Who proposed the tourism product tree?

Wu Bihu and Yu Xi. Wu Bihu and Yu Xi expressed tourism products in the form of a tree diagram, in which the trunk represents tourism products, the roots are the three major elements that form tourism products, including attractions, facilities and services, and the five main branches represent tourism products. The five major types are sightseeing and educational tourism products, leisure and entertainment vacation tourism products, business exhibition and event tourism products, special tourism products and special interest tourism products.