Mining subsidence degrades soil structure and root-soil reinforcement, but the role of arbuscular mycorrhizal fungi (AMF) in regulating root-soil composite mechanical properties across vegetation restoration types has not been systematically investigated. We established alfalfa, Caragana, and mixed vegetation treatments in the Shenmu coal mining subsidence area of Shaanxi Province, with and without inoculation of AMF, to evaluate root characteristics, soil structure, and root-soil composite mechanical properties at different soil depths. The results showed that under non-inoculated conditions, mixed planting exhibited the highest root density and root-soil composite cohesion (RSCC) in the 0–10 cm layer, but the difference decreased with depth; in the 10–20 cm layer, Caragana monoculture and mixed planting performed similarly, both outperforming alfalfa. AMF inoculation significantly increased root density, lignin and cellulose contents, single-root tensile force(SRTF), hyphal density (HD), and glomalin-related soil protein (GRSP) contents, promoted macroaggregate formation, and enhanced RSCC. Alfalfa showed the strongest shallow-layer response to AMF inoculation, with the greatest increase in RSCC (52.8%) in the 0–10 cm layer, while the enhancement declined with depth. Caragana exhibited a more uniform vertical response, with AMF-induced cohesion increases of 30.0–35.7% across soil layers. Mixed planting displayed a complementary depth-dependent pattern by integrating shallow and deep rooting traits, resulting in the largest cohesion increase in the 20–30 cm layer (52.4%). Structural equation modeling (SEM) revealed three synergistic pathways through which AMF enhanced root-soil composite mechanical properties: (i) root architecture optimization, (ii) lignocellulose-mediated root reinforcement, and (iii) hyphae–GRSP-driven soil structural improvement. These findings indicate that AMF-driven stabilization results from coordinated regulation of root architecture, root mechanical traits, and soil structural properties. Integrating AMF inoculation with mixed vegetation restoration may provide an effective strategy for improving soil stability and ecological restoration in arid and semi-arid mining subsidence areas.

In order to alleviate the problems of restoration success rate and ecosystem resilience under the condition of water shortage in the dump area in western China,the Zhunneng Heidaigou open-pit mine was selected as the study area,and different soil layer reconstruc-tion methods(three-layer structure and mixed structure)were used in the dump site,and different microbial combinations(AM,DSE,AM+DSE,CK)were combined for ecological reconstruction to study the water retention,water culvertability,and spatial distribution of water and salt in the reconstructed soil layer.Effects of microorganisms on plant growth and water use strategies.The results show that the ground penetrating radar verifies the physical characteristics of the three-layer structure and the mixed structure,the soil moisture of the three-layer structure is distributed in layers,the surface loess layer(ecological layer)increases with depth,the middle coarse sandstone lay-er(culvert layer)has a balanced water distribution and the moisture content reaches 12％,the bottom sandy clay layer(aquifer)has the function of blocking water infiltration,and there is no spatial difference in the water distribution of the mixed structure.The water reten-tion capacity of the three-layer structure treatment increased by 43.1％,and significantly increased the water absorption of 50-100 cm soil layer,thereby promoting the water utilization of plant roots,and the utilization efficiency reached 71.1％.Compared with CK,the water use efficiency of alfalfa was increased by 42.7％and the coverage was increased by 1.2 times.Therefore,the combination of three-layer structure and AM+DSE treatment has significant ecological restoration potential in the arid and semi-arid mining areas in western China,and this study provides new ideas and technical support for the ecological restoration of mining areas,which is conducive to the sustain-able development of mining areas in western China.

Ecological restoration in arid coal mining regions of western China faces challenges from severe water scarcity and high soil salinity. This study investigates the combined effects of soil layer reconstruction and microbial remediation on soil water retention and salinity management to promote plant growth. Using an indoor, simulated soil column test, we employed a model with ecological, culvert, and waterproof layers, introducing interlayers of 0, 4, 7, and 10 cm thickness between the culvert and ecological layers. The ecological layer serves as the root zone for plant growth, the culvert layer stores irrigation water and precipitation, and the aquiclude prevents water loss. We tested three conditions for each interlayer thickness: bare soil (CK), alfalfa (Medicago sativa L.) growth (AL), and alfalfa with arbuscular mycorrhizal fungi (AMF). Results showed that interlayer thickness significantly (p < 0.05) influenced soil water and salt distribution. The soil water content in the ecological layer decreased by 12% and 16% under the 7 and 10 cm treatments but increased by 4% with a 4 cm interlayer. Surface soil salt accumulation was reduced by 40% with interlayer treatments. AMF inoculation enhanced alfalfa root development, increasing underground biomass by 2.1 times and boosting water content by 10.5% and salt content by 15.8% in the absence of an interlayer. The AMF + 4 and 7 cm interlayer treatments reduced surface soil salinity by 47% and 41%, respectively, and increased water use efficiency by 42% and 56%, respectively, with aboveground biomass increasing by 96% and 70%. These findings provide strategies for water conservation and salt control in the ecological restoration of mining dumps in arid regions.

Revealing the spatial distribution mechanism of the coupling effect between soil water and salt is essential for managing saline-alkali farmland. This study utilized the multifractal method to analyze soil water and salt under varying water content levels in arid saline-alkali farmland. Soil samples were collected on the second (S1), fifth (S2), eighth (S3), eleventh (S4), and fourteenth (S5) days after a rainfall event. The findings showed that a significant decrease in soil water content, contrasting with an increase in soil salt content throughout the soil layers post-rainfall. As water content decreased, the spatial variability of soil water initially increased from S1-3 and then decreased, while the spatial variability of soil salt decreased. The spatial distribution between soil water and salt exhibited a high correlation at S3-4 (with relative water content of soil ranging from 0.52 to 0.75) due to their coupling effect. However, soil salt was unevenly leached by rainfall at high water content levels (S1-2) and precipitated at low water content levels (S5), resulting in low spatial variability correlations between soil water and salt. This study elucidated the coupling process of soil water and salt, identifying their spatiotemporal distribution mechanism in dryland agricultural areas.

Coal mining in arid and semi-arid areas has led to the emergence of large areas of coal mining subsiding areas.The ecological reclamation of mining areas is hard,and the mycorrhizal microbial technology for ecological restoration has become a current research hot-spot.To investigate the effects of arbuscular mycorrhizal fungi(AMF)inoculation on the root distribution characteristics and water use ef-ficiency(WUE)of Amorpha fruticosa L.Three experimental treatments were set up:control without planting A fruticosa L seedlings(CK1),planting A fruticosa L seedlings(CK),planting A fruticosa L seedlings and inoculated with AMF(+AM).The plant growth indicat-ors and soil moisture were measured,and the results showed that:① AMF inoculation effectively promoted the growth of A fruticosa L.Compared with CK treatment,the plant height,SPAD value,aboveground biomass and aboveground biomass increased by 38.5％,27.5％,11.1％and 69.4％,respectively;② Inoculation changed the root distribution of A fruticosa L and increased the total root length and the number of root tips by 329.0％and 586.1％,respectively.Besides,reduced the average root diameter by 22.9％,and increased the propor-tion of fine roots below 2 mm by 370.1％.At the same time,inoculation affected soil water distribution and water use pattern of A fru-ticosa L.Compared with CK treatment,the soil water content of 0-20 cm increased by 8.9％and 7.8％,and the soil water content of 20-50 cm decreased by 16.8％,4.0％and 11.6％,respectively.The water use ratio of A fruticosa L to soil below 5 cm was increased by 15.4％and 9.9％at 5-30 cm and 30-50 cm,respectively;③ Inoculation increased the WUE of A fruticosa L by 27.5％.The results of principal com-ponent analysis showed that fine root length(0.5-1.00 mm)and root tip number in the roots of A fruticosa L were the key root character-istics for the efficient use of soil water by AMF inoculation under drought stress.In conclusion,inoculation with mycorrhizal fungi can significantly promote the growth of A fruticosa L seedlings,promote the absorption and redistribution ability of soil water through the sig-nificant improvement of the fine root characteristic parameters of A fruticosa L,and then make A fruticosa L plants show a high WUE.The results of this study can provide a scientific guidance and technical support for the biological combined remediation technology in the western coal mining settlement area.

Investigating the spatial distribution characteristics of the interaction between soil salinity and moisture is crucial in revealing moisture–salinity interaction in semi-arid farmland. The sampling of soil was performed on the second (S1), fifth (S2), eighth (S3), eleventh (S4), and fourteenth (S5) days after the erosive rainfall. The multifractal method was used to analyze spatial distribution parameters of soil moisture and salinity under the different stages. The findings showed that the soil moisture content decreased from 22.44% to 12.73%, while the salinity increased from 0.71 to 1.18 g kg–1 after the rainfall. As the amount of moisture in the soil decreased, the variability in the distribution of moisture initially increased from S1 to S3 and then decreased, while the salinity content also decreased. The spatial distribution of soil moisture and salinity content showed a strong correlation at S3 to S4 (with the relative water content of soil ranging from 0.52 to 0.75), indicating a significant coupling effect in these stages. However, the distribution of soil salinity was not uniform under high moisture content conditions (S1 to S2), as it was leached unevenly by rainfall, and under low moisture content conditions (S5), it precipitated, resulting in a low correlation between the spatial distribution of soil moisture and salinity content. This research has provided insight into the coupling dynamics of soil moisture and salinity content, revealing the mechanisms governing their spatial distribution in dryland agricultural regions.

[Objective]To explore the water use characteristics of typical plants under different ecological measures at the waste dump,improve plant water use efficiency,and accelerate the ecological restoration process in mining areas.[Methods]Six ecological measures(control,inoculation,green fertilizer,inoculation+green fertilizer,inoculation+weathered coal,inoculation+green fertilizer+weathered coal)were implemented at the waste dump of the Heidaigou Coal Mine to treat Amorpha fruticosa.Stable isotopes of hydrogen and oxygen in water were combined with other techniques.[Results](1)The soil moisture content of the waste dump was 3％to 9％,which was lower in the 0-30 cm and 70-100 cm soil layers,and higher in 30-70 cm soil layer.(2)Amorpha fruticosa obtained water from precipitation and soil.The soil water undergoes significant fractionation processed in the 0-30 cm soil layer,and exhibited significant differences among different ecological measures,with the green fertilizer treatment showing the highest and inoculation+green fertilizer treatment being the lowest.(3)Significant differences existed in the water use characteristics of Amorpha fruticosa under various ecological measures.The inoculation treatment exhibited a higher water use ratio of 53.4％in the 50-100 cm soil layer;The green fertilizer treatment mainly utilized the soil water in the surface layer(0-20 cm),which was 42.6％;The treatment of inoculation and green fertilizer had a relatively uniform proportion of soil water use in each layer.[Conclusion]The inoculation+green fertilizer treatment optimized the water use characteristics of Amorpha fruticose plants,increased the utilization ratio of surface and deep soil water,and can be used as an ecological reclamation measure for waste disposal sites,which promoted the ecological recovery rate and effect of arid mining areas in the western region.

干旱半干旱区煤矿露天开采破坏了地表形态,加速水土流失,水资源的缺失严重影响了露天矿排土场植被恢复的效果.土层重构与微生物修复技术为解决露天矿排土场植被缺水困境指明了方向,但目前对土层重构下植物根系形态特征与土壤水分利用的关系以及深色有隔内生真菌(DSE)在其中起到的重要作用缺乏足够的认识,因此,本研究旨在探究土层重构模式下玉米根系生长和水分利用情况以及DSE的作用机制.研究对象为玉米,在温室进行为期4个月的土层重构室内模拟试验.试验布设3组处理,分别为空白对照(N-CK)、土层重构不接种DSE(L-CK)、土层重构且接种DSE(L-DSE).试验结果表明:①与纯砂土处理相比,土层重构处理的玉米根系总根长度降低了 39.7％,根系中小于0.3 mm细根的比例提高了 8.86％,深层(50～70 cm)土壤水分的利用率提高了 16.1％.②与土层重构不接种DSE处理相比,接种DSE玉米的叶片脯氨酸含量提高了 69.8％,30～50cm 土层根系根尖数、比根长分别提高了 106.6％、38.5％,且深层水分的利用效率相较于纯砂土处理及土层重构不接种DSE处理分别增加了 29.3％、11.1％.③玉米根系的根尖数与比根长是土层重构模式下实现对深层土壤水分高效利用的关键根系特征.综合研究表明,土层重构有助于优化玉米根系结构,提高细根所占比例及根尖数目,改善缺水环境下玉米的水分利用模式,且土层重构模式下接种DSE可以通过提高玉米叶片脯氨酸含量,优化玉米根系结构等途径提高对深层土壤水分的利用率,进而提高作物的长期抗旱能力.

The distribution of soil water and salt severely affects the ecological reconstruction and plant configuration modes at coal mine dumps.To investigate the characteristics of soil water and salt distribution under the three-layer reconstruction mode of “topsoil-aquifer-aquitard” in coal mine dump under the influence of mycorrhizal plants,laboratory soil column test was conducted,in which the soil was treated in three ways:planting maize and inoculating with arbuscular mycorrhizal fungi（YM+AMF）,planting maize（YM） only,and no planting of maize + no inoculation with bacteria（CK）.The results showed that:（1） The different treatments have no significant effect on the water migration characteristics at the bottom of the soil column,and the rise height of capillary water in the aquifer is about 10 cm in all treatments.（2） The distribution of water and salt is positively correlated with soil depth.AMF inoculation is beneficial to maintain the water content of soil in the surface layer,which was increased by 52.0% and 43.9% respectively compared with YM treatment at 0-10 cm and 10-20 cm.The salt content of soil at 10-50 cm is reduced by inoculation,and the electrical conductivity of soil at 20-30 cm,30-40 cm and 40-50 cm is 41.0%,14.1% and 8.1% lower than that of YM treatment,respectively.（3） The contribution rate of soil moisture at different depths to maize was quantified with the MIXSIAR model.The results indicate that the main water supply layer is located at 0-10 cm for YM and YM+AMF treatments,of which the water supply rate is 44.3% and 30.5%,respectively.Besides,bacterial inoculation significantly increases the water contribution rate of the middle and deep soil profile（20-70 cm）,with a cumulative increase of 13.8%.The research results have important scientific guiding significance for the ecological reclamation of “planting with water” in the western mining area.

[Objective]Part of the newly cultivated farmland formed by the"Gully Control and Land Reclamation"project is facing the risk of soil salinization in the loess hilly region.The spatial distribution characteristics of soil water and salt and their influencing factors were studied for preventing and controlling soil salinization,and promoting sustainable utilization of newly cultivated land.[Methods]A typical area of newly cultivated land was selected,and six experimental plots were established along a gully head to the gully mouth,with sampling points numbered sequentially from 1 to 6.The grid method was used to obtain soil samples from the 0-20 and 20-40 cm layers in each plot.The multifractal method was used to analyze the spatial distribution characteristics of soil water and salt.[Results]Soil water content and salt content gradually decreased from the gully head to the gully mouth.The mean soil water contents and salt contents at sampling points 1,2,and 3 were 17.6％ and 0.81 g/kg,respectively,which were 23.0％ and 14.1％ higher than the respective values at sampling points 4,5,and 6.Meanwhile,the multifractal parameters D1 of soil water and salt at sampling points 1,2,and 3 were less than the respective values at sampling points 4,5,and 6.ΔD values showed the opposite result,indicating that the spatial variability of soil water and salt at sampling points 1,2,and 3 were higher.The depth of groundwater influence was the main reason for increased accumulation of salt in the surface soil at sampling points 1,2,and 3(p＜0.05).The terrain characteristic was also an important reason(p＜0.05).The narrow terrain was not conducive to drainage,was prone to waterlogging,and exhibited exacerbated salt accumulation.In addition,sampling points 1,2,and 3 may be invaded by slope runoff and sediment with high salt content that increased soil water,salt content,and variability in the area.[Conclusion]The depth of groundwater influence,terrain characteristics,and slope runoff sediment were important reasons for the high soil water content,salt content,and their spatial variability at sampling points 1,2,and 3 in newly cultivated farmland.Thus,newly cultivated farmland near the gully head location would be a key area for preventing soil salinization in the future.

Coal mining has formed open-pit dumps and underground subsidence areas, changing the original landform and ecology. The instability of the open-pit dump slope is easy to cause soil erosion, which causes the landslide to shear the vegetation root system. The underground subsidence causes the ground fissure to develop and damage the plant root system. Therefore, one of the keys to mine ecological restoration is to enhance the shear resistance and strain resistance of plant roots. Microbial reclamation has the functions of improving soil physical and chemical properties, promoting plant root development and stress resistance. The effect of inoculation on the shear and tensile resistance of root-soil complex is have laid a good foundation for revealing the mechanism of mine ecological restoration. After artificial restoration, plant roots and soil to form a root-soil complex, which can greatly increase the shear strength of the soil, enhance the stability of the shallow soil, effectively reduce the soil and water loss of the slope of the open-pit dump and relieve the root starin. Arbuscular mycorrhizal fungi（AMF） or dark septate endophytic fungi（DSE） are ubiquitous in the rhizosphere, and their mycorrhizal symbionts formed with roots are bonded to the rhizosphere soil to form a root-soil complex. There are few studies on the mechanism and influencing factors of shear resistance. Therefore, the influencing factors, mechanism of action and ecological restoration potential of root-soil complex inoculated with microorganisms in mining areas are reviewed in this artical. At the same time, combined with the analysis of experimental data, it is concluded that the underground biomass, soil cohesion and shear strength of root-soil composite soil inoculated with AMF and DSE are significantly improved. Microbial reclamation technology not only improves the survival rate and stress resistance of artificial restoration vegetation.

It is important to study the mechanisms associated with the spatial distribution of soil water and salt to control soil salinization and promote the sustainable development of farmland. Six plots in a slight farmland with different spatial locations were selected to determine the spatial distribution of soil water and salt and their correlation using the multifractal method. Each plot was applied using the grid method (15 m × 15 m, 3600 m2), where each sampling site was located at the center point coordinates. The 0–20 and 20–40 cm soil layers were sampled.The spatial variability of the soil water and salt were 1.41 and 1.73 fold higher in the upstream farmland than in the downstream farmland. The spatial variability of the soil water and salt was significantly correlated. In addition, the spatial variability of the soil water and salt significantly correlated in the 0–20 and 20–40 cm layers. The spatial distribution of both soil water and salt in the entire soil layer had similar characteristics at this sampling scale. Our results provide a theoretical basis to study the interactive mechanisms associated with the distribution of soil water and salt.

Water resources determine the vegetation structure and types in the ecological restoration process, and are the main limiting factor for achieving green production and ecological restoration in mining areas. To investigate the effects of inoculation of Arbuscular Mycorrhiza Fungi (AMF) on plant root water extraction, simulated soil water distribution and water isotope fractionation in a semi-arid coal mining area, this study conducted the indoor stratified soil column simulation experiment with maize as the test plant. Three treatments were set up as pure soil column (CK1), soil column + maize (CK2), and soil column + inoculated maize (AMF), with three replicates for each treatment. Meanwhile, the height of capillary water rise in soil columns, soil water content, as well as hydrogen and oxygen isotopes of maize stem water and soil water were measured. The growth and development of maize, water transport patterns, and discrepancies in soil water isotope fractionation at different depths among different treatments were also analyzed in this article. Results showed that: (1) Inoculation could effectively promote the growth and development of maize, with plant height, aboveground biomass, underground biomass and total root length increased by 15.8%, 23.4%, 43.4% and 21.0%, respectively, compared to CK2 treatment. (2) AMF have also promoted the root system to absorb the retain water in the bottom clay layer, increased the capillary water elevation by 18.9%, and expanded the water absorption space of maize by approximately 50%, thereby affecting the water distribution in the soil columns. (3) There were significant fractionation differences between the surface and deep soil water of soil column compared to the initial water. At the surface layer of 0 ~ 10 cm, the 18O and 2H enrichment coefficients of CK2 and AMF treatments were significantly lower than those of CK1 treatment, while at the deep layer of 60 ~ 70 cm, the 18O and 2H enrichment coefficients of AMF treatment were significantly higher than those of CK2 treatment, indicating that AMF could enhance the phenomenon of isotopic fractionation in deep subsoil water. In summary, inoculation can improve the absorption of deep soil water by maize in the reconstructed soil layer, prompt the root system to counter-release to the upper dry soil through the water lifting effect, improve the water redistribution capacity, and affect the soil water isotope fractionation at different depths. The results could provide scientific basis and technical support for addressing the shortage of water resources for land reclamation in semi-arid coal mining areas.

微生物复垦技术在西部干旱-半干旱煤矿区生态修复中已被广泛应用,便捷的微生物菌剂施用方式对于提高采煤沉陷地生态治理效率具有重要意义.试验以蛋白桑为研究对象,供试菌剂为深色有隔内生真菌(dark septate endophyte,DSE),采用温室盆栽试验,设置DSE菌液根际接种(GXZR)、DSE菌液叶片涂抹(YMTM)和对照蛋白桑(CK)3个处理,探究不同菌液接种方式对蛋白桑生长发育影响及其生态修复前景.结果表明,与CK相比,YMTM与GXZR处理均能显著提高蛋白桑地上生物量,增加幅度为 1.9～3.3倍;同时YMTM与GXZR处理促进了蛋白桑对土壤C、N、P的吸收,全碳分别提升164.8%和121.8%、全氮分别提升177.7%和132.4%、全磷分别提升113.6%和28.7%.此外,YMTM与GXZR处理蛋白桑的相对饲用价值显著提升 1.04和 1.07倍.这些结果表明,DSE叶面涂抹促进蛋白桑对土壤C、N的吸收,使蛋白桑株高、冠幅、根茎叶生物量也得到显著提升,具有较强的碳汇作用.此外,DSE菌液叶面涂抹能够使DSE快速定殖于蛋白桑叶片,具有养分吸收快、利用率高、见效快的特点.因此,DSE叶面涂抹可作为一种新的微生物菌肥施用方式在矿区生态修复中应用,为煤矿区土地复垦与生态修复提供技术支撑.

Water shortage and soil salinization in gully farmland comprising sediment deposited farmland (SF) and excavated farmland (EF) have become a widespread concern in the loess hilly region. A two-year field experiment was conducted to assess the soil water content (SWC) and salt content (SSC) and their effect on the spring maize yield and water use efficiency in SF and EF. Eight treatments comprising flat cropping without mulching (1), ridge planting without mulching (2), ridge planting with plastic mulching (3), and ridge planting with straw mulching (4) were tested in the SF and EF plots, respectively. The results showed that the yield was higher in SF than EF, whereas the water use efficiency was significantly higher in EF because the bottom water flux was 117.4% higher in SF than EF (P < 0.01). A significant positive correlation was found between the average SWC and yield (P < 0.01), thereby indicating that the yield was severely limited by the SWC. Thus, the higher water use efficiency in EF has important implications for alleviating water scarcity during agricultural production in this region. The risk of soil salinization was decreased greatly by treatment 3 where the SSC was decreased in EF and SF were 0.09 g kg–1 and 0.08 g kg–1, respectively. In addition, treatment 3 had the most significant impacts on the yield and water use efficiency. Our study provided appropriate land type and effective tillage measure for the sustainable development in dryland agricultural areas.

Soil salinization and water deficits in gully consolidation farmland including excavated farmland (EF) and sediment deposited farmland (SF) have become an increasing concern in the Loess Hilly region, China. However, the responses of different farmland types and tillage‐mulching practices on soil salt content (SSC) and water use efficiency (WUE) have not been widely studied in this region. Thus, we conducted a two‐year field experiment to assess the soil water content (SWC) and SSC and their effect on the spring maize yield and WUE under different tillage‐mulching practices in EF and SF. Eight treatments incorporating flat cropping without mulching (FC), ridge planting without mulching (RP), ridge cropping with straw mulching (SM), and ridge cropping with plastic mulching (PM) were applied to EF and SF plots, respectively. Our results indicated that the yield of spring maize was limited by SWC (p < 0.01). Although EF had a low yield of spring maize compared to SF, it had the highest WUE (p < 0.01), which was mainly due to the lower groundwater consumption. Meanwhile, the average SSC was significantly lower in EF than in SF (p < 0.01). PM had the highest SWC (14.9%) and significantly reduced the accumulation of SSC (−0.09 g kg−1), thereby improving spring maize yield (12,200 kg ha−1) and WUE (1.71 kg m−3) (p < 0.05). These results suggested that EF with PM is optimal for groundwater conservation, decreasing the risk of soil salinization, and improving WUE and maize yield in dryland agricultural areas.

Soil physical properties (SPP) are considered to be important indices that reflect soil structure, hydrological conditions and soil quality. It is of substantial interest to study the spatial distribution of SPP owing to the high spatial variability caused by land consolidation under various land restoration modes in excavated farmland in the loess hilly area of China. In our study, three land restoration modes were selected including natural restoration land (NR), alfalfa land (AL) and maize land (ML). Soil texture composition, including the contents of clay, silt and sand, field capacity (FC), saturated conductivity (Ks) and bulk density (BD) were determined using a multifractal analysis. SPP were found to possess variable characteristics, although land consolidation destroyed the soil structure and decreased the spatial autocorrelation. Furthermore, SPP varied with land restoration and could be illustrated by the multifractal parameters of D1, ΔD, Δa and Δf in different modes of land restoration. Owing to multiple compaction from large machinery in the surface soil, soil particles were fine-grained and increased the spatial variability in soil texture composition under all the land restoration modes. Plough numbers and vegetative root characteristics had the most significant impacts on the improvement in SPP, which resulted in the best spatial distribution characteristics of SPP found in ML compared with those in AL and NR. In addition, compared with ML, Δa values of NR and AL were 4.9- and 3.0-fold that of FC, respectively, and Δa values of NR and AL were 2.3- and 1.5-fold higher than those of Ks, respectively. These results indicate that SPP can be rapidly improved by increasing plough numbers and planting vegetation types after land consolidation. Thus, we conclude that ML is an optimal land restoration mode that results in favorable conditions to rapidly improve SPP.

露天煤矿排土场土层重构对于生态重建具有重要意义,为研究接种深色有隔内生真菌(darkseptate endophytes,DSE)对不同重构土层模式下玉米根系水分的利用效应,采用土柱模拟培养试验,设置4种类型土层处理,每种土层类型下设置接菌及对照处理,共8组处理.结果表明:掺黄土20％处理下玉米根长密度最大,分别为掺黄土0％、10％和40％的3.2、2.4、2.8倍,水分胁迫后根系具有向下生长、吸取深层水分的能力;基于δ18O值的MixSIAR模型水源分析,掺黄土0％处理下玉米主要利用0～25 cm处的水分,水分利用效率达到80％;掺黄土10％处理下玉米主要利用15～35 cm处的水分,水分利用效率达到64％;而掺黄土20％处理下玉米对0～25 cm处的水分利用效率仅为36％,对25～45 cm处水分利用率达到64％,说明掺黄土20％处理下玉米主要利用土壤深层水分.接种DSE提高了植物吸收更深层水的能力,掺黄土20％处理下水分利用深度向下增加了5 cm,掺黄土20％基质中接菌处理在干旱胁迫后植物根系提水量达到最大,生长期总提水量较不接菌处理提升了45％;在不接菌条件下掺黄土20％植物根系提水量是掺黄土0％的1.45倍,而在接菌条件下掺黄土20％植物根系提水量可达到掺黄土0％的1.72倍.综上认为,接种DSE及土层重构均对提升植物提水能力具有显著作用.此外,本研究结果对露天矿区排土场土层重构过程中土壤改良及植物的水分利用效率提供实验参考依据.

Net primary productivity (NPP) of grassland is a key link and important part of the ecosystem's carbon cycle. We estimated the changes of NPP in grasslands of the Loess Plateau with unchanged land use types during 2000-2015 and analyzed its responses to the variation of main climate factors (annual precipitation, annual heavy rainfall, annual effective rainfall days, annual average temperature, annual maximum temperature, annual minimum temperature) using piecewise linear regression and Pearson correlation analysis. The driving factors of grassland NPP were further analyzed by pixel-by-pixel with boosted regression tree analysis. The results showed that annual mean grassland NPP in the Loess Plateau showed an increasing trend during the study period, with 51.3% of the total grassland area showing a significant increasing trend. The average increase rate of annual mean NPP declined from 15.23 g C·m-2·a-1 in 2000-2004 to 3.58 g C·m-2·a-1 in 2004-2015. There was a significant positive correlation between grassland NPP and precipitation, but negative correlation with temperature factors. Annual precipitation was the dominant climatic factor affecting NPP of the whole study area with the highest relative importance. Annual maximum temperature was the dominant driving force of grassland NPP of central Loess Plateau, while annual minimum temperature mainly affected the growth of grassland in high-altitude area of the western Loess Plateau.

Soil salinization is widespread and it hinders agricultural development in the loess hilly region of China. In this study, we determined the dynamic distribution of the soil salinity (SS) as well as its effects on maize (Zea mays L.) after rainstorm events in two land types produced by excavation and sediment deposition. Four treatments were tested comprising sediment deposited farmland without plastic mulch (S1) and with plastic mulch (S2), and excavated farmland without plastic mulch (E1) and with plastic mulch (E2). The results showed that the dynamic distribution of the SS exhibited similar characteristics included leaching, rapid accumulation, and relatively stability in the 0-40 cm soil layer after rainstorm events. A turning point where the leaching and accumulation of SS reached a balance in the 0-40 cm layer occurred on about the 4th day under the no plastic mulch treatments and on the 6th day under the plastic mulch treatments. The SS reached a relatively stable condition in the whole soil layer on the 12th day. Rainstorm events increased the accumulated SS by 0.36, 0.08, 0.44, and 0.20 g kg-1 under E1, E2, S1, and S2, respectively, during the year. Plastic mulch treatments decreased the average accumulated SS by 66.7% and the average SS by 22% by reducing water infiltration and soil evaporation. The average SS and accumulated SS in sediment deposited farmland were 8.9% and 47.6% higher, respectively, than those in excavated farmland because of the lower depth of the groundwater influence zone and more abundant capillary pores in the sediment deposited farmland. The average SS in the whole soil layer followed the order of: S1 (0.72 g kg-1) E1 (0.62 g kg-1) > E2 (0.53 g kg-1) > S2 (0.52 g kg-1) (P < 0.05), and these levels did not limit maize growth. However, the two land types without plastic mulch would be transformed into severe saline-alkali land after 10 years. Therefore, we conclude that E2 is the optimal treatment for this region because it resulted in the lowest accumulated SS. Our results are important for understanding the SS dynamics and controlling soil salinization after rainstorm events.