Unseasonably warm weather in parts of Canada may deprive some areas of one of their trademark natural attractions — rich fall colours.
A forestry expert says the vivid red leaves that draw crowds of tourists to areas of Ontario and parts of Quebec are triggered by bright sunshine combined with cold temperatures.
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Sean Thomas, a professor of forest ecology at the University of Toronto, says trees start breaking down the chlorophyll in their leaves in the fall in order to draw out nutrients such as nitrogen and store them over the winter.
He says chlorophyll is what gives leaves their green colour, so as it is broken down, other pigments such yellow and orange are revealed.
Thomas says that process can produce other chemicals that damage plant tissues if exposed to UV radiation.
To protect leaves from UV rays, Thomas says red pigments – a trademark of sugar maple trees, among others – emerge as a type of “leaf sunscreen.”