:A project creating artificial forests, "Amagasaki Forest Central Green Space," has proceeded in an urban waterfront area in Hyogo prefecture for ten years. In this project, plantings of nursery stocks from local plants are selected with consideration for biodiversity. In this paper, we analyzed the record of local seed collection, clearly defined as the role of each participant. Our results revealed those two features, the number of seeds and the number of species, differed by categories that were divided according to the sector to which the participants belonged. The category consisting of experts was equipped to collect many kinds of seeds, taking advantage of their identification capability. On the other hand, another category of citizens and/or enterprises, mainly beginners, working with the experts, was able to collect many kinds of easily-identifiable seeds such as acorns. The participants were also able to collect a large quantity of seeds when activities were held as a nature observation event by the experts. These results showed that efforts to preserve species diversity by mass collection of seeds from local plants should be supported by role sharing among various participants.