Carbon storage serves as a key indicator of ecosystem services and plays a vital role in maintaining the global carbon balance.Land use and cover change(LUCC)is one of the primary drivers influencing carbon storage va...Carbon storage serves as a key indicator of ecosystem services and plays a vital role in maintaining the global carbon balance.Land use and cover change(LUCC)is one of the primary drivers influencing carbon storage variations in terrestrial ecosystems.Therefore,evaluating the impacts of LUCC on carbon storage is crucial for achieving strategic goals such as the China’s dual carbon goals(including carbon peaking and carbon neutrality).This study focuses on the Aral Irrigation Area in Xinjiang Uygur Autonomous Region,China,to assess the impacts of LUCC on regional carbon storage and their spatiotemporal dynamics.A comprehensive LUCC database from 2000 to 2020 was developed using Landsat satellite imagery and the random forest classification algorithm.The integrated valuation of ecosystem services and trade-offs(InVEST)model was applied to quantify carbon storage and analyze its response to LUCC.Additionally,future LUCC patterns for 2030 were projected under multiple development scenarios using the patch-generating land use simulation(PLUS)model.These future LUCC scenarios were integrated with the InVEST model to simulate carbon storage trends under different land management pathways.Between 2000 and 2020,the dominant land use types in the study area were cropland(area proportion of 35.52%),unused land(34.80%),and orchard land(12.19%).The conversion of unused land and orchard land significantly expanded the area of cropland,which increased by 115,742.55 hm^(2).During this period,total carbon storage and carbon density increased by 7.87×10^(6) Mg C and 20.19 Mg C/hm^(2),respectively.The primary driver of this increase was the conversion of unused land into cropland,accounting for 49.28%of the total carbon storage gain.Carbon storage was notably lower along the northeastern and southeastern edges.By 2030,the projected carbon storage is expected to increase by 0.99×10^(6),1.55×10^(6),and 1.71×10^(6) Mg C under the natural development,cropland protection,and ecological conservation scenarios,respectively.In contrast,under the urban development scenario,carbon storage is projected to decline by 0.40×10^(6) Mg C.In line with China’s dual carbon goals,the ecological conservation scenario emerges as the most effective strategy for enhancing carbon storage.Accordingly,strict enforcement of the cropland red line is recommended.This study provides a valuable scientific foundation for regional ecosystem restoration and sustainable development in arid regions.展开更多
随着点源污染的控制与处理技术日趋完善,非点源污染成为重要的水污染源。武强溪作为流入千岛湖的第二大支流,量化武强溪流域非点源污染负荷,解析非点源污染时空分布特征,提出适合削减武强溪流域污染物的最佳管理措施(best management pr...随着点源污染的控制与处理技术日趋完善,非点源污染成为重要的水污染源。武强溪作为流入千岛湖的第二大支流,量化武强溪流域非点源污染负荷,解析非点源污染时空分布特征,提出适合削减武强溪流域污染物的最佳管理措施(best management practices,BMPs)对千岛湖水污染高效治理至关重要。该研究基于土壤水分评估工具(Soil and water assessment tool,SWAT)分析了武强溪流域径流量、总氮输出负荷量的时空分布特征,探究了不同管理措施及组合的削减效果,提出了武强溪流域非点源污染针对性的治理措施。结果表明:1)SWAT模型对于武强溪流域径流量和总氮输出负荷量的模拟具有较好的适用性,径流量校准期和验证期的决定系数(coefficient of determination,R^(2))分别为0.86、0.97,纳什系数(nash-sutcliffe coefficient,NSE)分别为0.83、0.96,百分比偏差(percent bias,PBIAS)分别为15.8%、-6.3%,总氮校准期和验证期的决定系数分别为0.87、0.74,纳什系数分别为0.63、0.66,百分比偏差分别为31.6%、21.2%;2)该流域径流量和总氮负荷主要集中在3—7月,分别占全年输出量的71.67%和75.76%。综合考虑氮的来源和流失途径,将耕地和林地面积占比大、坡度陡的子流域设置为总氮的关键污染源区。考虑调整化肥施用量/配方、改变耕作方式和设置植被缓冲带等削减非点源污染的手段,进行总氮输出负荷削减效率的情景模拟,表明10 m植被缓冲带是减少总氮输出负荷的最佳单一控制策略,总氮削减率可达到69.90%;实施综合管理措施对总氮的污染削减效果更佳,10 m植被缓冲带与施肥量减少20%可使总氮削减率达到74.79%。研究结果可为千岛湖水质管理与控制提供理论基础。展开更多
Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency（WUE） of maize for seed producti...Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency（WUE） of maize for seed production. Five planting densities of 6.75, 8.25, 9.75, 11.25 and 12.75 plants/m^2 were conducted in 2012, and a planting density of 14.25 plants/m^2 was added from 2013 to 2015. Through comparison with the Aqua Crop yield model, a modified model was developed to estimate the biomass accumulation and yield under different planting densities using adjustment coefficient for normalized biomass water productivity and harvest index. It was found that the modified yield model had a better performance and could generate results with higher determination coefficient and lower error. The results indicated that higher planting density increased the leaf area index and biomass accumulation, but decreased the biomass accumulation per plant. The total yield increased rapidly as planting density increased to 11.25 plants/m^2, but only a slight increase was observed when the density was greater than 11.25 plants/m^2. The WUE also reached the maximum when planting density was 11.25 plants/m^2, which was the recommended planting density of maize for seed production in Northwest China.展开更多
The mechanism of atmospheric, surface and soil water interactions (water transformation) in hillslope under natural conditions was analyzed, and a dynamic model was developed to simulate infiltration, overland flow an...The mechanism of atmospheric, surface and soil water interactions (water transformation) in hillslope under natural conditions was analyzed, and a dynamic model was developed to simulate infiltration, overland flow and soil water movement during natural rainfall in hillslope, by bringing forward concepts such. as rainfall intensity on slope and a correction coefficient of saturated soil water content for soil surface seal. Some factors, including slope angle, slope orientation and raindrop inclination, which affect the rainfall amount on slope, were taken into account while developing the dynamic model. The effect of surface seal on infiltration and water balance under a boundary condition of the second kind was also considered. Application of the model in a field experiment showed that the model simulated precisely the infiltration, overland flow and soil water movement in hillslope under natural rainfall conditions.展开更多
Water and nitrogen（N） are generally two of the most important factors in determining the crop productivity. Proper water and N managements are prerequisites for agriculture sustainable development in arid areas. Fie...Water and nitrogen（N） are generally two of the most important factors in determining the crop productivity. Proper water and N managements are prerequisites for agriculture sustainable development in arid areas. Field experiments were conducted to study the responses of water productivity for crop yield（WP_（Y-ET）） and final biomass（WP_（B-ET）） of film-mulched hybrid maize seed production to different irrigation and N treatments in the Hexi Corridor, Northwest China during April to September in 2013 and also during April to September in 2014. Three irrigation levels（70%–65%, 60%–55%, and 50%–45% of the field capacity） combined with three N rates（500, 400, and 300 kg N/hm^2） were tested in 2013. The N treatments were adjusted to 500, 300, and 100 kg N/hm^2 in 2014. Results showed that the responses of WP_（Y-ET） and WP_（B-ET） to different irrigation amounts were different. WP_（Y-ET） was significantly reduced by lowering irrigation amounts while WP_（B-ET） stayed relatively insensitive to irrigation amounts. However, WP_（Y-ET） and WP_（B-ET） behaved consistently when subjected to different N treatments. There was a slight effect of reducing N input from 500 to 300 kg/hm^2 on the WP_（Y-ET） and WP_（B-ET）, however, when reducing N input to 100 kg/hm^2, the values of WP_（Y-ET） and WP_（B-ET） were significantly reduced. Water is the primary factor and N is the secondary factor in determining both yield（Y） and final biomass（B）. Partial factor productivity from applied N（PFP_N） was the maximum under the higher irrigation level and in lower N rate（100–300 kg N/hm^2） in both years（2013 and 2014）. Lowering the irrigation amount significantly reduced evapotranspiration（ET）, but ET did not vary with different N rates（100–500 kg N/hm^2）. Both Y and B had robust linear relationships with ET, but the correlation between B and ET（R^2=0.8588） was much better than that between Y and ET（R^2=0.6062）. When ET increased, WP_（Y-ET） linearly increased and WP_（B-ET） decreased. Taking the indices of Y, B, WP_（Y-ET）, WP_（B-ET） and PFP_N into account, a higher irrigation level（70%–65% of the field capacity） and a lower N rate（100–300 kg N/hm^2） are recommended to be a proper irrigation and N application strategy for plastic film-mulched hybrid maize seed production in arid Northwest China.展开更多
Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in wat...Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions.展开更多
Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soi...Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soil conductance, soil-root conductance and root conductance. The vaues and relative importance varywith soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulicconductance of roots in wet soils, the soil-root interfaCe becomes a major limiting factor to water uptake inmoderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance inseriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be usedto evaluate the drought-resistance and water use efficiency of crops.展开更多
In this study the principal component analysis (PCA) and geographically weighted regression (GWR) are combined to estimate the spatial distribution of water requirement of the winter wheat in North China while the eff...In this study the principal component analysis (PCA) and geographically weighted regression (GWR) are combined to estimate the spatial distribution of water requirement of the winter wheat in North China while the effect of the macroand micro-topographic as well as the meteorological factors on the crop water requirement is taking into account. The spatial distribution characteristic of the water requirement of the winter wheat in North China and its formation are analyzed based on the spatial variation of the main affecting factors and the regression coefficients. The findings reveal that the collinearity can be effectively removed when PCA is applied to process all of the affecting factors. The regression coefficients of GWR displayed a strong variability in space, which can better explain the spatial differences of the effect of the affecting factors on the crop water requirement. The evaluation index of the proposed method in this study is more efficient than the widely used Kriging method. Besides, it could clearly show the effect of those affecting factors in different spatial locations on the crop water requirement and provide more detailed information on the region where those factors suddenly change. To sum up, it is of great reference significance for the estimation of the regional crop water requirement.展开更多
基金supported by the National Key R&D Program of China(2022YFD1900503).
文摘Carbon storage serves as a key indicator of ecosystem services and plays a vital role in maintaining the global carbon balance.Land use and cover change(LUCC)is one of the primary drivers influencing carbon storage variations in terrestrial ecosystems.Therefore,evaluating the impacts of LUCC on carbon storage is crucial for achieving strategic goals such as the China’s dual carbon goals(including carbon peaking and carbon neutrality).This study focuses on the Aral Irrigation Area in Xinjiang Uygur Autonomous Region,China,to assess the impacts of LUCC on regional carbon storage and their spatiotemporal dynamics.A comprehensive LUCC database from 2000 to 2020 was developed using Landsat satellite imagery and the random forest classification algorithm.The integrated valuation of ecosystem services and trade-offs(InVEST)model was applied to quantify carbon storage and analyze its response to LUCC.Additionally,future LUCC patterns for 2030 were projected under multiple development scenarios using the patch-generating land use simulation(PLUS)model.These future LUCC scenarios were integrated with the InVEST model to simulate carbon storage trends under different land management pathways.Between 2000 and 2020,the dominant land use types in the study area were cropland(area proportion of 35.52%),unused land(34.80%),and orchard land(12.19%).The conversion of unused land and orchard land significantly expanded the area of cropland,which increased by 115,742.55 hm^(2).During this period,total carbon storage and carbon density increased by 7.87×10^(6) Mg C and 20.19 Mg C/hm^(2),respectively.The primary driver of this increase was the conversion of unused land into cropland,accounting for 49.28%of the total carbon storage gain.Carbon storage was notably lower along the northeastern and southeastern edges.By 2030,the projected carbon storage is expected to increase by 0.99×10^(6),1.55×10^(6),and 1.71×10^(6) Mg C under the natural development,cropland protection,and ecological conservation scenarios,respectively.In contrast,under the urban development scenario,carbon storage is projected to decline by 0.40×10^(6) Mg C.In line with China’s dual carbon goals,the ecological conservation scenario emerges as the most effective strategy for enhancing carbon storage.Accordingly,strict enforcement of the cropland red line is recommended.This study provides a valuable scientific foundation for regional ecosystem restoration and sustainable development in arid regions.
文摘随着点源污染的控制与处理技术日趋完善,非点源污染成为重要的水污染源。武强溪作为流入千岛湖的第二大支流,量化武强溪流域非点源污染负荷,解析非点源污染时空分布特征,提出适合削减武强溪流域污染物的最佳管理措施(best management practices,BMPs)对千岛湖水污染高效治理至关重要。该研究基于土壤水分评估工具(Soil and water assessment tool,SWAT)分析了武强溪流域径流量、总氮输出负荷量的时空分布特征,探究了不同管理措施及组合的削减效果,提出了武强溪流域非点源污染针对性的治理措施。结果表明:1)SWAT模型对于武强溪流域径流量和总氮输出负荷量的模拟具有较好的适用性,径流量校准期和验证期的决定系数(coefficient of determination,R^(2))分别为0.86、0.97,纳什系数(nash-sutcliffe coefficient,NSE)分别为0.83、0.96,百分比偏差(percent bias,PBIAS)分别为15.8%、-6.3%,总氮校准期和验证期的决定系数分别为0.87、0.74,纳什系数分别为0.63、0.66,百分比偏差分别为31.6%、21.2%;2)该流域径流量和总氮负荷主要集中在3—7月,分别占全年输出量的71.67%和75.76%。综合考虑氮的来源和流失途径,将耕地和林地面积占比大、坡度陡的子流域设置为总氮的关键污染源区。考虑调整化肥施用量/配方、改变耕作方式和设置植被缓冲带等削减非点源污染的手段,进行总氮输出负荷削减效率的情景模拟,表明10 m植被缓冲带是减少总氮输出负荷的最佳单一控制策略,总氮削减率可达到69.90%;实施综合管理措施对总氮的污染削减效果更佳,10 m植被缓冲带与施肥量减少20%可使总氮削减率达到74.79%。研究结果可为千岛湖水质管理与控制提供理论基础。
基金the research grants from the National Natural Science Foundation of China (51379208, 91425302, 51621061)the Government Public Research Funds for Projects of the Ministry of Agriculture (201503125)the Discipline Innovative Engineering Plan (111 Program, B14002)
文摘Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency（WUE） of maize for seed production. Five planting densities of 6.75, 8.25, 9.75, 11.25 and 12.75 plants/m^2 were conducted in 2012, and a planting density of 14.25 plants/m^2 was added from 2013 to 2015. Through comparison with the Aqua Crop yield model, a modified model was developed to estimate the biomass accumulation and yield under different planting densities using adjustment coefficient for normalized biomass water productivity and harvest index. It was found that the modified yield model had a better performance and could generate results with higher determination coefficient and lower error. The results indicated that higher planting density increased the leaf area index and biomass accumulation, but decreased the biomass accumulation per plant. The total yield increased rapidly as planting density increased to 11.25 plants/m^2, but only a slight increase was observed when the density was greater than 11.25 plants/m^2. The WUE also reached the maximum when planting density was 11.25 plants/m^2, which was the recommended planting density of maize for seed production in Northwest China.
基金Project (No. 49725102) supported by the National Natural Science Foundation of China.
文摘The mechanism of atmospheric, surface and soil water interactions (water transformation) in hillslope under natural conditions was analyzed, and a dynamic model was developed to simulate infiltration, overland flow and soil water movement during natural rainfall in hillslope, by bringing forward concepts such. as rainfall intensity on slope and a correction coefficient of saturated soil water content for soil surface seal. Some factors, including slope angle, slope orientation and raindrop inclination, which affect the rainfall amount on slope, were taken into account while developing the dynamic model. The effect of surface seal on infiltration and water balance under a boundary condition of the second kind was also considered. Application of the model in a field experiment showed that the model simulated precisely the infiltration, overland flow and soil water movement in hillslope under natural rainfall conditions.
基金supported by the National Natural Science Foundation of China (51621061, 91425302, 51379208)the Research Projects of the Agricultural Public Welfare Industry in China (201503125)the Discipline Innovative Engineering Plan (111 Program, B14002)
文摘Water and nitrogen（N） are generally two of the most important factors in determining the crop productivity. Proper water and N managements are prerequisites for agriculture sustainable development in arid areas. Field experiments were conducted to study the responses of water productivity for crop yield（WP_（Y-ET）） and final biomass（WP_（B-ET）） of film-mulched hybrid maize seed production to different irrigation and N treatments in the Hexi Corridor, Northwest China during April to September in 2013 and also during April to September in 2014. Three irrigation levels（70%–65%, 60%–55%, and 50%–45% of the field capacity） combined with three N rates（500, 400, and 300 kg N/hm^2） were tested in 2013. The N treatments were adjusted to 500, 300, and 100 kg N/hm^2 in 2014. Results showed that the responses of WP_（Y-ET） and WP_（B-ET） to different irrigation amounts were different. WP_（Y-ET） was significantly reduced by lowering irrigation amounts while WP_（B-ET） stayed relatively insensitive to irrigation amounts. However, WP_（Y-ET） and WP_（B-ET） behaved consistently when subjected to different N treatments. There was a slight effect of reducing N input from 500 to 300 kg/hm^2 on the WP_（Y-ET） and WP_（B-ET）, however, when reducing N input to 100 kg/hm^2, the values of WP_（Y-ET） and WP_（B-ET） were significantly reduced. Water is the primary factor and N is the secondary factor in determining both yield（Y） and final biomass（B）. Partial factor productivity from applied N（PFP_N） was the maximum under the higher irrigation level and in lower N rate（100–300 kg N/hm^2） in both years（2013 and 2014）. Lowering the irrigation amount significantly reduced evapotranspiration（ET）, but ET did not vary with different N rates（100–500 kg N/hm^2）. Both Y and B had robust linear relationships with ET, but the correlation between B and ET（R^2=0.8588） was much better than that between Y and ET（R^2=0.6062）. When ET increased, WP_（Y-ET） linearly increased and WP_（B-ET） decreased. Taking the indices of Y, B, WP_（Y-ET）, WP_（B-ET） and PFP_N into account, a higher irrigation level（70%–65% of the field capacity） and a lower N rate（100–300 kg N/hm^2） are recommended to be a proper irrigation and N application strategy for plastic film-mulched hybrid maize seed production in arid Northwest China.
基金supported by the National Key Research and Development Program of China (2016YFC0400207)the National Natural Science Foundation of China (51222905, 51621061, 51509130)+2 种基金the Natural Science Foundation of Jiangsu Province, China (BK20150908)the Discipline Innovative Engineering Plan (111 Program, B14002)the Jiangsu Key Laboratory of Agricultural Meteorology Foundation (JKLAM1601)
文摘Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions.
文摘Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soil conductance, soil-root conductance and root conductance. The vaues and relative importance varywith soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulicconductance of roots in wet soils, the soil-root interfaCe becomes a major limiting factor to water uptake inmoderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance inseriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be usedto evaluate the drought-resistance and water use efficiency of crops.
基金supported by the National Basic Research Program of China (2006CB403406)the National Natural Science Foundation of China(51079154)the National HighTech Research & Development Program of China (2011AA100502)
文摘In this study the principal component analysis (PCA) and geographically weighted regression (GWR) are combined to estimate the spatial distribution of water requirement of the winter wheat in North China while the effect of the macroand micro-topographic as well as the meteorological factors on the crop water requirement is taking into account. The spatial distribution characteristic of the water requirement of the winter wheat in North China and its formation are analyzed based on the spatial variation of the main affecting factors and the regression coefficients. The findings reveal that the collinearity can be effectively removed when PCA is applied to process all of the affecting factors. The regression coefficients of GWR displayed a strong variability in space, which can better explain the spatial differences of the effect of the affecting factors on the crop water requirement. The evaluation index of the proposed method in this study is more efficient than the widely used Kriging method. Besides, it could clearly show the effect of those affecting factors in different spatial locations on the crop water requirement and provide more detailed information on the region where those factors suddenly change. To sum up, it is of great reference significance for the estimation of the regional crop water requirement.
