The Agro-climatic Vertical Zoning Based on GIS for Shangluo District in Southern Shaanxi Province

The agrotopoclimatic vertical zoning based on GIS is carried out by fuzzy comprehensive assessment. Shang-luo mountainous area is taken as an example, which is in the east of the south slope of Qinling Mountains in Shaanxi Province, and which belongs to the semi-humid mountainous climate transition from warm extratropical to subtropical zone.The heat index for vertical zoning is used to resemble the general characteristics and the regional differences by four kinds of spatial grids database. Cumulative temperature greater than 10 ℃, average extreme lowest temperatures, mean temperatures of the coldest mouth and mean temperatures of the warmest mouth are included. Before the indexes are spatially interpolated by inverse distance weight (IDW), they are emended to the same height above sea level via the lapse rates with the help of digital elevation model (DEM), which are based on sectional observation data in subtropical west mountainous regions in Qinling and Bashan.With the overlapping function of GIS, the graph of comprehensive zone of agro-climatic resources in Shangluo mountainous region based on GIS is made by superposing vertical zone grids with aridity grids in growth season and north subtropical boundary vector, using the combined function of the GIS.According to the comprehensive division graph made by GIS, three layers are divided into two climatic zones in Shangluo area:hot layer with easily drought tendency ( < 700 m), warm and semi-humid layer (750—1250 m), mild-cold and cool-cold humid layer (1250—1800 m) in subtropical zone. Warm drought layer with easily drought (800—1000 m), mild-cold and semi-humid layer (1100—1500 m), cool-cold and humid layer (1500—2500m) in warm extratropical zone. The naming for the vertical zoning reflects the horizontal and vertical climate characteristics of the Shangluo region, and the economic development direction in each layer.