关键词: 自然地理界线, 可拓工程, 主成分分析

Abstract: By means of the method of extension engineering, this article sets up a matter-element model of distinguishing objects. The model can be used to define the most reasonable location of the north boundary to the south subtropical belt in Fujian Province, and to show the various transitional states near the boundary objectively and quantitatively.In the design of the model, some generally recognized temperature indices and typical samples are chosen according to physical geography theory, to guarantee the correctness of the single-index dependent function. In the construction of the multiple-index comprehensive dependent function, the method of principal component analysis(PCA) is employed to determine the weight assignation of related factors, so as to avoid subjectivity and to balance objectively the deviation of the single-index boundaries. The model gives the output with satisfying explanations in physical geography meaning.Finally, the paper discusses the controversies on the east and west sections of the boundary, and points out that it is difficult for traditional qualitative methods and classical mathematics to explain the transitive features of geographic boundary, while the matter-element model has its advantages in this respect.

Key words: physical geograghic boundary, extension engineering, principal component analysis