Ethno-Forestry in Lanyu among the Tao/Yami people is the tribal scientific craft of creating, managing, using, conserving, and repairing forests, which has been largely associated wildlife resource management to meet desired cultural goals, material needs, and ethic values for both human and environment benefits. Their horticulture gardens within tropical forest are culturally and ecologically maintained as the inland g, coastal forest, cliff plantation, and grassland with shrubs, continuing to supply the plant resources needed for the daily rituals. In this study, the forest garden ants were investigated across six villages of Lanyu from 2000 to 2002. The Berlesse funnel for ant detections was set to quickly estimate the biological diversity and composition across 25 coastal watersheds in Lanyu Island and one shrubland in Xiaolanyu, totally 274 sites. A total of more than 40 ant species has been recorded, and the interaction of 20 dominant ant species was described, accounting for 95% of all individuals. The horticultural gardens in Lanyu mainly rely on the disturbance mechanism of natural forests and the custom management of Tao/Yami ethno-forestry. Gaps have been regenerated differently according to inland forests, sea cliffs, shrubland and fallows that gradually returned to fertility. Historically ecotones are created upon human landscape. Modern state constructions are recommended to respect the land use tradition of tribal forestry, to understand local roles of forest renewal and ecological conservation through aboriginal horticultural skills, and to avoid profound impacts of modern engineering methods on the fragile island environment.