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China leads in the greening of the world, with a nearly doubled increase in its forest area since the 1980 s revealed by the National Forest Inventory (NFI). However, a significant challenge persists in the absence of consistent and reliable remote sensing data that align with the NFI, hindering a comprehensive understanding of the spatiotemporal patterns of terrestrial ecosystem changes driven by afforestation and reforestation efforts over recent decades in China. Moreover, conventional binary thematic maps and land use and land cover (LULC) maps encounter difficulties in providing a thorough assessment of canopy cover at the subpixel level and trees extending beyond officially designated forest boundaries. This limitation creates substantial gaps in our comprehension of their invaluable contributions to ecosystem services. To confront these challenges, this study presents a systematic framework integrating time-series Landsat satellite imagery and random forest-based ensemble learning techniques. This framework aims to generate China's inaugural annual tree cover dataset (CATCD) spanning from 1985 to 2023 at a 30 m spatial resolution. Evaluation against multisource reference data shown high correlations ranging from 0.70 to 0.96 and reasonable RMSE values ranging from 5.6 % to 25.2 %, highlighting the reliability and precision of our approach across different years and data collection methodologies. Our analysis reveals that China's forested area has doubled, expanding from 1.04 million km2 in 1985 to 2.10 million km2 in 2023. Notably, 33 % of this growth can be attributed to a shift from non-forest to forest land categories, primarily observed in the three-north and southwest regions. However, the majority, contributing 67 %, results primarily from crown closure in central and southern China. This realization underscores the limitations of conventional binary thematic maps and LULC maps in accurately quantifying forest gain in China. Furthermore, China's tree population structure has undergone a transformative shift from 83 % forest trees and 17 % non-forest trees in 1985 to 92 % forest trees and 8 % non-forest trees in 2023, signifying a transition from afforestation to established forests. Our study not only enhances the understanding of tree cover variations in China but also provides valuable data for ecological investigations, land management strategies, and assessments related to climate change. [ABSTRACT FROM AUTHOR]

The Grain for Green Program and soil and water conservation engineering initiatives are crucial for controlling erosion in steep-slope agriculture. However, it is still unclear how these two management methods should be carried out in respect to the situation in mountainous areas. Therefore, taking a typical mountainous area in southwest China as an example, we simulated six scenarios in order to compare the food provisioning service (FPS) and soil conservation service of the Grain for Green Program (converting to grassland) and Construction Measures (converting to sloping terrace) under different slopes. Results showed that when farmland with a >25° slope was converted into grassland, the amount of soil erosion (M) decreased by 21.0%, while FPS decreased by only 0.7%. However, when farmland with a >25° slope was converted into sloping terrace, M decreased by 31.3% while FPS increased by 18.7%. With the increases of farmland slope ranges in the Construction Measures scenario, M gradually decreased and FPS gradually increased. Particularly when farmland >15° was converted into sloping terrace, M decreased by 63.9% and FPS increased by 52.7%. Furthermore, the trade-offs of Construction Measures are lower than that of Grain for Green on different slope ranges. Therefore, we conclude that Construction Measures are a more suitable method in mountainous areas than the Grain for Green, and we suggest that further research be conducted to consider the ecological risks of construction engineering measures.

The Grain for Green (GfG) program is an afforestation project created by the Chinese Government to protect the environment. Farmers who participate in GfG return farmland to forest. Losing arable land means losing an income source, so farmers have to reorient their livelihood strategies, leading to potential changes in the gender division of labor. To assess gender differences in the impact of policies, we use indicators from the Women's Empowerment in Agriculture Index (WEAI), which measures the status of women relative to that of men. Using sex-disaggregated data from farmers in mountainous areas of northeast China and applying the inverse probability weighted regression adjustment (IPWRA) estimator, we found that the status of men and women had increased with GfG participation, but women's status had improved more than men's. However, this was not because of their smooth participation in the program, but because of its challenges. Their decision-making skills improved unexpectedly due to pressure to protect their interests. Rural women worried about their families' livelihoods, so they tried to improve their family welfare and diversified their income sources. In this process, women had more interactions with outside communities. Our results underline the strong need to continuously monitor the gender impacts of environmental policies. [ABSTRACT FROM AUTHOR]

Ecological resilience is one of the most compelling issues in the current research field, which aims to explore how to address environmental challenges such as climate change, natural disasters and ecological risks. As the main carrier of ecological development, it is of great significance to improve the ecological resilience of river basin for regional green high quality development. From the perspective of spatial-temporal characteristics of landscape ecological resilience, the changing mechanism of ecological resilience level in Jinghe river basin was explored. Based on SWAT model, CASA model and InVEST model, the ecosystem services and trade-offs(EST)model evaluated the basin ecosystem services, and considered the landscape pattern characteristics; the basin ecological resilience assessment model was constructed and the spatial-temporal characteristics of ecological resilience in Jinghe river basin were revealed. The results show that from 2000 to 2020, the ecological resilience of all sub-basins in Jinghe river basin continues to increase. Compared with the situation in 2000, all sub-basins exceed the low resilience level in 2020, and 44.55% of the area in Jinghe river basin is transferred from the low resilience level, and 12.59% of the area is converted to the high resilience level. Ecological resilience is fluid and can have beneficial effects in other regions. The improvement of ecological resilience is based on the ecological resilience hotspots of Liupanshan and Ziwuling forest areas, radiating to the entire river basin. The ecological resilience pattern gradually decreases from the south to the north of the basin, and similar “high→low→high” pattern appears from the southern part of the basin to the east and west, and the ecological resilience level of the basin shows a significant upward trend. Although the southern part of the basin maintains high ecosystem services, it has low ecological stability due to the expansion of building land and unreasonable landscape structure. In general, the grain for green in Jinghe river basin in the past 20 years is beneficial to the improvement of ecosystem services and has a positive impact on the ecological resilience of the river basin. [ABSTRACT FROM AUTHOR]

【Objective】On the occasion of the implementation of the policy of returning farmland to forest for 20 years, the dynamic changes of soil aggregates and soil organic carbon (SOC) after returning farmland to forest in upper reaches of the Minjiang River were quantitatively studied, which provided scientific data support for ecological governance and ecological agriculture development in arid valleys.【Method】Taking the native forest as the control and the ecological forests (eco-forests) and orchards (cherry, crisp plum, apple) as research objects, the particle size composition, stability and SOC distribution of soil water-stable aggregates of various land types were analyzed, and the mixed effect was applied to determine the contribution of forest land type, soil depth, altitude gradient, gravel content (GC) and other factors to soil aggregate stability and organic carbon dynamics.【Result】The content of macro-aggregates (> 0.25 mm) in orchards was significantly lower than that in eco-forests, and that in both was significantly lower than that in native forests. The contents of soil agglomerates of various sizes in the native and eco-forests showed as: 5-10 mm > 2-5 mm > 0.25-2 mm > 0.053-0.25 mm > 0-0.053 mm, those in the orchards ranked as: 0.25-2 mm > 2-5 mm > 5-10 mm > 0.053-0.25 mm > 0-0.053 mm. In the 5-15 cm soil layer, the contents of 5-10 mm and 2-5 mm agglomerates in cherry orchards were significantly greater than those in crisp plum orchards and apple orchards. Soil aggregate stability indexes(MWD and GMD) showed as: native forests > eco-forests > cherry orchards > crisp plum orchards and apple orchards, and there were no significant differences between crisp plum orchards and apple orchards. The SOC content(SOCC) in the 0-5 cm soil layer showed as native forests > eco-forests > cherry orchards > crisp plum orchards and apple orchards, and the difference showed a decreasing trend with the increase of soil depth. SOC(SOCS) stocks at a depth of 0-30 cm were highest in eco-forests (63.1 t/hm2), followed by cherry orchards (56.1 t/hm2), apple orchards (52.5 t/hm2), and crisp plum orchards (51.3 t/hm2), while the SOCS in native forests were the lowest (47.3 t/hm2). At a dep th of 30-60 cm, cherry orchards had the highest SOCS (40.3 t/hm2), followed by crisp plum orchards (32.9 t/hm2), and apple orchards (2 9.3 t/hm2), and eco-forests had the l owest SOCS (24.7 t/hm2). SOC distribution was characterized as 'high content and low stock' in native forests, 'high content and high stock' in eco-forests, and 'low content and high stock' in orchards. The dominant factor of soil aggregates stability and organic carbon content was forest type, and the dominant factor of SOCS was soil depth.【Conclusion】The mountain agriculture of 'eco-forests on the higher valley and orchards on the lower valley, fruit trees and cattle on the gentle slopes and terraced fields' is an ideal model for the agriculture development in arid valleys, and the improvement of SOC accumulation in the topsoil should be the priority for the management of orchards in the future.

Since 1999, China has implemented the Grain for Green Project(GFGP), which has significantly changed the vegetation coverage status and land use structure of the Loess Plateau. As a result, vegetation coverage and ecological quality have been greatly improved. However, the spatio-temporal trend of the vegetation coverage is very uncertain, while the comprehensive assessment of its ecological effects has been relatively weak. To this end, two vegetation indices, including normalized difference vegetation index(NDVI)and fractional vegetation cover(FVC), were analyzed, and the changes in vegetation coverage and distribution on the Loess Plateau before and after the implementation of GFGP in the past forty years were reviewed. The results show that ① comparing five common data sets that record the dynamic changes of vegetation coverage, it is found that the data sources affect the authenticity of the eco-environmental benefits' evaluation results to a certain extent; ② the overall vegetation coverage of the Loess Plateau has been increasing in a fluctuating manner over the years, whose growth rate has surged due to the implementation of the project; its spatial distribution decreases from southeast to northwest, and is influenced by the ecosystem pattern, land use type, climate change, etc.; ③ with a rise of vegetation coverage, the water and soil conservation, and carbon sequestration capacity of the Loess Plateau ecosystem also gradually make a build-up, both of which are highly coupled with vegetation changes. According to the current situation of eco-environment management and food production level, it is recommended to strengthen the construction of high-standard farmland to alleviate the problem of arable land shortage caused by GFGP. Meanwhile, it is necessary to accelerate the promotion of ecological value transformation and eco-compensation, so that the lucid water and lush mountains can truly become invaluable assets. [ABSTRACT FROM AUTHOR]

【Objective】 On the occasion of the implementation of the policy of returning farmland to forest for 20 years, the dynamic changes of soil aggregates and soil organic carbon (SOC) after returning farmland to forest in upper reaches of the Minjiang River were quantitatively studied, which provided scientific data support for ecological governance and ecological agriculture development in arid valleys. 【Method】 Taking the native forest as the control and the ecological forests (eco-forests) and orchards (cherry, crisp plum, apple) as research objects, the particle size composition, stability and SOC distribution of soil water-stable aggregates of various land types were analyzed, and the mixed effect was applied to determine the contribution of forest land type, soil depth, altitude gradient, gravel content (GC) and other factors to soil aggregate stability and organic carbon dynamics. 【Result】 The content of macro-aggregates (> 0.25 mm) in orchards was significantly lower than that in eco-forests, and that in both was significantly lower than that in native forests. The contents of soil agglomerates of various sizes in the native and eco-forests showed as: 5-10 mm > 2-5 mm > 0.25-2 mm > 0.053-0.25 mm > 0-0.053 mm, those in the orchards ranked as: 0.25-2 mm > 2-5 mm > 5-10 mm > 0.053-0.25 mm > 0-0.053 mm. In the 5-15 cm soil layer, the contents of 5-10 mm and 2-5 mm agglomerates in cherry orchards were significantly greater than those in crisp plum orchards and apple orchards. Soil aggregate stability indexes(MWD and GMD) showed as: native forests > eco-forests > cherry orchards > crisp plum orchards and apple orchards, and there were no significant differences between crisp plum orchards and apple orchards. The SOC content(SOCC) in the 0-5 cm soil layer showed as native forests > eco-forests > cherry orchards > crisp plum orchards and apple orchards, and the difference showed a decreasing trend with the increase of soil depth. SOC(SOCS) stocks at a depth of 0-30 cm were highest in eco-forests (63.1 t/hm²), followed by cherry orchards (56.1 t/hm²), apple orchards (52.5 t/hm²), and crisp plum orchards (51.3 t/hm²), while the SOCS in native forests were the lowest (47.3 t/hm²). At a dep th of 30-60 cm, cherry orchards had the highest SOCS (40.3 t/hm²), followed by crisp plum orchards (32.9 t/hm²), and apple orchards (2 9.3 t/hm²), and eco-forests had the lowest SOCS (24.7 t/hm²). SOC distribution was characterized as ‘high content and low stock’ in native forests, ‘high content and high stock’ in eco-forests, and ‘low content and high stock’ in orchards. The dominant factor of soil aggregates stability and organic carbon content was forest type, and the dominant factor of SOCS was soil depth. 【Conclusion】 The mountain agriculture of ‘eco-forests on the higher valley and orchards on the lower valley, fruit trees and cattle on the gentle slopes and terraced fields’ is an ideal model for the agriculture development in arid valleys, and the improvement of SOC accumulation in the topsoil should be the priority for the management of orchards in the future. [ABSTRACT FROM AUTHOR]

Decades of reckless deforestation have caused serious soil erosion and land desertification issues in the Loess Plateau (LP). "Grain for Green" Program (GFGP), one of the world's largest ecological restoration projects, is crucial to improve the ecological environment. Previous studies have demonstrated that GFGP lowers soil erosion in the LP. However, there are trade-offs and synergies between ecological services. Does strengthening soil conservation prevent enhancing other ecosystem services? Consequently, can the GFGP improve many ecological services simultaneously? This study compares changes in NDVI prior to and following the implementation of the GFGP in LP to the enhancement of ecosystem services. During the research period, the LP's overall vegetation cover rose significantly, particularly in the GFGP's major counties. Significant improvements were made to ecosystem services such as carbon sequestration, soil conservation, and habitat quality. The GFGP enhanced the synergistic linkages between ecological services. The implementation of the GFGP decreased water yield, suggesting trade-offs with other ecosystem services. Additionally, we investigate regional trade-offs/synergies between ecosystem services and their influencing factors, which were influenced by topographic and climatic variables. To maximize the benefits of ecological restoration efforts, we need a deeper understanding of the relationships between ecosystem services and the mechanisms that drive them. Thus, policymakers can scientifically exert control over local influences on ecosystem services, either by boosting the provision of specific services or by limiting specific influences in order to maintain ecosystem stability. [ABSTRACT FROM AUTHOR]

The water retention service (WRS) in the Yellow River Basin is highly critical for the ecological security in northern China. Since the implementation of Grain for Green project during 2000, the changes of WRS and land cover in the Yellow River Basin have not been fully revealed, which limited the knowledge of how anthropogenic activities affected ecological processes. To address the issue, this study chose the water yield-based parameter correction method, and adopted the Sen’s slope test, Mann-Kendall analysis and Hurst index methods, firstly analyzing the inter-annual WRS changes in the Yellow River Basin from 1990 to 2020. Specifically, a new index, Ecosystem Service Deficit Index was proposed to accurately distinguish the deficit/surplus state of WRS. The results of land cover change showed that from 1990 to 2020, forest and grassland were both increasing at the rate of +556.5 km2/yr and +508.4 km2/yr, respectively, and cropland was decreasing with a trend of −965.5 km2/yr. Temporally, WRS was weakening (−0.03 mm/yr) during 1990–2000 but was strengthening in 2000–2020 (+0.08 mm/yr). Spatially, the decreases of WRS mainly occurred in the downstream, with the detectable increases in the headwaters of upstream and the midstream; it is noteworthy that the spatial increases of WRS was unsustainable in the future because Hurst index was less than 0.45 in the study area. The ecosystem service deficit index clearly revealed that WRS experienced a long (at least for 3/4 of study period) deficit period until 2011, and was capable of accurately distinguishing WRS surplus/deficit. The new index can also be applied to assess other ecosystem services. Overall, the integrated roles of the local Grain for Green practices and climate change contributed to the recovery of WRS in the Yellow River Basin, but this recovery may not last. More active human interventions needed to be implemented to mitigate future WRS degradation risks.

The Grain for Green Project (GGP), which was implemented in China since 1999, has achieved remarkable achievements, but some new issues have gradually emerged, and it is necessary to carry out scientific evaluation and systematic sorting. In order to provide scientific basis for the ecological construction and high-quality development of the Loess Plateau in the new period, this paper comprehensively evaluated and analyzed the achievements and problems of afforestation and grassland construction in Yan' an City after the implementation of GGP, and put forward specific countermeasures and suggestions based on the field investigation and remote sensing image interpretation of typical years from 1990 to 2020. The achievements obtained by the implementation of GGP in Yan' an City are as follows: ecological quality has been improved obviously, land use structure has been adjusted rapidly, agricultural industrial structure has been adjusted, fanners have been lifted out of poverty and become rich, forest and grassland area has been rapidly enlarged and vegetation recovered well. The problems in vegetation construction that Yan' an City currently faced are: vegetation restoration on a large scale has changed surface hydrological processes ( limited precipitation is expended through evapotranspiration, and is not conducive to subsequent stable growth of established vegetation and the ecological service function of continuous play), forest types are single during afforestation, artificial grassland construction scale has limitations, and large area of natural grassland needs to be reasonably explored. Suggestions for vegetation construction in Yan' an City in the future: to carry out comprehensive evaluation and planning of regional agriculture, to strengthen ecological effect monitoring and evaluation of GGP, to optimize forest stand and tree species step by step, to strengthen tending management and rational utilization of natural grassland, and to support and build animal husbandry sustainable development system. [ABSTRACT FROM AUTHOR]

Ecological compensation is an important economic means of water pollution control and quality management, especially for trans-regional rivers with unbalanced economic and social development between upstream and downstream. The Tangbai River Basin (TRB), a watershed crossing Henan province and Hubei province, China, forms one of the nation's most productive agricultural regions. The TRB has been exposed to high doses of fertilizers for a long time. This study simulates hydrologic and nutrient cycling in the TRB using Soil and Water Assessment Tool (SWAT) with limited data available. The results indicate that dryland fields, which constitute 62% of the basin area, produce 80% of total nitrogen (TN) and 85% of total phosphorus (TP) yields of the whole river basin. The water quality of river sections at the provincial boundary shows that only 29% of the time from 2000 to 2019 met the Class III standard regarding TN and TP concentrations, and the concentrations in the spring flood season are approximately three times the mean in the non-flood season. The Grain for Green ecological restoration measure in Henan province shows that restoration of non-flat drylands can reduce nutrient loads at trans-provincial sections by 3.5 times compared to that of slope-independent drylands; however, the water quality compliance rate remains similar. The value of ecological compensation can also vary widely depending on different quantitative criteria. The SWAT-based pollutant quantification method adopted in this study could have implications for ecological compensation in trans-regional rivers. [ABSTRACT FROM AUTHOR]

Decades of reckless deforestation have caused serious soil erosion and land desertification issues in the Loess Plateau (LP). “Grain for Green” Program (GFGP), one of the world’s largest ecological restoration projects, is crucial to improve the ecological environment. Previous studies have demonstrated that GFGP lowers soil erosion in the LP. However, there are trade-offs and synergies between ecological services. Does strengthening soil conservation prevent enhancing other ecosystem services? Consequently, can the GFGP improve many ecological services simultaneously? This study compares changes in NDVI prior to and following the implementation of the GFGP in LP to the enhancement of ecosystem services. During the research period, the LP’s overall vegetation cover rose significantly, particularly in the GFGP’s major counties. Significant improvements were made to ecosystem services such as carbon sequestration, soil conservation, and habitat quality. The GFGP enhanced the synergistic linkages between ecological services. The implementation of the GFGP decreased water yield, suggesting trade-offs with other ecosystem services. Additionally, we investigate regional trade-offs/synergies between ecosystem services and their influencing factors, which were influenced by topographic and climatic variables. To maximize the benefits of ecological restoration efforts, we need a deeper understanding of the relationships between ecosystem services and the mechanisms that drive them. Thus, policymakers can scientifically exert control over local influences on ecosystem services, either by boosting the provision of specific services or by limiting specific influences in order to maintain ecosystem stability.

Ecological compensation is an important economic means of water pollution control and quality management, especially for trans-regional rivers with unbalanced economic and social development between upstream and downstream. The Tangbai River Basin (TRB), a watershed crossing Henan province and Hubei province, China, forms one of the nation’s most productive agricultural regions. The TRB has been exposed to high doses of fertilizers for a long time. This study simulates hydrologic and nutrient cycling in the TRB using Soil and Water Assessment Tool (SWAT) with limited data available. The results indicate that dryland fields, which constitute 62% of the basin area, produce 80% of total nitrogen (TN) and 85% of total phosphorus (TP) yields of the whole river basin. The water quality of river sections at the provincial boundary shows that only 29% of the time from 2000 to 2019 met the Class III standard regarding TN and TP concentrations, and the concentrations in the spring flood season are approximately three times the mean in the non-flood season. The Grain for Green ecological restoration measure in Henan province shows that restoration of non-flat drylands can reduce nutrient loads at trans-provincial sections by 3.5 times compared to that of slope-independent drylands; however, the water quality compliance rate remains similar. The value of ecological compensation can also vary widely depending on different quantitative criteria. The SWAT-based pollutant quantification method adopted in this study could have implications for ecological compensation in trans-regional rivers.

There is debating over the question of whether the large-scale ‘Grain for Green’ program on the Loess Plateau of China threatens regional food security. Self-sufficiency index and cropland pressure index were used to assess food security on the Loess Plateau after the implementation of revegetation program. The results showed that the ‘Grain for Green’ program initially had a considerable impact on regional food security, where grain yield fell from 1999 to 2001, resulting in a lower grain self-sufficiency and increased farmland stress. Subsequently, grain yield in this region increased due to the elevated agricultural material input and increased construction of terraces and check dams. The grain self-sufficiency index would have increased to 96.55% if there were improvements to the agricultural conditions, such as fertilization and irrigation, which would have resulted in an increase in the crop yield per unit of 20%. However, the grain self-sufficiency increased to 105.25% via the construction of terraces and check dams. Thus, the government should further expand the ‘Grain for Green’ program in coordination with improvements to the agricultural production conditions and the construction of terraces and check dams on the Loess Plateau.

Abstract This study selected the Dunhuang city with the unique landscape pattern, its oasis surround by desert, for studying the vegetation change. Based on two period GaoFen-1 images, combined with field survey data, the dimidiate pixel model and fractional vegetation coverage estimation model were applied to detect the changes of local vegetation coverage from July 2013 to July 2015. Analysis showed that during the study years, the Grain for Green project had a remarkable effect on the changes. The vegetation types of intermediate high and very low grades increased by 0.66 and 6.78 km2 respectively. The low vegetation coverage decreased by 23.87 km2. The vegetation coverage types of intermediate grade increased by 88.97 km2 because of the planted forest, which accounted for 10.84% of the study area. The vegetation coverage types of high grade reduced by 72.47 km2. This change effectively prevents the spread of desert and lays a good foundation for the ecological construction of Dunhuang city.

Soil carbon (C) and nitrogen (N) have different responses to different restoration measures. In this paper, surface (0-30 cm) soil C and N densities under different restoration measures in the Sanjiangyuan region were investigated and analyzed. The results showed that although there was no significant difference between rest-grazing (RG) and normal grazing (NG) grassland, SOCD in RG increased by 10.15%, and total N density (TND) increased by 8.56% in the year of the experiment. Compared with cropland, 8 years after Grain for Green (GFG), SOCD increased by 10.49-19.31%, SICD increased by 22.47-54.20%, and TND increased by 1.3-17.45%. Compared with HTT (extreme degradation-black soil beach), 12 years after planting artificial grassland, SOCD increased by 43.97-77.21%, SICD increased by 89.19-716.22%, and TND increased by 49.16-71.40%. Conclusions: Differences in soil types and climatic zones were responsible for the differences in soil C and N in different regions. Short-term grazing rest in Sanjiangyuan region has a certain effect on soil fertility restoration. Implementing the GFG project in the agro-pastoral ecotone improved soil fertility and, concurrently, moderate disturbance should be carried out on the basis of increasing vegetation diversity. Artificial grassland planting on black soil beach can improve soil quality, and moderate grazing disturbance in winter had the best immobilization effect on SIC, while no disturbance in the whole year was beneficial to the accumulation of organic matter. Both biological and abiotic factors have affected soil C and N content and density, but the degree of the influence varied with geographic location. [ABSTRACT FROM AUTHOR]

This paper introduces the second phase of the Grain for Green. The first phase ran from 1999 to 2014, and the second phase started in 2015. The second phase of the GfG (GfG/2) addresses some problems of the first phase (GfG/1), in particular the lack of income for the farmers, as well as some changes to the rural areas, in particular the small number of remaining farmers. The paper describes how the GfG/2 (unlike the GfG/1) encourages farmers to organize themselves in cooperatives, or work with investors, and grow fruit trees to generate sustainable incomes. The paper also describes the constraints that prevent the smooth implementation of the GfG/2, in particular the insufficient financial support, the fact that some of the land that should be converted is "essential farmland", and the small and scattered pieces of farmland. The paper argues that in spite of this, the program is likely to succeed, and help farmers generate sustainable incomes. The paper is based in four periods of fieldwork in Chongqing Municipality, Shaanxi Province, and Yunnan Province and extensive interviews of farmers and government officers. [ABSTRACT FROM AUTHOR]

The aim of China's Grain for Green Program is to reduce soil erosion by subsidizing reforestation of farmland located on steep slopes with low crop productivity. I show theoretically that the incentives created by the program combined with insufficient oversight have led to afforestation of non-sloped highly productive farmland. With a unique land transition dataset, I show that this unintended land use effect has been substantial, amounting to nearly one-fifth of the total amount of cropland converted to forest. This unexpected displacement of highly productive farmland represents a form of slippage/leakage that has not been fully explored in the literature on payment for ecosystem services programs. This form of land displacement is significant in the context of China as well as other countries with limited arable land relative to population size as it can negatively impact national food production targets and self-sufficiency goals. [ABSTRACT FROM AUTHOR]

In order to provide a basis for comprehensive assessment of the ecological effects of large-scale conversion of “Grain for Green” in the Loess Plateau, based on NASA’s MOD16A2 evapotranspiration product (spatial resolution 500 m), this paper analyzed the temporal and spatial variation characteristics of actual evapotranspiration (ET) in the Loess Plateau and typical watersheds in the middle Yellow River from 2001 to 2017. The results show that the annual average ET and the annual average seasonal evapotranspiration of the Loess Plateau are both increased from northwest to southeast. The seasonal evapotranspiration follows the order of summer > autumn > spring > winter; Since the implementation of “Grain for Green”, the annual average evapotranspiration of the Loess Plateau shows an increasing trend of 8.23 mm/a and the annual average evapotranspiration is 277.76 mm; The annual average evapotranspiration shows an increasing trend from 2001 to 2017 for all watersheds in the middle Yellow River and that of the Yanhe River basin increases with average increasing rate of 12.96 mm/a; the annual average evapotranspiration of Huangfuchuan shows more gently increasing trend with average increasing rate of 4.34 mm/a. Among the main tributary catchments, the annual average ET value of Weihe River is the highest (388.26 mm) and that of Huangfuchuan is the lowest (153.71 mm). [ABSTRACT FROM AUTHOR]

To effectively utilize the vegetation on grain-for-green slopes in the wind-water erosion crisscross region, it is necessary to determine the reasonable vegetation utilization intensity. We set up runoff plots on slopes which were not cultivated and were closed for many years in the Liudaogou catchment, a typical catchment in wind-water erosion crisscross region of the Loess Plateau. With artificial simulated rainfall experiments, the characteristics of runoff and sediment yield on slopes (10°, 20° and 30°) under different utilization intensity of vegetation were studied to select the reasonable utilization intensity. The results showed that the runoff rate in the process of rainfall simulation could be divided into two periods; rapidly increasing in the initial period and slow increasing or quasi-steady state in the middle and late periods. The variation of erosion rate during the rainfall was dependent on the slope. The utilization intensity had a significant effect on the runoff yield, which increased with the increasing utilization intensities. The slope gradient had a significant effect on the sediment yield, with the variation of sediment yield with slope gradient being; 20°>30°>10°. Compared with the unused (natural) plots, the relative runoff and sediment increased with increasing utilization intensities. Predicted based on the rainfall data, annual soil erosion amount on the slope would be basically lower than the tolerance level of soil loss when the vegetation cover on the slope surface reached 25% in 15 years after abandoning reclamation. More attention should be paid to the restoration and management of vegetation on the slope of 20° in this area. [ABSTRACT FROM AUTHOR]

Satellite remote sensing of vegetation has indicated that vegetation greenness has increased globally. However, the feedback mechanisms of vegetation restoration on eco-hydrological functions remain unclear, especially in fragile ecosystems. In this study, twelve three-dimensional hillslope plots with different vegetation restoration strategies were selected and their surface and subsurface runoff (SR and SSR, respectively) were monitored in the karst region of southwest China. These strategies were classified as either natural restoration (NR) or artificial management methods (PF, planted forest; GL, grassland), using cropland (CL) as a reference. The results showed that vegetation restoration effectively reduced both SR and SSR. Runoff from the three restoration strategies (59–66 mm) was significantly lower than that from the CL (119 mm). All the strategies had lower runoff than that of CL, except for PF, which exhibited higher SR because of its sparse canopy. Vegetation restoration reduced SR by increasing vegetation cover, which can intercept rainwater and weak the contribution (2.9–12.9%) of rainfall intensity to runoff, thereby reducing runoff generated by "infiltration-excess" mechanisms. This decrease in SSR may be due to an increased water storage capacity in the soil-root zone, causing the soil-bedrock interface to require more rainwater to "fill" and then "spill" to form lateral SSR during the rainfall events. These findings demonstrate that both canopy interception and root-soil interactions contribute to the improvement in hydrological function after vegetation restoration. Among the environmental factors contributing to runoff variation, soil depth was identified as the most crucial (51% of the variance) and showed a positive and negative correlations with SR and SSR, respectively. Consequently, restoration strategies with higher rainwater retention capacity can be selected to reduce SR losses, especially in areas with deeper soil layers. Accordingly, this study reveals that vegetation restoration reduces runoff and highlights the influence of soil depth in karst areas of southwest China. • Runoff with restoration strategies was lower than that of cropland. • Vegetation restoration weakens rainfall intensity's contribution to runoff. • Vegetation restoration reduced runoff generated by infiltration-excess mechanisms. • Soil depth contributes to 51% of the explained variability in runoff. [ABSTRACT FROM AUTHOR]

Reasonably assessing the effectiveness of government expenditure on the Grain for Green project (GFG) in providing forest carbon sequestration would contribute to the development of China’s forest carbon sequestration. Using the government expenditure data from the GFG in Yunnan Province from 2001 to 2015 and the MODIS Land Cover Type (MCD12Q1) time-series datasets, we calculated the forest carbon sequestration of various counties (cities or districts). The impacts of GFG government expenditure on forest carbon sequestration were empirically evaluated by the least squares dummy variables method (LSDV). The research results indicate that a 1% increase in government expenditure on the GFG yielded a 0.0364% increase in forest carbon sequestration. However, the effects of GFG government expenditure on forest carbon sequestration differed greatly in different areas because of the diversity of the natural environments, forest resource endowment, and government policies. If the initial forest endowment was not considered, the effectiveness of government expenditure on the GFG in providing forest carbon sequestration would have been overestimated. This study argues that, to improve the efficiency of GFG government expenditure in Yunnan Province, more investment should be made in regions with positive regression coefficients that have passed the significance t-test, such as Diqing Tibetan Autonomous Prefecture in the northwest, Baoshan City in the west, Honghe Hani and Yi Autonomous Prefecture in the south, and Wenshan Zhuang and Miao Autonomous Prefecture in the east.

Abstract: The Grain for Green Program (GGP) was the most all‐embracing program of ecological reconstruction implemented in China. To estimate carbon storages and carbon sequestration potentials of the GGP forests, the study presented in the paper collected data spanning from 1999 to 2010, such as tree species, tree planting area relevant to the GGP, empirical growth curves suitable for different planted tree species in China, as well as wood density (WD), biomass expansion factor (BEF), carbon fraction (CF) of different trees species, and estimated the carbon storages of the biomasses of GGP forests from 1999 to 2050. It showed that the total carbon storage of the biomass of GGP forests was 320.29 Tg upon the GGP completion in 2010; the total carbon sequestration is higher during the early GGP‐implementation stage than at the late GGP‐implementation stage, and the annual mean carbon sequestration of GGP forests was 26.69 Tg/year. The potential of GGP forests as carbon sink presented an increasing increment. In China, the potential increments of GGP forests as carbon sinks were estimated to be 397.34, 604.00, 725.53, and 808.90 Tg in 2020, 2030, 2040, and 2050, respectively, and the carbon sequestration rates were 1.72, 0.89, 0.52, and 0.36 Mg ha−1 year−1, respectively, corresponding to 2010s, 2020s, 2030s, and 2040s. Therefore, the GGP forests had bigger carbon sequestration capacities and potentials in China. [ABSTRACT FROM AUTHOR]

Understanding the relationship between land use change and ecosystem services is critical for achieving sustainable ecosystem services and for developing scientifically effective eco-conservation policies. The Zhifanggou watershed is a typical hill and gully region on the Loess Plateau that has experienced a process of serious damage and rapid recovery in recent decades, and the accompanying land use changes have been dramatic. Taking the Zhifanggou watershed as an example, this study built an energy flow model for the watershed considering croplands, woodlands and grasslands as components. This study evaluated the changes in ecosystem service values before and after the implementation of a Grain for Green (GFG) program using the method of equivalent value factor per-unit of ecosystem area. Then changes in ecosystem service values in the Zhifanggou watershed were simulated. The results were as follows: (1) the total value of ecosystem services showed a linear increase ( P  < 0.01) from 1995 to 2010, increase 44.2% over this time. In addition, the provisioning, regulating, supporting and cultural service values showed a cooperative growth trend ( P  < 0.01). (2) The change in ecosystem service values in the watershed was very small over the period examined and if the GFG program continues, it will stabilize after a slight net increase. Provisioning services showed a downward trend, while regulating, supporting and cultural services show an upward trend, furthermore, provisioning services showed a trade-off relationship with the other three services ( P  < 0.01). (3) If the cycle of deforestation and reclamation to agriculture continues, the ecosystem service values will decrease by approximately 83% in the next 30 years, the ecosystems will be seriously damaged again, and the values of all four types of ecosystem services will show a decreasing trend ( P  < 0.01). In general, the ecological environment of the Zhifanggou watershed has been stabilized by the Grain for Green program. However, the government’s scientific and rational policies to ensure that the GFG program results are not destroyed and to achieve stable and sustainable development on the Loess Plateau are still needed. [ABSTRACT FROM AUTHOR]

This study selected the Dunhuang city with the unique landscape pattern, its oasis surround by desert, for studying the vegetation change. Based on two period GaoFen-1 images, combined with field survey data, the dimidiate pixel model and fractional vegetation coverage estimation model were applied to detect the changes of local vegetation coverage from July 2013 to July 2015. Analysis showed that during the study years, the Grain for Green project had a remarkable effect on the changes. The vegetation types of intermediate high and very low grades increased by 0.66 and 6.78 km2 respectively. The low vegetation coverage decreased by 23.87 km2. The vegetation coverage types of intermediate grade increased by 88.97 km2 because of the planted forest, which accounted for 10.84% of the study area. The vegetation coverage types of high grade reduced by 72.47 km2. This change effectively prevents the spread of desert and lays a good foundation for the ecological construction of Dunhuang city. [ABSTRACT FROM AUTHOR]

China’s Conversion of Cropland to Forests Program (CCFP) is the world’s largest afforestation-based Payments for Ecosystem Services (PES) program, having retired and afforested over 24 million ha involving 32 million rural households. Prior research has primarily focused on the CCFP’s rural welfare impacts, with few studies on program-induced environmental improvements, particularly at the household level. In this study, data from a 2010 survey covering 2808 rural households from across China was analyzed using an interval regression model to explain household-reported survival rates of trees planted on program-enrolled cropland. In addition to household-level factors, we explore the influence of local conditions and institutional configurations by exploiting the wide diversity of contexts covered by the data set. We find that households with more available labor and more forestry experience manage trees better, but that higher opportunity costs for both land and labor have the opposite effect. We also find that the local implementation regime- e.g., the degree of prior consultation with participants and regular monitoring - has a strong positive effect on reported survivorship. We suggest that the level of subsidy support to participating households will be key to survivorship of trees in planted CCFP forests for some time to come.

Context: Recent conceptual developments in ecosystem services research have revealed the need to elucidate the complex and unintended relationships between humans and the environment if we are to better understand and manage ecosystem services in practice. Objectives: This study aimed to develop a model that spatially represents a complex human-environment (H-E) system consisting of heterogeneous social-ecological components and feedback mechanisms at multiple scales, in order to assess multi-dimensional (spatial, temporal, and social) trade-offs in ecosystem services. Methods: We constructed an agent-based model and empirically calibrated it for a semi-arid region in Northeast China, and examined ecosystem service trade-offs derived from the Sloping Land Conversion Program (SLCP), which is based on payment for ecosystem services. This paper describes our model, named Inner Mongolia Land Use Dynamic Simulator (IM-LUDAS), using the overview, design concepts, and details + decision (ODD + D) protocol and demonstrates the capabilities of IM-LUDAS through simulations. Results: IM-LUDAS represented typical characteristics of complex H-E systems, such as secondary and cross-scale feedback loops, time lags, and threshold change, revealing the following results: tree plantations expanded by the SLCP facilitated vegetation and soil restoration and household change toward off-farm livelihoods, as expected by the government; conversely, the program caused further land degradation outside the implementation plots; moreover, the livelihood changes were not large enough to compensate for income deterioration by policy-induced reduction in cropland. Conclusions: IM-LUDAS proved itself to be an advanced empirical model that can recreate essential features of complex H-E systems and assess multi-dimensional trade-offs in ecosystem services. [ABSTRACT FROM AUTHOR]

As an important target province for implementation of the Grain for Green Program (GGP) in China, the carbon storage and carbon sequestration potential in living tree biomass and soil organic carbon under the GGP in Henan Province were estimated. In this study, we compiled the planted area for different tree species under the GGP in Henan Province during 200–2012 by using empirical growth curves and some parameters to estimate the carbon stock in the living tree biomass from 2000 to 2060. The empirically-based equation for the change in soil organic carbon (SOC) under China’s GGP was applied to estimate the carbon stock change in SOC for Henan Province. The total carbon storage under the Henan Province’s GGP was 51.73 Tg in 2012. The total carbon storage of the later period (2007–2012) was greater than that of the earlier period (2000–2006), and the annual mean carbon sequestration was 1.63 Tg yr −1 from 2000 to 2012. The carbon sequestration potential in the south zone was higher than that of other zones in Henan Province. The potential increments of carbon sink of the GGP in Henan Province are expected to reach 54.05 Tg, 104.23 Tg, 129.23 Tg, 136.97 Tg and 139.35 Tg in 2020, 2030, 2040, 2050 and 2060, respectively. Therefore, Henan Province’s GGP has a large carbon sequestration function and potential. [ABSTRACT FROM AUTHOR]

Soil water is a key limiting factor for plant growth, species richness, primary productivity and grassland stability in arid and semi-arid area all over the world. Root system is the linkage between vegetation and soil for material circulation and energy transformation. Since the Chinese government implemented “Grain for Green” project in 1999, lots of annual croplands was converted to perennial native vegetation, which had significantly altered the eco-hydrological cycle in the Loess Hilly Region. The evaluations of root morphology and water-using characteristics of different vegetation abandoned from croplands are benefit to understand the effect of different vegetation communities on hydrologic cycle and provide theory guidance for vegetation restoration in semi-arid area. In this study, soil and root samples of 5 differents vegetation communities (Artemisia capillaris, A. sacrorum, Bothriochloa ischaemun, Lespedeza davurica and Pinus tabulaeformis) were collected in dry and wet seasons of 2015 in Wangmaogou watershed of Wuding River. The root morphological structures and signatures of stable isotopes were determined by using stable isotope technology. Each vegetation communities was arranged in the 2-3 plots as repeat, arranged 2 plots in Artemisia capillaris, A. sacrorum, Bothriochloa ischaemun and Lespedeza davurica, respectively, arranged 3 plots in Pinus tabulaeformis. Then 5 quadrats were established in each kind of plots. Ensured the same distances between collection points and the shrubs or trees when sampling in Lespedeza davurica or Pinus tabulaeformis, and to avoid the error caused by the different horizontal distances from the stems of the plant (For examples, root biomass, soil water contents, etc.). The results showed that the RLDs (Root length densities) of A. capillaris, A. sacrorum, B. ischaemun, L. davurica and P. tabulaeformis in dry season (16.3, 21.7, 17.3, 17.3, 6.0 mm/cm3) were 9.4, 10.2, 5.3, 2.9 and 1.4 times compared that in wet season (1.7, 2.1, 3.2, 5.9, 4.2 mm/cm3), respectively. The root systems of A. capillaris, A. sacrorum, B. ischaemun were more sensitive to seasonal variations of soil water than L. davurica and P. tabulaeformis. The soil water contents and δ18O of soil water in the surface soil layers were obvious difference between dry and wet season. A. capillaris could only use the soil water from 0-10 cm layer, and A. sacrorum, B. ischaemun mainly absorbed the soil water from 30-40 cm layer during the dry season, while the layers of soil water were moved up to 0-10 and 10-20 cm layers in wet season, respectively. L. davurica and P. tabulaeformis mainly used the soil water from below 60 cm layers in dry season, and absorbed soil water from 20-40 cm layer in wet season. In conclusions, the strategies of soil water uptake were significant difference between dry season and wet season. The root systems used soil water from deeper soil layers in dry season and more closer to surface layers in wet season. These results demonstrated that the changes of soil water and root systems distribution were consistent with the seasonal variation in water uptake patterns estimated by using stable isotope. The results of the present research can provide technical support for vegetation restoration and eco-hydrological process in the Loess Hilly Region. [ABSTRACT FROM AUTHOR]

• Inter-annual changes in land cover and water retention service (WRS) were revealed. • WRS was increased in the recent 30 years in the Yellow River Basin. • Climate change and vegetation are the main drivers affecting WRS. • A new index indicated a prolonged deficit of WRS before 2011. The water retention service (WRS) in the Yellow River Basin is highly critical for the ecological security in northern China. Since the implementation of Grain for Green project during 2000, the changes of WRS and land cover in the Yellow River Basin have not been fully revealed, which limited the knowledge of how anthropogenic activities affected ecological processes. To address the issue, this study chose the water yield-based parameter correction method, and adopted the Sen's slope test, Mann-Kendall analysis and Hurst index methods, firstly analyzing the inter-annual WRS changes in the Yellow River Basin from 1990 to 2020. Specifically, a new index, Ecosystem Service Deficit Index was proposed to accurately distinguish the deficit/surplus state of WRS. The results of land cover change showed that from 1990 to 2020, forest and grassland were both increasing at the rate of +556.5 km2/yr and +508.4 km2/yr, respectively, and cropland was decreasing with a trend of −965.5 km2/yr. Temporally, WRS was weakening (−0.03 mm/yr) during 1990–2000 but was strengthening in 2000–2020 (+0.08 mm/yr). Spatially, the decreases of WRS mainly occurred in the downstream, with the detectable increases in the headwaters of upstream and the midstream; it is noteworthy that the spatial increases of WRS was unsustainable in the future because Hurst index was less than 0.45 in the study area. The ecosystem service deficit index clearly revealed that WRS experienced a long (at least for 3/4 of study period) deficit period until 2011, and was capable of accurately distinguishing WRS surplus/deficit. The new index can also be applied to assess other ecosystem services. Overall, the integrated roles of the local Grain for Green practices and climate change contributed to the recovery of WRS in the Yellow River Basin, but this recovery may not last. More active human interventions needed to be implemented to mitigate future WRS degradation risks. [ABSTRACT FROM AUTHOR]

Knowledge of the changes of soil properties and soil particle-size distribution (PSD) is important for quantifying soil quality and dynamics during natural succession. We applied multifractal theory to characterize the PSDs in five soil layers of nine croplands abandoned for less than 1 year, 2, 5, 7, 10, 15, 20, 30 and 35 years and evaluated the changes of soil organic carbon (SOC), total nitrogen (total N), total phosphorus (total P), soil texture and multifractal parameters [capacity dimension ( D ), entropy dimension ( D ), correlation dimension ( D ) and Hölder exponent of order zero ( α )] during natural succession on the Loess Plateau of China. Rényi spectra ( D ) and singularity spectra f( α) characterized the PSDs well and sensitively reflected the changes of heterogeneity of the surface soil (0-20 cm) during natural succession. SOC, total N and clay contents and the multifractal parameters increased significantly by the late stage of succession, mostly in the topsoil (0-10 cm). Natural succession thus effectively improved the soil physicochemical properties on the Loess Plateau of China, even though it was time-consuming. SOC and total N contents decreased with depth throughout the natural succession, but the multifractal parameters were higher in the topsoil only in the late stage. D and D were strongly and positively correlated with SOC and total N contents in the surface layers and with fine particles in all layers, suggesting that D and D may be sensitive and practical indices for quantifying changes in soil properties and erosion. [ABSTRACT FROM AUTHOR]

Background: Farming on sloping lands has historically led to forest loss and degradation in China, which coupled with unsustainable timber extraction activities, was deemed responsible for catastrophic flooding events in the late 1990s. These events led to the introduction of forest policies targeting ecological conservation and rural development in China, a process epitomized by the launch of the conversion of cropland to forest program (CCFP) in 1999. This systematic review responds to the question: What are the environmental and socioeconomic effects of China’s Conversion of Cropland to Forest Program after the first 15 years of implementation? Methods: Based on the published protocol, we searched for English language studies published between 1999 and 2014, and screened them for relevance and eligibility in two stages (titles and abstracts followed by full texts), after which they were further assessed for potential sources of bias before data extraction and analyses. Following initial screening of 879 titles and abstracts, 169 studies underwent full text screening, followed by 61 studies being subjected to quality assessment. Eighteen papers did not meet minimum quality criteria, while the remaining 43 papers were eligible and underwent data extraction and subsequent analyses. Among the final set of 43 studies were four national-level studies, seven regional-level studies, and 32 county-level (or below) studies. The majority of studies were published after 2009 and evaluated impacts within the first 5 years of CCFP implementation, such that the long-term impacts of the program remain open for further investigation. Results: A skewed temporal and geographic distribution of the examined studies limits the generalizability of the results, though the evidence base confirms a substantial increase in forest cover and associated carbon stocks linked to reallocation of sloping agricultural land to forest. To some degree, soil erosion has been controlled and flood risk reduced at local scales. Meanwhile household incomes have increased and rural employment has readjusted towards off-farm sectors. However, some studies also indicate instances of diminished food security and increasing social inequality. Finally, several studies indicate suboptimal regional or localized trade-offs among specific ecosystem services, including carbon sequestration vs. water discharge rates, flood control vs. riparian soil replacement, and forest productivity vs. biodiversity. Conclusions: Additional research on long-term environmental impacts and program effects in under-studied regions, particularly southern and western provinces, is necessary. In terms of recommendations for future research on the CCFP, there is a significant need to examine confounding factors, ideally through the selection of matching control groups to CCFP participants, and to ensure that sampling methodologies are more representative of selected study sites and the overall targeted area. There remain many opportunities to assess specific socioecological effects, upon which to base future policy decisions and more broadly inform ecological restoration and eco-compensation in both theory and practice. [ABSTRACT FROM AUTHOR]

The Grain for Green (GFG) Project in China is currently the largest environmental rehabilitation project aimed at turning low-yielding farm land to forests and pastures. Such conversion of land use type also promotes remediation of the polluted environment. Soil microbes reflect soil function and are therefore considered an essential component of ecosystem restoration. To evaluate the environmental effects of converting atrazine polluted farmland to secondary forest, we determined soil chemical properties, soil bacterial communities and their responses to three types of land use (primary forest, PF; secondary forest, SF; farm land, FL) in Wuying, China. Our results showed that soil organic matter significantly decreases in the order PF > SF > FL. Bacterial 16S rRNA gene 454 pyrosequencing revealed that the soil bacterial diversity level remained unchanged. However between FL and the two forested sites, we observed an increase of Actinobacteria, β-proteobacteria and Firmicutes; and a decrease of Acidobacteria and Verrucomicrobia, while in SF the bacterial community structure was similar to PF. We conclude that reforestation permits bacterial community, resetting from FL back to a state that resembles natural conditions. In addition, 20 years of natural attenuation degraded soil atrazine residues in SF but traces remained in the soil. Reforestation generally resulted in favorable ecological impacts on soil quality and the bacterial community compared with active farm fields. [ABSTRACT FROM AUTHOR]

Background: Agricultural activities on sloping lands have historically led to forest loss and degradation in China which, coupled with industrial pressures on the environment, were deemed responsible for catastrophic flooding events in the late 1990s. After these events, China's forest policy underwent a significant reorientation towards ecological conservation and rural development, a process epitomized by the Conversion of Cropland to Forest Program (CCFP). Launched in 1999, the CCFP integrates both socioeconomic and environmental objectives with the aim of reforesting smallholder cropland on sloping lands, while compensating farmers with payments for their lost income. Following 15 years of implementation, it is timely to conduct a comprehensive assessment of the state of knowledge about the CCFP's impacts on human populations and the environment. Methods/design: The primary research question asks "What socioeconomic and environmental effects has the Conversion of Cropland to Forest Program had on human populations and land resources during its first 15 years in China?" We use a theory of change and a Population-Intervention-Comparator-Outcome (PICO) framework to structure our systematic review, where populations of interest consist of both human populations and land resources targeted by the program, while the intervention of interest is the CCFP as defined by its component activities, including compensatory subsidies, skill-training, and enforcement with field checks. Outcomes are defined as both the socioeconomic and environmental impacts of the program. We will conduct a search for relevant English and Chinese language literature on Scopus, Web of Science, CAB Abstracts, AGRIS (FAO), and the China National Knowledge Infrastructure. Search results will be screened for relevance in a two stage process (titles and abstracts, followed by full texts) based on predefined eligibility criteria, and then further assessed for potential sources of bias. Extraction of data from those studies that have passed full-text screening will follow a coding protocol based on the PICO framework, and quantitative and qualitative analyses of the extracted data will be conducted and synthesized. Finally, a narrative report will present the findings of the review, alongside a geographic map illustrating the coverage of included studies compared with the actual implementation area of the CCFP. [ABSTRACT FROM AUTHOR]

Background: Agricultural activities on sloping lands have historically led to forest loss and degradation in China which, coupled with industrial pressures on the environment, were deemed responsible for catastrophic flooding events in the late 1990s. After these events, China's forest policy underwent a significant reorientation towards ecological conservation and rural development, a process epitomized by the Conversion of Cropland to Forest Program (CCFP). Launched in 1999, the CCFP integrates both socioeconomic and environmental objectives with the aim of reforesting smallholder cropland on sloping lands, while compensating farmers with payments for their lost income. Following 15 years of implementation, it is timely to conduct a comprehensive assessment of the state of knowledge about the CCFP's impacts on human populations and the environment. Methods/design: The primary research question asks "What socioeconomic and environmental effects has the Conversion of Cropland to Forest Program had on human populations and land resources during its first 15 years in China?" We use a theory of change and a Population-Intervention-Comparator-Outcome (PICO) framework to structure our systematic review, where populations of interest consist of both human populations and land resources targeted by the program, while the intervention of interest is the CCFP as defined by its component activities, including compensatory subsidies, skill-training, and enforcement with field checks. Outcomes are defined as both the socioeconomic and environmental impacts of the program. We will conduct a search for relevant English and Chinese language literature on Scopus, Web of Science, CAB Abstracts, AGRIS (FAO), and the China National Knowledge Infrastructure. Search results will be screened for relevance in a two stage process (titles and abstracts, followed by full texts) based on predefined eligibility criteria, and then further assessed for potential sources of bias. Extraction of data from those studies that have passed full-text screening will follow a coding protocol based on the PICO framework, and quantitative and qualitative analyses of the extracted data will be conducted and synthesized. Finally, a narrative report will present the findings of the review, alongside a geographic map illustrating the coverage of included studies compared with the actual implementation area of the CCFP. [ABSTRACT FROM AUTHOR]

Summary The limitation of soil water in semiarid regions restricts the formation of a good cover of vegetation. The Loess Plateau in China, well known for its severe soil erosion, has a thick loessial soil that holds substantial volumes of water and provides the basis of a sustainable restoration of vegetation. Our limited understanding of the dynamics of deep soil moisture, however, could lead to the mismanagement of soil–water resources or could even misguide the policies of vegetational reconstruction. To evaluate the temporal response of deep soil moisture in different types of revegetation, we observed soil moisture to a depth of 340 cm in four plots, planted with Korshinsk peashrub (KOP), purple alfalfa (ALF), native plants (natural fallow, NAF), and millet (MIL), on 15 measurement events from 2010 to 2012. Our analysis provided four main conclusions. (1) The quantitative difference of potential evapotranspiration and actual precipitation resulted in natural deficits of soil moisture. The dynamics of deep soil moisture, however, were mainly dominated by the type of vegetation. Deep soils in plots of KOP and ALF became drier than the soil in plots of NAF and MIL. (2) Deep soil moisture in KOP and ALF was weakly variable. Correlations of time series of soil moisture between the upper and lower layers tended not to be significant. Dried soil layer, a special hydrological phenomenon, had formed in the plots. (3) The correlation between variances of soil moisture and the corresponding mean values were not always significantly positive due to the influence of vegetational type, observational depth, and date. (4) Fallow may be the best cover for achieving adequate hydrological sustainability of the soil. These results are expected to help improve the understanding of the response of deep soil moisture to vegetational restoration and to provide insight into the dynamics of deep soil moisture influenced by vegetation on loessial slopes. [ABSTRACT FROM AUTHOR]

China's remarkable economic development has been achieved at the cost of its environment. Scholarly attention on international norm diffusion and policy learning asserts that international influence could make a positive impact on China's environmental politics. However, the policy process in China still retains the campaign style, which dates back to Mao's era. This case study of two inland counties in Shaanxi province provides empirical material that partially challenges the so-called international influence approach. County B and W, which were involved in an international forestry cooperation project with the Kreditanstalt fur Wiederaufbau (KFW), both learned from their partner in subsequently implementing the Grain for Green project, but with different levels of learning and, consequently, different institutional changes. The findings based on these two counties indicate an important factor other than the structure of international influence, one which definitely affects policy learning and the resultant changes made by local bureaucrats, namely local learning agents; thus, a locality with a strong local learning agent is more likely to induce learning and substantive institutional changes. The findings also underscore the difficulty in spreading new norms and knowledge from international actors to the Chinese government. The impact of international influence in enhancing domestic governance cannot be taken for granted. [ABSTRACT FROM AUTHOR]

China's Conversion of Cropland to Forests Program (CCFP) is the world's largest afforestation-based Payments for Ecosystem Services (PES) program, having retired and afforested over 24 million ha involving 32 million rural households. Prior research has primarily focused on the CCFP's rural welfare impacts, with few studies on program-induced environmental improvements, particularly at the household level. In this study, data from a 2010 survey covering 2808 rural households from across China was analyzed using an interval regression model to explain household-reported survival rates of trees planted on program-enrolled cropland. In addition to household-level factors, we explore the influence of local conditions and institutional configurations by exploiting the wide diversity of contexts covered by the data set. We find that households with more available labor and more forestry experience manage trees better, but that higher opportunity costs for both land and labor have the opposite effect. We also find that the local implementation regime- e.g., the degree of prior consultation with participants and regular monitoring - has a strong positive effect on reported survivorship. We suggest that the level of subsidy support to participating households will be key to survivorship of trees in planted CCFP forests for some time to come. [ABSTRACT FROM AUTHOR]

Abstract: Soil aggregate stability influences several aspects of soil physical behavior, such as water infiltration and soil erosion (Amézketa, 1999). We investigated the soil aggregate stability characteristics in the framework of the ‘Grain for Green’ vegetation rehabilitation project at the Loess Plateau (China) by using the Le Bissonnais (1996) and the modified Yoder (1936) methods. Both non-grazed grassland and afforestation revegetations were considered. The size distribution mode was always >2mm for the fast wetting test (FW) in the non-grazed grassland communities. This fraction accounted for approximately 40% to 80% of the total soil weight. The wet stirring (WS) test showed a distribution similar to that determined by the FW test. For the slow wetting (SW) test, 80% or more of the non-grazed grassland soil fragments was >2mm. The mean weighted diameter (MWD) that was determined by the Le Bissonnais' method was different among the tests and land uses. For the FW test, all the plant communities were significantly different from that of the recently abandoned grazing on grassland at the 0–20 and 20–40cm depths. In the Artemisia sacrorum community, the maximum MWD was approximately 3mm for the 0–20cm depth. There were no significant differences among the plant communities after 3years of afforestation and 7years of non-grazing of the grassland. The MWDs were lower in the afforestation area than in the non-grazed grassland area. The maximum MWD value from the FW test was approximately 1.8mm and was significantly lower (<0.5mm) for cropland. The MWD of the modified Yoder method was positively related to the slow wetting and wet stirring (WS) tests of the Le Bissonnais' method (n=20 and r=0.83 and 0.87, respectively). In the Loess Plateau, revegetations by non-grazed grassland and afforestation are efficient means of increasing aggregate stability and decreasing soil erodibility. The aggregate stability under non-grazed grasslands is higher than that under afforestation. The effect of revegetation is persistent, which makes it a suitable long-term management practice. Compared with the modified Yoder's method, the FW test of the Le Bissonnais' method is better at determining aggregate stability differences among land uses and is recommended for future studies. [Copyright &y& Elsevier]

The changes in cropland quantity and quality due to land use are critical concerns to national food security, particularly for China. Despite the significant ecological effects, the ecological restoration program (ERP), started from 1999, has evidently altered the spatial patterns of China's cropland and agricultural productivity. Based on cropland dynamic data from 2000 to 2008 primarily derived from satellite images with a 30-m resolution and satellite-based net primary productivity models, we identified the impacts on agricultural productivity caused by ERP, including 'Grain for Green' Program (GFGP) and 'Reclaimed Cropland to Lake' (RCTL) Program. Our results indicated that the agricultural productivity lost with a rate of 132.67×10 t/a due to ERP, which accounted for 44.01% of the total loss rate caused by land use changes during 2000-2005. During 2005-2008, the loss rate due to ERP decreased to 77.18×10 t/a, which was equivalent to 58.17% of that in the first five years and 30.22% of the total loss rate caused by land use changes. The agricultural productivity loss from 2000-2008 caused by ERP was more attributed to GFGP (about 70%) than RCTL. Although ERP had a certain influence on cropland productivity during 2000-2008, its effect was still much less than that of urbanization; moreover, ERP was already converted from the project implementation phase to the consolidation phase. [ABSTRACT FROM AUTHOR]

This research attempts to model the complexity of planting trees to increase China''s CO2 sequestration potential by using a GIS-based integrated assessment (IA) approach. We use the IA model to assess the impact of China''s Grain for Green reforestation and afforestation program on farmer and state incomes as well as CO2 sequestration in Liping County, Guizhou Province. The IA model consists of five sub-models for carbon sequestration, crop income, timber income, Grain for Green, and carbon credits. It also includes a complementary qualitative module for assessing program impacts by gender and ethnicity. Using four scenarios with various assumptions about types of trees planted, crop incomes by township, CO2 credit prices, state subsidies, methods for estimating carbon sequestered, and harvesting of trees, we find great variation in the impact of the Grain for Green program on incomes and on carbon sequestered over a 48 year period at both the county and township levels. [Copyright &y& Elsevier]

Abstract: China is facing increased environmental pressures as its economy rapidly develops, with shortages of water potentially limiting development—especially in its dryer north and west. The highly erodible Loess Plateau in the Yellow River Basin is the main source of high sediment loads resulting in poor water quality. Engineering and re-vegetation measures have been (and are being) widely implemented to reduce these environmental problems, but it has since been found that re-vegetation activities result in a decrease of streamflow. Given that water resources are currently over allocated in the Yellow River Basin (as seen by the river increasingly not reaching the sea), the external hydrological impacts from current and planned re-vegetation activities need to be taken into account by a wide range of natural resources managers and policy makers. To increase the awareness of the hydrology-landuse change implications in the region, a decision support tool called Re-Vegetation Impacts on Hydrology (ReVegIH) has been developed. To maximize use of the tool, the design of ReVegIH has been participatory with the final design of the functionality actively taking account of user requirements and needs. ReVegIH provides a means for users to: (1) determine where priority (and target) re-vegetation activities should be undertaken; (2) ascertain what species are suitable for a specific location; (3) simulate the related hydrological impact on an average annual basis. The spatial resolution of the first two functions is provided at 100m, while the third is at the catchment (or county) level for the 113,000km2 study site, called the Coarse Sandy Hilly Catchment, which drains the main south flowing branch of the Yellow River. ReVegIH assesses afforestation impacts on average annual streamflow via application of an aerial-weighted evapotranspiration model operating at steady-state forced by long-term (21-year) annual average meteorological data and landuse scenarios. ReVegIH does not consider the changes in annual streamflow following observed 21-year trends of annual precipitation and pan evaporation data, nor as a function of time since afforestation, and the ability to simulate the hydrological impact due to establishing plantations in different areas in the landscape through time is not included. [Copyright &y& Elsevier]

Summary: This paper examines the conflict that may exist between conservation and food security. In China, policymakers and scholars are debating whether or not conservation set-aside programs threaten food security. To address the debate, we describe China’s conservation set-aside program known as Grain for Green and compare it with similar programs outside of China. We then use data that we collected to measure the production and price impacts of the program on China’s grain economy since 1999. Our simulations find that Grain for Green has only a small effect on China’s grain production and almost no effect on prices or food imports. [Copyright &y& Elsevier]

• Trade-offs and synergies among ecosystem services were simulated under the Grain for Green Program scenario and the agricultural development scenario. • Trade-offs of ESs does not increase but decrease under agricultural development scenario, and farmers' livelihood can also be guaranteed. • It is of great significance to realize the win-win situation of regional ecological and resource demand to find the most suitable development direction in the region. To restore China's degraded environment and improve ecological balance, the government launched a land use policy known as the Grain for Green Program (GFGP), which is the largest ecological construction project in China or anywhere else. It has greatly increased the vegetation cover on the Loess Plateau but occupied the space of agricultural development (AD) over the years. Research on the impact of policy implementation on ecosystem services (ESs) and their trade-offs can support scenario analyses that provide realistic guidance for decision makers to formulate future regional ecological restoration planning. Our focus is Ningwu County and Jingle County on the Loess Plateau, a typical ecologically fragile and impoverished area where expansion of vegetation cover has driven extensive loss of farmland and its benefits to farmers. In this study, soil conservation (SC), water yield (WY), habitat quality (HQ), and food supply (FS) were selected to assess the change of ESs and their trade-offs in different scenarios that represent ecological restoration and land reclamation policies. The results revealed that overall ESs had the largest increase but there were more trade-offs among ESs under the GFGP scenario. For a single ESs, SC and HQ were increased while FS and WY were decreased under the GFGP scenario. From the view of trade-offs, the GFGP scenario exhibited more trade-offs than the AD scenario. Furthermore, compared to the GFGP scenario, the numbers of sub-watersheds with trade-offs of ESs decreased under the AD scenario. With more concern about the contradiction between implementing GFGP and protecting farmland, we confirm that it is extremely unwise to incessantly implement GFGP to improve overall ESs without considering the trade-offs among ESs. Given the certain sub-watersheds mainly developing agriculture, the AD scenario appears to best reduce trade-offs among ESs and ensure the improvement of ESs. Therefore, it is of great significance to realize the win-win situation of regional ecological and resource demand to find the most suitable development direction in the future. [ABSTRACT FROM AUTHOR]

Soil respiration is a large carbon flux from terrestrial ecosystems to the atmosphere, and small variations in soil respiration can prominently influence the global carbon (C) cycle. The vegetation changes could directly affect soil respiration. The large-scale "Grain for Green" project carried out on the Loess Plateau, China has importantly affected the contribution of soil respiration to atmospheric carbon dioxide (CO 2). Therefore, it is important to study the effects of vegetation restoration on soil respiration. We selected four land-use types: crop, forest, shrub, and grassland in the Zhifanggou watershed to analyze variation in soil respiration during dry and rainy seasons. Furthermore, the source of CO 2 emissions from soil respiration was identified using isotopes. The results showed that soil respiration in the rainy season was significantly higher than that in the dry season (P <.05). Soil respiration in the dry season was as follows: shrubland (1.04 μmol m−2 s−1) > cropland (0.72 μmol m−2 s−1) > forestland (0.44 μmol m−2 s−1) > grassland (0.33 μmol m−2 s−1). However, grass and forestland had significantly higher soil respiration than shrub and cropland in the rainy season (P <.05). Roots were the main source of soil respiration in cropland, which contributed >70% of CO 2 emissions. Following revegetation, litter contributed more to soil respiration than roots or soil microorganisms at >68% of soil respiration. Our results provide a theoretical basis for assessing C balance in terrestrial ecosystems. Unlabelled Image • Soil respiration in the rainy season was higher than that in the dry season. • Vegetation restoration increased soil respiration in the rainy season. • Roots were the main source of soil respiration in cropland. • Litter was the most important source to soil respiration in the vegetation land. [ABSTRACT FROM AUTHOR]