Very old trees - inconsistent taps

[berkshires]

Someone recently had a post on this subject buried in a long thread, but I was curious to get more eyeballs on the subject.

I have some very old trees - like probably four feet wide or more, some are hollow. I've found that I get very inconsistent results from tapping them. Some taps seem to produce nothing or next to nothing, while others do well. I never hit stained wood, that I can tell. These trees have never been tapped (that I know of, within the last 50 years). They just don't seem to produce sap so well from some areas.

Have any of you encountered this?

I wonder if maples, as they reach the end of their life, just don't have sap running through the whole tree. Could there be substantial areas that are not stained, but just don't do anything?

I also found this post from Dr Tim: http://mapletrader.com/community/sho...roducing-trees
The only thing here that seems pertinent to different volumes of sap from different parts of the tree was this:

4. Areas with little or no growth due to slow growth occurring in some areas, but none in others.

Dr Tim, have y'all ever studied this? If, as you say in the above, there are areas with no growth, does no growth = no sap? Or does it have to do with what that wood is supposed to be feeding? If there's a big branch it's feeding, and that branch is dying, does that mean no sap?

GO

[slammer3364]

I had that.I just did not tap the trees that did not produce. I have only two hard maples on 90 taps and they are old trees,some big old reds are the ones I had problems with