Simply Science: Why are the leaves changing color already?

6:02 PM, Aug 16, 2012   |    comments
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MINNEAPOLIS - It's been a long summer with intense heat that started weeks early and didn't let up until just recently.  So it's no wonder why some trees could be a little confused.

It's only August but some trees are already transitioning to their fall colors. While a few of the trees may be turning because they think it's September, most of the colors appearing and leaves falling are a result of conservation.

"(Losing their leaves is) actually kind of a survival strategy for the tree to save water. By shedding some of it's leaf surface, it doesn't lose as much water off from the leaves, and it just conserves what it has," said Master Arborist Kent Honl.

This is especially the case for Birch and Cottonwood trees. But when it comes to Maples, look to the trunk. Is it flared or does it look like a telephone pole that is straight all the way to the ground?

The ones that go straight into the ground, often have girdling roots that circle around beneath the soil surface and constrict the sap flow in the tree," said Honl.

Low sap flow means lower moisture... so shedding leaves is again one way trees can protect themselves from drying out.

For most trees, fall color is still a month away. Several factors come in to play when determining the timing of peak fall color, including temperature and drought status. Typical peak season for Minnesota runs mid September though mid October.


































(Copyright 2012 by KARE. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)

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