Populus euphratica clone sub-plant water utilization strategy optimization method based on branched percolation rotation irrigation

Abstract

The invention discloses a populus euphratica cloned sub-plant water utilization strategy optimization method based on branch seepage rotation irrigation, and relates to the technical field of desert plant ecological restoration, the optimization method comprises the following specific steps: selecting a branch seepage rotation irrigation ecological restoration test area, dividing a root cutting area and digging a root cutting ditch, and adopting three irrigation modes for processing; determining a cloned child plant-mother plant pair as a research object in September after three years; synchronously collecting multiple types of samples, and sealing and storing at low temperature; treating the sample and measuring indexes; quantifying a water contribution proportion through a comparison method and a model, determining an optimal irrigation mode, and optimizing a water utilization strategy; by combining the multi-mode irrigation and isotope analysis technology, the water source of the populus euphratica cloned sub-plants is accurately analyzed, a traditional experience-driven mode is broken through, the water resource utilization efficiency is improved, meanwhile, the Bayesian model is utilized to quantify the water absorption difference of the cloned sub-plants of different tree ages, a theoretical basis is provided for formulating a differential irrigation scheme, and the method is suitable for popularization and application. And sustainable restoration of an ecological system is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of desert plant ecological restoration, in particular to a Populus euphratica clonal ramet water utilization strategy optimization method based on bifurcated infiltration wheel irrigation. BACKGROUND

[0002] Ecological restoration in arid regions is a key area of global ecological environment management, and water management for vegetation restoration is a core challenge. Populus euphratica, as a key species in inland river basins, has clonal reproduction characteristics, making it an ideal choice for ecological restoration. However, under extreme climate conditions in arid regions, the temporal and spatial distribution of surface water and groundwater resources is extremely uneven, and traditional irrigation methods cannot accurately match the water requirements of Populus euphratica clonal ramets. In recent years, the development of isotope tracing technology has provided a new tool for analyzing plant water sources. By measuring the stable isotope ratios of plant xylem water and potential water sources, the contribution of different water sources to plant water uptake can be quantified. Combined with bifurcated infiltration wheel irrigation technology, how to optimize the irrigation mode to guide Populus euphratica clonal ramets to efficiently use surface water and reduce dependence on mother plant water storage has become a key scientific problem for improving ecological restoration effectiveness.

[0003] Traditional irrigation management in ecological restoration has several limitations: first, the irrigation mode is monotonous, usually adopting a one-size-fits-all strategy with fixed intervals and water quantities, without considering the differentiated water needs of Populus euphratica clonal ramets at different developmental stages. For example, two-year-old seedlings may rely more on surface water, while four-year-old individuals may have the ability to use deep soil water. However, the traditional mode cannot dynamically adjust the water supply structure. Second, the water source analysis is extensive, often relying on indirect inference through apparent growth indicators, lacking precise positioning of the actual plant water uptake layer. Although some studies use isotope technology, they only qualitatively determine the water uptake layer without quantifying the specific contribution ratios of mother plants, surface water, and soil water at each layer, leading to a lack of scientific basis for irrigation optimization. In addition, traditional methods rarely consider the water connection between clonal plant mother plants and ramets, which may result in irrigation schemes that do not accurately match the needs of ramet developmental stages. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a Populus euphratica clonal ramet water utilization strategy optimization method based on bifurcated infiltration wheel irrigation. By setting up multi-mode irrigation tests in the ecological restoration test area of the lower reaches of the Tarim River, and combining liquid water isotope tracing and Bayesian mixture models, the water contribution ratios of mother plants, surface water, and soil water at each layer to clonal ramets are accurately quantified. This method breaks through the limitations of traditional irrigation relying on experience and extensive water source analysis, reveals the water utilization differences of clonal ramets at different ages, and selects the optimal irrigation mode that can reduce mother plant dependence and improve surface water utilization efficiency, providing a scientific and efficient water resource management scheme for ecological restoration in arid regions.

[0005] The application provides a Populus euphratica clone daughter plant water utilization strategy optimization method based on a seepage wheel irrigation, and the specific steps of the optimization method are as follows: S100, test site selection and pretreatment: a seepage wheel irrigation ecological restoration test area containing broken root sprouting, flooding seed dispersal and ecological carrying capacity test area is selected, and the broken root sprouting test area is divided into three regions D1, D2 and D3 according to the terrain; when the Populus euphratica mother plant has not germinated, 18 broken root trenches with a depth of 70-90 cm, a width of 30-50 cm and a length of 15-20 m are excavated at a distance of 5-10 m from the Populus euphratica mother plant, and then the three irrigation modes F1, F2 and F3 are used for treatment; the seepage wheel irrigation ecological restoration test area is located in Ruoqiang County and Weili County in the lower reaches of the Tarim River, between the old Tarim River and Qiwenkuer River, and is a river section controlled by the Kunasite ecological gate; S200, determination of research objects: in September three years after the irrigation treatment, Populus euphratica broken root daughter plants with good growth vigor in different irrigation modes are selected, the mother plants connected with the Populus euphratica broken root daughter plants are found through clone root tracing, and the clone daughter plant-mother plant pairs are determined as research objects; S300, collection of multiple types of samples: plant, soil, surface water and groundwater samples are collected synchronously from the selected research objects, all the samples are sealed in brown containers and stored at low temperature; S400, sample treatment and index determination: the soil samples are subjected to drying treatment, and the water content and water content rate are calculated; the liquid water in the plant xylem and soil is extracted by using a LI-2100 full-automatic vacuum condensation extraction system, and the O and H in the groundwater, surface water, soil water in each layer and plant xylem water are determined by using a LWIA-912-0008 liquid water isotope analyzer. S500, data analysis and strategy optimization: the water absorbing soil layers of the Populus euphratica clone daughter plant and the mother plant are preliminarily judged by using a direct comparison method, and the influence of precipitation is excluded, then the water contribution proportions of the mother plant, surface water and soil water in each layer to the clone daughter plant are quantified by using a Bayesian mixture model, the optimal irrigation mode is determined according to the analysis result, and the water utilization strategy optimization is completed.

[0006] Further, in the S100, test site selection and pretreatment, the three irrigation modes F1, F2 and F3 are as follows: the F1 mode has an irrigation interval of 11 days, an irrigation water volume of 6 m³ / 10 m and an irrigation duration of 2 days; the F2 mode has an irrigation interval of 23 days, an irrigation water volume of 7 m³ / 10 m and an irrigation duration of 3 days; and the F3 mode has an irrigation interval of 33 days, an irrigation water volume of 8 m³ / 10 m and an irrigation duration of 4 days.

[0007] Further, in the S200, the different tree ages include two-year-old, three-year-old and four-year-old, and the number of determined clone daughter-mother pairs is 16 pairs. The grouping of the 16 pairs of clone daughter-mother pairs under the F1, F2 and F3 irrigation modes is as follows: the F1 mode includes two-year-old D1P7S2, D1P3S3, three-year-old D1P2S5 and four-year-old D2P10S1, D3P8S1; the F2 mode includes two-year-old D3P11S, three-year-old D3P11S1, D3P11S2 and four-year-old D3P11S8, B1P1S1; and the F3 mode includes two-year-old D1P10S2, D2P13S14, three-year-old D1P10S1, D2P6S1, four-year-old D2P4S7 and D2P13S2, wherein D represents the root-cut sprouting research area, P is the number of adult Populus euphratica, S is the number of clone seedlings, and B is the adult Populus euphratica not included in the root-cut sprouting research area.

[0008] Further, in the S300, the plant samples include xylem stems and clone roots in the multi-type sample collection; the xylem stems have a diameter of 0.3-0.5 mm and a length of 3-5 cm, and 5 roots are collected from each Populus euphratica; 3-5 segments of clone roots are collected from each pair, and each segment has a length of 3-5 cm; and the recorded ecological indexes of Populus euphratica before sampling include crown width, height and diameter at breast height, and the distance between the clone daughter and the mother plant, i.e., the length of the clone root, is also recorded.

[0009] Further, in the S300, the soil samples are collected in layers in the multi-type sample collection: 20-100 cm from the ground surface, with each 20 cm as a layer; 100-350 cm from the ground surface, with each 50 cm as a layer; and 3 sample bottles and 1 self-sealing bag of soil samples are collected from each layer.

[0010] Further, in the S300, the surface water sampling is performed by first cleaning the brown screw thread sampling bottle with surface water, then placing the sampling bottle in the water for 30 seconds; the underground water sampling is performed by first cleaning the Bell tube and the sampling bottle with water, then placing the Bell tube in the water well for 30 seconds, and then moving the underground water in the Bell tube into the sampling bottle; and 3 repeated samples of surface water and underground water are collected.

[0011] Further, in the S500, in the data analysis and strategy optimization, when the direct comparison method is used, the possible soil layer for water absorption of the clone daughter and the mother plant is preliminarily determined in combination with the precipitation and the strong evaporation fractionation effect in the extreme arid area downstream of the Tarim River, and is used to exclude the possibility of precipitation as the main water source.

[0012] Further, in the S500, in the data analysis and strategy optimization, the calculation formula of the Bayesian mixture model is as follows: wherein represents the stable isotope ratio of the xylem water of Populus euphratica clone daughter. is the contribution rate of the i-th end member, that is, the proportion of a certain water source in the total water absorption of the poplar clone, is the stable isotope ratio of the i-th end member, indicating the stable isotope ratio of each potential water source, is the effect coefficient of the covariate reflecting the influence degree of the environmental variable on the water source contribution rate, which is calculated by Bayesian statistical inference combined with MCMC algorithm, represents the covariate, indicating the environmental variable affecting the water utilization of the poplar, is the observation error, is the stable isotope ratio of the xylem water of the poplar clone; The effect coefficient is calculated by Bayesian statistical inference combined with MCMC algorithm. First, a normal prior distribution with a mean of 0 and a large variance is set for the effect coefficient. Then, based on the data of the stable isotope ratio of the xylem water of the poplar clone, the stable isotope ratio of each potential water source and the environmental variable affecting the water utilization of the poplar, a likelihood function containing the effect coefficient is constructed. According to the Bayesian theorem, the prior distribution and the likelihood function are combined to construct the posterior probability distribution of the effect coefficient. Then, the Markov chain Monte Carlo algorithm is used to sample the posterior probability distribution to generate a large number of effect coefficient samples conforming to the distribution. When the sample size meets the requirements and the sampling process converges, the mean or median of the samples is taken as the optimal estimate value of the effect coefficient, and the standard deviation of the samples is used to measure the uncertainty of the estimate value.

[0013] Further, in the data analysis and strategy optimization, the specific steps of the water utilization strategy optimization are as follows: based on the water contribution proportions of the mother plant, surface water and each layer of soil water to the poplar clone obtained by the Bayesian mixture model, the variation characteristics of the water contribution proportions of the mother plant, surface water and deep soil water under different irrigation modes are analyzed and compared, and combined with the water utilization characteristics of the poplar clone of different ages, the irrigation mode that reduces the contribution proportion of the mother plant, increases the contribution proportion of the surface water and maintains the contribution proportion of the deep soil water at an effective level is selected as the optimal water utilization strategy for the poplar clone.

[0014] Compared with the prior art, the poplar clone water utilization strategy optimization method based on the bifurcated infiltration wheel irrigation has the following beneficial effects: I. The present application realizes accurate analysis of the water source of Populus euphratica clone daughter plants by combining multi-mode irrigation test and isotope analysis technology. In traditional ecological restoration, irrigation mode often relies on experience and lacks scientific judgment of the actual water absorption layer of plants, resulting in waste of water resources or poor restoration effect. The method quantifies the water contribution proportion of mother plants, surface water and soil water of each layer to clone daughter plants through root cutting and sprouting test combined with liquid water isotope tracing technology, breaks through the limitations of traditional methods relying only on apparent growth indicators, changes the selection of irrigation mode from experience-driven to data-driven, improves the efficiency of water resource utilization, and provides a replicable and quantifiable technical paradigm for ecological restoration in arid regions.

[0015] II. The present application quantifies the regulatory effect of environmental variables on water sources by Bayesian mixed models. In traditional research, much attention is paid to single tree age or overall community, and the dependence of clonal plants on water sources at different development stages is ignored. The method compares the water absorption strategies of two-year-old, three-year-old and four-year-old clone daughter plants by grouping, finds that optimizing irrigation mode can significantly reduce the proportion of mother plant water contribution, while improving the utilization rate of surface water and maintaining the effective supply of deep soil water. This mechanism provides a theoretical basis for vegetation restoration in arid regions: different irrigation schemes are developed for individuals of different ages, which can avoid excessive consumption of mother plant water storage and promote the independent survival ability of clone daughter plants, and ultimately realize the sustainable restoration of the ecosystem.

[0016] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following specification, and it is intended to cover any alternatives, modifications, or equivalents included within the scope of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work on the basis of these drawings.

[0018] Figure 1 Flow chart of Populus euphratica clone daughter plant water utilization strategy optimization method based on seepage irrigation; Figure 2 Schematic diagram of functional zoning of seepage irrigation ecological restoration test area; Figure 3 Schematic diagram of the positional relationship between Populus euphratica clone daughter plants and mother plants and surrounding water sources; Figure 4 Soil water content profile distribution characteristic diagram of different soil layer depths; Figure 5 A graph showing the contribution ratio of water sources to Populus euphratica clones under different irrigation gradients; Figure 6 A graph showing the contribution ratio of water sources to Populus euphratica clones of different ages; Figure 7 A comparison chart of the proportion of water source utilization by Populus euphratica clones under different irrigation gradients; Figure 8 A comparison chart showing the proportion of water source utilization for cloned poplar trees of different ages. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] Example 1: S100, Site selection and pretreatment, such as Figure 1 As shown: The experimental site for this embodiment was also selected in the infiltration and rotational irrigation ecological restoration experimental area located in Ruoqiang County and Yuli County in the lower reaches of the Tarim River. This area is situated between the old Tarim River channel and the Qiwenkuoer River, controlled by the Kunaste ecological gate, and includes a root-cutting and sprouting, overflow seeding, and ecological carrying capacity experimental area. Figure 2 As shown, the area has numerous river networks and ditches, with multiple water sources including shallow soil water, groundwater, and surface water. The water resources exhibit strong spatial heterogeneity, and the poplar trees are concentrated in the area, making it an ideal location for conducting experiments.

[0021] In the root pruning and sprouting experimental area, the terrain was divided into three areas: D1, D2, and D3. From the end of March to the beginning of April 2021, before the mother trees of Populus euphratica sprouted, 18 root pruning trenches were dug 5-10m away from the mother trees in a sunny location, with the soil moisture holding capacity being good and the mother trees growing well. The trenches were 70-90cm deep, 30-50cm wide, and 15-20m long.

[0022] Subsequently, three irrigation modes, F1, F2, and F3, were used for treatment. In mode F1, the irrigation interval was 11 days, the irrigation water volume was 6 m³ / 10 m, and the irrigation duration was 2 days. In mode F2, the irrigation interval was 23 days, the irrigation water volume was 7 m³ / 10 m, and the irrigation duration was 3 days. In mode F3, the irrigation interval was 33 days, the irrigation water volume was 8 m³ / 10 m, and the irrigation duration was 4 days.

[0023] S200, Research Subjects Determined: In September 2024, three years after the irrigation treatment, two-year-old, three-year-old and four-year-old Populus euphratica rootless seedlings in F1, F2 and F3 irrigation modes were selected, and the cloning root tracing was started from the Populus euphratica clone seedlings, until the Populus euphratica mother plant connected to it was found, and finally 16 pairs of clone seedling-mother plant pairs were determined as the research objects, as shown in Figure 3

[0024] The specific grouping is as follows: F1 mode contains two-year-old D1P7S2 and D1P3S3, three-year-old D1P2S5, and four-year-old D2P10S1 and D3P8S1; F2 mode contains two-year-old D3P11S, three-year-old D3P11S1 and D3P11S2, and four-year-old D3P11S8 and B1P1S1; F3 mode contains two-year-old D1P10S2 and D2P13S14, three-year-old D1P10S1 and D2P6S1, and four-year-old D2P4S7 and D2P13S2, wherein D represents the rootless sprouting research area, P is the number of adult Populus euphratica, S is the number of cloned seedlings, and B is the adult Populus euphratica not included in the rootless sprouting research area.

[0025] S300, multi-type sample collection: In September 2024, plant, soil, surface water and groundwater samples were collected synchronously from the selected 16 pairs of clone seedling-mother plant pairs, all samples were sealed in brown containers and stored at low temperature.

[0026] Before sampling, the crown width, height and diameter at breast height of the selected Populus euphratica were investigated and recorded, and the distance between the Populus euphratica clone seedling and the mother plant, i.e. the length of the clone root, was recorded.

[0027] The plant samples include xylem stems and clone roots, the xylem stems select suberized stems with a diameter of 0.3-0.5 mm and a length of 3-5 cm, 5 roots are collected from each Populus euphratica, the bark and phloem are removed during collection, and only the xylem is reserved; 3-5 segments of clone roots are collected from each pair of clone seedling-mother plant, each segment is 3-5 cm long, after sampling, the plant samples are quickly placed in a brown glass container, sealed with cotton, then covered with a lid, and sealed with Parafilm sealing film, the samples are numbered and labeled and stored in an incubator with ice to avoid evaporation fractionation affecting the accuracy of stable isotope determination.

[0028] ​Soil samples were collected at a distance of 50 cm from the selected Populus euphratica plant, parallel to the clonal root connecting the daughter plant and the mother plant, and the soil profile was excavated to a depth of 4 m. The sampling was stratified as follows: 20-100 cm from the ground surface, with each 20 cm as a layer, i.e., 20-40 cm, 40-60 cm, 60-80 cm, and 80-100 cm; 100-350 cm from the ground surface, with each 50 cm as a layer, i.e., 100-150 cm, 150-200 cm, 200-250 cm, 250-300 cm, and 300-350 cm. Three sample bottles and one self-sealing bag of soil sample were collected for each layer, and the same sealing and storage methods as for the plant samples were used to avoid mechanical fractionation affecting the test results.

[0029] When collecting surface water and groundwater samples, the surface water was sampled using a surface water cleaning brown screw thread mouth sampling bottle, and the sampling bottle was placed in the water for 30 seconds. The groundwater was sampled by first cleaning the bell tube and the sampling bottle with groundwater, and then placing the bell tube in the water well for 30 seconds. The groundwater sample in the bell tube was then moved into the sampling bottle. Three repeated samples of surface water and groundwater were collected, quickly capped, sealed with Parafilm sealing film, and placed in an ice box containing ice to avoid mechanical fractionation affecting the experimental results.

[0030] S400, sample processing and index determination: After completing the field collection of samples, the isotopic samples were transferred to a refrigerator for storage.

[0031] The soil samples were subjected to drying treatment. Appropriate amounts of soil samples were taken from each bag of soil sample and placed in three clean aluminum boxes, and labels were attached. The total weight of the aluminum boxes containing wet soil was measured using a high-precision electronic balance, and recorded as soil sample number-Wwet1, -Wwet2, and -Wwet3. The three aluminum boxes were placed in an oven at 105°C and dried for at least 12 hours or until the sample mass was constant. After drying, the aluminum boxes were removed from the oven and placed in a desiccator to cool to room temperature. The total weight of the aluminum boxes and dry soil was then measured and recorded as soil sample number-Wdry1, -Wdry2, and -Wdry3. The moisture content of each aluminum box of soil sample was calculated by the difference between the wet weight and the dry weight. The average value of the three repeats of the same soil sample was obtained to obtain the soil water content, and the soil water content was obtained, as shown in Figure 4

[0032] ​LI-2100 automatic vacuum condensation extraction system was used to extract liquid water in plant xylem and soil. The sample was put into the sample bottle and tightly plugged with cotton (to avoid sample debris from the sample bottle into the instrument during extraction). The heating system was heated at 130℃ for 2 hours to completely evaporate the sample. The water vapor was captured by the glass tube after passing through the cold well, and the extraction efficiency could reach 99%. LWIA-912-0008 liquid water isotope analyzer was used to measure the O and H in groundwater, surface water, soil water and plant xylem water.

[0033] S500, data analysis and strategy optimization: Considering the precipitation and strong evaporation fractionation effect in the extremely arid area of the lower reaches of Tarim River, the direct comparison method was first used to preliminarily judge the possible soil layer of Populus euphratica clone daughter plants and mother plants, and to exclude the influence of precipitation on plant water uptake.

[0034] Then, Bayesian mixture model (MixSIR) was used to quantify the water contribution proportion of mother plants, surface water and each layer of soil water to clone daughter plants. Bayesian mixture model (MixSIAR model) is a stable isotope mixing model based on Bayesian framework. The calculation formula of Bayesian mixture model is as follows: Wherein is the stable isotope ratio of Populus euphratica clone daughter plant xylem water, is the contribution rate of the i th end member, that is, the proportion of a certain water source in the total water absorption of Populus euphratica clone daughter plants, is the stable isotope ratio of the i th end member, which refers to the stable isotope ratio of each potential water source, is the effect coefficient of covariate , which reflects the influence degree of environmental variables on water source contribution rate, which is calculated by Bayesian statistical inference combined with MCMC algorithm, is the covariate, which refers to the environmental variable affecting the water use of Populus euphratica, is the observation error, is the stable isotope ratio of Populus euphratica clone daughter plant xylem water.

[0035] The effect coefficient was calculated by Bayesian statistical inference combined with MCMC algorithm. Firstly, the normal prior distribution with mean of 0 and large variance was set for the effect coefficient. Then, the likelihood function including the effect coefficient was constructed based on the stable isotope ratio of the xylem water of the clone seedlings, the stable isotope ratio of each potential water source and the environmental variables affecting the water use of P. euphratica. Next, the posterior probability distribution of the effect coefficient was constructed by combining the prior distribution with the likelihood function according to the Bayesian theorem. Subsequently, a large number of effect coefficient samples conforming to the posterior probability distribution were generated by sampling the posterior probability distribution using Markov Chain Monte Carlo algorithm. When the sample size met the requirements and the sampling process converged, the mean or median of the samples was taken as the optimal estimate of the effect coefficient, and the standard deviation of the samples was used to measure the uncertainty of the estimate.

[0036] From the analysis results, under different irrigation gradients, the mother plant had outstanding water contribution to the root-cut P. euphratica seedlings. Under F1 and F3 irrigation gradients, the average water contribution rate of the mother plant was the largest, reaching 20.28% and 18.93%, respectively, and the average contribution rate of surface water was the second, reaching 18.72% and 18.10%, respectively. Under F2 irrigation gradient, the average water contribution rate of the mother plant was only 0.04% lower than the second, reaching 18.02%, and the average contribution rate of surface water was the largest, reaching 18.06%, as shown in Table 2. Figure 5 Under different irrigation gradients, the water contribution of each layer of soil to the root-cut P. euphratica seedlings was different. Under F1 irrigation treatment, the average water contribution rate of each soil layer was the largest in the 60-80 cm layer, reaching 16.12%, followed by the 20-40 cm layer, reaching 15.72%, and the smallest in the 40-60 cm layer, reaching 13.98%. Under F3 irrigation treatment, the average water contribution rate of each soil layer was the largest in the 60-80 cm layer, reaching 17.27%, followed by the 40-60 cm layer, reaching 17.2%, and the smallest in the 20-40 cm layer, reaching 14.33%. Under F2 irrigation gradient, the average water contribution rate of each soil layer was the largest in the 20-40 cm layer, reaching 16.74%, followed by the 80-100 cm layer, reaching 16.18%, and the smallest in the 40-60 cm layer, reaching 15.22%.

[0037] Different tree age mother plants also had outstanding water contribution to the root-cut P. euphratica seedlings. The average water source of two-year-old, three-year-old and four-year-old P. euphratica seedlings was the mother plant, accounting for 19.12%, 18.48% and 19.52%, respectively, as shown in Table 3. Surface water also had outstanding contribution, accounting for 18.02%, 18.48% and 18.33%, respectively, as shown in Table 4. Figure 6 Figure 6 ​The contribution of each layer of soil water to the water of the Populus euphratica seedling is different: the contribution of the 40-60 cm soil water to the water of the two-year-old Populus euphratica seedling is the largest, with an average contribution rate of 16.52 %, the contribution of the 60-80 cm soil water is the second, with an average contribution rate of 15.88 %, and the contribution of the 80-100 cm soil water is the smallest, with an average contribution rate of 14.98 %; the largest contribution of the soil layer to the water of the three-year-old Populus euphratica seedling is the 60-80 cm soil layer, with an average contribution rate of 16.50 %, the 40-60 cm soil layer is the second, with an average contribution rate of 16.08 %, and the 80-100 cm soil layer is the smallest, with an average contribution rate of 14.80 %; for the four-year-old Populus euphratica seedling, the contribution of the 60-80 cm soil layer is the largest, the contribution of the 80-100 cm soil layer is the second, and the contribution of the 40-60 cm soil layer is the smallest, with an average contribution rate of 16.83 %, 16.37 %, and 14.37 %, respectively.

[0038] Based on the contribution proportion of each water source quantified by the Bayesian mixture model, the water utilization characteristics under different irrigation modes are analyzed and compared, such as Figure 8 As shown in the figure, combined with the water utilization characteristics of the clonal ramets of different ages, the F2 irrigation mode belongs to a moderate irrigation water amount, duration and interval time, such as Figure 7 As shown in the figure, under this mode, the contribution proportion of the parent plant to the water of the clonal ramet is reduced, the contribution proportion of the surface water is increased, and the contribution proportion of the deep soil water is maintained at an effective level, which can make the Populus euphratica seedling gradually change from mainly relying on the water of the parent plant to mainly relying on the surface water, thereby reducing the water burden of the parent plant. Therefore, the F2 irrigation mode is determined as the optimal water utilization strategy for the Populus euphratica clonal ramet, and the water utilization strategy optimization is completed.

[0039] In summary, in this embodiment, the Populus euphratica clonal ramet in the bifurcation infiltration wheel irrigation ecological restoration test area in the lower reaches of the Tarim River is taken as the research object, three irrigation modes F1, F2 and F3 are set by dividing the root-cut sprouting test area, 16 pairs of clonal ramet-parent plant pairs of different ages are selected, plant, soil, surface water and groundwater samples are systematically collected, soil moisture and hydrogen and oxygen isotopes of each water source are determined after treatment, and the contribution proportion of water is analyzed by combining the direct comparison method and the Bayesian mixture model. The results show that under the F2 mode (interval of 23 days, water amount of 7 m³ / 10 m, duration of 3 days), the dependence of the clonal ramet on the surface water is increased, the contribution of the parent plant to the water is reduced, and the contribution of the deep soil water is stable, which is the optimal strategy for the water utilization of the Populus euphratica clonal ramet, and provides a scientific basis for the irrigation management of the ecological restoration of Populus euphratica in the arid region.

[0040] Example Two: S100, selection and pretreatment of the test site: The Tarim River downstream of the Ruoqiang County and the Yuli County was selected as the experimental area for the ecological restoration of the branch seepage irrigation. The area is located between the old Tarim River and the Qiwenguer River, belongs to the Kun-Ast ecological gate controlled river section, contains the broken root sprouting, overflow drifting seed and ecological carrying capacity test area, has a water network composed of river network and branch, strong spatial heterogeneity of water resources, concentrated distribution of Populus euphratica, and surface water, soil water and groundwater supply.

[0041] The broken root sprouting test area is divided into D1, D2 and D3 regions according to the terrain. From the end of March to the beginning of April 2021, when the Populus euphratica mother plants have not yet sprouted, 18 broken root trenches with a depth of 70-90 cm, a width of 30-50 cm and a length of 15-20 m are excavated at a distance of 5-10 m from the mother plants in sunny and well-moistured soil sections with good growth conditions of the mother plants. Then, three irrigation modes F1, F2 and F3 are adopted: F1 interval 11 days, water volume 6 m³ / 10 m, duration 2 days; F2 interval 23 days, water volume 7 m³ / 10 m, duration 3 days; F3 interval 33 days, water volume 8 m³ / 10 m, duration 4 days.

[0042] S200, research object determination: In September 2024, two-year-old, three-year-old and four-year-old Populus euphratica broken root seedlings under the three irrigation modes were selected, the connected mother plants were found by tracing the cloned roots, and 16 pairs of cloned seedling-mother plant pairs were determined, including two-year-old D1P7S2, D1P3S3, three-year-old D1P2S5, four-year-old D2P10S1 and D3P8S1 under F1 mode, two-year-old D3P11S, three-year-old D3P11S1, D3P11S2, four-year-old D3P11S8 and B1P1S1 under F2 mode, and two-year-old D1P10S2 and D2P13S14, three-year-old D1P10S1 and D2P6S1, four-year-old D2P4S7 and D2P13S2 under F3 mode, wherein D represents the broken root sprouting research area, P is the number of adult Populus euphratica, S is the number of cloned seedlings, and B is the adult Populus euphratica not included in the broken root sprouting research area.

[0043] S300, multiple types of sample collection: Plant, soil, surface water and groundwater samples were collected simultaneously. Plant samples were 5 pieces of 0.3-0.5 mm diameter, 3-5 cm long xylem stems (without bark and phloem) and 3-5 pieces of 3-5 cm long cloned roots, the crown width, height and cloned root length were recorded; soil samples were collected at 20-100 cm per 20 cm layer, 100-350 cm per 50 cm layer, 3 sample bottles and 1 self-sealing bag soil sample per layer; surface water was sampled after 30 seconds of standing in a brown bottle, and groundwater was sampled with a Bell tube, each with 3 replicates, all samples were stored in brown containers at low temperature.

[0044] S400, sample treatment and index determination: Soil samples were dried at 105℃ to constant weight, and their moisture content and water content were calculated. Liquid water was extracted from plant xylem and soil using a LI-2100 system, and the water content of each source was determined using an LWIA-912-0008 analyzer. O and H.

[0045] S500, Data Analysis and Strategy Optimization: Considering the arid characteristics of the lower reaches of the Tarim River, the direct comparison method was used to eliminate the influence of precipitation and determine the water-absorbing layer. Then, the contribution ratio of each water source was calculated using a Bayesian mixture model. The calculation formula for the Bayesian mixture model is as follows: The results showed that the surface water contribution rate of the F2 mode was 18.06%, which was slightly higher than that of the mother plant (18.02%). The contribution of deep soil water was stable, which could reduce the water dependence of the daughter plants on the mother plant. Therefore, it was determined to be the optimal irrigation mode, and the strategy optimization was completed.

[0046] In summary, this embodiment uses Populus euphratica clones in the ecological restoration experimental area of ​​the lower reaches of the Tarim River as the research object. By dividing the root-cutting and sprouting experimental area and setting three irrigation modes (F1, F2, and F3), 16 pairs of cloned daughter-mother plants of different ages were selected. Plant, soil, surface water, and groundwater samples were systematically collected. After processing, soil moisture content and hydrogen and oxygen isotopes of various water sources were measured. The water contribution ratio was analyzed by combining the direct comparison method and Bayesian mixture model. The results show that under the F2 mode (interval of 23 days, water volume of 7 m³ / 10 m, duration of 3 days), the cloned daughter plants' dependence on surface water increased, the water contribution of the mother plants decreased, and the contribution of deep soil water remained stable. This is the optimal water use strategy and can provide scientific support for irrigation management of Populus euphratica ecological restoration in arid areas.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for optimizing water use strategy of Populus euphratica clones based on infiltration and rotational irrigation, characterized in that, The specific steps of this optimization method are as follows: S100, Site Selection and Pretreatment: The ecological restoration experimental area of ​​infiltration rotation irrigation, which includes root-cutting and suckering, overflow seeding and ecological carrying capacity experimental areas, was selected. The root-cutting and suckering experimental area was divided into three areas, D1, D2 and D3, according to the terrain. When the Populus euphratica mother trees had not sprouted, 18 root-cutting trenches with a depth of 70-90cm, a width of 30-50cm and a length of 15-20m were dug at a distance of 5-10m from them. Then, the three irrigation modes, F1, F2 and F3, were used for treatment respectively. S200, Research Subjects Determination: In September three years after the irrigation treatment, healthy poplar root-cutting offspring of different ages were selected from different irrigation modes. The clonal root was used to trace the source of the mother plant connected to it, and the clonal offspring-mother plant pair was determined as the research subjects. S300, multi-type sample collection: plant, soil, surface water and groundwater samples are collected simultaneously for the selected research subjects. All samples are sealed in brown containers and stored at low temperature. S400, Sample Processing and Index Determination: Soil samples were dried, and moisture content and water content were calculated. Liquid water was extracted from plant xylem and soil using a LI-2100 fully automated vacuum condensation extraction system. Liquid water isotopes in groundwater, surface water, soil water at various layers, and plant xylem water were measured using an LWIA-912-0008 liquid water isotope analyzer. O and H; S500, Data Analysis and Strategy Optimization: The water-absorbing soil layers of Populus euphratica clones and mother plants are initially determined by direct comparison method and the influence of precipitation is excluded. Then, the Bayesian mixture model is used to quantify the water contribution ratio of the mother plant, surface water and soil water in each layer to the clones. Based on the analysis results, the optimal irrigation mode is determined and the water use strategy is optimized.

2. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In S100, during the selection and pretreatment of the experimental site, the three irrigation modes F1, F2, and F3 are as follows: F1 mode has an irrigation interval of 11 days, an irrigation water volume of 6 m³ / 10 m, and an irrigation duration of 2 days; F2 mode has an irrigation interval of 23 days, an irrigation water volume of 7 m³ / 10 m, and an irrigation duration of 3 days; and F3 mode has an irrigation interval of 33 days, an irrigation water volume of 8 m³ / 10 m, and an irrigation duration of 4 days.

3. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In the S200 study, the different tree ages included two-year-old, three-year-old, and four-year-old trees, and the number of cloned daughter-mother pairs was 16.

4. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In the S300 sampling process, plant samples include xylem stems and clonal roots. The xylem stems are 0.3-0.5 mm in diameter and 3-5 cm in length, with 5 stems collected from each poplar tree. For each pair of clonal roots, 3-5 segments are collected, each segment being 3-5 cm in length. The ecological indicators of the poplar tree recorded before sampling include crown width, height, and diameter at breast height (DBH). The distance between the clonal daughter tree and the mother tree, i.e., the length of the clonal root, is also recorded.

5. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In the S300 multi-type sample collection, the soil samples are collected in layers as follows: 20-100cm from the ground surface, with each layer being 20cm apart; 100-350cm from the ground surface, with each layer being 50cm apart. Three sample bottles and one self-sealing bag of soil samples are collected from each layer.

6. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In the S300 multi-type sample collection, when sampling surface water, the brown threaded sampling bottle is first cleaned with surface water, and then the sampling bottle is placed in the water and left to stand for 30 seconds; when sampling groundwater, the Bayle tube and sampling bottle are first cleaned with water, the Bayle tube is placed in the well and left to stand for 30 seconds, and then the groundwater in the Bayle tube is transferred into the sampling bottle, and three duplicate samples are collected for both surface water and groundwater.

7. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In the S500 data analysis and strategy optimization, when using the direct comparison method, the possible soil layers for water absorption by Populus euphratica clones and mother plants are preliminarily determined by combining the precipitation and strong evaporation fractionation effect in the extremely arid area of ​​the lower reaches of the Tarim River, and this is used to rule out the possibility that precipitation is the main source of water absorption.

8. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In the S500 data analysis and strategy optimization, the calculation formula for the Bayesian mixture model is as follows: ,in This indicates the stable isotope ratio of water in the xylem of Populus euphratica clones. It represents the contribution rate of the i-th endmember, i.e., the proportion of a certain water source in the total water absorption of the Populus euphratica clone. It represents the stable isotope ratio of the i-th endmember, referring to the stable isotope ratio of each potential water source. Covariates The effect coefficient, reflecting the degree of influence of environmental variables on the contribution rate of water sources, is calculated through Bayesian statistical inference combined with the MCMC algorithm. The term "covariate" refers to environmental variables that affect the water use of Populus euphratica. It is an observation error. The stable isotope ratios of xylem water in Populus euphratica clones are given.

9. The method for optimizing water use strategy of Populus euphratica clones based on infiltration rotational irrigation according to claim 1, characterized in that, In S500, the specific steps for optimizing water use strategy in data analysis and strategy optimization are as follows: Based on the proportions of water contribution from the mother plant, surface water, and soil water at each layer quantified by the Bayesian mixture model to the Populus euphratica clone progeny, analyze and compare the changing characteristics of the proportions of water contribution from the mother plant, surface water, and deep soil water under different irrigation modes. Combined with the water use characteristics of clone progeny at different ages, select the irrigation mode that reduces the proportion of water contribution from the mother plant, increases the proportion of water contribution from surface water, and maintains the proportion of water contribution from deep soil water at an effective level, and determine it as the optimized water use strategy for Populus euphratica clone progeny.

Images