关键词: 黄淮海地区, 冬小麦产量, VIP模型, NDVI

Abstract: Huang-Huai-Hai region as the main grain-producing region,its production is closely r-elated with national food safety.Spatial-temporal evolution of crop production and its driving forces in this region should be clarified for regional scale productivity trend analysis.In this paper,a coupled model of Soil-Vegetation-Atmosphere Transfer(SVAT) and crop growth dynam-ics(VIP model) driven by AVHRR NDVI and climatic variables is applied to simulate the prod-uctivity of winter wheat in the Huang-Huai-Hai region from 1981 to 2000.In this period,air temperature became warmer and sunshine duration became shortened,whereas no obvious trend for precipitation was observed.The simulated grain yields are validated with statistic yield at county level gathered in Hebei Plain.It is found that the biomass increased before 1997 and then decreased.However,due to the improvement of harvest index,per unit area grain yield grew significantly during the whole period,with per unit area grain yield doubled in 2000 over 1981.The enhanced input of fertilizer and popularization of fine crop strains are the principal reasons for grain yield increase.The consumption of fertilizer was doubled from the 1980s to the 1990s,which contributed 40% of the grain yields.At the same time,the harvest index of winter wheat improved continu-ously from 0.31 to 0.44.However,the crop productivity was disturbed by climatic variability from year to year,which contributed 8.5% of the interannual variability of regional grain output.In the study area,the spatial-temporal evolution of grain production is clearly related with local conditions and manag-ement,e.g.irrigation facilities and soil conditions.The increment of grain yield is different in these 20 years.In the 1980s,there were 46% of the areas with an yield improvement by 30%,some areas even as high as 100%.However,the increment obviously stepped down in the 1990s,with the enhancement ranging between 15% and 30% in about 55% of the areas,and only 30% of the areas with an yield increment exceeding 30%.The grain yield of wheat in the Huang-Huai-Hai region has reached its plateau,which is supported by excess consumption of surface and ground water.To keep the agriculture sustainable in this area,water conservation and saving techniques and engineering projects should be widely improved.

Key words: NDVI, Huang-Huai-Hai region, winter wheat productivity, VIP model