我国亚热带划分中的一些问题

SOME PROBLEMS ON THE DIVISION OF THE SUB-TROPICAL BELT IN CHINA

我国的亚热带幅员辽阔、物产丰富、人口密集、地形复杂、气候多样,气候带如何划分是一个重要问题。在区划的原则、等级、指标和界线等问题上,都有不同的看法。作者就这些问题发表了意见,并提出了划分亚热带的具体方案。

The sub-tropical belt in China covers a vast area with abundant produ cts, dense population and various climates. HOW to divide this belt climato-logically is an important problem and has long been debated. The author’s opinions are as follows.1 ) The sub-tropical belt in China is divided into 3 sub-belts. the north, the middle and the south sub-tropical .2 ) Whether or not there is "dead-winter" is the main difference between the sub-tropical and the temperate belts, and the boundary coincides approximately with the 0℃ isotherm of the coldest month. Thermophilous crops that cannot be cultivated in winter is the distinction of sub-tropical belt from tropical belt, and the line of demarcation lies along the 15℃ isotherm of the coldest month.3 ) In the north sub-tropical belt the planting system is rice-wheat, two crops per year. The accumulation of daily temperature>10 ℃ is 4500-5300℃. In the middle sub-tropical belt, one can harvest five times every two years. The crops are double cropping rice, wheat or green manure, with an accumulated temp’erature (>10℃) of 5300-6500℃. The south sub-tropical belt crops three times per year, cool-like crops is adopted after the harvest of double-cropping rice, and thermophilous crops are sometimes planted too, the accumulated temperature (>10℃) is 6500-8000℃.4 ) In consideration of the regionalization of climates in the Plateau,the indices will be different from those used in the plain. It is suggested that the accumulation of daily temperature>10℃, which has been employed as indices in the above demarcation, should be minus 300-500℃ in the Plateau.