Desertification land restoration method based on artificial algae crust

Abstract

The invention provides an artificial algae crust-based desertification land restoration method, which comprises the following steps: screening algae species, carrying out artificial culture and resistance exercise on the screened species to obtain enough available biomass, treating the obtained biomass, adding auxiliary materials to prepare an artificial algae crust inoculum, and carrying out artificial algae crust-based desertification land restoration on the artificial algae crust inoculum. And inoculating the inoculum to a to-be-repaired area, and maintaining until algae crust is formed. According to the method, the artificial algae crust with similar species structure, function and physical characteristics as the algae crust naturally formed in the field is rapidly formed through human intervention, and can automatically grow and develop after colonization, so that the restoration treatment of the desertification land is realized; the method effectively solves the problems of microbial death of the inoculum caused by too strong stress generated by a field environment, low colonization success rate caused by instability of an inoculation area, and difficult growth and expansion of the inoculum caused by rapid dehydration of the inoculum due to poor water retention capacity of the desertification land, and is an environment-friendly, sustainable and efficient novel desertification organism treatment method.

Description

Technical Field

[0001] The invention belongs to the field of algae biotechnology and ecological restoration technology, and specifically relates to a method for restoring desertified land based on artificial algae crust. Background Art

[0002] Against the backdrop of climate change and intensified human disturbance, desertification is showing a degenerative trend from structural destruction to functional disorder. It is increasingly difficult to control desertification in arid land using existing technologies, and it is very easy to recur. Due to the lack of precipitation and soil moisture, it is difficult to create artificial vegetation, the survival rate is low and the sustainability is poor. In addition, excessive vegetation restoration may lead to excessive water consumption and exceed the threshold of regional water resource carrying capacity. Although chemical and engineering sand fixation have increased the speed of governance, they are costly, have high pollution risks and poor sustainability. In response to the above problems, it is urgent to develop green and environmentally friendly governance technologies with strong sustainability, and to propose new theories, methods and models for desertification governance. In the process of vegetation reconstruction, people gradually realized that the large number of biological crusts in desert areas, which are widely developed on exposed surfaces, play a vital role in stabilizing the sand surface, and are expected to become the key to solving the dilemma of desertification prevention and control and restoration of degraded ecosystems in arid areas.

[0003] Biological crust is a complex formed by spore plant groups such as algae, lichens and mosses and soil. It is widely distributed in arid areas and can occupy 30% of the land area in arid areas, and up to 70% in some areas. Biological crust species including algae can produce polysaccharides and a large number of hyphae, which can tightly adhere to and bind sand particles, fix the desert surface, and increase the wind speed of sand blowing. It is figuratively called "desert carpet" and the "living skin" of the earth; it also has powerful carbon and nitrogen fixation functions. The carbon fixation amount can account for 1% of the annual net primary productivity of the ecosystem, and the nitrogen fixation amount can account for 25% of the total nitrogen fixation of terrestrial organisms. It forms "fertile islands" in the distribution area and promotes nutrient improvement. Biological soil crust can recover on its own after the disturbance factors are removed, but this recovery takes tens to hundreds of years, so it is necessary to increase its recovery rate through artificial means. Algae are the pioneer groups in the formation of biological crusts in arid areas. Their successful colonization and formation of algae crusts are the prerequisites for the succession of lichen and moss biological crusts. Therefore, artificial algae crusts have important potential and prospects in the restoration and reconstruction of degraded ecosystems. Although existing technologies can propagate a small number of crusted algae, in addition to the large water consumption, the function of the cultivated algae is degraded due to the difference between the culture environment (aquatic) and the habitat (arid terrestrial), resulting in low survival rate of artificially cultured crusted algae after inoculation in the wild, and long-term and high-cost maintenance is required. Therefore, the culture system suitable for crusted algae is one of the current technical bottlenecks, and there is no complete artificial algae crust restoration technology system. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for desertification land restoration based on artificial algae crust in view of the deficiencies of the above-mentioned prior art. The method integrates species screening, artificial cultivation and artificial resistance training, inoculum preparation, inoculation and maintenance into a system, and through human intervention, quickly forms artificial algae crusts with species structure, function and physical characteristics similar to those of algae crusts naturally formed in the wild.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for restoring desertified land based on artificial algae crust, comprising the following steps:

[0007] S1. Screening and culture

[0008] The algae crusts collected from the wild were broken into 2-3 mm pieces and spread on the surface of a solid matrix moistened with liquid culture medium for screening and culture. The photosynthetically active radiation was 20-500 μE·m -2 ·s -1 , the culture temperature is 10-40°C, the relative humidity is 50-95%, the culture time is 1-5 days, and green filamentous colonies are obtained;

[0009] S2. Artificial culture

[0010] The green filamentous colonies obtained in S1 were placed in a terrestrial non-submerged culture system. The green filamentous colonies attached to the surface of the solid substrate moistened by the liquid culture medium and grew inside, but were not immersed in the liquid culture medium. -2 ·s -1 , the temperature is 10-40℃, the relative humidity is 25-75%, and the biomass on the surface and inside of the solid matrix is ​​not less than 20g·m -2 ;

[0011] S3. Artificial resistance training

[0012] The artificially cultured biomass obtained in S2 is subjected to artificial resistance training in situ and then collected; the artificial resistance training method includes: water shortage treatment, changing the culture temperature, changing the light intensity and spectrum composition, reducing the nitrogen concentration in the liquid culture medium, and adding hydrogen peroxide to the liquid culture medium;

[0013] S4. Preparation of artificial algae crust inoculum

[0014] After the artificial resistance-trained biomass obtained in S3 is dried until it is completely dehydrated, the treated biomass together with the attached solid matrix are sheared into fragments with a size of 1 to 5 mm, and auxiliary materials are added to prepare an artificial algae crust inoculum, wherein the proportion of the biomass to the total weight of the artificial algae crust inoculum is 40% to 80%;

[0015] S5. Inoculation and maintenance

[0016] The artificial algae crust inoculum obtained in S4 is mixed with water in a weight ratio of 1:5 to 1:100, stirred evenly, and then sprayed onto the surface of the area to be repaired, and maintained until the algae crust is formed.

[0017] Preferably, the green filamentous colonies in S1 include one or more of Microscalyx, Root Algae, Pseudobranch Algae, Monophyll, Anabaena, Nostoc, Sheath Algae, Thin Sheath Algae, Oscillatoria, and Tetrasaccharum; the proportion of algae dry biomass in the green filamentous colonies is not less than 50% of the total dry biomass of the colonies, and the proportion of the dry biomass of Microscalyx or Oscillatoria to the total dry biomass of the colonies is not less than 20%.

[0018] Preferably, the solid matrix for screening and culture in S1 is one or more of a filter membrane, non-woven fabric, woven fabric, sponge, and paper that has water absorption and water retention capabilities and is biodegradable, and the liquid culture medium is pure water.

[0019] Preferably, the solid matrix for artificial culture in S2 is one or more of a filter membrane, a non-woven fabric, a woven fabric, a sponge, and paper that has the ability to absorb and retain water and is biodegradable, and the liquid culture medium is a common algae liquid culture medium.

[0020] Preferably, the water shortage treatment in S3 is to dry the biomass in situ and then add water in situ, and the drying time is 6 to 48 hours; the culture temperature is changed in the range of 10 to 40°C; the light intensity is changed in the range of 100 to 2000 μE·m -2 ·s -1 ; The changing of the spectral composition includes increasing the proportion of blue light with a wavelength of 400-500nm or adding one or more of ultraviolet light with a wavelength of 200-400nm, wherein the proportion of ultraviolet light does not exceed 5% of the total light energy; the changing of the nitrogen concentration in the liquid culture is: maintaining sufficient nitrogen in the early stage of artificial culture, gradually reducing the nitrogen concentration 10 to 20 days before the end of artificial culture, and reducing the nitrogen concentration in the liquid culture medium to less than 5% of the initial concentration 7 to 10 days before the end of artificial culture; the concentration of hydrogen peroxide added to the liquid culture medium is 0.1% to 5%.

[0021] Preferably, the process of artificial resistance training in S3 is single, multiple or continuous, and any change in conditions is performed in a gradual manner.

[0022] Preferably, the auxiliary materials added in S4 include one or more of soybean fiber, bentonite, ascorbic acid, ascorbic acid esters, activated carbon powder, sodium starch octenyl succinate, hydroxymethyl cellulose, and sodium alginate, and all are in powder form; the proportion of the auxiliary materials to the total weight of the artificial algae crust inoculum is: 0.1% to 5% soybean fiber, 0.1% to 2% bentonite, 0.05% to 0.5% ascorbic acid, 0.05% to 0.5% ascorbic acid esters, 0.1 to 2% activated carbon powder, 0.1 to 5% sodium starch octenyl succinate, 0.1 to 5% hydroxymethyl cellulose, and 0.1 to 5% sodium alginate.

[0023] Preferably, the amount of artificial algae crust inoculant in S5 is 1 to 20 g·m -2 Calculation: The spray droplet size is 1 to 6 mm, producing a splashing effect.

[0024] Preferably, the maintenance method in S5 is: spraying 2-3 kg·m on the surface of the inoculated area on the 1st to 3rd day, the 4th to 7th day, the 10th to 15th day, and the 30th to 45th day after inoculation. -2 , 1~2kg·m -2 , 0.5~1kg·m -2 , 0.5~1kg·m -2 of water.

[0025] The present invention has the following significant technical effects:

[0026] 1. The present invention provides a desertification land restoration method based on artificial algae crusts, which integrates species screening, artificial cultivation and artificial resistance training, inoculum preparation, inoculation and maintenance into a system, and quickly forms artificial algae crusts with similar species structure, function and physical characteristics to those of algae crusts naturally formed in the wild through human intervention. After colonization, it can grow and develop on its own, which is an environmentally friendly and sustainable new method for desertification land management. The present invention effectively solves the problems of excessive stress from the wild environment leading to the death of inoculated species microorganisms, low colonization success rate due to unstable inoculation areas, and poor water retention capacity of desertified land leading to rapid dehydration of inoculum and difficulty in growth and expansion.

[0027] 2. The present invention uses species from naturally formed algae crusts to ensure that the selected species have the ability to form algae crusts and have the basis for survival in arid desert environments. By screening and culturing under conditions close to the natural habitat of crusted algae and lacking external nutrients, it is ensured that a microbial community with algae as the core that can grow well in an oligotrophic environment is obtained, especially a microbial community with nitrogen fixation function, breaking through the limitation of the lack of ecological function of a single strain. Microcoelenterate and Oscillatoria are common dominant filamentous cyanobacteria in algae crusts. They can fix soil particles through the entanglement of algae filaments and extracellular secretions to form algae crusts. The present invention ensures the initial biomass of Microcoelenterate and Oscillatoria in the selected colonies, and ensures their dominant position in the biomass obtained after artificial cultivation and artificial resistance training.

[0028] 3. The present invention uses a terrestrial non-immersion system to artificially cultivate the selected algae, thereby avoiding the problems of survival ability and functional degradation caused by the existing aquatic immersion culture system for cultivating terrestrial algae, while improving the output rate of biomass per unit volume of liquid culture medium, breaking through the bottleneck of the cultivation method. The cultivation system can also be used for artificial resistance training, saving time and cost, simplifying the operation process, wherein the progressive resistance training mode can make the cultivated biomass gradually adapt to the harsh environment of the inoculation area, including high light intensity, ultraviolet light, high temperature and drought stress; in the process of artificial cultivation and resistance training, by gradually reducing the nitrogen concentration, the proportion of nitrogen-fixing species in the species community structure of the cultivated biomass is increased, the nitrogen-fixing ability of the inoculum after inoculation is improved, and the maintenance cost is reduced; by adding hydrogen peroxide, the oxidative stress to which the biomass is subjected in the wild environment is simulated, the resistance of the obtained biomass is further improved, and the problem of functional degradation caused by artificial cultivation is solved.

[0029] 4. The present invention dries the algae biomass together with the solid matrix used for cultivation in situ and prepares the inoculum, which retains the extracellular secretions and residual nutrients of the artificial biomass with the maximum efficiency, and at the same time utilizes the characteristics of the biodegradable matrix to improve the water retention capacity of the inoculum, and improves the stability and water retention capacity of the surface soil in the inoculated area at the initial stage of inoculation. By adding auxiliary materials to the inoculum, the stability and water retention capacity of the surface soil in the inoculated area at the initial stage of inoculation are further improved, wherein soybean fiber, bentonite, sodium octenyl succinate starch, hydroxymethyl cellulose, and sodium alginate are used as both adhesives and water retaining agents, especially sodium alginate, which contacts divalent metal ions such as calcium and magnesium in the surface soil after inoculation, and can form a protective layer to slow down water evaporation and improve the water retention capacity of the surface soil; ascorbic acid and ascorbic acid esters are used as antioxidants to increase the shelf life of the inoculum; activated carbon powder is used as a shading agent, which is adsorbed on microbial cells such as algae, and can reduce the light stress received by algae cells in the initial stage of inoculation, so that the algae can grow better.

[0030] 5. When the inoculum of the present invention is inoculated, the surface soil of the inoculation area is impacted by the large droplets formed by spraying, so that the surface soil and the inoculum are fully mixed, which promotes the diffusion of the filamentous algae in the inoculum in the structure formed by the surface soil particles. After inoculation, water maintenance is performed to promote the movement of filamentous algae, accelerate its wrapping and adhesion to soil particles, and increase the formation rate of the crust structure. At the same time, by reducing the amount of water applied, the water stress impact on the biomass after being inoculated into the field environment is reduced, further improving the colonization success rate and reducing the maintenance cost.

[0031] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the relative abundance of Microcoleus, Oscillatoria, and Pseudoclones in the total algae biomass in the naturally formed algae crust and the biomass obtained after artificial cultivation and resistance training;

[0033] Figure 2 is the relative abundance of Microcoleus, Oscillatoria, and Pseudocloma in the total algal biomass in the naturally formed algal crust and the artificial algal crust after 32 days of inoculation;

[0034] Figure 3 It is a comparison of the total biomass and the algae biomass per unit of liquid culture medium used for artificial cultivation and resistance training;

[0035] Figure 4 It is a comparison of the chlorophyll a content in the naturally formed algae crust and the artificial algae crust after 32 days of inoculation;

[0036] Figure 5 It is a comparison of the content of extracellular secretions in naturally formed algae crusts and artificial algae crusts after 32 days of inoculation;

[0037] Figure 6 It is a comparison of the total nitrogen content in naturally formed algae crusts and artificial algae crusts after 32 days of inoculation;

[0038] Figure 7 It is a comparison of the penetration pressure of naturally formed algae crust and artificial algae crust after 32 days of inoculation;

[0039] Figure 8 It is the result of evaporation rate of naturally formed algae crust and artificial algae crust after 32 days of inoculation. DETAILED DESCRIPTION

[0040] Example 1

[0041] This embodiment is a method for desertification land restoration based on artificial algae crust, denoted as A, and the method comprises the following steps:

[0042] S1. Screening and culture

[0043] S101. Collect well-developed dry algae crusts from the Gurbantunggut Desert, and break the algae crusts into pieces that can pass through a sieve with an aperture of 3 mm by knocking and rolling.

[0044] S102. Place the broken pieces of crust at intervals of 5 cm on a hydrophilic nylon filter membrane with a pore size of 0.22 μm and a 5 cm thick hydrophilic melamine sponge at the bottom, and place them in a plastic tray with a depth of 10 cm. Use pure water to moisten the melamine sponge and the filter membrane. After the crusted pieces are moistened, continue to add water to the tray until the water depth reaches 3 cm. Place the tray in a temperature of 25 ± 2 ° C, relative humidity of 90% ± 5%, and photosynthetically active radiation of 80 ± 10 μE·m -2 ·s -1 Screening and culture were carried out in a clean environment.

[0045] S103. After 3 days of screening and culture, obvious green filamentous colonies appeared on and around some crust fragments. Through microscopic observation and sequencing analysis, it was found that the main species in the green filamentous colonies was Microcoleus with sheaths, and it also contained algae microorganisms such as Oscillatoria and Pseudobranchium. The above green filamentous colonies were collected.

[0046] S2. Artificial culture

[0047] S201. Spread a layer of natural cellulose paper on a 2 mm thick melamine sponge that occupies the bottom of the tray and completely covers the sponge. Use 500 mL of full-component BG11 liquid medium to soak the paper and sponge but not submerge the paper. Then spread the green filamentous colonies obtained in S1 evenly on the surface of the paper. Place the above tray in a temperature of 25 ± 2 °C, relative humidity of 70% ± 5%, and photosynthetically active radiation of 100 ± 10 μE·m -2 ·s -1 The paper was kept moist by spraying pure water evenly on the paper surface during the cultivation process. After 7 days of cultivation, it can be seen that the green colonies have completely covered the paper surface and have increased significantly in thickness.

[0048] S202: Collect the biomass on the paper surface, divide it into 5 equal parts and spread it on 5 trays containing sponges and paper soaked with BG11 liquid culture medium as described in S201. Continue to culture for 7 days under the same conditions. At this time, the biomass on the paper reaches 64.3 g·m -2 , this is the second stage of cultivation.

[0049] S3. Artificial resistance training

[0050] S301. After the artificial cultivation is completed, the nitrogen concentration of the culture medium in the tray is found to be 35.4% of the initial value. At this time, resistance training is started to increase the photosynthetically active radiation to 300±20μE·m -2 ·s -1 , and stop replenishing water to allow the paper in the tray and the biomass on it to gradually dry for 24 hours until they are completely dehydrated.

[0051] S302, spraying pure water on the completely dehydrated paper with biomass to make the surface biomass completely wet, and spraying 0.1% hydrogen peroxide aqueous solution to keep the biomass wet for 24 hours, and then increasing the photosynthetically active radiation to 500±20μE·m -2 ·s -1 , raise the temperature to 28 °C and repeat the drying process.

[0052] S303, repeat the above drying and rehydration process for 4 more times (5 times in total), and add 5W·m to the light source during the third drying and rehydration. -2 The light intensity was increased by 300 μE·m each time from the third drying and rehydration. -2 ·s -1 , the temperature increased by 3°C. After the fifth drying process, the nitrogen concentration in the paper was found to have dropped to 1.2% of the initial value. At this time, the paper and the biomass on it were removed and weighed. By comparing the weight of the paper without biomass and the paper with biomass, the total biomass on the paper was found to be 104.2 g·m -2 , the proportion of algal biomass in the total biomass was estimated to be 74.9% by chlorophyll a content.

[0053] S4. Preparation of artificial algae crust inoculum

[0054] The paper with biomass is processed into 3 mm square fragments by using a paper shredder, auxiliary materials are added to the fragments, and a three-dimensional mixer is used to mix them evenly to prepare artificial algae crust inoculum, in which soybean fiber powder (800 mesh), activated carbon powder (3000 mesh), ascorbic acid powder and sodium alginate powder (2000 mesh) account for 3.5%, 1.4%, 0.14% and 0.7% of the total weight of the inoculum respectively, and the biomass accounts for 70% of the total weight of the inoculum. After preparation, the inoculum is placed in an aluminum-plastic sealed bag and sealed for storage at room temperature.

[0055] S5. Inoculation and maintenance

[0056] S501. Take out the artificial algae crust inoculum stored for 3 months, mix it with tap water at a ratio of 1:50, stir it evenly, and use a slurry nozzle (droplet size is about 6 mm) to spray evenly on the surface of bare sand collected from the Gurbantunggut Desert in a square tray with a depth of 10 cm and a size of 1×1 m for inoculation, so that the algae biomass density on the sand surface is 7.6 g·m -2 During inoculation, the distance between the liquid outlet and the sand surface is controlled so that the liquid droplets can splash the surface sand. After inoculation, the above tray is immediately placed outdoors in an open and unobstructed environment.

[0057] S502: On the 2nd, 5th, 12th and 30th days after inoculation, spray 2 kg m2 of the inoculated tray evenly onto the sand surface. -2 , 2kg·m -2 , 1kg·m -2 , 0.5kg·m -2 The artificial algal crusts formed on the sand surface in the trays were analyzed on day 32.

[0058] Comparative Example 1

[0059] The blank control, which only included the tray containing bare sand and the application of water in step S5 of Example 1, was denoted as CK.

[0060] Comparative Example 2

[0061] The microbial community screened from the crust was not used, that is, step S1 in Example 1 was not performed, and a single artificially cultured Microcoleus biomass separated and purified was used instead of the green filamentous colonies used in S2. The remaining steps and the proportions of the materials used were the same as in Example 1, and were recorded as B1.

[0062] Comparative Example 3

[0063] No artificial resistance training is performed, that is, step S3 in Example 1 is not performed, and the paper with artificially cultured biomass obtained in S2 is directly used for drying and then S4 is performed to prepare artificial algae crust inoculum. The remaining steps and the proportion of materials used are the same as in Example 1, which is recorded as B2.

[0064] Comparative Example 4

[0065] The terrestrial non-submerged culture system is not used, that is, the artificial culture and artificial resistance training of S2 and S3 in Example 1 are not included, and the submerged culture method is used, which is recorded as B3. The specific culture method is:

[0066] Use a 500mL BG 11 The isolated green filamentous colonies were cultured in a conical flask containing liquid culture medium. 3 ·h -1Air was aerated at a rate of 100 ℃ and 150 ℃. The biomass was collected from the 500 mL conical flask by centrifugation and divided into 5 equal parts and added into 5 conical flasks containing 500 mL BG11 liquid culture medium for second-stage culture. 3 ·h -1 Air aeration is performed at a rate of, and the other culture conditions are the same as those in Example 1; the harvested biomass is dried and then subjected to S4 to prepare an artificial algae crust inoculum; the other steps and the proportions of the materials used are the same as those in Example 1.

[0067] Comparative Example 5

[0068] Compared with Example 1, the auxiliary materials in step S4 do not include soybean fiber and sodium alginate powder, and the remaining steps and the proportions of the materials used are the same as those in Example 1, which is recorded as B4.

[0069] Comparative Example 6

[0070] Compared with Example 1, the auxiliary material in step S4 does not include activated carbon powder, and the remaining steps and the proportions of the materials used are the same as those in Example 1, which is recorded as B5.

[0071] Comparative Example 7

[0072] Compared with Example 1, in step S4, the preparation of the artificial algae crust inoculum does not include a solid matrix, that is, after the algae biomass on the paper is separated, the paper is discarded; the remaining steps and the proportion of materials used are the same as in Example 1, denoted as B6.

[0073] Comparative Example 8

[0074] Compared with Example 1, in step S5, after the inoculum is directly and evenly applied to the surface of the area to be repaired, water is immediately applied on the bare sand surface to which the inoculum has been applied by spraying atomized tap water at a weight ratio of 1:50 to the inoculum (without splashing effect); the remaining steps and the material ratios used are the same as in Example 1, recorded as B7.

[0075] Comparative Example 9

[0076] Compared with Example 1, no subsequent maintenance was performed after inoculation in step S5, and analysis was performed only after 32 days, which was recorded as B8.

[0077] The artificial algae crust formed on the sand surface in Example 1 and Comparative Examples 1 to 9 was analyzed, and the analysis items included: relative abundance of algae species, chlorophyll a (representing the biomass of surviving algae), extracellular secretions (indicating the nature of the crust), total nitrogen (indicating the nitrogen fixation ability), crust penetration resistance (crust stability), and crust drying time (water retention capacity). The results are as follows:

[0078] Figure 1It is the relative abundance of Microcoleus, Oscillatoria, and Pseudoclones in the total algae biomass in the naturally formed algae crust and the biomass obtained after artificial cultivation and resistance training, where S represents the naturally formed algae crust. Figure 1 It can be seen that the distribution characteristics of the main algae species in the biomass obtained by cultivation in Example 1 are only slightly different from the algae crust naturally formed in the wild, but do not affect the ranking of the main algae species; Comparative Example 2 uses a single species of sheathed Microcoleus for cultivation, and the algae in the obtained biomass are only sheathed Microcoleus; Comparative Example 3 shows that the artificial resistance training process causes a slight difference in the species structure, but does not affect the ranking of the main algae species; Comparative Example 4 shows that the use of the traditional aquatic immersion culture method not only significantly changes the species structure of the cultured biomass relative to the natural crust in the wild, but also significantly reduces the relative abundance of Pseudobranched Algae with nitrogen fixation ability.

[0079] Figure 2 is the relative abundance of Microcoleus, Oscillatoria, and Pseudoclones in the total algal biomass in the naturally formed algal crust and the artificial algal crust after 32 days of inoculation, where S represents the naturally formed algal crust. Figure 2 It can be seen that the distribution of the main algae species in the artificial algae crust obtained in Example 1 is most similar to the algae crust formed naturally in the wild.

[0080] Figure 3 It is a comparison of the total biomass and algae biomass corresponding to the unit liquid culture medium used for artificial cultivation and resistance training. Figure 3 It can be seen that when the starting biomass from the same source is used, the biomass obtained by the artificial cultivation method of Example 1 per unit volume of the same liquid culture medium is more than 4 times higher than that of the traditional aquatic immersion cultivation method in Comparative Example 4; and compared with the single sheathed Microcoleus as the starting biomass in Comparative Example 2, there is no significant difference in the algae biomass.

[0081] Figure 4 The chlorophyll a content in the naturally formed algae crust is compared with that in the artificial algae crust after 32 days of inoculation, where S represents the naturally formed algae crust. Figure 4 It can be seen that the chlorophyll a content of the artificial algae crust obtained in Example 1 is not significantly different from that of the algae crust naturally formed in the wild. A high chlorophyll a content means that the algae biomass content in the crust is high and the colonization survival rate after inoculation is high. The chlorophyll a content in the artificial crusts of each comparative example is decreased to varying degrees compared with the algae crust naturally formed in the wild.

[0082] Figure 5 It is a comparison of the content of extracellular secretions in naturally formed algae crusts and artificial algae crusts after 32 days of inoculation, where S represents naturally formed algae crusts. Figure 5It can be seen that the content of extracellular secretions of the artificial algae crust obtained in Example 1 is higher than that of the algae crust naturally formed in the wild and other comparative examples, which is conducive to the adhesion of soil particles to form a crust structure, playing the role of a water retaining agent and improving soil quality.

[0083] Figure 6 It is a comparison of the total nitrogen content in naturally formed algae crusts and artificial algae crusts after 32 days of inoculation, where S represents naturally formed algae crusts. Figure 6 It can be seen that the total nitrogen content of the artificial algae crust obtained in Example 1 is slightly lower than that of the algae crust naturally formed in the wild, and the other comparative examples are all reduced to varying degrees compared with Example 1.

[0084] Figure 7 It is the penetration pressure comparison between the naturally formed algae crust and the artificial algae crust after 32 days of inoculation, where S represents the naturally formed algae crust. Figure 7 It can be seen that the penetration pressure of the artificial algae crust obtained in Example 1 is higher than that of the algae crust naturally formed in the wild, and is also higher than all the comparative examples. The higher the penetration pressure, the greater the structural strength of the biological soil crust, and the better the surface stability and erosion resistance.

[0085] Under the same environmental conditions (30°C, relative humidity 60%, incident radiation energy 100W·m -2 ) to transform the 25cm naturally formed in the Gurbantunggut Desert 2 Algae crust and 10 cm sandy soil below it and 25 cm sandy soil after 32 days of inoculation of the present invention 2 The artificial algae crust and the 10 cm sand below it were dried to 5% moisture content after reaching the maximum water retention capacity, and the evaporation rate was calculated. The results are as follows: Figure 8 As shown in FIG. 1 , where S represents naturally formed algae crust. Figure 8 It can be seen that the artificial algae crust obtained by the present invention has a lower evaporation rate than the algae crust naturally formed in the wild and has a stronger water retention capacity.

[0086] In summary, the method of using artificial algae crust to repair desertified land can produce an artificial algae crust on the surface of bare sand within 32 days, which has the same main algae species structure as the algae crust naturally formed in the wild, and the algae biomass, extracellular secretion content, total nitrogen content, strength, and water retention performance are not inferior to or higher than the algae crust naturally formed in the wild.

[0087] Example 2

[0088] This embodiment is a method for desertification land restoration based on artificial algae crust, which was carried out in the Gurbantunggut Desert in July 24. The method includes the following steps:

[0089] S1. Screening and culture

[0090] S101. Collect well-developed dry algae crusts from the Gurbantunggut Desert, and break the algae crusts into pieces that can pass through a sieve with a pore size of 2 mm by knocking and rolling.

[0091] S102. Place the broken pieces of crust at intervals of 5 cm on a 5 cm thick hydrophilic polyester non-woven fabric in a 10 cm deep plastic tray. Wet the non-woven fabric with pure water. After the crusted pieces are wetted, continue to add water to the tray until the water depth reaches 4 cm. Place the tray in a temperature of 15 ± 2 ° C, relative humidity of 85% ± 5%, and photosynthetically active radiation of 200 ± 10 μE·m -2 ·s -1 Screening and culture were carried out in a clean environment.

[0092] S103. After 5 days of screening and culture, obvious green filamentous colonies appeared on and around some crust fragments. Through microscopic observation and sequencing analysis, it was found that the main species in the green filamentous colonies was Microcoleus with sheaths, and it also contained algae microorganisms such as Oscillatoria and Pseudobranchium. The above green filamentous colonies were collected.

[0093] S2. Artificial culture

[0094] S201. Spread two layers of newsprint on a 5 mm thick polyester nonwoven fabric that occupies the entire bottom of the tray and completely cover the nonwoven fabric. Use full-component BBM liquid medium to soak the paper and nonwoven fabric but not submerge the paper. Then evenly apply the green filamentous colonies obtained in S1 on the surface of the paper. Place the above tray in a temperature of 25 ± 8 °C, relative humidity of 60% ± 5%, and photosynthetically active radiation of 200 ± 10 μE·m -2 ·s -1 The paper was kept moist by spraying pure water evenly on the paper surface during the cultivation process. After 7 days of cultivation, it was found that the green colonies had completely covered the paper surface and had a significant increase in thickness.

[0095] S202: Collect the biomass on the paper surface, divide it into 5 equal parts and spread it on 5 trays containing sponges and paper soaked with BBM liquid culture medium as described in S201, and continue to culture for 7 days under the same conditions. At this time, the biomass on the paper reaches 52.6 g·m -2 .

[0096] S203, repeat the above steps S201 and S202 twice, and obtain a biomass on paper of 76 g·m -2 .

[0097] S3. Artificial resistance training

[0098] S301. After the artificial cultivation is completed, the nitrogen concentration of the culture medium in the tray is found to be 21.5% of the initial value. At this time, resistance training is started to increase the photosynthetically active radiation to 400±20μE·m -2 ·s -1 , and stop replenishing water to allow the paper in the tray and the biomass on it to gradually dry until they are completely dehydrated after 8 hours.

[0099] S302. Increase photosynthetically active radiation to 600±20μE·m -2 ·s -1 , the temperature was raised to 32°C and the drying process was repeated, and then the completely dehydrated paper with biomass was hydrated by spraying pure water to completely wet the biomass on its surface.

[0100] S303, repeat the above drying and rehydration process for 4 more times (5 times in total), and increase the light intensity by 400 μE·m each time starting from the third drying and rehydration. -2 ·s -1 , the temperature increased by 4°C. After the fifth drying process, the nitrogen concentration in the paper was found to have dropped to 0.4% of the initial value. At this time, the paper and the biomass on it were taken off and weighed. By comparing the weight of the paper without biomass and the paper with biomass, the total biomass on the paper was found to be 118.9 g·m -2 , the proportion of algal biomass in the total biomass was estimated to be 82.1% by chlorophyll a content.

[0101] S4. Preparation of artificial algae crust inoculum

[0102] The above-mentioned paper with biomass was broken into 5 mm square fragments, auxiliary materials were added to the above fragments, and mixed evenly using a three-dimensional mixer to prepare artificial algae crust inoculum, in which bentonite (2000 mesh), activated carbon powder (3000 mesh), ascorbic acid ester powder, and sodium starch octenyl succinate accounted for 2%, 1.4%, 0.1%, and 3% of the total weight of the inoculum, respectively, and the biomass accounted for 70% of the total weight of the inoculum. After completion, the inoculum was sealed in an aluminum-plastic bag and stored at room temperature.

[0103] S5. Inoculation and maintenance

[0104] S501. Take out the artificial algae crust inoculum stored for one month, mix it with tap water at a ratio of 1:100, stir it evenly, and use a slurry nozzle (droplet size is about 3 mm) to spray it evenly on the bare sand surface on the leeward slope of the dune, so that the algae biomass density on the sand surface is 10 g·m -2 During inoculation, the distance between the liquid outlet and the sand surface is controlled so that the droplets can splash the surface sand.

[0105] S502: On the 3rd, 7th, 14th and 40th days after inoculation, 3 kg m -2 , 2kg·m -2 , 1kg·m -2 , 1kg·m -2 of water.

[0106] Example 3

[0107] This embodiment is a method for desertification land restoration based on artificial algae crust, which was carried out in the Gurbantunggut Desert in July 24. The method includes the following steps:

[0108] S1. Screening and culture

[0109] S101. Collect well-developed dry algae crusts from the Gurbantunggut Desert, and break the algae crusts into pieces that can pass through a sieve with an aperture of 3 mm by knocking and rolling.

[0110] S102. Place the broken crusted pieces at 5 cm intervals on a 5 cm thick hydrophilic polyester non-woven fabric in a 10 cm deep plastic tray. Wet the non-woven fabric with pure water. After the crusted pieces are wetted, continue to add water to the tray until the water depth reaches 4 cm. Place the tray in a temperature of 35 ± 2 ° C, relative humidity of 70% ± 5%, and photosynthetically active radiation of 30 ± 10 μE·m -2 ·s -1 Screening and culture were carried out in a clean environment.

[0111] S103. After 5 days of screening and culture, obvious green filamentous colonies appeared on and around some crust fragments. Through microscopic observation and sequencing analysis, it was found that the main species in the green filamentous colonies was Microcoleus with sheaths, and it also contained algae microorganisms such as Oscillatoria and Pseudobranchium. The above green filamentous colonies were collected.

[0112] S2. Artificial culture

[0113] A layer of newsprint was placed on both sides of a 1m×1m 50-mesh nylon filter placed vertically on the ground. A drip irrigation device was used to irrigate the filter at a flow rate of 1 L·h at intervals of 10 cm above the filter. -1 BG11 was dripped into the middle of the newsprint at a flow rate of 1.5 ℃. The device was placed in a greenhouse, where the temperature was controlled at 26 ± 8 °C and the relative humidity was 50% ± 5%. The green filamentous colonies obtained from S1 were evenly smeared on the surface of the paper. The photosynthetically active radiation on the surface of the paper was adjusted to 200 ± 10 μE·m through the sunshade device on the top of the greenhouse. -2 ·s -1The first stage of artificial cultivation was carried out, and the culture medium was dripped during the cultivation process. After 20 days of cultivation, it was seen that the green colonies had completely covered the surface of the paper and had a significant increase in thickness. At this time, the biomass on the paper reached 102.3 g·m -2 .

[0114] S3. Artificial resistance training

[0115] S301. After artificial cultivation, resistance training was started. First, pure water was used to replace 1 / 4 concentration of BG11 and the photosynthetically active radiation was increased to 400±20μE·m -2 ·s -1 The drip irrigation system was stopped after 1 day to allow the paper and the biomass on it to dry gradually until they were completely dehydrated after 16 hours.

[0116] S302. Increase photosynthetically active radiation to 600±20μE·m -2 ·s -1 , the temperature was raised to 32 °C and the drying process was repeated, and then the drip irrigation system was turned on to allow the completely dehydrated biomass to be fully moistened for 1 day.

[0117] S303, repeat the above drying and rehydration process for 4 more times (5 times in total), and increase the light intensity by 300 μE·m each time starting from the second drying and rehydration. -2 ·s -1 , the temperature was increased by 4°C, and tap water was used instead of BG11 medium. After the fifth drying process, the paper with the biomass on it was removed and weighed. By comparing the weight of the paper without biomass and the paper with biomass, the total biomass on the paper was found to be 121.3 g·m -2 , the proportion of algal biomass in the total biomass was estimated to be 71.9% by chlorophyll a content.

[0118] S4. Preparation of artificial algae crust inoculum

[0119] The above-mentioned paper with biomass was broken into 1 mm square fragments, auxiliary materials were added to the above fragments, and mixed evenly using a three-dimensional mixer to prepare artificial algae crust inoculum, in which the auxiliary materials, sodium octenyl succinate starch, activated carbon powder (3000 mesh), ascorbic acid powder, hydroxymethyl cellulose, and sodium alginate accounted for 1%, 1.4%, 0.1%, 1%, and 1% of the total weight of the inoculum, respectively, and the biomass accounted for 65% of the total weight of the inoculum. After completion, the paper was placed in a light-proof plastic sealed barrel and sealed at room temperature.

[0120] S5. Inoculation and maintenance

[0121] S501. Take out the artificial algae crust inoculum stored for one month, mix it with tap water at a ratio of 1:5, stir it evenly, and use a slurry nozzle (droplet size is about 5 mm) to spray it evenly on the ground surface of the leeward slope of the sand dune where the crust is destroyed by trampling, so that the algae biomass density on the sand surface is 10 g·m -2 During inoculation, the distance between the liquid outlet and the sand surface is controlled so that the droplets can splash the surface sand.

[0122] S502: On the 2nd, 6th, 10th and 35th days after inoculation, 2.5 kg·m -2 , 1kg·m -2 , 0.5kg·m -2 , 1kg·m -2 of water.

[0123] The present invention can obtain artificial algae crusts that are highly similar to the naturally formed algae crusts and have nitrogen-fixing functions by screening species from natural algae crusts. Compared with existing crust algae cultivation technology, the present invention has a higher output rate of algae biomass per unit culture medium volume, and does not change the species structure of the main algae during the co-cultivation of multiple species. The artificial resistance training method in the present invention significantly improves the colonization survival rate of the algae biomass in the inoculum after inoculation and the nitrogen-fixing ability of the crust, and further improves the colonization survival rate of the algae biomass, the content of extracellular secretions, the nitrogen-fixing ability, the strength and the water-retention capacity of the artificial algae crusts by adding a variety of auxiliary materials. In addition, the present invention uses natural or biodegradable auxiliary materials to assist the formation of algae crusts, which is an environmentally friendly, sustainable and efficient new type of biological control method for desertification.

[0124] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for desertification land restoration based on artificial algae crust, characterized in that: The following steps are involved: S1. Screening and culture The algae crusts collected from the wild were broken into 2-3 mm pieces and spread on the surface of a solid matrix moistened with liquid culture medium for screening and culture. The photosynthetically active radiation was 20-500 μE·m -2 ·s -1 , the culture temperature is 10-40°C, the relative humidity is 50-95%, the culture time is 1-5 days, and green filamentous colonies are obtained; S2. Artificial culture The green filamentous colonies obtained in S1 were placed in a terrestrial non-submerged culture system. The green filamentous colonies attached to the surface of the solid substrate moistened by the liquid culture medium and grew inside, but were not immersed in the liquid culture medium. -2 ·s -1 , the temperature is 10-40℃, the relative humidity is 25-75%, and the biomass on the surface and inside of the solid matrix is ​​not less than 20g·m -2 ; S3. Artificial resistance training The artificially cultured biomass obtained from S2 is collected after artificial resistance training in situ; The artificial resistance training methods include: water shortage treatment, changing the culture temperature, changing the light intensity and spectrum composition, reducing the nitrogen concentration in the liquid culture medium, and adding hydrogen peroxide to the liquid culture medium; S4. Preparation of artificial algae crust inoculum After the artificial resistance-trained biomass obtained in S3 is dried until it is completely dehydrated, the treated biomass together with the attached solid matrix are sheared into fragments with a size of 1 to 5 mm, and auxiliary materials are added to prepare an artificial algae crust inoculum, wherein the proportion of the biomass to the total weight of the artificial algae crust inoculum is 40% to 80%; S5. Inoculation and maintenance The artificial algae crust inoculum obtained in S4 is mixed with water in a weight ratio of 1:5 to 1:100, stirred evenly, and then sprayed onto the surface of the area to be repaired, and maintained until the algae crust is formed.

2. The method according to claim 1, characterized in that The green filamentous colonies described in S1 include one or more of Microcoelenterate, Root Algae, Pseudobranch Algae, Monophyll, Anabaena, Nostoc, Sheath Algae, Thin Sheath Algae, Oscillatoria, and Tetraselena; the proportion of algae dry biomass in the green filamentous colonies to the total dry biomass of the colonies is not less than 50%, and the proportion of the dry biomass of Microcoelenterate or Oscillatoria to the total dry biomass of the colonies is not less than 20%.

3. The method according to claim 1, characterized in that The solid matrix for screening and culture described in S1 is one or more of a filter membrane, non-woven fabric, woven fabric, sponge, and paper that has the ability to absorb and retain water and is biodegradable, and the liquid culture medium is pure water.

4. The method according to claim 1, characterized in that: The solid matrix for artificial culture in S2 is one or more of a filter membrane, a non-woven fabric, a woven fabric, a sponge, and paper that has the ability to absorb and retain water and is biodegradable, and the liquid culture medium is a common algae liquid culture medium.

5. The method according to claim 1, characterized in that The water shortage treatment in S3 is to dry the biomass in situ and then add water in situ, and the drying time is 6 to 48 hours; The culture temperature is changed to a range of 10 to 40°C; The light intensity is changed in the range of 100 to 2000 μE·m -2 ·s -1 ; The changing of the spectral composition includes increasing the proportion of blue light with a wavelength of 400-500nm or adding one or more of ultraviolet light with a wavelength of 200-400nm, wherein the proportion of ultraviolet light does not exceed 5% of the total light energy; The nitrogen concentration in the liquid culture is changed as follows: sufficient nitrogen is maintained in the early stage of artificial culture, and the nitrogen concentration begins to be gradually reduced 10 to 20 days before the end of artificial culture, and the nitrogen concentration in the liquid culture medium is reduced to less than 5% of the initial concentration 7 to 10 days before the end of artificial culture; The concentration of hydrogen peroxide added to the liquid culture medium is 0.1% to 5%.

6. The method according to claim 1, characterized in that The process of artificial resistance training described in S3 can be single, multiple or continuous, and any change in conditions is performed in a gradual manner.

7. The method according to claim 1, characterized in that The auxiliary materials added in S4 include one or more of soybean fiber, bentonite, ascorbic acid, ascorbic acid ester, activated carbon powder, sodium starch octenylsuccinate, hydroxymethyl cellulose, and sodium alginate, and all of them are in powder form.

8. The method according to claim 1, characterized in that The proportion of the auxiliary materials described in S4 to the total weight of the artificial algae crust inoculum is: 0.1% to 5% soybean fiber, 0.1% to 2% bentonite, 0.05% to 0.5% ascorbic acid, 0.05% to 0.5% ascorbic acid ester, 0.1% to 2% activated carbon powder, 0.1% to 5% sodium starch octenylsuccinate, 0.1% to 5% hydroxymethyl cellulose, and 0.1% to 5% sodium alginate.

9. The method according to claim 1, characterized in that: The amount of artificial algae crust inoculant used in S5 is based on the ratio of algae biomass in the inoculant to the area to be repaired, which is 1 to 20 g·m -2 Calculation: The spray droplet size is 1 to 6 mm, producing a splashing effect.

10. The method according to claim 1, characterized in that The maintenance method described in S5 is: spray 2-3 kg·m on the surface of the inoculated area on the 1st to 3rd day, 4th to 7th day, 10th to 15th day, and 30th to 45th day after inoculation. -2 , 1~2kg·m -2 , 0.5~1kg·m -2 , 0.5~1kg·m -2 of water.

Images