The key zones of returning farmland to forestland and grassland in Ningxia were studied. By using the ＂stepwise revised method＂,the climate productive potential,light and temperature productive potential in the zone in recent 50 years were counted. The light and temperature productive potential of corn in Ningxia irrigated area,the central arid zone and the southern mountain area presented the linear increase trend. But when considered the climate productive potentials of light,temperature and water,the numerical value was very low because of the scarce rainfall,and no agriculture without the irrigation. The light and temperature productive potential,climate productive potential of winter wheat in the central arid zone had no significant trend,but the variation range of climate productive potential was very big. The light and temperature productive potential of winter wheat in the southern mountain area had no significant variation trend,and the climate productive potential presented the weak decline trend. It illustrated that the productive of winter wheat was greatly restricted by the water content. By using the meteorological factor data which were simulated by RegCM3-WOFOST/LINGRA coupled model,the future climate productive potentials of winter wheat in the central south of Ningxia was counted. They both presented the weak increase trend. It illustrated that the climate in Ningxia was favorable to improve the yield of winter wheat after returning farmland to forestland.
[Objective]The aim was to research influence of climate conditions on potato yield and establish the forecasting model of potato yield.[Method]SPSS（Statistical Package for the Social Sciences） was used to separate potato output into meteorological yield and tendency yield over the years,and analysis of the relation between potato climate yield and meteorological factors was carried out.[Result]The result showed that affecting yield factor consisted of the universality and regional.The universality included vapour pressure or relative humidity of air in last August-September,precipitation in late June to early July and in mid-August;The regional is including precipitation in January and in early to mid April,vapour pressure of air in May.Prediction model about yield was established by using stepwise regression method,which qualified rates of fitting better quality.[Conclusion]Because of its long effective period,high accuracy and simplicity to dalculate,the method provided a guarantee for weather service on the crop farming of potatoes.
In order to assess the climatical and ecological effect which returned the farmland to pasture or forest, the vegetation and crop in Northwest China with suitable threshold value were classified in this experiment by using multi-temporal SPOT/VEGETATION dada and combing supervised classification with unsupervised classification. Compared with the data from Statistical Department and actual investigation, the precision of the classified result was above 85%.
