"Jack Schmidling" wrote in message

There were lots more that were not answered... like why do some very small
trees produce more sap than some (most) very large trees?

Why do some trees produce none?

The answers to these were not very satisfying.

I'm not an Arborist but I did sleep at a ......
Just a wild guess on the first question. Compared to their size the younger
trees need to grow a larger percentage each year to be able to establish
their own space in the forest. To do this requires more energy, thus more
sap. Like humans that grow up fast the first 18 years and then spend the
next 60 growing out around the edges slowly.

Mark R