This is Winnipeg's Urban Forest

It's 3:30 p.m., mid-June 2014. Time to pick up my daughter from her school, a half a block from our house. Nearly there, I notice a flock of brown-black grackles in the trees, moving like fat raindrops, like jazz hands, from the elm trees to the apartment block lawn and back.

Each panel of the sidewalk between them is full of idiosyncratic illustrations. Mostly these are the remains of Day-Glo green cankerworms, but they are supplemented with pink earthworm segments and shiny black beetles making a run for it on top of white spots of grackle shit.

It should go without saying that the annual cankerworm infestation is at its peak.

Cankerworm caterpillars eat the leaves of American elm, Manitoba maple and green ash in May and June. If they're present in large enough numbers, they'll strip a tree bare in a day or two, then spin silken lines and drop to the sidewalk, looking for their next meal. It should also go without saying that the bellies of the birds that eat cankerworms - grackles and robins and sparrows - are filled to the brim with bright green goo.

So the space between the mowed lawn and the seventy-five-foot-tall elm canopy is full of wings and late afternoon raindrops, shadows and bright green worms on silk lines trying to escape the flock. There's cottonwood fluff stuffed in the cracks in the sidewalk, too, and in the lawn's five-day stubble. The gilled mushrooms that emerged today on the boulevard - half of which got stomped on this morning by school-bound children - are grey-black and the size of my thumb.

The crossing guards are singing tunelessly across the street, flapping their faded neon-orange flags, stopping traffic in both directions. They're like monks, chanting prayers they've said a hundred times. Parents in work clothes obey their instructions, picking up their children from school and hauling them home.

Nearly there, and rappelling worms have landed on my shoulders and the nape of my neck. There are wings in my peripheral vision. The air is humid, thick with spores and pollen and seeds.

People stop at the edge of the grackle squat, unsure how to navigate it. Go around? Go through? Or fail to notice altogether, causing extra ripples of movement, the swaying lines of silk slowly rotating; birds moving from the ground to the lowest branches of the trees, their tails flicking. Children drop their hats and bags, as they do, even kicking off shoes as they run through.

On the edges of all of this are just-emerged hosta fronds and grass seed and elm seedlings, grown from the pounds and pounds of seed dropped annually.

Just beyond that, there's the man with the parrots, who has a series of cages and perches on his balcony. The bright birds punctuate their ring tones and hello-ing with loud parrotty squawks as he gazes down at the street, a bemused look on his face.

And then there's the rusty-door shrieks of the merlins, nesting two doors down and rocketing through the trees.

And then there's the beautiful big elm in front of my house with its spreading branches that covers my house like a giant umbrella.

This is my experience of Winnipeg's urban forest.

When I use the words "urban forest," I mean all the trees and shrubs on public or private land within city limits.

Winnipeg also has Assiniboine Forest, which was created out of an undeveloped section of the former Town of Tuxedo in 1973, one of the twelve municipalities that were added to the City of Winnipeg in 1972 to become what was called "unicity." Many of those former cities became suburbs that then required roads and sewage systems, boulevard trees and light poles. Some people say that the unicity accelerated Winnipeg's urban sprawl, while others say that it made the delivery of municipal services more efficient.1

When it was founded, Assiniboine Forest was at the edge of a suburb on one side with the remainder surrounded by farmland, but forty-five years later, its 287 hectares of aspen parkland now have housing developments right up to its borders. That urban forest - technically a park - is part of Winnipeg's larger urban forest.

The City of Winnipeg estimates that there are approximately eight million trees in its urban forest, three million in what they call natural areas and five million on private property. In 2015, it was estimated that 299,000 of the eight million are boulevard and park trees.2 It's hard to know if that number includes shrubs, either the introduced species like lilac and caragana or natives like chokecherry and dogwood.

But it definitely includes all the riverbank trees, the trees on the boulevard, whatever you've got growing in your yard and everything on boulevards and on the 4,047 hectares of parkland the city maintains.

I said "cankerworm infestation" and I meant it. In the spring, Winnipeggers pick caterpillars from other people's shoulders instead of shaking hands when they meet in the street.

It's a part of our culture, like the urban forest, like tree banding. Half of the visitors to the city in the spring ask, "What are those strange belts on the trees?" What they are is strips of insulation four inches wide, attached to the tree midway up the trunk and spread with a thick layer of Tanglefoot, an intensely sticky substance made of resin, oil and wax. They're applied in early fall and removed in late spring. The bands are meant to catch the wingless adult female cankerworms that climb up trees so they can lay next year's eggs in the uppermost branches in the fall and the spring. If the trees are banded, the females get stuck in the Tanglefoot goo and die.

On my block, one family organizes tree banding. I know this because every year a note stapled to a bank machine envelope appears in my mailbox asking for a donation to cover the cost of banding my elm. I know this because the bands go up every year and it wasn't me that put them up.

Winnipeggers band our trees because cankerworms can eat all of an infested tree's leaves in only a few days, which causes the tree to expend energy to grow a new set of leaves. This extra energy expenditure weakens the tree, making it more susceptible to Dutch elm disease and other stressors.

In spring 2014, we had a cankerworm infestation, but, admittedly, it was pretty minor, with the City of Winnipeg reporting that their numbers were low throughout most of the city.3

Trees Winnipeg, an advocacy group formed in 1992 as the Coalition to Save the Elms, has allocated considerable resources to tree banding. In addition to their education programs, they have also provided people with supplies. In 2015, however, they announced that they would no longer be focusing on tree banding:

"Since the mid 1990's, Block Captain volunteers and neighbours have worked hard at organizing tree banding in their communities to protect our urban forest from cankerworm infestations. As a result of this city-wide effort, The City of Winnipeg reports that cankerworm populations have been consistently low over the last several years and Trees Winnipeg feels that the urgency for city-wide tree banding is reduced for the immediate future."4

According to Trees Winnipeg, though cankerworms are under control, the numbers of leaf-loving caterpillars are on the rise, including forest tent caterpillars and elm spanworms. Unfortunately, tree banding doesn't protect the trees against either of them because the female moths of both of those species have wings.5

Given the low numbers of cankerworms, Trees Winnipeg felt like it was time to redirect their resources toward new projects such as their ReLeaf program, which provides homeowners with saplings to plant on their property and workshops to make sure that they plant them properly, and preparations for the emerald ash borer, which was confirmed in Winnipeg suburb St. Boniface in 2017.

It's a weekday in September 2013. I've just finished work and my stomach is growling, but instead of heading home, I drive toward Linden Woods, a newish development in the south end of the city. There's a chill in the air, but it's still summer.

I've a date with someone I've never met to pick her chokecherries.

Tonight, I'm one of three volunteers picking Schubert chokecherries, a cultivar of the wild chokecherry that has pretty purple leaves to match its purple berries. Chokecherries are weird. Eaten straight from the tree, they have a mouth-puckering taste and texture. The only way I can describe it is to say that they're furry. But cooked down with sugar to a deep purple syrup or jam, they have a beautifully complex flavour.

After parking my dirty little Prius, I walk up to the front door and check in with the homeowner, an older woman living alone. Surveying the tidy yard, I note that there are four healthy chokecherry trees. Returning to my car, I pull out my stepladder and bins and wait for my fellow volunteers. Ten minutes later, I'm still the only picker present. I check my email and discover that the other two pickers sent messages to say that they won't be able to make it.

In the meantime, it's starting to get dark. And here I am with four trees full of fruit.

After spending a few more minutes standing under the tree with my glowing smart phone,...