Spatiotemporal patterns of dust storms are affected by climate change through changes in convective instability, regional meteorological characteristics, and local sediment supply. Linking dust storm dynamics to clima...Spatiotemporal patterns of dust storms are affected by climate change through changes in convective instability, regional meteorological characteristics, and local sediment supply. Linking dust storm dynamics to climate change helps the understanding of what controls the initiation of dust storms, and assists the prediction of future dust storm occurrence. This study examines the temporal dynamics of spring dust storms in Inner Mongolia, a major dust source area in East Asia. We found that severe spring dust storms have significantly declined from1954 to 2007. Four dust storm types showed similar decreasing trends from 2001 to 2012. This change in spring dust storm dynamics is attributed to the shift in vegetation green-up dates based on the analysis of a satellite derived vegetation index. Earlier vegetation green-up has a dampening effect on spring dust storms. Suitable environmental conditions for vegetation green-up hinder the emergence of dust storms. This study expands our understanding of the dynamics of spring dust storms in the changing climate through a new perspective on vegetation phenology in the spring.展开更多
An experiment was conducted in an oasis area in northwest China to assess the coupling effects of water and nitrogen supply through drip irrigation on photosynthetic characteristics,nitrogen uptake,and yield of sunflo...An experiment was conducted in an oasis area in northwest China to assess the coupling effects of water and nitrogen supply through drip irrigation on photosynthetic characteristics,nitrogen uptake,and yield of sunflower(Helianthus annuus L.),as well as the nitrate distribution in the root-zone soil.The experiment included three irrigation levels(210[W1],300[W2],and 390[W3]mm),three nitrogen levels(162[N1],232[N2],and 302[N3]kg/hm^(2)),and control treatment(no fertilization during whole growth period and only irrigated at the budding stage).A nitrogen content over-accumulation in the soil was observed under the low irrigation amount with high fertilizer supply,which cannot enhance the sunflowers’absorption of nitrogen.Excessive irrigation caused leach of the soil nitrogen,reduced nitrogen content in the root-zone soil(0-40 cm)and limited nitrogen uptake by the crop.Although low irrigation amount with high fertilizer supply can increase the nitrogen content in the soil,it cannot enhance the sunflowers’absorption of nitrogen.At the vegetative stage of sunflower growth,the accumulation of nitrogen in the organs was mainly concentrated in the leaves,while it was transferred to the flower disk at the reproductive growth stage.Reasonable coupling of water and nitrogen improved the transport of nitrogen from leaves and stems to the flower disk and promoted the formation of yield components.Six regression equations were established with irrigation and fertilization amount as independent variables,and seed rate,seed weight per flowerdisk,1000 grain weight,yield,water use efficiency and nitrogen partial factor productivity as dependent variables,respectively.Multiple regression and spatial analysis suggested that the irrigation amount of 241.62-253.35 mm and the fertilization application of 202.02-209.40 N kg/hm^(2)was a good irrigation strategy,under which all six factors exceed 75%of their maxima,and the yield of sunflower reached 3229.3 kg/hm^(2).展开更多
基金supported by the National Natural Science Foundation of China (41171401)the National Basic Research Program of China (973) (2012CB955402) Programs
文摘Spatiotemporal patterns of dust storms are affected by climate change through changes in convective instability, regional meteorological characteristics, and local sediment supply. Linking dust storm dynamics to climate change helps the understanding of what controls the initiation of dust storms, and assists the prediction of future dust storm occurrence. This study examines the temporal dynamics of spring dust storms in Inner Mongolia, a major dust source area in East Asia. We found that severe spring dust storms have significantly declined from1954 to 2007. Four dust storm types showed similar decreasing trends from 2001 to 2012. This change in spring dust storm dynamics is attributed to the shift in vegetation green-up dates based on the analysis of a satellite derived vegetation index. Earlier vegetation green-up has a dampening effect on spring dust storms. Suitable environmental conditions for vegetation green-up hinder the emergence of dust storms. This study expands our understanding of the dynamics of spring dust storms in the changing climate through a new perspective on vegetation phenology in the spring.
基金supported by Scientific and Technological Innovation Team Project of Xinjiang Production and Construction Corps(Grant No.2019CB004).
文摘An experiment was conducted in an oasis area in northwest China to assess the coupling effects of water and nitrogen supply through drip irrigation on photosynthetic characteristics,nitrogen uptake,and yield of sunflower(Helianthus annuus L.),as well as the nitrate distribution in the root-zone soil.The experiment included three irrigation levels(210[W1],300[W2],and 390[W3]mm),three nitrogen levels(162[N1],232[N2],and 302[N3]kg/hm^(2)),and control treatment(no fertilization during whole growth period and only irrigated at the budding stage).A nitrogen content over-accumulation in the soil was observed under the low irrigation amount with high fertilizer supply,which cannot enhance the sunflowers’absorption of nitrogen.Excessive irrigation caused leach of the soil nitrogen,reduced nitrogen content in the root-zone soil(0-40 cm)and limited nitrogen uptake by the crop.Although low irrigation amount with high fertilizer supply can increase the nitrogen content in the soil,it cannot enhance the sunflowers’absorption of nitrogen.At the vegetative stage of sunflower growth,the accumulation of nitrogen in the organs was mainly concentrated in the leaves,while it was transferred to the flower disk at the reproductive growth stage.Reasonable coupling of water and nitrogen improved the transport of nitrogen from leaves and stems to the flower disk and promoted the formation of yield components.Six regression equations were established with irrigation and fertilization amount as independent variables,and seed rate,seed weight per flowerdisk,1000 grain weight,yield,water use efficiency and nitrogen partial factor productivity as dependent variables,respectively.Multiple regression and spatial analysis suggested that the irrigation amount of 241.62-253.35 mm and the fertilization application of 202.02-209.40 N kg/hm^(2)was a good irrigation strategy,under which all six factors exceed 75%of their maxima,and the yield of sunflower reached 3229.3 kg/hm^(2).
