A method for estimating and configuring soil and water conservation herb cover

Abstract

The present invention relates to the field of soil and water conservation technology and discloses a method for estimating and configuring soil and water conservation herb cover. The method specifically comprises the following steps: investigating and determining the herb cover in each sample plot; secondly, establishing a functional relationship between the plant's underground root density and the aboveground cover; further, measuring the soil detachment rate and saturated hydraulic conductivity to characterize the soil's soil and water conservation functions; analyzing the relationship between the two parameters and the root density to determine whether the relative soil detachment rate is ≤0.00816 and the saturated hydraulic conductivity is ≥0.54 cm·min ‑1 Root density can be used to estimate the corresponding herb cover. For grasslands with a mixture of taproot and fibrous root herbs, the same method should be used to first determine the fibrous root herb cover that corresponds to the same water and soil conservation function as described above. This can then indirectly determine the taproot herb cover. Using this calculated herb cover to optimize the herbaceous plant ratio will better maximize the soil and water conservation function of the herbs.

Description

Technical Field

[0001] The invention belongs to the technical field of soil and water conservation, and in particular relates to a method for estimating and configuring soil and water conservation herb cover. Technical Background

[0002] With the implementation of ecological projects, the ecological environment continues to improve. Vegetation plays a crucial role in soil erosion prevention and ecological restoration. However, while excessive vegetation density is beneficial for soil erosion prevention, it can exacerbate soil moisture depletion. Particularly in arid and semi-arid regions, low precipitation and high evaporation can lead to insufficient soil moisture for plant growth, even leading to risks of soil drying and vegetation degradation in some areas. Therefore, scientifically and rationally planning tree and grass planting densities has become a major challenge in the current fields of soil and water conservation and ecological restoration.

[0003] Traditional research often relies on indoor simulation experiments, artificially cultivating and manipulating vegetation cover, then using rainfall and indoor water flushing tests to obtain relatively reliable coverage data. However, this approach faces challenges such as long plant cultivation cycles and large experimental workloads. Furthermore, indoor experiments are often conducted on reconstituted soils, and the results obtained may differ from actual results under natural conditions. Summary of the Invention

[0004] In response to the deficiencies in the prior art, the present invention provides a method for estimating the optimal herbaceous cover with soil and water conservation function, in order to solve the problem that the herbaceous cover does not meet the local environmental conditions during the process of soil and water loss control. Taking natural grassland as the research object, the relationship between aboveground cover and underground root density is constructed by utilizing the large heterogeneity of plant growth, and the appropriate herbaceous cover is further inferred. On the one hand, this method analyzes the characteristics of existing grasslands and does not require artificial plant cultivation, and has the advantages of a short test cycle and simple operation; on the other hand, it takes the original root-soil complex as the research object, avoiding the influence of the use of reconstructed soil in the indoor test process on the results. The obtained results are closer to the natural growth conditions and have stronger guidance for engineering. In addition, on the basis of determining the herbaceous cover, a suitable herbaceous optimized configuration structure can also be obtained to adapt to the local ecological environment and development needs, which is of great significance for maintaining ecological balance and promoting sustainable development.

[0005] To achieve the above object, the present invention adopts a technical solution: a method for estimating and configuring soil and water conservation herb cover, the method comprising the following steps:

[0006] Step 1: Set up multiple sample plots on the natural grassland slope and obtain the herb cover of each sample plot;

[0007] Step 2: Establish a functional relationship between the surface cover and underground root density of herbaceous plants;

[0008] Step 3: Collect undisturbed root-soil complex samples and measure the relative soil detachment rate and saturated hydraulic conductivity of herbaceous plants to characterize the soil and water conservation functions;

[0009] Step 4: Based on the completion of Step 3, measure the root density of the herbaceous plants within the original root-soil complex. If the grassland is a mixture of taproot and fibrous root herbs, manually select the roots of the taproot and fibrous root herbs to determine the root density of the fibrous root herbs.

[0010] Step 5: Analyze the relationship between relative soil separation rate, saturated hydraulic conductivity and root density, and determine when the soil and water conservation performance reaches the critical value (relative soil separation rate ≤ 0.00816 and saturated hydraulic conductivity ≥ 0.54 cm·min -1 ) root density, and based on the functional relationship established in step 2, estimate the total surface herb cover corresponding to the root density;

[0011] Step 6: If it is a mixed grassland, based on step 5, the relationship between the relative soil separation rate, saturated hydraulic conductivity and the root density of fibrous root herbs in the mixed grassland should be analyzed to determine the herbaceous coverage of fibrous root plants in the mixed grassland. The coverage of taproot herbs in the mixed grassland can be determined by the difference between the total herbaceous coverage of the mixed grassland and the coverage of fibrous root herbs in the mixed grassland, thereby determining the configuration ratio of different plants in the mixed grassland.

[0012] Preferably, the step 1 is:

[0013] Six 1×1m plots were randomly placed on the grassland slope, and the total herb cover V of the mixed plot was obtained by combining digital photogrammetry and software. HB and the total herbaceous cover V of the single fibrous root system plot B .

[0014] Preferably, the step 2 is:

[0015] In mixed plots and single root plots, root-soil complex samples were collected from the sample plots. The root-soil complex samples were washed and collected. After obtaining the root length density, the root-soil complex samples were dried to obtain the root weight density. HB and root density (RMD hb , RLD hb ) (Formula 1, Formula 2), the surface coverage of single fibrous root system grassland V B and root density (RMD b , RLD b ) (Formula 3, Formula 4) are as follows:

[0016] RMD hb=0.09×V HB -0.62(1)

[0017] RLD hb =0.30×V HB -1.32(2)

[0018] RMD b =0.18×V B -4.81(3)

[0019] RLD b =0.87×V B -24.94(4)

[0020] Where V HB is the coverage of mixed grassland, V B is the coverage of grassland with a single fibrous root system, RMD hb and RMD b The root weight density of mixed grassland and the root weight density of single fibrous root system grassland (kg·m -3 ); RLD hb and RLD b The root length density of mixed grassland and the root length density of single fibrous root system grassland (cm·cm -3 ).

[0021] If it is difficult to construct the functional relationship between the surface cover and root density of mixed grassland and the functional relationship between the surface cover and root density of fibrous root grassland, then the formulas (5) and (6) applicable to both types of grasslands are used.

[0022] RMD=0.15×V-3.12(5)

[0023] RLD=0.71×V-18.57(6)

[0024] Where V is the coverage of grassland (%).

[0025] Preferably, the step 3 is:

[0026] The original soil samples of root-soil composites were collected from each sample plot of mixed grassland, and the soil separation rate was determined by soil separation test. 草 and bare earth SDR 裸 The ratio of soil separation rates was used to obtain the relative soil separation rate RSD (Equation 7), which was used to characterize the soil conservation function;

[0027]

[0028] Original soil samples of root-soil composites were collected, and the saturated hydraulic conductivity of the soil was determined using the constant head method to characterize the water retention function of the soil.

[0029] Preferably, the step 4 is:

[0030] After the soil separation test, the root density in the ring cutter was obtained; for mixed grasslands, the roots of different plant species were manually selected to obtain the corresponding root weight density and root length density.

[0031] Preferably, the step 5 is:

[0032] The relationship between relative soil detachment rate and root weight density, root length density, and the relationship between saturated hydraulic conductivity and root weight density, root density were analyzed. The relative soil detachment rate decreased exponentially with the root density, and the root density corresponding to the critical detachment rate (root length density RLD) was higher than that of the critical detachment rate. HB 10.96cm·cm -3 , root mass density RMD HB 1.95 kg·m -3 ), indicating that it has good soil retention performance;

[0033] The saturated hydraulic conductivity has a quadratic function relationship with the root density, showing a trend of increasing and then decreasing. The root density (root length density RLD) corresponding to the maximum saturated hydraulic conductivity is higher or lower than that of the root density (root length density RLD). HB 21.22cm·cm -3 , root mass density RMD HB 7.17 kg·m -3 ), the saturated hydraulic conductivity will decrease, which is not conducive to water retention.

[0034] Moreover, the critical root density for achieving water retention performance is also in the root density range with better soil retention performance (RLD HB ≥10.96cm·cm -3 , RMD HB ≥1.95kg·m -3 ), therefore, it is determined that when the root density is at this level, the soil and water conservation function of the vegetation reaches the critical value (relative soil separation rate ≤ 0.00816, and saturated hydraulic conductivity ≥ 0.54 cm·min -1 ).

[0035] In determining the root length density RLD corresponding to the critical value of water and soil conservation performance HB =21.22cm·cm -3 , root mass density RMD HB =7.17kg·m -3 Based on the formula in step 2, the two corresponding herb cover V can be estimated by modifying the formula to some extent. HB1 and V HB2 , for V HB1 and V HB2 Take the average value to get the overall coverage of mixed grassland VHB If the coverage exceeds this level, it will help reduce soil erosion but will be detrimental to water infiltration; if the coverage is less than this level, its water and soil conservation functions cannot be effectively exerted.

[0036] Preferably, the step 6 is:

[0037] For mixed grassland, first determine the main species of fibrous root herbs in the sample plot. Based on step 4, obtain the root density of fibrous root herbs in the mixed sample plot. According to the relationship between coverage and root density of single fibrous root grassland established in step 2, the coverage of two fibrous root herbs in the mixed grassland is obtained based on the above root weight density and root length density. b1 and V b2 Coverage V of fibrous root herbaceous plants in mixed grasslands b According to step 5, the total coverage V of the plant in the mixed grassland is obtained. HB . Using the overall coverage of mixed grassland V HB Coverage of fibrous root grass in mixed grassland V b The difference between the two values ​​is the coverage V of taproot herbs in the mixed grassland. h ; Obtain the optimal configuration ratio of taproot and fibrous root herbs in mixed grasslands, and effectively exert the water and soil conservation functions of vegetation.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] By monitoring the root density of natural slopes, the present invention indirectly estimates the herbaceous cover with the best soil and water conservation function. This method has significant advantages such as a short test period and a small workload. In addition, the estimated results can better reflect the actual situation under natural growth conditions, thereby providing more effective technical support and decision-making reference for related engineering projects.

[0040] Based on the estimation of the optimal herbaceous cover, the present invention can also obtain the optimal configuration ratio of different plant species; and provides a formula for estimating the surface herbaceous cover based on the root density of herbaceous plants within the depth range of 0-5 cm underground;

[0041] The present invention provides a method for estimating and configuring the coverage of soil and water conservation herbaceous plants, which is to first obtain the soil and water conservation performance when it reaches the critical value (relative soil separation rate ≤ 0.00816, and saturated hydraulic conductivity ≥ 0.54 cm·min -1 ) of the herbaceous root density, and estimated the corresponding total grassland cover through the functional relationship between surface cover and underground root density, and obtained the optimal configuration ratio of taproot and fibrous root herbs. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the mixed grassland of the present invention;

[0043] Figure 2 A graph showing the relationship between aboveground coverage and underground root density of herbaceous vegetation of the present invention;

[0044] Figure 3 The relationship between relative soil separation rate, saturated hydraulic conductivity and root density of the present invention;

[0045] Figure 4 Empirical frequency analysis diagram of the present invention. DETAILED DESCRIPTION

[0046] The following diagrams illustrate various embodiments of the present invention. For clarity, many physical details will be included in the following description. However, it should be understood that these physical details are not intended to limit the present invention. In other words, in some embodiments of the present invention, these physical details are not essential. Furthermore, to simplify the illustrations, some commonly used structures and components are depicted in a simplified schematic manner.

[0047] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0048] A method for estimating and configuring soil and water conservation herb cover, the method comprising the following steps:

[0049] Step 1: Set up multiple sample plots on the natural grassland slope and obtain the herb cover of each sample plot;

[0050] Step 2: Establish a functional relationship between the surface cover and underground root density of herbaceous plants;

[0051] Step 3: Collect undisturbed root-soil complex samples and measure the relative soil detachment rate and saturated hydraulic conductivity of herbaceous plants to characterize the soil and water conservation functions;

[0052] Step 4: Based on the completion of Step 3, measure the root density of the herbaceous plants within the original root-soil complex. If the grassland is a mixture of taproot and fibrous root herbs, manually select the roots of the taproot and fibrous root herbs to determine the root density of the fibrous root herbs.

[0053] Step 5: Analyze the relationship between relative soil separation rate, saturated hydraulic conductivity and root density. When the soil and water conservation performance reaches the critical value (relative soil separation rate ≤ 0.00816 and saturated hydraulic conductivity ≥ 0.54 cm·min -1 ) root density, and based on the functional relationship established in step 2, estimate the total surface herb cover corresponding to the root density;

[0054] Step 6: If it is a mixed grassland, based on step 5, the relationship between the relative soil separation rate, saturated hydraulic conductivity and the root density of fibrous root herbs in the mixed grassland should be analyzed to determine the herbaceous coverage of fibrous root plants in the mixed grassland. The coverage of taproot herbs in the mixed grassland can be determined by the difference between the total herbaceous coverage of the mixed grassland and the coverage of fibrous root herbs in the mixed grassland, thereby determining the configuration ratio of different plants in the mixed grassland.

[0055] Furthermore, the step 1 is:

[0056] Six 1×1m plots were randomly arranged on the grassland slope. Each plot was photographed with a high-precision camera. Digital photogrammetry and Adobe Photoshop CC 2019 software were used to obtain the total herb cover V of the mixed plot. HB ( Figure 1 a) and total herbaceous cover V of single fibrous root system plots B ( Figure 1 b).

[0057] Furthermore, the step 2 is:

[0058] In mixed plots ( Figure 1 a) and single fibrous root system plots ( Figure 1 b) Using a circular cutter with a diameter of 10 cm and a height of 5 cm, collect root-soil complex samples within the sample plot. Place the root-soil complex samples on a 2 mm sieve, rinse, and collect. After obtaining the root length density using WinRHIZO software, dry the root-soil complex samples in a 65°C oven for 24 h to obtain the root weight density. Constructing the surface cover V of mixed grassland HB and root density (RMD hb , RLD hb ) (Formula 1, Formula 2), the surface coverage of single fibrous root system grassland V B and root density (RMD b , RLD b ) (Formula 3, Formula 4) are as follows:

[0059] RMD hb =0.09×V HB -0.62(1)

[0060] RLD hb =0.30×V HB -1.32(2)

[0061] RMD b =0.18×V B -4.81(3)

[0062] RLDb =0.87×V B -24.94(4)

[0063] Where V HB is the coverage of mixed grassland, V B is the coverage of grassland with a single fibrous root system, RMD hb and RMD b The root weight density of mixed grassland and the root weight density of single fibrous root system grassland (kg·m -3 ); RLD hb and RLD b The root length density of mixed grassland and the root length density of single fibrous root system grassland (cm·cm -3 ).

[0064] If it is difficult to construct the functional relationship between the surface cover and root density of mixed grassland and the functional relationship between the surface cover and root density of fibrous root grassland, then the formulas (5) and (6) applicable to both types of grasslands are used.

[0065] RMD=0.15×V-3.12(5)

[0066] RLD=0.71×V-18.57(6)

[0067] Where V is the coverage of grassland (%).

[0068] Furthermore, the step 3 is:

[0069] Using a circular ring cutter with a diameter of 10 cm and a height of 5 cm, the original soil samples of the root-soil composite in each sample square of the mixed grassland were collected. The soil separation rate was determined by the soil separation test. The SDR 草 and bare earth SDR 裸 The ratio of soil separation rates was used to obtain the relative soil separation rate RSD (Equation 7), which was used to characterize the soil conservation function;

[0070]

[0071] A circular ring cutter with a diameter of 5.05 cm and a height of 5 cm was used to collect undisturbed soil samples of root-soil composites. The saturated hydraulic conductivity of the soil was determined using the constant head method to characterize the water retention function of the soil.

[0072] Furthermore, the step 4 is:

[0073] After the soil separation test, the root density within a circular ring with a diameter of 10 cm and a height of 5 cm was measured. For mixed grasslands, the roots of different plant species were manually selected based on their color, odor, and shape to obtain the corresponding root weight density and root length density.

[0074] Furthermore, the step 5 is:

[0075] The relationship between relative soil separation rate and root weight density, root length density, and the relationship between saturated hydraulic conductivity and root weight density, root density were analyzed. The relative soil separation rate decreases exponentially with root density and can quickly reach a stable state ( Figure 3 ). The empirical frequency method was used to analyze the relative stable state of soil separation rate. First, the soil separation rates of different sessions were arranged from large to small, and the corresponding separation rates were accumulated one by one. The proportion of the accumulated separation rate greater than a certain parameter value to the total separation rate (Ps, %) was calculated. The soil separation rate RSD corresponding to Ps = 0.90 was calculated to be 0.00816, which was used as the critical value. If it is lower than this value, it means that the soil separation rate has reached a stable state and will not produce a large fluctuation with the increase of root density. Figure 3 The relationship between soil separation rate and root density in mixed grassland can be used to obtain the root length density RLD corresponding to the critical separation rate. HB 10.96cm·cm -3 , root mass density RMD HB 1.95 kg·m -3 , higher than the root density, the soil separation rate reaches a relatively stable state, which indicates that it has better soil retention performance.

[0076] The saturated hydraulic conductivity shows a quadratic function relationship with the root density, showing a trend of increasing and then decreasing. Based on this trend, the root density corresponding to the maximum saturated hydraulic conductivity is obtained. At this time, the maximum saturated hydraulic conductivity is 0.54 cm·min -1 , the corresponding root length density RLD HB 21.22cm·cm -3 , root mass density RMD HB 7.17 kg·m -3 Above or below this root density, the saturated hydraulic conductivity will decrease, which is not conducive to water retention.

[0077] Moreover, the critical root density for achieving water retention performance is also in the root density range with better soil retention performance (RLD HB ≥10.96cm·cm -3 , RMD HB ≥1.95kg·m -3 ), therefore, it is determined that when the root density is at this level, the soil and water conservation function of the vegetation reaches the critical value (relative soil separation rate ≤ 0.00816, and saturated hydraulic conductivity ≥ 0.54 cm·min -1 ).

[0078] In determining the root length density RLD corresponding to the critical value of water and soil conservation performance HB =21.22cm·cm -3 , root mass density RMD HB =7.17kg·m -3 Based on the formula in step 2, the two corresponding herb cover V can be estimated by modifying the formula to some extent. HB1 and V HB2 , where V HB1 =(7.17+0.62) / 0.09=86.56%, V HB1 =(7.17+0.62) / 0.09=74.47%, for V HB1 and V HB2 Take the average value to get the average herb cover V HB =(86.56%+74.47%) / 2=80.52%. Exceeding this coverage is beneficial to reducing soil erosion but is detrimental to water infiltration; below this coverage, its water and soil conservation functions cannot be effectively exerted.

[0079] Furthermore, the step 6 is as follows: for mixed grassland, first determine the species of the main fibrous root herbs in the sample plot, and based on step 4, obtain the root density of the fibrous root herbs in the mixed sample plot, RMD b =5.67kg·m 3 , RLD b =198.80cm·cm -3 According to the relationship between the coverage and root density of the single fibrous root system grassland established in step 2, based on the above root weight density and root length density, the coverage of the two fibrous root system herbs in the mixed grassland V is obtained. b1 and V b2 , where V b1 =(5.67+4.81) / 0.18=58.22%, V b2 =(19.80+24.94) / 0.87=51.40%, for V b1 and V b2 Take the average value to get the coverage V of fibrous root herb in mixed grassland b =(58.22%+51.40%) / 2=54.81%. According to step 5, when the critical value of water and soil conservation performance is achieved in mixed grassland (relative soil separation rate ≤ 0.00816, and saturated hydraulic conductivity ≥ 0.54 cm·min -1 ) of the total coverage of herbaceous plants V HB The overall coverage of mixed grassland is 80.52%. HB (80.52%) and the coverage of fibrous root herbaceous plants in mixed grasslands V bThe difference is 54.81%, which is the coverage V of taproot herbs in the mixed grassland. h (25.71%); that is, when the configuration ratio of taproot and fibrous root herbs in mixed grassland reaches 1:2, the water and soil conservation functions of vegetation can be effectively exerted.

[0080] Table 1 Determination of optimal herbaceous cover in grassland

[0081]

[0082]

[0083] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A method for estimating and configuring soil and water conservation herb cover, characterized in that: The method comprises the following steps: Step 1: Set up multiple sample plots on the natural grassland slope and obtain the herb cover of each sample plot; Step 2: Establish a functional relationship between the surface cover and underground root density of herbaceous plants; Step 3: Collect undisturbed root-soil complex samples and measure the relative soil separation rate and saturated hydraulic conductivity of the herbaceous plant to characterize the soil's soil and water retention capabilities. The critical value of the relative soil separation rate is ≤0.00816, and the critical value of the saturated hydraulic conductivity is ≥0.54 cm·min -1 ; Step 4: Based on the completion of Step 3, measure the root density of the herbaceous plants within the original root-soil complex. If the grassland is a mixture of taproot and fibrous root herbs, manually select the roots of the taproot and fibrous root herbs to determine the root density of the fibrous root herbs. Step 5: Analyze the relationship between relative soil separation rate, saturated hydraulic conductivity, and root density, and determine that the relative soil separation rate is ≤ 0.00816 and the saturated hydraulic conductivity is ≥ 0.54 cm·min -1 Based on the functional relationship established in step 2, the total surface herb cover corresponding to the root density is estimated; Step 6: If it is a mixed grassland, based on step 5, the relationship between the relative soil separation rate, saturated hydraulic conductivity and the root density of fibrous root herbs in the mixed grassland should be analyzed to determine the herbaceous coverage of fibrous root plants in the mixed grassland; the coverage of taproot herbs in the mixed grassland can be determined by the difference between the total herbaceous cover of the mixed grassland and the coverage of fibrous root herbs in the mixed grassland, thereby determining the optimal configuration ratio of different plants in the mixed grassland; the optimal configuration ratio of taproot and fibrous root herb coverage in the mixed grassland is 1:

2.

2. The method for estimating and configuring soil and water conservation herb cover according to claim 1, characterized in that: The step 1 is: Six 1×1m plots were randomly placed on the grassland slope to obtain the total herb cover V of the mixed plot. HB and the total herbaceous cover V of the single fibrous root system plot B .

3. The method for estimating and configuring soil and water conservation herb cover according to claim 1, characterized in that: The step 2 is: In mixed plots and single root plots, root-soil complex samples were collected from the plots. The root-soil complex samples were washed and collected. After obtaining the root length density, the root-soil complex samples were dried to obtain the root weight density. The surface cover V of the mixed grassland was constructed. HB and root density RMD hb , RLD hb The functional relationship is as follows: (1) and (2), the surface coverage of a single fibrous root system grassland V B and root density RMD b , RLD b The functional relationship (3) and (4) are as follows: RMD hb =0.09×V HB -0.62 (1) RLD hb =0.30×V HB -1.32 (2) RMD b =0.18×V B -4.81 (3) RLD b =0.87×V B -24.94 (4) Where V HB is the coverage of mixed grassland, V B is the coverage of grassland with a single fibrous root system, RMD hb is the root mass density of mixed grassland, RMD b RLD is the root density of grassland with a single fibrous root system; hb is the root length density of mixed grassland, RLD b The root length density of grassland with a single fibrous root system; If it is difficult to construct the functional relationship between the surface cover and root density of mixed grassland and the functional relationship between the surface cover and root density of fibrous root grassland, then the formulas (5) and (6) applicable to both types of grasslands are used. RMD=0.15×V-3.12 (5) RLD=0.71×V-18.57 (6) Where V is the coverage of grassland.

4. The method for estimating and configuring soil and water conservation herb cover according to claim 1, characterized in that: The step 3 is: The original soil samples of root-soil composites were collected from each sample plot of mixed grassland, and the soil separation rate was determined by soil separation test. 草 and bare earth SDR 裸 The ratio of soil separation rate to obtain the relative soil separation rate RSD is formula (7), which is used to characterize the soil conservation function of the soil; Original soil samples of root-soil composites were collected and the saturated hydraulic conductivity of the soil was measured. The saturated hydraulic conductivity was used to characterize the water retention function of the soil.

5. The method for estimating and configuring soil and water conservation herb cover according to claim 1, characterized in that: The step 4 is: For mixed grasslands, the roots of different plant species were manually selected to obtain the corresponding root weight density and root length density.

6. The method for estimating and configuring soil and water conservation herb cover according to claim 1, characterized in that: The step 5 is: The relationship between relative soil detachment rate and root weight density, root length density, and the relationship between saturated hydraulic conductivity and root weight density, root system density were analyzed. The relative soil detachment rate decreased exponentially with root system density, and was higher than that of root length density RLD. HB 10.96cm·cm -3 , root weight density RMD HB 1.95 kg·m -3 , indicating good soil retention performance; The saturated hydraulic conductivity showed a quadratic function relationship with the root density, showing a trend of increasing and then decreasing, which was higher or lower than the maximum saturated hydraulic conductivity of 0.54 cm·min -1 The corresponding root density is, among which, the root length density RLD HB 21.22cm·cm -3 , root mass density RMD HB 7.17 kg·m -3 , the saturated hydraulic conductivity will decrease, which is not conducive to water retention; Based on the root density corresponding to the critical value of water and soil conservation performance, the corresponding two herbaceous cover V HB1 and V HB2 , for V HB1 and V HB2 Take the average value to get the overall coverage of mixed grassland V HB .

7. The method for estimating and configuring soil and water conservation herb cover according to claim 3, characterized in that The step 6 is: Based on step 4, the root density of fibrous root herbs in the mixed plot was obtained. According to the relationship between the coverage and root density of the single fibrous root grassland established in step 2, the coverage of the two fibrous root herbs in the mixed grassland was obtained based on the above root weight density and root length density. b1 and V b2 Coverage V of fibrous root herbaceous plants in mixed grasslands b ; According to step 5, the total coverage V of the plant in the mixed grassland is obtained HB ; Using the overall coverage of mixed grassland V HB Coverage of fibrous root grass in mixed grassland V b The difference between the two values ​​is the coverage V of taproot herbs in the mixed grassland. h And the optimal configuration ratio of taproot and fibrous root herbs in mixed grasslands.

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