Don't see too many trees around there - how come?
Far northern Iceland, and pretty rocky. (Near the coast; map below.)

According to what little I can determine from the German on the page from whence this comes: Der Wasserfall Dynjandi, it's on the side of a fjord.
"Don't see too many trees around there - how come?"
Depends. Could be there never were trees at this place.
Iceland has some trees. They have planting programs. When the vikings came there were trees, mostly birches. Used them up for things like charcoal and rafters.
Volcanic rock doesn't harbor much fertile soil.