When fire mimicry treatments began in 2006 on the oaks at Hearst Castle I had identified two control oaks, trees there were not to be treated in order to compare their response with the treated oaks. The yearly photos indicate that, indeed, these two oaks have shown no clear improvement in canopy density, compared to the treated oaks.
In 2012 a California State Park employee did a fire mimicry treatment on one of the two control oaks by mistake. The results were noticeable. The photos below show results for both the control oak that was accidentally treated, and the other control oak that has remained untreated. Note that the treated oak has shown noticeable improvement in canopy health in just one year! Note also that I have used the photos from Jan. 2011 rather than Jan. 2012. The canopy damage caused by the windstorm in Dec. 2011 would have biased the results.