Impact of Street Tree Base Management on the Plants Colonizing Street Tree Bases in Western Japanese City

Abstract

The space at the base of street trees (hereafter referred to as "street tree bases") is invaded and colonized by a diverse plant population, primarily consisting of native species. As such, it is implied that street tree bases contribute to urban biodiversity. Various types of street tree bases exist (hereafter referred to as "street tree base types"). These include trees with garden beds at their bases, and trees with bases covered by artificial structures. However, there is a lack of information regarding the plants that invade and colonize street tree bases and comprehensive research is required in this direction. Therefore, we conducted a study involving street tree bases (n=104) and we examined the effects of street tree base types on the plant species that colonize the bases of street trees, in Fukuoka City, one of Japan’s five largest cities. In addition, the street tree base’s contribution to urban biodiversity was examined and was based on the presence of buried seed populations. Our results show that many plants that were not found in other types invaded and colonized in each street tree base type, forming a plant community that differed from other types. We believe that street tree bases can further increase urban biodiversity by establishing various street tree base types and management of their street tree bases. In addition, it was found that buried seed communities were present in many street tree bases indicating that they also serve as urban soil seed banks.