The Hyrcanian forest is a unique natural heritage of global importance

The Hyrcanian forest is a unique natural heritage of global importance. The Caspian region harbors the world's last remaining primary forests of the temperate deciduous forest formation.

In Europe, eastern North America and East Asia the temperate deciduous forests are reduced to less than 1/3 of their natural distribution area, and most of the remaining stands are changed to secondary woodland and artificial plantations. Semi-natural and old deciduous forests survived or regenerated in few protected areas and only on small sites. In Europe and East Asia, this is the result of several thousands of years of land use history, but in North America the deciduous forests were changed during the last four centuries.

The Caspian region in the North of Iran is one of the most important refuge and survival areas of “Arcto-tertiary” forest vegetation in western Eurasia (like the Colchic in Georgia and Turkey). The Caspian (together with the Colchic) forests are the oldest (in terms of their evolution since the tertiary period), the most diverse (in terms of forest types, structures and biological diversity including relic and endemic species), most productive and most natural temperate deciduous forests in western Eurasia.

The main potential is the integrity of the Caspian region as a terrestrial eco-region, defined by certain geological, geo-morphological, climatic, and biodiversity features, that means:

- Geologically young (tertiary) high mountain range, consisting of old bedrocks of different formations of the Earth history (Paleozoic, Mesozoic), and of younger volcanic (tertiary) and marine and fluviatile (quaternary) deposits,

- wide array of geo-morphological forms, such as coastal plains, slopes, valleys, volcanic mountains, rocks, ridges, karst forms etc.,

- Temperate humid climate with an altitudinal gradient and a gradient from Northwest to East,

- Regional water cycle between the Caspian sea (with the Volga river, the drainage area includes large parts of the European deciduous forest region) and the Alborz mountains (great number of springs, streams, rivers flowing back to the Caspian sea),

- closed vegetation cover, mainly formed by the Caspian forests, which provide key ecosystem functions, such as water supply, climate stabilization, carbon storage and sequestration, soil formation and soil protection, habitat of biological diversity etc.,

- “hot spot” of biodiversity with very specific ecosystems, high number of plant and animal species including endemic forms, particular genetic resources.

The proposed areas represent the most important example of a temperate deciduous forest eco-region in western Eurasia. With regard to the high diversity of ecological, cultural and socio-economic aspects of the region the proposed heritage should consist of several parts. For that reason six areas in Iran are selected and defined as parts with different functions. The selection of areas is based on the natural division in watershed basins and covers the altitudinal profile from the foothills to the high mountain belt. They are selected along the gradient from East to West and it started with Golestan national park as biggest part.