The implementation of the Grain for Green Program is a great breakthrough in the history of China's ecological environment construction,which can control soil erosion effectively,increase land productivity and improv...The implementation of the Grain for Green Program is a great breakthrough in the history of China's ecological environment construction,which can control soil erosion effectively,increase land productivity and improve the ecological environment.To investigate the eco-environmental benefits brought by the Grain for Green Program,the spatiotemporal variations of vegetation cover in the growing season from 2000 to 2010 across the Hekou-Longmen (He-Long) region were analyzed by using remote sensing information,meteorological data and land use data.Moreover,the impacts of climate and human activities on vegetation change were evaluated objectively.Annual vegetation cover in the growing season increased very significantly.Increased vegetation cover occurred in 98.7% of the region,of which the area for vegetation cover improved slightly constituted 79.8% of the whole area.Vegetation moderately improved was mainly distributed in the south of the He-Long region,covering 9.6% of the area,and the area for vegetation basically unchanged concentrated in the middle and upper reaches of the Wuding River.Precipitation was found to be an important natural factor influencing vegetation cover change.The area of vegetation cover showing a significantly positive correlation with precipitation occupied 22.14% of the region.As driven by policies from the Grain for Green Program,forestland increased significantly and land use structure became more intensive.Human activities played a positive and effective role in the protection,restoration and improvement of vegetation in the places where vegetation cover was basically unchanged,even though precipitation declined greatly,and vegetation improved moderately with massive increases of forestland and grassland.展开更多
The Grain for Green Project(GGP) is an important measure for the prevention of sloping farmland and the restoration of natural vegetation.This project has been critical to the restoration of ecological environments in...The Grain for Green Project(GGP) is an important measure for the prevention of sloping farmland and the restoration of natural vegetation.This project has been critical to the restoration of ecological environments in western China. However,the effect of the GGP on freshwater ecosystem services under extreme climates remains unclear. Thus, taking the middle and upper reaches of the Wujiang River Basin in western China as an example, this study assessed the variation of three freshwater ecosystem services(e.g., water yield, soil retention and nutrient retention) impacted by the GGP under drought stress by employing the Integrated Valuation of Ecosystem Services and Tradeoffs(In VEST) model. In addition,the trade-off/synergistic relationship between three freshwater ecosystem services was analyzed based on the Pearson correlation coefficient. As revealed from the results, the effect of the GGP on the water yield and nutrient retention under drought stress was significantly higher than that on the soil retention.With the increase in the drought degree, the variation rate of the water yield and nutrient retention impacted by the GGP increased, whereas that of the soil retention decreased. The GGP in droughts of different seasons resulted in a significant heterogeneity in the changes of three freshwater ecosystem services. The correlation coefficients between the water yield and soil retention as well as that between the water yield and the nutrient retention increased, and the correlation coefficients declined between soil and nutrient retention under different drought degrees following the GGP. Unlike for the summer drought case, there were no significant changes in the correlation coefficients between three freshwater ecosystem services in spring, autumn and winter droughts. The results suggest that the amount of farmland converted to shrubland should be regulated to reduce the trade-off intensity between freshwater ecosystem services. In addition, food security and ecological environment protection should be balanced during the implementation of the GGP, and the most concentrated distribution region of farmland-to-forest conversion will be the key area of ecological management in the future.展开更多
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...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.展开更多
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 a...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.展开更多
Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and...Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and transfer rate of LULC in the Jinghe River Basin(JRB),China using LULC data from 2000 to 2020.Through trajectory analysis,knowledge maps,chord diagrams,and standard deviation ellipse method,we examined the spatiotemporal characteristics of LULC changes.We further established an index system encompassing natural factors(digital elevation model(DEM),slope,aspect,and curvature),socio-economic factors(gross domestic product(GDP)and population),and accessibility factors(distance from railways,distance from highways,distance from water,and distance from residents)to investigate the driving mechanisms of LULC changes using factor detector and interaction detector in the geographical detector(Geodetector).The key findings indicate that from 2000 to 2020,the JRB experienced significant LULC changes,particularly for farmland,forest,and grassland.During the study period,LULC change trajectories were categorized into stable,early-stage,late-stage,repeated,and continuous change types.Besides the stable change type,the late-stage change type predominated the LULC change trajectories,comprising 83.31% of the total change area.The period 2010-2020 witnessed more active LULC changes compared to the period 2000-2010.The LULC changes exhibited a discrete spatial expansion trend during 2000-2020,predominantly extending from southeast to northwest of the JRB.Influential driving factors on LULC changes included slope,GDP,and distance from highways.The interaction detection results imply either bilinear or nonlinear enhancement for any two driving factors impacting the LULC changes from 2000 to 2020.This comprehensive understanding of the spatiotemporal characteristics and driving mechanisms of LULC changes offers valuable insights for the planning and sustainable management of LULC in the JRB.展开更多
A 1-year baseline survey was conducted in north-western China to evaluate the ecological restoration quality of grain for green(GFG)using soil ciliate communities.The aims of this study were focused on analyzing the c...A 1-year baseline survey was conducted in north-western China to evaluate the ecological restoration quality of grain for green(GFG)using soil ciliate communities.The aims of this study were focused on analyzing the changes of soil ciliate communities in four plots(A,GFG for 15 years;B,GFG for 13 years;C,layland;D,cultivated land)for GFG environmental assessment.Simultaneously we studied the effects of vegetation communities and physical-chemical variables with GFG changes on soil ciliates.A total of 114 species of ciliates were identified among the four sample sites,representing 9 classes,14 orders,22 families and 37 genera.The community patterns of the soil ciliates were significantly correlated with the individual abundance of aboveground plants,soil water content,and soil porosity.The contents of total nitrogen were the main factor affecting the soil ciliate community composition.The species number,individual abundance,and diversity index of the ciliates were each in the order A>B>C>D;that is,the community composition of ciliates was complicated with the implementation of the GFG.It was shown that the succession of ciliate community shifts toward promoting the complexity with the progress of GFG.These findings demonstrate that soil ciliate communities may be used as a useful indicator to evaluate the effects of the ecological restoration quality of GFG.展开更多
A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges...A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges.Various climatic factors such as temperature,precipitation,and solar radiation,as well as anthropogenic factors such as ecological engineering and population migration,will affect the conditions for vegetation.However,the relationships among various factors remain unclear and the response of vegetation to climate change and anthropogenic activities in the Loess Plateau of China has not been well established.This study investigated the spatio-temporal characteristics and relationships between vegetation coverage and climatic factors in the Loess Plateau for the period of 1985–2015.Further analysis separated the anthropogenic and climatic factors on vegetation succession based on residual analysis.The results showed that the normalized difference vegetation index(NDVI)followed a significant upward trend with annual change rates of 0.15%during 1985–2015.The trend of human-induced NDVI increase was consistent with the spatial distribution of increasing forest areas in the eastern part of the Loess Plateau.Eco-restoration projects were the main driving factors that promoted vegetation coverage on the Loess Plateau.Furthermore,these results demonstrated that migrants to cities in the Loess Plateau could relieve ecological pressures and promote vegetation restoration.Therefore,the government should strive to increase population mobility and restore vegetation to sustain this particularly fragile ecological environment.展开更多
Social resources of indigenous people are valuable wealth, including the social norms, the relational network, belief, attitude as well as the social system which is accumulated from generation to generation. Those so...Social resources of indigenous people are valuable wealth, including the social norms, the relational network, belief, attitude as well as the social system which is accumulated from generation to generation. Those social resources are very important for local ecological resource management, which can help diffuseness and communion of skills and traditional conservation techniques for conserving and restoring the ecological sites. Social capital is one indicator of social resources, which is accepted widely. In order to investigate the role of social resources of indigenous people in local ecological resource management, the authors studied the relation between social capital of indigenous people and local ecological resource management, taking Zhangye City as an exam-ple. In this paper, social capital of indigenous people is quantified by constructing social capital index, composed of structural so-cial capital and cognitive social capital; local ecological resource management is quantified by constructing 'Grain for Green Pro-ject' performance index. Based on correlation analysis approach and logistic regression analysis approach, the authors analyzed the relation between social capital and 'Grain for Green Project' performance index, as well as the relations between 'Grain for Green Project' performance index and other factors such as per capita net income, medical treatment and so on. Results showed that the correlation between social capital and 'Grain for Green Project' performance index was positive, the coefficient was 0.761, with P<0.01. An increase of 1 unit in social capital is associated with an increase of 1.550 units in 'Grain for Green Project' per-formance. With factor, such as faction, per capita net income, medical treatment, increasing 1 unit, the 'Grain for Green Project' performance index will increase 3.912, 1.039 and 1.005 units, respectively.展开更多
The area of land that is affected by soil erosion in the Yangtze River has been reduced by 146,000 km~2(accounting for 27%of the entire Yangtze River)since 2000.However,the contributions of different tributaries to th...The area of land that is affected by soil erosion in the Yangtze River has been reduced by 146,000 km~2(accounting for 27%of the entire Yangtze River)since 2000.However,the contributions of different tributaries to this soil erosion decline and the underlying causes have not been determined.Here we quantify the soil erosion decline in the Yangtze River and the impacts of the Grain-for-Green Programme(GFGP)and climate change using the RUSLE model and statistical methods.The results were as follows:(1)After the implementation of the GFGP,soil erosion decreased in ten sub-basins excluding the Dongting Lake catchment;(2)Soil erosion was mainly affected by the GFGP and the rainfall erosivity.Specifically,the contributions of the GFGP and rainfall erosivity to soil erosion decline are estimated to be 70.12%and 29.88%,respectively.(3)“Scenario#9”means the combination of slope(15°-25°)of retired farmland converted to shrub land and slope(>25°)of retired farmland converted to grassland.Considering scenario feasibility and management targets,Scenario#9 was the most appropriate land use scenario for the Yangtze River.This study offers insights into managing and reducing soil erosion in the future.展开更多
During the past decade, great efforts have been made to boost the land use trans- formation in the Loess Plateau, especially for reducing soil erosion by vegetation restoration measures. The Grain-for-Green project (...During the past decade, great efforts have been made to boost the land use trans- formation in the Loess Plateau, especially for reducing soil erosion by vegetation restoration measures. The Grain-for-Green project (GFG) is the largest ecological rehabilitation program in China, which has a positive impact on the vegetation restoration and sustainable devel- opment for the ecologically fragile region of west China. Based on the Landsat TM/ETM im- ages for three time periods (2000, 2005 and 2010), this study applied the GIS technology and a hill-slope analytical model to reveal the spatio-temporal evolutional patterns of returning slope farmland to grassland or woodland in Baota District, Yan'an city of Shaanxi province. Results showed that: (1) from 2000 to 2010, the area of farmland decreased by approximately 35,030 ha, which is the greatest decrease among all the land-use types, whereas grassland, woodland and construction land increased, of which grassland expanded rapidly by 26,380 ha (2) The annual variation rate of land-use dynamics was 1.98% during the period 2000-2010, of which the rate was 1.05% for the 2000-2005 period and 2.92% for the 2005-2010 period, respectively. Over the past decade, returning farmland to woodland or pastures was the main source of increased grassland and woodland, and the reduction of farmland contributed to the increase in grassland and woodland by 97.39% and 85.28%, respectively. (3) As the terrain slope increases, farmland decreased and woodland and grassland increased significantly. Areas with a slope ranging from 15° to 25° and less than 15° were the focus of the GFG project, accounting for 85% of the total area of farmland reduction. Meanwhile, the reduction in farmland was significant and spatially correlated with the increase in woodland and grass- land. (4) Between 2000 and 2010, the area of destruction of grass and trees in grasslands and woodlands for the reclamation of farmland was approximately 4596 ha. The area subject to the GFG policy was 4456 ha with a slope greater than 25° over the decade, but the area of farmland was still 10,357 ha in 2010. Our results indicate that there has still a great potential for returning the steep-slope farmlands to woodlands or grasslands in the Loess Plateau.展开更多
The "Grain for Green Project" initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human a...The "Grain for Green Project" initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human activities are responsible for the improvement and degradation to a certain degree. In order to monitor the vegetation variations and clarify the causes of rehabilitation in the Shaanxi-Gansu-Ningxia Region, this paper, based on the MODIS-NDVI and climate data during the period of 2000-2009, analyzes the main charac- teristics, spatial-temporal distribution and reasons of vegetation restoration, using methods of linear regression, the Hurst Exponent, standard deviation and other methods. Results are shown as follows. (1) From 2000 to 2009, the NDVI of the study area was improved progres- sively, with a linear tendency being 0.032/10a, faster than the growth of the Three-North Shelter Forest Program (0.007/10a) from 1982 to 2006. (2) The vegetation restoration is characterized by two fast-growing periods, with an "S-shaped" increasing curve. (3) The largest proportion of the contribution to vegetation restoration was observed in the slightly improved area, followed by the moderate and the significantly improved area; the degraded area is distributed sporadically over southern part of Ningxia Hui Autonomous Region as well as eastern Dingbian of Shaanxi province, Huanxian and Zhengyuan of Gansu province. (4) Climate change and human activities are two driving forces in vegetation restoration; more- over anthropogenic factors such as "Grain for Green Project" were the main causes leading to an increasing trend of NDVI on local scale. However, its influencing mechanism remains to be further investigated. (5) The Hurst Exponent of NDVI time series shows that the vegetation restoration was sustainable. It is expected that improvement in vegetation cover will expand to the most parts of the region.展开更多
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 (ER...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 satel- lite-based net primary productivity models, we identified the impacts on agricultural produc- tivity 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 132.67×104 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 de- creased to 77.18×104 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. Al- though 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.展开更多
Evaluating the effects of revegetation on runoff and erosion reduction is essential for studying soil and water conservation on the Loess Plateau after implementation of China's Grain for Green Project.However,qua...Evaluating the effects of revegetation on runoff and erosion reduction is essential for studying soil and water conservation on the Loess Plateau after implementation of China's Grain for Green Project.However,quantifying the influence of revegetation on the erosion caused by concentrated runoff in extreme rainstorms is still challenging.To evaluate this influence,scouring-erosion experiments were implemented in situ on the vegetated hillslope plots(GR)and bare hillslope plots(CK).The runoffreducing effects of grass(GRR)averaged 31%,20%and 8%,and the erosion-reducing effects of grass(GER)averaged 93%,95%and 93%on the 5-plots,10-plots and 18-plots,respectively.The ratios of GRR to GER were 0.09e0.33,implying that the ability of vegetation to reduce erosion was greater than its ability to reduce runoff.The GRR and GER obviously decreased as the inflow rate increased,and the GRR decreased as the hillslope gradient increased,but there were no obvious differences in the GER between hillslope gradients.Vegetation could decrease the ability of the concentrated flow to carry and transport sediment and increase the energy consumption of the concentrated flow in response to hydraulic resistance.Vegetation also significantly reduced the degree of rill development.The degree of rill dissection on the GR(0.054e0.087 m^(2)m^(2))was lower than that on the CK(0.061e0.184 m^(2)m^(2)).Our findings provide an essential reference for ecological environment and vegetation restoration on loess hillslopes.展开更多
基金funded by the funding from the Chinese Academy of Sciences(KZCX2-XB3-13,KZZD-EW-04-03)the National Science Foundation of China(41230852,41101265)and China Census for Water
文摘The implementation of the Grain for Green Program is a great breakthrough in the history of China's ecological environment construction,which can control soil erosion effectively,increase land productivity and improve the ecological environment.To investigate the eco-environmental benefits brought by the Grain for Green Program,the spatiotemporal variations of vegetation cover in the growing season from 2000 to 2010 across the Hekou-Longmen (He-Long) region were analyzed by using remote sensing information,meteorological data and land use data.Moreover,the impacts of climate and human activities on vegetation change were evaluated objectively.Annual vegetation cover in the growing season increased very significantly.Increased vegetation cover occurred in 98.7% of the region,of which the area for vegetation cover improved slightly constituted 79.8% of the whole area.Vegetation moderately improved was mainly distributed in the south of the He-Long region,covering 9.6% of the area,and the area for vegetation basically unchanged concentrated in the middle and upper reaches of the Wuding River.Precipitation was found to be an important natural factor influencing vegetation cover change.The area of vegetation cover showing a significantly positive correlation with precipitation occupied 22.14% of the region.As driven by policies from the Grain for Green Program,forestland increased significantly and land use structure became more intensive.Human activities played a positive and effective role in the protection,restoration and improvement of vegetation in the places where vegetation cover was basically unchanged,even though precipitation declined greatly,and vegetation improved moderately with massive increases of forestland and grassland.
基金supported by the Science and Technology Foundation of Guizhou Province (No. [2020]1Y152)the Guizhou Education Department Project (No. KY[2021]075)。
文摘The Grain for Green Project(GGP) is an important measure for the prevention of sloping farmland and the restoration of natural vegetation.This project has been critical to the restoration of ecological environments in western China. However,the effect of the GGP on freshwater ecosystem services under extreme climates remains unclear. Thus, taking the middle and upper reaches of the Wujiang River Basin in western China as an example, this study assessed the variation of three freshwater ecosystem services(e.g., water yield, soil retention and nutrient retention) impacted by the GGP under drought stress by employing the Integrated Valuation of Ecosystem Services and Tradeoffs(In VEST) model. In addition,the trade-off/synergistic relationship between three freshwater ecosystem services was analyzed based on the Pearson correlation coefficient. As revealed from the results, the effect of the GGP on the water yield and nutrient retention under drought stress was significantly higher than that on the soil retention.With the increase in the drought degree, the variation rate of the water yield and nutrient retention impacted by the GGP increased, whereas that of the soil retention decreased. The GGP in droughts of different seasons resulted in a significant heterogeneity in the changes of three freshwater ecosystem services. The correlation coefficients between the water yield and soil retention as well as that between the water yield and the nutrient retention increased, and the correlation coefficients declined between soil and nutrient retention under different drought degrees following the GGP. Unlike for the summer drought case, there were no significant changes in the correlation coefficients between three freshwater ecosystem services in spring, autumn and winter droughts. The results suggest that the amount of farmland converted to shrubland should be regulated to reduce the trade-off intensity between freshwater ecosystem services. In addition, food security and ecological environment protection should be balanced during the implementation of the GGP, and the most concentrated distribution region of farmland-to-forest conversion will be the key area of ecological management in the future.
基金This work was supported by the National Natural Science Foundation of China(Grant number:U2002209,41867029)Distinguished Young Found Project of Yunnan Province(Grant number:202201AV070001)Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant number:2019QZKK0307).
文摘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.
基金This work was supported by the National Key Research and Development Program of China[2017YFC0504704]National Natural Science Foundation of China[41601092,41731289]+2 种基金National Geological Prospecting special[DD20190504]Shaanxi Province Innovation Talent Promotion Project Technology Innovation Team[Grant 2018TD-037]Shaanxi Provincial Technology Innovation Guidance Project[Grant 2017CGZH-HJ-06].
文摘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.
基金partly funded by the National Key Research and Development Program of China(NK2023190801)the National Foreign Experts Program of China(G2023041024L)the Key Scientific Research Program of Shaanxi Provincial Education Department,China(21JT028)。
文摘Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and transfer rate of LULC in the Jinghe River Basin(JRB),China using LULC data from 2000 to 2020.Through trajectory analysis,knowledge maps,chord diagrams,and standard deviation ellipse method,we examined the spatiotemporal characteristics of LULC changes.We further established an index system encompassing natural factors(digital elevation model(DEM),slope,aspect,and curvature),socio-economic factors(gross domestic product(GDP)and population),and accessibility factors(distance from railways,distance from highways,distance from water,and distance from residents)to investigate the driving mechanisms of LULC changes using factor detector and interaction detector in the geographical detector(Geodetector).The key findings indicate that from 2000 to 2020,the JRB experienced significant LULC changes,particularly for farmland,forest,and grassland.During the study period,LULC change trajectories were categorized into stable,early-stage,late-stage,repeated,and continuous change types.Besides the stable change type,the late-stage change type predominated the LULC change trajectories,comprising 83.31% of the total change area.The period 2010-2020 witnessed more active LULC changes compared to the period 2000-2010.The LULC changes exhibited a discrete spatial expansion trend during 2000-2020,predominantly extending from southeast to northwest of the JRB.Influential driving factors on LULC changes included slope,GDP,and distance from highways.The interaction detection results imply either bilinear or nonlinear enhancement for any two driving factors impacting the LULC changes from 2000 to 2020.This comprehensive understanding of the spatiotemporal characteristics and driving mechanisms of LULC changes offers valuable insights for the planning and sustainable management of LULC in the JRB.
基金the National Natural Science Foundation of China(Project number:41761056,41361055,42067012).
文摘A 1-year baseline survey was conducted in north-western China to evaluate the ecological restoration quality of grain for green(GFG)using soil ciliate communities.The aims of this study were focused on analyzing the changes of soil ciliate communities in four plots(A,GFG for 15 years;B,GFG for 13 years;C,layland;D,cultivated land)for GFG environmental assessment.Simultaneously we studied the effects of vegetation communities and physical-chemical variables with GFG changes on soil ciliates.A total of 114 species of ciliates were identified among the four sample sites,representing 9 classes,14 orders,22 families and 37 genera.The community patterns of the soil ciliates were significantly correlated with the individual abundance of aboveground plants,soil water content,and soil porosity.The contents of total nitrogen were the main factor affecting the soil ciliate community composition.The species number,individual abundance,and diversity index of the ciliates were each in the order A>B>C>D;that is,the community composition of ciliates was complicated with the implementation of the GFG.It was shown that the succession of ciliate community shifts toward promoting the complexity with the progress of GFG.These findings demonstrate that soil ciliate communities may be used as a useful indicator to evaluate the effects of the ecological restoration quality of GFG.
基金Under the auspices of the National Key Research and Development Program of China(No.2017YFC0504701)National Natural Science Foundation of China(No.41971220,41701119,41471143)National Social Science Foundation of China(No.15ZDA021)
文摘A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges.Various climatic factors such as temperature,precipitation,and solar radiation,as well as anthropogenic factors such as ecological engineering and population migration,will affect the conditions for vegetation.However,the relationships among various factors remain unclear and the response of vegetation to climate change and anthropogenic activities in the Loess Plateau of China has not been well established.This study investigated the spatio-temporal characteristics and relationships between vegetation coverage and climatic factors in the Loess Plateau for the period of 1985–2015.Further analysis separated the anthropogenic and climatic factors on vegetation succession based on residual analysis.The results showed that the normalized difference vegetation index(NDVI)followed a significant upward trend with annual change rates of 0.15%during 1985–2015.The trend of human-induced NDVI increase was consistent with the spatial distribution of increasing forest areas in the eastern part of the Loess Plateau.Eco-restoration projects were the main driving factors that promoted vegetation coverage on the Loess Plateau.Furthermore,these results demonstrated that migrants to cities in the Loess Plateau could relieve ecological pressures and promote vegetation restoration.Therefore,the government should strive to increase population mobility and restore vegetation to sustain this particularly fragile ecological environment.
基金funded by the items of the West Action Plan of Chinese Academy of Science (No. KZCX2-XB2-04-04)Key Project of National Natural Science Foundation of China (No. 40671076)
文摘Social resources of indigenous people are valuable wealth, including the social norms, the relational network, belief, attitude as well as the social system which is accumulated from generation to generation. Those social resources are very important for local ecological resource management, which can help diffuseness and communion of skills and traditional conservation techniques for conserving and restoring the ecological sites. Social capital is one indicator of social resources, which is accepted widely. In order to investigate the role of social resources of indigenous people in local ecological resource management, the authors studied the relation between social capital of indigenous people and local ecological resource management, taking Zhangye City as an exam-ple. In this paper, social capital of indigenous people is quantified by constructing social capital index, composed of structural so-cial capital and cognitive social capital; local ecological resource management is quantified by constructing 'Grain for Green Pro-ject' performance index. Based on correlation analysis approach and logistic regression analysis approach, the authors analyzed the relation between social capital and 'Grain for Green Project' performance index, as well as the relations between 'Grain for Green Project' performance index and other factors such as per capita net income, medical treatment and so on. Results showed that the correlation between social capital and 'Grain for Green Project' performance index was positive, the coefficient was 0.761, with P<0.01. An increase of 1 unit in social capital is associated with an increase of 1.550 units in 'Grain for Green Project' per-formance. With factor, such as faction, per capita net income, medical treatment, increasing 1 unit, the 'Grain for Green Project' performance index will increase 3.912, 1.039 and 1.005 units, respectively.
基金National Natural Science Foundation of China,No.42101259,No.42371101,No.42301455Qin Chuangyuan Cites High-level Innovation or Entrepreneurship Talent Project,No.QCYRCXM-2023-066+2 种基金Fifth Batch Special Funding(Pre-Station)from China Postdoctoral Science Foundation,No.2023TQ0207Fundamental Research Funds for the Central Universities,No.GK202304024,No.1110011297,No.1112010355Teaching Reform Project of Shaanxi University,No.23GGYS-JG06。
文摘The area of land that is affected by soil erosion in the Yangtze River has been reduced by 146,000 km~2(accounting for 27%of the entire Yangtze River)since 2000.However,the contributions of different tributaries to this soil erosion decline and the underlying causes have not been determined.Here we quantify the soil erosion decline in the Yangtze River and the impacts of the Grain-for-Green Programme(GFGP)and climate change using the RUSLE model and statistical methods.The results were as follows:(1)After the implementation of the GFGP,soil erosion decreased in ten sub-basins excluding the Dongting Lake catchment;(2)Soil erosion was mainly affected by the GFGP and the rainfall erosivity.Specifically,the contributions of the GFGP and rainfall erosivity to soil erosion decline are estimated to be 70.12%and 29.88%,respectively.(3)“Scenario#9”means the combination of slope(15°-25°)of retired farmland converted to shrub land and slope(>25°)of retired farmland converted to grassland.Considering scenario feasibility and management targets,Scenario#9 was the most appropriate land use scenario for the Yangtze River.This study offers insights into managing and reducing soil erosion in the future.
基金Foundation: National Natural Science Foundation of China, No.41130748
文摘During the past decade, great efforts have been made to boost the land use trans- formation in the Loess Plateau, especially for reducing soil erosion by vegetation restoration measures. The Grain-for-Green project (GFG) is the largest ecological rehabilitation program in China, which has a positive impact on the vegetation restoration and sustainable devel- opment for the ecologically fragile region of west China. Based on the Landsat TM/ETM im- ages for three time periods (2000, 2005 and 2010), this study applied the GIS technology and a hill-slope analytical model to reveal the spatio-temporal evolutional patterns of returning slope farmland to grassland or woodland in Baota District, Yan'an city of Shaanxi province. Results showed that: (1) from 2000 to 2010, the area of farmland decreased by approximately 35,030 ha, which is the greatest decrease among all the land-use types, whereas grassland, woodland and construction land increased, of which grassland expanded rapidly by 26,380 ha (2) The annual variation rate of land-use dynamics was 1.98% during the period 2000-2010, of which the rate was 1.05% for the 2000-2005 period and 2.92% for the 2005-2010 period, respectively. Over the past decade, returning farmland to woodland or pastures was the main source of increased grassland and woodland, and the reduction of farmland contributed to the increase in grassland and woodland by 97.39% and 85.28%, respectively. (3) As the terrain slope increases, farmland decreased and woodland and grassland increased significantly. Areas with a slope ranging from 15° to 25° and less than 15° were the focus of the GFG project, accounting for 85% of the total area of farmland reduction. Meanwhile, the reduction in farmland was significant and spatially correlated with the increase in woodland and grass- land. (4) Between 2000 and 2010, the area of destruction of grass and trees in grasslands and woodlands for the reclamation of farmland was approximately 4596 ha. The area subject to the GFG policy was 4456 ha with a slope greater than 25° over the decade, but the area of farmland was still 10,357 ha in 2010. Our results indicate that there has still a great potential for returning the steep-slope farmlands to woodlands or grasslands in the Loess Plateau.
基金National Natural Science Foundation of China, No.41171090 No.40871052
文摘The "Grain for Green Project" initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human activities are responsible for the improvement and degradation to a certain degree. In order to monitor the vegetation variations and clarify the causes of rehabilitation in the Shaanxi-Gansu-Ningxia Region, this paper, based on the MODIS-NDVI and climate data during the period of 2000-2009, analyzes the main charac- teristics, spatial-temporal distribution and reasons of vegetation restoration, using methods of linear regression, the Hurst Exponent, standard deviation and other methods. Results are shown as follows. (1) From 2000 to 2009, the NDVI of the study area was improved progres- sively, with a linear tendency being 0.032/10a, faster than the growth of the Three-North Shelter Forest Program (0.007/10a) from 1982 to 2006. (2) The vegetation restoration is characterized by two fast-growing periods, with an "S-shaped" increasing curve. (3) The largest proportion of the contribution to vegetation restoration was observed in the slightly improved area, followed by the moderate and the significantly improved area; the degraded area is distributed sporadically over southern part of Ningxia Hui Autonomous Region as well as eastern Dingbian of Shaanxi province, Huanxian and Zhengyuan of Gansu province. (4) Climate change and human activities are two driving forces in vegetation restoration; more- over anthropogenic factors such as "Grain for Green Project" were the main causes leading to an increasing trend of NDVI on local scale. However, its influencing mechanism remains to be further investigated. (5) The Hurst Exponent of NDVI time series shows that the vegetation restoration was sustainable. It is expected that improvement in vegetation cover will expand to the most parts of the region.
基金National Key Program for Developing Basic Science, No.2010CB950904National Natural Science Foundation of China, No.41071344+1 种基金Knowledge Innovation Program of CAS, No.KZCX2-EW-306Strategic Priority Research Program of CAS, No.XDA05050602
文摘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 satel- lite-based net primary productivity models, we identified the impacts on agricultural produc- tivity 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 132.67×104 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 de- creased to 77.18×104 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. Al- though 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.
基金The work was funded by the Natural Science Basic Research Program of Shaanxi Province(2021JQ-165)China Postdoctoral Science Foundation(2020M683591)Key National Research and Development Program of China(2016YFC0501604).
文摘Evaluating the effects of revegetation on runoff and erosion reduction is essential for studying soil and water conservation on the Loess Plateau after implementation of China's Grain for Green Project.However,quantifying the influence of revegetation on the erosion caused by concentrated runoff in extreme rainstorms is still challenging.To evaluate this influence,scouring-erosion experiments were implemented in situ on the vegetated hillslope plots(GR)and bare hillslope plots(CK).The runoffreducing effects of grass(GRR)averaged 31%,20%and 8%,and the erosion-reducing effects of grass(GER)averaged 93%,95%and 93%on the 5-plots,10-plots and 18-plots,respectively.The ratios of GRR to GER were 0.09e0.33,implying that the ability of vegetation to reduce erosion was greater than its ability to reduce runoff.The GRR and GER obviously decreased as the inflow rate increased,and the GRR decreased as the hillslope gradient increased,but there were no obvious differences in the GER between hillslope gradients.Vegetation could decrease the ability of the concentrated flow to carry and transport sediment and increase the energy consumption of the concentrated flow in response to hydraulic resistance.Vegetation also significantly reduced the degree of rill development.The degree of rill dissection on the GR(0.054e0.087 m^(2)m^(2))was lower than that on the CK(0.061e0.184 m^(2)m^(2)).Our findings provide an essential reference for ecological environment and vegetation restoration on loess hillslopes.