of trees or stands 1. a tree or even-aged stand that has reached that stage of development when it is declining in vigor and health and reaching the end of its natural life span 2. a tree or even-aged stand that has begun to lessen in commercial value because of size, age, decay, or other factors —note the term has little applicability to uneven-aged stands, which consist of trees of diverse ages and stages of development —see mature, old-growth forestThis definition last updated 07/22/2008