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Fall 2011

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

October 11, 2011

Foliage map: Autumn’s showy march to the sea

Although our nights are getting longer, Washington's trees are still mostly green. People who want to see fall color must drive north or into the mountains. The cooler temperatures there have triggered deciduous trees to stop replacing chlorophyll in their leaves. When the chlorophyll breaks down, weaker yellow pigments become visible. Red pigments are produced in some tree leaves, setting visual fire to the forest.

Peak dates for fall color are determined by a combination of latitude, elevation, the cooling effects of rainfall and proximity to the ocean.

A maple in the city changes color.