Date: Monday, April 15, 2002 10:01 AM


Yesterday (April 14) I had the privilege of driving from Marquette, Michigan on the shore of Lake Superior to the Straights of Mackinaw where the two peninsulas of Michigan nearly touch. I took a more northerly route than the one I described last autumn running somewhat south of Lake Superior until cutting south to the Straights. (M-28 to M-123 to I-75 for those keeping score.) I drive this route 2-4 times per year. Here are some problems I observed.

The spruce and fir in the Seney National Wildlife Area visible from the highway for a stretch of about thirty miles are now experiencing widespread dieback. In fact from Marquette to Mackinaw, a distance of over 160 miles, nearly every wetland with spruce and fir and about 1/4 the northern white cedar "swamps" are either dead or brown and/or defoliated. But of course this is also happening "downstate."

The sort of spider branches mentioned in earlier letters are now to be found as far north as Negaunee, hundreds of miles from any urban area, all along the roadway. In many places individual hardwood trees are falling over, or the tops appear ragged with large dead branches, especially oaks on dry ridges. Willow and poplar are also dying in the same ways around Marquette that they are around Traverse City. Oaks are taking a heavy hit from Detroit to the northern UP, a distance of about 500 miles encompassing many thousands if not millions of acres. I see few healthy oak woods anywhere I travel in our state.

Now that what sufficed for winter has passed along the highways and biways where tree death has occurred crews are busy cutting up and carting away dead trees making the roads safer but obscuring the true extent of tree death.


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From: Gerry Hawkes <
Date: Wednesday, April 17, 2002 8:46 AM

Jeff -

What you describe has many similarities to what I am observing here in Vermont and neighboring New Hampshire and upstate New York.

In particular, virtually every tree species in and around wetlands or just in wet depressions is dying or dead. Joe said he thought it was most likely due to the accumulation of toxins carried by the runoff into these low areas. This explanation makes sense to me.

- Gerry

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-----Original Message-----
To: <>
Date: Tuesday, May 14, 2002 11:13 PM
Subject: What about Road Salt??

Mr. Hawkes--

Upon reading these repeated reports of dying trees within the Northern Wisconsin and Upper Michigan areas, I began paying a bit more attention to the roadside trees and the woods while working in the field.  And frankly, after doing a bit of research on the subject, I think the assertions posted on your page connecting the dying trees to air pollution are a BIG stretch of the imagination when other sources are far more probable.  

I strongly suggest you and those who contribute to your page review these links that discuss the impact of road deicing has on roadside trees.  The impact is NOT localized to the trees sprayed with aerosol containing high levels of salt.  Road salt enters the groundwater, impacting local lakes, destroying soil along roadways and killing trees up to 200 meters from the roadside.

Given the area I live (Vilas County where the UW Madison Study was performed) the variation in tree health along side the road is observably correlated to the amount of salting are done on these roads during the winter.  Hwy 45 is heavily traveled and therefore heavily salted roadway in the winter.  The dead trees along this road are numerous.  Wetlands along this roadway are filled with dead spruce.  However, along Hwy 17, where there is significantly less salting during the winter, the road side trees are healthier-- the spruce wetlands still have living spruce in them.  

I think it is foolish for your contributors to pretend to perform a forest assessment while driving along a roadway -- an area that is obviously affected by activities such as deicing and localized air pollution.  It is also presumptuous to try and connect all dying roadside trees to air pollution given the body of knowledge about other likely causes of tree death along roadsides.  There are many issues that affect forest health that are independent of air quality. I strongly suggest your contributors to educate themselves in the subject before reporting on forest conditions and then drawing possibly erroneous conclusions. 

The following are some good resources to start with--  

If one wishes to fix the problem, you need to understand what the problem is first, don't you think?


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-----Original Message-----
From: Gerry Hawkes <>
Date: Wednesday, May 15, 2002 7:27 AM
Subject: Re: What about Road Salt??

To cg -  

Please give what you are saying a bit more thought.   

Yes, road salt is very damaging to roadside and nearby trees.  The effect of road salt is often one of several reasons roadside trees decline and die at a faster rate than forest trees.  However there is widespread forest decline and death occurring in areas far removed from highways.  Some of the worst forest death is occurring in high elevation forests, far away and above any highways and effects of deicing salt.  

While there are many causes for tree death, road salt being significant and serious, air pollution is the only logical explanation for widespread decline in the health and vigor of trees and forests over broad geographic regions, species mixes and elevations.  

- Gerry




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