This paper reports a geomorphologic landscape investigation, vegetationsurvey and soil sampling at 14 sites across the Gurbantunggut Desert between87°37′09″-88°24′04″E and 44°14′04″-45°41′52...This paper reports a geomorphologic landscape investigation, vegetationsurvey and soil sampling at 14 sites across the Gurbantunggut Desert between87°37′09″-88°24′04″E and 44°14′04″-45°41′52″N. The study encountered 8 species of lowtrees and shrubs, 5 of perennial herbs, 8 of annual plants and 48 of ephemeral and ephemeroidplants. These species of plants represent one-third of the species found in the GurbantunggutDesert, and their communities make up a large proportion of desert vegetation with great landscapesignificance. In the investigation we found that the plant communities are accordingly succeededwith the spatial variation of macro-ecoenvironment. Using Principal Component Analysis (PCA) andCorrelation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandysoil's physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc.only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation.Meanwhile, the impact of microhabitat on the plant community pattern with an antagonisticinteraction made vegetation's eco-distribution in a temporary equilibrium.展开更多
Groundwater is the primary water source in the Kingdom of Saudi Arabia. As result of lack of basic knowledge on irrigation practices, massive abstractions of groundwater occurred in 1980＇s. A Decision Support Linear ...Groundwater is the primary water source in the Kingdom of Saudi Arabia. As result of lack of basic knowledge on irrigation practices, massive abstractions of groundwater occurred in 1980＇s. A Decision Support Linear Goal Programming （LGP） model was developed to determine optimal groundwater irrigation levels, to assess the implications for water management policies, and to estimate welfare impact on producer surplus. Due to the reductions of groundwater in 1980＇s, the Al-Wajid aquifer water levels have dropped in agricultural areas by more than 200 m. Results from this study estimate that the total groundwater of the Al-Wajid aquifer that can be saved is equal to 66 MCM for the first scenario, 147 MCM for the second scenario, and 229 MCM for the third scenario. Regarding the welfare analysis impacts, it is clear that the total gross margin is decreasing up to 7.7% at the end of the year of scenario Ⅲ. Therefore, the third scenario with a water saving increase to 18.1% is recommended as a directive for agricultural policy formation in the future.展开更多
Objective: To determine whether attenuated Salmonella typhimurium producing Helicobacter pylori (Hp) urease subunit B(UreB)can elicit specific immune responses against Hp in mice tested by a lavage technique. Methods:...Objective: To determine whether attenuated Salmonella typhimurium producing Helicobacter pylori (Hp) urease subunit B(UreB)can elicit specific immune responses against Hp in mice tested by a lavage technique. Methods: Attenuated Salmonella typhimurium producing Hp UreB immunized orally Balb/c mice twice at a 3-week interval. After 12 weeks,mice intestinal secretions were obtained without harm by administering a lavage solution intragastrically. The mice intestinal secretions of immune group were also directly washed out after the mice were killed. The antibody responses were evaluated by using serum and intestinal fluid with ELISA assay. Results: The multiple oral immunizations with SL3261/ pTC01-UreB induced significantly Hp-specific mucosal IgA response as well as serum IgG response. The IgA was also consistently higher in the intestinal fluid obtained by the lavage solution than by direct washout. In addition, no obvious side effects and changes in gastric inflammation were observed in mice. Conclusion: The attenuated Salmonella typhimurium expressing Hp UreB may be used as an oral vaccine against Hp infection. And the lavage technique is an ideal method in the study of mucosal immune responses.展开更多
Plastic cover as a method to minimize soil water evaporation and improve water use efficiency, was used for corn during the whole growing period in a desert area. Field studies were conducted to determine the effect o...Plastic cover as a method to minimize soil water evaporation and improve water use efficiency, was used for corn during the whole growing period in a desert area. Field studies were conducted to determine the effect of plastic covering management on corn growth and rooting pattern and its relationship with changes in climate. Four treatments, 0) bared soil without cover) 1) covering one side of the crop, 2) covering both sides of the crop, and 3) covering the surface totally, were established on a sandy loam soil. Results showed that treatment 0 was significantly different from others and revealed that plastic covering was not always good to corn growth. Improper usage of plastic cover might weaken root development and thereafter lower the total yield of the crop. Suitable practices combining different methods discussed could not only improve water use efficiency but also increase the crop yield.展开更多
The saline wetlands,or'saladas',of Monegros Desert,NE Spain,contain biodiversity that depends on the estab- lishment of a prognostic monitoring system that can warn of approaching irreversible damage.In the co...The saline wetlands,or'saladas',of Monegros Desert,NE Spain,contain biodiversity that depends on the estab- lishment of a prognostic monitoring system that can warn of approaching irreversible damage.In the context of a lack of existing biodiversity inventories for the saladas,we determined their state of conservation and vulnerability using seven physical indicators:escarpment continuity,cropping,stone dumping,size,water occurrence,distance to roads,and proximity to irrigated areas.These features were combined into three meaningful indexes,i.e.,conservation,current vulnerability,and future vulnerability,thus creating an assessment of the preservation or degradation of saladas in the context of encroaching agricultural irrigation projects.The proposed indexes produced consistent results and showed that a great number of the Monegros wetlands were threatened,regardless of their size or frequency of water occurrence.Only 20% of the saladas studied were classified as being in a good or very good conservation,whereas 50% were in bad or very bad shape.A high current vulnerability was found for 60% of the saladas.For saladas located in land to be irrigated, we predicted that 73% would have a high or very high future vulnerability.Currently,58% of the saladas were in bad or very bad condition and fully 65% of the saladas,variable in size,presented a bad or very bad prognosis.Our approach provides a monitoring strategy for the conservation of saline wetlands threatened by agricultural intensification,especially irrigation.展开更多
There are some bad impacts from a critical land such as flood in rainy season and dryness in dry season. Long dryness could cause shortage of water for human consumption, industry and agriculture. Prevention has been ...There are some bad impacts from a critical land such as flood in rainy season and dryness in dry season. Long dryness could cause shortage of water for human consumption, industry and agriculture. Prevention has been made to avoid the both bad impacts by building hydraulic structures like reservoirs and ponds in order to reduce the peak flow during the rainy season and to store the water for use during the dry season. However, they gradually become full of sediment. This will make them work insufficiently and will cause high maintenance cost. Moreover, wells in agriculture field used as retention also suffer dryness to make crop failure. This study aims to develop a model of pond for conservation of land and water in non irrigated land. Community participation is crucial in order to solve the flood and dryness problems. The community, especially the farmers will participate actively in the implementation and maintenance of the model. There are benefits in using the pond model such as： （1） to control sediment transport to the rivers, reservoir or other hydraulic structures; （2） to reduce flood rate; （3） to increase ground water recharge; （4） to contain water for agriculture and （5） to control the fertility of land. The cost of making a unit of model （sedrainpond） of 1.5 m diameter and 1.5 meter depth is relatively cheap between $10 to $20 （US）, and the maintenance is done by the farmers. When the pond model becomes functional, besides containing water in the rainy season, the water can be used to sustain water for agriculture in the dry season to avoid any crop failure. When the pond becomes dry, the farmers can harvest the suspended load sediment such as clay or silt to spread onto their land to keep its fertility.展开更多
Wood anatomy of Calligonum mongolicum Turcz. was described from an ecological perspective. This species showed similar wood structure to that species published in the same genus. This species has distinct growth ring ...Wood anatomy of Calligonum mongolicum Turcz. was described from an ecological perspective. This species showed similar wood structure to that species published in the same genus. This species has distinct growth ring boundaries, ring-porosity, distinct helical thickenings, simple perforation plate, nonseptate fibre, axial parenchyma, uni- or 2-5-seriate heterogeneous rays, and alternate intervessel pitting. It was observed that there is a slightly increase of fibre length as the diameter from the pith increases. However, the vessel element length remains more or less constant from pith to bark. Furthermore, the relationships between anatomical features and adaptability to desert environments were discussed.展开更多
基金Xinjiang Uygur Autonomous Region′s Natural Science Foundation Project，The special support project from the Director′s fund of the Xinjiang Institute of Ecology and Geology，国家自然科学基金
文摘This paper reports a geomorphologic landscape investigation, vegetationsurvey and soil sampling at 14 sites across the Gurbantunggut Desert between87°37′09″-88°24′04″E and 44°14′04″-45°41′52″N. The study encountered 8 species of lowtrees and shrubs, 5 of perennial herbs, 8 of annual plants and 48 of ephemeral and ephemeroidplants. These species of plants represent one-third of the species found in the GurbantunggutDesert, and their communities make up a large proportion of desert vegetation with great landscapesignificance. In the investigation we found that the plant communities are accordingly succeededwith the spatial variation of macro-ecoenvironment. Using Principal Component Analysis (PCA) andCorrelation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandysoil's physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc.only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation.Meanwhile, the impact of microhabitat on the plant community pattern with an antagonisticinteraction made vegetation's eco-distribution in a temporary equilibrium.
文摘Groundwater is the primary water source in the Kingdom of Saudi Arabia. As result of lack of basic knowledge on irrigation practices, massive abstractions of groundwater occurred in 1980＇s. A Decision Support Linear Goal Programming （LGP） model was developed to determine optimal groundwater irrigation levels, to assess the implications for water management policies, and to estimate welfare impact on producer surplus. Due to the reductions of groundwater in 1980＇s, the Al-Wajid aquifer water levels have dropped in agricultural areas by more than 200 m. Results from this study estimate that the total groundwater of the Al-Wajid aquifer that can be saved is equal to 66 MCM for the first scenario, 147 MCM for the second scenario, and 229 MCM for the third scenario. Regarding the welfare analysis impacts, it is clear that the total gross margin is decreasing up to 7.7% at the end of the year of scenario Ⅲ. Therefore, the third scenario with a water saving increase to 18.1% is recommended as a directive for agricultural policy formation in the future.
文摘Objective: To determine whether attenuated Salmonella typhimurium producing Helicobacter pylori (Hp) urease subunit B(UreB)can elicit specific immune responses against Hp in mice tested by a lavage technique. Methods: Attenuated Salmonella typhimurium producing Hp UreB immunized orally Balb/c mice twice at a 3-week interval. After 12 weeks,mice intestinal secretions were obtained without harm by administering a lavage solution intragastrically. The mice intestinal secretions of immune group were also directly washed out after the mice were killed. The antibody responses were evaluated by using serum and intestinal fluid with ELISA assay. Results: The multiple oral immunizations with SL3261/ pTC01-UreB induced significantly Hp-specific mucosal IgA response as well as serum IgG response. The IgA was also consistently higher in the intestinal fluid obtained by the lavage solution than by direct washout. In addition, no obvious side effects and changes in gastric inflammation were observed in mice. Conclusion: The attenuated Salmonella typhimurium expressing Hp UreB may be used as an oral vaccine against Hp infection. And the lavage technique is an ideal method in the study of mucosal immune responses.
文摘Plastic cover as a method to minimize soil water evaporation and improve water use efficiency, was used for corn during the whole growing period in a desert area. Field studies were conducted to determine the effect of plastic covering management on corn growth and rooting pattern and its relationship with changes in climate. Four treatments, 0) bared soil without cover) 1) covering one side of the crop, 2) covering both sides of the crop, and 3) covering the surface totally, were established on a sandy loam soil. Results showed that treatment 0 was significantly different from others and revealed that plastic covering was not always good to corn growth. Improper usage of plastic cover might weaken root development and thereafter lower the total yield of the crop. Suitable practices combining different methods discussed could not only improve water use efficiency but also increase the crop yield.
基金Project supported by the Ministry of Education and Science,Spain (No.AGL2006-01283)the European Regional Development Fund (No.EX2006-0347).
文摘The saline wetlands,or'saladas',of Monegros Desert,NE Spain,contain biodiversity that depends on the estab- lishment of a prognostic monitoring system that can warn of approaching irreversible damage.In the context of a lack of existing biodiversity inventories for the saladas,we determined their state of conservation and vulnerability using seven physical indicators:escarpment continuity,cropping,stone dumping,size,water occurrence,distance to roads,and proximity to irrigated areas.These features were combined into three meaningful indexes,i.e.,conservation,current vulnerability,and future vulnerability,thus creating an assessment of the preservation or degradation of saladas in the context of encroaching agricultural irrigation projects.The proposed indexes produced consistent results and showed that a great number of the Monegros wetlands were threatened,regardless of their size or frequency of water occurrence.Only 20% of the saladas studied were classified as being in a good or very good conservation,whereas 50% were in bad or very bad shape.A high current vulnerability was found for 60% of the saladas.For saladas located in land to be irrigated, we predicted that 73% would have a high or very high future vulnerability.Currently,58% of the saladas were in bad or very bad condition and fully 65% of the saladas,variable in size,presented a bad or very bad prognosis.Our approach provides a monitoring strategy for the conservation of saline wetlands threatened by agricultural intensification,especially irrigation.
文摘There are some bad impacts from a critical land such as flood in rainy season and dryness in dry season. Long dryness could cause shortage of water for human consumption, industry and agriculture. Prevention has been made to avoid the both bad impacts by building hydraulic structures like reservoirs and ponds in order to reduce the peak flow during the rainy season and to store the water for use during the dry season. However, they gradually become full of sediment. This will make them work insufficiently and will cause high maintenance cost. Moreover, wells in agriculture field used as retention also suffer dryness to make crop failure. This study aims to develop a model of pond for conservation of land and water in non irrigated land. Community participation is crucial in order to solve the flood and dryness problems. The community, especially the farmers will participate actively in the implementation and maintenance of the model. There are benefits in using the pond model such as： （1） to control sediment transport to the rivers, reservoir or other hydraulic structures; （2） to reduce flood rate; （3） to increase ground water recharge; （4） to contain water for agriculture and （5） to control the fertility of land. The cost of making a unit of model （sedrainpond） of 1.5 m diameter and 1.5 meter depth is relatively cheap between $10 to $20 （US）, and the maintenance is done by the farmers. When the pond model becomes functional, besides containing water in the rainy season, the water can be used to sustain water for agriculture in the dry season to avoid any crop failure. When the pond becomes dry, the farmers can harvest the suspended load sediment such as clay or silt to spread onto their land to keep its fertility.
文摘Wood anatomy of Calligonum mongolicum Turcz. was described from an ecological perspective. This species showed similar wood structure to that species published in the same genus. This species has distinct growth ring boundaries, ring-porosity, distinct helical thickenings, simple perforation plate, nonseptate fibre, axial parenchyma, uni- or 2-5-seriate heterogeneous rays, and alternate intervessel pitting. It was observed that there is a slightly increase of fibre length as the diameter from the pith increases. However, the vessel element length remains more or less constant from pith to bark. Furthermore, the relationships between anatomical features and adaptability to desert environments were discussed.
