Loess Plateau Region Research Articles

Method for Extracting Corn Planting Plots in the Loess Plateau Region Based on the Improved HRNet and NDVI Time Series

Method for Extracting Corn Planting Plots in the Loess Plateau Region Based on the Improved HRNet and NDVI Time Series

Analysis of Spatial and Temporal Changes in Vegetation Cover and Driving Forces in the Wuding River Basin, Loess Plateau

Vegetation cover in the Loess Plateau region is an important component of ecological protection in the Yellow River Basin, and this study provides a scientific reference for further vegetation restoration. Based on Landsat images and related data, we utilized the dimidiate pixel model and Geodetector method to study the vegetation cover in the Wuding River Basin from 2000 to 2022. The results indicated the spatial and temporal distribution of the vegetation cover and its changes over the study period. Additionally, the driving factors influencing its spatial changes were also uncovered. We also propose a land use shift vegetation cover contribution formula to quantify the effect of land type change on the FVC. The study showed that (1) the overall vegetation cover of the watershed increased significantly, and the FVC showed an increasing trend from 2000 to 2013 and a slow decline from 2013 to 2022, with the gradual transformation of low-graded FVC into a higher graded one. (2) The FVC increased spatially from northwest to southeast, and the trend of future changes is mainly decreasing. (3) The strongest explanatory power for the FVC change is the land use type and its interactive combination with rainfall. (4) The conversion of grassland to cropland contributes the most to the vegetation cover at 1.52%, and the increase in the cropland area is more conducive to the increase in the vegetation cover.

Building smallholder-adapted climate-resilient systems: Evidence from China's apple farms

Climate change affects crop production globally, and cash crops are particularly vulnerable, which may threaten human livelihoods. However, limited attention has been paid to building climate-resilient systems, especially for smallholders producing cash crops such as apples, which account for 13% of the global fruit consumption. In this study, we developed a smallholder-adapted climate-resilient system (SA-CRS) conceptual framework and applied this in an empirical assessment of the adaptation of smallholder apple farmers (SAFs) to the risk of low temperature during flowering (LTF) in China. The results show that average daily minimum temperatures have decreased by 1.77 °C, and the LTF hazard probability has increased by 6.1% from 1999 to 2018. Approximately 96.4% of the SAFs in the study regions reported LTF impacts in 2018, and 29.8% experienced apple yield losses averaging 16.43 t/ha. Notably, most SAFs in the Loess Plateau region with poor SA-CRS reported apple yield reduction. Such adverse effects lowered economic returns and further prevented SAFs from adopting adaptive measures, resulting in a vicious circle. By contrast, an effective SA-CRS in the Bohai Bay region has greatly reduced the risks, and a positive economic return further incentivizes the adoption of further adaptive measures, creating a virtuous circle. Our study showed that to achieve an effective SA-CRS, a market-oriented nexus approach is required that integrates an institutional price-enhancing mechanism (contributing 84% to smallholder decision-making), an organizational production-support system, and a public extension system tailored to the needs of SAFs.

Quantitative analysis of runoff alteration based on the Budyko model with time-varying underlying surface parameters for the Wuding River Basin, Loess Plateau

The evolution of basin runoff is related to water resource development and the safety of the ecological environment. This study took the Wuding River Basin (WRB) as the study area, using trend analysis, significance tests, and the elasticity coefficient method to identify the impact factors of basin runoff change. Based on four Budyko equations and stepwise multiple linear regression analysis, a fitting equation of time-varying underlying surface parameters that considers various factors was constructed, and the contribution rates of climatic and vegetation changes to runoff change were quantified. The WRB Runoff decreased significantly (p ≤ 0.05) at a rate of −0.175 mm∙a−1 during 1982–2019, and precipitation and potential evapotranspiration showed significant increasing trends. Sensitivity of runoff changes to time-varying underlying surface parameters, precipitation, and potential evapotranspiration decreased sequentially. Simulation accuracies of the Budyko equations for runoff changes were significantly improved with time-varying underlying surface parameters. The change of vegetation factors was the dominant factor leading to runoff reduction, and the impact of climatic factors on the runoff change was characterized by “promotion first, inhibition later.” The results provide a reference for water resource development and utilization and the hydrological–ecological response in the Loess Plateau region under a changing environment.

Combining slow-release fertilizer and plastic film mulching reduced the carbon footprint and enhanced maize yield on the Loess Plateau

Agricultural practices significantly contribute to greenhouse gas (GHG) emissions, necessitating cleaner production technologies to reduce environmental pressure and achieve sustainable maize production. Plastic film mulching is commonly used in the Loess Plateau region. Incorporating slow-release fertilizers as a replacement for urea within this practice can reduce nitrogen losses and enhance crop productivity. Combining these techniques represents a novel agricultural approach in semi-arid areas. However, the impact of this integration on soil carbon storage (SOCS), carbon footprint (CF), and economic benefits has received limited research attention. Therefore, we conducted an eight-year study (2015–2022) in the semi-arid northwestern region to quantify the effects of four treatments [urea supplied without plastic film mulching (CK-U), slow-release fertilizer supplied without plastic film mulching (CK-S), urea supplied with plastic film mulching (PM-U), and slow-release fertilizer supplied with plastic film mulching (PM-S)] on soil fertility, economic and environmental benefits. The results revealed that nitrogen fertilizer was the primary contributor to total GHG emissions (≥71.97%). Compared to other treatments, PM-S increased average grain yield by 12.01%–37.89%, water use efficiency by 9.19%–23.33%, nitrogen accumulation by 27.07%–66.19%, and net return by 6.21%–29.57%. Furthermore, PM-S decreased CF by 12.87%–44.31% and CF per net return by 14.25%–41.16%. After eight years, PM-S increased SOCS (0–40 cm) by 2.46%, while PM-U decreased it by 7.09%. These findings highlight the positive effects of PM-S on surface soil fertility, economic gains, and environmental benefits in spring maize production on the Loess Plateau, underscoring its potential for widespread adoption and application.

Research on the fugitive soil dust emission inventory in Western China based on wind erosion equation parameter optimization

The Wind Erosion Equation, currently one of the primary methods for estimating fugitive soil dust emission inventory, is influenced by several factors. Taking the convergent areas of the Tibet Plateau, Loess Plateau, and Qinba Mountains in Western China, we have optimized the climate factor using the WRF model driven by ERA5 reanalysis data. Additionally, we have modified the vegetation cover factors via normalized difference vegetation index and considered the impacts of the land use and cover change. Subsequently, other factors were allocated utilizing geographic information system, and the grid-based fugitive soil dust emission inventory for the study area for 2019 was derived through calculation. Based on the climate factor and vegetation cover factor, we have come up with the monthly allocation coefficients. The study has revealed the following findings: (1) Climate factors are unevenly distributed throughout the focused region, with the Loess Plateau showing the highest value, followed by the Tibet Plateau and the Qinba Mountains. There are also significant variations in the distribution of these factors among municipalities and counties; (2) The order of vegetation cover factor, primarily influenced by regional background as well as agricultural and pastoral activities, in the Loess Plateau, Tibetan Plateau and Qinba Mountains, is consistent with that of the wind erosion index; (3) In 2019, fugitive dust emissions from total suspended particles, PM10, and PM2.5 reached 9835.9, 2950.8, and 491.8 kt/a, respectively. The Loess Plateau exhibited the highest emission intensity due to factors such as low vegetation coverage, precipitation, high wind speed and wind erosion index; (4) Climate factor and vegetation cover factor are the primary factors influencing the monthly allocation coefficients. In 2019, the highest monthly fugitive dust emissions were estimated in April, accounting for approximately 36.21% of the total. The second and third-highest were found in August and June, respectively. This phenomenon can be explained climatically, as the Loess Plateau, semi-arid and arid regions, did not experience a significant increase in rainfall corresponding to rising temperatures.

Broad environmental adaptation of abundant microbial taxa in Robinia pseudoacacia forests during long-term vegetation restoration

Vegetation restoration has significant impacts on ecosystems, and a comprehensive understanding of microbial environmental adaptability could facilitate coping with ecological challenges such as environmental change and biodiversity loss. Here, abundant and rare soil bacterial and fungal communities were characterized along a 15−45-year chronosequence of forest vegetation restoration in the Loess Plateau region. Phylogenetic-bin-based null model analysis (iCAMP), niche breadth index, and co-occurrence network analysis were used to assess microbial community assembly and environmental adaptation of a Robinia pseudoacacia plantation under long-term vegetation restoration. The drift process governed community assembly of abundant and rare soil fungi and bacteria. With increasing soil total phosphorus content, the relative importance of drift increased, while dispersal limitation and heterogeneous selection exhibited opposite trends for abundant and rare fungi. Rare soil fungal composition dissimilarities were dominated by species replacement processes. Abundant microbial taxa had higher ecological niche width and contribution to ecosystem multifunctionality than rare taxa. Node property values (e.g., degree and betweenness) of abundant microbial taxa were substantially higher than those of rare microbial taxa, indicating abundant species occupied a central position in the network. This study provides insights into the diversity and stability of microbial communities during vegetation restoration in Loess Plateau. The findings highlight that abundant soil fungi and bacteria have broad environmental adaptation and major implications for soil multifunctionality under long-term vegetation restoration.

Increased sensitivity of vegetation to soil moisture and its key mechanisms in the Loess Plateau, China

AbstractSoil moisture (SM) plays a crucial role in connecting various ecological processes in terrestrial ecosystems, as vegetation growth heavily relies on SM availability. Despite many studies evaluating the impacts of SM on vegetation activity, changes in vegetation sensitivity to SM are still poorly understood. In this study, we evaluated the spatiotemporal changes of vegetation sensitivity to SM across the Loess Plateau (LP) region from 1982 to 2010 using satellite‐based normalised difference vegetation index (NDVI) and reanalysis SM data. Our results showed a significant increase in NDVI (slope = 0.0015/year, p < 0.001) and a slight decrease in SM (slope = −0.0001 m3/m3/year, p = 0.7) over the past 29 years, indicating a greening trend in the LP. By establishing a multiple linear model, we found that the sensitivity of vegetation dynamics to SM has significantly increased during the same period (slope = 0.029, p < 0.05). Spatially, vegetation in over half (51.2%) of the total area showed enhanced sensitivity to SM. Further analysis using the Lindeman–Merenda–Gold method showed that atmospheric CO2 was the major contributor (27.20%) to the sensitivity changes, followed by nitrogen deposition (23.70%) and air temperature (20.11%). Ecosystem structure changes (represented by non‐tree land cover fractions) and precipitation shifts contributed 16.13% and 12.83%, respectively, to sensitivity changes. These findings provide a better understanding of the spatiotemporal pattern and underlying mechanisms of ecosystem sensitivity to SM in the greening and warming LP.

Assessment of suitable areas for afforestation and its carbon sink value in fragile ecological areas of northern China

Afforestation and reforestation are pivotal in mitigating land degradation and bolstering the carbon sink capacity of terrestrial ecosystems. However, the potential economic ramifications of afforestation and reforestation in the context of climate change remain largely unexplored. In this study, we employed an interdisciplinary methodology to establish a framework for assessing future forest potential and carbon sequestration in the Eastern Loess Plateau region of China. Our findings indicate that an estimated 17,392.99 km2 of land suitable for afforestation still existed within the region, exhibiting a propensity to aggregate around existing forests rather than being dispersed randomly. Notably, 4385.36 km2 was prioritized for afforestation initiatives. Projections suggest a significant enhancement of the forest carbon sink within the study area by 2050, ranging from 36.93 Mt to 105.38 Mt. The corresponding economic value for this enhancement is estimated to vary between US$3.25 billion and US$17.68 billion. Of significance is the observed polarization of the region's carbon sink capacity over time, with half of the total carbon sinks concentrated within 10% of the districts. Additionally, approximately 26% of the counties are expected to transition from carbon sinks to carbon sources. These findings underscore the substantial impact of climate change on forest distribution and suggest a targeted approach to combat forest degradation by circumventing ineffective afforestation activities.

Geomorphic understanding of loess landslides activity on the loess tableland:A case study in the Bailu Tableland, China

Loess landslides, predominantly triggered by human activity and precipitation, dominate the geomorphological evolution of extensive regions of the Chinese Loess Plateau. Tablelands constitute a large proportion of this Loess Plateau. Although the area has a long history of human occupation, the Bailu Tableland is relatively poorly studied. Recent landslide events along the edge of the tableland significantly affected lives and livelihoods. To develop a better understanding of geomorphological evolution and develop appropriate hazard management and mitigation strategies, we characterized recent landslide activity and determined whether there are discernable trends in activity. We used Unmanned Aerial Vehicle (UAV) observations, Interferometric Synthetic Aperture Radar (InSAR) monitoring, and Digital Terrain Analysis (DTA) to observe significant differences in the position, shape, and magnitude between old and new landslides. The geomorphological evolution of the tableland was initially driven by large landslides, while current and future morphological development is more likely affected by small landslide events. We demonstrate the successful application of InSAR to investigate potential landslides in well-vegetated loess landscapes and show that loess landslides tend to develop on slopes with high relative relief and high topographic wetness associated with gully erosion. Unlike landslides induced by groundwater variations in the Heifangtai and South Jingyang tablelands, precipitation and infrastructure construction form the main controls on landslide activity in the Bailu Tableland. We propose two geomorphological evolution models that describe loess tableland recession caused by landslides. The results from this research contribute to a better understanding of the reactivation behavior of landslides along loess tablelands, provide a scientific foundation for landslide hazard and risk management, and supplement understanding of the geomorphological evolution of loess tableland landscapes.

Susceptibility assessment of soil-water hazard chain on a small catchment in gully region of Loess Plateau: Implications for artificially-induced mountaintop removal filling valley and geoheritage

Soil-water hazards are the most common hazards in Loess Plateau, China, and they can impart devastating effects on living environments of human beings, land planning, and geoheritage sites. A typical study area was selected to elucidate the relationship between soil-water hazards chain susceptibility and human activities, geoheritage sites. Landslide and gully erosion susceptibility was obtained by using gradient boosting and support vector machines, and then, hazard matrix was carried out to couple landslide and gully erosion susceptibility. Ultimately, the high susceptibility classes of landslides and gully erosion was selected as the material source of soil-water hazards chain. Meanwhile, Flow-R software was applied to acquire soil-water hazards chain susceptibility. Thereafter, different magnification times of soil-water hazards chain was quantified under different scenarios. Fourteen conditioning factors were considered in different susceptibility mapping after a collinearity test. The medium-high susceptibility of landslide, gully erosion, coupling soil-water hazards, soil-water hazards chain accounted for 41.40 %, 46.96 %, 49.11 %, and 51.14 % of the entire area, respectively. The proportion of magnification times were a trend of decreasing from first scenarios to third scenarios when the soil-water hazards magnification times was <5, however, there was a trend of increasing that of different scenarios when the magnification times was >5. Moreover, a series of geomorphological factors and human activities factors were highly important for the occurrence of geohazards, especially in artificially-induced mountaintop removal filling valley obviously amplified the harm of soil-water hazards. In addition, many geoheritage sites were distributed in medium-high susceptibility areas for different soil-water hazards, and their proportion exceeded 40 %. This study provides a novel and useful paradigm for the relationship between human activities and soil-water hazards can attain an optimal state, and a harmonious balance can be established between human beings and nature.

Effects of different mulch materials on the photosynthetic characteristics, yield, and soil water use efficiency of wheat in Loess tableland

Due to the lack of precipitation and poor temporal and spatial stability in the Loess Plateau for a long time, it is necessary to adopt mulching technology to support the stable and high yield of wheat cultivation system. This study aims at exploring different mulching materials on the soil water content, photosynthetic characteristics, wheat yield, and yield components of winter wheat in the gully region of the Loess Plateau. The results showed that the traditional flat soil water content is the lowest in the seedling stage. In the jointing stage and heading stage of many crop water requirements, ridge film mulching treatment can effectively promote the growth of wheat and increase the water use efficiency. The leaf area index (LAI) of different treatments wheat showed a trend of increasing first and then decreasing. In the jointing stage, ordinary mulching film (T1) and liquid mulching film (T3) had the highest LAI content, which were 3.78 and 3.71 respectively. The Pn and Gs in wheat flag leaves of T3 treatment is higher than that of CK throughout the entire growth period, and T3 significantly increased Ci and WUEi in different growth stage. And the grain number per panicle and grain weight of T3 treatment were 24.44 and 41.00 g, which were 19.3% and 5.4% higher than CK, respectively. Through the actual production calculation of the final harvest, the ridge film mulching has a significant increase in production compared with the CK. The yield of T3 treatment was 4980.25 kg hm−2, which was 29.37% higher than CK. It was significantly different from CK (P < 0.05). Based on the comprehensive analysis, the ridge film mulching treatment significantly affected the soil water content and wheat yield. And the liquid mulching film had the best effect. Exploring the impact of different covering techniques on the wheat cultivation system in the Loess Plateau region, to promote the scientific promotion of this technology.

Daily and seasonal patterns of stem diameter micro-variations in three semiarid forest species in relation to water status and environmental factors

Understanding the relationship between stem diameter micro-variation (SDMV) and stem water status and revealing the mechanism regulating stem water are essential for elucidating environmental adaptation and water use strategies in forest trees. Here, we report the results of the year-round monitoring (November 2018–October 2019) of SDMV and xylem sap flow obtained using high-resolution dendrometers and Granier-type thermal dissipation probes, respectively, in mature trees of three species in the semiarid Loess Plateau region: Quercus liaotungensis, Platycladus orientalis, and Robinia pseudoacacia. The year-round trend for the variations in stem diameter can be divided into phases of a decreasing period and a relatively stable period in the non-growing season, and a progressive rise and fluctuating plateau throughout the growing season. The observed interspecific differences in the time to full recovery from the water deficit state corresponded to species phenology and soil moisture conditions. These differences were manifested as the responses of sap flux density (Fd) and tree water deficit (TWD) to variations in soil water content during the growing season. Q. liaotungensis implements stomatal regulation early to avoid drastic water loss in the trunk, P. orientalis maintains a relatively stable Fd at the expense of increased TWD under soil drought, and R. pseudoacacia maintains relatively low stomatal conductance under soil drought with an increase in TWD. The results revealed that SDMV is determined by the stem water status and species-specific strategies for water use, which could provide beneficial information for forestation practices in semiarid regions.

The deviation between the behavior and willingness of rural residents to use clean energy and its influencing factors in China

Rural residents who really accept and adopt clean energy make significant sense for long-term sustainability. The purpose of this study was to resolve the limitations of existing studies that only discuss whether there is a deviation between behavior and willingness, and deeply measures the deviation level between behavior and willingness to use clean energy for heating, cooking, and producing hot water, and to identify the factors influencing contrasting levels of deviation for different energy-consumption activities. A survey of 854 rural residents from 62 villages was conducted in the Loess Plateau region of China, and the multinomial logit model was used to investigate the influencing factors. The results showed that the proportion of high-level deviation for heating and low-level deviation for cooking was the highest. Policy cognition and usefulness perception had significant negative impacts on the deviation for heating, cooking, and producing hot water. Herd mentality had a significant positive impact on low-level deviation in hot water production. Males were more likely to have a high-level deviation for cooking. The results of this study provide a basis for scientific policy formulation and guide the transition from the willingness to the actual clean energy adoption behavior of rural residents.

Spatiotemporal change and drivers of ecosystem quality in the Loess Plateau based on RSEI: A case study of Shanxi, China

The fragile ecological environment and intensive human activities in the Loess Plateau region of China have led to serious soil erosion and adverse weather disasters. To address these issues, the Chinese government has implemented a series of large-scale ecological restoration projects with significant investments and broad public participation. Throughout this process, the ecosystems have undergone substantial artificial intervention. This study utilizes MODIS data to establish a remote sensing ecological index (RSEI) for evaluating the ecosystem quality of Shanxi Province, located in the eastern Loess Plateau, over the past 20 years (2000–2020). Furthermore, the study analyzed the natural and socio-economic factors that influence the local ecosystem quality using Geodetector analysis. The research findings revealed the following: 1) Over the 20-year period of large-scale ecological restoration projects, the ecosystem quality in Shanxi has significantly improved, as indicated by the average RSEI index increasing from 0.48 to 0.57. 2) The southern part of the province has experienced relatively better ecosystem recovery, while the ecosystem quality in the northern and western regions, particularly along the Yellow River, remains poor. 3) Overall, the major factors influencing ecosystem quality are natural geographical factors such as temperature and slope. However, with rapid urbanization, the negative impacts from socio-economic factors represented by GDP have intensified, particularly in the northern regions. Additionally, this study demonstrated that the geographically weighted regression model can better explain the local variations affecting the RSEI and exhibits a high degree of reliability. The research findings provide scientific and effective references for evaluating the ecosystem quality in the Loess Plateau and implementing ecological restoration projects.

First record of Pliocene ostracods from the Linxia Formation in Gansu Province, northwestern China (Loess Plateau region) and their palaeoenvironmental implications

ABSTRACT Understanding the palaeoenvironment of the Loess Plateau plays a key role in the researches about influences caused by the Tibetan Plateau uplift and the formation of the East Asia Monsoon (EAM). The Longxi area of the Gansu Province, northwestern China, is an ideal area to study such influences because of its unique geographical location within the transition zone among the EAM region, inland arid areas and the northeastern Tibetan Plateau. Here, we present ostracods from a borehole in the Longxi area, as ostracods are one of the few micropalaeontological proxies available in freshwater sediments. The studied ostracods were assigned to 13 species of 10 genera and 9 indeterminate taxa and reported for the first time from the Linxia Formation in the studied area. The ostracod assemblage is composed entirely of non-marine taxa, including species of Ilyocypris, Cypris, Cyprinotus, Heterocypris, Eucypris, Potamocypris, Zonocypris, Candona, Pseudocandona and Leucocythere. Ostracod biostratigraphy indicates that the Linxia Formation should be Pliocene in age. Palaeoenvironmental analysis of the studied ostracod assemblages suggests that there was a permanent freshwater lake with some temporary ponds in the studied area of the Loess Plateau during the Pliocene, which shows the influences of the East Asian Summer Monsoon during the Pliocene.

Climatic Warming-Induced Drought Stress Has Resulted in the Transition of Tree Growth Sensitivity from Temperature to Precipitation in the Loess Plateau of China.

Ongoing climate warming poses significant threats to forest ecosystems, particularly in drylands. Here, we assess the intricate responses of tree growth to climate change across two warming phases (1910-1940 and 1970-2000) of the 20th century in the Loess Plateau of China. To achieve this, we analyzed a dataset encompassing 53 ring-width chronologies extracted from 13 diverse tree species, enabling us to discern and characterize the prevailing trends in tree growth over these warming phases. The difference in the primary contributors over two warming phases was compared to investigate the association of tree growth with climatic drivers. We found that the first warming phase exerted a stimulating effect on tree growth, with climate warming correlating to heightened growth rates. However, a contrasting pattern emerged in the second phase as accelerated drought conditions emerged as a predominant limiting factor, dampening tree growth rates. The response of tree growth to climate changed markedly during the two warming phases. Initially, temperature assumed a dominant role in driving the tree growth of growth season during the first warming phase. Instead, precipitation and drought stress became the main factors affecting tree growth in the second phase. This drought stress manifested predominantly during the early and late growing seasons. Our findings confirm the discernible transition of warming-induced tree growth in water-limited regions and highlight the vulnerability of dryland forests to the escalating dual challenges of heightened warming and drying. If the warming trend continues unabated in the Loess Plateau, further deterioration in tree growth and heightened mortality rates are foreseeable outcomes. Some adaptive forest managements should be encouraged to sustain the integrity and resilience of these vital ecosystems in the Loess Plateau and similar regions.

Long-term anthropogenic field management enhanced wheat productivity and resource utilization in the Loess Plateau region of China

Low precipitation and poor soil quality are the main factors that limit wheat production in the Loess Plateau region of China. Straw incorporation and/or adding organic fertilizer can enhance wheat productivity by improving the soil water content (SWC) and soil fertility, but systematic long-term research has not yet been conducted. Thus, we conducted a 12-year continuous in-situ experiment in the Loess Plateau by testing four treatments: (1) CK: no fertilization and wheat straw removal; (2) FM: straw removal and application of inorganic fertilizer; (3) SI: straw incorporation and application of inorganic fertilizer; (4) SIOM: straw incorporation and application of inorganic fertilizer, with organic fertilizer added to replace 10% of the inorganic fertilizer. Under CK, the soil chemical properties and enzyme activities tended to decrease over the years. The soil fertility was significantly higher under FM than CK, and higher under SI and SIOM than FM (P < 0.05). SIOM significantly improved the soil nutrients and wheat productivity than other treatments (P < 0.05). Compared with FM, the soil bulk density in the 0–20 cm soil layer under SIOM decreased by 4.5%, while SOC, TN, TP, AN, and Olsen-P increased by 4.5%, 6.1%, 4.9%, and 12.3%, respectively. The DOC, DON, MBC, and MBN contents increased by 18.5%, 26.4%, 15.8%, and 16.2%, respectively. The activities of urease, sucrase, and catalase increased by 12.8%, 13.6%, and 22.8%, and the N uptake, nitrogen use efficiency (NUE), water use efficiency (WUE), water productivity, and wheat yield increased by 17.8%, 43.7%, 38.6%, 33.5%, and 22.4%. SIOM obtained the highest NUE, WUE, yield, and economic benefits of 37.83%, 14.34 kg ha–1 mm–1, 4579.16 kg ha–1, and 7990.39 Yuan ha–1, respectively. Linear mixed effects modeling showed that the year and treatment significantly affected the soil fertility and wheat productivity (P < 0.05). Random forest and structural equation modeling showed that the soil and fertilizer management strategies increased wheat productivity (R2 = 0.50) by improving the soil fertility. Therefore, straw incorporation and applying inorganic/organic fertilizers are effective management strategies for improving soil fertility and wheat productivity in semi-arid areas of Loess Plateau regions.

Ephemeral gully development in the hilly and gully region of China's loess plateau

AbstractEphemeral gully erosion is a significant form of soil erosion that visibly impacts soil productivity and restricts land use. While watersheds are fundamental for controlling soil erosion, past studies have focused on individual ephemeral gully or slope types, which do not fully represent changes in ephemeral gullies at the watershed scale. This research used remote sensing images (0.5 m resolution), unmanned aerial vehicles (UAV), and field investigations to analyze the spatial–temporal evolution and development rate of ephemeral gully erosion at the watershed scale on the Loess Plateau from 2009 to 2021. Using spatial information and morphological parameters of ephemeral gullies obtained from the SegNet model, we found that: (1) ephemeral gully numbers decreased from 4495 in 1999 to 2312 in 2021 due to improved vegetation coverage; (2) average growth rates of ephemeral gully frequency, length, density, dissection degree, and width were 2.87 km−2 year−1, 1.66 m year−1, 0.12 km km−2 year−1, 0.01% year−1, and 0.04 m year−1, respectively; (3) ephemeral gully erosion volume (V) and length (L) had a good power function relationship: . The root‐mean‐square error (RMSE) and coefficient of determination (R2) between measured and predicted ephemeral gully volumes indicated that the V–L relationship has a good predictive ability for ephemeral gully volume; thus, the V–L model was used to evaluate the development rate of ephemeral gully erosion volume in small watersheds from 2009 to 2021, revealing an average value of 743.20 m3 year−1. This study presents an empirical model for assessing ephemeral gully volume and volume changes at a watershed scale using high‐resolution remote sensing images, providing a reference for understanding the development of ephemeral gully erosion in small watersheds over time.

Discriminating the impacts of vegetation greening and climate change on the changes in evapotranspiration and transpiration fraction over the Yellow River Basin

Evapotranspiration (ET) is a vital parameter in terrestrial water-energy cycles. The transpiration fraction (TF) is defined as the ratio of transpiration (T) to evapotranspiration (ET), representing the contribution rate of vegetation transpiration to ecosystem ET. Quantifying the relative contributions of vegetation and climate change on the ET and TF dynamic is of great significance to better understand the water budget between the land and atmosphere. Here, we chose Yellow River Basin (YRB) as the study area and analyzed the spatiotemporal changes of ET, T, and TF from 1982 to 2015 using the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model. Meanwhile, the relative contributions of vegetation and climate change to ET, T and TF change were quantified. Model evaluation showed that the PT-JPL model performs well in the simulation of ET and T. During 1982–2015, the average annual ET, T, and TF increased at a rate of 3.20 mm/a, 0.77 mm/a and 0.003/a over the YRB during 1982–2015, respectively. The regions with significant increases in ET, T and TF almost covered the whole study area except for the upper reaches of the YRB. Vegetation greening was the main factor for the increase of ET and TF in the YRB and enhanced ET and TF at a rate of 0.72 mm/a and 0.57/a, respectively, which mainly observed in the entire Loess Plateau region (over 50 % of the study area). Precipitation (PRE) was also the dominated factor contributing to the increase in ET and TF, and temperature (TEM) showed a positive correlation with the changes in ET and TF in the most areas of YRB, which jointly dominated ET changes in the upper reaches of the YRB and TF changes in the southern part of the basin. Except for the total effects, leaf area index (LAI) also indirectly promoted ET changes by affecting PRE, TEM and relative humidity (RH). While wind speed (WS) and radiation (RAD) had a relatively weak regulatory effect on the changes in ET and TF. These findings were helpful for regional water resources management and formulating water resources-sustainable vegetation restoration strategies for local government.