1. silviculture trees dying from natural causes, usually by size class in relation to sequential inventories or subsequent to incidents such as storms, wildfire, or insect and disease epidemics 2. wildlife the loss to a population from all lethal causes, i.e., hunter kill, poaching, predation, accident, and disease —note mortality is a statistic generally expressed as a mortality rate (death rate, casualty rate) per 1,000, derived from the mean number of deaths divided by the mean population —see recruitment, turnoverThis definition last updated 07/20/2008