When considering forest management, it is important to understand the distinction between biological maturity and economic maturity, and more particularly that economic maturity usually precedes biological maturity. There is some gray area between the two, and it helps to consider the entire stand above and beyond the individual trees- since any harvest that may occur would treat the entire stand.
At a certain point in the life of a tree, it begins to increase in volume at a decreasing rate. The tree continues to grow, but it does so at an ever-decreasing rate until it eventually dies. During this time, it may develop hidden interior defects such as mineral stain, wind shake, or heart rot. A forested stand reaches biological maturity when the losses in volume due to death or other factors exceed the volume gain from new growth. Economic maturity is driven by a number of factors, but essentially occurs at the point when the amount of net annual return provided by the timber stand is at its peak. The landowner would not receive any more income by delaying a harvest, and would realize a better return from a newly established, productive timber stand.
Biological and Economic Maturity - Growth Rings on Pine Tree