Description　　The Hyrcanian Forests form a green arc of deciduous mixed broad-leaved forests stretching across some 850 kilometres along the Caspian Sea, from the Talish Mountains in the Republic of Az

Description

　　The Hyrcanian Forests form a green arc of deciduous mixed broad-leaved forests stretching across some 850 kilometres along the Caspian Sea, from the Talish Mountains in the Republic of Azerbaijan across the Alborz Mountains all the way to Golestan Province in the Islamic Republic of Iran. As the main climatic barrier and watershed between the Caspian Sea and the arid Irano-Turanian Plateau, the steep ridges of the Talish and Alborz mountain systems serve as an insuperable barrier of moist air accumulated above the Caspian Sea. As a result, there is ample precipitation feeding many rivers and creeks rapidly flowing down steep slopes and mountain gorges into the Caspian Sea. Thus, the Hyrcanian Forests (sometimes also referred as “Caspian Forests”), are metaphorically squeezed in between the “claws” of the Caspian Sea and arid drylands.

　　The forests are geographically separated and biogeographically distinct from Caucasus mountain forests, but linked with the latter by transition types found in Dizmar Protected Area (Iran). Due to highly particular topographic and climatic conditions, the Hyrcanian Forests survived the ice age periods as extremely rare “Tertiary relict forests” and have subsequently been adapting to the postglacial climate changes. Their natural distribution area is limited by the Caspian Sea, and by two main ecotones: first, the altitudinal treeline in the mountains and the dryness treeline where the forests transition into the mountain grasslands and semi-deserts of the South-Caucasian and Irano-Turanian dryland regions.

　　The serial World Heritage nomination of carefully selected representations of the Hyrcanian Forests located in the Islamic Republic of Iran was inscribed on the occasion of the 43^rd session of World Heritage Committee in Baku, Azerbaijan, according to criterion (ix) (Decision 43 COM 8B.4). The serial property encompasses 15 component parts representing key examples of the various stages and features of natural Hyrcanian forest ecosystems. While most of the ecological particularities characterizing the Hyrcanian Forests are represented in the inscribed property, there is considerable potential for further serial extension to include additional areas of global conservation value in both the Islamic Republic of Iran and the Republic of Azerbaijan. The proposed serial transnational extension amounts to a full nomination, triggering a prior updating of the Tentative Lists of both involved States Parties. The additional components proposed are described below. All add value to the inscribed property in terms of inscription criteria (ix) and (x). It deserves to be emphasized that the Committee explicitly encouraged a transnational approach (see Decisions 30 COM 8B.24 and 43 COM 8B.4).

　　The forest region is recognized as a Tertiary floristic center, representing a vast natural museum featuring numerous endemic and relic species. Jointly with the Colchis of Georgia, it is the most important arcto-tertiary relic and diversity center of broad-leaved deciduous forest vegetation (nemoral forest biome) and its flora and fauna in Western Eurasia, stretching from the coastal lowlands and foothills to the upper mountain belt. Despite the similarities,there are important differences between Colchic and Hyrcanian forests in terms of climate, forest structure and composition as well as altitudinal zoning. For example, the upper mountainous forest belt in the Colchis is formed by evergreen coniferous forests of Abies nordmanniana and Picea orientalis, whereas deciduous broad-leaved forests of Quercus macranthera and Carpinus orientalis dominate this altitudinal belt in the Hyrcanian region. The most characteristic and specific relic tree species of the Hyrcanian forests, Parrotia persica, is entirely missing in the Colchis. While nemoral broad-leaved forests also occur in Europe, Eastern Asia and North America, they have mostly been converted to agricultural land or fundamentally altered and degraded by human activities there. Unlike anywhere else at this scale, the Tertiary flora continues to be exceptionally intact, both in the inscribed property and the components proposed as extensions. The most intact representations of the Hyrcanian Forests can thus be regarded as the best available representation of intact Holarctic mixed and deciduous forests worldwide.