Fall is in the air! Autumn brings brisk morning temperatures, beautiful golden evenings and cascading leaves; perhaps that’s why we call it “fall.”
We all know that fall leaf colours turn the landscape from a green forest canopy to one of yellow, orange and red. But why do the leaves change colour at this time of year?
Why do leaves change colour?
Every fall, many leaves begin to change colour from vibrant green to eye-catching purple, red, orange and yellow. This change can be attributed to two factors: sunlight and weather.
Sunlight
During spring and summer, sunlight is abundant. Deciduous trees produce chlorophyll, a green pigment that helps convert sunlight into food.
As the days get shorter leading into fall, trees get less sun and therefore produce less chlorophyll. This causes the green colour to fade and other coloured pigments in the leaves to surface. These pigments help protect the leaves from damage.
Weather
The brightest fall colours often follow a stretch of warm, sunny days and cool nights. Cool temperatures boost the production of anthocyanins, the pigment that produces red and purple, while sunny days boost the overall pigment concentration, resulting in brighter colours.
However, extreme temperatures and prolonged cloud cover can dull the colours and lead to early leaf drop.
The spectrum of fall colours
In the National Capital Region, there are more than 70 species of trees and shrubs, including 50 distinct deciduous species.
Here are the leaf colours you may see. Each deciduous tree species has its own distinct shade of fall colours:
- Yellow and orange: Maples, birches and poplars showcase vibrant yellow and orange leaves.
- Red: Look for red hues in sugar maples, staghorn sumacs, red oaks and dogwoods.
- Purple: Although less common, rich purple tones can be found in certain maples and sumacs.
Unique among conifers, the tamarack (Larix laricina) turns a brilliant gold in late fall before shedding its needles in October and November. You can easily find this tree at the Mer Bleue boardwalk, as it is often found in boggy areas. The Tamarack tree provides great photographic opportunities once deciduous trees have shed their leaves.
Tips to enjoy the fall colours
The stunning landscape brings many visitors to Ottawa-Gatineau to enjoy this seasonal phenomenon. You can experience the colours this fall in the National Capital Region’s many parks and urban lands.
Gatineau Park is a local favourite. However, given its popularity, this area often reaches visitor capacity. To see the same colours and have a better experience, follow these three tips for an enjoyable day in Gatineau Park.
