 Ecologically the Harly Forest is a near-natural hillside forest ("naturnaher Hangwald") on warm-dry chalk and silicate habitats.The southeastern edge of the ridge lies immediately above the Oker Valley and from 1203 was the construction site of an Imperial castle, built during the German throne quarrel between the Welf and Hohenstaufen dynasties.It was erected at the behest of by the Welf king Otto of Brunswick to control the trade route to the Imperial City of Goslar, whose citizens had allied with his rival Philip of Swabia.