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 polic展开更多
This paper reviewed existing literatures on land use change since the demonstration phase of the Three Gorges Project and found that reservoir inundation, migration resettlement, urban relocation, and post-supporting ...This paper reviewed existing literatures on land use change since the demonstration phase of the Three Gorges Project and found that reservoir inundation, migration resettlement, urban relocation, and post-supporting construction were first paid more attention to, when analyzing the driving forces of land use change in the migration area. However, at the post-migration period （the end of migration resettlement）, above-mentioned drivers had not obviously driven land use change, but the evolutions of ＂migration demands＂ replacing them increasingly became the major drivers of land use change in the migration area. Therefore, the future priority fields of land use explanations in the mi- gration area, Three Gorges Project were （1） identifying the corresponding relationships between the spatial distributions of land use change and migration resettlement and indigenous inhabitants; （2） un- derstanding the change of ＂migration demands＂ and their causing ＂indigenous inhabitants＇ demands＂ being how to drive land use transforms; （3） finding the driving processes of the conflict and exclusion between immigrants and indigenous inhabitants, and the transfer of immigrants and indigenous in- habitants on land use change; and （4） measuring the dynamic feedback of ＂migration demands＂ at dif- ferent stages on the processes, directions and their corresponding impacts of land use change in order to building the coupling framework among ＂migration demands＂, driver behaviors, and land use. This paper presents a new access for the explanation of land use change and also supplies scientific proofs to obtain adaptive decision-making to optimize land use patterns in the migration area, Three Gorges Project.展开更多
基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、...基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、恢复时间和气候等数据735条,旨在探究我国退耕还草工程对土壤有机碳含量的影响及其主导因素。结果表明:1)农田恢复为草地后,土壤有机碳含量呈先下降后上升趋势(时间拐点约为第6年),整体上退耕还草工程使土壤有机碳含量提高了19.8%。2)土壤有机碳的正响应随土壤深度增加而减弱,且深度超过1 m时其正响应不明显。3)土壤有效氮是影响土壤有机碳恢复的主要因素,而土壤有效磷和植物功能群对其影响不大。4)沿着增加的水分梯度,土壤有机碳的恢复效果由负变正,转变阈值为25.15 (干旱指数)。总体而言,我国退耕还草工程对土壤有机碳含量的影响为正效应,此效应受环境梯度和恢复时间的共同影响。本研究能够为我国土地利用变化背景下土壤碳库管理的相关决策提供科学依据。展开更多
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 polic
基金supported by the Key Project of Science and Technology of Ministry of Education,China(No.210181)the Foundation of Application Basic Research Project of Chongqing Municipal Commission of Education,China(No.KJ090805)
文摘This paper reviewed existing literatures on land use change since the demonstration phase of the Three Gorges Project and found that reservoir inundation, migration resettlement, urban relocation, and post-supporting construction were first paid more attention to, when analyzing the driving forces of land use change in the migration area. However, at the post-migration period （the end of migration resettlement）, above-mentioned drivers had not obviously driven land use change, but the evolutions of ＂migration demands＂ replacing them increasingly became the major drivers of land use change in the migration area. Therefore, the future priority fields of land use explanations in the mi- gration area, Three Gorges Project were （1） identifying the corresponding relationships between the spatial distributions of land use change and migration resettlement and indigenous inhabitants; （2） un- derstanding the change of ＂migration demands＂ and their causing ＂indigenous inhabitants＇ demands＂ being how to drive land use transforms; （3） finding the driving processes of the conflict and exclusion between immigrants and indigenous inhabitants, and the transfer of immigrants and indigenous in- habitants on land use change; and （4） measuring the dynamic feedback of ＂migration demands＂ at dif- ferent stages on the processes, directions and their corresponding impacts of land use change in order to building the coupling framework among ＂migration demands＂, driver behaviors, and land use. This paper presents a new access for the explanation of land use change and also supplies scientific proofs to obtain adaptive decision-making to optimize land use patterns in the migration area, Three Gorges Project.
