This high rainfall explains the survival of karri forests quite a distance from their main stronghold between Manjimup and Walpole. The karri forests are one of the major attractions of the Porongurups and occur chiefly on the upper slopes of the range on deep red soils known as "karri loam". On lateritic soils downslope, the predominant type of vegetation is a mixed forest of jarrah and marri, whilst on the highly exposed and frequently waterlogged summits, an open mossy herbland prevails.