Due to many centuries of intensive settlement, most of the area is shaped by human influence. The original natural vegetation of Thuringia is forest with beech as its predominant species, as can still be found in the Hainich mountains today. In the uplands, a mixture of beech and spruce would be natural. However, most of the plains have been cleared and are in intensive agricultural use while most of the forests are planted with spruce and pine. Since 1990, Thuringia's forests have been managed aiming for a more natural and tough vegetation more resilient to climate change as well as diseases and vermin. In comparison to the forest, agriculture is still quite conventional and dominated by large structures and monocultures. Problems here are caused especially by increasingly prolonged dry periods during the summer months.