The importance of being deciduous

I started this post weeks ago as my seven-month farm apprenticeship was coming to a close. Luckily it's still fall, so it hasn't taken me so long to post this that it's irrelevant. I hope you enjoy, and I look forward to seeing friends and family this week for Thanksgiving! 

The study of Biology is the study of survival. And for survival, there must be smart resource allocation, reproductive strategies that work, and trade-offs.

The chilly, crisp air and crunchy leaves that both suddenly appeared in full force this week have gotten me thinking a lot about tree survival. The tricks of deciduous trees are famous. Each year, New England boasts the beauty of its trees as the leaves turn from green to red, purple, gold, and yellow. Tourists and residents alike, with cameras in hand, praise the ever-changing canvas of colorful leaves. And each year, as the colors change, the leaves begin to fall.

Does it make sense for a tree to lose its leaves, only to grow new ones months later? Sure, if it means that it will survive another year and reproduce. Leaf-drop happens for a number of different reasons, but it's all to protect the tree from the dangers of having to deal with winter.

Now that it's fall again, the crunchy, dried-out leaves on the ground have reminded me of a research article that came out a couple years ago. The research found that ethylene gas (the same gas that ripens bananas, etc.) triggers cells to form between the leaf and stem. These cells are called "abscission cells," and actually work to separate the leaf from the stem, effectively pushing it off the tree. In other words, the tree has a very active role in making itself leaf-less. Contrary to popular belief, it doesn't just happen on a blustery day.

Here's a link to a summary of the research in an article on NPR, from 2009.