I don't pretend to have scientific, measureable proof that trees have souls.  All I have is a feeling and normally feelings are NOT enough for me.  But, in the case of souls, I don't believe we would have the abiulity to measure their existence even if they did exist.  (See the His Dark Materials trilogy).  I sometimes get the same feeling from trees that I get from other humans--a rising up in me that reaches out across the void to another being.

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