Longitudinal and lateral distribution patterns of an alien plant, Vicia villosa along the Nakdonggang River in South Korea

초록

Vicia villosa, an alien plant introduced as a rotation crop, has invaded into the riparian area and reduced biodiversity of native vegetation along Nakdonggang River in South Korea. The aim of the study was to elucidate the distribution patterns and their causing factors of V. villosa in the riparian zone of the Nakdonggang River. We mapped the distribution area of V. villosa community and investigated the land use within the levees and adjacent river at intervals of 500 m along a 336 km-long riparian zone of the river. V. villosa was found almost everywhere along the Nakdonggang River. Spatial analysis with Moran's I showed that V. villosa communities were spatially autocorrelated and aggregated in the riparian zones along the linear longitudinal scale from downstream to upstream. Our findings revealed that V. villosa might be introduced from the cultivated cropland adjacent the river and expanded mainly to the nearby artificial grassland in the riparian zone. It is recommended to start controlling V. villosa from the center of its aggregated distribution area and it is necessary to manage riparian zone and adjacent areas of rivers simultaneously.