Enjoying Nature’s Paint Brush

ENJOYING NATURE’S PAINT BRUSH

Wednesday, October 10, 2007 (Napanee Beaver)

Friday, October 12, 2007 (Picton Gazette)

Planning a bus tour to take in the fall colour can be a bit tricky, with a lot of guess work involved in choosing a date. However, dates didn’t much matter this fall since conditions weren’t optimum for producing the dazzling colours that we look forward to every autumn at this time. The record drought this year put a lot of stress on all except those trees that had the good fortunate to find water somewhere down beneath the parched surface. It was too dry, and it was far too hot to bring on the colours.

Our tour last week took us to Jones Falls, a small community along the famous Rideau Canal that seems to excel every fall in producing an outstanding parade of colours. According to residents there, that area was even drier this summer than Prince Edward County and outlying areas, and it reflected in the lack of colour along some of my favourite roads. In these situations, we always know we can fall back on Newboro’s famous Kilborn’s store and Westport’s Village Green as backups!

Fall colour is most intense during years in which a relatively dry sunshiny summer is followed by a rainy period in late August or early September, and then by an autumn with moderately low night temperatures and bright crisp days. With few exceptions, we had neither sufficient rainfall, nor the cool nights. Fall colour was doomed to failure early on in the season. Contrary to popular belief, it is not frost that brings on the colour; indeed, a killing frost can turn leaves a dull, dirty brown, causing them to cling to the trees well into winter. Cool temperatures within reason, however, will encourage the formation of the red pigments. All we need to enjoy this spectacular fall show is a bright sunshiny day and that is when we will see the maples and sumacs in an absolute riot of colour.

Leaf colour is caused by the presence of chemicals called pigments. During spring and summer, leaves are green because chlorophyll, which reflects green light, is present in large quantities. Other pigments are there too, but their effects are masked by chlorophyll. But all this colour we see is sheer waste, in technical terms anyway. As the days become shorterand the tree begins to tire, sap circulation is sealed off. Production of chlorophyll ceases and disintegrates. The reds and purples appear when the sun has oxidized the sugars and acids abandoned in the leaves.

If you want to be one up, you can refer to these pigments as anthocyanins. They are responsible for the variety of hues from our most brilliant scarlets through a variety of reds, subdued lavenders, purples to deep blue. We are more familiar with these anthocyanins in other forms – apples, violets, grapes, blueberries and beets. These pigments tend to develop in some of our trees during the autumn and it is our maples that put on the best showing. Because pigments are many-hued in different species and since yellow pigments remain after the green pigments have gone, we end up with an explosion of colour in our trees. The red pigments are in the upper surface of the leaf and the yellows throughout the leaf result in all kinds of colour combinations. Some families of trees – the poplar comes to mind – are incapable of producing any of these red pigments, even in the faintest of hues. Thus we are offered only yellow and gold from this species.

The production of the anthocyanins, and therefore the intensity of the reds, is affected by many things – weather during summer and fall, the amount of available light, air and soil temperature, nitrogen supply and soil moisture. Even single leaves may not be evenly coloured if part of the leaf has been shaded by another.

Many of us tend to take the annual fall colour for granted. Not every country, or even every part of North America can boast the complimentary stage show we are treated to each fall. In South America, for example, this colour does not occur – except for a small region in southern Chile. While parts of Europe, China and Japan can also boast the changing colours, it is here, in eastern North America, where the presentation is the most spectacular, for we have the tree species that produce the bright colours that are lacking in other parts of the world.

It is this phantasmagoria of hues that compels people to head off each fall for the annual colour tour, whether by car or by bus. We met several tour buses that were doing the same as we were – escorting people around to savour an annual spectacle that has made this part of the world famous.