Hyrcanian Forest Vegetation Database

The Hyrcanian forests in northern Iran are biogeographically unique natural closed-canopy temperate deciduous forests. Although many vegetation and floristic studies were carried out in these forests, a comprehensive phytosociological analysis is still outstanding. For this purpose, we created a database (GIVD ID: AS-IR-006) using the TURBOVEG software. It includes 1597 releves ranging from 20 to 400 m(2) in size sampled from 1959 to 2016, containing 802 taxa; 664 of the releves were digitized from the literature and 933 were unpublished data from fieldwork of the first two authors of this report. Species cover in the releves was estimated using three different cover scales: percentage, 7-degree Braun-Blanquet and ordinal scale (1-9). The scientific plant names were standardized following The Plant List (www.theplantlist.org). The sampled sites cover the whole range of the Hyrcanian forests from Astara (Gilan province, near to the Azerbaijan Republic border) in the west to Darkesh (North-Khorasan province) in the east, approximately 800 km in length and at altitudes ranging from -22 to 2850 m a.s.l. Information about topographic and soil properties is available for more than half of the releves. Vegetation patterns and distribution of associations in these forests are related mainly to altitude and biogeographical differences between west and east. Moreover, there are several associations connected to microhabitats with different soil properties and topographic features. The most frequent tree species in the database are Carpinus betulus, Fagus orientalis, Parrotia persica, Quercus castaneifolia and Alnus subcordata, the most frequent shrubs are Ruscus hyrcanus, Crataegus microphylla and Ilex spinigera, and the most frequent herbs are Viola caspia, Galium odoratum, Sanicula europaea, Festuca drymeja and Solanum kieseritzkii.