Multi-temporal series of satellite SPOT-VEGETATION normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) data from 1998 to 2007 were used for analyzing vegetation change of the eco...Multi-temporal series of satellite SPOT-VEGETATION normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) data from 1998 to 2007 were used for analyzing vegetation change of the ecotone in the west of the Northeast China Plain. The yearly and monthly maximal values,anomalies and change rates of NDVI and NDWI were calculated to reveal the interannual and seasonal changes in vegetation cover and vegetation water content. Linear regression method was adopted to characterize the trends in vegetation change. The yearly maximal NDVI decreased from 0.41 in 1998 to 0.37 in 2007,implying the decreasing trend of vegetation activity. There was a significant decrease of maximal NDVI in spring and summer over the study period,while an increase trend was observed in autumn. The vegetation-improved regions and vegetation-degraded regions occupied 17.03% and 20.30% of the study area,respectively. The maximal NDWI over growing season dropped by 0.027 in 1998–2007,and about 15.15% of the study area showed a decreasing trend of water content. Vegetation water stress in autumn was better than that in spring. Vegetation cover and water content variations were sensitive to annual precipitation,autumn precipitation and summer temperature. The vegetation degradation trend in this ecotone might be induced by the warm-drying climate especially continuous spring and summer drought in the recent ten years.展开更多
During the 21st century,policies toward agriculture,forestry,and urbanization have emerged to ensure food security,ecological restoration,and human well-being by managing land in Northeast China.However,the integrated...During the 21st century,policies toward agriculture,forestry,and urbanization have emerged to ensure food security,ecological restoration,and human well-being by managing land in Northeast China.However,the integrated effects and relationships of various policies are still not well understood.This study observed the land use land cover changes in Central Jilin from 2000 to 2019 and,by considering policy involvement,aimed to understand the effects and trade-offs of policies.Results showed that the cropland,including dryland and rice paddy,and the forest,including coniferous forest and deciduous forest,are dominant land types in Central Jilin.During 2000–2019,the land changed diversely,of which the main changes were the expanded dryland(+0.43 million ha),the increased deciduous forest(+22 million ha),the decreased coniferous forest(–0.08 million ha),and the expanded urban settlement(+0.04 million ha).With these changes,despite the unit grain yield showing a rising trend,the yield contribution of Central Jilin to the national total decreased.The poor cultivating structure made for the cropland expansion and reduced the implementation space of environmental restoration projects such as the Grain to Green.Thus,in Central Jilin that transits from the agri-food production zone to the eco-regulation zone,environmental projects coexisted in a trade-off manner with agricultural policies that aim to liberate agricultural productivity.In the key urban agglomerations of Central Jilin,the increase in the proportion of green space improved the thermal environment and carbon balance.The gross domestic product of the large city and its local proportion also rose.These improvements benefited from the promotion of development policies and urbanization policies at key time points.In the future,it is necessary to coordinate agricultural policies and environmental projects and promote the progress of small-and medium-sized cities to ensure the equality of regional development.This study has implications for making decisions to revitalize Northeast China and researchers who inform decisions.展开更多
Plant life form diversity and its direct gradient analysis on a larger scale climate change gradient were tested, based on the data from Northeast China Transect platform. The results showed that the species numbers, ...Plant life form diversity and its direct gradient analysis on a larger scale climate change gradient were tested, based on the data from Northeast China Transect platform. The results showed that the species numbers, life form richness and life form diversity were relative higher at the eastern forests and the ecotone between typical vegetation, while those on the meadow grasslands and typical steppes were lower. Although plant life forms can reflect the climate variations, life form diversity is not consistent with the major global gradient along the NECT.展开更多
基金Under the auspices of Major State Basic Research Development Program of China (973 Program) (No. 2009CB426305)National Natural Science Foundation of China (No. 30370267) "Eleventh Five-year" Science and Technology In-novation Platform Foster Program of Northeast Normal University (No. 106111065202)
文摘Multi-temporal series of satellite SPOT-VEGETATION normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) data from 1998 to 2007 were used for analyzing vegetation change of the ecotone in the west of the Northeast China Plain. The yearly and monthly maximal values,anomalies and change rates of NDVI and NDWI were calculated to reveal the interannual and seasonal changes in vegetation cover and vegetation water content. Linear regression method was adopted to characterize the trends in vegetation change. The yearly maximal NDVI decreased from 0.41 in 1998 to 0.37 in 2007,implying the decreasing trend of vegetation activity. There was a significant decrease of maximal NDVI in spring and summer over the study period,while an increase trend was observed in autumn. The vegetation-improved regions and vegetation-degraded regions occupied 17.03% and 20.30% of the study area,respectively. The maximal NDWI over growing season dropped by 0.027 in 1998–2007,and about 15.15% of the study area showed a decreasing trend of water content. Vegetation water stress in autumn was better than that in spring. Vegetation cover and water content variations were sensitive to annual precipitation,autumn precipitation and summer temperature. The vegetation degradation trend in this ecotone might be induced by the warm-drying climate especially continuous spring and summer drought in the recent ten years.
基金Under the auspices of Science and Technology Major Project of Jilin Province(No.20200503001SF)Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020237)+1 种基金Cooperative Project of Jilin Province and Chinese Academy of Sciences for Industrializing Advanced Technology(No.2020SYHZ0004)National Natural Science Foundation of China(No.41701210)。
文摘During the 21st century,policies toward agriculture,forestry,and urbanization have emerged to ensure food security,ecological restoration,and human well-being by managing land in Northeast China.However,the integrated effects and relationships of various policies are still not well understood.This study observed the land use land cover changes in Central Jilin from 2000 to 2019 and,by considering policy involvement,aimed to understand the effects and trade-offs of policies.Results showed that the cropland,including dryland and rice paddy,and the forest,including coniferous forest and deciduous forest,are dominant land types in Central Jilin.During 2000–2019,the land changed diversely,of which the main changes were the expanded dryland(+0.43 million ha),the increased deciduous forest(+22 million ha),the decreased coniferous forest(–0.08 million ha),and the expanded urban settlement(+0.04 million ha).With these changes,despite the unit grain yield showing a rising trend,the yield contribution of Central Jilin to the national total decreased.The poor cultivating structure made for the cropland expansion and reduced the implementation space of environmental restoration projects such as the Grain to Green.Thus,in Central Jilin that transits from the agri-food production zone to the eco-regulation zone,environmental projects coexisted in a trade-off manner with agricultural policies that aim to liberate agricultural productivity.In the key urban agglomerations of Central Jilin,the increase in the proportion of green space improved the thermal environment and carbon balance.The gross domestic product of the large city and its local proportion also rose.These improvements benefited from the promotion of development policies and urbanization policies at key time points.In the future,it is necessary to coordinate agricultural policies and environmental projects and promote the progress of small-and medium-sized cities to ensure the equality of regional development.This study has implications for making decisions to revitalize Northeast China and researchers who inform decisions.
文摘Plant life form diversity and its direct gradient analysis on a larger scale climate change gradient were tested, based on the data from Northeast China Transect platform. The results showed that the species numbers, life form richness and life form diversity were relative higher at the eastern forests and the ecotone between typical vegetation, while those on the meadow grasslands and typical steppes were lower. Although plant life forms can reflect the climate variations, life form diversity is not consistent with the major global gradient along the NECT.
