Dear Dr. Dietze and Dr. Moorcroft,

I was very sorry to see that I have only just found your research as referenced in the subject, since I have been searching for such excellent information as you studied and reported on, for several years.  Your paper is probably the best, most convincing and comprehensive account of the damage being done to forests from air pollution I have come across.
I wonder if you have been able to notice or record, or continue to study, that the decline and premature mortality from air pollution that you documented using the Forest Service data through 2005, has been rapidly accelerating since that time. I am not a scientist myself, but as a life-long gardener in New Jersey I noticed that by 2008, every single tree began exhibiting evidence of decline, and not healthy growth - and that includes all species, in all habitat circumstances, of all ages...which, I subsequently discovered, is mirrored in many places around the world.
Even more importantly, and increasingly, by the end of the growing season, it is difficult to impossible to find a leaf on any plant that does not have symptoms of ozone exposure, whether it is an aquatic plant in a pond, or a tropical decorative ornamental in a pot, or tree being watered and fed in a commercial nursery.  The only common denominator shared by this diverse vegetation is the atmosphere - not precipitation, or temperature increase, or acid soils.
Another interesting question, is about nitrogen deposition which you note leads initially to faster growth, but ultimately is harmful.  I wonder if we have crossed a point where that is damaging forests around the world, particularly because there are some lichens that appear to thrive in high nitrogen environments, that are by all indications, spreading at a truly astonishing rate in many diverse locations.
I was particularly intrigued by one passage in your paper, as follows:

"Our estimates of ozone impacts are likely underestimated for three reasons. First, ozone concentrations were only observed in about half the counties and thus had to be inferred in the remaining areas. This is problematic because ozone is relatively short lived in the atmosphere, showing a finer scale spatial pattern than NO3- or SO42-, and thus interpolation errors are likely to be higher.  Second, our interpolation scheme that sought to account for production, via population density, did not account for the dominant wind directions of transport nor differences in ozone destruction due to reactions with hydrocarbon compounds.  Third, we used the peak 8-hr ozone concentrations as our ozone estimate as this is the basis of current health standards and regulation. This is potentially problematic because plants, unlike animals, are more sensitive to cumulative exposure rather than peak exposure. Still, peak and cumulative concentrations are highly correlated (figure not shown), and we expect our conclusions regarding the effects of ozone to be qualitatively robust." 
It seems to be well-accepted in the scientific community that net primary production of biomass is reduced by ozone by approximately 20 - 25%, and that 40 ppb is the threshold at which plants are damaged - a background level that now essentially prevails everywhere in the world.  So I believe your conclusion is vitally important - it is the cumulative damage of persistent low-level exposure that is most significant - and over time far surpasses the reduction in growth for annual plants.
Add to that increased vulnerability to biotic attacks from insects, disease and fungus - which have become epidemics everywhere you care to look - and it would seem that we are on the verge of a world without trees.

My question to both of you after this rather long explanation is, at what point will the scientific community, those who KNOW about this existential threat to humanity and the rest of the biosphere, feel that the evidence is compelling enough to step forward and say so?  Do they plan on waiting until there is nothing but dead dry sticks consumed by wildfires?

I mean these questions most sincerely...and I thank you for your attention.  Any reply will be greatly appreciated.  In fact, I would be delighted to talk to either of you, if you care to call, 908-xxx-xxxx.  I don't think there is any way to exaggerate how important this is.  Many species, if not all, are going to go extinct from climate change.  But the loss of forests will accelerate the process in ways that aren't even being calculated in climate modeling.

Gail Zawacki

The New York Times ran an elegy for the ash tree which finally allowed some recognition that the emerald ash borer is nothing new, and has only recently become an epidemic - but still not a hint of curiosity as to why that should be:

"Back in 2002, when the borers were first discovered in North America — in Windsor, Ontario — experts thought it might be possible to eradicate them. But after about six months, researchers realized that the insects had been here for years, probably decades, and had already started spreading across the upper Midwest....“Ninety-nine percent of the ashes in North America are probably going to die,” said Andrew M. Liebhold, a research entomologist with the United States Forest Service."

The cold winter did nothing to slow them down.  It doesn't explain why the ash are dying around my house and all over New Jersey, where the beetle has yet to be found despite extensive efforts to find them.

And let's not forget the beetle in California that is spreading a fungus which is killing hundreds of different species:

"If we can't control them," Eskalen said, "they are going to wipe out all our trees."
Such pests typically feast on a small group of plants. But this one doesn't seem to discriminate. 
When Eskalen and his colleagues surveyed the 335 species at the Huntington and the Arboretum, in Arcadia, they found the beetle had attacked 207 of them and 54% of these victims were infected with fungus. Nearly two dozen of the trees were being used as reproductive hosts — places where the beetles can raise their brood. 
The consequences of a wide-ranging infestation could be enormous. Common city trees, such as American sweetgum and maple, would become public branch-dropping hazards. Native trees such as the California sycamore and the coast live oak have started to succumb, creating a fire risk in the form of dead, dry tinder. Avocados and other crops could face huge financial losses.
Oh gee really?  All species at risk - up to 286 now?  Branch-dropping hazards?  Wildfire risk? Crop losses?  Duh?

Wouldn't you think these "experts" would add things up and realize that we are in a new world shaped by an unprecedented force?  I expect the researchers who have discovered that plants can detect the chewing of insects will not have enough time to figure out whether ozone impairs their innate defenses.

Meanwhile, in a move that can only be described as insane, Worcester is chopping down trees to deter the Asian longhorn beetle.  The video in this story is mind-boggling.

Meanwhile, humans continue to maul the remnants of other species remaining on earth.  The pesticides killing bees, it turns out, are working up the food chain and killing birds, and extinctions are proceeding faster than ever before.  Fungus is killing not only trees and bats, but now snakes as well, and jellyfish will soon rule the oceans.  Quelle surprise!

Oh but WAIT!  If only we hadn't, oh, started agriculture or...become capitalists or...been more conscious and spiritual, and peaceful and egalitarian - like indigenous people! - we could have averted this mass extinction event...right?  Wrong.  We.  Could.  NOT.