A method for vegetation restoration of salinized wetland based on gradient moisture regulation

Abstract

The application discloses a kind of salinization wetland vegetation recovery method based on gradient moisture control, first, according to moisture gradient, degraded wetland is divided into three levels of moisture zone, namely low moisture zone, medium moisture zone and high moisture zone, and according to moisture zoning, vegetation recovery scheme is formulated, based on the quantitative relationship between soil moisture content and vegetation aboveground biomass, water supplement measures are formulated, and soil is improved through salt-nutrient synergistic control.The application innovatively integrates hydrological engineering and ecological process control, breaks through the differentiated water supply mode, realizes the synergistic effect of increasing soil and salt inhibition, provides a replicable recovery paradigm for semi-arid region wetlands, and provides a quantifiable natural solution for coping with land desertification and climate change.

Description

Technical Field

[0001] This invention relates to the fields of ecological restoration, wetland protection, and water resource management, and more specifically to a method for vegetation restoration in saline wetlands based on gradient water regulation. Background Technology

[0002] Semi-arid wetlands, as core carriers of ecological transition zones, hold an irreplaceable strategic position in maintaining regional water resource balance, conserving biodiversity, and sequestering carbon emissions. Taking typical wetlands in Northwest my country as an example, their soil carbon storage is significantly higher than that of surrounding ecosystems, making them a precious carbon sink in arid environments. However, under the combined effects of climate change and human activities in recent decades, these wetlands are facing a systemic degradation crisis. Sharp declines in natural precipitation and over-extraction of groundwater have led to a continuous deficit in soil moisture, triggering a vicious cycle of salt accumulation on the surface. Monitoring shows that soil electrical conductivity in some areas has exceeded 4000 μS / cm, far exceeding the vegetation tolerance threshold. Hydrological imbalance directly triggers vegetation community decline, manifested as a sharp drop in cover to below 30%, aboveground biomass below 40% of the stable state, and further accompanied by hindered plant nutrient absorption, with the nitrogen-to-phosphorus ratio in leaves falling below 10, severely restricting ecosystem productivity. At the same time, the carbon and nitrogen cycle mediated by soil microorganisms has collapsed, with microbial biomass carbon and phosphorus decreasing by more than 30% compared to healthy wetlands. This has led to accelerated loss of soil organic matter, causing wetlands to reverse from "carbon sinks" to "carbon sources." This intertwined "water-salt-biological" triple degradation pathway constitutes a major challenge for wetland restoration in semi-arid regions.

[0003] Current restoration technologies face severe challenges. First, homogenized irrigation strategies ignore the spatial heterogeneity of soil moisture gradients, and indiscriminate irrigation can exacerbate the salt leaching-evaporation concentration cycle. Second, vegetation restoration and soil improvement are disconnected; even with high-density planting of salt-tolerant species, phosphorus uptake efficiency in unimproved soils remains below 60% of normal levels. Third, microbial-driven mechanisms have long been neglected; chemical amendments fail to activate soil biological activity, leading to nutrient cycling blockage. At their root, traditional methods have failed to unravel the coupling mechanism between moisture gradients, salt transport, vegetation response, and microbial function, particularly lacking quantitative understanding of key ecological thresholds (such as salt inhibition thresholds and microbial activation thresholds). Furthermore, semi-arid wetlands face problems such as soil salinization (EC value > 4000 μS / cm), vegetation degradation (coverage < 30%), and soil carbon-nitrogen imbalance (abnormal C / N ratio), and traditional irrigation methods easily lead to water-salt-nutrient imbalances. Therefore, providing a new wetland vegetation restoration method that addresses the shortcomings of existing technologies is a pressing issue for those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a method for vegetation restoration in saline wetlands based on gradient water regulation. By innovatively integrating hydrological engineering and ecological process regulation, it breaks through the differentiated water replenishment model, achieves synergistic effect of increasing soil moisture and suppressing salinity, provides a replicable restoration paradigm for wetlands in semi-arid areas, and also provides a quantifiable natural solution for addressing land desertification and climate change.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for vegetation restoration in saline wetlands based on gradient water regulation includes the following steps:

[0007] Step 1: Moisture gradient division

[0008] Degraded wetlands are divided into low-water, medium-water, and high-water zones based on soil moisture content and soil electrical conductivity.

[0009] Step Two: Vegetation Restoration and Watering Measures

[0010] Select salt-tolerant pioneer species, and adopt different planting patterns in different water zones according to the water zone division in step one. Develop water replenishment measures based on the quantitative relationship between soil moisture content and aboveground biomass (i.e., the vegetation growth water requirement model).

[0011] y = 1387.2x - 71.28 R ² = 0.7138;

[0012] Where y represents the aboveground biomass of vegetation, in g / m³ 2 x represents soil moisture content, %

[0013] Step 3: Soil Improvement

[0014] (3.1) Salinity control: Add humic acid and microorganisms to the soil during water replenishment to reduce soil electrical conductivity to <3000μS / cm;

[0015] (3.2) Nutrient balance regulation: Apply slow-release fertilizer to achieve a C:N:P ratio of 100:8:1.

[0016] Preferably, the division of low-water zones, medium-water zones, and high-water zones in step one is based on the following criteria:

[0017] Low water zone: Soil moisture content <10%, soil electrical conductivity >3500 μS / cm;

[0018] Medium-water zone: Soil moisture content 10-15%, soil electrical conductivity 2500-3500 μS / cm;

[0019] High water zone: Soil moisture content >15%, soil electrical conductivity <2500 μS / cm.

[0020] Preferably, the salt-tolerant pioneer species mentioned in step two are Suaeda salsa, Reed, and Typha, and the specific planting pattern is as follows:

[0021] Low-water zone: Plant Suaeda salsa in saline-alkali soil, with a planting density of >50 plants / m²;

[0022] In the middle water zone, plant Suaeda salsa and Reed, with a total planting density of 30 plants / m² and a density ratio of 1:1 for the two plants.

[0023] High-water zone: Plant reeds and cattails at a density of <20 plants / m², with the proportion of cattails not exceeding 1 / 5 of the total planting density.

[0024] Preferably, the water replenishment measures described in step one are as follows:

[0025] Low-water zones: Pulsed watering is used, with a watering depth of 5 cm each time and an interval of 3 days between each time, to maintain the soil moisture content at 12±2%;

[0026] In the secondary water zone, slow-release water replenishment is adopted, with a daily water depth of 2 cm to maintain soil moisture content at 18±2%.

[0027] High-water zone: Natural water storage during the rainy season, and daily water replenishment depth of <1cm during the dry season to maintain soil moisture content at 25%±4%.

[0028] Furthermore, when the aboveground biomass in the high-water zone is >220 g / m², the aboveground parts should be harvested and returned to the low-water zone.

[0029] Furthermore, the microorganisms mentioned in step (3.1) are nitrogen-fixing bacteria and phosphate-solubilizing bacteria; their specific applications are as follows:

[0030] Low-water zone: Use a compound microbial agent composed of nitrogen-fixing bacteria and phosphate-solubilizing bacteria at a dosage of 0.6-0.8 kg / m²; use 0.5 kg / m² of humic acid; wherein the mass ratio of nitrogen-fixing bacteria to phosphate-solubilizing bacteria is 1:1, and the compound microbial agent and humic acid are dissolved in water before application.

[0031] Greywater zone: Use a compound microbial agent composed of nitrogen-fixing bacteria and phosphate-solubilizing bacteria at a dosage of 0.3-0.4 kg / m²; use 0.2 kg / m² of humic acid; wherein the mass ratio of nitrogen-fixing bacteria to phosphate-solubilizing bacteria is 1:1, and the compound microbial agent and humic acid are dissolved in water before application;

[0032] High-water zone: Use phosphate-solubilizing bacteria at a rate of 0.1 kg / m²; use 0% humic acid; dissolve the phosphate-solubilizing bacteria in water before application.

[0033] Furthermore, when the soil electrical conductivity is > 3500 μS / cm, the amount of microorganisms used increases by 20% based on the original mass; when the soil carbon-nitrogen ratio is > 12, the amount of microorganisms used decreases by 15% based on the original mass; for every 1 kg of aboveground parts returned to the field, the corresponding amount of microorganisms used decreases by 0.1 kg / m².

[0034] Preferably, the slow-release fertilizer described in step (3.2) comprises, by weight percentage, 75% ammonium polyphosphate, 25% coated urea and 5% humic acid.

[0035] Furthermore, by mass percentage, ammonium polyphosphate contains 62% P2O5, coated urea contains 42% N, and humic acid contains ≥50% C.

[0036] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for vegetation restoration in saline wetlands based on gradient water regulation, which has the following beneficial effects:

[0037] This invention establishes a quantitative relationship between soil moisture content and aboveground biomass based on a water-vegetation response model fitted from field survey data (y=1387.2x-71.28). R ² = 0.7138, where y represents aboveground biomass (g / m³). 2 (x represents soil moisture content (%)), guiding precise water replenishment. Furthermore, through synergistic regulation of salt, carbon, and nitrogen, when the aboveground biomass >220 g / m², the aboveground parts are harvested and returned to the low-water zone to increase soil organic carbon (high-water zone organic carbon >7 g / kg). Finally, through microbial-driven inoculation with salt-tolerant bacteria (Pseudomonas), microbial phosphorus biomass is increased (high-water zone microbial phosphorus reaches >5 mg / kg), activating the soil phosphorus pool. The technical advantage of this invention lies in resolving the feedback loop between salt, water, and vegetation, reducing freshwater consumption, and significantly shortening the vegetation recovery cycle. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 The vegetation cover is compared between the present invention and traditional restoration methods;

[0040] Figure 2 This invention represents the aboveground biomass of vegetation under both the present invention and traditional restoration methods.

[0041] Figure 3The soil organic carbon content is compared to that of the present invention and traditional restoration methods. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] The vegetation restoration method for saline wetlands based on gradient water regulation includes the following specific steps:

[0045] Step 1: Moisture gradient division

[0046] Degraded wetlands are divided into three levels of water zones, specifically:

[0047] Low water zone: Soil moisture content <10%, soil electrical conductivity >3500 μS / cm;

[0048] Medium-water zone: Soil moisture content 10-15%, soil electrical conductivity 2500-3500 μS / cm;

[0049] High water zone: Soil moisture content >15%, soil electrical conductivity <2500 μS / cm;

[0050] Step Two: Vegetation Restoration and Watering Measures

[0051] Select salt-tolerant pioneer species (Suaeda salsa + Reed, with a mixed community of stems and leaves containing >1.5 g / kg phosphorus); adopt different planting patterns for different water zones:

[0052] Low-water zone: High-density planting of Suaeda salsa (>50 plants / m²);

[0053] In the middle water zone: medium density planting of Suaeda salsa and Reed (30 plants / m², with a density ratio of 1:1 between the two plants).

[0054] High-water zone: Low-density planting of reeds (<20 plants / m²), combined with emergent plants such as cattails (density ratio not exceeding 1 / 5);

[0055] Biomass regulation: When the aboveground biomass is >220 g / m², the aboveground parts are harvested and returned to the field to increase soil organic carbon (which can increase by 15%-20%).

[0056] A water-vegetation response model fitted based on field survey data was used to establish a quantitative relationship between soil moisture content and aboveground biomass (y=1387.2x-71.28). R ² = 0.7138, where y represents aboveground biomass (g / m³). 2 (x represents soil moisture content (%)), based on the dynamics of soil physical properties and this model to guide precise water replenishment, mainly including:

[0057] Low water zone: Pulsed watering (5 cm water depth per watering, 3-day interval) is used to maintain soil moisture content at 12±2% and reduce surface salinity (EC reduction >30%).

[0058] In the secondary water zone, slow-release water replenishment (2 cm / day) is adopted to maintain soil moisture content at 18±2%;

[0059] High-water zone: Natural water storage during the rainy season, and a small amount of water replenishment (<1cm / day) during the dry season to maintain soil moisture content at 25%±4%.

[0060] Step 3: Soil Improvement

[0061] Salt control: Add humic acid during water replenishment, combined with microbial activators (pseudomonas such as nitrogen-fixing bacteria), to reduce soil electrical conductivity (EC) to <3000 μS / cm.

[0062] Low-water zone: Compound bacterial agent (mass ratio of nitrogen-fixing bacteria: phosphate-solubilizing bacteria 1:1) application rate: 0.6-0.8 kg / m²; humic acid carrier: 0.5 kg / m²; (both must be dissolved in water and applied simultaneously with water replenishment).

[0063] Greywater zone: Compound bacterial agent (mass ratio of nitrogen-fixing bacteria to phosphate-solubilizing bacteria 1:1) application rate: 0.3-0.4 kg / m²; humic acid carrier: 0.2 kg / m²; (both must be dissolved in water and applied simultaneously with water replenishment).

[0064] High-water zone: Single phosphate-solubilizing bacteria application rate: 0.1 kg / m² (to maintain phosphorus activation function); Humic acid carrier: 0 (to avoid excessive carbon leading to nitrogen competition); must be dissolved in water and applied simultaneously with water replenishment;

[0065] In addition, dynamic adjustments are needed based on soil conditions. When soil electrical conductivity > 3500 μS / cm, the amount of microbial agent should be increased by 20% (to counteract salt inhibition). When the soil carbon-nitrogen ratio > 12, the amount of microbial agent should be reduced by 15% (to prevent nitrogen fixation). For every 1 kg of litter returned to the field, the amount of microbial agent should be reduced by 0.1 kg / m² (litter provides a carbon source).

[0066] Nutrient balance regulation: Apply slow-release fertilizer to achieve a C:N:P ratio of 100:8:1;

[0067] Slow-release fertilizer components:

[0068] Ammonium polyphosphate (containing 62% P2O5 by mass) provides a slow-release phosphorus source that hydrolyzes into plant-absorbable orthophosphate.

[0069] Coated urea (by weight, containing 42% N): controlled-release nitrogen (release cycle 90 days), matching the plant growing season;

[0070] Humic acid (by mass percentage, C content ≥50%): chelates salts, promotes phosphorus activation, and inhibits excessive carbon accumulation in stems.

[0071] The weight ratio of the three components is 75%, 25%, and 5%.

[0072] Implementation results:

[0073] The implementation effect was monitored by using naturally restored wetlands and wetlands restored by "mass water replenishment".

[0074] Naturally restored wetlands refer to wetlands that undergo ecological restoration without any artificial restoration measures, relying solely on their natural restoration potential.

[0075] "Flood irrigation" wetland restoration refers to wetland restoration with increasing water surface area (water depth of about 40-50 cm) as the core measure.

[0076] Two years after the technology was implemented, monitoring of the restoration effects was conducted. The results are attached. Figure 1-3 As shown, the results indicate that the vegetation coverage of naturally restored wetlands and wetlands restored through "flood irrigation" was 24% and 13%, respectively. Figure 1 The aboveground biomass was 82.5 g / m² and 52.1 g / m². Figure 2 Soil organic carbon was 4.6 g / kg and 4.5 g / kg ( Figure 3 This technology, when applied to wetlands, resulted in a vegetation cover of 65%, an increase in aboveground biomass to 274.4 g / m², and an increase in soil organic carbon to 7.9 g / kg. Compared with traditional restoration methods (natural restoration and flood irrigation), this invention has significant advantages.

[0077] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for vegetation restoration in saline wetlands based on gradient water regulation, characterized in that, Includes the following steps: Step 1: Moisture gradient division Degraded wetlands are divided into low-water, medium-water, and high-water zones based on soil moisture content and soil electrical conductivity. The criteria for these zones are as follows: Low water zone: Soil moisture content <10%, soil electrical conductivity >3500 μS / cm; Medium-water zone: Soil moisture content 10-15%, soil electrical conductivity 2500-3500 μS / cm; High water zone: Soil moisture content >15%, soil electrical conductivity <2500 μS / cm; Step Two: Vegetation Restoration and Watering Measures Select salt-tolerant pioneer species, and based on the water zoning in step one, adopt different planting patterns in different water zoning areas. Develop water replenishment measures based on the quantitative relationship between soil moisture content and aboveground biomass of the vegetation, namely: y=1387.2x-71.28, R²=0.7138; Where y represents the aboveground biomass of vegetation, in g / m³ 2 x represents soil moisture content, % The water replenishment measures mentioned are as follows: Low-water zones: Pulsed watering is used, with a watering depth of 5 cm each time and an interval of 3 days between each time, to maintain the soil moisture content at 12±2%; In the secondary water zone, slow-release water replenishment is adopted, with a daily water depth of 2 cm to maintain soil moisture content at 18±2%. High-water zone: Natural water storage during the rainy season, and daily water replenishment depth <1cm during the dry season to maintain soil moisture content at 25%±4%; The salt-tolerant pioneer species are Suaeda salsa, Reed, and Typha, and the specific planting pattern is as follows: Low-water zone: Plant Suaeda salsa in saline-alkali soil, with a planting density of >50 plants / m²; In the middle water zone, plant Suaeda salsa and Reed, with a total planting density of 30 plants / m² and a density ratio of 1:1 for the two plants. High-water zone: Plant reeds and cattails at a density of <20 plants / m², with the proportion of cattails in the total planting density not exceeding 1 / 5; Step 3: Soil Improvement (3.1) Salinity control: Add humic acid and microorganisms to the soil during water replenishment to reduce soil electrical conductivity to <3000μS / cm; The microorganisms are nitrogen-fixing bacteria and phosphate-solubilizing bacteria; their specific applications are as follows: Low-water zone: Use a compound microbial agent composed of nitrogen-fixing bacteria and phosphate-solubilizing bacteria at a dosage of 0.6-0.8 kg / m²; use 0.5 kg / m² of humic acid; wherein the mass ratio of nitrogen-fixing bacteria to phosphate-solubilizing bacteria is 1:1, and the compound microbial agent and humic acid are dissolved in water before application. Greywater zone: Use a compound microbial agent composed of nitrogen-fixing bacteria and phosphate-solubilizing bacteria at a dosage of 0.3-0.4 kg / m²; use 0.2 kg / m² of humic acid; wherein the mass ratio of nitrogen-fixing bacteria to phosphate-solubilizing bacteria is 1:1, and the compound microbial agent and humic acid are dissolved in water before application; High-water zone: Use phosphate-solubilizing bacteria at a rate of 0.1 kg / m²; use 0% humic acid; dissolve the phosphate-solubilizing bacteria in water before application. When the soil electrical conductivity is > 3500 μS / cm, the amount of microorganisms used should be increased by 20% based on the original mass; when the soil carbon-nitrogen ratio is > 12, the amount of microorganisms used should be reduced by 15% based on the original mass; for every 1 kg of aboveground parts returned to the field, the amount of microorganisms used should be reduced by 0.1 kg / m². (3.2) Nutrient balance regulation: Apply slow-release fertilizer to achieve a C:N:P ratio of 100:8:1; When the aboveground biomass in the high-water zone is >220 g / m², the aboveground parts should be harvested and returned to the low-water zone.

2. The method for vegetation restoration in saline wetlands based on gradient water regulation according to claim 1, characterized in that, The slow-release fertilizer described in step (3.2) comprises, by weight percentage, 75% ammonium polyphosphate, 25% coated urea and 5% humic acid.

3. The method for vegetation restoration in saline wetlands based on gradient water regulation according to claim 2, characterized in that, By mass percentage, ammonium polyphosphate contains 62% P2O5, coated urea contains 42% N, and humic acid contains ≥50% C.

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