A diversity Survey of mountainous forests trees in north of Iran

Biodiversity and its natural process in different ecosystems contribute to the correct understanding of the interrelationships between the land, climate, plants and other living things. Through biodiversity, it is possible to plan the utility patterns of natural resources by referring to its component parts. The forests of North of Iran (with an area of 1.8 square kilometers) belong to the Hycranian or deciduous broad-leaf forests and possesses a temperate and humid climate. They are of great importance in Iran because of their uniqueness in plant community, ecological, genetic and species diversity. As only a small percent of the plants in Iran is located in Europe, Siberia, Caspian sea coasts and the forests of north of Iran, the number of tree species and shrubs reaches to more than 80 and 50 respectively. Besides, since the majority of the forests of north of Iran are mountainous and have a high diversity of woody species a study of the trees species of the Hycranian forests can prove to be very useful and of highest importance. For this purpose, 40 sample plots 0.5 hectare have been randomly chosen and surveyed in different altitudes between 100-3520 m of Tonekabon forests. The results obtained from the analysis of this survey, indicates that with increase in altitude from sea level, species richness decrease while species diversity and evenness continue to rise so that the maximum species diversity is observed at the altitude range of 350-750 m above sea level and the least diversity of species is observed at the range of 1550-1750 m altitude.