【摘要】 据西北五省区制定的规划或计划,到2010年将累计退耕400×104hm2,约占现有耕地面积的1/4。按照目前的单产水平和粮食作物比例,西北地区将减少粮食产量近400×104t,相当于1996年西北地区粮食总产量的1/8。同时,退耕对当地的粮食生产存在正面影响,主要表现在:①退耕节省下来的生产要素的转移可以带来未退耕耕地粮食产量提高;②西北地区生态环境以及局地小生境的改善可以促进粮食生产、降低灾害风险。此外,农业科技进步和工程设施建设的加强,会对保留耕地上的粮食生产起到极大的推动作用。通过对西北五省区粮食单产的预测并结合人口预测可知,2010年西北地区粮食总产量可达4516.9×104t,在人均400kg、425kg和450kg水平下粮食需求分别为3936.1×104t、4182.1×104t和4428.1×104t。因此,从长远的角度来看,就西北地区整体而言将不会出现粮食短缺,但粮食盈余水平较低;而就具体省区而言,陕西、甘肃和青海三省区必须通过粮食调入才能满足本省区需求,而新疆和宁夏粮食则有一定盈余。更多还原

【Abstract】 The conversion from farmland to forest or grassland is an effective way to make North-west China beautiful,but necessarily it may influence the grain production of that region.Accord-ing to the plan made by the five provinces /municipalities,till2010the accumulative total area of farmland to be converted to forest or grassland is about 400×10 4 ha,or24.8%of the total farmland area.That is to say,400×10 4 t grain(12.4%of the total grain production in1996)will be minified in Northwest China.Simultaneously positive impacts caused by this kind of conver-sion must be seen.They are expatiated as below:(1)the transfer of water,fertilizer etc.to re-served farmland can bring more marginal profit;and(2)the improvement of ecological condi tion and local environment can promote grain production and reduce the risk of natural disasters.Furthermore,the advancement in agricultural science and technology,and the construction of a-gricultural infrastructure must make reserved farmland more productive.After predicting we can see that the total yield of grain in Northwest China will hit4516.9×10 4 t,and the demand of grain,respectively based on the different level-400kg,425kg or450kg per capita,is about 3936.1×10 4 t,4182.1×10 4 t or4428.1×10 4 t.Then a conclusion can be drawn that from the long-term point of view the grain shortage will not appear in Northwest China on the whole,but the situation is austere.To achieve the equilibrium of demand and supply,Shaanxi,Gansu and Qing-hai must import grain from Xinjiang and Ningxia.更多还原