Plantation species are tree species suitable for mass plantation to rehabilitate forests for erosion control and retaining water. After centuries of cutting and burning, many of the Hong Kong hillsides gave an overall impression of dry barren soil. Early afforestation effort was concentrated on the use of fast growing exotic species such as Pinus elliottii, Lophostemon confertus and Acacia confusa. Native species have been used more often in recent years, such as  Machilus spp., Castanopsis fissa and Schima superba.