Ash borer took out 99% of ash trees here in < 5 years. It was astonishing how quickly it happened.
Only good news is that, similar to Asian Ash species, a small number of ash trees survived by quickly activating immune defenses to smother the beetle larvae. The genome(s) of these trees are being studied to determine why they are able to recognize the infection quickly, while the others are seemingly oblivious to the fact they’re being attacked. The majority of these are blue ash, but there are isolated cases in every sub-species.
One of these “survivor” ash trees is growing down by booze creek. It is a white ash, and is completely unscathed while all surrounding ash trees died rapidly between 2014-2016.
Unfortunately, there will be significant consequences to the ecosystem regardless of if/when the surviving ash trees re-populate, because all the dead ash trees had fallen to the ground by 2018, opening up much of the forest floor to sunlight and seedling germination. These areas are now dominated by boxelder and tulip poplar, which is not the usual composition for early stages of forest succession.
I think PDO is useful if it has been very sustained like what we're seeing now. It's a symptom of a very persistent pattern. Since persistence is often the way to go in long range forecasting it's useful in that way.