This is a two parter, first I Have a client with a 100' tulip poplar approx. 4'"DBH" with a large cavity at the base of the tree.The tree sets about 25' away from the house with the cavity facing away towards the east. the cavity is about 6' high and 3' across the bottom.I have not probed to see how far decay has set in, but just from poking around it appears to go into the tree at least 2'. She wants a written assesment of the tree along with my recommendations. Ihave been an Arborist for 12 years but have had little experience in cavity work. The thickness of the callus tissue around the cavity seems to be at least 4-5" thick, my questions are:1. how can I determine if the tree is safe(it has been there for quite some time) or is it as much of a hazard as it appears? 2.will carving outand removing the decayed tissue help or weaken the tree? any advice or reference would be greatly appreciated. "Green leaves for everyone"!!!!

Reply to post by Jeff, on October 26, 1999 at 22:41:10:

Admit your out of you depth, and offer to act as primary contractor and have the firms you sub out to show you how to do it.

Most proffesionals I have met are more then happy to pass on their knowledge. But then this market is still pretty fragmented.

Reply to post by Jeff, on October 26, 1999 at 22:41:10:

No tree bigger than a person is safe. Never use that word, without modifiers, like "reasonably" or "relatively". Better to write about safe useful life expectance, or do not park car under this tree in a wind over 45 mph, or what ever you come up with.
It seems accepted that taking decay products out of a rotting tree neither helps nor hinders. My take: if you remove stuff, try not to infringe on live wood. Also, removing decay products might very likely make the niche less desireable for fungi, by cutting down on moisture.

Reply to post by Jeff, on October 26, 1999 at 22:41:10:

there is an accepted guideline , backed by empirical research, that if less than 2/3 of the diameter of the tree is decayed then the tree may still be considered "safe". this guide should be be balanced by what you observe in the tree yourself e.g. lean of tree , prevailing winds, structure of canopy, etc etc

Reply to post by mark lutherborrow, on October 26, 1999 at 22:41:10:

I'd still be quite careful about the word safe, even with the 2/3 guideline. Mattheck uses 2/3 (t/R < .3) as does the Bartlett recommendation. But they are limited by the conditions when they apply- wind speeds, soil conditions, targets, etc.

So, as Peter suggested, avoid the word 'safe', and substitute something a little less certain, or accompany the statement with one that says "...no tree is entirely without risk..."

Reply to post by Jeff, on October 26, 1999 at 22:41:10:

ever heard of the SIA Method?
It is commonly used among consultants in middle europe.
with four sheets an inclinometer (measuring the tree´s height and a calliper)you can
determine the residual wall atree needs in a gale of wind force 12.
In thsi method the triangle of statics is included. TZree safety makes oinly sense if you know
the load which affects the tree, but of course material properties and the load bearing geometry of the stem
plays a role as well. All these factors are included in the SIA Method. SIA stands for Statics integrated Assessment.
Questions? Ask me.

Reply to post by EBrudi, on October 26, 1999 at 22:41:10:

Hello Mr. Brudi and others,
I read your thoughts in the AREA Forum in the Journal of Arboriculture, Vol. 27, No. 2, March 2001, regarding SIA, and as the City Arborists for the City of Bath, Maine, I would be very interested in learning more about this assessment technique. My biggest problem with most hazard assessment, is the necessity to compromise the bark and woody tissue of the tree in question. I would greatly appreciate a step by step instruction on the use of this technique. My contact information is:

Thomas C. Hoerth
City Arborist, City of Bath
1 Oak Grove Ave.
Bath, Maine 04530-1926
207-443-4088 (h)
207-443-8345 (w)
207-751-7677 (cell)
thoerth@clinic.net

I look froward to hearing from you. Sincerely, Tom Hoerth