The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature, precipitation, and the East Asian Monsoon across China were reviewed. Findings show tha...The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature, precipitation, and the East Asian Monsoon across China were reviewed. Findings show that the land cover in China has been significantly modified by human activities over the last several thousands years, mainly through cropland expansion and forest clearance. The cropland over traditional Chinese agricultural areas increased from 5.32×10^5 km^2 in the mid-17th century to 8.27×10^5 km^2 in the mid-20th century, while the forest area over the Chinese mainland had been reduced by 1.66×10^6 km^2 during the last 300 years. These changes of land cover have been detected as an important driving force of climate change by simulations of climatic effects based on various climate models （including RegCM3, RegCM2-NCC, RIEMS version1, MM5 version 2, and AGCM＋SSiB） with reconstructed historical land cover data or by contrasting current land cover to potential natural vegetation. The human-induced land cover changes over China have led to the enhancement of the East Asian winter monsoon, as well as cooling in winter and warming in summer approximately since 1700. However, the simulation results on annual mean temperature, precipitation, and the East Asian summer monsoon varied from model to model, which cannot be simply attributed to certain forcing so far, but undoubtedly, using different land cover datasets in various simulations played a key role. Thus, developing different regional scales with high time resolution more accurate gridded historical land cover datasets on is needed in the future.展开更多
Recent studies have demonstrated the importance of LUCC change with climate and ecosystem simulation, but the result could only be determined precisely if a high-resolution underlying land cover map is used. While the...Recent studies have demonstrated the importance of LUCC change with climate and ecosystem simulation, but the result could only be determined precisely if a high-resolution underlying land cover map is used. While the efforts based satellites have provided a good baseline for present land cover, what the next advancement in the research about LUCC change required is the development of reconstruction of historical LUCC change especially spatially-explicit historical dataset. Being different from other similar studies, this study is based on the analysis of historical land use patterns in the traditional cultivated region of China. Taking no account of the less important factors, altitude, slope and population patterns are selected as the major drivers of reclamation in ancient China, and used to design the HCGM （Historical Cropland Gridding Model, at a 60 km×60 km resolution）, which is an empirical model for allocating the historical cropland inventory data spatially to grid cells in each political unit. Then we use this model to reconstruct cropland distribution of the study area in 1820, and verify the result by prefectural cropland data of 1820, which is from the historical documents. The statistical analyzing result shows that the model can simulate the patterns of the cropland distribution in the historical period in the traditional cultivated region efficiently.展开更多
Landscape in the middle and lower reaches of the Yellow River in China has un-dergone significant changes for thousands of years due to agricultural expansion.Lack of reliable long-term and high-resolution historical ...Landscape in the middle and lower reaches of the Yellow River in China has un-dergone significant changes for thousands of years due to agricultural expansion.Lack of reliable long-term and high-resolution historical cropland data has limited our ability in un-derstanding and quantifying human impacts on regional climate change,carbon and water cycles.In this study,we used a data-driven modeling framework that combined multiple sources of data(historical provincial cropland area,historical coastlines,and satellite da-ta-based maximum cropland extent)with a new gridding allocation model for croplands dis-tribution to reconstruct a historical cropland dataset for the middle and lower reaches of the Yellow River at a 10-km resolution for 58 time points ranging from the period 1000 to 1999.The cropland area in the study area increased by 2.3 times from 21.87 million ha in 1000 to 50.64 million ha in 1999.Before 1393,the area of cropland increased slowly and was pri-marily concentrated in the Weihe and Fenhe plains.From 1393-1820,the area of cropland increased rapidly,particularly on the North China Plain.Since 1820,cropland cover has tended to become saturated.Our newly reconstructed results agreed well with remotely sensed data as well as historical document-based facts regarding cropland distribution.展开更多
基金supported by the National Natural Science Foundation of China(GrantsNos40771017,40625002)the Chinese Academy of Sciences(Grant NoKZCX2–YW–315)
文摘The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature, precipitation, and the East Asian Monsoon across China were reviewed. Findings show that the land cover in China has been significantly modified by human activities over the last several thousands years, mainly through cropland expansion and forest clearance. The cropland over traditional Chinese agricultural areas increased from 5.32×10^5 km^2 in the mid-17th century to 8.27×10^5 km^2 in the mid-20th century, while the forest area over the Chinese mainland had been reduced by 1.66×10^6 km^2 during the last 300 years. These changes of land cover have been detected as an important driving force of climate change by simulations of climatic effects based on various climate models （including RegCM3, RegCM2-NCC, RIEMS version1, MM5 version 2, and AGCM＋SSiB） with reconstructed historical land cover data or by contrasting current land cover to potential natural vegetation. The human-induced land cover changes over China have led to the enhancement of the East Asian winter monsoon, as well as cooling in winter and warming in summer approximately since 1700. However, the simulation results on annual mean temperature, precipitation, and the East Asian summer monsoon varied from model to model, which cannot be simply attributed to certain forcing so far, but undoubtedly, using different land cover datasets in various simulations played a key role. Thus, developing different regional scales with high time resolution more accurate gridded historical land cover datasets on is needed in the future.
基金Natiional Natural Science Foundation of China,No.40471007Innovation Knowledge Project of CAS,No.KZCX2-YW-315
文摘Recent studies have demonstrated the importance of LUCC change with climate and ecosystem simulation, but the result could only be determined precisely if a high-resolution underlying land cover map is used. While the efforts based satellites have provided a good baseline for present land cover, what the next advancement in the research about LUCC change required is the development of reconstruction of historical LUCC change especially spatially-explicit historical dataset. Being different from other similar studies, this study is based on the analysis of historical land use patterns in the traditional cultivated region of China. Taking no account of the less important factors, altitude, slope and population patterns are selected as the major drivers of reclamation in ancient China, and used to design the HCGM （Historical Cropland Gridding Model, at a 60 km×60 km resolution）, which is an empirical model for allocating the historical cropland inventory data spatially to grid cells in each political unit. Then we use this model to reconstruct cropland distribution of the study area in 1820, and verify the result by prefectural cropland data of 1820, which is from the historical documents. The statistical analyzing result shows that the model can simulate the patterns of the cropland distribution in the historical period in the traditional cultivated region efficiently.
基金National Natural Science Foundation of China,No.42201263National Key Research and Development Program of China on Global Change,No.2017YFA0603304。
文摘Landscape in the middle and lower reaches of the Yellow River in China has un-dergone significant changes for thousands of years due to agricultural expansion.Lack of reliable long-term and high-resolution historical cropland data has limited our ability in un-derstanding and quantifying human impacts on regional climate change,carbon and water cycles.In this study,we used a data-driven modeling framework that combined multiple sources of data(historical provincial cropland area,historical coastlines,and satellite da-ta-based maximum cropland extent)with a new gridding allocation model for croplands dis-tribution to reconstruct a historical cropland dataset for the middle and lower reaches of the Yellow River at a 10-km resolution for 58 time points ranging from the period 1000 to 1999.The cropland area in the study area increased by 2.3 times from 21.87 million ha in 1000 to 50.64 million ha in 1999.Before 1393,the area of cropland increased slowly and was pri-marily concentrated in the Weihe and Fenhe plains.From 1393-1820,the area of cropland increased rapidly,particularly on the North China Plain.Since 1820,cropland cover has tended to become saturated.Our newly reconstructed results agreed well with remotely sensed data as well as historical document-based facts regarding cropland distribution.
