I am in Sweden inspecting embankment dams. On the one I am right now there is red lichen growing on most of the rocks in the slopes. However, I encountered a part that does not have this red lichen for some reason. Now I am wondering why this is? Could it be because something is different inside the dam at this part? Like temperature, leakage etc? Does anyone have a suggestion?
Could be, but I would rather expect some recent disturbance. Similarly when I was in Tatra mountains in Slovakia, it was obvious which stone is in place for very long time and which was broken just recently.
Maybe because of its exposure to sunlight? or being a dam I am sure they have catchment maintenance and one of the jobs would be to keep noxious weeds at bay.
So the target species of weeds they may have sprayed at the bottom of the lichen growth may of oversprayed from drift onto t he rocks and killed the lichen in that area, any selective or non selective herbicide would do this.
If you look closely there appears to be a lot of dead what look like weeds directly in front of the the whiter rocks.