Method for repairing small and micro wetlands in three-dimensional coupling plant configuration mode

Abstract

The invention discloses a method for repairing a small and micro wetland in a three-dimensional coupling plant configuration mode. The method comprises the following steps: (1) constructing a woody skeleton layer: constructing a carbon sink core and a habitat support by matching trees, shrub and grass; (2) constructing a herbaceous purification layer: intercepting pollution and supplementing carbon sink; (3) construction of an aquatic buffer layer: ecological communication and carbon library stabilization; and (4) an ecological coupling key technology. According to the method, a vertical ecological structure with a woody framework layer, a herbaceous purification layer and an aquatic buffer layer is constructed, and the taxodium orientalis and local plants are introduced to be reasonably proportioned, so that the balance between the carbon sequestration capacity and the ecological safety is realized. And a microbial enhancement technology is integrated, so that the ecological environment of the small and micro wetlands is improved, the self-purification capacity and carbon sequestration efficiency of the wetland system are improved, and the carbon sequestration function of the wetland system is enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wetland ecological restoration and carbon sink enhancement, in particular to a method for repairing small and micro wetlands by using a three-dimensional coupled plant configuration mode. BACKGROUND

[0002] Subtropical urban small and micro wetlands (including ponds, pits, small riverine wetlands, etc., usually <10 hectares in area) are numerous and widely distributed, and are an important part of the regional ecosystem. The ecological restoration and carbon sink capacity enhancement of small and micro wetlands is of great significance for improving the regional ecological environment and enhancing the ecosystem service function. However, the current small and micro wetlands are facing many serious problems. In terms of hydrology, small and micro wetlands generally have weak hydrological connectivity, which makes the water flow of the wetland poor, the material exchange and energy flow limited, and the vitality and stability of the wetland ecosystem reduced. In terms of pollution, it is easily affected by agricultural non-point source pollution, industrial point source pollution and domestic sewage discharge, among which the problem of total phosphorus exceeding standard is particularly serious, which seriously threatens the water quality and ecological balance of the wetland. In terms of carbon sink capacity, it is easily affected by extreme climate (such as drought, flood) and human activities (such as vegetation destruction, soil disturbance), and the carbon sink stability is poor, making it difficult to fully play its carbon sink potential.

[0003] In view of the current problems of ecological structure degradation and carbon sink capacity attenuation of subtropical urban small and micro wetlands, and the lack of targetedness and carbon sink efficiency of existing restoration techniques, it is urgent to develop ecological restoration and carbon sink efficiency integrated techniques that adapt to the ecological characteristics of small and micro wetlands, to comprehensively improve their core ecological system functions such as water quality purification, biological habitat maintenance and carbon sequestration.

[0004] In the field of wetland ecological restoration and carbon sink enhancement, a large amount of research and practice has been carried out. In the research of ecological effects of complex pollutants, some studies have used environmental chemical analysis techniques to preliminarily explore the migration and transformation rules of pollutants in wetlands, but most of the research objects focus on large wetlands at the watershed scale or single type of pollutants (such as nitrogen and phosphorus or single heavy metal), and the research on the complex scene of multiple types of pollutants (such as nitrogen and phosphorus nutrients, heavy metals, persistent organic pollutants, etc.) coexisting in small and micro wetlands is still relatively scarce. It is difficult to accurately analyze the interaction, migration and transformation rules and ecological toxicity effects under the coexistence of multiple pollutants, and thus it is difficult to provide accurate theoretical basis for the ecological restoration of small and micro wetlands.

[0005] In the field of plant-microorganism interaction ecological remediation technology, the existing technology mostly uses single herbaceous plants (such as reed) or conventional plant combinations for remediation, lacks the optimization of the ratio of woody plants to local dominant plants and the functional synergy design, and does not fully tap the functional potential of the narrow root exudates of the two in regulating microbial communities and rhizosphere microenvironment synergy purification; on the other hand, the existing plant configuration mostly focuses on single pollution interception function, and fails to incorporate carbon sink supplement (such as selecting plants with high biomass and slow decomposition of litter) and landscape ornamental (considering seasonal changes and plant level matching) into system design, making it difficult to meet the comprehensive needs of wetland "ecological purification-carbon sink enhancement-landscape service". In the aspect of microbial ecological remediation, some studies have begun to focus on the carbon sequestration and emission reduction function of wetland ecosystems. In existing research, some schemes attempt to adjust the carbon cycle process of wetland soil by adding functional microbial agents, and some studies on greenhouse gas emissions in wetlands have monitored and analyzed greenhouse gas emission fluxes under different environmental conditions, and explored the influence mechanism of temperature, water, vegetation type and other factors on greenhouse gas emissions. However, the above researches have not carried out in-situ observation and directional culture of plant root microorganisms, and have not deeply explored the interaction mechanism between plant root exudates and exogenous microbial agents, making it difficult to achieve efficient synergy between plants and microorganisms through directional activation of microbial agent activity by root exudates to form "carbon sequestration-emission reduction" dual effect, and there are still obvious technical limitations in dealing with the poor stability of small and micro wetland carbon pools (carbon storage annual fluctuation coefficient > 15%) and complex pollution. At the same time, the existing wetland monitoring equipment is mostly designed based on large water bodies or laboratory simulation environments, and its monitoring parameters, installation methods and data collection frequency cannot adapt to the unique ecological characteristics of small and micro wetlands, making it difficult to meet the monitoring needs of the whole growth cycle of small and micro wetland plants and the long-term purification process of pollutants.

[0006] Therefore, in the field of wetland ecological remediation and carbon sink enhancement technology, there are many problems in the existing technology that need to be solved. In terms of plant configuration mode, the existing technology mostly uses single plants or conventional plant combinations for wetland remediation, which is difficult to achieve functional synergy between plants, and does not fully tap the potential advantages of woody plants and local dominant plants in rhizosphere microenvironment complementation and habitat stratification,

[0007] Especially in the comprehensive functions of pollutant removal, carbon sink supplement and landscape improvement, there are obvious defects, which are difficult to meet the multiple needs of subtropical urban small and micro wetland ecological restoration and function improvement. In the field of microbial ecological restoration, the existing research is insufficient in in-situ observation and culture of plant root microbial community, and the synergistic mechanism of plant root exudates and microbial inoculants is unknown. And it has not been deeply explored to screen specific strains from water body, and to realize effective carbon assimilation through domestication and directional injection, which cannot effectively deal with the problems of poor carbon sink stability and complex pollution of small and micro wetlands. In addition, the monitoring demand of meeting the whole growth cycle of small and micro wetland plants and the long-term purification process of pollutants further restricts the optimization of restoration technology.

[0008] In summary, the existing technology has obvious deficiencies in solving the problems of weak hydrological connectivity, complex pollution sources and poor carbon sink stability of subtropical small and micro wetlands, and realizing the technical system of small and micro wetland ecological restoration "hydrological regulation-pollution control-carbon sink efficiency". An innovative technical solution is needed to fill this gap. SUMMARY

[0009] The technical problem to be solved by the present application is to overcome the deficiencies of the prior art and provide a method for repairing small and micro wetlands by a three-dimensional coupled plant configuration mode, which realizes the improvement of hydrological connectivity, effective pollution control and enhancement of carbon sink stability of subtropical urban small and micro wetlands, and achieves the goal of ecological restoration and carbon sink efficiency.

[0010] The technical solution adopted by the present application to solve the technical problem is that

[0011] A method for repairing small and micro wetlands by a three-dimensional coupled plant configuration mode, specifically comprising the following steps:

[0012] (I) Construction of the woody framework layer: construction of carbon sink core and habitat support by matching trees, shrubs and grasses

[0013] A, main tree species configuration

[0014] (1) Gradient planting of Cunninghamia lanceolata: plant 3-year-old Cunninghamia lanceolata container seedlings in the land transition zone around the wetland, plant 50-60 plants per mu; set up 2-4 rows of buffer zones along the water level line, and gradually reduce the row spacing to form a "sparse outside and dense inside" permeable forest belt;

[0015] Further, when the Tsuga orientalis gradient is planted, in the terrestrial transition zone with an elevation higher than the normal water level by 50 cm or more around the wetland, 3-year-old Tsuga orientalis container seedlings with a height of 2.5 m or more are planted at a row spacing of 4 m and a plant spacing of 3 m, with 54-56 plants per mu (preferably 55 plants) per mu. Three rows of buffer zones are arranged along the water level line, and the row spacing is gradually reduced to 2 m, forming a "sparse outside and dense inside" permeable forest belt. This not only ensures light penetration, but also builds stable carbon through the rapid growth characteristics. According to estimates, the carbon storage of a 5-year-old Tsuga orientalis forest vegetation can reach 12-15 t / hm², and the annual increase of soil organic carbon is more than 40% higher than that of pure native forests.

[0016] (2) Mixed planting of native associated species: Plant 1 native tree species every 7-9 m (preferably 8 m) in the Tsuga orientalis forest belt, and the proportion of native tree species should not exceed 20% of the total woody plants.

[0017] Further, when the native associated species are mixed, at least one of the water-tolerant willow and Tsuga pondii is selected.

[0018] Through reasonable configuration, the interspecific ecological niche is complementary, effectively relieving the intraspecific competition pressure of Tsuga orientalis, not only relieving the interspecific competition pressure of Tsuga orientalis, but also using the developed root system of willow and Tsuga pondii to fix soil and conserve water, using fallen leaves to supplement soil nutrients, improving soil structure, optimizing carbon and nitrogen cycles, and reducing the risk of decline of single tree species carbon sink function.

[0019] B, associated water-loving shrubs

[0020] (1) Transition area between woody framework layer and herbaceous purification layer

[0021] Between the Tsuga orientalis forest belt and the emergent plant belt, a transition area with a width of 2-3 m is developed, and "small leaf mosquito mother + fine leaf water group flower + gold calyx rhododendron" is mixed and planted, with a planting ratio of 2.8-3.2:2.8-3.2:2 (preferably 3:3:2); triangular planting method is adopted, and the plant spacing is controlled at 1.5-2 m. Small leaf mosquito mother is planted near the Tsuga orientalis forest belt, using its root system to stabilize the soil and prevent soil erosion under the Tsuga orientalis forest; fine leaf water group flower is in the middle, playing a role in absorbing water pollutants, and attracting insects and birds; gold calyx rhododendron is planted near the emergent plant belt, with its bright flowers to improve the landscape ornamental of the wetland, and at the same time improve the soil microenvironment.

[0022] (2) Edge area of hygrophytic herbaceous belt (part of herbaceous purification layer)

[0023] On the outside edge of the hygrophytic herbaceous belt, a cluster of fine leaf water group flowers is planted every 4-5 m, with 3-5 plants per cluster, forming a discontinuous shrub buffer zone. The root system of fine leaf water group flower can further reinforce the soil and reduce the damage of rainwater erosion to the soil of wetland, while its fruits and flowers provide food and habitat for birds, enhancing the biodiversity of wetland ecosystem.

[0024] (3) Small and micro wetland slope area

[0025] In the relatively gentle area with a slope less than 30°, small leaf mosquito mother and gold osmanthus are mainly planted.

[0026] Further, in the small and micro wetland slope area, small leaf mosquito mother is densely planted with a plant spacing of 1.2 m x 1.2 m, and gold osmanthus is planted every 3-4 m with one plant. The developed root system of small leaf mosquito mother can effectively prevent soil erosion and slope collapse; the growth of gold osmanthus can increase the slope vegetation coverage and beautify the slope landscape, and at the same time improve the slope soil conditions.

[0027] C. Key technology adaptation

[0028] Before the planting of the main tree species of the east spruce forest belt and the local associated woody plants (trees / shrubs), the "ecological hole improvement technology" is used: a planting hole with a depth of 70-80 cm and a width of 50-60 cm is dug, and the bottom is filled with more than 20 cm of a mixture of sawdust and local humus soil (as a carbon source base), the middle layer is a mixture of "local red soil + rotten straw" (preferably a mixture of local red soil and rotten straw with a volume ratio of 6-7:3), and the middle layer is added with 4-5% of superphosphoric acid (as an improver, aiming at the problem of insufficient phosphorus in Hunan red soil) corresponding to the dry weight of the middle layer, and the surface is covered with 8-12 cm (preferably 10 cm) of aquatic plant residues. Improve the planting efficiency of woody plant root system and the starting speed of carbon sink.

[0029] Herbaceous plants only need to cover the surface of the planting area with 5-8 cm of aquatic plant residues (simplified surface treatment). Because the herbaceous plant root system is shallow (mostly concentrated in the 0-20 cm soil layer), and the phosphorus demand is lower than that of woody plants, the surface phosphorus of Hunan red soil can basically meet the growth of herbaceous plants, and deep improvement is not needed.

[0030] (2) Construction of herbaceous purification layer: pollution interception and carbon sink supplement

[0031] A, configuration combination

[0032] (1) Emergent plant zone (water level 0-30 cm): In the area extending 5-8 m from the edge of the Taxodium distichum forest, a mixed planting mode of "Iris pseudacorus + Alisma orientale + Iris pseudacorus + Zephyranthes grandiflora" is adopted, with a ratio of 2.8-3.2:1.8-2.2:1.8-2.2:3 (preferably 3:2:2:3). The plant spacing is adjusted to (30-40 cm) x (40-50 cm) (preferably 35 cm x 45 cm). Iris pseudacorus and Zephyranthes grandiflora, as the main nitrogen and phosphorus absorbing plants, are distributed on the side close to the water body, fully exerting their purification capacity. Alisma orientale is interspersed in the middle position to absorb heavy metals and part of the nutrient salts. Iris pseudacorus is planted on the side close to the wetland herb zone, which can not only purify water quality but also beautify the wetland landscape and attract biological habitat.

[0033] (2) Wetland herb zone (water level -10-0 cm): A 2.8-3.2 m (preferably 3 m) wide buffer zone is set inside the emergent plant zone, with Lemna as the main plant, and Typha (preferably a planting ratio of 3.5-4:1). The compact plant morphology and developed root system of Lemna can effectively intercept sediment and pollutants in surface runoff, while increasing the surface vegetation coverage of the wetland. Typha serves as a landscape embellishment, and together they form a "biological filter net". In addition, the combination of Lemna and Typha can provide low-lying foraging and hiding places for birds.

[0034] B. Dynamic management strategy

[0035] Every autumn, 1 / 3-1 / 2 of the above-ground part of the emergent plants is harvested (leaving 10-15 cm of stem), and the harvested material is crushed and mixed with Taxodium distichum leaves for composting to produce organic substrate for the wetland, achieving carbon element closed-loop recycling and avoiding carbon loss caused by traditional harvesting.

[0036] (Three) Construction of aquatic buffer layer: ecological connectivity and carbon pool stability

[0037] A. Submerged-flooding leaf plant configuration

[0038] Submerged plant group (water level 30-100 cm): Choose local Vallisneria, Hydrilla verticillata, use "seeding + cutting" combination, cover degree control in 40%-50%, its root system can fix the bottom mud carbon (reduce organic carbon resuspension), leaf released allelochemicals can inhibit the growth of algae, alleviate eutrophication.

[0039] Floating leaf plant embellishment (water level 20-50 cm): Plant 1 cluster of Nymphaea or Trapa bispinosa every 8-10 m, with an area of no more than 1 m², to avoid shading the submerged plants from light, while providing egg-laying sites for aquatic insects and enhancing the complexity of the ecosystem.

[0040] B. Microbial synergistic reinforcement

[0041] In the root zone of aquatic plants, "functional bacteria agent slow-release balls" are placed, 3-5 per square meter. Through plant root exudates to activate the activity of the bacteria agent, both to improve the total phosphorus removal rate (25% higher than pure plant repair) and to inhibit carbon emissions (including CO2 and CH4, reducing indirect losses of carbon pools), forming a "carbon sequestration-emission reduction" double effect with the woody layer.

[0042] The functional bacteria agent slow-release ball is a biological bacteria agent for lake ecological restoration, produced and sold by Hangzhou Mamba Environmental Protection Co., Ltd.

[0043] (Four) Key technology of ecological coupling

[0044] A, water level dynamic control: through the micro dam, the water level of the wetland is controlled at "flood period ≤80cm, dry period ≥20cm", which guarantees the normal respiration of the Taxodium distichum knee-shaped roots, provides suitable habitat for herbaceous and aquatic plants, and maintains the stability of carbon sink function.

[0045] B, carbon sink monitoring linkage: biomass monitoring sample plots are set up in the woody layer and herbaceous layer respectively, the diameter at breast height of woody plants and herbaceous biomass are measured every quarter, combined with soil profile carbon content (0-60cm layered sampling), a "vegetation carbon-soil carbon" double pool accounting system is constructed, and the carbon sink efficiency of the mode is accurately tracked.

[0046] Therefore, the technical problem to be solved by the present application is: how to deeply analyze the problems of single plant configuration mode, unclear microbial ecological restoration mechanism and inaccurate ecological system monitoring in wetland ecological restoration and wetland carbon sink improvement technology. Specifically, it includes: how to scientifically construct the vertical ecological structure of "woody framework layer + herbaceous purification layer + aquatic buffer layer", realize the functional cooperation between plants, realize the functional cooperation of woody plants and native plants in pollutant treatment, carbon sink capacity and landscape creation; systematically study the plant root microbial community, clarify the interaction mechanism of plant root exudates and microbial agent, form a "carbon sequestration-emission reduction" double effect through domestication and directional placement of specific bacteria; design 24-hour monitoring equipment suitable for the ecological characteristics of small and micro wetlands, realize long-term and accurate monitoring of small and micro wetland ecological system, and finally realize the improvement of hydrological connectivity of subtropical small and micro wetlands, effective pollution control, and enhancement of carbon pool stability, to achieve the goal of ecological restoration and carbon sink efficiency.

[0047] The present application belongs to the technical field of wetland ecological restoration and carbon sink enhancement, and specifically relates to an ecological restoration and carbon sink enhancement method for subtropical small and micro wetlands (including ponds, pits, small riverbank wetlands, etc., usually <10 hectares in area). In view of the problems of weak hydrological connectivity, vulnerability to agricultural non-point source pollution (total phosphorus exceeding standard is a significant problem), poor carbon pool stability, etc. in small and micro wetlands, taking carbon sink enhancement as the core, ecological adaptation as the basis and functional synergy as the target, a vertical ecological structure of a "woody framework layer + herbaceous purification layer + aquatic buffer layer" is constructed, and Chinese fir and local plants are introduced for reasonable matching, so as to balance the carbon sink capacity and ecological safety. Microbial reinforcement technology is integrated to improve the ecological environment of small and micro wetlands, enhance the self-purification capacity and carbon sequestration efficiency of the wetland system, and enhance the carbon sink function.

[0048] The present application belongs to the technical field of environmental engineering, specifically relates to the sub-field of water pollution control and ecological restoration, and focuses on the research and development of artificial wetland simulation test equipment and ecological purification technology. The technical boundary of the present application extends to the following cross-field:

[0049] 1. Ecological effect research field of complex pollutants: for the complex scene of coexistence of nitrogen, phosphorus, heavy metals and organic pollutants in small and micro wetlands, environmental chemical analysis technology is used to analyze the migration and transformation law of pollutants, and pollution ecology method is used to explore the ecological toxicity effect, so as to provide theoretical basis for formulating accurate ecological restoration strategy;

[0050] 2. Plant-microorganism interaction ecological restoration technology field: the woody framework layer takes the hybrid offspring (preferably Chinese fir 302, 118 clone) of Tsuga and Taxodium mucronatum as the carbon sink core and habitat support, which has the advantages of water tolerance, salt and alkali tolerance and fast growth, and is configured with the associated water-loving shrubs Viburnum betulifolium, Hibiscus mutabilis, Rhododendron fortunei and the herbaceous purification layer Eustylis, Alisma orientale, Nymphoides peltatum, Iris halophila, Impatiens walleriana and Typha angustifolia, which improves the ornamental nature of the wetland on the basis of pollution interception and carbon sink supplement, and is suitable for ecological restoration and function improvement of small and micro wetlands.

[0051] 3. In-situ observation and culture of root microbial community by using microbial ecology method, and "functional bacteria agent slow-release ball" is put into the root zone of aquatic plants, which activates the activity of the agent through plant root exudates, improves the nitrogen and phosphorus removal rate, and inhibits carbon emission, forming a "carbon sequestration-emission reduction" dual effect with vegetation carbon sink.

[0052] 4. For the monitoring needs of small and micro wetland plant whole growth cycle and long-term pollution purification process, water quality monitoring equipment suitable for small and micro wetlands is set up to realize long-term and accurate monitoring of the dynamic changes of the wetland ecological system, and provide data support for ecological restoration technology optimization and carbon sink enhancement research.

[0053] The present application has the following advantages:

[0054] (1) Environmental benefits are improved: When traditional small and micro wetland restoration technology uses single plant restoration, the average annual carbon sequestration is about 3-5 t CO2 / (hm²·a), and the total phosphorus removal rate is less than 40%. The present application uses the carbon sink purification landscape synergy core technology, uses Cunninghamia lanceolata as the main body of the arbor layer, and simultaneously matches water-loving shrubs and local herbs to form an "arbor-shrub-grass" ecological restoration network, and the combined annual carbon sequestration reaches 8-10 t CO2 / (hm²·a), which is 60%-100% higher than traditional technology; combined with the root zone microbial functional agent slow-release ball, the wetland ecosystem annual carbon emission is reduced by 40%-50% compared with traditional restoration, the nitrogen and phosphorus removal rate reaches more than 60%, the lead and cadmium concentration is reduced by 60%, and the COD (chemical oxygen demand) is reduced by more than 70%, which meets the multiple function requirements of small and micro wetlands "pollution control + sequestration + emission reduction + landscape", and greatly improves the environmental benefits of wetland ecological restoration.

[0055] (2) The stability of the ecological system is enhanced: The traditional wetland restoration has simple community structure, and the biological diversity index is only 1.2-1.5, and the ecological system stability is poor. The ecological community optimization construction technology of the present application uses Cunninghamia lanceolata as the local dominant woody plant, and scientifically mixes and plants other local tree species to construct a multi-level community structure. After monitoring, the biological diversity index of the wetland ecological system is increased to 2.8-3.2 after using the present technology, and the increase is more than 100%, which creates a diversified habitat for birds, insects and other organisms. At the same time, the self-regulation ability of the ecological system is significantly enhanced, and the annual fluctuation range of the carbon sink function of Cunninghamia lanceolata is reduced from 15%-20% of the traditional restoration to 5%-8%, which effectively guarantees the continuous and stable play of the carbon sink function, and overcomes the disadvantages of the unreasonable community structure of the traditional restoration.

[0056] (3) Cost control and sustainable development: In the traditional small and micro wetland restoration, the cost of seedling accounts for 40%-50% of the total investment, the cost of waste treatment accounts for 15%-20%, and the ecological value is difficult to realize. The low-cost high-benefit implementation technology of the present application is based on more than 60% of local species, combined with the high survival rate (survival rate is more than 90%) of Cunninghamia lanceolata cutting seedling technology, so that the cost of seedling is reduced by 40% compared with the traditional one. The "wetness for wetness" composting cycle mode is introduced, the wetland waste resource utilization is realized, the waste treatment cost is reduced to less than 5%, and the overall restoration cost is reduced by 30% compared with the traditional one. In the future, through the construction of carbon sink trading system, according to the current carbon sink market price, each hectare of wetland can realize carbon sink economic income of about 3000-5000 yuan per year, forming a sustainable mode of "ecological restoration-carbon sink production-value realization", effectively solving the problems of high cost, resource waste and low economic benefit of traditional restoration, and providing a replicable innovation path for small and micro wetland restoration.

[0057] Advantages of the present application:

[0058] (1) Carbon sink, purification and landscape synergy: creatively combine the high carbon sink characteristics of Cunninghamia lanceolata, the ornamental characteristics of shrubs, and the purification function of local herbs, and cooperate with the root zone microbial ecological technology to build a "arbor-shrub-grass" three-dimensional coupled ecological restoration network. Cunninghamia lanceolata as the main body of the arbor layer, with its efficient photosynthesis and biomass accumulation ability, becomes the main force of carbon sink in small and micro wetlands; the microbial functional bacteria agent slow-release ball rich in functional bacteria such as oxidizing bacteria is put in the root zone, and the oxidizing bacteria can target the decomposition of organic carbon in the wetland water, and through oxidation, it is converted into microbial biomass or stable humus, rather than released into the atmosphere in the form of carbon dioxide, at the same time, the oxidizing bacteria inhibit the activity of carbon-producing microorganisms such as methanogens through competitive inhibition, reducing the emission of greenhouse gases such as methane; combined with local herbaceous plants, a pollution purification network is formed; at the same time, the shrub layer has ornamental characteristics, which can beautify the wetland landscape and meet the multiple functional needs of small and micro wetlands "pollution control + carbon sink and emission reduction + landscape", this combination technology provides a new path for wetland ecological restoration.

[0059] (2) Ecological community optimization construction technology: Cunninghamia lanceolata is used as the local dominant woody plant, and is scientifically mixed with local tree species such as willow and metasequoia to build a multi-level and stable wetland plant community structure. According to the ecological needs of small and micro wetlands, the proportion of Cunninghamia lanceolata and other species is reasonably planned to give full play to the leading role of Cunninghamia lanceolata in the community, while creating a diversified habitat for birds, insects and other organisms, and improving the biodiversity and self-regulation ability of the wetland ecosystem. Through this ecological community optimization construction method, the stability of the wetland ecosystem is enhanced, and the carbon sink function of Cunninghamia lanceolata is ensured to be continuously and stably exerted. This community construction mode has unique innovation and practicality.

[0060] (3) Balance of cost and benefit: based on local species (accounting for more than 60%), combined with Cunninghamia lanceolata cutting seedling technology (survival rate above 90%), and the introduction of "wetness for wetness" composting cycle mode, the cost is reduced by 30% compared with traditional restoration. In the future, through the construction of carbon sink trading system, the carbon sequestration capacity of Cunninghamia lanceolata can be converted into economic value, forming a sustainable mode of "ecological restoration-carbon sink production-value realization". This low-cost and high-yield technical implementation path has unique innovation and replicability. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 Planting schematic diagram for the plants of Example 1;

[0062] Figure 2The plane view for the plant configuration of Example 1; 1 is Iris pseudacorus + Alisma orientale + Sagittaria trifolia + Alisma orientale, 2 is Typha angustifolia + Iris pseudacorus + Alisma orientale + Nymphaea tetragona + Trapa bispinosa + Nymphoides peltatum, 3 is Iris pseudacorus + Alisma orientale + Nymphaea tetragona + Trapa bispinosa, 4 is natural revetment, 5 is Sagittaria trifolia + Alisma orientale + Vallisneria denseserrulata + Myriophyllum aquaticum + Nymphaea tetragona + Trapa bispinosa, 6 is Salix matsudana, 7 is Rhododendron calocodon, 8 is Abies firma forest belt, 9 is Alisma orientale + Sagittaria trifolia + Vallisneria denseserrulata, 10 is Acorus gramineus var. gramineus + Nymphoides hydrophylla var. gracilis;

[0063] Figure 3 The schematic diagram for the slow-release ball effect of the functional microbial agent of Example 1;

[0064] Figure 4 The comparison diagram before and after the transformation of Example 1. DETAILED DESCRIPTION

[0065] The application will be further described in detail below in combination with specific examples.

[0066] Example 1

[0067] A method for repairing small and micro wetlands by a three-dimensional coupled plant configuration mode, specifically comprising the following steps:

[0068] (I) Construction of the woody framework layer: construction of carbon sink core and habitat support by matching arbor, shrub and grass

[0069] 1. Configuration of main tree species

[0070] (1) Gradient planting of Abies firma: 3-year-old Abies firma container seedlings are planted in the land transition zone around the wetland with an elevation of more than 50 cm above the normal water level, 55 seedlings per mu; three buffer zones are set along the water line, and the row spacing is gradually reduced to form a "sparse outside and dense inside" permeable forest belt;

[0071] When the Abies firma gradient is planted, 3-year-old Abies firma container seedlings with a height of more than 2.5 m are planted in the land transition zone around the wetland with an elevation of more than 50 cm above the normal water level, 55 seedlings per mu; three buffer zones are set along the water line, and the row spacing is gradually reduced to 2 m to form a "sparse outside and dense inside" permeable forest belt. It not only guarantees the light penetration, but also constructs stable carbon through its rapid growth characteristics. According to the measurement, the carbon storage of 5-year-old Abies firma forest vegetation under this density can reach 12-15 t / hm², and the annual increase of soil organic carbon is more than 40% higher than that of pure native forest.

[0072] (2) Mixed planting of native associated tree species: 1 native tree species is planted every 8 m in the Abies firma forest belt, and the proportion of native tree species does not exceed 20% of the total woody plants.

[0073] When the native associated tree species are mixed, the native tree species are selected as water-tolerant Salix matsudana and Taxodium ascendens; the ratio of Salix matsudana to Taxodium ascendens is 1:1.

[0074] Through reasonable configuration, the interspecific ecological niche is complementary, which effectively relieves the intraspecific competition pressure of Cunninghamia lanceolata, and also relieves the interspecific competition pressure of Cunninghamia lanceolata. Through the developed root system of willow and pool cypress, the fallen leaves supplement soil nutrients, improve soil structure, optimize carbon and nitrogen cycle, and reduce the risk of decline of carbon sink function of single tree species.

[0075] 2. Associated water-loving shrubs

[0076] (1) Transition area between woody framework layer and herb purification layer

[0077] In the transition area between Cunninghamia lanceolata forest belt and emergent plant belt, a width of 2-3m transition area is opened up, and "small leaf mosquito mother + fine leaf water group flower + gold calyx rhododendron" is mixed and planted, and the planting proportion is 3:3:2; Triangle planting method is adopted, and the plant spacing is controlled at 1.5-2m. Small leaf mosquito mother is planted near Cunninghamia lanceolata forest belt, which uses its root system to stabilize soil and prevent soil erosion under Cunninghamia lanceolata; Fine leaf water group flower is in the middle, which plays a role in absorbing water pollutants and attracting insects and birds; Gold calyx rhododendron is planted near the emergent plant belt to improve the soil microenvironment with its bright flowers.

[0078] (2) Edge area of hygrophyte belt

[0079] On the outside edge of the hygrophyte belt (mainly with Potamogeton and Typha), a cluster of fine leaf water group flowers is planted every 4-5m, with 3-5 plants per cluster, forming a discontinuous shrub buffer zone. The root system of fine leaf water group flower can further reinforce the soil and reduce the damage of rainwater erosion to the soil of wetland, while its fruits and flowers provide food and habitat for birds, enhancing the biodiversity of wetland ecosystem.

[0080] (3) Small and micro wetland slope area

[0081] In the relatively gentle area with a slope of less than 30°, small leaf mosquito mother and gold calyx rhododendron are mainly planted.

[0082] In the small and micro wetland slope area, small leaf mosquito mother is densely planted with a plant spacing of 1.2m x 1.2m, and gold calyx rhododendron is planted every 3-4m with one plant. The developed root system of small leaf mosquito mother can effectively stabilize the soil and prevent slope collapse; the growth of gold calyx rhododendron can increase the vegetation coverage of the slope, beautify the slope landscape, and at the same time improve the soil conditions of the slope.

[0083] 2. Key technology adaptation

[0084] The main tree species of Cunninghamia lanceolata forest belt and local associated woody tree species (arbor / shrub) are planted by using "ecological hole improvement technology" before planting: digging a planting hole with a depth of 80 cm and a width of 60 cm, filling the bottom layer with more than 20 cm of mixed material of sawdust and local humus soil (as carbon source base), the middle layer is made of "local red soil + rotten straw" mixture (the volume ratio of local red soil to rotten straw is 7:3), and the middle layer is added with 5% of superphosphoric acid calcium (as an improver, aiming at the problem of insufficient phosphorus in Hunan red soil) of the dry weight of the middle layer, and the surface layer is covered with 10 cm of aquatic plant residues. The root planting efficiency of woody plants and the starting speed of carbon sink are improved.

[0085] The herbaceous plants only need to cover the surface layer of the planting area with 5-8 cm of aquatic plant residues (simplified surface layer treatment). Because the herbaceous plant root system is shallow (mostly concentrated in the 0-20 cm soil layer), and the phosphorus demand is lower than that of woody plants, the surface layer phosphorus of Hunan red soil can basically meet the growth of herbaceous plants, and there is no need for deep improvement.

[0086] (II) Construction of herbaceous purification layer: pollution interception and carbon sink supplement

[0087] 1. Configuration combination

[0088] (1) Emergent plant zone (water level 0~30cm): along the Cunninghamia lanceolata forest edge extending 5~8m area, using "Salvinia natans + Alisma orientale + Iris pseudacorus + Impatiens balfourii" mixed planting mode, staggered planting according to the ratio of 2.8-3.2:1.8-2.2:1.8-2.2:3 (preferably 3:2:2:3), and the plant spacing is adjusted to (30-40cm)×(40-50cm) (preferably 35cm×45cm). Salvinia natans and Impatiens balfourii are the main nitrogen and phosphorus absorbing plants, which are distributed on the side close to the water body, fully exerting their purification capacity; Alisma orientale is planted in the middle position to absorb heavy metals and part of nutrient salts; Iris pseudacorus is planted on the side close to the wetland herb zone, which can not only purify water quality, but also beautify the wetland landscape and attract biological habitat.

[0089] (2) Wetland herb zone (water level -10~0cm): a 2.8-3.2m (preferably 3m) wide buffer zone is set inside the emergent plant zone, with Lemna as the main plant, and Typha (preferably Lemna and Typha planting ratio of 3.5-4:1). The compact plant form and developed root system of Lemna can effectively intercept the sediment and pollutants in surface runoff, and increase the surface vegetation coverage of wetland; Typha forms a landscape ornament, and the two together form a "biological filter net". In addition, the combination of Lemna and Typha can provide low-lying foraging and hiding places for birds.

[0090] 2. Dynamic management strategy

[0091] Every autumn, 1 / 3-1 / 2 of the above-ground part of the emergent plants is harvested (10-15 cm of stem is reserved), and the harvested plants are crushed and mixed with fallen leaves of Cunninghamia lanceolata to make organic substrate for the wetland, realizing carbon element closed-loop circulation and avoiding carbon loss caused by traditional harvesting.

[0092] (Three) Construction of aquatic buffer layer: ecological connectivity and carbon pool stability

[0093] 1. Submerged-floater plant configuration

[0094] Submerged plant group (water level 30-100 cm): local cattail and black algae are selected, and a combination of "seeding + cutting" is used, and the coverage is controlled at 40%-50%, the root system can fix the carbon in the sediment (reduce the resuspension of organic carbon), and the allelochemicals released by the leaves can inhibit the growth of algae and alleviate eutrophication.

[0095] Floater plant decoration (water level 20-50 cm): plant 1 cluster of water lily or water caltrop every 8-10 m, and the area of each cluster is not more than 1 m², which can avoid shading the light of submerged plants, and at the same time provide a place for water insects to lay eggs and enhance the complexity of the ecological system.

[0096] 2. Microbial synergistic reinforcement

[0097] "Functional bacteria slow-release balls" are thrown in the root zone of aquatic plants, 3-5 per square meter. The functional bacteria slow-release balls contain Bacillus group, nitrifying bacteria, methanotrophs, photosynthetic bacteria, and blue-green algae control bacteria complex bacteria. Through plant root exudates to activate the activity of the bacteria, not only to improve the total phosphorus removal rate (25% higher than pure plant repair), but also to inhibit carbon emissions (including CO2 and CH4, reduce indirect loss of carbon pool), and form a "carbon sequestration-emission reduction" double effect with the woody layer.

[0098] The functional bacteria slow-release balls are river and lake ecological restoration biological bacteria produced and sold by Hangzhou Manba Environmental Protection Co., Ltd.

[0099] (Four) Key technologies of ecological coupling

[0100] 1. Dynamic control of water level: The water level of the wetland is controlled at "≤80 cm in flood season and ≥20 cm in dry season" through a micro-dam, which ensures the normal respiration of Cunninghamia lanceolata knee roots and provides suitable habitats for herbaceous and aquatic plants, and maintains the stability of carbon sink function.

[0101] 2. Carbon sink monitoring linkage: Biomass monitoring sample plots are set up in the woody layer and herbaceous layer, respectively, and the diameter at breast height of woody plants and herbaceous biomass are measured every quarter, combined with soil profile carbon content (0-60 cm layered sampling), to build a "vegetation carbon-soil carbon" double pool accounting system, and accurately track the carbon sink performance.

[0102] Advantages of the embodiment:

[0103] (1) Environmental benefits are improved: When traditional small and micro wetland restoration techniques use single plant restoration, the average annual carbon sequestration is about 0.5-1.0 t / hm2, and the total phosphorus removal rate is less than 40%. The present application uses carbon sink purification landscape synergy core technology, uses Cunninghamia lanceolata as the main body of the arbor layer, and simultaneously matches with water-loving shrubs and local herbs to form an "arbor-shrub-grass" ecological restoration network, and the combined annual carbon sequestration reaches 2.0-2.5 t / hm2, which is 60%-100% higher than that of traditional techniques; in combination with the root zone microbial functional agent slow-release ball, the annual carbon emission of the wetland ecosystem is reduced by 40%-50% compared with traditional restoration, the nitrogen and phosphorus removal rates reach more than 60%, the cadmium concentration is reduced by 80%, and the COD (chemical oxygen demand) is reduced by more than 70%, meeting the multiple functional requirements of small and micro wetlands "pollution control + carbon sequestration and emission reduction + landscape", and greatly improving the environmental benefits of wetland ecological restoration. The comparative analysis results of carbon sequestration monitoring before and after restoration are shown in Table 1. The comparative analysis results of water quality monitoring before and after restoration are shown in Table 2. Table 1 Comparative analysis of carbon sequestration monitoring before and after restoration

[0104]

[0105]

[0106] Note: The natural accumulation of soil organic carbon needs to go through a complete cycle from vegetation growth to litter decomposition, and finally the transformation process is completed by microorganisms. In addition, 1-year-old Cunninghamia lanceolata is in the seedling stage, and the root system and canopy are not fully developed, and the litter input is only 15%-20% of that of mature plants (5-year-old), which cannot provide sufficient carbon source for the soil. At the same time, it takes 2-3 years for the microbial community to adapt to the improved soil environment and form high-efficiency carbon assimilation capacity, so the contribution of natural carbon accumulation within 1 year is weak, and the improvement of organic carbon mainly depends on the input of exogenous substrate.

[0107] Table 2 Comparative analysis of water quality monitoring before and after restoration

[0108]

[0109] (2) The stability of the ecological system is enhanced: Traditional wetland restoration has simple community structure and a biological diversity index of only 1.2-1.5, and the ecological system stability is poor. The ecological community optimization and construction technology of the present application uses Cunninghamia lanceolata as the local dominant woody plant, and scientifically mixes and plants other local tree species to construct a multi-level community structure. Through monitoring, the biological diversity index of the wetland ecological system after using the present technology is increased to 2.8, with an increase of more than 100%, creating a diversified habitat for birds, insects and other organisms. At the same time, the self-regulation ability of the ecological system is significantly enhanced, and the annual fluctuation range of the carbon sequestration function of Cunninghamia lanceolata is reduced from 15%-20% to 8%-10%, effectively guaranteeing the continuous and stable exertion of the carbon sequestration function, and overcoming the disadvantages of the unreasonable community structure of traditional restoration. The comparative analysis results of biological diversity monitoring before and after restoration are shown in Table 3.​​

[0110] Table 3 Comparison and analysis of biodiversity monitoring before and after repair

[0111]

[0112] (3) Cost control and sustainable development: In traditional small and micro wetland restoration, the cost of seedlings accounts for 40% to 50% of the total investment, and the cost of waste treatment accounts for 15% to 20%, and the ecological value is difficult to realize. The low-cost and high-benefit implementation technology of the invention is based on more than 60% of local species, combined with the high survival rate (survival rate of more than 90%) of Cunninghamia lanceolata cutting seedling technology, which reduces the cost of seedlings by 40% compared with the traditional method. The introduction of the "wetness for wetness" composting cycle mode realizes the resource utilization of wetland waste, reduces the cost of waste treatment to less than 5%, and reduces the overall repair cost by 30% compared with the traditional method. In the future, by constructing a carbon sink trading system, according to the current carbon sink market price, each hectare of wetland can realize carbon sink economic income of about 3000-5000 yuan per year, forming a sustainable mode of "ecological restoration-carbon sink production-value realization", effectively solving the problems of high cost, resource waste and low economic benefit in traditional repair, and providing a replicable innovation path for small and micro wetland repair.

[0113] Table 4 Plant list

[0114]

Claims

1. A method for restoring small wetlands using a three-dimensional coupled plant configuration pattern, characterized in that, Specifically, the following steps are included: (I) Construction of the woody framework layer: The combination of trees, shrubs and grasses to construct the carbon sink core and habitat support A. Main tree species configuration (1) Gradual planting of Oriental pine: 3-year-old container seedlings of Oriental pine are planted in the terrestrial transition zone around the wetland, with 50-60 seedlings per mu; 2-4 rows of buffer zone are set up along the water level line, and the row spacing is gradually reduced to form a "sparse outside and dense inside" permeable forest belt; (2) Mixed planting of native and associated tree species: One native tree species is planted at intervals of 7-9m in the Oriental fir forest belt, and the proportion of native tree species shall not exceed 20% of the total woody plants; B. Accompanying water-loving shrubs (1) Transition zone between woody framework layer and herbaceous purification layer Between the Oriental pine forest belt and the emergent plant belt, a transition zone with a width of 2-3m is opened up, and "small-leaved water lily + fine-leaved water lily + golden calyx rhododendron" are mixed-planted in a ratio of 2.8-3.2:2.8-3.2:2; a triangular planting method is adopted, and the spacing between plants is controlled at 1.5-2m. (2) Marginal area of ​​wetland herbaceous zone Plant a clump of small-leaved water clumps at intervals of 4-5m along the outer edge of the wetland herbaceous zone, with 3-5 plants in each clump, to form a discontinuous shrub buffer zone. (3) Small wetland slope area In areas with gentler slopes less than 30°, *Rhododendron simsii* and *Rhododendron simsii* should be planted as the main species. C. Key technology adaptation Before planting the main tree species, Oriental pine forest belt and native associated woody tree species, the "ecological pit improvement technology" is adopted: dig planting pits 70-80cm deep and 50-60cm wide, fill the bottom layer with a mixture of wood chips and local humus soil of more than 20cm, the middle layer base material is a mixture of "local red soil + decomposed straw", add superphosphate equivalent to 4-5% of the dry weight of the middle layer base material, and cover the surface with 8-12cm of aquatic plant residues; For herbaceous plants, only 5-8cm of aquatic plant residue needs to be covered on the surface of the planting area; (II) Construction of the Herbal Purification Layer: Pollution Interception and Carbon Sequestration Supplementation A. Configuration Combinations (1) Emergent plant zone, water level 0~30cm: In the area extending 5~8m inward from the edge of the Oriental fir forest, a mixed planting pattern of "pickpox + water plantain + yellow iris + canna lily" is adopted, and the plants are planted alternately in the ratio of 2.8-3.2:1.8-2.2:1.8-2.2:3, and the plant spacing is adjusted to (30-40cm)×(40-50cm). (2) Wetland herbaceous zone, water level -10~0cm: Set up a 2.8-3.2m wide buffer zone inside the emergent plants, with water lily as the main plant and cattail as the supplement; B. Dynamic Management Strategy Every autumn, 1 / 3 to 1 / 2 of the above-ground parts of emergent aquatic plants are harvested. The harvested material is crushed and mixed with fallen leaves of Oriental pine to make compost, which is then used as an organic substrate for wetland reuse. (III) Construction of aquatic buffer layers: ecological connectivity and carbon pool stability A. Submerged-floating plant arrangement Submerged plant communities, water level 30-100cm: Select native Vallisneria natans and Hydrilla verticillata, using a combination of sowing and cutting propagation, with coverage controlled at 40%-50%; Add floating-leaved plants to the water level at 20-50cm: plant a clump of water lilies or water chestnuts every 8-10m, with each clump not exceeding 1m² in area. B. Microbial synergistic enhancement Place "functional microbial agent slow-release balls" in the root zone of aquatic plants, 3-5 balls per square meter; The functional microbial agent slow-release balls are ecological restoration biological microbial agents, produced and sold by Hangzhou Mamba Environmental Protection Co., Ltd. (iv) Key technologies for ecological coupling A. Dynamic water level control: The wetland water level is controlled at "≤80cm during the wet season and ≥20cm during the dry season" through miniature sluice gates and dams; B. Carbon sequestration monitoring linkage: Biomass monitoring plots are set up in the woody and herbaceous layers respectively. The diameter at breast height of woody plants and the biomass of herbaceous plants are measured every quarter. Combined with the carbon content of soil profile, a dual-database accounting system of "vegetation carbon-soil carbon" is constructed to accurately track the carbon sequestration efficiency of the model.

2. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1, characterized in that, In step (1), during the construction of the woody framework layer, when planting Oriental pine in a gradient, in the terrestrial transition zone around the wetland where the elevation is more than 50cm above the normal water level, use 3-year-old Oriental pine container seedlings with a height of more than 2.5m to plant with a row spacing of 4m × plant spacing of 3m, planting 55 seedlings per mu; set up 3 rows of buffer zone along the water level line, and gradually reduce the row spacing to 2m to form a "sparse outside and dense inside" permeable forest belt.

3. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (1), when constructing the woody framework layer, if native companion tree species are mixed in, at least one of the following native tree species should be selected: water-resistant willow or pond cypress.

4. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (1), during the construction of the woody framework layer, one native tree species is planted every 8m in the Oriental pine forest belt.

5. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (1), the planting ratio of small-leaved water lily, fine-leaved water lily, and golden calyx rhododendron is 3:3:

2.

6. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (1), during the construction of the woody framework layer, in the small wetland slope area, *Rhododendron simsii* is densely planted at a spacing of 1.2m × 1.2m, and *Rhododendron simsii* is planted every 3-4m as a sparse addition.

7. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (1), during the construction of the woody framework layer, when adapting key technologies, the middle layer base material is a mixture of "local red soil + decomposed straw", with a volume ratio of local red soil to decomposed straw of 6-7:

3.

8. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (two), during the construction of the herbaceous purification layer, the emergent plant zone, with a water level of 0-30cm, extends 5-8m inward along the edge of the Oriental pine forest. A mixed planting pattern of "pickpox + water plantain + yellow iris + canna indica" is adopted, with staggered planting in a ratio of 3:2:2:3, and the plant spacing is adjusted to 35cm×45cm.

9. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (II) the construction of the herbaceous purification layer, the wetland herbaceous zone, with a water level of -10 to 0 cm, is set up with a 3m wide buffer zone inside the emergent plants, with water lily as the main plant and cattail as the main plant. The planting ratio of water lily to cattail is 3.5-4:

1.

10. The method for restoring small wetlands using a three-dimensional coupled plant configuration pattern according to claim 1 or 2, characterized in that, In step (two), during the construction of the herbaceous purification layer, 1 / 3 to 1 / 2 of the above-ground parts of the emergent plants are harvested every autumn, leaving 10-15cm of stems.

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