Protected Forests (保護林, Hogo-rin) are areas of national forest in Japan so designated in an effort to conserve biodiversity. Japan's Protected Forest system includes three categories of protected forests: Forest Biosphere Reserves; Biotic Community Protection Forests; and Rare Population Protection Forests. Some of these national forests are linked by a network of Green Corridors that are also included in the system. Established in 1915, the system was overhauled in 2015 and expanded in 2019.