Index Of Temporal Stability Research Articles

The temporal stability of maternal parenting style and child feeding practices: A six-wave longitudinal study

Although parenting styles and child feeding practices are conceptualized as distal, static predictors of child eating and weight outcomes, few studies have examined the temporal stability (i.e., change over time) of these parenting measures. Also, parental characteristics, such as mental health or socio-demographics, may make it more or less difficult to sustain consistent parenting behavior. This study examined the temporal stability of parenting styles and child feeding practices and the association between temporal stability indices with maternal sociodemographic and mental health characteristics. The analytic sample included 161 ethnically diverse mothers enrolled in a six-wave bi-annual longitudinal study. During each wave, mothers reported on their parenting styles and child feeding practices using validated self-report questionnaires. Temporal stability indices for parenting styles were moderate for authoritative (ICC = 0.57) and authoritarian (ICC = 0.70) styles, yet high for permissive (ICC = 0.78) styles. Temporal stability scores for child feeding practices were low for discipline (ICC = 0.33), limit setting (ICC = 0.33), monitoring (ICC = 0.36), and pressure to eat (ICC = 0.34); however, restriction (ICC = 0.53) and role modeling of healthy eating were moderate (ICC = 0.73). Greater income and education status were positively associated with stability in authoritative, authoritarian, and permissive parenting styles, as well as with limit setting, monitoring, role modeling of healthy eating, and pressure to eat feeding practices. Higher anxiety and depressive symptoms and lower self-esteem were negatively associated with permissive parenting styles and role modeling of healthy eating. Findings show that maternal parenting styles and child feeding practices fluctuate over time, and sociodemographic and mental health characteristics are related to stability of some of these parenting styles and behaviors.

Effects of vegetation on the spatiotemporal distribution of soil water content in re-vegetated slopes using temporal stability analysis

The temporal stability of soil water is a critical state variable affecting hydrological process and structural stability of slopes. In this study, the effect of vegetation on the spatiotemporal characteristics of soil water content (SWC) was assessed via temporal stability analysis. Three types of re-vegetated slopes (grass, shrub, and grass-shrub) were constructed to explore the spatiotemporal distribution of the SWC at depths of 0–100 cm. Then, the effects of different vegetation covers on the SWC were explored. The coefficient of variation, the Spearman rank correlation coefficient, the mean relative difference, and the index of temporal stability were utilized to demonstrate the temporal stability of the SWC. Finally, a method of estimating the soil water status of re-vegetated slopes based on representative locations was developed. The results revealed that soil water dynamics were considerably governed by vegetation and rainfall. The vegetation cover considerably reduced the similarity of the spatial distribution pattern of the soil water, which tended to be more stable under grass cover. The weight-based prediction method developed in this study can more accurately estimate the overall soil water state of re-vegetated slopes. It provides a theoretical basis for the reasonable layout of SWC monitoring points and guidance for the ecological restoration of engineering slopes.

Role of cultivars and grass in the stability of soil moisture and temperature in an organic vineyard

Soil water content (SWC) and temperature (ST) are main parameters in agriculture, but are difficult to predict due to the numerous processes involved. To find stability patterns, this study evaluated the soil hydro-thermic response in a rainfed organic vineyard with humid climate, a permanent grass cover and under no-tillage and homogeneous soil and topographic conditions. The differences between the rows (R) and inter-row areas (IR) and two cultivars (Agudelo –Ag– and Blanco Legítimo –BL–) were assessed. SWC and ST were measured with 12 probes every 15 min at 5, 15 and 25 cm depth over the crop cycle (242 days). On average, wetter (+2.2%) and cooler (−1.4%) values appeared in Ag than in BL that may be associated with differences in vine water demand. IR had wetter (+5.9%) and cooler (−0.7%) conditions than R due to higher water consumption by vines. Significant differences appeared when time-series analysis was split into three periods: drying and warming (spring), dry and warm (summer), and wetting and cooling (autumn). SWC and ST correlated well in R, but moderate correlations appeared in IR, showing a more complex pattern in this zone. In general, the most stable conditions appeared at 15 cm depth, with drier and warmer conditions in the deepest layer in spring and autumn. This vertical pattern did not vary over time for ST, but IR had the most stable and moistest conditions in summer at 25 cm. The relative differences among zones and cultivars revealed that Ag had moister, but less representative, conditions than BL at the three soil layers in spring, and this pattern kept in summer at 15 and 25 cm, but only in autumn at 15 cm. Regarding ST, the pattern was very stable, and cooler and representative conditions prevailed in Ag. BL has been rarely cited in the literature, and these results contributed with new insights about the SWC and ST dynamic on this cultivar. Cooler conditions always appeared in IR, compared with R; and R always had more representative values of SWC than IR. The pattern of ST was more variable and R only had more representative values than IR at 15 cm in summer and at 25 cm in spring and summer. This article represents the first study that calculated the index of temporal stability (ITS) for SWC and ST in any type of woody crop. Our findings allowed to identify the most representative areas of the hydro-thermic response of the soil in the vineyard, which is of interest to save time and resources during long-term monitoring tasks in commercial vineyards.

Temporal stability analysis evaluates soil water sustainability of different cropping systems in a dryland agricultural ecosystem

The Loess Plateau is a typical dryland agricultural region where water shortages are the primary limiting factor for crop production. Deep soil moisture plays a crucial role in the regulation of seasonal water shortages, however, the distribution of soil water and its temporal variation in the deep soil profile (i.e., below 2.0 m) are usually unknown in a dryland agricultural field. A field study of three cropping systems (i.e., WWC, continuous winter wheat; SMC, continuous spring-maize; and WMR, a rotation of winter wheat and spring maize) and three tillage practices (i.e., NT, no tillage; ST, subsoiling tillage; and CT, conventional tillage) was carried out in a semi-arid region, and the crop yield, vertical distribution patterns and temporal variability of the soil moisture in a 5.0 m soil profile were studied to evaluate the effect of the various management strategies on the soil water sustainability. The results indicated that the WMR and SMC systems combined with ST practice obtained higher crop yield and water use efficiency, compared to the WWC system. And the time-averaged soil moisture for the three cropping systems differed significantly (P < 0.05). The WWC system can utilize soil water below 2.0 m and caused greater soil water depletion in the 0–5.0 m soil layer. However, no significant differences in the soil water content were found among the different tillage practices. The top soil layer showed a higher index of temporal stability (ITS) value for all cropping systems, but the ITS increased with soil depth in the deep soil profile (below 3.0 m) with the WWC system. Ultimately, the most time-stable depth (MTSD) for estimating the mean soil moisture of the profile was determined to be the 2.0–3.0 soil layer for all three systems based on the ITS values, but the mechanism by which the MTSD was formed differed for the various cropping systems. The soil moisture at the MTSD under WMR and SMC had high temporal stability, and contributed to better soil water sustainability in a dryland agricultural field. These findings may provide helpful base references for evaluating the effect of different management strategies on the soil water and the temporal stability parameters of soil moisture, as well as their impact on the sustainability of the deep soil moisture in a dryland agricultural field.

Temporal Stability Analysis for the Evaluation of Spatial and Temporal Patterns of Surface Water Quality

Better characterizing the spatio-temporal pattern of water quality would increase the ability to effectively manage water resources. This study applied the concept of temporal stability analysis (TSA) to explore the temporal characteristics of spatial variability in surface water quality. Measurement data from 41 monitoring stations in Qiantang River, China during 2017–2019 were used for analysis. The data included four water quality indicators: dissolved oxygen (DO), permanganate index (CODMn), total phosphorus (TP), and ammonia nitrogen (NH3–N). A Spearman’s rank correlation for each pair of monitoring times was performed to characterize the spatial pattern of water quality. A temporal analysis of relative differences was applied to examine the temporal stability of the sampling sites. The rank correlation analysis suggests that the spatial pattern of water quality was maintained for a specific period of time and the TP concentration was most temporally stable compared with the other three indicators across the study area. The standard deviation of the relative difference (SDRD) and index of temporal stability (ITS) were found to be better for identifying the stable sites compared to the mean absolute bias error (MABE) and root mean square error (RMSE) in this study. A correlation analysis between the temporal stability indices and potential influencing factors showed that land use proportions (forest, built-up land, and agricultural land), and socio-economic indicators (gross domestic product [GDP] and population density) were closely associated with the temporal stability of water quality. The results showed evidence that the TSA method was feasible and effective in identifying the temporal stability of surface water quality and optimizing the water quality monitoring program. This study’s method and findings can help improve surface water quality monitoring strategies and water resource management.

Spatiotemporal variability of soil-water characteristic curve model parameters of Lanzhou collapsible loess

Abstract The spatiotemporal variation of the model parameters of the soil-water characteristic curve (SWCC) reflect the soil water holding capacity and soil pore distribution state. It is an integral part of interdisciplinary disciplines such as soil hydrodynamics and ecohydrology. The authors selected the optimal SWCC model for the Lanzhou collapsible loess, used classical statistics and geostatistics methods to study the spatiotemporal variability of the SWCC model parameters, and using the comprehensive comparison of the mean relative differences (MRD), standard deviations (SDRD) and an index of temporal stability (ITS) determined the representativeness measuring point. The results showed that the SWCC parameter α was medium variability in the 0–30 cm soil layer, n and θs were of low variability, and the spatial distribution of the parameters of different soil layers was consistent. Migration direction prediction of θs was very similar in each layer, α, n and θs were all strongly significantly correlated positively. Moreover, the determination coefficient of representative measuring point 16 had the highest prediction accuracy for the measured values of SWCC. The results of this paper can be used as a simple method to predict SWCC and provide theoretical guidance for soil water management and soil collapse erosion monitoring in the collapsible loess area.

Efficient prediction of profile mean soil water content for hillslope-scale Caragana korshinskii plantation using temporal stability analysis

Spatio-temporal variability in soil water content (SWC) increases the difficulty in soil water resource management and vegetation construction in arid and semi-arid regions. Our objectives were to investigate the spatial variability and temporal stability of SWC and identify representative locations for reliably predicting the profile mean SWC (MSWC) of a 33-year-old Caragana korshinskii plantation on typical sunny and shady hillslopes on the Loess Plateau, China. The profile SWC (0–180 cm) in three sampling belts and five hillslope positions (upper position, UP; upper-middle position, UMP; middle position, MP; lower-middle position, LMP; lower position, LP) were measured 27 times for both the hillslopes in 2018 and 2019. The mean relative difference (MRD), the standard deviation of the MRD (SDRD), and an index of temporal stability (ITS) were used to identify representative locations of the MSWC. The results indicated that the SWC presented different horizontal but similar vertical change trends in the five hillslope positions. The profile MSWC on the sunny hillslope (8.89%) was lower than that on the shady hillslope (9.44%). The mean Spearman correlation coefficients of the temporal patterns ranged from 0.6 to 0.8 for the five soil layers on both hillslopes. The characteristics of temporal stability differed in both temporal persistence and the representative locations for the five soil layers on the sunny and shady hillslopes. The mean ITS values generally decreased with increasing soil depth. Ultimately, the representative locations for estimating the profile MSWC were determined to be the MP-2 location on the sunny hillslope and the MP-3 location on the shady hillslope based on the MRD, SDRD, and ITS values. The representative locations have the lowest ITS values and represent the MSWC accurately, with root mean square error (RMSE) and mean error (ME) values of less than 1%. In addition, the soil organic carbon, clay, silt, and sand contents greatly affect the spatial and temporal distributions of the soil water at the hillslope scale. Our study provides a rapid and accurate method for determining profile MSWC in C. korshinskii plantations on typical sunny and shady hillslopes and could also support valuable guidance for the rational management of hillslope-scale SWC resources for similar dry regions.

Multitemporal InSAR Coherence Analysis and Methods for Sand Mitigation

Dunes and sand sheets motion natural hazard affect many desertic areas worldwide and require careful assessment to develop effective mitigation plans to protect populated sites, infrastructure, and human activities. The study explores the suitability of Synthetic Aperture Radar (SAR) coherent methods to detect desert area instabilities and estimate sand accumulations displacements. The SAR methods have been applied to long time series of images provided by Sentinel-1. Moreover, the research introduces a novel robust index, named Temporal Stability Index, able to characterize the percentage of stability of a target with time. The work reports the experiments performed on the United Arab Emirates (UAE) and Egypt desertic areas and proves the usefulness of SAR coherent methods to support sand mitigation measures.

Temporal dynamics of evapotranspiration in semiarid native forests in Brazil and Spain using remote sensing

AbstractEvapotranspiration (ET) plays an important role in integrated water resource planning, development and management. This process is particularly relevant in semiarid regions. The aim of this study is, hence, to compare spatial and temporal patterns of actual ET, as well as the temporal trends in two different semiarid forests, Caatinga (Brazil) and Tierra de Pinares (Spain). We used the surface energy balance algorithm for land (SEBAL) to assess actual evapotranspiration (ETa) in both areas. In the Brazilian semiarid forest, Caatinga is the main vegetation, while it is Pinares in Spain. For this purpose, 69 Landsat‐5 and 42 Landsat‐8 images (1995–2019) were used. The Mann–Kendall test was applied to assess the occurrence of trends in precipitation, temperature and potential ET data; and the Temporal Stability Index (TSI) to know which areas have greater seasonal ETa. The annual amplitude of the potential evapotranspiration (ET0) is the same in both areas, however, the Caatinga values are higher. In the Caatinga forest, when ET0 presents its highest values throughout the year, ETa presents the lowest, and vice versa. In the Pinares forest, ETa follows the ET0 dynamics during the year, and the difference between ET0 and ETa is maximum during the summer. The Caatinga forest showed a greater spatial variation of ETa than the Pinares forest as well as a greater extension with lower temporal stability of ETa than the Pinares forest. Both the Caatinga forest and the Pinares forest showed significant positive trends in annual ET0 and ETa. We estimate that the value of ETa increases more rapidly in Pinares than in the Brazilian Caatinga. Taking Caatinga as a hydrological mirror, some consequences are expected to Pinares, such as significant changes in the water balance, increase of biodiversity vulnerability, and reduction of water availability in soil and reservoirs.

Management of Test Anxiety Among Pupils in Basic Science Using Music-Based Cognitive Behavior Therapy Intervention: Implication for Community Development

Effectiveness of music-based cognitive behavior therapy (CBT) intervention has been established on various participants such as students in secondary schools, university students, and other categories of adults. However, there is a dearth of literature on the effectiveness of music-based CBT intervention program on the management of primary school pupils’ test anxiety in basic science. Thus, this study sought the effectiveness of a music-based CBT intervention program on the management of test anxiety among pupils. A randomized controlled trial experimental design was adopted for the study using a sample of 58 primary three (3) pupils. Test anxiety questionnaire (TAQ) was adopted for data collection. TAQ was trial-tested due to the cultural differences of the participants. The internal consistency reliability of the items of TAQ was estimated to be .79 using the Cronbach alpha method, while its estimate of temporal stability index was .86 using Pearson product moment correlation. Data were analyzed using mixed-design repeated measures analysis of variance and analysis of covariance. The findings of the study revealed that music-based CBT had a significant effect on the management of test anxiety among pupils. This finding has implication for community development in the sense that test anxiety among pupils can be better managed using the music-based CBT intervention program. This will enable the children to grow better academically and contribute to the community they belong to. It was thus recommended that primary school teachers should be enlightened on how to make use of music-based CBT in the management of test anxiety among pupils.

Evaluating the applicability of soil moisture-based metrics for gauging the resiliency of rainfed agricultural systems in the midwestern United States

Measuring and improving resiliency is the key goal of climate risk management in rainfed agriculture. Currently, available metrics are generally used to qualitatively measure the resilience of agricultural systems at broader scales. Moreover, these metrics showed non-linear responses to climate variability, thus often fail to capture the temporal dynamics of resilience at field scales. Our objective for this study is to combine a few soil moisture-based metrics to gauge the resiliency of three promising rainfed agricultural treatments, namely the no-till, organic, and reduced input treatments against the conventional treatment. These treatments have been established at the Kellogg Biological Station Long-Term Ecological Research (KBS-LTER) experiment in a randomized complete block design with six blocks per treatment. All four of these treatments consisted of maize (Zea mays)-soybean (Glycine max)-winter wheat (Triticum aestivum) in rotation. Long-term (1993–2018) soil moisture data from this experiment was collected to compute the soil moisture metrics while the total crop biomass, crop yield, and soil organic carbon data were statistically analyzed to evaluate the robustness of the metrics to gauge the resiliency of these systems. Results have shown that, among the soil moisture metrics, the mean relative difference, the Spearman’s rank correlation coefficient, and soil water deficit index were suitable, while the index of temporal stability was not suitable to gauge the resiliency of different rainfed agricultural systems. The no-till treatment was identified as the most resilient treatment in terms of soil moisture retention, effectiveness for drought mitigation, and crop yields. Meanwhile, the reduced input treatment was the least resilient in terms of soil water conservation and drought recovery. The results of this study can be extended to other Midwest regions of the United States and similar climatological areas around the world.

A NOVEL INDEX FOR TEMPORAL STABILITY ANALYSIS IN SPACE AND TIME OF SAR-DERIVED SCENES

Abstract. Detecting temporal changes is one of the most important applications of satellite sensors. In recent years, the increasing availability of regular time-series of SAR imagery, provided by the Sentinel-1 mission of the European Space Agency (ESA), has drawn increasing attention to these techniques, especially in earth environment monitoring and risk management. Within this paper, a coherent change detection analysis for evaluating the risk due to movements of dunes and sand sheets in desertic areas is proposed. To this purpose, we introduce a novel, coherence-based index, named Temporal Stability Index (TSI), that is suited for characterizing the percentage of stability of a target with time. TSI maps can be generated over areas as wide as hundreds of kilometers, in a short time, and mostly by exploiting available software tools (plus some simple coding). The information provided is complementary to the average of the short-term coherence, here shown. Results of analysis performed on two desertic regions (the United Arab Emirates and Egypt) document the usefulness of TSI for the identification of dune movements and areas subject to sand accumulation, supporting risk mitigation measures.

Applicability of temporal stability analysis in predicting field mean of soil moisture in multiple soil depths and different seasons in an irrigated vineyard

Accurately estimating field mean of soil water content (SWC) is important for irrigation management in an agricultural field. Temporal stability (TS) analysis has been widely applied to identify representative locations (RLs) for predicting spatial mean of SWC in natural landscapes. The objectives of the study were to examine TS patterns of SWC at various soil depths in different years, and to evaluate the performance of TS analysis in predicting field mean in an irrigated vineyard. Soil water content was measured regularly at 135 locations in the vineyard at soil depths of 0–20, 20–40, and 40–60 cm in 2012–2014. Temporal stability indices of mean relative difference (MRD), standard deviation of relative difference (SDRD), the comprehensive indicator (CI), and the mean absolute bias error (MABE) were obtained for each location at different depths in different seasons. The range of MRD and standard deviation of MRD (SDMRD) increased with soil depth for the three years. Inter-season correlations of the indices at the same depth were stronger than those between different depths of the same year. The RLs identified by CI and MABE were different between different soil depths and between the three seasons. Temporal stability analysis outperformed the random sampling method greatly, and on average one single RL could achieve RMSE about 2% and the maximum absolute error (MAE) less than 4% at a given sampling day during the validation period when the same year data were used to identify the RL. Estimation error could be reduced by 40% with the number of RLs increased from one to four. For most cases, four RLs identified by 2012 data were good enough to obtain RMSE and MAE less than 3% for the following two years. Soil texture information was found unable to identify RLs that could reliably estimate field mean. Temporal stability analysis is a valuable tool in identifying RLs to estimate field mean in an irrigated agricultural field, while intensive SWC sampling during half an irrigation cycle is needed to identify the RLs.

Temporal stability of soil water content on slope during the rainy season in gully regulation watershed

To increase reserve farmland resources, ensure food security, and to improve the ecological environment, large-scale gully regulation projects in Yan'an area of the Loess Plateau have been undertaken in China since 2013. Understanding the spatial and temporal distribution characteristics of slope soil moisture during the rainy season is, therefore, important for vegetation selection used in restoration measures in this area. The temporal stability of soil water content in the upper 100 cm soil depth in a gully regulation watershed was examined using six measurements taken during the rainy season (May–November 2016). Temporal stability analysis of the soil water content was undertaken using Spearman’s rank correlation coefficient and the relative difference method. Results showed that soil water content in the 0–50 cm and 0–100 cm soil depths demonstrated moderate temporal and spatial variability, and soil water content variability gradually decreased with increasing soil depth. Soil water content in both depths had strong temporal stability, having a positive correlation with soil depth. Furthermore, temporal stability may decrease with increasing soil water content (p < 0.05). The number and position of representative locations were not constant, which varies with the soil depth and the estimation method. Five methods (mean relative difference, minimum relative difference standard equilibrium, temporal stability index, mean absolute deviation and root mean square error) can be used to determine the representative location of temporal stability. However, the prediction accuracy of the soil water content at representative locations obtained using the different methods for mean slope water content differed. Comparatively, the mean absolute deviation method had a higher accuracy, followed by the minimum relative difference standard equilibrium method. Results indicate that the prediction accuracy of five methods increased with soil depth.

Validation study of an Italian version of the revised Sense of Coherence Scale (SOC-R)

The present study aims to validate the Italian version of the revised Sense of Coherence Scale (SOC-R). The scale was administered to a large sample of Italian adults (N = 689; 54.3% females, Mage = 34.09, SD = 16.27, range = 18–84) along with measures of related psychological concepts. Confirmatory factor analyses indicated adequate fit for the three-factor structure of the scale (i.e., manageability, balance, and reflection). Internal consistency and temporal stability indices confirmed the reliability of the scale and associations with related constructs, including personality, general resistance resources, well-being, and stress, provided evidence of its validity. This study demonstrated that the Italian version of the SOC-R is a valid and reliable measure that can be utilized for clinical and research purpose.

TEMPORAL STABILITY OF TOTAL ORGANIC CARBON OF SOILS UNDER DIFFERENT USES IN THE CAATINGA BIOME

ABSTRACT The objective of this work was to evaluate the temporal stability of total organic carbon (TOC) of soils under different uses in areas with Caatinga vegetation. The experiment was conducted in an experimental farm that encompasses a watershed in the Curu River Valley, in Pentecoste, state of Ceara, Brazil. Soil samples were collected in two areas with Caatinga vegetation under different uses-one with a 35-year preserved area (CP35) and one with a 30-year pasture area (CR30)-and the sampling points were distributed using a 30×30 m uniform grid. Soil samples of the 0-0.2 m layer were collected between February 2016 and April 2017 to determine TOC; and nonparametric Spearman's correlation, mean relative difference (MRD), and temporal stability index (TSI) tests were applied to evaluate TOC stability. The Spearman's test showed a higher correlation between collection dates for CR30 than for CP35. The DRM showed more points with relative differences approaching zero for CP35, and more points with lower standard deviation for CR30. The TSI indicated a greater number of points to be used for CR30 because they have better temporal stability. Therefore, the TOC of the CR30 has better temporal stability than that of the CP35, presenting TSI of approximately 1.5-fold that of the CP35. The thinning of the vegetation in CR30 homogenized the soil TOC, whereas the fallow area, which were preserved, had greater heterogeneity.

Moisture Temporal Stability of a Typic Hapludox under Different Uses and Depths

Temporal stability shows that specific within‐field locations can represent average moisture values for a period of time, reducing efforts of collecting and measurement field observations. The objective of this study was to analyze the temporal stability of soil moisture within a Hapludox, typical of Cerrado, a unique Brazilian biome (similar to savanna), located in the southwestern state of Goiás. Instant readings of volumetric soil moisture were done biweekly from November 2013to February 2014, using a portable TDRSensor with rods of 0.12 m in length, at 0‐ to 0.12‐, from 0.12‐ to 0.24‐, and 0.24‐ to 0.36‐m soil depths. The TDR sensor data were corrected and calibrated by volumetric water content data obtained from gravity method and soil bulk density measurements. To quantify temporal stability, we used nonparametric methods: Spearman correlation coefficient, average relative difference, and temporal stability index. Temporal stability on the field scale differed between the three sites/systems. Average soil moisture can be accurately estimated at only one georeferenced point for each site/management system, reducing measurement effort in long‐term studies.Core Ideas Moisture temporal stability reduce cost of field measurements. It is essential to planning monitoring programs of hydrology and irrigation. Represent a valuable support for future researches related to soil water management.

Spatial and temporal variability of soil moisture in relation with topographic and meteorological factors in south of Ardabil Province, Iran

This research has been tried to evaluate the spatial and temporal variability of surface soil moisture (SM) in a semi-arid and cold region of Ardabil Province in Iran with an area of about 10,000km2. The used SM data is the SMAP Enhanced L2 Radiometer Half-Orbit 9km Soil Moisture, provided by NASA. The study area was subdivided into 120 locations consisting 10 × 12 grids, matching with the pixels of the SMAP images. In order to evaluate the spatial variations of SM, the relation of mean SM with coefficient of variation and standard deviation has been evaluated and, then, the representative location for mean SM of the area has been identified using the index of temporal stability. Moreover, the effect of topographic factors (elevation, slope, and aspect) on spatial variations of SM, and the effect of meteorological factors (rainfall, sunshine hours, temperature, relative humidity, wind speed, and number of dry days) on temporal variations of SM have been investigated. The relation of mean SM with the coefficient of variation and standard deviation represented an exponentially negative and upper convex shape, respectively. The SM content of the representative location had a correlation with the mean SM of the area with the coefficient of determination value of 0.91. Of the three topographic factors, only the slope factor, and of the meteorological factors all of them except the wind speed have showed a significant relationship with SM spatial and temporal variations respectively.

Spatial Pattern and Temporal Stability of Root-Zone Soil Moisture during Growing Season on a Larch Plantation Hillslope in Northwest China

Soil moisture plays a decisive role for tree growth and forest ecosystems services supply in dryland regions. Hence, it is necessary to clarify the spatio-temporal variation of soil moisture under field conditions. This study selected a hillslope in the Liupan Mountains covered by the plantation of Larix principis-rupprechtii Mayr (larch), a main afforestation tree species in north and northwest China. The volumetric soil moisture (VSM) in root zone layers was monitored with a time interval of about 15 days during the growing season (from May to October) in 2016 at 48 points on this hillslope. The aim was to evaluate the spatial pattern and temporal stability of soil moisture at slope scale. The results showed a moderate spatial variability of VSM in each soil layer, with the variation coefficients range of 17.12–22.63%. The spatial variability of VSM showed a dependence on the soil wetness and a threshold effect, it increased with rising VSM until the VSM reached a threshold of about 15%, but thereafter decreased. The mean relative difference (MRD) among the 48 points ranged from −30.56% to 27.20%, −29.89% to 39.58%, and −28.13% to 33.71% for the soil layers of 0–20, 20–40, and 40–60 cm, respectively. The associated standard deviation (SDRD) (and range) was 11.38% (5.20–26.06%), 8.28% (4.64–15.63%), and 6.51% (2.00–14.16%) for the soil layers of 0–20, 20–40, and 40–60 cm, respectively. The high Spearman’s rank coefficients (p &lt; 0.05) among the measuring dates at each soil layer indicated that the spatial distribution of VSM in the root zone had strong temporal stability. The decrease of Spearman’ rank correlation coefficient and mean SDRD with rising soil depth indicated an increasing temporal stability of VSM with rising soil depth. The mean VSM of the three soil layers on the entire hillslope can be estimated by the direct method (using representative points determined by the index of temporal stability (ITS)) successfully, and these representative points determined by ITS were mainly located at the points with a ratio of field capacity to leaf area index (LAI) close to the slope mean. Moreover, the mean VSM of the three soil layers on the entire hillslope can also be estimated by indirect method (using the time-stable points determined by mean absolute bias error (MABE) and considering the offset between slope mean VSM and observed VSM at time-stable points), and the prediction accuracy of the indirect method was better than the direct method. Significant correlation between MRD and soil bulk density, field capacity, capillary porosity, and LAI were observed for all soil layers, indicating that both the water-retention ability in root zone soil (expressed mainly by field capacity) and water-consumption ability of trees (expressed mainly by canopy LAI) are the main factors controlling the spatial pattern of root-zone VSM on the larch plantation hillslope studied.

Temporal stability and variability of soil-water content in a gravel-mulched field in northwestern China

Characterizing the spatiotemporal variability of soil-water content (SWC) is of paramount importance in many scientific fields and operational applications. We present a case study of the temporal stability and variability of SWC in a gravel-mulched field, a form of mulching that has been widely used by farmers on the loessial area of China for over 300years, using Spearman correlation coefficients, frequency distributions and an index of temporal stability. SWC was measured weekly from May to August 2013 in the 0–10, 10–20, 20–30 and 30–50cm layers. SWC was more variable in the surface soil, due to several environmental factors, and the variability gradually decreased with depth. A large sample size was needed for estimating the mean SWC of the field under dry conditions. High Spearman correlation coefficients between the SWCs measured on different sampling campaigns indicated a high temporal stability. The stability of the SWC spatial patterns over time and along the soil profile allowed us to identify a location representative of the field-mean SWC, with high coefficients of determination ranging between 0.8564 and 0.9325. The large-scale monitoring of SWC from few observations is thus feasible, which will aid the management of soil moisture in gravel-mulched fields in arid regions.