A drought ecological restoration substrate based on regulation of root spatio-temporal succession and microenvironment improvement and a construction method thereof

Abstract

This invention discloses a drought-resistant ecological restoration substrate and its construction method based on root spatiotemporal succession regulation and microenvironment improvement. The substrate composition includes a substrate soil component, a vegetation community building component, and a rhizosphere microenvironment regulating component. Each cubic meter of substrate soil component contains 2.5–4.0 kg of the vegetation community building component and 4.5–8.0 kg of the rhizosphere microenvironment regulating component. The vegetation community building component includes pioneer herb seeds, transitional leguminous shrub and grass seeds, and top-grade deep-rooted tree and shrub seeds. This invention significantly improves root anchoring force. Actual measurements show that after adding the regulating component of this invention, the root depth of shrubs increases by more than 30% compared to conventional formulations, completely eliminating the risk of root slippage.

Description

Technical Field

[0001] This invention belongs to the field of ecological environment restoration technology, and in particular relates to a drought ecological restoration substrate and its construction method based on root spatiotemporal succession regulation and microenvironment improvement. Background Technology

[0002] In the ecological restoration of highway and railway slopes, hydroseeding technology is already very mature. Existing technologies typically use a universal formula consisting of soil, organic matter, fertilizer, water-retaining agent, binder, and mixed seeds. However, in practical engineering applications (especially in loess hilly areas and alkaline soil areas), this universal formula has the following unresolved drawbacks:

[0003] 1. The problem of vegetation community degradation (green for one year, yellow for three years): Current techniques often simply mix the seeds of grasses, shrubs, and trees. Because herbaceous plants (pioneer species) germinate quickly and have a strong ability to compete for water and nutrients, shrubs and trees (top apex species) die during the seedling stage due to failure to compete. A few years later, the herbaceous plants degenerate, while the deep-rooted woody plants fail to grow, and the slopes become bare again. Simply adjusting the seed species (such as adding elm trees) is a conventional method and cannot solve the problem of competition.

[0004] 2. The problems of substrate compaction and alkaline stress: The pH value of substrates such as loess soil often reaches above 8.5. Under high pH values, the effectiveness of conventional PAM binders is reduced; at the same time, trace elements such as phosphorus and iron in the soil are fixed, making it difficult for plants to absorb them. Conventional formulas that only add compound fertilizer cannot solve the problem of nutrient blockage due to alkalinity.

[0005] 3. Insufficient root penetration: On dry, hard soil slopes, if the substrate layer cannot provide a special root-promoting environment, plant roots will have difficulty penetrating the substrate layer and entering the original soil, causing the hydroseeding layer and the slope surface to form two separate layers, making it very easy for the entire plant to slide off. Summary of the Invention

[0006] In view of this, the present invention aims to propose a drought ecological restoration substrate and its construction method based on the regulation of root spatiotemporal succession and microenvironment improvement, so as to solve at least one technical problem in the background art.

[0007] This invention is no longer limited to the simple mixing of conventional components, but proposes a dual-effect regulation system of wood vinegar and gypsum combined with a spatiotemporal hierarchical planting strategy to solve the above problems from the two dimensions of chemical improvement and ecological succession.

[0008] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0009] A drought-prone ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement, wherein the substrate composition comprises a substrate soil component, a vegetation community building component, and a rhizosphere microenvironment regulating component; 2.5-4.0 kg of vegetation community building component and 4.5-8.0 kg of rhizosphere microenvironment regulating component are added to each cubic meter of substrate soil component;

[0010] The vegetation community building components include pioneer herb seeds, transitional leguminous shrub and grass seeds, and top deep-rooted tree and shrub seeds.

[0011] Furthermore, the mass fraction of the pioneer herb seeds is 15% to 25%, which is used to quickly cover the ground surface within 30 days after spraying;

[0012] Transitional leguminous shrubs and grasses, with a seed mass fraction of 45%–55%, are used to provide nitrogen source and reinforce intermediate soil within 1–3 years;

[0013] The weight fraction of top-grade deep-rooted tree and shrub seeds is 20% to 30%, and the seeds are selected from one or more of elm and apricot trees; they are used to form deep anchor roots after 3 years.

[0014] Furthermore, the pioneer herb seeds are selected from one or more of the following: ice grass, awnless brome, and crested wheatgrass;

[0015] The seeds of transitional leguminous shrubs and grasses are selected from one or more of alfalfa, alfalfa, purple locust, lespedeza, and caragana.

[0016] Top-quality deep-rooted tree and shrub seeds are selected from one or more of elm and apricot trees.

[0017] Furthermore, the matrix soil components include imported soil, organic soil, and reinforcing fibers, with a volume ratio of (9-11):(0.8-1.5):(0.3-0.6).

[0018] Furthermore, in the substrate soil components, the imported soil is sieved loam or loam with a pH value of 8.0 to 8.6; the organic soil is peat moss or well-rotted compost with an organic matter content of ≥30%; and the reinforcing fiber is plant fiber or polypropylene fiber with a length of 6 to 15 mm.

[0019] Furthermore, the pH-growth dual-effect regulator in the rhizosphere microenvironment regulating component is wood vinegar or a mixture of wood vinegar and superphosphate; the aggregate structure stabilizer includes high molecular weight polyacrylamide and gypsum; and the water-retaining agent is an acrylamide-acrylate copolymer crosslinker.

[0020] Furthermore, the microenvironment-regulating components, by mass percentage, include:

[0021] Wood vinegar: 15-25 parts;

[0022] Polyacrylamide: 10-15 parts;

[0023] Gypsum: 20-30 parts;

[0024] Water-retaining agent: 15-20 parts;

[0025] The remainder is compound fertilizer;

[0026] Preferably, the wood vinegar has a pH value of 2.5 to 3.5 and an organic acid content of ≥3%.

[0027] Preferably, the water-retaining agent is an acrylamide-acrylate copolymer crosslinker;

[0028] Preferably, the compound fertilizer has an N:P2O5:K2O ratio of 15:15:15.

[0029] A method for slope ecological restoration using the aforementioned drought-resistant ecological restoration matrix based on root spatiotemporal succession regulation and microenvironment improvement includes the following steps:

[0030] S1: Clean the slope surface and create horizontal micro-grooves on the slope surface;

[0031] S2: Lay the metal mesh and anchor it;

[0032] S3: If the vegetation community building component contains large seeds with a particle size greater than 5 mm, the large seeds are directly sown manually into the mesh of the metal mesh before hydroseeding.

[0033] S4: Mix the substrate soil components with the rhizosphere microenvironment conditioning components and the remaining seeds except for large seeds evenly to prepare a mud-like spraying material;

[0034] S5: Use a wet spraying machine to spray the hydroseeding material onto the slope, with a thickness of 8-12cm;

[0035] S6: Cover with non-woven fabric and water.

[0036] Furthermore, in step S4, the wood vinegar is added at the final stage of adding water and stirring, so as to utilize the in-situ reaction between the wood vinegar and gypsum to form a microporous structure.

[0037] Furthermore, the method is applicable to alkaline soil slopes in arid and semi-arid regions with a pH value greater than 8.0 and an annual rainfall of less than 500 mm.

[0038] Compared with existing technologies, the drought ecological restoration substrate and its construction method based on root spatiotemporal succession regulation and microenvironment improvement described in this invention have the following advantages:

[0039] (1) This invention solves the problem of competition between grasses and shrubs. This application achieves harmonious coexistence of grasses, shrubs, and trees by limiting the proportion of herbaceous plants and using wood vinegar to preferentially promote the root development of woody plants, thus avoiding later degradation. By precisely configuring the proportion of the three types of seeds, the competitiveness of pioneer herbaceous plants is limited, the backbone role of transitional shrubs and grasses is highlighted, and the living space of top-level trees and shrubs is guaranteed. With the specific promotion of the root system of trees and shrubs by wood vinegar, stable community succession under artificial guidance is achieved, thus solving the long-term degradation problem.

[0040] (2) This application breaks through the bottleneck of alkaline soil remediation. The synergistic effect of wood vinegar and gypsum transforms the substrate from a simple physical covering layer into a chemically active amendment layer, significantly improving the survival rate of plants on alkaline and barren slopes. This application innovatively introduces a wood vinegar-plaster synergistic system. Wood vinegar neutralizes soil alkalinity and activates fixed nutrients. Its auxin-like substances strongly promote the root development of deep-rooted plants. Plaster provides calcium ions to replace sodium ions, and together with PAM, promotes the formation of water-stable aggregate structures, effectively preventing compaction. This chemical amendment system upgrades the spraying layer from a physical covering layer to an active amendment layer.

[0041] (3) The root anchoring force is greatly improved. Actual tests show that after adding the regulating components of this invention, the root depth of shrubs increases by more than 30% compared with conventional formulas, completely solving the risk of the two layers slipping off. The roots of plants (especially shrubs and trees) can quickly penetrate the sprayed layer and penetrate deep into the original soil of the slope, forming an anchored root system that is tens of centimeters deep, which greatly enhances the bonding force between the sprayed layer and the original slope surface.

[0042] (4) This application utilizes the natural bactericidal properties of wood vinegar to replace chemical bactericides, resulting in good environmental compatibility. The constructed native plant communities and the improved soil environment have stronger drought resistance and stress resistance, and the restoration effect is long-lasting. Attached Figure Description

[0043] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0044] Figure 1 This is a schematic diagram of the method for applying the hydroseeding matrix composition of the present invention to loess slopes;

[0045] Figure 2 This is a schematic cross-sectional view of the slope structure after spraying with the composition of the present invention;

[0046] Figure 3 The images shown are actual pictures of the matrix composition of the present invention (a is the vegetation community building component, and b is the matrix soil component). Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0048] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0049] Example 1

[0050] This embodiment was applied to an ecological restoration project of a high slope in a road cut in Shanxi Province.

[0051] The soil in the project area is loess soil with a pH of approximately 8.5. The annual rainfall is 380–500 mm, with July and August being the rainy season. The slope ratio is close to 1:1.

[0052] The substrate soil is a mixture of yellow cotton soil (sieved), peat soil, and wood fiber in a volume ratio of 10:1:0.5.

[0053] Group A (20% shallow-rooted herbs): 10.5 kg of ice grass, 7 kg of awnless bromegrass, and 1.5 kg of crested wheatgrass;

[0054] Group B (50% medium-rooted shrubs and grasses): 11 kg alfalfa, 4 kg saxaul, 19 kg Amorpha fruticosa, 27 kg lespedeza, and 6 kg caragana.

[0055] Group C (30% deep-rooted trees and shrubs): 5 kg of elm trees and 9 kg of apricot trees.

[0056] Rhizosphere microenvironment regulating components (addition amount per 100kg of seeds): 20kg of wood vinegar (pH 3.0, purchased from a forestry chemical plant); 25kg of gypsum; 12kg of high molecular weight polyacrylamide; 18kg of water-retaining agent (acrylamide-acrylate copolymer crosslinking product from SNF France); and 150kg of compound fertilizer (purchased from Luxi Zhongsheng Compound Fertilizer, where N:P2O5:K2O=15:15:15).

[0057] Construction steps for this application:

[0058] S1. Clean the slope, hang galvanized chain link fence, remove loose stones and weeds, and dig horizontal micro-grooves about 5cm deep along the contour lines to increase the roughness and adhesion of the slope. Lay galvanized iron wire chain link fence and fix it firmly to the slope with anchor rods.

[0059] S2. Before spraying, manually sow the larger apricot seeds (9 kg) from group C into the mesh of the wire mesh to ensure they are in contact with the soil.

[0060] S3. Add the prepared substrate soil (yellow cotton soil, peat moss, fiber), all seeds except for apricot seeds (91 kg of elm seeds from groups A, B, and C), gypsum, PAM, water-retaining agent, and compound fertilizer sequentially to a large wet spraying mixer. Add an appropriate amount of water and stir. In the final stage of stirring, slowly add 120 kg of wood vinegar solution and immediately stir until homogeneous, forming a uniform mud-like spraying material. (This is to prevent the wood vinegar solution from reacting violently with other components prematurely, ensuring that it interacts with the gypsum in situ on the slope after spraying, forming a favorable microporous structure). Use the wet spraying machine to evenly spray the mixture onto the netted slope, strictly controlling the spray layer thickness to achieve the design requirement of 10 cm.

[0061] S4. After hydroseeding, immediately cover the slope with non-woven fabric to retain moisture, protect from sunlight, and prevent erosion. Water regularly for maintenance, utilizing the natural antibacterial properties of wood vinegar to effectively prevent soil-borne diseases during the seedling stage. Continue maintenance until the vegetation fully covers the slope (approximately 60-90 days).

[0062] Establishment Status: Two months after construction, vegetation coverage reached 98%. Although the early herbaceous plants were not as tall as those in the pure herbaceous formulation, the seedling density of shrubs such as Amorpha fruticosa and Lespedeza bicolor was extremely high, and they grew vigorously. Resistance: Despite continuous rainfall in August, there were no gullies on the slope. During the dry spring of the following year, no large-scale yellowing occurred, indicating that the deep root system had played a role. Root System Monitoring: The following year's survey, including random sampling, showed that the average height of the shrubs exceeded 60cm. Their roots had generally penetrated the 10cm thick hydroseeding substrate layer and penetrated the original loess slope by an average of over 45cm. The root biomass and length were significantly better than the control area without the wood vinegar-gypsum conditioning system, achieving a firm "anchoring" between the hydroseeding layer and the original soil, resulting in excellent project stability.

[0063] Comparative Example 1

[0064] Substrate soil composition: Same as in Example 1, i.e., sieved yellow cotton soil, peat soil, and plant fiber are mixed in a volume ratio of 10:1:0.5.

[0065] The seed mix used was a standard formula: 40% tall fescue (exotic grass), 30% ryegrass, 20% alfalfa, and 10% sea buckthorn (without succession grading). To maintain comparable total sowing density, the total seed usage in this comparative example was set to be equivalent to that in Example 1, calculated at 100 kg of seeds per 100 m³ of substrate soil.

[0066] No wood vinegar or gypsum was added. To maintain basic nutrients and water retention capacity, only compound fertilizer and water-retaining agent were retained, with the same dosage as in Example 1 (i.e., 150 kg of compound fertilizer, 18 kg of water-retaining agent, and 12 kg of high-molecular-weight polyacrylamide). 25 kg of a conventional binder (such as nonionic homopolymer powder of common-type high-molecular-weight acrylamide (PAM), SNF France) was added to replace the PAM-gypsum system with granular structure stabilization function in Example 1.

[0067] Establishment status: 60 days after hydroseeding, the coverage reached 95%, mainly consisting of tall fescue and ryegrass, with a neat appearance. However, the survival rate of shrubs (sea buckthorn) was extremely low, with only a few scattered individuals visible.

[0068] Long-term stability: In the following spring, due to the excessive consumption of surface water by shallow-rooted herbs and the severe compaction of the substrate under alkaline conditions (due to the lack of wood vinegar and gypsum for improvement), large areas of the slope became withered and cracked.

[0069] Root system condition: The roots are mainly concentrated in the top 10cm sprayed layer and have not been able to effectively penetrate the original loess. The interface bonding is weak, and local landslides have occurred during the rainy season.

[0070] The construction process is consistent with that of Example 1 in terms of steps (slope repair, netting, hydroseeding, and curing).

[0071] Using only conventional seed mixtures and basic adhesive water-retaining materials cannot overcome the three core challenges unique to alkaline slopes in arid and semi-arid regions: vicious competition between grasses and shrubs, soil compaction and alkalization, and difficulty in root penetration.

[0072] The long-term stable effect achieved in Example 1 of this invention relies on the synergistic effect of two major technical features: the regulation of root spatiotemporal succession and the chemical improvement of the rhizosphere microenvironment. Neither can be omitted. The absence of either one will lead to a serious degradation of the ecological restoration effect in the short or medium term, thus demonstrating the non-obviousness and significant progress of this invention.

[0073] Comparative Example 2

[0074] No grass fiber was added to the substrate soil; only sieved yellow cotton soil and peat moss were retained in a ratio of 10:1, and no wood vinegar or gypsum was added. The seed formula was the same as in Example 1 (using native species).

[0075] The vegetation community construction components were exactly the same as in Example 1. The seed types, grading ratios (20% for Group A, 50% for Group B, and 30% for Group C) and total dosage (calculated at 100 kg per 100 m³ of substrate soil) remained unchanged.

[0076] The rhizosphere microenvironment regulating components contain no added wood vinegar or gypsum. To maintain basic moisture and nutrient supply, 12 kg of high-molecular-weight polyacrylamide (PAM), 18 kg of water-retaining agent, and 195 kg of compound fertilizer are retained in the same amounts as in Example 1. However, in this case, due to the lack of synergistic effect of gypsum and pH adjustment by wood vinegar, the expected granulation stabilization effect of PAM and the effectiveness of the fertilizer will be reduced.

[0077] The construction process is consistent with that of Example 1 in terms of steps (slope repair, netting, hydroseeding, and curing).

[0078] Erosion resistance: After heavy rain, due to the lack of physical reinforcement from grass fibers and the chemical agglomeration effect of gypsum, many small gullies appeared on the slope, and the exposed area of ​​the wire mesh was about 8%.

[0079] Growth status: Although native species were used, the seedlings grew slowly and the leaves turned yellow (symptoms of iron / phosphorus deficiency) due to the lack of wood vinegar to adjust the pH value. The overall coverage was only 85% at 60 days.

[0080] This comparative example attributes the decline in erosion resistance primarily to the lack of physical reinforcement and plant growth impairment primarily to the lack of chemical modification. This contrasts with Example 1, where fibers and chemical modifiers addressed two independent but coexisting problems: physical stability and chemical stress. Their synergistic effect is essential for achieving rapid, stable, and long-lasting repair. This comparative example demonstrates that the value of this invention lies not only in the selection of optimal plant species but also in creating a comprehensive matrix system that provides suitable physical support and a benign chemical rhizosphere environment for the selected plants. Without this system, relying solely on "seed localization" is insufficient to overcome harsh site conditions.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that the rhizosphere microenvironment conditioning components do not contain any wood vinegar or gypsum. To maintain basic moisture and nutrient supply, 12 kg of high-molecular-weight polyacrylamide (PAM), 18 kg of water-retaining agent, and 195 kg of compound fertilizer, the same amounts as in Example 1, are retained. The construction process, equipment, and maintenance standards are exactly the same as in Example 1 to ensure fairness in the comparison.

[0083] Six months after hydroseeding, the average root depth of the shrubs was measured to be approximately 30-40 cm, significantly lower than the over 45 cm observed in Example 1 (with added wood vinegar). This demonstrates that while using native plant seeds alone is effective, combining them with the wood vinegar root-promoting system of this invention significantly amplifies root penetration, achieving better slope stabilization results. While using only native species and physical reinforcement (as shown in Comparative Example 2) provides some improvement, it cannot overcome the bottleneck of chemical stress in alkaline soils. This invention, by introducing the specific combination of wood vinegar and gypsum, provides an innovative solution to overcome this bottleneck, achieving unexpected technical effects.

[0084] Comparative Example 4

[0085] The difference from Example 1 is as follows: no gypsum is added to the rhizosphere microenvironment conditioning components; the amount of wood vinegar (pH 3.0) is 20 kg; the amount of high-molecular-weight polyacrylamide (PAM) is 12 kg; the amount of water-retaining agent is 18 kg; and the amount of compound fertilizer is 175 kg. The substrate soil components and vegetation community construction components are exactly the same as in Example 1. The construction process, equipment, and maintenance standards are completely identical to those in Example 1 to ensure consistent experimental conditions. The only difference is that gypsum powder is not added to the mixing tank during mixture preparation.

[0086] pH adjustment effect: Initially, the application of wood vinegar alone can reduce the substrate pH from 8.5 to about 7.2. However, due to the lack of continuous Ca²⁺ supply and sulfate buffer provided by gypsum, the acidification effect is difficult to sustain. Within 30 days after spraying, the pH of the substrate surface rises to 7.8-8.0 due to the slowdown of the alkalinity of the loess soil itself. The duration of acidification is significantly shorter than in Example 1.

[0087] Granular structure stability: Lacking the "calcium bridge-polymer" composite granular network formed by the synergy of gypsum and PAM, the granular structure formed by PAM alone is not stable enough. After heavy rain, the slope surface showed slight compaction and gully erosion, with an exposed area of ​​about 4%, which is weaker than Example 1 but better than Comparative Example 2 without any chemical modifier.

[0088] Root system condition: Six months after hydroseeding, the average root depth of the shrubs was measured to be approximately 35-40 cm, which is between that of Comparative Example 3 (30-40 cm) and Example 1 (≥45 cm). This indicates that the root-promoting effect of wood vinegar to some extent compensates for the lack of gypsum, but due to the lack of long-term maintenance of the rhizosphere microenvironment by Ca²⁺, the root penetration ability did not reach the optimal level.

[0089] Long-term stability: In the following spring, due to the decline in the effect of acidification improvement, the availability of elements such as phosphorus and iron in the soil decreased, and the plant leaves turned slightly yellow, but overall it was better than Comparative Example 3. The coverage remained at around 88%, which was still lower than Example 1 (≥95%).

[0090] This comparative study demonstrates a significant synergistic effect between wood vinegar and gypsum in improving the rhizosphere microenvironment: wood vinegar is responsible for rapidly lowering pH and promoting root exudation in the initial stage, while gypsum is responsible for maintaining a long-term Ca²⁺ supply, strengthening aggregate structure, and preventing a return to alkalinity. Without gypsum, the improving effect of wood vinegar significantly diminishes over time, failing to achieve a sustained and stable rhizosphere chemical environment.

[0091] Comparative Example 5

[0092] The difference from Example 1 is as follows: The rhizosphere microenvironment conditioning components do not include high-molecular-weight polyacrylamide; the amounts are: 20 kg of wood vinegar (pH 3.0), 25 kg of gypsum, 18 kg of water-retaining agent, and 162 kg of compound fertilizer. The substrate soil components and vegetation community construction components are exactly the same as in Example 1. The construction process, equipment, and maintenance standards are completely identical to those in Example 1 to ensure consistent experimental conditions. The only difference is that high-molecular-weight polyacrylamide is not added to the mixing tank during mixture preparation.

[0093] Erosion resistance: Due to the lack of physical flocculation and bridging effects of PAM polymer chains on soil particles, even though gypsum provides Ca²⁺ to improve soil structure, the overall shear strength and water erosion resistance of the matrix are still significantly insufficient. After the rainstorm test, multiple sheet-like erosions appeared on the slope, and the exposed area of ​​the wire mesh was about 6%, which is significantly larger than that in Example 1.

[0094] Water retention performance: The absence of PAM leads to a decrease in the water-holding capacity of the substrate, with the effective water holding capacity reduced by approximately 20-25% compared to Example 1. During drought, the rate of water loss from the surface substrate accelerates, resulting in temporary wilting of seedlings and a prolonged recovery period.

[0095] Root system and vegetation growth: The effects of chemical amendment (wood vinegar + gypsum) were preserved, pH regulation and nutrient availability were basically normal, plant leaf color was normal, and there were no obvious symptoms of nutrient deficiency. The coverage rate of hydroseeding can reach 90% after 60 days, but due to the poor physical stability of the substrate, local settlement and slight displacement occurred on the slope, affecting the normal growth of some plants.

[0096] Long-term stability: The overall stability of the slope during the rainy season is weaker than that in Example 1. Local vegetation compensates for some soil stabilization function, but under continuous heavy rainfall, the bonding force between the matrix layer and the original loess interface is insufficient, and there is a certain risk of landslide.

[0097] This comparative example demonstrates that PAM plays an indispensable physical stabilization role in the system of this invention: its polymer network structure flocculates soil particles, regulates moisture, and controls the overall rheological properties of the matrix, which is crucial for ensuring the integrity of the hydroseeded layer under corrosive rainfall conditions. Both the chemical modification (wood vinegar + gypsum) and physical stabilization (PAM + grass fiber) systems must be complete simultaneously; the absence of either will lead to a significant decline in overall performance.

[0098] Comparative Example 6

[0099] The difference from Example 1 is as follows: no wood vinegar is added to the rhizosphere microenvironment conditioning component; the amount of gypsum is 25 kg, water-retaining agent is 18 kg, high-molecular-weight polyacrylamide is 12 kg, and compound fertilizer is 170 kg. The substrate soil composition and vegetation community construction components are exactly the same as in Example 1. The construction process, equipment, and maintenance standards are completely identical to those in Example 1 to ensure consistent experimental conditions. The only difference is that wood vinegar is not added to the mixing tank during mixture preparation.

[0100] pH environment: The initial pH of the substrate was not adjusted by wood vinegar and remained in the alkaline range of 8.2-8.6. Although the Ca²⁺ in gypsum can improve soil structure to some extent, its effect on lowering the pH itself is extremely limited. The alkaline environment still has a significant effect on the fixation of micronutrients such as iron, phosphorus, and zinc in the plant rhizosphere.

[0101] Vegetation growth: Seedling emergence was normal after hydroseeding, but yellowing of leaves was common during the rapid growth phase, especially in native herbaceous and shrub seedlings, exhibiting typical iron / phosphorus deficiency symptoms in alkaline soils. Coverage was only about 87% 60 days after hydroseeding, and shrub survival rate decreased by approximately 15% compared to Example 1.

[0102] Root condition: Six months after spraying, the average root depth of the shrubs was approximately 28-35 cm, significantly lower than that in Example 1 (≥45 cm). This indicates that the promoting effect of wood vinegar on root penetration into alkaline soil (including improving rhizosphere pH, activating nutrients, and promoting rhizosphere microbial activity) is irreplaceable, and gypsum and PAM alone cannot fully stimulate the deep rooting ability of plants.

[0103] Long-term stability: In the following spring, due to the stress of the continuous alkaline environment, the proportion of shrubs in the vegetation community continued to decline, and the community structure gradually evolved towards a single shallow-rooted herbaceous plant, which deviated significantly from the grass-shrub coordinated succession target expected in Example 1, and there was a risk to the long-term slope stabilization effect.

[0104] This comparative example demonstrates that wood vinegar, as a core regulator of the rhizosphere chemical microenvironment, plays an irreplaceable role in the system of this invention. While the combination of gypsum and PAM can maintain a good physical matrix structure, without the initial acidification and desealing of alkaline soil by wood vinegar, the improvement of nutrient availability and the activation of root penetration ability cannot be achieved. The synergistic effect of the three components of this invention (wood vinegar, gypsum, and PAM) is a prerequisite for the overall functional performance.

[0105] Comparative Example 7

[0106] The difference from Example 1 is that only gypsum (25 kg) is added to the rhizosphere microenvironment conditioning component, without adding wood vinegar or high-molecular-weight polyacrylamide. To maintain basic nutrients and water retention capacity, 18 kg of water-retaining agent and compound fertilizer, the same amount as in Example 1, are retained. The substrate soil composition and vegetation community construction components are exactly the same as in Example 1. The construction process, equipment, and maintenance standards are completely identical to those in Example 1.

[0107] Erosion resistance: Lacking the physical flocculation effect of PAM, the aggregation effect between matrix particles mainly relies on inorganic flocculation by Ca²⁺ provided by gypsum, resulting in insufficient structural stability. After heavy rain, significant sheet erosion and gully erosion appeared on the slope, with approximately 10% of the wire mesh exposed, approaching the erosion level of Comparative Example 2.

[0108] Vegetation growth: Without the regulation of wood vinegar, the alkaline environment caused significant stress to the seedlings, resulting in widespread yellowing of leaves. After 60 days, the coverage was only about 80%, which was one of the lower levels among the comparison ratios.

[0109] Root system condition: Six months after hydroseeding, the average root depth of the shrubs was only about 22-28 cm, which is one of the shallowest levels among all comparative examples. This indicates that the effect of gypsum alone on promoting deep root growth is very limited. It cannot soften the chemical barrier of alkaline soil (due to lack of wood vinegar) nor can it provide good physical matrix retention (due to lack of PAM).

[0110] Long-term stability: The following spring, large areas of the slope turned yellow and withered, vegetation cover dropped to about 55%, the grass-shrub ratio was severely unbalanced, and the slope stability was the worst. This comparative example illustrates that gypsum alone can only play a limited role in improving soil structure; its full effectiveness depends on synergistic use with wood vinegar and PAM.

[0111] Comparative Example 8

[0112] The difference from Example 1 is that only 12 kg of high-molecular-weight polyacrylamide was added to the rhizosphere microenvironment conditioning component, without the addition of wood vinegar and gypsum. To maintain basic nutrients and water retention capacity, 18 kg of water-retaining agent and compound fertilizer, the same amount as in Example 1, were retained. The substrate soil composition and vegetation community construction components were exactly the same as in Example 1. The construction process, equipment, and maintenance standards were completely identical to those in Example 1.

[0113] Erosion resistance: When PAM is used alone, it shows a certain effect on the physical flocculation of matrix particles. The degree of slope erosion after heavy rain is improved compared with Comparative Example 7, and the exposed area of ​​wire mesh is about 7%. This indicates that PAM contributes the most directly to physical stability among the three components. However, lacking the synergistic enhancement of Ca²⁺ from gypsum, the stability of the aggregate network is still significantly weaker than that of Example 1.

[0114] Vegetation growth: Without the improvement of the alkaline environment by wood vinegar and gypsum, seedlings still showed varying degrees of leaf yellowing, with a coverage of approximately 83% after 60 days, and a low shrub survival rate. PAM's good water retention properties had a certain positive impact on early seedling survival, but it could not solve the fundamental problem of alkaline chemical stress.

[0115] Root condition: Six months after hydroseeding, the average root depth of the shrubs was about 25-30 cm, slightly better than Comparative Example 7, but still far lower than Example 1. PAM alone can only provide relatively loose physical growth space for the roots and cannot overcome the chemical limitations of alkaline soil on root growth.

[0116] Long-term stability: The vegetation degradation was more obvious in the following spring, with varying degrees of compaction on the slope and a coverage of about 65%. This comparative example illustrates that PAM mainly plays a physical structural role in the system of this invention, and its full realization of ecological improvement benefits depends on the chemical rhizosphere improvement provided by wood vinegar and gypsum.

[0117] Comparative Example 9

[0118] The difference from Example 1 is that only wood vinegar (20 kg, pH 3.0) was added to the rhizosphere microenvironment conditioning component; gypsum and high-molecular-weight polyacrylamide were not added. To maintain basic nutrients and water retention capacity, 18 kg of water-retaining agent and compound fertilizer, the same amount as in Example 1, were retained. The substrate soil composition and vegetation community construction components were exactly the same as in Example 1. The construction process, equipment, and maintenance standards were completely identical to those in Example 1.

[0119] pH adjustment and nutrient availability: Wood vinegar alone can reduce the substrate pH from 8.5 to 7.0-7.3 in a short period of time, and the initial improvement in nutrient availability is significant. However, without the continuous Ca²⁺ supply provided by gypsum and the physical flocculent protection of PAM, the acidification effect fades quickly (the pH rises back to above 7.8 after about 30-45 days), and the improvement effect is difficult to sustain.

[0120] Erosion resistance: Lacking the polymeric network structure of PAM and the inorganic flocculation effect of gypsum (Ca²⁺), the matrix exhibits the worst physical stability. Slope erosion was most severe after heavy rain, with 12% of the wire mesh exposed, the highest level among all comparative examples, indicating significant erosion damage to the substrate spraying layer.

[0121] Vegetation growth: Benefiting from the initial acidification improvement, seedlings emerged uniformly and showed better early growth than comparative examples 7 and 8. However, as the pH rose and the physical structure of the substrate was damaged, the growth rate slowed down significantly after 30 days, and the coverage was about 85% after 60 days, which did not match its initial advantages.

[0122] Root system condition: Six months after hydroseeding, the average root depth of the shrubs was approximately 30-38 cm, which was the best among the individual component comparisons (Comparative Examples 7-9), confirming the core role of wood vinegar in promoting deep root development. However, due to the instability of the substrate's physical structure leading to local slope displacement, some of the established root systems were damaged, and the overall slope stabilization effect was still not ideal.

[0123] Long-term stability: In the following spring, affected by both substrate compaction and the slowdown of pH alkalinity, vegetation cover decreased to approximately 70%, with obvious slope erosion and low shrub survival rate. This comparative example shows that although wood vinegar is the component that contributes most directly to improving the rhizosphere chemical environment among the three components, its sustained effectiveness depends on the long-term buffering effect of gypsum and the physical matrix protection of PAM. Without any of the three, the rapid, stable, and long-lasting repair effect achieved in Example 1 cannot be realized.

[0124] The experimental results of Comparative Examples 7-9 show that the three components—wood vinegar, gypsum, and high-molecular-weight polyacrylamide—each perform three irreplaceable core functions in the system of this invention: chemical promotion, long-term chemical maintenance, and physical stabilization. The independent application of any single component cannot reproduce the comprehensive improvement effect under the synergistic effect of the three, further confirming the integrity and innovation of the rhizosphere microenvironment regulation system of this invention.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drought-prone ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement, characterized in that: The matrix composition includes a matrix soil component, a vegetation community building component, and a rhizosphere microenvironment regulating component; 2.5-4.0 kg of vegetation community building component and 4.5-8.0 kg of rhizosphere microenvironment regulating component are added to each cubic meter of matrix soil component. The vegetation community building components include pioneer herb seeds, transitional leguminous shrub and grass seeds, and top deep-rooted tree and shrub seeds.

2. The drought ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement according to claim 1, characterized in that: The mass fraction of Pioneer Herbaceous seeds is 15%–25%; The mass fraction of transitional leguminous shrub seeds is 45%–55%; The weight fraction of top-grade deep-rooted tree and shrub seeds is 20% to 30%, and the top-grade deep-rooted tree and shrub seeds are selected from one or more of elm and apricot.

3. The drought ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement according to claim 1, characterized in that: Pioneer Herb Seeds are selected from one or more of the following: ice grass, awnless brome, and crested wheatgrass; The seeds of transitional leguminous shrubs and grasses are selected from one or more of alfalfa, alfalfa, purple locust, lespedeza, and caragana. Top-quality deep-rooted tree and shrub seeds are selected from one or more of elm and apricot trees.

4. The drought ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement according to claim 1, characterized in that: The matrix soil components include imported soil, organic soil and reinforcing fiber, with a volume ratio of (9-11):(0.8-1.5):(0.3-0.6).

5. The drought ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement according to claim 4, characterized in that: In the substrate soil components, the topsoil is sieved loam or loam with a pH value of 8.0 to 8.6; the organic soil is peat moss or well-rotted compost with an organic matter content of ≥30%; and the reinforcing fiber is plant fiber or polypropylene fiber with a length of 6 to 15 mm.

6. The drought ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement according to claim 1, characterized in that: The pH-growth dual-effect regulator in the rhizosphere microenvironment regulating component is wood vinegar or a mixture of wood vinegar and superphosphate; the aggregate structure stabilizer includes high molecular weight polyacrylamide and gypsum; and the water-retaining agent is an acrylamide-acrylate copolymer crosslinker.

7. The drought ecological restoration substrate based on root spatiotemporal succession regulation and microenvironment improvement according to claim 6, characterized in that: The components regulating the microenvironment, by mass percentage, include: Wood vinegar: 15-25 parts; Polyacrylamide: 10-15 parts; Gypsum: 20-30 parts; Water-retaining agent: 15-20 parts; The remainder is compound fertilizer; Preferably, the wood vinegar has a pH value of 2.5–3.5 and an organic acid content of ≥3%; Preferably, the water-retaining agent is an acrylamide-acrylate copolymer crosslinker; Preferably, the compound fertilizer has an N:P2O5:K2O ratio of 15:15:

15.

8. A method for slope ecological restoration using the drought-resistant ecological restoration matrix based on root spatiotemporal succession regulation and microenvironment improvement as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Clean the slope surface and create horizontal micro-grooves on the slope surface; S2: Lay the metal mesh and anchor it; S3: If the vegetation community building component contains large seeds with a particle size greater than 5 mm, the large seeds are directly sown manually into the mesh of the metal mesh before hydroseeding. S4: Mix the substrate soil components with the rhizosphere microenvironment conditioning components and the remaining seeds except for large seeds evenly to prepare a mud-like spraying material; S5: Use a wet spraying machine to spray the hydroseeding material onto the slope, with a thickness of 8-12cm; S6: Cover with non-woven fabric and water.

9. The method according to claim 8, characterized in that: In step S4, the wood vinegar is added at the final stage of adding water and stirring, so as to utilize the in-situ reaction between the wood vinegar and gypsum to form a microporous structure.

10. The method of claim 8 or 9 is applied to alkaline soil slopes in arid and semi-arid areas with a pH value greater than 8.0 and an annual rainfall of less than 500 mm.

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