Mountainous areas are the priority for forest restoration in semiarid regions,with hillslopes serving as the basic units of mountains.Precipitation is the only water source in these regions,and the uneven distribution...Mountainous areas are the priority for forest restoration in semiarid regions,with hillslopes serving as the basic units of mountains.Precipitation is the only water source in these regions,and the uneven distribution of hillslope soil moisture replenishment after precipitation determines vegetation survival and growth.Therefore,in this study experiments were performed on a hillslope in the Liupan Mountains,Ningxia Hui Autonomous Region,China,to quantify the unevenness of soil moisture replenishment.Soil water content(SWC)in the 0–60 cm layer and precipitation were monitored throughout the growing season in 2020 and 2021.The results showed that(1)Annual soil moisture replenishment was the highest at the mid-slope position,with an average of 309.9 mm,especially under moderate and heavy rain grade conditions,reaching 38.7% and 30.8% of the total replenishment,respectively;(2)Vertical replenishment played a dominant role in the total replenishment,accounting for 82.8%;lateral replenishment played an important but lesser role,accounting for up to 17.2% of the total replenishment;(3)Based on a soil moisture replenishment model established in this study,the maximal replenishment occurred at 90 m from the top of the slope;(4)The dominant factors contributing to the soil moisture replenishment were rainfall amount and saturated hydraulic conductivity(Ks).These findings suggest that attention should be given to both vertical and lateral soil moisture replenishment,and the mid-slope position could be preferred for site selection to achieve precise and integrated forest-water management on hillslopes in semi-arid mountainous regions.展开更多
Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influenci...Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.展开更多
Soil desiccation cracking is a common phenomenon on the earth surface.Numerical modeling is an effective approach to study the desiccation cracking mechanism of soil.This work develops a novel 3D moisture diffusion di...Soil desiccation cracking is a common phenomenon on the earth surface.Numerical modeling is an effective approach to study the desiccation cracking mechanism of soil.This work develops a novel 3D moisture diffusion discrete model that is capable of dynamically assessing the effect of cracking on moisture diffusion and allowing moisture to be discontinuous on both sides of the cracks.Then,the parametric analysis of the moisture exchange coefficient in the 3D moisture diffusion discrete model is carried out for moisture diffusion in continuous media,and the selection criterion of the moisture exchange coefficient for the unbroken cohesive element is given.Subsequently,an example of moisture migration in a medium with one crack is provided to illustrate the crack hindering effect on moisture migration.Finally,combining the 3D moisture diffusion discrete model with the finite-discrete element method(FDEM),the moisture diffusion-fracture coupling model is built to study the desiccation cracking in a strip soil and the crack pattern of a rectangular soil.The evolution of crack area and volume with moisture content is quantitatively analyzed.The modeling number and average width of cracks in the strip soil show a good consistency with the experimental results,and the crack pattern of the rectangular soil matches well with the existing numerical results,validating the coupled moisture diffusion-fracture model.Additionally,the parametric study of soil desiccation cracking is performed.The developed model offers a powerful tool for exploring soil desiccation cracking.展开更多
This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked asphalt.Thermodynamic parameters,morphological characteristics,interfacial healing energy,and...This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked asphalt.Thermodynamic parameters,morphological characteristics,interfacial healing energy,and interfacial healing strength were analyzed using molecular dynamics and macroscopic tests under different time,temperature,and water conditions to evaluate the specific states and critical conditions involved in self-healing.The results indicate that basalt-fiber molecules can induce rearrangement and a combination of water-soaked asphalt at the healing interface.Hydroxyl groups with different bonding states increase the interfacial adsorption capacity of water-soaked asphalt.The interaction between basalt fiber molecules and water molecules leads to a"hoop"phenomenon,while aromatics-2 molecules exhibit a"ring band aggregation"phenomenon.The former reduces the miscibility of water and asphalt molecules,while the latter causes slow diffusion of the components.Furthermore,a micro-macro dual-scale comparison of interfacial healing strength was conducted at temperatures of 297.15 and 312.15 K to identify the strength transition point and critical temperature of 299.4 K during the self-healing process of basalt-fiber modified water-soaked asphalt.展开更多
During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the s...During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis results.To elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget analysis.The findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern Pacific.This increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective instability.Such a process is pivotal in amplifying intraseasonal convection anomalies.The observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns.展开更多
Objectives This study investigated the effects of curdlan on the physical and sensory properties of pineapple jam,addressing the limitations of pectin such as high cost and low gelling efficiency in pineapple-based fo...Objectives This study investigated the effects of curdlan on the physical and sensory properties of pineapple jam,addressing the limitations of pectin such as high cost and low gelling efficiency in pineapple-based formulations.Materials and Methods Pineapple jams were prepared with three concentrations of curdlan(0.5%,1%,and 1.5%).The samples were assessed for cooking time,syneresis,water activity,pH,moisture content,colour,texture,microstructure,and sensory acceptability.Results Incorporating curdlan into pineapple jam shortened the cooking time,with 1.5%curdlan reducing it from 3 to 1 h.Curdlan also decreased syneresis and water activity while increasing the moisture content,pH,and colour attributes(lightness,redness,and yellowness)of the jam.Texture analysis revealed increased hardness and reduced adhesiveness with increasing curdlan concentration.Microstructural observations indicated more heterogeneous structures and greater particle aggregation as curdlan concentration increased.Sensory evaluations showed no significant differences in colour,taste,or overall acceptability,though the formulation containing 0.5%curdlan demonstrated superior spreadability.Conclusion Curdlan effectively improved the physical and functional properties of pineapple jam and reduced cooking time,suggesting its potential as a functional,cost-effective gelling agent.Further studies are needed to assess its scalability,shelf-life,and industrial feasibility.展开更多
Moisture-enabled electricity generation(MEG)has emerged as a promising sustainable energy harvesting technology,comparable to photovoltaics,thermoelectrics,and triboelectrics[1].MEGs generate electricity by converting...Moisture-enabled electricity generation(MEG)has emerged as a promising sustainable energy harvesting technology,comparable to photovoltaics,thermoelectrics,and triboelectrics[1].MEGs generate electricity by converting the chemical potential of moisture into electric energy through interactions with hygroscopic materials and nanostructured interfaces.Unlike solar or thermal harvesters,MEGs operate continuously by utilizing ubiquitous atmospheric moisture,granting them unique spatial and temporal adaptability.Despite nearly a decade of progress and the exploration of diverse material systems for MEG,the overall output power remains significantly limited due to inherently low charge carrier concentrations and restricted ion diffusion fluxes[2].As a result,standalone MEG devices often deliver low and unstable output,limiting practical applications.To enhance performance and versatility,recent efforts have explored hybridization of MEG with other ambient energy sources such as triboelectric or thermoelectric effects.展开更多
Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some common factors that usually cause damage to trees when they are struck by lightning?2.How might the un...Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some common factors that usually cause damage to trees when they are struck by lightning?2.How might the unique characteristics of a tree contribute to its ability to survive a lightning strike?展开更多
A common concern to planting for reforestation is seedling failure that is directly measurable by seedling early field performance of growth and survival.Root growth potential(RGP)is a commonly used metric of seedling...A common concern to planting for reforestation is seedling failure that is directly measurable by seedling early field performance of growth and survival.Root growth potential(RGP)is a commonly used metric of seedling quality and has been considered indicative of seedling field performance.The effect of RGP is thought to be dependent on planting site and underlining environmental conditions.Moisture stress often is considered the primary cause of seedling failure in addition to other environmental factors such as soil physicochemical properties in regions such as the Inland Northwest of the United States that is prone to growing season drought.In addition,it is interesting to test whether seedling early field performance is related to their morphological attributes and whether the morphological attributes are related to RGP.A comprehensive evaluation on early field performance of three planted conifer species of interior Douglas-fir(Pseudotsuga menziesii(Mirb.)Franco var.glauca(Beissn.)Franco),grand fir(Abies grandis(Douglas ex D.Don)Lindl.),and western larch(Larix occidentalis Nutt.)was conducted in this study.It was found that RGP did not show clear correlation with early field performance across species.RGP also was not significantly correlated with seedling morphological measures such as below-and above-ground biomass and root-to-shoot ratio(R:S,by mass).Early field performance of growth and survival varied greatly across individuals of seedlings.The most influential predictors of early seedling growth and survival were their initial size(indicative of energy reserve)and soil temperature that likely interacted with soil moisture.Our findings suggest that seed stock selection for reforestation probably should favor species and genotypes with greatest heat tolerance that may be better adapted to future conditions in the region.展开更多
In this study,we investigate the complex relationship between western disturbances(WDs),the El Ni?o–Southern Oscillation(ENSO),and extreme precipitation events(EPEs) in the western Himalaya(WH) during the extended wi...In this study,we investigate the complex relationship between western disturbances(WDs),the El Ni?o–Southern Oscillation(ENSO),and extreme precipitation events(EPEs) in the western Himalaya(WH) during the extended winter season(November–March).WDs west of WH coincide with 97% of recorded EPEs,contributing substantially(32% in winter,11% annually) to total precipitation within WH.WDs are 6% less frequent and 4% more intense during El Ni?o than La Ni?a to the west of WH.During El Ni?o(compared to La Ni?a) years,WDs co-occurring with EPEs are significantly more intense and associated with 17% higher moisture transport over “WH box”(the selected region where most of the winter precipitation over WH occurs).This results in twice the EPE frequency during El Ni?o periods than La Ni?a periods.A substantial southward shift(~180 km) of the subtropical jet(STJ) axis during El Ni?o brings WD tracks further south towards their primary moisture sources,especially the Arabian Sea.We have shown that WDs that are both more intense and pass to the south of their typical latitudes have higher levels of vertically integrated moisture flux(VIMF)within them.VIMF convergence in the most intense pentile of WDs is 5.7 times higher than in the weakest,and is 3.4 times higher in the second lowest latitude pentile than in the highest.Overall,this study demonstrates a direct link between changes in the latitudinal position and intensity of WDs associated with the winter STJ,and moisture convergence,which leads to the occurrence of EPEs over WH during ENSO phases.展开更多
The article examines the impact of increased aridization of the territory due to an increase in air temperature,reduced precipitation,and the formation of moisture deficiency on grain yields in Northern Kazakhstan.The...The article examines the impact of increased aridization of the territory due to an increase in air temperature,reduced precipitation,and the formation of moisture deficiency on grain yields in Northern Kazakhstan.The most important result of the work is the revealed inverse relationship between grain yields and the temperature of the growing season:low-yielding years are associated with high temperatures and droughts,and high-yielding years are associated with lower temperatures and an optimal ratio of heat and moisture.The novelty of this study is the use of the method of hydrological and climatic calculations in identifying the nature of temperature variability and precipitation in the territory of Northern Kazakhstan for the modern period(1991–2020)compared with the base period(1961–1990).At all the studied meteorological stations,there is a tendency for the average annual temperature and the temperature of the growing season to increase:in the forest-steppe zone with an average warming intensity of 0.3–0.33℃ per decade;in the steppe zone by 0.2–0.43℃ per decade;and in the growing season by 0.2–0.7℃ per decade.The air temperature in the steppe zone is rising more intensively than in the forest-steppe zone,and precipitation in the forest-steppe zone has changed more than in the steppe zone.An increase in the average annual air temperature during the growing season(May–August),combined with a shortage of atmospheric moisture or a constant amount of it,led to an increase in the degree of aridization of the territory,an increase in the frequency of droughts in the steppe zone of Northern Kazakhstan.展开更多
Heatwaves are becoming increasingly frequent and severe,posing escalating risks to ecosystems and human well-being.While soil moisture(SM)deficits are recognized as important contributors to heatwave amplification,the...Heatwaves are becoming increasingly frequent and severe,posing escalating risks to ecosystems and human well-being.While soil moisture(SM)deficits are recognized as important contributors to heatwave amplification,their spatially heterogeneous impacts across the Northern Hemisphere remain insufficiently understood.In this study,we analyze ERA5 reanalysis data(1980-2022)to investigate trends in heatwave frequency,intensity,and duration,as well as their sensitivity to SM variability.Our results show robust increases in heatwave occurrence(0.76 events per decade),intensity(0.81℃per decade),and average duration(0.40 days per decade),with extreme events,as represented by maximum intensity and duration,rising at even faster rates(2.18℃per decade and 0.83 days per decade,respectively).Strong negative correlations are observed between SM deficits and heatwave metrics,with the magnitude of this relationship varying across land cover types and heatwave severity levels.Quantile regression reveals that SM reductions have a greater impact at higher quantiles for most indicators.Cropland exhibits the highest sensitivity to SM anomalies,whereas forests show more resilience due to their superior water retention capacities.These findings underscore the crucial role of land-atmosphere interactions in shaping heatwave extremes,providing a scientific basis for enhancing early warning and adaptation strategies in the context of ongoing climate change.展开更多
Extensive flooding swept across large areas of Central Asia,mainly over Kazakhstan and southwestern Russia,from late March to April 2024.It was reported to be the worst flooding in the area in the past 70 years and ca...Extensive flooding swept across large areas of Central Asia,mainly over Kazakhstan and southwestern Russia,from late March to April 2024.It was reported to be the worst flooding in the area in the past 70 years and caused widespread devastation to society and infrastructure.However,the drivers of this record-breaking flood remain unexplored.Here,we show that the record-breaking floods were contributed by both long-term climate warming and interannual variability,with multiple climatic drivers at play across the synoptic to seasonal timescales.First,the heavy snowmelt in March 2024 was associated with above-normal preceding winter snow accumulation.Second,extreme rainfall was at a record-high during March 2024,in line with its increasing trend under climate warming.Third,the snowmelt and extreme rainfall in March were compounded by record-high soil moisture conditions in the preceding winter,which was a result of interannual variability and related to excessive winter rainfall over Central Asia.As climate warming continues,the interplay between the increasing trend of extreme rainfall,interannual variations in soil moisture pre-conditions,as well as shifting timing and magnitudes of spring snowmelt,will further increase and complicate spring flooding risks.This is a growing and widespread challenge for the mid-to high-latitude regions.展开更多
The primary mechanism driving plant species loss after nitrogen(N)addition has been often hypothesized to be asymmetric competition for light,resulting from increased aboveground biomass.However,it is largely unknown ...The primary mechanism driving plant species loss after nitrogen(N)addition has been often hypothesized to be asymmetric competition for light,resulting from increased aboveground biomass.However,it is largely unknown whether plants’access to soil water at different depths would affect their responses,fate,and community composition under nitrogen addition.In a semiarid grassland exposed to 8-years of N addition,we measured plant aboveground biomass and diversity under four nitrogen addition rates(0,4,10,and 16 g m2 year1),and evaluated plant use of water across the soil profile using oxygen isotope.Aboveground biomass increased significantly,but diversity and shallow soil-water content decreased,with increasing rate of nitrogen addition.The water isotopic signature for both plant and soil water at the high N rate indicated that Leymus secalinus(a perennial grass)absorbed 7%more water from the subsurface soil layer(20e100 cm)compared to Elymus dahuricus(a perennial grass)and Artemisia annua(an annual forb).L.secalinus thus had a significantly larger biomass and was more abundant than the other two species at the high N rate but did not differ significantly from the other two species under ambient and the low N rate.Species that could use water from deeper soil layers became dominant when water in the shallow layers was insufficient to meet the demands of increased aboveground plant biomass.Our study highlights the importance of water across soil depths as key driver of plant growth and dominance in grasslands under N addition.展开更多
Tafoni are globally developed on cliffy slopes,and many of them are favorable places for the preservation of stone historical relics.However,the characteristics and formation processes of tafoni in the Loess Plateau a...Tafoni are globally developed on cliffy slopes,and many of them are favorable places for the preservation of stone historical relics.However,the characteristics and formation processes of tafoni in the Loess Plateau are yet to be understood.This paper studied the features of the tafoni on conglomerate slopes in Huoshizhai National Geopark of Ningxia Hui Autonomous Region and discussed its formation processes by field investigation and morphometry,insitu relative humidity(RH)measurement,salt chemistry and X-ray fluorescence spectrometer(XRF)experiments of 24 samples.The bedrock of the tafoni is dominated by reddish fluvial conglomerates of the Lower Cretaceous Heshangpu Formation with abundant chemically unstable components including feldspars,lithic fragments,and calcite cements.The RH values vary from 5%to 100%,but the backwalls of the tafoni have higher RH values than outer surfaces.The more moisture on the backwalls is possibly generated by water influx from the rock interior,resulting in more salt precipitation on the backwalls.As a result,the backwalls have been subject to predominant salt weathering.The dominant salts involved in salt weathering are probably derived from the dissolution of the salt interbeds in the basin,although the chemical dissolution of the unstable components such as feldspars,lithic fragments,and calcite cements might have produced small amounts of salts.The salt types dominantly include nitrates,sulfates,and halite.In the progression of tafoni,the moisture maintenance on the backwalls gives rise to the accretion of salts,which in turn enhance the weathering rates of the backwalls.As a result,the volumes of the tafoni have become enlarged owing to inward growth and coalescence of adjacent smaller ones.展开更多
Moistube irrigation is a newly-developed irrigation technique that utilizes a semipermeable membrane to release water slowly and continuously into the plant root zone.Alternate Moistube Irrigation(AMI)is a combination...Moistube irrigation is a newly-developed irrigation technique that utilizes a semipermeable membrane to release water slowly and continuously into the plant root zone.Alternate Moistube Irrigation(AMI)is a combination of alternative irrigation and moistube irrigation.In order to investigate the effects of AMI on plant growth,greenhouse experiments were conducted on spinach(Spinacia oleracea)and water spinach(Ipomoea aquatica)plants at different time.We measured soil water content at a depth of 20 cm in the planting boxes,and also determined seed emergence rate,plant height,largest leaf area,fresh weight per plant,yield,and irrigation water productivity(IWP)for both spinach and water spinach.The results showed that the AMI treatments had significantly higher soil water content than the conventional surface irrigation control(CK).The emergence rates of spinach and water spinach were significantly higher in the AMI treatments than in the CK,and the plant height,largest leaf area,and fresh weight during the middle and late stages of spinach and water spinach growth were also significantly higher than those of the CK.Both spinach and water spinach grew well and produced high yield with high IWP under AMI with a high water head pressure of 1.5 m at tube spacing of 20 or 30 cm.We found that AMI with a suitable combination of head pressure and tube spacing can promote plant growth and increase yield and IWP under controlled conditions.展开更多
The rate of fire spread is a key indicator for assessing forest fire risk and developing fire management plans.The Rothermel model is the most widely used fire spread model,established through laboratory experiments o...The rate of fire spread is a key indicator for assessing forest fire risk and developing fire management plans.The Rothermel model is the most widely used fire spread model,established through laboratory experiments on homogeneous fuels but has not been validated for conifer-deciduous mixed fuel.In this study,Pinus koraiensis and Quercus mongolica litter was used in a laboratory burning experiment to simulate surface fire spread in the field.The effects of fuel moisture content,mixed fuel ratio and slope on spread rate were analyzed.The optimum packing ratio,moisture-damping coefficient and slope parameters in the Rothermel model were modified using the measured spread rate which was positively correlated with slope and negatively with fuel moisture content.As the Q.mongolica load increased,the spread rate increased and was highest at a fuel ratio of 4:6.The model with modified optimal packing ratio and slope parameters has a significantly lower spread rate prediction error than the unmodified model.The spread rate prediction accuracy was significantly improved after modifying the model parameters based on spread rates from laboratory burning simulations.展开更多
This study aimed to explore the relationship between Soil-Plant Analysis Development(SPAD)values and key environmental factors in cucumber(Cucumis sativus L.)cultivation in a greenhouse.SPAD values,indicative of chlor...This study aimed to explore the relationship between Soil-Plant Analysis Development(SPAD)values and key environmental factors in cucumber(Cucumis sativus L.)cultivation in a greenhouse.SPAD values,indicative of chlorophyll content,reflect plant health and productivity.The analysis revealed strong positive correlations between SPADvalues and both indoor light intensity(ILI,r=0.59,p<0.001)and outdoor light intensity(OLI,r=0.62,p<0.001),suggesting that higher light intensities were associated with enhanced SPAD values.In contrast,significant negative correlations were found between SPAD values and soil temperature at 15-30 cm depth(ST1530,r=−0.47,p<0.001)and volumetric soil moisture content at the same depth(SM1530,r=−0.52,p<0.001),with higher soil temperatures(e.g.,28℃)and excessive moisture(e.g.,25%)leading to reduced SPAD values.Multiple regression analysis identified ST1530 and SM1530 as significant negative predictors of SPAD,with coefficients of−0.97(p=0.05)and−0.34(p=0.05),respectively,suggesting that increases in soil temperature and moisture result in lower SPAD values.Indoor light intensity(e.g.,600-800μmol/m^(2)/s)emerged as a significant positive contributor,with a coefficient of 0.01(p<0.001),highlighting its role in promoting chlorophyll synthesis.Additionally,relative humidity(r=0.27,p<0.01)showed a positive,although less pronounced,association with SPAD.These results underscore the importance of both direct and indirect environmental factors in influencing SPAD variability and,by extension,plant health and productivity in cucumber cultivation.展开更多
A gigantic project named Gully Land Consolidation(GLC)was launched in the hillgully region of the Chinese Loess Plateau in 2011 to cope with land degradation and create new farmlands for cultivation.The dynamic change...A gigantic project named Gully Land Consolidation(GLC)was launched in the hillgully region of the Chinese Loess Plateau in 2011 to cope with land degradation and create new farmlands for cultivation.The dynamic change of groundwater table and loess subsidence in the backfilled farmland are the main causes of site disasters and soil disease,but there is a lack of research on these issues.Based on this,the Shijiagou(SJG)backfilled farmland which is a typical GLC engineering site located in Ansai District,Yan'an City,Shaanxi Province was selected as the study area in this paper.Field site monitoring was carried out in this area,including four aspects of monitoring:rainfall,groundwater table,soil moisture and soil settlement displacement.The following findings were obtained from the analysis of the monitoring data in 2019-2020:(1)The backfilled farmlands have suffered a significant groundwater table rise.And the percentage increase of groundwater table increased from the upstream of F-1(such as 49.2%,46.3%,26.4%)to the downstream of F-5(90.0%,52.3%,34.2%correspondingly),which is related to the terrain of the valley channel and dam seepage.It is also revealed that rainfall characteristics are positively correlated with the depth of water infiltration and groundwater table.(2)The influence depth of rainfall infiltration on soil moisture of the backfilled loess in the GLC study area is no more than 2.5 m,and that within 1.5 m depth is significantly affected by rainfall.In addition,the dramatic rise in the groundwater table led to a steep increase in soil moisture,thus the soil underwent collapse deformation due to water immersion,and the farmland experienced large subsidence displacement.(3)The backfilled loess of the GLC farmland was in a continuous consolidation and settlement stage after the filling completion.With the passage of time,the settlement displacement and settlement rate of the backfilled loess gradually decreased,from 1.0-1.9 mm/d in 2019 to 0.4-0.8 mm/d in 2020,which indicates the GLC farmland tended to be stable.This study reveals the hydrological evolution characteristics and settlement deformation laws of the backfilled loess,which is important for the stability of the farmland and the management of the GLC project.展开更多
The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock.This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City,Qin...The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock.This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City,Qinghai Province,China.Uniaxial creep tests were carried out on ultra-soft mudstone with various moisture contents.The test results indicated that the creep duration of the rock sample with a natural moisture content of 9%is 2400 times longer than that of the sample with a natural moisture content of 13%,while its accumulated strain is 70%of the latter.For the rock sample with a natural moisture content of 9.80%,the creep duration under 0.5 MPa load is 80%of that under 0.25 MPa load,yet the accumulated strain is 1.4 times greater.Additionally,porosity significantly influences the creep behavior of mudstone.Analysis of the cause of the Gaomiao landslide and field monitoring data indicates that the instability of the Gaomiao landslide is related to the moisture content of the landslip mass and external forces.The creep-slip curves of landslides and the creep deformation curves of rocks share a common trend.Precisely identifying the moment when the shift occurs from steady state creep to accelerated creep is critical for comprehending slope instability and rock failure.Moreover,this study delves deeper into the issue of the consistency between landslide creep and rock deformation.展开更多
基金financially supported by the Central Public-Interest Scientific Institution Basal Research Fund of Chinese Academy of Forestry(CAFYBB2021ZW002)the National Key Research and Development Program of China(2022YFF1300404)the National Natural Science Foundation of China(U21A2005)。
文摘Mountainous areas are the priority for forest restoration in semiarid regions,with hillslopes serving as the basic units of mountains.Precipitation is the only water source in these regions,and the uneven distribution of hillslope soil moisture replenishment after precipitation determines vegetation survival and growth.Therefore,in this study experiments were performed on a hillslope in the Liupan Mountains,Ningxia Hui Autonomous Region,China,to quantify the unevenness of soil moisture replenishment.Soil water content(SWC)in the 0–60 cm layer and precipitation were monitored throughout the growing season in 2020 and 2021.The results showed that(1)Annual soil moisture replenishment was the highest at the mid-slope position,with an average of 309.9 mm,especially under moderate and heavy rain grade conditions,reaching 38.7% and 30.8% of the total replenishment,respectively;(2)Vertical replenishment played a dominant role in the total replenishment,accounting for 82.8%;lateral replenishment played an important but lesser role,accounting for up to 17.2% of the total replenishment;(3)Based on a soil moisture replenishment model established in this study,the maximal replenishment occurred at 90 m from the top of the slope;(4)The dominant factors contributing to the soil moisture replenishment were rainfall amount and saturated hydraulic conductivity(Ks).These findings suggest that attention should be given to both vertical and lateral soil moisture replenishment,and the mid-slope position could be preferred for site selection to achieve precise and integrated forest-water management on hillslopes in semi-arid mountainous regions.
基金supported by the Natural Science Foundation of Henan Province(252300421290)the National Natural Science Foundation of China(41771438)+1 种基金the Program for Innovative Research Team(in Science and Technology)of Henan University(22IRTSTHN010)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(HNYJS2020JD14).
文摘Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.
基金supported by the State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering(Grant No.SKLGDUEK2206)National Natural Science Foundation of China(Grant No.11872340).
文摘Soil desiccation cracking is a common phenomenon on the earth surface.Numerical modeling is an effective approach to study the desiccation cracking mechanism of soil.This work develops a novel 3D moisture diffusion discrete model that is capable of dynamically assessing the effect of cracking on moisture diffusion and allowing moisture to be discontinuous on both sides of the cracks.Then,the parametric analysis of the moisture exchange coefficient in the 3D moisture diffusion discrete model is carried out for moisture diffusion in continuous media,and the selection criterion of the moisture exchange coefficient for the unbroken cohesive element is given.Subsequently,an example of moisture migration in a medium with one crack is provided to illustrate the crack hindering effect on moisture migration.Finally,combining the 3D moisture diffusion discrete model with the finite-discrete element method(FDEM),the moisture diffusion-fracture coupling model is built to study the desiccation cracking in a strip soil and the crack pattern of a rectangular soil.The evolution of crack area and volume with moisture content is quantitatively analyzed.The modeling number and average width of cracks in the strip soil show a good consistency with the experimental results,and the crack pattern of the rectangular soil matches well with the existing numerical results,validating the coupled moisture diffusion-fracture model.Additionally,the parametric study of soil desiccation cracking is performed.The developed model offers a powerful tool for exploring soil desiccation cracking.
文摘This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked asphalt.Thermodynamic parameters,morphological characteristics,interfacial healing energy,and interfacial healing strength were analyzed using molecular dynamics and macroscopic tests under different time,temperature,and water conditions to evaluate the specific states and critical conditions involved in self-healing.The results indicate that basalt-fiber molecules can induce rearrangement and a combination of water-soaked asphalt at the healing interface.Hydroxyl groups with different bonding states increase the interfacial adsorption capacity of water-soaked asphalt.The interaction between basalt fiber molecules and water molecules leads to a"hoop"phenomenon,while aromatics-2 molecules exhibit a"ring band aggregation"phenomenon.The former reduces the miscibility of water and asphalt molecules,while the latter causes slow diffusion of the components.Furthermore,a micro-macro dual-scale comparison of interfacial healing strength was conducted at temperatures of 297.15 and 312.15 K to identify the strength transition point and critical temperature of 299.4 K during the self-healing process of basalt-fiber modified water-soaked asphalt.
基金supported by the National Natural Science Foundation of China [grant number 42088101]。
文摘During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis results.To elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget analysis.The findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern Pacific.This increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective instability.Such a process is pivotal in amplifying intraseasonal convection anomalies.The observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns.
基金funded by the Ministry of Higher Education Malaysia(MOHE)through the Fundamental Research Grant Scheme(FRGS),Project Code:FRGS/1/2024/TK05/USM/01/4.
文摘Objectives This study investigated the effects of curdlan on the physical and sensory properties of pineapple jam,addressing the limitations of pectin such as high cost and low gelling efficiency in pineapple-based formulations.Materials and Methods Pineapple jams were prepared with three concentrations of curdlan(0.5%,1%,and 1.5%).The samples were assessed for cooking time,syneresis,water activity,pH,moisture content,colour,texture,microstructure,and sensory acceptability.Results Incorporating curdlan into pineapple jam shortened the cooking time,with 1.5%curdlan reducing it from 3 to 1 h.Curdlan also decreased syneresis and water activity while increasing the moisture content,pH,and colour attributes(lightness,redness,and yellowness)of the jam.Texture analysis revealed increased hardness and reduced adhesiveness with increasing curdlan concentration.Microstructural observations indicated more heterogeneous structures and greater particle aggregation as curdlan concentration increased.Sensory evaluations showed no significant differences in colour,taste,or overall acceptability,though the formulation containing 0.5%curdlan demonstrated superior spreadability.Conclusion Curdlan effectively improved the physical and functional properties of pineapple jam and reduced cooking time,suggesting its potential as a functional,cost-effective gelling agent.Further studies are needed to assess its scalability,shelf-life,and industrial feasibility.
基金the financial support of the National Natural Science Foundation of China(No.22205165).
文摘Moisture-enabled electricity generation(MEG)has emerged as a promising sustainable energy harvesting technology,comparable to photovoltaics,thermoelectrics,and triboelectrics[1].MEGs generate electricity by converting the chemical potential of moisture into electric energy through interactions with hygroscopic materials and nanostructured interfaces.Unlike solar or thermal harvesters,MEGs operate continuously by utilizing ubiquitous atmospheric moisture,granting them unique spatial and temporal adaptability.Despite nearly a decade of progress and the exploration of diverse material systems for MEG,the overall output power remains significantly limited due to inherently low charge carrier concentrations and restricted ion diffusion fluxes[2].As a result,standalone MEG devices often deliver low and unstable output,limiting practical applications.To enhance performance and versatility,recent efforts have explored hybridization of MEG with other ambient energy sources such as triboelectric or thermoelectric effects.
文摘Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some common factors that usually cause damage to trees when they are struck by lightning?2.How might the unique characteristics of a tree contribute to its ability to survive a lightning strike?
基金Funded by PotlatchDeltic Corporation,grant number RGPSQ17。
文摘A common concern to planting for reforestation is seedling failure that is directly measurable by seedling early field performance of growth and survival.Root growth potential(RGP)is a commonly used metric of seedling quality and has been considered indicative of seedling field performance.The effect of RGP is thought to be dependent on planting site and underlining environmental conditions.Moisture stress often is considered the primary cause of seedling failure in addition to other environmental factors such as soil physicochemical properties in regions such as the Inland Northwest of the United States that is prone to growing season drought.In addition,it is interesting to test whether seedling early field performance is related to their morphological attributes and whether the morphological attributes are related to RGP.A comprehensive evaluation on early field performance of three planted conifer species of interior Douglas-fir(Pseudotsuga menziesii(Mirb.)Franco var.glauca(Beissn.)Franco),grand fir(Abies grandis(Douglas ex D.Don)Lindl.),and western larch(Larix occidentalis Nutt.)was conducted in this study.It was found that RGP did not show clear correlation with early field performance across species.RGP also was not significantly correlated with seedling morphological measures such as below-and above-ground biomass and root-to-shoot ratio(R:S,by mass).Early field performance of growth and survival varied greatly across individuals of seedlings.The most influential predictors of early seedling growth and survival were their initial size(indicative of energy reserve)and soil temperature that likely interacted with soil moisture.Our findings suggest that seed stock selection for reforestation probably should favor species and genotypes with greatest heat tolerance that may be better adapted to future conditions in the region.
基金the Ministry of Science and Technology,Government of India,and Council of Scientific and Industrial Research(CSIR)(09/081(1371)/2019-EMRI)for its funding,supported by a NERC Independent Research Fellowship(MITRE,NE/W007924/1)。
文摘In this study,we investigate the complex relationship between western disturbances(WDs),the El Ni?o–Southern Oscillation(ENSO),and extreme precipitation events(EPEs) in the western Himalaya(WH) during the extended winter season(November–March).WDs west of WH coincide with 97% of recorded EPEs,contributing substantially(32% in winter,11% annually) to total precipitation within WH.WDs are 6% less frequent and 4% more intense during El Ni?o than La Ni?a to the west of WH.During El Ni?o(compared to La Ni?a) years,WDs co-occurring with EPEs are significantly more intense and associated with 17% higher moisture transport over “WH box”(the selected region where most of the winter precipitation over WH occurs).This results in twice the EPE frequency during El Ni?o periods than La Ni?a periods.A substantial southward shift(~180 km) of the subtropical jet(STJ) axis during El Ni?o brings WD tracks further south towards their primary moisture sources,especially the Arabian Sea.We have shown that WDs that are both more intense and pass to the south of their typical latitudes have higher levels of vertically integrated moisture flux(VIMF)within them.VIMF convergence in the most intense pentile of WDs is 5.7 times higher than in the weakest,and is 3.4 times higher in the second lowest latitude pentile than in the highest.Overall,this study demonstrates a direct link between changes in the latitudinal position and intensity of WDs associated with the winter STJ,and moisture convergence,which leads to the occurrence of EPEs over WH during ENSO phases.
文摘The article examines the impact of increased aridization of the territory due to an increase in air temperature,reduced precipitation,and the formation of moisture deficiency on grain yields in Northern Kazakhstan.The most important result of the work is the revealed inverse relationship between grain yields and the temperature of the growing season:low-yielding years are associated with high temperatures and droughts,and high-yielding years are associated with lower temperatures and an optimal ratio of heat and moisture.The novelty of this study is the use of the method of hydrological and climatic calculations in identifying the nature of temperature variability and precipitation in the territory of Northern Kazakhstan for the modern period(1991–2020)compared with the base period(1961–1990).At all the studied meteorological stations,there is a tendency for the average annual temperature and the temperature of the growing season to increase:in the forest-steppe zone with an average warming intensity of 0.3–0.33℃ per decade;in the steppe zone by 0.2–0.43℃ per decade;and in the growing season by 0.2–0.7℃ per decade.The air temperature in the steppe zone is rising more intensively than in the forest-steppe zone,and precipitation in the forest-steppe zone has changed more than in the steppe zone.An increase in the average annual air temperature during the growing season(May–August),combined with a shortage of atmospheric moisture or a constant amount of it,led to an increase in the degree of aridization of the territory,an increase in the frequency of droughts in the steppe zone of Northern Kazakhstan.
基金National Key Research and Development Plan of China,No.2023YFF0805703National Natural Science Foundation of China,No.42271268。
文摘Heatwaves are becoming increasingly frequent and severe,posing escalating risks to ecosystems and human well-being.While soil moisture(SM)deficits are recognized as important contributors to heatwave amplification,their spatially heterogeneous impacts across the Northern Hemisphere remain insufficiently understood.In this study,we analyze ERA5 reanalysis data(1980-2022)to investigate trends in heatwave frequency,intensity,and duration,as well as their sensitivity to SM variability.Our results show robust increases in heatwave occurrence(0.76 events per decade),intensity(0.81℃per decade),and average duration(0.40 days per decade),with extreme events,as represented by maximum intensity and duration,rising at even faster rates(2.18℃per decade and 0.83 days per decade,respectively).Strong negative correlations are observed between SM deficits and heatwave metrics,with the magnitude of this relationship varying across land cover types and heatwave severity levels.Quantile regression reveals that SM reductions have a greater impact at higher quantiles for most indicators.Cropland exhibits the highest sensitivity to SM anomalies,whereas forests show more resilience due to their superior water retention capacities.These findings underscore the crucial role of land-atmosphere interactions in shaping heatwave extremes,providing a scientific basis for enhancing early warning and adaptation strategies in the context of ongoing climate change.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.42422502,42275038)the China Meteorological Administration Climate Change Special Program(Grant No.QBZ202306)。
文摘Extensive flooding swept across large areas of Central Asia,mainly over Kazakhstan and southwestern Russia,from late March to April 2024.It was reported to be the worst flooding in the area in the past 70 years and caused widespread devastation to society and infrastructure.However,the drivers of this record-breaking flood remain unexplored.Here,we show that the record-breaking floods were contributed by both long-term climate warming and interannual variability,with multiple climatic drivers at play across the synoptic to seasonal timescales.First,the heavy snowmelt in March 2024 was associated with above-normal preceding winter snow accumulation.Second,extreme rainfall was at a record-high during March 2024,in line with its increasing trend under climate warming.Third,the snowmelt and extreme rainfall in March were compounded by record-high soil moisture conditions in the preceding winter,which was a result of interannual variability and related to excessive winter rainfall over Central Asia.As climate warming continues,the interplay between the increasing trend of extreme rainfall,interannual variations in soil moisture pre-conditions,as well as shifting timing and magnitudes of spring snowmelt,will further increase and complicate spring flooding risks.This is a growing and widespread challenge for the mid-to high-latitude regions.
基金supported by the Natural Science Foundation of Gansu Province(Grant Number:25JRRA749,24JRRA515,24JRRA527)the Fundamental Research Funds for the Central Universities(Grant Number:lzujbky-2022-ct01)+1 种基金JP and JS were supported by Spanish Government grants PID2020115770RB-I,PID2022-140808NB-I00,and TED2021-132627 BeI00funded by MCIN.SLC was supported by NSF award DEB-2423861.
文摘The primary mechanism driving plant species loss after nitrogen(N)addition has been often hypothesized to be asymmetric competition for light,resulting from increased aboveground biomass.However,it is largely unknown whether plants’access to soil water at different depths would affect their responses,fate,and community composition under nitrogen addition.In a semiarid grassland exposed to 8-years of N addition,we measured plant aboveground biomass and diversity under four nitrogen addition rates(0,4,10,and 16 g m2 year1),and evaluated plant use of water across the soil profile using oxygen isotope.Aboveground biomass increased significantly,but diversity and shallow soil-water content decreased,with increasing rate of nitrogen addition.The water isotopic signature for both plant and soil water at the high N rate indicated that Leymus secalinus(a perennial grass)absorbed 7%more water from the subsurface soil layer(20e100 cm)compared to Elymus dahuricus(a perennial grass)and Artemisia annua(an annual forb).L.secalinus thus had a significantly larger biomass and was more abundant than the other two species at the high N rate but did not differ significantly from the other two species under ambient and the low N rate.Species that could use water from deeper soil layers became dominant when water in the shallow layers was insufficient to meet the demands of increased aboveground plant biomass.Our study highlights the importance of water across soil depths as key driver of plant growth and dominance in grasslands under N addition.
基金financially supported by the National Natural Science Foundation of China(Grant No.42361002)the Fund of Ningxia Hui Autonomous Region(Grant No.2022AAC03665).
文摘Tafoni are globally developed on cliffy slopes,and many of them are favorable places for the preservation of stone historical relics.However,the characteristics and formation processes of tafoni in the Loess Plateau are yet to be understood.This paper studied the features of the tafoni on conglomerate slopes in Huoshizhai National Geopark of Ningxia Hui Autonomous Region and discussed its formation processes by field investigation and morphometry,insitu relative humidity(RH)measurement,salt chemistry and X-ray fluorescence spectrometer(XRF)experiments of 24 samples.The bedrock of the tafoni is dominated by reddish fluvial conglomerates of the Lower Cretaceous Heshangpu Formation with abundant chemically unstable components including feldspars,lithic fragments,and calcite cements.The RH values vary from 5%to 100%,but the backwalls of the tafoni have higher RH values than outer surfaces.The more moisture on the backwalls is possibly generated by water influx from the rock interior,resulting in more salt precipitation on the backwalls.As a result,the backwalls have been subject to predominant salt weathering.The dominant salts involved in salt weathering are probably derived from the dissolution of the salt interbeds in the basin,although the chemical dissolution of the unstable components such as feldspars,lithic fragments,and calcite cements might have produced small amounts of salts.The salt types dominantly include nitrates,sulfates,and halite.In the progression of tafoni,the moisture maintenance on the backwalls gives rise to the accretion of salts,which in turn enhance the weathering rates of the backwalls.As a result,the volumes of the tafoni have become enlarged owing to inward growth and coalescence of adjacent smaller ones.
基金Supported by Key Research and Development Program of Shanxi Province(202302140601009).
文摘Moistube irrigation is a newly-developed irrigation technique that utilizes a semipermeable membrane to release water slowly and continuously into the plant root zone.Alternate Moistube Irrigation(AMI)is a combination of alternative irrigation and moistube irrigation.In order to investigate the effects of AMI on plant growth,greenhouse experiments were conducted on spinach(Spinacia oleracea)and water spinach(Ipomoea aquatica)plants at different time.We measured soil water content at a depth of 20 cm in the planting boxes,and also determined seed emergence rate,plant height,largest leaf area,fresh weight per plant,yield,and irrigation water productivity(IWP)for both spinach and water spinach.The results showed that the AMI treatments had significantly higher soil water content than the conventional surface irrigation control(CK).The emergence rates of spinach and water spinach were significantly higher in the AMI treatments than in the CK,and the plant height,largest leaf area,and fresh weight during the middle and late stages of spinach and water spinach growth were also significantly higher than those of the CK.Both spinach and water spinach grew well and produced high yield with high IWP under AMI with a high water head pressure of 1.5 m at tube spacing of 20 or 30 cm.We found that AMI with a suitable combination of head pressure and tube spacing can promote plant growth and increase yield and IWP under controlled conditions.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFC1511603)the Fundamental Research Funds for the Central Universities(2572021BA04).
文摘The rate of fire spread is a key indicator for assessing forest fire risk and developing fire management plans.The Rothermel model is the most widely used fire spread model,established through laboratory experiments on homogeneous fuels but has not been validated for conifer-deciduous mixed fuel.In this study,Pinus koraiensis and Quercus mongolica litter was used in a laboratory burning experiment to simulate surface fire spread in the field.The effects of fuel moisture content,mixed fuel ratio and slope on spread rate were analyzed.The optimum packing ratio,moisture-damping coefficient and slope parameters in the Rothermel model were modified using the measured spread rate which was positively correlated with slope and negatively with fuel moisture content.As the Q.mongolica load increased,the spread rate increased and was highest at a fuel ratio of 4:6.The model with modified optimal packing ratio and slope parameters has a significantly lower spread rate prediction error than the unmodified model.The spread rate prediction accuracy was significantly improved after modifying the model parameters based on spread rates from laboratory burning simulations.
文摘This study aimed to explore the relationship between Soil-Plant Analysis Development(SPAD)values and key environmental factors in cucumber(Cucumis sativus L.)cultivation in a greenhouse.SPAD values,indicative of chlorophyll content,reflect plant health and productivity.The analysis revealed strong positive correlations between SPADvalues and both indoor light intensity(ILI,r=0.59,p<0.001)and outdoor light intensity(OLI,r=0.62,p<0.001),suggesting that higher light intensities were associated with enhanced SPAD values.In contrast,significant negative correlations were found between SPAD values and soil temperature at 15-30 cm depth(ST1530,r=−0.47,p<0.001)and volumetric soil moisture content at the same depth(SM1530,r=−0.52,p<0.001),with higher soil temperatures(e.g.,28℃)and excessive moisture(e.g.,25%)leading to reduced SPAD values.Multiple regression analysis identified ST1530 and SM1530 as significant negative predictors of SPAD,with coefficients of−0.97(p=0.05)and−0.34(p=0.05),respectively,suggesting that increases in soil temperature and moisture result in lower SPAD values.Indoor light intensity(e.g.,600-800μmol/m^(2)/s)emerged as a significant positive contributor,with a coefficient of 0.01(p<0.001),highlighting its role in promoting chlorophyll synthesis.Additionally,relative humidity(r=0.27,p<0.01)showed a positive,although less pronounced,association with SPAD.These results underscore the importance of both direct and indirect environmental factors in influencing SPAD variability and,by extension,plant health and productivity in cucumber cultivation.
基金funded by the National Natural Science Foundation of China for Distinguished Young People(No.41825018)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23090402)the Natural Science Foundation of China(No.41790442)。
文摘A gigantic project named Gully Land Consolidation(GLC)was launched in the hillgully region of the Chinese Loess Plateau in 2011 to cope with land degradation and create new farmlands for cultivation.The dynamic change of groundwater table and loess subsidence in the backfilled farmland are the main causes of site disasters and soil disease,but there is a lack of research on these issues.Based on this,the Shijiagou(SJG)backfilled farmland which is a typical GLC engineering site located in Ansai District,Yan'an City,Shaanxi Province was selected as the study area in this paper.Field site monitoring was carried out in this area,including four aspects of monitoring:rainfall,groundwater table,soil moisture and soil settlement displacement.The following findings were obtained from the analysis of the monitoring data in 2019-2020:(1)The backfilled farmlands have suffered a significant groundwater table rise.And the percentage increase of groundwater table increased from the upstream of F-1(such as 49.2%,46.3%,26.4%)to the downstream of F-5(90.0%,52.3%,34.2%correspondingly),which is related to the terrain of the valley channel and dam seepage.It is also revealed that rainfall characteristics are positively correlated with the depth of water infiltration and groundwater table.(2)The influence depth of rainfall infiltration on soil moisture of the backfilled loess in the GLC study area is no more than 2.5 m,and that within 1.5 m depth is significantly affected by rainfall.In addition,the dramatic rise in the groundwater table led to a steep increase in soil moisture,thus the soil underwent collapse deformation due to water immersion,and the farmland experienced large subsidence displacement.(3)The backfilled loess of the GLC farmland was in a continuous consolidation and settlement stage after the filling completion.With the passage of time,the settlement displacement and settlement rate of the backfilled loess gradually decreased,from 1.0-1.9 mm/d in 2019 to 0.4-0.8 mm/d in 2020,which indicates the GLC farmland tended to be stable.This study reveals the hydrological evolution characteristics and settlement deformation laws of the backfilled loess,which is important for the stability of the farmland and the management of the GLC project.
基金The work described in this paper is partially supported by the Second Tibetan Plateau Scientific Expedition and Research Grant(2019QZKK0708)ARC Discovery Project grants(DP210100437,DP230100126),for which the authors are very grateful.
文摘The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock.This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City,Qinghai Province,China.Uniaxial creep tests were carried out on ultra-soft mudstone with various moisture contents.The test results indicated that the creep duration of the rock sample with a natural moisture content of 9%is 2400 times longer than that of the sample with a natural moisture content of 13%,while its accumulated strain is 70%of the latter.For the rock sample with a natural moisture content of 9.80%,the creep duration under 0.5 MPa load is 80%of that under 0.25 MPa load,yet the accumulated strain is 1.4 times greater.Additionally,porosity significantly influences the creep behavior of mudstone.Analysis of the cause of the Gaomiao landslide and field monitoring data indicates that the instability of the Gaomiao landslide is related to the moisture content of the landslip mass and external forces.The creep-slip curves of landslides and the creep deformation curves of rocks share a common trend.Precisely identifying the moment when the shift occurs from steady state creep to accelerated creep is critical for comprehending slope instability and rock failure.Moreover,this study delves deeper into the issue of the consistency between landslide creep and rock deformation.
