Special Column:Celebration of the 70th Anniversary of IGSNRR, CAS
Yang Bai, Li Shikui, Huo Zhiguo
In this paper, the dynamic variation of the norhtern boundaries of the North-, Middle-and South-subtropical zones and its influence on agricultural production in the subtropical region of China in the last hundred years are studied by analyzing the climatic data of 315 meteorological stations. The main results show:(1)The northern transitional zone of the South-Subtropical Zone is narrower than those of the others. The northern transitional zone of the North-Subtropical Zone in the plain is about 1. 5 degrees of latitude on the average and is wider than that in the mountainous areas. The width of the transitional zone between the North-and Middle-Subtropical Zone in the Poyang and Dongting Lakes plain is about 1. 5 to 3 degrees of latitude, while in other parts it is much narrower.(2)The range in which the line of demarcation swings in different periods is narrower for the northern boundary of the South-Subtropical Zone and wider for those of the others. For the northern boundaries of the North-and Mid-Subtropical Zones, the swing range is wider in the plain than in the mountainous areas. In the plain, for the northern boundary of the North-Subtropical Zone, the distance between the lines of demarcation in the coolest and warmest periods is 1. 5 degrees of latitude on the average. In the Poyang and Dongting Lakes plain, for the Northern boundary of the Mid-Subtropical Zone, it is 2 degrees of latitude on the average.(3)In the last hundred years, the variation of agroclimatic zone may cause the northern boundary of the double cropping rice to swing about 1 degree of latitude at most, and the swing is close to 1 degree of latitude for the suitable and probable planting regions of orange.
