The data collected from the inventory is considered and the first thinning operation is planned when the plantation is around 30 years old. The target is to remove about 33% of the trees in a plantation to create openings that allow for more light and space so the remaining trees will thrive. The aim is to remove any diseased trees so that healthy trees will not be infected and leave any hardwood trees that are present, either from planting or natural regeneration. The trees to be removed are painted with a dot or slash by forestry staff or a hired contractor. This process is called “marking” and operators only harvest the marked trees.