Old - growth can not solely be determined by size or age of the trees within a forest because these qualities vary widely with species. (nps.gov)
These frequent fires, over several centuries, created diverse patterns of forest species, varied ages of tree species and tree species replacing one another in succession. (trib.com)
Looking further for reasons to wring our hands or turn our backs on pellets, we find that German forests have increased between 2002 and 2012, the average age of trees is increasing, and the sustainable wood harvesting still has room for growth. (treehugger.com)