Periodic annual increment (PAI), is a forestry term that describes the change in the size of a tree between the beginning and ending of a growth period, divided by the number of years that was designated as the growing period (Avery, 339). For sigmoid growth, the graph of PAI increases rapidly and then quickly declines, approaching zero. PAI may go negative if a tree loses volume due to damage or disease. Periodic annual increment is commonly used instead of current annual increment as a basis for computing growth per cent. Growth per cent indicates the rate of increase with relation to the wood capital required for its production, this is usually based on a single year's growth (Chapman, 315).
Famous quotes containing the words periodic and/or annual:
“But parents can be understanding and accept the more difficult stages as necessary times of growth for the child. Parents can appreciate the fact that these phases are not easy for the child to live through either; rapid growth times are hard on a child. Perhaps it’s a small comfort to know that the harder-to-live-with stages do alternate with the calmer times,so parents can count on getting periodic breaks.”
—Saf Lerman (20th century)
“No annual training or muster of soldiery, no celebration with its scarfs and banners, could import into the town a hundredth part of the annual splendor of our October. We have only to set the trees, or let them stand, and Nature will find the colored drapery,—flags of all her nations, some of whose private signals hardly the botanist can read,—while we walk under the triumphal arches of the elms.”
—Henry David Thoreau (1817–1862)