Why leaves change colour in autumn
The vivid, often simple colors on the outside are the products of the complex chemistry of growth inside a leaf. Take the yellows and oranges, the dominant colors of aspen, ash, birch and some oaks, these colors come from compounds called carotenoids (also responsible for the color of carrots) which are present in the leaf during the growing season.
The green chlorophyll, the workhorse of photosynthesis, dominates and covers up those carotenoids in summer. As the days grow shorter and the temperatures cool, chlorophyll degrades and goes from green to colorless, allowing the oranges and the yellows to show up.
Trees with gorgeous scarlet, crimson, and ruby fall leaves have another reason for their colour. Red pigments are not present in the leaf during summer. Trees that turn red produce this pigment, called anthocyanin, in the autumn. These pigments play a key role in readying the tree for the next spring.
Researchers discovered that anthocyanins act as a sunscreen, protecting leaves from bright seasonal light when it is cold outside. Other researchers have discovered that the sun screening effect protects leaves from too much light, which can interfere with late-season transport of nutrients from the leaf back to the twigs, something trees do as a conservation mechanism. Learn more at https://www.farmersalmanac.com/chemistry-fall-color-19160
Climate change threatens city water source
Warmer temperatures this year had a lasting effect on the glacier that feeds Edmonton’s water supply.
The Saskatchewan Glacier terminus saw 10 metres of thinning this year, said Brian Menounos, Canada Research Chair in glacier change. It is also the glacier that feeds the North Saskatchewan River, Edmonton’s sole source of drinking water.
Matthew Chernos, a Calgary-based hydrologist and consultant, said the high alpine glaciers feeding Alberta’s river systems act as natural reservoirs. While the North Saskatchewan River is mostly made up of rainwater and snow melt by the time it reaches Edmonton, glacier melt is a big part of the river flow in July and August, when the glacier’s winter snowpack has melted away
The scientists were quick to note that fading glaciers also threaten sensitive aquatic ecosystems that rely on cooler water to stay healthy, and the irrigation demands of the agriculture industry. Read more at https://edmontonjournal.com/news/local-news/bad-year-for-the-glaciers-climate-change-threatens-glacier-behind-edmontons-water-source
This deer hide used to make buckskin leather
White-tailed deer are an integral part of a healthy Albertan ecosystem, feeding on plants and serving as prey for many species. They get their name from their tail which has a white underside. When alarmed, they hold their tail upright, exposing the white, as they bound away.
In Alberta, the rut, or mating season, occurs in November. Males spar with rivals, battling each other with their antlers. Fawns are born in early June. Does hide their fawn in tall grass or shrubs when they are first born, to keep them safe from predators. The doe returns every few hours to feed and move the fawn.
Deer are notorious for foraging continuously along the same pathway, so deer trails are well worn and easy to spot. Deer have scent glands between the two parts of their hooves, and on their legs. These scent glands are used to communicate with other deer. Learn more at https://www.ealt.ca/species-spotlight-list/deer
York boat important to fur trade transportation
It is not known how much timber was harvested by early settlers. We can only speculate by paying attention to the variety of uses to which timber was put. York boats, riverboats, gold dredges, ferries and barges were all built at Edmonton on the river flats.
Artist Paul Kane noted in 1846 “40 or 50 men…their employment chiefly is building boats, sawing timber, which they raft down the river from 90 miles higher.” He was fascinated by the prodigious effort needed to keep a supply of York boats.
Kane wrote they are “building the boats, about thirty feet long and six feet beam, which go as far as York Factory, and are found more convenient for carrying goods on the Saskatchewan. . .more than one-half of the boats built here never return. This system requires them to keep constantly building.”
It was a long and perilous river journey from Fort Edmonton to Hudson Bay. Some boats were lost to rough water. Most likely many boats were not sea-worthy after being subjected to the harsh winter elements at the bay. Fur-laden boats left Fort Edmonton each fall and crews could not return with the next year’s trade goods until the following late spring.
Text and information for this piece from Living in the Shed by Billie Milholland https://www.facebook.com/billie.milholland
Fundraiser for solar farm judicial review
Charles writes “As a citizen of Edmonton for fifty years I am glad to see greater awareness of our river valley, and greater use. The conflicts that come with multiple users, like the Epcor solar farm, always need to be presented to the public.
Consider something about the arts and the river valley. Paul Kane, I believe painted the valley but there is a history of artists being inspired by the valley. This time of the year the quality of light in the valley is spectacular.”
Photo by Vanessa Denman who says, “I was surprised and delighted at how crystal clear the water is and how I could see the sandbar.”
Comment or contribution
If you have a comment, concern, or question, contact us at nsrivervalley@gmail.com Please also email us river valley photos or event information. Your friends, neighbours and colleagues can sign up for this newsletter on our web site.
Sincerely yours,
Harvey Voogd
North Saskatchewan River Valley Conservation Society
780.691.1712