It is a natural phenomenon affecting vegetation. High and rocky limestone cliffs that rise above both river banks, also including the Danube, provide a specific microclimate, which allowed the development of complex vegetation of thermophilic forests and shrubs, all the way to mesophilic beech and walnut and beech and linden forests.
In the gorge of Brnjica river there is a widespread community of Sessile oak and Turkey oak (Quercetum petraeae-cerris) with Oriental hornbeam on steep, exposed slopes. The interesting fact is that at the very beginning of the valley on the Danube bank there is a climatogenic forest of Hungarian oak and Turkey oak with Oriental hornbeam. The gorge of Brnjica river is dominated by oak (Quercus virgiliana), Turkey oak (Quercus cerris), lilac (Syiringo vulgaris), flowering ash (Fraxinus ornus), Montpellier maple (Acer monspessulanum) and Oriental hornbeam (Carpinus orientalis).