Ecological collaborative restoration method and system for arid valley based on slope position grading

Abstract

The application discloses a kind of dry valley ecological collaborative repair method and system based on slope position grading, comprising the following steps: establishing the slope position grading model for partitioning the slope of dry valley, obtaining the site condition parameters of dry valley, using the slope position grading model to partition the slope of dry valley, the slope position of dry valley slope is divided into upper area, middle area and lower area;Identify the key factors affecting the repair target in the repair strategy, and establish the relationship model between the site condition parameters of each partition and the key factors, according to the corresponding relationship model of each partition and the repair strategy, obtain the repair scheme of each partition. With the whole slope as the evaluation object, accurately match the key site conditions such as wind erosion and moisture evaporation, gravel stratum rainwater infiltration under specific ecological environment of dry valley, realize accurate grading and partition of slope position, provide a reliable basis for accurately formulating and matching the management and repair scheme of different dry valley slopes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ecological restoration, and particularly relates to a dry valley ecological collaborative restoration method and system based on slope grading. BACKGROUND

[0002] The dry valley is a unique ecological landscape appearing in the lower part of the deep valley in the high mountain and valley area, has the characteristics of drought, high temperature, sparse vegetation, etc., is a typical ecological fragile zone, and is prone to desertification or rocky desertification. The dry valley has a distinct "burning wind effect". The typical performance is the dry and hot wind phenomenon formed by the sinking adiabatic warming of the airflow after climbing over the mountain on the leeward slope. The superposition of strong wind and high temperature accelerates the evaporation of surface water, and the wind erosion effect is enhanced, further aggravating the soil drought, forming a "wind erosion-evaporation" double water loss effect. During the sinking process of the airflow, the temperature increases by about 10℃ for every 1000m of descent, resulting in a relatively dry and sparse vegetation in the middle and lower part of the valley.

[0003] At present, domestic and foreign scholars have done a lot of research on the vegetation restoration of the dry valley, and formed a variety of ecological restoration comprehensive management measures such as mechanical bench building, guest soil, construction of water storage tank (water bucket), water irrigation, soil improvement, soil solidification by building a dam, and mixed planting of multiple tree species. In CN109565995A, the micro-topography of the engineering excavation slope of the dry valley is modified, and suitable plant species are selected to establish a vegetation community. In CN115720819A, the construction of artificial grassland and fruit forest, the artificial vegetation restoration of grass-shrub-forest in sub-alpine soil yard, and the grassland construction and artificial grassland construction technology of turf transplantation in alpine regions are proposed to speed up the vegetation restoration of the slag field in the ecologically fragile area of the hydropower station. In CN116998375A, the soil water-holding capacity is greatly improved and the utilization efficiency of water resources is improved by constructing a double-layer ecological geotextile and a water storage area. In CN112913374A, 10 plant species, 10 microbial agent combinations and 10cm deep spray soil most suitable for the restoration of high and steep slopes in dry and hot valleys are selected to construct a structure composed of trees, shrubs and herbaceous plants. In CN117882615A, a method for rapidly greening the slope in the dry and hot valley is proposed, which includes cleaning the slope, pulling up the ecological net, digging a pit at the intersection of the grid and punching the planting groove substrate by using a rapid greening device.

[0004] The existing ecological restoration management methods have the following problems when applied to the ecological restoration of the dry valley: 1) Most of the existing vegetation restoration methods are based on the regional altitude, ignoring the influence of the water and heat condition difference caused by the special climate of the dry valley on the vegetation restoration; 2) The ecological problem of "different soil on the same slope" in the dry valley is not considered, and the same and single engineering and biological measures are used for the natural mountain slope, resulting in low plant survival rate and unsatisfactory ecological restoration effect. SUMMARY

[0005] The purpose of the present application is to provide a slope position grading-based ecological collaborative restoration method and system for arid valley, which discloses a two-way feedback mechanism of canopy coverage and soil moisture evaporation, planting survival rate and soil water holding capacity, and solves the regional ecological restoration problem of the lower part of the arid valley slope position.

[0006] The present application is realized by the following technical solutions:

[0007] The slope position grading-based ecological collaborative restoration method for arid valley comprises the following steps:

[0008] A slope position grading model for partitioning the slope surface of the arid valley is established, the site condition parameters of each region of the slope surface of the arid valley are obtained, including air temperature, wind size, evaporation intensity, air humidity, soil thickness, and soil gravel content, the slope surface of the arid valley is partitioned by using the slope position grading model, and the slope surface of the arid valley is divided into an upper region, a middle region and a lower region.

[0009] According to the partition strategy under the slope position grading model and the site condition characteristics of different partitions, different restoration strategies and targets are formulated for each partition, the key factors affecting the restoration target in the restoration strategy are identified, and a relationship model between the site condition parameters and the key factors of each partition is established, and the restoration scheme of each partition is obtained according to the corresponding relationship model and the restoration strategy of each partition.

[0010] In some embodiments, the slope position grading model is a slope position index S calculated according to the following formula:

[0011] S=f1×T n +f2×W n +f3×E n +f4×H n +f5×D n +f6×G n ; wherein T n , W n , E n , H n , D n , G n respectively correspond to the normalized values of air temperature, wind size, evaporation intensity, air humidity, soil thickness, and soil gravel content, and the value interval is [0, 1]; f1, f2, f3, f4, f5, and f6 are the corresponding weights, and the weights of air temperature, wind size, and evaporation intensity are greater than the weights of air humidity, soil thickness, and soil gravel content.

[0012] The slope surface is partitioned according to the slope position index S and the slope position grading threshold interval, and the slope position grading threshold interval is obtained by cluster analysis combined with expert experience.

[0013] In some embodiments, according to the zoning strategy of the slope position classification model and the site condition characteristics of different zones, the restoration strategy of the upper zone is to use deep-rooted trees to anchor the soil and combine with herbaceous plants to cover the ground surface, and the restoration target is to achieve a target reduction in soil erosion within the restoration period;

[0014] The restoration strategy of the middle zone is to use shrubs to form a wind barrier and combine with herbaceous layers to fill ecological niche pores, reduce wind speed, and reduce wind erosion, and the restoration target is to achieve a target reduction in soil moisture evaporation within the restoration period;

[0015] The restoration strategy of the lower zone is to use a combination of trees, shrubs, and herbs, and the restoration target is to achieve a target increase in soil water holding capacity within the restoration period.

[0016] In some embodiments, in the upper zone, the depth of tree root anchoring is used as a key factor affecting the restoration target of the upper zone, and a first relationship model between the corresponding site condition parameters and the depth of tree root anchoring when using the standard restoration scheme of the upper zone is established; the predicted value of the depth of tree root anchoring is obtained according to the current site condition parameters of the upper zone and the first relationship model, and the restoration scheme of the upper zone is determined according to the predicted value of the depth of tree root anchoring and the target depth of tree root anchoring.

[0017] And / or, in the middle zone, the shrub canopy coverage is used as a key factor affecting the restoration target of the middle zone, and a second relationship model between the corresponding site condition parameters and the shrub canopy coverage when using the standard restoration scheme of the middle zone is established; the predicted value of the shrub canopy coverage is obtained according to the current site condition parameters of the middle zone and the second relationship model, and the restoration scheme of the middle zone is determined according to the predicted value of the shrub canopy coverage and the target canopy coverage of the shrub.

[0018] And / or, in the lower zone, the planting survival rate is used as a key factor affecting the restoration target of the lower zone, and a third relationship model between the corresponding site condition parameters and the planting survival rate when using the standard restoration scheme of the lower zone is established; the predicted value of the planting survival rate is obtained according to the current site condition parameters of the lower zone and the third relationship model, and the restoration scheme of the lower zone is determined according to the predicted value of the planting survival rate and the target value of the planting survival rate.

[0019] In some embodiments, the step of determining the restoration scheme of the upper zone according to the predicted value of the depth of tree root anchoring and the target depth of tree root anchoring includes:

[0020] When the predicted value of the tree root anchoring depth reaches the first root anchoring depth threshold value, the upper region standard repair scheme is adopted as the upper region repair scheme; when the predicted value of the tree root anchoring depth does not reach the second root anchoring depth threshold value, the current region is re-partitioned; when the predicted value of the tree root anchoring depth is between the first root anchoring depth threshold value and the second root anchoring depth threshold value, the optimized upper region standard repair scheme is adopted as the upper region repair scheme; the first root anchoring depth threshold value and the second root anchoring depth threshold value are determined according to the target depth of the tree root anchoring.

[0021] In some embodiments, the step of determining the middle region repair scheme according to the predicted value of the shrub canopy coverage and the target shrub canopy coverage comprises:

[0022] When the predicted value of the shrub canopy coverage reaches the target shrub canopy coverage requirement, the middle region standard repair scheme is adopted as the middle region repair scheme; when the predicted value of the shrub canopy coverage does not reach the target shrub canopy coverage requirement, the optimized middle region standard repair scheme is adopted as the middle region repair scheme.

[0023] In some embodiments, the step of determining the lower region repair scheme according to the predicted value of the planting survival rate and the target planting survival rate comprises:

[0024] When the predicted value of the planting survival rate reaches the target planting survival rate requirement, the lower region standard repair scheme is adopted as the lower region repair scheme; when the predicted value of the planting survival rate does not reach the target planting survival rate requirement, the optimized lower region standard repair scheme is adopted as the lower region repair scheme.

[0025] In some embodiments, a first coupling influence coefficient between the shrub canopy coverage and the soil water evaporation reduction range is obtained, and a first coupling relationship model between the shrub canopy coverage change range and the soil water evaporation reduction range change range is established according to the first coupling influence coefficient and the change range of the site condition parameters;

[0026] The shrub canopy coverage and the current site condition parameters in the monitoring period are obtained, the current soil water evaporation reduction range change range is obtained according to the change range of the current shrub canopy coverage and the site condition parameters and the first coupling relationship model, and it is judged whether the middle region repair scheme needs to be optimized according to the current soil water evaporation reduction range change range.

[0027] In some embodiments, a second coupling influence coefficient between the planting survival rate and the soil water holding capacity increase range is obtained, and a second coupling relationship model between the planting survival rate change range and the soil water holding capacity increase range change range is established according to the second coupling influence coefficient and the change range of the site condition parameters;

[0028] Obtain the planting survival rate and the current site condition parameter in the monitoring period, and obtain the current soil water holding capacity increment change amount according to the current planting survival rate, the change amount of the site condition parameter and the second coupling relationship model, and determine whether the lower area repair scheme needs to be optimized according to the current soil water holding capacity increment change amount.

[0029] In another aspect, the application also provides a slope position grading-based dry valley ecological collaborative repair system for executing the slope position grading-based dry valley ecological collaborative repair method, comprising:

[0030] The first module is configured to divide the slope surface of the dry valley according to the obtained site condition parameters of each region of the slope surface of the dry valley, and adopt a slope position grading model;

[0031] The second module is configured to output the corresponding repair scheme according to the relationship model of each subarea and the site condition parameter;

[0032] The third module is configured to obtain the current soil water evaporation reduction change amount according to the first coupling influence coefficient between the shrub canopy coverage and the soil water evaporation amount reduction, and the first coupling relationship model between the shrub canopy coverage change amount and the soil water evaporation reduction change amount established based on the first coupling influence coefficient and the change amount of the site condition parameter, the shrub canopy coverage in the monitoring period and the change amount of the current site condition parameter, and determine whether the middle area repair scheme needs to be optimized according to the current soil water evaporation reduction change amount;

[0033] The fourth module is configured to obtain the current soil water holding capacity increment change amount according to the second coupling influence coefficient between the planting survival rate and the soil water holding capacity increment, and the second coupling relationship model between the planting survival rate change amount and the soil water holding capacity increment change amount established based on the second coupling influence coefficient and the change amount of the site condition parameter, the planting survival rate in the monitoring period and the change amount of the current site condition parameter, and determine whether the lower area repair scheme needs to be optimized according to the current soil water holding capacity increment change amount.

[0034] Compared with the prior art, the application has the following advantages and beneficial effects:

[0035] The application breaks through the limitation of the traditional slope position division method which only relies on a single slope index, takes the overall slope surface as the evaluation object, optimizes and constructs a dynamic zoning model based on air temperature, wind size, evaporation intensity, air humidity, soil thickness and soil gravel content, accurately matches key site conditions such as wind erosion and water evaporation, gravel stratum rainwater infiltration and the like under specific ecological environment of the dry valley, realizes accurate grading and zoning of the slope position, and provides a reliable basis for accurately formulating and matching the management and repair scheme of different dry valley slopes.

[0036] The present application formulates different repair strategies and repair targets for different partitions, identifies key factors affecting the repair targets of each partition in the repair strategy, and establishes a relationship model between site condition parameters and key factors, combined with the repair target to formulate a targeted repair scheme, so that the matching accuracy of the partition repair measures is improved by more than 50%.

[0037] The present application focuses on the influence of the "foehn effect" on the middle and lower zones, and establishes a coupling relationship model between the key factors and the repair targets in the middle and lower zones, directly associates the key factors with the repair targets, and realizes dynamic prediction of the repair targets according to the dynamic monitoring data in the repair process, and according to the prediction, the repair scheme is intervened in advance, realizing closed-loop control and feedback of the repair process, and shortening the ecological repair period. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0039] Figure 1 The flow chart of the ecological collaborative repair method of the dry valley based on slope position grading in the embodiments of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments.

[0041] The present application takes the overall slope surface as the evaluation object, extracts the core site condition parameters affecting ecological repair according to the unique ecological environment of the dry valley, forms a core parameter system, and on this basis, identifies the key points of treatment in different slope position partitions, formulates targeted treatment targets, and realizes dynamic association and matching between slope position partitions and treatment targets.

[0042] In order to realize accurate partition of slope position, the natural mountain slope surface is evaluated as a whole, and temperature, wind, evaporation, humidity, soil layer and gravel amount are quantified as slope grading indexes for slope position partition. The specific steps are as follows:

[0043] 1. Build a slope position grading model

[0044] The core site condition parameters and quantization standards of slope position grading are shown in Table 1.

[0045] Table 1 Site Condition Parameters and Quantitative Standards

[0046]

[0047] The weighting is determined based on the contribution of site condition parameters to slope classification, with a total weight of 1.

[0048] Based on the unique natural site conditions of arid valleys and the characteristics of the "Foehn effect," the "Foehn effect" is taken as the main factor influencing slope classification. The weights of air temperature, wind force, and evaporation intensity, which are strongly correlated with the "Foehn effect," are increased. The slope classification of arid valleys is guided by the impact of the "Foehn effect" on the ecological restoration of arid valleys.

[0049] A slope index (S-value) calculation model is established, expressed as follows:

[0050] S=f1×T n +f2×W n +f3×E n +f4×H n +f5×D n +f6×G n ;

[0051] Among them, T n W n E n H n D n G n These correspond to the normalized site condition parameters of air temperature, wind force, evaporation intensity, air humidity, soil layer thickness, and soil gravel content, respectively, with a value range of [0, 1]; f1, f2, f3, f4, f5, and f6 are the corresponding weights.

[0052] Based on the slope position index calculation model and the actual measured site condition parameters, the slope position index S of different areas on the slope can be calculated.

[0053] The threshold ranges for slope grading were obtained by combining cluster analysis (K-means algorithm) with expert experience, as shown in Table 2.

[0054] Table 2 Threshold Intervals for Slope Classification

[0055]

[0056] 2. Develop a partition repair strategy and repair goals.

[0057] The partition repair strategy and repair objectives are shown in Table 3.

[0058] Table 3 Partition Repair Strategy and Repair Targets

[0059]

[0060] 2.1) Upper area restoration strategy and restoration target

[0061] Identify the key problems of upper area governance: thick soil layer, low air temperature, high air humidity, and gravity erosion.

[0062] Develop upper area restoration goals: use deep-rooted cold-resistant trees to anchor soil, herbaceous rapid ground cover to reduce rainwater erosion and improve soil and slope protection capacity.

[0063] Within 3 years, the anchoring depth of tree roots is >1.5 m, and the soil erosion amount is reduced by 85%.

[0064] Restoration plant combination: deep-rooted, cold-resistant trees, and creeping herbs.

[0065] Restoration planting technology: hole-shaped land preparation, backfilling of guest soil; add water retention agent to each hole, and cover the surface with erosion-resistant mesh.

[0066] 2.2) Middle area restoration strategy and restoration target

[0067] Identify the key problems of middle area governance: obvious "fire wind effect", high air temperature, strong wind erosion, fast water evaporation, and low humidity.

[0068] Develop middle area restoration goals: select drought-tolerant legume shrubs, their dense branch canopies form a "windbreak", reducing wind speed to reduce wind erosion. The herb layer fills the ecological niche gap to achieve the purpose of wind reduction and evaporation reduction.

[0069] Within 3 years, the shrub canopy coverage is ≥90%, and the soil water evaporation is reduced by 40%.

[0070] Restoration plant combination: deep-rooted, drought-tolerant legume shrubs, and ground cover herbs.

[0071] Restoration planting technology: fish-scale pit land preparation, straw bundle buried in the pit; surface covered with degradable mulch.

[0072] 2.3) Lower area restoration strategy and restoration target

[0073] Identify the key problems of lower area governance: similar to the middle area in terms of climate conditions, but with high stone content, thin soil, and poor soil water retention capacity.

[0074] Develop lower area restoration goals: take engineering auxiliary measures to improve planting survival rate and enhance soil water storage and retention capacity.

[0075] Within 3 years, the planting survival rate reaches 80%, and the soil water holding capacity increases by 35%.

[0076] Restoration plant combination: drought-tolerant and poor soil-tolerant trees; legume shrubs; herbs.

[0077] Rehabilitation technique: terrace reclamation, field surface laid with gravel-clay water barrier; rainwater collection ditch laid to guide rainwater to planting hole.

[0078] 3. Identify the key factors in the rehabilitation scheme, establish the relationship model between the site condition parameters and the key factors under the standard rehabilitation scheme, and determine the rehabilitation scheme according to the relationship model and the rehabilitation strategy

[0079] 3.1) Upper zone rehabilitation scheme

[0080] According to the rehabilitation strategy and rehabilitation target of the upper zone, the key factor affecting the realization of the rehabilitation target, i.e. the anchoring depth of arbor roots, is identified, and the first relationship model between the corresponding site condition parameters and the key factor under the standard rehabilitation scheme of the upper zone is established.

[0081] Identify the key site condition parameters that affect the anchoring depth Y (unit: m) of arbor roots in the upper zone: soil layer thickness (D), gravel content (G), air temperature (T), and evaporation intensity (E), and establish the first relationship model between the anchoring depth Y of arbor roots and the above-mentioned site condition parameters, which is represented as:

[0082] Y = Y0-0.08×G-0.05×T+0.02×D-0.04×E;

[0083] Wherein, Y0 is the baseline value of the anchoring depth of arbor roots under ideal site condition parameters (low G, T, E and high D) when the standard rehabilitation scheme of the upper zone is adopted, and Y0 is 2.2.

[0084] According to the first relationship model and the site condition parameter data of the current region, the anchoring depth Y of arbor roots in the rehabilitation period is calculated;

[0085] When Y≥1.8; the standard rehabilitation scheme of the upper zone is adopted (for example, deep-rooted arbor: Minjiang cypress + radiata pine, hole-shaped reclamation + anti-erosion net);

[0086] When 1.5≤Y<1.8; the standard rehabilitation scheme of the upper zone needs to be optimized, and the optimization of arbor species / combination or the improvement of guest soil + water-retaining agent is needed;

[0087] When Y<1.5; it is judged that the region is not suitable for being the upper zone, and needs to be re-zoned, for example, the region is divided into the middle zone.

[0088] 3.2) Middle zone rehabilitation scheme

[0089] According to the rehabilitation strategy and rehabilitation target of the middle zone, the key factor affecting the realization of the rehabilitation target, i.e. shrub canopy coverage, is identified, and the second relationship model between the corresponding site condition parameters and the key factor under the standard rehabilitation scheme of the middle zone is established.

[0090] Identify the key site condition parameters that affect the shrub canopy coverage P (unit: %) in the middle zone: air temperature (T), wind size (W), evaporation intensity (E), air humidity (H), gravel content (G), and establish the second relationship model between the shrub canopy coverage P and the above site condition parameters, expressed as:

[0091] P = P0-1.2×(T-16)-1.0×(E-1600) / 100-0.8×G+0.6×H-0.5×W;

[0092] Where (E-1600) / 100 standardizes the evaporation amount, making the coefficients comparable; P0 is the baseline value of shrub canopy coverage under ideal site condition parameters when using the middle zone standard restoration scheme, and P0 is 98.

[0093] According to the second relationship model and the current site condition parameter data of the region, calculate the shrub canopy coverage P in the restoration period;

[0094] When P≥90%; use the middle zone standard restoration scheme (for example, legume shrubs: combination of Anagyris pedunculata and Indigofera linifolia, fish scale pit preparation + mulching film);

[0095] When 80%≤P<90%; optimize shrub species / combination, increase density, straw bundle, and optimize mulching film covering method;

[0096] When P<80%; backfill guest soil, drip irrigation assistance.

[0097] 3.3) Lower zone restoration scheme optimization

[0098] According to the restoration strategy and restoration target of the lower zone, identify the key factor that affects the restoration target implementation—planting survival rate, and establish the third relationship model between the corresponding site condition parameters and the key factor when using the lower zone standard restoration scheme;

[0099] Identify the key site condition parameters that affect the planting survival rate L (unit: %) in the lower zone: air temperature (T), wind size (W), evaporation intensity (E), air humidity (H), gravel content (G), and soil layer thickness (D), and establish the third relationship model between the planting survival rate L and the above site condition parameters, expressed as:

[0100] L = L0-1.5×G-1.2×(T-18)-0.9×(E-1800) / 100+0.8×H+0.4×D-0.6×W;

[0101] Wherein, for evaporation intensity E, taking 1800 mm as the benchmark, the survival rate decreases by 0.9% for every 100 mm increase. L0 is the benchmark value of planting survival rate under ideal site condition parameters when the lower zone standard restoration scheme is adopted, and L0 is 92.

[0102] When L≥80%; the lower zone economic forest standard restoration scheme (tree: combination of Xikang peach and Zanthoxylum bungeanum, legume shrub: Lespedeza, herb: Pedicularis; terrace soil + gravel clay water barrier + rainwater collection ditch) is adopted;

[0103] When 70%≤P<80%; container seedlings and water retention agent are adopted for strengthening;

[0104] When P<70%; backfilling of guest soil, drip irrigation and shading comprehensive measures are adopted.

[0105] By establishing a linear relationship model between the identified key factors and the site condition parameters, a quantitative decision basis is provided for the selection and optimization of restoration schemes in different partitions and different site conditions of the dry valley slope, so that the method can be widely used for rapid decision-making of different dry valley management schemes. If the expected value is greater than or equal to the target value, it means that the existing site conditions can support the realization of the restoration target, and the standard technology package can be adopted. If the expected value is less than the target value, it means that the site condition is strong, and engineering measures (such as additional water retention agent in the lower zone) must be taken to compensate for the site disadvantage.

[0106] 4. Restoration scheme implementation effect evaluation and scheme optimization decision

[0107] In view of the significant influence of "foehn effect" on the middle zone and the lower zone, according to historical data, a coupling relationship model between the corresponding key factors and the restoration target is established in the middle zone and the lower zone respectively, and the target achievement of the current restoration scheme is evaluated and predicted according to the periodic monitoring data and the coupling relationship model, so as to provide a decision basis for timely intervention in the restoration process.

[0108] 4.1) Middle zone restoration scheme implementation effect evaluation and scheme optimization decision

[0109] Middle zone key factor: shrub canopy coverage (P)≥90%; middle zone restoration target: soil water evaporation reduction (E r )≥40%;

[0110] Identify the key site condition parameters (wind size W, air humidity H) that affect shrub canopy coverage and soil water evaporation, and establish a first coupling relationship model between the change amount of shrub canopy coverage and the change amount of soil water evaporation reduction, which is expressed as:

[0111] ΔE r,i =k m ×ΔP i -λ×ΔW+η×ΔH;

[0112] where ΔP i is the annual change of shrub canopy coverage (%), ΔE r,i is the annual change of soil water evaporation reduction rate (%); k m is the canopy evaporation suppression efficiency coefficient, i.e., the first coupling influence coefficient between the shrub canopy coverage and the soil water evaporation reduction, and the empirical value in the middle region of the Minjiang Dry Valley is 0.48; λ is the wind weakening coefficient, and the value is 0.4-0.5, indicating that the wind speed annual change (ΔW) increases by 1 m / s, the evaporation suppression effect is weakened by 0.4%-0.5%; η is the humidity enhancement coefficient, and the value is 0.2-0.3, indicating that the air humidity annual change (ΔH) increases by 10%, the evaporation suppression effect is enhanced by 2%-3%.

[0113] The change of the shrub canopy coverage will directly affect the wind speed and the air humidity in the middle region, and the shrub canopy coverage, the wind speed and the air humidity in the middle region affect the soil water evaporation. According to the correlation between the above factors, the first coupling relationship model between the change of the shrub canopy coverage and the change of the soil water evaporation reduction is established.

[0114] Based on the first coupling relationship model, the data of the shrub canopy coverage, the wind speed and the air humidity are monitored regularly (e.g., with 1 year as the monitoring period) in the restoration process, the changes of the shrub canopy coverage, the wind speed and the air humidity in the monitoring period are obtained, and the corresponding change of the soil water evaporation reduction is obtained according to the first coupling relationship model. The target achievement of the current middle region restoration scheme is evaluated and predicted by comparing the change with the middle region restoration target.

[0115] In order to achieve the total target of E r ≥40% in 3 years, the annual average ΔE r,i needs to reach about 13%. According to the model, this requires the annual average ΔP i must reach about 13 / 0.48≈27%. If ΔE r,i is monitored to be lower than the model expectation in a certain year, the possible reasons are: (1) the wind is significantly enhanced (ΔW>0) in the year; (2) the canopy growth quality is poor, and the actual k m value is low.

[0116] The coordinated dynamic target of the middle region: P1+∑ΔP i ≥90% and ∑ΔE r,i ≥40% should be met in the 3-year management period. P1 is the initial shrub canopy coverage.

[0117] When the repair coordination target reaches the middle zone coordination threshold, it is judged that the current repair scheme is effective and does not need to be optimized, and when it does not reach the middle zone coordination threshold, it is judged that the current repair scheme needs to be further intervened and optimized, such as strengthening water and fertilizer, replacing shrub species, etc.

[0118] 4.2) Effect evaluation and scheme optimization decision of lower zone repair scheme

[0119] Key factor of lower zone: planting survival rate (L) ≥80%, repair target of lower zone: soil water holding capacity increase (C i ) ≥35%;

[0120] Identify the key site condition parameters (gravel content G, air temperature T) that affect planting survival rate and soil water holding capacity increase, and establish a second coupling relationship model between the change amount of planting survival rate and the change amount of soil water holding capacity increase, expressed as:

[0121] ΔL i =k s ×ΔC i,i -σ×ΔG -μ×ΔT;

[0122] Wherein, ΔL i is the annual change amount of planting survival rate (%), ΔC i,i is the annual change amount of soil water holding capacity increase (%); k s is the water survival sensitive coefficient, that is, the second coupling influence coefficient between planting survival rate and soil water holding capacity increase, and the empirical value in the middle zone of Minjiang Dry Valley is 0.65; σ is the gravel stress coefficient, the value is 0.7, which means that for every 1% increase in the annual change amount of gravel content (ΔG), the survival rate will decrease by 0.7%; μ is the temperature stress coefficient, the value is 0.5, which means that for every 1℃ increase in the annual change amount of temperature (ΔT), the survival rate will decrease by 0.5%.

[0123] The change of planting survival rate will directly affect the gravel content and air temperature of the lower zone, and the planting survival rate, gravel content and air temperature of the lower zone will also affect the soil water holding capacity. According to the above relationship, a second coupling relationship model between the change amount of planting survival rate and the change amount of soil water holding capacity is established.

[0124] Based on the second coupling relationship model, the data of planting survival rate, gravel content and air temperature are monitored regularly (such as 1 year as the monitoring period) during the repair process, and the change amount of planting survival rate, gravel content and air humidity in the monitoring period is obtained. According to the second coupling relationship model, the corresponding change amount of soil water holding capacity increase can be obtained, and the change amount is compared with the repair target of the lower zone to evaluate and predict the target achievement of the current lower zone repair scheme.

[0125] The lower zone governance must be improved by engineering measures (such as water-resisting layer, rainwater collection ditch) to quickly improve ΔC i,i , so as to guarantee ΔL i . If the engineering measures are effective, ΔC i,i ≥20% can be realized in the first year, and it is expected that ΔL i can be improved by 20*0.65=13%. If the actual ΔL i is much lower than this value, the possible reason is that an abnormally high temperature (ΔT>0) or soil gravelization (ΔG>0) is encountered in the year, which produces additional stress.

[0126] The lower zone coordination dynamic target: within 3 years of governance period, L1+∑ΔL i ≥80%; ∑ΔC i,i ≥35%. Wherein L1 is the initial survival rate.

[0127] When the repair coordination target reaches the lower zone coordination threshold, it is judged that the current repair scheme is effective and does not need to be optimized, and when it does not reach the lower zone coordination threshold, it is judged that the current repair scheme needs to be further intervened and optimized, for example, immediately taking shading, supplemental irrigation and other measures to resist high temperature stress, and surface guest soil improvement to relieve gravelization.

[0128] The following takes a dry valley in the upper reaches of the Minjiang River as an example to explain the ecological coordination repair method in detail.

[0129] 1) Slope position grading

[0130] According to the above measurement method, the site condition parameters are obtained. The site condition parameters are normalized, as shown in Table 4, and input into the slope position index (S value) calculation model to calculate the slope position index (S value).

[0131] Table 4: measured value and normalized treatment of site condition parameters

[0132]

[0133] Calculate S value: S=0.25*0.50+0.20*0.33+0.20*0.33+0.15*0.38+0.10*0.44+0.10*0.30=0.388.

[0134] Slope position grading determination: S=0.388∈ [0.30, 0.60]; it is determined that the slope position of the region is the middle zone.

[0135] 2) Subzone repair scheme

[0136] Upper zone:

[0137] According to the corresponding site condition parameters of the upper zone, the anchoring depth Y of the arbor root system is calculated to be greater than 1.5 m when the standard restoration scheme is adopted; the upper zone standard restoration scheme is adopted for restoration in this area.

[0138] The deep-rooted arbor is combined with Sabina pingii and Pinus radiata, and the creeping herb is Cynodon.

[0139] The planting hole is excavated according to the 2 m x 3 m plant spacing, and water retention agent 15 g is applied in the hole; Sabina pingii (seedling height > 80 cm) and Pinus radiata (seedling height > 100 cm) are planted; Cynodon seed is mixed with fine sand at a ratio of 1:2 and sown, and the soil is covered with 1 cm; the surface is covered with anti-erosion net (plant fiber-based degradable net, tensile strength ≥ 50 kN / m 2 ).

[0140] The water retention agent is selected from polyacrylamide (molecular weight 6 million, water absorption ratio ≥ 300, and the soil saturated water holding capacity can be maintained for 120 days when the application amount is 15 g / hole), 15 g of water retention agent is applied per hole (when the soil permeability is > 10 mm / h, the water retention agent dosage is increased by 20%), and 1 kg of organic fertilizer is applied per hole. The herb seeds are mixed at a ratio of 1:1 and sown, with a density of 3 kg / acre, and the soil is covered with a thickness of 1-2 cm.

[0141] Middle zone:

[0142] According to the corresponding site condition parameters of the middle zone, the canopy coverage P of the shrub is calculated to be:

[0143] P=P0-1.2×(T-16)-1.0×(E-1600) / 100-0.8×G+0.6×H-0.5×W=98-1.2×(15-16)-1.0×(1500-1600) / 100-0.8×25%+0.6×55%-0.5×4=98.33%≥90%;

[0144] The middle zone standard restoration scheme is adopted for restoration in this area.

[0145] The shrub is combined with Leguminosae dense shrubs, such as combined with Baphia sp. and Indigofera linnaei, and the ground cover herb is Clematis.

[0146] The fish scale pit is excavated according to the 2 m x 2 m plant spacing; the Leguminosae shrubs Baphia sp. (seedling height > 60 cm) and Indigofera linnaei (seedling height > 50 cm) are planted; the Clematis seeds are mixed with fine sand and strip sown with a row spacing of 20 cm; straw bundles (diameter 20 cm) are buried in the pit; the surface is covered with degradable mulch (starch-PBAT blended mulch, light transmittance ≤ 30%).

[0147] The fish scale pit has a size of 60 cm*40 cm*30 cm, and is designed in a radial structure to better disperse and guide water flow and reduce water and soil loss; by increasing the pit depth, the soil water storage capacity is enhanced, and especially in the dry season, more water can be effectively stored. The fish scale pits are arranged in a triangular staggered pattern along the contour lines, with a row spacing of 1.5-2.0 m and a pit spacing of 0.8-1.2 m, and a 15°-25° inclination is maintained.

[0148] A plant bag is installed in the fish scale pit, which contains soil, water retaining agent and an appropriate amount of organic fertilizer, etc., which can further improve the water retention rate, especially in harsh environments, effectively helping plants to pass through the water shortage period in the early growth stage. The soil in the plant bag can be adjusted according to the needs of the plant species, such as adding humus soil and water-retaining fertilizer in the bag, to further improve the nutrient content and water retention capacity of the soil. A water-retaining geotextile (such as polypropylene geotextile) is placed inside each fish scale pit, which can prevent soil particles from being lost while enhancing the water retention capacity of the soil. Through the application of this geotextile, the water retention capacity of the soil can be improved, especially in dry seasons or in the case of insufficient rainfall, effectively reducing the evaporation of soil water, and improving the sustainability of plant growth.

[0149] Lower area:

[0150] According to the corresponding site condition parameters of the lower area, the planting survival rate L calculated by using the standard restoration scheme is greater than 80%; the lower area is restored by using the standard restoration scheme of the lower area.

[0151] The arbor is a combination of Xikang almond and Zanthoxylum bungeanum, the leguminous shrub is Lespedeza, and the herb is Pedicularis.

[0152] Build terraces, and lay clay-gravel water barrier layer (clay: gravel = 3:1, 15 cm thick, locally available) on the field surface; according to the 2m*1m plant row spacing, zonally interplant Xikang almond (seedling height >40 cm) and Zanthoxylum bungeanum (seedling height >50 cm); rainwater collection ditches are arranged along the field contour line with a spacing of 5 m; Lespedeza (seedling height >60 cm) is interspersed between economic tree species, and Pedicularis is strip seeded in the ditch ridge.

[0153] Maintenance measures during the restoration period:

[0154] Drip irrigation once a month (water volume 10 m 3 / acre) in the dry season; replanting in spring every year in areas with a mortality rate >10%; mowing shrubs once every 2 years in the middle area to promote sprouting.

[0155] 3) Effect evaluation of restoration scheme implementation and scheme optimization decision

[0156] Take the effect evaluation of the restoration scheme implementation and the scheme optimization decision in the middle area as an example:

[0157] Obtain the current shrub canopy coverage, site condition parameters (wind size, air humidity), calculate the soil water evaporation amount reduction change according to the first coupling relationship model, and evaluate the repair target achievement in the middle area according to the current soil water evaporation amount reduction data.

[0158] During the repair period, the measures for optimizing the maintenance operation during the repair period can adopt an intelligent water monitoring system based on the drip irrigation system. Through soil moisture sensors, meteorological data and automatic control systems, the soil moisture content is monitored in real time. According to factors such as climate change, soil moisture, plant growth requirements, etc., the irrigation amount of the drip irrigation system is automatically adjusted to ensure that plants can receive appropriate water supply under different seasons and different climate conditions. Through this precise water control, water resource utilization efficiency is improved, and water and soil loss caused by excessive irrigation is avoided.

[0159] Monitor the survival rate every spring, and replant dead plants; moderately thin the Pinus radiata on the uphill position after it is dense, and reserve Sabina chinensis as the dominant.

[0160] The meteorological (air temperature, wind size, evaporation intensity, air humidity) index is introduced, and the slope position is objectively divided through the slope position index, so that the limitation of single slope grading is overcome, the scientificity of slope grading is improved, and the configuration difficulty of "same slope different soil" in the arid valley is solved.

[0161] The partition scheme and benefits are shown in Table 5.

[0162] Table 5 Slope position function area benefit table

[0163]

[0164] By using the repair method of the present application, the canopy interception efficiency of the protective forest on the uphill position reaches 68%, effectively reducing the runoff peak value by 43%; the Shannon-Wiener index of the shrub on the middle slope position breaks through the threshold value of 2.5, and the number of pollination insects is 2.3 times that of the traditional mode; the economic fruit yield on the lower slope position is stably maintained at 800 kg / mu, and the unit area output value is increased by 120% through the under-forest intercropping mode. This multi-dimensional benefit improvement mechanism makes the comprehensive efficiency increase by 50% compared with the conventional method, verifying the feasibility of the ecological-economic synergistic path. The cooperation of water-retaining agent and precise irrigation prolongs the duration of effective soil water to 180 days after the rainy season, and the water use efficiency is increased by 2.8 times compared with traditional flooding irrigation. The introduction of economic shrub species not only reduces the management cost, but also forms a carbon sink system with an annual carbon sequestration amount of 3.2 t / ha.

[0165] The application is applied in 12 demonstration points in the upper reaches of Minjiang River, and shows that through slope position zoning and precise matching of plant functional groups, the unit area restoration cost can be reduced by 37%, and the formation period of ecological service function can be shortened by about 18 months. The technical mode based on natural solution provides a new theoretical framework and practical path for ecological restoration in global dry valley areas.

[0166] In another aspect, the present application also relates to a slope position grading-based dry valley ecological collaborative restoration system for executing the slope position grading-based dry valley ecological collaborative restoration method, comprising:

[0167] A first module is configured to divide the slope surface of the dry valley according to the slope position grading model based on the obtained site condition parameters of each region of the slope surface of the dry valley;

[0168] A second module is configured to output the corresponding restoration scheme according to the relationship model and the site condition parameters of each division;

[0169] A third module is configured to obtain the current soil water evaporation reduction change amount according to the first coupling influence coefficient between the shrub canopy coverage and the soil water evaporation reduction amount, the first coupling relationship model between the shrub canopy coverage change amount and the soil water evaporation reduction change amount established based on the first coupling influence coefficient and the site condition parameter change amount, the shrub canopy coverage in the monitoring period and the change amount of the current site condition parameters, and determine whether the middle region restoration scheme needs to be optimized according to the current soil water evaporation reduction change amount;

[0170] A fourth module is configured to obtain the current soil water holding capacity increase change amount according to the second coupling influence coefficient between the planting survival rate and the soil water holding capacity increase amount, the second coupling relationship model between the planting survival rate change amount and the soil water holding capacity increase change amount established based on the second coupling influence coefficient and the site condition parameter change amount, the planting survival rate in the monitoring period and the change amount of the current site condition parameters, and determine whether the lower region restoration scheme needs to be optimized according to the current soil water holding capacity increase change amount.

[0171] As used in the description and the appended claims, certain terminology is used to describe parts that will be apparent to those skilled in the art. It is not intended to exclude other equivalents of the parts from the scope of the application. As used in the description and the appended claims, the singular forms "a," "an," and "the" are used to include plural references unless the context clearly dictates otherwise. As used herein, the term "includes" and / or "including" means, but is not limited to, the meaning that is synonymous with "comprising" or "comprising." The term "substantially" means within acceptable manufacturing tolerances, and those skilled in the art will recognize that the technology can be practiced within a certain error tolerance, which is expected by those skilled in the art. The subsequent description of the preferred embodiments of the application is provided for the purpose of illustration and is not intended to limit the application in any way. The scope of the application is set forth in the claims that follow.

[0172] It is further noted that the terms "comprise" "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product or process that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such product or process. An element proceeded by "comprises a" does not, without more constraints, exclude the presence of additional identical elements in the product or process that contains the referred element.

[0173] The above specification and description of the application discloses and describes several preferred embodiments of the application, but it is understood that the application is not limited to the forms disclosed, but is intended to cover alterations, modifications, and equivalents thereof, which may be used in various other combinations, modifications, and environments without departing from the spirit or scope of the application as defined by the following claims. Changes and modifications within the scope of the application may be made by those skilled in the art, which do not depart from the spirit of the application, and it is intended to fall within the scope of the claims.

Claims

1. A method for collaborative ecological restoration of arid river valleys based on slope grading, characterized in that, Includes the following steps: A slope position classification model was established to divide the arid valley slope into three zones. Site condition parameters for each zone of the arid valley slope were obtained, including air temperature, wind speed, evaporation intensity, air humidity, soil thickness, and soil gravel content. The slope position classification model was used to divide the arid valley slope into upper, middle, and lower zones. Based on the zoning method under the slope classification model and the site condition characteristics of different zones, different restoration strategies and objectives are formulated for the middle and lower zones. Key factors affecting the restoration objectives in the restoration strategies are identified, and a relationship model between site condition parameters and key factors in the middle and lower zones is established. Based on the relationship model and restoration strategy corresponding to the middle and lower zones, restoration schemes for the middle and lower zones are obtained. Based on the zoning strategy of the slope grading model and the site conditions of different zones, the restoration strategy for the middle zone is to use shrubs to form a windbreak barrier and combine it with a herbaceous layer to fill the ecological niche pores, reduce wind speed and reduce wind erosion, and the restoration target is the target reduction in soil moisture evaporation during the restoration period; the restoration strategy for the lower zone is to use a combination of trees, shrubs and herbs, and the restoration target is the target increase in soil water holding capacity during the restoration period. In the central area, shrub canopy cover is considered a key factor influencing the restoration goals. A second relationship model is established between site condition parameters and shrub canopy cover when adopting the standard restoration scheme for the central area. The second relationship model is the relationship between air temperature, wind speed, evaporation intensity, air humidity, gravel content, and shrub canopy cover. Based on the current site condition parameters in the central area and the second relationship model, the predicted value of shrub canopy cover is obtained. The restoration scheme for the central area is then determined based on the predicted value of shrub canopy cover and the target shrub canopy cover. And / or, in the lower zone, the planting survival rate is a key factor affecting the remediation target of the lower zone. A third relationship model is established between the site condition parameters corresponding to the lower zone standard remediation scheme and the planting survival rate. The third relationship model is the relationship between air temperature, wind speed, evaporation intensity, air humidity, gravel content, soil thickness and planting survival rate. Based on the current site condition parameters of the lower zone and the third relationship model, the predicted value of the planting survival rate is obtained. Based on the predicted value of the planting survival rate and the target value of the planting survival rate, the remediation scheme of the lower zone is determined.

2. The method for coordinated ecological restoration of arid valleys based on slope position classification according to claim 1, characterized in that, The slope grading model calculates the slope index S according to the following formula: S=f1×T n +f2×W n +f3×E n +f4×H n +f5×D n +f6×G n Among them, T n W n E n H n D n G n These correspond to the normalized values ​​of air temperature, wind speed, evaporation intensity, air humidity, soil layer thickness, and soil gravel content, respectively, with a value range of [0, 1]. f1, f2, f3, f4, f5, and f6 are the corresponding weights, and the weights of air temperature, wind speed, and evaporation intensity are greater than the weights of air humidity, soil layer thickness, and soil gravel content. The slope is divided into zones based on the slope position index S and the slope position classification threshold interval, which is obtained through cluster analysis combined with expert experience.

3. The method for ecological collaborative restoration of arid valleys based on slope position classification according to claim 1, characterized in that, The steps for determining the central zone restoration plan based on the predicted shrub canopy coverage and the target shrub canopy coverage include: When the predicted shrub canopy coverage reaches the target shrub canopy coverage requirement, the standard central zone restoration scheme is adopted as the central zone restoration scheme; when the predicted shrub canopy coverage does not reach the target shrub canopy coverage requirement, the optimized standard central zone restoration scheme is adopted as the central zone restoration scheme.

4. The method for coordinated ecological restoration of arid valleys based on slope position classification according to claim 1, characterized in that, The steps for determining the remediation plan for the next area based on the predicted and target survival rates of the plants include: When the predicted survival rate of the planted plants reaches the target survival rate, the standard remediation plan for the lower zone is adopted as the remediation plan for the lower zone; when the predicted survival rate of the planted plants does not reach the target survival rate, the optimized standard remediation plan for the lower zone is adopted as the remediation plan for the lower zone.

5. The method for coordinated ecological restoration of arid valleys based on slope position classification according to claim 1, characterized in that, Obtain the first coupling influence coefficient between shrub canopy coverage and the decrease in soil moisture evaporation. Based on the first coupling influence coefficient and the changes in site condition parameters, establish a first coupling relationship model between the change in shrub canopy coverage and the change in the decrease in soil moisture evaporation. The shrub canopy coverage and current site condition parameters are obtained during the monitoring period. Based on the changes in the current shrub canopy coverage and site condition parameters and the first coupling relationship model, the change in the current soil moisture evaporation rate is obtained. Based on the change in the current soil moisture evaporation rate, it is determined whether the remediation plan for the central area needs to be optimized.

6. The method for coordinated ecological restoration of arid valleys based on slope position classification according to claim 1, characterized in that, Obtain the second coupling influence coefficient between planting survival rate and soil water holding capacity increase. Based on the second coupling influence coefficient and the change in site condition parameters, establish a second coupling relationship model between the change in planting survival rate and the change in soil water holding capacity increase. The plant survival rate and current site condition parameters are obtained during the monitoring period. Based on the changes in the current plant survival rate and site condition parameters and the second coupling relationship model, the change in the current soil water holding capacity is obtained. Based on the change in the current soil water holding capacity, it is determined whether the remediation plan for the lower area needs to be optimized.

7. A collaborative ecological restoration system for arid river valleys based on slope grading, characterized in that, The method for collaborative ecological restoration of arid valleys based on slope grading as described in any one of claims 1-6 includes: The first module is used to divide the slope of the arid valley into zones based on the site condition parameters of each area of ​​the arid valley slope using a slope grading model. The second module is used to output the corresponding repair plan based on the relationship model and site condition parameters of each zone. The third module is used to obtain the current change in soil moisture evaporation based on the first coupling influence coefficient between the obtained shrub canopy coverage and the decrease in soil moisture evaporation, and the first coupling relationship model between the change in shrub canopy coverage and the change in the decrease in soil moisture evaporation established based on the first coupling influence coefficient and the change in site condition parameters, the change in shrub canopy coverage and the current site condition parameters during the monitoring period, and to determine whether the remediation plan for the central area needs to be optimized based on the current change in the decrease in soil moisture evaporation. The fourth module is used to obtain the current change in soil water holding capacity based on the second coupling influence coefficient between the obtained planting survival rate and the increase in soil water holding capacity, and the second coupling relationship model between the change in planting survival rate and the change in soil water holding capacity established based on the second coupling influence coefficient and the change in site condition parameters, the planting survival rate during the monitoring period, and the change in the current site condition parameters. Based on the current change in soil water holding capacity, it is used to determine whether the remediation plan for the lower area needs to be optimized.

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