Why Do Trees Lose Their Leaves?

Snowcreek (11/2/15) Alicia Vennos

It’s survival not just of the fittest, but of the wisest.

Deciduous trees drop their leaves in order to survive.  As days grow shorter and colder, deciduous trees shut down veins and capillaries (that carry water and nutrients) with a barrier of cells that form at the leaf’s stem.

Called “abscission” cells, the barrier prevents the leaf from being nourished. Eventually, like scissors, the abscission cells close the connection between leaf and branch and the leaf falls.

Had the leaves remained on branches, the leaves would have continued to drink and, once temperatures drop to freezing, the water in the tree’s veins would freeze, killing the tree.

Further, with leaves fallen, bare branches are able to carry what little snow collects on them, protecting them from being broken under the weight of the snow. So, by cutting off their food supply (leaves), deciduous trees survive winter.

The fallen leaves continue to benefit the tree through winter, spring and summer by creating a humus on the forest floor that insulates roots from winter cold and summer heat, collects dew and rainfall, and decomposes to enrich the soil and nurture life.

It’s a cycle of survival, planned wisely.

3 replies
  1. Maribeth Seaton-Murray says:

    Thank you very much for the special report on why trees lose their leaves. We appreciate all the care and time you and all the website’s color spotters spend on keeping us informed about the glories of autumn in California. The new format is lovely! We are always happy to share your website with folks who are unaware that “Dude, autumn happens here too.” Peace.

      • Maribeth Seaton-Murray says:

        It’s a pleasure and a blessing! Nature needs all the love she can get (now more than ever) and you provide a marvelous way to enlighten folks to her autumn beauty. Your website is a wonderful community in which to hang out 🙂

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