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Sunday, April 28, 2013






Sunday, 9:00 AM.  50 degrees F, wind WSW, light with occasional stronger gusts.  The sky is cloudless but hazy, the barometer is down at 29.98 in. and the humidity is 80%.  It is a nice spring morning, the snow is melting fast and we may get some rain.  At this point the ground seems to be absorbing the snow melt and there is as yet no flooding of nearby streams.  The lower Chequamegon Bay at Ashland is still iced in and it is predicted to be a record late ice-out (since records were kept in 1900 or so).  It may be several weeks until the ice is off the Bay.
   I have calculated, as best as I can at this point, the age of the big white pine that went down a couple of weeks ago on 9th and Manypenny.  It is 36 inches in diameter at breast height (about 4' off the ground, where I would normally count annual growth rings rings) but the only saw cut at this time is at 20' trunk height, where I counted 86 distinct rings.  Adding roughly twenty additional years for the remaining twenty feet of trunk length, I estimate the age of the tree as something more than 106 years.
The house on the corner was built around the turn of the twentieth Century, so the tree was probably planted around then.  When the tree blew down I estimated its height at eighty feet.
   The tree grew rapidly during the first thirty or forty years of its life and then began to slow down, and there was very little growth in the latter years of its life.  There were early years when  its diameter increased as much as a half an inch. Of course growing conditions affect annual ring size as much or more than the age of the tree, and years with better or worse moisture and temperature conditions are quite obvious.  With a really good saw cut and lots of patience one can identify years of drought or other environmental stress by counting back from the outermost ring.  Conifer growth rings are easier to count than most hardwood trees as the water conducting cells that become the woody tissue are all large  empty cells called vessels.
   In a natural environment a white pine might live for hundreds of years, but in an urban setting many things can happen to shorten its life span.  Road, sewer and water line construction, root compaction, lack of water infiltration due to road and other hard surfaces, reflected heat, trunk damage due to being hit with lawn mowers and other equipment, improper power line pruning...all take their toll.
   I took a better look at the base of the tree where it snapped off at ground level, and although I didn't detect any soft rot, most of the base of the tree at the root flare was very punky, a dry rot that I could actually break apart with my fingers.  I dont know if there is a really good way to detect that kind of condition, except to do core borings of the heartwood, which can cause its own problems.  There is a device that has recently been developed that can determine the density of wood in a living tree that should give some indication of its soundness, but I have had no experience with it. 
   Ancient trees are an environmental and historical treasure, but they can be very dangerous to life and property, and need to be monitored closely and sometimes need, reluctantly, to be taken down.

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