In the river systems, the environmental change always undergoes a process from quantitative to qualitative change. The upper limit of the qualitative change is called threshold. When the process reaches or goes beyond...In the river systems, the environmental change always undergoes a process from quantitative to qualitative change. The upper limit of the qualitative change is called threshold. When the process reaches or goes beyond the limit, the original event series will be replaced by the other event series. Investigations show that the evolution of the Huanghe River alluvial fan and delta has also under gone a process from quantitative to qualitative change. The geometric forms in each process are roughly the same. This threshold of the geometric forms not only provides us a quantitative index for plotting the periodicity of the alluvial fan and delta, but also is of importance for estimation of the trend of natural environmental change.It is shown that there are three periodic alluvial fans of the Huanghe River since the middle Holocene and four periodic delta since 1855 A.D., the thresholds of their geometric forms are from 0.93 to 0.94 and from 1.2 to 1.21 respectively.The changing trend in the past and the展开更多
The Shandong Xiajin Yellow River Ancient Mulberry Trees System is a model of desertification control in the floor area in the Luxibei Plain,and of sustainable development.The current study about ancient mulberry trees...The Shandong Xiajin Yellow River Ancient Mulberry Trees System is a model of desertification control in the floor area in the Luxibei Plain,and of sustainable development.The current study about ancient mulberry trees in Xiajin county is mainly qualitative representation,lack of quantitative research.In addition,the relevant important ecological functional assessment should not only confine to quantitative assessment which illustrate the current condition,but also analyze the eco-service changes,derived from ecosystem structure develop,from the time dimension.Based on quantitative eco-service assessment of the ancient mulberry tree group,this paper intend to conduct a comprehensive analysis of ecological functions of ancient mulberry group focuses on the perspective of system structure and function evolution.Quantitative evaluation results show that the system has significant eco-efficiency in water conservation,reducing sediment loss,adjust atmosphere,etc.On timescale,thanks to mulberry cultivation,ecosystem structure and services have also undergone a corresponding change.In ecosystem structure：Planting pioneer trees such as mulberries and other species which can tolerate hostile site conditions,improves the micro-environment.This makes it possible for other crops to grow.The mixed forests and the combination of forestry and agriculture protect biodiversity.What＇s more,they make the structure of the ecosystems more robust,giving full play to their functions.In terms of ecosystem services：ecosystem services of Xiajin Yellow River Ancient Mulberry Trees have shown diversified development.And its main function has transferred from supply products to leisure and entertainment functions.展开更多
土壤养分是土壤肥力的基础,掌握其含量与分布特征可为改善立地条件、建设高效农田防护林体系提供科学依据。以盐城市阜宁县和淮安市涟水县黄河故道土壤为研究对象,采用层次分析法(AHP)与物元分析模型相结合的方式,分别对研究区内有林地...土壤养分是土壤肥力的基础,掌握其含量与分布特征可为改善立地条件、建设高效农田防护林体系提供科学依据。以盐城市阜宁县和淮安市涟水县黄河故道土壤为研究对象,采用层次分析法(AHP)与物元分析模型相结合的方式,分别对研究区内有林地和无林地土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾7个指标的变化特征进行了分析评价。结果表明:①随着远离河堤,土壤有机质、全氮、碱解氮、全钾、速效钾含量呈增加趋势;全磷含量呈减少趋势;有效磷在有林地呈减少趋势,在无林地呈增加趋势。②有林地土壤有机质(2~3级)、全氮(1~2级)含量显著高于无林地,而其余指标与无林地基本一致。③在距黄河故道<0.5、0.5~1.0和1.0~1.5 km 3个区域内,有林地土壤养分等级分别为较丰富Ⅱ、丰富Ⅰ、丰富Ⅰ,无林地土壤养分等级分别为贫乏Ⅳ、适量Ⅲ、适量Ⅲ。可见,开展农田防护林建设能有效促进土壤有机质、氮素的积累,提升土壤养分等级,若在此基础上合理追施磷肥,能进一步提高土壤肥力及其生态、经济效益。展开更多
文摘In the river systems, the environmental change always undergoes a process from quantitative to qualitative change. The upper limit of the qualitative change is called threshold. When the process reaches or goes beyond the limit, the original event series will be replaced by the other event series. Investigations show that the evolution of the Huanghe River alluvial fan and delta has also under gone a process from quantitative to qualitative change. The geometric forms in each process are roughly the same. This threshold of the geometric forms not only provides us a quantitative index for plotting the periodicity of the alluvial fan and delta, but also is of importance for estimation of the trend of natural environmental change.It is shown that there are three periodic alluvial fans of the Huanghe River since the middle Holocene and four periodic delta since 1855 A.D., the thresholds of their geometric forms are from 0.93 to 0.94 and from 1.2 to 1.21 respectively.The changing trend in the past and the
基金The International Exchange and Cooperation Project of Ministry of Agriculture“Conservation of Globally Important Agricultural Heritage Systems(GIAHS)in China in 2016”The Youth Talent Supporting Project of China Association for Science and Technology(2016010103)
文摘The Shandong Xiajin Yellow River Ancient Mulberry Trees System is a model of desertification control in the floor area in the Luxibei Plain,and of sustainable development.The current study about ancient mulberry trees in Xiajin county is mainly qualitative representation,lack of quantitative research.In addition,the relevant important ecological functional assessment should not only confine to quantitative assessment which illustrate the current condition,but also analyze the eco-service changes,derived from ecosystem structure develop,from the time dimension.Based on quantitative eco-service assessment of the ancient mulberry tree group,this paper intend to conduct a comprehensive analysis of ecological functions of ancient mulberry group focuses on the perspective of system structure and function evolution.Quantitative evaluation results show that the system has significant eco-efficiency in water conservation,reducing sediment loss,adjust atmosphere,etc.On timescale,thanks to mulberry cultivation,ecosystem structure and services have also undergone a corresponding change.In ecosystem structure：Planting pioneer trees such as mulberries and other species which can tolerate hostile site conditions,improves the micro-environment.This makes it possible for other crops to grow.The mixed forests and the combination of forestry and agriculture protect biodiversity.What＇s more,they make the structure of the ecosystems more robust,giving full play to their functions.In terms of ecosystem services：ecosystem services of Xiajin Yellow River Ancient Mulberry Trees have shown diversified development.And its main function has transferred from supply products to leisure and entertainment functions.
文摘土壤养分是土壤肥力的基础,掌握其含量与分布特征可为改善立地条件、建设高效农田防护林体系提供科学依据。以盐城市阜宁县和淮安市涟水县黄河故道土壤为研究对象,采用层次分析法(AHP)与物元分析模型相结合的方式,分别对研究区内有林地和无林地土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾7个指标的变化特征进行了分析评价。结果表明:①随着远离河堤,土壤有机质、全氮、碱解氮、全钾、速效钾含量呈增加趋势;全磷含量呈减少趋势;有效磷在有林地呈减少趋势,在无林地呈增加趋势。②有林地土壤有机质(2~3级)、全氮(1~2级)含量显著高于无林地,而其余指标与无林地基本一致。③在距黄河故道<0.5、0.5~1.0和1.0~1.5 km 3个区域内,有林地土壤养分等级分别为较丰富Ⅱ、丰富Ⅰ、丰富Ⅰ,无林地土壤养分等级分别为贫乏Ⅳ、适量Ⅲ、适量Ⅲ。可见,开展农田防护林建设能有效促进土壤有机质、氮素的积累,提升土壤养分等级,若在此基础上合理追施磷肥,能进一步提高土壤肥力及其生态、经济效益。
