Shipway in “Quality takes Time” makes the case for growing bigger, more mature trees to provide high quality wood for value-added secondary manufacturing. He also argues the age at which Douglas-fir growth begins to slow and decline – the culmination of Mean Annual Increment should be raised from the 80 to 90 year mark that early 20th century growth curve calculations (McArdle, 1961) inferred, to at least 200 years. Though he rightly states that there are few known concrete examples of this that can be adduced, research on the species within it’s natural range in the Pacific Northwest supports his inference.
In 1991, when the US Federal Courts curtailed logging on 17 Western national forests over concerns about the rapid loss of late seral (‘old growth’) habitat for the threatened northern spotted owl, one effect was to motivate the US Forest Service to find ways to provide the required habitat while still harvesting timber. The then predominant 'norm' of short rotation clearcut forest management had caused the threat to the owl. So much late seral forest had already been “converted” that in addition to protecting what still remained, there was need to reestablish more; requiring a combination of continuous cover selection system harvest and extended rotations. Commercial thinning (CT) could provide at least some timber supply as well as speed the creation of structural biodiversity out of the homogeneous juvenile stands. Both commercial thinning and longer rotations had appealed to foresters since the 1940s; but the ready availability of first growth and an industry unready to log and use the smaller, mediocre quality logs had kept their actual use to a minimum.