Autumn is the time when leaves fall from the trees. It may seem like a gradual process but often, leaf loss can be sudden; especially after an overnight frost or during gale force winds.
As summer winds down, deciduous trees produce cells at the base of each leaf stem called the abscission layer. This layer weakens the attachment of the leaf to its tree while blocking nutrients from nourishing the leaf causing its chlorophyll to degrade. Since chlorophyll is green, other colours such as red or yellow can then become more prominent.
Frost can accelerate the process by further weakening the abscission layer so that leaves are very loosely attached and will fall at a slight breeze. Early frosts are the enemy of glorious fall colours as they can send leaves to the ground before colours can develop.
This video was taken in Raymore Park on the morning of November 12, 2013 and illustrates how quickly leaves can fall from trees when conditions are right. There had been an overnight temperature of -4°C the night before, severely weakening abscission layers and even the gentlest breeze was enough to send large numbers of leaves to the ground.
The difference between early fall and early winter is illustrated in these two photographs; no prizes for guessing which one was taken today. The park literally teems with billions of creatures (mainly insects) at the end of summer while on a day like today wildlife seems strangely absent, even though a fair number of animals stick around by hibernating or finding winter food.
In addition to seasonal differences, the two photographs are about 8 years apart which can be seen by the growth of the bushes on the left.
29 September 2004.
Looking at today’s image, it’s hard to imagine anything surviving but in less than three months, the park will begin to stir as the sun’s warmth returns.
6 January 2013.
Off topic rant/ The apartment building in the photographs is one of a pair of notorious carbuncles built on Weston Road in the 1970s. These have been the subject of many a city compliance order and have become in some ways too big to fail. The landlord was recently given $1.8 million of taxpayers’ money to fix up the place. Hopefully the gift of a GO Station moving onto the doorstep should spare the taxpayer from further assistance to this alleged capitalist enterprise. /rant