Trees in Monarch Park got heaps of mulch and attention Oct. 19 when tree adopters mulched the park’s youngest trees for winter while those on a tree tour wowed at the fall colours.
Stephanie Baptist, adopt-a-tree coordinator for the Friends of Monarch Park, said the 62 new trees in the park all have volunteers to look after them.
From May to October, volunteers will water the trees weekly, or as much as needed to make sure the trees survive the four or five years it takes to grow a full root system.
Just as the tree adopters were parking their spades and wheelbarrows, Jessica Piskorowski, an arborist with LEAF (Local Enhancement and Appreciation of Forests) led a tour that showed off Monarch’s surprising variety of trees.
But with fall colours peaking, Piskorowski’s first question was a perennial one – why do tree leaves change colour?
Chlorophyll is a green pigment that allows leaves to turn sunlight into energy. As trees get less daylight in fall and temperatures cool, trees produce less and less chlorophyll, she said.
That’s when “all these wonderful other pigments that were masked by the green pigments start to appear,” Piskorowski said. “But they were there the whole time.”
Carotenoids are the brightest of the underlying pigments – they come in about 60 types and are bright red, orange or yellow. The most common type, beta-carotene, is the same pigment that colours most fruits and vegetables.
Hardier than chlorophyll, carotenoids help shield tree leaves from overexposure when they face direct sun.
Another group of pigments, anthocyanins, show in trees that turn dark purple. They filter damaging ultra-violet light and give colour to cherries, beets, apples and cranberries.
Showing the brightest fall colours of all the trees in Monarch Park are the sugar maples, Piskorowski said, noting that few Toronto parks have a whole grove of them the way Monarch does.
Prized for their sugary sap, it still takes about 40 litres of maple-tree sap to make just one litre of maple sugar, she added.
Sugar maples can live 200 years and grow mostly in the Maritimes, southern Ontario and Quebec. They can reach up to 35 metres tall, and are some of the tallest trees in the park.
“Once it gets a gap in the canopy, it’s able to start shooting up, loves the sun, and grows into a very, very large tree,” Piskorowski said.
Sugar maples look much like the non-native Norway maple, Piskorowski said, but there is a quick way to tell them apart. With a less droopy angle, maple keys from the Norway variety make way better moustaches when you hold one under your nose.
Some of the less well-known trees at Monarch that Piskorowski spoke about are the northern catalpa, Kentucky Coffeetree and London Planetree.
Piskorowski said the catalpa is one of her favourites in late spring and early summer. It features clusters of white, trumpet-shaped flowers with yellow stripes and purple spots inside.
Sporting the largest leaf of any tree in Ontario, Kentucky Coffeetrees also produce long, leathery seed pods.
Early settlers used to roast their seeds as a coffee substitute, Piskorowski said, although they are mildly toxic and can harm small children or pets.
Despite their name, Kentucky Coffees are native to southwest Ontario and are becoming popular as a city street tree.
Saved for last on the tour, the London Planetree features peeling, mottled bark that looks something like military camouflage. It has a very wide canopy that casts great shade in summer.
Often confused with sycamore, Piskorowski said you can usually tell them apart because London planetrees tend to grow their seeds in pairs.
Winding up the tour, Toronto-Danforth Councillor Paula Fletcher noted the importance of Toronto’s 10 million trees, especially when the city is expected to lose some 860,000 ash trees to the emerald ash borer.
“The tree canopy in Toronto is currently around 19 per cent, and to have a really solid tree canopy for climate change it needs to be up around 30 per cent,” Fletcher said.
“Every tree that we can put in parks or your home is very important.”