초록
Ansan city in the coastal area of the mid-western Korea is known as a newly industrialized city(73.44$Km^2$, 127, 000 persons), with the increase rate of 27.8% in population and mean density of 1, 732 persons/$Km^2$. According to the census of the city(1986), it consists of cultivated field(36.8%), forest(34.2%), industrial area(7.4%), residential area(4.1%) and others(12.5%). The forest vegetation in the city is composed of four associations and two subassociations as follows; Pinus rigida, Pinus densiflora-Rhododendron mucronulatum, Quercus mongolica-Rhododendron mucronulatum and Robinia pseudo-acacia asociation, and Quercus mongolica-Corylus sieboldiana var. mandshurica and Robinia pseudoacacia-Alnus hirsuta subassociation. Various environmental conditions have been changed with the progress of urbanization of the city, since 1977. For example, a heat island phenomenon, which is the air temperature of 2 or 3$^{\circ}C$ higher in the central area than that of the boundary area, and floral changes caused by air pollutants such as decreasing bryophyte species along increasing SO$_2$ concentration.