Istanbul, marked for centuries for its historical, cultural and art richness of the Middle East, has also noted for its many natural beauties and interesting points, like Princes' islands. Having a Mediterranean climatic condition, these islands differ from the region in general and offer a different vegetation cover to Istanbul in a short distance. This vegetation cover, especially red pine (Pinus brutia) forests and maquis species create a Mediterranean aspect for the great Istanbul City. Previously, Princes' islands were small fisherman village. After 1856, starting of the steamships for transportation, reaching to Islands has become easier and islands population has started to increase. A new settlement formed with summer houses begun to establish on the islands in 1940's. New houses first appeared around the dock and spread along the seaside After 1945, these housing groups reached to hills of the Islands. In this study, effects of these settlements on the natural vegetation covers of the Buyukada, the largest one of the nine islands, are evaluated. For pointing out of this effect, decreasing of the forested areas was calculated with the base of the forest regulation changes within a historical perspective and fire effects on forest decline. These determinations were made by a designed monitoring system, which is especially prepared for Buyukada.