[6] The lowest point within its territory is 1,360 m, accounting for a denivelation of 244 m. The average altitude is 1,482 m.[7] There are not permanent rivers within the limited territory of Bogdan but the river Topolnitsa just southwest of the reserve and its right stem the Kriva spring in its vicinity on the northern slopes.

[9] The ecosystems of the reserve are relatively homogeneous and the predominant biotope are the European beech (Fagus sylvatica) forests some 140–170 years old on average.

[11] There are two Balkan endemic species, Pastinaca hirsuta and Campanula sparsa, as well as one included in the Red Book of Bulgaria, Elwes's snowdrop (Galanthus elwesii).

Other species of conservational importance include Geum rhodopeum, Hesperis sylvestris and round-leaved sundew (Drosera rotundifolia).

The former include fire salamander, alpine newt, yellow-bellied toad and common frog.