Stair division method and precise treatment method for spartina alterniflora area

Abstract

The invention relates to the technical field of spartina alterniflora management, in particular to a spartina alterniflora area cascade division method and a precise management method, and the method comprises the steps: determining the area change rate of each spartina alterniflora area; setting a plurality of sampling points, and obtaining parameters corresponding to the sampling points; assigning the parameter of each sampling point according to an assignment rule; calculating the treatment difficulty index of the spartina alterniflora, inputting the treatment difficulty index of each sampling point in geographic information system software, carrying out interpolation processing, drawing a treatment difficulty index contour line for an interpolated layer, carrying out treatment area division on each spartina alterniflora area according to the treatment difficulty index contour line, and carrying out treatment area division on each spartina alterniflora area. The treatment district division is used for guiding the selection of the most reasonable treatment measures. According to the method, the spartina alterniflora district is divided into different districts according to the treatment difficulty, and the different districts can be precisely treated by adopting the optimal process.

Description

Technical Field

[0001] The invention relates to the technical field of Spartina alterniflora control, and in particular to a Spartina alterniflora area ladder division method and a precise control method. Background Art

[0002] The treatment process of Spartina alterniflora can be mainly divided into physical method, chemical method and biological method. Physical method includes manual removal of seedlings, fabric covering, continuous mowing and flooding of dikes. Chemical method refers to the use of suitable herbicides for prevention and control, but chemical methods are usually toxic and may affect other animals and plants in the ecosystem, and even affect human health. Biological control of Spartina alterniflora refers to the use of natural enemies such as insects, fungi and pathogens to inhibit the growth and reproduction of Spartina alterniflora, or the use of other species to replace the Spartina alterniflora ecosystem, thereby curbing the outbreak of Spartina alterniflora populations. Among them, the role of natural enemies is complex, and they often threaten other non-targets (such as certain indigenous species). Therefore, the introduction of natural enemies may lead to new biological invasions and must be cautious.

[0003] Due to the stubbornness of Spartina alterniflora, it is difficult to control it. In the engineering projects for Spartina alterniflora control, two or even multiple methods have gradually developed and repeatedly implemented, such as mowing + tillage, mowing + tillage twice, mowing + shading, mowing + flooding, mowing + excavation, mowing + tillage + biological substitution, etc. The above different methods have different costs, good and bad control effects, and have different impacts on the local ecosystem. Generally speaking, the method with less impact on the local ecosystem and water and sand conditions and the lower economic cost is less effective in removing Spartina alterniflora. After cleaning, Spartina alterniflora is easy to relapse and difficult to cure; while the method that can completely remove Spartina alterniflora is often costly, and at the same time, it will cause more serious damage to the local ecosystem, or will cause a huge change in the water and sand conditions of the tidal flat. At present, there is a problem of blindness in the selection of Spartina alterniflora control measures, and even if it is Spartina alterniflora in an area, the habitats in different areas will show different suitability for the growth of Spartina alterniflora due to changes in parameters such as tidal flat elevation and sediment properties. The plant height and density of Spartina alterniflora are different, and the difficulty of control is also different. Adopting a control method will either not completely remove the high-suitable area of ​​Spartina alterniflora, or over-control the low-suitable area of ​​Spartina alterniflora, resulting in a waste of engineering costs and unnecessary damage to the local ecosystem or tidal flat terrain. Summary of the invention

[0004] The purpose of the present invention is to provide a method for tiered division of Spartina alterniflora regions and a precise control method in view of the defects of the prior art, wherein the Spartina alterniflora area is divided into different areas according to the difficulty of control, and the most suitable process is adopted for precise control in different areas, thereby solving the problems of incomplete removal, cost waste and unnecessary damage to the local ecosystem or tidal flat terrain caused by blind process selection in the current Spartina alterniflora control project.

[0005] In order to solve the above technical problems, in a first aspect, the present invention provides a method for dividing a Spartina alterniflora region into steps, comprising:

[0006] Determine the area change rate of each Spartina alterniflora patch;

[0007] Multiple sampling points were set up in the survey area of ​​each Spartina alterniflora patch to obtain the sediment pH value and total organic carbon content at each sampling point, and sample plots were set up at the sampling points to count the aboveground biomass and density of Spartina alterniflora in the sample plots corresponding to each sampling point;

[0008] According to the assignment rules, the area change rate, sediment pH value, sediment total organic carbon content, aboveground biomass and density of Spartina alterniflora of each sampling point are assigned values; wherein the area change rate of a sampling point is equal to the area change rate of the Spartina alterniflora patch corresponding to the sampling point;

[0009] The control difficulty index of Spartina alterniflora was calculated based on the area change rate, sediment pH value, sediment total organic carbon content, aboveground biomass of Spartina alterniflora and its density. The control difficulty index of each sampling point was input into the geographic information system software and interpolation was performed. The control difficulty index contour lines were drawn for the interpolated layer, and each Spartina alterniflora area was divided into control areas based on the control difficulty index contour lines. The control area division was used to guide the selection of the most reasonable control measures.

[0010] Furthermore, the method for calculating the control difficulty index of Spartina alterniflora includes:

[0011] According to the assigned values ​​of sediment pH value and sediment total organic carbon content, the index value for evaluating the growth suitability of Spartina alterniflora was calculated, the index value of each sampling point was input into the geographic information system software, and interpolation processing was performed, and the index value contour lines were drawn for the interpolated layer. According to the index value contour lines, each Spartina alterniflora area was divided into a low-suitability area for Spartina alterniflora, a medium-suitability area for Spartina alterniflora, and a high-suitability area for Spartina alterniflora, and the area proportion of the medium-suitability area for Spartina alterniflora and the high-suitability area for Spartina alterniflora in the area near each sampling point was calculated;

[0012] The control difficulty index of Spartina alterniflora corresponding to each sampling point was calculated based on the area change rate, sediment pH value, sediment total organic carbon content, the aboveground biomass and density of Spartina alterniflora, and the proportion of the area of ​​the medium suitable area and the high suitable area of ​​Spartina alterniflora in the area near the sampling point.

[0013] In some embodiments, the assignment rules include:

[0014] Area change rate (% / year): Area change rate ≤ 5%, assigned a value of 1; 5% < area change rate ≤ 10%, assigned a value of 5; area change rate > 10%, assigned a value of 10;

[0015] Sediment pH value: if the sediment pH value is ≤7.0 or the sediment pH value is >8.5, the value is 1; if the sediment pH value is 7.0 < ≤7.5 or the sediment pH value is 8.0 < ≤8.5, the value is 5; if the sediment pH value is 7.5 < ≤8.0, the value is 10;

[0016] Total organic carbon content of sediments: if the total organic carbon content of sediments is ≤0.15%, the value is 1; if the total organic carbon content of sediments is 0.15%<≤0.3%, the value is 5; if the total organic carbon content of sediments is >0.3%, the value is 10;

[0017] The aboveground biomass of Spartina alterniflora (kg / m2): aboveground biomass ≤ 0.8%, assigned a value of 1; 0.8 < aboveground biomass ≤ 1.6%, assigned a value of 5; aboveground biomass > 1.6%, assigned a value of 10;

[0018] The density of Spartina alterniflora (plants / m2): density ≤ 80, assigned a value of 1; 80 < density ≤ 150, assigned a value of 5; density > 150, assigned a value of 10.

[0019] Furthermore, the index value for evaluating the growth suitability of Spartina alterniflora = the assigned value of sediment pH + the assigned value of sediment total organic carbon content. The area with index value ≤3 is the low suitable area of ​​Spartina alterniflora, the area with index value 3<index value≤10 is the medium suitable area of ​​Spartina alterniflora, and the area with index value >10 is the high suitable area of ​​Spartina alterniflora.

[0020] Furthermore, the governance areas include easy governance areas, medium-difficulty governance areas, difficult governance areas, and extremely difficult governance areas;

[0021] The difficulty index of Spartina alterniflora control = area change rate value × 2 + aboveground biomass value × 2 + density value × 2 + sediment pH value value + sediment total organic carbon content value + percentage of medium suitable area of ​​Spartina alterniflora in the area near the sampling point × 10 + percentage of high suitable area of ​​Spartina alterniflora in the area near the sampling point × 20;

[0022] Areas with a governance difficulty index ≤31 are easy to govern, areas with a governance difficulty index of 31<≤54 are medium-difficulty governance areas, areas with a governance difficulty index of 54<≤77 are difficult to govern, and areas with a governance difficulty index of >77 are extremely difficult to govern.

[0023] In some embodiments, it includes: adjusting the scope of the divided governance area: replacing the arc boundary that protrudes toward the scope of the governance area with a higher governance difficulty index with a plurality of straightened line segments; replacing the arc boundary that protrudes toward the scope of the governance area with a lower governance difficulty index with a plurality of circumscribed line segments of the arc.

[0024] In some embodiments, the method for determining the area change rate of each Spartina alterniflora patch includes:

[0025] Collect satellite remote sensing images of the target area at present and one year ago, extract the distribution boundary and area information of the Spartina alterniflora patches in the two images, and calculate the area change rate of each Spartina alterniflora patch; among them, for the patches newly added within one year, the weighted average of the area change rates of the three patches closest to the newly added patch one year ago is taken as the area change rate of the newly added patch. That is, the area change rate of the newly added patch within one year is equal to the area change rate of the three nearest patches multiplied by the weights respectively, and the weight = the ratio of the area of ​​a certain nearest patch to the sum of the areas of the three nearest patches.

[0026] In some embodiments, the sampling points are arranged as follows: a square grid section is set in the survey area of ​​each Spartina alterniflora patch, the nodes of the grid are the sampling points, and the side length of the grid is 100 meters. For sections less than 300 meters in length, sampling points are set at both ends and at the trisection points of the section.

[0027] In a second aspect, the present invention provides a method for precise control of Spartina alterniflora, comprising:

[0028] For scattered distribution areas that cannot be identified by satellite remote sensing images and easy-to-control areas, manual removal is used for control;

[0029] For the medium-difficulty control areas, difficult-to-control areas, and extremely difficult-to-control areas, uniform mowing should be carried out to prevent the sexual reproduction of Spartina alterniflora;

[0030] After mowing, the medium-difficulty areas should be plowed once, and the difficult-to-control areas should be plowed twice at intervals. The plowing depth must ensure absolute destruction of the rhizomes of Spartina alterniflora. The extremely difficult-to-control areas should be treated by excavation and flooding.

[0031] Furthermore, the methods of excavation and flooding for the extremely difficult-to-control areas include:

[0032] The extremely difficult-to-control areas are divided into two types of treatment areas: excavation and flooding. The excavation treatment area is the area with beach elevation>H, and the flooding treatment area is the area with beach elevation≤H.

[0033] The soil within the depth h of the excavation treatment area shall be completely excavated to ensure that the excavation depth is greater than 1.5 times the depth of the root system of Spartina alterniflora. The excavated soil shall be used for the construction of the flooded dam and protective seawall;

[0034] Multiple dams are built in the flooding treatment area. The multiple dams divide the flooding treatment area into one or more closed areas. Water inlets are opened on the dams. When high tide comes, the water inlets are opened to replenish water to the closed areas. When the tide level drops, the water inlets are closed to store water. The flooding depth should be maintained at more than 60 cm and the time should be more than N months. If the natural tidal conditions cannot meet the flooding depth, a pump station needs to be set up to pump water to increase the flooding level;

[0035] After N months of flooding, the water in the enclosed area is drained, the water inlet is sealed, and the enclosed area is kept dry for n days for sunbathing to further inactivate plant residues.

[0036] The beneficial effects of the present invention are:

[0037] 1. The present invention sets sampling points, obtains the area change rate, sediment pH value, sediment total organic carbon content, aboveground biomass and density of Spartina alterniflora at each sampling point, and assigns values, thereby calculating the governance difficulty index of Spartina alterniflora, interpolating the governance difficulty index corresponding to each sampling point and drawing governance difficulty index contour lines, thereby dividing each Spartina alterniflora area, and can adopt appropriate processes according to the governance difficulty of different regions, thereby reducing damage to the ecological environment while ensuring the governance effect.

[0038] 2. The present invention uses the area proportion of the medium suitable area and the high suitable area of ​​Spartina alterniflora in the area near the sampling point as an influencing factor of the control difficulty index of Spartina alterniflora, thereby increasing the proportion of recurrence factors of Spartina alterniflora, making the division of different control difficulty areas of Spartina alterniflora more reasonable, which is beneficial to reducing the possibility of recurrence of Spartina alterniflora after control and improving the control effect.

[0039] 3. The present invention uses different processing methods according to the different protrusions of the arc boundary of the governance area. That is, if it protrudes to the governance area with a higher governance difficulty index, the arc boundary is replaced by a plurality of straightened line segments; if it protrudes to the governance area with a lower governance difficulty index, the arc boundary is replaced by a plurality of circumscribed line segments of the arc. Since the arc boundary is replaced by a straight line, it is beneficial to reduce the difficulty of the project and reduce the cost. In addition, by reducing the area of ​​the governance area with a low governance difficulty index and increasing the area of ​​the governance area with a high governance difficulty index, the simplification of the boundaries of different areas is achieved, thereby avoiding the problem that the governance area with a high governance difficulty index adopts the governance measures of the governance area with a low governance difficulty index, resulting in a decrease in the governance effect.

[0040] 4. For a section with a length of less than 300 meters, the present invention sets sampling points at both ends of the section and at the trisection points, thereby avoiding the situation in which insufficient sampling points in some Spartina alterniflora areas lead to untrue calculation results of the control difficulty index.

[0041] 5. The present invention uses manual removal for scattered distribution areas and easy-to-control areas; uniform mowing is performed for medium-difficulty control areas, difficult-to-control areas, and extremely difficult-to-control areas. After mowing, the medium-difficulty control areas are plowed once, the difficult-to-control areas are plowed twice at intervals, and the extremely difficult-to-control areas are treated by excavation and flooding. Targeted treatment processes are used for areas of different control difficulties, which ensures the treatment effect, reduces construction costs, and reduces damage to the ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of the ladder division and precise management of the present invention;

[0043] Figure 2 It is a schematic diagram of the embankment arrangement of a certain Spartina alterniflora area of ​​the present invention;

[0044] Figure 3 It is a cross-sectional view of the dam of the present invention.

[0045] Figure numerals: closed area 1, vertical embankment 2; parallel embankment 3; tidal ditch 4; land 5; sea 6; water inlet 7; pumping station 8; geotextile 9; soil 10. DETAILED DESCRIPTION

[0046] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] The tidal flats in a certain area of ​​the northern coastal zone of the Yellow River Delta were invaded by the invasive species Spartina alterniflora, and the Spartina alterniflora area tiered division method and precise control method of the present invention were used to clear it. Figure 1 As shown, including:

[0048] S1. Collect satellite remote sensing images of the target area at present and one year ago, extract the distribution boundary and area information of the Spartina alterniflora patches in the two images, and calculate the area change rate of each Spartina alterniflora patch. Before the implementation of the project, there were 15 tidal flats with a total area of ​​420hm2 in the project area. 2 Taking the area of ​​Spartina alterniflora one year ago as a reference, the growth rate of the 15 areas of Spartina alterniflora in the project area ranged from -1.56% to 18%, and there was no new area added within one year.

[0049] S2. The boundary of each Spartina alterniflora patch spreads outward by 50 meters as the boundary of the survey area. Multiple parallel and equally spaced sections are arranged in the survey area, and the distance between each two adjacent sections is set to 100 meters. Sampling points are arranged on each section, including equally spaced sampling points, and the distance between each two adjacent sampling points is set to 100 meters. Sections with a length of less than 300 meters are set with four sampling points at both ends and three equal points. A total of 736 sampling points are set in the project area.

[0050] S3, at each sampling point with 100cm 3 A soil ring cutter was used to sample soil sediments of 0 to 15 cm, and the pH value and total organic carbon content of the sediments were determined. The pH value of the sediments in the project area was between 7.84 and 8.57, and the total organic carbon content was between 0.031% and 0.604%. 1m×1m plots were set up at the sampling points in the Spartina alterniflora area, with a total of 492 plots (since the area of ​​the survey area is larger than that of the Spartina alterniflora area, plots only exist at the sampling points in the Spartina alterniflora area), and the aboveground biomass and density of the Spartina alterniflora in each plot were recorded. The aboveground biomass of Spartina alterniflora in the project area is between 0.12 and 4.99 kg / m 2 The density is between 7 and 289 plants / m 2 between.

[0051] S4. Assign values ​​to the parameters of each sampling point according to the assignment rules in the following table, where the area change rate is the area change rate of the Spartina alterniflora patch where the sampling point is located:

[0052]

[0053] S5, using the sum of the values ​​of the two parameters of sediment pH value and sediment total organic carbon content as an index for evaluating the suitability of Spartina alterniflora growth, that is, evaluating the suitability of Spartina alterniflora growth by the value of the value of the value of the value of the pH value of the sediment + the value of the total organic carbon content of the sediment. The index value of each sampling point is input in the geographic information system software, and interpolation is performed, and contour lines are drawn for the interpolated layer. The area with index value ≤3 is the low suitable area of ​​Spartina alterniflora, the area with 3<index value ≤10 is the medium suitable area of ​​Spartina alterniflora, and the area with index value>10 is the high suitable area of ​​Spartina alterniflora. The larger the proportion of the surrounding high suitable area, the greater the possibility of recurrence of plant tissues scattered in the surrounding area after the Spartina alterniflora spreads or is removed to the surrounding area, and the area proportion of the medium suitable area and the high suitable area in the 25-meter circular area around each sampling point is calculated.

[0054] The control difficulty index of Spartina alterniflora was calculated by “area change rate value × 2 + aboveground biomass value × 2 + density value × 2 + sediment pH value + sediment total organic carbon value + proportion of suitable areas in a 25-meter circular area around the sampling point × 10 + proportion of high-suitable areas in a 25-meter circular area around the sampling point × 20”. The control difficulty index of Spartina alterniflora at each sampling point was calculated in the geographic information system software. The control difficulty index of Spartina alterniflora within the scope of this project was between 18.74 and 100. The control difficulty index of Spartina alterniflora was interpolated within the distribution range of Spartina alterniflora, and contour lines were drawn for the interpolated layer. Areas with a control difficulty index ≤ 31 are easy-to-control areas, areas with a control difficulty index of 31 < ≤ 54 are medium-difficulty control areas, areas with a control difficulty index of 54 < ≤ 77 are difficult-to-control areas, and areas with a control difficulty index of > 77 are extremely difficult-to-control areas. The distribution areas of the above four types of areas in this project are 47.57 hm 2 、129.08hm 2 、59.40hm 2 、183.88hm 2 .

[0055] S6. The boundary lines directly divided according to the difficulty index of Spartina alterniflora control in this project are mostly arcs with many inflection points. If crawler harvesters, rotary tillers, and excavators are operated strictly according to the shapes of the contour lines during actual construction, it will be difficult and will slow down the construction progress and increase the construction cost, which is inconsistent with the purpose of reducing the impact of control measures on the local ecological environment and saving construction costs.

[0056] Therefore, the boundary lines of the four terraced areas were adjusted according to the terrain conditions. The arc boundaries that convexed toward a higher governance difficulty index range were directly replaced by straightening multiple line segments, and the arc boundaries that convexed toward a lower governance difficulty index were replaced by connecting multiple tangent line segments of the arc boundaries.

[0057] S7. The project carried out uniform mowing in the medium-difficulty control areas, difficult-to-control areas and extremely difficult-to-control areas from June 4 to June 27 to prevent the sexual reproduction of Spartina alterniflora. Crawler machinery was used to mow in order from low to high along the terrain, and mowing along the bottom of the Spartina alterniflora was controlled to control the stubble height to less than 10 cm. During the operation, manual measures were supplemented to mow in places where machinery could not mow. Mowing construction was arranged during the period of low tide and when the water depth was less than 40 cm at low tide. The cut Spartina alterniflora was piled up in the original area. Whenever the stacking area per acre reached 50m 2 When the operation is completed, the stacked Spartina alterniflora is transferred to the bank. After the operation is completed, the operation area is cleaned out in a unified and timely manner.

[0058] S8. From July 1 to July 14, the project used a boat-type rotary tiller to carry out the first tillage in the medium-difficulty and difficult-to-treat areas, with a tillage depth of about 30 cm, which inhibited the asexual reproduction of Spartina alterniflora and reduced the survival rate of Spartina alterniflora. For corners and other locations where machinery is difficult to operate, additional tillage was carried out manually.

[0059] S9. Based on the elevation and tidal conditions of the extremely difficult-to-control areas and from the perspective of construction cost, this project adopts the excavation technology for areas with beach elevation above 0.4 meters, and the enclosure and flooding technology for areas with beach elevation 0.4 meters and below.

[0060] S9.1. From July 2 to July 18, the project will completely excavate the earth within a depth of 1m in the extremely difficult-to-control area with a beach elevation of more than 0.4m. The excavated earth will be used first to surround and flood the dam body in step S9.2, and the excess earth will be used to build artificial seawalls on the tidal flats.

[0061] S9.2. From July 3 to July 10, the project built multiple vertical dikes 2 in four areas of Spartina alterniflora with a beach elevation of 0.4 meters or less in the extremely difficult-to-control area. The vertical dikes 2 are dikes perpendicular to the coastline. Then, parallel dikes 3 were built from the ocean 66 to the land 55 at different beach elevations (a parallel dike 3 was built for every 15-20 cm increase in beach elevation). The parallel dikes 3 are dikes parallel to the coastline. The vertical dikes 2 and the parallel dikes 3 are connected to each other, enclosing the control area into 29 closed areas 1 (i.e., flooded ponds), such as Figure 2 As shown, only parts of the dam and the closed area 1 are shown schematically.

[0062] The top width of the dam is set to 2m and the bottom width is 5m. The dam body is made entirely of the earth excavated in step S9.1. Figure 3 As shown, after the earthen dam is built, it is covered with a layer of geotextile 9, and both sides of the geotextile 9 are respectively buried in the soil 10 on both sides of the dam, and both sides of the geotextile 9 are buried underground at a depth of 0.5 meters.

[0063] A water inlet 7 is reserved on the dam, such as Figure 2 As shown, only the water inlet 7 is reserved on the vertical embankment 2. When high tide comes, the water inlet 7 is opened to replenish water through the tidal ditch 4. When the tide level drops, the water inlet 7 is closed to store water, forming a terraced flooding. The flooding pond begins on July 12, and the water depth is always maintained greater than 60 cm until July 30 of the following year. Considering the leakage loss and evaporation loss, 9 out of 29 closed areas 1 cannot maintain the designed water depth under natural conditions. Pumping stations 8 ( Figure 2 Only part of the pumping station 8 is shown in the figure. At high tide, water is replenished from the tidal channel 4 to a depth of 80 cm through the pumping station 8.

[0064] On July 31, at the lowest tide, the water inlet 7 of 29 closed areas 1 was opened to release water. After the water level reached the low tide level, the water inlet 7 was closed and a mobile water pump was used to drain the stored water. The pool was kept dry for 30 days for sun drying to further inactivate the plant residues.

[0065] S10, this project supplemented 9 scattered Spartina alterniflora areas that were not identified by satellite remote sensing images through manual field investigation from June 15 to June 25, and artificially pulled out the Spartina alterniflora in the scattered Spartina alterniflora areas and the easy-to-manage areas, and pulled out the roots of the Spartina alterniflora completely during the pulling out, and avoided the scattering of the biological tissue of the Spartina alterniflora. Steps S1 to S12 in the present embodiment do not fully represent the time sequence.

[0066] S11. The project will complete the second tillage of the difficult-to-control area from March 1 to March 18 of the following year, using the same tillage method as step S8.

[0067] S12. The Spartina alterniflora control project of this project was completed on August 31 of the following year. After completion, continuous monitoring was maintained for two years. During the continuous monitoring period, a full-field survey was conducted using drones on the 15th and 16th of each month from March to October each year. 17 recurrences of Spartina alterniflora were found. When sporadic occurrences occurred, they were removed by manual removal (same as step S11).

[0068] After the project was implemented, there were very few recurrences of Spartina alterniflora during the two-year continuous monitoring period, and the treatment effect was good. Since July of the second year, no recurrence of Spartina alterniflora was found, and the thorough removal of Spartina alterniflora was achieved. Relative to the rough scheme of all digging or flooding in the project area, the use of the present invention greatly saves construction costs, and also avoids the unnecessary destruction of easy-to-manage areas by blindly adopting a process with good treatment effect but large impact on tidal flat habitat. Thanks to this, after the project implemented the Spartina alterniflora treatment project, the regional habitat quality was greatly improved, and the cycle of recovery and improvement was very short, and in 1 year, it was realized that the bottom organic carbon, total nitrogen, and total phosphorus decreased by 53.49%, 17.28%, and 7.36% respectively, and the biodiversity index increased by 20.12%.

[0069] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for dividing the area of ​​Spartina alterniflora into steps, characterized in that: include: Determine the area change rate of each Spartina alterniflora patch; Multiple sampling points were set up in the survey area of ​​each Spartina alterniflora patch to obtain the sediment pH value and total organic carbon content at each sampling point, and sample plots were set up at the sampling points to count the aboveground biomass and density of Spartina alterniflora in the sample plots corresponding to each sampling point; According to the assignment rules, the area change rate, sediment pH value, sediment total organic carbon content, aboveground biomass and density of Spartina alterniflora of each sampling point are assigned values; wherein the area change rate of a sampling point is equal to the area change rate of the Spartina alterniflora patch corresponding to the sampling point; The control difficulty index of Spartina alterniflora was calculated based on the area change rate, sediment pH value, sediment total organic carbon content, aboveground biomass of Spartina alterniflora and its density. The control difficulty index of each sampling point was input into the geographic information system software and interpolation was performed. The control difficulty index contour lines were drawn for the interpolated layer, and each Spartina alterniflora area was divided into control areas based on the control difficulty index contour lines. The control area division was used to guide the selection of the most reasonable control measures.

2. The method for dividing the Spartina alterniflora region into steps according to claim 1, characterized in that: Methods for calculating the difficulty index of Spartina alterniflora management include: According to the assigned values ​​of sediment pH value and sediment total organic carbon content, the index value for evaluating the growth suitability of Spartina alterniflora was calculated, the index value of each sampling point was input into the geographic information system software, and interpolation processing was performed, and the index value contour lines were drawn for the interpolated layer. According to the index value contour lines, each Spartina alterniflora area was divided into a low-suitability area for Spartina alterniflora, a medium-suitability area for Spartina alterniflora, and a high-suitability area for Spartina alterniflora, and the area proportion of the medium-suitability area for Spartina alterniflora and the high-suitability area for Spartina alterniflora in the area near each sampling point was calculated; The control difficulty index of Spartina alterniflora corresponding to each sampling point was calculated based on the area change rate, sediment pH value, sediment total organic carbon content, the aboveground biomass and density of Spartina alterniflora, and the proportion of the area of ​​the medium suitable area and the high suitable area of ​​Spartina alterniflora in the area near the sampling point.

3. The method for dividing the Spartina alterniflora region into steps according to claim 2, characterized in that: The assignment rules include: Area change rate (% / year): Area change rate ≤ 5%, assigned a value of 1; 5% < area change rate ≤ 10%, assigned a value of 5; area change rate > 10%, assigned a value of 10; Sediment pH value: if the sediment pH value is ≤7.0 or the sediment pH value is >8.5, the value is 1; if the sediment pH value is 7.0 < ≤7.5 or the sediment pH value is 8.0 < ≤8.5, the value is 5; if the sediment pH value is 7.5 < ≤8.0, the value is 10; Total organic carbon content of sediments: if the total organic carbon content of sediments is ≤0.15%, the value is 1; if the total organic carbon content of sediments is 0.15%<≤0.3%, the value is 5; if the total organic carbon content of sediments is >0.3%, the value is 10; Aboveground biomass of Spartina alterniflora (kg / m 2 ): aboveground biomass ≤ 0.8%, assigned a value of 1; 0.8 < aboveground biomass ≤ 1.6%, assigned a value of 5; aboveground biomass > 1.6%, assigned a value of 10; Density of Spartina alterniflora (plants / m 2 ): Density ≤ 80, assigned a value of 1; 80 < density ≤ 150, assigned a value of 5; density > 150, assigned a value of 10.

4. The method for dividing the Spartina alterniflora region into steps according to claim 3, characterized in that: The index value for evaluating the growth suitability of Spartina alterniflora = the assigned value of sediment pH + the assigned value of sediment total organic carbon content. The area with index value ≤3 is the low suitable area for Spartina alterniflora, the area with index value < index value ≤10 is the medium suitable area for Spartina alterniflora, and the area with index value >10 is the high suitable area for Spartina alterniflora.

5. The method for dividing the Spartina alterniflora region into steps according to claim 3, characterized in that: The governance areas include easy governance areas, medium-difficulty governance areas, difficult governance areas, and extremely difficult governance areas; The difficulty index of Spartina alterniflora control = area change rate value × 2 + aboveground biomass value × 2 + density value × 2 + sediment pH value value + sediment total organic carbon content value + percentage of medium suitable area of ​​Spartina alterniflora in the area near the sampling point × 10 + percentage of high suitable area of ​​Spartina alterniflora in the area near the sampling point × 20; Areas with a governance difficulty index ≤31 are easy to govern, areas with a governance difficulty index of 31<≤54 are medium-difficulty governance areas, areas with a governance difficulty index of 54<≤77 are difficult to govern, and areas with a governance difficulty index of >77 are extremely difficult to govern.

6. The method for dividing the Spartina alterniflora region into steps according to any one of claims 1 to 5, characterized in that: include: The scope of the divided governance area is adjusted: the arc boundary that protrudes toward the scope of the governance area with a higher governance difficulty index is replaced by straightening it with multiple line segments; the arc boundary that protrudes toward the scope of the governance area with a lower governance difficulty index is replaced by connecting multiple tangent line segments of the arc.

7. The method for dividing the Spartina alterniflora region into steps according to any one of claims 1 to 5, characterized in that: Methods for determining the area change rate of each Spartina alterniflora patch include: Satellite remote sensing images of the target area at present and one year ago were collected, the distribution boundaries and area information of Spartina alterniflora areas in the two images were extracted, and the area change rate of each Spartina alterniflora area was calculated. Among them, for the areas newly added within one year, the weighted average of the area change rates of the three areas closest to the newly added area one year ago was taken as the area change rate of the newly added area.

8. The method for dividing the Spartina alterniflora region into steps according to any one of claims 1 to 5, characterized in that: The sampling points were arranged as follows: square grid sections were set up in the survey area of ​​each Spartina alterniflora patch. The nodes of the grids were the sampling points, and the side length of the grids was 100 meters. For sections less than 300 meters in length, sampling points were set up at both ends and at the trisection points of the sections.

9. A method for precise control of Spartina alterniflora according to the method for cascading the Spartina alterniflora region according to any one of claims 1 to 8, characterized in that: include: For scattered distribution areas that cannot be identified by satellite remote sensing images and easy-to-control areas, manual removal is used for control; For the medium-difficulty control areas, difficult-to-control areas, and extremely difficult-to-control areas, uniform mowing should be carried out to prevent the sexual reproduction of Spartina alterniflora; After mowing, the medium-difficulty areas should be plowed once, and the difficult-to-control areas should be plowed twice at intervals. The plowing depth must ensure absolute destruction of the rhizomes of Spartina alterniflora. The extremely difficult-to-control areas should be treated by excavation and flooding.

10. The precise control method for Spartina alterniflora according to claim 9, characterized in that: The methods of excavation and flooding for extremely difficult-to-control areas include: The extremely difficult-to-control areas are divided into two types of treatment areas: excavation and flooding. The excavation treatment area is the area with beach elevation>H, and the flooding treatment area is the area with beach elevation≤H. The soil within the depth h of the excavation treatment area shall be completely excavated to ensure that the excavation depth is greater than 1.5 times the depth of the root system of Spartina alterniflora. The excavated soil shall be used for the construction of the flooded dam and protective seawall; Multiple dams are built in the flooding treatment area. The multiple dams divide the flooding treatment area into one or more closed areas. Water inlets are opened on the dams. When high tide comes, the water inlets are opened to replenish water to the closed areas. When the tide level drops, the water inlets are closed to store water. The flooding depth should be maintained at more than 60 cm and the time should be more than N months. If the natural tidal conditions cannot meet the flooding depth, a pump station needs to be set up to pump water to increase the flooding level; After N months of flooding, the water in the enclosed area is drained, the water inlet is sealed, and the enclosed area is kept dry for n days for sunbathing to further inactivate plant residues.

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