Abstract
Changes in habitat areas of mangrove trees along the Nagura river, the Miyara river and the Fukido river in Ishigaki island of Okinawa prefecture are studied by GIS analyses of aerial photographs taken within 10-year interval since 1962 to 2007. The GIS analyses showed a rapid wide change in the habitat area of mangrove after the construction of a drainage channel in the lagoon of the Nagura river. Although the catchment area of the Miyara river is nearly the same as the one of the Nagura river, the Miyara river has experienced little change in its mangrove habitat. The Fukido-river area has almost been consisted of a natural forest of mangrove. Little change of the mangrove area is also seen in this location. Study results show that the advancing of the mangrove habitat area onto the sea side is limited in shadow areas against incoming ocean waves.
