm castings according to claim 2, characterized in that: The vegetation diversity analysis of the light rare earth open-pit mine in the first step includes a plant diversity survey of the light rare earth open-pit mine, and an investigation of the plant species in the light rare earth open-pit mine; It also includes a plant diversity analysis of light rare earth open-pit mines, comparing the plant community diversity indices of nine different sampling points, selecting shrubs and herbaceous plants with high abundance, frequency and importance values ​​as dominant plants, and using Limonium bicolor as the dominant plant species combined with dominant shrubs and herbaceous plants to jointly construct the plant community of light rare earth open-pit mines.

4. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings according to claim 3, characterized in that: The preparation of mycorrhizal fungi and tolerant earthworm castings in the second step is as follows; Mycorrhizal fungi were grown in a greenhouse potted culture, with soil samples containing different concentrations of lanthanum (La) and cerium (Ce), tolerant earthworm castings added, and Limonium bicolor and mycorrhiza inoculated; Mechanical separation of earthworms and feces, separation by mechanical screening, and then collection of earthworm feces for fermentation in a fermentation tank; The greenhouse pot method was used to set up three soil samples with different concentrations of lanthanum (La) and cerium (Ce), namely high concentration (La2031.71mg / kg, Ce4162.03mg / kg), medium concentration (La329.41mg / kg, Ce741.81mg / kg), and low concentration (La107.15mg / kg, Ce362.11mg / kg). 2 The tolerant vermicompost was treated with Limonium bicolor and mycorrhizae, and a blank control (CK) was set up in a group, each treatment was set up with 3 replicates, and a total of 54 pots were randomly arranged; Add 2kg sterilized soil and 50g fungicide to each pot, add 50g fungicide to the blank control group, sow 5 strong and plump Limonium bicolor in each pot after germination, and thin out the seedlings one week after germination, leaving 3 plants with similar growth in each pot; The experiment was carried out in a laboratory with natural lighting, a temperature of 25°C to 30°C, a relative humidity of 32% to 40%, and watering of plants at regular intervals using the weighing method. Data were measured 90 days after plant emergence.

5. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings according to claim 4, characterized in that: The earthworms and feces are separated mechanically, and the earthworm feces are collected by mechanical screening; The vermicompost uses a fermentation tank that makes full use of solar energy for continuous fermentation. The feces are mixed with fermentation bacteria. The feces in the tank are turned over once a day with a turning machine. Fresh feces are sent in from one side of the tank, and the fermented materials are sent out from the other end of the tank. The greenhouse structure fermentation shed fully utilizes solar energy and has a high fermentation temperature. It takes 7 days in summer and about 15 days in winter to ferment and decompose. The fermentation temperature is controlled below 60°C, making it a mature high-quality fertilizer.

6. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings according to claim 5, characterized in that: The third step includes the determination of physical and chemical properties in the rhizosphere soil; Variance analysis shows that the values ​​of various physical indicators of the soil in the light rare earth open-pit mine do not change much. The soil bulk density, moisture, capillary porosity and non-capillary porosity of different soil layers do not change significantly. The soil moisture content shows a decreasing trend from the surface to the bottom layer. Determination of light rare earth elements La and Ce in soil; The content of light rare earth La and Ce in the soil of light rare earth open-pit mines was determined and compared at 9 different sampling points for plant community diversity; Determination of La and Ce in roots, stems and leaves of Limonium bicolor; Determine whether Limonium bicolor is a plant that accumulates La and Ce elements, and use Limonium bicolor as a plant that slows down the migration rate of La and Ce elements in the soil.

7. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings according to claim 6, characterized in that: The fourth step uses a combination model of Limonium bicolor-mycorrhizal fungi-tolerant earthworm manure to guide the restoration of the existing plant community, including the following steps: Guide the restoration of plant communities, with the dominant plant Limonium bicolor as the core, and guide the gradual restoration of shrubs and herbaceous plants in the existing plant communities after improving soil physical and chemical properties and increasing soil fertility by adding different mycorrhizal fungi and tolerant earthworm castings; The design of restoration of different plant communities guides the restoration of the "trees + shrubs + herbaceous plants" plant community; guides the restoration of the "shrubs + herbaceous plants" plant community; guides the restoration of the "trees + herbaceous plants" plant community.

8. The method for restoring degraded plant communities in light rare earth open-pit mines using a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings according to claim 7, characterized in that: The specific designs for restoration of different plant communities include the following; Guide the restoration of the "trees + shrubs + herbaceous plants" plant community; The existing plant community is Populus tomentosa + Robinia pseudoacacia + Sophora japonica + Platycladus orientalis + Prunus persica + Syringa syringae + Pinus sylvestris var. mongolica. Add the combination of Limonium bicolor + Glomus aggregatum + tolerant earthworm manure, and add dominant shrubs and herbaceous plants such as Lespedeza chinensis, Stipa brevisflower, and Artemisia annua that reduce soil pollutants to jointly complete the design of guiding the restoration of the existing plant community. Guide the restoration of "shrubs + herbs" plant communities; The existing plant community is Xinjiang Populus + Sophora japonica + Populus tomentosa + Prunus persica + Pinus sylvestris. Add the combination of Limonium bicolor + Glomusintraradices + tolerant earthworm manure, and add dominant shrubs + herbaceous plants such as lilac, Lespedeza, Prunus armeniaca, and Saussurea argentea to reduce soil pollutants, and jointly complete the design of guiding the restoration of the existing plant community; Guide the restoration of "trees + herbaceous plants" plant communities; The existing plant community is Sophora japonica + Populus tomentosa + Prunus persica + Syringa sylvestris + Platycladus orientalis + Pinus sylvestris. The combination of Limonium bicolor + Acaulosporalaevis + tolerant earthworm castings is added, and the dominant herb Elymus dahliae that reduces soil pollutants, the perennial herb Lespedeza bicolor with slope protection and soil and water conservation functions, and the perennial herb Polygonum aviculare with sand fixation function are added to complete the design of guiding the restoration of the existing plant community.

9. An evaluation method for restoring degraded plant communities in light rare earth open-pit mines guided by a combination of Limonium bicolor, mycorrhizal fungi, and tolerant earthworm castings, characterized in that: The method comprises the following steps: Survey on the status of plants in rare earth tailings ponds, including survey of plant species in light rare earth open pit mines and statistical analysis of plant species; Analysis of the effects of restoration of existing plant communities on soil, including soil physical / chemical properties and changes, soil light rare earth content and changes; Screening of light rare earth enriched plants and production of mycorrhizal environmentally friendly pots, including screening of light rare earth enriched plants and cultivation by greenhouse potting method; Vegetation community evaluation and plant restoration model optimization, and determining the ecological restoration characteristics of plant communities through hierarchical analysis method.

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