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Water stress on crops can severely disrupt crop growth and reduce yields, requiring the accurate and prompt diagnosis of crop water stress, especially in semiarid regions. Infrared thermal imaging cameras are effective tools to monitor the spatial distribution of canopy temperature (Tc), which is the basis of the daily water stress index (DWSI) calculation. This research aimed to evaluate the variability of plant water stress under different soil cover conditions through geostatistical techniques, using detailed thermographic images of Neem canopies in the Brazilian northeastern semiarid region. Two experimental plots were established with Neem cropped under mulch and bare soil conditions. Thermal images of the leaves were taken with a portable thermographic camera and processed using Python language and the OpenCV database. The application of the geostatistical technique enabled stress indicator mapping at the leaf scale, with the spherical and exponential models providing the best fit for both soil cover conditions. The results showed that the highest levels of water stress were observed during the months with the highest air temperatures and no rainfall, especially at the apex of the leaf and close to the central veins, due to a negative water balance. Even under extreme drought conditions, mulching reduced Neem physiological water stress, leading to lower plant water stress, associated with a higher soil moisture content and a negative skewness of temperature distribution. Regarding the mapping of the stress index, the sequential Gaussian simulation method reduced the temperature uncertainty and the variation on the leaf surface. Our findings highlight that mapping the Water Stress Index offers a robust framework to precisely detect stress for agricultural management, as well as soil cover management in semiarid regions. These findings underscore the impact of meteorological and planting conditions on leaf temperature and baseline water stress, which can be valuable for regional water resource managers in diagnosing crop water status more accurately. [ABSTRACT FROM AUTHOR]

Background: Festuca kryloviana is a significant native grass species in the Qinghai Lake region, and its low emergence rate is a primary factor limiting the successful establishment of cultivated grasslands. The region's arid and low-rainfall climate characteristics result in reduced soil moisture content at the surface. Despite the recognized impact of water availability on plant growth, the specific role of moisture in seedling development remains not fully elucidated. This study aims to investigate the germination rate and seedling growth velocity of F. kryloviana seeds under varying moisture conditions, and to integrate physiological and transcriptomic analyses of seedlings under these conditions to reveal the mechanisms by which water influences seedling development. Results: The emergence rate of F. kryloviana seedlings exhibited an initial increase followed by a decrease with increasing moisture content. The highest emergence rate, reaching 75%, was observed under 20% soil moisture conditions. By the eighth day of the experiment, the lengths of the plumules and radicles under the optimal emergence rate (full water, FW) were 21.82% and 10.87% longer, respectively, than those under closely matching the soil moisture content during the background survey (stress water, SW). The differential development of seedlings under varying moisture regimes is attributed to sugar metabolism within the seeds and the accumulation of abscisic acid (ABA). At FW conditions, enhanced sugar metabolism, which generates more energy for seedling development, is facilitated by higher activities of α-amylase, sucrose synthase, and trehalose-6-phosphate synthase compared to SW conditions. This is reflected at the transcriptomic level with upregulated expression of the α-amylase (AMY2) gene and trehalose-6-phosphate synthase (TPS6), while genes associated with ABA signaling and transduction are downregulated. Additionally, under FW conditions, the expression of genes related to the chloroplast thylakoid photosystems, such as photosystem II (PSII) and photosystem I (PSI), is upregulated, enhancing the seedlings' light-capturing ability and photosynthetic efficiency, thereby improving their autotrophic capacity. Furthermore, FW treatment enhances the expression of the non-enzymatic antioxidant system, promoting metabolism within the seeds. In contrast, SW treatment increases the activity of the enzymatic antioxidant system, including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), to cope with water stress. Conclusions: Our experiment systematically evaluated the impact of moisture conditions on the growth and development of F. kryloviana seedlings. Physiological and transcriptomic data collectively indicate that adequate water (20%) supply enhances seedling growth and development by reducing ABA levels and increasing α-amylase activity within seeds, thereby boosting sugar metabolism and promoting the growth of seedling, which in turn leads to an improved emergence rate. Considering water management in future cultivation practices may be a crucial strategy for enhancing the successful establishment of F. kryloviana in grassland ecosystems. [ABSTRACT FROM AUTHOR]

Soil surface cover is one of the most critical factors affecting soil water vapor transport, especially in drylands where water is limited, and the water movement occurs predominantly in the form of vapor instead of liquid. Biocrusts are an important living ground cover of dryland soils and play a vital role in modifying near‐surface soil properties and maintaining soil structure. The role of biocrusts in mediating soil water vapor transport during daytime water evaporation and nighttime condensation remains unclear. We investigated the differences in vapor diffusion properties, vapor adsorption capacity, and water evaporation between bare soil and three types of biocrusts (cyanobacterial, cyanobacterial‐moss mixed, and moss crusts) in the Chinese Loess Plateau. Our results showed that the three types of biocrusts had 5%–39% higher vapor diffusivity than bare soil. At the same level of ambient relative humidity and temperature, the initial vapor adsorption rates and cumulative adsorption amounts of the biocrusts were 10%–70% and 11%–85% higher than those of bare soil, respectively. Additionally, the late‐stage evaporation rate of cyanobacterial‐, cyanobacterial‐moss mixed‐, and moss‐biocrusts were 31%–217%, 79%–492%, and 146%–775% higher than that of bare soil, respectively. The effect of biocrusts on increasing vapor transport properties was attributed to the higher soil porosity, clay content, and specific surface area induced by the biocrust layer. All of these modifications caused by biocrusts on surface soil vapor transport properties suggest that biocrusts play a vital role in reshaping surface soil water and energy balance in drylands. Key Points: Biocrusts increase water vapor diffusion properties, water vapor adsorption amount, and cumulative evaporation amountModified soil properties of biocrust are a key factor influencing water vapor fluxReshaped vapor transport properties of biocrust control soil water and energy balance [ABSTRACT FROM AUTHOR]

Introduction: Salinization damages soil system health and influences microbial communities structure and function. The response of microbial functions involved in the nutrient cycle to soil salinization is a valuable scientific question. However, our knowledge of the microbial metabolism functions in salinized soil and their response to salinity in arid desert environments is inadequate. Methods: Here, we applied metagenomics technology to investigate the response of microbial carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling and the key genes to salinity, and discuss the effects of edaphic variables on microbial functions. Results: We found that carbon fixation dominated the carbon cycle. Nitrogen fixation, denitrification, assimilatory nitrate reduction (ANRA), and nitrogen degradation were commonly identified as the most abundant processes in the nitrogen cycle. Organic phosphorus dissolution and phosphorus absorption/transport were the most enriched P metabolic functions, while sulfur metabolism was dominated by assimilatory sulfate reduction (ASR), organic sulfur transformation, and linkages between inorganic and organic sulfur transformation. Increasing salinity inhibited carbon degradation, nitrogen fixation, nitrogen degradation, anammox, ANRA, phosphorus absorption and transport, and the majority of processes in sulfur metabolism. However, some of the metabolic pathway and key genes showed a positive response to salinization, such as carbon fixation (facA, pccA, korAB), denitrification (narG, nirK, norBC, nosZ), ANRA (nasA, nirA), and organic phosphorus dissolution processes (pstABCS, phnCD, ugpAB). High salinity reduced the network complexity in the soil communities. Even so, the saline microbial community presented highly cooperative interactions. The soil water content had significantly correlations with C metabolic genes. The SOC, N, and P contents were significantly correlated with C, N, P, and S network complexity and functional genes. AP, NH4+, and NO3- directly promote carbon fixation, denitrification, nitrogen degradation, organic P solubilization and mineralization, P uptake and transport, ASR, and organic sulfur transformation processes. Conclusion: Soil salinity in arid region inhibited multiple metabolic functions, but prompted the function of carbon fixation, denitrification, ANRA, and organic phosphorus dissolution. Soil salinity was the most important factor driving microbial functions, and nutrient availability also played important roles in regulating nutrient cycling. [ABSTRACT FROM AUTHOR]

Vegetation primarily draws water from soil moisture (SM), with restoration in drylands often reducing SM storage (SMS). However, anomalies have been detected in the Beijing–Tianjin Sand Source Region (BTSSR) of China via the Global Land Data Assimilation System (GLDAS) and Gravity Recovery and Climate Experiment (GRACE). This study quantified the sources of increased SMS in drylands to elucidate the effects of vegetation restoration on SMS. The results indicated the following: (1) In vegetated drylands, 46.2% experienced a significant increase in SMS while 53.8% remained stable; both were positively correlated with the normalised difference vegetation index (NDVI). (2) The increase in SMS was accompanied by a decrease in groundwater storage (GWS), as indicated by the significant correlation coefficients of −0.710 and −0.569 for SMS and GWS, respectively. Furthermore, GWS served as the primary source of water for vegetation. (3) The results of the redundancy analysis (RDA) indicated that the initial vegetation, the driver of the observed trend of increased SMS and decreased GWS, accounted for 50.3% of the variability in water storage. Therefore, to sustain dryland ecosystems, we recommend that future vegetation restoration projects give due consideration to the water balance while concurrently strengthening the dynamic monitoring of SMS and GWS. [ABSTRACT FROM AUTHOR]

The high complexity of the parameter–simulation problem in land surface models over semiarid areas makes it difficult to reasonably estimate the surface simulation conditions that are important for both weather and climate in different regions. In this study, using the dense site datasets of a typical semiarid region over Tibet and the Noah land surface model with the constrained land parameters of multiple sites, an enhanced Kling–Gupta efficiency criterion comprising multiple objectives, including variable and layer dimensions, was obtained, which was then applied to calibration schemes based on two global search algorithms (particle swarm optimization and shuffled complex evaluation) to investigate the site-scale spatial complexities in soil temperature simulations. The calibrations were then compared and further validated. The results show that the Noah land surface model obtained reasonable simulations of soil moisture against the observations with fine consistency, but the negative fit and huge spatial errors compared with the observations indicated its weak ability to simulate the soil temperature over regional semiarid land. Both calibration schemes significantly improved the soil moisture and temperature simulations, but particle swarm optimization generally converged to a better objective than shuffled complex evaluation, although with more parameter uncertainties and less heterogeneity. Moreover, simulations initialized with the optimal parameter tables for the calibrations obtained similarly sustainable improvements for soil moisture and temperature, as well as good consistency with the existing soil reanalysis. In particular, the soil temperature simulation errors for particle swarm optimization were unbiased, while those for the other method were found to be biased around −3 K. Overall, particle swarm optimization was preferable when conducting soil temperature simulations, and it may help mitigate the efforts in surface forecast improvement over semiarid regions. [ABSTRACT FROM AUTHOR]

Soil moisture (SM) is a critical element of the hydrological cycle, land surface processes, and surface energy balance. However, the low spatial resolution of commonly used SM products limits the application of SM in agriculture and eco‐hydrology in cold and arid regions. In this study, the normalized difference soil index (NDSI) and bare soil index (BSI) were added to traditional downscaling factors including land surface temperature, normalized difference vegetation index, digital elevation mode, apparent thermal inertia, Albedo, and temperature vegetation dryness index, as they are more strongly correlated with surface SM in the bare soil‐vegetation alternation zone of such region. Using the random forest algorithm, a downscaling model of SM was constructed for such region. The accuracy of the downscaled SM estimates was validated by comparing them with the original SM data collected from May to September 2021, which is the non‐freezing period of the soil. The findings indicate that the newly added NDSI and BSI have good correlation with SM. Incorporating NDSI and BSI to construct the downscaled model enhances the accuracy by over 19% compared to excluding them, while also providing a more comprehensive representation of SM information. NDSI and BSI can be well applied to the downscaled research of SM in the bare soil‐vegetation alternation zone, which is of great value for the study of eco‐hydrology and agricultural drought monitoring in cold and arid regions. Core Ideas: Adding soil factors improves the downscaling of soil moisture in cold and arid regions.Compared with the traditional model, the improved model showed a significant increase in accuracy.This improved model better characterized soil moisture spatial and temporal variability. [ABSTRACT FROM AUTHOR]

The spatial distribution of soil moisture is a critical determinant for the success of vegetation restoration initiatives in semi-arid and arid regions. The Qilian Mountains, situated within a semi-arid zone in China, have been subject to significant water-induced soil erosion, which has led to extensive restoration activities, predominantly utilizing the species P. crassifolia. However, the interconnections between soil moisture and various land cover types within this region remain unclear, presenting challenges to effective woodland rehabilitation. This study examines the surface soil moisture dynamics in afforested areas with varying ages of plantation to determine the influence of tree planting on the moisture content of the upper soil layer. It investigates the characteristics and temporal patterns of surface soil moisture as the age of the plantation increases. The findings indicate that: (1) soil moisture levels follow a descending sequence from natural forest, through shrubland and grassland, to planted forest and mixed forest, with statistically significant differences observed between natural and mixed forests (p < 0.05); (2) young afforested areas (less than 50 years old) have lower soil moisture levels compared to natural forests, shrublands, or grasslands, and the ecohydrological impacts of afforestation become apparent with a temporal delay; and (3) the analysis using Generalized Additive Mixed Models (GAMM) and the application of Kriging interpolation to determine the spatial distribution of soil moisture reveals that in semi-arid and arid regions, several factors have a pronounced a non-linear relationship with the moisture content of the surface soil. These factors include the duration of afforestation, the position on the lower slope, the presence of shade on the slope, and the scale at which the study is conducted. Therefore, a comprehensive understanding of the dynamics of soil water content is essential to prevent the potential failure of artificially established forests due to inadequate soil moisture in their later stages. [ABSTRACT FROM AUTHOR]

Erosion is a powerful force that has moulded the Earth ever since water has been present on its rocky surface. In its seemingly harmless pursuit, erosion threatens ecosystems, reduces agricultural production, and impacts water quality. When trying to investigate erosion, there is no easy way to identify hotspots, only leaving the possibility of predicting where erosion should be occurring. This study aimed to develop a method to identify erosion using Synthetic Aperture Radar (SAR) images in a process called Coherent Change Detection (CCD). In doing so, it was found that CCD can be used to identify erosion due to rain events; however, false positives were also found due to soil moisture changes. This study used a new method for removing soil moisture effects that utilised the drying out of the soil to map where changes had occurred. This helped limit false positives, but more work is required to ensure soil moisture does not interfere with the results. Field data comprising aerial imagery and soil sampling were collected to improve the SAR processing as well as validate the results. The results of this study indicate the feasibility of developing an erosion analysis system capable of providing near real-time data specifically for arid regions. [ABSTRACT FROM AUTHOR]

Ultisol dry land is characterized by significantly low organic carbon content, an important factor influencing soil water content and physicochemical dynamics. The addition of N fertilizer dissolved in seaweed liquid extract as an enrichment solution can change the character of biochar. Therefore, this study aimed to analyze the characteristics of cogongrass biochar enriched with dissolved N fertilizer in seaweed extract of different species and assess its impact on soil water content in Ultisol. Urea was used as a nitrogen source, and biochar enriched with N fertilizer dissolved in seaweed liquid extract from Kappapychus alvarezii, Sargassum sp., and Ulva lactuca was tested. Biochar dose used was 20% of soil weight with a 10% extract concentration for each type. Furthermore, five-level treatments were tested in a pot experiment, namely (i) without biochar, (ii) biochar unenriched, (iii) enriched with N fertilizer dissolved in K. alvarezii extract, (iv) enriched with N fertilizer dissolved in Sargassum sp. extract, and (v) biochar enriched with N fertilizer dissolved in U. lactuca extract. Each treatment was repeated three times, following a randomized block design. The results showed that cogongrass biochar enriched with N fertilizer dissolved in seaweed extract had a more amorphous surface morphology structure. The proportion of elements and functional groups in cogongrass biochar changed. Enriched biochar increased Ultisol moisture levels, but water holding capacity and retention were lower than the unenriched sample. [ABSTRACT FROM AUTHOR]

Water vapor adsorption on soil, a crucial non-rainfall water resource in arid regions, warrants further experimental investigation, particularly on two typical land surfaces: bare soil and gravel. This study examined the formation characteristics and influencing factors of vapor adsorption in an arid region of Northwestern China. Observations and analyses were conducted on adsorption and evaporation measurements taken by two small weighing lysimeters (SLSs); soil temperature at a depth of 5 cm; surface temperature; relative humidity; and air temperature at a height of 30 cm above the ground from 2019 to 2020. The adsorbed water in this area was more abundant at night and less abundant during the day, with a stable nightly adsorption rate of 0.013 mm/h. Adsorption was more frequent in spring and winter (from January to June and November to December), accounting for about 90% of the total annual adsorption. In 2019 and 2020, the ratio values of adsorption to evaporation were 0.16 and 0.10 for bare soil, and 0.10 and 0.12 for gravel, respectively. Adsorption was more likely to occur when the soil moisture content was less than 13%; the highest adsorption frequency was close to 20% when the RH was between 75 and 95%; low soil temperatures were more conducive to the occurrence of adsorption. The effect of temperature differences (Ta−Ts) on adsorption was stronger than that of relative humidity. The adsorption frequency generally showed a bimodal change with increasing temperature difference, but the effect of temperature differences was less effective for gravel than bare soil. When the relative humidity was high and the temperature difference was weakly positive, the maximum adsorption intensity could reach 0.18 mm/h. [ABSTRACT FROM AUTHOR]

Soil moisture content is an important measure of soil health, and high-precision soil moisture trend analysis is essential for understanding regional ecological quality in the context of climate change, flood monitoring, and water cycle processes. However, in the arid regions of Central Asia, where data are severely lacking, obtaining high-spatial-resolution, continuous soil moisture data is difficult due to the scarcity of stations. Moreover, because soil moisture is easily affected by evaporation time, surface morphology, and anthropogenic factors, mature theoretical models or empirical or semiempirical models to measure soil moisture are also lacking. To investigate the distribution and trend of soil moisture in the Ebinur Lake water, in this study, microwave remote sensing and visible remote sensing data were selected as inputs, and the Global Land Data Assimilation System (GLDAS-2.2) data products were downscaled using the GTWR model, which increased the spatial scale from 27,830 m × 27,830 m to 30 m × 30 m. The phenomena involved in the soil moisture change cycle, spatial distribution, temporal variation, and internal randomness distance were analyzed in the study area through wavelet analysis, Theil–Sen trend analysis, the Mann–Kendall (MK) test, and a variogram. This study obtained high-resolution continuous soil moisture data in the arid and data-scarce region in Central Asia, thus broadening the field of multisource remote sensing analysis and providing a theoretical basis for the construction of precision agriculture in northwest China. [ABSTRACT FROM AUTHOR]

Soil water availability is an essential prerequisite for vegetation functioning. Vegetation takes up water from varying soil depths depending on the characteristics of its rooting system and soil moisture availability across depth. The depth of vegetation water uptake is largely unknown across large spatial scales as a consequence of sparse ground measurements. At the same time, emerging satellite-derived observations of vegetation functioning, surface soil moisture, and terrestrial water storage present an opportunity to assess the depth of vegetation water uptake globally. In this study, we characterize vegetation functioning through the near-infrared reflectance of vegetation (NIRv) and compare its relation to (i) near-surface soil moisture from the ESA's Climate Change Initiative (CCI) and (ii) total water storage from the Gravity Recovery and Climate Experiment (GRACE) mission at a monthly timescale during the growing season. The relationships are quantified through partial correlations to mitigate the influence of confounding factors such as energy- and other water-related variables. We find that vegetation functioning is generally more strongly related to near-surface soil moisture, particularly in semi-arid regions and areas with low tree cover. In contrast, in regions with high tree cover and in arid regions, the correlation with terrestrial water storage is comparable to or even higher than that of near-surface soil moisture, indicating that trees can and do make use of their deeper rooting systems to access deeper soil moisture, similar to vegetation in arid regions. At the same time, we note that this comparison is hampered by different noise levels in these satellite data streams. In line with this, an attribution analysis that examines the relative importance of soil water storage for vegetation reveals that they are controlled by (i) water availability influenced by the climate and (ii) vegetation type reflecting adaptation of the ecosystems to local water resources. Next to variations in space, the vegetation water uptake depth also varies in time. During dry periods, the relative importance of terrestrial water storage increases, highlighting the relevance of deeper water resources during rain-scarce periods. Overall, the synergistic exploitation of state-of-the-art satellite data products to disentangle the relevance of near-surface vs. terrestrial water storage for vegetation functioning can inform the representation of vegetation–water interactions in land surface models to support more accurate climate change projections. [ABSTRACT FROM AUTHOR]

Semi-arid regions are strongly dependent on the rainfall regime. Yet season identification is still ambiguous and clear definitions are lacking regarding which variables and criteria should be used. The objective of this work is to establish a method for hydrological season partitioning in the semi-arid Caatinga biome in northeastern Brazil considering precipitation, soil moisture and vegetation. The following four periods were employed for this purpose: (i) dry–rainy transition, (ii) rainy season, (iii) rainy–dry transition and (iv) dry season. The method was applied to the Aiuaba experimental basin (AEB) from 2003 to 2022. We observed a large inter-annual variability in the duration of seasons and a tendency for the rainy–dry transition season to increase, facts that may indicate changes in the hydrological regime of the region. This novel combination of precipitation, soil moisture, and vegetation data for identification of hydrological seasons within the Caatinga biome allows a detailed seasonal hydrological behaviour analysis. [ABSTRACT FROM AUTHOR]

In environmentally sensitive areas, especially the arid and semi-arid regions, the greening stability process and its influencing factors can directly affect the sustainable development of the ecological environment. In this study, multi-source remote sensing data such as land use/cover data, MODIS NDVI, and soil moisture, methods such as stability index, vegetation quantitative remote sensing, and Geodetector were employed to analyze the sustainability of the greening process in the Mu Us Sandy in 2000–2020, which were viewed from three aspects: changes in stability of land use types and function, soil moisture change and influencing factors on greening stability. The results showed that, (1) From the stability of land use types, continuous stable ecological land accounted for more than 50%, showing that decreased from northwest toward southeast. (2) From the functional stability, NDVI showed a fluctuated growth (0.035/a), with an increasing distribution pattern from northwest to southeast. Additionally, Vegetation changes were unstable and concentrated in the western part of the study area (OtogBanner and Otog Front Banner), while the eastern part was stable, in which vegetation improvement took the main position. Moreover, mobile dunes almost disappeared, and semi-fixed dunes decreased and gradually shrank to the west of the sandy area, while fixed dunes soared and were concentrated in the middle of the sandy land. (3) From the soil moisture change, soil moisture at different underground depths showed an overall increasing trend, but the deep soil moisture was higher than the shallow, and spatial distribution varied greatly. (4) From the influencing factors, natural factors significantly influence greening stability, among which precipitation had a particularly profound impact, and interactions with other natural and social factors were higher explanatory. The paper aims to explore whether the ecological environment is developing in a good and orderly direction in the Mu Us Sandy Land, and the potential factors that cause its changes, to provide a theoretical basis for scientific governance in the Mu Us Sandy Land and other arid and semi-arid areas in the future. [ABSTRACT FROM AUTHOR]

Significant temporal and spatial variability in soil moisture (SM) is observed during the warm season in China and its surrounding regions. Because of the existence of two different evapotranspiration regimes, i.e., soil moisture-limited and energy-limited, averaging the land–atmosphere (L–A) coupling strength for all soil wetness scenarios may result in the loss of coupling signals. This study examines the daytime-only L–A interactions under different soil moisture conditions, by using two-legged metrics in the warm season from May to September 1981–2020, partitioning the interactions between SM and latent heat flux (SM–LH, the land leg) from the interactions between latent heat flux and the lifting condensation level (LH–LCL, the atmospheric leg). The statistical results reveal large regional differences in warm-season daytime L–A feedback in China and its surrounding areas. As the soil becomes wetter, the positive SM–LH coupling strength increases in arid regions (e.g., northwest China, Hetao, and the Great Indian Desert) and the positive feedback shifts to the negative one in semi-arid/semi-humid regions (northeast and northern China). The negative LH–LCL coupling is most pronounced in wet soil months in arid regions, while the opposite is true for the Tibetan Plateau. In terms of intraseasonal variation, the large variability of SM in north China, the Tibetan Plateau, and India due to the influence of the summer monsoon leads to the sign change in the land segment coupling index, comparing pre- and post-monsoon periods. To further examine the impact of SM anomalies on L–A coupling and to explore evapotranspiration regimes in the North China Plain, four sets of sensitivity experiments with different soil moisture levels over a period of 10 years were conducted. Under relatively dry soil conditions, evapotranspiration is dominated by the soil moisture-limited regime with positive L–A coupling, regardless of external moisture inflow. The critical soil moisture value separating a soil moisture-limited and an energy-limited regime lies between 0.24 m3/m3 and 0.29 m3/m3. Stronger positive feedback under negative soil moisture anomalies may increase the risk of drought in the North China Plain. [ABSTRACT FROM AUTHOR]

The intensity and duration of precipitation play an important role in surface runoff processes. A hilly area may have more complicated runoff processes. In this study, the characteristics of annual rainfall from 1987 to 2023 in the Taihang Mountain were obtained by the Pearson-III frequency curve, homogeneity and MK test. Four surface runoff generation processes during 2014 to 2023 were monitored. The contribution of rainfall to changes in runoff were quantified based on the double cumulative curve method. Results showed that for the last decade, a significant upward trend in the frequency of moderate and heavy rainfall events. The spatial variability of rainfall in the Taihang Mountain and the influence of elevation are both smaller when the rainfall during 24 h is lower than 50 mm. The two surface runoff processes in 2016 and 2023 were typical runoff storm runoff. The two surface runoff processes in 2021 were runoff generation under saturated condition. For runoff generation under saturated condition, the contribution of rainfall was only 58.17%. While when the runoff coefficient was greater than 0.5, the surface runoff generating processes were entirely determined by rainfall. This study suggested that for semi-arid regions, where rainfall is unevenly distributed over the seasons, more soil water is needed to maintain local and downstream water demand during the non-rainy season. [ABSTRACT FROM AUTHOR]

Shrubland is an important type of vegetation in the semi-arid region of the western Loess Plateau, and it is of great value to the maintenance of biodiversity and soil and water conservation. Equally, there may be significant differences in the level of diversity and the community assembly patterns across different types of shrublands (desert, alpine, and secondary shrublands). This study aimed to reveal the diversity and the community assembly patterns of different types of shrublands and the environmental explanations for these by using a taxonomic and phylogenetic analysis approach, as well as by considering soil and climate factors. The diversity level of the desert shrublands was low, and the habitats of the three types of shrubland were significantly different. Precipitation may be the main environmental factor driving the variation in and diversity of these types of shrubland. All three types of shrubland were strongly affected by environmental filtering and competitive exclusion, and their community assembly patterns were similar. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate the response of leaf area index and forage productivity of Lotus corniculatus clover genotypes with two different soil moisture contents under shade netting conditions. A randomized experimental block design in a split plot arrangement with three replicates was used. The large plots were soil moisture contents: optimum (OSMC: 26 % ± 1.5) and suboptimal (SSMC: 22 % ± 1.5); and the small plots were L. corniculatus accessions: 255301, 255305, 202700, 226792, and the bird's-foot trefoil (Estanzuela Ganador) variety. The variables measured were leaf area index (LAI), dry matter biomass production (DM) (g plant-1), dry forage increase rate (DFIR) (g plant-1 d-1), and leaf-to-stem ratio (L/S), plus the climatic variables of temperature (°C) and relative moisture (%) in the shade net. Accession 255305 was the best responder in LAI, DM, and DFIR, with values of 3.2, 94.9 g plant-1, and 0.30 g plant-1 d-1, respectively, with OSMC; while the bird's foot trefoil had the best response in LAI with SSMC. There were no differences (P=0.05) between the genetic materials evaluated in DM and DFIR, with average values of 82.4 g plant-1 and 0.26 g plant-1 d-1, respectively. Accessions 255301 and 226792 were the best L/S ratio with values of 2.9 and 2.5, respectively. In general, the best productive performance in terms of DM was obtained in spring, summer, and summer-autumn, with values of 17.5, 11.7, and 17.7 g plant-1, respectively. [ABSTRACT FROM AUTHOR]

Drought is a powerful natural hazard that has significant effects on ecosystems amid the constant threats posed by climate change. This study investigates agricultural drought in a semi-arid Mediterranean basin through the interconnections among four indices: precipitation (meteorological reanalysis), vegetation development, thermal stress, and soil water deficit (remote sensing observations). While drought seems to be a clear concept with effective assessment tools (e.g., SPI and SPEI), the definition of drought periods is blurrier. This article examines the main drivers of agricultural drought, precipitation, soil moisture deficit, incipient vegetation development, and rising soil surface temperature. Their temporal connections in various agrosystems of the basin and the determination of drought periods by revisiting the run theory were investigated. The Pearson correlations at different spatial scales showed a medium to low level of agreement between the indices, which was explained by the geographical heterogeneity and the climatic variability between the agrosystems within the basin. It was also shown that the cascade of impacts expected from lower precipitations was revealed by the cross-correlation analysis. The connection between precipitation deficit and vegetation remains significant for at least one month for most pairs of indices, especially during drought events, suggesting that agricultural drought spells can be connected in time through the three or four selected indices. Short-, mid-, and long-term impacts of precipitation deficiencies on soil moisture, vegetation, and temperature were revealed. As expected, the more instantaneous variables of soil moisture and surface temperature showed no lag with precipitation. Vegetation anomalies at the monthly time step showed a two-month lag with a preceding effect of vegetation to precipitation. Finally, the determination of drought events and stages with varying thresholds on the run theory showed large variability in duration, magnitude, and intensity according to the choice of both normality and dryness thresholds. [ABSTRACT FROM AUTHOR]

Water resource management scenarios have become more crucial for arid to semi-arid regions. Their application prerequisites rigorous hydrological modelling approaches since data are usually exposed to uncertainties and inaccuracies. In this work, Soil Water Assessment Tool (SWAT), an open source semi-distributed, continuous-time, process-based physical hydrological model is used to model hydrological processes and eventually calculate groundwater recharge estimations in Seybouse basin, Northeast Algeria. The model uses estimated rainfall to calibrate the model with observed discharge from hydrometric stations. Model calibration and validation are performed over four hydrometric stations located in the basin. Uncertainty analysis and sensitivity analysis supported the calibration period. SUFI-2 algorithm is used for uncertainty estimations along with a global sensitivity analysis prior to calibration simulations. Simulated flood hydrographs showed generally good accuracy with few misfits on the peaks. The model obtained satisfactory and consistent calibration and validation results for which the Nash score varied from 0.5 to 0.7 for calibration and from −0.1 to 0.6 for validation and R2 from 0.6 to 0.7 for calibration and 0.03 to 0.8 for validation. Moreover, estimated water budget values show strong similarities with the observed values found in the literature. The present work shows that the rigorously calibrated and validated SWAT model can simulate hydrological processes as well as major high and low flows using estimated rainfall data. [ABSTRACT FROM AUTHOR]

• Causality models were applied to discover ecosystem causal networks. • Growing season temperature dominated changes in ecosystem structure and function. • Only weak causal links existed between ecosystem structure and function. • Relative causality-driven intensities were identified. The understanding of the interplay between the environment, ecosystem structure, and function is crucial for effectively managing ecosystems in the face of climate change and environmental disturbances. Numerous observations and simulation experiments relying on correlation analysis have yielded the conclusion that environmental factors can directly or indirectly affect ecosystem community structure and function. However, the limitations of traditional ecological approaches lie in their inadequate control over confounding factors, thus hindering our comprehensive understanding of the true causal relationships. Our study aims to address these limitations and obtain a more accurate picture of causality about environment, ecosystem structure and function within a long-term time series data of an ecosystem. Here, utilizing a 31-year dataset of typical temperate grassland ecosystems, we developed an advanced causal discovery model and further enhanced it to effectively identify the causal network within the ecosystem, while also quantifying the intensity of causal pathways connecting the environment, ecosystem structure, and function. We found that the primary driver for changes in ecosystem structure and function was the temperature during the growing season, with soil water content being the secondary factor. However, there was only a weak causal relationship between ecosystem structure and gross primary productivity (GPP), which was mediated by eurytopic xerophyte plants. These findings challenge the conventional notion that precipitation is a key driver of changes in ecosystem carbon fluxes, highlighting the importance of plant-available water in regulating ecosystem structure and function. Our results suggest that the effects of global warming and severe droughts on plant growth and carbon sequestration capacity necessitate significant attention and further mitigation measures in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Water scarcity and water-related soil erosion are severely exacerbated by inappropriate human activities and global climate change. Hence, to find a suitable technology to mitigate drought and soil erosion, three consecutive field experiments were conducted to explore the impact of ridge-furrow cropping with biochar amendment on soil water storage, runoff, sediment yield, soil nutrient losses, alfalfa (Medicago sativa L) fodder yield, crop water productivity (WP c), and economic benefit from 2019 to 2021. This experiment was conducted in a split-plot design, taking biochar amendment patterns (no biochar amendment and biochar amendment at a rate of 3× 104 kg ha−1) as a main plot and ridge-furrow technologies (traditional planting, open-ridging, and tied-ridging) as a split-plot. The combination of biochar amendment with ridge-furrow technology, especially tied-ridging technology, increased soil water storage, and captured runoff, sediment, and related soil nutrient losses, consequently increasing alfalfa fodder yield, WP c , and income. During this study, compared to traditional planting, open-ridging depicted an increase in soil water storage by a range of 9.8–39.6 mm, an alfalfa fodder yield boost ranging from 9.8% to 38.6%, and a WP c increase ranging from 0.1 to 16.5 kg ha−1 mm−1. On the other hand, tied-ridging showed greater improvements with soil water storage increasing by 29.1–65.1 mm, alfalfa fodder yield growing by 11.6–44.4%, and WP c advancing by 0.9–17.5 kg ha−1 mm−1. The mean decrease in runoff, sediment, and nutrients (total nitrogen, total phosphorus, and organic matter) loss for open-ridging was 17.9%-37.7%, 46.4%-75.5%, and 40.4%-75.3%, respectively, while for tied-ridging, it was 22.3%-55.5%, 62.1%-87.6%, and 49.0%-87.3%, respectively. Compared to no biochar amendment, soil water storage, alfalfa fodder yield, and WP c for biochar amendment increased by 9.1%-20.4%, 5.8%-52.7%, and 4.6–7.8 kg ha−1 mm−1, respectively, while runoff, sediment, and nutrients loss for biochar amendment decreased by 32.2%-40.9%, 25.5%-55.5%, and 35.9%-53.3%, respectively. Structural equation modeling analysis indicated that the significant direct effect of biochar amendment and ridge-furrow technology on WP c was 0.20 and 0.62, respectively, whereas the significant direct effect of runoff and actual crop evapotranspiration on alfalfa fodder yield was −0.40 and 0.94, respectively. Tied-ridge cropping combined with biochar addition was a highly suggested approach for addressing soil erosion and enhancing alfalfa fodder yields in the Loess Plateau in China. This technology could mitigate soil water scarcity and soil erosion, and give farmers the confidence to invest in this technology in dryland regions. • Ridge-furrow technology with biochar amendment reduced soil erosion. • Ridge-furrow technology with biochar amendment increased crop yield. • Biochar amendment and ridge-furrow technology had a direct effect on water use efficiency. • Runoff and evapotranspiration had a direct effect on alfalfa fodder yield. • Tied-ridge cropping with biochar amendment was recommended. [ABSTRACT FROM AUTHOR]

[Display omitted] • Moss biocrusts show significant temporal variability in greenness. • Moss biocrust greenness increases 48% in wet season compared to dry season. • Climatic factors (moisture, humidity, and wind) influence greenness more than soil. • Biocrust greenness correlates positively with biocrust gross primary productivity. • Biocrust greenness serves as a reliable indicator for biocrust carbon-fixation rates. Biocrusts are common living covers found across drylands worldwide, and their photosynthesis substantially contributes to carbon input in these ecosystems. However, direct monitoring of biocrusts' photosynthetic carbon fixation is challenging due to their scattered distribution, dark pigments, and lower CO 2 exchange rate. Current studies have limited monitoring frequency and the results are difficult to extend to a broader spatial scale. Greenness typically functions as an indicator of both vegetation cover and plant photosynthesis. Monitoring biocrust greenness is expected to be able to provide insights into their environmental responses and estimate carbon fixation rates, particularly for moss biocrusts. Here, we monitored greenness, soil moisture and temperature, and gross primary productivity (GPP) of moss biocrusts, as well as climatic factors over two years in the northern China's Loess Plateau. The results indicated that moss biocrust greenness was highly sensitive to changing environmental conditions and exhibited significant temporal variability. Moss biocrust greenness exhibited a notably higher value in wet season (0.384) than in dry season (0.259). According to these greenness values, we proposed moss biocrust activity and classified it into high (>0.403), medium (0.334–0.403), low (0.271–0.333), and dormancy (<0.270). Soil moisture, relative humidity, and wind speed were the three main determinates of moss biocrust greenness. Higher soil moisture and relative humidity were linked to increased greenness, whereas elevated wind speed led to a reduction. In dry seasons, soil moisture contributed 23.4 % to the variation in moss biocrust greenness, while in wet seasons relative humidity contributed 16.1 %. A significant and positive correlation between moss biocrust greenness and GPP was found, and annual GPP prediction based on greenness using machine learning performed well. Our study highlights the significance of moss biocrust greenness and their potential as indicators for moss biocrust photosynthetic carbon fixation rates and possibly other ecological functions in drylands. [ABSTRACT FROM AUTHOR]

The traditional classification of drought events into seasonal and flash types oversimplified the complexity and variability of global drought phenomena, limiting a deeper understanding of drought characteristics and their impacts on vegetation. To address this issue, soil moisture percentile methods and the Soil Moisture Anomaly Percentage Index (SMAPI) were employed to create time series for flash drought (FD) and seasonal drought (SD) events globally from 1981 to 2020. A novel categorization framework was proposed to subdivide the two basic drought categories into eight distinct drought types using a set relationship identification method. The results showed fluctuating trends in the frequencies of Independent FD and Inclusion FD, which declined rapidly after 2011 at rates of 0.05 and 0.04 times/year, respectively. Independent FD frequency was highest in humid areas and decreased with increasing aridity. The spatial distributions of Inclusion FD and SD were similar, with both frequencies highest in extremely arid areas and decreasing with increasing humidity. The frequency of Independent SD, which peaked in semi-arid areas, increased significantly after 2011 at a rate of 0.01 times/year. The occurrence of FD evolving into SD or emerging at the end of SD was rare, with a global average of 0.46 events/decade and little spatial variation. Between 1981 and 2020, FD showed a U-shaped trend in drought duration, while SD showed no clear pattern. The duration of FD showed little difference across arid and humid zones, but the duration of SD decreased significantly with increasing humidity. Vegetation responses to drought varied, with arid regions showing longer response time compared to humid regions. A positive correlation between temperature and solar-induced chlorophyll fluorescence (SIF) during droughts was observed, while precipitation generally showed a negative correlation with SIF. Radiation had a minimal effect on SIF during droughts. The study offered a comprehensive categorization of drought events, enhancing our understanding of their spatiotemporal characteristics and vegetation responses on a global scale. • Global eight drought types were identified using a new classification framework. • The spatio-temporal patterns of eight drought types globally were examined. • Vegetation response to droughts across various wet and dry regions were detected. • The meteorological conditions associated with SIF changes in drought was analyzed. [ABSTRACT FROM AUTHOR]

• Sensitivity of dust emissions to wind's variations is higher than those of vegetation and soil moisture. • The residual effect weakens the sensitivity of dust emissions to driving factors. • Key driving factor of dust emissions is spatially differentiated in Earth's main drylands. The identification of driving factors that contribute to dust emissions holds great significance on studying global climate change. In the present study, we constructed a new index, Dust Sensitivity Index, which allowed us to identify the sensitivity of dust emissions responding to variations in driving factors over 2003–2017 in Earth's main drylands. We found that dust emissions were sensitive to driving factor variability in eastern Brazil, the southern drylands of the Sahel, eastern Africa, eastern Australia and parts of northern Eurasia, where the aridity index (AI) is relatively high. The main factor affecting the DSI varies geographically over the Earth's main dryland regions. In total, wind speed made the largest relative contribution to DOD sensitivity (11.3%), followed by soil moisture (10.8%) and vegetation (10.4%). In addition, wind, vegetation, and soil moisture interact to impose complex and varying limitations on dust activity. 39.3% of the Earth's main drylands were limited by vegetation, 31.2% by wind and 29.5% by soil moisture. Our study also demonstrates that the residual effects of previous dust-driving factors have impacts on contemporary conditions. We found that regions characterized by lower DSI values displayed the most prominent residual effects in general. [ABSTRACT FROM AUTHOR]

Evapotranspiration (ET) serves as a pivotal metric for studying ecohydrological processes. Its dynamics are intricately linked to the interplay among water balance, energy balance, and land use. However, the precise estimation of ET at a regional scale, coupled with a comprehensive understanding of its response to changes in water, heat, and vegetation factors, presents an ongoing challenge. In this study, we assessed the necessity to refine soil evaporation simulations in arid and semiarid regions. Subsequently, we introduced the random forest algorithm to optimize the soil evaporation module of the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model to enable a more accurate prediction of ET. Then, we quantitatively explored the correlation between ET and pertinent factors, such as soil moisture, solar radiation, and the normalized difference vegetation index (NDVI) in the Inner Mongolia section of the Yellow River Basin (IMSYRB), which is a typical arid and semiarid region. The findings underscore that soil evaporation is the predominant constituent of ET in the IMSYRB. Moreover, soil moisture, as opposed to relative humidity, better represent the near-surface moisture conditions within the study area. The refined model (PT-JPL-RF) exhibited enhanced simulation performance at both individual stations and in the overall region for ET. Furthermore, the application of the PT-JPL-RF model for scrutinizing the spatiotemporal ET variations in the study area revealed an average ET of 250 mm over the past four decades. Since 1982, a fluctuating upward trend of 0.99 mm/year has been observed. Spatially, ET exhibits an eastward distribution, with elevated values in the eastern sectors compared to those in the western regions, particularly in the Big Black River Basin (296 mm). Vegetation was the primary factor influencing ET variations in the IMSYRB, contributing to an annual increase by 1.58 mm. These findings demonstrate the benefits of integrating machine learning algorithms with physical models and provide a practical example for accurately simulating and predicting ET across diverse regions. • Examined the need to enhance PT-JPL model within arid and semiarid regions. • Soil moisture better reflected regional humidity than relative humidity. • Improved evapotranspiration simulations by merging PT-JPL and Random Forest models. • Boosted evapotranspiration simulation accuracy by 7.9% with the hybrid model. • Vegetation index contributed most to evapotranspiration, reaching 1.79 mm/year. [ABSTRACT FROM AUTHOR]

Soil salinization exerts a severe impact on environmental degradation that threatens the structure and ecological functions of lake wetland. To study the characteristics of soil water-salt in the typical plant communities in the ecological buffer zone of the arid lake wetland, three zones were selected lakeshore as the starting point in Stone House, Bird Island, and Duck Bay management stations of Lake Ebinur wetland, August 2016 and 2017. These zones, including the waterward radiation zone, the water level variation zone, and the landward radiation zone, to investigate the variation patterns of soil water-salt in different zones and soil depths (0–5, 5–10, 10–20, 20–40, 40–60 cm). The results showed that: the soil pH in different plant communities in zones were all alkaline with weak varianbility. Soil moisture and total salt content were moderately variable. According to the Xinjiang saline-alkali classification standards, soils in the three zones were classified as non-salinized soil to mildly salinized soil, heavily salinized soil to saline soil, and non-salinized soil to heavily salinized soil, respectively; soil pH and moisture content in different plant communities of the zones tended to increase along with soil deepens and salt content decreased. The differences in soil pH and moisture between different soil profiles in the same zone were not so significant, but the differences in total salt content were bigger. The soil moisture and total salt content among different zones within the same soil profile remained prominent. The relationship between soil pH, moisture content, and total salt content in waterward radiation zone and water level variation zone was complex, showing an unclear pattern. In the landward radiation zone, soil pH and total salt content were negatively correlated with moisture, while soil pH was positively correlated with total salt content. The study demonstrated that the changes in soil water-salt in Lake Ebinur Wetlands were mainly influenced by structural factors (microtopography, soil characteristics, vegetation, parent material, hydrology), followed by random factors (irrigation, soil improvement, cultivation practices, and human activities). [Display omitted] • Surface soil salts aggregation, deep pH and moisture aggregation in lake ecological buffer zones. • Increasing salts and decreasing trends in pH and moisture in watershed to land transition soils. • Soil water-salt in ecological buffer zones in arid regions is influenced by structural factors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vegetation type, soil characteristics and stand structure all had effects on soil water content. • Shallow layer soil water content (0–60 cm) of degraded poplars was significantly higher than that of healthy poplars. • Sand content was the dominant factor affecting SWC of healthy poplars, while SWC of degraded poplars was mainly affected by canopy closure. • The relationship between SWC and poplar degradation was dynamic mutual feed-back. Large-scale afforestation poses threats to water resources security in water-limited areas, and the water availability affects plants growth and mortality. Shelterbelts degradation inevitably causes stand structure changes, which affect the soil water content (SWC). In this study, we used high-density sampling method to study the Populus simonii Carr stands located in the only 6.3 km2 Boluosu forest farm in the semiarid region of northern China, including healthy and degraded stands, and cropland and grassland plots as controls. The vertical profiles (0–200 cm) of SWC was measured in each plot in 73 selected locations, soil characteristics and stand structure of typical Populus simonii Carr were measured. The main purpose was to analyze the impact of the Populus simonii Carr degradation on the soil water vertical variation and to combine this information with stand structure and soil characteristics to analyze all their effects together. The results showed that compared with cropland (254.7 ± 14.96 mm) and grassland (237.9 ± 12.62 mm), the soil water storage of healthy Populus simonii Carr (198.91 ± 8.47 mm) decreased by 21.9 % and 16.4 %, respectively. The shallow layer (0–60 cm) SWC increased significantly with degradation degree (P < 0.01), and the shallow layer soil water storage of the degraded Populus simonii Carr (79.7 ± 4.5 mm) was 20 mm (33.5 %) higher than that of healthy Populus simonii Carr (59.7 ± 2.8 mm). There were significant differences in the dominant factors of SWC between healthy and degraded Populus simonii Carr. For healthy Populus simonii Carr , sand content was the dominant factor controlling the SWC and explained 54.6 % of the variations in shallow layer SWC. For degraded Populus simonii Carr , canopy closure was the main factor controlling the SWC and explained 63.3 % of the variations in shallow layer SWC. The study showed that should prioritize plantations with lower water consumption for future afforestation. Additionally, considering the shallow soil water recovery after shelterbelt degradation, the results could provide a scientific support for sustainable management of plantations. [ABSTRACT FROM AUTHOR]

The importance of uptake of atmospheric methane (CH 4) in dry Arctic soils for the total Arctic CH 4 budget is unresolved. This is partly due to lack of data on the spatial variability of net CH 4 consumption and understanding of the main process drivers. We measured net CH 4 consumption in Arctic and subarctic landscapes located in in Disko Bay Area and Kangerlussuaq in Western Greenland and in the St. Elias Range in the Yukon, Canada, respectively. Our aim was to characterize the in situ spatial variability of net CH 4 uptake in hitherto unexplored Arctic dry upland soils to explore possible limits and environmental drivers across the Arctic geodiversity. Furthermore, we sampled soil for incubation experiments to investigate how net CH 4 oxidation responded to changes in soil moisture in contrasting geomorphic settings and parent geological parent materials. We used a laser-based fast deployable chamber system for flux measurements. All studied sites were net sinks of atmospheric CH 4 with an average flux −7.5 ± 5.6 μmol CH 4 m-2h−1, that are in the upper range of reported net CH 4 uptake fluxes in similar soils of the Arctic. The large observed spatial variability within all studied sites (coefficient of variation 50 – 120 %) highlights the need for careful research design allowing for many spatial replicates to achieve representative values. Sites with an active geomorphic environment (abrasion plateau, riverbeds, mountain tops) generally had lower than average net CH 4 uptake. Our incubation studies revealed that subsurface CH4 oxidation is the main driver of net surface-atmosphere exchange and that net CH 4 oxidation in these layers responded more to changes to soil moisture than in near surface layers. Our study shows surprisingly similar flux magnitudes of net CH 4 uptake across widely different landscape forms and geologic parent material, but responding similarly to soil hydrology and geomorphic disturbance, indicating global controls on the net CH 4 oxidation in these dry upland environments. [ABSTRACT FROM AUTHOR]

Sustainable development faces the crucial challenge of safeguarding water-related ecosystem services, particularly in arid regions. However, scale-dependent interactions and their influencing factors remain unclear. This study addresses this local gap on the regional level by focusing on ecologically vulnerable mountain areas, employing a comprehensive quantitative and spatial analysis approach, utilizing Spearman coefficient, trade-off/synergy index, and trade-off/synergy criterion, to examine water-related ecosystem services interactions across scales in arid area. Additionally, a Geographical detector was used to identify dominant natural and human activity factors. Finally, we determined ecologically optimal and worst areas and proposed spatial planning and management recommendations for ecological protection and restoration. Key results indicate that: (1) From 1995 to 2015, water yield and nutrient delivery ratio exhibited a declining trend, while soil retention showed an increasing trend, with the weakest nutrient delivery ratio function in the reserve. (2) At the grid scale, there were 2 trade-offs among water-related ecosystem services in 1995, which decreased to 1 trade-off in 2005 and 2015. The synergistic was most prominent near Qinghai Lake, while the trade-off was most obvious in the western mountainous areas. Conversely, the county scale demonstrated synergy. (3) NDVI, slope, and precipitation dominantly influence the spatial heterogeneity patterns of soil retention_water yield, soil retention_nutrient delivery ratio, and water yield_nutrient delivery ratio, respectively, with natural factors outweighing human activities in impacting water-related ecosystem services. This study contributes to the improvement and optimization of ecological environment management decisions. • Examines trade-offs among water-related ecosystem services at varying scales. • County scale may obscure trade-offs observable at raster scale. • Stronger correlations among water-related ecosystem services with larger scales. • Significant trade-off is identified between soil retention_nutrient delivery ratio. • Natural factors drive dominant water-related ecosystem services variations. [ABSTRACT FROM AUTHOR]