The pattern of landscape patches and invasion of naturalized plants in developed areas of urban Seoul

Fragmented developed areas usually support source-sink patches for invasive organisms in urban landscapes. Invasive plants that have a different origin than the spreading source have an important role in artificial landscape restoration in degraded areas. However, many alien plant species have invaded the original habitat or ecosystem of native plants; sequentially their fast growing populations colonize neighboring ecosystems easily. Biological contamination sometimes occurs, unbalancing biodiversity in the natural landscape system. Therefore, long-term monitoring for dynamic communities after restoration in urban areas is indispensable for establishing a strategy for sustainable urban management. Under this principle we have examined the spreading of representative naturalized plant species according to recent land use changes. In this study, we have selected two representative invasive plants, Robinia pseudoacacia and Eupatorium rugosum. Their distribution pattern and patch characteristics of population were identified by the data of Seoul Biotope Map and a field survey. As a result of GIS-aided analysis of landscape patches, these two species often occurred in the same place. Concentration patterns of population distribution were found in forest edges disturbed by development of roads and human settlement. Especially, Eupatorium rugosum had extended to inner forest patches although the individuals were scattered. Distribution patterns of those species were partly related to landscape indices such as patch size and shape of the forest edge.