Dear Novice:

Assuming you are correct in that the trees are pines and not spruce, fir,
larch, redwood, etc., there is a simple explanation for this sort of
observation. Pines are (almost all) shade intolerant: That means they do not
send new growth into areas where the intensity of sunlight is too low to
"justify the investment" in new tissue.

Additionally, some species (such as white pine) are much aggressive
self-pruners than others (e.g. the spruces). Self-pruning is the term we use
for when a tree sheds branches that have died, and in the majority these
branches died due to the low-intensity of sunlight on them as the
surrounding trees grow and shade each other. Trees are much more
compartmentalized as organisms than are animals, and if a particular branch
does respires more energy than it fixes via photosynthesis, the tree 'opts'
to kill and often shed it.

Hope this helps!
ML
--
Mike LaMana, MS, CTE
Consulting Forester & Arborist
Heartwood Consulting Services, LLC
Toms River, NJ
www.HeartwoodConsulting.net



"Novice" wrote in message
om...
Hi all, I was driving along the highway the other day and noticed that
some tall pine trees have lower branches and others don't. I would
suggest the reason for this is that in some groves of trees the sun
manages to reach the lower branches either because the grove has a
plain on one of its edges or because the upper branches are sparse
enough to allow a sufficient amount of sunlight through to allow the
lower branches to photosynthesize.

One other explanation would be that there are foresters who
intentionally go through and remove the lower growth from the trees so
that the trees don't waste undue energy on maintaining the lower
branches which aren't as capable of producing energy. Would another
possible explanation be simply a difference in the species of the
tree? For instance some trees are just better at maintaining lower
branches with minimal exposure to sunlight.

Thanks for any suggestions for why this phenomenon occurs,
Novice