Queen and Spadina, 2015

What would happen if people simply disappeared from the intersection of a large metropolis, never to return? How would this depopulation change a place that has been traversed by thousands of people each day for a century? If everything done to maintain it — the washing, paving, building, repairing — suddenly ceased, what would become of this landscape in ten years' time?

Upon initial consideration, it may seem like little would happen. An intersection such as Queen and Spadina has looked much the same for decades. Change has been incremental and relatively superficial: the repainting of a building, new streetlights, the installation of a billboard. The greater landscape of roads, sidewalks and buildings has remained constant. This infrastructure is constructed of concrete, asphalt and brick, all designed to withstand the routine stresses of traffic and weather.

Yet despite the seemingly robust construction, change occurs rapidly when there are no longer people around to "take care" of things. The most immediate and striking post-human difference is that, with the exception of the odd pop can or tattered awning blown by the wind, there is an absence of movement. An eerie quiet has descended as well, only broken by the sound of rain on asphalt or the rattle of a garbage bin knocked over by a scavenging raccoon.

Seeds blown from nearby trees and plants persist, no longer swept up or trampled upon; some find their way into a crack and, with adequate rainfall, germinate. In a week, plants are sprouting wherever light, moisture and soil are present. The flurry of growth is greatest in the squares of soil around existing street trees, and in cracks near older buildings where the soil under sidewalks is still fertile, undisturbed by development.

Within weeks, some tree saplings are a metre tall. The majority are exotic species such as tree of heaven, which are more tolerant of the harsh growing conditions. After a couple months, small mammals and birds, which had left the area when the human-supplied food disappeared, return to feed on the new seeds, flowers, and insects. Nests soon appear in trees, atop light posts, and in the crooks of windowsills.

Come fall, the trees drop their leaves, plants and grasses dry out, seeds are dispersed by wind and rain. The detritus accumulates, blocking sewers and clogging eavestroughs. Water ceases to drain freely, causing shallow pools to form along the edge of curbs and on flat roofs, providing sustenance to animals, birds, and plants.

The rise of nature parallels the steady decline of human-made structures. In a few years, roofs begin to flood, their drains blocked by leaves and nests. The rotting building materials become fertile places for seeds dropped by birds to grow. The freezing and thawing of standing water causes pavement to crack and heave, opening spaces where the roots of already-growing trees push into and thrive.

Many trees reach heights of ten metres in less than a decade, their canopies providing a cool, moist place under which younger trees and plants survive. As years pass, tall grasses growing along cracks spill over onto the flat of sidewalks, creating large mats that become habitat for additional plants, fungi, and insects.

In a decade the landscape is dramatically transformed. Indications of the past are still recognizable, but rapidly fading, undermined and outperformed by natural processes: the growth and death of plants, infestations of insects, severe weather, the changing of seasons.

If this is the extent of change after only ten years, imagine how little time it would take for roads to be completely overgrown by tall grasses, for the buildings to cave in upon their foundations and be subsumed by a reemerging forest, for most indications of our presence to disappear completely.