Why forest lakes have a short lifespan
From the time a lake is created, it begins to fill with dead plants, eroded soil material and other sediment. As dead plants break down, they reduce oxygen levels in the lake. This, in turn, slows down decay causing more vegetation to build up on the bottom and the lake gets shallower. Water-loving plants around the shore gradually extend to the middle of the lake to form a swamp. Eventually, shrubs and trees establish and the forest gradually takes over.Source.
