Grain For Green Project Research Articles

The Spatiotemporal Dynamics of Vegetation Cover and Its Response to the Grain for Green Project in the Loess Plateau of China

The Spatiotemporal Dynamics of Vegetation Cover and Its Response to the Grain for Green Project in the Loess Plateau of China

An improved framework for quantifying the contribution of climatic and anthropogenic factors to vegetation dynamics - A case study of China

Accurately quantifying the impact of climatic and anthropogenic factors on vegetation change is critical for developing and evaluating ecological management strategies. However, most presented studies typically ignore the climate temporal effects and assume that all pixels are affected by both climate change (CC) and human activities (HA), which often introduce uncertainties. In this study, Leaf area index (LAI), temperature, precipitation, solar radiation, and land cover data from 1982 to 2020 were used to detect and attribute vegetation dynamics in China. We used partial correlation analysis, generalize linear model, trend analysis, and improved RESTREND to analyze the spatiotemporal variation characteristics of vegetation LAI from 1982 to 2020 and to quantify the effects of CC and HA on vegetation dynamics since the implementation of the Grain for Green Project (GGP). The results indicate that significant vegetation greening appeared in most areas (66.2%) between 2000 and 2020. Both CC and HA have positive effects on vegetation greening. In arid and semi-arid regions, precipitation was the primary driver of vegetation change, while in high-latitude areas of southern and southwestern China, temperature was the primary determinant. After considering the temporal effects, the explanatory power of climate variables for vegetation dynamics increased by 4.0% compared to ignoring the temporal effects, accounting for 72.81%. After dividing the pixels into those affected by CC and those affected by both CC and HA, the contribution of HA was decreased from 31.19% to 25.96%. Although the contribution of HA is lower than that of CC, ecological engineering has effectively promoted vegetation greening. These research findings provide scientific data and theoretical basis for ecological environment protection and natural resource management.

Benefit evaluation of sloping land conversion program in the upper reaches of the Yellow River

This study used forestry statistical data and field survey data from 2000 to 2018 to analyze the ecological restoration effect of the returning farmland to forest project in the upper reaches of the Yellow River, considering four perspectives, namely, project construction goals, ecosystem quality, ecosystem service functions, and ecological restoration driving factors. One-way ANOVA and logit regression analysis methods were used for comparison. The results show that the implementation of the Grain for Green Project has reduced the carrying capacity of rural land, effectively curbed the continuous deterioration of the ecological environment, and protected and benefited the forest ecosystem. (1) Initiatives of the return farmland to forest project have achieved the expected goals, and the forest coverage rate has increased significantly from 5.26 % (in 2000) to 15.63 % (in 2019); the proportion of primary, secondary, and tertiary industries related to forestry has reached a reasonable level, and the economic benefits thereof continue to improve. (2) Indicators such as total forest and grass vegetation coverage, vegetation net primary productivity, and forest and grass health index reflect that the functional quality of the regional forest and grass ecosystem is gradually improving. (3) The ecosystem service function of the project region has improved considerably, and the ecological benefits are significant. (4) In terms of the contribution value of the driving forces for this ecological restoration project, they can be ranked as follows: government investment > reducing land carrying capacity > policy of returning farmland to forest > government management > hydrological factors > meteorological factors. (5) After the implementation of the Grain for Green Project, farmers' income has increased significantly, but the changes in livelihood capital income are not synchronized. As the ecological environment in the Grain for Green project areas gradually improved from deterioration, the natural capital and social capital of farmers' livelihood capital decreased significantly, while the physical capital and financial capital increased significantly, with no significant change in human capital. Farmers' satisfaction with the Grain for Green Project is as follows: natural capital has a significant negative impact, while financial capital and social capital have significant positive impacts, and there are no significant changes in physical capital and human capital. Finally, the consistency test results show that the fit is as high as 95 %, and the accuracy exceeds 90 %. Notably, the implementation of the Grain for Green Project has played a pivotal role in ecological restoration and contributed greatly to ecological benefits. These achievements provide a scientific basis and theoretical support for the country to formulate relevant policies for forestry projects, which holds great significance for the country in addressing the contradiction between economic and social development and ecological protection.

Spatiotemporal Variability of Soil Erosion in the Pisha Sandstone Region: Influences of Precipitation and Vegetation

The Pisha sandstone area, situated in the upper and middle reaches of the Yellow River in China, is characterized by severe soil and water erosion, making it one of the most critical regions on the Loess Plateau. The rugged terrain and exposed bedrock complicate management efforts for this area, posing challenges for accurate forecasting using soil erosion models. Through an analysis of terrain, vegetation, and precipitation impacts on soil erosion, this study offers theoretical support for predicting soil erosion within the exposed Pisha sandstone area of the Loess Plateau. This has substantial implications for guiding water and soil conservation measures in this region. Focusing on China’s exposed sandstone area within the Geqiugou watershed, temporal and spatial changes in vegetation cover and land use from 1990 to 2020 were analyzed. The result shows that, from 1990 to 2020, the grassland area has exhibited a consistent downward trend, with successive reductions of 64.86% to 59.46%. The area of low vegetation cover witnessed a significant decline of 59.29% in 2020 compared to that in 1990. The moderate erosion area decreased from 84.52 to 57.17 km2. The significant reduction in soil and water loss can be attributed to the expansion of forest and grassland areas, with the implementation of the Grain for Green project serving as a key policy driver for facilitating this expansion. This study provided a good example of combining rainfall with vegetation coverage to fast estimation soil erosion. A mathematical relationship between the vegetation rainfall coupling index (RV) and soil erosion was established with strong fitting effects, enabling estimation of the soil erosion volume under varying slope conditions within Pisha sandstone areas. The main focus of future soil and water conservation in the Pisha sandstone area should be on effectively managing the channel slope and minimizing exposed bedrock areas through a combination of slope cutting, the application of anticorrosive materials, and the implementation of artificial vegetation planting.

Spatiotemporal Evolution and Simulation Prediction of Ecosystem Carbon Storage in the Yellow River Basin Before and After the Grain for Green Project

Under the background of "dual carbon", the impact of the implementation of the Grain for Green project on the carbon storage of the ecosystem in the Yellow River Basin must be explored, which can serve as an important reference for improving the policy implementation of the new round of the Grain for Green project and improving the carbon sink capacity of the ecosystem in the Yellow River Basin. In this study, 1990, before the implementation of the project, was selected as the starting year of the research period, and 2020, after the implementation of the two rounds of the project, was selected as the end year of the research period. Based on the ecosystem type data from 1990 to 2020, the InVEST model was used to calculate the soil carbon pool, underground carbon pool, below carbon pool, dead organic matter carbon pool, and total carbon storage of ecosystems in the Yellow River Basin and the area where the project was implemented from 1990 to 2020. The results showed that： ① From 1990 to 2020, the area of forest ecosystem in the Yellow River Basin expanded by 26 610.06 km2, and the area of farmland decreased by 46 849.06 km2 after the implementation of two rounds of the project. Spatially, the upper reaches of the Yellow River were dominated by grassland and other ecosystems； the middle reaches of the Yellow River were dominated by farmland, forest, and grassland ecosystems； and the lower reaches of the Yellow River were dominated by farmland ecosystems. ② From 1990 to 2020, the carbon storage in the project implementation area showed a fluctuating and increasing trend, and the total carbon storage reached a peak （219.47×108 t） in 2009 and decreased to 218.59×108 t in 2020 due to the decrease of grassland ecosystem from 2010 to 2020. Spatially, the high-value areas of carbon storage were distributed in Aba Tibetan and Qiang Autonomous Prefecture of Sichuan Province and the southern tip of Gansu Province in the upper reaches of the forest and grass accumulation and in the whole of Shanxi Province and the central and southern parts of Shaanxi Province in the middle reaches. Shangluo City in Shaanxi Province and Alxa League in Inner Mongolia Autonomous Region were prefecture-level cities with the highest and lowest average carbon density. ③ In 2035, the carbon storage loss of the natural development scenario was predicted to be 0.83×108 t, and the other three scenarios would increase this loss. Under the moderate farmland return scenario, the Yellow River Basin ecosystem had the strongest carbon sequestration capacity, and the predicted carbon storage would increase by 2.72×108 t compared with that in 2020, and the deep farmland return scenario was the comprehensive optimal scenario. Therefore, in the future, the Yellow River Basin could refer to the deep farmland return scenario to optimize and adjust the implementation plan of the Grain for Green project, and the predicted value of carbon storage can provide some data support for achieving the dual carbon goal.

Responses of vegetation to hydroclimatic variables on the Loess Plateau after large scale vegetation restoration

AbstractUnderstanding plant‐water relations is essential for effective regional water management and promoting ecologically sustainable development on the Loess Plateau, especially in the context of the Grain for Green project initiated in 1999. This study evaluated the variations in vegetation variables (leaf area index, enhanced vegetation index, solar‐induced chlorophyll fluorescence and gross primary production) and hydroclimatic variables (precipitation, total water storage, aridity index and standardized precipitation evapotranspiration index) from 2003 to 2020, along with their interactions across the Loess Plateau. Our analysis revealed a general increase in vegetation variables, with the largest increase observed in the forest expansion areas. Precipitation and the aridity index exhibited significant upwards trends, while total water storage showed a significant decline, particularly in the forest expansion areas. Vegetation variables were more sensitive to changes in total water storage across the Loess Plateau. In the northwest region, where large‐scale croplands and grasslands expansion occurred, vegetation variables also showed sensitivity to precipitation. Lag effect analysis revealed short time lags (1–3 months) between vegetation and hydroclimatic variables, expect for total water storage (6 months). Overall, human activities and climate factors contributed 58.4% and 41.6% to the increase in leaf area index, and 52.2% and 47.8% to the increase in gross primary production, respectively. In relatively arid environments, precipitation contributed over 50% to the observed vegetation greening. This study underscores the increasingly significant role of human activities in driving vegetation greening on the Loess Plateau, particularly in large‐scale afforestation areas.

Effect of different vegetation restoration patterns on community structure and co-occurrence networks of soil fungi in the karst region.

The Grain for Green Project (GGP) by the Chinese government was an important vegetation restoration project in ecologically fragile and severely degraded karst regions. Soil fungi play a facilitating role in the cycling of nutrients both above and below the ground, which is crucial for maintaining ecosystem function and stability. In karst regions, their role is particularly critical due to the unique geological and soil characteristics, as they mitigate soil erosion, enhance soil fertility, and promote vegetation growth. However, little is known about how the implementation of this project shifts the co-occurrence network topological features and assembly processes of karst soil fungi, which limits our further understanding of karst vegetation restoration. By using MiSeq high-throughput sequencing combined with null model analysis technology, we detected community diversity, composition, co-occurrence networks, and assembly mechanisms of soil fungi under three GGP patterns (crop, grassland, and plantation) in the southwestern karst region. Ascomycota and Basidiomycota were the main fungal phyla in all the karst soils. Returning crop to plantation and grassland had no significant effect on α diversity of soil fungi (P > 0.05), but did significantly affect the β diversity (P = 0.001). Soil moisture and total nitrogen (TN) were the main factors affecting the community structure of soil fungi. Compared with crop, soil fungi networks in grassland and plantation exhibited a higher nodes, edges, degree, and relatively larger network size, indicating that vegetation restoration enhanced fungal interactions. The soil fungi networks in grassland and plantation were more connected than those in crop, implying that the interaction between species was further strengthened after returning the crop to plantation and grassland. In addition, null-model analysis showed that the assembly process of soil fungal communities from crop to grassland and plantation shifted from an undominant process to dispersal limitation. These data indicated that GGP in karst region changed the composition and assembly mechanisms of the soil fungal community and enhanced the interaction between fungal species, which can contribute to a better understanding of the fungal mechanisms involved in the restoration of degraded karst soils through vegetation recovery.

Continuous Decline in Direct Incomes for Farmers Threatens the Sustainability of the Grain for Green Project

Understanding the impacts of ecological projects on household livelihoods is important in ensuring their sustainability. However, existing studies typically cover only a limited, discrete temporal point. Insufficient study duration makes it difficult to determine the full impact and dynamics of a project, affecting the veracity of the results. Representing one of the world’s largest investments in an ecosystem service programs, the Grain for Green Project (GGP) has an objective of increasing household incomes. Using data from 7112 questionnaires collected through 12 consecutive years (2007–2018) of field survey monitoring, this study examined the long-term impacts of the GGP on household livelihoods in the Beijing–Tianjin Sandstorm Source Control Project area through comparisons between participant households (PHs) and non-participant households (NPHs). The results show that GGP subsidies significantly increased household incomes only during the period 2007–2015, and their share of total household income decreased from 9.21% in 2007 to 1.62% in 2018. Subsidies for GGP cannot compensate farmers for losses due to the reduction in farmland. The above findings suggest that the effect of subsidies diminishes over time. Increased investment in jobs and skills training is needed to consolidate the GGP results. This provides new perspectives and empirical support for the study of international ecological compensation policies and sustainable development.

Changes in Soil Organic Carbon Density and Its Response to Climate Change and Human Activities Before and After the Grain for Green Project on the Loess Plateau

Accurately assessing the changes in soil organic carbon storage （SOCS） before and after the Grain for Green Project （GFG） in the Loess Plateau （LP） and exploring the relationship between its spatial and temporal distribution and the influencing factors were important references for the development of regional recycling as well as the formulation of ecological protection policies. Based on the data of climate, human activities, and SOCD in the surface （0-20 cm） and deep （0-100 cm） soil before and after GFG in the LP from 2001 to 2020, we investigated the changes in SOCD at different spatial and temporal scales by using the methods of trend analysis, the kriging method, and variance partitioning analysis. The results showed that： ① Before and after the GFG, the surface SOCS of the whole region increased by 8 338.7×104 t； the deep SOCS increased by 1 160.02×104 t. ② In each bioclimatic subregion, the whole-region average SOCD of Ⅰ （Semi-Humid Forest Region）, Ⅱ （Semi-Humid Semi-Arid Forest and Grassland Region）, and Ⅲ （Semi-Arid Typical Grassland Region） showed a significant increasing trend, with a decreasing trend in Ⅳ （arid semi-arid desert grassland area） and Ⅴ （arid desert area）. ③ The average surface SOCS increase in different ecosystems was ranked as follows： cropland > grassland > woodland > shrubs > bare land and sparse vegetation. The deep soil increase was ranked as follows： grassland > cropland > woodland > shrubs > bare land and sparse vegetation. ④ Climate factors were the most important driving factors for changes in SOCD； the annual average temperature and precipitation were significantly positively correlated with changes in SOCD. The results of the study could provide data support for regional ecological management and land use policy formulation to promote high quality development of the ecological environment in the LP.

The impact of vegetation reconstruction on soil erosion in the Loess plateau

Vegetation restoration not only extensively reshapes spatial land use patterns but also profoundly affects the dynamics of runoff and sediment loss. However, the influence of vegetation restoration on runoff and sediment yield from a regional perspective are scarce. This study therefore focused on 85 sites within the “Grain for Green” Project (GGP) region on the Loess Plateau, to investigate the impacts of the GGP on soil erosion. The results revealed a notable reduction in sediment loss and runoff due to vegetation restoration. Since the inception of the GGP in 1999, approximately 4.1 × 106 ha of degraded lands have been converted into forestlands, shrublands, and grasslands, resulting in an average annual reduction of 1.4 × 109 m3 in runoff and a decrease of 3.6 × 108 t in annual sediment loss on the whole Loess Plateau, with the GGP contributing approximately 26.7% of the sediment reduction in the Yellow River basin. The reduced soil erosion has mainly been regulated by vegetation cover, soil properties (clay, silt, and sand), slope, and precipitation on the Loess Plateau. The insights gained offer valuable contributions to large-scale assessments of changes in soil erosion in response to vegetation reconstruction and enhance our understanding of the spatial configurations associated with soil erosion control measures.

Changes in water conservation and possible causes in the Yellow River Basin of China during the recent four decades

As water quality declines and water resources become scarce, water conservation emerges as the central challenge of water resource management and sustainable development in the watershed ecosystem. The Yellow River, known as the “mother river” of China, of which the water conservation function has received significant public attention in the changing environmental conditions. In the study, the InVEST water yield model was utilized to evaluate the spatiotemporal dynamics of water conservation; the MK trend test and Sen’s slope were used to examine the trends of precipitation and water conservation, respectively. Additionally, the response of water conservation to climate, land use, and soil changes during the period 1981–2020 was also discussed. The results showed that under the comprehensive influence of various factors, the water conservation of the YRB showed a decreasing and then increasing trend, which was presumed to be associated with the Grain for Green Project. Water conservation showed an increasing trend in the upstream area of the study area while decreasing in the lower reaches in recent decades. The changes in water conservation function in the YRB resulted from the comprehensive influence of climate factors, soil conditions, and land use types. Besides, woodland and grassland provide the highest water conservation capacity, which initially increased and then decreased with the increase of slope. The spatial analysis emphasized the critical role of water conservation in the Yellow River Basin, particularly highlighting the source area (above Lanzhou Station), the southern tributaries of the Wei River, and the upper reaches of the Yiluo River as significant water conservation zones. These areas should be considered crucial and given priority in regional water resource management and ecological protection efforts. The findings of this study could provide a theoretical foundation for ecological protection and water security in the YRB, which are essential for sustainable development.

Improving Tree Cover Estimation for Sparse Trees Mixed with Herbaceous Vegetation in Drylands Using Texture Features of High-Resolution Imagery

Tree cover is a crucial vegetation structural parameter for simulating ecological, hydrological, and soil erosion processes on the Chinese Loess Plateau, especially after the implementation of the Grain for Green project in 1999. However, current tree cover products performed poorly across most of the Loess Plateau, which is characterized by grasslands with sparse trees. In this study, we first acquired high-accuracy samples of 0.5 m tree canopy and 30 m tree cover using a combination of unmanned aerial vehicle imagery and WorldView-2 (WV-2) imagery. The spectral and textural features derived from Landsat 8 and WV-2 were then used to estimate tree cover with a random forest model. Finally, the tree cover estimated using WV-2, Landsat 8, and their combination were compared, and the optimal tree cover estimates were also compared with current products and tree cover derived from canopy classification. The results show that (1) the normalized difference moisture index using Landsat 8 shortwave infrared and the standard deviation of correlation metric calculated by means of gray-level co-occurrence matrix using the WV-2 near-infrared band are the optimal spectral feature and textural feature for estimating tree cover, respectively. (2) The accuracy of tree cover estimated using only WV-2 is highest (RMSE = 7.44%), indicating that high-resolution textural features are more sensitive to tree cover than the Landsat spectral features (RMSE = 11.53%) on grasslands with sparse trees. (3) Textural features with a resolution higher than 8 m perform better than the combination of Landsat 8 and textural features, and the optimal resolution is 2 m (RMSE = 7.21%) for estimating tree cover, whereas the opposite is observed when the resolution of textural features is lower than 8 m. (4) The current global product seriously underestimates tree cover on the Loess Plateau, and the tree cover calculation using the canopy classification of high-resolution imagery performs worse than the method of directly using remote sensing features.

Temperature Mainly Determined the Seasonal Variations in Soil Faunal Communities in Semiarid Areas

The implementation of the Grain for Green Project has increased vegetation coverage and provided suitable habitats and food resources for soil fauna, thereby promoting the development of soil faunal communities. Studying seasonal variations in soil fauna communities in different vegetation areas can improve our understanding of the mechanisms that drive soil fauna recovery. We selected five typical artificially restored vegetation habitats, including Populus simonii (POS), Pinus tabulaeformis (PIT), Caragana korshinskii (CAK), Stipa bungeana (STB), and Medicago sativa (MES), and one farmland (Zea mays, FAL) habitat on the Loess Plateau. In this study, soil fauna communities and environmental factors were investigated during spring (May), summer (August), and autumn (November). Among the habitats, the STB habitat had the largest seasonal variation in soil faunal density (from 1173 ind·m−2 in May to 10,743 ind·m−2 in August), and the FAL habitat had the smallest (from 2827 ind·m−2 in August to 5550 ind·m−2 in November). Among the restored vegetation habitats, Acarina (44.89–88.56%) had the highest relative abundance of all taxa. The redundancy analysis (RDA) results showed that among the factors driving seasonal variation in soil animal communities, temperature (47.41%) was the most important, followed by precipitation (22.60%). In addition, the dominant groups, Acarina and Collembola, played an influential role in seasonal variations in soil faunal density. Temperature mainly determined the seasonal variations in soil faunal communities. Seasonal factors should be considered when conducting soil fauna research, as they contribute to biodiversity conservation and regional ecological management in the Loess Plateau.

Determining the impacts of climate change and human activities on vegetation change on the Chinese Loess Plateau considering human-induced vegetation type change and time-lag effects of climate on vegetation growth

ABSTRACT Since the initiation of the Grain for Green Project (GFGP) in 1999, dramatic change in vegetation status on the Loess Plateau. Spatially, geographical detector was employed to detect dominant variables influencing the spatial arrangement of normalized difference vegetation index (NDVI). Temporally, lagged or accumulated monthly precipitation, temperature and standardized precipitation evapotranspiration indices (SPEIs) sensitive to the monthly NDVI were first detected for every individual pixel, and the correlation between the NDVI and meteorological elements with time-lag effects was established a random forest model of unchanged land cover, followed by attributing impacts of climatic alterations and human interventions through residual examination across changed land cover. The findings indicate that (1) precipitation, slope, and soil dominantly influence the spatial arrangement of the NDVI. (2) Precipitation in current the month and cumulative temperatures of the previous 1–2 months steadily affect vegetation growth significantly, the optimal accumulation time interval for SPEI around 2000 are 8 months and 4 months, respectively. (3) Increases in the average NDVI within woodland and meadow vegetation on the Loess Plateau were primarily driven by climate change before 2000, accounting for 76.2%, whereas after 2000 it was dominantly driven by human activities, accounting for 64.16%.

TIC-driven sustainable land use mode in the Loess Plateau: A case study of gully land consolidation project in Yan'an City, China

The Loess Plateau is one of the most severely eroded areas in the world. The complexity of the multiple challenges facing the Loess Plateau entails the support of scientific and systematic innovations in land use. Based on technological innovation cluster (TIC) theory, this paper develops a self-circulation structure model for the TIC to analyze the hierarchical structure of the land-use innovations in the Loess Plateau. Then, employing the self-circulation structure model and taking the “Gully Land Consolidation Project” (GLCP) as a case study, this paper proposes one TIC-driven sustainable land use mode (TSLUM). A TIC has been developed among innovations in the TSLUM. The structure of TSLUM consists of three types of innovations: basic, related, and infrastructure innovations. Basic innovations are generally radical innovations that breed related, and infrastructure innovations. Diffusion-based and reversal-based mechanisms govern the evolution of the TSLUM. These two clustering mechanisms integrate with each other and jointly promote the development of the TSLUM in a self-circulation way. Furthermore, the TSLUM exhibits multiple functions, such as optimizing gully-slope interaction mechanism, providing continuous driving forces, consolidating the achievements of the “Grain for Green Project”, bolstering rural livelihoods, and fostering some feasible ways for food security. The results obtained will be useful for advancing sustainable land use and regional sustainable development in the Loess Plateau via TICs effectively and systematically.

Surface soil microbiome changes in Grain for Green Project accelerates organic carbon mineralization on the Loess Plateau in China

AbstractIncreasing amounts of greenhouse gases, such as CO2, released into the atmosphere have a profound impact on global climate change. Understanding how soil organic carbon (SOC) mineralization changes as a result of land‐use change can shed light on the mechanisms by which SOC mineralization occurs, thus illuminating pathways to achieve global C neutrality targets. Accordingly, the Grain for Green Project (GGP) on the Loess Plateau was used as the starting point to observe how microorganisms affect SOC mineralization through field sampling and laboratory incubation experiments. We found a significant increase in SOC mineralization rates resulting from the GGP, though only at the soil surface (0.47–6.40 mg·kg−1 soil·day−1). We also found that soil microorganisms had a significant effect on different types of C sources, and Proteobacteria and Ascomycota/Mortierellomycota were the dominant bacterial and fungal groups at the GGP sites. The factors limiting SOC mineralization varied with farmland conversion to other land‐use types, and the direct and interactive contributions of these factors were quantified. The explanatory power examined in terms of land‐use ability to directly predict SOC mineralization rates was as follows: farmland (0.82), grassland (0.76), shrubland (0.41), and forestland (0.29). Along the increasing vegetative complexity gradient from farmland to forestland, the individual variable explanatory values decreased, while the relative importance of the interactive effects between variables increased. Our research demonstrates that the GGP increased soil biological activity and improved microbial community ability to metabolize C sources, thereby accelerating SOC mineralization. This will provide a scientific basis for decisions to enhance global semidrought recovery.

Ecological restoration success on the Loess Plateau of China: A qualitative and quantitative exploration based on rephotography

AbstractEcological restoration programs such as the “Grain for Green Project” (GFGP) have significantly reduced soil erosion and increased vegetation cover on the Loess Plateau (LP) of China over the last decades. The LP has become the paragon of ecological restoration and soil and water conservation across the world and has been highlighted by numerous reports in the literature. However, there is a lack of “seeing is believing” evidence (that is, a picture is worth a thousand words) depicting the effectiveness of the ecological restoration on the LP. Rephotography (repeat photography) was used in this study to compare historical and current photographs of the same locations to explore the landscape changes associated with ecological restoration. Twenty‐nine photo pairs between 1925 and 2021 were compiled and combined with satellite imagery and the deduced Normalized Difference Vegetation Index (NDVI) between 1986 and 2021. This allowed the establishment of a rephotography library reflecting the achievements of ecological remediation and reconstruction on the LP. This in turn provides intuitive and detailed evidence for the ecological environment construction of the LP and resonates with the notion of “lucid waters and lush mountains being invaluable assets”. In addition to presenting a great opportunity to investigate landscape change over time, which is difficult to discern using other approaches, the study provides a scientific reference and a basis for government decision‐making. The potential use of rephotography for calibrating remote sensed data was also discussed. Good agreement was found between the NDVI derived from rephotography of large areas and NDVI derived from satellite imageries, which may facilitate the accurate reconstruction of time series NDVI.

Constructing semi-arid ecological barriers to prevent desertification

<p>Semi-arid regions worldwide face escalating challenges, including water resource shortages, ecological fragility, and relentless expansion of desertification. Here, we propose the establishment of a worldwide Semi-arid Ecological Barrier (SAEB) as a proactive measure in response to these challenges to curtail desertification and alleviate extreme events. Beyond its immediate benefits, the SAEB holds significant promise for future global carbon control efforts. This perspective offers a case study exemplifying the principles of ecological civilization, focusing on preventing desertification in the Yellow River Basin. Policy of ecological recover, such as the ��Grain for Green�� project in China, has shown to be effective in strengthening the SAEB. It contributes valuable insights into innovative strategies for addressing water scarcity, ecological fragility, and desertification expansion.</p>

Is Abandoned Cropland Continuously Growing in China? Quantitative Evidence and Enlightenment from Landsat-Derived Annual China Land Cover Dataset

Abandoned cropland is a great waste of land resources, which not only affects the stability of food production, but also wastes limited cropland resources. China has large areas of abandoned cropland, and accurately extracting the large-scale abandoned cropland is a prerequisite for the government to implement reclamation policies and estimate the food production potential of abandoned cropland. China has implemented the Grain for Green Project (GGP) since 1980, but most research has not considered its impact on the extraction of abandoned cropland. Therefore, a method was proposed to identify abandoned cropland excluding the regions of GGP, and to analyze the spatio-temporal characteristics and potential of abandoned cropland in China from 1991 to 2018. GGP potential and food production potential of abandoned cropland were discussed. The results showed that 26.47 million hectares of cropland has been abandoned in the past 28 years (including cropland that has been reclaimed). Under the positive influence of the government’s food security policy, the abandoned cropland has decreased in recent years, but the total area is still high. The abandonment mainly occurred in the Jiangnan Hills, the Hilly Regions of Fujian and Guangdong Province, the North China Mountains, and Eastern Inner Mongolia. The higher the elevation and the steeper the slope, the higher the abandonment rate. In addition, the urban-rural income gap significantly affected the abandonment rate. This study drew the spatial and temporal distribution map of abandoned cropland in China with a spatial resolution of 30 m considering GGP. It provides an important basis for formulating reclamation and GGP policy.

The temporal variation of sediment connectivity from 1982 to 2020 in the Wei River basin, China

AbstractSediment connectivity is a valuable metric that characterizes the relationship between sediment transport from the source to the sink, and the ease of sediment erosion. Over the past four decades, changes in land use types and vegetation cover have significantly altered sediment dynamics in the Wei River basin. In this study, we used the index of connectivity (IC) to assess the temporal changes in sediment connectivity at a watershed scale. We employed Landsat images to analyse the relationship between changes in vegetation cover or land use type and sediment connectivity. We used factor detector and interaction detector in Geodetector to analyse the importance and impact of vegetation and slope on IC changes. We assessed the correlation of sediment yield and connectivity to validate our results and it shows that IC has strong or moderate positive correlation with sediment yield from eight out of nine stations in the Wei River Basin. Our findings demonstrate that soil and water conservation measures, as well as the grain for green project, have led to the transformation of cropland and grassland into woodland. This change is reflected in the decrease of the maximum IC value from 6.24 to 5.72 in the Beiluo sub‐basin, indicating a decreasing trend in sediment connectivity. Although the maximum IC value increased from 5.76 to 5.08 in the Jing sub‐basin, driven by human activity, showing an increasing trend. Furthermore, the IC value decreased in the western part of the Wei sub‐basin. Overall, sediment connectivity exhibits a weak decreasing trend in most regions of the Wei River basin, while it shows an increasing trend slightly in the Jing sub‐basin. The correlation coefficients ranged from 0.47 to 0.86, with sediment yield being moderately or strongly correlated with IC. Our study identified vegetation, human activity, and slope as the main influencing factors of IC. The results of factor detector showed that the q value of vegetation was 0.63 and the slope was 0.1, Vegetation played a major role in the change of IC. The results of interaction detector showed that interaction between vegetation and slope was greater than the single factor. The temporal variability of sediment connectivity in the basin provides valuable insights for sediment transport management. Our research highlights the importance of studying sediment connectivity and offers proposals for measures that can be taken to address sediment transport challenges in the Wei River basin.