Plant species richness was studied along altitudes in northern Iran. Data from 216 plots showed an increase in species with altitude, peaking at 2500m. Forbs were the most common plants, while ferns were the least. A polynomial model accurately represented the change in species richness. Woody plants had peaks at 1900m and 2100m. Species diversity decreased with altitude due to human activities like road construction and tourism. Conservation strategies are needed to protect the ecosystem.