Several naturalists followed in the 19th century, including Filippo de Filippi, William Thomas Blanford, and Nikolai Zarudny who documented mammal, bird, reptile, amphibian and fish species.
The most extensive forest is found on the mountain slopes rising from the Caspian Sea, with stands of oak, ash, elm, cypress, and other valuable trees.
On the plateau proper, areas of scrub oak appear on the best-watered mountain slopes, and villagers cultivate orchards and grow the plane tree, poplar, willow, walnut, beech, maple, and mulberry.
[2] Ungulate species include wild boar, urial, Armenian mouflon, red deer, and goitered gazelle.
Endangered species in Iran include the Baluchistan bear, Asiatic cheetah, Caspian seal, Persian fallow deer, Siberian crane, hawksbill turtle, green turtle, Oxus cobra, Latifi's viper, dugong, Panthera pardus tulliana, Caspian Sea wolf, and dolphin.