河北省退耕还林对粮食生产的影响

从定性和定量角度分析退耕还林对粮食生产的影响，并采用灰色GM（1，1）模型预测河北省未来8年的人口发展趋势，最后利用灰色关联法对河北省粮食总产量的影响因素进行研究分析。结果表明：退耕还林造成全省耕地面积的减少，但由于其改善了粮食生产环境，大大提高了粮食单产，从而增加了粮食总产量；河北省未来人口持续增长，对耕地和粮食资源产生很大压力；在影响河北省粮食总产的诸因素中，粮食单产和灌溉是决定粮食总产的首要因素，而化肥施用量则为次要因素。

Effects of removal lands from cultivation to afforestation on grain production of Hebei Province

Effects of removal lands from cultivation to afforestation on grain production are analyzed by means of qualitative and quantitative methods.The module of GM(1,1) is used to forecast the trend of population development of Hebei in the next eight years and the gray correlation method is applied to study factors of the total grain yield.The results show that removal lands from cultivation to afforestation leads to the reduction of cropland areas in the whole province and improves the environment of grain production at the same time which increases the grain yield per unit area.So the total grain yield is increased.The increasing population brings the large stress on cropland and grain resource. Grain yield per unit area and irrigation are the most important factors among all influencing factors and the application of chemical fertilizer is the secondary factor.