AU2021100375A4 - Technique for ecologically restoring engineering-damaged surface by using moss crust - Google Patents

Abstract

The present disclosure provides a technique for ecologically restoring an engineering-damaged surface by using a moss crust. The technique includes: selecting a naturally developed and well-growing moss crust; crushing the moss crust by using a plant crusher, and passing through a 80-mesh sieve to obtain stem and leaf fragments of the moss crust; adding the stem and leaf fragments of the moss crust together with other auxiliary materials according to a certain ratio into a mixing tank, and mixing evenly to obtain a slurry; and spraying the slurry to a slope, and carrying out corresponding maintenance to achieve ecological restoration of the engineering-damaged surface. The present sprays the prepared slurry to the engineering-damaged surface and carries out appropriate maintenance measures to achieve rapid restoration by using the moss crust. The technique has the advantages of low cost, quick effect and wide application range, finds a new way for erosion control and ecological restoration, and has a very broad industrialization prospect. 11 DRAWINGS Slurry preparation Nutrient Wood Binder Moss Soil Water solution fiber 20 6 kg/m3 crust 116 500 500 L/m3 kg/m3 24 kg/m3 kg/m3 L/m3 Spraying 1 Follow-up maintenance FIG. 1 Page 1 of4

Description

DRAWINGS

Slurry preparation

Nutrient Wood Binder Moss Soil Water solution fiber 20 6 kg/m 3 crust 116 500 500 L/m 3 kg/m 3 24 kg/m3 kg/m 3 L/m3

Spraying

1 Follow-up maintenance

FIG. 1

Page 1 of4

TECHNIQUE FOR ECOLOGICALLY RESTORING ENGINEERING-DAMAGED SURFACE BY USING MOSS CRUST TECHNICAL FIELD The present disclosure belongs to the ecological field, and specifically relates to a technique for ecologically restoring an engineering-damaged surface by using a moss crust. BACKGROUND Engineering-damaged surface refers to a surface on the earth where the original natural environment is damaged due to various engineering measures implemented by humans in production and life. It may be a flat or sloped surface. The engineering damage is quite serious to the surrounding environment, such as change the original topography and land cover, reduce soil stability and fertility, change the groundwater level, the surface heat and humidity environment, trigger local micro-climate changes, and increase the risk of soil erosion. General measures to prevent soil erosion mainly include engineering measures and plant measures. The engineering measures include mortared stone slope protection, cement mortar plastered slope protection, sprayed concrete and shotcrete-bolt support, which are time-consuming, costly, short in service life, and will also cause damage to the surrounding environment. The plant measures are the first choice to fundamentally solve various environmental problems and restore the damaged ecological environment. Biocrusts are an organic complex composed of diminutive cyanobacteria, algae, fungi, moss and lichen species on the soil surface, which had an important function in dryland ecosystems. As a pioneer colonizing community, biocrusts are widely found in arid and semi-arid areas, and have important effects on retention of soil moisture, improvements to nutrient cycling, increased soil stability, and the reduction of water/wind erosion hazards. Moss crusts are the final stage of biological crust succession. They have higher photosynthesis rates, exopolysaccharide production, biological diversity, increased soil water contents, and nutrient contents, which resulted in the moss crust having had stronger resistance to adversity factors and have a positive effect on the prevention and control of soil erosion. SUMMARY Due to the physical damage, the original features and ecological environment of the engineering-damaged surface have undergone major changes, and the site conditions have deteriorated seriously. The engineering-damaged surface is highly unstable both in engineering and ecology. If no ecological restoration is completed in a short period of time, various problems may arise, such as soil erosion, invasion of alien plants, collapse, and even landslide accidents. Therefore, a technique for quickly restoring the ecological environment of the engineering-damaged surface is needed. The current control measures mainly include engineering measures and traditional plant measures. Although these two measures have a certain effect on the prevention of soil erosion, they have not fundamentally solved the problem. The engineering measures include mortared stone slope protection, cement mortar plastered slope protection, sprayed concrete and shotcrete-bolt support. They are time-consuming, costly, short in service life, and will cause damage to the surrounding environment. They will change the surface heat and humidity environment, trigger local micro-climate changes, and cause other environmental problems. The traditional plant measures require good site conditions, have high economic costs, and take a long time to take effect. On some steep slopes with broken terrain and loose soil, the traditional plant measures cannot prevent soil erosion, and may cause landslides and aggravate soil erosion due to plant gravity and other reasons. In view of this, the present disclosure provides a rapid restoration method by using a moss crust. The method includes slurry preparation, spraying and follow-up maintenance. The method has the advantages of low cost, quick effect and wide application range, finds a new way for erosion control and ecological restoration, and has a very broad industrialization prospect. The first objective of the present disclosure is to provide a method for ecologically restoring an engineering-damaged surface by using a moss crust. The method includes the following steps: 1) slurry preparation, 2) spraying and 3) follow-up maintenance. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, a slurry is prepared from the following raw materials: a substrate soil, stem and leaf fragments of a moss crust, a Hoagland nutrient solution, a wood fiber, a binder and water. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, an amount of the raw materials of the slurry is as follows: 116 kg/m3 of substrate soil, 24 kg/m3 of stem and leaf fragments of the moss crust, 500 L/m3 of Hoagland nutrient solution, 20 kg/m3 of wood fiber, 6 kg/m3 of binder and 500 L/m3 of water. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, a dominant species of the moss crust is Didymodon vinealis (Brid.) Zand.. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, the moss crust is crushed by a plant crusher at 32,000 r/min. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, the crushed moss crust is passed through a sieve with a mesh number of less than 80.

Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, the spraying includes mixing the slurry evenly and then spraying the slurry to a slope. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, the slurry is sprayed at a rate of 200 m2 per cubic meters of the slope for about 10 min. Preferably, in the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure, the follow-up maintenance includes: covering by a shading net with a shading rate of 70%, watering to keep a moisture content of 15% to 25% in a soil surface, and applying a nutrient solution every 10 d. More preferably, the method for ecologically restoring an engineering-damaged surface by using a moss crust according to the present disclosure includes the following steps: 1) selecting a naturally developed and well-growing moss crust, and scooping out a 1 cm thick surface crust for further use; 2) drying the collected moss crust in the shade in a laboratory, removing impurities visible to the naked eye, then crushing the moss crust with a plant crusher, and passing the moss crust through an 80-mesh sieve; 3) adding prepared stem and leaf fragments of the moss crust and other raw materials into a mixing tank, mixing evenly, and spraying to the slope; 4) covering by a shading net with a shading rate of 70%, watering from time to time according to actual weather conditions to keep a moisture content of 15% to 25% in the soil surface, and applying a nutrient solution every 10 d; and 5) cultivating for 60 d continuously to achieve a moss crust coverage of more than 60% and a moss crust density of 48 plants/cm2 .

The present disclosure has at least the following advantages: 1. Years of experiments have shown that it is completely feasible to realize ecological restoration by using a biocrust in a short period of time by adopting various control methods. Compared with the traditional arbor, shrub and grass plant measures, the biocrust has the advantages of low cost and easy provenance collection, construction, transportation and maintenance. A subsequent embodiment will provide budget estimates of different measures, which will demonstrate that the construction cost of the moss crust is lower than other plant measures. 2. The method of the present disclosure takes effect quickly. Preliminary experiments have shown that in about 45-60 d, the coverage of an artificially cultivated biocrust reaches more than % to bring out efficient soil and water conservation. However, if shrub and grass are planted for ecological restoration, it takes at least one year; and it takes a longer time for forest and grass.

Therefore, it is more appropriate to use a rapidly cultivated moss crust to implement the ecological restoration of an engineering-damaged surface. 3. The method of the present disclosure has a wide application range, and the biocrust can grow well in many places with poor site conditions and harsh environments. The traditional measures of arbors, shrubs, grasses and vascular plants are often not suitable for stone slopes or high steep soil slopes with poor site conditions. As a pioneer colonizing plant in arid and semi-arid areas, biocrust has a variety of ecological functions and strong resistance to adversity, and finds a new way of slope management. The method of the present disclosure has low price, quick effect, wide application range and broad market space. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows a flowchart of a technique of the present disclosure. FIG. 2 shows steps of cultivating a moss crust according to an embodiment of the present disclosure. FIG. 3 shows a change of a moss crust coverage over time according to an embodiment of the present disclosure. FIG. 4 shows a change of a moss crust density over time according to an embodiment of the present disclosure. FIG. 5 shows a change of moss crust biomass over time according to an embodiment of the present disclosure. DETAILED DESCRIPTION FIG. 1 shows a flowchart of a technique in an embodiment of the present disclosure. The technical solutions of the present disclosure are described in further detail below with reference to the specific embodiments. It should be understood that the following embodiments are merely illustrative embodiments of the present disclosure, and are not intended to construct a limitation to the protection scope of the claims of the present disclosure. Embodiment 1 1. Materials and methods 1.1. Sample collection and preparation methods A moss crust sample was collected from a natural slope of Zhifanggou, Ansai County, Shaanxi Province, China (36°46'99"-36°52'44"N, 109°17'2"-109°18'50"E). The main vegetation in the sampling area is Populus simonii moench., Caraganakorshinskii kom. and Stipa bungeana trin. The coverage of the moss crust is more than 80%, and the average thickness of the moss crust is 11.45±0.51 mm (n=9). A moss crust with a thickness of 1 cm was scooped out with a spatula, put into a clean plastic bag, brought back and dried naturally in a laboratory. Impurities such as plant residues, soil blocks and stones that are visible to the naked eye were removed, and then the moss crust was crushed by a miniature plant sample crusher (FLB-100) for further use. An identification has shown that a dominant species of the tested moss crust is Didymodon vinealis (Brid.) Zand.. 1.2 Slurry preparation Two experimental factors, namely nutrient solution and shading rate, were considered in the experiment. The nutrient solution was Hoagland nutrient solution. The experimental factors and levels are shown in the table below: Table 1 Design of experimental factors and levels Level Nutrient solution Shading rate(%) 1 No 0 2 Yes 50 3 -- 70 4 -- 90 Note: "--" in the table means blank. A full factorial experiment was carried out on these two factors, as shown in the following design table: Table 2 Design of full factorial experiment of nutrient solution and shading rate Treatment Nutrient solution Shading rate(%) 1 No 0 2 No 50 3 No 70 4 No 90 5 Yes 0 6 Yes 50 7 Yes 70 8 Yes 90 According to a slurry preparation method, various raw materials required for spraying were sequentially added into a mixing tank, mixed evenly, and then evenly inoculated to each test plot by using a simple spraying integrated device. The area of each plot was 1 m x 1 m. In order to eliminate the influence of spatial differences on the test results, the plots in each treatment block were randomly distributed. Afterwards, according to the experimental design, shading nets with different shading rates were set up on a bracket to cover the plot. The size of the bracket was 1 m x 1 m x 0.2 m. 1.3 Spraying Stem and leaf fragments of the moss crust and auxiliary materials were evenly mixed according to an amount as follows: water (500 L/m 3) + Hoagland nutrient solution (500 L/m3 ) + wood fiber (20 kg/m 3) + binder (6 kg/m 3) + moss crust stem and leaf fragments (24 kg/m 3) + soil (116 kg/m 3), and sprayed to each plot.

After spraying, the nutrient solution was applied every 10 d, with an application rate of 2.1 L/m2 each time. The moisture content in a 0-5 cm soil surface was regularly monitored by using a soil moisture meter, TDR (TRIME-PIC032). According to the measured soil moisture content, the watering time was appropriately adjusted to ensure that the moisture content was 15-25%. 1.4 Measurement indicators and methods Starting from 30 d after spraying, the biological indicators of the moss crust were measured every 15 d, and the cultivation was over until the moss crust coverage did not change significantly. The coverage was measured by using Li Xinrong's sampling frame method, which adopted 2.5 cm x 2.5 cm grids. The plant density was measured by taking five squares with an area of 2.5 x 2.5 cm2 at equal distances on the diagonal of each plot, measuring the number of moss plants in the square, and finding an average value for each plot. Chlorophyll a was used to represent biomass. Specifically, the moss crust was collected by a circular hollow tube sampler with a diameter of 1.6 cm, and three samples with an area of 2.01 cm 2 and a thickness of 5 mm were collected from each plot. The samples were passed through a 0.1 mm sieve, rinsed with tap water to separate the moss crust from the soil, and washed with distilled water. Then the moss crust was dried and put in a mortar. A small amount of quartz sand, calcium carbonate and 3 ml of 95% ethanol were added to grind the moss crust into a homogenate. Then 5 mL of 95% ethanol was added, and the grinding was continued until the tissue became white. The homogenate was allowed to stand for 5 min, filtered into a 25 mL brown volumetric flask, and rinsed with a small amount of 95% ethanol for several times until there was no green in a filter paper and residue. Finally, the volume was determined with 95% ethanol, and the colorimetric determination of the pigment was performed with 95% ethanol as a blank. The absorbance was measured at 665 nm and 649 nm, and the concentration was calculated as follows: p = 13.95 x A665nm - 6.88 x A649nm; W =p x V x N/S In the equations: p represents a concentration of chlorophyll a (mg• L- 1); W represents a content of chlorophyll a ( g• cm-2); V represents a volume of an extract (mL); N represents a dilution factor; S represents a sampling area (cm 2 ) of the sample. 2. Results analysis (1) Appearance of moss crust As shown in FIG. 2, A represents the slurry to spray, B represents the spraying process, C represents a panoramic view of layout, and D represents a moss crust after 7 months of cultivation. The preparation and spraying of the mixed slurry, the cultivation of the moss crust and the moss crust after 7 months of cultivation show that the moss crust grew well and it is feasible to realize rapid cultivation of the moss crust in the field. (2) Dynamic changes in the moss crust coverage The moss crust coverage was measured at different time periods (as shown in FIG. 3), which shows that: Treatment 7 (nutrient solution + 70% shading) shown in Table 2 is the best practice for cultivation, and under high temperature conditions in summer, the moss crust coverage can reach more than 60% after 60 d of cultivation. (3) Dynamic changes in the moss crust density The moss crust density during the cultivation period changed with time, as shown in FIG. 3. As the cultivation time prolonged, the moss crust density increased significantly, and the moss crust density in Treatment 7 (nutrient solution + 70% shading) during the same period was significantly higher than that in other treatments. (4) Changes in the moss crust biomass By analyzing the content of chlorophyll a of different treatments (FIG. 4) at the end of the experiment, it can be seen that the moss crust biomass of Treatment 7 (nutrient solution + 70% shading) was significantly higher than that of other treatments (p<0.05), so it represented the best combination of factors to cultivate the moss crust. Therefore, it is feasible to carry out ecological restoration of an engineering-damaged surface by spraying the moss crust. The best formulation of the slurry to spray includes: water (500 L/m3)+ Hoagland nutrient solution (500 L/m 3) + wood fiber (20 kg/m 3) + binder (6 kg/m 3) + moss crust stem and leaf fragments (24 kg/m 3) + soil (116 kg/m 3). The follow-up maintenance includes: shading net (70%) + watering (moisture content 15% to 25%) + nutrient solution (10 d/time). Embodiment 2 This embodiment provides budget estimates for different measures, which shows that the construction cost of the moss crust is lower than other measures. For the biocrust method, refer to the method in Embodiment 1. The grass measure is illustrated with Cynodon dactylon (1.) Pers. as a typical demonstration. The grass measure includes: prepare a land on a slope in late spring and early summer, to remove rocks and construction waste on the slope; shovel a lawn of Cynodon dactylon (1.) Pers., wash soil at the root of the Cynodon dactylon (1.) Pers., divide the Cynodon dactylon (1.) Pers. into several individual plants, and soak seedlings in clean water; open about 3 cm deep holes according to a row spacing of 8 cm x 8 cm, four plants per hole; fill the holes with a doped base fertilizer, and cover with soil; and water thoroughly to keep the slope moist (see Table 2). The shrub measure is illustrated by taking Amorphafruticosa Linn. as an example. The shrub measure includes: prepare a land on a slope in late autumn, to remove rocks and construction waste on the slope; select branches of Amorpha fruticosa Linn. more than one year old after leaves of the Amorphafruticosa Linn. are deciduous, and cut the branches into small sections of about 20 cm with the lower end cut obliquely and the upper end cut flat; open holes according to a row spacing of 18 cm x 18 cm, two plants per hole; fill the hole with a doped base fertilizer, water, cover with soil, and step on the soil tightly to keep the soil moist (see Table 3). Table 1 Costs of 100 m 2 grass/shrub measures and 100 m2 of biocrusts Types of costs Grass measure Shrub Biocrust Amount saved by biocrust Amount saved by measure compared to grass measure biocrust compared to shrub measure Seedling/provenance cost 150.0 660.0 558.9 -408.9 101.1 Transportation cost 8.1 35.6 30.2 -22.1 5.5 Operating cost 1320.3 1411.5 712.5 607.8 699.1 Maintenance cost 300.0 300.0 200.0 100.0 100.0 Total (yuan) 1778.4 2407.2 1501.6 276.8 905.6

Table 2 shows a budget estimate of 100 m2 Cynodon dactylon (1.) Pers. treated by the method according to Embodiment 1 of the present disclosure. Table 2 Budget estimate of Cynodon dactylon (1.) Pers. Quota No.: Reference 08133 Project: Ccynodon dactylon (1.) Pers. Quota unit: 100 m2 Scope of work: turning soil, preparing the land, removing impurities, applying a base fertilizer, setting out, watering and cleaning. No. Item Unit Quantity Unit price (yuan) Total (yuan) First Direct cost 1105.34 (I) Basic direct cost 1089.00 1 Labor cost 1050.00 Labor Hour 105.0 10.00 1050.00 2 Material cost 39.00 Cynodon Plant 5000 0.03 150.00 dactylon Water m3 4 1.00 4.00 Organic fertilizer m3 3.5 10.00 35.00 (II) Other direct costs % 1.50 1089.00 16.34 Second Indirect cost % 5.50 1105.34 60.79 Third Corporate profits % 2.00 1166.13 23.32 Four Taxes % 11.00 1189.45 130.84 Total 1320.29

Table 3 shows a budget estimate of 100 m2 Amorphafruticosa Linn. treated by the method according to Embodiment 1 of the present disclosure. Table 3 Budget estimate of Amorphafruticosa Linn. Quota No.: Reference 08133 Project: AamorphafruticosaLinn. Quota unit: 100 m 2 Scope of work: turning soil, preparing the land, removing impurities, applying a base fertilizer, setting out, watering and cleaning. No. Item Unit Quantity Unit price (yuan) Total (yuan) First Direct cost 1246.72 (I) Basic direct cost 1228.30 1 Labor cost 560.00 Labor Hour 56.0 10.00 560.00 2 Material cost 668.30 Amorpha fruticosa Plant 1100 0.60 660.00 Water m3 2 1.00 2.00 3 1 Organic fertilizer m 0.63 10.00 6.30

(II) Other direct costs % 1.50 1228.30 18.42 Second Indirect cost % 5.50 1246.72 68.57 Third Corporate profits % 2.00 1246.72 24.93 Four Taxes % 11.00 1271.66 139.88 Total 1411.54

The above described are preferred implementations of the present disclosure. It should be noted that a person of ordinary skill in the art may further make several improvements and modifications without departing from the principle of the present disclosure, but such improvements and modifications should also be deemed as falling within the protection scope of the disclosure.

Claims (5)

1. What is claimed is: 1. A technique for ecologically restoring an engineering-damaged surface by using a moss crust, wherein the method comprises the following steps: 1) slurry preparation, 2) spraying and 3) follow-up maintenance; wherein a slurry is prepared from the following raw materials: a substrate soil, stem and leaf fragments of a moss crust, a Hoagland nutrient solution, a wood fiber, a binder and water; an amount of the raw materials of the slurry is as follows: 116 kg/m3 of substrate soil, 24 kg/m 3 of stem and leaf fragments of the moss crust, 500 L/m3 of Hoagland nutrient solution, 20 kg/m3 of wood fiber, 6 kg/m3 of binder and 500 L/m3 of water; the spraying is applied to a soil slope; the moss crust is crushed and then passed through an 80-mesh sieve; the follow-up maintenance comprises: covering by a shading net with a shading rate of 70%, watering to keep a moisture content of 15% to 25% in a soil surface, and applying a nutrient solution every 10 d.
2. 2. The method according to claim 1, wherein a dominant species of the moss crust is Didymodon vinealis (Brid.) Zand..
3. 3. The method according to claim 1, wherein the moss crust is crushed by a plant crusher at 32,000 r/min.
4. 4. The method according to claim 1, wherein the spraying comprises mixing the slurry evenly and then spraying the slurry to the slope; wherein the slurry is sprayed at a rate of 200 m2 per cubic meters of the slope for about 10 min.
5. 5. The method according to claims 1 to 4, wherein the method comprises the following steps: 1) selecting a naturally developed and well-growing moss crust, and scooping out a 1 cm thick surface crust for further use; 2) drying the collected moss crust in the shade in a laboratory, removing impurities visible to the naked eye, then crushing the moss crust with a plant crusher, and passing the moss crust through an 80-mesh sieve; 3) adding prepared stem and leaf fragments of the moss crust and other raw materials into a mixing tank, mixing evenly, and spraying to the slope; 4) covering by a shading net with a shading rate of 70%, watering from time to time according to actual weather conditions to keep a moisture content of 15% to 25% in the soil surface, and applying a nutrient solution every 10 d; and 5) cultivating for 60 d continuously to achieve a moss crust coverage of more than 60% and a moss crust density of 48 plants/cm2 .