Why Do Leaves Turn Red?


As the days grow shorter here in the Northern Hemisphere, one of the last gasps of fall is the rush of color in the surrounding woods. The vivid red-leafed trees are always my favorite, jumping out of the crowd like Halloween candy to a five year old. However, the red color may indicate that the tree is rooted in difficult soil.

Emily M. Habinck, a former University of North Carolina graduate student, found that in places where the soil was relatively low in nitrogen and other essential elements, trees produced more red pigments known as anthocyanins. This finding supports a hypothesis by plant physiologist William Hoch of Montana State University, Bozeman, who argues that the increase in anthocyanin production in red-leafed plants, is the trees defense against fall sunlight. The additional protection allows the trees more time to gain valuable nutrients, offsetting the energetic cost of producing the pigment.

Why is this a TreeHugger noticeable event (besides the tree bit)? Not only is it a beautiful example of form following function, but from time to time we need to step back and see the forest for the trees. ::The Geological Society of America