Celebrate Monona’s Year of the Bike and Green Living month at the Aldo Leopold Nature Center with the next in our public lecture series on nature, climate, energy, and sustainability! Join special guest Maggie Grabow (PhD, MPH) from the University of Wisconsin’s Global Health Institute to learn about the environmental and human health benefits of bicycling. There are […]
Have you noticed that some trees retain their leaves?![]()
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In fall, deciduous trees and shrubs shed their leaves to conserve resources during the cold winter months. Trees shed their leaves by growing a layer of cells between the leaf stem and the tree branch that is called the abscission layer, which is a natural process of detachment that occurs with leaves and fruit. ![]()
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However, you might notice that some trees hold onto their dry, brown leaves throughout winter. This phenomenon is called 'marcescence' and it happens when the abscission layer is incomplete.![]()
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Typically, leaf marcescence is seen on some species of oak, beech, and hornbeam. It almost always occurs on young trees and on the sexually immature parts of older trees. Even large and mature trees have branches that stay in an immature state. Those branches are usually located low in the crown and close to the main stem. Over winter, the retained leaves may gradually wear out or, when spring arrives, they get pushed away by new growth.![]()
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There is no real consensus about the reason for this phenomenon. Some theories suggest that marcescence might be ecologically advantageous. For example, leaves that drop in the spring deliver organic material at a time when it is most needed by the tree. Also, the snow trapped in the retained leaves might provide extra moisture at the base of the tree when the snow melts. Others have hypothesized that persistent leaves might help protect buds and new twigs during winter from both frost and browsing animals.![]()
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What signs of late fall do you see? Visit us for a hike or take a walk around your neighborhood looking for cyclical events influenced by seasonal changes. ![]()
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Photo: Stephanie Briand, Aldo Leopold Nature Center![]()
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#PhenologyFriday #Marcescence #WIEnviroEd #NatureIsEverywhere #NatureIsForEveryone #EveryBodyOutside
