They stand upright. They breathe. Like us humans, they are made of mostly water. What are they?

Trees.

Early in elementary school, we are taught about our dependence on our forest friends for every breath we take. Every autumn, as leaves change, fall, wither, scatter and disappear, we watch with wonder. We relate. Even our anatomy resonates: branches fill our lungs, our trunks support our limbs, our nerves have roots, and a stem connects our brain and spinal cord. The tree-human relationship is special and always has been.

So, imagine how scientists must have scratched their heads when the trees in Biosphere 2, a research facility in Arizona constructed to mimic and study Earth systems, began falling over before they reached full maturation.  Supposedly, every natural condition necessary for the healthy growth of trees had been recreated inside Biosphere 2. Why were the trees so fragile? 

The answer to this question is considered one of the most important discoveries of the Biosphere 2 project. Eventually, scientists uncovered the essential, missing ingredient for the healthy maturation of trees: wind.

A lack of wind inside Biosphere 2 changed the composition of wood in the trees. Without sufficient wind, less “stress wood,” or wood with a higher cellulose content, developed in their trunks.  Without enough stress wood, these trees could not position themselves for proper sun absorption. They grew fast, but the wood was not solid enough to support this growth, so they fell over prematurely.

Wind. Without the stress that wind creates, trees look like they are flourishing. They grow tall. They even grow rapidly. But, beneath that good-looking bark lies yet another tree-human connection: without wind, we collapse quickly too.