Lichens of Golestan National Park

Golestan National Park, the first area in Iran officially designated as a national park, spans three provinces—Golestan, North Khorasan, and Semnan—and is located between the towns of Gorgan and Bojnord (37°16′34″ to 37°31′N and 55°43′ to 56°17′45″E) (see Map). This ecologically diverse region features a mountainous landscape, with elevations ranging from 450 meters in the valleys to nearly 2,400 meters along the ridges.

The climate of the park is significantly influenced by humidity from the Caspian Sea and prevailing westerly winds, which bring substantial summer precipitation to the mountains. Annual rainfall varies markedly, from around 150 mm in the eastern sections to as much as 750 mm in the west. In the highlands, precipitation remains relatively constant throughout the year. The region’s average relative humidity is 45%, increasing to 100% in the summer and dropping to 18% in winter. Average annual temperatures range between 11.5°C and 17.5°C, with recorded extremes from a minimum of -25°C to a maximum of 45°C.

The western part of the park experiences a humid, temperate climate with annual precipitation between 500 and 600 mm. This area is dominated by Hyrcanian deciduous forests, including species such as Parrotia persica, Quercus castaneifolia, Carpinus betulus, Acer velutinum, A. monspessulanum, Celtis caucasica, Cornus sanguinea, Crataegus spp., Pyrus boissieriana, Lonicera floribunda, Tilia caucasica, Acer cappadocicum, and Fraxinus excelsior.

In contrast, the eastern part of the park receives less than 400 mm of annual rainfall and features a steppe-like, Irano-Turanian vegetation dominated by species of Festuca, Acanthophyllum, and Artemisia. The central, transitional zone (400–500 mm annual rainfall) represents the most diverse ecological region, supporting a mix of shrublands, conifer stands, and pastures. This area harbors both Hyrcanian and Irano-Turanian elements, along with Mediterranean components such as Juniperus excelsa, J. communis, Berberis spp., Astragalus spp., and Euphorbia spp.

The intricate interplay of geomorphological, geological, hydrological, and climatic factors creates a wide range of habitats, resulting in high biodiversity (Akhani, 1998).

The lichenized mycobiota of northern Iran has been studied since the 19th century by researchers such as Boissier & Buhse (1860), Rabenhorst (1871), Szatala (1940, 1957), Oxner (1946), Weber (1965), Vězda (1974–1980), Nimis & Tretiach (1997), Seaward et al. (2004), Sohrabi (2005), Ahti & Sohrabi (2006), and Sohrabi & Orange (2006). However, only a few studies—namely those by Nimis & Tretiach (1997), Seaward et al. (2004), Sohrabi (2005), Ahti & Sohrabi (2006), and Sohrabi & Orange (2006)—provide precise locality data from within the present-day boundaries of Golestan National Park (Sohrabi & Sipman, 2007).