Analysis on Relationships between Landscape Structures and Distribution Patterns for Native and Hybrid Dandelions (Taraxacum) in Tsukuba-city, Ibaraki Pref.

Abstract

Relationships between landscape structures and distribution patterns for dandelions （Taraxacum） were examined in Tsukuba city, Ibaraki Pref. By using molecular analysis, collected samples were discriminated as " native dandelions"， "introduced dandelions"， " tetraploid hybrids， " triploid hybrids”, and "androgenesis hybrids". 32 sampling sites were grouped into five landscape types according to their similarities of land uses. The native, dandelions mainly occurred at satoyama landscape. In contrast, hybrid dandelions （tetraploid hybrids） mainly occurred at urbanized areas and bare, lands. Vegetation survey was also conducted at 20 sampling sites, and their components were summarized by DCA analysis. Positive correlation was found between the frequency of native, dandelions and, vegetation of forest floor and margin, and negative correlation between the frequency of tetraploid hybrids and, vegetation of open habitats. Based on the results obtained, it was suggested that, native dandelions tended to exist in the landscape containing more forest margin, whereas tetraploid hybrids in landscape developed, and/or vacant lands. Role of dandelions as environmental indicator species was discussed.