基于EMD的河北省粮食产量波动及其成因的时空多尺度分析

论文利用经验模态分解(EMD)方法对1978年以来河北省粮食产量波动及其成因进行了时空多尺度的分析。从粮食产量波动的趋势量分布来看，1978年以来河北省粮食产量不断增长，但是20世纪90年代后期粮食增长停滞，且有下降趋势。EMD分解结果表明：河北省粮食产量存在4年、6年及11年左右的准周期波动，并以4、6年左右的周期波动为主；在对河北省4个国家二级生态类型区进行EMD分解时发现，Ⅵ₁辽吉西蒙东南冀北山地区与Ⅱ₂冀鲁豫低洼平原区是粮食产量4年左右周期波动的控制地区，而Ⅱ₁燕山太行山山前平原区与Ⅱ₂冀鲁豫低洼平原区，是河北省粮食产量6年左右周期波动的主要控制地区；在对粮食单产和粮食播种面积两个影响因子进行EMD分解时发现，粮食单产是粮食产量4年左右波动的主要控制因子。同时粮食单产也是1978-1993年时段粮食产量6年左右波动的主要控制因子，粮食单产和粮食播种面积的波动叠加交互作用控制着1993-2005年时段粮食产量6年左右波动的变化。对两个尺度的周期性波动分析发现，河北省粮食产量波动幅度近年来不断增加，这将给河北省的粮食供需关系带来巨大的压力。研究的时空分析结果为保证粮食稳定生产具有重要的指导意义。

Analysis on the Fluctuation of Grain Output in Hebei Province and Its Causes at Multi-time and Space Scale Based on Empirical Mode Decomposition Method

The EMD method was introduced to study the fluctuation of grain production in Hebei Province of China and its causes at multi-time and space scale since the year of 1978, and the data show that the annual grain output in Hebei Province of China continued to grow until late 1990s but stagnation and downward trend from then on. The data have been decomposed into three IMFS and a residual trend term. The conclusions are drawn: 1) The fluctuations of grain output have 4-year, 6-year and 11-year time scales. Hereinto, fluctuations of the 4-year and 6-year time scales are more prominent. Shown from the residual trend term, the grain output has increased continually since 1978, but stagnated after 1998. 2) We have decomposed the data of fluctuation of grain output in national secondary ecological districts of Hebei by EMD. We found that Ⅵ_1 and Ⅱ_2 are the control factors of the about 4-year fluctuation of grain output and Ⅱ_1 and Ⅱ_2 are the main influencing factors of the 6-year fluctuation of grain yield. 3)We have decomposed the data of per capita grain yield and cultivated land by EMD. We found that per capita grain yield is the control factor of the 4-year fluctuation of grain output and the 6-year fluctuation of grain output during 1978-1993, the superposition interaction of per capita grain yield and cultivated land are the main influencing factors of the 6-year fluctuation of grain yield. Therefore, in order to eliminate the short-term and the long-term unfavorable factors, we must improve the foundation of grain production, add the investment in science and technology and enhance the ability of disaster prevention and control the decrease in cultivated land so as to stabilize per grain yield in Hebei Province of China. Analysis on the periodic fluctuation of the three time scales revealed that fluctuation of the grain output will be strengthened in the recent years, which means that it can be possible for a big pressure of the grain security in Hebei. So the conclusions of the paper will take measures to guarantee the grain security.