Horqin Sand Land is regarded as the t ypical region for studying the probl em of desertification.The integra-tion of 3S(GIS,GPS and RS)techniques offer a most helpful meth od to study and monitor the dynamics o f dese...Horqin Sand Land is regarded as the t ypical region for studying the probl em of desertification.The integra-tion of 3S(GIS,GPS and RS)techniques offer a most helpful meth od to study and monitor the dynamics o f desertification.Based on the data derived from3perio ds’ multitemporal Landsat TMimagery of the 1990s,the regional land use a nd dynam-ics of desertification in Horqin San d Land were studied.The main results revealed that:1)as long as the general change tendency was concerned,the deserti fication of Horqin Sand Land would co ntinue to spread;2)there was a gradual de-crease in the area of both moving sand dunes and semi-stabilized ones,whi ch meant that fruitful progress had b een made to control the desertification during the 1990s;3)as a result of unreasonable cultivation,the total area of stabilized san d dunes and grassland in the middle and western region decreased obviously.It suggested that the increasing damage caused by human was leading to the hazard of further desertification.So i n the future,it is necessary to take more effec-tive measures to control the spread o f desertification and restore the degraded ecosystems for the purpose of optimizing the global eco-environment in Horqin Sand Land.展开更多
The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing image...The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing images, this study utilizes geomorphology and landscape ecology to monitor and analyze the aeolian geomorphology characteristics of the Horqin Sandy Land. Results show that the sand dunes of the Horqin Sandy Land are mainly distributed on alluvial plains along the banks of the mainstream and tributaries of the Western Liao River, and the sand dune types tend to simplify from west to east and from south to north. The aeolian geomorphology coverage tend to be decreasing in the past 40 years, with an average annual change rate of 0.31%. While the area of traveling dunes decreased, the area of fixed and semi-fixed dunes increased. The fractal dimensions of various types of sand dune have all remained relatively constant between 1.07 and 1.10, suggesting that they are experiencing a relatively stable evolutionary process. There is a complex interaction between fluvial and aeolian processes of the Horqin Sandy Land, which plays a central role in surface landscape molding. Sand dunes on both sides of different rivers on the Horqin Sandy Land present certain regularity and different characteristics in terms of morphology, developmental scale, and spatial pattern. There are six fluvial-aeolian interaction modes in this area: supply of sand sources by rivers for sand dune development, complete obstruction of dune migration by rivers, partial obstruction of dune migration by rivers, influence of river valleys on dune developmental types on both sides, influence of river valleys on dune developmental scale on both sides, and river diversion due to obstruction and forcing by sand dunes. This study deepens our understanding of the surface process mechanism of the interaction between fluvial and aeolian processes in semi-arid regions, and provides a basis for researches on regional landscape responses in the context of global environmental change.展开更多
Growth and physiological responses of wheat to sand burial were studied in Horqin Sandy Land, to determine the impact on productivity and survival as well as antioxidant enzymes responses. This study consisted of one ...Growth and physiological responses of wheat to sand burial were studied in Horqin Sandy Land, to determine the impact on productivity and survival as well as antioxidant enzymes responses. This study consisted of one control （no sand） and four sand burial treatments： 25%, 50%, 75% and 100% of seedling height, respectively. Minor burial （25%） had no effect on wheat growth and survival; deep burial （100%） was fatal, and the others had an intermediate effect. Thus, the survival limit to sand burial was equal to seedling height. Sand burial mainly decreased shoot biomass and crop yield, but had small effects on belowground biomass. Superoxide dismutase （SOD） activity increased with time after burial in all treatments with surviving plants. Peroxidase （POD） activity increased after six days under burial, and catalase （CAT） activity de- creased after burial, but recovered after 12 days. The concentration of malondialdehyde （MDA）, a marker for oxidative stress, was low on the sixth day, but increased thereafter with burial depth. Thus, sand burial 〉25% should be avoided due to growth rate reduction leading to reduced crop yield, and even 25% burial showed physiological indicators of stress.展开更多
In this study, the eff ects of soil moisture on sand saltation and dust emission over the Horqin Sandy Land area are investigated, based on observations of three dust events in 2010. The minimum friction velocity init...In this study, the eff ects of soil moisture on sand saltation and dust emission over the Horqin Sandy Land area are investigated, based on observations of three dust events in 2010. The minimum friction velocity initiating the motion of surface particles, namely, the threshold friction velocity, is estimated to be 0.34, 0.40, and 0.50 m s？1 under the very dry, dry, and wet soil conditions, respectively. In comparison with the observations during the dust events under the very dry and dry soil conditions, the dust emission fl ux during the wet event is smaller, but the saltation activities of sand particles （d≧50 μm） are stronger. The size distributions of airborne dust particles （0.1≦d≦20 μm） show that concentrations of the fi ner dust particles （0.1≦d≦0.3 μm） have a secondary peak under dry soil conditions, while they are absent under wet soil conditions. This suggests that the surface soil particle size distribution can be changed by soil moisture. Under wet soil conditions, the particles appear to have a larger size, and hence more potential saltating particles are available. This explains the occurrence of stronger saltation processes observed under wet soil conditions.展开更多
用Guelph入渗仪对科尔沁沙地不同沙漠化阶段土壤不同层次的土壤饱和导水率(Kfs)进行测定,分析研究了Kfs与沙地类型、土层厚度、沙丘坡位及土壤理化性质的关系。结果表明:(1)草地(潜在沙漠化)、固定沙丘(轻度沙漠化)和流动沙丘(严重沙漠...用Guelph入渗仪对科尔沁沙地不同沙漠化阶段土壤不同层次的土壤饱和导水率(Kfs)进行测定,分析研究了Kfs与沙地类型、土层厚度、沙丘坡位及土壤理化性质的关系。结果表明:(1)草地(潜在沙漠化)、固定沙丘(轻度沙漠化)和流动沙丘(严重沙漠化)的Kfs依次增大,平均值分别为2.15、4.79和5.89 mm min-1,呈现出土壤入渗能力随沙漠化程度的增强而增强的趋势;三种沙地间Kfs差异显著,沙丘不同坡位Kfs也有较大差异,表明科尔沁沙地Kfs具有较高的空间异质性;(2)三种沙地Kfs随深度的变化规律差异较大,草地Kfs随深度呈抛物线状变化,而固定沙丘Kfs随深度呈指数函数变化;(3)通过逐步回归分析发现对Kfs影响较大的土壤理化性质是土壤有机质含量、土壤细砂含量、黏粉粒含量和粗砂粒含量,并且Kfs与前三个因素呈显著的负相关关系,与最后一个因素呈显著的正相关关系。展开更多
文摘Horqin Sand Land is regarded as the t ypical region for studying the probl em of desertification.The integra-tion of 3S(GIS,GPS and RS)techniques offer a most helpful meth od to study and monitor the dynamics o f desertification.Based on the data derived from3perio ds’ multitemporal Landsat TMimagery of the 1990s,the regional land use a nd dynam-ics of desertification in Horqin San d Land were studied.The main results revealed that:1)as long as the general change tendency was concerned,the deserti fication of Horqin Sand Land would co ntinue to spread;2)there was a gradual de-crease in the area of both moving sand dunes and semi-stabilized ones,whi ch meant that fruitful progress had b een made to control the desertification during the 1990s;3)as a result of unreasonable cultivation,the total area of stabilized san d dunes and grassland in the middle and western region decreased obviously.It suggested that the increasing damage caused by human was leading to the hazard of further desertification.So i n the future,it is necessary to take more effec-tive measures to control the spread o f desertification and restore the degraded ecosystems for the purpose of optimizing the global eco-environment in Horqin Sand Land.
基金Under the auspices of Natural National Science Foundation of China(No.41671002,41401002)
文摘The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing images, this study utilizes geomorphology and landscape ecology to monitor and analyze the aeolian geomorphology characteristics of the Horqin Sandy Land. Results show that the sand dunes of the Horqin Sandy Land are mainly distributed on alluvial plains along the banks of the mainstream and tributaries of the Western Liao River, and the sand dune types tend to simplify from west to east and from south to north. The aeolian geomorphology coverage tend to be decreasing in the past 40 years, with an average annual change rate of 0.31%. While the area of traveling dunes decreased, the area of fixed and semi-fixed dunes increased. The fractal dimensions of various types of sand dune have all remained relatively constant between 1.07 and 1.10, suggesting that they are experiencing a relatively stable evolutionary process. There is a complex interaction between fluvial and aeolian processes of the Horqin Sandy Land, which plays a central role in surface landscape molding. Sand dunes on both sides of different rivers on the Horqin Sandy Land present certain regularity and different characteristics in terms of morphology, developmental scale, and spatial pattern. There are six fluvial-aeolian interaction modes in this area: supply of sand sources by rivers for sand dune development, complete obstruction of dune migration by rivers, partial obstruction of dune migration by rivers, influence of river valleys on dune developmental types on both sides, influence of river valleys on dune developmental scale on both sides, and river diversion due to obstruction and forcing by sand dunes. This study deepens our understanding of the surface process mechanism of the interaction between fluvial and aeolian processes in semi-arid regions, and provides a basis for researches on regional landscape responses in the context of global environmental change.
基金funded by Foundation for Excellent Youth Scholars of CAREERI,CAS (Y451081001)National Natural Science Foundation of China (41401620,41201249)The Chinese Academy of Sciences has kindly granted Prof.O. Andrén a 'Professorship for Senior International Scientists' (Grant No.Y229D91001)
文摘Growth and physiological responses of wheat to sand burial were studied in Horqin Sandy Land, to determine the impact on productivity and survival as well as antioxidant enzymes responses. This study consisted of one control （no sand） and four sand burial treatments： 25%, 50%, 75% and 100% of seedling height, respectively. Minor burial （25%） had no effect on wheat growth and survival; deep burial （100%） was fatal, and the others had an intermediate effect. Thus, the survival limit to sand burial was equal to seedling height. Sand burial mainly decreased shoot biomass and crop yield, but had small effects on belowground biomass. Superoxide dismutase （SOD） activity increased with time after burial in all treatments with surviving plants. Peroxidase （POD） activity increased after six days under burial, and catalase （CAT） activity de- creased after burial, but recovered after 12 days. The concentration of malondialdehyde （MDA）, a marker for oxidative stress, was low on the sixth day, but increased thereafter with burial depth. Thus, sand burial 〉25% should be avoided due to growth rate reduction leading to reduced crop yield, and even 25% burial showed physiological indicators of stress.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2010CB428501)China Meteorological Administration Special Public Welfare Research Fund(GYHY201006014)+1 种基金National Natural Science Foundation of China(41075005)Research Fund for Doctoral Program of Higher Education of China(20110001130010)
文摘In this study, the eff ects of soil moisture on sand saltation and dust emission over the Horqin Sandy Land area are investigated, based on observations of three dust events in 2010. The minimum friction velocity initiating the motion of surface particles, namely, the threshold friction velocity, is estimated to be 0.34, 0.40, and 0.50 m s？1 under the very dry, dry, and wet soil conditions, respectively. In comparison with the observations during the dust events under the very dry and dry soil conditions, the dust emission fl ux during the wet event is smaller, but the saltation activities of sand particles （d≧50 μm） are stronger. The size distributions of airborne dust particles （0.1≦d≦20 μm） show that concentrations of the fi ner dust particles （0.1≦d≦0.3 μm） have a secondary peak under dry soil conditions, while they are absent under wet soil conditions. This suggests that the surface soil particle size distribution can be changed by soil moisture. Under wet soil conditions, the particles appear to have a larger size, and hence more potential saltating particles are available. This explains the occurrence of stronger saltation processes observed under wet soil conditions.
文摘用Guelph入渗仪对科尔沁沙地不同沙漠化阶段土壤不同层次的土壤饱和导水率(Kfs)进行测定,分析研究了Kfs与沙地类型、土层厚度、沙丘坡位及土壤理化性质的关系。结果表明:(1)草地(潜在沙漠化)、固定沙丘(轻度沙漠化)和流动沙丘(严重沙漠化)的Kfs依次增大,平均值分别为2.15、4.79和5.89 mm min-1,呈现出土壤入渗能力随沙漠化程度的增强而增强的趋势;三种沙地间Kfs差异显著,沙丘不同坡位Kfs也有较大差异,表明科尔沁沙地Kfs具有较高的空间异质性;(2)三种沙地Kfs随深度的变化规律差异较大,草地Kfs随深度呈抛物线状变化,而固定沙丘Kfs随深度呈指数函数变化;(3)通过逐步回归分析发现对Kfs影响较大的土壤理化性质是土壤有机质含量、土壤细砂含量、黏粉粒含量和粗砂粒含量,并且Kfs与前三个因素呈显著的负相关关系,与最后一个因素呈显著的正相关关系。
