The ecologically ideal road density for small islands: The case of Kinmen

Road construction is one of the most destructive developments on small islands. Road networks can lead to fragmentation of habitats or may cause sudden extinctions of native species, hence it is important to study the influence of road systems on a small island's ecosystem. Using the Kinmen Islands, Taiwan, as an example, this research intends to obtain the acceptable road density for small islands, from an ecological point of view. Three methods of deriving the acceptable road density for small islands are developed in this analysis. The first method incorporates the allowable density of roads for viably sustainable populations of wolves in continental areas. Since wolves are the top predators of a healthy ecosystem and because with a sustainable wolf population the ecosystem is believed to be sound, this road density could be ideal for a small island. However, the allowable road density for wolves was obtained in continental areas and it is not clear that it is valid, in direct application, on small islands. The second method modifies the road density from model islands to fit the conditions of the desired islands. In this research, Okinawa (Japan) is the model island and used as a suitable density of roads for Kinmen. Finally, in the third method, the largest small island was used as the model island and derivation procedure of the second method was applied.Results show that the smaller islands have a higher density of species but a lower ideal road density. Also, the current road density of Kinmen has exceeded the results obtained by the three models. Therefore, road construction policies must be rigorously reviewed for the sake of Kinmen's ecosystem.