Drylands of the world cover 41%of the Earth＇s land surface and are a direct source of livelihood for 6.5 billion people, especially in developing countries. However, nearly all drylands are at risk of land degradatio...Drylands of the world cover 41%of the Earth＇s land surface and are a direct source of livelihood for 6.5 billion people, especially in developing countries. However, nearly all drylands are at risk of land degradation as a result of human activities. Poverty and desertification in dryland areas are major problems threatening sustainable agriculture and rural development in dryland areas. Several topics that are significant for sustainable agriculture and rural development for food security and environmental rehabilitation in dryland areas were stressed in this paper.展开更多
保护自然植被和营造人工植被是黄土高原植被恢复的重要措施,为定量阐明该区域典型植被类型的生态服务功能,合理评估不同恢复植被措施的生态效益,选取了两种典型森林生态系统(刺槐人工林和辽东栎天然次生林),基于多年连续调查数据分析了...保护自然植被和营造人工植被是黄土高原植被恢复的重要措施,为定量阐明该区域典型植被类型的生态服务功能,合理评估不同恢复植被措施的生态效益,选取了两种典型森林生态系统(刺槐人工林和辽东栎天然次生林),基于多年连续调查数据分析了其碳汇功能特征。采用以胸径和树高为基础变量的生物量方程估算了乔木层生物量;采用样方收获法测算了灌木、草本和凋落物现存量;依据两次样地调查的数据(间隔9年)和连续多年凋落物收集的数据,估算了两种森林生态系统的净初级生产力和固碳速率;再结合对两种林地土壤CO2排放的监测与分析结果进一步估算了两种生态系统的碳汇功能。结果表明:刺槐林的生物量碳密度(67.63 t C/hm2)略低于辽东栎林(76.85 t C/hm2),林分内各组分碳密度仅在乔木叶部分差异显著。研究期间刺槐林和辽东栎林的生物量年均增长量分别为15.20,18.21 t/(hm2·a);植被层年均固碳量分别为7.57,8.91 t C/(hm2·a)。因刺槐林地的土壤异养呼吸速率低于辽东栎林地,故其碳汇功能相对较高。展开更多
The objectives of the current study were to estimate evapotranspiration（ET） over the grassland and assess seasonal variation of moisture availability at the wind-water erosion crisscross region in the northern Loess...The objectives of the current study were to estimate evapotranspiration（ET） over the grassland and assess seasonal variation of moisture availability at the wind-water erosion crisscross region in the northern Loess Plateau of China. The Liudaogou Catchment which has the representative climatic and hydrological characteristics of the wind-water erosion crisscross region was chosen as the study location. The reference crop evapotranspiration（ET 0） was estimated by Penmen method, which was recommended by FAO56 and the evapotranspiration over the grassland（ET） was estimated by Penmen-Monteith equation using the observed meteorological data with time unit of 1 h. The soil moisture availability factor was defined by m a =ET/ET 0. The calculated results for 2006 indicated that the total ET 0 was slightly more than the total yearly precipitation and ET accounted for 37 % of that, ET increased distinctly after the intensive rainfall event in the rainy season. Most of the m a was less than 0.4 and its annual mean was 0.34. It was expected that the results provided a basis for studies on dynamic functional analysis of soil moisture, relationship between soil water and crop growth at the wind-water erosion crisscross region in the northern Loess Plateau.展开更多
The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four ...The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four carboxymethylcelluloses （CMC） mixed at various rates with the sandy soil, on the water-holding capacity and hydraulic conductivity （Ks） when leached with distilled water （simulating rain）, tap water, and saline water were evaluated. The maximum water absorption of CMCs ranged between 80 and 100 kg. kg^-1 of polymer; however, the absorbent swelling capacity decreased significantly with increasing the salt concentration in the solution. The water absorption capacity of CMCs decreased significantly when incorporated in the sandy soil compared to that of the absorbent alone. Application of CMC increased significantly the available water content up to 3 ± 0.5 times. All soils treated with CMCs showed a significant lower in Ks compared to the control soil. Meanwhile, Ks was found increased with increasing the salt concentration in the leaching solution. This understanding of characteristics of the absorbents and the interactions among absorbents, soil, and irrigation water quality would be of help in water management of sandy soil展开更多
The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calcula...The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calculation of surface runoff was applied to results of the field survey, and components of monthly water budget were estimated. The unit area of 1 km2 was selected as the index area for the estimation. A component of habitant water consumption was added to the water budget to consider the contribution of human activity. Results indicated that the water storage was negative in May, June and July while the annual amount was approximately 0.0. Evaportanspiration attained maximum in August and its annual total accounted for 74.2% of annual precipitation. Results of this study are significant for the sustainable water conservation and utilization in the northern of Loess Plateau where annual water resources are relatively deficient.展开更多
基金Supported by Global COE Program (Global Center of Excellence for Dryland Science) Funded by MEXTCore-University Program Funded byJSPS
文摘Drylands of the world cover 41%of the Earth＇s land surface and are a direct source of livelihood for 6.5 billion people, especially in developing countries. However, nearly all drylands are at risk of land degradation as a result of human activities. Poverty and desertification in dryland areas are major problems threatening sustainable agriculture and rural development in dryland areas. Several topics that are significant for sustainable agriculture and rural development for food security and environmental rehabilitation in dryland areas were stressed in this paper.
文摘保护自然植被和营造人工植被是黄土高原植被恢复的重要措施,为定量阐明该区域典型植被类型的生态服务功能,合理评估不同恢复植被措施的生态效益,选取了两种典型森林生态系统(刺槐人工林和辽东栎天然次生林),基于多年连续调查数据分析了其碳汇功能特征。采用以胸径和树高为基础变量的生物量方程估算了乔木层生物量;采用样方收获法测算了灌木、草本和凋落物现存量;依据两次样地调查的数据(间隔9年)和连续多年凋落物收集的数据,估算了两种森林生态系统的净初级生产力和固碳速率;再结合对两种林地土壤CO2排放的监测与分析结果进一步估算了两种生态系统的碳汇功能。结果表明:刺槐林的生物量碳密度(67.63 t C/hm2)略低于辽东栎林(76.85 t C/hm2),林分内各组分碳密度仅在乔木叶部分差异显著。研究期间刺槐林和辽东栎林的生物量年均增长量分别为15.20,18.21 t/(hm2·a);植被层年均固碳量分别为7.57,8.91 t C/(hm2·a)。因刺槐林地的土壤异养呼吸速率低于辽东栎林地,故其碳汇功能相对较高。
基金Supported by the National Natural Science Foundation of China(NSFC)(41271046)Postdoctoral Science Foundation of China(Oversea scholar,87328)+1 种基金Heilongjiang Provincial Department of Education Scientific Research Foundation for overseas scholars,China(1251H017)Scientific Research Foundation of Northeast Agricultural University of China(115-180152)
文摘The objectives of the current study were to estimate evapotranspiration（ET） over the grassland and assess seasonal variation of moisture availability at the wind-water erosion crisscross region in the northern Loess Plateau of China. The Liudaogou Catchment which has the representative climatic and hydrological characteristics of the wind-water erosion crisscross region was chosen as the study location. The reference crop evapotranspiration（ET 0） was estimated by Penmen method, which was recommended by FAO56 and the evapotranspiration over the grassland（ET） was estimated by Penmen-Monteith equation using the observed meteorological data with time unit of 1 h. The soil moisture availability factor was defined by m a =ET/ET 0. The calculated results for 2006 indicated that the total ET 0 was slightly more than the total yearly precipitation and ET accounted for 37 % of that, ET increased distinctly after the intensive rainfall event in the rainy season. Most of the m a was less than 0.4 and its annual mean was 0.34. It was expected that the results provided a basis for studies on dynamic functional analysis of soil moisture, relationship between soil water and crop growth at the wind-water erosion crisscross region in the northern Loess Plateau.
文摘The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four carboxymethylcelluloses （CMC） mixed at various rates with the sandy soil, on the water-holding capacity and hydraulic conductivity （Ks） when leached with distilled water （simulating rain）, tap water, and saline water were evaluated. The maximum water absorption of CMCs ranged between 80 and 100 kg. kg^-1 of polymer; however, the absorbent swelling capacity decreased significantly with increasing the salt concentration in the solution. The water absorption capacity of CMCs decreased significantly when incorporated in the sandy soil compared to that of the absorbent alone. Application of CMC increased significantly the available water content up to 3 ± 0.5 times. All soils treated with CMCs showed a significant lower in Ks compared to the control soil. Meanwhile, Ks was found increased with increasing the salt concentration in the leaching solution. This understanding of characteristics of the absorbents and the interactions among absorbents, soil, and irrigation water quality would be of help in water management of sandy soil
基金Supported by JSPS Core University Program, Japan CAS "Western Light" (2006YB04)
文摘The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calculation of surface runoff was applied to results of the field survey, and components of monthly water budget were estimated. The unit area of 1 km2 was selected as the index area for the estimation. A component of habitant water consumption was added to the water budget to consider the contribution of human activity. Results indicated that the water storage was negative in May, June and July while the annual amount was approximately 0.0. Evaportanspiration attained maximum in August and its annual total accounted for 74.2% of annual precipitation. Results of this study are significant for the sustainable water conservation and utilization in the northern of Loess Plateau where annual water resources are relatively deficient.
