Floristic and species diversity in altitudinal gradient of Lahrod-Shabil (north Sabalan)

This study was conducted by the aim of study the species composition and diversity in the north faced slopes of Sabalan (altitude profiles of Lahrood-Shabil) along 7 transects in three elevation classes of 1500 to 2000m, 2000 to 2500m and 2500 to 2700m in the grass-shrubland dominated habitats. Plant specimens were collected in the fieldworks, and then species were identified using the checklists and reliable literature. Overall, 64 identified species were belonged to 48 genera and 22 families. Poaceae family with 9 genera and 16 species, Fabaceae family with 4 genera and 8 species and Asteraceae family with 6 genera and 6 species are the dominant family and genera. According to the Rankaier's system hemicryptophytes with 50%, therophytes with 31%, geophytes with 16% and chamaephytes with 3% are the growing life forms at the study area. In terms of geographical distribution, 42% of the species are belong to Iran-Turonian region, 22% of those to Iran-Turonian and Euro-Siberian, 12% are cosmopolitan, 3% to Euro-Siberian and other 21% is belong to other regions. From the identified species 6 of them are in threatened status based on the International :union: for Conservation of Nature and Natural Resources (IUCN) criteria. Diversity and evenness of species were calculated using numerical indices. Results of numerical diversity indices (Simpson and Shannon-Weiner) showed significant change according to elevation. However, the evenness indices (Simpson and Smith and Wilson) show no significant change by elevation.