Tuesday, February 22, 2011

The Science Behind Vented Tree Tubes: Air Flow Increases Stem Diameter

For me today is a day for feeling old.  Not only have I been working with tree tubes for nearly 22 years, I just learned that one of my best customers was born the year I graduated from high school; I had already been working at garden centers and as a freelance landscaper for 2 years before he was born, thinking about better ways of planting oak trees into the landscape.

But with age comes experience, and with experience comes - hopefully - wisdom.  One area in which the entire forestry community has more wisdom than we did 22 years ago is in tree tube design and function.

Back in the early days - the stone age - of tree tubes in the USA we all thought that a treeshelter should be an air-tight chamber; unventilated with the base pushed into the soil.  We all dreaded the idea of a "chimney effect" of air movement in the tube, fearing that it would overheat or over-dry the seedling inside.

How wrong we were!  Nowadays there is a large and growing body of research that shows that vented tree tubes 1) increase overall growth and 2) result in a better distribution of growth - you get a larger tree with similar allocation of growth between height, stem diameter and roots as an un-tubed tree.

Here is a great page summarizing the current body of research on vented tree tubes.

With every passing year we learn more about how to use tree technology to produce trees with a growth allocation that more closely approximates that of open grown trees.  Of course there is one BIG difference between a tree grown in a Wilson Tree Tube by Tubex and an open grown tree:  One is still alive, and one was eaten by deer!

So while I've been at this tree tube thing for a long time, it's exciting to see how far we've come, and to think about how much there is still to learn.

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