Loess Plateau Region Research Articles

Study on the Root Characteristics and Effects on Soil Reinforcement of Slope-Protection Vegetation in the Chinese Loess Plateau

The Loess Plateau region of China suffers from severe soil erosion, and the selection of effective slope-protection vegetation is essential to prevent soil and water loss. This study focused on individual plants of common species in the Loess Plateau, such as Caragana korshinski Kom., Hippophae rhamnoides Linn., Pinus tabuliformis Carr., Robinia Pseudoacacia Linn., Populus tomentosa Carr., Prunus armeniaca Lam. The root spatial distribution, geometric morphology, and fractal characteristics of these plants were measured using the whole-root-excavation method, and the vertical pull-out force of their root systems was quantified using the in situ whole-plant root-pulling method. The results showed that H. rhamnoides dominates in the vertical spatial distribution of its root system through a larger number of inclined roots. C. korshinskii, P. tomentosa, R. pseudoacacia, and P. armeniaca dominate in the horizontal spatial distribution of their root systems through a greater number of horizontal roots. P. tabuliformis, on the other hand, achieves a relatively balanced distribution in both horizontal and vertical spaces through its well-developed taproot and numerous lateral roots. In terms of the geometric morphology and fractal characteristics of their root systems, H. rhamnoides and C. korshinskii exhibit a larger number of fine roots and complex branching, resulting in a higher total-root length, total-root surface area, and root fractal dimension. The soil-stabilizing ability of H. rhamnoides, C. korshinskii, and R. pseudoacacia was stronger, mainly influenced by their total-root length, total-root surface area, and inclined root quantity, and these species can be prioritized as typical vegetation for soil and water conservation in the construction of Loess Plateau vegetation. From the perspective of slope stabilization and soil conservation alone, we strongly recommend planting shrub vegetation in the Chinese Loess Plateau.

The Impact of Water Potential and Temperature on Native Species' Capability for Seed Germination in the Loess Plateau Region, China.

Global warming is increasing the frequency and intensity of heat waves and droughts. One important phase in the life cycle of plants is seed germination. To date, the association of the temperature and water potential thresholds of germination with seed traits has not been explored in much detail. Therefore, we set up different temperature gradients (5-35 °C), water potential gradients (-1.2-0 MPa), and temperature × water potential combinations for nine native plants in the Loess Plateau region to clarify the temperature and water combinations suitable for their germination. Meanwhile, we elucidated the temperature and water potential thresholds of the plants and their correlations with the mean seed mass and flatness index by using the thermal time and hydrotime models. According to our findings, the germination rate was positively correlated with the germination percentage and water potential, with the former rising and the latter decreasing as the temperature increased. Using the thermal time and hydrotime models, the seed germination thresholds could be predicted accurately, and the germination thresholds of the studied species varied with an increase in germination percentage. Moreover, temperature altered the impact of water potential on the germination rate. Overall, the base water potential for germination, but not the temperature threshold, was negatively correlated with mean seed mass and was lower for rounder seeds than for longer seeds. This study contributes to improving our understanding of the seed germination characteristics of typical plants and has important implications for the management and vegetation restoration of degraded grasslands.

A discussion on carbon and oxygen isotopes of secondary carbonates in loess-paleosol sequences

Although carbon and oxygen isotopic compositions of carbonates are valuable for Quaternary climate reconstruction due to their sensitivity to paleoclimate changes, a comprehensive understanding regarding the formation, factors influencing isotopic variations, and age uncertainties of secondary carbonates in loess deposits remains elusive. This study investigates the microstructure and stable isotopes of secondary carbonates, specifically calcified root cells (CRC) and needle-fiber calcite (NFC), found within the loess deposits of the last glacial period in the northwestern region of the Chinese Loess Plateau. The average δ13C values of soil total organic matter, CRC, NFC, and total inorganic carbonates in the YuanBao sections are −22.1‰, −14.9‰, −7.0‰, −4.6‰, respectively. Radiocarbon dating results reveal that both CRC and NFC were not of synsedimentary origin. The pronounced negativity of the carbon isotopic composition and the microstructures offer insights that CRC formation is closely tied to C3 plants. The synchronous depletion of δ13CCRC and δ18OCRC values during the transition period from the last glacial to the Holocene, underscores the sensitivity of isotopic composition of CRC to local environmental changes, making it a potential candidate for paleo-climate studies. Additionally, CRC formed during the glacial period provides a close approximation to the true sedimentation age. The radiocarbon dating of NFC highlights a significant fluctuation in carbon source translocation depth, resulting in a pronounced temporal and spatial decoupling between NFC formation and the surrounding deposits. Consequently, values of δ13CNFC and δ18ONFC seem to exhibit no significant trend across the limited depth range in this research. We propose that, when using NFC for paleoclimate reconstruction, careful consideration of variations in translocation depths of carbon sources is imperative to prevent misestimations. NFC could potentially be more fitting for broader temporal-scale paleoclimate reconstructions rather than high-resolution investigations.

Responses of belowground fine root biomass and morphology in Robinia pseudoacacia L. plantations to aboveground environmental factors

The adaptation of fine roots to a variety of environmental conditions is crucial for promoting the growth and long-term survival of forest trees. To achieve sustainable forest ecology management requires a comprehensive understanding of the intricate relationships between belowground and aboveground factors in the forest ecosystem. Equally important is identifying the factors that directly affect the growth and development of fine roots belowground. This study was carried out in 25-year-old pure plantations of Robinia pseudoacacia L. within the Caijiachuan watershed, Jixian County, Shanxi Province, China. Twenty-seven permanent sample plots were established, with each plot measuring 20 × 20 m. These plots covered nine different stand densities ranging from 775 to 2975 trees/ha, with three replicates per density. Through field surveys and multivariate analysis, along with the use of a simplified Generalized Linear Model, this study revealed the alterations in belowground fine root biomass and morphology resulting from variations in stand density. Additionally, it explored the mutual relationships between belowground fine root biomass and morphology and aboveground environmental characteristics. The results show that, under different stand densities, only fine root biomass, specific fine root length, fine root tissue density, and fine root tip density displayed significant differences (P < 0.05), while specific fine root surface area exhibited a decreasing trend with increasing stand density. Moreover, lower densities (1025 and 1175 trees/ha) promoted the growth of specific fine root length and specific fine root surface area, while higher densities (2100 and 2475 trees/ha) supported the development of fine root biomass and fine root tip density. The combined contributions of semi-decomposition layer litter layer thickness (contribution value: 0.1340), mean tree height (contribution value: 0.2710), and neighborhood comparison (contribution value: 0.1840) significantly explain the variations in fine root biomass (P = 0.014) and specific fine root surface area (P = 0.031). Fine root biomass shows statistically significant correlations only with total phosphorus and available phosphorus (P < 0.05). The influence of soil factors (contribution value: 0.0306) on subterranean fine roots is much less pronounced compared to that of stand structure (contribution value: 0.1152) and other environmental factors (contribution value: 0.1128). These factors together account for the variations in subterranean fine roots, with stand structure and other environmental factors making the most significant contributions (contribution value: 0.5840). These research findings offer valuable insights into the connections between subterranean fine roots and aboveground biotic and abiotic factors in Robinia pseudoacacia L. plantations in the northern Loess Plateau region. Furthermore, they provide vital information for the prudent management and operation of low-efficiency Robinia pseudoacacia L. plantations.

Deep plowing increases soil water storage and wheat yield in a semiarid region of Loess Plateau in China: A simulation study

ContextRational tillage practice is critical for increasing soil water storage capacity and improving crop production in semiarid areas with uneven rainfall distribution. ObjectiveThe aims of this study are to examine the effects of fallow tillage practice on wheat yield, soil water storage and water use efficiency, to investigate the appropriateness of different tillage practices under varying precipitation conditions, and to identify key factors contributing to yield variations among these practices. MethodsHere we compared the effects of different tillage practices (deep plowing, DP; subsoiling tillage, ST; and shallow rotary tillage, RT) on soil water storage and winter wheat yield in a semiarid region of the Loess Plateau in China, using field experimental data from 2009 to 2014 and APSIM (Agriculture Production System sIMulator) simulation results from 1980–2018. ResultsThe APSIM well simulated the soil water storage (0–200 cm), phenology, biomass and yield of winter wheat, with R2 > 0.65 and 0.71 for each variable in calibration years and validation years, and nRMSE <16.9 % and 22.1 %, respectively, indicating a good correlation and medium consistency between simulated and measured values. The simulated average annual soil water storage, biomass, yield, and water use efficiency under DP were 8.4 %, 18.4 %, 25.5 %, and 22.3 % higher than under RT, and 7.9 %, 13.8 %, 22.4 %, and 21.4 % higher than under ST, respectively. These variables did not differ between ST and RT treatments. Compared to RT, DP improved the soil water storage by 9.0 %–12.0 % from October to March, increased by 4.8 %–7.1 % during the fallow period, and increased by 2.5 %–7.4 % from April to June. This was mainly because DP had more precipitation reserves during the fallow period, but in the later stage of wheat growth, as precipitation increased, the difference in soil water storage between different tillage practices decreased. Wheat yield, precipitation and soil water storage were significantly and positively correlated. The difference in yield between DP and RT was greater at the medium than at low and high yield production levels, but that between ST and RT was not significant. ConclusionDP increased soil water storage from October to March and improved wheat yield, which should be recommended to ensure high wheat yield and efficient water use in the Loess Plateau. ImplicationsThis study validated the applicability of DP tillage in semi-arid areas on a long-term scale and found its superiority at different yield production levels.

Importance of forest stand structures for gross rainfall partitioning on China’s Loess Plateau

Large-scale ecological restoration in the arid and semi-arid Loess Plateau region of northern China is challenged by the intensifying water stress due to the changes in precipitation regimes. Although the importance of Gross Precipitation Partitioning (GRP) has been well recognized in forest hydrology, especially in dry areas, the processes are not understood because site- or region-specific factors complicate the accurate quantifications. This study integrates meta-analysis and field observation to compare patterns of GRP in forest stands that had different origins (plantations vs. native forests) and tree species (deciduous vs. evergreen) compositions. We aimed at quantifying the dominant biotic and abiotic factors controlling each of the GRP components to form empirical relationships between the GRP components and the influencing factors via the Boosted Regression Trees (BRT) model. We found a convergence in the GRP components among the examined stands that have diverse tree species and origins. Our results indicated that, unlike stem flow (SF) and canopy interception (Ic), the throughfall (TF) did not differ between natural and plantation stands. Meanwhile, from the perspective of species composition, the broadleaf forest stands had significantly higher SF rates than the coniferous stands. We found that stand structures exerted limited influence on TF, but significantly affected SF and Ic. We hypothesized that the residence time of the GRP components was important in explaining the matrix of influencing factors. The cumulative influences of stand structure factors played a more important role than species in most conditions. Based on the most influential factors (cumulative explanatory power > 70 %) selected from the BRT model, we successfully built a general formula to represent the GRP processes across the diverse forest stands in the Loess Plateau. Our study provides insights into the underlying mechanism of GRP for developing more realistic forest hydrological models. An improved understanding of GRP and better models are important for guiding large scale reforestation efforts that account for hydrological processes across stand species and origins.

Effects of tillage microrelief units on splash erosion: A case study from the Loess Plateau, in China

A tillage microrelief unit is the smallest spatially discontinuous area unit of tillage microrelief. Understanding the impact of tillage microrelief units on splash erosion is essential for selecting suitable tillage measures and employing soil and water conservation practices. The objective of this study was to investigate the characteristics and mechanisms of splash erosion under different tillage microrelief units in various directions and distances using the rainfall simulation experiment in the soil landscape of the Loess Plateau region in China, characterized primarily by sloping farmland as the main land use type. Three typical microrelief units, namely, artificial digging (AD), contour tillage (CT), and straight slope conditions (SSC) were designed at 0°, 3°, 5°, 10°, 15°, and 20° slopes. Tillage microrelief units with high surface roughness produced more splash erosion than flat lands. Further, the highest surface roughness increased the total splash amount by 102% relative to flat lands. The tillage microrelief unit itself was elevated with a certain slope, which increased the downslope splash of CT, SSC, and AD by 121%, 173%, and 11%, respectively. Different surface roughness values and slopes under different microrelief units were used to determine the amount of splash erosion. The results showed that the total splash amount responded significantly (P < 0.01) to the interaction between surface roughness and slope, and the sensitivity to roughness was higher than that to slope. According to the single-factor analysis, the surface roughness of all slopes significantly influenced the amount of splash erosion. Furthermore, the sensitivity of the tillage microrelief unit to the slope decreased because of the high slope under high surface roughness. Overall, the results of this study showed that in different tillage microrelief units of slopes in the Loess Plateau, SSC and CT significantly increased the outward splash erosion in this area, while AD significantly decreased the outward splash erosion. Moreover, slope did not have a considerable influence.

Quantification of ecosystem service value and its guidance to land use strategy in Loess Plateau region: A case study of Qingyang City

Abstract Alterations in land use strategies significantly influence regional sustainable development, affecting ecosystem service functions, surface energy balance, and biodiversity. This study explores the impact of ecosystem service values on land use within Qingyang City, situated in the Loess Plateau. We employ an index system to assess ecosystem services at the Loess Plateau across four dimensions—supply, regulation, culture, and support. Utilizing physical and ecological value equivalent factors, we quantify these indices and the value of Qingyang City’s ecological service system. Specifically, the ecosystem equivalent factors for sloped cropland and terraced fields in Qingyang City are quantified as 1.1545 and 1.9788, respectively. Our findings reveal that ecosystem services significantly influence land use; notably, cropland and grassland, which collectively provide approximately 98% of climate regulation services, have experienced a reduction in their total climate regulation capacity by −14.19% and −9.42%, respectively, from 2010 to 2020. This reduction highlights a marked weakening in the climate regulatory capabilities of these land types, underscoring the need for Qingyang City to reassess and adjust its land use strategies to enhance the climate regulation service capacities of cropland and grassland.

Ditch control and land reclamation promote vegetation recovery in Loess Plateau.

This study aimed to assess the impact of land consolidation projects and climate change on changes in vegetation in the Loess Plateau during 2012-2021. The study also explored the impacts of human activities and climate change on the ecological quality of the Loess Plateau during this period. The spatial and temporal normalized difference combined meteorological monitoring data, project data, and normalized difference vegetation index (NDVI) data that was used to create the vegetation index dataset spanning from 2012-2021. The study discussed and assessed the effectiveness of the project, revealing the following results: 1) A significant increase was observed in the vegetation index of the Loess Plateau region from 2012 to 2021, with an upward trend of 0.0024 per year (P < 0.05). 2) Contributions to changes in vegetation attributed to climatic factors and the anthropogenic factors of the ditch construction project were 82.74 and 17.62%, respectively, with climatic factors dominating and the degree of response of the ditch construction project increasing annually. 3) In the Loess Plateau, climatic variables dominated changes in vegetation. However, land consolidation projects in vegetation factors played a key role in changes in vegetation, and the degree of influence was gradually increasing.

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 &lt; 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 &lt; 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.