Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science （LCS） in the study of global environmental change. Based on remotely sensed data of...Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science （LCS） in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21 st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the ＂Grain for Green＂ policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of ＂Western Development＂, ＂Revitalization of Northeast＂, coupled with rapidly economic development during this period.展开更多
Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in ...Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in the Maowusu Sand Area were analyzed and the relation among these characteristics and the resource utilization efficiency, taxonomic categories and growth forms of the species were assessed. The results showed that species from Chenopodiaceae, Gramineae, Leguminosae which possessed the C 4 photosynthesis pathway, or C 3 pathway and also with nitrogen_fixation capacities had higher or the highest P n values, i.e., 20～30 μmol CO 2·m -2 ·s -1 , while that of evergreen shrub of Pinaceae had the lowest P n values, i.e., 0～5 μmol CO 2·m -2 ·s -1 . Those species from Compositae, Scrophulariaceae, and Gramineae with C 3 pathway but no N_fixation capacity had the highest E rates, i.e., 20～30 mmol H 2O·m -2 ·s -1 and again the evergreen shrub together with some species from Salicaceae and Compositae had the lowest E rates, i.e., 0～5 mmol H 2O·m -2 ·s -1 . Species from Leguminosae, Gramineae and Chenopodiaceae with C 4 pathway or C 3 pathway with N_fixation capacity, both shrubs and grasses, generally had higher WUE . However, even the physiological traits of the same species were habitat_ and season_specific. The values of both P n and E in late summer were much higher than those in early summer, with average increases of 26%, 40% respectively in the four habitats. WUE in late summer was, however, 12% lower. Generally, when the environments became drier as a result of habitats changed, i.e., in the order of wetland, lowland, fixed sand dune and shifting sand dune, P n and E decreased but WUE increased.展开更多
Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit th...Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit the stress signals within cells as well as between cells and tissues,and make appropriate adjustments in their growth and development in order to survive and reproduce.In recent years,significant progress has been made on many fronts of the stress signaling research,particularly in understanding the downstream signaling events that culminate at the activation of stress-and nutrient limitation-responsive genes,cellular ion homeostasis,and growth adjustment.However,the revelation of the early events of stress signaling,particularly the identification of primary stress sensors,still lags behind.In this review,we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.展开更多
The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed ＂dual-track＂ structure...The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed ＂dual-track＂ structure of rural-urban development in China as well as un- stable rural development institution and mechanism. It is necessary to restructure rural pro- duction, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realizing urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring. Basing on the effects analysis of industrialization and urbanization on rural production, living and ecological space, the mechanism of pushing forward rural spatial restructuring by carry- ing out land consolidation is probed. A conceptualization of the models of rural production, living and ecological spatial restructuring is analyzed combining with agricultural land con- solidation, hollowed villages consolidation and industrial and mining land consolidation. Fi- nally, the author argues that a ＂bottom-up＂ restructuring strategy accompanied by a few ＂top-down＂ elements is helpful for smoothly pushing forward rural spatial restructuring in China. In addition, the optimization and restructuring of rural production, living and ecological space will rely on the innovations of regional engineering technology, policy and mechanism, and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development.展开更多
Rural hollowing is a recent geographic phenomenon that has received significant attention in China, which is experiencing rapid urbanization. It has led to the wasteful use of rural land resources, and imposed obstacl...Rural hollowing is a recent geographic phenomenon that has received significant attention in China, which is experiencing rapid urbanization. It has led to the wasteful use of rural land resources, and imposed obstacles on the optimization of land use and coordinated urban-rural development. Rural hollowing has various forms of manifestation, which refers to the neglect and vacancy of rural dwellings, both of which can lead to damage and ultimate abandonment of rural dwellings. Damaged dwellings have different degrees of destruction, ranging from slight, moderate to severe. The evolutive process of rural hollowing in general has five stages, i.e., emergence, growth, flourishing, stability, and decline. Based on the combination of both regional economic development level and its physiographic features, the types of rural hollowing can be categorised as urban fringe, plain agricultural region, hilly agricultural region, and agro-pastoral region. Especially, the plain agricultural region is the most typical one in rural hollowing, which shows the spatial evolution of rural hollowing as a ＂poached egg＂ pattern with a layered hollow core and solid shape. Furthermore, the driving forces behind rural hollowing are identified as the pull of cities and push of rural areas. In particular, this paper identifies contributors to rural hollowing that include rural depopulation in relation to rapid urbanisation and economic change, land ownership and land use policy, and institutional barriers.展开更多
Today, about 30% of world nitrogen (N) fertilizer is consumed by China. Rice crops in China consume about 37% of the total N fertilizer used for rice production in the world. Average rate of N application for rice pro...Today, about 30% of world nitrogen (N) fertilizer is consumed by China. Rice crops in China consume about 37% of the total N fertilizer used for rice production in the world. Average rate of N application for rice production in China is high and fertilizer-N use efficiency is low compared with other major rice growing countries. Research progresses have been made internationally and domestically on the application method, fertilizer-N sources, computer-based decision support systems, and real-time N management in order展开更多
High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production;however,the N budgets of such intensive vegetable production remain to be explored.The goal...High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production;however,the N budgets of such intensive vegetable production remain to be explored.The goal of this study was to determine the annual N balance and loss in a greenhouse vegetable system of annual rotation of tomato,cucumber,and celery at five N (urea) application rates (0,348,522,696,and 870 kg N ha-1 year-1).Total N input to the 0-50 cm soil layer ranged from 531 to 1 053 kg ha-1,and N fertilizer was the main N source,accounting for 66%-83% of the total annual N input.In comparison,irrigation water,wet deposition,and seeds in total accounted for less than 1% of the total N input.The fertilizer N use efficiency was only 18% under the conventional application rate of 870 kg N ha-1 and decreased as the application rate increased from 522 to 870 kg N ha-1.Apparent N losses were 196-201 kg N ha-1,of which 71%-86% was lost by leaching at the application rates of 522-870 kg N ha-1.Thus,leaching was the primary N loss pathway at high N application rates and the amount of N leached was proportional to the N applied during the cucumber season.Moreover,dissolved organic N accounted for 10% of the leached N,whereas NH3 volatilization only contributed 0.1%-0.6% of the apparent N losses under the five N application rates in this greenhouse vegetable system.展开更多
Land use transition refers to the changes in land use morphology （both dominant morphology and recessive morphology） of a certain region over a certain period of time driven by socio-economic change and innovation, ...Land use transition refers to the changes in land use morphology （both dominant morphology and recessive morphology） of a certain region over a certain period of time driven by socio-economic change and innovation, and it usually corresponds to the transition of socio-economic development phase. In China, farmland and rural housing land are the two major sources of land use transition. This paper analyzes the spatio-temporal coupling characteristics of farmland and rural housing land transition in China, using high-resolution Landsat TM （Thematic Mapper） data in 2000 and 2008, and the data from the Ministry of Land and Resources of China. The outcomes indicated that： （1） during 2000-2008, the correlation coefficient of farmland vs. rural housing land change is -0.921, and it shows that the change pattern of farmland and rural housing land is uncoordinated; （2） the result of Spearman rank correlation analysis shows that rural housing land change has played a major role in the mutual transformation of farmland and rural housing land; and （3） it shows a high-degree spatial coupling between farmland and rural housing land change in southeast China during 2000-2008. In general, farmland and rural housing land transition in China is driven by socio-economic, bio-physical and managerial three-dimensional driving factors through the interactions among rural population, farmland and rural housing land. However, the spatio-temporal coupling phenomenon and mechanism of farmland and rural housing land transition in China are largely due to the ＂dual-track＂ structure of rural-urban development.展开更多
基金National Basic Research Program of China, No.2009CB421105National Key Technology R&D Program, No.2006BAC08B00Knowledge Innovation Program of the CAS, No.KSCX1-YW-09-01
文摘Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science （LCS） in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21 st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the ＂Grain for Green＂ policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of ＂Western Development＂, ＂Revitalization of Northeast＂, coupled with rapidly economic development during this period.
文摘Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in the Maowusu Sand Area were analyzed and the relation among these characteristics and the resource utilization efficiency, taxonomic categories and growth forms of the species were assessed. The results showed that species from Chenopodiaceae, Gramineae, Leguminosae which possessed the C 4 photosynthesis pathway, or C 3 pathway and also with nitrogen_fixation capacities had higher or the highest P n values, i.e., 20～30 μmol CO 2·m -2 ·s -1 , while that of evergreen shrub of Pinaceae had the lowest P n values, i.e., 0～5 μmol CO 2·m -2 ·s -1 . Those species from Compositae, Scrophulariaceae, and Gramineae with C 3 pathway but no N_fixation capacity had the highest E rates, i.e., 20～30 mmol H 2O·m -2 ·s -1 and again the evergreen shrub together with some species from Salicaceae and Compositae had the lowest E rates, i.e., 0～5 mmol H 2O·m -2 ·s -1 . Species from Leguminosae, Gramineae and Chenopodiaceae with C 4 pathway or C 3 pathway with N_fixation capacity, both shrubs and grasses, generally had higher WUE . However, even the physiological traits of the same species were habitat_ and season_specific. The values of both P n and E in late summer were much higher than those in early summer, with average increases of 26%, 40% respectively in the four habitats. WUE in late summer was, however, 12% lower. Generally, when the environments became drier as a result of habitats changed, i.e., in the order of wetland, lowland, fixed sand dune and shifting sand dune, P n and E decreased but WUE increased.
文摘Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit the stress signals within cells as well as between cells and tissues,and make appropriate adjustments in their growth and development in order to survive and reproduce.In recent years,significant progress has been made on many fronts of the stress signaling research,particularly in understanding the downstream signaling events that culminate at the activation of stress-and nutrient limitation-responsive genes,cellular ion homeostasis,and growth adjustment.However,the revelation of the early events of stress signaling,particularly the identification of primary stress sensors,still lags behind.In this review,we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.
基金National Natural Science Foundation of China,No.41171149No.41130748No.41201176
文摘The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed ＂dual-track＂ structure of rural-urban development in China as well as un- stable rural development institution and mechanism. It is necessary to restructure rural pro- duction, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realizing urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring. Basing on the effects analysis of industrialization and urbanization on rural production, living and ecological space, the mechanism of pushing forward rural spatial restructuring by carry- ing out land consolidation is probed. A conceptualization of the models of rural production, living and ecological spatial restructuring is analyzed combining with agricultural land con- solidation, hollowed villages consolidation and industrial and mining land consolidation. Fi- nally, the author argues that a ＂bottom-up＂ restructuring strategy accompanied by a few ＂top-down＂ elements is helpful for smoothly pushing forward rural spatial restructuring in China. In addition, the optimization and restructuring of rural production, living and ecological space will rely on the innovations of regional engineering technology, policy and mechanism, and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development.
基金National Natural Science Foundation of China, No.40635029 No.40871257+1 种基金 Knowledge Innovation Program of the Chinese Academy of Sciences, No.KSCX-YW-09 No.KZCX2-YW-QN304
文摘Rural hollowing is a recent geographic phenomenon that has received significant attention in China, which is experiencing rapid urbanization. It has led to the wasteful use of rural land resources, and imposed obstacles on the optimization of land use and coordinated urban-rural development. Rural hollowing has various forms of manifestation, which refers to the neglect and vacancy of rural dwellings, both of which can lead to damage and ultimate abandonment of rural dwellings. Damaged dwellings have different degrees of destruction, ranging from slight, moderate to severe. The evolutive process of rural hollowing in general has five stages, i.e., emergence, growth, flourishing, stability, and decline. Based on the combination of both regional economic development level and its physiographic features, the types of rural hollowing can be categorised as urban fringe, plain agricultural region, hilly agricultural region, and agro-pastoral region. Especially, the plain agricultural region is the most typical one in rural hollowing, which shows the spatial evolution of rural hollowing as a ＂poached egg＂ pattern with a layered hollow core and solid shape. Furthermore, the driving forces behind rural hollowing are identified as the pull of cities and push of rural areas. In particular, this paper identifies contributors to rural hollowing that include rural depopulation in relation to rapid urbanisation and economic change, land ownership and land use policy, and institutional barriers.
文摘Today, about 30% of world nitrogen (N) fertilizer is consumed by China. Rice crops in China consume about 37% of the total N fertilizer used for rice production in the world. Average rate of N application for rice production in China is high and fertilizer-N use efficiency is low compared with other major rice growing countries. Research progresses have been made internationally and domestically on the application method, fertilizer-N sources, computer-based decision support systems, and real-time N management in order
基金Supported by the National Natural Science Foundation of China-Japan Science and Technology Agency (NSFC-JST)Major International Joint Research Project (No. 30821140542)+1 种基金the National Basic Research Program (973 Program) of China (No. 2007CB109303)the Major Science and Technology Program for Water Pollution Control and Treatment of China (No. 2008ZX07101-005)
文摘High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production;however,the N budgets of such intensive vegetable production remain to be explored.The goal of this study was to determine the annual N balance and loss in a greenhouse vegetable system of annual rotation of tomato,cucumber,and celery at five N (urea) application rates (0,348,522,696,and 870 kg N ha-1 year-1).Total N input to the 0-50 cm soil layer ranged from 531 to 1 053 kg ha-1,and N fertilizer was the main N source,accounting for 66%-83% of the total annual N input.In comparison,irrigation water,wet deposition,and seeds in total accounted for less than 1% of the total N input.The fertilizer N use efficiency was only 18% under the conventional application rate of 870 kg N ha-1 and decreased as the application rate increased from 522 to 870 kg N ha-1.Apparent N losses were 196-201 kg N ha-1,of which 71%-86% was lost by leaching at the application rates of 522-870 kg N ha-1.Thus,leaching was the primary N loss pathway at high N application rates and the amount of N leached was proportional to the N applied during the cucumber season.Moreover,dissolved organic N accounted for 10% of the leached N,whereas NH3 volatilization only contributed 0.1%-0.6% of the apparent N losses under the five N application rates in this greenhouse vegetable system.
基金National Natural Science Foundation of China, No.41171149 No.41130748 Knowledge Innovation Program of the Chinese Academy of Sciences, No.KZCX2-YW-QN304
文摘Land use transition refers to the changes in land use morphology （both dominant morphology and recessive morphology） of a certain region over a certain period of time driven by socio-economic change and innovation, and it usually corresponds to the transition of socio-economic development phase. In China, farmland and rural housing land are the two major sources of land use transition. This paper analyzes the spatio-temporal coupling characteristics of farmland and rural housing land transition in China, using high-resolution Landsat TM （Thematic Mapper） data in 2000 and 2008, and the data from the Ministry of Land and Resources of China. The outcomes indicated that： （1） during 2000-2008, the correlation coefficient of farmland vs. rural housing land change is -0.921, and it shows that the change pattern of farmland and rural housing land is uncoordinated; （2） the result of Spearman rank correlation analysis shows that rural housing land change has played a major role in the mutual transformation of farmland and rural housing land; and （3） it shows a high-degree spatial coupling between farmland and rural housing land change in southeast China during 2000-2008. In general, farmland and rural housing land transition in China is driven by socio-economic, bio-physical and managerial three-dimensional driving factors through the interactions among rural population, farmland and rural housing land. However, the spatio-temporal coupling phenomenon and mechanism of farmland and rural housing land transition in China are largely due to the ＂dual-track＂ structure of rural-urban development.
