Autumn colors important for trees
PHOENIX - This time of year, broad-leaf trees throughout the northern hemisphere are turning their characteristic yellows, oranges, and reds. The pigments protect the leaves as they produce a final batch of nutrients that will be stored in the trees’ roots over winter.
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Now, a researcher with the McDowell Mountain Regional Park near Phoenix suggests that the intensity of those colors may have as much to do with the soil a tree grows in as with the species of tree itself.
Researcher Emily Habinck surveyed a section of forest in a nature preserve outside of Charlotte, N.C., while a grad student at the University of North Carolina. She found that in places where the soil was low in nitrogen and other nutrients, sweet-gum and red maples produced large amounts of a red pigment compared with trees in more nutrient-rich areas. The mechanism apparently allows the leaves to survive longer into the fall so they can deliver the right amount of nutrients to tree roots.
The work bolsters results from a study in 2003 that hinted at how important the production of red pigment can be. Montana State University’s William Hoch used genetic techniques to block red-pigment production in red-leafed plants. When he did, the leaves succumbed far faster to the weaker fall sunlight and so delivered less nutrients to plant roots. The results of Ms. Habinck’s work are being presented at this week’s meeting of the American Geological Society in Denver. (Christian Science Monitor)
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