By using the statistical data of grain yield in China's major grain producing areas from 1949 to 2008,and fluctuation theory,the historical process and main cause of fluctuation of grain yield in China's major...By using the statistical data of grain yield in China's major grain producing areas from 1949 to 2008,and fluctuation theory,the historical process and main cause of fluctuation of grain yield in China's major grain producing areas are analyzed.The results of research show that the grain yield in China's major grain producing areas grows in unstable fluctuation,with high-frequency fluctuation cycle and regular length;the amplitude of fluctuation,on the whole,is moderate,with not strong stability;the fluctuation of grain yield has correspondence,reflecting the N-shape developmental trend of grain production at present;the fluctuation of grain yield has gradient characteristics;in the process of comparison of grain yield,the average growth rate annually of grain yield in China's major grain producing areas is higher than that of the national average,but the relative fluctuation coefficient is also higher than that of the national average.From five aspects,namely natural disaster,agricultural policy,production input,grain price and grain circulation,the cause of fluctuation of grain yield in China's major grain producing areas is analyzed,and measures of preventing and arresting super-long fluctuation of grain yield are put forward.Firstly,stick to strict farmland protection system,and strive to promote farmland quality;secondly,strengthen infrastructure construction of grain production and beef up the ability of preventing natural disaster;thirdly,quicken the pace of agricultural technology and establish robust technology supporting system;fourthly,lay stress on innovation of agricultural organization system and provide implementation path and vehicle for application of agricultural technology measures;fifthly,perfect disaster precaution system and grain market system,and strengthen the ability of preventing risk of grain production.展开更多
The fluctuation in Ommastrephe bartrami yield from 1995 to 2001 in the North Pacific was shown obvious, on which this study was conducted using data of sea surface temperature （SST）, chlorophyll-a （chl-α） and sta...The fluctuation in Ommastrephe bartrami yield from 1995 to 2001 in the North Pacific was shown obvious, on which this study was conducted using data of sea surface temperature （SST）, chlorophyll-a （chl-α） and statistical production. The study shows that, cool water and low food abundance caused by abnormal Kuroshio resulted in the reduction in abundance of O. bartrami, which was worsened by excessive catch and the unawareness to local fishery resources protection.展开更多
Using meteorological data and mathematical statistics analysis,we take Jungar Banner in the northern farming-pastoral region of China for example,to analyze the fluctuations in the precipitation and average temperatur...Using meteorological data and mathematical statistics analysis,we take Jungar Banner in the northern farming-pastoral region of China for example,to analyze the fluctuations in the precipitation and average temperature in Jungar Banner during the period 1961-2009.We calculate the NPP of agricultural ecosystem and climatic yield of the main crops in the region during the period 1961-2009,and expound the response of agricultural ecosystem productivity to climate fluctuations in Jungar Banner.Indubitably the climate changes impose great effects on the structure and function of regional ecosystem,and there is a need to take a number of measures to minimize the detrimental effects of climate changes on climatic yield of the main crops.展开更多
This study aims to characterize water table fluctuations and estimate groundwater recharge in the Tougou catchment located in the Sahel zone of Burkina Faso.Water table fluctuation and groundwater budget approaches ar...This study aims to characterize water table fluctuations and estimate groundwater recharge in the Tougou catchment located in the Sahel zone of Burkina Faso.Water table fluctuation and groundwater budget approaches are developed on an experimental site equipped with observation wells.The trends of water fluctuations in the different layers of the weathering profile are similar.There is a time-lag response of groundwater recharge to the daily precipitation occurrences.The interaction between the upper(clayey alteration)and lower(transition zone-fractured schist complex)parts of the weathering profile shows that generally the hydraulic head in the upper part is higher than that of the lower part due to difference in drainage porosity.The latter varies at the catchment scale between 0.006 and 0.009 and is inversely proportional to the saturated thickness of the clayey alteration layer.The groundwater recharge is annually estimated between 36 and 49 mm,which correspond to 6%and 9%of mean annual rainfall in the catchment.Annual evapotranspiration was estimated to be about 223 to 443 mm.展开更多
基金Supported by Youth Initiation Fund Program of Jilin Agricultural University
文摘By using the statistical data of grain yield in China's major grain producing areas from 1949 to 2008,and fluctuation theory,the historical process and main cause of fluctuation of grain yield in China's major grain producing areas are analyzed.The results of research show that the grain yield in China's major grain producing areas grows in unstable fluctuation,with high-frequency fluctuation cycle and regular length;the amplitude of fluctuation,on the whole,is moderate,with not strong stability;the fluctuation of grain yield has correspondence,reflecting the N-shape developmental trend of grain production at present;the fluctuation of grain yield has gradient characteristics;in the process of comparison of grain yield,the average growth rate annually of grain yield in China's major grain producing areas is higher than that of the national average,but the relative fluctuation coefficient is also higher than that of the national average.From five aspects,namely natural disaster,agricultural policy,production input,grain price and grain circulation,the cause of fluctuation of grain yield in China's major grain producing areas is analyzed,and measures of preventing and arresting super-long fluctuation of grain yield are put forward.Firstly,stick to strict farmland protection system,and strive to promote farmland quality;secondly,strengthen infrastructure construction of grain production and beef up the ability of preventing natural disaster;thirdly,quicken the pace of agricultural technology and establish robust technology supporting system;fourthly,lay stress on innovation of agricultural organization system and provide implementation path and vehicle for application of agricultural technology measures;fifthly,perfect disaster precaution system and grain market system,and strengthen the ability of preventing risk of grain production.
基金Supported by National Key Project for Basic Research of China (2005CB422300)
文摘The fluctuation in Ommastrephe bartrami yield from 1995 to 2001 in the North Pacific was shown obvious, on which this study was conducted using data of sea surface temperature （SST）, chlorophyll-a （chl-α） and statistical production. The study shows that, cool water and low food abundance caused by abnormal Kuroshio resulted in the reduction in abundance of O. bartrami, which was worsened by excessive catch and the unawareness to local fishery resources protection.
基金the Doctoral Program of Higher Education(20120003110017)the Natural Science Foundation of Gansu Province(1308RJZA285)the Academic Upgrading Scheme for Young Teachers of Northwest Normal Univer-sity(NWNU-LKON-12-33)
文摘Using meteorological data and mathematical statistics analysis,we take Jungar Banner in the northern farming-pastoral region of China for example,to analyze the fluctuations in the precipitation and average temperature in Jungar Banner during the period 1961-2009.We calculate the NPP of agricultural ecosystem and climatic yield of the main crops in the region during the period 1961-2009,and expound the response of agricultural ecosystem productivity to climate fluctuations in Jungar Banner.Indubitably the climate changes impose great effects on the structure and function of regional ecosystem,and there is a need to take a number of measures to minimize the detrimental effects of climate changes on climatic yield of the main crops.
文摘This study aims to characterize water table fluctuations and estimate groundwater recharge in the Tougou catchment located in the Sahel zone of Burkina Faso.Water table fluctuation and groundwater budget approaches are developed on an experimental site equipped with observation wells.The trends of water fluctuations in the different layers of the weathering profile are similar.There is a time-lag response of groundwater recharge to the daily precipitation occurrences.The interaction between the upper(clayey alteration)and lower(transition zone-fractured schist complex)parts of the weathering profile shows that generally the hydraulic head in the upper part is higher than that of the lower part due to difference in drainage porosity.The latter varies at the catchment scale between 0.006 and 0.009 and is inversely proportional to the saturated thickness of the clayey alteration layer.The groundwater recharge is annually estimated between 36 and 49 mm,which correspond to 6%and 9%of mean annual rainfall in the catchment.Annual evapotranspiration was estimated to be about 223 to 443 mm.
