Half of Russia's overall land area is moun-tainous and most of these NPAs are in the mountains, including all seven of Russia's nat ural World Heritage sites. Most are in the Caucasus, Altai, Kuznetsky Alatau and Sayan Ranges in southern Russia, and in the Kamchatka, Jugjur and Sikhote-Alin regions in the Far East. These mountain ecosystems have with a long period of snow harsh climates cover, steep, unstable and highly erodible land scapes with high frequency of avalanche, debris flow and rockfall; thin skeletal rocky soils; and complex mosaics of plant and animal habitats,